Best Available Techniques (BAT) reference document for the intensive rearing of poultry or pigs : Industrial Emissions Directive 2010/75/EU (Integrated Pollution Prevention and Control).
Date: 2017-07-06
Institutions: Joint Research Centre
Subjects: animal feedingstuffs, animal nutrition, animal production, directive (EU), environmental impact, environmental policy, environmental protection, intensive livestock farming, organic fertiliser, pollution from agricultural sources, poultry, poultry farming, reduction of gas emissions, research report, swine, water pollution

Best Available Techniques (BAT) 
Reference Document for the 
Intensive Rearing of Poultry or Pigs 

Industrial Emissions Directive 
2010/75/EU 
(Integrated Pollution Prevention 
and Control)

Germán  Giner  Santonja,  Konstantinos  Georgitzikis, 
Bianca Maria Scalet, Paolo Montobbio,  
Serge Roudier, Luis Delgado Sancho 

2017 

EUR  28674  EN 

Best Available Techniques (BAT) 
Reference Document for the 
Intensive Rearing of Poultry or 
Pigs 

Industrial Emissions Directive 2010/75/EU 
Integrated Pollution Prevention and control 

Authors: 

Germán Giner Santonja
Konstantinos Georgitzikis
Bianca Maria Scalet
Paolo Montobbio
Serge Roudier
Luis Delgado Sancho

2017 

EUR  28674  EN 

This publication is a Science for Policy report by the Joint Research Centre (JRC), the European Commission’s science 
and knowledge service. It aims to provide evidence-based scientific support to the European policy-making process. 
The  scientific  output  expressed  does  not  imply  a  policy  position  of  the  European  Commission.  Neither  the  European 
Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of this 
publication. 

Contact information  
Name: European IPPC Bureau 
Address: Joint Research Centre, Edificio Expo c/ Inca Garcilaso 3, E-41092 Seville, Spain 
E-mail: JRC-IPTS-EIPPCB@ec.auropa.eu 
Tel.: +34 95 4488 284 

JRC Science Hub 
https://ec.europa.eu/jrc 

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Under the Commission Decision of 12 December 2011 on the Re-use of Commission Documents (2011/833/EU), the 
present BREF document is subject to free re-use, except for parts covered by any third-party rights which may be 
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JRC107189

EUR 28674 EN

PDF

ISBN 978-92-79-70214-3

ISSN 1831-9424

doi:10.2760/020485

Luxembourg: Publications Office of the European Union, 2017 

© European Union, 2017 

How to cite this report: Germán Giner Santonja, Konstantinos Georgitzikis, Bianca Maria Scalet, Paolo Montobbio, Serge 
Roudier,  Luis  Delgado  Sancho;  Best  Available  Techniques  (BAT)  Reference  Document  for  the  Intensive  Rearing  of 
Poultry or Pigs; EUR 28674 EN; doi:10.2760/020485

All images © European Union, 2017, except cover pictures credits, from left to right: 1. Pig nose in the pen. Focus is on
nose. Shallow depth of field.  © fotolia.com - Dusan Petkovic (www.color24.com); 2. Daily three yellow chicken at the 
poultry  farm  ©  fotolia.com  -  kharhan  (stock.adobe.com);  3.  A  group  of  entertaining  Indian  running  ducks  © 
fotolia.com - daseaford (stock.adobe.com); 4. Piglets suckling sow © fotolia.com - Budimir Jevtic (stock.adobe.com); 5. 
Grassland after mechanical slurry injection © fotolia.com - Ruud Morijn; 6. Hen house © fotolia.com - Nicole Gonzalez; 
7. Flock  of  Turkeys  in  the  farm  ranch  ©  fotolia.com  -  Tertman  (stock.adobe.com);  8.  Ammonia  emissions  from
irrigation of dilute pig slurry © Institute of 
Grassland and Environmental Research 

Title Best Available Techniques (BAT) Reference Document for the Intensive Rearing of Poultry or Pigs 

Abstract

The BAT reference document (BREF) entitled 'Intensive Rearing of Poultry or Pigs' forms part of a series presenting the 
results  of  an  exchange  of  information  between  EU  Member  States,  the  industries  concerned,  non-governmental 
organisations  promoting  environmental  protection,  and  the  Commission,  to  draw  up,  review  and,  where  necessary, 
update BAT reference documents as required by Article 13(1) of the Directive 2010/75/EU on industrial emissions. This 
document is published by the European Commission pursuant to Article 13(6) of the Directive. This BREF for Intensive 
Rearing of Poultry or Pigs concerns the activities specified in Section 6.6 of Annex I to Directive 2010/75/EU, namely 
'6.6. Intensive rearing of poultry or pigs': 

(a) with more than 40 000 places for poultry 
(b) with more than 2 000 places for production pigs (over 30 kg), or 
(c) with more than 750 places for sows. 

In particular, this document covers the following on-farm processes and activities: 
- nutritional management of poultry and pigs; 
- feed preparation (milling, mixing and storage); 
- rearing (housing) of poultry and pigs; 
- collection and storage of manure; 
- processing of manure; 
- manure landspreading; 
- storage of dead animals. 

Important  issues  for  the  implementation  of  Directive  2010/75/EU  in  the  intensive  rearing  of  poultry  or  pigs  are 
ammonia emissions to air, and total nitrogen and total phosphorus excreted. This BREF contains 10 chapters. Chapter 1 
provides  general  information  on  pig  and  poultry  production  in  Europe.  Chapter  2  describes  the  major  activities  and 
production  systems  used  in  intensive  poultry  or  pig  production.  Chapter  3  contains  information  on  the  environmental 
performance of installations in terms of current emissions, consumption of raw materials, water and energy. Chapter 4 
describes in more detail the techniques to prevent or, where this is not practicable, to reduce the environmental impact 
of operating installations in this sector that were considered in determining the BAT. This information includes, where 
relevant, the environmental performance levels (e.g. emission and consumption levels) which can be achieved by using 
the  techniques,  the  associated  monitoring  and  the  costs  and  the  cross-media  issues  associated  with  the  techniques. 
Chapter 5 presents the BAT conclusions as defined in Article 3(12) of the Directive. Chapter 6 presents information on 
'emerging  techniques'  as  defined  in  Article  3(14)  of  the  Directive.  Chapter  7  is  dedicated  to  concluding  remarks  and 
recommendations for future work. 

Printed in Ispra (Italy)

Acknowledgements 

This  report  was  produced  by  the  European  Integrated  Pollution 
Prevention  and  Control  Bureau 
the  European 
Commission's  Joint  Research  Centre  –  Directorate  B:  Growth  and 
Innovation  under  the  supervision  of  Serge  Roudier  (Head  of  the 
EIPPCB) and Luis Delgado Sancho (Head of the Circular Economy and 
Industrial Leadership Unit). 

(EIPPCB)  at 

The  authors  of  this  BREF  were  Mr  Germán  Giner  Santonja,  Mr 
Konstantinos  Georgitzikis,  Ms  Bianca  Maria  Scalet  and  Mr  Paolo 
Montobbio. 

This report was drawn up in the framework of the implementation of 
the  Industrial  Emissions  Directive  (2010/75/EU)  and  is  the  result  of 
the  exchange  of  information  provided  for  in  Article  13  of  the 
Directive. 

Major contributors of information were: 

 among  EU  Member  States:  Austria,  Belgium,  Denmark,
Finland,  France,  Germany,  Ireland,  Italy,  the  Netherlands,
Spain and the United Kingdom;

 among farmers' associations: DAFC (Danish Agriculture & Food
Council), FEFANA (EU Association of Specialty Feed Ingredients
and their Mixtures), IFA (Irish Farmers' Association), and NFU
(UK - National Farmers' Union).

Other  contributors  to  the  review  process  were  Portugal,  Poland, 
Sweden,  COPA-COGECA  (Committee  of  Professional  Agricultural 
Organisations and General Committee for Agricultural Cooperation in 
the  European  Union),  the  Danish  Committee  for  Pig  Production,  EEB 
(European  Environmental  Bureau),  IFIP  (French  Pork  and  Pig 
Institute),  ITAVI  (France  -  Technical  Institute  of  Aviculture),  KTBL 
(Germany 
in 
Agriculture), and UFU (Ulster Farmers' Union). 

for  Technology  and  Structures 

-  Association 

The whole EIPPCB team provided contributions and peer reviewing. 

This document is one from the series of foreseen documents listed below (at the time of writing, 
not all documents have been drafted): 

Best Available Techniques Reference Document 

Ceramic Manufacturing Industry 
Common Waste Water and Waste Gas Treatment/Management Systems in the Chemical 
Sector 
Common Waste Gas Treatment in the Chemical Sector 

Emissions from Storage 

Energy Efficiency 

Ferrous Metals Processing Industry 

Food, Drink and Milk Industries 

Industrial Cooling Systems 

Intensive Rearing of Poultry or Pigs 

Iron and Steel Production 

Large Combustion Plants 

Code 

CER 

CWW 

WGC 

EFS 

ENE 

FMP 

FDM 

ICS 

IRPP 

IS 

LCP 

Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 

LVIC-AAF 

Large Volume Inorganic Chemicals – Solids and Others Industry 

Large Volume Organic Chemical Industry 

Management of Tailings and Waste-rock in Mining Activities 

Manufacture of Glass 

Manufacture of Organic Fine Chemicals 

Non-ferrous Metals Industries 

Production of Cement, Lime and Magnesium Oxide 

Production of Chlor-alkali 

Production of Polymers 

Production of Pulp, Paper and Board 

Production of Speciality Inorganic Chemicals 

Production of Wood-based Panels 

Refining of Mineral Oil and Gas 

Slaughterhouses and Animals By-products Industries 

Smitheries and Foundries Industry 

Surface Treatment of Metals and Plastics 
Surface Treatment Using Organic Solvents (including Wood and Wood Products 
Preservation with Chemicals) 
Tanning of Hides and Skins 

Textiles Industry 

Waste Incineration 

Waste Treatment 

Reference Document 
Economics and Cross-media Effects 

Monitoring of Emissions to Air and Water from IED installations 

LVIC-S 

LVOC 

MTWR 

GLS 

OFC 

NFM 

CLM 

CAK 

POL 

PP 

SIC 

WBP 

REF 

SA 

SF 

STM 

STS 

TAN 

TXT 

WI 

WT 

ECM 

ROM 

Electronic  versions  of  draft  and  finalised  documents  are  publicly  available  and  can  be 
downloaded from http://eippcb.jrc.ec.europa.eu/. 

Preface 

PREFACE 

1. 

Status of this document 

Unless  otherwise  stated,  references  to  ‘the  Directive’  in  this  document  refer  to  Directive 
2010/75/EU  of  the  European  Parliament  and  the  Council  on  industrial  emissions  (integrated 
pollution prevention and control) (Recast).  

This  document  is  a  working  draft  of  the  European  IPPC  Bureau  (of  the  Commission's  Joint 
Research  Centre).  It  is  not  an  official  publication  of  the  European  Union  and  does  not 
necessarily reflect the position of the European Commission. 

2. 

Participants in the information exchange 

As  required  in  Article  13(3)  of  the  Directive,  the  Commission  has  established  a  forum  to 
promote  the  exchange  of  information,  which  is  composed  of  representatives  from  Member 
States, the industries concerned and non-governmental organisations promoting environmental 
protection  (Commission  Decision  of  16  May  2011  establishing  a  forum  for  the  exchange  of 
information  pursuant  to  Article  13  of  Directive  2010/75/EU  on  industrial  emissions  (2011/C 
146/03), OJ C 146, 17.05.2011, p. 3). 

Forum  members  have  nominated  technical  experts  constituting  the  technical  working  group 
(TWG)  that  was  the  main  source  of  information  for  drafting  this  document.  The  work  of  the 
TWG was led by the European IPPC Bureau (of the Commission's Joint Research Centre). 

3. 

Structure and contents of this document 

Chapters 1 and 2 provide general information on the intensive rearing of poultry or pigs and on 
the industrial processes and techniques used within this sector. 

Chapter  3  provides  data  and  information  concerning  the  environmental  performance  of  farms 
within  the  sector,  and  in  operation  at  the  time  of  writing,  in  terms  of  current  emissions, 
consumption  and  nature  of  raw  materials,  water  consumption,  and  use  of  energy  and  the 
generation of waste. 

Chapter 4 describes in more detail the techniques to prevent or, where this is not practicable, to 
reduce emissions from pig or poultry farms that were considered in determining the BAT. This 
information includes, where relevant, the environmental performance levels (e.g. emission and 
consumption levels) which can be achieved by using the techniques, the associated monitoring 
and the costs and the cross-media issues associated with the techniques. 

Chapter 5 presents the BAT conclusions as defined in Article 3(12) of the Directive. 

Chapter  6  presents  information  on  'emerging  techniques'  as  defined  in  Article  3(14)  of  the 
Directive. 

Concluding remarks and recommendations for future work are presented in Chapter 7. 

Intensive Rearing of Poultry or Pigs 

i 

Preface 

4. 

Information sources and the derivation of BAT 

This  document  is  based  on  information  collected  from  a  number  of  sources,  in  particular 
through  the  TWG  that  was  established  specifically  for  the  exchange  of  information  under 
Article  13  of  the  Directive.  The  information  has  been  collated  and  assessed  by  the  European 
IPPC  Bureau  (of  the  Commission's  Joint  Research  Centre)  who  led  the  work  on  determining 
BAT, guided by the principles of technical expertise, transparency and neutrality. The work of 
the TWG and all other contributors is gratefully acknowledged. 

The  BAT  conclusions  have  been  established  through  an  iterative  process  involving  the 
following steps: 

 
 
 

 

 

identification of the key environmental issues for the sector; 
examination of the techniques most relevant to address these key issues; 
identification of the best environmental performance levels, on the basis of the available 
data in the European Union and worldwide; 
examination of the conditions under which these environmental performance levels were 
achieved, such as costs, cross-media effects, and the main driving forces involved in the 
implementation of the techniques; 
selection  of  the  best  available  techniques  (BAT),  their  associated  emission  levels  (and 
other  environmental  performance  levels)  and  the  associated  monitoring  for  this  sector 
according to Article 3(10) of, and Annex III to, the Directive. 

Expert judgement by the European IPPC Bureau and the TWG has played a key role in each of 
these steps and the way in which the information is presented here. 

Where  available,  economic  data  have  been  given  together  with  the  descriptions  of  the 
techniques presented in Chapter 4. These data give a rough indication of the magnitude of the 
costs and benefits. However, the actual costs and benefits of applying a technique may depend 
strongly on the specific situation of the farm concerned, which cannot be evaluated fully in this 
document.  In  the  absence  of  data  concerning  costs,  conclusions  on  the  economic  viability  of 
techniques are drawn from observations on existing farms. 

5. 

Review of BAT reference documents (BREFs) 

BAT is a dynamic concept and so the review of BREFs is a continuing process. For example, 
new  measures  and  techniques  may  emerge,  science  and  technologies  are  continuously 
developing and new or emerging processes are being successfully introduced into the industries. 
In  order  to  reflect  such  changes  and  their  consequences  for  BAT,  this  document  will  be 
periodically reviewed and, if necessary, updated accordingly. 

6. 

Contact information  

All  comments  and  suggestions  should  be  made  to  the  European  IPPC  Bureau  at  the  Joint 
Research Centre (JRC) at the following address: 

European Commission 
JRC Directorate B – Growth and Innovation 
European IPPC Bureau 
Edificio Expo 
c/Inca Garcilaso, 3 
E-41092 Seville, Spain 
Telephone: +34 95 4488 284 
Fax: +34 95 4488 426 
E-mail: JRC-B5-EIPPCB@ec.europa.eu 
Internet: http://eippcb.jrc.ec.europa.eu 

ii 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Best Available Techniques (BAT) Reference Document for the Intensive 
Rearing of Poultry or Pigs 

PREFACE ........................................................................................................................ I 

SCOPE ..................................................................................................................... XXXI 

1  GENERAL INFORMATION ................................................................................. 1 

1.1 

1.2 

1.2.1 
1.2.2 

1.3 

1.3.1 

1.3.2 
1.3.3 

INTENSIVE LIVESTOCK FARMING .................................................................................. 1 

THE POULTRY PRODUCTION SECTOR IN EUROPE .......................................................... 5 

Egg production and consumption ........................................................................ 5 
Poultry meat production and consumption .......................................................... 8 
Alternative poultry meat production ...................................................................... 11 
Economics of the poultry sector ........................................................................ 12 
Economics of the egg production sector ................................................................ 12 
Economics of the poultry meat production sector .................................................. 15 
THE PIG PRODUCTION SECTOR IN EUROPE .................................................................. 19 

1.2.2.1 

1.2.3 

1.2.3.1 
1.2.3.2 

Structure, trends and geographical distribution of the pig production sector in 
Europe ............................................................................................................... 19 
Production and consumption of pork ................................................................ 22 
Economics of the pig sector .............................................................................. 25 

1.4 

ENVIRONMENTAL ISSUES OF INTENSIVE POULTRY OR PIG FARMING .......................... 30 

1.4.1 
1.4.2 
1.4.3 

Emissions to air ................................................................................................. 32 
Emissions to soil and water ............................................................................... 37 
Other emissions ................................................................................................. 39 

2  APPLIED PROCESSES AND TECHNIQUES .................................................. 41 

2.1 

2.2 

INTRODUCTION ........................................................................................................... 41 

POULTRY PRODUCTION ............................................................................................... 43 

2.2.1 

2.2.1.1 
2.2.1.2 

2.2.1.2.1 
2.2.1.2.2 
2.2.1.2.3 

2.2.1.3 

2.2.2 
2.2.3 

2.2.3.1 
2.2.3.2 
2.2.3.3 
2.2.3.4 

2.2.4 

2.2.4.1 
2.2.4.2 
2.2.4.3 
2.2.4.4 
2.2.4.5 
2.2.4.6 

Production of eggs ............................................................................................. 43 
Cage systems for laying hens ................................................................................. 44 
Non-cage systems for laying hens .......................................................................... 46 
Deep litter system ........................................................................................... 47 
Aviary system ................................................................................................. 48 
Additional structures for non-cage housing .................................................... 50 
Pullet rearing .......................................................................................................... 51 
Production of broiler meat ................................................................................. 51 
Other poultry production sectors ....................................................................... 53 
Rearing of broiler breeders ..................................................................................... 53 
Production of turkeys ............................................................................................. 53 
Production of ducks ................................................................................................ 54 
Production of guinea fowl ...................................................................................... 55 
Control of poultry indoor environment ............................................................. 56 
Temperature control ............................................................................................... 56 
Ventilation of poultry housing ............................................................................... 58 
Water fogging ........................................................................................................ 59 
Pad cooling ............................................................................................................. 60 
Lighting of poultry housing.................................................................................... 60 
Control of dust ....................................................................................................... 61 

Intensive Rearing of Poultry or Pigs 

iii 

2.2.5 

2.2.5.1 
2.2.5.2 
2.2.5.3 

Poultry feed and drink supply ............................................................................ 62 
Poultry feed formulation ......................................................................................... 62 
Feeding systems ...................................................................................................... 64 
Drinking water supply systems ............................................................................... 65 
PIG PRODUCTION ......................................................................................................... 67 

2.3 

2.3.1 

2.3.1.1 

Pig housing and manure collection .................................................................... 67 
Housing systems for mating and gestating sows .................................................... 71 

2.3.1.2 

2.3.1.3 
2.3.1.4 

2.3.1.1.1 

2.3.1.2.1 
2.3.1.2.2 

2.3.1.1.2 
2.3.1.1.3 
2.3.1.1.4 

2.3.1.4.1 
2.3.1.4.2 
2.3.1.4.3 

Individual housing with a fully or partly slatted floor for mating and 
gestating sows ................................................................................................. 72 
Sow crates with a solid floor for mating and gestating sows .......................... 74 
Group housing with or without straw for mating and gestating sows ............. 75 
Group housing with electronic feeders ........................................................... 77 
Housing systems for farrowing sows ...................................................................... 78 
Housing for farrowing sows with confined movement ................................... 79 
Housing of farrowing sows allowing sow movement ..................................... 80 
Housing systems for weaners ................................................................................. 81 
Housing of fattening pigs ........................................................................................ 83 
Housing of fattening pigs on a fully slatted floor ........................................... 84 
Housing of fattening pigs on a partly slatted floor .......................................... 84 
Housing of fattening pigs on a solid concrete floor and straw ........................ 86 
Control of indoor environment in pig housing systems ..................................... 88 
Heating of pig housing ............................................................................................ 90 
Ventilation of pig housing ...................................................................................... 91 
Lighting of pig housing .......................................................................................... 97 
Water fogging ......................................................................................................... 97 
Pig feed and drink supply .................................................................................. 97 
Pig feed formulation ............................................................................................... 97 
Feeding systems ...................................................................................................... 99 
Drinking water supply systems ............................................................................. 101 
END-OF-PIPE TECHNIQUES FOR AIR CLEANING.......................................................... 103 

2.3.2.1 
2.3.2.2 
2.3.2.3 
2.3.2.4 

2.3.3.1 
2.3.3.2 
2.3.3.3 

2.3.2 

2.3.3 

Wet scrubbers .................................................................................................. 103 
Biofilters .......................................................................................................... 104 

PROCESSING AND STORAGE OF ANIMAL FEED ........................................................... 105 

COLLECTION AND STORAGE OF MANURE .................................................................. 106 

General requirements ....................................................................................... 106 
Poultry manure ................................................................................................. 110 
Pig manure ....................................................................................................... 111 
Storage systems for solid manure .................................................................... 112 
Storage systems for slurry ................................................................................ 114 
Slurry storage in tanks .......................................................................................... 114 
Slurry storage in earth-banked stores (or lagoons) ............................................... 116 
Other types of slurry storage ................................................................................. 117 
ON-FARM MANURE PROCESSING ............................................................................... 118 

2.6.5.1 
2.6.5.2 
2.6.5.3 

Mechanical separators ...................................................................................... 120 
Aerobic digestion (aeration) of liquid manure ................................................. 121 
Composting of solid manure ............................................................................ 122 
Anaerobic digestion of manure in a biogas installation ................................... 123 
Anaerobic lagoon system ................................................................................. 124 

Intensive Rearing of Poultry or Pigs 

2.4 

2.4.1 
2.4.2 

2.5 

2.6 

2.6.1 
2.6.2 
2.6.3 
2.6.4 
2.6.5 

2.7 

2.7.1 
2.7.2 
2.7.3 
2.7.4 
2.7.5 

iv 

 
2.7.6 
2.7.7 

Manure additives ............................................................................................. 124 
Slurry acidification .......................................................................................... 126 

2.8  MANURE LANDSPREADING TECHNIQUES .................................................................. 127 

2.8.1 
2.8.2 

2.8.2.1 
2.8.2.2 
2.8.2.3 
2.8.2.4 
2.8.2.5 
2.8.2.6 
2.8.2.7 

2.8.3 
2.8.4 

Slurry transport systems .................................................................................. 129 
Slurry landspreading systems .......................................................................... 130 
Broadcast spreader ............................................................................................... 130 
Irrigators ............................................................................................................... 132 
Low-pressure irrigator .......................................................................................... 133 
Band spreader (or trailing hose) ........................................................................... 133 
Trailing shoe spreader .......................................................................................... 134 
Injector (open slot) ............................................................................................... 134 
Injector (closed slot) ............................................................................................. 135 
Solid manure landspreading systems .............................................................. 136 
Incorporation ................................................................................................... 138 

2.9 

ON-FARM TRANSPORT .............................................................................................. 140 

2.10  MAINTENANCE AND CLEANING ................................................................................ 141 

2.11  USE AND DISPOSAL OF RESIDUES .............................................................................. 142 

2.12 

STORAGE AND DISPOSAL OF DEAD ANIMALS ............................................................ 143 

2.13 

2.14 

TREATMENT OF WASTE WATER ................................................................................ 144 

INSTALLATIONS FOR HEAT AND POWER PRODUCTION AND ENERGY RECOVERY ..... 145 

2.14.1 
2.14.2 
2.14.3 
2.14.4 
2.14.5 

Renewable energy production ......................................................................... 145 
Heat recovery by heat exchangers ................................................................... 145 
Heat pumps ...................................................................................................... 146 
Biogas energy production ................................................................................ 146 
Energy production from biomass .................................................................... 147 

2.15  MONITORING OF EMISSIONS AND CONTROL OF PROCESS PARAMETERS ................... 148 

3  CURRENT CONSUMPTION AND EMISSION LEVELS OF INTENSIVE 

POULTRY OR PIG FARMS .............................................................................. 149 

3.1 

3.2 

INTRODUCTION ......................................................................................................... 149 

CONSUMPTION LEVELS ............................................................................................. 151 

3.2.1 

3.2.1.1 
3.2.1.2 

3.2.2 

3.2.2.1 

3.2.2.2 

3.2.2.1.1 
3.2.2.1.2 
3.2.2.1.3 

3.2.2.2.1 
3.2.2.2.2 
3.2.2.2.3 
3.2.2.2.4 

3.2.3 

3.2.3.1 
3.2.3.2 

Feed consumption and nutritional levels ......................................................... 151 
Poultry feeding ..................................................................................................... 151 
Pig feeding ........................................................................................................... 153 
Water consumption ......................................................................................... 156 
Water requirements of poultry farms ................................................................... 156 
Birds' water consumption ............................................................................. 156 
Use of cleaning water ................................................................................... 157 
Use of cooling water .................................................................................... 157 
Water requirements of pig farms .......................................................................... 158 
Animals' water consumption ........................................................................ 158 
Use of cleaning water ................................................................................... 160 
Use of cooling water .................................................................................... 161 
Use of water for air cleaning systems ........................................................... 161 
Energy consumption ........................................................................................ 161 
Poultry farms ........................................................................................................ 161 
Pig farms .............................................................................................................. 164 

Intensive Rearing of Poultry or Pigs 

v 

3.2.4 

3.2.4.1 
3.2.4.2 

Other inputs ..................................................................................................... 168 
Bedding (litter) ..................................................................................................... 168 
Cleaning material .................................................................................................. 169 
EXCRETION AND EMISSION LEVELS ........................................................................... 170 

3.3 

3.3.1 

3.3.1.1 
3.3.1.2 

3.3.2 

3.3.2.1 
3.3.2.2 

3.3.3 

3.3.3.1 
3.3.3.2 

3.3.4 
3.3.5 

3.3.5.1 
3.3.5.2 
3.3.5.3 

3.3.6 

3.3.6.1 
3.3.6.2 

3.3.7 

3.3.7.1 
3.3.7.2 

3.3.8 
3.3.9 

Excretion of nutrients and manure generation ................................................. 170 
Levels of excretion and characteristics of poultry manure ................................... 171 
Levels of excretion and characteristics of pig manure .......................................... 174 
Emissions from housing systems ..................................................................... 180 
Emissions from poultry housing ........................................................................... 182 
Emissions from pig housing ................................................................................. 185 
Emissions from manure storage facilities ........................................................ 188 
Emissions from solid manure storage ................................................................... 189 
Emissions from slurry storage .............................................................................. 191 
Emissions from manure processing ................................................................. 193 
Emissions from landspreading ......................................................................... 193 
Emissions to air .................................................................................................... 194 
Emissions to soil and water .................................................................................. 197 
Emissions of metals .............................................................................................. 199 
Emissions from the whole farm ....................................................................... 200 
Emissions from the whole-farm process chain for the rearing of poultry ............. 200 
Emissions from the whole-farm process chain for the rearing of pigs .................. 202 
Noise ................................................................................................................ 203 
Sources and emissions on poultry farms ............................................................... 204 
Sources and emissions on pig farms ..................................................................... 204 
Solid waste from poultry and pig farms ........................................................... 205 
Emissions of odour .......................................................................................... 205 

4  TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT ..... 207 

4.1 

GOOD AGRICULTURAL PRACTICE FOR ENVIRONMENTAL MANAGEMENT ................. 209 

4.1.1 

Storage and disposal of dead animals .............................................................. 212 

4.2 

4.3 

4.3.1 
4.3.2 

ENVIRONMENTAL MANAGEMENT SYSTEMS .............................................................. 215 

NUTRITIONAL MANAGEMENT .................................................................................... 218 

Nutritional measures ........................................................................................ 218 
Multiphase feeding .......................................................................................... 225 
Poultry .................................................................................................................. 225 
Pigs ....................................................................................................................... 227 
Low-protein, amino-acid-supplemented diets ................................................. 231 
Addition of phytase to achieve phosphorus-balanced diets for poultry and 
pigs ................................................................................................................... 243 
Highly digestible inorganic feed phosphates ................................................... 246 
Other feed additives ......................................................................................... 248 
Benzoic acid ......................................................................................................... 249 
Probiotics .............................................................................................................. 252 
Enzymes................................................................................................................ 254 
Phytogenic feed additives ..................................................................................... 257 
TECHNIQUES FOR THE EFFICIENT USE OF WATER ...................................................... 259 

4.3.2.1 
4.3.2.2 

4.3.3 
4.3.4 

4.3.5 
4.3.6 

4.3.6.1 
4.3.6.2 
4.3.6.3 
4.3.6.4 

TECHNIQUES FOR THE EFFICIENT USE OF ENERGY .................................................... 263 

4.5.1 

Introduction ...................................................................................................... 263 

vi 

Intensive Rearing of Poultry or Pigs 

4.4 

4.5 

 
4.5.2.1.1 

4.5.1.1 
4.5.1.2 

4.5.2 

4.5.2.1 

4.5.2.2 

4.5.3 

4.5.3.1 
4.5.3.2 

4.5.4 

4.5.4.1 

4.5.4.1.1 

4.5.4.1.2 
4.5.4.1.3 
4.5.4.1.4 

4.5.4.2 

4.5.4.2.1 

4.5.4.2.1.1 
4.5.4.2.1.2 
4.5.4.2.1.3 
4.5.4.2.1.4 

4.5.4.2.2 
4.5.4.2.3 

General energy-saving measures .......................................................................... 264 
Energy management approach ............................................................................. 264 
Insulation ......................................................................................................... 266 
Insulation in poultry housing ................................................................................ 267 
Heat-reflecting membranes .......................................................................... 269 
Insulation in pig housing ...................................................................................... 270 
Low-energy lighting ........................................................................................ 272 
Lighting in poultry housing .................................................................................. 274 
Lighting in pig housing ........................................................................................ 275 

Optimisation of heating/cooling and ventilation systems and management in 
poultry and pig farms ...................................................................................... 276 
Efficient use of energy for heating ....................................................................... 276 

General measures for the efficient use of energy for heating in poultry 
farms ............................................................................................................. 276 
General measures for the efficient use of energy for heating in pig farms ... 277 
Gas-fired infrared heaters and air blowers ................................................... 278 
Wood- and biomass-fired boilers ................................................................. 279 
Efficient use of energy for ventilation .................................................................. 282 
Management of ventilation in poultry houses .............................................. 282 
Circulating fans ................................................................................... 282 
Circulating fans in combination with heat exchangers ........................ 283 
Equal spreading of recirculated air by indoor fans and heaters ........... 284 
Energy-saving fans .............................................................................. 284 
Management of ventilation in pig houses ..................................................... 285 
Use of high-efficiency ventilation systems .................................................. 288 
Heat recovery .................................................................................................. 289 
Heat exchangers ................................................................................................... 289 
Heat pumps for heat recovery .............................................................................. 293 
Heat recovery in broiler housing with heated and cooled littered floor 
(combideck system) ............................................................................................. 295 
Natural ventilation ........................................................................................... 298 

4.6 

TECHNIQUES FOR THE REDUCTION OF EMISSIONS FROM POULTRY HOUSES ............. 301 

Techniques for cage housing of laying hens ................................................... 301 
Enriched cages ..................................................................................................... 303 
Small groups in enriched cages ............................................................................ 306 
Techniques for non-cage housing of laying hens ............................................ 307 
Deep litter or floor regime systems ...................................................................... 310 
Forced ventilation system and infrequent manure removal (in case of deep 
litter with a manure pit) ................................................................................ 310 
Manure belt or scraper (in case of deep litter with a manure pit) ................. 311 
Forced air drying of manure via tubes (in case of deep litter with a manure 
pit) ................................................................................................................ 314 
Forced air drying of manure using perforated floor (in case of deep litter 
with a manure pit) ........................................................................................ 315 
Manure belts (in case of aviary) ........................................................................... 317 
Manure belts (in case of aviary), with or without a veranda and free-range 
system ........................................................................................................... 317 
Underfloor manure drying (in case of aviary) .............................................. 322 

4.6.2.1.1 

4.6.2.1.2 
4.6.2.1.3 

4.6.2.1.4 

4.6.2.2 

4.6.2.2.1 

4.6.2.2.2 

4.6.2.3 

4.6.3 

4.6.3.1 

Forced air drying of litter using indoor air (in case of solid floor with deep 
litter) ..................................................................................................................... 323 
Techniques for housing of pullets ................................................................... 324 
Group cage with manure belts and forced manure drying .................................... 326 

Intensive Rearing of Poultry or Pigs 

vii 

4.5.5 

4.5.5.1 
4.5.5.2 
4.5.5.3 

4.5.6 

4.6.1 

4.6.1.1 
4.6.1.2 

4.6.2 

4.6.2.1 

4.6.4.2.1 
4.6.4.2.2 
4.6.4.2.3 

4.6.3.2 
4.6.3.3 
4.6.3.4 

4.6.4 

4.6.4.1 

4.6.4.2 

4.6.4.3 
4.6.4.4 
4.6.4.5 

4.6.4.6 

4.6.5 

4.6.5.1 
4.6.5.2 
4.6.5.3 
4.6.5.4 

4.6.5.5 
4.6.5.6 

4.6.6 

4.6.6.1 

4.6.6.2 

4.6.7 

4.6.7.1 
4.6.7.2 
4.6.7.3 

Small groups in enriched cages ............................................................................ 326 
Aviaries ................................................................................................................. 327 
Deep litter with or without a manure pit ............................................................... 329 
Techniques for housing of broilers .................................................................. 330 

Natural or forced ventilation with a non-leaking drinking system (in case of 
solid floor with deep litter) ................................................................................... 333 
Forced drying system of litter using indoor air (in case of solid floor with deep 
litter) ..................................................................................................................... 336 
Litter-based systems with circulating fans .................................................... 336 
Litter-based systems with circulating fans and a heat exchanger ................. 338 
Litter-based systems with air recirculated (equally spread) by indoor fans 
and heaters .................................................................................................... 340 
Perforated floor with a forced air drying system .................................................. 342 
Litter on manure belt and forced air drying (in case of tiered floor systems) ....... 344 
Separate hatching and growing of broiler chicks for a limited time (in case of 
tiered floor systems) ............................................................................................. 346 
Heated and cooled littered floor (combideck system)........................................... 348 
Techniques for housing of broiler breeders ..................................................... 348 
Manure removal by belts, forced manure drying (in case of cage systems) ......... 349 
Manure belt or scraper (in case of deep litter with a manure pit) ......................... 350 
Forced air drying of manure via tubes (in case of deep litter with a manure pit) . 351 
Forced air drying of manure using perforated floor (in case of deep litter with a 
manure pit) ............................................................................................................ 353 
Litter-based systems with circulating fans ............................................................ 354 
Manure belts (in case of aviary) ........................................................................... 355 
Techniques for housing of turkeys ................................................................... 356 

4.7 

4.7.1 

4.7.1.1 

4.7.1.1.1 

Forced ventilation and a non-leaking drinking system (in case of solid floor 
with deep litter) ..................................................................................................... 356 
Natural ventilation with a non-leaking drinking system (in case of solid floor 
with deep litter) ..................................................................................................... 358 
Techniques for housing of ducks ..................................................................... 360 
Frequent litter addition (in case of solid floor with deep litter) ............................ 360 
Frequent litter addition (in case of deep litter combined with slatted floor) ......... 362 
Frequent manure removal (in case of fully slatted floor) ...................................... 363 
TECHNIQUES FOR THE REDUCTION OF EMISSIONS FROM PIG HOUSES ....................... 365 

Common housing systems for various categories of pigs ................................ 369 
Deep pit (in case of a fully slatted floor) .............................................................. 369 
Deep pit (in case of a partly slatted floor) ..................................................... 370 
Vacuum system for frequent slurry removal (in case of a fully slatted floor) ...... 372 
Vacuum system for frequent slurry removal (in case of a partly slatted floor) ..... 374 
Slanted walls in the manure channel (in case of a fully or partly slatted floor) .... 376 
Scraper for frequent manure removal (in case of a partly or fully slatted floor) ... 376 
Convex floor and separated manure and water channels (in case of partly 
slatted pens) .......................................................................................................... 378 
Slurry cooling channels ........................................................................................ 379 
Slurry surface cooling fins .................................................................................... 380 
Frequent slurry removal by flushing (in case of a fully or partly slatted floor) .... 383 
Kennel or hut housing (in case of a partly slatted floor) ....................................... 386 
Housing systems for mating and gestating sows ............................................. 387 
Deep pit (in case of a fully or partly slatted floor) ................................................ 390 
Vacuum system for frequent slurry removal (in case of a fully slatted floor) ...... 391 
Vacuum system for frequent slurry removal (in case of a partly slatted floor) ..... 391 
Slanted walls in the manure channel (in case of a fully or partly slatted floor) .... 392 

4.7.1.2 
4.7.1.3 
4.7.1.4 
4.7.1.5 
4.7.1.6 

4.7.1.7 
4.7.1.8 
4.7.1.9 
4.7.1.10 

4.7.2 

4.7.2.1 
4.7.2.2 
4.7.2.3 
4.7.2.4 

viii 

Intensive Rearing of Poultry or Pigs 

 
4.7.2.5 
4.7.2.6 
4.7.2.7 
4.7.2.8 
4.7.2.9 
4.7.2.10 
4.7.2.11 

4.7.3 

4.7.3.1 

Scraper for frequent slurry removal (in case of a fully or partly slatted floor) ..... 395 
Frequent slurry removal by flushing (in case of a fully or partly slatted floor).... 395 
Reduced manure pit (in case of a partly slatted floor) .......................................... 397 
Kennel or hut housing (in case of a partly slatted floor) ...................................... 400 
Slurry cooling ....................................................................................................... 402 
Full litter system (in case of a solid concrete floor) ............................................. 403 
Feeding/lying boxes on a solid floor (in case of litter-based pens) ...................... 407 
Housing systems for farrowing sows .............................................................. 409 
Deep pit (in case of a fully or partly slatted floor) ............................................... 411 
Reduced manure pit (in case of a partly slatted floor) .................................. 413 

4.7.3.1.1 

4.7.3.2 

4.7.3.3 
4.7.3.4 
4.7.3.5 
4.7.3.6 
4.7.3.7 
4.7.3.8 
4.7.3.9 

4.7.4 

4.7.4.1 
4.7.4.2 
4.7.4.3 
4.7.4.4 
4.7.4.5 
4.7.4.6 
4.7.4.7 
4.7.4.8 
4.7.4.9 

4.7.4.10 
4.7.4.11 
4.7.4.12 

4.7.4.13 
4.7.4.14 

4.7.5 

4.7.5.1 
4.7.5.2 
4.7.5.3 
4.7.5.4 
4.7.5.5 
4.7.5.6 
4.7.5.7 
4.7.5.8 
4.7.5.9 
4.7.5.10 

4.7.5.11 
4.7.5.12 
4.7.5.13 
4.7.5.14 
4.7.5.15 

Vacuum system for frequent slurry removal (in case of a fully or partly slatted 
floor) .................................................................................................................... 414 
Slanted walls in the manure channel (in case of a fully or partly slatted floor) ... 414 
Scraper for frequent slurry removal (in case of a fully or partly slatted floor) ..... 414 
Frequent slurry removal by flushing (in case of a fully or partly slatted floor).... 415 
Slurry cooling ....................................................................................................... 416 
A combination of water and manure channels (in case of a fully slatted floor) ... 417 
Manure pan (in case of a fully or partly slatted floor) .......................................... 420 
Littered pens with combined manure generation (slurry and solid manure) ........ 422 
Housing systems for weaners .......................................................................... 423 
Deep pit (in case of a fully or partly slatted floor) ............................................... 426 
Vacuum system for frequent slurry removal (in case of fully slatted floor) ......... 427 
Vacuum system for frequent slurry removal (in case of partly slatted floor) ....... 427 
Slanted walls in the manure channel (in case of a fully or partly slatted floor) ... 428 
Scraper for frequent slurry removal (in case of fully or partly slatted floor) ....... 429 
Frequent slurry removal by flushing (in case of a fully or partly slatted floor).... 430 
Kennel or hut housing (in case of a partly slatted floor) ...................................... 431 
Straw flow housing system (in case of a solid concrete floor) ............................. 433 
Convex floor and separated manure and water channels (in case of partly 
slatted pens) .......................................................................................................... 433 
Slurry cooling ....................................................................................................... 435 
Pens for weaning pigs with partly slatted floor .................................................... 436 
Pens or flat decks with a fully slatted floor and a concrete sloped underground 
floor to separate faeces and urine ......................................................................... 438 
Manure collection in water ................................................................................... 439 
Full litter system (in case of solid concrete floor) ................................................ 441 
Housing systems for growing and finishing pigs (fattening pigs) ................... 445 
Deep pit (in case of a fully or partly slatted floor) ............................................... 449 
Vacuum system for frequent slurry removal (in case of a fully slatted floor) ...... 452 
Vacuum system for frequent slurry removal (in case of a partly slatted floor) .... 453 
Fully or partly slatted floor with slanted walls in the manure channel ................. 454 
Scraper for frequent slurry removal (in case of a fully or partly slatted floor) ..... 455 
Frequent slurry removal by flushing (in case of a fully or partly slatted floor).... 456 
Reduced manure pit (in case of a partly slatted floor) .......................................... 458 
Kennel or hut housing (in case of partly slatted floor) ......................................... 459 
Straw flow system (in case of a solid concrete floor)........................................... 461 
Partly slatted pens with a convex floor and separated manure and water 
channels ................................................................................................................ 463 
Manure collection in water ................................................................................... 465 
Slurry cooling ....................................................................................................... 465 
Full litter system (in case of a solid concrete floor) ............................................. 468 
Littered external alley (in case of a solid concrete floor) ..................................... 474 
V-shaped manure belts (in case of a partly slatted floor) ..................................... 475 

Intensive Rearing of Poultry or Pigs 

ix 

4.8 

TECHNIQUES FOR THE REDUCTION OF EMISSIONS TO AIR WITHIN HOUSING ............. 478 

4.8.1 
4.8.2 
4.8.3 

4.8.3.1 

4.8.4 
4.8.5 
4.8.6 

Introduction ...................................................................................................... 478 
Ionisation ......................................................................................................... 478 
Water fogging .................................................................................................. 480 
Misting of capturing and reactive agents .............................................................. 482 
Oil spraying ..................................................................................................... 484 
Floating balls in slurry channels ...................................................................... 486 
Biological additives in poultry litter ................................................................ 487 

4.9 

END-OF-PIPE MEASURES FOR THE REDUCTION OF EMISSIONS TO AIR FROM 
HOUSING .................................................................................................................... 489 

4.9.1 
4.9.2 
4.9.3 
4.9.4 
4.9.5 
4.9.6 

4.9.6.1 
4.9.6.2 

4.9.7 
4.9.8 
4.9.9 

Introduction ...................................................................................................... 489 
Water scrubber ................................................................................................. 492 
Bioscrubber (or biotrickling filter)................................................................... 493 
Wet acid scrubber ............................................................................................ 501 
Biofilter ............................................................................................................ 507 
Multi-stage scrubber ........................................................................................ 509 
Two-stage scrubber: wet acid scrubber combined with bioscrubber .................... 509 
Three-stage scrubber: water scrubber combined with wet chemical scrubber and 
biofilter ................................................................................................................. 513 
Partial air treatment in air cleaning systems .................................................... 518 
Dry filters ......................................................................................................... 519 
Water trap ........................................................................................................ 521 

4.10 

TECHNIQUES FOR THE REDUCTION OF ODOUR EMISSIONS ........................................ 522 

4.10.1 

4.10.1.1 
4.10.1.2 
4.10.1.3 
4.10.1.4 
4.10.1.5 

4.10.2 
4.10.3 
4.10.4 
4.10.5 
4.10.6 

General measures for odour prevention ........................................................... 522 
Dilution of odorants .............................................................................................. 522 
Discharge conditions ............................................................................................ 523 
Dietary effects ....................................................................................................... 525 
Air cleaning systems ............................................................................................. 526 
Odour management plan ....................................................................................... 526 
Good operational practice in pig housing ........................................................ 528 
Good operational practice in poultry housing .................................................. 529 
Slurry storage ................................................................................................... 529 
Manure processing ........................................................................................... 530 
Landspreading .................................................................................................. 530 

4.11 

TECHNIQUES FOR THE REDUCTION OF EMISSIONS FROM MANURE STORAGE ............ 531 

4.11.1 

4.11.1.1 
4.11.1.2 
4.11.1.3 
4.11.1.4 

4.11.2 

4.11.2.1 
4.11.2.2 
4.11.2.3 
4.11.2.4 
4.11.2.5 
4.11.2.6 

Reduction of emissions from storage of solid manure ..................................... 531 
General practice for the batch storage of solid manure in the field ...................... 531 
Application of a covering to solid manure heaps .................................................. 533 
Storage of dried solid manure in a barn ................................................................ 536 
Concrete silo for solid manure storage ................................................................. 537 
Reduction of emissions from the storage of slurry .......................................... 539 
General aspects ..................................................................................................... 539 
Application of a rigid cover to slurry stores ......................................................... 542 
Application of a flexible cover to slurry stores ..................................................... 546 
Application of a floating cover to slurry stores..................................................... 548 
Application of covers to earth-banked slurry stores (lagoons) ............................. 557 
Techniques to protect soil and water against emissions from slurry storage ........ 560 

x 

Intensive Rearing of Poultry or Pigs 

 
4.11.2.6.1 

Storage tank construction and auxiliary equipment for slurry collection 
and transfer ................................................................................................... 560 
Measures to prevent and inspect leakage from slurry stores ........................ 562 
4.11.2.6.2 
4.11.2.6.3 
Impermeable lining for earth-banked slurry lagoons .................................... 565 
TECHNIQUES FOR THE ON-FARM PROCESSING OF MANURE ...................................... 566 

4.12 

4.12.3 

4.12.4 

4.12.3.1 

4.12.3.2 

4.12.3.1.1 

4.12.1 
4.12.2 

4.12.2.1 
4.12.2.2 
4.12.2.3 
4.12.2.4 
4.12.2.5 
4.12.2.6 

Introduction ..................................................................................................... 566 
Mechanical separation of slurry ...................................................................... 570 
Introduction .......................................................................................................... 570 
Screw press separator ........................................................................................... 574 
Decanter-centrifuge separator .............................................................................. 576 
Coagulation-flocculation ...................................................................................... 578 
Sieve separation ................................................................................................... 580 
Filter presses ........................................................................................................ 582 
Biological treatment of slurry ......................................................................... 584 
Aerobic digestion (aeration) of slurry .................................................................. 584 
Aerobic biological manure processing in a serial tank configuration........... 586 
Nitrification-denitrification of slurry .................................................................... 587 
Composting of solid manure ........................................................................... 591 
Composting .......................................................................................................... 591 
Co-composting of poultry manure with green residues ........................................ 597 
Composting of poultry manure with a biological inoculum ................................. 599 
Anaerobic digestion of manure in a biogas installation .................................. 600 
4.12.5 
Anaerobic lagoon system ................................................................................ 606 
4.12.6 
Evaporation and thermal drying of manure ..................................................... 608 
4.12.7 
External tunnel for manure drying .................................................................. 610 
4.12.8 
Slurry acidification .......................................................................................... 613 
4.12.9 
4.12.10 
Combustion of poultry litter for energy recovery ........................................... 618 
4.12.11  Ammonia stripping .......................................................................................... 622 
4.12.12  Manure additives ............................................................................................. 624 
Slurry and wet manure belt dryer .................................................................... 629 
4.12.13 

4.12.4.1 
4.12.4.2 
4.12.4.3 

4.13 

TECHNIQUES FOR THE REDUCTION OF EMISSIONS FROM MANURE LANDSPREADING 632 

4.13.1 

4.13.1.1 

4.13.2 
4.13.3 
4.13.4 

4.13.4.1 
4.13.4.2 

4.13.4.2.1 
4.13.4.2.2 
4.13.4.2.3 

4.13.4.3 
4.13.4.4 
4.13.4.5 

4.13.5 

Balancing the spreading of manure with the available land and soil/crop 
requirements .................................................................................................... 633 
Phosphorus fertilisation norms ............................................................................. 636 
Groundwater protection schemes .................................................................... 636 
Manure landspreading management practices ................................................ 637 
Manure application systems ............................................................................ 641 
Use of low-emission manure (solid or liquid) application techniques ................. 641 
Slurry dilution ...................................................................................................... 648 
Low-pressure water irrigation systems ......................................................... 648 
Pulse-jet irrigator .......................................................................................... 650 
Landspreading of diluted slurry using drip lines .......................................... 652 
Band spreader (or trailing hoses) and trailing shoes............................................. 653 
Shallow injector (open slot) ................................................................................. 657 
Deep injector (closed slot).................................................................................... 660 
Incorporation of solid manure or slurry .......................................................... 663 

4.14 

TECHNIQUES TO REDUCE NOISE EMISSIONS .............................................................. 670 

Intensive Rearing of Poultry or Pigs 

xi 

4.15 

TECHNIQUES FOR THE TREATMENT AND DISPOSAL OF RESIDUES OTHER THAN 
MANURE AND DEAD ANIMALS ................................................................................... 676 

4.15.1 
4.15.2 

4.15.2.1 
4.15.2.2 
4.15.2.3 

Solid residues ................................................................................................... 676 
Generation, segregation and treatment of liquid residues ................................ 677 
Segregation, collection and prevention of waste water generation ....................... 677 
Treatment of waste water ...................................................................................... 679 
Landspreading of waste water by using an irrigation system ............................... 684 

4.16  OPTIMISATION OF THE WHOLE-FARM ENVIRONMENTAL IMPACT – ADOPTION OF 

AN INTEGRATED APPROACH ...................................................................................... 686 

4.17 

TECHNIQUES FOR THE REDUCTION OF DUST EMISSIONS ........................................... 691 

4.17.1 
4.17.2 
4.17.3 

Techniques to reduce dust generation inside livestock buildings .................... 691 
Techniques to reduce the dust concentration inside animal houses ................. 693 
Air cleaning systems ........................................................................................ 693 

4.18  MONITORING ............................................................................................................. 694 

4.18.1 

4.18.1.1 
4.18.1.2 

4.18.2 

4.18.2.1 
4.18.2.2 
4.18.2.3 

4.18.3 
4.18.4 
4.18.5 
4.18.6 

4.18.6.1 
4.18.6.2 

4.18.7 
4.18.8 

Excretion of nitrogen and phosphorus ............................................................. 694 
Mass balance ......................................................................................................... 694 
Manure analysis .................................................................................................... 695 
Ammonia emissions ......................................................................................... 696 
Mass balance ......................................................................................................... 696 
Ammonia emission measurements ....................................................................... 698 
Emission factors ................................................................................................... 700 
Ventilation rate ................................................................................................ 700 
Odour emissions .............................................................................................. 701 
Dust emissions ................................................................................................. 702 
Air cleaning systems ........................................................................................ 702 
Verification of air cleaning systems ..................................................................... 703 
Monitoring of process parameters of air cleaning systems ................................... 703 
Emissions to water ........................................................................................... 705 
Process parameters ........................................................................................... 705 

5  BAT CONCLUSIONS ......................................................................................... 707 

SCOPE  ................................................................................................................................... 707 

DEFINITIONS ....................................................................................................................... 708 

GENERAL CONSIDERATIONS ......................................................................................... 710 

5.1 

GENERAL BAT CONCLUSIONS .................................................................................. 711 

5.1.1 
5.1.2 
5.1.3 
5.1.4 
5.1.5 
5.1.6 
5.1.7 
5.1.8 
5.1.9 
5.1.10 
5.1.11 

Environmental management systems (EMS) ................................................... 711 
Good housekeeping.......................................................................................... 712 
Nutritional management .................................................................................. 713 
Efficient use of water ....................................................................................... 714 
Emissions from waste water ............................................................................ 715 
Efficient use of energy ..................................................................................... 716 
Noise emissions ............................................................................................... 716 
Dust emissions ................................................................................................. 718 
Odour emissions .............................................................................................. 719 
Emissions from solid manure storage .............................................................. 720 
Emissions from slurry storage ......................................................................... 721 

xii 

Intensive Rearing of Poultry or Pigs 

 
5.1.12 
5.1.13 
5.1.14 
5.1.15 

On farm processing of manure ........................................................................ 723 
Manure landspreading ..................................................................................... 724 
Emissions from the whole production process ................................................ 725 
Monitoring of emissions and process parameters ........................................... 725 

5.2 

BAT CONCLUSIONS FOR THE INTENSIVE REARING OF PIGS ...................................... 728 

5.2.1 

Ammonia emissions from pig houses ............................................................. 728 

5.3 

BAT CONCLUSIONS FOR THE INTENSIVE REARING OF POULTRY .............................. 731 

5.3.1 

5.3.1.1 
5.3.1.2 
5.3.1.3 
5.3.1.4 

Ammonia emissions from poultry houses ....................................................... 731 
Ammonia emissions from houses for laying hens, broiler breeders or pullets ..... 731 
Ammonia emissions from houses for broilers ...................................................... 732 
Ammonia emissions from houses for ducks ......................................................... 733 
Ammonia emissions from houses for turkeys ...................................................... 733 
DESCRIPTION OF TECHNIQUES ........................................................................ 734 

5.4 

5.4.1 
5.4.2 
5.4.3 
5.4.4 
5.4.5 
5.4.6 

5.4.6.1 

5.4.6.2 

5.4.7 
5.4.8 

5.4.8.1 

5.4.9 

5.4.9.1 
5.4.9.2 
5.4.9.3 

5.4.10 

5.4.10.1 
5.4.10.2 

5.4.11 
5.4.12 

5.4.12.1 

5.4.12.2 
5.4.12.3 

5.4.13 

5.4.13.1 

5.4.13.2 
5.4.13.3 
5.4.13.4 

Techniques for reducing emissions from waste water .................................... 734 
Techniques for efficient use of energy ............................................................ 734 
Techniques for reducing dust emissions ......................................................... 735 
Techniques for reducing odour emissions ....................................................... 736 
Techniques for reducing emissions from the storage of solid manure ............ 736 
Techniques for reducing emissions from slurry storage ................................. 737 

Techniques for reducing ammonia emissions from slurry stores and earth-
banked storage ...................................................................................................... 737 
Techniques for reducing emissions to soil and water from slurry stores.............. 738 
Techniques for on farm manure processing .................................................... 738 
Techniques for manure landspreading ............................................................ 739 
Techniques for slurry landspreading .................................................................... 739 
Techniques for monitoring .............................................................................. 740 
Techniques for monitoring N and P excretion ..................................................... 740 
Techniques for ammonia and dust monitoring ..................................................... 741 
Techniques for monitoring of air cleaning systems.............................................. 742 
Nutritional management .................................................................................. 743 
Techniques for reducing nitrogen excreted .......................................................... 743 
Techniques for reducing phosphorus excreted ..................................................... 743 
Techniques to treat emissions to air from animal housing .............................. 744 
Techniques for pig houses ............................................................................... 744 
Description of floor types and techniques for reducing ammonia emissions in 
pig houses ............................................................................................................. 744 
Techniques for cooling slurry .............................................................................. 747 
Techniques for reducing the pH of slurry ............................................................ 747 
Techniques for poultry housing ....................................................................... 747 

Techniques for reducing ammonia emissions from houses for laying hens, 
broiler breeders or pullets ..................................................................................... 747 
Techniques for reducing ammonia emissions from broiler houses ...................... 749 
Techniques for reducing ammonia emissions from duck houses ......................... 749 
Techniques for reducing ammonia emissions from turkey houses ....................... 749 

6  EMERGING TECHNIQUES ............................................................................. 751 

6.1 

REARING OF POULTRY .............................................................................................. 751 

6.1.1 

Low-litter flooring system for broilers ............................................................ 751 

Intensive Rearing of Poultry or Pigs 

xiii 

6.1.2 

Sequential feeding in poultry ........................................................................... 752 

6.2 

REARING OF PIGS ....................................................................................................... 753 

6.2.1 
6.2.2 

6.2.3 
6.2.4 
6.2.5 

Air cleaning of underfloor exhaust airflow with fully slatted floors ............... 753 
Air cleaning of underfloor exhaust flow with partly slatted floors with a 
scraper and urine separation ............................................................................ 755 
Near-zero-emission stall housing system ......................................................... 757 
Photocatalytic titanium dioxide coating paints ................................................ 760 
Alternative farrowing pens .............................................................................. 760 

6.3  MANURE PROCESSING ............................................................................................... 763 

6.3.1 
6.3.2 
6.3.3 
6.3.4 

Combined biological manure processing and ammonia stripping ................... 763 
Phosphorus separation by gypsum-based precipitate ...................................... 765 
Electro-oxidation/electro-coagulation.............................................................. 766 
Struvite precipitation ........................................................................................ 768 

6.4  MANURE LANDSPREADING ........................................................................................ 770 

6.4.1 

P Index ............................................................................................................. 770 

7  CONCLUDING REMARKS AND RECOMMENDATIONS FOR FUTURE 

WORK .................................................................................................................. 773 

8  GLOSSARY .......................................................................................................... 777 

I. 

II. 

III. 

IV. 

V. 

VI. 

ISO COUNTRY CODES ................................................................................................ 777 

MONETARY UNITS ..................................................................................................... 777 

UNIT PREFIXES, NUMBER SEPARATORS AND NOTATIONS .......................................... 778 

UNITS AND MEASURES .............................................................................................. 778 

CHEMICAL ELEMENTS ............................................................................................... 779 

CHEMICAL FORMULAE COMMONLY USED IN THIS DOCUMENT ................................. 780 

VII.  ACRONYMS ................................................................................................................ 781 

VIII.  TECHNICAL TERMS .................................................................................................... 783 

9  ANNEXES ............................................................................................................ 795 

9.1 

9.2 

9.2.1 

ANIMAL SPECIES AND LIVESTOCK UNITS (LU).......................................................... 795 

EXAMPLES OF PHASE FEEDING PROGRAMMES .......................................................... 798 

9.2.1.1 
9.2.1.2 
9.2.1.3 
9.2.1.4 
9.2.1.5 

9.2.2 

9.2.2.1 
9.2.2.2 
9.2.2.3 
9.2.2.4 
9.2.2.5 

Multiphase feeding for poultry ........................................................................ 798 
Pullets ................................................................................................................... 798 
Laying hens........................................................................................................... 799 
Broilers ................................................................................................................. 800 
Turkeys ................................................................................................................. 801 
Ducks .................................................................................................................... 802 
Multiphase feeding for pigs ............................................................................. 803 
Gestating sows ...................................................................................................... 803 
Farrowing sows ..................................................................................................... 803 
Weaners ................................................................................................................ 804 
Fattening pigs ....................................................................................................... 804 
Multiphase feeding in France ............................................................................... 806 

9.3 

EXAMPLE OF CALCULATION OF COSTS ASSOCIATED WITH THE APPLICATION OF 
EMISSION REDUCTION TECHNIQUES .......................................................................... 807 

xiv 

Intensive Rearing of Poultry or Pigs 

 
9.3.1 
9.3.2 
9.3.3 
9.3.4 

9.4 

9.5 

9.5.1 
9.5.2 
9.5.3 
9.5.4 

Methodology ................................................................................................... 807 
Examples in the UK ........................................................................................ 810 
Examples in Spain ........................................................................................... 812 
Appendices ...................................................................................................... 816 

REFERENCE TECHNIQUES .......................................................................................... 820 

DATA COMPILATION FOR EXCRETION ....................................................................... 821 

Total nitrogen excreted from pig rearing ........................................................ 821 
Total phosphorus excreted from pig rearing ................................................... 823 
Total nitrogen excreted from poultry rearing .................................................. 824 
Total phosphorus excreted from poultry rearing ............................................. 826 

9.6 

DATA COMPILATION FOR AMMONIA EMISSIONS ....................................................... 828 

9.6.1 
9.6.2 

Ammonia emissions to air from an animal house for pigs .............................. 828 
Ammonia emissions to air from an animal house for poultry ......................... 831 

10  REFERENCES ..................................................................................................... 835 

Intensive Rearing of Poultry or Pigs 

xv 

List of figures 

Figure 1.1:  Animal density in the European Union expressed as number of livestock units per 

hectare of utilised agricultural area in 2010 ........................................................................... 2 
Figure 1.2:  Example of the production chain of the egg production sector .............................................. 7 
Figure 1.3:  Example of the production chain of the broiler production sector ....................................... 11 
Figure 1.4:  Evolution of the weekly EU average price for Class A eggs in packing stations for the 

period 2009 to 2014 ............................................................................................................. 15 

Figure 1.5:  Market prices for eggs from caged hens (average for categories L and M) for the period 

2011 to 2013 ......................................................................................................................... 15 

Figure 1.6:  Evolution of monthly EU average selling price in slaughter plants for broilers 

(wholesale price for class A chicken) for the period 2006 to 2012 ...................................... 17 
Figure 1.7:  Market prices for broilers for the period 2011 to 2013 ........................................................ 18 
Figure 1.8:  Pig density by region (in average number per km2) in 2013 ................................................ 21 
Figure 1.9:  Production of meat by type of animal (in tonnes) in the EU-28 ........................................... 23 
Figure 1.10:  Evolution of pig meat market prices on weekly basis (EUR/100 kg deadweight) in the 

EU-28, January 2009 - February 2015 ................................................................................. 28 
Figure 1.11:  Market prices for pig meat ................................................................................................... 29 
Figure 1.12:  Illustration of the potential negative environmental aspects related to intensive livestock 

farming ................................................................................................................................. 31 

Figure 1.13:  Nitrogen consumption, utilisation and losses in the production of a pig for slaughter 

with a final live weight of 108 kg ......................................................................................... 32 
Figure 1.14:  Emissions of ammonia to air by industry sector/activity in Europe in 2014 ........................ 34 
Figure 1.15:  Nitrogen cycle showing the main transformations and losses to the environment after 

manure landspreading .......................................................................................................... 38 

Figure 2.1:  Schematic representation of activities carried out on farms for the intensive rearing of 

poultry or pigs ...................................................................................................................... 42 
Figure 2.2:  Possible placement of the equipment in enriched cages ....................................................... 45 
Figure 2.3:  Schematic drawing of two large enriched cages .................................................................. 45 
Figure 2.4:  Schematic cross section of a single-tiered non-cage system ................................................ 48 
Figure 2.5:  Common aviary configurations ............................................................................................ 50 
Figure 2.6:  Example of schematic cross section of a common broiler house ......................................... 52 
Figure 2.7:  Effect of dust attraction caused by ionisation on the roof of a poultry shed ........................ 61 
Figure 2.8:  Schematic view of a housing design for mating sows .......................................................... 73 
Figure 2.9: 
Individual housing of mating sows (service centre) ............................................................. 74 
Figure 2.10:  Floor design for sow crates with a solid concrete floor for mating and gestating sows ....... 74 
Figure 2.11:  Example of a housing system for group housing of gestating sows with individual 

feeding stalls and shared lying and defecating area ............................................................. 75 

Figure 2.12:  Example of group housing for gestating sows with individual feeding stalls in 

combination with full litter ................................................................................................... 76 

Figure 2.13:  Example of group housing for mating and gestating sows with perforated lying area 

(perforation in the lying area < 15 %) .................................................................................. 76 
Figure 2.14:  Layout of a pen for gestating sows fed with an electronic feeder ........................................ 78 
Figure 2.15:  Example of confined housing of farrowing sows on a fully slatted floor with a storage 

pit underneath ....................................................................................................................... 79 
Figure 2.16:  Farrowing pens allowing sow movement ............................................................................. 80 
Figure 2.17:  Schematic picture of a fully slatted floor pen for weaners ................................................... 81 
Figure 2.18:  Schematic picture of a weaner pen with a partly slatted floor .............................................. 82 
Figure 2.19:  Design of a partly slatted floor system for fattening pigs ..................................................... 85 
Figure 2.20:  Pen design for fattening pigs with partly slatted (convex) floor and solid area in the 

centre .................................................................................................................................... 85 
Figure 2.21:  Solid concrete floor with slatted external alley and scraper underneath .............................. 86 
Figure 2.22:  An example of a solid concrete floor system for fattening pigs ........................................... 87 
Figure 2.23:  Solid concrete floor with external littered alley and manure channel .................................. 87 
Figure 2.24:  Schematic view of airflow in an exhaust ventilation system ................................................ 93 
Figure 2.25:  Schematic view of airflow in a pressure ventilation system ................................................. 93 
Figure 2.26:  Schematic view of airflow in a neutral ventilation system ................................................... 94 
Figure 2.27:  Schematic representation of a wet scrubber ....................................................................... 103 
Figure 2.28:  Example of above-ground slurry tank with an underground receiving pit ......................... 116 
Figure 2.29:  Example of earth-banked slurry store, and design features ................................................ 117 
Figure 2.30:  Placement of the manure when applying manure with different application and 

incorporation methods ........................................................................................................ 128 
Figure 2.31:  Example of a broadcast spreader with a splash plate ......................................................... 130 

xvi 

Intensive Rearing of Poultry or Pigs 

 
 
Figure 2.32:  Example of a raingun ......................................................................................................... 131 
Figure 2.33:  Example of a broadcast technique with low trajectory and low pressure .......................... 131 
Figure 2.34:  Example of a broadcast technique with low trajectory and low pressure .......................... 132 
Figure 2.35:  Rear view of a horizontal boom with splash plate for slurry application........................... 133 
Figure 2.36:  Side view of a horizontal boom with splash plate for slurry application ........................... 133 
Figure 2.37:  Example of a band spreader fitted with rotary distributor to improve lateral distribution . 134 
Figure 2.38:  Example of an open slot injector ....................................................................................... 135 
Figure 2.39:  Example of a rotaspreader ................................................................................................. 136 
Figure 2.40:  Example of a rear discharge spreader ................................................................................ 136 
Figure 2.41:  Example of a dual-purpose spreader .................................................................................. 137 
Figure 2.42:  Vertical drum manure spreader .......................................................................................... 138 
Figure 2.43:  Operating principle of a heat pump ................................................................................... 146 
Figure 3.1:  Evolution of water consumption with the live weight of post-weaning piglets ................. 159 
Figure 3.2:  Breakdown of electricity consumption on pig farms in France ......................................... 167 
Figure 3.3:  Evolution over time of ammonia volatilisation (percentage of total nitrogen) for 

different pig categories ...................................................................................................... 177 
Figure 3.4:  Nitrogen losses from manure landspreading ...................................................................... 194 
Figure 3.5:  Cumulative ammonia volatilisation losses during storage and following landspreading 

of broiler litter .................................................................................................................... 202 
Figure 4.1:  Continuous improvement in an EMS model ...................................................................... 215 
Figure 4.2:  Example of reduced protein intake by animals achieved by synthetic amino acid 

supplementation to a low-protein diet, while maintaining an adequate amino acid supply232 

Figure 4.3:  Fluctuation of synthetic amino acids and high-protein feedstuff (soya) prices from 2004 

to 2008 ............................................................................................................................... 241 

Figure 4.4:  Example of the cost difference between a low-protein diet and a conventional diet in 

Spain .................................................................................................................................. 242 
Figure 4.5:  Effect of reduced crude protein diets on the intake of water by pigs ................................. 261 
Figure 4.6:  Schematic representation of feed, water and heat distribution by a biomass burner in a 

broiler house ...................................................................................................................... 280 
Figure 4.7:  Schematic representation of a heat recovery system installed in a broiler house .............. 296 
Figure 4.8:  Graphic representation of the working principle of the combideck system during one 

broiler production cycle ..................................................................................................... 296 
Figure 4.9:  Scheme of rows of enriched cages for laying hens ............................................................ 303 
Figure 4.10:  Schematic representation of a deep litter system with a manure pit for laying hens ......... 311 
Figure 4.11:  Schematic representation of a deep litter system with a manure pit, a veranda and a free-

range system for laying hens ............................................................................................. 312 
Figure 4.12:  Deep litter systems with forced drying via tubes under the slatted floor ........................... 314 
Figure 4.13:  Deep litter system with perforated floor and forced manure drying .................................. 316 
Figure 4.14:  Scheme of a litter-based aviary for laying hens ................................................................. 318 
Figure 4.15:  Combinations of slatted floors in aviaries ......................................................................... 319 
Figure 4.16:  Scheme of the underfloor manure drying system in aviary with a deep pit ....................... 322 
Figure 4.17:  Cross section of the housing system with deep litter and a manure pit ............................. 329 
Figure 4.18:  Examples of layouts for systems of circulating fans and a heat exchanger ....................... 339 
Figure 4.19:  Plan and cross section of horizontal ventilation with air recirculated by indoor fans ........ 340 
Figure 4.20:  Schematic representation of a forced drying system with a perforated floor for broilers 

(A), an improved design (B), and a detail of the floor of the improved design (C) ........... 343 
Figure 4.21:  Schematic overview of the tiered floor system with two rows and six floors.................... 345 
Figure 4.22:  Schematic cross section and principle of a tiered floor system with forced drying for 

broilers ............................................................................................................................... 345 

Figure 4.23:  Example of a time flow pattern synchronising the patio hatching/raising cycle (19 days) 

with the finishing cycle in the different houses ................................................................. 347 
Figure 4.24:  Cross section of system with forced air drying by vertical tubes....................................... 352 
Figure 4.25:  Scheme of an additional tier over the nests in an aviary system ........................................ 355 
Figure 4.26:  Scheme of a naturally ventilated house for turkey fattening .............................................. 359 
Figure 4.27:  Principle of operation of the overflow slurry channel ....................................................... 371 
Figure 4.28:  Vacuum system in case of a fully slatted floor .................................................................. 372 
Figure 4.29:  Vacuum system in case of a partly slatted floor ................................................................ 374 
Figure 4.30:  Example of PE pipes ready to be cast in concrete ............................................................. 379 
Figure 4.31:  Slurry surface cooling fins ................................................................................................. 381 
Figure 4.32:  Fully slatted floor with flushing gutters ............................................................................. 383 
Figure 4.33:  Fully slatted floor with flushing tubes ............................................................................... 384 
Figure 4.34:  Fully slatted floor with flushing of a permanent slurry layer in channels underneath ....... 384 

Intensive Rearing of Poultry or Pigs 

xvii 

Figure 4.35:  Cross section and plan view of the floor in a housing system for gestating sows with a 

manure channel with slanted walls ..................................................................................... 393 

Figure 4.36:  Flushing gutters in individual mating/gestating sow housing (in case of a partly slatted 

floor)................................................................................................................................... 396 
Figure 4.37:  Individual housing with a small manure pit ....................................................................... 398 
Figure 4.38:  Solid concrete floor and fully slatted external alley with a storage pit underneath ............ 398 
Figure 4.39:  Kennel housing system for gestating sows ......................................................................... 400 
Figure 4.40:  Kennel housing for mating and gestating sows with individual feeding stalls ................... 401 
Figure 4.41:  Littered floor with a slatted feeding area ............................................................................ 404 
Figure 4.42:  Solid concrete floor system with straw and electronic sow feeders ................................... 405 
Figure 4.43:  Scheme of the floor levels in litter-based pens with feeding/lying boxes .......................... 408 
Figure 4.44:  Farrowing crate with a partly slatted floor (solid floor in the lying areas) ......................... 411 
Figure 4.45:  Farrowing crate with a manure scraper (in case of a partly slatted floor) .......................... 415 
Figure 4.46:  Flushing system with a manure gutter ................................................................................ 416 
Figure 4.47:  Combination of water and manure channels ...................................................................... 418 
Figure 4.48:  Shallow slurry pits separating manure and water channels during construction ................ 418 
Figure 4.49:  A manure pan (in case of fully slatted floor) ...................................................................... 420 
Figure 4.50:  Littered farrowing pens with a yard ................................................................................... 422 
Figure 4.51:  Flat deck system with a scraper under a fully slatted floor ................................................ 429 
Figure 4.52:  Kennel housing system for weaners ................................................................................... 431 
Figure 4.53:  Partly slatted floor with a shallow manure pit and a water channel for spoiled drinking 

water in combination with a convex floor .......................................................................... 434 

Figure 4.54:  Convex floor with triangular metal slats in combination with a discharge system and 

slanted walls in the manure channel ................................................................................... 434 
Figure 4.55:  Partly slatted floor with a convex or sloped concrete floor ................................................ 436 
Figure 4.56:  Flat decks or pens with an underground concrete slope to separate faeces from urine ...... 438 
Figure 4.57:  Cross section of a variation of a system for rearing weaners with manure collection in 

water ................................................................................................................................... 440 
Figure 4.58:  Housing system with deep litter for weaners ..................................................................... 441 
Figure 4.59:  Housing system with a littered floor and a yard (with or without a covered lying area) 

for weaners ......................................................................................................................... 442 
Figure 4.60:  Convex floor in combination with a gutter system............................................................. 456 
Figure 4.61:  Partly slatted floor and external alley with the flushing of a permanent slurry layer in 

channels underneath ........................................................................................................... 457 
Figure 4.62:  Kennel housing system for fattening pigs .......................................................................... 460 
Figure 4.63:  Design of the straw flow system for fattening pigs ............................................................ 462 
Figure 4.64:  Effect on costs of heat utilisation for different levels of slurry cooling ............................. 467 
Figure 4.65:  Pens with a solid concrete straw-bedded floor and natural ventilation .............................. 469 
Figure 4.66:  Schematic plans and sections of housing systems equipped with V-shaped belts ............. 475 
Figure 4.67:  Effect of dust attraction caused by ionisation on the roof of a poultry shed ...................... 478 
Figure 4.68:  Schematic view of an oil spraying system ......................................................................... 485 
Figure 4.69:  Schematic representation of the functioning principle of floating balls ............................. 486 
Figure 4.70:  Ammonia removal efficiency as a function of the proportion of the treated air by the air 

cleaning system .................................................................................................................. 491 
Figure 4.71:  Bioscrubber workflow ........................................................................................................ 494 
Figure 4.72:  Ammonia emissions from a broiler house .......................................................................... 504 
Figure 4.73:  Two-stage scrubber: acid scrubber combined with bioscrubber ........................................ 510 
Figure 4.74:  Three stage scrubber: water scrubber combined with wet acid scrubber and biofilter ....... 514 
Figure 4.75:  Schematic of a dry filter installed in a broiler house .......................................................... 520 
Figure 4.76:  Scheme of the water trap .................................................................................................... 521 
Figure 4.77:  Rigid cover for slurry storage, with conical shape ............................................................. 543 
Figure 4.78:  Geometrical plastic tiles in a slurry tank ............................................................................ 550 
Figure 4.79:  Underground slurry tank with liquid-tight geomembrane .................................................. 561 
Figure 4.80:  Inspection shaft for area drainage pipes from a slurry store ............................................... 563 
Figure 4.81:  Examples of manure processing strategies ......................................................................... 567 
Figure 4.82:  Screw press scheme ............................................................................................................ 574 
Figure 4.83:  Schematic of a decanter centrifuge for slurry separation ................................................... 576 
Figure 4.84:  Schematic representation of a coagulation-flocculation pretreatment for slurry 

separation ........................................................................................................................... 578 
Figure 4.85:  Illustration of a rotating (drum) sieve separator used for slurry ......................................... 581 
Figure 4.86:  Schematic representation of a filter-pressing separator ...................................................... 583 

xviii 

Intensive Rearing of Poultry or Pigs 

 
Figure 4.87:  Mass balance and composition of the different streams resulting from a combination of 
a mechanical separation stage with flocculation and a biological aeration treatment with 
serial tank configuration .................................................................................................... 587 

Figure 4.88:  Example of biogas installation, following anaerobic treatment of manure, located in 

Denmark ............................................................................................................................ 601 
Figure 4.89:  Principle of external drying tunnel with perforated manure belts ...................................... 611 
Figure 4.90:  Schematic representation of a slurry acidification system ................................................. 613 
Figure 4.91:  Systems for slurry acidification directly in the storage tank .............................................. 614 
Figure 4.92:  Equipment for slurry acidification during spreading ......................................................... 614 
Figure 4.93:  Whole-farm assessment of the slurry acidification effect on the nitrogen available for 

plant uptake........................................................................................................................ 616 
Figure 4.94:  Scheme of a manure belt dryer .......................................................................................... 630 
Figure 4.95:  Irrigation boom fitted with hanging nozzles to spray the water-slurry mixture close to 

the soil surface ................................................................................................................... 649 
Figure 4.96:  Pulse-jet irrigator in operation ........................................................................................... 651 
Figure 4.97:  Example of trailing hoses mounted on a bar ...................................................................... 654 
Figure 4.98:  Scheme of a trailing shoe spreader .................................................................................... 654 
Figure 4.99:  Scheme of an open slot injector ......................................................................................... 658 
Figure 4.100: Scheme of a closed slot injector ........................................................................................ 661 
Figure 4.101: Incorporation equipment combined with a big tanker ....................................................... 664 
Figure 4.102: Scheme of a first flush system ........................................................................................... 680 
Figure 4.103: Location of a system of swales and wetland for a poultry farm ........................................ 681 
Figure 4.104: Layout of a system for purifying slurry based on constructed wetlands ............................ 682 
Figure 4.105: Example of a sprinkler or travelling irrigation system....................................................... 684 
Figure 6.1:  Layout of the ventilation system (left) and the floor design (right) with reduced slat 

openings ............................................................................................................................. 753 
Figure 6.2:  Drawing of the partly slatted floored 'Perstrup' pens ......................................................... 756 
Figure 6.3:  Scheme of slurry cooling in the shallow manure channels and heated piglet area ............ 758 
Figure 6.4:  Gestating sow room of the near-zero-emission pig housing system showing the 'roof-

ceiling' construction principle ............................................................................................ 758 
Figure 6.5:  An illustration of a design for an alternative farrowing sow pen ....................................... 761 
Figure 6.6:  Schematic representation of the combined treatment system including the solid 

separation step, biological treatment procedure and ammonia stripping stages ................ 764 
Figure 9.1:  Total nitrogen excreted by weaners ................................................................................... 821 
Figure 9.2:  Total nitrogen excreted by fattening pigs (1 of 2) ............................................................. 821 
Figure 9.3:  Total nitrogen excreted by fattening pigs (2 of 2) ............................................................. 822 
Figure 9.4:  Total nitrogen excreted by sows ........................................................................................ 822 
Figure 9.5:  Total phosphorus excreted by weaners .............................................................................. 823 
Figure 9.6:  Total phosphorus excreted by fattening pigs ..................................................................... 823 
Figure 9.7:  Total phosphorus excreted by sows ................................................................................... 824 
Figure 9.8:  Total nitrogen excreted by laying hens .............................................................................. 824 
Figure 9.9:  Total nitrogen excreted by broilers .................................................................................... 825 
Figure 9.10:  Total nitrogen excreted by ducks ....................................................................................... 825 
Figure 9.11:  Total nitrogen excreted by turkeys .................................................................................... 826 
Figure 9.12:  Total phosphorus excreted by laying hens ......................................................................... 826 
Figure 9.13:  Total phosphorus excreted by broilers ............................................................................... 827 
Figure 9.14:  Total phosphorus excreted by turkeys ............................................................................... 827 
Figure 9.15:  Ammonia emissions to air from an animal house for mating and gestating sows (1 of 2)  828 
Figure 9.16:  Ammonia emissions to air from an animal house for mating and gestating sows (2 of 2)  828 
Figure 9.17:  Ammonia emissions to air from an animal house for farrowing sows ............................... 829 
Figure 9.18:  Ammonia emissions to air from an animal house for weaners (1 of 2) ............................. 829 
Figure 9.19:  Ammonia emissions to air from an animal house for weaners (2 of 2) ............................. 830 
Figure 9.20:  Ammonia emissions to air from an animal house for fattening pigs (1 of 2) ..................... 830 
Figure 9.21:  Ammonia emissions to air from an animal house for fattening pigs (2 of 2) ..................... 831 
Figure 9.22:  Ammonia emissions to air from an animal house for laying hens (1 of 2) ........................ 831 
Figure 9.23:  Ammonia emissions to air from an animal house for laying hens (2 of 2) ........................ 832 
Figure 9.24:  Ammonia emissions to air from an animal house for broilers (1 of 2) .............................. 832 
Figure 9.25:  Ammonia emissions to air from an animal house for broilers (2 of 2) .............................. 833 

Intensive Rearing of Poultry or Pigs 

xix 

Table 1.1:  Animal density in the EU-28 expressed as number of livestock units per hectare of 

List of tables 

Table 1.2: 

utilised agricultural area for the years 2007, 2010 and 2013 .................................................. 3 
Summary of existing farms requiring a permit by category of activities in Annex I to 
Directive 2010/75/EU (reference period 2012–2013) ............................................................ 4 
Typical poultry rearing data ................................................................................................... 5 
Balance sheet for total egg production in the EU-27 for the years 2010–2013 ...................... 5 

Table 1.3: 
Table 1.4: 
Table 1.5:  Number of laying hens and usable production of eggs (total eggs) in EU-27 Member 

Table 1.6: 

States ...................................................................................................................................... 6 
Balance sheet for poultry meat production (in carcass weight) in the EU-27 for the years 
2011–2013 .............................................................................................................................. 8 
Poultry meat production in the EU-27 (in thousand tonnes of carcass weight) in 2012 ......... 9 

Table 1.7: 
Table 1.8:  Number of utility chicks of table strains hatched (in thousands of heads) in EU-27 

Member States ...................................................................................................................... 10 

Table 1.9:  Marketing terms and conditions for production of alternative broilers, according to 

Regulations (EC) 543/2008 and 834/2007 (organic) ............................................................ 11 
Table 1.10:  Comparison of production costs for rearing systems for laying hens at EU level ................ 13 
Table 1.11:  Prices, technical performance and production costs for egg production in selected EU 

countries in 2010 .................................................................................................................. 14 

Table 1.12:  Average performance data and production costs for egg production in France for the 

year 2011 .............................................................................................................................. 14 

Table 1.13:  Average performance data and production costs for meat poultry species in France for 

the year 2009 ........................................................................................................................ 16 

Table 1.14:  Prices, technical performance and production costs for broiler production in selected EU 

countries in 2011 .................................................................................................................. 16 
Table 1.15:  Pig population in the EU-28 in 2015 (in thousands) ............................................................ 19 
Table 1.16:  Pig population and changing structure of pig farms by herd size class in the EU-28, 

2005-2010 ............................................................................................................................ 22 

Table 1.17:  Balance sheet for pig meat production (in carcass weight) in the EU-27 for the years 

2010–2013 ............................................................................................................................ 24 

Table 1.18:  Summary of physical performance data for the production of pigs for selected EU 

countries (year 2009) ............................................................................................................ 25 

Table 1.19:  Summary of financial performance in the year 2014 in selected countries (in EUR per 

kg deadweight (1)) ................................................................................................................ 27 

Table 1.20:  Changes in total production costs in the EU for the years 2009–2014 (in EUR per kg 

deadweight) .......................................................................................................................... 28 
Table 1.21:  Emissions to air from the intensive rearing of poultry or pigs ............................................. 32 
Table 1.22:  Overview of processes and factors involved in ammonia release from animal houses ........ 33 
Table 1.23:  Total fluxes of greenhouse gas emissions for the EU-27 pig and poultry production .......... 35 
Summary of the main characteristics of enriched cages ....................................................... 44 
Table 2.1: 
Range of weights of duck breeds for meat and egg production ........................................... 55 
Table 2.2: 
Examples of required indoor temperature for broiler rearing ............................................... 57 
Table 2.3: 
Indoor temperature for rearing turkeys, applied in France ................................................... 57 
Table 2.4: 
Table 2.5: 
Examples of lighting programmes for broiler production .................................................... 60 
Table 2.6:  Number of birds serviced by each type of drinking equipment in France ............................ 66 
Table 2.7:  Absorbency and characteristics of different bedding types .................................................. 69 
Table 2.8:  Manure and bedding management in litter-based systems for fattening pigs in France 

(from 30 kg to 115 kg live weight) ....................................................................................... 88 
Table 2.9:  General indicative levels of indoor environment for pigs .................................................... 89 
Table 2.10:  Example of temperature requirements in heated housing for different pig categories in 

healthy conditions ................................................................................................................ 90 
Table 2.11:  Ventilation rates and indoor temperatures for pig housing, in France.................................. 95 
Table 2.12:  Ventilation rates and indoor temperatures for pig housing, in the Netherlands ................... 96 
Table 2.13:  Ventilation rates for thermally insulated pig houses according to DIN 18910-1, in 

Germany and Austria ........................................................................................................... 96 
Table 2.14:  Number of animal serviced by each type of drinking equipment in France ....................... 102 
Table 2.15:  Storage times of poultry and pig manure in a number of Member States .......................... 107 
Table 2.16:  Examples of national regulations (2013) prohibiting manure application during certain 

periods of the year .............................................................................................................. 108 
Table 2.17:  Advantages and disadvantages of solid manure- and slurry-based systems ....................... 109 
Table 2.18:  Factors used for calculating storage dimensions for pig slurry, in Belgium-Flanders and 

Spain................................................................................................................................... 111 

xx 

Intensive Rearing of Poultry or Pigs 

 
 
Table 2.19:  Factors for calculating the dimensions of the manure store for cage-reared laying hens 

in France (1 000 bird places) ............................................................................................. 113 
Table 2.20:  Examples of requirements applied for temporary field heaps in different Member States 114 
Table 2.21:  Qualitative comparison of four slurry transport systems ................................................... 129 
Table 2.22:  Comparison of solid manure spreading systems ................................................................ 137 
Table 3.1:  Key environmental issues of the major on-farm activities ................................................. 149 
Indication of feed conversion ratio and feed consumption per poultry category ............... 151 
Table 3.2: 
Table 3.3:  Appraisal of protein and lysine levels and scope for recommended amino acid balances . 152 
Table 3.4:  Applied calcium and phosphorus levels in commercial feeds for poultry ......................... 152 
Table 3.5:  Appraisal of protein and lysine levels and scope for recommended amino acid balances 

for sows (one phase for every physiological stage) ........................................................... 153 
Table 3.6:  Applied calcium and phosphorus levels in commercial feeds for sows ............................. 154 
Table 3.7:  Appraisal of protein and lysine levels and scope for recommended amino acid balances 

Table 3.8: 

for pigs (one phase for each major stage of growth) .......................................................... 154 
Calcium and digestible phosphorus standard levels applied to feed for pigs, in total 
amount per kg of feed ........................................................................................................ 155 
Example of rationing used for conventional and heavy fattening pigs in Italy .................. 155 

Table 3.9: 
Table 3.10:  Average nutritional levels applied in Italy for heavyweight pigs for different live weight 

intervals (as % of raw feed) ............................................................................................... 156 
Table 3.11:  Water consumption of different poultry species per cycle and per year ............................ 156 
Table 3.12:  Estimated water use for cleaning of poultry housing ......................................................... 157 
Table 3.13:  Average water requirements of pigs in Spanish farms with respect to pig category ......... 158 
Table 3.14:  Example of the effect of water to feed ratio on the production and dry matter content of 

manure of fattening pigs .................................................................................................... 159 

Table 3.15:  Effect of water delivery of drinking nipples on the production and dry matter content of 

manure of fattening pigs .................................................................................................... 160 
Table 3.16:  Estimated average water use for the cleaning of pig housing in Denmark ........................ 160 
Table 3.17:  Annual average gas consumption reported for poultry production in France .................... 162 
Table 3.18:  Annual average electricity consumption for poultry production in France ........................ 163 
Table 3.19:  Distribution of electricity consumption for two poultry farms in France .......................... 163 
Table 3.20: 
Indicative levels of daily energy consumption of activities on poultry farms in Italy ....... 163 
Table 3.21: 
Indicative levels of energy use in poultry farms in the UK ............................................... 164 
Table 3.22:  Estimates of energy consumption (kWh/bird) for pullets and laying hens, in France ....... 164 
Table 3.23:  Energy consumption allocation in a broiler house in Finland ............................................ 164 
Table 3.24:  Share of energy sources and total average energy consumption for different types of pig 

farms in France .................................................................................................................. 165 

Table 3.25:  Distribution of energy consumption in integrated farms in France, for each 

physiological stage (average values from 15 farms) .......................................................... 165 

Table 3.26:  Shares of energy consumption for each consuming process, in integrated farms in 

France ................................................................................................................................ 165 

Table 3.27:  Average annual energy consumption per type of pig farm and by type of energy source 

used and operation in Italy ................................................................................................. 166 

Table 3.28:  Average daily energy consumption for farms in Italy by animal capacity and energy 

source ................................................................................................................................. 166 

Table 3.29:   Electric energy consumption for different rearing stages in pig farms in the UK (data 

from 11 farms) ................................................................................................................... 167 
Table 3.30  Typical amounts of bedding materials applied in France in pig housing systems ............. 168 
Table 3.31:  Typical amounts of bedding material used in poultry and pigs housing systems .............. 169 
Table 3.32:  Nitrogen excretion standards calculated for different animal categories ........................... 171 
Table 3.33:  Excretion levels of different elements in poultry manure, in France ................................. 172 
Table 3.34:  Examples of excretion levels for total N and P, from Italy, Ireland and Belgium 

(Flanders) ........................................................................................................................... 172 
Table 3.35:  Standard values for excretion of broilers in Denmark (reference year 2014) .................... 172 
Table 3.36:  Calculated excretion levels for different poultry categories, in the Netherlands 

(reference year 2008) ......................................................................................................... 173 
Table 3.37:  Nitrogen and excreta production by poultry type in the UK (reference year 2012) ........... 173 
Table 3.38:  Composition and production of manure from different poultry species and manure 

management in France ....................................................................................................... 174 

Table 3.39:  Range of levels reported for daily and annual production of manure, urine and slurry by 

different pig categories ...................................................................................................... 175 

Table 3.40:  Example of effect of reduced CP levels in feed for growers and finishers on daily 

consumption, retention and losses of nitrogen ................................................................... 175 

Intensive Rearing of Poultry or Pigs 

xxi 

Table 3.41:  Average excretion of nitrogen (kg per year) in housing with a breeding sow (205 kg) 

and different numbers of piglets (up to 25 kg) at weaning ................................................. 176 
Table 3.42:  Nitrogen retention in different growing phases of fattening pigs (Italian data) ................. 176 
Table 3.43:  Standard level of nitrogen excretion in kg/animal place/year, in France ........................... 177 
Table 3.44:  Example of consumption, retention and excretion of phosphorus in pigs (kg per pig) ...... 178 
Table 3.45:  Average composition of different types of pig manure and standard deviation (in 

brackets) in kg per 1 000 kg of manure .............................................................................. 178 

Table 3.46:  Pig excreta and nitrogen produced in relation to different pig categories and nutritional 

measures, in the UK ........................................................................................................... 179 

Table 3.47:  Calculated annual excretion of nutrients per pig category, in the Netherlands (reference 

year 2008) .......................................................................................................................... 179 

Table 3.48:  Annual excretion rates and slurry generation for pig rearing units and different pig 

categories, in Ireland and Belgium (Flanders) ................................................................... 180 
Table 3.49:  Annual excretion rates for different pig categories, in Denmark (reference year 2014) .... 180 
Table 3.50:  Examples of national ammonia emission factors for poultry housing ................................ 183 
Table 3.51:  Ammonia emission factors for different poultry types, in Denmark .................................. 183 
Table 3.52:  Estimated emissions from fan ventilated littered duck housing in the UK......................... 184 
Table 3.53:  Range of reported air emission levels from poultry houses ............................................... 185 
Table 3.54:  Ammonia emission factors for pig housing, used in the UK .............................................. 186 
Table 3.55:  Ammonia emission factors for pig housing by pig category, in Germany ......................... 187 
Table 3.56:  Range of emissions to air from housing systems for sows (mating/gestating, farrowing) . 188 
Table 3.57:  Range of emissions to air from housing systems for weaners ............................................ 188 
Table 3.58:  Range of emissions to air from housing systems for fattening pigs ................................... 188 
Table 3.59:  Average ammonia and nitrous oxide emissions during storage of solid pig manure in 

heaps................................................................................................................................... 189 
Table 3.60:  Ammonia and nitrous oxide emissions during storage of solid poultry manure in heaps .. 190 
Table 3.61:  Range of ammonia emission factors for solid poultry manure storage as reported by 

Member States .................................................................................................................... 190 
Table 3.62:  Emission factors reported by the UK for solid manure storage .......................................... 190 
Table 3.63:  Ammonia emissions from uncovered stored pig slurry ...................................................... 191 
Table 3.64:  Ammonia emission factors for covered and uncovered slurry storage in Denmark ........... 191 
Table 3.65:  Range of ammonia emission factors for pig slurry storage as reported by Member States 192 
Table 3.66:  Factors influencing the emission levels of ammonia into air from landspreading ............. 194 
Table 3.67:  Emissions from solid manure landspreading, with or without incorporation, reported 

from the UK ....................................................................................................................... 195 

Table 3.68:  Range and average values of ammonia emissions measured after landspreading of solid 

manure without incorporation ............................................................................................ 196 

Table 3.69:  Ranges of national ammonia emission factors for slurry landspreading, as reported by 

Member States .................................................................................................................... 196 

Table 3.70:  Average NH4-N emission factors and ranges of measured values, expressed as 

percentage of total ammoniacal nitrogen applied ............................................................... 196 
Table 3.71:  Emissions of N2O-N from landspreading of solid manures ............................................... 197 
Table 3.72:  Reported N2O-N emissions from pig manure landspreading ............................................. 197 
Table 3.73:  Emissions of metals associated with landspreading of poultry manure ............................. 200 
Table 3.74:  Examples of the nitrogen flow through the whole farm chain for broiler manure ............. 200 
Table 3.75:  Examples of the nitrogen flow through the whole farm chain for laying hen manure ....... 201 
Table 3.76:  Nitrogen losses through all stages of poultry manure management by type of manure 

produced, in France ............................................................................................................ 201 

Table 3.77:  Nitrogen losses through all stages of pig manure management (without manure 

processing), in France ........................................................................................................ 202 

Table 3.78:  Examples of ammonia emission factors used as a reference for housing, storage and 

landspreading of slurry in Spain ......................................................................................... 203 
Table 3.79:  Typical sources of noise and examples of noise levels in poultry units ............................. 204 
Table 3.80:  Typical sources of noise and examples of noise levels in pig units ................................... 204 
Table 3.81:  Odour emission factors for different animal categories and housing systems in the 

Table 4.1: 
Table 4.2: 

Table 4.3: 
Table 4.4: 

xxii 

Netherlands, Germany and Denmark ................................................................................. 206 
Information for each technique .......................................................................................... 207 
Examples of emission concentrations in flue-gases from small-scale on-farm 
incinerators ......................................................................................................................... 214 
Examples of total emissions per operating cycle from small-scale on-farm incinerators .. 214 
Standard levels of nitrogen (N) and diphosphorus pentoxide (P2O5) excretion in 
Germany, Finland and France ............................................................................................ 220 

Intensive Rearing of Poultry or Pigs 

 
Table 4.5: 

Table 4.6: 
Table 4.7: 

Table 4.8: 
Table 4.9: 

Examples of the influence of nutrition measures on excreted nitrogen, phosphorus and 
potassium for the rearing of pigs ....................................................................................... 220 
Regressions used in Belgium (Flanders) to calculate the actual level of excretion ........... 222 
Contract prices for raw materials and estimates of raw material costs for balanced feed 
formulations for pigs.......................................................................................................... 223 
Examples of multiphase feeding regimes and associated emissions in the poultry sector . 226 
Reduction potential for ammonia emissions in fattening pig production with different 
crude protein adjusted feeding ........................................................................................... 228 

Table 4.10:  Examples of excreted nitrogen reductions for two-phase feeding programmes in the pig 

sector compared to the one-phase feeding ......................................................................... 228 

Table 4.11:  Example of the influence of multiphase feeding on excreted nitrogen and phosphorus 

for fattening pigs ................................................................................................................ 229 

Table 4.12:  Example of the influence of multiphase feeding with amino acid and phytase addition 

on excreted nitrogen and phosphorus for sows and weaners ............................................. 230 
Indicative crude protein levels in low-protein feeds for pigs ............................................. 233 
Indicative crude protein levels in low-protein feeds for poultry ........................................ 234 

Table 4.13: 
Table 4.14: 
Table 4.15:  Environmental and economic benefits of formulating a low-crude-protein diet with 

synthetic amino acid supplementation ............................................................................... 235 

Table 4.16:  Effects of two low-protein diets with partial or total substitution of soybeans by 

essential amino acids on fattening pigs (finishers) ............................................................ 236 

Table 4.17:  Summary of the effect of a reduction of dietary protein and the use of low-protein diets 

on nitrogen excretion and ammonia emission.................................................................... 236 

Table 4.18:  Effects of reduced crude protein levels with amino acid supplementation in one-phase 

feeding of fattening pigs .................................................................................................... 237 

Table 4.19:  Examples of emissions and costs reductions for two-phase feeding schemes after 

transition from a one-phase feeding scheme for fattening pigs ......................................... 237 

Table 4.20:  Effectiveness of transition from two-phase feeding to three-phase feeding for fattening 

pigs and different crude protein reductions ....................................................................... 238 

Table 4.21:  Effect of the protein content of fattening pigs' feed on slurry characteristics and nitrogen 

emissions ........................................................................................................................... 239 
Table 4.22:  Example of extra costs calculation for low-protein feeding strategies for fattening pigs .. 241 
Table 4.23:  Total phosphorus, phytate-phosphorus and phytase activity in selected plant feedstuffs .. 243 
Table 4.24:  Examples of excreted phosphorus reduction for different feeding programmes in the pig 

sector, applying a low-phosphorus diet with or without addition of phytase..................... 245 

Table 4.25:  Calculated reduction of phosphorus excretion based on digestibility, for the poultry 

sector .................................................................................................................................. 247 

Table 4.26:  Measured results of benzoic acid effects by rate of addition and by the characteristics of 

the tests in growing and finishing pigs .............................................................................. 251 
Table 4.27:  Reductions in excretion with the direct-fed microbial strains in pigs ................................ 253 
Table 4.28:  Reductions in excretion with the direct-fed microbial strains of lactobacillus in finishing 

broilers ............................................................................................................................... 253 
Table 4.29:  Gains in FCR and value of ingested feed with the use of probiotics in broilers ................ 253 
Table 4.30:  Average daily balance of nitrogen in broilers with and without the addition of feed 

additives (enzymes) ........................................................................................................... 255 
Table 4.31:  Effect of different additives in poultry at various feeding stages ...................................... 255 
Table 4.32:  Examples of the effect of drinking equipment on the water consumption and slurry 

generation of fattening pigs ............................................................................................... 260 

Table 4.33:  Examples of the effect of drinking equipment on the water consumption and slurry 

generation of gestating sows .............................................................................................. 260 
Table 4.34:  Benchmark figures for energy use in a pig farm ................................................................ 265 
Table 4.35:  Benchmark figures for energy use in a weaning house...................................................... 265 
Table 4.36:  Heat transfer coefficients (U) for different poultry house insulation materials with a 

thickness of 2.54 cm .......................................................................................................... 267 

Table 4.37:  Estimations of heat losses during one production cycle from roofs in laying hen 

housing, and the requirements for energy replacement (building area: 1 200 m2) ............. 268 

Table 4.38:  Costs for the renovation of insulation and sealing in a standard poultry house of 

1 200 m2 ............................................................................................................................. 269 

Table 4.39:  Recommended heat transfer coefficients (U) for two different temperatures, applied in 

France ................................................................................................................................ 271 
Table 4.40:  Effect of insulation thickness on heat consumption in weaner houses .............................. 271 
Table 4.41:  Principal lighting sources for animal houses ..................................................................... 273 
Table 4.42:  Example of a mixed farm benefitting from warm water heating served by a wood boiler 281 

Intensive Rearing of Poultry or Pigs 

xxiii 

Table 4.43:  Operating conditions and energy consumption of a broiler housing system equipped 

with energy-saving fans, in Finland ................................................................................... 285 

Table 4.44:  Heat consumption according to minimum ventilation flows and added insulation, for 

weaners at an early post-weaning age ................................................................................ 287 
Table 4.45:   Ammonia emissions and germs concentration in relation to the ventilation rate ............... 287 
Table 4.46:  Example of operational data of an air-air heat exchanger .................................................. 290 
Table 4.47:  Propane and electricity consumption and costs, in three different poultry farms applying 

heat recovery by air-air heat exchangers ............................................................................ 292 
Table 4.48:  Results of the application of the combideck system ........................................................... 297 
Table 4.49:  Comparison of performance for identical houses with and without the combideck 

system................................................................................................................................. 297 
Table 4.50:  Different natural ventilation configurations ....................................................................... 299 
Table 4.51:  Summary of relevant reported achievable emissions in cage systems for laying hens ....... 302 
Table 4.52:  Effect of increasing the manure removal frequency, without manure drying, on 

ammonia emissions from enriched cages in comparison with weekly manure removal .... 304 

Table 4.53:  Effect of manure removal frequency, with manure drying on ventilated belts, on 

ammonia emissions from enriched cages, and associated costs ......................................... 304 

Table 4.54:  Economic consequences of removing manure two or three times per week compared to 

only once per week ............................................................................................................. 305 

Table 4.55:  Summary of relevant reported achievable emissions in deep-litter-based non-cage 

systems for laying hens ...................................................................................................... 308 

Table 4.56:  Summary of relevant reported achievable emissions in aviary-based non-cage systems 

for laying hens .................................................................................................................... 309 
Table 4.57:  Ventilation rates applied in deep litter housing systems for laying hens ............................ 313 
Table 4.58:  Cost data associated with different deep litter systems with a manure pit ......................... 313 
Table 4.59:  Resource demand associated with the different deep litter systems with a manure pit ...... 313 
Table 4.60:  Reported ventilation rates for aviary systems for laying hens equipped with manure 

belts .................................................................................................................................... 320 

Table 4.61:  Summary of cost data in Germany for different configurations of aviary systems for 

laying hens ......................................................................................................................... 321 
Table 4.62:  Summary of reported achievable emissions in systems for rearing pullets ........................ 325 
Table 4.63:  Emissions associated with combinations of slatted floor extension, characteristics of the 

drying air and frequency of manure removal, for the rearing of pullets ............................. 328 

Table 4.64:  Summary of reported emissions from broiler housing with different system 

configurations ..................................................................................................................... 331 

Table 4.65:  Effects on emissions of controlling mechanical ventilation in deep litter broiler housing 

systems ............................................................................................................................... 334 

Table 4.66:  Breakdown of resource demand in kWh per bird place/year in deep litter broiler houses 

(cycles of 38–42 days)........................................................................................................ 335 
Investment costs for deep litter houses for broilers ............................................................ 336 

Table 4.67: 
Table 4.68:  Reported emissions from broiler production in deep litter housing systems with 

circulating fans ................................................................................................................... 337 
Table 4.69:  Summary of emissions in systems for rearing broiler breeders .......................................... 349 
Table 4.70:  Cost data for deep litter systems equipped with manure pit aeration through pipes .......... 353 
Table 4.71:  Extra costs for manure pit aeration through pipes (in case of deep litter systems), in 

comparison with a reference system .................................................................................. 353 
Table 4.72:  Ventilation parameters in turkey rearing ............................................................................ 357 
Table 4.73:  Emissions from turkey rearing systems, with forced or natural ventilation (in case of 

deep litter) .......................................................................................................................... 357 
Table 4.74:  Ventilation rate range for forced ventilated Pekin duck rearing houses ............................. 360 
Table 4.75:  Reported emission data from deep litter systems for the rearing of ducks ......................... 361 
Table 4.76:  Reported ventilation rates applied in vacuum systems for frequent slurry removal (in 

case of a fully slatted floor) ................................................................................................ 373 

Table 4.77:  Consumption related to the management of FSF systems equipped with vacuum slurry 

removal ............................................................................................................................... 373 

Table 4.78:  Costs for the implementation of cooling fins for different animal categories and 

expected ammonia emissions reduction, in the Netherlands .............................................. 382 
Table 4.79:  Emission levels of system-integrated housing techniques for mating and gestating sows . 388 
Table 4.80:  Emission levels associated with slanted walls in the manure channel (in case of partly 

slatted floors) ...................................................................................................................... 394 

Table 4.81:  Ammonia emissions from mating/gestating sow houses with frequent slurry removal by 

flushing ............................................................................................................................... 396 
Table 4.82:  Energy requirements for flushing systems applied in gestating sow houses ...................... 397 

xxiv 

Intensive Rearing of Poultry or Pigs 

 
Table 4.83:  Emissions from housing systems for gestating sows with a reduced manure pit ............... 399 
Table 4.84:  Calculated extra costs for installing a reduced manure pit for gestating sows in existing 

houses with a fully slatted floor ......................................................................................... 399 

Table 4.85:  Consumption and labour requirements for kennel housing systems for mating and 

gestating sows .................................................................................................................... 401 
Table 4.86:  Expected electricity consumption depending on the cooling programme applied ............. 402 
Table 4.87:  Emissions of mating and gestating sows housed in littered systems ................................. 406 
Table 4.88:  Resources demand associated with solid floor housing systems covered with litter for 

mating/gestating sows, in Germany ................................................................................... 406 

Table 4.89:  Extra costs for the implementation of straw-littered solid floors with weekly 

replacement of bedding, in Spain ...................................................................................... 407 
Table 4.90:  Emission levels of system-integrated housing techniques for farrowing sows .................. 410 
Table 4.91: 
Investment costs reported for a fully slatted floor housing system with water and 
manure channels, in comparison with a fully slatted floor system with a deep pit ............ 419 

Table 4.92:  Extra costs for installing in FSF a combination of water and manure channels compared 

to a deep pit........................................................................................................................ 419 
Table 4.93:  Extra costs for installing in a FSF a manure pan in comparison to a deep pit, in Spain .... 421 
Table 4.94:  Emission levels of system-integrated housing techniques for weaners ............................. 424 
Table 4.95:  Ventilation rates (m3/h per animal place) applied to weaner houses with fully slatted 

floors .................................................................................................................................. 426 
Table 4.96:  Consumption and labour requirements for kennel housing systems for weaners .............. 432 
Table 4.97:  Emissions of housing systems equipped with a convex solid floor and separate manure 

and water channels ............................................................................................................. 434 
Table 4.98:  Odour emission factors for weaners, in Germany .............................................................. 437 
Table 4.99:  Extra costs associated to the retrofitting of partly slatted floors in existing fully slatted 

floored pens for weaners, in Spain ..................................................................................... 438 

Table 4.100:  Resources demand for two different variations of solid concrete floor housing systems 

with litter for weaners (8–28 kg) ....................................................................................... 443 
Table 4.101:  Emission levels associated with straw-littered systems for rearing of weaners ................. 444 
Table 4.102:  Emission levels of system-integrated housing techniques for fattening pigs ..................... 446 
Table 4.103:  Emissions associated with a deep pit (in case of a fully slatted floor) or with an 

overflow channel for various categories of pigs ................................................................ 450 

Table 4.104:  Resources demand for the rearing of fattening pigs in houses with a fully slatted floor 

with an overflow channel ................................................................................................... 450 

Table 4.105:  Ventilation rates (m3/h per animal place) applied to fattening pig houses with fully 

slatted floors ...................................................................................................................... 451 

Table 4.106:  Emissions from partly slatted floor systems for fattening pigs with infrequent manure 

removal .............................................................................................................................. 451 

Table 4.107:  Investment and operating costs for fattening pig houses with a fully slatted floor with an 

overflow channel ............................................................................................................... 452 
Table 4.108:  Emission levels associated with slanted walls in the manure channel ............................... 454 
Table 4.109:  Ammonia emissions from fattening pig houses with frequent slurry removal by flushing 457 
Table 4.110:  Emissions from housing systems for fattening pigs with a reduced manure pit ................ 459 
Table 4.111:  Calculated extra costs for installing a reduced manure pit in existing houses with a fully 

slatted floor, in Spain ......................................................................................................... 459 
Table 4.112:  Consumption and labour requirements for kennel housing systems for fattening pigs ..... 460 
Table 4.113:  Emission levels from straw flow systems for fattening pigs .............................................. 463 
Table 4.114:  Emissions of housing systems equipped with a convex solid floor and separated manure 

and water channels ............................................................................................................. 464 

Table 4.115:  Ammonia emission values achieved by slurry cooling channels for different fattening 

pig housing systems and cooling effect levels ................................................................... 466 

Table 4.116:  Electricity consumption of cooling channels in partly slatted floors by the cooling effect 

applied ............................................................................................................................... 466 
Table 4.117:  Emission levels from housing systems with full litter for the rearing of fattening pigs .... 471 
Table 4.118:  Resource requirements associated with deep litter and littered-floors applied to fattening 

pigs housing systems (1) .................................................................................................... 472 

Table 4.119:  Average characteristics of solid manure produced by deep litter housing systems for 

fattening pigs, in France .................................................................................................... 472 

Table 4.120:  Extra costs for implementation of straw littered housing systems for fattening pigs in 

comparison to a fully slatted floor system with a deep pit ................................................. 473 

Table 4.121:  Emissions associated with the use of the V-shaped belt system in partly slatted floor 

systems .............................................................................................................................. 476 

Intensive Rearing of Poultry or Pigs 

xxv 

Table 4.122:  Investment and operating costs for partly slatted floor systems with V-shaped manure 

belts, compared to conventional houses, in the Netherlands .............................................. 477 

Table 4.123:  Parameters and performances of fogging in poultry housing compared to other cooling 

systems techniques ............................................................................................................. 481 
Table 4.124:  Estimation of the annual operating costs for a fogging system .......................................... 481 
Table 4.125:  Odour abatement efficiencies achieved by misting of reactive agents in laboratory trials . 483 
Table 4.126:  Estimates of average costs for the atomisation of patented odour-abating chemicals by 

animal produced ................................................................................................................. 483 
Table 4.127:  Extra costs related to the technique of oil spraying in poultry housing .............................. 485 
Table 4.128  Composition of treated and untreated turkey manure ........................................................ 488 
Table 4.129:  Types of exhaust air cleaning systems in animal housing, their applicability and removal 

performance........................................................................................................................ 489 
Table 4.130:  Extra costs related to water scrubbers in poultry housing .................................................. 493 
Table 4.131:  Emission reductions achieved by the application of bioscrubbers in pig production ......... 495 
Table 4.132:  Reported emission levels achieved with the application of bioscrubbers .......................... 496 
Table 4.133:  Examples of water consumption and water discharges for fattening pig farms applying 

bioscrubbers ....................................................................................................................... 497 
Table 4.134:  Associated costs for bioscrubbers in the Netherlands by pig category ............................... 498 
Table 4.135:  Cost ranges associated with the use of bioscrubbers for exhaust air treatment in 

fattening pig production, in Germany and Denmark .......................................................... 499 

Table 4.136:  Investment and annual operating costs for a biotrickling filter applied to a newly built 

facility for pig production .................................................................................................. 500 
Table 4.137:  Extra costs related to the application of bioscrubbers in poultry housing .......................... 500 
Table 4.138:  Examples of removal efficiencies of chemical scrubbers applied in pig and poultry 

housing systems ................................................................................................................. 502 
Table 4.139:  Reported emission levels achieved with the application of acid scrubbers ........................ 503 
Table 4.140:  Additional energy consumption associated with air cleaning by an acid scrubber applied 

in pig farms in Denmark ..................................................................................................... 504 

Table 4.141:  Associated extra costs for acid scrubbers by associated ammonia reduction efficiency 

and animal category in the Netherlands ............................................................................. 505 

Table 4.142:   Investment and annual operating costs for an acid scrubber applied to a new house for 

pig production .................................................................................................................... 505 
Table 4.143:  Extra costs related to the application of acid scrubbers in poultry housing........................ 506 
Table 4.144:  Annual resources demand for the operation of a biofilter, in Germany ............................. 508 
Table 4.145:  Emission reductions achieved by the application of two-stage scrubbers in pig 

production .......................................................................................................................... 511 
Table 4.146:  Emission levels achieved with the application of two-stage scrubbers in pig production .. 511 
Table 4.147:  Cost ranges associated with the use of two-stage scrubber systems for exhaust air 

treatment in fattening pig production, in Germany ............................................................ 512 

Table 4.148:  Costs associated with the use of two-stage scrubbers with an 85 % NH3 reduction 

efficiency, in the Netherlands ............................................................................................. 513 

Table 4.149:  Examples of removal efficiencies achieved with a three stage scrubber system (water 

scrubber, wet acid scrubber and biofilter) .......................................................................... 515 
Table 4.150:  Emission levels achieved with the application of three-stage scrubbers in pig production 515 
Table 4.151:  Annual resources demand for the operation of a multi-stage scrubber, in Germany .......... 516 
Table 4.152:  Waste water volume produced by air cleaning system in a housing system for 1 000 

fattening pigs ...................................................................................................................... 516 

Table 4.153:  Cost ranges associated with the use of three-stage scrubber systems (combining a water 

scrubber, wet acid scrubber and biofilter) in fattening pig houses ..................................... 517 

Table 4.154:  Investment and annual operating costs for a three-stage scrubber (water and acid 

scrubber + biotrickling) applied to a newly built facility for fattening pig production ...... 517 

Table 4.155:  Emission levels and cost data for different percentages of exhaust air treated by two-

stage air cleaning systems .................................................................................................. 519 
Table 4.156:  Ammonia emissions from covered and uncovered poultry manure heaps ......................... 534 
Table 4.157:  Nitrogen losses from covered and uncovered solid manure heaps ..................................... 535 
Table 4.158:  Cost data of a silo for the storage of solid pig manure ....................................................... 538 
Table 4.159:  Overview of the different types of covers applied in slurry storage ................................... 541 
Table 4.160:  Ammonia emissions as a percentage of the total stored nitrogen in slurry containers in 

Denmark ............................................................................................................................. 542 

Table 4.161:  Reduction of gaseous emissions from the storage of slurry with the use of a rigid cover 

in underground pilot stores, compared to uncovered stores ............................................... 544 
Table 4.162:  Costs for rigid polyester covers reported from France ....................................................... 544 
Table 4.163:  Cost data for different covers of slurry tanks, in Germany ................................................ 545 

xxvi 

Intensive Rearing of Poultry or Pigs 

 
Table 4.164:  Ammonia emissions mitigation costs for different covers of slurry tanks, in Germany .... 545 
Table 4.165:  Costs for different types of flexible covers in France ........................................................ 547 
Table 4.166:  Costs for covering an above-ground slurry tank with flexible covers, in the UK .............. 548 
Table 4.167:  Performance of different types of floating covers ............................................................. 554 
Table 4.168:  Investment costs for some types of floating covers, in Denmark ...................................... 555 
Table 4.169:  Investment costs for different types of floating covers in France ...................................... 556 
Table 4.170:  Costs for covering an above-ground slurry tank with floating flexible covers, in the UK  556 
Table 4.171:  Cost data for different covers of earth-banked slurry stores (lagoons), in Germany ......... 559 
Table 4.172:  Investment costs for covering a slurry lagoon in the UK ................................................... 559 
Table 4.173:  Cost data for above-ground and underground slurry silos ................................................. 562 
Table 4.174:  Investment costs for slurry tanks and leakage inspection systems in Germany ................. 564 
Table 4.175:  Summary of the main characteristics of techniques for processing manure ...................... 568 
Table 4.176:  Characteristics and technical data of common slurry separators in the Netherlands ......... 572 
Table 4.177:  Costs of slurry mechanical separation in the Netherlands for an annual capacity of 

5 000 m3 ............................................................................................................................. 573 
Table 4.178:  Separation performance range of a screw press ................................................................. 575 
Table 4.179:  Characteristics of the separated fractions from a decanter-centrifuge separation of 

typical pig slurry in Denmark ............................................................................................ 577 

Table 4.180:  General characteristics of the incoming slurry and the produced fractions after a 

mechanical separation process including flocculation ....................................................... 579 
Table 4.181:  Example of pig slurry separated with a drum sieve ........................................................... 581 
Table 4.182:  Mass balance of the mechanical separation and biological treatment of pig slurry ........... 589 
Table 4.183:  Composition of manure and products in g/kg .................................................................... 589 
Table 4.184:  Nitrogen and weight losses during composting of solid pig manure, in France ................ 595 
Table 4.185:  Investment costs for equipment used in composting plants ............................................... 596 
Table 4.186:  Indicative values of the C/N ratio for different materials .................................................. 597 
Table 4.187:  Composition variation of turkey manure co-composted with green residues (ratio 1/1 in 

weight) ............................................................................................................................... 598 
Table 4.188:  Energy consumption of equipment used in composting and co-composting plants .......... 598 
Table 4.189:  Operational and cost data for a biogas plant applied on a small-scale farm, operating 

with pig slurry only ............................................................................................................ 604 

Table 4.190:  Number of existing biogas plants for manure digestion and the amount of manure 

digested in the Baltic Sea region countries (estimated for year 2012) ............................... 605 
Table 4.191:  Characteristics of effluents from slurry treated in anaerobic lagoons ................................ 607 
Table 4.192:  Costs for a vacuum evaporation plant for pig slurry, with a capacity of 14 000 

tonnes/year ......................................................................................................................... 610 

Table 4.193:  Average ammonia, methane and nitrous oxide emissions from the laying hen house and 

drying tunnel ...................................................................................................................... 612 
Table 4.194:  Cost data reported for slurry acidification in relation to the number of pigs, in Denmark  617 
Table 4.195:  Operating costs for a slurry acidification unit treating 10 000 m3/yr, in Denmark ............ 617 
Table 4.196:  Achievable emission levels from a fluidised bed combustion plant for poultry litter, in 

comparison with fresh wood shavings and ELVs set by Directive 2010/75/EU for waste 
incineration plants .............................................................................................................. 620 
Table 4.197:  Summary of the main characteristics for different groups of manure additives ................ 628 
Table 4.198:  Input and output characteristics of the manure processed in the manure belt drying 

process ............................................................................................................................... 630 
Table 4.199:  Calculated maximum allowable animal number per hectare ............................................. 635 
Table 4.200:  Costs for implementing spring slurry application practices in a typical pig farm in the 

UK in order to limit nitrate leaching losses ....................................................................... 640 
Table 4.201:  Characteristics of four different slurry application techniques .......................................... 643 
Table 4.202:  Bonus for conserved nitrogen, achieved by applying low-emission spreading techniques 

for slurry ............................................................................................................................ 646 

Table 4.203:  Costs for slurry spreading and associated ammonia emission reduction costs for 

different application techniques and farm sizes, in Germany ............................................ 647 
Table 4.204:  Average chemical characteristics of the water-slurry mixture ........................................... 653 
Table 4.205:  Estimated operating costs for a band spreader system and a broadcast system for the 

application of slurry ........................................................................................................... 656 

Table 4.206:  Extra costs related to slurry application with band spreading techniques in comparison 

with a broadcast spreader, in Spain.................................................................................... 657 

Table 4.207:  Ammonia emissions reduction achieved by slurry injection in comparison with surface 

application techniques, in Denmark ................................................................................... 659 

Table 4.208:  Extra energy and costs associated with open (shallow) and closed (deep) slot injection 

for different operating conditions applied in Denmark ...................................................... 660 

Intensive Rearing of Poultry or Pigs 

xxvii 

Table 4.209:  Summary of experiment results on ammonia emissions reduction with different manure 

incorporation equipment .................................................................................................... 665 

Table 4.210:  Average ammonia emissions and reduction efficiencies from the spreading of solid 

manures followed by immediate incorporation using different equipment ........................ 665 

Table 4.211:  Reduction of ammonia emissions achieved by the incorporation of solid manure after 

application .......................................................................................................................... 666 

Table 4.212:  Calculated ammonia emissions from the application of solid pig manure followed by 

incorporation, with different equipment and time lags ....................................................... 666 
Table 4.213:  Emissions of N2O after spreading and incorporation of solid manure ............................... 666 
Table 4.214:  Example of the effect of storage conditions and application conditions of broiler litter 

on subsequent emissions during application ...................................................................... 667 

Table 4.215:  Comparison of ammonia losses from different procedures for landspreading of 

differently stored broiler litters ........................................................................................... 667 

Table 4.216:  Extra costs for the incorporation of slurry applied by a broadcast spreader with a splash 

plate, in comparison with no incorporation within 24 hours, in Spain ............................... 668 
Table 4.217:  Reducing effect of different noise measures ...................................................................... 674 
Table 4.218:  Examples of assessed combinations of techniques for fattening pigs ................................ 687 
Table 4.219:  Examples of assessed combinations of techniques for broiler production ......................... 688 
Table 4.220:  Examples of assessed combinations of techniques for laying hens in enriched cages ....... 688 
Table 4.221:  Examples of assessed combinations of techniques for laying hens on litter ...................... 689 
Table 4.222:  Emission factors for dust (PM10) reported for various pig categories and types of 

manure management .......................................................................................................... 692 

Table 4.223:  Emission factors for dust (PM10) reported for various poultry categories and types of 

manure management .......................................................................................................... 693 

Table 4.224:  Sampling strategy and monitoring conditions for testing ammonia emissions in a 

livestock housing system .................................................................................................... 699 

Table 4.225:  Sampling strategy and monitoring conditions for testing dust emissions in a livestock 

housing system ................................................................................................................... 702 
Table 4.226:  Parameters to be recorded in the operations logbook ......................................................... 704 
BAT-associated total nitrogen excreted ............................................................................. 713 
Table 5.1: 
BAT-associated total phosphorus excreted ........................................................................ 714 
Table 5.2: 
Table 5.3: 
BAT-associated time delay between manure landspreading and incorporation into the 
soil ...................................................................................................................................... 725 
BAT-AEL for ammonia emissions to air from each pig house .......................................... 730 
BAT-AELs for ammonia emissions to air from each house for laying hens ...................... 731 
BAT-AEL for ammonia emissions to air from each house for broilers with a final 
weight of up to 2.5 kg......................................................................................................... 732 
Table 6.1:  Odour, hydrogen sulphide and ammonia concentrations and emissions ............................ 754 
Table 6.2:  Average concentrations and emissions of ammonia and odour measured in trials with 

Table 5.4: 
Table 5.5: 
Table 5.6: 

underfloor ventilation ......................................................................................................... 756 

Table 6.3:  Nutrient content of the resulting fractions after the multi-step biological and chemical 

Table 6.4: 

Table 6.5: 

manure processing .............................................................................................................. 765 
Example of concentration levels obtained before and after treatment of pig slurry by 
electro-coagulation ............................................................................................................. 767 
Efficiency of a combination of electro-coagulation and electro-oxidation in laboratory 
trials .................................................................................................................................... 767 

Table 7.1:  Key milestones of the review process of the BREF for the Intensive Rearing of Poultry 

or Pigs ................................................................................................................................ 773 
Split views .......................................................................................................................... 774 
Table 7.2: 
Standard values for the calculation of live animal mass in LU, used in Germany ............. 795 
Table 9.1: 
Standard values for the calculation of live animal mass in LU, used in Spain ................... 796 
Table 9.2: 
Standard values for the calculation of live animal mass in LU, used in the UK ................ 796 
Table 9.3: 
Table 9.4: 
Livestock unit coefficients used by Eurostat ...................................................................... 797 
Table 9.5:  Multiphase feeding for pullets in the UK ........................................................................... 798 
Table 9.6:  Multiphase feeding for pullets (free range) in the UK ....................................................... 798 
Table 9.7:  Multiphase feeding for pullets in Germany ........................................................................ 798 
Table 9.8:  Multiphase feeding for laying hens (in cages) in the UK ................................................... 799 
Table 9.9:  Multiphase feeding for laying hens (free range) in the UK ................................................ 799 
Table 9.10:  Multiphase feeding for laying hens (in cages) in Germany ................................................ 799 
Table 9.11:  Multiphase feeding for light broilers (40 days) in the UK ................................................. 800 
Table 9.12:  Multiphase feeding for heavy broilers (7 to 8.5 weeks) in the UK .................................... 800 
Table 9.13:  Multiphase feeding for broilers in Germany ...................................................................... 800 
Table 9.14:  Multiphase feeding for turkeys in the UK .......................................................................... 801 

xxviii 

Intensive Rearing of Poultry or Pigs 

Table 9.15:  Multiphase feeding for turkeys (starter) in Germany ......................................................... 801 
Table 9.16:  Multiphase feeding for turkeys (male) in Germany ........................................................... 801 
Table 9.17:  Multiphase feeding for turkeys (female) in Germany ........................................................ 802 
Table 9.18:  Multiphase feeding for ducks in Germany ......................................................................... 802 
Table 9.19:  Multiphase feeding for gestating sows in the UK .............................................................. 803 
Table 9.20:  Multiphase feeding for gestating sows in Germany ........................................................... 803 
Table 9.21:  Multiphase feeding for farrowing sows in Germany ......................................................... 803 
Table 9.22:  Multiphase feeding for weaners and growers in the UK .................................................... 804 
Table 9.23:  Multiphase feeding for weaners in Germany ..................................................................... 804 
Table 9.24:  Multiphase feeding for finishers in the UK (two phases) .................................................. 804 
Table 9.25:  Multiphase feeding for fattening pigs in Germany (two phases) ....................................... 805 
Table 9.26:  Multiphase feeding for weaners and fattening pigs in the UK (5 phases) ......................... 805 
Table 9.27:  Multiphase feeding for fattening pigs in Germany (5 phases) ........................................... 805 
Table 9.28:  Multiphase feeding for pigs in France ............................................................................... 806 
Table 9.29:  Units used for assessing costs ............................................................................................ 808 
Table 9.30:  Capital expenditure considerations .................................................................................... 809 
Table 9.31:  Annual cost considerations ................................................................................................ 809 
Table 9.32:  Additional costs incurred with liquid manure application by soil injection in the UK ...... 810 
Table 9.33:  Additional costs incurred with solid manure incorporation by ploughing in the UK ........ 811 
Table 9.34:  Additional costs incurred with air duct installation in the UK ........................................... 811 
Table 9.35:  Additional costs incurred with metal grid floor replacement in the UK ............................ 812 
Table 9.36:  Additional costs incurred for the installation of multiphase feeding in fattening pig 

houses in Spain .................................................................................................................. 812 

Table 9.37:  Additional costs to install a partly slatted floor with a reduced pit in gestating sow 

houses in Spain .................................................................................................................. 813 

Table 9.38:  Additional costs to install a manure pan with a smooth surface under the slatted floor in 

a new house for farrowing sows in Spain .......................................................................... 813 

Table 9.39:  Additional costs to install a manure pan with a smooth surface under the slatted floor in 

an existing house for farrowing sows in Spain .................................................................. 814 

Table 9.40:  Additional costs to install slanted walls in the manure pit of a new house for weaners in 

Spain .................................................................................................................................. 814 

Table 9.41:  Additional costs to install a partly slatted floor and reduced pit in an existing gestating 

pig house in Spain .............................................................................................................. 815 

Table 9.42:  Additional costs incurred for the fitting of a mounted trailing hose system to an existing 

slurry tanker ....................................................................................................................... 816 
Table 9.43:  Economic life of new facilities .......................................................................................... 817 
Table 9.44:  Repair costs as a percentage of new costs ......................................................................... 818 
Table 9.45:  Annual costs to consider in capital costs of feeding systems ............................................. 818 
Table 9.46:  Annual costs to consider in capital costs of housing systems ............................................ 819 
Table 9.47:  Annual costs to consider in capital costs of manure storage systems ................................ 819 
Table 9.48:  Annual costs to consider in capital costs of manure storage systems ................................ 819 

Intensive Rearing of Poultry or Pigs 

xxix 

xxx 

Intensive Rearing of Poultry or Pigs 

SCOPE 

This  BREF  for  the  Intensive  Rearing  of  Poultry  or  Pigs  concerns  the  following  activities 
specified in Section 6.6 of Annex I to Directive 2010/75/EU, namely '6.6. Intensive rearing of 
poultry or pigs':  

Scope 

(a)  with more than 40 000 places for poultry 

(b)  with more than 2 000 places for production of pigs (over 30 kg), or 

(c)  with more than 750 places for sows. 

In particular, this document covers the following on-farm processes and activities: 

 

 

 

 

 

 

 

nutritional management of poultry and pigs; 

feed preparation (milling, mixing and storage); 

rearing (housing) of poultry and pigs; 

collection and storage of manure; 

processing of manure; 

manure landspreading; 

storage of dead animals. 

This document does not address the following processes or activities: 



disposal  of  dead  animals;  this  may  be  covered  in  the  BREF  for  Slaughterhouses  and
Animal By-products Industries (SA);

Other reference documents which are of relevance for the activities covered by this BREF are 
the following: 

Reference documents 

Activity 

Waste Incineration (WI) 

Incineration of manure 

Waste Treatment Industries (WT) 
Monitoring of emissions from IED-
installations (ROM) 
Economics and Cross-media Effects (ECM) 

Composting and anaerobic digestion of manure 

Monitoring of emissions to air and water 

Economics and cross-media effects of techniques 

Emissions from Storage (EFS) 

Storage and handling of materials 

Energy Efficiency (ENE) 

General aspects of energy efficiency 

Food, Drink and Milk Industries (FDM) 

Feed production 

The scope of the BREF does not include matters that only concern safety in the workplace or 
the  safety  of  products  because  these  matters  are  not  covered  by  the  Directive.  They  are 
discussed only where they affect matters within the scope of the Directive. 

Intensive Rearing of Poultry or Pigs 

xxxi 

xxxii

Intensive Rearing of Poultry or Pigs 

Chapter 1 

1  GENERAL INFORMATION 

This  chapter  provides  general information  on  pig  and  poultry  production  in  Europe.  It  briefly 
describes the position of Europe in the world market and developments in the internal European 
market and those of its Member States. It introduces the main environmental issues associated 
with intensive pig and poultry farming. 

For the purposes of this document, the term 'farm' is used as synonymous with 'installation' as 
defined  in  the  Industrial  Emissions  Directive,  which  may  consist  of  one  or  more  stationary 
technical  units  (plants)  and  of  all  the  directly  associated  activities.  Other  terminology  used  in 
this document includes: 







Rearing of poultry: the rearing cycle for the production of eggs or for the production of
meat from chickens, turkeys, ducks, guinea fowl, etc., including parent stock and pullets.

Rearing  of  pigs:  the  rearing  of  animals  of  the  porcine  species,  of  any  age,  kept  for
breeding or fattening.

Rearing  of  sows:  the  rearing  of  female  pigs  including  mating,  gestating  and  farrowing
sows  (including  offspring)  as  well  as  replacement  sows  (which  have  been  selected  or
purchased as replacement breeding stock and are part of the sow herd) and gilts that have
been serviced.

1.1 

Intensive livestock farming 

Farming has been and still is dominated by family-run businesses. Until the mid-1970s, crops 
were  grown  and  different  animal  species  were  reared  in  mixed  farming  systems.  Feed  was 
grown on the farm or purchased locally and manure was returned to the land as fertiliser.  

Since  then,  increasing  market  demands,  the  evolution  of  breeds  due  to  genetic  selection,  the 
development  of  farming  equipment  and  the  availability  of  a  wide  range  of  feedstuff  have 
encouraged  farmers  to  specialise.  As  a  consequence,  animal  numbers  and  farm  sizes  have 
increased and livestock farming has become intensive. Some regions have specialised in animal 
production; scale and agglomeration economies have appeared, leading to areas of high animal 
density.  The  feed  market  has  opened  up  and  feed  materials  have  started  to  be  imported  from 
outside the EU. Intensive farming has thus led to significant imports of nutrients that are then 
returned  to  soil,  in  the form  of  manure,  in different areas to that  where the  feed  material  was 
produced, sometimes in excessive loads. 

Animal density is itself considered a rough indicator of the amount of animal manure produced 
and  therefore  of  the  nutrient  supply  to  the  land,  which  can  exceed  the  requirements  of  the 
agricultural  area  to  grow  crops  or  to  maintain  grassland.  Hence,  data  on  the  concentration  of 
livestock production at a regional level are considered a good indicator of areas with potential 
environmental  problems  (e.g.  eutrophication  of  natural  waters  due  to  excess  nitrogen  and/or 
phosphorus). 

The term ‘livestock units’ (see Section 9.1) can be used in reports to present the total size of the 
livestock  population,  allowing  a  summation  of  animal  species  according  to  their  feed 
requirements. The meaning of the term ‘intensive livestock farming’ in Europe is illustrated by 
using  animal  density  expressed  in  the  number  of  livestock  units  per  hectare  of  utilised 
agricultural area (LU/ha).  

Figure 1.1  shows  the  animal  density  of  all  farmed  livestock  (in  LU/ha)  at  a  regional  level  in 
2010.  In  2010  the  total  livestock  population  in  the  EU-27  amounted  to  134  million  livestock 
units which was a decrease of -2 % compared with 2005. The total livestock density in EU-28 in 
2010  was  0.77  LU/ha.  The  picture  illustrates  that  for  nearly  all  Member  States  the 

Intensive Rearing of Poultry or Pigs 

1 

Chapter 1 

environmental impact of intensive livestock farming is a regional issue, but for a few countries 
like  the  Netherlands  and  Belgium  it  can  almost  be  considered  a  national  issue.  The  total 
livestock density remained more or less stable between 2005 and 2010 in EU-27 [ 2, Eurostat 
2017 ]. Table 1.1 shows the variation of animal density for the years 2007, 2010 and 2013 in the 
EU-28  and  for  each  Member  State,  expressed  in  livestock  units  per  hectare  of  utilised 
agricultural area. 

NB: One livestock unit (1 LU) is defined as the grazing equivalent of one adult dairy cow producing 3 000 kg of milk 

annually, without additional concentrated foodstuffs.  

Source: [ 2, Eurostat 2017 ] 

Figure 1.1:  Animal  density  in  the  European  Union  expressed  as  number  of  livestock  units  per 

hectare of utilised agricultural area in 2010 

2 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Table 1.1:  Animal  density  in  the  EU-28  expressed  as  number  of  livestock  units  per  hectare  of 

utilised agricultural area for the years 2007, 2010 and 2013 

Chapter 1 

Country 

Country 

2013 
2007 
0.29 
2.76 
Belgium 
1.26 
Bulgaria 
0.41 
0.49 
Czech Republic  0.58 
3.21 
1.72 
Denmark 
3.57 
1.06 
Germany 
0.89 
0.35 
Estonia 
0.64 
1.43 
Ireland 
0.56 
0.64 
Greece 
0.38 
0.58 
Spain 
1.00 
0.82 
France 
0.34 
0.90 
Croatia 
0.51 
0.78 
Italy 
0.56 
1.69 
Cyprus 
Latvia 
0.76 
0.28 
NB: One livestock unit (1 LU) is defined as the grazing equivalent of one adult dairy cow producing 

Lithuania 
Luxembourg 
Hungary 
Malta 
Netherlands 
Austria 
Poland 
Portugal 
Romania 
Slovenia 
Slovakia 
Finland 
Sweden 
United Kingdom 

2010 
0.33 
1.28 
0.53 
3.64 
3.58 
0.87 
0.72 
0.60 
0.41 
1.07 
0.35 
0.49 
0.57 
0.79 

2007 
0.39 
1.23 
0.57 
4.80 
3.35 
0.78 
0.72 
0.58 
0.44 
1.13 
0.39 
0.50 
0.57 
0.86 

2013 
2.74 
0.22 
0.50 
1.58 
1.10 
0.32 
1.20 
0.44 
0.62 
0.79 
0.55 
0.77 
1.60 
0.26 

2010 
2.80 
0.26 
0.49 
1.86 
1.07 
0.33 
1.16 
0.46 
0.62 
0.81 
0.78 
0.77 
1.70 
0.26 

3 000 kg of milk annually, without additional concentrated foodstuffs. 

Source: [ 6, Eurostat 2017 ] 

The  areas  with  high  livestock  densities  typically  have  many  intensive  pig  and  poultry  farms, 
each with a large number of animals. For example, the share of pigs and poultry exceeds 50 % 
in  most  of  these  regions  and  poultry  accounts  for  more  than  20 %  of  the  regional  livestock 
population  in  parts  of  France  (Loire  Region,  Brittany),  Spain  (Catalonia)  and  the  United 
Kingdom  (east  England).  In  some  Member  States  there  is  a  decline  in  the  actual  number  of 
farms, but the remaining farms now tend to keep more animals and have higher production.  

Based  on  data submitted  by  Member  States  during  2009–2011,  information  on the  number  of 
farms specified in Section 6.6 of Annex I to the IED is given in Table 1.2.  

Intensive Rearing of Poultry or Pigs 

3 

Chapter 1 

Table 1.2: 

Summary of existing farms requiring a permit by category of activities in Annex I to 
Directive 2010/75/EU (reference period 2012–2013) 

Member 
State 

Total 

Austria 
Belgium 
Flanders 
Wallonia 
Bulgaria 
Cyprus 
Czech Rep. 
Denmark 
Germany 
Estonia 
Greece 
Spain 
Finland 
France 
Hungary 
Italy 
Ireland 
Latvia 
Lithuania 
Luxembourg 
Malta 
Netherlands 
Poland 
Portugal 
Romania 
Slovenia 
Slovakia 
Sweden 
UK 
EU-27 
NB: NI = no information provided. 
Source: [ 607, EIONET COM 2014 ]  

27 
859 
792 
67 
93 
50 
428 
1 245 
2 682 
53 
55 
2 918 
229 
3 189 
581 
1 812 
206 
38 
75 
8 
NI 
2 174 
820 
152 
392 
30 
141 
255 
1 506 
20 018 

Poultry 
6.6 (a) 
22 
448 
415 
43 
49 
20 
238 
NI 
1 465 
7 
46 
544 
131 
2 515 
241 
892 
96 
7 
34 
NI 
NI 
968 
675 
112 
254 
23 
88 
146 
1 299 
11 575 

Pigs 
6.6 (b) 
3 
366 
344 
22 
23 
30 
140 
NI 
931 
46 
3 
1 685 
68 
589 
246 
800 
100 
28 
41 
8 
NI 
903 
96 
36 
125 
6 
46 
98 
163 
6 580 

Sows 
6.6 (c) 
2 
35 
33 
2 
21 
NI 
50 
NI 
286 
0 
6 
689 
30 
85 
94 
120 
10 
3 
NI 
NI 
NI 
303 
49 
4 
13 
1 
7 
11 
44 
1 863 

4 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Chapter 1 

1.2 

The poultry production sector in Europe 

By  far  the  majority  of  poultry  farms  are  part  of  the  production  chain  for  chicken  eggs  or  for 
chicken broilers. A comparatively small number of farms produce turkeys (for meat) and ducks 
(for meat, foie gras or eggs). The value of the eggs and poultry products in the EU-27 in 2012 
was EUR 30 748 million [ 7, DG AGRI 2013 ]. 

The following Sections 1.2.1, 1.2.2 and 1.2.3 briefly describe the poultry sectors in Europe with 
an  emphasis  on  chicken  production.  More  detailed  statistical  data  can  be  found  in  the  annual 
reports  of  the  European  Commission  (DG  Agriculture  and  Eurostat).  Poultry  production  data 
vary by poultry species and poultry breed and also somewhat by Member State, depending on 
market demands. Breeds are either selected for their egg-producing capacities or growing (meat) 
potential. 

Table 1.3 shows some typical production data for some poultry species under the scope of the 
Directive.  

Table 1.3:  Typical poultry rearing data 

Types of animal production 

Production cycle (days) 

Live weight (kg) 

350–450 
33–42 
45–63 
84–150 
63–120 
48–56 
70–85 (2) 
76–80 

Laying hen 
Standard broiler 
Heavy broiler 
Male turkey 
Female turkey 
Pekin duck 
Barbary duck (mixed) 
Guinea fowl 
(1) Requirements are set by Directive 2007/42/EC. 
(2) Lower end of the range corresponds to female and higher to male ducks. 
(3) Values calculated from data (2009) provided by [ 418, ITAVI 2010 ]. 
(4) Values calculated from data provided by [ 328, CORPEN 2006 ]. 
Source:[ 328, CORPEN 2006 ] [ 383, France 2010 ] [ 418, ITAVI 2010 ] [ 500, IRPP TWG 2011 ] [ 633, ITAVI 

1.1–2.0 
1.5–2.6 
2.2–3.3 
10–21 
3.5–15 
2.8–3.75 
3.65–4.0 
1.63–1.78 

Stocking density 
(kg/m2) 
12–36 
up to 39 (1) 
up to 39 (1) 
58–75 
52–75 
20–55 
51–63 (3) 
24–30 (4) 

2013 ]

1.2.1 

Egg production and consumption 

Worldwide, Europe is the second largest producer of hen eggs, producing around 10 % of the 
world total. The supply balance of egg production in the EU-27 is presented in Table 1.4 for the 
years 2010 to 2013.  

Table 1.4:  Balance sheet for total egg production in the EU-27 for the years 2010–2013 

Gross internal production (1 000 t) 
Imports (1 000 t) 
Exports (1 000 t) to non-member countries 
Internal consumption (1 000 t), of which: 

- Eggs for hatching 
- Eggs for human consumption 
Human consumption (kg/head/year) 
Source: [ 673, DG AGRI 2014 ] 

2011 

2013 
2010 
7 297  7 303  7 271  7 333 

2012 

20 
217 

35 
185 

20 
33 
182 
215 
6 885  7 105  7 121  7 138 
880 
812 
6 005  6 231  6 114  6 326 
12.6 
12.6 

1 007 

12.5 

12.2 

874 

Intensive Rearing of Poultry or Pigs 

5 

Chapter 1 

The consumption per capita of eggs did not vary greatly between Member States; according to 
2007 data, it ranges from an average of 8.5 kg per capita in Portugal to 18 kg per capita in Spain 
[ 1, Eurostat 2011 ]. 

Eggs  for  human  consumption  are  produced  in  all  Member  States.  In  the  year  2012,  the  top 
producer  Member  States  were  France  (856  kt),  Spain  (862  kt),  Italy  (698  kt),  and  Germany 
(826 kt).  In  2011,  the  main  exporters  to  non-member  countries  of  eggs  for  consumption  were 
the  Netherlands  with  53 %  of  the  total  EU-27  exports,  Germany  (13.1 %),  Poland  (10.6 %), 
Spain (6.8 %) and France (5.9 %). 

Table 1.5  presents  the  total  number  of  laying  hens  in  Member  States  for  the  years  2012  and 
2013 and the total usable production of eggs for the year 2013.  

Table 1.5:  Number of laying hens and usable production of eggs (total eggs) in EU-27 Member 

Number of laying hens (thousands) (1) 

States 

Belgium 
Bulgaria 
Czech Republic 
Denmark 
Germany 
Estonia 
Ireland 
Greece 
Spain 
France 
Italy 
Cyprus 
Latvia 
Lithuania 
Luxembourg 
Hungary 
Malta 
Netherlands 
Austria 
Poland 
Portugal 
Romania 
Slovenia 
Slovakia 
Finland 
Sweden 
United Kingdom 

2012 
9 190 
3 859 
5 081 
3 429 
47 334 
741 
2 764 
NI 
38 350 
45 945 
61 226 
435 
2 193 
2 430 
NI 
5 939 
NI 
29 570 
5 902 
35 309 
4 857 
6 520 
1 466 
3 586 
4 031 
7 009 
35 857 
363 024 

2013 
8 442 
3 995 
5 563 
3 304 
49 903 
998 
2 827 
3 791 
38 409 
47 041 
60 312 
427 
2 665 
2 479 
103 
5 671 
NI 
32 924 
5 962 
37 649 
7 235 
6 589 
1 467 
2 582 
4 151 
7 053 
36 626 

Change (%) 
-8.1 
3.5 
9.5 
-3.6 
5.4 
34.7 
2.3 
NI 
0.2 
2.4 
-1.5 
-1.8 
21.5 
2.0 
NI 
-4.5 
NI 
11.3 
1.0 
6.6 
49.0 
1.1 
0.1 
-20.5 
3.0 
0.6 
2.1 

Total eggs 
(1 000 t) 
2013 
163 
78 
73 
78 
847 
11 
46 
100 
862 
918 
691 
8 
41 
51 
(2) 
165 
5 
704 
99 
637 
127 
301 
21 
76 
67 
104 
711 

6 982 

EU-27 
(1) Data gathered on the basis of Article 31 of Regulation (EC) 589/2008. 
(2) Included in Belgium. 
NB: NI = no information provided. 
Source: [ 673, DG AGRI 2014 ] 

378 437 

4.2 

6 

Intensive Rearing of Poultry or Pigs 

Chapter 1 

From 1 January 2012, keeping hens in conventional cages was prohibited and egg producers had 
to  change  to  either  enriched  cages  or  alternative  housing  systems.  The  transition  to  full 
compliance  with  Council  Directive  1999/74/EC  laying  down  minimum  standards  for  the 
protection  of  laying  hens  encountered  difficulties.  In  Europe,  in  2008,  278 million  hens  were 
still  reared  in  conventional  cage  systems,  of  which  only  about  7 %  were  in  enriched  cages. 
However,  57 %  of  EU  citizens  were  prepared  to  pay  more  for  eggs  sourced  from  animal 
welfare-friendly production [ 20, COM 2008 ]. 

In northern Europe, non-cage egg production has gained popularity since the end of the 1990s. 
In Austria, conventional cages were prohibited at the end of 2008, and enriched colonies will 
also be banned by 2020, whilst in Germany, conventional cages were prohibited at the end of 
2009. In Sweden, conventional cages ceased to be used by the end of 2002 and only enriched 
colony systems are permitted since then [ 5, The Poultry Site 2017 ]. 

The  production  chain  of  the  egg  production  sector  is  a  sequence  of  different  activities,  each 
representing one breeding or production step  (see Figure 1.2). The breeding, hatching, rearing 
and egg laying often take place at different sites and on different farms to prevent the  possible 
spread  of  diseases.  Layer  farms,  particularly  the  larger  ones,  often  include  the  grading  and 
packing of eggs, after which the eggs are delivered directly to the retail (or wholesale) market. 

Source: [ 24, LNV 1994 ] 

Figure 1.2:  Example of the production chain of the egg production sector 

Intensive Rearing of Poultry or Pigs 

7 

Chapter 1 

The other egg-producing sectors (in particular ducks) represent only a very small portion of the 
rearing  activity  in  comparison  with  the  chicken  egg  production  sector.  Little  information  is 
available in relation to the structure, position and development of these sectors. 

1.2.2 

Poultry meat production and consumption 

The supply balance of poultry meat in the EU-27 is presented in Table 1.6 for the years 2011 to 
2013. 

Table 1.6:  Balance  sheet  for  poultry  meat  production  (in  carcass  weight)  in  the  EU-27  for  the 

years 2011–2013 

2011 
13 205 
1.0 
7.7 
13 198 
819 
1 288 
12 792 

1 000 t (1)
2012 
13 474 
1.2 
9.3 
13 466 
840 
1 323 
12 982 

23.9 

23.7 

2013 
13 718 
1.1 
9.4 
13 710 
787 
1 311 
13 187 

NI 

Gross internal production 
Imports - live animals 
Exports - live animals 
Usable production 
Imports 
Exports with non-member states 
Internal use 
Gross consumption 
(kg/head/year) 
(1) Carcass weight.  
NB: NI = no information provided. 
Source: [ 673, DG AGRI 2014 ] 

In 2009, Cyprus recorded the highest per capita consumption of poultry meat (45 kg). Portugal 
and Greece recorded an annual consumption of poultry meat averaging respectively 34 kg and 
30 kg per capita [ 1, Eurostat 2011 ].  

According  to  another  survey,  in  2012,  the  total  poultry  meat  production  in  the  EU-27  was 
12.9 million tonnes. This  represents an increase of 14 % compared to 2007. The main poultry 
meat  is  broiler  meat  with  a  total  production  of  9.9  million  tonnes  in  2012.  There  are  seven 
leading producers of broiler meat, each with a production of more than 0.7 million tonnes: the 
UK,  Poland,  Germany,  France,  Spain,  Italy  and  the  Netherlands;  these  countries  account  for 
76 %  of  the  EU's  poultry  meat  production.  Besides  broilers,  turkeys  and  ducks  are  also 
important  subsectors.  Total  turkey  meat  production  in  the  EU-27  in  2012  was  1.9  million 
tonnes. The main producing countries of turkey meat are France, Germany, Poland, Italy and the 
UK, with a common share of 81 % of the EU total. The total duck meat production in the EU-27 
was 0.5 million tonnes. Of all EU countries, France is by far the largest producer of duck meat 
with  almost  half  of the total  EU  production, followed  by  Hungary  and  Germany.  These three 
countries have a common  share of 74 % of the EU total. Other poultry relates to guinea fowl 
and  goose.  Table 1.7  gives  an  overview  of  the  total  poultry  meat  production,  subdivided  by 
broilers, turkeys, ducks and other poultry, for the EU-27 Member States [ 588, LEI Wageningen 
2013 ]. 

8 

Intensive Rearing of Poultry or Pigs 

Table 1.7:  Poultry meat production in the EU-27 (in thousand tonnes of carcass weight) in 2012 

Chapter 1 

EU Member 
State 

Broilers 

Turkeys 

Ducks 

Belgium 
Bulgaria 
Czech Republic 
Denmark 
Germany 
Estonia 
Ireland 
Greece 
Spain 
France 
Italy 
Cyprus 
Latvia 
Lithuania 
Luxembourg 
Hungary 
Malta 
Netherlands 
Austria 
Poland 
Portugal 
Romania 
Slovenia 
Slovakia 
Finland 
Sweden 
United Kingdom 
EU-27 
(1) Calculated figures: Other poultry = Total poultry – (Broilers+Turkeys+Ducks). 
(2) Included in Belgium. 
Source: [ 588, LEI Wageningen 2013 ] 

Other 
poultry (1) 
1 
5 
1 
5 
75 
2 
0 
17 
71 
118 
144 
1 
0 
3 
(2) 
43 
0 
28 
14 
0 
19 
0 
0 
4 
0 
2 
0 
553 

0 
21.7 
4.8 
0 
63.6 
0 
4.2 
0.2 
6.0 
235.8 
14 
0 
0 
0.3 
(2) 
69.6 
0 
17 
0.1 
17 
8.5 
0 
0 
0.4 
0 
0 
33 
496 

246 
78 
158 
175 
1 150 
14 
116 
160 
1 063 
1 080 
817 
27 
24 
77 
(2) 
280 
4 
738 
91 
1 325 
258 
340 
55 
68 
99 
80 
1 400 
9 923 

3 
0 
8 
0 
387 
0 
9 
3 
111 
415 
286 
1 
0 
0 
(2) 
95 
0 
27 
25 
290 
39 
10 
7 
14 
8 
4 
177 
1 919 

Total 
poultry 
250 
105 
172 
180 
1 676 
16 
129 
180 
1 251 
1 849 
1 261 
29 
24 
80 
(2) 
488 
4 
810 
130 
1 632 
324 
350 
62 
86 
107 
86 
1 610 
12 891 

% of EU-27 
total 
1.9 
0.8 
1.3 
1.4 
13.0 
0.1 
1.0 
1.4 
9.7 
14.3 
9.8 
0.2 
0.2 
0.6 
(2) 
3.8 
0.0 
6.3 
1.0 
12.7 
2.5 
2.7 
0.5 
0.7 
0.8 
0.7 
12.5 
100.0 

Table 1.8  presents  the  total  number  of  chicks  hatched  of  table  strains  for  the  years  2012  and 
2013.  

Intensive Rearing of Poultry or Pigs 

9 

 
 
 
 
 
 
Chapter 1 

Table 1.8:  Number  of  utility  chicks  of  table  strains  hatched  (in  thousands  of  heads)  in  EU-27 

Member States 

EU Member State 

2012 

2013 

Change (%) 

Belgium 

Bulgaria 

120 918 

128 607 

45 852 

42 450 

Czech Republic 

130 429 

120 547 

Denmark 

Germany 

Estonia 

Ireland 

Greece 

Spain 

France 

Italy 

Cyprus 

Latvia 

Lithuania 

Hungary 

Malta 

NI 

NI 

738 396 

741 093 

NI 

NI 

73 275 

71 816 

NI 

NI 

616 240 

612 174 

884 907 

888 577 

515 802 

522 182 

12 735 

15 966 

46 276 

10 985 

17 289 

48 419 

143 886 

144 244 

NI 

NI 

Netherlands 

387 257 

403 161 

Austria 

Poland 

Portugal 

Romania 

Slovenia 

Slovakia 

Finland 

Sweden 

69 933 

68 851 

729 435 

809 964 

204 113 

204 964 

257 733 

242 256 

2 311 

49 023 

64 203 

NI 

1 964 

58 191 

66 193 

NI 

United Kingdom 

916 438 

946 234 

EU-27 
NB: NI = no information provided. 

6 025 130  6 150 160 

Source: [ 673, DG AGRI 2014 ] 

6.3 

-7.4 

-7.4 

NI 

0.4 

NI 

-2.0 

NI 

-0.6 

0.4 

1.2 

-13.7 

8.3 

4.6 

0.2 

NI 

4.1 

-1.5 

11.0 

0.4 

6.0 

-15.0 

18.7 

3.1 

NI 

3.2 

2.1 

The  production  of  broilers  is  the  main  subsector  of  the  poultry  meat  production  chain.  The 
different steps in the broiler production chain are shown in Figure 1.3. The majority of poultry 
meat production is based on an all-in, all-out system applying littered floors. Broiler farms with 
over  40 000  bird  places  are  quite  common  in  Europe.  The  EU  broiler  meat  sector  commonly 
uses fast-growing genotypes which achieve the target live weight of 2–2.5 kg in around 5 to 6 
weeks, after which the broilers are delivered to the slaughterhouse.  

10 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 1 

Source: [ 24, LNV 1994 ] 

Figure 1.3:  Example of the production chain of the broiler production sector 

1.2.2.1 

Alternative poultry meat production 

Alternative  broiler  production  that  may  use  slower-growing  genotypes  is  increasingly  gaining 
attention in many EU countries. The poultry meat of such breeding programmes is a premium 
product, and farmers and processors receive a higher market price to compensate for the higher 
production costs. The conditions and names of the alternative broiler production in the EU are 
regulated by Regulation 543/2008, in which the marketing terms are described. The production 
of organic broilers is regulated in Regulation 834/2007, including the requirement to use organic 
feed. These requirements are summarised in Table 1.9. 

Table 1.9:  Marketing  terms  and  conditions  for  production  of  alternative  broilers,  according  to 

Regulations (EC) 543/2008 and 834/2007 (organic) 

Production system 

Extensive indoor  
Free-range  
Traditional free-range  
Free-range, total freedom  
Organic  
Source: [ 588, LEI Wageningen 2013 ] 

Minimum age 
(days) 
56  
56  
81  
81  
70 to 81  

Maximum indoor 
density (birds/m2) 
15  
13  
12  
12  
10  

Access to outdoor run 

No  
Yes, 1 m2 per bird  
Yes, 2 m2 per bird  
Yes, 2 m2 per bird  
Yes, 2 m2 per bird  

The number of farms with free-range or organic production is small, except in France where a 
large  number  of  farms  are  involved  in  alternative  broiler  production.  In  organic  production, 
France and the UK are the largest producers within the EU. In free-range production systems, 
broilers have access to an outdoor area for at least half of their lifetime. An example of this type 
of broiler production is 'Label Rouge' in France, with the following standards: a slow-growing 
breed, a low indoor density and access to an outdoor area. In France, about 12 % of all broilers 
have access to an outdoor run. 

The  so-called  intermediate  market  segment  or  certified  broiler  production  has  a  position 
between regular broiler production and organic production. Certified broilers are slow-growing 
broilers that are kept indoors until they are at least 56 days old. Certified broilers are produced 
in France ('certifié'), the UK ('Freedom Food') and the Netherlands (one star within the 'Better 
Life  Certificate').  France,  the  UK  and  the  Netherlands  hold  a  significant  position  in  this 
production  segment,  but  Germany  also  has  some  companies  that  have  started  to  produce 
certified broilers. This type of production is expected to grow further in the coming years.  

Intensive Rearing of Poultry or Pigs 

11 

 
 
 
 
 
 
 
 
 
 
Chapter 1 

No statistics are available on the exact numbers of alternative broilers in the EU. It is estimated 
that the market share of alternative broilers is 5–10 % including the market for organic and free-
range  broilers,  as  defined  by  EU  regulations  and  directives,  as  well  as  the  numbers  for 
'backyard' poultry production in some southern European countries and private label production, 
such as 'Label Rouge' in France, 'Freedom Food' in the UK and intermediate extensive indoor 
production in the Netherlands [ 588, LEI Wageningen 2013 ].  

Similar  types  of  farming  to  those  described  for  broilers  are  also  defined  in  Regulations  (EC) 
543/2008  and  834/2007  for  all  poultry  species  for  meat  production  such  as  turkeys,  ducks, 
guinea fowl and geese.  

1.2.3 

Economics of the poultry sector 

The majority of poultry farms are family-run enterprises. Some farms belong to large integrated 
companies  carrying  out  all  the  activities  of  a  production  line,  from  production  (hatching, 
rearing,  slaughtering,  transport)  to  retail  and  including  animal  feed  supply. The  net  margin  of 
poultry farms varies in each Member State and depends on production costs and product price. 
Production costs may consist of: 

 

 

 

 

 

 

 

costs for chicks (meat production) or pullets (cost of young hens at 16–20 weeks, less the 
revenue from the end-of-lay hens); 

feed costs during the growing or the laying period; 

variable  costs  (water  and  litter  costs,  veterinary  costs,  energy  costs,  cleaning  and 
disinfecting costs); 

manure management costs; 

labour costs; 

housing costs (maintenance of equipment and buildings, depreciation costs, interest); 

general costs.  

The gross income of a farm depends on the number of eggs or kg of live weight that can be sold 
and the prices the farmer receives (including the price of end-of-lay hens). The prices of poultry 
products are not guaranteed or fixed and fluctuate in the market. In some Member States (e.g. 
France, Germany, the UK, Italy), contracts are stipulated between farmers and buyers to reduce 
price fluctuations. This market is in turn affected by the dynamics and the structure of the large 
grocery retailers, who are the main outlets for the poultry products and are therefore responsible 
for the majority of the annual turnover of poultry products. 

1.2.3.1 

Economics of the egg production sector 

The  layer  sector  had  to  deal  with  additional  costs  related  to  the  implementation  of  Council 
Directive  1999/74/EC  as  egg  producers  had  to  change  conventional  cages  to  either  enriched 
cages or alternative housing systems from 1 January 2012. It is also evident that increasing the 
space  allowance  per  bird  in  enriched  cages  or  in  non-cage  systems  will  provoke  additional 
poultry house costs and as a result the investment in housing and equipment will increase. 

Production costs for different laying hen rearing systems in Europe are reported in Table 1.10, 
as calculated by an extensive study on the competitiveness of the EU egg industry, together with 
the basic assumptions made for the technical performance (egg production, mortality and daily 
feed intake), labour input and investment costs. For the purpose of comparison to the situation 
before the year 2012, conventional cages are also displayed. 

12 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 1 

According to the results of this study, the average production costs in the EU of eggs produced 
in  enriched  cage  systems  were  calculated  to  be  7  %  higher  and  the  production  costs  of  eggs 
produced  in  an  aviary  system  22 %  higher  in  comparison  to  conventional  cages  providing 
550 cm2 per hen. This means that the market price should be higher to keep the egg producer's 
income  at  a  constant  level.  In  this  context  it  should  also  be  mentioned  that  other  alternative 
housing systems, like free-range and organic, have higher production costs than enriched cages 
and  aviaries.  Eggs  produced  in  these  systems  need  an  even  higher  bonus  from  the  market  to 
compensate the egg producer for the additional costs [ 392, LEI Wageningen 2012 ]. 

However, consumers regard free-range and organic eggs in a positive manner; this demand can 
sustain higher market prices [ 5, The Poultry Site 2017 ]. 

Table 1.10:  Comparison of production costs for rearing systems for laying hens at EU level 

Conventional cage (1)  Enriched cage 

Aviary 

400 
340 
7 
111 
60 000 
35 
1 909 
6.05 
6.5 
2.7 

Production parameters and main assumptions for costs  
Laying period (days) 
Eggs per hen  
Mortality (%) 
Daily feed consumption per hen (g) 
Number of birds managed per worker 
Stocking density (birds/m2) 
Surface area per house (m2) 
Housing investment (EUR/bird) 
Inventory investment (EUR/bird) 
Other inventory investment (EUR/bird) 
Production costs per hen housed (EUR/bird) 
3.30 
Pullet at 17 weeks 
10.29 
Feed costs 
1.29 
Other variable costs 
1.91 
Housing 
0.99 
Labour 
0.37 
General costs 
0.27 
Revenue end-of-lay hen 
17.89 
Total cost 
0.052 6 
Total cost per egg  
0.85 
Total cost per kg of eggs  
Difference % (2)  
NR 
(1) Conventional cages have been banned since January 2012. 
(2) Calculated on the basis of 550 cm2 per hen in conventional cages.  
NB: NR = not relevant. 
Source: [ 392, LEI Wageningen 2012 ] 

400 
340 
7 
111 
55 000 
27 
2 237 
7.73 
10.60 
2.95 

3.30 
10.29 
1.51 
2.75 
1.10 
0.41 
0.27 
19.10 
0.056 2 
0.91 
7 

392 
326 
9 
123 
40 000 
18 
2 414 
11.47 
9.00 
4.5 

3.70 
11.07 
1.39 
3.08 
1.51 
0.51 
0.26 
20.99 
0.064 4 
1.04 
22 

From  the  same  study,  the  costs  of  egg  production  (in  conventional  cages)  in  several  EU 
countries are presented in Table 1.11 as calculated for the year 2010 in order to give an insight 
into  the  build-up  of  production  costs  at  EU  level.  The  differences  are  mainly  caused  by 
differences  in  feed  costs,  the  price  of  young  hens  (pullets),  housing  costs  and  manure 
management  (disposal)  costs.  All  countries  have  revenue for  spent  hens, except  for  Denmark, 
where egg producers have to pay for rendering. In Spain and Poland there is revenue for manure 
disposal.  

Intensive Rearing of Poultry or Pigs 

13 

 
 
 
 
 
 
 
 
 
 
 
Chapter 1 

Table 1.11:  Prices, technical performance and production costs for egg production in selected EU 

countries in 2010 

NL  FR  ES 

IT  UK  PL  DK  EU 

400 
332 
63 

410 
345 
64 

392 
330 
63 

392 
340 
62.5 

Prices and technical performance 
Feed price (EUR/100 kg) 
22.0  23.0  23.5  24.0  24.8  23.5  21.8  23.2 
Pullet cost at 20 weeks (EUR/pullet)  3.57  3.84  3.89  3.85  4.38  3.49  4.70  3.96 
396 
Laying period (days) 
389 
369 
420 
343 
Number of eggs produced per hen 
339 
363 
322 
61.4  62.3 
Egg weight (g)  
61.6  62.5 
2.01  2.13  2.07  2.02  2.15  2.12  1.99  2.07 
Feed conversion ratio 
Mortality (%) 
6.6 
8.0 
Production costs (euro cents/kg of eggs) 
Hen cost at 20 weeks 
Feed 
Other variable costs 
Labour 
Housing 
General 
Manure management  
Revenue for spent hen 
Total production costs 
Source: [ 392, LEI Wageningen 2012 ] 

16.0  19.2  17.6  18.5  20.6  16.7  22.2  18.7 
44.2  49.0  48.6  48.5  53.2  49.8  43.3  48.1 
5.5 
5.9 
6.5 
4.0 
3.7 
4.5 
7.0 
6.9 
8.0 
1.0 
1.0 
1.1 
0 
0.7 
2.6 
-1.0 
-1.1 
-1.1 
84 
82.0  84.5 

7.0 
6.5 
4.7 
3.8 
8.3 
7.5 
1.1 
1.0 
1.5 
1.7 
-1.5 
1.2 
85.9  88.8  78.2  89.3 

4.8 
3.2 
5.7 
0.9 
-0.2 
-1.7 
79 

4.7 
2.2 
5.5 
0.8 
-0.3 
-1.3 

6.5 
3.2 
6.1 
1.1 
0.0 
-1.9 

8.0 

5.0 

7.0 

6.0 

7.0 

5.0 

Another  example  of  a  breakdown  of  production  costs  for  different  rearing  systems  for  egg 
production is shown in Table 1.12, where French national averages for the year 2011 are shown. 
Production costs were derived according to the technical performance of the farms and taking 
into account investment and financial costs as well as costs for feed, pullets, labour and all other 
variable cost factors. 

Table 1.12:  Average performance data and production costs for egg production in France for the 

year 2011 

Enriched cages  Free-range (2)   Organic  Barn 

Technical performance 
Stocking density (birds/m2 of usable 
area) 
Laying period (days) 
Empty period (days) 
Mortality (%) 
Number of eggs produced per hen 
Weight of eggs produced per hen (kg) 
Feed conversion ratio (kg of feed/100 
kg of eggs) 
Production costs (EUR/hen) 
Feed cost  
Labour costs  
Pullet cost  
Investment cost, financial cost and 
other fixed costs  
Variable costs (water, electricity, 
cleaning and disinfection etc.)  
Total production cost  
Total production cost (EUR/100 eggs) 
(1) 750 cm2/bird. 
(2) French specification 'Label Rouge'. 
NB: NI = no information provided. 

Source: [ 417, ITAVI 2012 ] 

(1) 

380.3 
22.04 
5.89 
314.9 
20.17 

2.18 

11.27 
0.73 
3.18 

3.35 

0.71 

19.24 
6.11 

8.29 

347.4 
27.1 
7.45 
284.7 
16.98 

2.57 

12.29 
3.05 
3.27 

3.71 

0.83 

23.15 
8.13 

6.41 

9.00 

353.2 
27.3 
6.96 
291.6 
17.46 

363.1 
NI 
8.12 
299.2 
18.58 

2.49 

2.35 

22.89 
3.81 
4.82 

11.97 
1.83 
3.13 

4.82 

3.7 

0.9 

0.84 

37.24 
12.79 

21.47 
7.17 

14 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
The  evolution  of  the  weekly  EU  average  price  for  Class  A  egg  is  shown  in  Figure 1.4  while 
Figure 1.5 presents the yearly average market price for eggs in Member States. 

Chapter 1 

Source: [ 698, DG AGRI 2014 ] 

Figure 1.4:  Evolution of the weekly EU average price for Class A eggs in packing stations for the 

period 2009 to 2014 

Source: [ 673, DG AGRI 2014 ] 

Figure 1.5:  Market  prices  for  eggs  from  caged  hens  (average  for  categories  L  and  M)  for  the 

period 2011 to 2013  

1.2.3.2 

Economics of the poultry meat production sector 

An  example  of  production  costs  for  the  poultry  meat  sector  is  shown  in  Table 1.13,  where 
French national averages for the year 2009 are displayed. The calculations include investment 
costs,  feed  costs,  fixed  costs  (chicks,  financial  expenses,  water,  etc.),  and  variable  costs 
(heating, electricity, etc.) for fully equipped housing. 

Intensive Rearing of Poultry or Pigs 

15 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 1 

Table 1.13:  Average  performance  data  and  production  costs  for  meat  poultry  species  in  France 

for the year 2009 

Parameter 

Standard 

Broiler 

Heavy 

'Certified' 

'Label' 

Turkey 

Duck 

Male  Female  Male  Female 

Guinea 
fowl 

17.1 

3.74 

17.9 

11.0 

7.9 

4.88 

3.27 

2.53 

14.9 

3.44 

58.5 

87.6 

120.7 

88.0 

84.4 

70.2 

77.2 

2.22 

2.3 

12.9 

6.5 

4.6 

2.5 

2.16 

3.2 

2.4 

2.4 

2.8 

2.8 

2.64 

3.60 

6.87 

4.1 

1.7 

2.8 

5.5 

0.938 

1.607 

1.137 

1.271–1.299 

1.593 

37.7 

22.8 

6.51 

Stocking 
density 
(birds/m2) 
Production 
cycles per year 
Age at 
slaughter 
(days) 
Live weight at 
slaughter (kg)  
Feed 
conversion 
ratio 
Mortality 
(%) 
Production 
cost (EUR/kg 
live weight) 
Source: [ 418, ITAVI 2010 ] 

0.831 

4.18 

1.8 

1.9 

The  production  costs  for  broilers  at  farm  level  have  been  calculated  for  nine  Member  States 
based on the situation in 2011. Table 1.14 gives the average price of feed and day-old chicks as 
well as the average feed conversion as a good indicator of the production efficiency. The price 
of feed strongly affects the total production costs and it is influenced by the world market prices 
of  the  main  feed  ingredients,  such  as  grains  (wheat  and  maize)  and  soybean  meal.  The 
difference in feed price between the EU countries is a result of differences in the structure of the 
supply  chain  (integrated  versus  non-integrated),  average  farm  size,  feed  mill  policy,  average 
transport distance to farms and optimal position with access to sea harbours and waterways for 
efficient supply of feed ingredients. Growing broilers to a higher final weight also results in a 
higher feed intake per kg of growth. 

Table 1.14:  Prices, technical performance and production costs for broiler production in selected 

EU countries in 2011 

NL 

DE 

FR  UK 

IT 

ES 

DK 

PL 

HU 

2.46 
2.2 
1.85 
1.67 
33.8 
40.1 
0.306  0.311  0.31  0.367  0.355  0.316  0.317  0.311  0.308 

2.1 
1.65 
32.8 

2.7 
1.95 
34.6 

1.92 
1.75 
32.8 

2.3 
1.76 
34.5 

2.3 
1.8 
32 

2.3 
1.75 
35.4 

2.2 
1.68 
34.5 

Prices and technical performance 
Live weight (kg)  
Feed conversion  
Feed price (EUR/100 kg) 
Day-old chick (EUR)  
Production costs (EUR cents/kg of live weight) 
16.6 
16.9 
Day-old chicks 
61.9 
57.4 
Feed 
7.4 
8.2 
Other variable costs 
3.1 
4.9 
Labour 
7.0 
6.5 
Housing 
1.1 
1.1 
General 
0.0 
Manure management  
-0.1 
Total production costs 
94.9  96.9 
NB: NI = no information provided. 
Source: [ 588, LEI Wageningen 2013 ] 

14.4 
56.4 
8.6 
4.4 
5.4 
1.1 
0.9 
91.2 

14.7 
57.9 
8.6 
4.5 
5.8 
1.1 
0.4 
92.9 

15.1 
74.1 
7.5 
2.6 
6.2 
1.0 
NI 
106.5 

12.2 
67.4 
5.8 
2.9 
5.9 
0.9 
NI 
95.2 

15.7 
54.1 
9.3 
4.6 
6.5 
1.1 
0.0 
91.4 

14.1 
60.7 
7.2 
1.4 
5.9 
0.8 
-0.1 
90.2 

13.9 
57.6 
8.9 
2.3 
8.0 
0.8 
0.3 
91.8 

16 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 1 

Data in the above table show that EU countries also differ in some other cost components. Other 
variable  costs  relate  to  heating,  electricity,  litter,  animal  health  and  catching.  These  variable 
costs  vary  slightly  between  countries,  mainly  because  of  differences  in  heating  costs  (fuel 
prices) and costs of catching. Labour costs also differ between countries. Normally, the work on 
the farm is done by the farmer. The differences in housing costs (poultry house and inventory) 
between the countries relate to differences in investments for a poultry house, stocking density 
and  interest  rate.  General  costs  relate  to  the  costs  at  farm  level  for  insurance,  bookkeeping, 
consultancy,  communication  and  transport.  In  some  countries  broiler  farmers  have  manure 
management  costs.  In  the  Netherlands,  Germany  and  Hungary  farmers  have  to  pay  for  a 
sustainable management (disposal) of manure. In other countries, farmers do not have to pay for 
manure disposal, while in the UK and Poland farmers even get a small revenue. 

Poultry meat prices are also subject to fluctuations. The evolution of the monthly average price 
for broiler meat in the EU is shown in Figure 1.6. Figure 1.7 shows the yearly average market 
price for broiler meat in Member States. 

Source: Data derived from the price reporting system established with Regulation (EC) 546/2003 [ 10, CIRCA 2012 ] 

Figure 1.6:  Evolution  of  monthly  EU  average  selling  price  in  slaughter  plants  for  broilers 

(wholesale price for class A chicken) for the period 2006 to 2012 

Intensive Rearing of Poultry or Pigs 

17 

 
 
 
 
 
 
 
Chapter 1 

Source: [ 673, DG AGRI 2014 ] 

Figure 1.7:  Market prices for broilers for the period 2011 to 2013  

18 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Chapter 1 

1.3 

The pig production sector in Europe 

1.3.1 

Structure, trends and geographical distribution of the pig 
production sector in Europe 

Pig meat is produced throughout the EU on several types of farms with considerable variations 
from one Member State to another. In 2012, the value of the pig sector agricultural products in 
the EU-27 was EUR 37 785 million [ 7, DG AGRI 2013 ]. 

According  to  the  'Farm  structure  survey'  carried  out  by  all  Member  States  on  the  basis  of 
Regulation (EC) 1166/2008, in 2015 the total pig population in the EU-28 was 148.7 million, 
consisting of 41.7 million piglets  with a live weight of less than 20 kg, 12.3  million breeding 
sows reflecting the permanent pig herd and 60.2 million fattening pigs with 50 kg or over [ 699, 
Eurostat 2017 ]. A detailed breakdown for the EU-28 is presented in Table 1.15. 

Table 1.15:  Pig population in the EU-28 in 2015 (in thousands) 

Total population 
Piglets, < 20 kg 
Breeding sows 
Covered sows 
Sows not covered 
Breeding pigs (breeding sows + boars) 
20 kg < pigs < 50 kg 
Fattening pigs, ≥ 50 kg 
50 kg < fattening pigs < 80 kg 
80 kg ≤ fattening pigs < 110 kg 
Fattening pigs ≥ 110 kg 
Breeding boars 
Sows covered for the first time 
Gilts not yet covered 
NB: 'Gilts not yet covered' and 'Sows covered for the first time' are 

148 724.2 
41 704.9 
12 301.8 
8 411.1 
3 888.7 
12 502.8 
34 271.1 
60 245.2 
27 599.7 
24 111.9 
8 534.6 
201.1 
1 500 
1 490.8 

also included in 'Fattening pigs'. 

Source: [ 699, Eurostat 2017 ] 

The trend of the pig livestock population over the period 2007–2015 confirms a decrease in the 
total  number  of  pigs  (-7.6 %).  The  number  of  breeding  sows  has  declined  (-98.3  %)  and  the 
same  behaviour  is  observed  for  fattening  pigs  over  50  kg  (-6.1 %).  The  number  of  piglets 
decreased by around 3.8 % from 2007 to 2015 [ 699, Eurostat 2017 ].  

The  total  number  of  sows  represents  the  production  capacity.  Between  2008  and  2013,  the 
number  of  sows  fell  by  13.5 %.  In  the  13  newest  Member  States  the  reduction  was  steeper  
(-20 %) than in the EU-15 (-8 %). The decrease affects pig farms of all sizes, including larger 
farms (>200 sows). Such extreme changes are a combination of several factors,  which have a 
varying impact depending on the structure of pig production. The general decrease concerns all 
countries,  but  one  underlying  reason  is  the  concentration,  i.e.  an  increase  in  the  size  of  the 
largest farms to the detriment of the smallest farms (e.g. in Belgium, Germany, Estonia, France, 
Latvia, Lithuania, the Netherlands, Austria, Portugal and Finland). However, the decrease in the 
total number of sows is balanced by a gain in productivity [ 3, Eurostat 2014 ]. Other reasons for 
the contraction in the EU pig herd are the high feed costs throughout 2012 and the first half of 
2013 together with the new welfare rules in the sow sector [ 7, DG AGRI 2013 ]. 

Intensive Rearing of Poultry or Pigs 

19 

 
 
 
 
 
 
 
 
 
 
 
Chapter 1 

Germany, Spain, France, Denmark, Poland and the Netherlands are the major producers at EU 
level, with more than two thirds of the breeding pigs [ 699, Eurostat 2017 ]. At regional level, 
data  are  more  informative  than  national  figures  as  a  means  of  displaying  the  zones  of  pig 
production (see Figure 1.8). The most important zone extends from Denmark through northern 
Germany and into the Netherlands and Belgium. Pig farming is particularly concentrated in the 
Danish  regions  of  Capital  (region),  Central  Jutland  and  North  Jutland.  A  particularly  high 
concentration of pigs per km2 could also be observed in the Dutch region of North Brabant and 
the Belgian region of West Flanders as well as in the German regions of western Lower Saxony 
(districts  of  Cloppenburg  and  Vechta) and the  northern  parts  of  North  Rhine-Westphalia. The 
location  of  pig  farming  is,  to  some  degree,  reliant  upon  easy  access  to  animal  feed  and,  in 
particular, cereals. Some areas with a high concentration of pig farming are close to sea ports, 
which may be used to import feed. Otherwise, the distribution of pig farms across the EU can be 
linked to consumer preferences for different types of meat and to the complementary nature of 
different types of pig farming (breeders, fatteners, etc.). There were also other regional pockets 
where  the  density  of  pigs  is  relatively  high:  these  included  Catalonia,  Aragon  and  Murcia  in 
Spain, Brittany in north-west France, Lombardy in northern Italy, and Wielkopolskie in central 
Poland [ 4, Eurostat 2014 ] [ 15, Eurostat 2014 ]. 

Pig farms vary considerably in size. The latest data collected by the 'Farm structure survey' on 
the distribution of the pig population by size of the herds (in numbers of 'other pigs') show that 
about three quarters of other pigs (77.9 %) and about half of the sows (48.6 %) are reared by 
just 1.7 % of the largest farms (those with more than 400 'other pigs').  At the EU level, small 
units (less than 10 other pigs) rear 3.8 % of 'other pigs' and they account for 73.3 % of the pig 
farms [ 4, Eurostat 2014 ]. 

Small pig producers are mostly found in the 13 Member States that joined the EU since 2004, 
which leads to a decreasing herd size. According to the 'Farm structure survey' of 2010, the 13 
newest  Member  States  accounted  for  2.9 %  of  the  breeding  sows  overall,  but  only  62.9 %  of 
these sows are in farms with at least 10 sows and 41 % are in herds of 100 to 199 sows. Animals 
kept  in  small  units  of  less  than  10  other  pigs  are  important  in  Romania  (62.8 %),  Croatia 
(45.3 %), Slovenia (31.4 %), Lithuania (28.8 %) and Bulgaria (25.8 %) [ 4, Eurostat 2014 ]. 

In  addition,  almost  half  of  the  'other  pigs'  (41.6 %)  are  reared  by  fatteners,  i.e.  farms  without 
sows. The large fatteners (at least 400 'other pigs') account for more than one third of other pigs 
in  ten  countries  (Belgium,  Denmark,  Germany,  Spain,  Italy,  Luxembourg,  the  Netherlands, 
Finland,  Sweden  and  the  United  Kingdom).  They  reflect  a  production  organised  between 
specialised breeding farms and fatteners. These 10 countries represent two thirds of the 'other 
pigs'  production  and  three  quarters  of  the  EU  pork  production.  In  France  the  distribution  is 
balanced between typical fatteners and large breeders. The large breeders (at least 400 pigs and 
100 sows) manage more than two thirds of the 'other pigs' in six countries (the Czech Republic, 
Estonia, Ireland, Greece, Cyprus and Portugal). This class represents also half of the EU-28 sow 
herd [ 4, Eurostat 2014 ].  

In  the  UK,  approximately  40 %  of  the  total  438 000  breeding  sows  are  reared  outdoors  in 
rotational systems. This type of rearing scheme is not included in the statistics of the permitted 
farms given in Table 1.2. 

The figures on the changing structure of the average unit size related to 2010 are presented in 
Table 1.16.  More  detailed data about  the  pig  population  and  the  exact  distribution  of  national 
herds by size can be taken from the 'Farm structure survey'. 

20 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 1 

Source: [ 4, Eurostat 2014 ] 

Figure 1.8:  Pig density by region (in average number per km2) in 2013  

Intensive Rearing of Poultry or Pigs 

21 

 
 
 
 
 
 
 
 
Chapter 1 

Table 1.16:  Pig  population  and  changing  structure  of  pig  farms  by  herd  size  class  in  the  EU-28, 

2005-2010 

Holdings (x 1 000) 

Animals (x 1 000) 

Average number of 
animals per holdings 

EU Member State  2005  2007  2010 

2005 

2007 

2010 

2005  2007  2010 

NI 

303 
75 

341 
128 

895 
6 
252 

818 
5 
207 

6 430 
670 
1 908 

6 256 
848 
2 876 

7 
154 
11 
7 
79 
3 
1 
33 
108 
106 
35 
101 
1 
30 
95 
0 
283 
0 
9 
45 
664 
67 

8 
191 
15 
9 
89 
5 
1 
45 
116 
NI 
42 
103 
1 
39 
152 
0 
316 
0 
10 
52 
702 
83 

Belgium 
Bulgaria 
Czech Republic 
Denmark 
Germany 
Estonia 
Ireland 
Greece 
Spain 
Croatia 
France 
Italy 
Cyprus 
Latvia 
Lithuania 
Luxembourg 
Hungary 
Malta 
Netherlands 
Austria 
Poland 
Portugal 
Romania 
Slovenia 
Slovakia 
Finland 
Sweden 
United Kingdom 
EU-28 
NB: NI = no information provided. 
Source: [ 7, DG AGRI 2013 ] 

1 092 
6 318 
8 
932 
477 
3 019 
13 534  13 723  13 173  1 500  1 903  2 598 
459 
26 858  27 059  27 571 
389 
370 
251 
355 
1 516  1 977  2 007  1 253 
1 606 
1 660 
1 017 
947 
1 112 
22 777  23 424  24 712 
1 501 
1 575 
14 793  14 283  13 922 
9 331 
9 040 
8 758 
330 
458 
424 
383 
419 
430 
860 
956 
1 200 
84 
90 
83 
3 208 
3 823 
3 860 
71 
79 
73 

49 
354 
12 
569 
356 
524 
21 
14 
598 
18 
543 
11 312  11 663  12 255  1 167  1 342  1 743 
3 147 

6 
82 
4 
5 
60 
2 
1 
19 
70 
128 
24 
26 
1 
18 
63 
0 
183 
0 
7 
38 
3 247 
388  17 717  18 512  15 244 
1 913 
50 
5 345 
382 
588 
1 367 
1 520 
4 443 

60 
25 
22 
3 
15 
24 
455 
649 
424 
3 822  3 624  2 883  154 626  157 245  153 311  40.5 

1 834 
1 753  1 698  1 656  4 936 
505 
1 005 
1 401 
1 811 
4 860 

86 
39 
38 
3 
14 
55 
657 
894 
445 
53.2 

71 
28 
27 
3 
17 
21 
513 
732 
495 
43.4 

23 
197 
NI 
353 
85 
706 
11 
8 
429 
12 
523 

33 
217 
15 
405 
90 
619 
14 
10 
463 
14 
564 

1 799 
4 709 
544 
837 
1 448 
1 676 
4 833 

26 
11 
2 
2 
10 

32 
40 
3 
2 
10 

34 
42 
3 
3 
11 

3 235 

1.3.2 

Production and consumption of pork 

The  EU-27  accounts  for  22.8 %  of  the  world  pork  production,  with  22.7  million  tonnes  of 
carcass  weight  of  the  nearly  one  hundred  million  tonnes  produced  in  the  whole  world 
(99 532 328 t) [  17,  FAO 2009  ].  For  comparison,  pork  production totals  more  than  twice the 
carcass weight of beef and veal. 

Figure 1.9 shows the decrease registered for the slaughter of cattle, sheep and goats since 2005, 
whilst at the same time the increase in the total weight of pigs and poultry slaughtered, leading 
to an overall expansion in meat production within the EU-28.  

22 

Intensive Rearing of Poultry or Pigs 

  
 
 
 
 
 
 
 
Chapter 1 

Source: [ 16, Eurostat 2017 ] 

Figure 1.9:  Production of meat by type of animal (in tonnes) in the EU-28 

The average weight to which pigs are finished and their average carcass weight vary throughout 
the EU. This has a significant impact in relation to the period of time that the pigs are housed, 
the  quantity  of  feed  consumed,  and  the  volume  of  effluent  produced.  For  example  in  Italy, 
heavy pigs are reared to an average live weight of 156 kg, yielding a carcass weight of 112 kg. 
The types of pig production carried out in the EU are listed below: 

 

'Continental' pig, produced in Germany, the Netherlands, Austria, Belgium and France, 
with a carcass weight of around 90 kg. 

  British  pig,  with  a  90–105 kg  live  weight  and  a  79  kg  average  carcass  weight.  Also 

produced in Spain. 

  Danish pig, intermediate between continental and British types. 

 

 

Italian heavy pig. Standard pigs are also produced in Italy [ 383, France 2010 ]. 

Iberian pig, with a 150 kg live weight and a 120 kg carcass weight [ 624, IRPP TWG 
2013 ]. 

Not all of this production is consumed in the Member States themselves. As a whole, the EU is 
a net exporter of pork, importing only a very small amount (see Table 1.17). Not every major 
producer is an exporter. Denmark, the Netherlands, Belgium and Spain are large exporters, Italy 
and  UK  are  net  importers  while  Germany  and  France  are  net  exporters  to  a  lesser  extent  
[ 383, France 2010 ]. The supply balance for pig meat in the EU-27 is presented in Table 1.17 
for the years 2010 to 2013. 

Intensive Rearing of Poultry or Pigs 

23 

 
 
 
 
 
 
 
 
 
Chapter 1 

Table 1.17:  Balance sheet for pig meat production (in carcass weight) in  the EU-27 for the years 

2010–2013  

Gross internal production (1 000 t) 
Imports - live animals (1 000 t) 
Exports - live animals (1 000 t) 
Usable production (1 000 t) 
Imports (1 000 t) 
Exports (1 000 t) with non-member states 
Internal consumption (1 000 t) 
Per capita consumption (kg/head/year) 
NB: NI = no information provided. 

Source: [ 673, DG AGRI 2014 ] 

2010 
22 209 
0.12 
75.5 
22 133 
22 
1 839 
20 316 
40.8 

2011 
22 503 
0.02 
66.2 
22 437 
15 
2 175 
20 278 
40.7 

2012 
22 026 
0.02 
36.6 
21 990 
16 
2 182 
19 824 
39.7 

2013 
22 012 
0.02 
23.5 
21 989 
15 
2 177 
19 827 
NI 

The  annual  consumption  for  pork  products  averages  around  40 kg  per  capita,  a  level  that  is 
higher  than  the  combined  total  of  poultry,  cattle,  sheep  and  goats.  In  2009  Denmark  had  the 
highest overall consumption of meat in the EU, 81 kg per capita. Austria and Germany average 
in excess of 50 kg, while the United Kingdom, Bulgaria and Greece recorded per capita is below 
30 kg [ 1, Eurostat 2011 ]. 

With  varying  live  weights  at  the  end  of  the  finishing  period,  the  period  of  time  needed  for 
rearing  a  pig  also  varies  in  the  EU.  Many  factors  influence  this,  such  as  the  feeding,  farm 
management and market demands requiring a certain quality of pork meat.  

Table 1.18  presents  the  physical  performance  data  concerning  the  production  of  pigs  for  a 
selected sample of EU countries. 

24 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Table 1.18:  Summary  of  physical  performance  data  for  the  production  of  pigs  for  selected  EU 

countries (year 2009) 

Performance 

DK 

FR 

DE 

UK 

IT 

NL 

ES 

SE 

EU 
Average 

Chapter 1 

31 

19 

35 

48 

45 

51 

61 

60 

52 

51 

51 

819 

753 

785 

898 

437 

285 

362 

450 

492 

440 

475 

460 

25.1 

36.6 

29.9 

31.4 

1.97 

1.70 

1.54 

2.02 

1.80 

1.70 

1.69 

1.70 

23.9 

31.57 

27.45  26.16 

2.32 
52.7 
23 

2.38 
42.0 
25 

2.2 
51.3 
34 

24.7 
2.33 
45.4 
25 

21 
2.23 
48.1 
28 

22.47 
2.3 
43.2 
27 

22.25  22.64  27.19  23.71  23.19 

21.69  26.03  21.81  22.11 
2.22 
34.0 
27 

Pigs weaned per sow per 
year  
Pigs sold per sow per year   25.63 
Litters per sow per year  
2.25 
Sow replacement rate (%)   53.8 
31 
Lactation period (days)  
Post-weaning daily live 
weight gain (g/day)  
Post-weaning feed 
conversion ratio  
Average number of days 
in post-weaning unit  
Transfer weight to 
finishing unit (kg)  
Finishing daily live 
weight gain (g/day)  
Finishing feed conversion 
ratio  
Average number of days 
in finishing unit  
Finishing pigs' feed 
consumption (kg) per pig  
Finishing ration average 
energy content (MJ 
ME/kg)  
Finishing mortality (%)  
Pigs per pig place per year 
(finishing)  
Average live weight at 
slaughter (kg)  
Average carcass weight - 
cold (kg)  
Carcass meat production 
per sow per year (kg)  
Average lean meat 
percentage (%) 
NB: NI = no information provided. Finishing = the rearing phase after post-weaning until slaughter.  

2 064  2 189  2 084  1 643  2 781  2 349  1 729  1 924 

12.32 

12.96 

13.32 

12.7 

13.8 

3.60 

3.10 

3.20 

0.70 

2.40 

4.80 

2.40 

4.06 

3.19 

2.89 

4.13 

1.72 

2.93 

2.59 

3.49 

60.2 

60.1 

56.5 

62.0 

47.0 

56.4 

58.0 

57.7 

4.10 

12.8 

13.2 

2.66 

2.85 

2.92 

2.77 

3.68 

2.71 

2.71 

2.83 

107 

116 

120 

103 

166 

117 

105 

117 

128 

203 

243 

265 

187 

483 

250 

236 

242 

107 

119 

205 

116 

134 

640 

792 

643 

876 

NI 

89 

93 

81 

78 

90 

79 

87 

84 

81 

98 

24.32 

23.01 
2.28 
45.5 
27 

423 

1.78 

53 

30.03 

767 

2.89 

116 

256 

11.83 

3 

3.14 

117 

90 

2 062 

58 

Source: [ 415, BPEX 2010 ] 

Depending on the final slaughter weight, the castration of male piglets is a practice still in use to 
avoid  boar  taint.  While  alternatives  to  castration  are  being  investigated,  the  debate  on  the 
practice  in  relation  to  the  production  systems  and  efficiency,  and  the  use  of  anaesthetic  is 
ongoing. As an example, in the UK, over 90 % of British pigs are produced on farms which are 
members  of  a  recognised quality  assurance  scheme  that  does not allow  the  castration of  male 
pigs.  

1.3.3 

Economics of the pig sector 

The economy of European pig production is driven by the choices of the Common Organisation 
of  Agricultural  Markets,  for  which  the  key  factor  is  competitiveness,  even  if  there  are  small 
niche markets. Prices mostly reflect the situation of supply and demand, while the EU Common 
Agricultural  Policy  only  indirectly  affects  the  pig  sector  by  shifting  crop  production.  Market 
crises are recurrent and there is little public financial support for European pig production. For 

Intensive Rearing of Poultry or Pigs 

25 

 
 
 
 
 
 
 
Chapter 1 

more  efficiency,  the  trend  is  towards  concentration  in  larger  farms  and  in  specialised  regions 
(economy of scale and agglomeration). The efficiency of the whole chain, and not only of the 
farm,  is  important  [  383,  France  2010  ].  The  economics  of  pig  production  are  also  largely 
dictated by the availability of feed, or easy access to transport, and suitable markets. This has 
led to regional development of the industry. 

Environmental constraints and financial drivers for better nutrient recovery within pig farming 
have led to a link between production and the availability of land for spreading manure. Manure 
(solid  or  slurry)  has  a  nutrient  value  for  crops  and  when  used  in  accordance  with  crop 
requirements  is  a  valuable  fertiliser.  When  landspread  it  adds  both  major  and  minor  plant 
nutrients (predominantly nitrogen and phosphorus) to the soil which can leach into ground and 
surface  waters.  This  can  be  a  problem  where  there  are  concerns  over  eutrophication  of  water 
bodies  and/or  nitrate  levels  in  drinking  water  sources.  Where  sufficient  land  for  spreading  is 
available,  manure  can  be  applied  beneficially  without  a  potential  risk  of  water  pollution  by 
nitrates. Where  manure transportation  is possible,  wider  spreading  areas are  reached,  albeit  at 
higher costs. In this respect, differences exist across countries.  

In Denmark, the pig population is spread across the entire country, and therefore it has only a 
relatively average pig density associated with the cultivated land area. The mixed livestock and 
arable farming systems that are used in Denmark and Germany also allow the use of generated 
manure with a reduced environmental risk. The association with mixed farming also provides 
benefits in terms of feed costs. In contrast, in some Member States (e.g. the Netherlands) a small 
land area is associated with livestock farms, and the quantities of manure produced are so large 
that farmers pay to have it removed. In others, the manure has sufficient value that farmers can 
sell it or at least give it to other farmers [ 204, IMPEL 2009 ]. 

Pig density in Spain as a whole is very low, but there is a concentration of intensive pig farming 
and  other  agricultural  activity  in  the  northern  autonomous  communities  (e.g.  in  Catalonia).  It 
has been stated that the manure landspreading is of great agronomic interest to Spain as, along 
with  the  savings  on  mineral  fertilisers,  it  can  also  improve  the  structure  and  fertility  of  most 
Spanish  soils  and  can  contribute  significantly  to  the  fight  against  desertification.  These 
favourable  circumstances  support  the  growth  of  the  sector  and  even  the  setting  up  of  foreign 
companies.  

Generally, pig production in the EU does not tend to show the level of vertical integration found 
in  the  poultry  sector,  for  instance  the  breeding  and  finishing  of  pigs  are  often  carried  out  in 
separate  facilities.  In  the  latest  years,  there  has  been  a  tendency  towards  a  more  integrated 
approach  with  an  individual  or  company-based  control  of  feed  supply,  pig  production  and 
slaughtering  capacities.  There  is  also  a  trend  that  even  in  situations  where  breeding  and 
finishing are undertaken at separate sites these may be owned by a single producer. The most 
developed  integrated  production  systems  are  in  Denmark  and  fall  under  the  guidance  of  the 
Federation  of  Danish  Pig  Producers  and  Slaughterhouses  (Danske  Slagterier).  Examples  of 
vertical integration can be found also in Spain and Belgium [ 383, France 2010 ]. 

Where investments are made, there are a variety of reasons why farmers might decide to invest 
in environmental techniques. Often, national legislation pushes them towards the application of 
certain techniques, but also the requirements of the large grocery retailers can affect the choice 
and  operation  of  production  techniques,  as  happens  in  egg  production.  Increasing  attention  is 
being paid to animal welfare issues, such as the use of straw and access to an outdoor area. It 
should be borne in mind that techniques applied under the scope of animal welfare legislation 
are not always associated with the best environmental performance. 

In the UK as an example, some producers in the pig production sector moved to straw bedding 
systems  to  meet  the  desires  of  pork  customers,  particularly  on  welfare  grounds.  This  change 
applies  especially  to  loose-housed  dry  sows  (as  in  the  Netherlands)  and  eventually  provoked 
discussions  about  the  environmental  disadvantages  that  may  occasionally  result  from  some 
practices (e.g. use of straw). In the UK, many of the pigs that are fattened on straw are sourced 

26 

Intensive Rearing of Poultry or Pigs 

  
 
 
 
 
 
Chapter 1 

from outdoor sow herds, giving an example of a niche market with an integrated supply chain 
from producer to retailer. 

Some Member States set up public programmes for limited periods to encourage farmers to take 
action  or  to  adopt  techniques  in  order  to  reduce  emissions  to  the  environment.  Hence,  some 
farmers  are  able  to  access  financial  assistance  to  invest  in  improved  manure  management 
techniques  (e.g.  in  Finland,  financial  support  was  available  for  liquid  manure  injection)  
[ 26, Finland 2001 ] [ 37, BOE España 2009 ] [ 383, France 2010 ]. 

The economic viability of techniques or combinations of techniques is related to the economic 
profitability  of  the  sector  or  farm,  where  profitability  depends  on  production  costs  and  sales 
income. Table 1.19  shows the financial  performance data  for the  year 2014,  together  with  the 
variability of production costs across the EU. The evolution of the total production costs of pig 
meat across the EU during the period 2009–2014 is displayed in Table 1.20. The evolution of 
market  prices for  pig  meat  in  the  EU is presented  in  Figure 1.10  while  Figure 1.11  shows  the 
yearly average market price for pig meat in Member States from 2010 to 2013. 

Table 1.19:  Summary of financial performance in the year 2014 in selected countries (in EUR per 

kg deadweight (1))  

Production cost 
breakdown 

BE  CZ  DK  FR  DE  UK 

IE 

IT  NL  ES 

SE  EU 

Feed 

1.04  0.95  0.91  0.95  0.94  1.05  1.17  1.32  0.95  1.04  1.00  1.02 

Other variable costs  0.20  0.47  0.26  0.23  0.30  0.27  0.26  0.25  0.32  0.20  0.27  0.27 

Total variable costs 

1.23  1.41  1.17  1.19  1.23  1.32  1.43  1.57  1.27  1.23  1.26  1.30 

Labour  

0.12  0.11  0.14  0.15  0.15  0.17  0.12  0.17  0.16  0.09  0.19  0.15 

Depreciation and 
finance 

0.19  0.14  0.21  0.21  0.22  0.22  0.19  0.20  0.20  0.14  0.38  0.21 

Total fixed costs 

0.31  0.25  0.35  0.36  0.37  0.38  0.31  0.38  0.35  0.23  0.57  0.36 

Total production 
costs 
(1) Values in EUR as per exchange GBP/EUR = 0.81. 
NB: Figures may not add up due to rounding. 

1.54  1.65  1.52  1.54  1.60  1.72  1.74  1.94  1.62  1.47  1.83  1.65 

Source: [ 382, BPEX 2016 ] 

Intensive Rearing of Poultry or Pigs 

27 

 
 
 
 
 
 
 
 
 
 
Chapter 1 

Table 1.20:  Changes in total production costs in  the EU for the years 2009–2014 (in EUR per kg 

deadweight) 

2009 

2010 

2011 

2012 

2013 

2014 

EU Member 
State 
AT 
BE 
CZ 
DK 
FR 
DE 
UK 
IE 
IT 
NL 
ES 
SE 
EU 

1.45 
1.41 
1.73 
1.42 
1.41 
1.54 
1.50 
1.48 
1.74 
1.45 
1.44 
1.48 
1.50 
NB: Figures may not add up due to rounding.  
Source: [ 382, BPEX 2016 ] 

1.61 
1.48 
1.85 
1.41 
1.42 
1.52 
1.68 
1.52 
1.79 
1.42 
1.42 
1.72 
1.57 

1.68 
1.61 
1.78 
1.59 
1.65 
1.76 
1.78 
1.72 
1.96 
1.62 
1.60 
1.97 
1.73 

1.78 
1.73 
1.86 
1.68 
1.66 
1.82 
1.91 
1.84 
1.98 
1.68 
1.64 
2.14 
1.74 

1.79 
1.74 
1.84 
1.68 
1.71 
1.82 
1.89 
1.93 
2.01 
1.77 
1.64 
2.08 
1.74 

1.65 
1.56 
1.65 
1.53 
1.56 
1.63 
1.74 
1.77 
1.96 
1.64 
1.49 
1.86 
1.58 

Source: [ 25, BPEX 2015 ] 

Figure 1.10:  Evolution of pig meat market prices on weekly basis (EUR/100 kg deadweight) in  the 

EU-28, January 2009 - February 2015 

28 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 1 

Source: [ 673, DG AGRI 2014 ]  

Figure 1.11:  Market prices for pig meat  

The  European  Commission  and  Member  States  are  progressively  introducing  rules  to  oblige 
industry and farmers to commit to minimising greenhouse gas (GHG) emissions as part of the 
actions  implementing  the  Kyoto  Protocol.  Provisions  that  could  be  introduced  may  become  a 
significant driver in the future and may affect the costs of production. In the UK, the strategy on 
low carbon emissions (Low Carbon Transition Plan) moved the English pig industry to organise 
an action plan on greenhouse gases (Roadmap and Greenhouse Gas Action Plan). 

Intensive Rearing of Poultry or Pigs 

29 

 
 
 
 
 
 
 
Chapter 1 

1.4 

Environmental issues of intensive poultry or pig farming 

Environmental issues have only been on the agricultural agenda for a relatively short period of 
time.  It  was  not  until  the  1980s  that  the  environmental  impact  of  intensive  livestock  farming 
really  became  an  issue.  Awareness  of  the  implications  of  farming  activities  such  as  excess 
manure application and its impact on soil and water quality and odour nuisance has increased 
over the years, due to an increasing population in rural areas. 

The growing concerns about climate change focused attention on the emissions from the entire 
livestock sector. According to the FAO, 14.5 % of human-induced GHG emissions are related 
to  livestock  production  [  18,  FAO  2013  ].  On  a  global  scale,  the  greater  contributions  come 
from  enteric  fermentation  by  ruminant  animals  and  deforestation  related  to  feed  crops,  whilst 
emissions from pig and poultry farms contribute to a lesser extent.  

According  to  another  published  article,  livestock  sector  contributes  to  78 %  for  terrestrial 
biodiversity  loss,  80 %  for  soil  acidification  and  air  pollution  (ammonia  and  nitrogen  oxides 
emissions), 81 % for global warming, and 73 % for water pollution (both N and P) [ 523, Leip 
et al. 2015 ]. 

The  existence  of  livestock  farms  near  areas  of  particular  protection  or  interest  (e.g.  sites  of 
specific scientific interest, wildlife and geological areas or where vegetation is very sensitive) 
may  lead  to  stricter  local,  regional  and/or  national  legal  requirements  and  additional 
improvement  conditions.  This  may  be  the  case  for  the  EU  Natura  2000  sites,  those  in  the 
vicinity  of  residential  areas,  or  close  to  other  farms  where  a  cumulative  impact  of  dust  and 
odour may occur. 

One of the major challenges in the modernisation of poultry and pig production is the need to 
balance the reduction or elimination of the polluting effects on the environment with increasing 
animal  welfare  demands,  while  at  the  same  time  maintaining  a  profitable and  economically 
viable business. In addition, food security has become a real concern  for governments and the 
public.  The  European  agricultural  industry  has  to  operate  in  the  global  food  market  with 
technological  advances  which  simultaneously  aim  to  achieve  economic  efficiency,  safeguard 
animal and consumer health, and protect the environment.  

Potentially, agricultural activities on intensive poultry and pig farms can contribute to a number 
of negative environmental consequences (see also Figure 1.12): 

 

 

 

 

 

 

 

 

 

 

surface water and groundwater pollution (e.g. NO3

- and NH4

+); 

acidification (NH3 mainly, H2S, NOX, etc.); 

eutrophication (N, P); 

airborne pollution, in particular ammonia (NH3), N2O, NO, dust (PM10 and PM2.5),  bio-
aerosols, etc.; 

increase of the greenhouse effect (CO2, CH4, N2O, etc.); 

desiccation (groundwater use); 

local disturbance (odour, noise); 

diffuse spreading of heavy metals, pesticides and toxic substances; 

spreading of pathogens including antibiotic-resistant pathogens;  

residues of pharmaceuticals in waters. 

An  integrated  accounting  of  the  environmental  impacts  of  pig  or  poultry  farming  should 
consider  the  flow  of  manure  and  nutrients  along  the  whole  production  chain.  Positive 
environmental aspects of intensive livestock farming  also exist, e.g.  manure use for anaerobic 
digestion, manure substituting manufactured mineral fertiliser.  

30 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 1 

Source: [ 29, Pahl 1999 ] 

Figure 1.12:  Illustration  of  the  potential  negative  environmental  aspects  related  to  intensive 

livestock farming 

The key on-farm environmental aspect of intensive livestock production is related to the natural 
living processes, i.e. that the animals metabolise feed containing nutrients absorbed by the feed 
crop.  Some  of  the  nutrients  are  then  retained  in  the  animals,  while  the  rest  are  excreted  via 
manure. The quality and composition of the manure and the way it is stored and handled are the 
main factors determining the emission levels of intensive livestock production. 

From  an  on-farm  environmental  point  of  view,  the  efficiency  with  which  pigs,  for  example, 
convert feed  for  maintenance,  growth, and  breeding  is  important. The  pigs’ requirements  will 
vary  during  different  stages  of their  life,  e.g.  during  the  rearing  and  growth  periods  or  during 
different  stages  of  their  reproductive  life.  To  be  sure  that  their  nutritional  requirements  are 
always  met,  it  has  become  customary  to  feed  nutrients  at  levels  in  excess  of  the  animals’ 
requirements.  At  the  same  time,  emissions  of  nitrogen  into  the  environment  can  be  observed 
which are partly due to this imbalance. The process of nitrogen consumption, utilisation and loss 
in  the  production  of  pigs  for  slaughter  is  quite  well  understood.  Nutritional  management  as  a 
preventive  measure  aims  to  improve  the  efficiency  with  which  dietary  nitrogen  is  retained  in 
body tissue (see Figure 1.13 for the basic situation).  

Animal  welfare  and  health  are  linked  and  should  be  taken  into  account  when  considering  the 
impacts of diseases [ 708, EC 2016 ]. 

Intensive Rearing of Poultry or Pigs 

31 

 
 
 
 
 
 
 
 
Chapter 1 

NB: The relative contribution of the sow is also included. Basic situation without nutritional management. 
Source: [ 34, Ajinomoto 2000 ] 

Figure 1.13:  Nitrogen consumption, utilisation and losses in the  production of a pig for  slaughter 

with a final live weight of 108 kg 

1.4.1 

Emissions to air 

Emissions to air from the production systems for the intensive rearing of poultry or pigs can be 
summarised as shown in Table 1.21. 

Table 1.21:  Emissions to air from the intensive rearing of poultry or pigs  

Air 

Production system 

Ammonia (NH3) 

Animal housing, manure storage, processing and landspreading 

Odour 

Dust (bioaerosols) 

Methane (CH4) 
Nitrous oxide (N2O) 

NOX (NO + NO2) 

Carbon dioxide (CO2) 

Animal housing, manure storage and landspreading 
Animal housing, milling and grinding of feed, feed storage, solid manure 
storage and landspreading, heaters in buildings and small combustion 
installations  
Animal housing, storage of manure and manure processing  

Animal housing, manure storage, processing and landspreading 
Animal housing, manure storage and landspreading, heaters in buildings 
and small combustion installations 
Animal housing, energy used for heating and transport on farm, and 
biogenic CO2 that may be emitted in the field 

Ammonia emissions 
Most attention has been paid to the emission of ammonia from livestock production, as this is 
considered  an  important  compound  for  the  acidification  of  soil  and  water.  The  subsequent 
impacts of ammonia deposition to land can be significant, including adverse effects on aquatic 
ecosystems  in  rivers  and  lakes,  and  damage  to  forests,  crops  and  other  vegetation.  Ammonia 
contributes also to eutrophication in water and soil by nitrogen enrichment with adverse effects 
in aquatic ecosystems, loss of biodiversity, etc. 

Furthermore,  ammonia  reacts  with  atmospheric  acids,  forming  (secondary)  particles  that 
contribute significantly to the burden of particulate matter in the atmosphere, which is likely to 
threaten human health [ 337, Webb et al. 2005 ]. As a secondary particle precursor, ammonia 
plays  an  important  part  in  the  long  range  transport  of  the  acidic  pollutants,  having 
environmental  effects  beyond  an  individual  region  [  474,  VDI  2011  ].  The  1979  Geneva 
Convention  on  Long-range  Transboundary  Air  Pollution  is  an  important  measure  for  globally 
protecting  the  environment  against  air  pollution.  The  1999  Gothenburg  Protocol  which 

32 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 1 

originated from the Convention is aimed at reducing acidification, eutrophication and ground-
level ozone. Annex IX to the Protocol includes measures for the control of ammonia emissions. 

Agriculture  was  responsible  for  94 %  of  EU-28  NH3  emissions  in  2011  [  706,  EEA  2017  ]. 
Between  1990  and  2014,  NH3  emissions  in  the  EU-28  dropped  by  24 %.  The  Member  States 
that  contributed  most (i.e. more  than  10 %)  to  NH3  emissions in  2014  were  Germany,  France 
and  Italy  [  697,  EEA  2016  ].  Commitments  from  EU  Member  States  to  reduce  ammonia 
emissions and other atmospheric pollutants have been adopted in Directive 2016/2284 [ 700, EC 
2016 ]. The contribution of IED pig and poultry farms tot the total NH3 emissions is relatively 
large, because of the large percentage of animals (around 20 %) that fall under the IED [ 707, 
Alterra 2007 ]. 

Emissions  of  ammonia  occur  at  all  stages  of  manure  management.  Ammoniacal  nitrogen  in 
livestock excreta is the main source of NH3. In animal houses, it is volatilised from the manure 
and  spreads  through  the  farm  building  and  is  eventually  removed  by  the  ventilation  system. 
Factors such  as  the  temperature,  ventilation rate, humidity,  stocking  density,  litter  quality  and 
feed composition (crude protein) can all affect ammonia levels. Factors that influence the rate of 
ammonia emissions from animal houses are presented in Table 1.22. For example in pig slurry, 
urea  nitrogen  represents  more  than  95 %  of  the  total  nitrogen  in  pig  urine.  As  a  result  of 
microbial urease activity, this urea can rapidly be converted into volatile ammonia. The rate of 
conversion  depends  on  the  pH  of  the  manure  and  other  environmental  parameters  (e.g. 
temperature). 

Table 1.22:  Overview of processes and factors involved in ammonia release from animal houses 

Processes 

Faeces production 

Nitrogen components and 
appearance 
Uric acid/urea (70 %)  
+ undigested proteins (30 %) 

Degradation  

Ammonia/ammonium in manure 

Volatilisation 

Ammonia in air 

Removal  
Emission 

Ammonia in animal house 
Ammonia in environment 

Affecting factors 

Animal and feed 

Process conditions of manure e.g. T, pH, Aw, 
airflow at floor level, urease activity  
Process  conditions,  local  climate,  exposed 
surface  and  contact  time  of  manure/slurry 
with the air 
Ventilation: T, RH, air velocity 
Air cleaning 

NB: T = temperature, pH = acidity, Aw = water activity, RH = relative humidity. 

Ammonia gas has a sharp and pungent odour and in higher concentrations in animal houses can 
irritate the eyes, throat and mucous membranes in humans and farm animals. In many Member 
States  workplace  regulations  set  upper  limits  for  the  acceptable ammonia  concentration  in 
working environments. In general, the generation of gaseous substances in the animal  housing 
also  influences  the  indoor  air  quality  and  can  affect  the  animals’  health  and  create  unhealthy 
working conditions for the farmer. 

The average amount of ammonia emissions in the EU-27 expressed in kg of nitrogen per kg of 
produced pork is estimated equivalent to 28 g. Based on this value, the total ammonia emissions 
for the whole European pig sector are estimated to be 606 ktonnes of nitrogen per year. Average 
ammonia emissions per kg of poultry meat and eggs are estimated at a level of 20 g and 12 g 
respectively.  Total  ammonia  emissions  from  EU  poultry  meat  production  amount  to  217 
ktonnes of N, while total emissions for EU egg production sum up to 88 ktonnes of N per year. 
The methodology applied took into account all on-farm emissions related to livestock rearing, as 
well as the emissions associated with the production of feed and emissions caused by input of 
mineral fertilisers, pesticides, energy and land for the production of feed [ 416, COM 2010 ]. 

Intensive Rearing of Poultry or Pigs 

33 

 
 
 
 
 
 
 
 
 
Chapter 1 

The  E–PRTR  for  2014  shows  that  the  largest  share  by  far  of  ammonia  emissions  from  the 
industry sectors covered by the E-PRTR originates from the intensive rearing of poultry or pigs. 
In particular, 6 669 registered farms for the intensive rearing of pigs or poultry with ammonia 
emissions  of  more  than  10  t/year  emitted  a  total  of  178.4  ktonnes  of  ammonia  to  air, 
representing  83.2  %  of  the  total  ammonia  emissions  from  all  industry  sectors  covered  by  the  
E–PRTR (see Figure 1.14) [ 45, E-PRTR 2017 ]. 

NB: Coverage: EU-27 plus Iceland, Liechtenstein, Norway and Serbia; industry sectors covered by Annex I to the  
E-PRTR with capacity thresholds described therein; farms with emissions of ammonia of more than 10 t/yr; 
normal operation.  
Source: [ 45, E-PRTR 2017 ] 

Figure 1.14:  Emissions of ammonia to air by industry sector/activity in Europe in 2014 

Greenhouse gases 
Greenhouse  gases  have  an  effect  on  global  warming  in  relation  to  their  potential  for  trapping 
heat  in  the  atmosphere.  Methane  (CH4)  and  nitrous  oxide  (N2O)  are  the  most  important 
greenhouse gases associated with animal farming and their global warming potential for a time 
horizon of 100 years is 25 (CH4) and 298 (N2O) times greater than CO2.  

Emissions  of  CH4  and  N2O  from  livestock  production  are  regulated  as  part  of  the  Paris 
Agreement  under  the  United  Nations  Framework  Convention  on  Climate  Change.  The  EU 
reduction  target  for  GHG  is  20 %  by  2020,  with  reference  to  1990,  with  a  proposed  further 
reduction target of 40 % by 2030 [ 701, COM 2014 ]. 

The  amount  of  CH4  generated  by  a  specific  manure  management  system  is  affected  by  the 
extent of anaerobic conditions present, the temperature of the system, and the retention time of 
organic  material  in the  system.  When  manure  is stored  or  treated as  a liquid  (e.g.  in  lagoons, 
tanks,  or  pits),  it  decomposes  anaerobically  and  can  produce  a  significant  quantity  of  CH4. 
When manure is handled as a solid (e.g. in stacks or piles) or when it is deposited on pastures 
and rangelands, it tends to decompose under more aerobic conditions and less CH4 is produced  
[ 659, IPCC 2006 ]. 

Most  of  the  nitrous  oxide  in  livestock  systems  occurs  through  the  microbiological 
transformation of  nitrogen and  this involves  three  main  processes:  nitrification, denitrification 
and  autotrophic  nitrifier  denitrification.  For  denitrification  to  occur,  anaerobic  conditions  are 

34 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 1 

necessary,  while  nitrification  occurs  under  aerobic  conditions.  Not  much  is  known  about  the 
nitrifier denitrification pathway, but it is believed to be similar to denitrification. Under partial 
or  transient  anaerobic  conditions,  the  denitrification  reaction  is  uncompleted,  resulting  in  the 
production  of  NO  and  N2O.  Apart from  the  lack  of oxygen  availability,  denitrification is  also 
favoured by the presence of an available carbon source and warm temperatures, among others. 
Because of this dependence upon such site-specific factors, emissions of N2O exhibit a rather 
high degree of spatial and temporal variability [ 551, Oenema et al. 2005 ]. 

Soil microbial processes (denitrification processes) produce nitrous oxide, and nitrogen gas (N2) 
which is harmless to the environment. Both can be produced from the breakdown of nitrate in 
the soil, whether derived from manure, mineral fertilisers or the soil itself, but the presence of 
manure  encourages  this  process.  Livestock  housing  itself,  particularly  littered  systems,  is  an 
additional source of N2O emissions [ 570, ALTERRA 2000 ]. 

The IPCC factor [ 550, IPCC 2006 ] for direct N2O-N emissions from mineral/organic fertiliser, 
crop residues and N mineralised as a result of soil C loss is 0.01 kg N2O-N/kg N applied. The 
IPCC emission factor for indirect N2O-N emissions is 0.010 kg N2O-N/kg (NH3-N + NOX-N) 
volatilised and 0.007 5 kg N2O-N/kg N leached [ 500, IRPP TWG 2011 ]. 

According  to  the  results  of  a  study  on  the  quantification  of  greenhouse  gas  emissions  of  the 
livestock  sector  in  the  EU-27,  on  average  pork  and  poultry  meat  have  a  carbon  footprint  of 
about  7.5 kg  CO2-eq/kg  of  meat  and  5.0  kg  CO2-eq/kg  of  meat,  respectively.  Egg  production 
causes about 3 kg CO2-eq/kg product. Total emissions in the EU-27 amount to 165.5 and 21 X 
106  tonnes  CO2-eq  for  pork,  poultry  meat  and  egg  production  respectively.  These  emissions 
include  all  on-farm  emissions  associated  with  livestock  rearing  including  emissions  related to 
the production, transport and processing of feed, as well as land use changes induced by feed 
production [ 416, COM 2010 ]. 

The  share  of  each  gas  in  the  total  fluxes  of  greenhouse  gas  emissions  for  pig  and  poultry 
production is presented in Table 1.23. 

Table 1.23:  Total fluxes of greenhouse gas emissions for the EU-27 pig and poultry production 

CH4 
N2O 
CO2 related to energy 
consumption 
CO2 related to land use and 
land use change 
Total carbon footprint 
Source: [ 416, COM 2010 ] 

kg CO2-eq/kg of 
produced pork meat 
0.74 
1.71 

kg CO2-eq/kg of 
produced poultry meat 
0.04 
1.1 

kg CO2-eq/kg of 
produced eggs 
0.03 
0.77 

2.00 

3.1 

7.55 

1.4 

2.4 

4.94 

0.75 

1.33 

2.88 

Other gases 
Among other gas emissions related to livestock rearing, NOX and N2 need to be mentioned. NOX 
is  normally  associated  with  combustion  processes,  while  N2  is  derived  from  nitrification-
denitrification processes but is not an environmental concern. 

Odour 
Odour is a local problem but is an issue that is becoming increasingly important as the livestock 
industry expands and as ever increasing numbers of rural residential developments are built in 
traditional farming areas, bringing residential areas closer to livestock farms. The increase in the 
number  of  farm  neighbours  is  expected  to  lead  to  increased  attention  to  odour  as  an 
environmental  issue  as  odour  emissions  can  be  offensive  and  give  rise  to  problems  with 
neighbours.  

Intensive Rearing of Poultry or Pigs 

35 

 
 
 
 
 
 
 
 
 
 
 
Chapter 1 

Odour can be emitted by stationary sources, such as from manure storage facilities and animal 
houses,  and  can  also  be  an  important  emission  during  landspreading,  depending  on  the 
spreading  technique  applied.  Its  impact  increases  with  farm  size.  Dust  emitted  from  farms 
contributes to the transportation of odour.  

Odour  is  caused  by  microbial  degradation  of  organic  substance  (e.g.  faeces,  urine,  and 
feedstuff).  Odour  is  a  complex  mixture  of  many  different  compounds,  such  as  sulphurous 
compounds  (e.g.  H2S,  mercaptans),  indolic  and  phenolic  compounds  volatile  fatty  acids  (e.g. 
acetic acid, n-butyric acid), ammonia and volatile amines [ 511, Le et al. 2007 ] [ 270, France 
2010 ].  A leading  substance  in  the complex  mixture of  odorous  compounds  (e.g.  ammonia  or 
hydrogen sulphide) cannot be determined [ 474, VDI 2011 ]. 

Dust 
In the past, dust was not reported as an important environmental issue for the intensive livestock 
sector. Nowadays, especially where farms are close to residences, there are concerns over local 
air quality and a growing interest for dust emissions from livestock farms. A distinction is often 
made between dust and fine dust particles, i.e. the fractions of PM10 and PM2.5 (diameters below 
10 and 2.5 micrometres respectively), which are considered a major environmental risk to health 
due to diseases in the respiratory track.  

The  airborne  particles  that  can  be  generated  in  livestock  buildings  range  from  non-organic 
substances (e.g. soil material) to organic particles from plants and animals, including dead and 
living  microorganisms  such  as  bacteria,  fungi,  viruses  and  parts  of  these  organisms,  e.g. 
endotoxins,  that  are  usually  called  ‘bioaerosols’(see  Section  1.4.3)  [  474,  VDI  2011  ].  Dust 
emissions are also a way for odour dispersion around the animal house [ 383, France 2010 ].  

Inside the animal house, dust is known under certain circumstances to be a contaminant that can 
affect  both  the  respiration  of  the  animals  and  the  farmer,  such  as  in  broiler  houses  with  litter 
having a high dry matter content. The main sources of dust emissions are the animal houses and 
the feed management. The factors that affect dust emissions include ventilation, activity of the 
animals, type and quantity of bedding, type and consistency of feedstuff, humidity in the animal 
house. 

The  type  of  feed  and  feeding  technique  can  influence  the  concentration  and  emission  of  dust 
(bioaerosols).  The  feeding  of  pellets  or  meals  (unpelleted  feeds)  via  liquid  feed  systems  and 
through  the  addition  of  feed  fats,  or  oils  in  the  case  of  dry  feed  systems,  can  reduce  dust 
development. Mealy feed mixes are better when combined with oils as binding agents. Liquid 
feed installations are regarded as desirable. A dry feed system may only be implemented on the 
basis of automatic slop/raw slop feeders. The high quality of the feed and bedding raw materials 
can  be  ensured  through  dry  harvesting  and  storage.  This  will  then  prevent,  in  particular, 
microbial and fungal contamination. 

Regular  cleaning  of  the  housing  equipment  and  all  the  housing  surfaces  will  remove  dust 
deposits. This regime is assisted by the all-in, all-out rotation method as, following the removal 
of all the livestock, careful cleaning and disinfecting of the housing is necessary. Moreover, the 
indoor dust concentration depends very much on the animal activity. Housing techniques which 
offer the animals only a little freedom of motion (e.g. housing of laying hens in enriched cages) 
emit  less  dust  than  those  which  provide  more  freedom  of  motion  (e.g.  aviary  housing,  floor 
husbandry). 

The type and quality of the litter has a great influence on emissions. Finely structured material 
(e.g. chopped straw) releases more particles than coarse material (long straw, wood shavings). 
As a general rule, in non-litter housing, less dust occurs than in the case of litter-based housing. 
In  litter-based  housing,  care  must  be  taken  to  keep  the  litter  clean  and  dry  under  all 
circumstances and free of mould/fungus. Low air velocities in the floor area can reduce the dust 
content in the air. 

36 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
In  pig  housing,  airborne  particulate  matter  also  depends  on  the  feeding  technique  and  human 
presence.  During  feeding  time  and  when  the  animals  are  disturbed  (e.g.  during  inspection 
rounds), higher concentrations are measured than at night and in resting phases. 

The presence of an air cleaning system can also influence dust emissions from housing. 

Chapter 1 

1.4.2 

Emissions to soil and water 

Emissions from housing and manure storage facilities that contaminate soil and groundwater or 
surface  water  occur  because  of  inadequate  facilities  or  operational  failures  and  should  be 
considered  accidental  rather  than  structural.  Adequate  equipment,  frequent  monitoring  and 
proper operation can prevent leakage and spillage from slurry storage facilities.  

Emissions to surface water can also occur from a direct discharge of the waste water arising on 
a  farm.  Little  quantified  information  is  available  on  these  emissions.  Similarly,  the  treated 
effluent  from  slurry  processing  systems  will  normally  have  increased  levels  of  nitrogen, 
phosphorus, BOD and total suspended solids (TSS) [ 364, Portugal 2010 ]. Waste water arising 
from  water  collected  from  the  farmyard,  manure  collection  areas,  household  and  agricultural 
activities  might  also  be  mixed  with  slurry  to  be  applied  onto  land,  although  mixing  is  not 
allowed in many Member States. 

The quality of waste water produced from intensive livestock farming is generally affected by 
the feeding regime, animal manure, the litter used and other supplementary substances such as 
pharmaceuticals  or  disinfectants.  Waste  water  is  usually  the  result  of  manure  run-off,  wash 
water after cleaning of animals, cleaning and disinfecting of buildings and farmyards, and waste 
water from exhaust air treatment by wet scrubbing. In addition, polluted precipitation water may 
be infiltrated into the drainage via storage and manipulation, as well as from the roof surfaces 
[ 373,  UBA  Austria  2009  ].  Emissions  to  water  from  these  sources  contain  nitrogen  and 
phosphorus, but increased levels of BOD may also occur; in particular in water collected from 
the farmyard and from manure collection areas. 

However, of all the sources, landspreading is the key activity responsible for the emissions of a 
number  of  components  (e.g.  nitrogen  compounds,  phosphorus,  heavy  metals)  to  soil, 
groundwater  and  surface  water.  It  has  to  be  stressed  that  land  fertilisation  with  untreated 
manure/slurry  or  with  fractions  derived  from  manure/slurry  treatments  is  good  agronomical 
practice as long as they are properly managed and the side-effects are minimised.  

Most  attention  has  been  given  to  the  emission  of  nitrogen  and  phosphorus,  but  other 
contaminants,  such  as  (heavy)  metals  (e.g.  copper  and  zinc),  pathogen  microorganisms  and 
pharmaceuticals  may  end  up  in  manure  and  their  emissions  may  cause  negative  effects in the 
long run. 

Contamination  of  waters  due  to  nitrates,  phosphates,  pathogens  (particularly  faecal  coliforms 
and  salmonella)  or  heavy  metals  is  the  main  concern.  Excess  landspreading  has  also  been 
associated  with  an  accumulation  of  copper  in  soils,  but  EU  legislation  starting  in  1984 
significantly reduced the level of copper allowed in pig feeds, thereby reducing the potential for 
soil contamination when manure is correctly applied. While improved design and management 
can lead to the elimination of potential pollution sources on farm, the existing spatial density of 
pig production in the EU is of particular concern with regard to the availability and suitability of 
land for spreading pig slurry. Increased environmental regulation of the spreading of manure has 
sought to address this problem. Indeed, in the Netherlands and the Flemish region of Belgium, 
exports of surplus manure occur. 
Directive 2000/60/EC of the European Parliament and of the Council establishing a framework 
for  the  Community  action  in  the  field  of  water  policy  or,  in  short,  the  EU  Water  Framework 
Directive  was  adopted  to  provide  coordinated  sets  of  objectives  and  tools  to  protect  water 
bodies. The Directive establishes an approach for water management based on river basins, the 

Intensive Rearing of Poultry or Pigs 

37 

 
 
 
 
 
 
 
 
 
 
Chapter 1 

natural  geographical  and  hydrological  units.  In  this  framework,  Member  States  put  various 
initiatives  in  place  to  address  diffuse  pollution  from  agriculture,  such  as  the  Codes  of  Good 
Agricultural  Practice,  or  more  specific  initiatives,  like  the  England  Catchment  Sensitive 
Farming Delivery Initiative in the UK.  

For the Baltic and Mediterranean Seas, eutrophication concerns arise, as they are characterised 
by  longer  water  retention times.  The  objective  of  Council  Directive  91/676/EEC  (the  Nitrates 
Directive)  is  to  reduce  these  risks  via  the  reduction  and  limitation  of  organic  nitrogen 
application per hectare of arable land. 

Nitrogen 
For  nitrogen,  the  various  emission  routes  after  manure  landspreading  are  illustrated  in 
Figure 1.15. Through these reactions, losses of 25–30 % of the nitrogen excreted in pig slurry 
have been reported. Depending on the weather and soil conditions, this can be 20–100 % of the 
ammoniacal  nitrogen  if  the  slurry  is  surface  spread.  The  ammonia  emission  rate  tends  to  be 
relatively high in the first few hours after application and decreases rapidly during the day of 
application.  It  is  important  to  note  that  the  ammonia  release  is  not  only  an  unwanted  air 
emission, but also provokes a reduction of the fertilising quality of the applied manure. 

Source: [ 702, Whalen et al. 2013 ] 

Figure 1.15:  Nitrogen cycle showing the main transformations and losses to the environment after 

manure landspreading 

To comply with the Nitrates Directive, Members States are obliged to identify zones that drain 
into waters which are vulnerable to pollution from nitrogen compounds and that require special 
protection, i.e. the Nitrate Vulnerable Zones. In these zones, regulations aim to control nitrate 
concentrations in ground and surface waters by careful management of land, inorganic nitrogen 
fertiliser  and  manure  applications,  e.g.  landspreading  is  restricted  to  a  maximum  level  of 
170 kg N/ha per year. 

Of the whole EU-27 area, 46.7 % has been designated as vulnerable zones, including Member 
States that apply a whole territory approach. As compared to 2007, the total area in the EU-27 
designated as vulnerable zones has increased (the total EU-27 area to which action programmes 
apply  was  39.6 %  in  2007  including  the  area  of  Member  States  that  apply  a  whole  territory 
approach) [ 427, COM 2010 ] [ 460, COM 2013 ]. 

38 

Intensive Rearing of Poultry or Pigs 

Chapter 1 

Fewer  problems  arise  from  landspreading  in  areas  where  sufficient  land  appropriate  for 
application  is  available  for  the  amount  of  manure  that  is  produced.  The  intensive  rearing  of 
poultry or pigs is sometimes affected by an insufficient, small land area being associated with 
productive farms, particularly in areas with a high concentration of farms.  

Phosphorus 
Phosphorus is an essential element in agriculture and plays an important role in all forms of life. 
In  natural  (i.e.  unfarmed)  systems,  it  is  efficiently  recycled  as  it  remains  in  the  ecosystems, 
transforming in cycles across vegetation, residues and soil. In agricultural systems, it is removed 
by  crops  and  eventually  by  the  animal  product,  so  further  phosphorus  has  to  be  imported  to 
sustain productivity.  

Phosphorus is normally held firmly in the soil, but excessive manure applications can result in 
unnecessary soil enrichment, which at elevated topsoil concentrations can result in phosphorus 
leaching  to  ground  and  surface  waters.  Also,  phosphorus  can  be lost  through  soil  erosion  and 
from surface run-off of freshly applied manure. 

Manure  applications  that  comply  with  the  nitrogen  load  allowed  by  the  Nitrates  Directive 
(maximum  170 kg  N/ha  per  year)  normally  provide  an  excess  of  phosphorus  fertilisation.  As 
only  part  of  the  phosphorus  is  taken  up  by  the  plants  (5–10 %),  large  and  often  excessive 
applications of manure and mineral fertiliser were common in the past. Increased awareness of 
farmers on environmental and economic aspects induced a change in farm practices for a better 
use of nutrients. 

The importance of manure as a source of phosphorus has increased to the point at which it is 
estimated that 50 % of the input to EU surface waters from leaching and penetration into soil 
can be attributed to the application of animal manure  [ 32, SCOPE 1997 ]. Phosphorus  is the 
main  cause  of  algal  blooms  in  fresh  water  systems  and  can  be  damaging  to  aquatic  life  and 
unsightly for water users. 

Potassium  can  also  be  lost  by  leaching  and  in  surface  run-off.  This  means  a  decrease  in  the 
fertiliser value of manure, but is not a risk to the environment. 

1.4.3 

Other emissions 

Noise 
The  intensive  rearing  of  poultry  or  pigs  can  generate  other  emissions  such  as  noise  and 
emissions of  bioaerosols. Like  odour, it is a  local  problem,  and  disturbances can  be  kept  to  a 
minimum  by  properly  planning  activities.  The  relevance  of  this  problem  may  increase  with 
expanding  farms  and  with  the  growth  in  rural  residential  developments  in  traditional  farming 
areas. 

Intensive Rearing of Poultry or Pigs 

39 

40 

Intensive Rearing of Poultry or Pigs 

Chapter 2 

2  APPLIED PROCESSES AND TECHNIQUES 

This chapter describes the major activities and production systems used in intensive poultry or 
pig  production,  including  the  materials  and  equipment  used  and  the  techniques  applied.  It 
presents  the  techniques  that  are  generally  applied  throughout  Europe  and  to  creates  a 
background for the environmental data presented in Chapter 3. It also describes those techniques 
that can serve as a reference or benchmark for the environmental performances of the reduction 
techniques  presented  in  Chapter  4,  without  giving  an  exhaustive  description  of  all  existing 
practices or a  description of  all combinations  of  techniques  that  may  be  found on  IED  farms. 
Because of historical developments and climatic, economic and geographical differences, farms 
vary in the kind of activities that take place, as well as in the way in which these activities are 
carried  out,  namely  in  the combinations  of  techniques  that  may  be  applied.  Nevertheless,  this 
chapter should give the reader a general understanding of the common production systems and 
techniques applied in Europe in the production of poultry and pigs. 

2.1 

Introduction 

Livestock  production  mainly  consists  of  converting  feed  into  meat  or  eggs,  and  is  usually 
performed  in  different  phases.  The  objective  is  to  achieve  a  high  efficiency  in  the  feed 
conversion  ratio  (FCR),  whilst  respecting  animal  welfare  and  avoiding  emissions  that  are 
harmful to the environment or to people. It is important to note that good environmental farm 
management is more likely to be practised if it is complementary to product quality rather than 
at the expense of it, since economic profitability and customer satisfaction are the main drivers 
for the activity. 

In general, the production systems commonly applied do not require highly complex equipment 
and installations, but they increasingly require a high level of expertise to properly manage all 
the activities of the farm.  

The animal housing system, where animals for meat or egg production are kept for all or part of 
the  year,  is  the  main  determinant  of  the  activities  of  the  farm,  and  includes  the  following 
elements (see Sections 2.2 and 2.3): 









the way the animals are stocked (cages, crates, free);

the system to remove and store (internally) the produced manure;

the equipment used to control and maintain the indoor climate;

the equipment used to feed, water and litter the animals.

Other important elements of the rearing system are: 











the outdoor storage of manure;

the storage of feedstuffs;

the storage of dead animals;

the storage of other residues;

the loading and unloading of animals.

Additionally,  on  egg-producing  farms,  the  selection  and  packaging  of  eggs  is  a  common 
activity, but this is outside the scope of this document.  

Intensive Rearing of Poultry or Pigs 

41 

Chapter 2 

A  number  of  associated  activities  can  be  part  of  the  farming  system,  but  these  vary  between 
farms for reasons such as the availability of land, farming tradition, or commercial interest. The 
following activities or techniques may be encountered on an intensive livestock farm:  

 

 

 

 

 

manure landspreading; 

on-farm  manure  processing  and  treatment,  e.g.  biogas  production,  manure  separation, 
composting;  

feed milling and grinding; 

waste water treatment;  

residue treatment, such as carcass incineration. 

Schematically,  farm  activities  for  the  rearing  of  poultry  or  pigs  can  be  illustrated  as  in 
Figure 2.1. 

Figure 2.1:  Schematic representation of activities carried out on farms for the intensive rearing of 

poultry or pigs 

42 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.2 

Poultry production 

2.2.1 

Production of eggs 

For  commercial  egg  production,  the  poultry  breeds  used  are  from  selection  and  breeding 
programmes  that  optimise  their  genetic  potential  for  high  egg  production.  The  breeds  have 
smaller bodies and so direct more of the dietary nutrients into egg production, rather than into 
increasing their body mass. The egg-producing breeds are further divided into birds that produce 
white shelled eggs or coloured shelled eggs. 

Council Directive 1999/74/EC of 19 July 1999 lays down minimum standards for the protection 
of  laying  hens.  In  accordance  with  this  Directive,  since  2012  conventional  battery  cages  are 
banned  for  laying  hens  and  only  enriched  cages  or  alternative  (non-cage)  rearing  systems  are 
allowed. Unenriched cages are allowed for breeders and pullets. 

The  number  of  laying  hens  per  surface  area  varies  between  housing  systems.  The  formerly 
commonly used cage systems allowed a stocking density, depending on tier arrangement, of up 
to  22  birds  in  each  cage  floor  area  or  up  to  30–40 birds/m2  (corresponding  to  the  available 
ground  area).  The  rearing  systems  allowed  by  Directive  1999/74/EC  laying  down  minimum 
standards for the protection of laying hens have much lower densities. In particular:  

 

 

 

enriched  cages:  up  to  approximately  13  birds/m2  of  cage  area  and  up  to  approximately 
16 birds/m2  of  usable  area  (each  laying  hen  must  have  at  least  750  cm2  of  cage  area, 
600 cm2 of which shall be usable); 
barn systems: up to 9 birds/m2; 

aviary systems: up to 9 birds/m2 of usable area or up to 36 birds/m2 corresponding to the 
available ground area (no more than four levels can be used). 

In  non-cage  systems,  hens  can  walk  around  freely,  such  as  in  barn  systems  and  free-range 
systems in which the hens also have continuous daytime access to open-air runs. 

In  cage  systems,  birds  are  kept  in  tiered  enclosures  made  from  welded  steel  wire  which  are 
arranged in long rows with sloped floors to allow the eggs to roll to the front side of the cages, 
where they are removed by hand or on a conveyor belt. The cage systems can be described as a 
combination of the following elements: 

 

 

 

building construction; 

cage design and placement; 

manure collection, removal and storage. 

Intensive  egg  production  usually  takes  place  in  closed  buildings  made  of  various  materials  
(e.g.  stone,  wood,  steel  with  sheet  cladding).  The  building  can  be  designed  with  or  without  a 
light system, but always with ventilation. The equipment in the housing can vary from manual 
systems  to  fully  automated  systems  for  indoor  air  quality  control  (see  Section  2.2.4),  feeding 
and  drinking  (see  Section  2.2.5),  manure  removal  and  egg  collection.  Close  to the  housing  or 
immediately attached are the feed storage facilities. 

Laying hens kept in cages have one laying period of about 12–15 months (after a growing period 
of  around  16–20 weeks).  The  laying  period  can  be  extended  by  a  forced  moult  between  the 
eighth and twelfth month of lay, hence a second laying period of at least 7 months can be added 
[  39,  Germany  2001  ].  Moulting  is  a  natural  process,  but  in  commercial  egg  production  it  is 
sometimes still induced by feed modification or light alteration, hence it is argued that it is not a 
welfare-compatible  practice.  Moult  induction  by  feed  or  water  deprivation  is  prohibited 
(Directive 98/58/EC concerning the protection of animals kept for farming purposes), whereas 

Intensive Rearing of Poultry or Pigs 

43 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

changing feed composition (e.g. reducing the energy content by increasing the bran percentage) 
or  controlling  feed (instead  of  ad  libitum  provision) is  allowed.  Studies  are  ongoing  to  find  a 
more acceptable alternative  method of inducing moulting in laying hens to prolong the laying 
period. 

2.2.1.1 

Cage systems for laying hens 

Directive 1999/74/EC phased out conventional cages for laying hens as of 31 December 2011, 
and  therefore  they  are  not  described  in  this  document.  The  cage  systems  described  below 
correspond to modern cages that are referred to as ‘enriched’, ‘furnished’, or ‘colony systems’.  

Enriched  cages  are  equipped  with  structural  features  to  stimulate  species-specific  behaviour, 
like nests, perches, litter, and increased cage height. Nest boxes can be placed at the front of the 
cage and are normally darkened by plastic curtains to encourage laying. Nests can be adapted to 
keep hens out at night, with gentle expulsion systems or automatic doors that allow animals to 
exit but not to enter the nest. In enriched cages, the area in which eggs are laid can be relatively 
small,  and  collisions  occasionally  occur  between  eggs  in  the  nest  box,  which  can  damage  the 
eggshell. 

Perches are arranged to provide around 15 cm per hen, and are designed to strengthen animals’ 
legs. Wing flapping is made possible due to a cage height of at least 45 cm. Sand-bathing and 
scratching  are  possible  in  separate  areas,  equipped  with  automated  distribution  of  sand, 
shavings,  or  other  materials,  plastic  mats,  or  other  kinds  of  litter.  Claw  shorteners  such  as 
perforated  plates,  abrasive  stones,  ceramics,  plates  or  strips  are  provided  and  are  frequently 
placed in the baffle plates behind the feed troughs. All these features can be placed in different 
relative positions in the cage, as shown in Figure 2.2. 

A summary of the main characteristics of enriched cages is presented in Table 2.1. 

Table 2.1: 

Summary of the main characteristics of enriched cages 

Minimum cage area per hen  
Minimum total area per cage 
Length of feed trough  

Minimum height  

Drinking system  
Length of perches  

Levels and droppings  

Additional features  

At least 750 cm2, of which 600 cm2 shall be usable  
2 000 cm2 
12 cm per hen 
45 cm: headroom between levels in the usable area 
20 cm (at least): in the remaining area of the cage 
Two nipple drinkers or two cups must be within reach of each hen  
At least 15 cm per hen 
No more than four levels, arranged to prevent droppings falling on 
the levels below 
A nest: litter such that pecking and scratching are possible 

44 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 46, Netherlands 2010 ] 

Figure 2.2:  Possible placement of the equipment in enriched cages 

Source: [ 21, EFSA 2005 ] 

Figure 2.3:  Schematic drawing of two large enriched cages 

Hens are reared in enriched cages in a wide variety of group sizes. Groups of up to 10–12 birds 
are generally referred to as a 'small group', while 15–30 birds could be regarded as a 'medium-
sized'  group  and  above  this  number  would  be  regarded  as  a  'large  group'.  Larger  cages  may 

Intensive Rearing of Poultry or Pigs 

45 

 
 
 
 
 
 
 
Chapter 2 

house  up  to  60  birds.  Neither  the  maximum  nor  the  optimum  number  of  birds  has  yet  been 
defined [ 38, ASG Lelystad 2006 ]. 

There  are  a  wide  variety  of  enriched  cages  designs.  Positioning  and  layout  of  equipment  is 
important  to  allow  proper  use  and  thus  contribute  to  bird  welfare,  hygiene  and  performance. 
Cage  dimensions  are  related  to  the  group  size  and  may  influence  inspection  of  birds  and 
depopulation [21, EFSA 2005 ]. In Germany, the small group system that has been developed 
goes beyond the EU requirements for an enriched cage and allows for better hygiene levels. The 
cages are arranged on three to five tiers, and are often stacked in two levels with an intermediate 
platform [ 368, France 2010 ].  

The manure is collected on manure conveyor belts that are situated under each tier of cages. At 
the end of the belt, a cross-conveyor further transports the manure outside, normally to external 
storage.  Closed  manure  storage  can  pose  a  sanitary  risk;  hence,  manure  is  also  transported 
directly to field heaps or external storage, or to other uses (e.g. direct application on compatible 
cultivations, manure processing or treatment). The manure belts are made of smooth, easy-to-
clean  polypropylene  or  trevira  and  no  residue  sticks  to  them.  With  modern  reinforced  belts, 
manure  can  be  removed  from  very  long  runs  of  cages.  Some  drying  takes  place  on  the  belts, 
especially during the summer, and manure may be held on the belts for up to a week.  

Frequently,  the  manure  on  the  belts  is  dried  by  blowing  air  over  the  droppings  through  pipes 
that are placed above or along the belts. The air can be preheated and the manure is removed at 
least once a week at a minimum dry matter content of 40–60 %. A benefit for the animals is the 
introduction  of  fresh  cooling  air  immediately  adjacent  to  the  birds.  Further  improvements 
consist  of  the  introduction  of  conditioned  air  and/or  the  use  of  heat  exchangers  to  condition 
incoming outside air. 

2.2.1.2 

Non-cage systems for laying hens 

Laying  hens  are  also  kept  in  systems  which  Directive  1999/74/EC  refers  to  as  ‘alternative 
systems’.  They  are  also  commonly  called ‘non-cage  systems’.  In  alternative  housing  systems, 
hens are reared on a litter-covered solid floor in combination with a slatted floor. Often the floor 
is made of concrete, but other materials can be used as well. Manure accumulates either on the 
solid floor or under the slatted area for the 14-month laying period. 

Manure  removal  is  generally  mechanised  using  scrapers  or  belts.  They  may  have  air-drying 
systems  ventilating  and  drying  the  manure.  Air  temperature  can  be  increased  with  heating 
systems and/or heat exchangers using the heat of outgoing ventilation air to heat incoming fresh 
air. 

The removal system is used to convey the manure from the building to a container or storage 
area.  Alternatively  the  storage  may  be  underneath  the  building  in  a  separate  room.  Another 
approach is to store the manure in a pit underneath a perforated floor or below the house where 
it is stored and subsequently processed or spread on the land [ 38, ASG Lelystad 2006 ]. 

Article 4 of Directive 1999/74/EC regulates features for non-cage systems, such as: 

 

 

 

 

 

 

 

46 

the availability of feeders and drinkers; 

the positioning and dimensioning of nests, perches and litter; 

the number and the height of the floors where the hens can move freely; 

the prevention of droppings from falling on levels below; 

the dimensions and the availability of pop-holes giving access to open runs; 

the general characteristics of the open runs; 

the stocking density. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

These  features  allow  for  a  more  comfortable housing.  However,  higher  ammonia  and  dust 
emissions  may  arise  compared  to  cage  systems,  due  to  the  presence  of  litter  material  and  to 
increased animal activity, though this can be mitigated by the frequent removal of manure with 
belts or scrapers.  

What  non-cage  systems  all  have  in  common  is  that  the  birds  have  more  space  or  can  move 
around  more  freely  within  the  building,  and  that  operators  can  enter  them.  The  housing 
construction is similar to that of the cage systems with respect to  walls, roof and foundations. 
Birds are kept in large groups with 2 000 to 10 000 bird places per housing facility, where the air 
is replaced and emitted passively by natural ventilation or by forced ventilation with negative 
pressure.  Thermally  insulated  poultry  houses  have  forced  ventilation,  and  can  be  either 
windowless or with windows for natural daylight. 

Various housing designs are applied, such as variations of the basic schemes of: 

 

 

the deep litter system, also referred to as the single-tier non-cage system or single level 
system; 

the aviary system, also referred to as the ‘perchery’ or multi-level system. 

These  indoor  systems  can  be  combined  with  either  one  or  both  of  the  following  additional 
structures: verandas and/or free ranges (see Section 2.2.1.2.3). 

2.2.1.2.1 

Deep litter system  

In single-tier or single-level systems, the ground floor area is fully or partly covered with litter 
and may be combined with a slatted floor. At least 250 cm2 of littered area is provided per hen 
and the litter occupies at least one third of the ground surface in accordance with the provisions 
of  Directive  1999/74/EC.  The  remaining  area  is  covered  with  slats  that  are  mostly  made  of 
plastic, wire mesh or wood. Underneath the slats, a manure pit or a manure removal system (e.g. 
scrapers or belts) is placed to collect the droppings together with spilled water from the drinkers. 
Usually the slatted floor is in the middle of the hen house, with littered floors on both sides, but 
there are also houses where slatted floors are placed along sidewalls with the litter in the middle 
of the house.  

The pit is formed by the raised floor or can be sunk into the ground (see Figure 2.4). Droppings 
are removed from the pit at the end of the laying period, or may be removed periodically, with 
the aid of aerated or non-aerated manure belts or  a scraper. At least  a third of the exhaust  air 
volume  is  drawn  off  via  the  droppings  pit.  In  single-tier  systems,  there  is  only  one  level 
available for the birds at any one point [ 38, ASG Lelystad 2006 ]. 

Variations  are  possible  in  wider  houses,  where  rows  of  laying  nests  can  be  placed,  or  in  the 
same  house,  two  stacked  compartments  can  be  arranged  on  different  levels  of  the  house  
[ 70, Netherlands 2010 ]. 

The laying nests, feed installation and water supply are usually placed on the slats to keep the 
litter area dry. Nest boxes can be automated or hand collected, with an artificial grass bottom or 
with litter. Also the size of each nest can vary largely, from single nest boxes for one hen at a 
time to group nests.  

The automatic supply of feed and drinking water, with long troughs or automatic round feeders 
(feeder pans) and nipple drinkers, cups or round drinkers are usually installed above the slatted 
area,  although  this  depends  on  the  available  space.  Lighting  programmes  to  influence  the 
performance/rate  of  laying.  Perches  are  available  and  are  usually  placed  in  A-frames  on  the 
slatted floor [ 38, ASG Lelystad 2006 ] [ 39, Germany 2001 ] [ 44, IKC 2000 ]. 

Intensive Rearing of Poultry or Pigs 

47 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 38, ASG Lelystad 2006 ]  

Figure 2.4:  Schematic cross section of a single-tiered non-cage system 

2.2.1.2.2 

Aviary system  

Aviaries (multi-level systems or percheries) consist of the ground floor plus one or more levels 
of perforated platforms, from which  manure cannot fall on birds below. At some point across 
the system, there will be at least two levels available for birds. An aviary house is a construction 
with thermal insulation and forced ventilation and either natural or artificial light. Houses can be 
combined with a free range and an outside scratching area. Birds are kept in large groups and 
enjoy freedom of movement over the entire house area over multiple levels. The housing space 
is  subdivided  into  different  functional  areas:  feeding  and  drinking,  sleeping  and  resting, 
scratching and egg-laying area. The fact that the birds can use several levels allows for higher 
stocking densities compared to the commonly used floor regime (deep litter): up to 9 birds per 
usable  m2  or  up  to  18  birds  per  m2  of  ground  space.  Houses  can  accommodate  up  to  80 000 
birds. Droppings are removed by manure belts or collected in a manure pit. 

Many configurations are possible (see Figure 2.5). Three major categories can be distinguished: 

- Aviaries with non-integrated nest boxes: aviaries with several levels of perforated floors with 
manure belts under them and separately arranged nest boxes (see Figure 2.5, configuration A). 
Feeders and drinkers are distributed in such a way that they provide equal access for all hens. 

The  earlier  type  of  aviaries  has  stacks  of  elevated  floors  and  separate  units  of  nest  boxes. 
Between  the  elevated  floors  and  the  nest  boxes  an  aisle  covered  with  litter  is  positioned  to 
enable operators to walk through the system and to provide litter to the hens. The elevated floors 
usually have a slight slope to allow eggs to roll towards one side. Under each floor a manure 
belt is positioned to prevent the manure from falling to the lower levels, and to transport manure 
out of the hen house. The nest boxes (individual or group nests) can be lined up in one row or in 
multiple rows above one another. 

On  the  elevated  floors,  water  and  feed  is  provided.  Nipple  drinkers  are  usually  used  for 
watering,  but  cups  are  also  an  option.  Feed  is  provided  by  means  of  chain feeders  or  feeding 
pans. Perches are located over the elevated floors. The top floor usually has many perches; the 
lower floors often have perches only along the sides. 

Litter  is  provided  on  the  floor  of  the  house.  In  some  systems  the  entire  floor  is  covered  with 
litter and birds can walk underneath the elevated floors. In other some systems, birds cannot use 
the space underneath the stacks [ 38, ASG Lelystad 2006 ]. 

-  Aviaries  with  integrated  nest  boxes:  aviaries  as  above  but  where  nest  boxes  are  integrated 
within the blocks of perforated floors (see Figure 2.5, configuration B). 

48 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

The use of a system with integrated nest boxes is an evolution of the previously described non-
integrated nest system. In this type of aviaries, stacks of elevated floors with units of nest boxes 
are  integrated  in  the  same  stack.  Often,  stacks  with  integrated  nest  boxes  are  alternated  with 
stacks without nest boxes. Between the different stacks of floors, an aisle covered with litter is 
positioned to enable operators to walk through the system and to provide litter to the hens. The 
nest boxes (individual or group nests) are usually lined up in two rows connected with the back 
of the nests.  

On  the  elevated  floors  water  and  feed  is  provided.  Water  is  usually  provided  through  nipple 
drinkers, but cups are also possible. Feed can be provided by means of chain feeders or feeding 
pans. Perches are located over the elevated floors. The top floor usually has many perches, the 
lower  floors  often  have  only  perches  along  the  sides  of  the  floors.  Perches  are  also  placed  in 
front of the nest boxes. 

Litter is provided on the bottom of the hen house. In some systems the entire floor is covered 
with  litter  and  birds  can  walk  underneath  the  elevated  floors.  Other  systems  have  the  area 
underneath  the  elevated  floors  blocked,  so  that  hens  have  to  jump  onto  the  slatted  floors  to 
continue [ 38, ASG Lelystad 2006 ].  

- Portal aviaries: aviaries with elevated perforated floors, the top tier of which is a single level 
which links the lower stepped platforms (see Figure 2.5 configuration D). The keeper can walk 
under  and  upon  the  top  tier.  Nest  boxes  are  integrated  in  the  system.  Units  of  nest  boxes  are 
integrated into the same stack. Typically, litter covers fully the entire floor of the hen house and 
birds can walk underneath the elevated floors. Between the different stacks of floors, under the 
single level part, an aisle covered with litter is positioned to enable carers to walk through the 
system and to provide litter to the hens. On the outside of the two stacks there is also an aisle 
covered with litter.  

On  the  elevated  floors  water  and  feed  is  provided.  Water  is  usually  provided  through  nipple 
drinkers, but cups are also possible. Feed can be provided by means of chain feeders or feeding 
pans. Perches are located over the elevated floors. 

Intensive Rearing of Poultry or Pigs 

49 

 
 
 
 
 
 
 
Chapter 2 

Source: [ 47, Netherlands 2010 ] 

Figure 2.5:  Common aviary configurations  

2.2.1.2.3 

Additional structures for non-cage housing 

Covered veranda 
This consists of an outside covered area, which is available to the birds during daylight hours. 
Covered verandas are connected to the hen house and can be built as additional elements to the 
house, or as a part of the main structure, covered by a roof extension. Verandas are often closed 
by shutters or a curtain that can be lifted to provide hens access to the free-range area. If there is 
no free range, curtains are replaced by fences of wire mesh preventing  birds from getting out, 
but allowing fresh air to blow freely through the area. In this case, the climate is similar to that 
outside, except for the rain, which is prevented from entering the area by the use of protective 

50 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Chapter 2 

devices.  The  floor  of  the  covered  veranda  is  usually  littered  (e.g.  a  thin  layer  of  sand)  
[ 38, ASG Lelystad 2006 ].  

Free range 
Free ranges can be covered with grass. The birds have access to this area from houses via pop-
holes in the wall and from the covered veranda, if present. They will use the area if they feel 
there is sufficient shelter. The shelter may be trees or bushes, but it can also be artificial shelter 
(elevated  nets,  tents).  Also,  a  fence  is  used  as  cover  to  walk  along.  Providing  a  sand  bath  is 
another way to attract poultry to use these facilities. Areas near the house may be covered with 
free-draining  material,  in  order  to  maintain  good  hygiene  both  outside  and  inside  the  house  
[  38,  ASG  Lelystad  2006  ].  Protection  is  also  necessary  from  wild  avifauna  for  biosecurity 
reasons, e.g. due to the risk of avian flu.  

Veranda and free-range housing variations are not intended to reduce ammonia emissions. 

2.2.1.3 

Pullet rearing 

Success in  the laying  period  will  greatly  depend  on  effective  housing  and  management  in the 
rearing period. In order to facilitate a smooth start to the laying period, it is advisable to rear the 
pullets  of  laying  hens in a  system  that  is  similar  to  the  one  they  will  be  housed  in during  the 
laying period [ 38, ASG Lelystad 2006 ]. This procedure, together with a transfer well before 
the  onset  of  laying,  minimises  the  stress  due  to  the  transfer  into  a  new  facility  and, 
consequently, promotes layer productivity.  

Feed and light management of the pullets will also influence the production results later in life. 
Stimulation too early may lead to more egg-laying problems. As the challenges hens meet in the 
laying  period  are  different  for  cage  systems  and  alternative  systems,  the  rearing  management 
should be focussed on the demands of the laying period [ 38, ASG Lelystad 2006 ]. 

The rearing phase for chicks up to 17 or 20 weeks is normally run in separate facilities because 
the  microbial  conditions  of  the  adult  environment  would  be  too  dangerous  for  young  chicks. 
The space provided in small group housing is about 0.035–0.045 m2 per bird. 

Management  details  differentiate  pullet  rearing  from  the  laying  period.  For  instance,  in  pullet 
rearing, more care is paid to providing heat to the few-days-old birds, to encouraging them to 
feed and drink after arrival, and to synchronising their activity with lighting programmes.  

Pullets  can  be  reared  in  simple  deep  litter  housing  on  a  bedded  solid  floor  in  closed,  well 
insulated houses with forced ventilation and without functional areas. The manure is stored with 
the bedding and is removed at the end of the rearing period, which is about 16–18 weeks. The 
system  is  relatively  animal-friendly  and  provides  a  space  of  0.05–0.07  m2  per  head  (whilst in 
aviaries, 0.017–0.04 m2 per head is usual). However, high ammonia, dust and odour emissions 
arise  due  to  the  long-term  indoor  manure  storage.  A  slatted  floor  covering  no  more  than  two 
thirds of the area can be included, allowing a deep pit underneath. Manure is removed at the end 
of the rearing period. 

2.2.2 

Production of broiler meat 

Broiler  meat  is  produced  by  growing  meat-type  breeds  of  chicken.  Meat  chickens  stem  from 
broad breeding programmes which balance health, welfare and productivity. A limited number 
of  international  companies  produce  hybrid  varieties  (strains)  from  combinations  of  many 
different  breeds.  Traits  that  are  mostly  considered  in  the  genetic  selection  are:  higher  breast 
meat  yield,  more  efficient  feed  conversion,  reproduction  efficiency,  and  improved  disease 
resistance. Obviously, these strains are not as well suited to laying eggs as the laying breeds.  

Intensive Rearing of Poultry or Pigs 

51 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Directive 2007/43/EC, laying down minimum rules for the protection of chickens kept for meat 
production, establishes rules for the protection of animals, aiming for a balance between animal 
welfare, health, economic and social considerations, and environmental impacts.  

The traditional housing for intensive broiler production is a simple, closed-building construction 
of  concrete  or  wood  with  artificial  lighting  or  artificial/natural  light  combination  lighting 
systems,  and  thermal  insulation.  Forced  ventilation (negative  pressure  principle)  is  applied  by 
way  of  fans  and  air  inlet  valves  (see  Figure 2.6).  Naturally  ventilated  buildings  are  also  used 
which are constructed with open side walls (windows with louvre-type curtains). Open climate 
houses are located so that they are freely exposed to a natural stream of air and are positioned at 
a right angle to the prevailing wind direction. Additional ventilating fans may operate via ridge 
slots  during  hot  weather  and  gable  openings  may  also  apply  to  provide  extra  air  circulation 
during hot periods in summer. Wire mesh screens along upper side walls keep wild birds out.  

Broilers are commonly kept on litter spread over the entire floor area. Bedding can be made up 
of  chopped  straw  or  wood  shavings,  but  also  of  shredded  paper,  rice  husks  or  other  material, 
which  has  to  comply  with  the  provisions  (dry  and  friable  on  the  surface)  of  Directive 
2007/43/EC. The floor area is usually built as a solid concrete slab, but may also consist of a 
clay  floor  (in  France,  93 %  of  buildings  have  non-concrete  floors).  The  bedding  is  spread 
uniformly  at  the  beginning  of  each  growing  period  and  the  solid  manure  is  removed  (broiler 
litter) at the end of the growing period.  

Modern  housing  is  mainly  equipped  with  controlled  ventilation  systems  that  allow  climate 
control  for  animals,  litter  drying,  and,  ultimately,  for  channelling  air  to  air  treatment  devices. 
The airflow direction depends on the position of inlets and outlets which can be placed on the 
roof  ridge,  on  side  walls  or  gable  ends.  Hence  the  air  can  be  drawn  from  the  sides  up  to  the 
ridge, or from the top down to the sides (cross ventilation), or all along the length of the house 
from one gable side to the other (tunnel ventilation). In housing fitted with cross ventilation, the 
litter  moisture  may  be  less  homogenous  and  can  be  around  10 %  higher  [  91,  Italy  2010  ]. 
Directing the ventilated air in a precise direction also allows it to be channelled entirely to an air 
treatment system, without leaving any uncontrolled airflows. 

Source: [ 400, Silsoe Inst. 1997 ] 

Figure 2.6:  Example of schematic cross section of a common broiler house 

Automatic,  height-adjustable feeding  and  drinking  systems  (mostly  tube  feeders  with  round 
feeder pans and nipple drinkers with drip-water catch bowls) are provided.  

Closed buildings have oil- or gas-fired warm-air blowers for whole room heating, when needed; 
heat exchangers (water-air, air-air) coupled to air blowers are increasingly used. Radiant heaters 
(mostly gas-fired) are used for zone heating.  

52 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Broilers are kept at a stocking density of 13 to 26 birds per m2, depending on the duration of the 
fattening  period  and  consequently  of  the  live  weight  (LW)  at  slaughter.  Typical  bird  weights 
and ages prior to slaughter are given below: 

Chapter 2 

 

 

 

34-day cycle and final weight of 1.5 kg of LW per bird; 

40-day cycle and final weight of 2 kg of LW per bird; 

45–55-day  cycle  and  final  weight  of  2.1 kg  of  LW  per  female  bird  or  3 kg  of  LW  per 
male bird. 

Directive 2007/43/EC defines the maximum stocking density in a housing system as 33 kg/m2. 
Broilers can also be kept at a higher stocking density of 39 kg/m2 and up to 42 kg/m2 if Member 
States  allow  derogations,  provided  that  the  housing  systems  comply  with  certain  welfare 
requirements. 

Houses  can  be  combined  with  a  veranda,  where  open  side  walls  along  the  side  of  the  house 
allow birds access to a covered, outside climate area for animal welfare reasons. Verandas are 
usually equipped with a base plate covered with some type of litter (scratching area) or ground 
covering.  Verandas  are  often  combined  with  free-range  systems  (made  accessible  from  the 
twentieth day of the bird's  life  onward) where the animals have free access to an outside area 
during the daytime. This production system is especially common on organic farms or in special 
animal welfare programmes (see also Section 2.2.1.2.3). 

2.2.3 

Other poultry production sectors 

2.2.3.1 

Rearing of broiler breeders  

Meat broilers are slaughtered well before they become sexually reproductive at around 5 months 
of age. The broilers' parents, often called 'broiler breeders', live to maturity and beyond so they 
can be used for breeding. Broiler breeder farms raise parent stock which produces fertile eggs 
for  broiler  production.  Housing  is  similar  to  that  of  broilers,  additionally  equipped  with  nests 
where eggs are laid, or they may be reared in cage systems. 

Broiler breeder rearing is typically a two-stage process. Parent stock purchased from a primary 
breeder is delivered at a day old to 7–10 days old. Most are first placed on starter farms, where 
males  and  females  are  raised  separately,  until  10–20  weeks  old.  In  the  houses  where 
reproduction  takes  place,  8–10  males  are  provided  for  a  hundred  females,  and  one  nest  is 
provided for approximately every five females. Feeding of broiler breeders is restricted to avoid 
reproductive problems. 

2.2.3.2 

Production of turkeys  

Turkeys are reared for meat production and different production systems apply. These include 
the  two-phase  system  (e.g.  in  the  UK,  the  Netherlands,  Germany).  The  first  period  covers  a 
brooding period for all birds up to 4–6 weeks, until they reach an approximate weight of 2 kg, 
after which the birds are transferred to different housing for the fattening phase. In general, the 
slaughter weight for the stags is from 14.5 kg to 21 kg live weight, with a fattening period that 
ends at 16–22 weeks, and for the hens, the slaughter weight is generally from 7.5 kg to 11 kg 
live  weight,  with  a fattening  period  between  10  and 17  weeks. The animals are  kept  in  much 
higher densities at the beginning, when they are still small. During the growing period, the birds 
are thinned, and after 22 weeks only a third of the birds may be left. For example in the UK, the 
hens are removed first and sold as oven-ready birds. Stags are used for further processing. 

Intensive Rearing of Poultry or Pigs 

53 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

The most commonly applied turkey housing is a traditional housing construction, which is very 
similar  to  that  used  for  the  housing  of  broilers  (Figure 2.6).  Turkeys  are  housed  in  closed, 
thermally  insulated  buildings  with  forced  ventilation,  or  in  open  houses  with  open  side  walls 
and  louvre-type  curtains  (controlled  natural  ventilation).  Forced  ventilation  is  applied  by  fans 
and inlet valves while natural ventilation is created via automatically controlled louvre-windows 
or  wall-mounted  inlet  valves.  Open  houses  are  aligned  at  right  angles  to  the  prevailing  wind 
direction and located in such a way as to be exposed to natural airflow. Additional ventilation is 
applied via ridge slots and gable openings. Radiant gas heaters are used for heating. 

Closed buildings are typically used to house all young turkeys in the first rearing period, and to 
rear the females in the finishing phase. For the finishing period, stags are more often reared in 
houses with open side walls and natural ventilation, which may also be fitted with outdoor free 
ranges. The  stocking  density  in  Germany  is  reported  as  5  birds/m2  for  the  finishing  period  of 
female turkeys and 2.8 birds/m2 for the finishing period of male turkeys [ 118, Germany 2010 ]. 

Precautions  are  put  in  place  to  protect  against  emergencies  like  power  cuts,  extreme  weather 
conditions  or  fire,  since  all  animals  in  these  large  units  will  be  at  risk  at  once.  During  peak 
summertime  temperatures,  additional  measures  are  taken  to  minimise  heat  stress  on  the  birds 
(by  providing  for  larger-volume  air  exchange,  operating  extra  fans  for  bird  comfort  in  open 
houses, water fogging or roof sprinkling). 

Wire meshing in the upper side wall section is applied to keep wild birds out. A floor regime is 
operated with litter material (chopped straw, wood shavings) with a depth of 5–7.5 cm spread 
over the entire housing floor area (built of concrete), with layers topped up during the rearing 
cycle reaching a depth of 20–55 cm. Manure removal and cleaning of the house takes place at 
the end of each respective growing period. All manure is removed by an excavator or a front-
end  loader.  Litter  replenishment  is  applied  as  needed.  Automatic  height-adjustable  drinkers 
(such as bell drinkers) and feeders are provided during the growing period to minimise spillages 
and avoid the degradation of litter. Daylight length and light intensity can be controlled during 
brooding and, in houses with forced ventilation, over the entire brooding/finishing period. 

The rearing of turkeys must comply with the provisions laid down in the  Council of Europe's 
'Recommendation  concerning  turkeys  (meleagris  gallopavo  ssp)'  as  adopted  by  the  Standing 
Committee of the European Convention for the protection of animals kept for farming purposes 
on 21 June 2001. 

2.2.3.3 

Production of ducks 

Ducks are generally reared for meat production. There are numerous breeds on the market, but 
popular breeds for commercial meat production are Pekin and Barbary; Rouen and Muscovy are 
both types of Barbary. The Muscovy and domestic duck hybrid (mallard duck) is obtained by 
crossing a female Pekin duck and a male Muscovy and it is produced on farms for meat and foie 
gras.  Different  breeds  are  used  for  egg  laying,  although  Pekins  have  a  reasonable  laying 
performance compared with the other breeds reared for meat. Pekins account for about 80 % of 
meat production and Barbary ducks for 20 %. Muscovy ducks are the heavier types. Drakes are 
normally heavier than female ducks (see Table 2.2). 

Ducks  are  kept  in  housing,  although  in  some  Member  States  outdoor  rearing  is  also  allowed. 
There are three main housing systems for the fattening of ducks: 

 

 

 

54 

fully littered, with or without water systems positioned above a gully; 

partly slatted/partly littered; 

fully slatted. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
The commonly applied duck house is a traditional housing system and is similar to the broiler 
house (Figure 2.6). It has a concrete floor that is covered with litter. The house is equipped with 
a ventilation system (natural or mechanical) and, depending on the climatic conditions, heating 
is applied. Partly or fully slatted floors are also used. 

Chapter 2 

Table 2.2:  Range of weights of duck breeds for meat and egg production 

Adult drake  
(kg) 

Adult duck 
(kg) 

3.00–4.50 
4.50–5.50 
4.50–5.00 

Meat breeds 
Pekin 
Muscovy 
Rouen 
Egg breeds  
Indian Runner 
Khaki Campbell 
Source: [ 506, TWG ILF BREF 2001 ] [ 365, France 2010 ] 

2.00–2.25 
2.25 

2.80–3.75 
2.25–3.00 
3.50–4.10 

1.60–2.00 
2.00 

Production cycles will vary between Member States. In Germany, the cycle for Pekin duck meat 
production consists  of a  growing  period  until  they  reach  16  days  old; followed by  a  finishing 
period  until  day  40–42,  and  a  final  weight  of  2.9–3.1 kg.  Growing  and  finishing  is  done  in 
separate  houses.  Manure  is  removed  and  houses  are  cleaned  and  disinfected  during  a  service 
period  of  about  five  to  seven  days,  before  they  are  stocked  again.  The  maximum  stocking 
density is 20 kg live weight/m2 of accessible floor area in both phases. Thus, the growing houses 
can accommodate  approximately 20 000 ducklings and the finishing houses about 6 000 ducks 
(see fact sheets in [39, Germany 2001]). In France, Barbary drakes and ducks are raised together 
on  fully  slatted  floors,  with  a  density  of  14.5  birds/m2  until  day  72,  when  females  are  then 
slaughtered. Males are reared until 85 days of age [ 365, France 2010 ]. 

The  fully  littered  system  is  commonly  applied,  using  wheat  or  barley  straw  (including  wood 
shavings for the ducklings). A suitably thick bedding layer, taking into account that the manure 
of  ducks  is  much  wetter  than  that  of  chicken  broilers,  is  crucial  for  the  good  health  and 
condition  of  the  birds;  a  daily  addition  is  normally  necessary  in  order  to  avoid  wet  litter. 
Approximately 3–4 kg of straw per duck is needed, generating triple the quantity of manure, i.e. 
9–12 kg of litter per duck at 30–35 % total solid content. Slatted flooring is also used, with the 
slats made out of plastic-coated wire or synthetic material. 

The rearing of ducks  has to comply with the provisions laid down in the  Council of Europe's 
'Recommendation concerning Muscovy ducks (cairina moschata) and hybrids of Muscovy and 
domestic ducks (anas platyrhynchos)' and 'Recommendation concerning Domestic ducks (anas 
platyrhynchos)'  as  adopted  by  the  Standing  Committee  of  the  European  Convention  for  the 
protection  of  animals  kept  for  farming  purposes  on  22  June  1999.  In  particular.  the  design, 
construction and maintenance of enclosures, buildings and equipment for ducks have to be such 
that they allow the fulfilment of the essential biological requirements of ducks, such as access to 
water for bathing or to water facilities  sufficient in number and so designed to allow water to 
cover  the  head  and  be  taken  up  by  the  beak  so  that  the  duck  can  shake  water  over  the  body 
without difficulty.  

2.2.3.4 

Production of guinea fowl 

Approximately  45  million  guinea  fowl  are  produced  in  Europe  per  year.  Of  the  total  EU 
production,  86 % is  situated  in  France, in  926  farms  incorporating  1 345  buildings  and  a total 
surface area of 437 000 m2 [ 365, France 2010 ]. A further 13 % of European production takes 
place in Italy. 

Intensive Rearing of Poultry or Pigs 

55 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Commercial  breeding  and  the  raising  of  guinea  keets  can  be  compared  with  that  of  turkeys. 
Guinea fowl are very different in their behaviour to chickens and need a lot of space: in France 
they are reared at a density of 16.8 birds/m2, until 78 days. Breeder guinea fowl (approximately 
350 000 in France) are raised in cages where artificial insemination is practised systematically. 
It  is  unclear  whether  there  are  any  farms  in  Europe  rearing  guinea  fowl  intensively  in  such 
numbers so as to be under the scope of Directive 2010/75/EU. 

2.2.4 

Control of poultry indoor environment  

Housing  systems  for  all  poultry  species  are  normally  equipped  to  maintain  the  indoor 
environment.  Factors  that  are  important  for  the  indoor  environment  in  poultry  housing  in 
general are: 

 

 

 

 

 

 

indoor air temperature and humidity (see Section 2.2.4.1); 

air composition and air velocity at the animal level (see Section 2.2.4.2); 

light intensity (see Section 2.2.4.5); 

dust concentration (see Section 2.2.4.3); 

stocking density; 

insulation of the building. 

Treatments applied to incoming air (principally for animal welfare reasons) generally comprise 
dust removal, cooling and/or humidification [ 264, Loyon et al. 2010 ]. Adjustments are usually 
made  by  controlling  the  temperature,  ventilation  and  lighting.  Minimum  health  standards  and 
production levels impose requirements on the indoor climate of poultry houses. 

2.2.4.1 

Temperature control 

The temperature in poultry houses is controlled by means of the following techniques: 

 

 

 

 

 

 

 

insulation of the building; 

local heating (deep litter systems) or space heating; 

direct  heating  (e.g.  infrared,  gas/air  heating,  gas  convectors,  hot-air  cannon)  or  indirect 
heating (central heating of space, central heating of underfloor); 

cooling by spraying of the roof (practised in warmer climates and in summer); 

cooling by spraying water mist, also known as fogging; 

wet filters (pad cooling systems); 

heat exchangers. 

Floors are often made of concrete and are normally not further insulated, except for broilers (see 
Section  4.6.4.1).  Partly  insulated  floors  are  sometimes  applied  while  in  the  northernmost 
countries floors are often fully insulated (e.g. Finland). There is a potential loss of heat from the 
housing by radiation to the soil underneath, but this is small and has not been reported as having 
an effect on production. Heating is sometimes applied through heat recovery from the exhaust 
air,  which  is  also  used  for  manure  drying.  For  layers,  heating  is  hardly  needed  when  the 
stocking density is high. 

56 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Generally,  in  winter,  but  also  during  the  early  stages  of  production  (young  birds),  heating  is 
applied to broilers, turkeys, ducks and pullets. Local heating is usually provided by gas radiators 
that  allow  the  animals  to  find  their  optimal  temperature  by  displacement  below  the  heater. 
Movement is sometimes restricted when the birds (of all species) are small, to keep them near 
the brooders. 

The  capacity  of  the  heating  equipment  is  related  to  the  number  of  birds  in  the  shed  and  the 
volume of the shed. For example, in Portugal, gas radiators with a capacity of 6 000 kJ are equal 
to 650 one-day-old birds per radiator, and a capacity of 12 500 kJ equates to 800 newborn birds. 
Some typical temperatures for the housing of broilers are shown in Table 2.3.  

Table 2.3:  Examples of required indoor temperature for broiler rearing  

Age (days) 

Indoor temperature (°C) 

Portugal (1) 
37–38 
35 
32 
28 

No heating 

1–3 
3–7 
7–14 
14–21 
21–29 
28–35 
Over 35 
(1) [ 8, Portugal 1999 ] 
(2) [ 40, NFU/NPA 2001 ] 
(3) [ 339, ITAVI 1997 ] 

UK (2) 
30–34 
32 
28–30 
27 

18–21 

France (3) 
31–33 
30–32 
28–30 
26–28 
26–23 
20–23 
18–20 

In turkey housing, the required temperature is higher (32–34 °C) at the beginning of the rearing 
period, so heating may initially need to be applied. When the birds grow, the indoor temperature 
is  gradually  decreased  (see  Table 2.4).  When  heating  the  turkey  housing,  more  ventilation  is 
needed and this results in higher energy consumption. On a number of farms in the Netherlands, 
recirculation of the air is practised, combining natural and mechanical ventilation. By operating 
valves, the airflow can be adjusted in such a way that the air is mixed properly, and less energy 
is then needed for heating.  

Table 2.4: 

Indoor temperature for rearing turkeys, applied in France 

Age (days) 

Temperature 
(°C) 
33.5–34 
32.5–33.5 
32–33 
31.5–32.5 
31 
29.5 
29 
28.5 
28 
27.5 
27 
Source: [ 339, ITAVI 1997 ] 

0–2 
3–4 
5–6 
7–8 
9–10 
1–14 
1–16 
17–18 
19–20 
21–22 
23–24 

Age (days) 

25–26 
27–28 
29–32 
33–34 
35–36 
37–38 
39–40 
41–42 
43–44 
+44 

Temperature 
(°C) 
26.5 
26 
25.5 
24.5 
24 
23.5 
23 
22.5 
21 
19–21 

During hot weather it may be necessary to lower the indoor temperature to ensure birds do not 
suffer  heat  stress.  Directive  2007/43/EC  of  28  June  2007  states  that  for  outdoor  temperatures 
higher than 30 °C, the interior temperature should not exceed the outside temperature by more 
than 3 °C.  

Intensive Rearing of Poultry or Pigs 

57 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

In practice, in spraying systems, plates located outside the building are used for injecting water 
into the incoming airflow, at a low pressure of 3 to 5 bar. These devices are the least expensive 
and  allow  a  maximum  cooling  of  3–5 °C  but  have  a  lower  cooling  efficiency,  e.g.  a  spraying 
device needs three to five times more water than a fogging system for the same cooling effect 
[ 358, France 2010 ]. 

The  main  cooling  techniques  used  in  poultry  farming  are  water  fogging  (see  Section 2.2.4.3) 
and wet filters (see Section 2.2.4.4) which are based on evaporative cooling. A farmer needs to 
utilise both air movement and evaporative cooling during hot weather to keep birds comfortable 
and productive, taking into account the relative humidity in the barn. 

2.2.4.2 

Ventilation of poultry housing 

Poultry housing can be naturally and/or forced ventilated, depending on the climatic conditions 
and  the  birds’  requirements.  Ventilation  has  the  objective  of  circulating  the  air  in  order  to 
provide fresh air and to remove gaseous products, heat and moisture to ensure a suitable indoor 
climate.  

The building can be designed to force the ventilation airstream across, or longitudinally through, 
the building or from an open ridge in the roof downwards via fans below the cages. For both 
natural  and  forced  ventilation  systems,  the  prevailing  wind  direction  may  influence  the 
positioning of the building, for instance it may increase  the required control of the ventilation 
airflow, as well as reduce emissions to sensitive receptors in the vicinity of the farm. Where low 
outdoor  temperatures  occur,  heating  equipment  may  be  installed  to  maintain  the  required 
temperature inside the building. 

Ventilation  is  important  for  the  birds’  health  and  will  therefore  affect  production  levels.  It  is 
applied when cooling is required, and for maintaining the composition of the indoor air at the 
required  levels.  For  broilers  for  example,  Directive  2007/43/EC  lays  down  minimum 
requirements environmental parameters that need to be ensured, namely: 

 

 

 

 

NH3 concentration not exceeding 20 ppm; 

CO2 concentration not exceeding 3 000 ppm; 

indoor temperature, when the outside temperature measured in the shade exceeds 30 °C, 
not exceeding this outside temperature by more than 3 °C; 

indoor average humidity, measured over 48 hours, not exceeding 70 % when the outdoor 
temperature is below 10 °C. 

Parameters  for  controlling  fan  speed  and  air  inlet  openings  may  include  temperature,  relative 
humidity  and  carbon  dioxide  concentration  which  are  monitored  by  appropriate  sensors. 
Additional air parameters can be controlled. For example, for the composition of air in broiler 
housing in Belgium-Flanders, upper limit values are also set for H2S at 20 ppm and for SO2 at 
5 ppm.  

Ventilation  systems  can  be  divided  into  natural  and  forced  systems.  Natural  systems  are 
comprised of openings in the ridges of the roof. Minimum outlet sizes are 2.5 cm2/m3 of housing 
volume, with a required inlet of 2.5 cm2/m3 on each side of the building. With natural systems, 
the  design  of  the  building  is  important  to  enhance  ventilation.  If  width  and  height  are  not 
properly matched, ventilation may be insufficient and may give rise to increased levels of odour 
inside the housing. 

Forced  (mechanical)  ventilation  systems,  where  ventilation  is  carried  out  through  the  use  of 
electrically powered fans in the walls or roof that are normally controlled by the temperature in 
the  building,  operate  under  negative  pressure  and  a  net  inlet  of  2 cm2/m3  of  housing  volume. 

58 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

They  are  more  expensive,  but  give  better  control  of  the  indoor  climate.  Different  designs  are 
applied, such as: 

 

 

 

 

roof/side  ventilation:  air  is  pulled  down  across  the  width  of  the  house  by  air  inlets  and 
fans in the roof and exits through side vents; 

ridge ventilation: air is drawn in through openings in side walls and forced out via fans on 
ridges; 

cross ventilation: air is pulled across the width of the house by air inlets and fans in side 
walls; 

tunnel ventilation: air is pulled down the length of the house with air inlets and fans in 
gable end walls.  

For layers housed in cages, the ventilation airflow ranges from 3 to 7 m3 per bird per hour in the 
summer (depending on the climate zone) and 0.5 to 0.8 m3 per bird per hour in the winter [ 39, 
Germany 2001 ]. 

Generally,  the  ventilation  capacity  of  4–6  m3  per  kg  live  weight  is  applied  in  the  design  of 
ventilation systems for broilers. The air speed at bird level varies with temperature, and speed 
levels of 0.1–0.3 m/s have been reported [ 8, Portugal 1999 ]. The ventilation capacity changes 
with the outside air temperature and relative humidity (RH) and with the age and live weight of 
the birds (CO2, water and heat requirements).  

The relationship between ventilation needs and the different variables  was reported in a study 
conducted  in  Belgium.  With  an  outside  air  temperature  of  15 °C  and  a  RH  of  60 %,  the 
ventilation was determined by the  CO2 balance in the first three days, by the water balance in 
the first 28 days, and after this by the heat balance. With lower outside air temperatures, the CO2 
balance  and  water  balance  become  more  important.  From  a  temperature  of  15 °C,  the  heat 
balance  becomes  more  important  in  combination  with  lower  RH  and  heavier chickens.  It  was 
concluded that a minimum ventilation requirement for broilers should be set at 1 m3 per kg live 
weight, to be prudent [ 509, Province Antwerpen 1999 ]. 

2.2.4.3 

Water fogging  

Fogging systems are a means of lowering the indoor temperature in regions with high summer 
temperatures,  and  controlling  humidity  and  dust.  The  key  characterisation  parameters  for  the 
equipment  are  pressure  and  design.  Water  is  sprayed  through  specially  designed  nozzles  and 
indoor air is cooled through evaporative cooling. 

The fogging system at medium pressure (< 70 bar) has a good cost efficiency but presents risks 
of litter moistening. The fogging system at a high pressure (> 70 bar) is more sensitive to the 
water quality and the clogging of the nozzle. The higher cooling efficiency makes it possible to 
obtain a reduction in temperature of up to 10 °C when the surrounding air is dry and the droplets 
fine enough (< 10 microns) [ 358, France 2010 ]. 

In combination with fans, evaporative cooling is combined with convective cooling: evaporation 
cools the air and fans, which are placed close to the nozzles, to create an airflow that intensifies 
the cooling effect. The benefits of this technique are: 

 

 

 

 

cooling effect; 

dust abatement (see Section 2.2.4.6); 

additive products can be sprayed simultaneously with water;  

cleaning of slatted floors, where present, is easier. 

Intensive Rearing of Poultry or Pigs 

59 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.2.4.4 

Pad cooling  

Pad cooling systems (or wet filters) are used to cool down the incoming air in poultry houses by 
a water evaporation effect. The system is most effective at high temperatures and low relative 
humidities. 

The pads are cellulose or plastic panels with a large specific surface area and are continuously 
kept soaked. The warm incoming air flows through the moist pads (by negative pressure), taking 
up humidity and cooling down in turn. Excess water is recirculated [ 358, France 2010 ]. 

The residual salinity of the circulating water and the possibility that pathogenic organisms can 
develop  on  the  large  surfaces  are  the  main  difficulties  encountered  with  the  management  of 
these systems. 

2.2.4.5 

Lighting of poultry housing 

Poultry  housing  may  use  only  artificial  light  or  may  allow  natural  light  to  enter  (sometimes 
called ‘daylight housing’). The laying activity and laying rate can be influenced by the use of 
artificial lighting.  

Minimum light intensity and light periods (lighting duration per day) are regulated by Directive 
1999/74/EC of 19 July 1999, laying down minimum standards for the protection of laying hens, 
and Directive  2007/43/EC of 28 June 2007, laying down minimum rules for the protection of 
chickens kept for meat production. In particular, the following requirements apply:  

 

 

In  broiler  houses,  a  lighting  intensity  of  at  least  20  lux  during  the  lighting  periods  and 
illuminating  at  least  80 %  of  the  usable  area  is  required  (temporary  reduction  may  be 
allowed following veterinary advice). In addition, within seven days from the time when 
the chickens are placed in the building and until three days before the foreseen time of 
slaughter,  the  lighting  must  follow  a  24-hour  rhythm  and  include  periods  of  darkness 
lasting  at  least  6  hours  in  total,  with  at least  one  uninterrupted  period  of  darkness  of  at 
least 4 hours, excluding dimming periods; 

For the production of laying hens, all buildings shall have light levels sufficient to allow 
all hens to see one another and be seen clearly, to investigate their surroundings visually 
and  to  show  normal  levels  of  activity.  After  the  first  days  of  conditioning,  the  lighting 
regime  must  follow  a  24-hour  rhythm  and  include  an  adequate  uninterrupted  period  of 
darkness lasting, by way of indication, about one third of the day. A period of twilight of 
sufficient duration ought to be provided when the light is dimmed, so that the hens may 
settle down.  

Different  lighting  schemes  are  applied  with  alternating  periods  of  light  and  darkness.  An 
example of lighting program is shown in Table 2.5 for broilers. 

Table 2.5:  Examples of lighting programmes for broiler production  

Age of birds (days) 

Light 
intensity 
(lux) 

Hours of 
light per 
day 

1–3 
4–10 
11–15 
16–21 
22–35 
36–42 

20 
5 
5 
5 
5 
5 

23 
8 
12 
16 
18 
23 

Source: [ 709, The Poultry Site 2017 ] 

60 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

In  laying  hens,  the  photoperiod  length  is  usually  between  12  and  17  hours  in  practice,  often 
increasing  as  the  birds  increase  in  age  (for  gonadal  stimulation).  Good  production  results  can 
also be achieved with intermittent photoperiods (alternating short periods of light and darkness). 
Light intensity necessary to keep a normal laying rate is 5 to 7 lux. Light intensities well over 
10 lux are usually avoided to prevent serious feather pecking.  

Where there is natural light in laying hen houses, apertures are often shaded or baffled to avoid 
direct  sunlight  and  thus  arranged  in  such  a  way  that  light  is  distributed  evenly  within  the 
accommodation. For the first few days after housing light may be fairly bright. Later the light 
intensity  should  be  such  as  to  prevent  health  and  behavioural  problems  [  38,  ASG  Lelystad 
2006 ]. 

In  turkey  rearing,  lighting  is  particularly  important  during  the  first  few  days  of  rearing  
(1–7 days), when programmes with a light intensity of at least 10 lux or more (up to 50 lux) and 
2 to 3 hours of darkness are applied. Afterwards, the light intensity is reduced. Light schemes 
can  vary  from  at  least  14 to 16  hours  a  day,  with  an  appropriate  period  of  rest  from  artificial 
lighting always available to birds in conformance with Directive 98/58/EC.  

2.2.4.6 

Control of dust 

Controlling  dust  at  source  not  only  reduces  emissions  to  the  external  environment,  but  also 
helps  to  maintain  a  better  indoor  environment  for  animals  and  workers.  Animal  activity  is 
normally a factor in increasing dust emission. Dust levels may also increase when the form of 
the feed is dusty, such as with some non-pelleted feeds for laying hens. Broiler feed is less dusty 
as  it  contains  a  higher  level  of  fat.  The  equipment  in  which  feed  is  administered  can  also 
increase  the  amount  of  airborne  dust.  Automatic  feeders  can  generate  dust  when  the  feed  is 
dropped into the troughs. 

Dust  emissions  are  generally  higher  in  houses  using  bedding  than  in  enriched  cages.  Oil 
spraying is an inexpensive and effective abatement method, removing airborne dust by binding 
it to oil in the litter (see Section  4.8.4); however, cleaning of the houses can be more difficult 
and the quality of the litter can be affected.  

Dry  filters  can  be  fitted  to  internal  air  recirculation  units.  Negative  ionisation  of  indoor  air 
deposits  fine  dust  on  surfaces  which  can  easily  be  removed  after  each  growing  cycle  (see 
Figure 2.7). 

Source: [ 377, Netherlands 2010 ] 

Figure 2.7:  Effect of dust attraction caused by ionisation on the roof of a poultry shed 

Intensive Rearing of Poultry or Pigs 

61 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Water fogging (see Section 4.8.3) produces small droplets that absorb airborne particles and fall 
on the floor. It is important that the size of water and dust particles are similar, in the range of a 
few  micrometres.  If  the  sprayed  droplets  are  too  large,  the  dust  particles  flow  around  the 
droplets and are not absorbed, as little or no contact occurs.  

2.2.5 

Poultry feed and drink supply  

2.2.5.1 

Poultry feed formulation 

Feeding is very important, as it determines the quality of the end products. For example, broiler 
growth (reaching the required weight in only 5 to 8 weeks) depends largely on feed quality. The 
way feed is obtained varies from the purchase of ready-to-use feed mixtures to on-farm milling 
and preparation of the required mixtures, which are often stored in silos adjacent to the birds’ 
housing. The formulation of poultry feed  has also  to meet the requirements of the  animals by 
ensuring  the  right  level  of  energy  and  essential  nutrients,  such  as  amino  acids,  vitamins  and 
minerals. 

In  poultry  production,  the  energy  value  of  a  feed  (ingredient  or  diet)  is  expressed  as  the 
metabolisable  energy  (ME)  as  it  is  not  possible  to  measure  the  digestible  energy  (DE)  since 
faeces  and  urine  are  not  separated  and  because  of  the  negligible  energy  losses  of  the  heat 
increment which is needed for the formulation of net energy (NE).  

The essential amino acids (or indispensable amino acids) are those that the animal metabolism 
cannot provide or can only provide in small quantities. Therefore, essential amino acids must be 
supplied  through  the  diet  in  sufficient  quantities  to  cover  the  animals'  requirements.  The 
essential  amino  acids  are  methionine  (+cystine),  lysine,  threonine,  valine,  isoleucine,  leucine, 
tryptophan, arginine, histidine and phenylalanine (+tyrosine).  

Cystine is not an essential amino acid per se, but methionine can only be made from cysteine 
and thus they are always linked. In formulations of poultry feed, the most frequent amino acid 
deficiencies  are  sulphur  amino  acids  (methionine  and  cysteine)  and  lysine.  Another  quoted 
deficiency is typically threonine [ 506, TWG ILF BREF 2001 ]. However, latest developments 
in the production of amino acids means more amino acids are now available for better poultry 
feed formulations. 

In  the  formulation  of  feeds  for  poultry  nutrition,  the  ideal  protein  is  a  concept  where  the 
optimum indispensable amino acids supply is described in terms of ratios to lysine  (which has 
been used as a reference because it is the first limiting amino acid for growth in pigs) and where 
any deficiency of one of the indispensable amino acids will compromise growth and/or health. 
In this profile, all indispensable amino acids are equally essential for performance, just covering 
the requirements for all physiological functions. In practical nutrition, this offers the advantage 
that  the  lysine  requirement  will  vary  (per  kg  of  feed  or  per  MJ  of  energy),  but  not  the  ideal 
amino  acids  profile  expressed  relative  to  lysine.  Each  of  these  ratios  can  thus  be  directly 
introduced as a constraint in feed formulation. 

Formulating  feeds  can  require the  use  of  linear  programming  to  obtain the required  mixtures. 
Layers, in particular, require sufficient calcium to produce the eggshell. Phosphorus is important 
for its role in the storage of calcium in the bones and will either be fed as a supplement or made 
more readily available from feedstuffs used in the diet by, for example, adding phytase to the 
feed. Other minerals (trace elements) in the feed can be varyingly controlled as well: Na, K, Cl, 
I, Fe, Cu, Mn, Se and Zn, while others like S and F are already sufficiently available in the feed. 
Vitamins are not produced by the animals themselves, or are produced in insufficient quantities, 
and  should  therefore  be  added  to  the  daily  ration.  Vitamins  are  often  part  of  a  premix  with 
minerals. 

62 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

The  use  of  additives  in  animal  feed  is  regulated  at  European  Union  level  (Commission 
Regulations  1831/2003  and  429/2008).  Each  additive  is  evaluated  for  safety  and  efficacy,  as 
well as for the way it is used in animal nutrition. Only after a thorough risk assessment is each 
feed  additive  authorised  for  use  accompanied  by  the  conditions  of  that  use  and  its  effects, 
indicating the  minimum and  maximum dosage in feeds, for which species it is applicable, the 
appropriate age of the animal and whether a withdrawal period has to be observed. 

The  composition  of  poultry  feed  also  varies  considerably  between  Member  States,  as  it  is  a 
mixture of different ingredients, such as: 

 

 

 

 

cereals grains, their products and by-products; 

oilseeds,  oil  fruits,  their  products  and  by-products,  tubers,  roots,  their  products  and  by-
products; 

other seeds and fruits, their products and by-products; 

milk products and fish, other marine animals, their products and by-products. 

Meat and bone meal is banned in Europe. In Spain, pork lard is added to the feed because of the 
lack  of the  enzyme  lactase,  but  milk  products  are  not  included.  In  the  UK,  ‘bulbs,  tubers  and 
roots or root crops’ are not fed to poultry. In France, animal fats are not used. In Danish broiler 
production,  wholewheat  is  added  to  the  broiler  feed  at  the  farm,  from  day  10.  The  share  of 
wholewheat in the total feed is initially 2 % at day 10 and is then continuously increased up to 
30–35 % at the end of the production cycle.  

Different substances can be added to poultry feed for different reasons, e.g.: 

 

 

 

 

 

Some substances are added in small amounts, but can have a positive effect on growth, by 
increasing the weight gained and  improving the feed conversion ratio (FCR). Enzymes, 
herbs,  essential  oils,  immunostimulants  and  organic  acids  are  examples  of  substances 
used (compounds of Cu and Zn may also be included in this category). 

Some substances raise the nutritional quality of the feed (e.g. vitamins, trace elements). 

Some substances improve the technical quality of the feed, e.g. technological additives, 
such as those that can improve the pressing of feed into granules. 

Some  substances  balance  the  protein  quality  of  the  feed,  therefore  improving  the 
protein/nitrogen conversion (pure amino acids). 

Some  substances  increase  the  digestibility  of  phosphorus  of  plant  origin,  therefore 
improving phosphorus uptake from feed (e.g. the enzyme phytase). 

The use of antibiotics as feed additives in animal feed to stimulate growth is prohibited under 
EU  Regulation  No  1831/2003/EC.  Coccidiostats  and  histomonostats  may  be  added  to  prevent 
the development of parasites. Such products are regulated as additives in animal nutrition. 

Apart  from  the  feed  formulation,  different  types  of  feeding  regimes  are  also  adopted  during 
production  cycles  to  match  the  feed  more  closely  to  the  requirements  of  the  birds.  For  the 
different categories, the following numbers of feeds are most commonly applied: 

 

 

 

 

layers: 

2 phases (feeding up to laying, during laying); 

broilers: 

3–4 phases (early weeks growing, finishing); 

turkeys: 

4–6 phases (more types for stags than for hens); 

ducks: 

2–3 phases. 

Intensive Rearing of Poultry or Pigs 

63 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

Layers  can  also  have  six-phase  feeding,  three  phases  up  to  laying  (pullets)  and  three  phases 
during laying, or two to three phases up to laying (pullets) and one or two phases during laying 
[ 40,  NFU/NPA  2001  ]  [  506,  TWG  ILF  BREF  2001  ].  Feeding  programmes  for  broilers  are 
affected  by  the  strain  of  bird,  as  well  as  the  sex  and  market  age  or  market  weight  
[ 327, Germany 2010 ]. 

2.2.5.2 

Feeding systems 

Feeding practices depend on the type of production and bird species. Feed is given in mashed 
form, crumbs, or pellets. Layers are generally fed ad libitum [ 40, NFU/NPA 2001 ] [ 30, Spain 
2001 ]. Meat species, such as broilers and turkeys, are also fed ad libitum. Hand feeding is still 
applied, but in large enterprises modern feeding systems are applied that reduce the spillage of 
feed and that allow accurate (phase) feeding.  

Common feeding systems are: 

 

 

 

 

chain feed conveyor; 

auger conveyor; 

feeding pans; 

moving feed hopper. 

Chain  feed  conveyors  move  feed  from  the  storage  area  through  to  the  feeding  gutter.  It  is 
possible to influence the feeding pattern, spilling and rationing by adjusting the velocity of the 
conveyor.  Chain  feed  conveyors  are  common  in  floor  systems  and  are  also  applied  in  cage 
systems. In the auger conveyor, feed is pushed or pulled through the feeding gutter by a spiral. 
Spillage is low. Application is common in floor systems and aviary systems. 

Feeding pans or bowls are connected with supply via the transport system. The diameter varies 
from  300 mm  to  400  mm.  Feed  is  transported  by  a  spiral,  chain  or  a  steel  rod  with  small 
scrapers. The system is designed with a lifting device. They are applied in floor systems (e.g. 
broilers, turkeys and ducks). In the case of bowls, one bowl feeds approximately 65–70 birds. 
For  the feeding  of  turkeys,  feeding  pans  are  used  in  the  earlier life  stage  but, at  a  later stage, 
feeding  barrels  (50–60 kg)  are  also  used.  Feed  is  supplied  in  large  buckets  or  square  feeding 
troughs. Tube feeding systems are increasingly applied to reduce spillage. 

A feed hopper is a moving system  that  moves alongside the cages on wheels  or a rail, and is 
equipped  with  a  funnel-shaped  hopper.  Moved  by  hand  or  electrically,  this  system  fills  the 
feeding trays or gutters. 

Examples of feeding space allowances (in the UK) for meat poultry species are as follows: 

 

 

 

 

64 

Broiler, pan feeders: 1 linear metre per 100 birds. 

Broiler, chain feeders: 0.75 linear metre per 100 birds. 

Turkeys, pan feeders: 1 linear metre per 100 birds. 

Ducks, trough space: 50 cm per 100 birds from 1 day old to 8 weeks of age, 60 cm per 
100 birds of 8 weeks of age and over. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.2.5.3 

Drinking water supply systems 

All  animals  must  have  permanent  access  to  a  suitable  water  supply  or  be  able to  satisfy  their 
fluid intake needs by other means (Directive 98/58/EC). For all poultry species water has to be 
available  without  restriction.  Birds  need  water  to  control  their  body  temperature,  as  well  to 
support the digestion of the feed provided. The drinking water system is also used to provide 
additional  micronutrients  to  birds  in  case  of  additional  requirements.  Techniques  applying 
restricted  watering  have  been  tried  but  for  welfare  reasons  this  practice  is  no  longer  allowed 
(except for breeders).  

Various drinking systems are applied. Design, proper maintenance and control of the drinking 
system aim to provide sufficient water at all times and, at the same time, to prevent leakages and 
spillage  and,  therefore,  wetting  of  the  litter.  Natural  drinking  behaviour  also  has  to  be 
considered, e.g. hens drink by putting their beak into the water, and then lifting their head and 
letting the water run down their throat. 
There are different drinking systems: 

 

 

 

 

high-capacity nipple drinkers (around 80–90 ml/min or higher); 

low-capacity nipple drinkers (around 30–50 ml/min); 

round (or bell) drinkers; 

water troughs (or cup drinkers); 

Nipple  drinkers  are  often  used  in  automatic  watering  systems  designed  to  provide  water  on 
demand to broilers or laying hens. They improve water hygiene and reduce evaporation.  

Nipple drinkers have various designs. Usually, they are made of a combination of  plastic and 
steel and are placed underneath the water supply pipe. A pressure control system is installed at 
the beginning of each pipe, with a water gauge to measure consumption. Pressure regulation in 
water lines is a critical aspect as leaking is often the result of the wrong water pressure (e.g. any 
slope in the floor and long pipelines may create pressure differences in the system). Drinkers are 
generally designed to produce optimal results within a certain pressure range.  

High-capacity nipple drinkers have the advantage that the bird quickly receives a proper amount 
of  water,  but  have  the  disadvantage  of  leaking  water  during  drinking.  To  catch  this  leakage, 
small cups are installed underneath the nipples (drip cups). Nipple drinkers with a drip cup are 
the  most  economical  in  water  consumption.  Low-capacity  nipple  drinkers  are  not  affected  by 
leakage, but drinking takes longer with nipples than with bell drinkers. In non-cage systems for 
laying hens, the drinking hens may block other hens on their way to the nest, and so eggs may 
be laid in incorrect places [ 407, Netherlands 2002 ].  

In floor housing, the nipple drinker system can be installed in such a way that it can be lifted out 
(for  example  for  cleaning  and  mucking  out).  It  works  with  low  pressure.  Additionally,  the 
nipple line is generally positioned above the birds’ heads and gradually raised as the birds grow 
to  avoid  water leaking  and  spoiling  the  litter underfoot.  Additionally,  some  individuals'  water 
intake (and hence food intake) may be constrained through inefficient use of nipples, and these 
and other slower-growing birds may find it increasingly difficult to obtain water as nipple lines 
are raised progressively during the growing period [ 624, IRPP TWG 2013 ].  

Round  drinkers  are  small,  circular  plastic  containers  of  different  designs  (e.g.  bell-shaped 
designs)  depending  on  the  type  of  bird  or  the  system  they  are  applied  to.  They  are  usually 
attached  to  a  winch  line  and  can  be  pulled  up.  They  work  on  low  pressure  and  are  easily 
adjustable. Round drinkers (or bell drinkers) are the oldest systems but are still widely used in 
turkey and duck rearing. They incur a notable waste of water because even a minimal movement 
of  a  bird´s  head  leads  to  spillages.  Stabilisers  are  also  applied  to  prevent  tipping  over  
[ 357, France 2010 ]. 

Intensive Rearing of Poultry or Pigs 

65 

 
 
 
 
 
 
 
 
 
Chapter 2 

Water troughs (or cup drinkers) are containers providing water which are placed on or below the 
water supply pipe. Cups are either filled with water all the time or filled when a metal strip is 
touched by a bird. Other valves can also be used to trigger water delivery, e.g. a floating ball for 
young poultry that cannot force valves to open. Cup drinkers are placed in groups or in lines and 
can minimise stagnant water; however, they can be more complicated to keep clean.  

In most layer housing systems, automatic watering systems are applied using nipple drinkers. In 
the Netherlands, 90 % of the water supply systems for layers are nipple drinkers and 10 % are 
round  drinkers  [  407,  Netherlands  2002  ].  The  number  of  birds  serviced  in  France  by  the 
different types of drinking systems is shown in Table 2.6. 

Table 2.6:  Number of birds serviced by each type of drinking equipment in France  

Species 

Starter 

Serviced birds  Grower/Finisher 

Round drinker  
Nipple drinker  
Drinker with cup  
Large cup 
Round drinker  
Mini-cup  
Large cup 
Nipple drinker  
Drinker with cup  

100–150 
10–20 
200–250 
60 
50–200 
20 
100 
8–10 
200–250 

Round drinker  

50 

Broiler 

Turkey  

Duck 

Serviced birds 
100–130 
15–18 
200–250 

100–120 
20 
100 
100–120 
135 

120–150 

Round drinker  
Nipple drinker  
Drinker with cup  

Round drinker  
Mini-cup  
Large cup 
Nipple drinker  
Drinker with cup  
Round drinker, 
wide channel 
Nipple drinker (1) 
Round drinker  
Nipple drinker  

5–7 
50 
15 
(1) When nipple drinkers are provided as the drinking source, then an additional water source must also 

Nipple drinker (1) 
Round drinker  
Nipple drinker  

5–7 
100–130 
15 

Guinea fowl 

be provided, such as troughs, bell drinkers, baths or showers. 

Source: [ 357, France 2010 ] [ 500, IRPP TWG 2011 ] 

In broiler houses, watering points are installed in many places, frequently using a combination 
of round drinkers and nipples drinkers. The round drinker design gives every bird easy access to 
water and aims at limiting spillage, to prevent wetting the litter.  

In the UK, nipple drinkers are more commonly applied for broilers than round drinkers. In the 
Netherlands, only 10 % of the water supply systems for broilers are nipple drinkers and 90 % 
are round drinkers. In France, 80 % of broiler farms use nipple drinkers, 15 % bell drinkers and 
5 % cup drinkers [ 40, NFU/NPA 2001 ] [ 407, Netherlands 2002 ] [ 357, France 2010 ]. 

Drinking  water  for turkeys  is supplied  using  round  drinkers  or  water troughs. Round  drinkers 
and  troughs  can  differ  in  size  according  to  the  stage  of  production  (smaller  or  larger  birds). 
Nipple  drinkers  are  generally  not  applied,  as  turkeys  do  not  use  these  effectively.  In  France, 
30 %  of  turkey  farms  use  nipple  drinkers,  20 %  use  cup  drinkers  and  50  %  bell  drinkers  
[ 357, France 2010 ]. 

For duck rearing in the UK, a minimum water drinker space of 60 cm per 100 birds should be 
provided. The most commonly used source is the bell drinker. Ongoing research in the UK aims 
to determine the height, width and depth of the most suitable trough-type drinkers. Where nipple 
drinkers  are  provided  as  the  drinking  source,  then  an  additional  water  source  should  also  be 
provided, such as troughs, bell drinkers, baths or showers. In France, 75 % of duck farms use 
bell drinkers and the rest nipple drinkers [ 357, France 2010 ]. 

66 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.3 

Pig production 

2.3.1 

Pig housing and manure collection 

In intensive pig production systems, separate phases of production are recognised which require 
different feeding and housing conditions: 

 

 

 

breeding (including mating, gestating, farrowing and neonatal period); 

weaning;  

fattening (growing and finishing).  

The gestation length of the sow is approximately 112 to 115 days. The average litter size in the 
EU  is  11.  After  birth,  piglets  are  nursed  by  their  dams  for  approximately  21  to  28  (in  some 
Member States up to 35) days. During this phase of production in most Member States, male 
piglets that will not be used for breeding are surgically castrated. 

After  weaning,  piglets  are generally  moved  to  -  and  mixed  with  -  members  of other  litters  in 
specially designed housing systems for weaners. This phase presents the greatest management 
challenge  as  dietetic  changes  (from  milk  to  solid  foods  at  this  early  age)  are  frequently 
associated with disease outbreaks. After about  5 weeks, when  the piglets reach approximately 
30 kg  live  weight  the  weaned  pigs  are  moved  on  to  further  accommodation  to  finish  their 
growth prior to slaughter.  

As  the  selection  of  individuals  to  fill  pens  in  the  fattening  houses  is  based  on  live  weight, 
members  of  different  litters  may  become  pen  mates  in  the  fattening  pens.  There  are  a  few 
instances  where  pigs  are  housed  together  during  the  entire  rearing  period  from  weaning  to 
slaughter.  However,  due  to  economic  reasons,  different  management  and  environmental 
requirements during the production phases, these systems are rare. The length of time that pigs 
spend in the fattening sheds will be determined by their growth rate as in most systems the live 
weight determines the time of slaughter. The weight of carcasses will depend on the demand for 
meat cuts. 

Housing  system  designs  are  affected  by  a  number  of  factors  including  climate,  legislation, 
economics,  farm  structure  and  ownership,  research  and  traditions.  EU  legislation,  combined 
with certain socio-economic issues, has had a great impact on pig housing systems in Member 
States. Changes have also come about because of retailing standards applied in certain Member 
States which have had a major effect on the production methods used by some producers [ 495, 
EFSA 2007 ].  

Production  systems  can  be  divided  into  two  main  categories,  those  based  on  liquid  manure 
(slurry)  and  those  based  on  solid  manure.  Some  of  these  systems  provide  different  climatic 
zones where the pig can choose its microclimate for various activities (i.e. for resting in kennels 
or under thermo-boards). The main common characteristics of both systems, for all animal types 
(sows, weaners, fattening pigs), are given below. 

Techniques based on slurry 
In liquid manure techniques, fully or partly slatted (or perforated) floors with slurry channels or 
pits situated underneath are used. Housing systems with slatted floors are the most widely used 
throughout  the  EU.  Hygiene  is  maintained  in  these  systems,  usually  in  the  absence  of  any 
bedding (or bedding is used only in relatively small quantities, e.g. as occupational material), by 
the installation of slatted or perforated floors through which the excreta can fall and be stored in 
a physically separate place to that occupied by the animals. Slurry can be stored in the animal 
house  or  removed  continuously  or  periodically  (e.g.  at  the  end  of  the  production  cycle)  via 
channels and pipes to outdoor storage. 

Intensive Rearing of Poultry or Pigs 

67 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Floors  may  be  fully  slatted  over  the  entire  pen  area,  or  have  a  solid  concrete  lying  area 
combined with a slatted dunging area. Pens with partly slatted floors may require more space 
than fully slatted floors. Partly slatted floor systems need to provide enough space for pigs to be 
able to maintain separate and distinct lying and dunging areas, so that the solid portion of the 
floor and the pigs can be kept clean. Some pens are therefore equipped with two floor types that 
differ in the degree of perforation (i.e. 40 % versus 10 %; the area with lower perforation being 
intended for lying) in order to lessen the risk of reduced cleanliness.  

Slats  can  be  made  of  concrete,  metal  (mostly  iron)  or  plastic  and  have  different  shapes  (e.g. 
triangular),  although  the  use  of  composite  materials  is  increasing.  One  critical  component  for 
the  efficient  use  of  slatted  floors  is  the  dimension  of  the  gap  between  slats  in  relation  to  the 
dimensions of the animal feet at any given age.  

Directive 2008/120/EC of 18 December 2008 lays down minimum standards for the protection 
of  pigs  and,  among  other  things,  imposes  a  maximum  width  of  openings  in  concrete  slatted 
floors  according  to  pig  category.  The  maximum  width  of  the  openings  must  be  11 mm  for 
piglets, 14 mm for weaners, 18 mm for rearing pigs and 20 mm for gilts after service and sows. 
Directive 2008/120/EC also determines the minimum slat width, which is 50 mm for piglets and 
weaners, and 80 mm for rearing pigs, gilts after service and sows [ 158, EC 2008 ].  

The  manufacture  of  precast  concrete  flooring 
is  covered  by  a  European  Standard 
(EN +A1:2007),  consistent  with  Council  Directive  2001/88/EC.  This  standard  specifies  both 
minimum  and  maximum  gap  and  beam  widths  for  precast  concrete  floors  together  with  a 
manufacturing  tolerance.  The  top  of  the  beams  are  not  permitted  to  have  sharp  edges;  where 
radius or chamfer are provided these shall not exceed 3 mm. 

Concrete slats have proved to be more durable than other materials, such as metal and plastic. 
Smooth  finishes  facilitate  cleaning  and  ensure  that  no  faecal  matter  builds  up.  Systems  for 
removing manure and urine are related to the flooring system and as such are described in the 
context of housing systems. These systems may vary from deep pits with a long storage period 
to shallow pits and manure channels through which the slurry is removed frequently by gravity 
and valves, by flushing with a liquid or by scraping.  

The base and walls of the slurry pit, including the channels for slurry transfer, are usually built 
of reinforced concrete cast in situ, precast reinforced concrete modules or concrete blocks sealed 
with  a  waterproof  coating.  Channels  have  a  flat  or  a  V-shaped  base.  V-shaped  channels  are 
prone to potential blockages caused by solids left behind as the liquid fraction of the slurry may 
run off faster during evacuation [ 175, Ecodyn 2010 ] [ 624, IRPP TWG 2013 ]. 

Moreover,  some  countries  have  formulated  demands  stricter  than  or  additional  to  the  EU 
legislation with respect to floor area, floor design, or provision of natural light. For example, in 
Denmark  and  the  Netherlands,  the  requirement  for  continuous  solid  floor  space  is  greater  for 
most  pigs  and  the  maximum  drainage  opening  smaller  than  those  mentioned  in  the  EU 
Directive;  in  Sweden,  there  is  a  ban  on  fully  slatted  floors  in  all  pig  housing;  in  Germany, 
houses for the rearing of fattening pigs are required to have at least 50 % continuous solid floor 
[ 201, Mul M. et al 2010 ]. 

In general, there is increasing attention being paid to the provision of manipulable materials to 
animals, in  order  to  provide  them  with  the  opportunity  to  behave  naturally  (foraging,  rooting, 
nesting, etc.). When these behavioural needs are not met, which can be different for the different 
pig categories, a range of adverse welfare consequences result, one of these being an increased 
risk of tail biting in weaners and fattening pigs [ 566, EFSA 2014 ].  

Techniques based on solid manure 
In  solid  manure  techniques,  the  solid  floors  of  the  pens  are  littered  with  bedding  material  in 
order to bind urine and faeces in the litter. Straw and other materials, such as wood shavings, 
sawdust and peat (in Finland) are used. Bedding materials should be comfortable to lie on, non-

68 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
abrasive,  non-slippery,  highly  absorbent  and  have  low  levels  of  environmental  bacteria  and 
mycotoxin  contamination.  Bedding  materials  have  different  capacities  to  absorb  moisture,  in 
proportion to their dry weight. The absorbency and characteristics of different bedding materials 
are presented in Table 2.7.  

Chapter 2 

Table 2.7:  Absorbency and characteristics of different bedding types 

Bedding material 

Mean absorbency 
factor 
(kg water absorbed/kg 
material 

Sawdust (1) 

Barley straw (1) 

Wheat straw (1) 

Oat straw 

Triticale straw (1) 

Cornstalks 

Shredded paper (1) 

2.60 

1.91 

2.14 

2.86 

1.97 

2.70 

2.08 

Wood  chips/Coarse 
wood shavings 

NI 

Peat 

3.8–5.2 

Remarks 

to 

Coarse  sawdust  is  extremely  absorbent.  Fine 
sawdust is not a suitable bedding material due to 
potential  health  problems  for  workers  and 
animals because of increased dust emissions. 
Commonly  used  for  pigs;  soft  and  does  not 
contain  much  dust.  The  least  absorbent  of  all 
straw types. 
The  most  commonly  used  material  for  pigs; 
quite brittle, not as soft as barley and with wider 
stalks. The least palatable of all the straws. 
Softer  than  wheat  straw  and,  therefore,  more 
absorbent  than  all  other  straws.  It  can  be 
expensive  due 
feed  value.  Highly 
its 
palatable; however, very light and fluffy so will 
blow away quite easily in outdoor units. 
Similar to  wheat straw, although a  little harder. 
It  produces  a  30 %  larger  volume  of  straw 
compared with the equivalent yield of wheat or 
barley straw. 
Only available when the cob is  used for animal 
feed rather than when the whole plant is used for 
silage. 
Dust-free, very absorbent and costs little. 
Excellent  bedding  material  especially 
for 
farrowing  sows.  Light  to  handle  and  easy  to 
transport  packaged  in  bales.  Also  works  well 
mixed with straw. 
Good drainage properties.  Can be obtained free 
of  charge  from  processing  plants  and  joinery 
manufacture, thus incurring only transport costs. 
Likely  the  most  cost-effective  option  when 
produced on farm from home-grown or recycled 
wood. Can also be used underneath straw. Wood 
chips produced from wood that has been treated 
with  chemical  preservatives  or  glues  cannot  be 
used as a bedding material. 
Peat  has  a  very  high  absorption  capacity.  High 
dust  emissions  are  associated  with  its  use  as  a 
litter material, mainly during its application. 

(1) Values calculated on the basis of the information reported in reference [ 388, BPEX 2011 ]. 
NB: NI = no information provided. 

Source: [ 388, BPEX 2011 ] [ 624, IRPP TWG 2013 ] 

Straw  is  a  manipulable  material  enabling  rooting.  It  also  provides  thermal  insulation  and 
physical  cushioning,  as  well  as  having  a  moderate  absorption  capacity,  making  it  an effective 
bedding material. The viability of straw (availability and cost) is affected by plant harvests and 
competition  from  different  uses  (e.g.  biofuel).  In  the  UK,  pig  farms  typically  use  wheat  and 
barley straw and occasionally oat straw. 

Intensive Rearing of Poultry or Pigs 

69 

 
 
 
 
 
 
 
Chapter 2 

Due  to  the  large  surface  area  and  the  high  C : N  ratio,  straw  can  reduce  emissions  of  NH3  if 
properly  managed  (i.e.  keeping  the  litter  dry  by  more  frequent  straw  addition  or  manure 
removal,  hence  at  an  additional  cost)  but,  on  the  other  hand,  may  also  result  in  the  in  situ 
composting  of  the  litter  and  hence  increased  litter  temperature  and  NH3  emissions  
[ 252, IGER 2005 ].  

Additionally, compared to slurry management, straw bedding may lead to significantly higher 
emissions of greenhouse gases (methane and nitrous oxide). Nevertheless, CH4 emissions from 
the straw-based sow housing systems are not greater than the emissions from the slurry-based 
systems, as it seems that CH4 produced in the deeper anaerobic layers of the litter bed is readily 
oxidised to CO2 in the surface layer, due to aeration by the rooting and foraging behaviour of 
the pigs [ 441, Webb et al. 2012 ]. Finally, provision of straw, especially straw of poor quality, 
and the use of wood chips and sawdust will increase the production of airborne particles such as 
dust,  moulds  and  fungi  associated  with  respiratory  disturbances  in  pigs  and  humans  [  495, 
EFSA 2007 ]. 

Use of straw in pig housing is expected to increase due to concern for the welfare of the pigs. In 
conjunction with (automatically controlled) naturally ventilated housing systems, straw allows 
the animals to self-regulate their temperature with less ventilation and heating, reducing energy 
consumption. The integrated evaluation of straw use should consider the added cost of the straw 
and  mucking  out  the  pens;  possible  increased  emissions  from  storage  and  landspreading  with 
straw; and the benefit of adding organic matter to the soil [ 508, TFRN 2014 ]. 
[ 500, IRPP TWG 2011 ] 

For litter-based systems, even though there are a number of designs and layouts of the animal 
house and different practices for manure management, two main methods of litter management 
can be distinguished.  

a. Littered-floor system (or 'scraped litter'): In scraped systems, the lying and dunging areas are 
made  structurally  distinct  and  the  manure  is  removed  at  frequent  intervals  from  the  dunging 
area.  Animals  are  provided  with  little  to  moderate  amounts  of  litter  which  serves  as  an 
absorptive and manipulable material [ 495, EFSA 2007 ]. 

When  straw  is  used  as  bedding  material,  the  manure  is  scraped  with  a  typical  frequency  of 
between two and three times a week or manually removed from once or twice a week up to a 
daily frequency. Topping up with fresh dry litter is regularly carried out in order to prevent the 
litter from becoming too wet; this operation replaces the amount of straw which is removed with 
the  manure.  The  smaller  the  amount  of  litter  applied,  the  higher  the  risk  of  an  increase  in 
humidity and ammonia emissions. Floors can be sloped to one end to allow the collection of the 
manure resulting from the mixture of dung and straw. 

b.  Deep  litter  (or  'accumulated  litter'):  The  litter  accumulates  on  the  floor  and  a  permanently 
thick  bedding  is  provided.  Fresh  straw  is  added  upon  necessity  (usually  every  week)  over 
accumulating  manure,  which  is  removed  at  the  end  of  the  rearing  period  or  can  remain  for 
periods  longer  than  one  production  cycle  (removal  after  successive  production  cycles).  This 
period  can  range  from  a  few  weeks  (piglets,  sows)  to  several  months  (fattening  pigs,  sows). 
After the bedding material is spread, litter may need to be stirred, since pigs tend to defecate in 
the same area of the pen. The abundance of bedding can alleviate the effect of low temperatures.  

In deep litter systems, the whole area occupied by the animal has to be kept clean and dry by 
regular  provision  of  absorbent  bedding  material.  In  such  systems  the  animals  will  often 
subdivide  the  pen  area  into  separate  lying  and  dunging  areas,  choosing  to  lie  in  the  most 
thermally comfortable and undisturbed areas and excreting in areas of the pen which are cold, 
wet or draughty. Space requirements are therefore greater in these systems compared with fully 
or partly slatted pens [ 495, EFSA 2007 ]. 

70 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 2 

In the case of sawdust used as a bedding material, only a deep litter system is used; this can be a 
thick (60–80 cm) or thin (15–20 cm) bedding. The majority of sawdust bedding is provided at 
the start of the production cycle. The deep sawdust bedding is used for several batches and the 
surface layer is removed at the end of the cycle. In the case of thin sawdust bedding, no sawdust 
is added during the cycle and manure is removed at its end [ 262, France 2010 ].  

In  insulated  buildings  (and  during  summer  periods  in  uninsulated  ones)  the  upper  critical 
temperature  of  the  deep  bedding  systems,  especially  when  the  bedding  is  fermenting  and 
producing  a  large  amount  of  heat,  may  be  critical  in  creating  thermoregulatory  problems, 
resulting  in  heat  stress  and  decreased  performance;  the  heat  production  will  also  lead  to 
increased evaporation of water [ 495, EFSA 2007 ].  

Sections 2.3.1.1, 2.3.1.2, 2.3.1.3 and 2.3.1.4 give technical descriptions of the housing systems 
commonly  applied  for  sows,  weaners  and  fattening  pigs  (growers/finishers).  Their 
environmental performances and other characteristics are described and evaluated in Chapter 4. 
The overview aims to be representative of the applied techniques, but can never be exhaustive 
given the variation observed in systems and their adapted designs.  

2.3.1.1 

Housing systems for mating and gestating sows 

Sows are housed in different systems depending on the phase of the reproduction cycle. Mating 
sows are kept in systems which facilitate easy contact between boars and sows. After mating or 
after pregnancy diagnosis, the sows are usually moved to a separate part of the housing for the 
period of gestation. 

Housing  sows  in  groups  or  individually  in  confinement  is  regulated  by  2008/120/EC.  In 
compliance  with  this  Directive,  individual  housing  is permitted  for  sows  and  gilts  only  in  the 
first  4  weeks  after service and  the last  week  before  the  expected time  of farrowing.  Directive 
2008/120/EC also addresses the cases where group housing may have drawbacks, e.g. animals 
that are particularly aggressive or that are sick or injured may be temporarily kept in individual 
pens,  designed  to  allow  the  animal  to  turn  around  easily;  it  also  imposes  feeding  systems  for 
group housing that ensure that each animal can obtain sufficient food even when competitors for 
the food are present. Directive 2008/120/EC as well gives provisions for continuous solid floors 
and maximum drainage openings for gilts after service and pregnant sows: at least 0.95 m2 per 
gilt  and  1.3  m2  per  sow  must  be  a  continuous  solid  floor  of  which  a  maximum  of  15 %  is 
reserved for drainage openings. In addition, the total unobstructed floor area available to each 
gilt after service and to each sow when gilts and/or sows are kept in groups must be at least 1.64 
m2  and  2.25  m2  respectively.  When  these  animals  are  kept  in  groups  of  fewer  than  six 
individuals the unobstructed floor area must be increased by 10 %. When these animals are kept 
in  groups  of  40  or  more  individuals  the  unobstructed  floor  area  may  be  decreased  by  10  % 
[ 158, EC 2008 ]. 

Individual  housing  used  to  be  the  most  common  system  within  the  EU.  Individual  housing 
systems  generally  score  better  on  utilisation  of  labour.  In  addition,  since  individually  housed 
sows are limited in their movement, they are easier to control and there is more tranquillity in 
the stall, which has a positive effect in the early stages of gestation [ 202, EAAP 1998 ]. It is 
also easier to feed the sows in individual housing, where competition is minimised or negated. 
On  the  other  hand,  housing  sows  in  individual stalls,  from  the  weaning  period up  to  4  weeks 
after mating, severely restricts their freedom of movement, causes frustration and does not allow 
sows  to  socially  interact  during  a  period  of  the  reproductive  cycle  in  which  they  are  highly 
motivated to do so. In addition, the lack of exercise may cause damage and weakness to limbs 
and  bone  strength  as  a  consequence  of  reduced  muscle  use,  and  also  reduce  cardiovascular 
competence  [  494,  EFSA  2007  ].  With  the  entry  into  force  of  the  pig  welfare  Directive 
(2008/120/EC), individual pens may only coexist along with pens for groups. 

Intensive Rearing of Poultry or Pigs 

71 

 
 
 
 
 
 
 
 
 
Chapter 2 

Some countries' demands go beyond the EU legislation concerning standards for the protection 
of  pigs.  As  regards  the  minimum  unobstructed  floor  space,  which  depends  on  group  size,  in 
Austria, Germany, Denmark, Sweden, Finland and the Netherlands, the minimum unobstructed 
floor  space  requirement  per  gilt  is  greater  than  that  required  by  the  EU  legislation.  Extra 
demands  for  sows  in  groups  exist  in  Denmark  and  Sweden  while  Germany  and  Austria  have 
limited additional requirements. The requirements for continuous solid floor space is greater for 
most  pigs  and  the  maximum  drainage  opening  is  smaller  in  Denmark  and  in  the  Netherlands 
than mentioned in the EU Directive. As regards the group housing of pregnant sows and gilts, in 
the UK non-lactating sows should be kept in groups and there is no exception for 4 weeks after 
service, while in Sweden sows and gilts should always be housed in groups (except farrowing 
sows and sows 1 week before farrowing); in the Netherlands sows and gilts should be kept in 
groups starting from four days after service until 1 week before farrowing [ 201, Mul M. et al 
2010 ]. 

In the UK, certified programmes, mainly promoting and ensuring the production of quality food 
(farm assurance standards), can impose increased space allowances for animal welfare purposes 
[  419,  Red Tractor  2011  ].  In  the  UK,  85 %  of  mating  sows  are  group-housed  and  more  than 
55 % of mating sows have access to straw, as a result of British welfare legislation requiring all 
sows  to  be  loose-housed  from  weaning  to  farrowing  by  1999.  In  Poland,  production  on  solid 
floor with bedding is also commonly applied. In the Czech Republic, dry sows awaiting mating 
and gestation are kept in yards [ 264, Loyon et al. 2010 ]. 

In general, partly slatted floors are commonly applied throughout Europe, whereas fully slatted 
floors are only used in some Member States (e.g. France, Belgium). The slurry is either stored in 
deep pits or it is removed frequently by a vacuum system; other systems like flushing channels 
are  only  rarely  applied.  Scrapers  are  also  used  when  sows  are  housed  on  litter  (e.g.  Sweden, 
Denmark, the Czech Republic, Cyprus, Finland) [ 264, Loyon et al. 2010 ]. 

Buildings  are  generally  well  insulated,  or,  less  frequently,  partly  insulated.  Open  climate 
housing  is  rarely  applied  on  IED  farms.  Heating,  whether  by  electricity  or  gas/oil,  is  applied 
locally above animals to a defined area, otherwise the air entering the house is preheated [ 264, 
Loyon et al. 2010 ]. 

Only in some Member States (especially Cyprus, Denmark, Germany) is air conditioning or the 
pretreatment of incoming air to the housing commonly applied. Exhaust air treatment is used in 
the Netherlands, Belgium, Denmark and Germany but it is hardly used in the other EU Member 
States [ 264, Loyon et al. 2010 ]. 

2.3.1.1.1 

Individual housing with a fully or partly slatted floor for mating and 
gestating sows 

In  this  type  of  housing  system,  mating  and  gestating  sows  are  kept  in  individual  crates.  The 
crates  measure  about  2.0–2.1 m × 0.60–0.65  m  and  the  rear  end  is  equipped  with  concrete  or 
metal  slats  to  collect  slurry  in  a  deep  pit  or  shallow  channel  which  is  emptied  at  intervals 
depending on its capacity. The area the sow is allowed is such that she cannot turn around and 
excreta  are  deposited  at  a  fixed  location.  The  partitions  of  the  crates  are  barred  or  meshed  to 
allow  visual  contact  but  prevent  aggression.  Natural  or  mechanical  ventilation  is  applied  and 
sometimes a heating system. 

Feeding systems and drinkers are placed at the front end. Feeding may be manual or automatic 
(one to three times per day) and feed may be given dry or wet. Wet feeding systems can vary 
from the simple dropping of individual dry rations into water to complex pipeline distribution 
systems  from  a  central,  computer-controlled  mixing  facility.  Sows  commonly  have  a  trough 
which is either individual or shared (four to six sows) to allow the possibility of keeping sows of 
the same body size or condition in adjacent crates [ 494, EFSA 2007 ].  

72 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

Flooring  is  most  commonly  partly  slatted,  although  fully  slatted  floor  systems  do  occur  
[  494,  EFSA  2007  ].  A  central  slatted  passageway  runs  between  the  rows  of  crates  and  a 
concrete-floored one runs on either side of the crates for feeding.  

In the mating house, there are pens for housing the boars. These pens are absent in the housing 
section  for  gestating  sows.  Figure 2.8  shows  a  common  design  for  the  mating  section,  but 
various other designs are applied to enhance intensive contact between boar and sows. Also, the 
sows may face the central alley with the troughs placed on the inner side and the slatted area 
will be at the side corridors (see Figure 2.9). 

Source: [ 678, NSW DPI 2006 ] 

Figure 2.8:  Schematic view of a housing design for mating sows  

Intensive Rearing of Poultry or Pigs 

73 

 
 
 
 
 
 
 
Chapter 2 

Source: [ 163, Germany 2010 ] 

Figure 2.9:  Individual housing of mating sows (service centre) 

2.3.1.1.2 

Sow crates with a solid floor for mating and gestating sows  

In this system, mating and gestating sows are housed in crates similar to the above design but 
with  a  concrete  floor  often  with  a  layer  of  straw  bedding  to  produce  solid  manure  or 
farmyard manure (see Figure 2.10). Again, feeding and watering are applied at the front of the 
crate.  In  the  central  passageway  there  is  a  drainage  system  for  the  collection  and  removal  of 
urine. Manure and litter (straw, wood shavings or other where applied) are removed frequently 
[ 262, France 2010 ]. 

Figure 2.10:  Floor design for sow crates with a solid concrete floor for mating and gestating sows 

In  these  systems  ventilation  is  natural  when  straw  is  applied,  but  mechanically  driven  in 
insulated buildings where no straw is used. 

74 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.3.1.1.3 

Group housing with or without straw for mating and gestating sows 

In  this  housing  design,  several  sows  are  kept  together  in  enclosed  compartments  or  pens. 
Individual feeding stalls (0.4–0.5 m × 1.9–2.0 m) can be used to separate the sows temporarily 
during feeding, preventing dominant individuals from chasing off less dominant sows in order 
to  get  access  to  extra  feed  rations.  The  total  free  space  available  (excluding  feeding  stalls)  is 
commonly  2.25–2.8  m2  per  sow  depending  on  group  size.  The  feeding  areas  are  placed  over 
slatted floors and they can be combined with shared lying (perforated or solid floor with limited 
use of bedding material) and defecating areas (slatted flooring). Design varies with group size, 
which  is  highly  variable  (e.g.  from  5  to  40)  [  494,  EFSA  2007  ].  An  example  is  shown  in 
Figure 2.11.  

Source: [ 494, EFSA 2007 ] 

Figure 2.11:  Example  of  a  housing  system  for  group  housing  of  gestating  sows  with  individual 

feeding stalls and shared lying and defecating area 

A  solid  concrete floor  with  straw  bedding  in the  lying  area can  also  be  used  to  produce  solid 
manure (see Figure 2.12). 

Intensive Rearing of Poultry or Pigs 

75 

 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 494, EFSA 2007 ] 

Figure 2.12:  Example  of  group  housing  for  gestating  sows  with  individual  feeding  stalls  in 

combination with full litter 

Group housing of pregnant sows in pens with trough or floor feeding without use of individual 
feeding  stalls  is  also  commonly  used.  Flooring  is  solid  or  slatted.  Small  amounts  of  bedding 
material are used on the lying area. Groups are kept stable and small (< 10 animals) in order to 
reduce aggressive behaviour during feeding. Gilts are less dominant to each other, thus these are 
more often found in this type of system than older sows  [ 494, EFSA 2007 ]. A design with a 
perforated floor in the lying area, is shown in Figure 2.13. 

Source: [ 156, Germany 2010 ] 

Figure 2.13:  Example of group housing for  mating and gestating sows with perforated lying area 

(perforation in the lying area < 15 %)  

76 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 2 

For the ventilation of group housing, the same principles applies as for the individual housing of 
sows. Natural ventilation is an option in new deep litter housing systems. With the application 
of straw, heating is generally not applied as at low temperatures the sows are able to compensate 
by lying amongst the deep litter.  

Solid manure is generated and has to be frequently removed in order to prevent the litter from 
becoming  too  moist,  the  frequency  of  removal  depending  on  the  litter  type,  the  depth  of  the 
bedded  area  and  on  the  general  farm  management  practices.  In  units  where  bedding  is  used 
exclusively for rooting, the amount of litter is limited  so  that all the manure is handled in the 
form of slurry. In units with a slatted floor in the defecating and feeding areas, slurry may be 
emptied  using  scrapers.  In  units  with  solid  flooring,  the  manure  is  cleaned  either  daily  with 
scrapers or two to three times a week using a tractor-mounted tyre scraper. In units with deep 
litter in the lying area, the litter is removed once or twice annually. 

2.3.1.1.4 

Group housing with electronic feeders 

In  this  system,  sows  are  often  kept  in  large  dynamic  groups  (50–300  sows)  with  common 
dunging  and  lying  areas.  In  the  electronic  sow  feeder  systems  (ESFs)  each  sow  carries  an 
electronic  transponder  (ear  tag  or  collar)  allowing  passage  to  a  feeder  station.  A  precisely 
measured  individual  ration  of  food  is  then  dispensed  to  that  animal  which  is  protected  while 
eating  by  a  specialised  feeding  stall  with  gates  operated  by  the  sow  herself  or  by  the  feeding 
computer. A single feeding station can be shared by up to 70 sows [ 494, EFSA 2007 ].  

The pen layout is very important to  distribute and manage  large  groups of sows fed this way, 
since ESFs allow a profit for a reduced space per sow. Indeed, for groups of 40 animals or more, 
the  minimal  space  is  2.025  m2  per  sow  and  1.476  m2  per  gilt.  Pens  have  a  lying  area,  a 
defecating area and a feeding area where electronic sow feeders are placed. The lying areas are 
on solid concrete floors from which the manure is removed daily by a scraper tractor. Pens can 
be arranged on concrete slats or on straw.  

The version on  a slatted floor allows an available surface per sow of 2.20–2.66 m2. Short pen 
divisions may also be used to create boxes approximately two metres long. Stalls or boxes can 
be laid out at both sides of the corridors which are broad enough to allow two sows to pass each 
other (see Figure 2.14). 

The version with littered pens has a large area of 50–120 m2 where sows can lie and which is 
opposite a feeding and defecating zone. The total surface per sow is between 2.3 m2 and 3 m2 
and the minimal surface of the lying area is 1.2–1.4 m2 per sow. Litter is added and removed 
every 7–10 days in quantities between 200 and 450 kg/sow per year. 

The  feeding  stations  have  one  entrance  but  may  have  one  or  two  exits,  hence  allowing  the 
workers to direct animals to different areas as needed [ 262, France 2010 ]. 

Intensive Rearing of Poultry or Pigs 

77 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 262, France 2010 ] 

Figure 2.14:  Layout of a pen for gestating sows fed with an electronic feeder  

2.3.1.2 

Housing systems for farrowing sows 

Gestating sows are typically moved to farrowing accommodation three to seven days before the 
expected  farrowing  date  (115  days  after  service).  Sows  remain  in  the  farrowing  crate  or 
individual pen throughout lactation.  

There are different designs of farrowing pens. Flooring can be partly or fully slatted. Bedding is 
not  usually  provided.  In  accordance  with  Directive  2008/120/EC,  in  the  week  before  the 
expected  farrowing  time  sows  and  gilts  must  be  given  suitable nesting  material  in  sufficient 
quantity unless it is not technically feasible for the slurry system used in the establishment.  

The sows are often confined in their movement by farrowing crates, but loose-housing is also 
applied. For example, straw-based and loose-housing can be found in the UK. In some Member 
States, the use of farrowing crates is restricted to a limited period around the time of farrowing. 
However,  in  the  EU  as  a  whole,  the  use  of  farrowing  crates  throughout  lactation  is  the 
predominant  system  [  494,  EFSA  2007  ].  In  accordance  with  the  provisions  of  Directive 
2008/120/EC, farrowing pens where sows are kept loose must have some means of protecting 
the  piglets,  such  as  farrowing  rails.  Where  a  farrowing  crate  is  used,  the  piglets  must  have 
sufficient space to be able to be suckled without difficulty. 

Fully slatted flooring is applied widely in the EU, as it is considered to be more hygienic and 
labour  efficient  than  partly  slatted  or  solid  floors.  In  France,  93.6 %  of  the  total  capacity  for 
sows are housed on fully slatted floors [ 262, France 2010 ]. Danish information indicates that 
partly slatted floor systems are more energy-efficient and a gradual increase in these systems is 
being observed.  

Some general features of farrowing compartments are: 

 

 

 

 

78 

applied minimum room temperature of 18 °C; 

temperature for the sows of 16–18 °C; 

distinct safe lying area for piglets with a temperature of about 33 °C at the start of their 
lives; 

low airflow, in particular in the piglet area. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.3.1.2.1 

Housing for farrowing sows with confined movement 

The use of farrowing crates for this period predominates. These crates, typically 2.1 m × 0.9 m 
in size, are designed to restrict the movement of the sow and are placed centrally or offset in a 
pen which has a specialised provision for the piglets. Pen sizes measure 4–5 m2. 

In order to allow all in - all out production, farrowing rooms often contain a complete farrowing 
batch in one air space; this number can be up to 50–60 sows. Use of crates which can be opened 
out in such a way to allow the sow to move around more freely, including a full 360 degree turn, 
while still protecting the piglets from being crushed, is increasing. 

Piglets are housed in these systems until weaning, after which they are sold or reared in rearing 
pens (weaner housing). The floor can be fully or partly slatted. The lying area for the piglets is 
usually not slatted. Slats made of plastic or plastic-coated metal are increasingly used instead of 
concrete, as they are considered to be more comfortable. The design of the system can vary in 
the position of the piglet area and the applied slats. 

The slurry is stored under the slatted floor of the crates either in a shallow manure pit, in which 
case it is removed frequently via a central system in the building, or in a deep pit, from where it 
is removed only at the end of the lactating period or less frequently. A cross section of a typical 
pen system for farrowing sows is shown in Figure 2.15.  

There is a specific area for the piglets (the 'creep area'), usually positioned in the central alley 
(for easier observation) between the pens. This area is generally not slatted and is heated during 
the first days after birth by using a hanging lamp, a heat pad, by warming the floor or it may be 
an enclosed area to maintain  a higher temperature. The sow’s movement is limited to prevent 
crushing the piglets. 

Forced or natural ventilation is applied in such a way that the airflow will not disturb the climate 
at the floor level around sow and piglets and the different requirements for indoor environment 
conditions for sows and piglets are both met. In modern closed housing, fully automatic climate 
control is applied, thereby maintaining the temperature and humidity in the farrowing section at 
a constant level. 

The position of the sow is often as pictured in Figure 2.15, but the crates may also be reversed 
with the sows facing the alley. In practice, some farmers have observed that this position makes 
the sows more relaxed, as they can more easily notice movements in the alley, whereas in the 
other position they cannot turn, which makes them more restless. 

Source: [ 292, Italy 2001 ] 

Figure 2.15:  Example of confined housing of farrowing sows on a fully slatted floor with a storage 

pit underneath 

Intensive Rearing of Poultry or Pigs 

79 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.3.1.2.2 

Housing of farrowing sows allowing sow movement 

Farrowing  sows  are  housed  without  being  confined  in  their  movement  in  systems  with  partly 
slatted  floors.  A  separate  lying  area  for  the  piglets  prevents  them  from  being  crushed  by  the 
sow. This design requires more space than the design with restricted sow movement and needs 
more frequent cleaning. The number of pens or sows per compartment is generally less than 10. 

The  use  of  individual  pens  for  the  farrowing  sow  and  piglets  is  common  in  Member  States 
where  farrowing  crates  are  no  longer  allowed.  These  may  be  simple  pens  of  approximately 
2.0 m × 3.0 m with anti-crushing rails around the walls and a heated creep area for the piglets 
(see  Figure 2.16)  [  494,  EFSA  2007  ].  In  Sweden,  for  example,  farrowing  pens  must  have  a 
continuous solid floor area of at least 3 m2, a total floor area of at least 6 m2 and the farrowing 
pens should be constructed in such a manner as to allow nesting behaviour [ 201, Mul M. et al 
2010 ]. 

Beneath  the  slatted  flooring,  scrapers  or liquid  manure  systems  are  used. The  type  of  manure 
handling system influences the possibility to use straw during farrowing. These pens sometimes 
contain  a  temporary  crate  structure  made  by  moving  a  partition  into  place  at  the  time  of 
farrowing  (see  Figure 2.16);  this  reduces  the  total  space  available  when  the  sow  is  loose  
[ 494, EFSA 2007 ]. Temporary confinement of the sow can last up to seven days.  

Material for the floor system and heating and ventilation requirements for  the sow and piglets 
are  the  same  than  for  confined  movement.  With  loose  sow  housing,  the  walls  of  the  pen  are 
slightly higher than for the pen with restricted movement. 

NB:  Left:  Farrowing  pen  with  anti-crush  rails.  Right:  Farrowing  pen  with  gates  that  can  be  used  for  temporary 

confinement of the sow 

Source: [ 494, EFSA 2007 ] 

Figure 2.16:  Farrowing pens allowing sow movement 

Indoor  group  farrowing  systems  are in  use in  commercial  practice  but  only  to  a  small  extent. 
These  systems  operate  very  differently  compared  to  conventional  ones.  Five  to  ten  sows  are 
kept  in  groups  where  each  sow  has  access  to  an  individual  farrowing  nest  and  a  communal 
resting  area,  often  on  deep  straw  bedding.  In  this  system,  the  sows  are  moved  to  the  big  pen 
some days before farrowing and along the walls a cubicle is put up for each sow. There are no 
rails, creep area or heat lamp in the cubicle as it can distort the interaction between the sow and 
piglets during the nest phase. The nest boxes are taken out when the piglets have left the nest, 
usually 10 to 14 days after farrowing. Sows and piglets are then grouped in a ‘multisuckling’ 
system in the deep bedded system until weaning. Group housing systems for farrowing sows are 
reported to be in use in farms in Sweden [ 494, EFSA 2007 ].  

80 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.3.1.3 

Housing systems for weaners 

After  weaning,  the  sow  is  returned  to  service  accommodation  and  the  piglets  are  commonly 
moved immediately to the weaner accommodation. Piglets are typically weaned at 4 weeks and 
up  to  6  weeks  of  age.  In  accordance  with  Directive  2008/120/EC,  no  piglets  shall  be  weaned 
from the sow at less than 28 days of age, unless the welfare or health of the sow or the piglets 
would  otherwise  be  adversely  affected.  However,  piglets  may  be  weaned  up  to  seven  days 
earlier if they are moved into specialised houses which first need to be emptied and thoroughly 
cleaned and disinfected before the introduction of a new group. Furthermore, these houses have 
to be kept separate from houses where sows are kept, in order to minimise the transmission of 
diseases to the piglets. 

Weaners are commonly reared up to 30 kg live weight (range from 20 kg to 35 kg) in groups of 
varying  sizes.  Rearing  is  commonly  done  in  groups  of  less  than  20  animals,  such  as  in  small 
groups of the same litter (8–12 pigs per pen), but group sizes of up to 100 animals consisting of 
more  litters  are  also  common.  According  to  the  provisions  of  Directive  2008/120/EC,  the 
minimum unobstructed floor space available per weaner in the pen must be at least 0.15 m2 for a 
live weight of less than 10 kg, 0.20 m2 for a live weight between 10 kg and 20 kg, 0.30 m2 for a 
live weight of more than 20 kg but less than 30 kg and 0.4 m2 for a live weight of more than 
30 kg [ 158, EC 2008 ]. 

Weaners  may  be  moved  from  the  first stage  weaner accommodation  to a  larger,  second  stage 
accommodation  after  2–4  weeks  or  remain  in  the  same  pen  until  the  age  of  about  
9–10 weeks or, in a few instances, until slaughter [ 495, EFSA 2007 ]. 

A variety of housing systems are used. Weaners are typically reared either in conventional pens 
with partly or fully slatted floors or in flat decks (raised pens). Housing of weaners on fully or 
partly slatted floors is very similar to the housing of fattening pigs (growers/finishers).  

The fully slatted flooring is favoured for hygiene reasons as it separates piglets from their faeces 
and  urine  (Figure 2.17).  However,  fully  slatted  floors  are  not  easily  compatible  with  straw  or 
other rooting materials. 

Source: [ 182, Germany 2010 ] 

Figure 2.17:  Schematic picture of a fully slatted floor pen for weaners  

Partly  slatted  floors  are  mainly  used  in  Poland,  the  Czech  Republic,  Sweden,  Denmark  and 
Estonia [ 264, Loyon et al. 2010 ]. Partly slatted floor designs are applied to add comfort areas 
with  heated  spaces  (see  Figure 2.18).  Pens  with  partly  slatted  floors  may  require  more  space 
allowance than fully slatted floors as they need to provide enough space for pigs to be able to 

Intensive Rearing of Poultry or Pigs 

81 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

maintain separate and distinct lying  and defecating areas, so that the solid portion of the floor 
and the pigs can be kept clean [ 495, EFSA 2007 ]. In the partly slatted design, a covered lying 
area can be applied, which can be removed or lifted once the pigs have grown and need more 
ventilation. 

Source: [ 184, Germany 2010 ] 

Figure 2.18:  Schematic picture of a weaner pen with a partly slatted floor  

A  special  housing  design  for  weaners  is  the  use  of  flat  decks  that  are  intended  to  provide 
controlled  environment  housing.  It  originally  comprised  a  low,  well-insulated  building  with  a 
linked heating and ventilation system to maintain temperature at any desired level. Each house 
contains several pens with fully slatted floors above a slurry channel.  The pen floor level was 
originally  raised  (in  comparison  to  that  of  the  passage  floor),  but  more  recent  designs  have 
passages and pen floors at the same level. The system has evolved over the years and the term is 
loosely  describe  any  slurry-based  housing  system  for  weaners  
to 
now  often  used 
[ 636, Ramiran 2011 ].  

Systems  with  a  solid  floor  and  bedding  are  also  used  in  countries  such  as  Poland,  the  UK, 
Austria, Sweden,  the Czech Republic, Italy, Germany and Estonia [ 264, Loyon et al. 2010 ]. 
The  use  of  solid  floors  with  deep  litter  is  increasing  in  the  UK  and  is  anticipated  to  become 
more widespread in the future because of animal welfare concerns. Nevertheless, solid manure 
on a solid floor may compromise pig gut health due to increased exposure to microorganisms.  

Weaners  are  typically  housed  in  highly  controlled  environments  with  supplementary  heating. 
Room temperatures are maintained in the range of 28–30 °C for the first few days after weaning 
and are then reduced as the weaners grow (non-bedded systems). Heating is applied in the form 
of  gas  radiant  heaters,  electric  fan  or  convection  heaters  or  by  a  central  heating  plant  with 
heating pipes. Heating systems may also use recovered ground and/or air source heat. 

The  housing  is  equipped  with  mechanical  ventilation,  either  a  negative  pressure  or  balanced 
pressure  type.  Ventilation  is  almost  exclusively  provided  by  extractor  fans.  Typically,  air  is 
drawn  into  each  room  through  inlets  in  one  end  of  the  room  from  an  access  passageway 
common  to  a  group  of  flat  deck  rooms.  Inlet  air  might  be  preheated,  as  necessary,  by 
automatically  controlled  heaters.  Extractor  fans,  normally  situated  in  the  opposite  wall,  are 
intended  to  create  air  movements  across  the  room,  and  radiant  heaters  above  the  pens  (or 
underfloor heating) may be used to provide additional temperature/comfort control. 

82 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

Weaners are typically fed ad libitum (dry) or restricted (liquid) with an animal to feeder space 
ratio of 1 : 1 to 12 : 1, depending on the feeding system [ 495, EFSA 2007 ].  

Manure is handled in the form of slurry and is mainly drained through a pipe discharge, where 
the individual sections of the manure channels are emptied via plugs in the pipes. The channels 
can also be drained via sluice gates. The channels are cleaned after the removal of each group of 
pigs, often in connection with the cleaning of the pens, i.e. at intervals of 6 to 8 weeks. For the 
storage and removal of slurry, deep pit and frequent removal by vacuum systems are the most 
commonly  applied  techniques.  Manure  removal  by  scraper  is  also  used  [  264,  Loyon  et  al. 
2010 ]. 

2.3.1.4 

Housing of fattening pigs 

From  an  average  live  weight  of  30 kg  (20–35 kg),  pigs  are  moved  to  separate  sections  to  be 
grown and finished for slaughter. It is common to use two (or three) housing stages with larger 
pens  at  each  stage  in  the  fattening  period,  to  make  the  most  efficient  use  of  space,  but  the 
housing facilities are very much the same (i.e. one-phase up to 110–120 kg, two-phase with a 
grower period up to 40–60 kg and a finisher period from 40–60 kg to 110–120 kg; Italy: 150–
170 kg). Slaughter weights may be lower (e.g. in the UK: 90 kg) in countries where male pigs 
are not castrated after birth [ 495, EFSA 2007 ].  

There  are  many  different  construction  techniques  for  the  fattening  housing  such  as  insulated 
concrete,  composite  panels,  insulated  brick,  etc.  Buildings  are,  in  general,  well  insulated  and 
may have supplementary heating (depending on the prevailing weather conditions). Heating is 
mostly provided by electricity, gas or oil and sometimes by a mixture of all sources of energy. 
Wood, straw and other renewable sources are also used as a fuel, especially in Nordic countries. 
Ventilation  can  be  natural  or  forced  which  is  the  main  option  in  nearly  all  countries. 
Nonetheless,  the  use  of  controlled  natural  ventilation  is  also  important  in  some  countries, 
including Italy, Germany, Cyprus, Poland, Portugal and France. In Spain, Finland and Denmark, 
air conditioning is commonly applied. Ventilation with pretreated air is used in Spain, Poland 
and Denmark [ 264, Loyon et al. 2010 ].  

The number of pigs per house can range from a few to thousands [ 624, IRPP TWG 2013 ]. The 
house is usually divided into compartments for 10–15 pigs (small groups); however, the number 
of fattening pig houses with large group sizes is increasing (24 pigs up to 40 or more). The pens 
are arranged either with the aisle on one side or in a double row with the aisle in the centre. In 
the pens with a solid concrete floor, movable covers can be used to cover the lying area, at least 
during the first stage of the growing period. 

Feed  distribution  is  usually  automated  to  sensor-controlled  feeders,  adjusted  to  the  respective 
growing phase of the pigs. Liquid or dry feeding is applied ad libitum or may be restricted in the 
latter stages to prevent excessive fatness or with very heavy slaughter weights (> 120 kg). The 
design of feeding troughs and drinkers depends on the type of feeding.  

Accommodation  for  fattening  pigs  may  be  fully  slatted,  partly  slatted,  litter-based  with  a 
scraped  defecating  area  or  deep  bedded  with  straw  or  sawdust.  Although  there  are  national 
differences, housing with fully or partly slatted flooring (typically on concrete slats with 17 mm 
slot  spacing)  with  a  pen  floor  area  of  0.7  m2  at  the  end  of  the  finishing  period  predominates 
within  the  EU.  The  recommended  common  temperature  range  for  buildings  with  non-bedded 
perforated floors is 20–26 °C [ 495, EFSA 2007 ]. 

Partly slatted floors are mostly used in countries such as the Netherlands, the Czech Republic 
and  Denmark.  In  Ireland,  France  and  Germany  fully  slatted  floors  prevail  and  in  Spain  both 
types  of  floor  are  used  with  the  proportion  of  slatted  to solid floor being  60 : 40.  In  Belgium, 
fully  slatted  floors  are  prevalent  in  old  housing  or  in  new  houses  equipped  with  a  chemical 
scrubbing system. In the UK, straw bedding is common. Both systems for the storage of slurry 
are common: underground deep pit and frequent removal by channel systems [ 264, Loyon et al. 
2010 ].  

Intensive Rearing of Poultry or Pigs 

83 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.3.1.4.1 

Housing of fattening pigs on a fully slatted floor 

Housing systems with fully slatted floors are widely used throughout the EU. In these systems, 
slats  cover  the  entire  pen  area,  usually  to  maintain  hygiene  and  cleanliness  by  allowing  for  a 
quick  removal  of  faeces  and  urine  from  the  immediate  environment  of  the  animal,  and  thus 
favouring the conditions for a dry lying area. In addition, slatted floors are generally associated 
with lower airborne toxin concentrations than litter-based systems due to the potential bacterial 
contamination of straw and other litter materials.  

Slatted floors should have a sufficient perforation in order to keep the pen clean of manure and 
urine; on the other hand, the gap between slats should not endanger the animals, in accordance 
with Directive 2008/120/EC. 

The fully slatted floor housing system is very common for small groups (10–15) pigs and large 
groups  (up  to  24)  of  fattening  pigs  (growers/finishers).  It  is  applied  in  closed,  thermally 
insulated  housing  with  mechanical  ventilation,  as  well  as  in  houses  with  natural  ventilation. 
Windows allow daylight in, but electric lighting is also used. Auxiliary heating is applied only 
when necessary, as the pigs’ body heat is usually capable of satisfying the heat requirement. 

The pen is fully slatted and has no physical separation of the lying, eating and defecating areas. 
The slats are made of concrete or (plastic-coated) metal. Urine mixes with the manure or runs 
off through urine/liquid manure channels. The slurry is collected in a manure pit under the fully 
slatted floor. Depending on the depth of the pit, it may provide for an extended indoor storage 
period  (thus  high  ammonia  levels  in  the  house)  or  it  is  emptied  frequently  and  the  slurry  is 
stored  in  a  separate  storage  facility.  A  frequently  applied  system  has  the  individual  sections 
connected by a central drain, into which they are emptied by lifting a plug or a gate in the pipe. 

Point  4  of  Annex  I,  Chapter  I  of  the  Directive  2008/120/EC  concerning  the  welfare  of  pigs, 
states that 'pigs must have permanent access to a sufficient quantity of material to enable proper 
investigation and manipulation activities, such as straw, hay, wood, sawdust, peat or a mixture 
of such, which does not compromise the health of the animals'; the provision of such material 
may  be  somewhat  difficult  in  the  case  of  housing  systems  with  fully  slatted  floors  [  158,  EC 
2008 ]. A Scientific Opinion issued by EFSA concludes that 'stocking density, associated with 
lack of enrichment and fully slatted floors, is a significant risk for tail biting'. Tail biting may 
cause  very  poor  welfare,  and  tail  docking  is  likely  to  be painful [  495,  EFSA  2007  ].  Careful 
management  and  design  can  fulfil  the  pigs’  behavioural  needs,  therefore  avoiding  routine  tail 
docking.  In  slatted  floor  systems,  enrichment  material  (i.e.  straw,  hay)  can  be  provided  in 
feeders  or  racks  [  624,  IRPP  TWG  2013  ].  However,  as  the  problem  of  tail  biting  is  mainly 
multi-factorial, other parameters (e.g. poor indoor air quality) also have to be considered [ 495, 
EFSA 2007 ]. 

2.3.1.4.2 

Housing of fattening pigs on a partly slatted floor 

Partly slatted floor systems are applied in similar buildings to those used for fully slatted floor 
systems. The floor is divided into a slatted and a solid/non-slatted section. There are basically 
two options: to have the solid concrete floor on one side or in the centre of the pen. The solid 
part can be flat (see Figure 2.19), convex (see Figure 2.20) or slightly inclined (see description 
below).  

84 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 192, Germany 2010 ] 

Figure 2.19:  Design of a partly slatted floor system for fattening pigs  

Source: [ 265, BE Flanders 2010 ] 

Figure 2.20:  Pen  design  for  fattening  pigs  with  partly  slatted  (convex)  floor  and  solid  area  in  the 

centre 

The solid part usually functions as a feeding and resting place and the slatted part of the pen is 
designed  to  be  used  for  defecating.  Generally,  partly  slatted  floor  systems,  preferably  with  a 
raised  level  of  the  slatted  part,  allow  for  a  fairly  good  supply  of  straw  [  495,  EFSA  2007  ]. 
Slurry is collected in a channel or pit beneath the slatted part of the floor. 

In another pen layout, restricted amounts of straw are applied in the partly slatted pen designed 
with a concrete floor and one slatted area (solid/slatted: 2 : 1). Straw is given in straw racks that 
are filled manually, and from which the pigs take the straw in themselves. The solid floor has a 
slight incline (a slope of 5–7 %) to the dunging area, slurry and straw are moved towards the 
slats by the pigs’ activity; therefore, this system is also called a straw flow system.  

A partly slatted design is applied in Italy with a solid concrete floor and an external slatted alley 
adjacent  to  a  manure  channel  (see  Figure 2.21).  In  each  pen,  the  pigs  have  their  housing  and 

Intensive Rearing of Poultry or Pigs 

85 

 
 
 
 
 
 
 
 
 
Chapter 2 

feeding area inside the building, but an opening with a shutter allows them to reach the external 
defecating area with the slatted floor. The pig activity moves the manure through the slats into 
the manure channel, which is emptied once or twice a day with a scraper. The manure channel 
runs parallel to the pig building and is connected with a slurry storage facility. This system is 
also used for mating and gestating sows in group housing. 

Source: [ 391, Italy 1999 ] 

Figure 2.21:  Solid concrete floor with slatted external alley and scraper underneath 

Partly  slatted  flooring,  if  correctly  designed  and  well-drained,  can  reduce  emissions  of 
ammonia. The ventilation system has to function consistently in order to deliver the appropriate 
in-house  environment  for  the  pigs  with  the  purpose  of  maintaining  the  desired  lying  and 
defecating  areas  at  all  times.  If  the  ventilation  system  fails  to  provide  the  appropriate  indoor 
conditions, dunging and urination may take place on the solid floor area causing it to  become 
fouled and increase emissions. 

2.3.1.4.3 

Housing of fattening pigs on a solid concrete floor and straw 

In  the  housing  systems  for  fattening  pigs  with  a  solid  concrete  floor,  a  bedding  (> 10–15  cm 
bedding) with materials such as straw, sawdust, wood chips  or a big-bale supply is applied to 
improve animal welfare. The use of a bedding system demands good facilities for removing the 
bedding and cleaning/disinfecting in a strict batch system. Provision of straw, especially straw 
of poor quality, and the use of wood chips and sawdust, will increase the production of airborne 
particles  such  as  dust,  moulds  and  fungi  associated  with  respiratory  disturbances  in  pigs  and 
humans [ 495, EFSA 2007 ].  

These systems are applied in closed buildings or in open-front houses. The open-front designs 
are  equipped  with  wind  barriers  (netting  or  spaceboards),  but  straw  bales  are  also  used  for 
insulation and for protection against the wind. 

Pen designs can vary, but usually there is a lying area with straw and a feeding area, which may 
be elevated and accessible by steps (see Figure 2.22). The lying area may be covered. The pens 
may  be  positioned  on  one side  of  the  building  or  on  either  side  of  a  central  aisle.  Defecation 
takes  place  in  the  littered  area.  Mucking  out  and  cleaning  are  usually  done  with  a  tractor-
mounted front-end loader after each batch. Group size may range from 35–40 up to 250 pigs. 
The area provided per grower is usually 0.5 m2 and per finishing pig is 1.0–1.2 m2. 

86 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 202, EAAP 1998 ] 

Figure 2.22:  An example of a solid concrete floor system for fattening pigs 

In Italy, the bedded area is a littered external alley, which is similar to the design with slatted 
floor in the external alley (see Figure 2.23). The indoor pen area is used for lying and feeding 
and  has  very  little  or  no  straw.  The  outside  defecation  area  is  littered  and  connected  with  a 
manure channel. Manure and straw are moved into the channel by the pigs’ activity. Manure is 
removed once or twice daily by a drag chain or a scraper to outside manure storage. 

Source: [ 391, Italy 1999 ] 

Figure 2.23:  Solid concrete floor with external littered alley and manure channel 

Intensive Rearing of Poultry or Pigs 

87 

 
 
 
 
 
 
 
 
Chapter 2 

The  technique  may  take  place  with  a  wide  variation  of  pen  designs  and  manure  management 
systems. Examples of litter management, as reported by France, are detailed in Table 2.8. 

Table 2.8:  Manure and bedding management in litter-based systems for fattening pigs in France 

(from 30 kg to 115 kg live weight) 

Litter 
management 

Deep litter 
(straw) 

Littered floor  

Deep litter 
(deep sawdust 
bedding) 

Building features and 
management of bedding and 
manure 
-  Raised  bedded  area  and  feeding 

platform 

-  Straw provision at cycle start-up  
-  Fresh  straw  addition  over  the 
to  3 

accumulated  manure:  2 
times per week  

-  Manure removal at end of cycle 
-  Straw in lying area, scraper in the 
corridor and feeding platform  
-  Removal  of  manure  and  fresh 
straw  addition:  2  to  3  times  per 
week 

-  Raised  bedded  area  and  feeding 

platform 

-  Bedding  of  60–70  cm  used  for 

few batches 
the 

-  Only 

is 
surface 
removed at the end of each cycle. 
Bedding used for several cycles 
-  Bedding  of  20  cm  at  cycle  start-

layer 

Surface 
(m2/pig) 

Bedding use 
(kg/pig/cycle) 

Manure 
generation 
(kg/pig/cycle) 

1.3  

70 (50–80)  

200–300 

1.0  

45 (30–50) 

NI 

1.2  

50–60 

NI 

Deep litter 
(thin sawdust 
bedding)  

up  

-  No  sawdust  added  during  the 

1.3  

cycle 

-  Manure removal at end of cycle  

NB: NI = no information provided; DM = dry matter. 

Source: [ 420, Ramonet 2003 ] [ 262, France 2010 ] 

20–40  
(90 % DM) 

100–200  
(30–40 % DM) 

Littered  systems  in  the  UK  use  30–60 kg  of  straw/pig/cycle  while  deep  litter  systems  use  
50–120 kg of straw/pig/cycle [ 624, IRPP TWG 2013 ]. From Belgium-Wallonia a requirement 
of 80 kg of sawdust/pig/cycle is reported for systems applying a deep sawdust bedding, and an 
associated average manure generation of 123 kg/pig/cycle [ 567, Nicks B. 2004 ]. 

2.3.2 

Control of indoor environment in pig housing systems 

The indoor environment of the pig housing systems has to be adequately controlled to ensure: 

(a) 

the evacuation of harmful gases (CO2, CH4, NH3), whilst providing oxygen necessary for 
the breathing of the animals;  

(b)  maintenance of adequate humidity and temperature adapted to the physiological stage of 
the animal rearing, to ensure a good performance, in good health and without behavioural 
disorders. 

The  indoor  climate  in  pig  housing  systems  is  important,  as  ammonia,  combined  with  dust,  is 
known to be a frequent cause of pig respiratory diseases, including atrophic rhinitis and enzootic 
pneumonia. Since workers can also be subject to respiratory health issues it is doubly important 
that pig housing is sufficiently ventilated. 

88 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Minimum  (qualitative)  requirements  are  laid  down  in  Directive  2008/120/EC,  including  the 
control  of  the  pig  housing  climate  [  158,  EC  2008  ].  Temperature  and  humidity  of  air,  dust 
levels,  air  circulation  and  gas  concentrations  must  be  below  harmful  levels.  For  example,  the 
limit value concentrations shown in Table 2.9 are advised, but these values vary between MS. A 
good  indoor  environment  can  be  achieved  by  insulation  of  the  buildings,  heating,  ventilation, 
and pen layout and construction. 

Chapter 2 

Table 2.9:  General indicative levels of indoor environment for pigs 

Indoor environment factor 

Level/occurrence 

CO 
H2S 

Relative humidity  

NH3 

Air velocity 

CO2 

Source: [ 44, IKC 1993 ] 

Below measurable value 
Below measurable value 
60–80 % 
Pigs up to 25 kg:  
Pigs 25 kg upwards:  50–60 % 
Maximum 10 ppm 
Farrowing pens and weaners: 
Mating and gestating sows: 
Maximum 0.20 vol-% 

< 0.15 m/s 
< 0.20 m/s 

The performance of the applied system is affected by: 

 

 

 

 

design and construction of the building; 

position of the building in relation to wind directions and surrounding objects; 

application of control systems;  

number, age and production stage of the pigs in the housing. 

Insulation  can  be  applied  to  reduce  heat  losses  through  walls,  the  ground  and  the  roof  by 
interposition of layers of materials that slow down the transfer of heat in and out of the building. 
Different degrees of insulation are achieved by various materials. Two coefficients are generally 
used to  define this insulation: the  coefficient of  thermal  conductivity  (λ) and the  heat  transfer 
coefficient (U), which is the coefficient most commonly used and is expressed in W/m2 per °C  
[ 345, France 2010 ]. 

In  the  case  of  forced  ventilated  buildings  under  negative  pressure,  the  building  must  be  as 
airtight as possible. It is important to regularly verify the air sealing of doors and windows, and 
that  neither  water  condensation  on  walls  nor  undesired  air  draughts  occur.  In  the  case  of 
undesirable  airflow,  openings  are  usually  sealed  by  polyurethane  foam  spraying.  Height, 
positioning  and  number  of  pens  across  the  room,  as  well  as  properly  designed  pen  divisions 
(solid  or  open  to  allow  air  movement)  to  match  the  ventilation  system,  are  all  important 
considerations  for  designers  and  operators  if  the  optimum  living  environment  and  the  lowest 
emissions possible by the housing system are to be delivered. 

Treatments may be applied to incoming air (mainly for animal welfare reasons), primarily dust 
removal, cooling and/or humidification [ 264, Loyon et al. 2010 ]. 

The combination of heating and ventilation constitutes the crucial factor in indoor environment 
management.  Each  of  the  two  factors  has  an  antagonistic  action  on  the  other,  hence  the  best 
compromise has to be determined. 

Intensive Rearing of Poultry or Pigs 

89 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.3.2.1 

Heating of pig housing 

The  need  for  temperature  control  in  pig  housing  depends  on  the  climatic  conditions, 
construction  of  the  building  and  the  stage  of  production  of  the  animals  (see  Table 2.10).  In 
general, in colder climates or climates with periods of low temperatures, buildings are insulated 
and  equipped  with  mechanical  ventilation.  In  warmer  regions  (Mediterranean  latitudes),  high 
temperatures  have  a  greater  influence  on  the  welfare  and  productivity  of  adult  pigs  than  low 
temperatures.  Usually  there  is  no  need  to  install  heating  systems;  the  animal  body  heat  is 
generally  sufficient  to  maintain  welfare  temperatures  within  farms.  In  this  context,  climate 
control systems are mainly designed to guarantee good air circulation. 

In some housing systems for sows and fattening pigs (growers/finishers), large amounts of straw 
help  the  animals  to  maintain  a  comfortable temperature.  However,  the  most  important  factors 
are  live  weight,  age  and  production  stage.  Other  factors  that  affect  temperature  requirements 
are: 

 

 

 

individual or group housing; 

flooring system (fully or partly slatted or solid floors) and use of bedding; 

amount of feed (energy) the animals consume; 

Table 2.10:  Example  of  temperature  requirements  in  heated  housing  for  different  pig  categories 

in healthy conditions 

Farrowing pen 

Weaned pigs 

Mating and gestating sows 

Fattening pigs 

and 

Room 
sow 
location:  up  to  20–
22 °C 

Piglet  area:  first  days 
after birth, 28–30 °C 

7 kg, up to 25 °C  Mating, up to 20 °C 

10 kg, up to 24 °C  Early gestation, up to 20 °C 

20 kg,  up to  
20–22 °C 
30 kg, up to 18 °C 

15 kg, up to 22 °C  Middle gestation, up to 18 °C  40 kg, up to 16 °C 

20 kg, up to 20 °C  End of gestation, up to 16 °C 

50 kg, up to 15 °C 

Source: [ 44, IKC 1993 ] [ 261, France 2010 ] 

25 kg, up to 18 °C 

Pig  housing  can  be  heated  by  various  systems.  Heating  is  applied  as  zone  heating  or  room 
heating. Zone heating has the advantage that it is aimed at the place where it is most needed. 
Systems applied are: 

 

 

floors equipped with heating elements;  

heating elements above the pig places radiating heat onto the animals, as well as onto the 
floor surface. 

Room heating is applied by two methods: 

 

 

90 

by preheating: incoming air is preheated by leading the air through a central corridor to 
warm it to a minimum temperature, to reduce temperature fluctuations and to improve air 
movement in the housing area; 

by  post-heating:  heating  is  applied  to  the  air  once  it  has  entered  the  housing  area,  to 
reduce temperature fluctuations and to reduce heating costs. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Heating can be direct or indirect. Direct heating is accomplished by applying installations such 
as: 

Chapter 2 

 

 

 

 

 

 

 

 

gas heat radiators: infrared, gas air heaters and gas-fuelled radiation convectors; 

electric heat radiators: special light bulbs or ceramic radiators; 

electric floor heating: on matting or under the floor; 

floor  heating  with  warm  water  (water  is  heated  by  boilers  of  various  types  or  by  the 
techniques reported below); 

combined heat and power (CHP) systems; 

heat pumps; 

heat exchangers; 

heaters/blowers. 

Indirect heating can be compared to central heating in domestic applications. The installations 
applied can be: 

 

 

 

standard boilers (efficiency: 50–65 %);  

improved efficiency boilers (improved efficiency: 75 %); 

high efficiency boilers (high efficiency: 90 %). 

Boilers  can  be  open  or  closed  design.  Open  designs  use  indoor  air  for  the  burning  process. 
Closed designs draw air from outside the building and are particularly suitable for dusty areas. 

Extra local heating is applied to the piglets during their first weeks. Often, a heating lamp (gas 
or electric) is installed above the solid (non-slatted) lying area. The lying surface itself can also 
be  heated,  by  running  hot  water  through  tubes  or  a  reservoir  underneath  the  floor  surface. 
Weaners still have temperature requirements that require control of temperature and ventilation. 
Heating may be required during cold weather. The following heating systems are used: radiating 
heat lamps, electric heating (thermal bedding with a resistance wire heating) and also hot water 
heating systems (under the floor or through air ducts). 

Heating the housing of fattening pigs is not common, as their body heat is usually sufficient to 
create  a  comfortable environment.  In  pens  with  growers,  removable  covers  are  sometimes 
applied to create a more comfortable lying area in the early weeks. 

2.3.2.2 

Ventilation of pig housing 

Animal houses have to be ventilated in order to [ 474, VDI 2011 ]: 

 

 

 

 

supply the animals with fresh air; 

dissipate excess heat in order to keep the temperature within the optimal animal-specific 
range, which depends on age and performance; 

remove gaseous substances and dust; 

avoid damage to buildings due to humidity. 

Intensive Rearing of Poultry or Pigs 

91 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Ventilation  systems  vary  from  manually  controlled  naturally  ventilated  systems  to  fully 
automated  mechanically  ventilated  systems.  Two  main  building  and  ventilation  types  are 
distinguished for animal housing facilities: 

 

Forced  (or  mechanical)  ventilated  housing  systems  in  closed,  generally  thermally 
insulated buildings: 

o  exhaust ventilation: mechanical ventilation under negative pressure;  

o  pressure ventilation: mechanical ventilation in overpressure;  

o  neutral ventilation: mechanical ventilation under equal pressure. 

 

Natural (or free) ventilated housing systems: 

o  manual controlled ventilation; 

o  automatically controlled natural ventilation (ACNV). 

In  animal  houses  with  forced  ventilation,  fans  are responsible for  the  exchange of  indoor and 
outdoor air. The distribution of air can be accurately adjusted by means of valves, positioning of 
the  fan(s)  and  the  diameter  of  the  air  inlets.  In  contrast,  natural  ventilation  depends  on  the 
natural fluctuations of the outside air temperature and on the wind flow (pressure differences) 
and is attained by openings in the roof and/or sides of the building.  

A  defined  air  volume  flow  can  only  be  reached  in  animal  houses  with  forced  ventilation.  In 
addition,  a  more  even  airflow  in  the  housing  can  be  achieved.  This  is  important  when 
considering  the  application  with  housing  systems,  as  the  interaction  between  the  housing 
(flooring) system and the ventilation system affects the air currents and temperature gradients in 
the  house.  For  example,  partly  slatted  floors  may  combine  better  with  mechanical  ventilation 
than  with  natural  ventilation,  whereas  with  fully  slatted  floors,  natural  ventilation  may  be 
equally applied.  

The  volume  of  the  housing  area  and  the  air  inlet  and  outlet  openings  have  to  correspond  to 
create  the  required  ventilation  rate  at  all  times.  Irrespective  of  the  production  stage  and  the 
ventilation system, a draught close to the animals must be avoided. In new farms it is common 
to  apply 
requirements  
integrated 
[ 397, Denmark 2000 ]. 

that  match  heating  and  ventilation 

installations 

Operators  can  monitor  by  computer  the  ventilation  parameters  and  remotely  apply  correction 
measures for precision control. Control parameters may include temperature, relative humidity 
and  carbon  dioxide  concentration  which  are  monitored  by  appropriate  sensors.  Electronic 
equipment is applied to measure the fan revolutions per minute. A measuring fan in a ventilation 
tube can be used to measure the air velocity in the tube, which is related to a certain pressure 
and revolution rate.  

The  ventilation  techniques  that  are  mostly  applied  in  pig  housing  are  described  below  
[ 44, IKC 1993 ] [ 26, Finland 2001 ]. 

In  buildings  with  an  exhaust  ventilation  system,  fans are  used in the  side  walls or  in  the  roof 
(see Figure 2.24). Adjustable ventilation openings or vents allow fresh air to be drawn in. Fans 
expel air outside, usually through the ceiling at one or more points. This creates under-pressure, 
and creates fresh airflows into the building through the inlets. The fresh air inlets are usually on 
the wall, close to the ceiling, on the ceiling or on the floor. It is typical in an exhaust ventilation 
system for the air pressure inside the building to be lower than that outside. Exhaust ventilation 
works well when it is warm outside, and it is therefore a very popular and appropriate system in 
countries  with  warmer  climates.  On  fattening  pig  farms,  heating  costs  may  be  relatively  low 
when exhaust ventilation is used, provided that it is properly adjusted. 

92 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 26, Finland 2001 ] 

Figure 2.24:  Schematic view of airflow in an exhaust ventilation system 

In  buildings  with  a  pressure  ventilation  system,  fans  are  used  to  blow  air  into  the  building, 
which  means  that  the  air  pressure  inside  the  building  is  higher  than  outside.  Due  to  the 
difference in the pressure, air flows out of the building through outlets (see Figure 2.25). 

Source:[ 26, Finland 2001 ] 

Figure 2.25:  Schematic view of airflow in a pressure ventilation system 

When using pressure ventilation, the air entering the building can be preheated, and thus part of 
the heating in the winter can be done by means of ventilation. The main problem in this system 
is that the airflow is quite uneven when only one blowing point is used. Airflow is rapid and the 
air is cold close to the fan, but the airflow slows down rapidly when moving further away from 
the  fan.  Blowing  channels  may  be  used  to  avoid  this  problem.  Blowing  channels  are  usually 
placed in the middle of the pig house. In particular, air is blown into a channel, which spreads it 
throughout  the  building.  The  airflow,  distribution  and  direction  of  the  blow  are  controlled  by 
means of nozzles. Sometimes humidity is a problem, which, due to the higher pressure inside 

Intensive Rearing of Poultry or Pigs 

93 

 
 
 
 
 
 
 
 
 
Chapter 2 

compared to outside, leads to condensation on the surfaces of the channels when the air is not 
preheated.  This  is  why  pressure  ventilation  is  not  very  common  in  colder  climates.  It  is  only 
used  in  concrete  buildings,  as  the  humidity  can  damage  insulating  materials  and  structural 
timbers. 

A  neutral  ventilation system  is  a  combination  of  the exhaust  and  pressure  ventilation systems 
(Figure 2.26). As with exhaust ventilation, the exhaust air is drawn out of the building by means 
of  a  fan.  However,  the  replacement  air  does  not  flow  into  the  building,  because  of  negative 
pressure in the building, but air is drawn in through a channel. Thus, the difference between the 
air  pressure  inside  and  outside  the  building  is  much  smaller  than  in  the  case  of  exhaust  or 
pressure ventilation. In neutral ventilation, a heat exchanger can be used to reduce the need for 
additional  heating.  Neutral  ventilation  uses  more  energy  than  exhaust  or  pressure  ventilation, 
because the air is drawn in and blown out. Investment costs are also higher, as twice as many 
blowers and blowing channels are needed as for the other systems. 

Source:[ 26, Finland 2001 ] 

Figure 2.26:  Schematic view of airflow in a neutral ventilation system 

Natural  ventilation  systems  are  based  on  the  difference  in  density  and  air  pressure  between 
warm air and cold air due to wind, temperature and the so-called stack (or chimney) effect that 
causes warm air to rise and cold air to replace it. The stack effect depends on the relationship 
between  the  opening  and  the  position  of  air  inlets  and  outlets  and  the  inclination  of  the  roof 
(25 °; 0.46 m per metre stall width). Obviously, the design and construction of the building are 
very important with natural ventilation. As the effect is based on temperature differences, it is 
clear  that  the  effect  is  largest  when  the  ventilation  requirement  is  at  its  lowest  (in  winter).  In 
contrast to forced ventilation, no defined air volume flow can be set. 

The  naturally  created  negative  pressure  is  relatively  small;  even  in  winter  in  Finland  it  is 
reported as less than 20 Pa, and so, in summer, exhaust pressure ventilation is sometimes used 
to boost the airflow. Thus, combinations of ventilation systems are applied that work alternately, 
depending  on  the  indoor  and  outdoor  air  temperatures.  In  countries  such  as  the  Netherlands, 
wind is the prevailing factor that influences natural ventilation. 

In automatically controlled natural ventilation (ACNV), the increase or reduction of the airflow 
is  achieved  through  openings  or  vents  in  the  sides  or  roof  that  are  opened  and  closed  by 
electrically driven motors in response to sensors in the building.  

94 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

Ventilation of the building should be designed in such a way that air follows a predefined route. 
Underfloor extraction from pits beneath the pens is a way to achieve air stratification within pig 
housing.  Ventilation  by  drawing  air  from  the  manure  pit  in  slatted  floor  systems  is  also 
considered  an  efficient  way  to  reduce  concentrations  of  manure  gases  in  the  house.  By 
abstracting  air  from  this  head  space,  the  flow  of  air  through  the  slats  will  be  predominantly 
downwards.  This  will  reduce  releases  into  the  above-ground  environment.  Airflows  could  be 
locally increased during periods of disturbance, such as when slurry is being scraped or flushed. 
Stratified  air  management  has  the  potential  to  reduce  airflow  requirements,  thereby  cutting 
heating and cooling needs and reducing the cost of abatement with air cleaning systems. This 
system has specific requirements in terms of the length and diameters of the air channels. 

Irrespective of design or the principle applied, ventilation systems have to provide the required 
ventilation  rate  over  the  course  of  the  year,  which  depends  on the  different  production  stages 
and  the  time  of  year.  Air  velocity  around  the  animals  must  be  kept  below  0.15–0.20  m/s,  to 
avoid draughts. 

With forced ventilation, the air volume flow depends on the climatic conditions and is usually 
controlled depending on the temperature. The ventilation rate, which is dependent on the season 
and the time of the day, varies significantly. In summer, for example, it can reach ten times and 
in  some  cases  even  twenty  times  the  amount  of  the  minimum  airflow  rate  in  the  winter  
[ 474, VDI 2011 ]. The minimum (winter) ventilation rate is the flow necessary to evacuate the 
moisture  produced  in  cold  weather  by  the  youngest  animals  for  the  physiological  stage 
considered  and/or  carbon  dioxide  and  possibly  ammonia.  The  maximum  capacity  is  the  flow 
applied  in  hot  weather  to  the  heaviest  animals  for  the  stage  considered,  to  counteract  the 
temperature rise inside the building.  

The  optimum  airflow  significantly  contributes  to  the  control  of  the  indoor  concentrations  of 
ammonia, dust and germs. An increase in concentration of CO2, NH3, dust and germs can affect 
the pig feed intake by approximately 160 g/d, as a consequence decreasing the daily weight gain 
by 75 g [ 261, France 2010 ]. 

The recommended temperatures and ventilation rates in France  for heated and non-heated pig 
slurry-based houses are summarised in Table 2.11. Reference values from the Netherlands are 
reported in Table 2.12. 

Table 2.11:  Ventilation rates and indoor temperatures for pig housing, in France 

Animal category 

Mating/gestating sows (winter) 
Mating/gestating sows (summer) 
Farrowing sows (start of cycle)  
Farrowing sows (end of cycle) 

Weaners (start of cycle) 

Ventilation rate 
(m3/h per animal place) 

25–150 

35–250 

3–30 

Weaners (end of cycle) 
Fattening pigs (winter) 
Fattening pigs (summer) 
(1) For the piglet area, the temperature recommendation is 28–30 °C.  
Source: [ 261, France 2010 ] [ 345, France 2010 ]  

8–65 

Temperature 
(°C) 
20 
22 
24 (1) 
22 
27 (weaning at 28 days) 
28 (weaning at 27 days) 
24 
22 
24–25 

Intensive Rearing of Poultry or Pigs 

95 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Table 2.12:  Ventilation rates and indoor temperatures for pig housing, in the Netherlands  

Animal category 

Mating sows  
Gestating sows  
Gestating sows 1 week before birth 
Farrowing sows during birth 
Farrowing sows 1 week after latest birth 
Farrowing sows end  
Weaners start (7.5 kg) 
Weaners day 21  
Weaners day 42  
Fattening pigs day 1 (23 kg) 
Fattening pigs day 5 
Fattening pigs day 50  
Fattening pigs day 100  
Source: [ 421, Netherlands 2011 ] 

Minimum 
ventilation m3/h 
per animal place 
14–20 
18–25 
18–25 
18–25 
35–50 
35–50 
2–3 
4–6 
6–9 
6–8 
6–8 
11–15 
14–20 

Maximum 
ventilation m3/h 
per animal place 
120–150 
120–150 
160–200 
160–200 
200–250 
200–250 
10–12 
15–18 
20–30 
20–30 
20–30 
40–55 
60–80 

Temp 
(°C) 

22 
20 
20 
23 
20 
20 
26 
24 
22 
25 
23 
22 
21 

Design values in Germany and Austria are shown in Table 2.13 for different pig categories.  

Table 2.13:  Ventilation  rates  for  thermally  insulated  pig  houses  according  to  DIN  18910-1,  in 

Germany and Austria 

kg 
Live weight 
m3/h per animal 
Minimum ventilation rate (winter) 
Maximum ventilation rate (summer)  m3/h per animal 

Weaners and fattening pigs (1) 
10 
3.7 
23 

5 
2.5 
12 
Gestating sows (2) 

20 
5.4 
40 

30 
6.9 
53 

50 
9.4 
74 

100 
120 
14.1  15.6 
119 
108 

Live weight 
Minimum ventilation rate (winter) 
Maximum ventilation rate summer) 

kg 
m3/h per animal 
m3/h per animal 

150 
12.4 
83 

200 
15.1 
106 

250 
17.8 
128 

300 
20.3 
149 

Farrowing sows (3) 

150 
Live weight 
21.7 
Minimum ventilation rate (winter) 
Maximum ventilation rate (summer) 
139 
(1) Values calculated for 1.2 m2 per animal and temperatures from 28 °C to 18 °C. 
(2) Values calculated for 2.0 m2 per animal and temperature 18 °C. 
(3) Values calculated for 5.0 m2 per animal and temperature 18 °C. 
NB: Calculated values are based on an overpressure of 1 000 mbar and a house with a surface area of 14 m × 40 m. 
Source: [ 275, DIN 2004 ] [ 251, KTBL 2009 ] 

kg 
m3/h per animal 
m3/h per animal 

300 
29.6 
209 

250 
27.1 
187 

200 
24.5 
164 

Mating  and  gestating  sows  have  relatively  low  temperature  requirements.  In  Spain  and  Italy, 
many  farms  apply  only  natural  ventilation,  with  air  entering  from  outside  directly  into  the 
animal  housing  area.  Nevertheless,  in  large  farms,  with  a  high  density  of  animals,  ventilation 
requirements are met by means of fan ventilation. 

Extractor fans are commonly used, but, in Spain for example, there is a trend towards pressure 
ventilation systems linked to evaporative cooling, as these enable not only ventilation but also 
air  temperature  reductions  inside  the  building.  Throughout  Europe,  in  farrowing  and  weaning 
houses  it  is  common  to  control  the  indoor  climate  by  operating  automatic  (sensor-controlled) 
ventilation  systems  with  the  heating  of  the  air.  The  air  inlet  is  usually  via  a  central  corridor 
(indirect)  and the  design  of  the  ventilation  system  in  the  units  is  such that  a  draught  near the 
animals is avoided. 

96 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
The houses for fattening pigs that are naturally ventilated count on an air inlet directly into the 
pen  area,  whilst  extractor  fans  are  also  used  in  new  constructed  buildings.  Mechanical 
ventilation is also widely applied (e.g. for most fattening pig houses in Belgium-Flanders). 

Chapter 2 

2.3.2.3 

Lighting of pig housing 

Lighting requirements for pigs are laid down in Directive 2008/120/EC, stating that pigs must 
be  kept  in light  with  an intensity  of  at  least  40  lux  for  a  minimum  period  of  8  hours  per  day 
[ 158, EC 2008 ]. Light must be available for good control of the animals and must not have a 
negative  influence  on  pig  production.  Light  can  be  artificial  or  natural  entering  through  the 
windows; at the latter additional artificial lighting is normally applied. 

Additional  requirements  are  stipulated  in  some  Member  States.  Finland,  Austria,  Belgium, 
Sweden and Germany require that pigs have access to daylight through the walls or roof (3 % of 
the floor space in  Belgium and Germany; in Austria if there is no outdoor access) or through 
windows (all buildings must have windows for natural light in Sweden). Germany requires that 
pigs are housed under 80 lux for at least 8 hours per day [ 201, Mul M. et al 2010 ]. 

Different lamps are used with different energy requirements. Fluorescent lights are up to seven 
times  more  efficient  than  filament  bulbs.  LED  lights  are  characterised  by  lower  energy 
consumption  and  heat  output,  by  smaller  sizes  than  traditional  bulbs,  by  the  possibility  of 
dimming  bulbs  without  effect  on  the  spectral  sensitivity,  and  by  the  minimal  flicker  [  422, 
Taylor N. 2010 ].  

Lighting  installations  should  conform  to  normalised  standards  for  safe  operation  and  must  be 
water-resistant. Lights are installed in such a way that sufficient radiation (light level) is assured 
to allow the required maintenance and control activities to be carried out. 

2.3.2.4 

Water fogging 

Some  farms,  located  in  zones  where  summer  temperatures  are  extremely  high,  use  mist 
evaporative  cooling  systems  to  reduce  the  housing  temperature,  as  heat  stress  affects  animal 
performance. Spraying fine particles of water is a technique that produces a cooling effect by 
evaporative cooling, and has a positive effect on dust control, as described in Section 2.2.4.3. 

2.3.3 

Pig feed and drink supply  

2.3.3.1 

Pig feed formulation 

The feeding of pigs is aimed at supplying the required amount of  net energy,  essential amino 
acids,  minerals,  trace  elements  and  vitamins  for  growth,  finishing  or  reproduction.  The 
composition  and  supply  of  pig  feed  is  a  key  factor  in  the  reduction  of  emissions  to  the 
environment from pig farming. 

Pig  feed  formulation  is  a  complex  matter,  combining  many  different  components  in  the  most 
economical  way.  Different  factors  influence  the  composition  of  a  feed.  Components  used  for 
feed  formulation  are  determined  by  the  location.  It  is  now  common  for  different  feeds  to  be 
applied,  enabling  formulation  closer  to  the  requirements  of  the  pig.  For  example,  two-phase 
feeding is applied for sows and three-phase for finishers.  

In  general,  multiphase  (adapted  N  and  P  content)  feeding  regimes  are  commonly  applied  for 
fattening  pigs,  as  well  as  the  use  of  feed  additives,  with  the  aim  of  reducing  the  amount  of 
manure.  Multiphase  or  programmed  feeding  regimes  are  also  widespread  for  weaners.  This 
section can only give a short overview of the essential elements that are combined in pig feed. 

Intensive Rearing of Poultry or Pigs 

97 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

An important feature of a feed (material or diet) is its energy content (expressed in MJ/kg) and 
in particular the amount of productive energy that is available to the pig, the net energy (NE). 
There are a number of systems operating within the EU, used to express the energy value of a 
pig  feed.  In  the  past,  these  were  mostly  based  upon  digestible  energy  (DE)  which  is  the 
difference between the gross energy of the feedstuff and the dietary energy losses in the faeces. 
However, the DE system undervalues the productive energy content of fats and overvalues that 
of  protein  and  fibre.  A  modified  version  of  the  DE  system  is  the  metabolisable  energy  (ME) 
which takes into account energy losses through faeces, urine and gases. The net energy (NE) is 
the energy actually available for productive purposes (maintenance of bodily functions, growth, 
milk  production  and  reproduction)  taking  into  account  all  energy  losses,  not  only  through 
faeces, urine and gases but also the biggest energy loss by the pig, the heat. Nowadays, NE has 
been  adopted  by  the  majority  of  Member  States;  nevertheless,  energy  systems  based  on 
approximate DE are still in use. 

There are two basic NE systems in operation in the EU, one produced by France and one by the 
Netherlands.  There  are  also  derivations  such  as  the  Danish  system  which  is  basically  an  NE 
system but uses Feed Units. In comparison with feeds formulated on a DE system, formulating 
feeds  on  an  NE  basis  typically  results  in  reduced  crude  protein  content  [  624,  IRPP  TWG 
2013 ]. 

The indispensable (or essential) amino acids are those that cannot be synthesised by the animal 
organism, or can only be in small quantities. They must, therefore, be supplied through the diet, 
which has to provide the indispensable amino acids in sufficient quantities to cover the animal’s 
requirements. The essential  amino  acids  for  pigs  are the same  as  for  poultry,  but  the  order  of 
deficiency is not the same. In pigs, lysine is the first limiting amino acid, followed in general by 
methionine (and cystine), threonine, tryptophan, valine, isoleucine, histidine and the others.  

In the formulation of feeds for pig nutrition, the ideal protein is a concept where the optimum 
indispensable  amino  acids  supply  is  described  in  terms  of  ratios  to  lysine  and  where  any 
deficiency  of  one  of  the  indispensable  amino  acids  will  compromise  growth  and/or  health.  In 
this profile, all indispensable amino acids are equally limiting for performance, just covering the 
requirements for all physiological functions.  

In practical nutrition, this offers the advantage that the lysine requirement will vary (per kg of 
feed  or  per  MJ  of  energy),  but  not  the  ideal  amino  acids  profile  expressed  relative  to  lysine. 
Each  of  these  ratios  can  thus  be  directly  introduced  as  a  constraint  in  feed  formulation.  For 
many  years  pig  feeds  have  been  formulated  using  digestible  amino  acids  (standardised  ideal 
digestible or SID) rather than total. 

The pigs’ requirements for minerals (major elements and trace elements) is a complex matter, 
even more so due to the interactions between them. Their doses in feeds are measured in g/kg 
(minerals)  or  mg/kg  (trace  elements).  The  most  important  are  Ca  and  (digestible)  P  for  bone 
tissue. Ca is also important for lactation and P is important for the energy system. Often their 
functionalities are related and so therefore attention must be given to their ratio. The minimum 
requirements vary for the different production stages or purposes. For early growth (including 
weaners) and lactation, more Ca and P are required than for growing and finishing. Mg, Na and 
Cl  are  usually  given  at  levels  sufficient  to  meet  the  requirements.  The  requirements  of  trace 
elements are defined as minimum and maximum levels, as the elements are toxic above certain 
concentrations. 

Important trace elements are Fe, Zn, Mn, Cu, Se and I. The requirements can usually be met, but 
Fe is given by injection to suckling piglets. Cu and Zn can be added to the feed ration of pigs in 
a  quantity  higher  than  the  actual  production  requirements,  in  order  to  make  use  of  the 
pharmacological  effects  and  the  positive  effects  on  production  performance  (auxinic  effect). 
However,  European (i.e.  Directive  85/520/EEC  and  Regulation  1334/2003)  and national  rules 
have been adopted, establishing maximum concentration levels in livestock feeds; for example 

98 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
in Italy, regarding additives in feeds, which place limits on the addition of copper and zinc, in 
order to reduce the quantity of these two metals in animal slurry.  

Vitamins  are  organic  substances that  are important  for  many  physiological  processes,  but  can 
usually not (or not sufficiently) be provided by the pig itself and therefore have to be added to 
the pig’s feed. There are two types of vitamins: 

Chapter 2 

 

 

fat-soluble vitamins: A, D, E, K; 

water-soluble vitamins: B, H (Biotin) and C. 

Vitamins A, D, E and K can be stored in the body and are supplied on a regular basis, but B-
vitamins, H and C are supplied daily, as the animal cannot store them (except B12). There are 
minimum  requirements  for  the  concentration  of  vitamins  in  pig  feed,  but  the  requirements  of 
pigs  are  affected  by  many  factors,  such  as  stress,  disease  and  genetic  variation.  To  meet  the 
varying  requirements,  feed  producers  apply  a  safety  margin,  which  means  that  usually  more 
vitamins are supplied than necessary. 

Other substances might be added to pig feed to improve: 

 

 

 

 

production levels (growth, FCR): zootechnical additives; 

quality of feed: e.g. vitamins and trace elements;  

technological characteristics of feed (taste, structure); 

the  environmental  impact  of  animal  production:  digestibility  enhancers,  gut  flora 
stabilisers and additives that favourably affect the environment. 

Organic acids and acid salts can be added for their effect on digestibility and to allow a better 
use of the feed energy. 

Plants  contain  some  compounds  that  either  the  animal  cannot  digest  or  which  hinder  its 
digestive  system,  often  because  the  animal  cannot  produce  the  necessary  enzyme  to  degrade 
them.  Enzymes  are  substances  that  enhance  the  chemical  reactions  of  the  pigs’  digestive 
processes, e.g. the addition of the enzyme phytase to the feed enhances phosphorus digestibility 
by  breaking  down  the  indigestible  phytic  acid  (phytate)  part  of  phosphorus  of  plant  origin  in 
feedstuffs. By improving digestibility, they increase the availability of nutrients and improve the 
efficiency of metabolic processes. The use of antibiotics as  a feed additive in animal feed for 
growth promotion is prohibited in the EU (Regulation No 1831/2003/EC). 

2.3.3.2 

Feeding systems 

The  choice  of  feeding  system  is  important  as  it  can  influence  daily  weight  gain,  FCR  and 
percentage feed loss [ 39, Germany 2001 ]. In reality, differences within systems may be greater 
than  between  systems  [  624,  IRPP  TWG  2013  ].  Pig  feeding  encompasses  a  number  of  feed 
types.  Dry  feed  is  formulated  as  pellets  or  meal  without  any  addition  of  water.  Wet  feed  (or 
liquid  feed)  is  formulated  as  a  mixture  of  feed,  water  and  other  ingredients  so  that  it  can  be 
pumped.  Most  feed  mixed  on  farm  is  dispensed  as  a  meal  whereas  that  supplied  by  larger 
commercial mills is more often supplied in the form of pellets or nuts.  

Pelleting  improves  digestibility,  reduces feed  wastage  and  dust,  and  may  improve  feed  intake 
while the feed conversion ratio is generally improved. Pelleting, as a thermal process, can also 
reduce  or  eliminate  potential  pathogens  such  as  salmonella  in  the  feed  ingredients.  However, 
meal is cheaper to produce and gut microbiology is generally better for pigs fed with meal, with 
less diarrhoea and a lower salmonella incidence. 

Intensive Rearing of Poultry or Pigs 

99 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

In areas with a high population there are high quantities of liquid by-products available for the 
preparation of liquid feeds. These include starch products, those from the brewing and distilling 
industries  (including  bioethanol)  and  milk  products.  They  are  mixed  on  farm  with  meal  and 
circulated  to  the  pigs  via  a  pipeline.  Such  by-products  are  cost-effective  although  their 
composition and supply can be variable. They are low in dry matter and, therefore, the transport 
distance is crucial. There has been an increase in by-product feeding in the EU although this is 
inevitably limited by the supply of co-products [ 624, IRPP TWG 2013 ]. 

The design of the feeding installation depends on the feed type. Liquid feeding is most common, 
but for example in Spain and Belgium dry feeding is applied in most of the farms, and mixtures 
are  also  applied.  Regimes  are  ad  libitum  or  restricted.  For  example  in  Italy  the  following 
variations apply [ 412, Italy 2001 ]:  

 

 

 

for  mating/gestating  sows:  80 %  of  farms  operate  liquid  feeding;  the  other  20 %,  dry 
feeding;  

farrowing sows and weaners are given dry feed; 

growing/finishing pigs are liquid-fed on 80 % of farms (of which 5 % are fed with wetted 
feed), with feed supplied as dry plus drinkers on 5 %, and dry-fed on 15 %. 

The feeding system consists of the following parts: feeding trough, storage facility, preparation 
system, transport system and dosage system. 

Feeding  can  vary  from  fully  hand-operated  to  fully  mechanised  and  automated  systems. 
Troughs of different designs are used and provisions are made to prevent pigs from lying in the 
trough.  Feed is  often  delivered  dry  or  mixed  with  water.  Different  dry  feeds are  purchased to 
allow a mixture close to the required nutrient content. Dry feed is usually transferred from the 
storage to the mixing machines by augers. 

Distribution  varies  with  the  type  of  feed.  Dry  feed  can  be  transported  by  a  feeding  cart  or 
mechanically  through  feed  distribution  tubes  in  the  same  way  as  liquid  feed.  Liquid  feed  is 
pressed through a plastic tube system, in which the pressure is built up by the pumping system. 
There  are  centrifugal  pumps,  which  can  pump  large  amounts  and  can  achieve  about  3  bar. 
Displacement  pumps  have  a  lower  capacity,  but  are  less  limited  by  pressure  build-up  in  the 
system. 

Liquid  (wet)  feeders  consist  of  a  mixing  container,  where  the  feed  is  mixed  with  water,  and 
tubes  to  distribute  it  to  the  animals.  The  rationing  of  the  mixture  can  be  done  automatically 
based on weighing the exact amounts or can be computer-controlled, mixing according to the 
feeding  plan  and  substituting  feed  when  necessary.  Liquid  feeding  can  also  be  operated 
manually by weighing and mixing the required amounts. In Austria, fattening pigs are fed with a 
‘soup’ of water and 30 % dry matter coming from maize, soy, mineral raw materials and a raw 
fibre carrier called ‘pig fibre’ [ 373, UBA Austria 2009 ]. 

Feed  can  be  delivered  to  animals  by  using  mechanical  drops  with  calibrated  boxes  (drop-
feeding) that are fed by auger. The system is used for group-housed animals and for individual 
housing  (crates).  Group-housed  sows  can  be  individually  fed  with  computerised  sow  feeders 
(see Section 2.3.1.1.4) that identify the animals by an electronic identifier (chip) clipped at the 
ear or neck. The amount and supply are adjusted to allow the sow to eat as much and as often as 
it needs, but constrained by operator-determined limits.  

Individual feeding stalls are frequently provided in pens for group housing. Animals are free to 
roam in pens and enter the feeding stations, where they are individually fed, in order to reduce 
aggression between animals at feeding time. Self-locking or manual locking individual feeding 
stalls  can  be  used  for  activities  such  as  vaccination,  oestrous  detection,  and  artificial 
insemination. 

100 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 2 

With trickle feeding systems, feed is delivered via a top auger to individual feeding points, in 
small  portions,  at  regular  intervals  over  the  feeding  period.  The  feed  is  delivered  at  a  speed 
adjusted  to  the  consumption  rate  of  the  animals  (typically  80–180  g/minute),  to  discourage 
changes of feeding position, with consequent differences of feed intake within the group. In the 
rearing of sows, aggressive behaviour caused by competition for feed can be reduced. 

Liquid feeding has the potential to reduce production costs and is an effective management tool 
for controlling the presence of salmonella in pigs at slaughter but has no significant effect on 
measures  to  reduce  the  environmental  impact  [  289,  MLC  2005  ]  [  290,  Univ.  of  Newcastle 
2002 ]. On the other hand, the capital cost of wet feeding is high compared to that of dry feeding 
and  the  variability  of  ingredients  in  liquid  feeding  could  make  it  difficult  to  guarantee  the 
ingestion of properly balanced feed.  

2.3.3.3 

Drinking water supply systems 

All pigs over 2 weeks of age must have permanent access to a sufficient quantity of fresh water 
in  compliance  with  Directive  2008/120/EC.  Natural  drinking  behaviour  also  has  to  be 
considered.  

Inadequate water intake can lead to reduced feed intake, poor daily  weight gain and poor feed 
conversion. Significant losses may occur due to a recreational use of water. In turn, waste water 
may significantly increase the volume of slurry produced [ 423, Gill P. 1989 ]. 

For the supply of drinking water, a great variety of drinker systems are available. The quality of 
the water should be appropriate for the animals being produced according to the provisions of 
Regulation  (EC)  183/2005.  Some  farms  have  a  main  reservoir  with  a  large  capacity  and 
possibilities  for  disinfecting  treatment;  inside  each  house  or  sector  there  may  be  smaller 
reservoirs  to  allow  water  distribution  along  with  medicines  and/or  vitamins.  One  or  more 
pressure  regulators  are  necessary  to  control  pressure  in  the  pipeline;  a  filter  can  be  placed 
upstream of the distribution line [ 413, Portugal 2001 ] [ 357, France 2010 ]. 

The proper functioning of the watering system mainly depends on: 

 

 

 

 

the drinker design; 

the flow per drinker; 

the number of animals per drinker; 

the position of drinkers, e.g. height from the ground [ 357, France 2010 ]. 

The following drinker designs are commonly used to distribute water to the animals: 

 

 

 

 

 

nipple drinkers in a cup or a trough;  

bite drinkers; 

push-tube drinkers; 

trough with bowl and pallet; 

water trough at a constant level. 

Animals  easily  learn  how  to  use  nipple  and  bite  drinkers  and  the  cleanliness  of  the  water 
provided  is  ensured;  notable  waste  water  can  occur  in  comparison  with  trough  drinkers.  By 
pressing a nipple with its nose, the pig can make water run into the trough or the cup. Minimum 
requirement  capacities  vary  from  0.75–1.0 litres  per  minute  for  piglets  and  typically  
2.0–3.0 litres per minute for sows. A bite nipple gives water when the pig sucks on it and opens 

Intensive Rearing of Poultry or Pigs 

101 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

a  valve.  The  water  will  not  run  into  a  trough  or  cup.  The  capacity  of  the  bite  nipple  is  
0.5–1.5 litres per minute. Push-tube drinkers generally equip wet feeders or can be placed above 
small troughs.  

Watering  the  animals  by  filling  the  trough  can  vary  between  a  simple  tap  to  a  computerised 
dosing system measuring exactly the required volume. Trough drinkers at a constant water level 
allow fast animal adaptation and result in less water wastage due to the water being retained in 
the trough. However, this retained water is susceptible to spoilage, which could decrease water 
intake,  therefore  they  are  not  widely  used.  Troughs  with  bowl  and  pallet  combine  low  water 
wastage  with  acceptable  water  cleanliness.  The  bowl  is  generally  made  of  cast  iron  with  the 
shape of a snout.  

The number of animals serviced in France by the different types of drinking systems is shown in 
Table 2.14. 

Table 2.14:  Number of animal serviced by each type of drinking equipment in France  

Pig category 

Drinking 
system 

Capacity 
(l/min)  

Height (cm) (1) 

Piglets 

Weaners 

Fattening pigs 

Sows  
(Group housing) 

Bowl 
Bite drinkers 
Bowl 
Bite drinkers 
Bowl 
Bite drinkers 
Bowl 
Bite drinkers 

0.5 
0.5 
0.5–1.0 
0.5–0.8 
0.8–1.0 
0.5–0.8 
3.0 
1.5 

8 
20 
12 
30 
20 
50 
30 
70 

Maximum number of 
animals per drinker 
system 
NR 
NR 
18 
10 
18 
10 
10 
5 

Sows  
(individual housing) 
(1) For bowls, height is calculated from the higher edge and for bite drinkers from the of the end of the bitter. 
NB: NR = not relevant. 

Bowl 

> 3.0 

5–10 

NR 

Source: [ 357, France 2010 ] 

102 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.4 

End-of-pipe techniques for air cleaning  

Air cleaning systems are end-of-pipe techniques used to remove pollutants from the exhaust air 
of animal housing. They are applied only in forced ventilated houses because the exhaust air has 
to  be  collected  and  led through  the  cleaning  system  by  fans.  Air  cleaning  systems  operate  on 
different  removal  principles  (physical,  biological  and/or  chemical).  Different  types  of  wet 
scrubbers and biofilters are applied, individually or in combinations; they differ in applicability 
and removal performance (see related data in Table 4.129). 

Modifications  to  the  feed  formulation  and  adaptation  of  the  housing  system  may  not  always 
allow compliance with increasingly stringent emission regulations and targets. This can be seen 
as a driving force for the development and use of air cleaning systems; even if these techniques 
do not improve the indoor climate of the animal houses.  

2.4.1 

Wet scrubbers 

A wet scrubber, or trickling filter, is an end-of-pipe technique for removing pollutants from the 
exhaust air of a forced ventilated animal house. The air is filtered through a bed of inert material 
that has a high porosity and a large specific area and is continuously kept wet (see Figure 2.27). 
The contaminated air is blown through the filter either horizontally (cross-current) or upwards 
(counter-current),  to  produce  intensive  contact  between  air  and  water,  enabling  the  soluble 
contents  to  be  exchanged  from  the  gas  to  a  liquid  phase.  Most  of  the  trickling  water  is 
continuously  recirculated,  while  a  fraction  is  discharged  and  replaced  by  fresh  water.  The 
discharge  is  automatically  managed  on  the  basis  of  the  water  conductivity  and  allows  for  the 
removal  of  nitrogen  compounds.  These  techniques  have  the  potential  to  achieve  a  combined 
removal of ammonia, odour and particulate matter.  

Source:[ 13, Melse 2009 ] 

Figure 2.27:  Schematic representation of a wet scrubber  

Two  types  of  wet  scrubbers  are  mainly  used:  'acid  scrubbers',  and  'biotrickling  filters' 
(bioscrubbers)  and  their  combinations,  e.g.  'multi-stage  air  cleaning  systems’,  where  two  or 
three stages that operate on different principles are run in series, e.g. an acid scrubber to remove 
ammonia and a biofilter to remove odour.  

Intensive Rearing of Poultry or Pigs 

103 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

In a bioscrubber or biotrickling filter, the exhaust air is conducted through a package of plastic 
material,  which  is  continuously  sprayed  with  water  containing  microorganisms  to  trap  and 
breakdown  ammonia  and  organic  compounds  responsible  for  odour;  dust  is  also  dissolved  in 
water.  During  the  passage  through  the  moistened  packing  material,  ammonia  is  removed  by 
bacterial conversion to nitrite and nitrate. The bacterial population mainly grows as a film on the 
synthetic packing material and is partly suspended in the recirculating water.  

An  acid  scrubber  uses  a  spray  of  acid  solution  (usually  sulphuric  acid)  to  trap  and  remove 
ammonia  from  the  contaminated  exhaust  air.  The  pH  of  the  circulating  liquid  is  kept  at  low 
levels  (i.e.  < 5)  and  the  ammonium  salt  that  is  formed  is  removed  from  the  system  with  the 
discharge water.  

In practice, scrubbers should be designed for treating the maximum exhaust airflow rate. Since 
maximum ventilation rates do not occur frequently, scrubbers can alternatively be dimensioned 
for  treating  lower  ventilation  rates,  so  that  the  part  of  the  exhaust  air  that  exceeds  the  air 
cleaning system capacity is allowed to be vented untreated through a bypass. In this way, the air 
cleaning system size and cost are significantly decreased (as cost is proportional to the volume 
of  air  to  be  treated),  ammonia  removal  efficiency  is  kept  high  and  emission  loads  are  only 
slightly  affected;  on  the  other  hand,  odour  nuisance  mitigation  will  be  nearly  completely 
compromised. However, the ammonia removal efficiency of the system also depends on  other 
parameters, including the thickness of the filter package.  

Manufacturers  deliver  either  prefabricated  modules  or  custom-made  installations.  Periodic 
maintenance  and  controls  are  necessary  in  order  to  maintain  the  abatement  efficiency.  The 
nitrogen  compounds  that  result  from  both  chemical  and  microbial  processes  can  be  used  as 
fertilisers.  

2.4.2 

Biofilters 

A commonly applied method of treating the exhaust air of forced ventilated animal housing is 
the use of biofilters. The exhaust air flows through a large packed filter bed of organic material, 
such as compost, root wood or wood chips. The filter material is always kept moist, so that high 
microbial activity occurs on the biologically active film that is formed on its surface. The wet 
microbial film traps and degrades the organic compounds responsible for odour that are blown 
through the filter. Dust emissions are also considerably reduced. Even though NH3 is degraded 
by microbial activity, the use of single-stage biofilters for ammonia removal in animal housing 
is  generally  not  recommended  due  to  the  risk  of  formation  of  secondary  trace  gases  and  fast 
filter  material  decomposition.  At  normally  applied  air  residence  times,  the  filter  material 
lifespan is shortened in the case of relatively high NH3 and dust concentrations of the incoming 
air and inconsistent humidification of the packing. In general, this technique can be effectively 
used in combination with other air cleaning techniques  as a polishing step for effective odour 
removal. 

104 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.5 

Processing and storage of animal feed 

Many on-farm activities involve the processing and storage of feed. Many farmers obtain feed 
from  animal  feed  compounders  that  can  be  readily  used  or  that  needs  only  very  limited 
processing.  Production  of  the  basic  feed  ingredients  is  a  specialised  activity;  however,  some 
large  enterprises  produce  the  majority  of  the  basic  ingredients  themselves  and  also  purchase 
premixtures of additives to manufacture their own compound feed; this may also be the case for 
some small and medium-sized enterprises.  

The  processing  of  feedstuff  consists  of  grinding  or  crushing  and  mixing.  The  mixed  feed  can 
either be fed as a dry or a liquid feed. Mixing the feedstuff to obtain a liquid feed is often done 
shortly  before  feeding  the  animals,  as  this  liquid  cannot  be  stored  for  a  long  period  of  time. 
Grinding and crushing are time-consuming and require a lot of energy. Other energy-consuming 
parts  of  the  installation  are  the  mixing  equipment  and  the  conveyor  belts  or  air-pressure 
generators used to transport the feed. 

Feed processing and feed storage facilities are usually located as close as possible to the animal 
housing.  Feed  produced  on  the  farm  is  usually  stored  in  silos  or  sheds  as  dry  cereals;  gas 
emissions are then limited to the emission of carbon dioxide from respiration. 

Industrial  feed  can  be  wet  or  dry.  If  dry,  it  is  often  pelleted  or  granulated  to  allow  for  easier 
handling.  After  mixing  the  feedstuff,  dry  feed  is  transported  in  tanker  lorries  and  unloaded 
straight into closed silos, therefore dust emissions are usually not a problem.  

Driveways and trucks are preferably kept in a zone separate from the animal houses, in order to 
avoid  trucks  entering  the  clean  zone  and,  therefore,  reducing  the  risk  of  contamination 
(biosecurity measure). 

There are many different designs of silos and materials used. They can be flat at the bottom, to 
stand  on  the  ground,  or  conical,  resting  on  a  supporting  construction.  Sizes  and  storage 
capacities  are  numerous.  Nowadays,  polyester,  glass  fibre  reinforced  plastic  (GRP)  or 
galvanised steel silos are the most frequently used, and the inside is made as smooth as possible 
to prevent residues from sticking to the wall. For liquid feed, materials (resins) are applied to 
resist low pH products or high temperatures. 

Silos  are  usually  a  single  construction,  but  there  are  also  designs  on  the  market  that  can  be 
transported in parts and assembled in the farmyard. Silos are usually equipped with a manhole 
for internal inspection and a device for air venting or for relieving overpressure during filling. 
Equipment is also applied for aeration and  the stirring of the contents (especially soya) and to 
allow the smooth transportation of the feed out of the silo. 

Intensive Rearing of Poultry or Pigs 

105 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.6  Collection and storage of manure 

2.6.1 

General requirements 

Manure  is  an  organic  material,  which  supplies  organic  matter  to  soil,  together  with  plant 
nutrients (in relatively small concentrations compared to the mineral fertilisers). It is collected 
from  animal  housing  and  stored  either  as  slurry  or  as  solid  manure.  Manure  from  intensive 
livestock is not necessarily stored on the farm where it is produced and particular care is taken 
because of the risk of spreading disease. 

Slurry consists of excreta produced by livestock in a yard or a building, mixed with rainwater 
and  cleaning  water  and,  in  some  cases,  with  bedding  in  relatively  small  quantities  and  feed. 
Slurry may be pumped or discharged by gravity. Pig manure is often handled as slurry. 

Solid  manure  includes  farmyard  manure  (FYM)  and  consists  of  material  from  litter-covered 
yards,  dried  poultry  manure  from  belt  removal  systems  in  hen  housing,  excreta  with  a  lot  of 
straw  in  it,  or  solids  from  a  mechanical  slurry  separator.  Solid  manure  does  not  flow  under 
gravity  and  cannot  be  pumped.  Some  types  of  solid  manure  cannot  be  stacked  in  a  heap  and 
liquids  may  drain  from  the  material.  Most  poultry  production  systems  produce  solid  manure, 
which can generally be stacked.  

Storage facilities are usually built with a minimum capacity to guarantee sufficient storage until 
further  manure  handling  is  possible  or  allowed  (see  Table 2.15),  due  to  regulations 
implementing the Nitrates Directive (91/676/EC). The required minimum storage capacity and 
prohibition  period  for  manure  landspreading  differ  between  Member  States;  the  prohibition 
period may also depend on the soil and crop type. The storage capacity depends on the climate, 
on the regulatory requirements, on the landspreading risks (manure management planning), on 
the  size  of  the  farm  (animal  numbers)  and  on  the  amount  of  manure  produced  taking  into 
account the amount of waste water produced, and is expressed in months rather than in m3. For 
slurry  storage  in  earth-banked  lagoons,  in  particular,  the  calculation  for  the  required  storage 
capacity has to allow for a minimum freeboard as a safety margin to limit pressure on the bank 
and to prevent overtopping by the action of wind on the slurry surface or abnormal precipitation 
(predominately rainfall), which in turn can erode the top and dry slope and lead to pollution. In 
general the quantity of precipitation must be considered in uncovered storage facilities. 

The storage time depends on the fertiliser requirements of the crops, the vegetation period, the 
soil moisture deficit and the storage capacity. The field crops and fertiliser requirements differ 
between farms and management options and may change every year. The storage time can range 
from some days to some months depending on the management system [ 574, UBA Germany 
2011 ] [ 624, IRPP TWG 2013 ].  

Across Europe, a storage capacity of 4 to 6 months is generally applied for solid manure. In the 
northern  regions  (Sweden,  Finland),  even  larger  storage  capacities  may  be  applied.  A  storage 
capacity of 6 months seems to be a common standard in Europe for slurries; although, shorter 
(e.g. Czech Republic, Spain, Portugal) and even longer storage times are also common (e.g. the 
Netherlands,  Denmark,  Germany,  Sweden,  Finland)  [  264,  Loyon  et  al.  2010].  A  large  slurry 
tank can easily contain 2 000 m3 or even up to 5 000 m3. 

106 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Table 2.15:  Storage times of poultry and pig manure in a number of Member States 

Chapter 2 

EU 
Member State 

Belgium (Flanders) 

Belgium (Wallonia) 
Luxembourg 
Denmark  
Finland 

France 

Germany 

Austria 
Greece 
Ireland 

Italy 

Portugal 
Spain 
Sweden 

Netherlands 

External manure storage capacity (1) 
(in months) 
3 (farmyard manure)  
9 (slurry) 
9 (poultry manure when birds are kept indoors all the time)  
6 (slurry) 
5 
6–9 
12 (except for deep litter) 
3–4  
6 (Brittany)  
2–4 (solid manure, according to good agricultural practice) 
6–10 (slurry, depending on soil and climatic conditions) 
6  
4 
6 
3 (solid manure) 
4–6 (slurry) 
3–4 
3 or more 
8–10 
7 (slurry) 
length of production cycle (poultry) 
 6  
4 or 6 (depending on the region) 

Climate 

Atlantic/Continental 

Atlantic/Continental 
Atlantic/Continental 
Atlantic 
Boreal 

Atlantic 

Continental 

Continental 
Mediterranean 
Atlantic 

Mediterranean 

Mediterranean 
Mediterranean 
Boreal 

Atlantic 

Atlantic 
Continental 

UK  
Slovenia 
(1) Deep litter of poultry systems is considered storage space. 
Source: [ 537, COM 1999 ] [ 500, IRPP TWG 2011 ] [ 574, UBA Germany 2011 ] 

Table 2.16  reports  examples  of  national  regulations  implementing  the  Nitrates  Directive 
(91/676/EEC), which bans manure application during certain periods of the year. 

Intensive Rearing of Poultry or Pigs 

107 

 
 
 
 
 
 
 
Chapter 2 

Table 2.16:  Examples  of  national  regulations  (2013)  prohibiting  manure  application  during 

certain periods of the year 

EU 
Member State 

Germany 

Austria 

Netherlands 

Ireland 

France 

UK 

Denmark 

Italy 

Finland 

Belgium (Wallonia) 

Belgium (Flanders) 

Regulation for manure application 

Ban on slurry application between 01.11 and 31.01 on tillage land, and between 
15.11 and 31.01 on grassland 
Ban on slurry application between 15.10 and 15.02 on soils without vegetation, 
and between 15.11 and 15.02 on soils with vegetation 
Ban on slurry application between 01.09 and 31.01 on sandy and loose soils, and 
between 15.10 and 31.01 on clay and peat soils under grass 
Ban on slurry application between 15.10 and 12.01 till 31.01, depending on the 
region 
Ban  on  slurry  application  between  01.11  or  15.11  to  15.01,  depending  on  the 
type of cultivation 
Ban  on  slurry  application  between  01.09  and  31.12  for  sand  and  shallow  soils 
under  grass,  and  between  01.08  and  31.12  for  sand  and  shallow  soils  under 
tillage; in other soils, between 15.10 and 31.01 under grass, and between 01.10 
and 31.01 under tillage 
It is not allowed to spread slurry between 15.10 and 01.02 
Ban on manure application depending on whether it is slurry or solid manure, the 
type  of  crops  (arable  or  permanent  grassland)  and  the  region.  The  ban  periods 
generally  start  between  the  months  of  November/December  and  end  in 
January/February. 
Manure must not be applied between 15.10 and 15.04. It may be applied in the 
autumn up to 15.11, and application may be started in the spring no earlier than 
01.04, provided the ground is not frozen and is sufficiently dry to avoid run-off 
into  watercourses  and  any  danger  of  subsoil  compaction.  Manure  may  not  be 
applied on the surface of grassland after 15.09.  
Ban  on  the  application  on  slurry  and  poultry  manure  on  arable  land  between 
16/10 and 15/02, on grassland between 16.09 and 31.01.  
Ban on slurry application and other fertilisers from 15.10 until 15.02 on arable 
land on  heavy clay soils. Ban on slurry application  from 01.09 until 15.02 and 
obligation  to  sow  catch  crop/intermediate  crop  after  harvest  of  the  main  crop. 
Ban  on  farmyard  manure  and  compost  application  from  15.11  until  15.01  on 
arable land and grassland 

Source: [ 442, Hansen et al. 2008 ] [ 574, UBA Germany 2011 ] [ 624, IRPP TWG 2013 ] 

Manure  can  have  a  relatively  high  dry  matter  (DM)  content  (dried  poultry  manure  and  litter-
based manure) or can be a mixture of faeces, urine and cleaning water (slurry). Facilities for the 
storage of manure are normally designed and operated in such a way that the substances they 
contain cannot overflow. 

The  design  and  the  construction  material  for  the  manure  storage  facilities  often  have  to  be 
chosen in accordance with the specifications and technical requirements laid down in guidance 
notes or in national or regional regulations (e.g. Germany, the UK, Belgium). The regulations 
are  often  based  on  water  regulations  and  their  objective  is  to  prevent  any  contamination  of 
ground  or  surface  water.  They  also  include  provisions  for  maintenance  and  inspection  and 
procedures to follow in case of an escape of slurry, which could pose a risk of damage to water 
resources. 

Spatial planning of on-farm manure storage is regulated for the protection of water sources and 
to  protect  sensitive  receptors  in  the  vicinity  of  the  farm  against  odour.  Regulations  prescribe 
minimum distances, depending on the number of animals and on farm-specific features, such as 
prevailing wind direction and the type of neighbouring receptors. 

Table 2.17  compares  the  benefits  and disadvantages deriving  from  the  use of  solid  manure  or 
slurry-based manure management systems over the entire chain of farm processes and activities. 

108 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Table 2.17:  Advantages and disadvantages of solid manure- and slurry-based systems 

Chapter 2 

General 
advantages 

General 
disadvantages 

Transport and 
storage 

Fertiliser 
value and 
landspreading 
attributes 

Animal 
welfare 

Industry 
image 

Labour 
requirements 

Straw-based systems 
  More flexible long-term use of houses; 
  May reduce odour problems; 
  Perceived as more animal-friendly. 
  More floor space required per animal;  
  Straw  not  always  easily  available/high 

cost; 

  Potentially  higher  ammonia  and  GHG 

emissions; 

  Higher dust emissions associated. 
  Flexible, as almost any farm bulk trailer 
or  lorry  can  be  used  to  transport  solid 
manure;  

  Manure  may  be  stored  in  field  heaps 

before landspreading; 

  Few  straw-based  units  produce  only 

‘solid’ manure. 

  FYM  provides  a  greater  amount  of 
added  organic  matter,  as  well  as  plant 
nutrients;  
  Spreading 

is  generally  favoured  on 
uncropped  land  or  to  grassland  before 
reseeding, 
potential 
because 
smothering problems.  

of 

  Straw  is  widely  perceived  to  enhance 

the welfare of pigs;  

  Provides 

thermal 

thermal 
comfort ‘buffering’ and a more ‘natural’ 
environment;  

insulation, 

  Specific welfare concerns about outdoor 
production  systems  with  straw-bedded 
shelters;  

  Straw  must  be  of  good  quality,  without 

presence of fungus. 

Slurry-based systems 

  Generally more easily mechanised; 
  Lower labour inputs during housing. 

  Specialised 

storage  and  handling 

equipment required. 

  Almost  always  at  the  unit  itself  and 

must be in dedicated facilities; 

  Slurry  is  usually  moved  in  purpose-
made tankers or via piped systems;  
  High  work  rates  can  be  achieved  by 
pumping  slurry  through  pipelines  and 
tubes.  

  Slurry  can  be  more  readily  applied  to 
growing arable crops and grassland in 
early spring and summer; 

  Greater supply of nitrogen available to 
plant in the season of application. 

  European 

directives 
welfare 
increasingly  discourage  fully  slatted 
floor systems; 

  Poor  management  of  partly  slatted 
floor rearing systems entails problems 
of fouled lying areas; 

  Fully  slatted  floor  systems  have  been 
outlawed  in  new  houses  in  some  EU 
Member States. 

  The  perception  of  better  pig  welfare 
some  pig-meat  marketing 

provides 
advantages; 

  Producers see slatted floor housing as 
the  most  cost-effective  way 
to 
produce. 

  Little  evidence  that  a  higher  price  is 

achieved.  

  Advanced  mechanisation  of  straw  and 

solid manure handling;  

  Activity  involved  in  straw  procurement 

and additional manual tasks;  

  Typically, one extra full-time  worker  is 
required 
straw-based 
breeder/finishing pig unit of about 250–
300 sows. 

for 

a 

  Slurry-based  housing  systems  have 
lower labour requirements at all stages 
of production;  

  General husbandry tasks are generally 
more readily accomplished in housing 
layouts associated with slurry. 

  Straw-based  houses  are  more  flexible, 
but  reconversion  to  a  slurry  system 
would be costly;  

  Many  buildings  could  be 

readily 
adapted  to  other  farm  uses  (simple 
modifications  to  general  purpose  farm 
buildings). 

Flexibility of 
buildings 

  Buildings  with  low  ceiling  heights, 
to 
straw-based  manure 

may  be  difficult 
mechanised 
handling.  

adapt 

to 

  Ventilation  systems  may  not  be 
the 
controlling 
in  straw-bedded  pens 

suitable 
environment 
without modification; 

for 

  Floors  and  supporting  structures  may 
not  be  suitable  for  carrying  the  loads 
imposed  by  straw-based  systems  and 
their 
equipment 

associated  with 

Intensive Rearing of Poultry or Pigs 

109 

 
 
Chapter 2 

Straw-based systems 

Slurry-based systems 

management; 

  Natural  ventilation  could  also  be 
difficult  to  provide  in  many  houses, 
because of lack of headroom. 

Source: [ 253, ADAS 2002 ] [ 624, IRPP TWG 2013 ] 

2.6.2 

Poultry manure 

Solid manure is mostly produced in poultry houses and may be temporarily stored in the same 
building until its removal after the production cycle. The manure is cleared out approximately 
once a year for laying hens in systems without frequent removal (i.e. deep litter), or at the end of 
the  rearing  cycle  for  broilers  and  other  poultry  raised  for  meat.  Some  laying  hen  housing 
systems  allow  for  more  frequent, almost  daily  removal  of  manure (i.e.  with  manure  belts).  In 
free-range  systems,  birds  have  access  to the  outside  environment  and  some  droppings  will  be 
deposited in fields. In large farms, it is not unusual for the collection, further off-farm storage 
and management of the manure to be done by contracted third parties.  

Laying hens produce droppings with a typical moisture content of 80–85 %. The initial moisture 
content is likely to be mainly influenced by nutrition, whilst the drying rate is affected by the 
external  climate,  indoor  environment,  ventilation  and  the  manure  handling  system.  Some 
systems  enable  manure  to  be  dried  to  lower  moisture  content  in  order  to  reduce  ammonia 
emissions.  Some  laying  hens  use  a  litter-based  system  similar  to  broilers.  In-house  manure 
collection and storage systems are described in Section 2.2.1. Different types of manure can be 
obtained: 

  Wet  manure.  This  has  a  dry  matter  content  of  approximately  up  to  30–35 % and  is 

 

 

produced with regular daily removal. 
Pre-dried  manure,  with  a  dry  matter  content  of  approximately  35–50 %.  This  can  be 
produced,  for  example,  in  systems  where  manure  belts  are  fitted  with  pre-drying 
ventilation. 
Dry manure or littered manure. These can be produced in houses with deep pits with air-
drying or in littered houses. The manure has a high dry matter content of up to 80 %. 

Where  manure  belts  are  used,  manure  collection is frequent  (usually  every  one  to  three  days) 
because the weight of the accumulating droppings may hamper the performance of the removal 
system. 

Broilers are typically bedded on wood shavings, sawdust or straw which, when combined with 
bird droppings, produce a fairly dry (around 60 % dry matter) friable manure, often referred to 
as  poultry  litter.  Sometimes  shredded  paper  is  used  as  a  bedding  material.  Peat  is  the  most 
commonly  used  litter  material  for  broilers  and  turkeys  in  Finland.  Poultry  litter  quality  is 
affected  by  temperature  and  by  ventilation,  drinker  type  and  management,  feeder  type  and 
management, stocking density, nutrition and bird health. Systems are described in Section 2.2.2. 

Turkeys are typically bedded on wood shavings or straw (also mixed together) to about 75 mm 
depth,  which  produces  a  litter  of  40 %  to  60 %  dry  matter  as  an  average.  In  comparison  to 
broilers, turkeys tend to wet the litter more in the areas under the drinkers where extended bands 
with  levels  of  dry  matter  between  25 %  and  35 %  can  be  found  [  624,  IRPP  TWG  2013  ]  
[ 9, Italy 2013 ]. Systems are described in Section 2.2.3.2. 

Ducks are normally bedded on straw applying  higher amounts in finishing accommodation. A 
lot of water is spilled and this results in a litter relatively low in dry matter (around 25 % dry 
matter)  [  425,  DEFRA  2010  ].  Systems  are described  in  Section  2.2.3.3.  However,  in  France, 
meat  ducks  are  mainly  raised  on  fully  slatted  floors,  where  slurry  is  produced.  Stores  are 
dimensioned in relation to the surfaces where the ducks are reared, with a capacity of 300 m3 or 
450 m3 per 1 000 m2 of surface, for storage periods of 4 or 6 months respectively [ 257, France 
2010 ]. 

110 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.6.3 

Pig manure 

Slurry  may  be  stored  beneath  fully  slatted  or  partly  slatted  floors  of  livestock  buildings.  The 
storage  period  can  be  quite  short  but  may  extend  to  several  weeks  in  the  deep  pit  within  the 
housing  (e.g.  Belgium-Flanders,  the  UK,  Ireland);  in  general,  inside  storage  is  temporary  and 
slurry  is  regularly  removed  to  an  outside  storage  facility  in  the  farmyard  for  further 
management.  In-house  manure  collection  and  storage  systems  are  described  in  Section  2.3. 
Where  further  storage  is  required  or  where  treatment  is  applied,  slurry  is  usually  sluiced  by 
gravity or pumped to collection pits and/or directly to slurry stores. Slurry tankers are also used. 
Examples of factors used for calculating slurry storage volume are presented in Table 2.18. 

Table 2.18:  Factors  used  for  calculating  storage  dimensions  for  pig  slurry,  in  Belgium-Flanders 

and Spain 

Animal  
physiological state 

Fattening pigs (up to 100 kg) 

ES 
Annual slurry generation 
in m3 per animal place 

2.15 

BE (FL) 
Required storage 
capacity in m3 per 
animal place (1) 
0.8 (0.6 if water-saving 
devices are used) 
0.4 
NI 
2.3 
2.0 
NI 
NI 
1 
0.2  

Growers (20 to 50 kg) 
Finishers (50 to 100 kg) 
Farrowing sows (including piglets) 
Mating and gestating sows, boars 
Sow in a farrow-to-finish farm (2) 
Boars  
Gilts 
Weaners  
(1) Values corresponding to a storage period of 6 months. For a storage period of 9 months, the values 

1.8 
2.5 
5.1 
NI 
17.75 
6.12 
2.5 
0.41 

are increased by half. 

(2) Includes all offspring of the sow until end of fattening period. 
NB: NI = no information provided. 
Source: [ 255, BE Flanders 2010 ] [ 624, IRPP TWG 2013 ] 

Differences  in  similar  factors  are  common  because  the  amount  of  slurry  produced  is  variable 
due to the following aspects: 

 

 

 

 

 

yields and efficiency of the animals; 

amount and type of bedding used; 

spillage of drinking water, depending on the type of drinkers; 

water used for cleaning and sprinkling; 

differences in diet that may cause a higher consumption of drinking water and thus also 
higher urine production. 

Where significant quantities of straw are used for bedding, solid manure is generated which may 
be removed from buildings regularly (every one, two or three days) or (in deep-littered houses) 
after batches of pigs are moved every few weeks. Solid manure and FYM are typically stored in 
concrete yards or on field heaps ready for landspreading. 

In Belgium-Flanders, the factors used for estimating the required manure storage capacity (for a 
minimum of  3 months storage in house) for solid pig manure generated in deep litter housing 
systems are: 

 

 

group-housed mating and gestating sows: 2.4 m3/animal place; 

fattening pigs: 0.7 m3/animal place [ 255, BE Flanders 2010 ]. 

Intensive Rearing of Poultry or Pigs 

111 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Many pig farms produce both slurry and solid manure. There is a tendency to collect the excreta 
and urine separately to reduce ammonia emissions from housing (see Chapter 4). They may be 
mixed again in storage if further treatment of the slurry and/or the solid manure is not required 
[ 506, TWG ILF BREF 2001 ]. 

2.6.4 

Storage systems for solid manure  

Manure  collected  in  solid  form  is  normally  transported  by  front-end  loader  or  (chain)  belt 
systems and stored on an impermeable concrete floor that is placed outdoors or in closed barns. 
The storage system can be equipped with side walls to prevent liquid fractions or rainwater from 
leaking  away.  These  constructions  are  often  attached  to  an  effluent  tank  to  store  the  liquid 
fraction separately. The tank may be emptied regularly or the contents may be moved to a slurry 
store. Double storey constructions are also applied that allow the liquid fraction of manure and 
rainwater to drain into a basin underneath the manure storage area. 

The  storage  of  solid  manure  on  impermeable  surface  is  the  most  commonly  applied  option 
throughout Europe. However, field storage is still often practised. Measures for leakage control 
and collection and separate storage of seepage liquids are applied only in a few countries (e.g. 
Czech Republic, Italy, Germany, Finland) [ 264, Loyon et al. 2010 ].  

In France, solid manure is stored or composted on the field or on a concrete silo. A concrete silo 
may be obligatory, depending on the local water protection regulation. In the case of solid pig 
manure, storage on the field is done only after a two-month period inside the house in order to 
minimise  risks  of  leaching.  The  dry  layer  droppings  are  almost  always  stored  in  a  shed  
[ 259, France 2010 ]. 

Examples  of  calculation  factors,  used  in  France,  for  dimensioning  the  store  for  the  manure 
produced by cage-reared laying hens are reported in Table 2.19. 

112 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Table 2.19:  Factors for calculating the dimensions of the manure store for cage-reared laying hens 

in France (1 000 bird places) 

Chapter 2 

Manure 
collection 
system 

Characteristics 
of manure 

Type of 
manure 

Dry 
matter 
(%) 

Gutters 

Slurry 

< 20 

Belt, no air 
drying 
Belt, no air 
drying 
Belt, no air 
drying 
Belt with 
air drying 
Belt with 
air drying 

Wet 
droppings 
Wet 
droppings 
Wet 
droppings 
Pre-dried 
droppings 
Pre-dried 
droppings 

Belt with 
air drying 

Pre-dried 
droppings 

Store characteristics  

Storage 
type 

External 
pit 
External 
pit 

20–27 

20–27  Covered 
concrete 
silo with 
side 
walls 

28–35 

36–65 

Wall 
height 
(m) 

No 
of side 
walls 

NA 

NA 

1.5 

2 

1.5 

NA 

NA 

4 (1) 

4 (1) 

3 

> 65 

> 65 

Covered 
concrete 
silo 
without 
side 
walls 

NA 

NA 

1.5 

3.0 

3 

3 

< 20 

Droppings 

Underfloor 
pit without 
air drying 
Underfloor 
pit with air 
drying 
(1) The fourth side will have an opening to facilitate access to machinery. 
NB: NA = not applicable. 

Indoor storage in the 
underfloor pit with 
impermeable floor and walls 
Indoor storage in the 
underfloor pit with 
impermeable floor 

Pre-dried 
droppings 

35–65 

Storage period of 
4 months 

Storage period of 
6 months 

Surface 
(m2) 

Volume 
(m3) 

Surface 
(m2) 

Volume 
(m3) 

NA 

NA 

23.3 

NA 

35.0 

23.3 

NA 

35.0 

20.0 

NA 

24.0 

NA 

11.2 

NA 

14.0 

NA 

6.7 

6.7 

4.7 

3.3 

NA 

10.0 

NA 

NA 

10.0 

NA 

NA 

NA 

7.0 

5.0 

NA 

NA 

Storage surface = surface of the building 

Storage surface = surface of the building 

Source: [ 257, France 2010 ] 

In Belgium-Flanders, the factors used for estimating the manure storage capacity for the rearing 
of pullets and laying hens are the following [ 255, BE Flanders 2010 ]: 

 

 

pullets (wet manure): 10 m3/1 000 animal places; 

laying hens (wet manure): 30 m3/1 000 animal places. 

When manure is collected and carried away from housing immediately, especially when further 
management  is  done  by  third  parties,  there  is  no  need  for  intermediate  manure  storage.  For 
instance, daily collection from belts under laying hens or direct transport of broilers’ manure at 
the end of cycle can be done directly from the farm to a third party or for landspreading.  

Temporary field heaps can be created prior to landspreading. They  may remain in place for a 
few days or for several weeks. Since soil and water contamination can occur, depending on the 
rainfall and the length of storage, heaps should be located where there is no risk of direct run-off 
entering watercourses or infiltration of liquid fractions seeping from heaps to groundwater (e.g. 
in  a  well-drained  location  away  from  drainage  ditches  or  away  from  karstified  limestone). 
Member  States  regulate  temporary  field  heaps  in  different  ways  by  requiring  covers  (the 
Netherlands,  Finland,  France),  regulating  the  length  or  the  season  of  the  storage  (the 
Netherlands,  Belgium,  the  UK),  the  quantity  and  maturity  of  the  manure  (Austria),  or 
demanding a yearly rotation of the place of storage (the Netherlands, Austria, the UK, France). 
Some  examples  of  the  requirements  applied  in  different  Member  States  for  temporary  field 
heaps are presented in Table 2.20. 

Intensive Rearing of Poultry or Pigs 

113 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

Table 2.20: 

Examples of requirements applied for temporary field heaps in different Member 
States 

EU Member 
State 

Austria 

Belgium-Flanders 

Requirements 

No  requirement  to  cover  field  heaps.  A  three-month  storage  should  lead  to 
natural self-heating and the amount should correspond to the fertilising demand 
of the farm (about 25 t/ha). Mandatory yearly change of the storage place. 
Storage  of  solid  manure  in  field  heaps  is  forbidden  during  the  period 
landspreading is banned (15 November – 15 January) and is only permitted for a 
maximum of 1 month (pending landspreading) outside that period. 

France 

Ireland 

Finland 

Belgium-Wallonia  No requirement to cover the field heaps. The heap has to be relocated each year.  
The  manure  heap  can  be  placed  in  the  middle  of  the  field  or,  in  the  case  of  a 
gently sloping field, near the top. A layer of mud or peat at least 15 cm thick has 
to  be  spread  at  the  bottom  of  the  heap  in  order  to  catch  nutrient  run-off.  In 
winter, snow must first be removed from the site. Manure has to be piled up in 
one or a few large heaps. Piling up manure in the same place every year must be 
avoided.  Manure  heaps  must  always  be  covered  with  a  tarpaulin  or  a  layer  of 
peat  or  an  equivalent  protective  layer  at  least  10  cm  thick,  in  order  to  prevent 
excessive run-off and emissions to air. 
Location of temporary field heaps must change every year and, in this case, there 
is no need for a solid impermeable floor with drains. Mandatory cover only for 
poultry manure. No obligation to store solid pig manure on a solid floor if it has 
remained more than 2 months in-house in deep litter housing systems. 
Requirement for compact heap.  
Temporary storage is permitted on agricultural land only after storage for at least 
90 days and for a period not exceeding 3 months. Storage cannot be repeated in 
the same place within the same crop year. Temporary heaps must be of sufficient 
size and shape to ensure good aeration of the mass and, in order not to generate 
leachate, the necessary measures must be taken to complete drainage of leachate 
before  transfer  in  the  field  and  prevent  the  infiltration  of  rainwater,  as  well  as 
provide appropriate soil waterproofing. 
For temporary manure storage of 2 weeks or more, an absorbent layer of at least 
0.15 metres,  with  at least 25 % organic  matter (e.g. peat) is  requested. Contact 
with rainwater has to be prevented as  much as possible (in practice this  means 
the  use  of  a  plastic  sheet).  Requirements  may  be  applied  at  local  level  for 
temporary  manure  heaps  of  less  than  2  weeks  (same  protection  as  for  older 
heaps). 
Solid  manure  heaps  must  be  covered  and  have  to  be  stored  on  places  with 
impermeable surface covers (e.g. concrete) and liquid collection facilities. 
Covering  of  the  heaps  is  not  always  required.  Criteria  as  to  where  temporary 
field heaps may be located, and for how long, are normally applied. 

United Kingdom 

Netherlands 

Denmark  

Italy 

Source: [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ] 

2.6.5 

Storage systems for slurry 

2.6.5.1 

Slurry storage in tanks 

Slurry,  or  the  liquid  fraction  of  slurry  after  separation,  is  usually  stored  in  tanks  made  of 
concrete  or  steel  panels.  Slurry  is  pumped  from  the  slurry  pit  or  slurry  channel  inside  the 
housing to the external slurry storage system. Slurry is transported via a pipeline or by means of 
a slurry tanker, and can be stored in slurry tanks above or below ground.  

Slurry  storage  systems  consist  of  collection  and  transfer  facilities.  Collection  facilities  are 
structural-technical  facilities  (channels,  drains,  pits,  pipes,  slide  gates)  for  the  collection  and 
piping  of  liquid  manure,  slurry  and  other  effluents,  including  the  pumping  station  (i.e.  the 
reception pit from where the tank is filled or emptied). Valves and sliding gates are important 
devices  to  control  (back)  flow.  Although  single  valve  designs  are  still  common,  double  valve 
(sliding  gate)  designs  or  the  blocking  of  valves  are  recommended  for  safety  reasons.  The 

114 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 2 

structural-technical  facilities  intended  for  homogenisation  and  transfer  of  liquid  fractions  and 
slurry are called transfer facilities. 
Emissions  to  air  from  slurry  stores  can  be  reduced  by  decreasing  or  eliminating  the  airflow 
across the surface. Slurry tanks can be open or may be covered with a natural crust formed on 
the  surface  of  the  stored  slurry,  an  artificial  layer  of  floating  matter  (such  as  granulated 
materials, straw chaff or floating membrane) or with a firm cover (such as a canvas or concrete 
roof) to keep rainwater out and to reduce emissions. Both below- and above-ground stores may 
have a solid cover over the tank which is not in contact with the slurry surface. Formation and 
accumulation of gases in slurry stores present a real and significant health and safety hazard to 
operators. 

Only  in  some  Member  States  (e.g.  the  Netherlands,  Denmark)  are  the  slurry  storage  facilities 
generally  covered  by  tents  or  roofs.  Open  storage  is  still  widespread  along  with  the  use  of 
natural  or  artificial  crust  forming  [  264,  Loyon  et  al.  2010  ].  Other  options  for  reducing 
emissions from slurry stores  is the reduction of the surface area per unit volume of the slurry 
store (appropriate store design) and slurry acidification.  

Underground tanks and reception pits are often used to store small amounts of slurry and can act 
as reception pits to collect slurry before it is pumped to a larger slurry  store. They are usually 
square  constructions  built  from  rendered  reinforced  blocks,  reinforced  concrete  made  on  site, 
ready-made concrete panels, steel panels or GRP. With blocks or bricks, extra attention is paid 
to  the  impermeability  by  applying  elastic  coating  or  lining.  Occasionally,  larger  stores  are 
constructed  with  reinforced  concrete  or  block-work,  or  concrete  panels;  they  may  be  partly 
underground,  and  are  often  rectangular  in  shape.  Underground  tanks  made  of  reinforced 
concrete  elements  are  the  most  common  storage  systems  for  slurry  in  cold  regions.  They  are 
built with a common capacity of 5 000 m3 as circular and partly underground of up to 3 000 m3 
(e.g. in Finland 1 000–2 500 m3 as circular and partly underground).  

Above-ground circular stores are normally made from curved steel panels or concrete sections. 
Steel panels are coated to protect them against corrosion, usually with paint or a ceramic layer. 
Some  concrete  panel  stores  may  be  partly  underground.  Normally,  all  stores  are  built  on  a 
properly designed reinforced concrete base. In all tank designs, the thickness of the base plate 
and  the  suitability  of  the  seal  at  the  joint  of  the  wall  and  the  tank  base  are  very  important 
features to prevent slurry from leaking away. A typical system has a reception pit with a grid 
cover next to the main store. A pump is used to transfer slurry to the main stores; the pump can 
be fitted with an extra outlet to allow slurry  mixing in the reception pit. Above-ground slurry 
tanks  are  filled  via  a  pipe  with  an  opening  above  or  below  the  slurry  surface.  Since  gas  and 
odour emissions are different if the slurry is pipe-loaded from above or below the surface of the 
stored slurry, authorisations (e.g. Finland) may require that tanks are filled by a pipe below the 
slurry surface. Prior to discharge or filling, slurry is normally thoroughly mixed with hydraulic 
or  pneumatic  stirring  systems  to  agitate  sediment  and  floating  matter  and  to  obtain  an  even 
distribution of the nutrients. Slurry mixing can be carried out using propellers, either mounted 
through the side of the store or suspended from a gantry over the top of the store. Stirring can 
cause  sudden  releases  of  large  quantities  of  noxious  gases  and  proper  ventilation  is  required, 
particularly if done in housing. 

The  main  store  may  have  a  valve  outlet  to  allow  for  emptying  back  to  the  reception  pit,  or 
alternatively it can be emptied using a pump located in the store (Figure 2.28). 

Intensive Rearing of Poultry or Pigs 

115 

 
 
 
 
 
 
 
Chapter 2 

Source: [ 404, Tank manufacturer 2000 ] 

Figure 2.28:  Example of above-ground slurry tank with an underground receiving pit 

The  typical  size  is  1 500  m3,  within  the  range  of  500–5 000  m3,  which  is  made  up  of  round 
sections of 20 m in diameter or by boxed sections with a height of 5.2 m. A freeboard of at least 
0.5–0.75 metres is always left when filling the store, according to local conditions. 

2.6.5.2 

Slurry storage in earth-banked stores (or lagoons)  

Earth-banked walls or lagoons are commonly applied in many MS to store slurry for extended 
periods of time. They are normally a large rectangular or square shaped structure with  sloping 
earth  bank  walls  (earth-banked  lagoon)  with  a  large  surface  area  to  depth  ratio.  Their  design 
varies from simple ponds without any provisions to relatively well monitored storage facilities 
with  water-impermeable  lining  such  as  clay  or  thick  plastic  sheets  (e.g.  polythene  or  butyl 
rubber) on the bottom, protecting the soil underneath. The capacity of a lagoon depends on the 
slurry  generation  of  the  farm  and  the  operational  requirements.  Slurry  can  be  mixed  using 
pumps or propellers. If the slurry is not transported by pipelines but by a vacuum tank, earth-
banked stores can be equipped with an access ramp. The earth-banked store is often fenced off 
to prevent accidents. 

The  durability  of  lagoons  is  considered  to  be  10–15  years.  Capacity  varies  from  500 m3  to 
7 500 m3. The typical size is 1 500 m3, on an area of 15 × 30 m, with a depth of 4 m (0.5–0.75 m 
must be kept as a freeboard), to store manure of 1.0–1.1 t/m3 for a period of 6 to 10 months. For 
a capacity larger than 5 000 m3 and up to 7 500 m3, the homogenisation of the stored slurry is 
increasingly difficult.  

The soil used to construct an earth-banked store needs special properties to ensure stability and 
low  permeability,  which  usually  means  a  high  clay  content  (in-situ  clay  or  clay-lined  stores). 
These  stores  are  built  below,  above  or  partly  below/above  ground  level.  Earth-banked  stores 

116 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
also include a minimum allowance for freeboard in order to limit erosion and pressure on the 
bank and avoid overtopping (see Figure 2.29). These stores are not authorised in some Member 
States  if  they  are  not  equipped  with  a  geomembrane  liner  system  (i.e.  double-layered  plastic 
geomembrane) and with leakage control [ 257, France 2010 ].  

Chapter 2 

Source:[ 402, ADAS 2000 ] 

Figure 2.29:  Example of earth-banked slurry store, and design features 

On  some  farms  located  in  Mediterranean  countries,  a  multiple  earth-banked  store  or  lagoon 
system is used for biological treatment and not just for storage. In each store, slurry is held for a 
certain  period  of  time  for  aerobic  or  anaerobic  degradation  depending  on  the  design,  loading 
rate  and  type  of  microorganism  present.  Transport  between  the  different  stores  can  be  done 
mechanically  or  by  gravity,  using  the  natural  height  differences  of  the  site.  In  Portugal  for 
example,  these  systems  are  normally  designed  and  operated  to  comply  with  treatment 
requirements,  although,  due  to  legal  restrictions  on  the  quality  of  the  discharged  slurry,  the 
majority of farms use lagoons to store the slurry before landspreading it as fertiliser.  

The size of the earth-banked storage system may not allow the installation of some abatement 
techniques  for  the  control  of  gaseous  emissions  (e.g.  plastic  sheets  may  not  be  applicable  to 
large existing lagoons). 

2.6.5.3 

Other types of slurry storage  

For  the  short-term  storage  of  relatively  small  amounts  of  slurry,  flexible  bags  are  used.  They 
may be moved from farm to farm (when empty). Larger bags may be sited more permanently in 
earthworks to provide longer-term storage. Such stores are filled and emptied via pumps and the 
larger stores can be equipped with mixing tools. Slurries can also be stored in masonry stores, 
which constitute the stores with the highest risk, particularly with age.  

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117 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.7  On-farm manure processing 

To reduce nitrogen and phosphorus losses from livestock manure, it is important to manage the 
manure  effectively  so  as  to  improve  utilisation  of  the  nutrient  content,  thereby  reducing  the 
mineral fertiliser requirement.  

Where  farmers  have  insufficient  land  to  accommodate  the  manure  being  produced  they  are 
encouraged to export manure to their neighbours or look to reduce livestock numbers, in order 
not to exceed the limits imposed by the Nitrates Directive (91/676/EEC) concerning the amount 
of nitrogen that can be applied on farm. Movement of manure is an added cost and a potential 
source  of  odours  and  problems  with  biosecurity,  but,  at  the  same  time,  reduction  in  livestock 
numbers may not be economically viable.  

Some countries have opted to encourage the processing of livestock manure so as to improve its 
manageability and utilisation. It is important that manure processing does not increase losses of 
gaseous forms of nitrogen (NH3, N2O, NOX), or the formation and release of other (greenhouse) 
gases: CO2 and CH4 [ 203, ADAS 2005 ]. 

In some EU countries, manure processing is frequently done by mobile units run by contractors 
moving from farm to farm (e.g.  Denmark, Belgium-Flanders and France)  [ 256, VITO 2006 ] 
[ 259, France 2010 ] [ 533, Baltic Sea 2020 2011 ]. 

A report suggested on the basis of data from Member States that manure processing reached an 
average  level  of  7.8 %  of  the  total  livestock  manure  production,  with  a  big  variation  from 
country  to  country.  The  processing  comprises  108 million tonnes  of  manure,  containing 
556 000 tonnes of nitrogen and 139 000 tonnes of phosphorus. The largest share of the livestock 
manure production is being processed in Italy, Greece and Germany, with 36.8 %, 34.6 % and 
14.8 % respectively of the total. Anaerobic digestion is by far the most commonly used manure 
processing technology; 88 million tonnes of livestock manure and other products are processed 
in this way [ 595, Agro Business Park 2011 ]. 

Besides  on-farm  treatment,  manure  may  also  be  (further)  treated  off-site  in  industrial 
installations  such  as  poultry  litter  combustion  plants  and  centralised  composting  plants.  The 
assessment of off-site treatment is outside the scope of this document. 

FYM is not often treated, but in some cases it is composted, dried or treated anaerobically. In 
some  southern  countries  (e.g.  Italy,  Cyprus,  Portugal),  solids  separation  in  pig  slurry  is  of 
practical  importance,  possibly  because  of  the  value  ascribed  to  the  organic  matter  recovered. 
Amongst  all  other  treatment  techniques,  anaerobic  and  (to  a  lesser  extent)  aerobic  treatments 
have  some  use.  Interest  in  anaerobic  digestion  has  increased  due  to  the  rewards  of  biogas 
production [ 264, Loyon et al. 2010 ]. 

Manure processing prior to landspreading may be performed for the following reasons: 

 

 

 

 

 

 

to recover the residual energy (biogas) in the manure; 

to reduce odour emissions during storage and/or landspreading; 

to separate the solid phase of slurry; 

to decrease the nitrogen content of the manure to prevent groundwater and surface water 
pollution as a result of landspreading, and to reduce odour; 

to allow easy and safe transportation to other sites for application in other processes. 

to  reduce  the  gaseous  N  and  C  losses  from  manure  during  housing,  storage  and 
landspreading.  

The latter two reasons are frequent in regions with a nutrient surplus. 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

Organic  compounds  can  be  converted  to  methane  by  the  anaerobic  biological  digestion  of 
manure.  The  recovered  methane  is  normally  used  as  a  fuel  in  combined  heat  and  power 
production (CHP) systems for the production of electricity to sell in the public network and of 
heat to use at the farm or in the neighbourhood. In this way, the use of fossil fuels that would 
otherwise be needed to produce electricity and/or heat can be reduced. 

Odour  nuisance  that  occurs  during  or  after  the  storage  of  manure  can,  in  some  instances,  be 
reduced by aerobic or anaerobic treatment or by additives [ 506, TWG ILF BREF 2001 ].  

The solid phase, which is rich in phosphorus, can be separated from the liquid phase, which is 
rich in nitrogen, allowing for a more adequate and environmentally balanced use of nutrients, 
especially in order to avoid over-fertilisation with phosphorus. 

Nitrogen compounds in manure (organic, ammonium, nitrites and nitrates) can be converted to 
environmentally  neutral  nitrogen  gas  (N2).  The  most  common  technique  in  this  regard  is  the 
biological  nitrification-denitrification:  bacteria  convert  organic  and  ammonium  nitrogen  to 
nitrites and nitrates (nitrification) and further still to nitrogen gas (denitrification). 

On the other hand, reducing the N content of manure may mean that there is less N to be used as 
a  fertiliser  (compared  to  raw  manure).  This  amount  of  N  that  can  no  longer  be  provided  by 
manure then has to be supplied through the addition of mineral fertilisers, with the consequent 
indirect  emissions  associated  with  the  production  of  the  mineral  fertiliser,  including  N2O 
emissions. 

The  water  content  and  volume  of  the  manure  can  be  reduced.  In  addition,  pathogenic 
microorganisms  present  in  the  manure  can  be  deactivated  (this  prevents  the  spreading  of 
livestock  pathogens  to  other  regions),  and  odour  emissions  reduced.  Sometimes  different 
manure  compounds  are  separated  for  market  reasons.  The  techniques  given  below  are  often 
used: 

 

 

 

 

 

 

 

Separation  technologies  (e.g.  mechanical  separation):  separation  of  slurry  into  one  or 
more liquid and one or more solid fractions (see above).  
Ammonia  stripping:  after  pH  adjustment,  NH3  is  stripped  from  the  manure  fluid  and 
captured. 
Evaporation:  liquid  manure  is  heated  or  depressurised,  the  resulting  vapours  are  then 
condensed and further treated. 
Drying:  solid  manure  is  dried  by  air  or  animal  body  heat  (see  also  Section  4.5),  by 
burning fossil fuels, or by burning biogas from manure fermentation. 
Lime  treatment:  lime  (CaO  or  CaO-MgO)  is  added  to  the  manure,  with  the  aim  of 
reducing  the  amount  of  pathogens.  The  resulting  increase  in  pH  and  temperature  also 
leads to an increased release of NH3 in the air and a volume reduction. 
Composting: the volume of the solid pig manure fraction or poultry manure is reduced, 
and  also  many  pathogens  are  inactivated  by  the  temperature  increase  caused  by  the 
biological  degradation  of  organic  material.  The  composting  of  poultry  litter  is,  for 
example, used in the mushroom industry in Ireland. Under unfavourable conditions, this 
technique increases the potential for NH3, N2O and CO2 emissions. 
Pelletising:  dried  manure  may  be  converted  to  fertiliser  pellets,  but  with  a  notable 
expense for energy consumption. 

By regulating (reducing) the pH of slurry, a reduction in both ammonia and methane emissions 
can  be  achieved.  If  performed  during  in-house  storage,  slurry  acidification  (mainly  by  adding 
sulphuric acid) prevents these emissions occurring in the slurry management chain. 

In  the  following  sections  some  techniques  used  for  manure  processing  are  described  in  more 
detail. 

Intensive Rearing of Poultry or Pigs 

119 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.7.1 

Mechanical separators 

Natural settling (gravity sedimentation) is the easiest and cheapest way to remove undissolved 
material  from  liquid  manure  (slurry).  It  is  performed  in  a  thickener,  in  batch  or  continuous 
mode.  Most  thickeners  consist  of  a  container  that  is  cylindrical  at  the  top  and  conical  at  the 
bottom. Slurry is added to the top of a thickener and the suspended solids settle at the bottom of 
the  conical  part  by  gravity  from  where  they  can  be  removed.  A  secondary  function  is  the 
provision  of  storage  capacity.  However,  the  process  can  be  inefficient  as  it  requires  time  and 
space.  Thickeners  can  also  be  operated  in  continuous  mode,  where  the  slurry  is  added 
continuously, while solid and liquid fractions are removed at the same rate [ 594, Agro Business 
Park 2011 ] [ 203, ADAS 2005 ]. 

Mechanical separation is another separation process that separates slurry into a stackable solid 
fraction (solids or fibrous material at around 10–25 % of the initial mass) and a liquid fraction 
(at around 75–90 % of the initial mass). Separating the suspended solids from slurry means that 
the  two  manure  streams  can  be  handled  separately.  With  this  processing  option,  nutrients 
(especially P) and organic matter can be concentrated in the solid phase and transported to other 
regions  without  a  nutrient  surplus.  The  main  process  parameters  (i.e.  throughput,  separation 
efficiency, volume reduction and energy consumption) are influenced by many factors: 

 

 

 

 

 

type of the separator; 

sieve mesh size (or centrifugal force); 

slurry type; 

additives (water, flocculants); 

total solid content of the raw manure. 

A  wide  range  of  mechanical  separators  are  available.  Commonly  applied  techniques  include 
[ 219, Netherlands 2010 ]:  

 

 

 

 

Simple screen separators: these have a metal sieve mesh in either a vibrating, inclined or 
rotary screen. In rotary screen separators the sieve mesh is mechanically cleared of solids 
using  pressure  rolls,  brusher  rolls  or  scrapers.  The  separation  efficiency  is  low  to 
moderate.  

Screw separators: these are equipped with a rotating metal or plastic screw or auger that 
forwards  the  liquid  manure  into  a  cylindrical  metal  tube  fitted  with  small  openings  to 
allow the liquid fraction to be squeezed out. The end of the tube is closed using a piston 
that  provides  sufficient  back  pressure.  A  properly  set  back  pressure  can  ensure  this 
process is capable of removing about 25 % of phosphorus from pig slurry. This type of 
machine can easily be tuned to the specific needs of the farm (e.g. the production of dry 
solids suitable for composting or a wetter solid fraction with a higher nutrient removal). 

Belt filter presses: these are large separators often used in waste water treatment plants. 
Manure is fed between two parallel conveyor belts, one of which is permeable to water 
(the sieve belt). By means of pressure rolls, the liquid fraction is separated from the solid 
fraction.  To  establish  a  high  separation  efficiency  (50–75 %  phosphorus  removal), 
additives (flocculants) such as multivalent cations (e.g. FeCl3) and/or polymer flocculants 
(e.g. polyacrylamides) are applied to enhance the aggregation of suspended particles. Belt 
filter presses are designed to yield a highly clarified effluent. Because of their size, belt 
filter presses are not suitable for mobile separators. 

Centrifuges and decanters (vertically placed centrifuges): separation is achieved through 
centrifugal  forces  generated  by  the  rapid  rotation  of  the  installed  sieve  drum.  These 
separators are capable of efficiently removing small particles of high specific density, and 
are used to dewater sludge in waste water treatment plants. Without chemical additives, 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
centrifuges  can  obtain  a  high  phosphorus  separation  efficiency  of  50–70 %.  The 
drawback of these machines is the robustness, the capital cost and the high operating cost 
[ 257, France 2010 ]. Centrifuges can be incorporated in mobile equipment. 

Chapter 2 

Belt filter presses, screw presses and centrifuges may need an initial pre-separation stage or a 
cutting machine when large solid particles are present in the slurry in order to avoid clogging in 
parts of the equipment. Screw presses and centrifuges are more susceptible to wear, as a result 
of the presence of sand, than the other types of separators. Process parameters can be adjusted in 
slurry separation equipment, allowing optimisation of the separation efficiency. 

In  general,  mechanical  separation  is  performed  as  a  first  process  step  prior  to  the  aerobic 
treatment  of  slurry,  to  reduce  the  oxygen  requirement,  and  thus  the  energy  needs  
[ 257, France 2010 ]. Composting of the solid fraction can be applied afterwards to enhance its 
value. Aerobic treatment can be applied to further reduce the nitrogen surplus in the remaining 
liquid  fraction  or  this  fraction  is  landspread  without  further  treatment.  The  solid  fraction  can 
also be treated by anaerobic digestion. Similar systems to those applied on farm also exist for 
centralised facilities [ 264, Loyon et al. 2010 ].  

On the contrary, liquid manure can be converted into solid manure by mixing it with peat. There 
are mixers for this purpose, which makes this method practicable. Straw or sawdust can also be 
used as litter material, although Finnish work has shown that peat absorbs water and ammonia 
more  efficiently  and  also  prevents  the  growth  of  harmful  microbes.  This  method  has  been 
recommended, especially on farms in Finland where the storage capacity of the liquid manure 
tank is not adequate to accommodate all the liquid manure produced and where building a new 
tank is not considered profitable. Peat manure is a good soil improvement material for soil that 
is  poor  in  humus.  Liquid  manure  mixed  with  peat  produces  less  odours  than  liquid  manure 
alone;  here  the  carefully  mixed  liquid  manure  is  pumped  into  a  machine  which  mixes  liquid 
manure with peat into litter manure. 

On the other hand, peatlands are important wetlands and natural ecosystems with a high value 
for  biodiversity  conservation  and  climate  regulation.  Inappropriate  management  may  lead  to 
their degradation, with major environmental and social impacts, such as significant emissions of 
carbon  gases  (CH4,  CO2)  causing  global  warming,  and  a  loss  of  biodiversity  and  fresh  water 
resources [ 428, GEC 2008 ]. 

2.7.2 

Aerobic digestion (aeration) of liquid manure 

On some pig farms, aerobic digestion is used to improve the properties of liquid manure such as 
to  reduce  odour  emissions  from  pig  slurry  by  the  biological  oxidation  of  volatile  organic 
compounds, to decrease pathogens and BOD content, to produce a stabilised and homogenous 
liquid manure, and, in some cases, to reduce its nitrogen content.  

Slurry contains large quantities of nutrients for plants and microorganisms, as well as microbes 
that are capable of utilising these nutrients. The air conducted into liquid manure starts aerobic 
decomposition, which produces heat, and as a result of the aeration, bacteria and fungi which 
use  oxygen  in  their  metabolism  multiply.  The  main  products  from  the  activity  of 
microorganisms are carbon dioxide, water and heat. The associated heat generation can provide 
pathogen control.  

The main types of biological aerobic system are the following: 

 

 

intermittent aeration without any separation; 

intermittent aeration followed by sedimentation of aerated slurry; 

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121 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

 

 

mechanical  separation  of  raw  slurry  followed  by  intermittent  aeration  of  the  liquid 
fraction and sedimentation of aerated slurry; 

mechanical  separation  of  raw  slurry,  followed  by  intermittent  aeration  of  the  liquid 
fraction, and the mechanical separation of the aerated slurry with the addition of chemical 
flocculating agents or polymers. 

The  use  of  continuous  aerobic  treatments  is  declining  in  favour  of  intermittent  processes 
(aeration  in  sequential  batch  reactors  –  SBR).  The  air  supply  is  achieved  mostly  by  surface 
aerators or by fine bubble diffusers [ 264, Loyon et al. 2010 ]. In some cases, aerobic treatment 
is performed on slurry stored in lagoons [ 204, IMPEL 2009 ]. 

2.7.3 

Composting of solid manure  

The  composting  of  solid  manure  is  a  form  of  controlled  aerobic  treatment  which  can  occur 
naturally  in  farmyard  manure  heaps,  and  that  produces  a  more  stable product,  with  consistent 
chemical  properties,  than  the  initial  material.  A  high  porosity  (30–50 %)  is  required  for 
sufficient aeration. In addition, for manure to be composted it has to contain a certain amount of 
water, to ensure the development of microorganisms [ 257, France 2010 ].  

Temperatures  in  the  compost  heap  are  between  50 °C  and  over  70 °C  and  kill  most  of  the 
pathogens,  thus  cleansing  the  product.  A  significant  water  loss  also  takes  place  at  high 
temperatures, and compost with a dry matter of up to 85 % can be produced. 

Suitability for application depends on the structure of the manure, but requires a minimum dry 
matter content of 20 %. During composting the manure, which is usually arranged in windrows, 
is  monitored  for  temperature  and  moisture;  these  cannot  be  excessive  as  this  would  inhibit 
aeration.  Treated  effluent  from  manure  processing,  dirty  water  or  slurry  can  be  added  to  dry 
windrows. The compost is turned regularly using a windrow turner or other available farmyard 
machinery. On the largest units, composting vessels can be used instead of windrows.  

Typical FYM heaps do not satisfy the requirements for thorough composting. With controlled 
application, manure is composted in stacks of a size that suits the aerobic conditions and the use 
of  machinery.  Composting  can  also  be  performed  in  a  barn  (e.g.  pre-dried  poultry  manure). 
Specific systems have been developed that consist of a combination of tanks with aeration and 
stirring  equipment  to  enhance  the  fermentation  process  and  containers  or  boxes  for  further 
fermentation and drying. 

For  farmers,  the  main  advantage  of  composting  is  the  significant  reduction  in  the  volume  of 
material  to  be  transported  and  spread.  Other  potential  benefits  include  efficient  decrease  in 
pathogens  through  generation  of  heat,  reduction  in  odour,  concentration  of  nutrients  and  a 
lighter,  friable  and  more  homogeneous  product  (compost),  which  is  easier  to  handle  than 
untreated manure. Generally, the physical properties, the stability, and the organic form of the 
contained nitrogen make compost a good fertiliser and soil improver.  

Co-composting is the composting of solid manure with other organic substrates (usually green 
wastes) and, in general, it is applied to achieve an optimal C/N ratio of around 25–30, in order 
to ensure efficient composting. The best results are obtained by using well chopped straw and 
solid manure in the right proportions in long narrow windrows. A biological inoculum can be 
added to start up the degradation. For easier handling, pelletising can be applied in addition to 
composting. 

Composting  installations  handling  animal  manure,  which  is  an  animal  by-product,  must  be 
approved  under  Regulation  (EC)  1069/2009, in  accordance  with  Article  24. The  requirements 
applicable  to  composting  installations,  concerning  hygiene,  operational  parameters  and 
standards of derived products are set out in Article 10 and Annex V of Regulation 142/2011/EC.  

122 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.7.4 

Anaerobic digestion of manure in a biogas installation 

Anaerobic digestion of pig slurry is carried out in a digester in the absence of free oxygen, and 
consists  of  the  methanogenic  anaerobic  decomposition  of  organic  matter  by  microorganisms. 
The benefits of the process include the production of biogas, the stabilisation and hygienisation 
of the digested manure (digestate) which can be landspread as a soil conditioner and a source of 
nutrients  (e.g.  N  and  P)  with  improved  N  availability  for  the  plants  due  to  mineralisation, 
compared  to  the  untreated  slurry.  Less  odour  is  also  produced  during  landspreading.  The 
resulting  biogas  (approximately  50–75 %  methane  and  30–40 %  carbon  dioxide)  provides  a 
source of renewable energy, replacing fossil fuel use, which can be used for heating and/or for 
generating electricity.  

Processes can vary with temperature, process management, operating time and substrate mixing. 
In  practice,  the  mesophilic  process  (operated  in  a  temperature  range  of  30–45 °C)  is  most 
common for digesters at the farm scale. In large reactors, where the aim is generally to reduce 
the retention time  (and thus the reactor volume required), the thermophilic  process is applied, 
which  runs  at  a  higher  temperature  (50–55  °C).  In  the  case  of  joint  biogas  plants  (shared  by 
several  farmers),  the  thermophilic  process  is  also  preferred,  in  order  to  achieve  improved 
sanitisation [ 257, France 2010 ]. 

On  the  other  hand,  bacteria  are  very  sensitive  to  temperature  changes  and  this  sensitivity 
increases  with  higher  temperatures.  Moreover,  a  higher  temperature  shifts  the  equilibrium  of 
nitrogen towards more ammonia production, which renders the process vulnerable to ammonia 
inhibition (too much ammonia is toxic for methanogenesis bacteria).  

The  anaerobic  digestion  can  be  carried  out  either  in  intermittent  or  continuous  mode. 
Continuous  systems  are  the  most  common.  Here  the  digester  receives  a  continuous  flow  of 
substrate  (e.g.  slurry),  for  an  average  residence  time  of  the  mass  of  50–60  days,  whilst  an 
identical volume of digested matter is expelled daily. The plant is in operation throughout the 
year; the accruing biogas is produced continuously and may be stored in gas bags and used in 
combined heat and power (CHP) production units, or burnt directly to provide heat, including 
for the digester. The waste heat of the biogas engine is used to heat up the digester. The biogas 
can also be upgraded for direct use in the natural gas grid, or for producing a fuel that can be 
used for applications in transportation. 

In  discontinuous  (batch)  systems,  the  digester  is  charged  with  various  substrates  and  is 
hermetically  closed.  During  the  fermentation  (2  to  4  weeks),  the  matter  is  degraded  and  the 
digester is then emptied. In this system, the volume of produced biogas and its composition are 
not  constant  over  time.  For  this  reason,  several  digesters  are  installed  in  parallel  operating  in 
shifts [ 257, France 2010 ] [ 345, France 2010 ]. 

Slurry is ideally suited to anaerobic digestion, as it is easy to transfer and use, it has a high load 
of fresh bacteria, it is easily manipulated, it can be used to dilute other substrates, and it has a 
strong buffer effect (stabilises the pH), which facilitates the bacterial reactions and ensures the 
stability of the environment where the reaction takes place. Organic wastes, energy crops and 
solid  pig  and  poultry  manure  or  the  solid  fraction  from  mechanically  separated  slurry  are 
conveniently used to raise the dry matter content (which increases the yield and reduces heating 
needs),  but  conversely  incur  an  additional  cost  for  the  increase  in  energy  use.  Mixing  of  the 
mass  has  been  reported  to  be  more  difficult  for  dry  matters  higher  than  10 %  in  the  digester 
[ 257, France 2010 ].  

High initial installation costs are a major deterrent but can be overcome with targeted renewable 
energy  incentives  or  other  rewards  for  the  multiple  environmental  benefits  of  the  anaerobic 
digestion. Anaerobic digestion by the dry process based on solid manure is  currently not very 
developed but is a promising technique for the future as it requires less investment. 

Intensive Rearing of Poultry or Pigs 

123 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.7.5 

Anaerobic lagoon system 

Lagoons serve as a store for pig slurry and waste water, as well as for the biological anaerobic 
treatment  of  the  slurry  under  ambient  temperature  conditions.  The  treatment  system  may 
involve mechanical separation of the solids and the subsequent separate treatment of solids and 
liquids.  A  mechanical  separation  of  slurry  before  entering  the  lagoon  system  can  prevent  the 
capacity of the lagoon being reduced by sedimentation of sludge, and also reduces the organic 
matter in the liquid part.  

Slurry or the liquid fraction from  mechanical separation is put into a settling basin or lagoon, 
from  which  it  overflows  or  is  pumped  into  the  anaerobic  lagoon  system  (often  three  to  five 
earth-banked structures). The capacity of the lagoon that first receives the slurry is reduced over 
time by the sedimentation of the solid fraction, and needs to be desludged from time to time.  

The liquid from the second lagoon is sometimes used for flushing the pits under the pig pens. It 
is  believed  that  the  second  lagoon  provides  a  certain  degree  of  protection  against  disease-
carrying organisms carried over from the first lagoon. 

The  anaerobic  conditions  inside  the  lagoon  can  lead  to  emissions  of  gases  like  methane  and 
nitrous oxide which are related to the lagoon's surface size. The slurry and air temperature affect 
the  biological  activity  in  the  lagoon,  by  changing  the  type  of  predominant  methanogenic 
bacteria  between  psychrophilic  and  mesophilic.  Methane  emissions  are  also  affected  by  the 
wind turbulence, that removes CH4 from the lagoon surface and the atmospheric-boundary layer 
just above. 

The  solid  fraction  can  be used for landspreading; the  liquid  part  after  the  anaerobic  treatment 
may be directly applied to land, or, in a few cases, it may comply with local legal requirements 
for discharge into watercourses  [ 364, Portugal 2010 ]. Designs are country- and site-specific: 
for example, in Italy, covers are also used to collect biogas. 

2.7.6 

Manure additives 

Under the generic denomination of manure additives is a group of products made up of different 
compounds  that  interact  with  the  manure,  changing  its  characteristics  and  properties.  The 
following positive effects are claimed and are described to different degrees in the label of every 
product: 

1. 
2. 
3. 
4. 
5. 

a reduction in the emission of several gaseous compounds (NH3 and H2S); 
a reduction of unpleasant odours; 
a change in the physical properties of the manure to make its use easier;  
an increase in the fertilising value of the manure; 
a stabilisation of pathogenic microorganisms.  

Usually, items 1, 2 and 3 are the main reasons for their use at farm level. Below, the five groups 
of techniques are detailed. 

1. Additives for reducing the emission of several gaseous compounds. The decrease in gaseous 
emissions achieved through their use (mainly NH3 and H2S) is one of the most interesting yet 
controversial points. It has been well documented that up to 90 % of the N produced by pigs is 
in  the  form  of  urea.  When  the  urease  produced  by  faecal  microorganisms  comes  into  contact 
with urea, the following reaction occurs: 

CO(NH2)2 + 3 H2O  2 NH4 + HCO3

- + OH- 

coupled with the following equilibrium reaction NH3/NH4

+: 

NH3 + H2O  NH4

+ + OH- 

124 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

One  mole  of  urea  may  generate  two  moles  of  ammonia.  The  hydrolysis  of  urinary  nitrogen 
(urea)  to  ammonia  is  rapid.  Urea  spread  on  a  concrete  floor  starts  releasing  NH3  in  2–
2.5 minutes [ 277, Ji-Qin et al. 2000 ].  

This reaction is highly influenced by temperature and pH, for example, under 10 °C or at a pH 
below 6.5 the reaction stops. Acid addition to lower the pH and the addition of urease inhibitors 
to  prevent  the  hydrolysis  of  urea  both  offer  a  strategy  for  significant  control  of  ammonia 
emissions from livestock facilities, thus increasing the fertiliser value of slurry. 

2.  Additives  for  reducing  unpleasant  odours.  Several  types  of  additives,  with  different 
characteristics,  may  be  employed  for  reducing  odours  from  manure:  masking,  blocking, 
absorbing agents, microbiological agents, and chemical additives. 

Odour results from the mix of different compounds under anaerobic conditions. More than 200 
substances have been identified as causing odours, such as:  

 

 

 

 

 

volatile fatty acids; 

alcohols (indol, skatole, p-cresol, etc.); 

H2S and derivatives; 

ammonia; 

other N compounds (amines and mercaptans). 

A huge variation in the proportion and concentration of odour agents exists, depending on the 
type of farm, nutrition and nutritional management, and climatic conditions. This could explain 
why  the  effectiveness  of  these  compounds  against  odours  is  not  predictable  under  farm 
conditions. 

3. Additives for changing the physical properties of the manure. The objective of these additives 
is  to  make  the  manure  easier  to  handle  by  changing  the  physical  properties  of  the  manure, 
resulting in an increase in manure flow and the elimination of superficial crusts. In particular, 
these  additives  may  have  an  effect  on  the  dry  matter  content  and  viscosity  of  the  manure; 
however, these effects are not always found. 

Their application might make the cleaning of the manure pits easier, and thereby might shorten 
the cleaning time required and allow savings in water and energy consumption. Moreover, since 
the manure is more homogeneous, it facilitates the manure’s agricultural use (better dosing). 

4. Additives for increasing the fertilising value of the manure. As a consequence of the use of 
additives for reducing NH3 emissions (e.g. pH modification), higher levels of N are retained in 
the  manure.  In  other  cases,  through  an  increased  synthesis  of  the  microbial  cells  (use  of 
microbiological agents), higher levels of organic nitrogen are achieved.  

for  stabilising  pathogenic  microorganisms.  There  are  many  different 
5.  Additives 
microorganisms in manure, some of which contribute to the gaseous emissions and odours. It is 
also possible to find faecal coliforms and salmonella and other pig or poultry pathogens, viruses, 
eggs of flies and nematoda in the manure.  

Usually,  the  longer  the  storage  period,  the  higher  the  decrease  in  pathogens,  because  of  the 
different  requirements  of  temperature  and  pH.  The  pH  decreases  within  the  first  month  of 
storage (from 7.5 to 6.5 because of the microbial synthesis of volatile fatty acids) which has a 
negative  effect  on  pathogens  survival.  Some  of  the  manure  additives  have  been  designed  to 
especially control the eggs of flies. 

Intensive Rearing of Poultry or Pigs 

125 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Nowadays,  there  are  many  manure  additives  on  the  market,  with  different  characteristics  and 
purposes;  but  their  efficacy  has  not  been  demonstrated  in  every  case.  Information  concerning 
the performance and applicability of different additives is presented in Section 4.12.12.  

It  has  to  be  highlighted  that  in  many  cases  the  effects  on  human  or  animal  health  or  on  the 
environment  of  using  additives  are  not  known  and  this,  of  course,  limits  their  applicability 
[ 405, Tengman C.L. et al. 2001 ]. 

2.7.7 

Slurry acidification  

Acidification of slurry is a commonly used technique in a few countries (e.g. Denmark) with a 
high potential to reduce ammonia emissions. By adding acid (usually sulphuric acid), the pH of 
the  slurry  is  lowered  to  around  5.5,  and  thereby  the  ammonia  volatilisation  is  reduced  or 
inhibited. Nitrogen is retained in the manure in the form of ammonium and is available to crops 
when the manure is spread on the field. 

The technique can be applied in manure stores and/or animal houses using an automatic dosing 
system (see Section 4.12.9), but it is also possible to acidify the slurry in the tank immediately 
before  landspreading.  Another  alternative  is  to  continuously  acidify  it  in  a  system  directly 
mounted  on  the  slurry  spreader.  In  this  case,  the  acidified  slurry  is  spread  with  standard 
equipment (e.g. trail hoses) and an additional acid tank is placed in front of the tractor. 

126 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 2 

2.8  Manure landspreading techniques 

A range of equipment and techniques are used to spread slurry and solid manure to land. These 
are described in the following sections. Much of the manure was used to be landspread  using 
machinery  which  spreads manure  over  the  whole soil  surface ('broadcast')  by  throwing  it into 
the  air.  In  some  countries  (e.g.  the  Netherlands,  Denmark  and  Belgium-Flanders),  the  use  of 
band spreaders and injectors for slurry is required to reduce emissions. In many other countries, 
these techniques are also becoming increasingly popular. Solid manure is broadcast after being 
chopped or shredded into smaller pieces. Manure should be incorporated into soil by ploughing, 
discing or using other suitable cultivation equipment and, in some Member States, this is a legal 
requirement.  Contractors  are  often  used  for  manure  landspreading  and  manure  is  not  always 
spread on the producer’s own land. 

Directive  91/676/EEC,  the  Nitrates  Directive,  lays  down  minimum  provisions  on  the  manure 
landspreading,  with  the  aim  of  providing  all  waters  with  a  general  level  of  protection  against 
pollution  from  nitrogen  compounds,  and  additional  provisions  for  manure  landspreading  in 
designated Nitrate Vulnerable Zones. The measures include nitrogen content limits for manure, 
closed periods when some types of manure (high in available N) cannot be spread to grassland 
and  arable  land  (on  sandy  and  shallow  soils),  and  the  identification  of  other  situations  when 
manure should not be applied. In France for example, the dates for manure landspreading vary 
according to the C/N ratio i.e. type I with C/N > 8 (solid manure except poultry manure), or type 
II  (C/N  < 8  (solid  poultry  manure  and  slurry)  [  257,  France  2010 ].  In  other  countries  (i.e. 
Denmark),  nitrogen  quotas  for  each  farmer  have  been  introduced,  in  order  to  avoid 
unnecessarily high application levels of nitrogen per hectare of land. 

In  many  countries,  legislation  governing  the  manure  landspreading  aims  at  balancing  the 
amounts  of  manure  applied  with  the  nutrient  requirements  of  the  crop.  Indeed,  the  Nitrates 
Directive  is  based  on  this  approach,  by  requiring  action  programmes  and  codes  of  good 
agricultural  practice,  including  measures  for  regulating  the  periods  when  landspreading  is 
prohibited,  in  such  a  way  that  fertilisers  (including  manure)  are  spread  only  in  periods  when 
there is a crop available that can benefit from the nutrients applied to the field. Depending on 
legislation,  weather  conditions  and  field  crops  cultivated  in  different  regions  of  Europe,  there 
are  different  seasons  and  practices  applied  for  manure  landspreading.  In  other  countries  and 
areas, where landspreading is not controlled by specific legislation, spreading practices can rely 
upon published guidelines, such as codes of good practice.  

In a number of countries (e.g. Ireland, Sweden, Estonia, Finland, Germany, Belgium-Flanders, 
Denmark,  Lithuania,  Latvia  and  Poland),  the  phosphorus  load  is  used  as  a  limiting  factor  as 
well, either as a legal constraint or as a recommendation only. 

Ammonia volatilisation is reduced by using spreading machinery which decreases the exposed 
surface  area  of  manure  applied  to  the  surface  of  soil  or  burying  manure  through  injection  or 
incorporation into the soil. However, many factors influence the volatilisation of ammonia after 
landspreading of the manure. Abatement efficiencies will also vary depending on these factors.  

In  particular,  emissions  of  ammonia  as  a  percentage  of  TAN  applied  are  normally  decreased 
with  decreasing  air  temperature,  wind  speed,  solar  radiation  and  slurry  DM  content  
[ 508, TFRN 2014 ]. For example, an increase in wind speed of 1 m/s increases the ammonia 
loss by 10 % (expressed as percentage of TAN) [ 260, IGER 2001 ].  

In addition, emissions of ammonia as a percentage of TAN applied are normally decreased with 
increasing TAN concentration and application rate. Emissions from different manure types will 
also  vary.  Emissions  are  also  dependent  on  soil  conditions  that  affect  infiltration  rates.  For 
example, well-draining, coarse textured, dry soils, which allow faster infiltration, will give rise 
to  lower  emissions  than  wet  and  compact  soils  with  reduced  infiltration  rate.  However,  when 
very dry, some soils may become hydrophobic, which can also reduce infiltration and therefore 
increase emissions [ 508, TFRN 2014 ]. In addition, the decrease of the volatilisation rate with 

Intensive Rearing of Poultry or Pigs 

127 

 
 
 
 
 
 
 
 
Chapter 2 

time elapsed after application is significant for all application methods  [ 232, Huijsmans et al. 
2009 ]. 

The viscosity of slurry, which is determined by the content of organic particles, and its tendency 
to stick to the soil have an influence on ammonia volatilisation. A slurry with a high viscosity 
will increase NH3 emissions, by reducing the infiltration of liquid with dissolved TAN into the 
soil during landspreading. It has been observed for example that digested slurry penetrates the 
soil more easily and rapidly, not sticking to the surface as much as raw manure [ 517, Petersen 
et al. 2011 ].  

If  properly  applied,  manure  landspreading  has  benefits  in  terms  of  saving  mineral  fertiliser, 
improving soil conditions as a consequence of the addition of organic matter, and in reducing 
soil  erosion.  When  manure  is  not  properly  applied,  losses  of  the  applied  nutrients  occur  by 
volatilisation,  leaching  through  soil  layers,  running  through  to  field  drainage  systems  and  via 
run-off. Manure application techniques differ in the placement of the manure on the grass or the 
soil surface. As can be seen in Figure 2.30, the contamination of the vegetation and the exposed 
surface of the manure is different between application techniques. 

Source:[ 232, Huijsmans et al. 2009 ] 

Figure 2.30:  Placement  of  the  manure  when  applying  manure  with  different  application  and 

incorporation methods 

Energy  consumption  and  soil  compaction  related  to  the  spreading  equipment  can  also  be 
considered.  Landspreading  techniques  and  equipment,  which  are  detailed  in  the  following 
sections, vary depending on type of manure, land use and structure of the soil. 

128 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
2.8.1 

Slurry transport systems 

There  are  four  main  types  of  slurry  transport  systems  used  in  Europe  that  can  be  used  in 
combination with different slurry distribution systems. The features of these transport systems 
are set out in Table 2.21 and are discussed below. 

Chapter 2 

Table 2.21:  Qualitative comparison of four slurry transport systems  

Features 

Range of dry matter 
Requires separation or 
chopping 

Work rate 

Accuracy of 
application rate 

Soil compaction 

Capital costs 

Slurry tanker 
(vacuum) 
Up to 12 % 

No 

●●● 

● 

●●● 

● 

Transport system 

Slurry tanker 
(pumped) 
Up to 12 % 
No (centrifugal) 
Yes (PD pump) 

Umbilical hose 

Up to 8 % 
No (centrifugal) 
Yes (PD pump) 

●● 

●● 

●● (centrifugal) 
●●● (PD pump) 

●● (centrifugal) 
●●● (PD pump) 

●●● 

● (centrifugal) 
●● (PD pump) 

●● 

●●● 

Labour requirement 
per m3 
NB: Number of bullets (●) indicate input level or value, e.g. irrigator requires low labour input. 
Source: [ 390, ADAS 2001 ] 

●●● 

●●● 

●● 

Irrigation 
equipment 
Up to 3 % 

Yes 

●● (Depends on 

field size/shape) 

●● 

● 

●● 

● 

A slurry tanker can have a built-in tractor unit or can be built on a chassis with engine and cab 
for slurry transport in longer distances. When no there is independent motor unit in the tanker, a 
tow-bar exists for towing by a tractor.  

The slurry is sucked into the vacuum tanker by using an air pump to evacuate the air from the 
tank  to  create  a  vacuum;  the  tanker  is  emptied  using  the  air  pump  to  pressurise  the  tanker, 
thereby  forcing  the  slurry  out,  commonly  onto  a  splash  plate.  It  can  be  used  for  most  slurry 
transport and has a versatile applicability. 

Alternatively, the slurry can be pumped into and out of the tanker using a slurry pump, either a 
centrifugal (e.g. impeller-type) or positive displacement pump (PD pump), such as a lobe-type 
pump. Some tankers fitted with a centrifugal pump only pump  manure out and must be filled 
with  a  separate  pump.  The  pumped  tanker  generally  has  better  spreading  precision  (m3  or 
tonnes/ha) than vacuum tankers. PD pumps require more maintenance. 

In the case of an umbilical hose, the slurry is fed to the distribution system from a short-term 
stationary tank or directly from the store via a long flexible hose mounted directly on the rear of 
the  tractor.  The  hose  is  supplied  with  slurry  by  a  centrifugal  or  positive  displacement  pump. 
There is possible crop damage as the hose drags across the ground; hose damage and wear can 
especially be a problem on abrasive or flinty ground. The umbilical hose tends to be used where 
higher application rates are possible and on wetter soils where heavier machinery would mark 
the land (with increased potential for run-off). In general, the risk of soil damage by compaction 
caused by heavy slurry tankers is reduced. However, it is time-consuming to roll out hoses and 
roll them back in again. 

Slurry or waste water can also be transported through pipes, commonly underground, leading to 
a  length  of  flexible  pipe  on  the  surface  connected  to  an  irrigator  (see  Section  2.8.2.2).  The 
irrigator can be a self-propelled machine with flexible or reeled-in hoses, fed from a centrifugal 
or  positive  displacement  pump,  situated  near the  slurry  store.  It  is  suitable for  semi-automatic 
operation, but anti-pollution safeguards are needed (e.g. pressure and flow switches). Irrigators 
tend to be associated with high application rates. 

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Chapter 2 

2.8.2 

Slurry landspreading systems 

2.8.2.1 

Broadcast spreader 

Slurry  is  spread  over  the  whole  surface  of  an  area  of  land  or  crop.  The  broadcast  spreader  is 
often  considered  the  reference  system  when  comparing  techniques  for  reducing  ammonia 
emissions.  The  technique  is  rapid  and  inexpensive,  but  the  distribution  is  typically  uneven, 
especially in windy conditions, and the application of nutrients to the crops inconsistent, largely 
due to ammonia volatilisation. The use of broadcast spreading is restricted by the risk of crop 
quality deterioration or damage caused by slurry contamination. The diffusion of odours and the 
risk  of  pathogen  spreading  with  drifting  droplets  are  other  drawbacks  of  this  technique. 
Broadcast spreaders are not authorised in many countries (e.g. in Denmark and in Ireland where 
an upward facing splash plate is not permitted). 

With  broadcast  spreaders,  ammonia  losses  after  application  are  reported  to  be  in  the  range  of 
40–60 % of the total ammoniacal nitrogen applied (TAN), although emissions outside this range 
are also common [ 508, TFRN 2014 ]. Ammonia losses are greater from broadcasting slurry on 
stubble  than  on  bare  soil,  particularly  if  the  slurry  has  a  high  dry  matter  content,  because  of 
increased exposure to the air and a reduced infiltration rate. 

The  combination  of  a  tractor  with  a  tank  with  a  broadcast  spreader  at  the  rear  in  shown  in 
Figure 2.31. The untreated slurry is forced under pressure through a discharge nozzle, often onto 
an inclined plate (i.e. a splash plate) to increase the area over which it is distributed.  

Source: [ 390, ADAS 2001 ] 

Figure 2.31:  Example of a broadcast spreader with a splash plate 

Figure 2.32 shows a hose-reel irrigator with a ‘raingun’ attached to a moveable trolley, which is 
also a broadcast spreader. The trolley is pulled out to about 300 metres with its supply pipe and 
is wound back to the reel (using the supply hose) where it automatically shuts off. Dilute slurry 
is pumped to the hose-reel from the slurry lagoon via a main pipe  – often buried underground 
and with valved outlets in a number of places in the field. The applicator in this picture is the 
‘raingun’ that operates at a high connection pressure [ 408, UK 2002 ].  

130 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source:[ 408, UK 2002 ] 

Figure 2.32:  Example of a raingun  

Broadcasting can also be operated by low trajectory machines, which discharge at a relatively 
low angle to the land, and at a low pressure to produce large droplets, to avoid atomisation and 
wind  drift.  Figure 2.33  shows  a  tractor  applying  dilute  pig  slurry  through  a  boom  with  two 
splash  plates  to  a  crop  of  winter  wheat.  The  slurry  is  supplied  to  the  tractor/boom  using  an 
umbilical hose from the slurry lagoon.  

Source:[ 408, UK 2002 ] 

Figure 2.33:  Example of a broadcast technique with low trajectory and low pressure  

Intensive Rearing of Poultry or Pigs 

131 

 
 
 
 
 
 
 
Chapter 2 

Figure 2.34 shows the same type of boom applicator with two splash plates, but this time on the 
back of a tractor and tanker combination. Slurry is supplied from the tanker and is spread, again, 
with a low trajectory and at low pressure. 

Source: [ 408, UK 2002 ] 

Figure 2.34:  Example of a broadcast technique with low trajectory and low pressure 

2.8.2.2 

Irrigators 

Irrigators are devices for slurry or waste water landspreading. There are static irrigators such as 
sprinklers and rainguns that have to be moved manually to apply slurry to different parts of the 
field, and mobile  (or travelling) irrigators that are  self-propelled and normally travel in preset 
lines across the field.  For both types, the liquid is forced through nozzles that are designed to 
rotate or oscillate to distribute the liquid as relatively small droplets over a wide area. Travelling 
systems  can  be  equipped  with  a  specifically  designed  application  boom.  Irrigation  is  suitable 
only for slurries that can be pumped through long lengths of pipe and discharged through small 
nozzles without causing blockages.  

Low-pressure  irrigators  (e.g.  sprinklers)  are  designed  for  applying  irrigation  water  to  crops  at 
low  pressures  and  flow  rates.  Rainguns,  usually  fed  by  a  hose,  are  devices  for  applying 
irrigation water to crops at very high pressures in order to shoot the liquid over relatively long 
distances. Systems with pressures higher than 2 bar at the hose are prohibited in some Member 
States, as they can generate aerosols that are potential sources of microbiological contamination.  

Dilute  slurry  or  the  liquid  fraction  from  mechanical  separation  (less  than  2 %  dry  matter 
content)  can  be  landspread  by  irrigation  systems,  including  rainguns,  boom-mounted  splash 
plates  and  rotary  boom  systems.  The  rear  and  side  views  of  a  mobile  irrigation  system, 
consisting of a horizontal boom with splash plates, are shown in Figure 2.35 and Figure 2.36.  

132 

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Chapter 2 

Source: [ 247, IGER 2003 ] 

Figure 2.35:  Rear view of a horizontal boom with splash plate for slurry application  

Source: [ 247, IGER 2003 ] 

Figure 2.36:  Side view of a horizontal boom with splash plate for slurry application 

2.8.2.3 

Low-pressure irrigator 

The  system  is  based  on  the  use  of  controlled  amounts  of  slurry  or  liquid  fraction  from 
mechanical separation of slurry  which are mixed with irrigation  water and are distributed at a 
low pressure by irrigation systems such as pivots or sprinklers. These systems are widely used. 
More information is reported in Section 4.13.4.2.1, including a picture of a typical irrigator (see 
Figure 4.95) [ 242, CRPA 2009 ]. 

2.8.2.4 

Band spreader (or trailing hose) 

Band  spreading is commonly  referred  to  as  'trailing hose',  but it  is  also  known  as ‘drag  hose’ 
and 'drop hose'. Band spreaders are machines for the application of slurry to the land surface in 
parallel bands with no slurry applied between the bands. Band spreaders discharge slurry at or 
just above ground level in strips or bands through a series of hanging or trailing pipes attached 

Intensive Rearing of Poultry or Pigs 

133 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

to  a  boom.  The  band  spreader  is  fed  with  slurry  from  a  single  pipe,  and  thus  relies  on  the 
pressure  at  each  of  the  hose  outlets  to  provide  an  even  distribution.  Most  systems  use  rotary 
distributors to supply the slurry evenly to each outlet. The width is typically 12–28 m with about 
30–50 cm between bands (see Figure 2.37). Band spreading systems are normally fitted to the 
rear of slurry tankers but they can also be mounted at the rear of a tractor (umbilical system).  

The technique is applicable to grass and arable land, e.g. for applying slurry between rows of 
growing crops. Band spreading applies manure more uniformly than  broadcasting and enables 
higher yields [ 254, Webb J.M. et al. 2009 ]. 

Source: [ 562, MARM 2011 ] 

Figure 2.37:  Example  of  a  band  spreader  fitted  with  rotary  distributor  to  improve  lateral 

distribution 

2.8.2.5 

Trailing shoe spreader 

This  is  a  similar  configuration  to  the  band  spreader  with  a  'shoe'  device  added  to  each  hose 
designed to part crop or grass leaves and stems and deposit the slurry in bands under the crop 
canopy on the soil surface. It is also known as 'drag shoe' and 'sleighfoot'. 

This technique is mainly applicable to grassland. Grass blades and stems are parted by trailing a 
narrow shoe or foot over the soil surface and slurry is placed in narrow bands on the soil surface 
at  16–35  cm  intervals,  therefore  contamination  of  the  foliage  is  minimised.  The  slurry  bands 
should be covered by the grass canopy so the grass height should be a minimum of 8 cm. The 
machines are available in a range of widths up to 6–16 m [ 575, UBA Germany 2011 ].  

2.8.2.6 

Injector (open slot) 

Slurry is placed in slots cut into the soil to various depths depending on the type of injector. The 
slots cut in the soil are left open after filling with slurry. There are various types of injectors but 
each falls into one of two categories; either open slot shallow injection, up to 50 mm deep; or 
deep injection, typically about 150 mm deep. These normally comprise an array of injector units 
mounted on a tanker or at the rear of a tractor (umbilical system). Slurry is normally fed from 

134 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

the tanker or umbilical hose system to a rotary distributor that serves to chop and homogenise 
the manure and to supply it evenly to hoses attached to each injection unit.  

Open  slot  injectors  are  mainly  for  use  on  grassland,  especially  on  relatively  short  grass,  e.g. 
after cutting or grazing. Different shaped knives or disc coulters are used to cut vertical slots in 
the soil up to 5–6 cm deep into which slurry is placed (Figure 2.38). The spacing between the 
slots  is  typically  20–30 cm,  with  a  typical  working  width  of  6  m  that  can  reach  9–12 m.  The 
application rate must be adjusted so that excessive amounts of slurry do not spill out of the open 
slots onto the soil surface.  

Source: [ 563, MARM 2011 ] 

Figure 2.38:  Example of an open slot injector 

2.8.2.7 

Injector (closed slot) 

Slurry is landspread by placement in deep, vertical slots, cut into the soil by specially designed 
tines.  This  technique  can  be  shallow  (5–10  cm  depth)  or  deep  (generally  10–15 cm,  or  up  to 
20 cm).  Slurry  is  fully  covered  after  injection  by  closing  up  the  slots  with  press  wheels  or 
rollers, possibly fitted behind the injection tines. Shallow closed slot injection is more efficient 
than  open  slot  for  decreasing  ammonia  emissions.  To  obtain  this  added  benefit,  soil  type  and 
conditions must allow for effective closure of the slot. The technique is, therefore, less widely 
applicable than open slot injection. 

Deep  injection  can  be  used  effectively  to  spread  high  quantities  of  slurry  at  one  time.  Deep 
injectors usually comprise a series of tines, potentially fitted with lateral wings or ‘goose feet’, 
to  aid  lateral  dispersion  of  slurry  in  the  soil,  so  that  relatively  high  application  rates  can  be 
achieved. Tine spacing is typically 20–40 cm, and the working width 3–6 m although it can be 
up to 12 m. Although ammonia abatement efficiency is high, the applicability of the technique 
is  severely  limited.  The  use  of  deep  injection  is  restricted  mainly  to  arable  land  because 

Intensive Rearing of Poultry or Pigs 

135 

 
 
 
 
 
 
 
 
 
Chapter 2 

mechanical  damage  may  decrease  herbage  yields  on  grassland.  Other  limitations  include  soil 
depth  and  the  clay  and  stone  content,  the  slope,  and  a  high  draught  force  requiring  a  large 
tractor.  Also,  in  some  circumstances  there  is  a  greater  risk  of  nitrogen  losses  as  nitrous  oxide 
and nitrates. However, the technique is widely used in some Member States. A variation of the 
technique  rarely  used  is  the  direct  ground  injection  system;  this  forces finely  separated  slurry 
under pressure into the soil with little soil disturbance.  

2.8.3 

Solid manure landspreading systems 

For landspreading of solid manure, three main types of spreaders are commonly used: 

 

Rotaspreader (see Figure 2.39): a side discharge spreader which features a rotating shaft 
fitted with spinning flails running along its length. As the rotor spins, the flails throw the 
solid manure out to the side. 

Source: [ 390, ADAS 2001 ] 

Figure 2.39:  Example of a rotaspreader 

 

Rear discharge spreader (see Figure 2.40): a trailer body fitted with a moving floor or a 
conveyor  which  delivers  solid  manure  to  the  rear  of  the  spreader.  The  spreading 
mechanism  can  have  either  vertical  or  horizontal  rotating  beaters,  spinning  discs  or  a 
combination of beaters and spinning discs. 

Source: [ 390, ADAS 2001 ] 

Figure 2.40:  Example of a rear discharge spreader 

136 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Dual-purpose  spreader:  a  side  discharge  spreader  with  an  open-top  V-shaped  body 
capable  of  handling  both  slurry  and  solid  manure.  Fast-spinning  impellers  or  blades, 
usually at the front of the spreader, throw manure from the side of the machine. The rotor 
is  fed  with  material  by  an  auger  or  a  conveyor  fitted  in  the  base  of  the  spreader.  The 
spreader can be adjusted to spread either slurry or solid manure, usually through varying 
the  aperture  of  the  outlet  adjacent  to  the  distributor  mechanism  (e.g.  a  sliding  gate 
controls the flow rate of the manure onto the rotor) (see Figure 2.41).  

Chapter 2 

Source: [ 390, ADAS 2001 ] 

Figure 2.41:  Example of a dual-purpose spreader 

A quality comparison of the characteristics of solid manure spreaders is presented in Table 2.22. 

Table 2.22:  Comparison of solid manure spreading systems 

Features 

Rotaspreader 

Spreading system 
Rear discharge 
spreader 

Dual-purpose 
spreader 

Suitability for slurry 

Work rate 

Accuracy of application rate 

Lateral precision 

Soil compaction 

Ease of determining 
overlapping of adjacent runs 

Relative costs 

No 

●●● 

● 

● 

●●● 

● 

● 

No 

●●● 

●●● 

●●● 

●●● 

●●● 

●● 

Yes 

●●● 

●● 

●● 

●●● 

●● 

●●● 

NB: Number of bullets (●) indicates the input level or value, e.g. rotaspreader has a low accuracy of 

application rate. 

Source: [ 390, ADAS 2001 ] 

Spreaders with a narrow tank-case are most often used, allowing the use of wheels of a large 
diameter  that  need  limited  traction  power.  High-capacity  spreaders  are  equipped  with  large 
tanks. Regular spreading and relatively low soil compression are possible using spreaders with a 
double axle. Spreading devices used are mainly vertical drums (see Figure 2.42) and deflector 
plates;  the  old  spreaders  with  two  horizontal  drums  are  not  favoured  because  of  the  low 
spraying width. 

Intensive Rearing of Poultry or Pigs 

137 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

Source: [ 257, France 2010 ] 

Figure 2.42:  Vertical drum manure spreader 

Vertical  drums  are  suitable  for  solid  manure  with  more  than  400 kg/m3.  Drums  of  a  large 
diameter are preferred. The spraying width is 6–12 metres. Drums are mechanically simple and 
require relatively low power.  

Deflector plates with horizontal drums have a more general purpose, being more suited to lower 
density solid manure. The spraying width is wider, from 10 to 12 metres and adjustable shutters 
optimise  the  transverse  distribution  for  an  achievable  load  of  4–6 tonnes  of  solid  manure  per 
hectare. Some models allow discs to be tilted to provide an even spread right up to the spreading 
boundary, in the same way as fertiliser spreaders do. Spreading is successful if three conditions 
are met [ 257, France 2010]: 

 

 

 

the manure to spread is suitable for the equipment to be used; 

the mass is well homogenised before it is loaded on the spreader; 

the equipment is adjusted so that manure is evenly spread to the desired amount. 

An  accurate  application  of  nutrients  demands  a  uniform  spread  pattern.  The  coefficient  of 
variation for a machine's spread pattern is a measure of the uniformity of spread achieved, both 
laterally and longitudinally. A high number indicates a poor uniformity. Research suggests that 
manure spreaders should be chosen and operated to give a coefficient of variation of less than 
25 % [ 390, ADAS 2001 ]. 

2.8.4 

Incorporation 

After  landspreading,  manure  is  mixed  into  the  soil  or  buried  using  appropriate  cultivation 
machinery. Incorporation may be achieved with a plough or other types of equipment such as 
discs  or  cultivators,  depending  on  the  soil  type  and  soil  conditions.  Incorporating  the  manure 
spread on the surface into the soil is an efficient means of decreasing ammonia emissions. The 
manure must be completely buried under the soil to achieve maximum efficiency.  

As  ammonia  losses  take  place  quickly,  higher  reductions  in  emissions  are  achieved  when 
incorporation takes place immediately after landspreading. At the same time incorporation will 
reduce the development of odour in the vicinity of the manure-covered land.  

Efficiencies  depend  on  the  cultivation  machinery;  ploughing  is  mainly  applicable  to  solid 
manure  on  arable  soils.  Ploughs  are  more  efficient  but  much  slower  than  rotor  harrows; 
therefore,  manure remains uncovered  on the  soil  for a  longer time,  with  consequent  ammonia 

138 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
emissions. For this reason, the overall effect may be that ploughing is less efficient than other 
incorporation techniques.  

Where injection techniques for slurry are not possible or unavailable, incorporation may also be 
carried out after slurry spreading, by means of conventional soil cultivation equipment.  

Chapter 2 

Intensive Rearing of Poultry or Pigs 

139 

 
 
 
 
 
Chapter 2 

2.9  On-farm transport 

The  scale  of  transport  operations  on  farms  depends  on  the  farm  size,  farm  layout  and  the 
location  of  fuel  storage  areas,  feed  stores  and  feed  processing,  livestock  buildings,  product 
processing  (for  example  egg  packing  and  grading),  manure  storage,  and  fields  for  applying 
manure to land. 

Feed is usually mechanically or pneumatically handled, and in pig units using wet feed, feed is 
pumped to feeding troughs. 

Typically, tractors are used as the prime means of manure transport and landspreading, although 
in  some  pig  units,  slurry  irrigation  using  pumps  and  pipelines  is  practised.  Many  farmers  use 
contractors  who  typically  possess  larger  equipment  and  occasionally  self-propelled  vehicles 
with mounted ‘spreader’ bodies. Tractor-mounted slurry scrapers or loaders/grabs are used for 
moving manure around buildings and concrete areas, but in some egg-laying systems manure is 
moved mechanically by belts and conveyors. 

Eggs  are  usually  mechanically  handled  through  to  packing,  where  forklift  trucks  assist  the 
loading  of  lorries  for  road transport.  Forklifts  are  also  used to  transfer  crates containing  birds 
from broiler housing to road transport vehicles. 

Material handlers (a specialist form of tractor) are used on some sites to undertake a variety of 
tasks around the farm buildings. The movement of road transport lorries around the farm can be 
extensive  in  large  integrated  egg  production  enterprises  dealing  with  production  output  and 
inputs such as birds, feed, fuel, and packaging. Some sites carry out egg grading and packing for 
other producers. 

140 

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Chapter 2 

2.10  Maintenance and cleaning 

Maintenance  and  cleaning  primarily  relate  to  equipment  and  housing.  Paved  areas  of  the 
farmyard  can  also  be  cleaned  by  sweeping  or  by  spraying  with  water.  In  the  UK  and  Spain, 
farmers  report  that  modern  building  materials  are  easier to  clean  than  older  ones,  resulting  in 
water and labour savings. 

General  building  maintenance  is  necessary,  including  feed  handling  systems  and  other 
conveying  equipment.  Ventilation  systems  are  checked  for  the  correct  operation  of  fans, 
sensors,  temperature  controllers,  outlets  and  back-draught  shutters  and  emergency  provisions. 
Drinking  water  supply  equipment  is  checked  regularly.  The  provision  and  maintenance  of 
appropriate  conditions  for  keeping  livestock  are  required  to  meet  welfare  legislation  and  to 
reduce emissions of odour. 

Regular  maintenance  (refurbishing  and  repairs)  and  cleaning  of  vehicles,  such  as  tractors  and 
manure spreaders, also takes place. Regular checks should be made during operational periods, 
also  with  appropriate  maintenance  as  described  in  the  manufacturers’  instructions.  These 
activities  usually  involve  the  use  of  oil  and  cleaning  agents  and  can  require  energy  for 
equipment use. 

Many farms have a supply of faster wearing parts in order to carry out repairs and maintenance 
quickly.  Routine  maintenance  and  cleaning  are  carried  out  by  suitably  trained  farm  staff,  but 
more difficult or specialist maintenance work is carried out with specialist assistance. 

Buildings are usually cleaned and disinfected after batches of livestock and manure have been 
removed.  As  a  minimum,  the  frequency  of  cleaning  is  therefore  equal  to  the  number  of 
production cycles per year.  

Typically  in  pig  units,  wash-down  water  enters  the  slurry  system,  but  in  poultry  units  such 
contaminated  water  is  often  collected  separately  in  (underground)  storage  tanks,  before 
landspreading or treatment. Good hygiene practices are required in other building areas where 
products are handled and packed ready for dispatch. 

For  cleaning,  use is  often made  of  high-pressure  washers  using  only  water,  but surface-active 
agents are sometimes added. For disinfecting, disinfection agents are applied with an atomiser 
or sprayer. Disinfection is not a procedure normally applied, and is usually only carried out in 
the  case  of  disease  outbreaks  (e.g.  salmonella),  and  also  as  a  prevention  measure  in  order  to 
avoid them. 

Intensive Rearing of Poultry or Pigs 

141 

 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.11  Use and disposal of residues 

The  operation  of  a  pig  or  poultry  farm  gives  rise  to  a  number  of  different  residues,  some  of 
which are identified in the following list: 

 

 

 

 

 

 

 

 

 

 

wood; 

pesticides; 

veterinary  products  and  wastes,  whose  collection  and  specialised  disposal  is  primarily 
used  in  order  to  prevent  inappropriate  use  of  needles,  syringes  and  products  as  well  as 
minimising infection risks; 

vehicle and machinery waste, such as tyres, oils and lubricants; 

scrap metals; 

packaging (rigid plastic, film plastic, cardboard, paper, glass, pallets, etc.); 

feed wastes (spilt or spoilt feeds); 

building wastes (cement, asbestos and metal); 

waste from electrical and electronic equipment (e.g. fluorescent tubes); 

waste from diagnosis, treatment or prevention of disease (e.g. sharps), whose collection 
and disposal is subject to special requirements in order to prevent infection. 

The processing of manure, carcasses and waste water is subject to special provisions and is dealt 
with in Section 2.8, Section 2.12 and Section 2.13 respectively.  

Most  of  the  residues  are  paper  and  plastic  packaging  material.  The  most  common  hazardous 
residues are those from medicines that have been used or that are past their expiry date. Small 
amounts of residues of cleaning material or of chemicals necessary to operate special processes 
(e.g. air scrubber) may be found on a farm as well. 

In general, in larger farms, residues can be more economically disposed of than on small farms. 
For collection, the residues are stored in containers or in small bins and collected by municipal 
or  special  collection  services.  Where  no  public  waste  collection  is  organised,  farms  may  be 
obliged to organise collection and transportation themselves and are responsible for associated 
costs and treatment (e.g. in Finland). Collection is difficult to organise in remote areas. 

Off-farm waste handling includes disposal or treatment routes such as: 

 

 

 

 

 

landfilling; 

storage in dustbins, including in household collection; 

collection by suppliers; 

transferal to contractor; 

recovery or treatment of waste (e.g. oil recovery). 

Oils  are  stored  in  purpose-designed  cans/containers  and  are  collected  to  be  treated  off  farm. 
Veterinary  residues  are  stored  in  special  boxes  and  sometimes  collected  by  the  veterinary 
service or by licensed operators offering waste disposal services.  

Plant waste residues, like feed and crop waste residues, can be mixed with farmyard manure or 
slurry  and  landspread,  or  are  reused  in  other  ways.  Tyres  are  dealt  with  in  different  ways, 
varying  between  collection  by  suppliers,  stockpiling,  use  in  construction  as  tyre  bales,  use  in 
silage  as  clamps,  or  use  as  crash  barriers.  In  general,  waste  management  (storage,  transport, 
disposal or treatment) needs to be carried out in compliance with the provisions of the  Waste 
Framework Directive (2008/98/EC).  

142 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.12  Storage and disposal of dead animals  

The  procedures  for  the  collection,  storage  and  disposal  of  dead  animals  and  carcasses  are 
prescribed  by  Regulation  (EC)  1069/2009  of  21  October  2009  and  its  corresponding 
implementing  Regulation  (EC)  142/2011  of  25  February  2011,  laying  down  health  rules 
regarding animal by-products and derived products not intended for human consumption, which 
repealed  Regulation  (EC)  No  1774/2002  (Animal  by-products  Regulation).  In  particular, 
Regulation (EC)1069/2009 classifies on-farm dead pigs and poultry as Category 2 material, in 
accordance with Article 9, and specifies all the necessary conditions to ensure that management 
of dead animals is carried out properly, in authorised dedicated plants, in order to prevent the 
possible spread of pathogens. 

According to Article 13 of Regulation 1069/2009, possible disposal procedures for Category 2 
material are: 

 

 

 

 

 

 

disposal as waste by incineration or co-incineration; 

disposal  in  an  authorised  landfill,  following  processing  by  pressure  sterilisation  and 
permanent marking of the resulting material; 

used  for  the  manufacturing  of  organic  fertilisers  or  soil  improvers  to  be  placed  on  the 
market in accordance with Article 32 following processing by pressure sterilisation, when 
applicable, and permanent marking of the resulting material; 

composted or transformed into biogas following processing by pressure sterilisation and 
permanent marking of the resulting material; 

used as a fuel for combustion with or without prior processing;  

used  for  the  manufacture  of  derived  products  referred  to  in  Articles  33,  34  and  36  and 
placed on the market in accordance with those Articles. 

Some farms have an installation for incineration of dead animals. On-farm incinerators for the 
disposal of fallen stock which incinerate only animal carcasses are exempted from Chapter IV 
and Annex VI of the Industrial Emissions Directive (2010/75/EU) and are instead regulated by 
Regulation (EC) 1069/2009. Specifically, they must be approved in accordance with Article 24 
of  Regulation  (EC)  1069/2009  and  must  comply  with  Article  6  and  Annex  III  of  Regulation 
(EC)  142/2011,  in  particular  concerning  hygiene  conditions,  operating  conditions,  residue 
disposal  requirements,  temperature  measurement  requirements  and  requirements  for  dealing 
with abnormal operating conditions. In addition, specific requirements for operating conditions 
and water discharges are set out for high and low capacity plants. 

Small-scale  incinerators  (< 50 kg/hr)  are operated  in the  UK,  mainly  on  large  poultry  and  pig 
farms  for  the  incineration  of  animal  carcasses.  Strict  controls  apply  to  their  use,  including  a 
periodic  inspection  and  monitoring  regime.  The  ash  may  be  landfilled,  disposed  of  by  other 
routes, or recycled, as ashes have a high phosphorus content.  

Only animal by-products, including dead animals, originating in remote areas and under specific 
conditions and circumstances may be disposed of as waste by burning or burial on farm under 
official  supervision,  according  to  Article  19  of  Regulation  (EC)  1069/2009.  Several  Member 
States  have  already  granted  derogations  in  regard  to  the  possibility  to  dispose  of  animal  by-
products as waste by burial or burning in remote areas [ 492, DG SANCO 2005 ]. A remote area 
is defined as an area where the animal population is so small, and where disposal establishments 
or  plants  are  so  far  away  that  the  arrangements  necessary  for  the  collection  and  transport  of 
animal by-products would be unacceptably onerous compared to local disposal.  

Burial  and  burning  of  animal  by-products  may  also  be  justified  in  disease  control  situations 
requiring the emergency disposal of the animals killed as a measure to control an outbreak of a 
serious  transmissible  disease.  In  particular,  disposal  on  farm  should  be  allowed  under  special 
circumstances, since the available rendering or incinerator capacity within a region or a Member 
State could otherwise be a limiting factor in the control of a disease. 

Intensive Rearing of Poultry or Pigs 

143 

 
 
 
 
 
 
 
 
Chapter 2 

2.13  Treatment of waste water 

Waste water is a general term for water contaminated with faeces, urine, chemicals etc. and so 
posing a risk of pollution but of little value as a fertiliser. Waste water, also called dirty water, 
originates  from  washing  livestock  houses  and  equipment,  from  facilities  for  personnel,  and 
particularly from run-off from yards and open concrete areas that are contaminated by manure, 
waste animal feed, etc. Cleaning water from livestock farming facilities can contain residues of 
dung and urine, litter, and feedstuffs, as well as cleaning agents and disinfectants. 

Waste water can be managed in combination with slurry, but can also be treated and handled 
separately, in which case separate storage will be needed. On poultry farms, the aim is to keep 
manure dry to reduce ammonia emissions and to allow easier handling. Waste water is stored in 
special tanks  and  dealt  with  separately.  On  pig  farms,  waste  water  is  commonly  added  to  the 
slurry  and  treated  in  combination  or  applied  directly  to  land.  Various  treatment  systems  for 
slurry exist and they are described in Section 2.7.  

If kept separate, waste water may be landspread through low-rate irrigators (e.g. in the UK) or 
treated in a common or on-farm waste water treatment plant (e.g. sedimentation treatment is a 
minimum for waste water arising from solid manure systems in Finland).  

For  discharge  into  running  waters  or  a  public  sewage  system,  waste  water  from  intensive 
livestock  farming  must  comply  with  emission  limits  stipulated  under  water  regulations  [  373, 
UBA Austria 2009 ].  

Constructed  wetlands  with  reedbeds  are  aquatic  plant-based  systems  designed  specifically  for 
the removal of nitrogen from dilute waste water as it passes through the vegetative filter. Some 
of these solutions may have limited effectiveness (with water of variable quality) or may have a 
limited  lifetime.  They  are  relatively  inexpensive  to  construct  but  may  require  a  large  area  of 
land  to  provide  an  adequate  level  of  treatment  [  203,  ADAS  2005  ].  Their  construction  and 
operation and the discharges to groundwater and surface have to be authorised and assessed.  

Swales are ideal for collecting and transporting run-off but require large space. Ponds remove 
part of the sediment with a partial treatment. Soakaways need practically no care, but must not 
be used where there is a high level of contaminants. 

144 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.14 

Installations for heat and power production and energy 
recovery 

2.14.1 

Renewable energy production 

Renewable  energy  production  on  farm  can  contribute  to  the  reduction  of  the  energy  costs  by 
covering  part  of  the  energy  requirements  of  the  farm  and/or  selling  the  produced  energy  to 
supply networks.  

Solar or wind-driven generators are more frequently installed. Solar power supply depends very 
much  on  the  weather  conditions,  while  windmills  attached  to  a  generator  can  supply  power, 
particularly in areas with relatively high wind speeds. 

Electricity production from photovoltaic panels is possible in pig and poultry farms as large roof 
surfaces are available on houses. In addition, roof slopes (26–45 %) allow a good efficiency of 
the  system.  Government 
in  many  
EU Member States, have reduced payback times of the investment in solar energy production to 
5–10 years. Costs for photovoltaic panels are falling rapidly. Costs of about EUR 2 500 per kW 
or EUR 450–600 per m2 were reported in 2013.  

'Feed-In  Tariffs'  applied 

incentives,  such  as 

The installation of small wind turbines is also becoming more convenient: for sizes up to 12 m 
in  height,  costs  are  around  EUR 500/kW;  while  for  capacities  of  10–50 kW  and  15–30  m  in 
height, costs are reported to be around EUR 3 500 per kW. In France, contracts for the purchase 
of wind power electricity are established for 15 years. 

2.14.2 

Heat recovery by heat exchangers 

Several solutions for the recovery of energy from various media are available, which use heat 
exchangers based on three major principles: 

 

 

 

air-air heat exchangers; 

air-water heat exchangers; 

air-ground heat exchangers. 

Air-air exchange. The principle consists of warming up the air that enters the house using the 
heat of the exhaust air. The heat is transferred through plates that separate the flows that enter 
and exit the house.  

Air-water  exchange.  The  exhaust  air  warms  water  circulating  in  aluminium  fins  placed  in the 
extraction shaft. Recovered heat is returned indoors by a fan-convector. Electric consumption is 
only needed for the pump, which ensures the circulation of the water. The maximum recorded 
effect is an increase of 12 °C of the incoming air. 

Air-ground  exchange.  The  exchangers  use  the  inertia  of  the  ground  to  smooth  the  seasonal 
variations of temperatures and, consequently, to improve the conditions of thermal comfort of 
the  animals.  They  are  used  to  preheat  the  air  in  winter  as  well  as  to  cool  it  in  summer  
[ 347, Bartolomeu 2007 ].  

Intensive Rearing of Poultry or Pigs 

145 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 2 

2.14.3 

Heat pumps 

A heat pump is a device that transports heat from one location at a lower temperature to another 
location (the 'heat sink') at a higher temperature using mechanical work. When a heat pump is 
used for heating, it employs the basic refrigeration cycle but in the opposite direction, releasing 
heat into the conditioned space rather than the surrounding environment. In this use, heat pumps 
generally draw heat from the cooler external air, water or from the ground.  

Heat  pumps  use  a  refrigerant  liquid  as  an  intermediate  fluid  to  efficiently  transfer  heat  at 
relatively long distances. In heating mode, the refrigerant flowing through insulated pipes from 
the evaporator, where it vaporises, carries the thermal energy absorbed (from air, water or soil) 
indoors into the animal house, after the fluid's temperature has been augmented by compressing 
it. The condenser, where the refrigerant condenses, then transfers  heat (including energy from 
the compression) to the indoor air or water in the animal house for example. The refrigerant is 
then allowed to cool and to expand and the cycle  restarts by collecting heat in the evaporator 
(Figure 2.43). 

The  recovered  heat  can  be  used  to  produce  sanitary  warm  water  or  to  feed  a  heating  circuit 
(warm water buckles, underfloor heating or fan convectors) in the animal house. 

Source: [ 348, Bartolomeu 2008 ] 

Figure 2.43:  Operating principle of a heat pump 

2.14.4 

Biogas energy production 

In  the  intensive  livestock  production  sector,  the  potential  for  biogas  production  by  anaerobic 
digestion can be important at farm level although slurry has a relatively low energy content and 
generally  needs  to  be  supplemented  with  high-energy  feedstocks  like  energy  plants,  green 
wastes  and  silage  maize.  Poultry  manure  can also  be digested  with  pig  slurry  as  a  part  of the 
substrate.  

Anaerobic digestion (see Section 2.7.4) is a process of degradation of the organic matter without 
oxygen that leads to the production of biogas (mainly constituting of methane). Biogas can be 
used  as  fuel  by  a  co-generator  (CHP)  plant  to  produce  electricity  to  sell  it  to  the  commercial 
network and to produce heat which can cover part of the heating needs of the farm, such as for 
animal houses, greenhouses and piglet heating [ 345, France 2010 ]. The heat produced by CHP 
plants can also be transferred to external users by district heating for residential and commercial 
heating requirements. 

After  a  first  wave  of  digesters  that  were  built  in  the  1980s  and  1990s  had  little  real  success, 
anaerobic  treatment  is  in  a  new  phase  of  development  in  Europe,  especially  due  to  attractive 
prices provided for the energy produced, which is classified as renewable. The profitability of 

146 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
the  process depends  on  the  production  capacity  and  on  the  sale  price  of  the  electric  power  as 
well as from the valorisation of the heat produced. Different grants and incentives are in place in 
various  Member  States,  which  are  taken  into  account  in  the  economic  evaluation  of  these 
production systems. 

Chapter 2 

2.14.5 

Energy production from biomass 

Heat production using biomass (or wood) firing requires a whole infrastructure to benefit from 
the heat produced. These requirements, which normally are not present in existing farms, consist 
of the heating network, hot air blowers or heating floors or fins.  

Boilers  must  be  installed  close  to  buildings  because  the  heat  distribution  piping  network  is 
relatively  expensive.  However,  biomass  fuel  costs  generally  offer  substantial  savings  over 
imported fossil fuels, once the capital has been invested. 

This heating system is profitable when the heat needs are large and stable, as  is the case  with 
multiple  houses  or  users.  Some  examples  of  heat  requirements  for  different  size  farms  and 
animal categories are reported in Table 4.42. 

Intensive Rearing of Poultry or Pigs 

147 

 
 
 
 
 
 
 
 
 
Chapter 2 

2.15  Monitoring of emissions and control of process 

parameters 

This section gives some examples of common practice in monitoring of emissions and control 
of process parameters. In most cases, farmers do not normally monitor and control emissions to 
air  unless  specifically  required  to  do  so  as  a  result  of  complaints  from  neighbours.  These 
complaints are usually related to noise and odour emissions.  

In some areas, farmers have to keep a register of phosphate and nitrogen flow. This is usually 
where intensive livestock production is responsible for high pressures on the environment. The 
resulting balance gives a clearer indication of the input and losses of nutrients on the farm. The 
information  can  be  used  to  optimise  the  feeding  of  nutrients  to  the  animals  and  the 
landspreading. Some farmers assess the nutrient status of soils and apply an appropriate amount 
of  organic  nutrients  and  mineral  fertiliser  according  to  crop  requirements  and  rotations.  The 
level of precision varies from those who undertake soil and manure analysis and use some form 
of recognised nutrient management planning to those who estimate requirements using general 
published information or those just using experience or guesswork. The legislation that applies 
in some countries is described in Section 2.8, which explains why the extent of record-keeping 
is variable.  

Farmers keep records (receipts) of purchased items, although the extent to which they are kept 
in an organised way will vary. Such records will usually exist for the  main items of feed, fuel 
(including  electricity)  and  water  (not  all  private  abstractions)  so  the  amounts  used  can  be 
identified.  Since  feed  and  water  are  primary  inputs  to  livestock  systems  their  usage  may  be 
monitored by farmers irrespective of whether receipts are kept. Most poultry farmers will have 
bought  in  bedding  material,  whereas  pig  producers  who  use  straw  may  produce  their  own  or 
have an agreement with neighbouring farmers exchanging manure for clean straw.  

For  manure  spreading,  monitoring  is  generally  limited  to  keeping  records  of  the  spreading 
activity (timing, amount, location, quality, etc.) [ 204, IMPEL 2009 ]. 

Computerised registration and the administration of costs, inputs and outputs are increasing and 
are  already  common  in  large  enterprises.  Monitoring  provides  data,  often  remotely  or 
instantaneously, that are useful for the farm management. This information allows operators to 
ensure  that  systems  are  operating  within  their  specification  and  to  easily  identify  failures  or 
areas where further investigation is required. Where measuring is applied, water gauges, electric 
meters and computers for indoor climate control are used. 

There may be requirements to check slurry stores regularly for any signs of corrosion, leakage 
or loss of integrity of the solid or floating cover and to find any faults that need to be put right. 
Professional help may be required. Checking takes place after completely emptying the stores. 
In  Denmark,  where  surface  crusts  are  required  as  an  alternative  to  the  slurry  stores'  covers, 
farmers are required to inspect the crust at least monthly, and to maintain a record of findings. 

Emissions to water by discharging waste water may occur under specific legislation and within 
set (discharge) conditions and monitoring requirements. 

148 

Intensive Rearing of Poultry or Pigs 

Chapter 3 

3  CURRENT CONSUMPTION AND EMISSION LEVELS OF 

INTENSIVE POULTRY OR PIG FARMS 

This  chapter  presents  data  on  consumption  and  emission  levels  associated  with  activities  on 
farms  for  the  intensive  rearing  of  poultry  or  pigs,  based  on  the  information  that  has  been 
submitted  in  the  framework  of  the  information  exchange.  It  aims  to  give  an  overview  of  the 
ranges that apply to these sectors in Europe and so to serve as a benchmark for the performance 
levels  associated  with  the  techniques  presented  in  Chapter  4.  The  factors  that  account  for  the 
variation  of  data  are  briefly  described  when  possible,  or  sometimes  only  mentioned.  The 
circumstances  under  which  data  have  been  obtained  are  described  in  more  detail  in  the 
evaluation of applied techniques in Chapter 4. 

3.1 

Introduction 

The major production activities, systems and techniques on intensive pig and poultry farms have 
been described in Chapter 2. The consumption and emission levels that were reported were not 
always  clear  and  comparable,  and  major  variations  occur  due  to  a  large  number  of  factors. 
Table 3.1 summarises the key environmental issues of the major on-farm activities. 

Table 3.1:  Key environmental issues of the major on-farm activities 

Major on-farm activity 

Housing of animals: 





the  way  the  animals  are  stocked
(cages, crates, free)
the  system  to  remove  and  store
(internally) the manure produced

Housing of animals: 





to  control  and

the  equipment 
maintain the indoor climate and
the  equipment  to  feed  and  water
the animals

Key environmental issue 

Consumption 

Potential emission 

Energy, litter, 
medication 

NH3, odour, noise, greenhouse gases 
(CH4, N2O, etc.), dust and fine dust 
particles (PM10), manure, waste water, 
other wastes (e.g. dead animals) 

Energy, feed, 
water 

Noise, waste water, dust, CO2

Storage of feed 

Energy 

Dust and fine dust particles (PM10), waste 

Storage of manure in a separate facility 

Energy 

NH3, odour, emissions to soil, greenhouse 
gases 

Storage of residues other than manure 

NA 

Odour, emissions to soil, groundwater 

Storage of dead animals 

Energy 

Odour, pathogens 

Unloading and loading of animals 

NA 

Noise, dust 

Manure landspreading 

Energy 

On-farm treatment of manure 

Additives, 
energy, water 

NH3, odour, greenhouse gases, 
pathogens, emissions to soil, groundwater 
and surface water of N, P etc., noise  
NH3,  odour,  greenhouse  gases,  waste 
water, emissions to soil 

Milling and grinding of feed 

Energy 

Dust and fine dust particles (PM10), noise 

Treatment of waste water 

Additives, 
energy 

Odour, waste water 

Incineration of dead animals 

Energy 

Emissions to air, odour 

NB: NA = not applicable. 

Intensive Rearing of Poultry or Pigs 

149 

Chapter 3 

The central environmental issue for  the  poultry or pig rearing  sectors is manure management: 
the amount produced, composition, method of removal, storage, treatment and its landspreading. 
This is reflected in the order in which the activities are presented, starting with feed as the major 
consumption issue and followed by manure production as the most important emission. 

The levels of consumption and emission depend on many different factors, such as the animal 
category, production phase, and management system. Additionally, factors such as climate and 
soil  characteristics  also  have  to  be  taken  into  account.  As  an  example,  the  climate  in  the 
Mediterranean  regions  is  characterised  by  two  very  distinct  seasons,  spring-summer  and 
autumn-winter, in which consumption and emissions have distinct values. The tables show the 
widest  possible  ranges  of  reported  consumption  and  emissions.  In  the  accompanying  text  an 
attempt  is  made  to  explain  this  variation  as  far  as  information  allows,  but  without  being  too 
specific. 

Within  MS,  standard  units  are  applied  that  may  not  always  be  comparable  with  units  used 
elsewhere. Consumption and emission levels can be measured in different ways and at different 
moments involving the factors mentioned above. For the sake of comparison and for reference, 
relevant factors will be mentioned that influence the character and the level of the consumption 
or emissions level presented.  

In the assessment of consumption and emission levels, a distinction can be made between single 
activities and the farm as a whole. Where possible, data are directly associated with a single on-
farm  activity,  so  as  to  enable  a  clear  link  to  the  reduction  techniques  described  in  Chapter  4. 
Some  other  data  are  given  for  the  farm  as  a  whole.  In  the  assessment  of  consumption  and 
emission levels of pig farming, it is important to know the production system applied. Growing 
and finishing aim for a slaughter weight of 90–110 kg or 150–170 kg (Italy) and can be reached 
within different periods of time. Poultry production systems seem to be quite similar throughout 
the EU. 

A  remark  may  be  made  on  the  use  of  animal  units  to  standardise  data  and  to  achieve 
comparability. For this purpose EU countries use the ‘animal unit’ or ‘equivalent animal’. There 
may be difficulties associated  with these standardised units, because in different EU countries 
they are defined in different ways (see Section 9.1). 

150 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 3 

3.2  Consumption levels 

3.2.1 

Feed consumption and nutritional levels 

The  amount  and composition  of feed  given  to  poultry  and  pigs  and  the  feed  management  not 
only has a strong influence on animal performance but also on the amount of manure produced, 
its composition and structure, and thereby on emissions such as ammonia. Thus, feeding is an 
important  factor  in  the  environmental  performance  of  an  intensive  poultry  or  pig  enterprise. 
Emissions  from  livestock  farms  are  predominantly  related  to  the  metabolic  processes  of  the 
housed animals. Two processes are considered essential: 

 

 

enzymatic digestion of feed in the gastrointestinal tract; 

absorption of nutrients from the gastrointestinal tract. 

The advanced understanding of these processes is responsible for the development of the wide 
range  of  feeds  and  feed  additives  adapted  to  the  needs  of  the  animal  and  to  the  production 
objectives. 

Consumption levels vary with the energy requirements of the individual animal, which involve 
maintenance requirements, growth rate and production level. The total amount of feed intake is 
a  result  of  the  duration  of  the  production  cycle,  the  daily  intake  and  the  type  of  production 
purpose  and  it  is  also  influenced  by  a  number  of  factors  related  with  the  animal.  Data  on 
consumption  levels  are  reported  in  kg  per  head  per  production  cycle  or  kg  per  kg  of  product 
(eggs  or  meat).  Comparisons  are  difficult  to  make  with  the  use  of  different  breeds  and  the 
application of different production targets (egg weight or animal weight) and production cycles. 

The following sections present an overview of the feed intake levels and nutrient requirements 
reported and show the existing variation where possible together with the factors that account 
for that variation. 

3.2.1.1 

Poultry feeding 

Indicative feeding levels for different poultry species are presented in Table 3.2.  

Table 3.2: 

Indication of feed conversion ratio and feed consumption per poultry category 

Types of animal 
production 

Feed conversion 
ratio 

Feeding level range 
(kg/bird/cycle) 

Feed amount 
(kg/bird 
place/year) 
34–47 (3) 
15.3–15.7 (4) 
16.8–33 (5) (1) 
22.6–33 (5) (1) 
150 (1) 
65 (1) 
37–58 (1) 
37–42 
17 (7) 

NA 
5.5–6.6 (3) 
2.4–5.7 (5) 
3.9–8 (5) (1) 
50–60 (1) 
24 (1) 
5.7–9.0 (1) 
7.6–12.9 (6) 
4.5–4.7 (3) (6) 

2.1–2.8 (1) (2) 
NI 
1.6–2.2 (1) 
1.8–2.3 (1) 
2.6–3.1 (1) 
2.3–2.8 (1) 
2.45 (3) 
2.66–2.82 (6) (7) 
2.75–3.37 (7) 

Laying hens 
Pullets  
Standard broilers 
Heavy broilers  
Male turkey 
Female turkey 
Pekin duck  
Barbary duck  
Guinea fowl 
NB: NI = no information provided; NA = not applicable. 
Source: (1) [ 500, IRPP TWG 2011 ]  
(2) FCR kg feed per kg eggs. 
(3) [ 43, COM 2003 ] 
(4) Calculations based on data (2009) from [ 633, ITAVI 2013 ] (6.3 to 6.46 kg/bird/cycle)  
(5) Calculations based on data reported in Table 1.3 and 19 days of sanitation. 
(6) [ 280, France 2010 ]  
(7) [ 418, ITAVI 2010 ]  

Intensive Rearing of Poultry or Pigs 

151 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

The  purpose  of  poultry  feeding  and  the  components  used  in  poultry  feed  mixtures  have  been 
described in Section  2.2.5.1. The amino acid composition of feeds, which is derived from the 
amino  acid  profile of  the individual  feed  materials,  has  to  be as  close  as  possible to  the ideal 
amino acid profile for the relevant animal species. In this ‘ideal protein’ concept, the required 
amino acid levels are expressed relative to the lysine level of the feed. Farm practices are (along 
with their variability) reported in  

Table 3.3. The recommended amino acid balances are quoted from literature, but the appraisal 
of  protein  and  lysine  levels  results  from  farm  observations  at  a  European  level.  Examples  of 
applied commercial feeding programmes are presented in Annex 9.2.1.  

Table 3.3:  Appraisal  of  protein  and  lysine  levels  and  scope  for  recommended  amino  acid 

balances 

Broilers 

Layers 

Turkeys 
(medium weight) 

20–24 
18–22 
17–21 
NI 
NI 

15.4–20 
15.5–19 
15–17  
15–17 
13–16 

12.5–13.5 
12.5–13.5 
12.5–13.5 
NI 
NI 

11.6–12.1 
11.4 
11–11.4 
NI 
NI 

Energy level MJ/kg, ME basis 
Phase 1 
Phase 2 
Phase 3 
Phase 4 
Phase 5 
Protein level (CP=N*6.25), total content 
 % feed, phase 1 
 % feed, phase 2 
 % feed, phase 3 
 % feed, phase 4 
 % feed, phase 5 
Lysine level, total content 
 % feed, phase 1 
 % feed, phase 2 
 % feed, phase 3 
 % feed, phase 4 
 % feed, phase 5 
mg/day 
Recommended amino acid balance, in percentage of lysine level 
Threonine: lysine 
Methionine  +cystine: 
lysine 
Tryptophan: lysine 
Valine: lysine 
Isoleucine: lysine 
Arginine: lysine 
NB:  ME = metabolisable energy; CP = crude protein; NI = no information provided. 

NI 
NI 
NI 
NI 
NI 
850–900 

1.1–1.5  
1.0–1.3  
0.9–1.2  
NI 
NI 
NI 

19–23 
86–102 
79–94 
101–130 

14–19 
75–81 
63–73 
105–125 

66–73 

81–88 

63–73 

70–75 

11.0–12.5 
11.0–12.5 
11.5–12.5 
11.5–13.5 
NI 

25–30 
22–28 
19–26 
18–24 
15–22 

1.80–1.50 
1.60–1.30 
1.40–1.10 
1.20–0.90 
1.00–0.80 
NI 

55–68 

59–75 

15–18 
72–80 
65–75 
96–110 

Source: [ 506, TWG ILF BREF 2001 ] [ 280, France 2010 ] [ 327, Germany 2010 ] [ 294, UK 2010 ] 

[500, IRPP TWG 2011 ] 

Indications of the applied levels of calcium and phosphate in feed are given in Table 3.4. 

Table 3.4:  Applied calcium and phosphorus levels in commercial feeds for poultry 

Element 
(% of feed) 
2–4.4 
0.9–2.25 
Ca 
P  
0.354–0.55 
0.4–0.76 
NB: Diets based on multiphase feeding.  

Pullets  Laying hens  Broilers   Turkeys (male)  Ducks 

0.65–1.2 
0.32–0.78 

0.65–1.4 
0.45–0.90 

0.7–1.2 
0.6–0.85 

Source: [ANNEX 9.2.1] [ 280, France 2010 ] 

152 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 3 

3.2.1.2 

Pig feeding 

For  pigs,  the  feeding  strategy  and  feed  formulation  vary  with  factors  such  as  live  weight  and 
stage of (re)production. A distinction is made between the feeding of young sows (gilts), mating 
and gestating sows and farrowing sows and between piglets, weaners, and fattening pigs. Feed 
amounts  are  expressed  in  kg  per  day  and  in  required  energy  content  per  kg  of  feed.  A  large 
number  of tables  and  data on  various feeding  strategies  are  available. The  following  tables  in 
this section merely present the ranges of reported levels applied in Europe, acknowledging that 
higher or lower nutrient levels may also be applied in certain cases. The final intake depends on 
the  amount  consumed  and  on  the  nutrient  concentration  and  therefore  minimum  levels  are 
recommended  for  the  different feeds  to  meet  the  pigs’  requirements  given  their  average  daily 
intake.  

The  amino  acid  composition  of  feeds  has  to  be  as  close  as  possible  to  the  ideal  amino  acid 
profile.  The  sum  of  the  amino  acid  contribution  of  each  ingredient  used  to  make  the  feed  is 
compared  to  the  ideal  protein  profile.  Lysine  being  the  first  limiting  amino  acid  for  pig 
performance in this 'ideal protein' concept, the required amino acid levels are expressed relative 
to  lysine.  Farm  practices  are  (along  with  their  variability)  reported  in  Table 3.5  (sows)  and 
Table 3.7 (weaners and fattening pigs). The recommended amino acid balances are quoted from 
literature,  but  the  appraisal  of  protein  and  lysine  levels  result  from  field  observations  at  a 
European level. Some applied commercial feeding programmes for pigs are presented in detail 
in Annex 9.2.2. 

Lactating  sows  generally  need  higher  nutritional  levels  than  gestating  sows  due  to  milk 
production; in particular, crude protein and lysine are required to be in higher concentrations in 
the feed ration. The energy requirements increase towards the moment of birth. After farrowing, 
daily  energy  requirements  increase  with  the  increased  size  of  the  litter  and  also  as  lactation 
progresses. Between weaning and first mating, energy levels remain high to help the animal to 
recover  and  to  prevent  loss  of  condition.  After  mating,  the  energy  content  of  the  feed  can  be 
reduced. During winter, higher energy levels are applied for gestating sows. The amount of feed 
given to a sow in production, including dry periods, and depending on energy intake, amounts 
to about 1 200–1 400 kg per year. Average nutritional levels are shown for sows in Table 3.5.  

Table 3.5:  Appraisal  of  protein  and  lysine  levels  and  scope  for  recommended  amino  acid 

balances for sows (one phase for every physiological stage) 

Lactating sow  Gestating sow 

Energy level (MJ/kg), ME basis 
Protein levels (CP=N*6.25), total content (% feed) 
Lysine levels, total content (% feed) 
Recommended  amino  acid  balance,  in  percentage  of  lysine 
level 
Threonine : lysine 
Methionine+cystine: lysine 
Tryptophan : lysine 
Valine : lysine 
Isoleucine : lysine 
Arginine : lysine 
NB: ME = metabolisable energy; CP = crude protein; NA = not applicable. 

12.5–13.5 
16–18 
1.00–1.15 

65–72 
53–60 
18–24  
69–100 
53–70 
67–70 

12–13 
13–16 
0.70–1.70 

71–84 
54–67 
16–21 
65–107 
47–86 
NA 

Source: [ 506, TWG ILF BREF 2001 ] [ 430, Paulicks et al. 2006 ] 

Indications of the range of applied levels of calcium and phosphorus in feed for sows are given 
in Table 3.6. 

Intensive Rearing of Poultry or Pigs 

153 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.6:  Applied calcium and phosphorus levels in commercial feeds for sows 

Feed (kg/sow/day) (1) 
Calcium (% feed) 
Total phosphorus (% feed) 
(1) Average range. 
NB: Diets based on multiphase feeding. 

Mating and gestating sows 
2.2–2.7 
0.55–0.9 
0.4–0.75 

Source: [ANNEX 9.2] [ 329, CORPEN 2003 ] [ 624, IRPP TWG 2013 ] 

Lactating sows 
5–8  
0.55–0.95 
0.5–0.75 

The amino acid requirements of boars are much higher at higher weights and so inevitably feeds 
are higher in crude protein and this increases nitrogen excretion [ 624, IRPP TWG 2013 ]. 

Fattening  pigs  are  fed  according  to  their  body  weight,  with  feed  intake  increasing  with 
increasing  weight.  Towards  the  end  of  the  finishing  period  (the  last  20–30 kg)  the  amount  of 
feed given is unchanged, while the protein level is generally lowered.  

The total amount of feed consumed during growing and finishing depends on the breed, FCR, 
daily growth, length of the finishing period and final live weight. For pigs growing from 25 kg 
up to 110 kg live weight, about 260 kg of feed is consumed. Obviously, the nutrient levels of the 
feed  are  most  important.  Nutritional  levels  have  to  meet  the  requirements  of  daily  growth  or 
production. For each weight category average requirements can be distinguished, as reported by 
various  sources  and  summarised  in  Table 3.7.  Increasingly,  finishing  periods  range  between 
30 kg  and  final  weight  and  are  divided  into  two  or  three  feeding  phases.  In  these  phases,  the 
nutrient content in the feed varies to meet the varying demand of the pig. The end of the first 
growing phase ranges between 45 kg and 60 kg live weight and the second phase between 80 kg 
and 110 kg. Where one feed is given between 30 kg and 110 kg, the content of the feed is equal 
to the average of the level of the two–phase feeds. 

Table 3.7:  Appraisal  of  protein  and  lysine  levels  and  scope  for  recommended  amino  acid 

balances for pigs (one phase for each major stage of growth) 

Energy level (MJ/kg), ME basis 
Phase 1 (weaned piglet) 
Phase 2 (growing pig) 
Phase 3 (finishing pig) 
Protein levels (CP=N*6.25), total content 
 % feed, phase 1 
 % feed, phase 2 
 % feed, phase 3 
Lysine levels, total content 
 % feed, phase 1 
 % feed, phase 2 
 % feed, phase 3 
Recommended amino acid balance, in percentage of lysine level 
Threonine: lysine 
Methionine +cystine: lysine 

Tryptophan: lysine 

Valine: lysine 
Isoleucine: lysine 
Arginine: lysine 
(1) [ 663, Simongiovanni et al. 2012 ] 
NB: ME = metabolisable energy; CP = crude protein. 
Source: [ 506, TWG ILF BREF 2001 ]  

12.5–13.5 
12.5–13.5 
12.5–13.5 

21–17 
18–14 
17–13 

1.30–1.10 
1.10–1.00 
1.00–0.90 

60–72 
50–64 
18–20 (fattening pigs) 
18–22 (weaners) (1) 
68–75 
50–60 
18–45 

154 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Standard  applied  levels  of  calcium  and  digestible  phosphorus  in  feeds  for  sows,  weaners  and 
fattening pigs (growers/finishers) are given in Table 3.8. 

Chapter 3 

Table 3.8:  Calcium  and  digestible  phosphorus  standard  levels  applied  to  feed  for  pigs,  in  total 

amount per kg of feed  

Sows 

Weaners 

Fattening pigs 

8.4–9.0 

6.9–7.5 

6.4–7.0 

Parameter  Gestating  Lactating 
Calcium 
(g/kg) 
Phosphorus 
+ phytase 
addition 
(g/kg) 
Digestible 
phosphorus 
(g/kg) 
ME (MJ/kg 
feed) 
Source: [ 624, IRPP TWG 2013 ] 

2.0–2.2 

7.9–8.5 

2.8–3.0 

12.6 

13.3 

6–9 kg 

9–20 kg 

20–30 kg  30–45 kg 

45–105 kg 

8.3–9.0 

9.9–10.5 

9.9–10.5 

8.0–8.6 

7.5–8.1 

7.7–8.3 

9.3–9.9 

9.3–9.9 

7.5–8.1 

7.0–7.6 

3.9–4.1 

3.7–3.9 

3.4–3.6 

2.8–3.0 

2.6–2.8 

14.4 

14.1 

14.1 

13.4 

13.4 

Another  example  is  presented  in  Table 3.9  for  finishers  in  Italy,  where  a  distinction  is  made 
between heavy and conventional pigs. In general, the feeding is ad libitum for light pigs, which 
are  capable  of  strong  muscular  development,  but  rationed  for  heavy  pigs,  which  have  a 
considerable  propensity  towards  fat  accumulation  and  towards  a  higher  weight  level.  This 
changes the feed composition. For example, whey (5–6 % dry matter) can be used for the heavy 
pigs,  with  13–15  litres  of  whey  substituting  1 kg  of  dry  feed.  The  whey  can  be  used  in 
increasing quantities, from 3–4 litres per head per day at a weight of 30 kg up to a maximum of 
10–12 litres for more than 130 kg (quantities beyond these levels may have negative effects on 
the utilisation i.e. FCR of the total daily ration). 

Table 3.9:   Example of rationing used for conventional and heavy fattening pigs in Italy 

Heavy pig 

Live weight (kg) 

Feed (88 % DM) (kg/day) 
Conventional pig 
Feed (88 % DM) (kg/day) 
Digestible energy (MJ/kg) 
Lysine (%) 
NB: NA = not applicable. 

Source: [ 391, Italy 1999 ] 

Up to 
25 
Ad lib. 

Ad lib. 
13.8 
1.20 

30 

50 

75 

100 

125 

150+ 

1.2–1.5 

1.5–2.0 

2.0–2.5 

2.5–3.0 

2.7–3.2 

3.0–3.4 

1.5 
13.4 
0.95 

2.2 
13.4 
0.90 

2.8 
13.4 
0.85 

3.1 
13.4 
0.80 

NA 

In finishing the heavy weight pig in Italy, different weight ranges are distinguished with their 
associated nutrient levels (see Table 3.10). 

Intensive Rearing of Poultry or Pigs 

155 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.10:  Average  nutritional  levels  applied  in  Italy  for  heavyweight  pigs  for  different  live 

weight intervals (as % of raw feed) 

Nutritional parameters 

Crude protein (CP, %) 
Crude fats 
Crude fibre 
Total lysine 
Total methionine + cystine 
Total threonine 
Total tryptophan 
Calcium 
Total phosphorus 
Digestible energy (MJ/kg) 
Source: [ 391, Italy 1999 ] 

Pigs 
35–90 kg 
15–17 
4–5 
< 4.5–6 
0.75–0.90 
0.45–0.58 
0.42–0.63 
0.15 
0.75–0.90 
0.62–0.70 
> 13 

Pigs 
90–140 kg 
14–16 
< 5 
< 4.5 
0.65–0.75 
0.42–0.50 
0.50 
0.15 
0.75–0.90 
0.50–0.70 
> 13 

Pigs 
140–160 kg 
13 
< 4 
< 4 
0.60–0.70 
0.36–0.40 
0.40 
0.10–0.12 
0.65–0.80 
0.48–0.50 
> 13 

3.2.2 

Water consumption 

The  total  amount  of  water  used  includes  not  only  consumption  by  the  animals,  but  also  the 
water used to clean housing, equipment and the farmyard, the water used for cooling purposes 
and  the  water  consumed  by  air  cleaning  techniques.  Cleaning  water  particularly  affects  the 
volume of waste water produced on farms. After every cycle, the housing is fully cleaned and 
disinfected. The length of this cleaning period varies from 1 day [ 500, IRPP TWG 2011 ] up to 
2 (Finland, the UK) or even 3 weeks (Ireland). 

3.2.2.1 

Water requirements of poultry farms 

3.2.2.1.1 

Birds' water consumption 

In the poultry sector, water is required for satisfying the physiological needs of the birds. Water 
intake  depends  on  a  number  of  factors,  such  as  animal  species  and  age,  animal  condition 
(health), water and ambient temperature, feed composition, and the drinking system used. 

With  increasing  ambient  temperatures  the  minimum  water  intake  of  broilers  increases 
geometrically.  A  higher  laying  percentage  also  raises  the  daily  consumption  of  layers.  With 
respect  to  drinking  systems,  nipple  drinkers  show  lower  consumption  than  round  drinker 
systems, due to lower spillages. In general, drinking consumption is roughly twice the feeding 
consumption.  The  water  to  feed  ratio  is  between  1.6  (birds  with  a  slow  growth  rate)  and  2.2 
(birds  with  a  fast  growth  rate).  Average  water  consumption  levels  are  shown  in  Table 3.11. 
Water to feed ratios were reported for broilers, laying hens, turkeys and ducks. 

Table 3.11:  Water consumption of different poultry species per cycle and per year 

Poultry species 

Average water 
to feed ratio  
(l/kg) 

Water consumption  
per cycle 
(l/head per cycle) 

Laying hens 

1.8–2.0 

10 (up to production) 

Broilers 
Turkeys 
Ducks  
Source:  [  44,  IKC  1993  ]  [  391,  Italy  1999  ]  [  24,  LNV  1994  ]  [  358,  France  2010  ]  

4.5–11 
45–100  
30–46 

1.7–1.9 
1.8–2.2 
3.5–6  

 [ 500, IRPP TWG 2011 ] 

Annual water 
consumption 
(l/bird place per year) 
73–120  
(egg production)  
30–70 
117–150 
195–300 

156 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
3.2.2.1.2 

Use of cleaning water 

Waste water primarily results from the cleaning of the animal houses. All water spillages from 
drinking are usually removed as part of the manure. Farms that produce wet manure (no drying 
in  the  poultry  house)  can  store  this  water  in  the  manure  storage  facility.  On  farms  where  dry 
manure  is  produced,  waste  water  is  stored  separately  (e.g.  in  tanks).  Table 3.12  shows  the 
estimated cleaning water use for different poultry housing systems.  

Chapter 3 

Table 3.12:  Estimated water use for cleaning of poultry housing 

Poultry species 

Use (m3 per m2 cleaned) 

0.01 
0.030–0.060 (1) 

0.005–0.008 (1) 

0.009–0.010 (1) 
0.02 (2) 
0.005–0.050 (2) 
0.064 (1) 

Cycles  
per year 
1 
1 

6 

2–3 

8.6 
3.5 

Use (m3 per m2 
per year) 
0.01 
0.03–0.06 (1) 
0.03–0.048 (1) 
0.085–0.105 (2) 
0.018–0.03 (1) 
0.04–0.06 (2) 
0.040–0.430 (2) 
0.215 (1) 

Layers (enriched cages) 
Layers (deep litter) 

Broilers  

Turkeys 

Ducks (Pekin) 
Ducks (Barbary) 
(1) Data related to French poultry farms. 
(2) Data related to UK poultry farms. 
Source: [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ] 

The  volume  of  water  used  for  cleaning  purposes  is  variable  and  depends  on  the  technique 
applied  and  the  water  pressure  of  the  high-pressure  cleaner.  Also,  using  hot  water  or  steam 
instead of cold water will reduce the volume of cleaning water used. 

For laying hens, water use for cleaning varies with the housing system. Cleaning is done after 
each round of 12–15 months. For layers  kept in enriched cages, less cleaning water is needed 
than for layers in a deep litter system. The cleaning of housing systems where layers are kept on 
deep litter varies with the area covered with slats. The larger the surface with slats the higher the 
volume.  Cleaning  water  requirements  for  non-cage  housing  of  laying  hens  is  reported  to  be 
4 m3/1 000 hens in French farms [ 358, France 2010 ]. 

Cleaning water use for broiler houses varies widely. In France, water use for cleaning a broiler 
house with a 1 200 m2 floor surface (equivalent to 1 800 m2 including surfaces of walls and roof 
to be washed) is reported as 5.5 m3 per batch for a building on a hard-packed floor and 10 m3 for 
a building with a concrete floor. For turkeys and for the same surface, the quantity of cleaning 
water is about 11–13 m3 [ 358, France 2010 ]. 

3.2.2.1.3 

Use of cooling water 

Water consumption related to cooling of bird houses by fogging or spraying systems depends on 
climatic conditions, and only occurs for limited periods during the year. One litre of water that 
evaporates at 25 °C absorbs 678 Wh from the environment.  

To cool a house of 1 000 m2 by fogging, for 10 hours a day for 30 days, 100 m3 of water are 
needed. With a spraying system operating in the same conditions, the water requirement would 
be 190 m3 [ 354, ITAVI 2004 ]. Additional information is available in Section 4.8.3. 

Intensive Rearing of Poultry or Pigs 

157 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

3.2.2.2 

Water requirements of pig farms 

3.2.2.2.1 

Animals' water consumption 

Four types of water consumption can be identified: 

 

 

 

 

the water necessary for maintaining homeostasis and meeting the growth requirements; 

the water ingested by the animals in excess of what is strictly necessary; 

the water which is wasted at the moment of drinking due to an incorrect structuring of the 
distribution system; 

the water used by the animals for satisfying behavioural needs, such as the water spillage 
during  the  typical  behaviour  generated  by  the  lack  of  ‘play’  objects  other  than  the 
drinking system. 

Animal consumption of water is expressed in litres per kg of feed and depends on  animal age 
and  live  weight,  animal  health,  stage  of  production,  climatic  conditions,  and  feed  and  feed 
structure. 

The  water  consumption  of  finishers  per  kg  of  feed  ingested  decreases  with  age  but,  as  the 
animals have a higher feed intake with increasing live weight towards the end of the finishing 
period, the absolute daily water intake is higher. 

For sows, water consumption is important for maintaining homeostasis and for the production 
of piglets or milk. Such high levels of water ingestion also have positive effects on the animal’s 
ingestion  capacity  during  the  suckling  phase  and  on  maintaining  the  health  of  the  urogenital 
organs during pregnancy. Total water requirements can differ in different systems and regions.  

Table 3.13 shows the average water consumption for different pig categories and rearing stages 
in Spain.  

Table 3.13:  Average water requirements of pigs in Spanish farms with respect to pig category  

Pig production type 

Sows (in a farrow-to-finish farm) (1) 
Farrowing sows with piglets up to 6 kg 
Farrowing sows with piglets until 20 kg 
Gilts 
Weaners from 6 to 20 kg 
Growers from 20 to 50 kg 
Fattening pigs from 50 to 100 kg 
Fattening pigs from 20 to 100 kg 
Boars 
(1) Includes all offspring of the sow until end of fattening period. 
Source: [ 431, MARM 2010 ] 

Water consumption  
(l/animal place per day) 
60–73 
14–17 
21–26 
10–13 
2.7–3.3 
5.4–6.6 
11–14 
7–9 
15–18 

In  Denmark,  typically  around  800 kg  of  dry  feed  are  used  per  pig  place  per  year.  With  that 
amount, the pigs are drinking 2.5–3.0 litres of water per kg of feed. In total, 2 000–2 400 litres of 
drinking water are needed per pig place per year [ 500, IRPP TWG 2011 ].  

In the UK, water requirements for sows are reported as 20–40 l/d for farrowing sows and 10–
20 l/d for gestating sows [ 624, IRPP TWG 2013 ]. 

158 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
The  water  consumption  increases  linearly  with  body  weight  after  weaning,  as  represented  in 
Figure 3.1.  Animals  consume  0.8  litres  per  day  on  entry  (7 kg  live  weight),  reaching  
4–5 litres per day at the end of the weaning phase (27 kg live weight). The water consumption 
increases linearly at a rate of about 0.16 litres of water per kg of live weight.  

Chapter 3 

Source: [ 358, France 2010 ] 

Figure 3.1:  Evolution of water consumption with the live weight of post-weaning piglets 

Increased  water  requirements  at  higher  indoor  temperatures  are  due  to  the  thermoregulation 
needs.  For fattening  pigs,  the  ratio  of  water  intake  to  feed intake  increases form  close  to  3 at 
temperatures  between  20 °C  and  24  °C  to  over  4  at  a  temperature  of  28  °C.  A  higher  water 
wastage  is  also  expected  at  higher  temperatures,  due  to  the  efforts  that  animals  make  to  cool 
themselves [ 359, Massabie P 2001 ].  

Measurements in French farms have shown that, in the fattening phase, the daily water intake 
increases  by  0.063  litres  per  kg  of  live  weight  at  a  temperature  of  20–24 °C  (i.e.  water 
consumption (l/d) = 0.063 * weight (kg) + 2.564) and by 0.10 l/kg of live weight at an indoor 
temperature of 28 °C (i.e. water consumption (l/d) = 0.101 * weight (kg) + 2.564). In the case of 
lactating sows, at higher temperatures, water intake is not increased but the feed intake is [ 359, 
Massabie P 2001 ].  

In  general,  manure  production  increases,  but  with  a  simultaneous  decrease  in  its  dry  matter 
percentage,  due  to  an  increased  water  intake  (Table 3.14).  This  pattern  is  similar  for  pigs, 
lactating sows (including litter) and dry sows with water including other fluids such as whey, 
skimmed milk and silage effluent.  

Table 3.14:  Example of the effect of water to feed ratio on the production and dry matter content 

of manure of fattening pigs 

Water to feed 
ratio 
1.9 : 1 
2.0 : 1 
2.2 : 1 
2.4 : 1 
2.6 : 1 

Ration  
(kg/pig per day) 
2.03 
2.03 
2.03 
2.03 
2.03 

Manure production 
(m3/pig place per year) 
0.88 
0.95 
1.09 
1.23 
1.38 

Dry matter content 
(%) 
13.5 
12.2 
10.3 
8.9 
7.8 

Source: [ 44, IKC 1993 ] 

Water spillage and slurry generation are both influenced by the type of drinking system and the 
rate of water delivery. In  Table 3.15, it can be seen that an increase in the speed of the water 
delivery of the drinking nipples by a factor of 2 leads to an increase in the volume of the slurry 
produced by a factor of 1.5, and at the same time a decrease in the DM content of the slurry. 

Intensive Rearing of Poultry or Pigs 

159 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.15:  Effect of water delivery of drinking nipples on the production and dry matter content 

of manure of fattening pigs 

Water delivery 
(l/pig per min) 
0.4 
0.5 
0.6 
0.7 
0.8 
Source: [ 44, IKC 1993 ] 

Manure production 
(m3/pig place per year) 
1.31 
1.45 
1.60 
1.81 
2.01 

Dry matter content 
(%) 
9.3 
8.1 
7.2 
6.1 
5.2 

In cases of restricted feeding, drinking water consumption is reported to increase as pigs tend to 
satisfy  the  feeling  of  hunger  in  this  way;  this  extra  quantity  will  be  excreted  as  urine  and 
increases  slurry  generation.  Other  nutritional  factors  that  increase  water  consumption  are  the 
crude  protein  content  in  the  feed,  as  well  as  sodium  and  potassium  levels  [  359,  Massabie  P 
2001 ]. 

3.2.2.2.2 

Use of cleaning water 

The volume of waste water produced on pig farms is directly related to the amount of cleaning 
water  used.  Water  consumption  on  pig  farms  is  affected  not  only  by  the  cleaning  technique 
applied, but also by the housing system, as a lot of water is used if washing the floors is required 
for the purpose of slurry removal. For example, the larger the slatted floor surface, the lower the 
cleaning water use. In Table 3.16, data are reported that have been measured in different farm 
types or floor systems, but large variations are generally observed depending on the use of high-
pressure cleaning and the application of detergents to soak the surface. The differences in use 
between floor systems can therefore not explain by themselves the level and variation between 
different farms. 

Table 3.16:  Estimated average water use for the cleaning of pig housing in Denmark 

Reared animal  

Housing system (slurry 
management) 

Consumption 
(litres/animal/cycle) 

Farrowing sows 

Weaners  
(7–30 kg) 

Fattening pigs  
(30–100 kg) 

Crates, fully slatted floor 
Crates, partly slatted floor 
Fully slatted floor 
Draining floor with slits 
(50/50) 
Partly slatted floor 
Partly slatted floor  
(50–75 % solid floor) 
Partly slatted floor  
(25–50 % solid floor) 
Solid floor 
Draining floor with slits 
(33/67) 

NI 
NI 
15 

20 

20 

25 

25 

30 

25 

Consumption 
(litres/animal 
place/year) (1) 
340  
340 
87 

116 

116 

100 

100 

120 

100 

(1) Consumption calculated for an average production time of 90 days for fattening pigs and 63 days for 

weaners in Denmark. 

NB: NI = no information provided. 
Source: [ 437, Agrsci 2008 ] 

Differences in the ease of cleaning have been reported, but not measured, in relation to wall and 
hard surface material. However, reduced water consumption has been reported for the cleaning 
of  hard-packed  floors,  in  comparison  with  concrete  floors.  This  might  therefore  represent  a 
potential means for reduced water use.  

160 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
3.2.2.2.3 

Use of cooling water  

Water consumption related to cooling of pig houses by fogging or spraying systems depends on 
climatic conditions, and only occurs for limited periods during the year. One litre of water that 
evaporates at 25 °C absorbs 678 Wh from the environment. Additional information is available 
in Section 4.8.3. 

Chapter 3 

3.2.2.2.4 

Use of water for air cleaning systems 

Air  cleaning  systems  like  biofilters,  water  scrubbers,  chemical  scrubbers  and  multi-stage 
systems  consume  significant  volumes  of  water.  The  treated  air  leaves  these  systems  at  a 
humidity of more than 95 %. Water consumption is a function of the airflow rate, humidity and 
ambient temperature. This means that more water is provided to these systems in summer than 
in winter. On average over the year, fresh water consumption from 5 to 7 litres per 1 000 m3 of 
treated  exhaust  air  are  reported  with  the  application  of  any  of  these  air  cleaning  systems. 
Additional information concerning air cleaning systems is available in Section 4.9. 

3.2.3 

Energy consumption 

Quantification of the energy consumption of livestock farms is a complex undertaking for all the 
production  systems,  as  their  organisation  and  systems  are  not  homogeneous.  Moreover,  the 
technologies  applied  to  the  production  system,  on  which  the  amount  of  energy  consumption 
depends  to  a  large  extent,  vary  substantially  depending  on  the  structural  and  production 
characteristics of the farms. Another important factor that influences the energy consumption is 
the climatic conditions [ 506, TWG ILF BREF 2001 ]. The main measures applied in poultry 
and pig housing systems for reducing energy consumption consist of the control of heaters for 
the rearing  of  young  livestock,  the  insulation of  buildings,  control  of  ventilation  and  artificial 
lighting systems [ 264, Loyon et al. 2010 ]. 

The reported energy use on poultry and pig farms and their main findings are presented in the 
following sections.  

3.2.3.1 

Poultry farms 

As regards layer farms, artificial heating of the housing is not commonly applied, due to the low 
temperature  needs  of  the  birds  and  the  relatively  high  stocking  density.  Activities  requiring 
energy are: 

 

 

 

 

 

 

heating the water in winter; 

feed distribution; 

housing ventilation; 

lighting, this requires high consumption levels in order to artificially maintain a constant 
period  of  high  light  levels  during  the  year,  so  as  to  increase  egg  production  during  the 
periods of the shortest days; 

egg collection and sorting: consumption is about 1 kWh per 50–60 m of conveyor belt; 

operating the sorting and packaging facilities. 

Intensive Rearing of Poultry or Pigs 

161 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

On poultry meat farms, the main energy consumption is related to the following areas: 

 

 

 

 

heating  in  the  initial  phase  of  the  cycle  which  is  effected  with  hot  air  heaters  (e.g.  in 
France it accounts for around 80 % of the consumption); 

housing ventilation, which varies between the winter and summer periods from 2 000 to 
12 000 m3/h per 1 000 heads (e.g. the capacity of the installed ventilation system is around 
5 m3/h per kg of LW in France); 

lighting, which is critical for both animal welfare and performance; 

energy used for distribution, and sometimes, preparation of feed. 

Seasonal  variability  of  energy  consumption  during  the  year  is  primarily  related to  the  type  of 
farm  and  the  type  of  systems  used.  On  broiler  farms,  electrical  energy  consumption  is  at  a 
maximum  in  the  summer  (ventilation)  and  thermal  consumption  is  at  a  maximum  in  winter 
(heating). At laying hen farms, where winter heating is not used, the peak of (electrical) energy 
consumption is in summer, due to the increase in ventilation rate [ 391, Italy 1999 ]. 

Apart from annual trends, daily trends in electrical energy consumption are also quite variable 
and relate to the type of technical systems used on the farm.  Often, there are two daily peaks 
corresponding to feed distribution. In poultry farms, the main sources of energy are propane gas 
and electricity. In addition to electricity and propane gas, fuel oil is used to run tractor engines 
and generators.  

Propane  gas  is  widely  used  for  heating  poultry  meat  houses,  and,  for  instance,  in  France  it 
accounts for approximately  2 % of the production costs in broiler production. In poultry meat 
farms, gas heating is very important not only to provide the high ambient temperatures required 
on the birds' arrival (32 °C for chicks and 34 °C for turkeys on the first rearing day) and during 
the first days of rearing, but also because of the large surface and the volumes of air flowing in 
the poultry houses, which induce high energy requirements for heating. The required installed 
heating power is equivalent to about 85–100 W/m2 [ 341, Amand et al. 2007 ]. Data concerning 
the  average  gas  consumption  for  poultry  meat  houses,  observed  in  France,  are  reported  in 
Table 3.17. 

Table 3.17:  Annual average gas consumption reported for poultry production in France 

Annual average gas consumption (1) 

Type of animal 
production 
Standard broilers 
Heavy broilers 
Female turkeys 
Ducks (Barbary) 
Guinea fowl 
Broiler breeders 
Pullets 
(1) The range reported for each poultry species includes different housing, heating and ventilation systems.  
NB: NA = not applicable. 
Source:[ 342, ADEME 2008 ] 

kWh/kg of meat produced 
0.38 (0.34–0.48) 
0.35 (0.30–0.43) 
0.56 (0.50–0.58) 
0.57 (0.47–0.58) 
1.12 (1.06–1.19) 
NA 
NA 

kWh/m2 
93.8 (64.9–113.2)  
92.5 (58–110.4)  
95.2 (81.4–113.2) 
100.7 (82.8–110.4) 
103.5 (98.1–110) 
1.1 
47.6 

kg gas/m2 
6.8 (4.7–8.2) 
6.7 (4.2–8) 
6.9 (5.9–8.2) 
7.3 (6.0–8) 
7.5 (7.1–8) 
0.08 
3.45 

The  average  consumption  of  propane  gas  that  is  reported  from  the  UK  is  approximately 
15 kg/m2 for broilers, corresponding to a share of the total production costs of around 6.5–8 %. 
For  the  rearing  of  turkeys,  the  average  energy  consumption  is  reported  to  be  77.2 kWh/m2, 
which  corresponds  to  around  3.4 %  of  the  total  production  costs.  As  for  gas,  electricity 
consumption varies considerably according to  the type of production due to the differences in 
the  type  of  building,  ventilation  and  heating  needs.  Data  concerning  the  average  electricity 
consumption for poultry meat houses, observed in France, are reported in Table 3.18. 

162 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
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Table 3.18:  Annual average electricity consumption for poultry production in France 

Annual average electricity consumption 

Type of animal 
production 

kWh/m2 

Standard broilers 
Female turkeys 
Broiler breeders 
NB: NI = no information provided. 
Source: [ 342, ADEME 2008 ] 

15.2 
11.7 
18.8 

25 % of the lower 
reported values 
(kWh/m2) 
9.4 
7.2 
NI 

25 % of the higher 
reported values 
(kWh/m2) 
20.3 
13.1 
NI 

In  the  UK,  electricity  consumption  for  the  rearing  of  turkeys  is  reported  to  be  equivalent  to 
2.64 kWh/m2.  Examples  of  breakdown  values  for  electricity  consumption  are  reported  in 
Table 3.19, for two different poultry farms located in France, with a surface of 1 000 m2 each.  

Table 3.19:  Distribution of electricity consumption for two poultry farms in France 

Farm characteristics 

Ventilation 
(%) 

Lighting 
(%) 

Feeding 
(%) 

Watering 
(%) 

Others 
(%) 

Annual 
consumption 
(kWh) 

Broilers – High consumption 
farm (mechanical ventilation, 
artificial lighting, water 
pumping from borehole) 
Turkeys – Low consumption 
farm (no fans, natural 
lighting, connected to water 
supply network) 
Source: [ 342, ADEME 2008 ] 

48.1 

32.5 

4.7 

8.7 

6 

21 000 

18.4 

41.4 

16 

10.9 

13.3 

5 440 

Table 3.20 shows the energy requirements of some essential activities on broiler and layer farms 
in Italy. The daily consumption will be quite variable depending on the size and the equipment 
used, on energy-saving measures, as well as on losses caused by lack of insulation. The overall 
energy consumption for laying hens based on these data was reported as ranging between 3.5 
and 4.5 Wh per bird per day depending on the type of farm. 

Table 3.20:  Indicative levels of daily energy consumption of activities on poultry farms in Italy 

Activity 

Unit 
Wh/bird/day 
Wh/bird/day 
Wh/bird/day 
Wh/bird/day 

Local heating  
Feeding 
Ventilation 
Lighting 
Egg preservation (where necessary)  Wh/egg per day 
kWh per 50–60 m 
Conveyor belt for egg collection 
kWh 
Egg sorting and packaging  
(1) Only applicable at the initial stage of the cycle (15 days). 
NB: NI = no information provided; NA = not applicable. 
Source: [ 391, Italy 1999 ] 

Estimated energy consumption 
Broilers 
13–20 (1) 
0.4–0.6 
0.10–0.14 
NI 
NA 
NA 
NA 

Laying hens 
NA 
0.5–0.8 
0.13–0.45 
0.15–0.40 
0.30–0.35 
1 
1.5 

Indicative  levels  of  energy  use  in  poultry  farms  in  the  UK  are  shown  in  Table 3.21  
[ 500, IRPP TWG 2011 ]. 

Intensive Rearing of Poultry or Pigs 

163 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 3.21:  Indicative levels of energy use in poultry farms in the UK  

Poultry 
category 

Unit 

Live weight  
(kg) at marketing 

Electricity 

Non-electric 
static equipment 

kWh/bird per year 
Broilers  
kWh/bird per year 
Turkeys 
kWh/bird per year 
Ducks 
kWh/bird per year 
Geese 
kWh/dozen of eggs 
Laying hens 
NB: NI = no information provided; NA = not applicable. 
Source: [ 355, Warwick 2007 ] [ 500, IRPP TWG 2011 ] 

2.2 
14 
3.5 
NI 
NA 

0.4–0.7 
4.20 
2.6 
Trace 
0.54 

1.10 
7.00 
1.75 
Trace 
0.09 

Mobile 
machinery 
(fuel) 
Trace 
Trace 
Trace 
Trace 
Trace 

In  France,  the  total  energy  consumption  for  turkeys  is  reported  as  111 kWh/m2/year  
(i.e.  6 to  8 kWh/bird  or  17 kWh/bird/year),  while  for broilers  it  is reported  to  be  in  the  range 
from 0.6 to 0.8 kWh/bird [ 500, IRPP TWG 2011 ]. Estimates of energy consumption in pullet 
and laying hen houses in France are shown in Table 3.22. 

Table 3.22:  Estimates of energy consumption (kWh/bird) for pullets and laying hens, in France 

Cage system 
1.42 
NA 

Pullets 
Laying hens 
NB: NA = not applicable. 
Source: [ 340, ADEME 2007 ] 

Gas 

Electricity 

Non-cage system 
1.42 
NA 

Cage system 
0.45 
3.15 

Non-cage system 
0.45 
2.45 

The measured energy consumption in a broiler farm in Finland is presented in Table 3.23. 

Table 3.23:  Energy consumption allocation in a broiler house in Finland 

Unit 
Electricity 
kWh/batch 
3 800 
kWh/m2/batch 
2.38 
kWh/m2/year 
14.3 
0.88 
kWh/bird place/year 
NB: Data reported for a farm of 26 000 bird places, 6 batches/year, 1 600 m2. 
Source: [ 624, IRPP TWG 2013 ]  

Heat 
64 800 
40.5 
243 
15 

Approximately 50–70 % of the heat losses by convection from poultry houses occur from roofs 
that hence need to be well insulated. Losses are dependent on the different levels of insulation 
and of outdoor temperature (see example in Table 4.37).  

3.2.3.2 

Pig farms 

Energy  use  on  pig  farms  is  related  to  lighting,  heating,  ventilation  and  feed  preparation. 
Electricity is the main form of energy used as it responds to both needs for heating (e.g. radiant 
electric heaters) and power (e.g. ventilation, feed distribution, lighting). Fuel oil is the second 
source of energy, and it is mainly used to power generators but also for heating water in boilers 
(in more than 60 % of French farms) [ 343, ADEME 2008 ]. 

Gas, such as propane, is exclusively used for heating. In colder climates in northern Europe, like 
in Finland, consumption of fuels is significant because of the need for supplementary heating. 

164 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

For  example,  in  Finland,  pig  farm  buildings  are  always  heated  in  wintertime,  and  heating 
systems that make use of renewable energy are supported by farm building investments.  

Energy  sources  are  used  in  variable  shares  across  Europe.  In  Italy,  about  70 %  of  the  energy 
used in pig rearing comes from fuel oil, whilst in the UK more than 57 % of the energy used is 
electricity.  In  moderate  climates,  such  as  France,  electricity  is  the  form  of  energy  that  is 
consumed the most.  

The share of each energy source and the total average energy consumption, observed in France 
for  different  types  of  pig  farms,  are  reported  in  Table 3.24.  The  variability  between  farms  in 
total  energy  consumption  is  substantial,  i.e.  the  standard  deviation  of  the  average  energy 
consumption is equivalent to 328 kWh per sow per year for the integrated farrow-to-finish farm. 

Table 3.24:  Share of energy sources and total average energy consumption for different types of 

pig farms in France  

Electricity 

Fuel oil 

Gas 

Total average energy consumption 

Type of farm 

 % 

76 

Farrow-to-finish 
Rearing (weaners-to-
fattening pigs) 
Breeding 
(1) Value expressed in kWh/weaner produced. 
NB: NA = not applicable. 

70 

86 

 % 

21 

14 

30 

 % 

3 

0 

0 

kWh/pig 
produced/year 
48 

25 
19 (1) 

kWh/sow/year 

983 

NA 

403 

Source: [ 343, France 2010 ] [ 344, France 2010 ] 

The distribution of total energy consumption, reported from France for each physiological stage 
present  in  an  integrated  pig  farm  (where  rearing  from  farrowing  to  finish  is  performed),  is 
presented  in  Table 3.25.  The  shares  of  energy  used  for  each  process  (heating,  ventilation, 
lighting, feeding) are shown in Table 3.26. 

Table 3.25:  Distribution  of  energy  consumption  in  integrated  farms  in  France,  for  each 

physiological stage (average values from 15 farms) 

Physiological stage  Weaners 

Energy consumption (%) 
Source: [ 343, ADEME 2008 ] 

36 

Farrowing  
sows 
22 

Fattening 
pigs 
27 

Gestating sows  Other stages 

8 

7 

Table 3.26:  Shares  of  energy  consumption  for  each  consuming  process,  in  integrated  farms  in 

France 

Weaners 
Fattening pigs 
Farrowing 
Source: [ 344, ADEME 2008 ] 

Heating 
(%) 
79 
2 
81 

Ventilation 
(%) 
15 
90 
10 

Lighting 
(%) 
6 
3 
8 

Feeding 
(%) 
1 
5 
1 

The results of a project about the average annual energy consumption per LU (1 livestock unit = 
500 kg) for different types of farms in Italy, are summarised in Table 3.27.  

Intensive Rearing of Poultry or Pigs 

165 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.27:  Average  annual  energy  consumption  per  type  of  pig  farm  and  by  type  of  energy 

source used and operation in Italy 

Integrated farm 

Fattening pig farm 

Operation 

Electricity 
kWh/yr/LU  % 
27.3 

Fuels 
kWh/yr/LU  % 
0 

0 

Electricity 

kWh/yr/LU 
20.14 

0 

0 

0 

0 

52.75 

0 

52.75 

0 

0 

0 

0 

100 

0 

100 

85.12 

27.87 

8.39 

6.03 

19.39 

6.47 

173.41 

Fuels 
kWh/yr/LU  % 
0 

0 

70.84 

81.2 

0 

1.35 

0 

15.08 

0 

87.27 

0 

1.5 

0 

17.3 

0 

100 

 % 
11.6 

49.1 

16.1 

4.8 

3.5 

11.2 

3.7 

100 

10.01 

61.31 

95.08 

14.32 

Feeding 
Ventilation 
and heating 
Feed mill 
Manure 
management 
Manure 
processing 
Manure 
application 
Lighting 
Total energy 
consumption 
NB: LU = livestock unit = 500 kg. 
Source: [ 669, Italy 2013 ] 

224.71 

10.06 

31.08 

2.85 

42.3 

6.4 

4.4 

4.5 

13.8 

1.3 

100 

The  effect  of  farm  size  is  also  illustrated  for  farms  in  Italy  (Table 3.28).  Here,  the  larger  the 
farm, the higher the energy consumption. This was explained by the use of more machinery in 
larger  enterprises,  with  an  associated  higher  consumption  of  power  (factor  2.5).  Interestingly, 
this is in contrast with the experiences in the UK, where large herds have lower energy inputs 
per head than small herds [ 395, ADAS 1999 ]. 

Table 3.28:  Average daily energy consumption for farms in Italy by animal capacity  and energy 

source 

Energy source 

Electrical energy consumption 
Diesel fuel 
Natural gas 
Fuel oil 
Liquid gas 
Total thermal energy consumption 
Total energy consumption 
Source: [ 391, Italy 1999 ] 

Estimated energy consumption per animal capacity 
(kWh/head per day) 

Up to 500 
pigs 
0.061 
0.084 
0.002 
0.048 
0.042 
0.176 
0.237 

501 to 1 000 
pigs  
0.098 
0.107 
0.012 
0.029 
0.048 
0.196 
0.294 

1 001 to 3 000 
pigs 
0.093 
0.169 
0.023 
0.011 
0.018 
0.221 
0.314 

Over 3 000 
pigs 
0.150 
0.208 
0.010 
0.049 
0.026 
0.293 
0.443 

Heating  and  ventilation  are  the  main  consumers  of  electricity  in  pig  farms.  The  average 
electricity consumption is presented in Figure 3.2 for the different uses in the farm for French 
conditions; the share for ventilation can be highly variable, depending on the characteristics of 
fans and ventilation management, and on the animals’ physiological stages [ 344, ADEME 2008 ]. 

166 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 3 

Source: [ 344, ADEME 2008 ] 

Figure 3.2:  Breakdown of electricity consumption on pig farms in France 

A  study  concerning  electricity  consumption  on  pig  farms  adopting  different  techniques  was 
conducted  in  the  UK  over  a  period  of  1  to  2  years.  The  observed  results  are  reported  in 
Table 3.29. A major conclusion reached by this study was that the choice  of the system to be 
adopted  has  less  influence  on  electrical  consumption  than  the  way  in  which  the  system  is 
operated on a daily basis [ 432, BPEX 2010 ]. 

The main factors affecting the electricity use for ventilation are the stocking density (pig heat 
needs to be removed), and the differential between the outside temperature and the indoor target 
temperature.  Whilst  the  outside  temperature  is  beyond  the  control  of  users,  the  indoor  target 
temperature is indeed a variable that can be managed. 

Table 3.29:   Electric energy consumption for different rearing stages in pig farms in the UK (data 

from 11 farms) 

Electric energy consumption (kWh/pig produced) 

Animal category 

Total 
6.3–11.3 
1.7–10.6 
3.2–11.7 

Farrowing sows 
Weaners 
Growers 
(1) The lower values of the range were reported by farms equipped with ACNV systems. 
NB: NI = no information provided.  
Source: [ 432, BPEX 2010 ] 

Ventilation (1) 
0.04–1.43 
0.34–5.39 
3.59–14.7 

Heating 
3.9–12.6 
0.1–4.1 
NI 

Lighting 
0.6–0.9 
0.3–0.7 
0.9–2.6 

Lighting generally represents the third most relevant share of the total electric consumption of a 
pig farm. Daylight is considered to be desirable, but artificial light is used instead in areas where 
natural  light  intensity  can  be  highly  variable.  Minimum  lighting  requirements  are  set  by  the 
welfare legislation. Energy requirements for the lighting of pig housing can therefore be quite 
different for different areas in Europe.  

Energy use for heating depends on the type of animal, the climate in the different areas of the 
EU and the housing system as well as the management of air turnover in rooms, especially with 
regards  to  the  minimum  ventilation.  Creep  heating  in  farrowing  houses  represents  a  large 
proportion of total electricity use.  

For feed preparation, the total energy use is considered to be between 15 and 22 kWh/tonne of 
meal  produced  where  a  hammer  mill  with  pneumatic  transfer  is  used  to  mill  cereals. 
Pelletisation  or cubing  of the  feed  on farm  will double  the input, requiring  about  20 kWh  per 
tonne. Electrical consumption due to feed distribution  is quite low in the case of dry feed but 
can be significant in the case of wet feed [ 432, BPEX 2010 ]. 

Intensive Rearing of Poultry or Pigs 

167 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Pig rearing on litter is associated with less energy use because forced ventilation and heating are 
commonly  applied  only  to  the  farrowing  stage;  therefore  fuel  oil  is  the  main  type  of  energy 
consumption  for  carrying  out  the  activities  of  litter  spreading  and  cleaning.  As  reported  from 
France,  the  average  energy  consumption  levels  are  206 kWh/sow  per  year  (10.8 kWh  per  pig 
produced)  for  integrated  farms,  and  11.1 kWh/pig  produced  for  farms  with  the  post-weaning 
and fattening rearing stages only; these results are associated with the energy consumed due to 
the  use  of  litter,  without  including  other  forms  of  energy  consumption  (e.g.  electricity 
consumption) [ 344, ADEME 2008 ]. 

3.2.4 

Other inputs 

3.2.4.1 

Bedding (litter) 

The amount of litter used depends on the animal species, the housing system and the farmers’ 
preferences. Use of litter (bedding material) is normally expressed in kg per animal (per year). 
Examples  of  typical  amounts  of  bedding  material,  for  different  animal  categories,  housing 
systems and operating conditions, are reported in Table 3.30 and Table 3.31. Amounts used may 
increase  for  both  layers  and  pigs,  where  regulations  on  animal  welfare  and  market  demands 
require more use of litter-based housing techniques. 

Table 3.30  Typical amounts of bedding materials applied in France in pig housing systems 

Animal category 

Litter management  

Fattening pigs 

Sows 

Deep litter (straw) 
Littered floor (straw) 
Deep litter (60 to 80 cm of sawdust)  
Deep litter (20 cm of sawdust)  
Deep litter (straw) 
Littered floor (straw) 
Deep litter (straw) 

Weaners 
Source: [ 262, France 2010 ][ 263, France 2010 ]  

Typical amounts used 
kg/animal 
50–80 
30–50 
50–60 
20–40 
900 
637 
10–15  

168 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.31:  Typical amounts of bedding material used in poultry and pigs housing systems 

Animal 
species 
Poultry 

Layers 

Housing system 

Litter used 

Typical amounts used 
(kg/animal/yr) 

Deep litter on all or part of the 
area, with or without veranda 
and outdoor run 
Deep litter with forced air 
drying system with vertical 
tubes 

Chopped straw, wood shavings 

0.16–0.5 

Sand 

Wood shavings 

0.075 

2.5 

Pullets  Deep litter 

Broilers 

Deep litter, with or without 
veranda and outdoor run 

Ducks  Deep litter 
Turkeys  Deep litter 
Pigs 

Chopped straw, wood shavings 
Chopped straw (concrete floor) 
Chopped straw, wood shavings 
(clay floor) 

Peat 

Wood shavings 
Chopped straw 
Chopped straw, Wood shavings 

Sows 

Weaners 

Fattening 
pigs 

Individual pen for farrowing 
Deep litter for mating/gestating 
Plain floor with yard 
Individual pen with partly 
slatted floors and vacuum 
removal, for mating/gestating 

Deep litter on solid floor 

Kennel housing with partly 
slatted floor 
Plane floor with yard 

Deep litter on solid floor 

Straw 

Straw 

Plane floor with yard 

Straw 

slatted 
Partly 
vacuum removal 

floor  with 

2.3 
0.3–0.59 
1.1–1.9 (1) 
(average 1.7) 
0.096 (free-range) 
1.66 (closed housing) 
0.067 
7–28 
2–5.8 

180 
640 
300–450 (average 420) 

4 

40–60 
(average 53) 

26 

35 
275–400 
(average 350) 
250–300 
(average 275) 

8.7 

(1) Range derived from reported use of 4 to 7 kg per m2 per batch in France [ 500, IRPP TWG 2011 ], a standard 
density of 22.8 birds/m2 [ 418, ITAVI 2010 ] and 6.15 production cycles per year [ 328, CORPEN 2006 ]. 
Source:  [  87,  Germany  2010  ]  [  144,  Finland  2010  ]  [  145,  Finland  2010  ]  [  97,  UK  2010  ]  [  96,  UK  2010  ] 
[  116,  Germany  2010  ]  [  117,  Germany  2010  ]  [  193,  Germany  2010  ]  [  191,  Germany  2010  ] 
[  181,  Germany  2010  ]  [  183,  Germany  2010  ]  [  185,  Germany  2010  ]  [  276,  Finland  2010  ] 
[  60,  Germany  2010  ]  [  61,  Germany  2010  ]  [  62,  Germany  2010  ]  [  64,  Germany  2010  ] 
[  65,  Germany  2010  ]  [  66,  Germany  2010  ]  [  71,  Netherlands  2010  ]  [  72,  Netherlands  2010  ] 
[  109,  Netherlands  2010  ][  49,  Germany  2010  ]  [  81,  Germany  2010  ]  [  172,  Germany  2010  ] 
[  161,  Germany  2010  ]  [  157,  Germany  2010  ]  [  229,  Finland  2010  ]  [  119,  Germany  2010  ] 
[ 624, IRPP TWG 2013 ] [ 500, IRPP TWG 2011 ] 

3.2.4.2 

Cleaning material 

Cleaning  material  (detergents)  are  used  with  water  and  will  end  up  in  waste  water  treatment 
facilities or in the slurry. A variety of detergents are used for cleaning the housing. Very little 
information  is  available  on  the  amounts  used.  For  poultry,  a  concentration  of  one  litre  of 
disinfectant per m3  was reported, but for pigs, quantification is considered to be very difficult 
and no representative data have been reported. The use of veterinary hygiene biocidal products 
is regulated by Directive 98/8/EC concerning the placing of biocidal products on the market and 
Commission Regulation 2032/2003/EC. 

Intensive Rearing of Poultry or Pigs 

169 

Chapter 3 

3.3 

Excretion and emission levels 

The majority of emissions from the main activities on any poultry or pig farm can be attributed 
to  the  amount,  structure  and  composition  of  manure.  From  an  environmental  point  of  view, 
manure is the most important residue to be managed on farm. This section therefore starts by 
presenting  an  overview  of the  characteristics  of  poultry  and  pig  manure  before presenting  the 
emission levels of the on-farm activities which involve manure management. 

Emissions are presented as ranges rather than as single averages (mean values). On a national 
basis, emissions will vary within different ranges, but it is assumed that similar factors apply. 

3.3.1 

Excretion of nutrients and manure generation 

This section reports on the excretion levels and nutrient contents of manure. Generally, the kind, 
quantity,  and  composition  of  the  manure  depend  on  the  animal  species,  the  age  and  the 
performance of the animals, the feed ration, and the housing techniques applied. 

The  properties  of  manure,  expressed  in  dry  matter  (DM)  content  (expressed  in  %)  and  the 
concentration  of  nutrients  (N,  P,  etc.),  are  mainly  affected  by  the  quality  of  feed  and  by  the 
efficiency  with  which  the  animal  can  convert  feed  into  product  (feed  conversion  ratio).  The 
efficiency of protein utilisation depends on the dietary composition and the physiological status 
or the growth stage of the animals. As feed characteristics vary considerably, the concentrations 
of nutrients in fresh manure will show similar variations. Measures applied to reduce emissions 
associated  with  collection  (housing),  storage  and  the  processing  of  manure  will  affect  the 
structure  and  composition  of  manure,  and  in  the  end  will  influence  the  emissions  associated 
with landspreading. 

Models and tables are available in various Member States to estimate how manure production 
and nutrient content vary with the production stage and the composition of the diet. These tools 
can be used to allow estimation of nitrogen and phosphorus outputs through landspreading. The 
different  methods  used  for  the  assessment  of  excretion  result,  in  general,  in  different 
calculations between Member States. 

An example of a model used to estimate animal excretion, reported by Belgium, is presented in 
Table 4.6.  With  a  knowledge  of  the  composition  of  the  feed,  the  model  allows  for  the 
identification  of  the  potential  excretion  levels  of  total  N  and  P2O5  [  506,  TWG  ILF  BREF 
2001 ]. Based on continuous improvements in feed quality and feed conversion, updates of the 
calculation parameters can be derived. The conversion factor between P and P2O5 is P x 2.2915

Several mathematical models have been developed to predict pig excretion. As an example, one 
calculation  tool  for  fattening  pigs  is  based  on  the  following  simple  approach  [  610,  Fefana 
2012 ]:  

Nutrient Ingested (NI) – Nutrient Retained (NR) = Nutrient Excreted (NE) 

The  calculation  of  nitrogen  retention  in  the  animal  body  tissues  is  based  on  the  following 
equation [ 611, C.Rigolot et al. 2010 ]: 

Equation 3.1:   Nbody = [exp(−0.9892−0.0145*Lean %)*EBW^(0.7518+0.0044*Lean %)]/6.25 

where: 

Lean % = percentage of lean meat at slaughter weight; 
EBW = Empty Body Weight (0.96  body weight). 

170 

Intensive Rearing of Poultry or Pigs 

Chapter 3 

This  tool  can  also  calculate  the  excreted  phosphorus,  copper  and  zinc  contents,  taking  into 
account specific conditions of each farm (observed or calculated feed intake, dietary content of 
feed, weight gain, production cycles, initial and final weight of animals, one-phase or two-phase 
feeding). 

A methodology has been developed, within an EC-funded study, to assist individual producers 
in calculating manure coefficients for different animal categories, taking into account the animal 
type, diet and management practices [ 558, COM 1999 ]. The methodology is flexible enough to 
accommodate the variations in environmental conditions and farming practices within the EU. 
Table 3.32  summarises  the  ranges  of  calculated  coefficients  for  animal  excretion,  adapted  to 
different animal categories. 

Table 3.32:  Nitrogen excretion standards calculated for different animal categories 

Animal 
category 

Sows with 
piglets 
(till 25 kg) 

Nitrogen 
excretion  
(kg/ap/yr) 
Source: [ 558, COM 1999 ] 

21–32 

Fattening pigs 
(25–105 kg) 

Laying 
hens 

Broilers 
(1.8 kg) 

Ducks 
(3.3 kg) 

Turkeys 
(13 kg) 

7.5–13.1 

0.35–0.82 

0.23–0.52 

0.41–0.97 

0.9–1.68 

3.3.1.1 

Levels of excretion and characteristics of poultry manure 

Depending on the housing system and the way of collecting manure, different types of poultry 
manure are produced:  

 

 

 

 

wet (fresh) manure from laying hens with a DM content of 25–28 %; 

wet manure from ducks with a DM content of 0–20 %; 

dry manure (> 45 % DM) from layers in housing where drying is applied; 

deep litter (50–80 % DM) from laying hens, broilers, turkeys and ducks; 

Manure with a dry matter content between 20 % and 45 % is difficult to handle, and in practice 
water may be added to enable pumping as slurry. Deep litter is manure mixed with the bedding 
on which animals are kept on concrete or slatted floors. The DM content is important, as with 
increasing DM content, emissions of NH3 will decrease. Calculations showed that, with quick 
drying to a DM content of > 50 %, the emissions of NH3 (g/hr) were reduced to less than half 
the emissions of those from manure with a DM content of < 40 %.  

Feed type, housing system (manure drying and the use of litter) and poultry breeds are factors 
that account for the variation in the manure composition. With respect to feeding, it is clear that 
the higher the protein level in feed, the higher the nitrogen levels in manure. For the different 
poultry species, nitrogen concentration levels vary within a similar range, also as a consequence 
of manure management (see Table 3.38).  

In the next tables, examples of emission levels for excreted nitrogen, phosphorus and metals are 
reported  for  different  EU  Member  States.  The  quantities  of  various  elements  (nutrients  and 
metals)  excreted  with  the  manure,  for  different  poultry  species,  reported  from  France,  are 
presented in Table 3.33. 

Intensive Rearing of Poultry or Pigs 

171 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Excretion level (g/bird place/year) (1)

Chapter 3 

Table 3.33:  Excretion levels of different elements in poultry manure, in France 

Poultry category 

Production 
cycles per year 

Weight 
(kg) 
1.88 
1.91 
4.52 
9.7 
12.56 
4.8 
3.17 

CaO 

Standard broilers 
32 
Laying hens 
860 
Turkeys (female) 
418 
Turkeys (mixed) 
346 
Turkeys (male) 
398 
Barbary ducks 
235 
Pekin ducks 
179 
(1) Values are derived from original data expressed as g/bird, using the given production cycles. 
Source: [ 633, ITAVI 2013 ] 

Nitrogen  P2O5 
95 
380 
790 
568 
569 
294 
275 

K2O 
191 
248 
844 
598 
691 
357 
302 

311 
779 
1 352 
1 010 
1 159 
735 
491 

6.35 
1 
7.6 
2.47 
2.35 
3.5 
5.11 

Cu 

0.35 
0.57 
1.53 
1.07 
1.43 
0.71 
0.67 

Zn 
1.46 
3.38 
6.32 
5.22 
6.09 
3.42 
2.86 

Examples of excretion levels concerning total nitrogen and phosphorus, reported from Ireland, 
Belgium (Flanders) and Italy, are presented in Table 3.34. 

Table 3.34:  Examples  of  excretion  levels  for  total  N  and  P,  from  Italy,  Ireland  and  Belgium 

(Flanders) 

Poultry type 

Total nitrogen 
(kg/bird place per year) 

Laying hens 

Ireland 
0.56 

Italy  Belgium (Flanders) 
0.66 

0.81 

Broilers 

0.24 

0.36 

NI 
Turkeys 
NB: NI = no information provided. 

1 

0.61 

1.7 

Total phosphorus (as P2O5) 
(kg/bird place per year) 
Ireland  Belgium (Flanders) 

0.12 

0.09 

0.4 

0.45 

0.26 

1.05 

Source: [ 612, TWG comments 2012 ] [ 666, Belgium Flanders 2011 ] 

Calculated  values  for  broilers'  excretion  in  Denmark,  based  on  the  national  normative  system 
for 2014, are shown in Table 3.35. 

Table 3.35:  Standard values for excretion of broilers in Denmark (reference year 2014) 

Age at slaughter (days) 

Production parameters 

40 
2.55 
Live weight at slaughter (kg) 
4.35 
Feed consumption, per bird produced (kg) 
19.8 
Protein content in feed (%) 
7.9 
Number of batches per year 
Number of birds produced per m2 per batch 
15.7 
Number of birds produced per m2 per year 
124 
N excreted (kg per animal place per year) (1)
0.507 
(1) Values calculated from the original figures on the basis of the number of batches per year. 
Source: [ 612, TWG comments 2012 ] [ 653, Denmark 2014 ] 

30 
1.63 
2.45 
20.2 
10.1 
24.5 
249 
0.324 

32 
1.81 
2.77 
20.1 
9.6 
22.1 
212 
0.351 

35 
2.09 
3.33 
20.0 
8.9 
19.1 
170 
0.409 

Calculated excretion  levels for different poultry species in the Netherlands, based on standard 
data from 1999–2008, are presented in Table 3.36, together with the relevant parameters used in 
the calculation.  

172 

Intensive Rearing of Poultry or Pigs 

Table 3.36:  Calculated  excretion  levels  for  different  poultry  categories,  in  the  Netherlands 

Chapter 3 

(reference year 2008) 

Poultry 
categories 

Broilers 
Broiler breeders 
(< 18 weeks) 

Broiler breeders 
(> 18 weeks) 

Production 
cycle 

days 

41.8 

126 

298 

Initial and 
final weight 
kg + egg 
production 
0.42–2.23 
0.42–2 (hens) 
2.75 (cocks) 
2–7.75 (hens) 
3.7–4.8 (cocks) 
+ 11.9 kg eggs 

119 

Laying hens 
(< 18 weeks) 
Laying hens 
(> 18 weeks) 
Male turkeys 
Ducks 
NB: NI = no information provided.  
Source: [ 613, UR Wageningen 2012 ] 

129.5 
46 

409 

0.35–1.47 

1.47–1.76 
+ 17.3 kg eggs 
0.57–15 
0.56–3.21 

Feed 
conversion 
kg feed/kg 
growth 
1.8 

NI 

NI 

NI 

NI 

2.65 
2.22 

Total 
feed use 

N 
excreted 

P2O5 
excreted 

K2O 
excreted 

kg/yr  kg/ap/yr  kg/ap/yr  kg/ap/yr 

34.5 

20.7 

0.53 

0.33 

0.19 

0.2 

0.26 

0.16 

57.3 

1.12 

0.55 

0.44 

17.3 

0.34 

0.17 

0.14 

41.9 

112 
56.6 

0.75 

1.71 
0.76 

0.39 

0.87 
0.36 

0.33 

0.9 
0.48 

Data  concerning  the  quantity  of  manure  and  total  nitrogen  produced  by  different  poultry 
categories, reported from the UK, are presented in Table 3.37. 

Table 3.37:  Nitrogen and excreta production by poultry type in the UK (reference year 2012) 

Poultry 

Laying hens (cage) 
Laying hens (non-cage) 
Broilers 
Pullets 
Broiler breeders 
Turkeys (male) 
Turkeys (female) 
Ducks 
Source: [ 614, UK 2013 ] 

Total N produced 
(kg/ap/year) 
0.67 
0.75 
0.4 
0.33 
1.02 
2.18 
1.46 
1.71 

Manure output 
(kg/day) 
0.12 
0.12 
0.07 
0.04 
0.12 
0.18 
0.13 
0.1 

The quantity of manure produced as well as the nutrients content in manure after housing and 
before landspreading (after storage) are reported from France and presented in Table 3.38. 

Intensive Rearing of Poultry or Pigs 

173 

 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.38:  Composition  and  production  of  manure  from  different  poultry  species  and  manure 

management in France 

Manure produced 

Cycle
s per 
year 

Animal 
density 
(initial) 

Nutrient content in the manure  
(kg/tonne) 

kg/m2 
per year 

DM 
(%) 

No 

animal 
per m2 

N 

P2O5  K2O 

Ca
O 

Mg
O 

Animal 
production 

Type of 
manure 

Wet droppings 
Pre-dried 
droppings on 
belt 
Dried 
droppings in 
deep pit 
Dried 
droppings 
under shed 
Slurry 
Aviary 
Slurry 
Solid manure 
from housing 
Solid manure 
after storage 
Solid manure 
from housing 
Solid manure 
after storage 
Solid manure 
from housing 
Solid manure 
after storage 
Solid manure 
from housing 

Laying hens 

Ducks 

Standard 
broilers 

Heavy 
broilers 

Turkeys 

kg/bird 
place 
per 
year (1) 
NI 

30–40 

NI 

NI 

25 

40 

15–17 

NI 

80 

15–17 

70 
NI 
82 

5 

5 

NI 

NI 
NI 
NI 

120 

120 

80 

10 
33–44 
10–15 

75 

75 

1 

1 

1 

1 

1 
1 
4.9 

6.15 

6.15 

12–14  130–150 

70 

3.25 

12–14  130–150 

70 

3.25 

19–22  150–170 

65 

2.6 

19–22  150–170 

65 

2.6 

Guinea 
fowl 
(1) Values calculated on the basis of the reported data. 
NB: NI = no information provided. 

110–130 

7–8 

70 

3.63 

16.3 

NI 

NI 

15 

22 

14 

20 

12 

40.5 

3 

12 

50 

4.8 

NI 

30 

40 

28 

60 

8 

NI 

40 

40 

28 

60 

8 

NI 
NI 
14.5 

22 

22 

11 

11 

7.8 

7.8 

6.8 

9.5 

15–28  10–12 

5.9 

29 

22 

20 

15 

27 

21 

32 

5.9 

25 

23 

18 

17 

27 

25 

25 

16.2  1.2 
5.5 
7–8  NI  2–3 
6 
4.1 

1 

20 

14.5  3.7 

18 

11 

2.8 

15 

10 

2.5 

14 

7.5  1.9 

20 

23.5  3.7 

18 

18.2  2.8 

20 

18 

2 

Source: [ 258, France 2010 ] [ 328, CORPEN 2006 ] [ 434, ITAVI 2001 ] 

3.3.1.2 

Levels of excretion and characteristics of pig manure 

The annual amount of pig manure, urine and slurry that is produced varies by pig category, the 
nutrient  content  of  the  feed  and  the  drinking  system  applied,  as  well  as  by  the  different 
production  stages  with  their  typical  metabolism.  During  the  post-weaning  period,  feed 
conversion  and  live  weight  gain  primarily  affect  the  outputs  per  animal,  whereas  growth  rate 
and muscle percentage are less important. For sows, outputs are not influenced by performance 
when  expressed  per  animal,  but  can  vary  a  lot  when  expressed  per  piglet.  The  length  of  the 
production period and the feed to water ratio are important factors that further account for the 
variation  observed  in  amounts  of  slurry  per  year  (see  Table 3.39).  With  higher  slaughter 
weights, higher levels of slurry generation are found. 

174 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 3 

Table 3.39:  Range of levels reported for daily and annual production of manure, urine and slurry 

by different pig categories 

Pig category 

Gestating sows 

Farrowing sows (1) 

Weaners (2) 

Production 
(kg/head/day) 

Production  
(m3/head) 

Manure 

Urine 

Slurry 

Per month 

Per year 

2.4 

5.7 

1 

2.8–6.6 

5.2–9 

0.16–0.28 

10.2 

10.9–15.9 

0.43 

0.4–0.6 

1.4–2.3 

0.04–0.05 

1.9–3.3 

5.1–5.8 

0.5–0.9 

Finishers (85–120 kg) 

2–4.1 

Finishers (160 kg) 

NI 

1–2.1 

NI 

Gilts 
(1) Water intake varies with drinking system. 
(2) Feeding and drinking system account for variation. 
NB: NI = no information provided. 

2 

1.6 

3–7.7  

10–13 

3.6 

0.09–0.26  

1.1–3.1  

NI 

0.11 

NI 

1.3 

Source: [ 44, IKC 1993 ] [ 394, Smith et al. 2000 ] [ 411, Ireland 2001 ] [ 289, MLC 2005 ] 

The  following  remarks  can  be  made  on  the  variation  in  the  nutrient  composition  of  manure. 
Feed composition and the level of feed conversion ratio (FCR) determine the nutrient levels of 
pig  manure.  Feed  utilisation  may  vary,  but  advances  in  the  understanding  of  pig  metabolism 
make it possible to manipulate the composition of manure by adapting the nutrient content of 
the  feed  and  using  ingredients  which  improve  feed  utilisation  by  the  animals.  FCRs  vary 
between the different stages of production, e.g. finishing pigs have FCR levels ranging between 
2.5 and 3.1. 

Important  factors  for  the  level  of  excretion  of  nitrogen  and  phosphorus  are  N  and  P 
concentration in the feed, animal production type, and stage of the rearing cycle. Many reports 
clearly show that lower nitrogen levels in manure result from lower crude protein (CP) levels in 
feed. With a lower consumption and an unchanged retention, nitrogen losses are considerably 
reduced (see Table 3.40). 

Table 3.40:  Example  of  effect  of  reduced  CP  levels  in  feed  for  growers  and  finishers  on  daily 

consumption, retention and losses of nitrogen 

Animal 
category 

Low CP 
48.0 
57.1 
105.1 
88 

Growers 
Finishers 
Total 
Relative (%) 
Source: [ 28, FORUM 2001 ] 

Consumption 

Retention 

Losses 

Level of nitrogen (g/d) 

High CP 
55.6 
64.2 
119.8 
100 

Low CP 
30.4 
36.1 
66.5 
99 

High CP 
32.0 
35.3 
67.3 
100 

Low CP 
17.5 
21.0 
38.5 
73 

High CP 
23.7 
28.9 
52.6 
100 

The  annual  excretion  of  nitrogen  and  phosphorus  by  farrowing  sows  is  the  result  of  the 
excretion of both sow and piglets up to weaning, but varying litter size has a minor influence as 
illustrated with an example from the Netherlands (see  Table 3.41). The data clearly  show that 
excretion  is  influenced  by  the  content  of  nitrogen  in  the  feed,  rather  than  by  differences  in 
technical  performance  (number  of  pigs).  Nitrogen  utilisation  efficiency  is  considered  to  be 
highest by farrowing sows and piglets just after weaning. 

Intensive Rearing of Poultry or Pigs 

175 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.41:  Average excretion of nitrogen (kg per year) in housing with a breeding sow (205 kg) 

and different numbers of piglets (up to 25 kg) at weaning 

Average number of weaners 

17.1 

21.7 

25.1 

N1 

N2 

N1 

N2 

N1 

N2 

27.4 
20.4 
23.9 

29.0 
22.0 
25.5 

N excretion factor 
Piglet feed 
Sow feed – pregnant 
Sow feed – lactation 
N excretion 
N excretion (kg/yr) 
26.6 
26.2 
NB:  N1  =  higher  nitrogen  content  in  feeds;  N2  =  lower  nitrogen  content  in 
feeds. 
Source: [ 399, ID Lelystad 2000 ] 

27.4 
20.4 
23.9 

27.5 
20.4 
23.9 

29.0 
22.0 
25.5 

29.0 
22.0 
25.5 

26.7 

28.7 

29.5 

29.5 

Compared  to  the  gestation-farrowing  phases,  the  growing-finishing  stages  are  biologically 
inefficient. In addition, the protein efficiency is lower for heavier live weights, as can be seen 
for the Italian heavy pig that is reared up to an average final weight of 160 kg (see Table 3.42). 
Since the growing and finishing phases (together fattening) account for the major contribution 
of excreted nitrogen in a closed cycle farm (77–78 %), the most efficient measures for abating 
the nitrogen emissions are those that are taken in these categories. The ratio of nitrogen excreted 
to  nitrogen  ingested  for  fattening  pigs  is  generally  high,  e.g.  around  65 %,  on  a  closed  cycle 
farm.  

Table 3.42:  Nitrogen retention in different growing phases of fattening pigs (Italian data) 

Nitrogen balance 
(g/head per day) 

Nitrogen ingested 
Nitrogen excreted 
Nitrogen retention (%) 
(N ingested  N excreted)/N ingested 
Source: [ 391, Italy 1999 ] 

Fattening phase (kg) 
80–120 
69.3 
45.7 

120–160 
61.3 
40.7 

40–80 
40.9 
25.3 

38.1 

34.1 

33.6 

The  applied  fattening  method  is  very  important.  Whereas  in  Italy  1.5  fattening  cycles  are 
possible over 1 year, in other European Member States it is common to have between 2.5 and 3 
rounds  of  fattening  with  different  farming  systems,  leading  to  weights  between  90 kg  and 
120 kg.  The  associated  annual  level  of  nitrogen  excretion  in  Italy  for  a  fattening  period  from 
40 kg to 160 kg is reported as 15.4 kg N/animal place/year [ 391, Italy 1999 ].  

In France, where it is common to have three cycles for fattening pigs per year and six cycles for 
weaners, the levels of nitrogen excretion that are possible with standard and two-phase feeding 
are those shown in Table 3.43. 

176 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 3.43:  Standard level of nitrogen excretion in kg/animal place/year, in France  

Chapter 3 

N excretion 

Pig category 

Sows (1) (kg/animal place/year)  
Weaners (8–30 kg) (kg/animal) (2) 
Fattening pigs (30–112 kg) (kg/animal) (3)(4) 
(1) For 1 200 kg of feed/sow per year. 
(2) Feed conversion of 1.74. Values calculated on the basis of 6.5 cycles per year. 
(3) Feed conversion of 2.86. Values calculated on the basis of 3.2 cycles per year. 
(4) For pigs heavier than 112 kg, excretion is increased by 0.067 kg N/cycle  for each additional kg of live 
weight for standard feeding and by 0.06 kg N/cycle for each additional kg of live weight for two-phase 
feeding. 

Two-phase feeding 
20.4 
3.64 
12.12 

Standard feeding 
24.6 
4.03 
14.6 

Source: [ 258, France 2010 ] 

The evolution of ammonia volatilisation in relation to the total nitrogen excreted is ultimately 
different depending on the animal category, as is shown in Figure 3.3. 

Source: [ 258, France 2010 ] [ 436, Guingand N. 2002 ] 

Figure 3.3:  Evolution  over  time  of  ammonia  volatilisation  (percentage  of  total  nitrogen)  for 

different pig categories  

Similarly  to  nitrogen  excretion  levels,  phosphorus  excretion  varies  with  the  total  phosphorus 
content  in  the  diet,  the  genetic  type  of  the  animal  and  the  weight  class  of  the  animal  (see 
Table 3.44). Availability of phosphorus in the diet is an important factor. In fact, measures to 
improve  phosphorus  availability  (phytase)  show  reduced  phosphorus  emissions  in  manure. 
Retention of phosphorus is highest in weaners. 

Intensive Rearing of Poultry or Pigs 

177 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.44:  Example of consumption, retention and excretion of phosphorus in pigs (kg per pig) 

Days  Consumption  Retention 

Excretion 

Faeces  Urine  Total  % 

0.78 
1.58 
2.36 
5.38 

27 
133 
160 
365 

Sow 
Lactation 
Dry + gestating 
Total/cycle 
Total/year 
Pig 
Piglet (1.5–7.5 kg) (1) 
Weaner (7.5–26 kg) 
Finisher (26–113 kg) 
(1)  Based on 21.6 piglets/sow per year. 
(2)  Feed intake 2.03 kg/day and 4.8 g P/kg feed. 
(3)  Feed intake 2.03 kg/day and 2.1 g P/kg feed. 
Source: [ 538, Netherlands 1999 ]  

27 
48 
119 

0.25 
0.157 
1.16 (2) 

0.35 
0.24 
0.59 
1.35 

0.06 
0.097 
0.43 

0.34 
0.79 
1.13 
2.58 

0.09 
0.55 
0.64 
1.46 

0.12 
0.053 
0.65 (3) 

0.07 
0.007 
0.08 

0.43 
1.34 
1.77 
4.04 

0.19 
0.06 
0.73 

55 
85 
75 
75 

75 
38 
63 

After the nitrogen and phosphorus content, the excretion of potassium, magnesium oxide and sodium 
oxide are also relevant for manure landspreading, see Table 3.45. 

Table 3.45:  Average composition of different types of pig manure and standard deviation (in brackets) in 

kg per 1 000 kg of manure 

DM  OM  Ntotal  Nm  Norg 

P2O5 

Finishers 

Sows 

Average slurry 
Diluted slurry 

90 
(32) 
55 
(28) 
NI 
NI 

Finishers 
Sows 

20–40 
10 

60 

35 

NI 
NI 

5 
10 

kg per 1 000 kg of manure 

Slurry 
3.0 
4.2 
(1.1)  (1.3) 
2.5 
1.7 
(0.8)  (1.0) 
NI  NI 
NI  NI 

7.2 
(1.8) 
4.2 
(1.4) 
9.6 
4.3 
Liquid fraction of solid manure 
0.4 
0.1 

4.2 
(1.5) 
3.0 
(1.7) 
4.8 
3.8 

4.0–6.5  6.1 
1.9 

2.0 

7.2 
(1.9) 
4.3 
(1.4) 
5.9 
2.6 

K2O  MgO  Na2O  CaO  Density 
kg/m3 

1.8 
(0.7) 
1.1 
(0.7) 
1.7 
1.2 

NI 
0.9 
(0.3)  NI 
0.6 
NI 
(0.2)  NI 
5.2 
NI 
3.6 
NI 

1 040 
NI 
NI 
NI 
NI 
NI 

0.9–2.0  2.5–4.5  0.2–0.4  1.0 
0.2 

0.9 

2.5 

0.2 

NI 
NI 

1 010 
NI 

Pigs (straw) 

230–250  160  7.0–9.1  1.5 

6.0  7.0–10.9  3.5–11.2  0.7–3.1  1.0  6–7.5 

Solid manure 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

7.6 

8.8 

6.5 

8.2 

6.4 

335 

398 

278 

336 

12.9 

14.7 

10.2 

11.1 

NI  NI 

NI  NI 

NI  NI 

Sawdust litter 
Wood shavings 
litter 
Compost of deep 
litter 
Compost of 
scraped straw 
litter 
Compost of 
scraped litter 
and straw 
Compost of 
mechanically 
separated solid 
fraction of slurry 
NB: OM = organic matter; Nm
Source: [ 44, IKC 1993 ] [ 389, ADAS 2001 ][ 258, France 2010 ] [ 429, Texier et al. 2004 ] [ 433, CORPEN 2006] 

 = organic nitrogen; NI = no information provided. 

 = metabolic nitrogen; Norg

NI  NI 

NI  NI 

NI  NI 

11.0 

18.3 

20.8 

14.9 

10.5 

43.4 

3.0 

4.0 

7.7 

2.0 

7.2 

2.6 

3.0 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

8 

5 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

178 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
The  standard  quantities  of  nitrogen  and  manure  excreted  by  different  pig  categories  in  the  UK  are 
presented in Table 3.46.  

Chapter 3 

Table 3.46:  Pig  excreta  and  nitrogen  produced  in  relation  to  different  pig  categories  and  nutritional 

measures, in the UK  

Pig category 

N excretion 
(kg/ap/year)  

Weaners (< 20 kg) 
Sows 
Fattening pigs (20–50 kg) 
Fattening pigs (50–80 kg) 
Fattening pigs (80–110 kg) 
Fattening pigs (> 110 kg) 
Gilts 
Boars 

Source: [ 614, UK 2013 ] 

3.4 
18.1 
8.9 
13.3 
15.4 
15.4 
15.5 
21.8 

Manure output (kg/animal/day) 
Slurry 
1.3 
11.1 
3.8 
3.8 
5.2 
5.2 
5.7 
8.8 

Solid manure (FYM) 
1.5 
12.5 
4.3 
4.3 
5.9 
5.9 
6.4 
10 

From the Netherlands, calculated excretion rates per pig category and information on the physiological 
data associated with the calculations are presented in Table 3.47.  

Table 3.47:  Calculated annual excretion of nutrients per pig category, in the Netherlands (reference year 

2008) 

Production 
cycle 

Initial weight – 
Final weight 

Growth 
rate 

Total 
feed use 

N excreted 

P2O5 
excreted 

K2O 
excreted 

days 

kg 

kg/day 

kg/yr 

kg/ap/yr 

kg/ap/yr  kg/ap/yr 

117 

25.3–116.6 

0.778 

781 

12.9 

25.3–140 

0.704 

804 

13.5 

5 

5.9 

8.1 

8.1 

140–230 (1) 

(2) 

1941 

30.8 

14.7 

19.4 

Pig 
category 

Fattening 
pigs 

163 

Gilts - young 
boars 
Breeding 
sows 
(mixed) 
(1) 25.3 kg final weight of weaners. 
(2) 26.5 reared piglets per sow. 
NB: NI = no information provided. 

NI 

Source: [ 613, UR Wageningen 2012 ]  

Excretion rates per pig category in terms of total nitrogen (kg/year) and total phosphorus (kg/year) are 
presented  in  Table 3.48,  as  reported  by  Ireland  and  Belgium  (Flanders)  and  adopted  in  the  national 
regulations for the implementation of the Nitrates Directive. 

Intensive Rearing of Poultry or Pigs 

179 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.48:  Annual  excretion  rates  and  slurry  generation  for  pig  rearing  units  and  different  pig 

categories, in Ireland and Belgium (Flanders) 

Ireland 

Belgium (Flanders) 

Slurry generation  Annual excretion rate 

Annual excretion rate 
kg N/ap/yr  kg P/ap/yr  kg N/ap/yr  kg P/ap/yr 

Pig category 

Breeding unit (per sow place) 
Integrated unit (per sow place) 
Finishing unit (per pig place) 
Gilts not yet served 
Sows in pig 
Other breeding sows 
Boars 
Fattening pigs > 20 kg 
Fattening pigs < 20 kg 
NB: NI = no information provided. 

m3/ap/yr 
9.048 
16.22–25.12 
1.25–2.76 
1.77 
5.93 
2.48 
2.48 
1.77 
0.67 

35 
87 
9.2 
9.2 
20 
20 
16 
9.2 
3 

8 
17 
1.7 
NI 
NI 
NI 
NI 
NI 
NI 

NI 
NI 
NI 
NI 
24 
NI 
NI 
13.0 
2.18 

NI 
NI 
NI 
NI 
14,5 
NI 
NI 
5.33 
1.53 

Source: [ 615, IE EPA 2012 ] [ 666, Belgium Flanders 2011 ] 

In Denmark, the calculation of standard excretion values is based on a simple balance between input 
and output. The input is derived  from data recorded by farms yearly on feed intake and calculations 
based on the nutrient concentrations in the diets. The nutrient retention is calculated based on standard 
values  obtained  from  literature.  For  farms  using  phase  feeding  and  feed  optimisation  measures,  the 
following values for nitrogen and phosphorus excretion are obtained. Figures from 2014, which reflect 
mostly farms that are using phase feeding and feed optimisation, are presented below in Table 3.49.  

Table 3.49:  Annual excretion rates for different pig categories, in Denmark (reference year 2014) 

Animal category 

Weight 
(kg) 

Number of 
cycles 

32–107 
7.3–32 
NI 
NI 
NI 

Fattening pigs 
Weaners 
Mating and gestating sows 
Farrowing sows (2) 
Sows (4) 
(1) 115 days of gestation. 
(2) Including piglets up to 7.3 kg. 
(3) 31 days of lactation. 
(4) Values derived from individual values for gestating and farrowing sows for 115 days of gestation, 31 days of 

4 
6.5 
(1) 
(3) 
NI 

N excretion 
(kg N/animal 
place/yr) 
11.3 
3.2 
19.7 
33.4 
22.61 

P excretion 
(kg P2O5/animal 
place/yr) 
5.4 
2.1 
9.7 
16.5 
11.14 

lactation and 2.25 litters per year. 

NB: NI = no information provided. 

Source: [ 653, Denmark 2014 ] 

3.3.2 

Emissions from housing systems 

The following sections present the levels of emissions of different pollutants to air from poultry and 
pig  housing  systems.  Emission  data  published  for  individual  housing  techniques  generally  show  a 
large range of variation [ 474, VDI 2011 ]. The lowest levels are generally achieved with additional air 
cleaning techniques (end-of-pipe). 

Emissions  from  animal  housing  facilities  show  great  variability  over  the  course  of  the  day  and  the 
year. The level and variation of emissions to air are determined by many factors, which can be linked 
and can also affect each other. Major factors that influence emissions to air from housing are:  

180 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

 

 

Design and management of the animal housing and manure collection system; 

ventilation system and ventilation rate; 

applied heating and fluctuations of the indoor temperature; 

the growth stage of the animals and different animal activities over the course of the day; 

the amount and quality of manure, which in turn depends on: 

Chapter 3 

o 

o 

o 

o 

o 

o 

o 

feeding strategy; 

feed formulation (protein level); 

application of litter; 

watering and watering system;  

moisture content of manure; 

stocking density; 

animal’s health state. 

Key  emissions  to air  that are  produced in  animal  housing  systems  are  ammonia  (NH3),  odour,  dust, 
methane (CH4) and nitrous oxide (N2O). 

The main source of ammonia is the rapid hydrolysis of urea contained in urine by the urease, leading 
+).  Another  source  of  NH3  is  the  degradation  of  undigested  proteins,  but  this 
to  ammonium  (NH4
pathway is not as fast as the previous. The urease is an enzyme largely present in faecal bacteria and it 
can  be  found  in  abundance  on  fouled  surfaces  like  floors,  pits  and  walls  inside  livestock  buildings. 
Urease activity is affected by temperature; it is low at temperatures below 5–10 °C and above 60 °C. 
Under  practical  conditions,  models  show  an  exponential  increase  of  urease  activity  related  to 
temperature. Urease activity is also affected by pH, with optimum values ranging from 6 to 9, while 
animal  manure  pH  is  usually  buffered  to  between  7.0  and  8.4.  Therefore,  optimal  conditions  for 
complete  urea  hydrolysis  are  largely  met  in  animal  husbandry,  making  the  urea  availability  the 
+ production depends also on manure moisture content, as water is necessary 
limiting factor. The NH4
+  production  is  optimal  between  40 %  and  60 %  moisture  content; 
for  bacterial  activity.  Thus,  NH4
emissions decrease at values above and below this range. Ammonia generation stops below 5–10 % 
moisture content [ 590, Batfarm 2013 ]. 

Ammonia release from manure is also associated with the difference in NH3 concentration between the 
manure and the air above. On the one hand, NH3 concentration in the manure is affected by pH and 
temperature, as described above; on the other hand, NH3 removal from the surface air is governed by 
the  convective  mass  transport  due  to  the  house  ventilation  [  277,  Ji-Qin  et  al.  2000  ].  Due  to  its 
relatively low olfactory threshold, NH3 has a relationship with nuisance odour, at higher than neutral 
pH conditions [ 277, Ji-Qin et al. 2000 ] [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ]. 

Dust emissions originate from the feed, bedding material and from the animal activities. The amount 
of airborne  dust may vary  significantly depending on the type of animal, but also in the course of a 
day.  The  concentration  of  dust  in  animal  housing,  in  particular  the  PM10  fraction,  can  have  a  direct 
negative  effect  on  the  animals  and  humans,  due  to  the  compounds  that the  dust  particles  may  carry 
(bacteria, toxins). Dust also plays an important role as a carrier of odorous compounds. The airborne 
particles  that  can  be  generated  in  livestock  buildings  range  from  non-organic  substances  (e.g.  soil 
material) to organic particles from plants and animals, including dead and living microorganisms, such 
as bacteria, fungi, viruses and parts of these organisms, e.g. endotoxins. These biological components 
are usually named ‘bioaerosols’. The main factors that affect dust emissions are ventilation, activity of 
the animals, type and quantity of bedding, the type and the consistency of feedstuff, and humidity in 
the animal house. 

Intensive Rearing of Poultry or Pigs 

181 

 
 
 
 
 
 
Chapter 3 

More  dust  is  raised  from  bedded  pens  than  from  non-bedded  ones.  The  kind  and  quality  of  litter 
influence  the  emissions.  Finely  structured  material  (e.g.  chopped  straw)  emits  more  particles  than 
coarse material (long straw, wood shavings).  

The indoor dust concentration depends very much on the animal activity. Housing techniques which 
offer the  animals  only  little  freedom  of  motion (e.g. housing  of laying  hens  in enriched  cages)  emit 
less dust than those which provide more freedom of motion (e.g. aviary housing of laying hens). In pig 
housing, airborne particulate matter also depends on the feeding technique and human presence. Each 
time  feed  and  when  the  animals  are  disturbed  (e.g.  during  inspection  rounds),  higher  concentrations 
are measured than at night and in resting phases. The formation of dust can also be reduced, by serving 
liquid, moistened or pelleted feed and by using corn and grass feedstuffs in place  of roughage (hay, 
straw) or by adding dietary fat or oil to dry feed. 

Nitrous oxide formation occurs during incomplete nitrification-denitrification processes that normally 
convert NH3 into N2. Thus, N2O synthesis requires a close combination of aerobic and anaerobic areas; 
in  general,  these  heterogeneous  conditions  are  not  met  with  slurry  but  with  litter.  However,  N2O 
emissions can occur from slurry when a dry crust is formed on the surface, generating anaerobic and 
aerobic  micro-sites.  Because  of  these  numerous  sources  and  different  conditions  that  affect  N2O 
emissions formation, N2O production from manure has a highly random nature, especially with litter 
systems [ 590, Batfarm 2013 ]. 

Methane  production  originates  from  the  anaerobic  degradation  of  organic  matter  performed  by 
mesophilic/thermophilic bacteria with an optimal pH close to neutrality. In pig houses, the sources of 
CH4  emissions  are the animal  digestive  tract  and  the  releases from  the  manure.  The  level  of enteric 
CH4  is  a  function  of  the  fermentative  capacity  of  the  digestive  tract  in  the  animal,  and  the  content, 
source and solubility of dietary fibre. In indoor slurry/manure storage, CH4 release is promoted by high 
temperature, high organic matter content and low oxygen availability. On the contrary, the production 
is inhibited under aerobic conditions or high concentration of ammonium and sulphides. If a surface 
crust  is  formed  on  slurry,  CH4  releases  are  less,  since  the  CH4  produced  can  be  oxidised  into  CO2 
during passage through the crust [ 590, Batfarm 2013 ]. 

A long-term investigation carried out in fattening pig houses, found a clear influence of the average 
daily outside temperature (above 25 °C) on the level of the CH4 emissions. In the same study, it was 
also demonstrated that CH4 emissions were reduced significantly when a complete slurry removal at 
the end of each cycle and subsequent cleaning of the slurry pits were performed [ 444, Haeussermann 
et al. 2006 ]. 

3.3.2.1 

Emissions from poultry housing 

Ammonia  
In  accordance  with  Council  Directive  2007/43/EC,  concentrations  of  ammonia  must  not  exceed 
20 ppm in the house, measured at the level of the birds' heads. According to a study carried out in the 
UK  in  2002,  ammonia  concentrations  in  commercial broiler  houses  appear to  be  consistently  below 
15 ppm [ 149, Robertson et al. 2002]. In the case of reduced ventilation or high humidity, extremely 
high  concentrations  of  ammonia  are  possible  (50–200 ppm)  [  400,  Silsoe  Inst.  1997  ].  In  general, 
peaks in ammonia concentrations are related to poor litter management.  

An example of daily ammonia emission rates for different poultry categories as measured in the UK, 
for  conditions  without  changes  in  the  diet  to  reduce  emissions,  is  described  below  [  151,  Link  CR 
2005 ]:  

 

0.34  g/kg  of  LW/day  for  broilers,  with  significant  farm  variability  ranging  from  0.15 g/kg  of 
LW/day  to  a  peak  measured  value  of  around  1.3 g/kg  of  LW/day;  higher  emission  rates 
coincided with higher moisture contents;  

182 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 3 

 

 

 

values in the range of  0.2–1.8 g/kg of LW/day for laying  hens, depending  on manure storage, 
removal and/or crop age; 

0.14 g/kg of LW/day for turkeys, ranging from 0.05 g/kg of LW/day during winter to 0.4 g/kg of 
LW/day in summer;  
1 g/kg of LW/day for ducks, associated with higher moisture levels in the straw litter. 

Indicative ammonia emission factors reported by various Member States, for the housing of different 
poultry categories, are presented in Table 3.50.  

Table 3.50:  Examples of national ammonia emission factors for poultry housing  

Bird categories 

Country 

Broilers 

Hens in cages (with belts) 

Hens on floor, with manure 
pit 
Hens on floor, with manure 
belts 
Hens in cages  
Hens on floor 
Hens (cage and non-cage 
systems) 

Ammonia emission 
(kg NH3/ap/yr) 
0.039 (1)  
0.094 (2) 
0.117 (1) 
0.085 
0.29 (1) 
0.45 (3) 
0.091 
0.15 (3) 
0.204 (2) 
0.189 (2) 

Source 

[ 614, UK 2013 ] 
[ 616, Spain 2012 ] 
[ 614, UK 2013 ] 
[ 462, VITO 2005 ] 
[ 614, UK 2013 ] 
[ 500, IRPP TWG 2011 ] 
[ 571, Eurich-Menden et al. 2011 ] 
[ 500, IRPP TWG 2011 ] 
[ 616, Spain 2012 ] 
[ 616, Spain 2012 ] 

UK 
ES 
UK 
BE-Flanders 
UK 
FR 
DE 
FR 
ES 
ES 

IE 

0.14 

[ 639, IE EPA 2014 ] 

Turkeys (male) 

[ 571, Eurich-Menden et al. 2011 ] 
[ 614, UK 2013 ] 
[ 571, Eurich-Menden et al. 2011 ] 
Turkeys (female) 
[ 633, ITAVI 2013 ] 
Turkeys (gender mix) 
Ducks 
[ 571, Eurich-Menden et al. 2011 ] 
(1) Values calculated from the mean emissions expressed as g N/LU/d and the live weight coefficients of Table 9.3. 
(2) Values corresponding to the reference system and calculated from kg N-NH3/ap/yr reported. 
(3) EPER values. 

0.68 
0.659 (1) 
0.387 
0.263–0.374 
0.146 

DE 
UK 
DE 
FR 
DE 

Two  indicative,  more  detailed,  examples  of  national  ammonia  emission  factors  for  poultry  houses 
applied in Denmark are presented in Table 3.51. 

Table 3.51:  Ammonia emission factors for different poultry types, in Denmark  

Ammonia emission (1) 

Animal category 

Broilers, 35 days at slaughter 
Broilers, 40 days at slaughter 
Turkeys, females, 112 days at slaughter 
Turkeys, males, 147 days at slaughter 
Ducks, 52 days at slaughter 
Layers in cages with manure belt, 365 feeding days 
Layers, barn, deep litter and manure pit 
Layers,  aviary  (multi-tiered  and  manure  belt),  365 
feeding days 
(1) Calculated from values given as kg NH3-N in the Danish normative system. 
(2) The production cycles have been derived by dividing the breeding time by 365 days and considering 9 days 

kg/1 000 birds produced  
11.82 
15.9 
116.8 
213.2 
42.01 
84.39 
367.8 

kg/ap/year (2) 
0.098 
0.118 
0.352 
0.50 
0.251 
0.084 
0.36 

120.45 

0.12 

between two batches. 

Source: [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ] 

Intensive Rearing of Poultry or Pigs 

183 

 
 
 
 
 
 
 
 
 
 
Chapter 3 

Dust 
In general, dust levels are higher in litter-based systems than in cage systems. Dust may function as a 
carrier for part of the emissions to air, but its correlation with odours is less clear than for pig housing 
[ 438, Lacey et al. 2004 ].  

Studies  carried  out  in  France  in  laying  hen  housing  showed  a  much  higher  dust  concentration  in 
aviaries  than  in  cage  systems.  In  one  particular  study,  average  dust  emissions  (particle  size  < 100 
micrometres) were measured for a period of 5 hours, resulting in 1.8 mg/m3 in cage housing and 15.3 
mg/m3  in  aviaries  [ 367,  Michel  et  al.  2005  ].  Another  study  showed  that  the  daily  average 
concentration of fine dust (particle size < 4 micrometres) in deep litter houses was equivalent to 0.36 
mg/m3, which is significantly higher than the average emission in cage systems, around 0.12 mg/m3. In 
addition, the measured values had a high variability in the case of litter systems (from 0.30 mg/m3 to 
0.42 mg/m3), whereas values from cage systems  were more homogeneous (from 0.10 mg/m3 to 0.14 
mg/m3) [ 660, France 2010 ]. 

Under  UK  conditions,  reported  daily  average  dust  emissions  (with  higher  concentrations  during  the 
day and lower overnight) do not show significant differences between non-cage poultry houses (with 
the  exception  of  a  few  broiler  houses),  with  values  generally  below  0.4  g  per  kg  of  bird  per  day  
[ 151, Link CR 2005 ]. Dust emissions increase with the birds’ growth and activity. During the first 3 
weeks  of  rearing,  young  chicks  are  not  very  active  and  little  dust  is  generated,  but  in  the  following 
stages, the older birds occupy most of the available space, walk more actively and lose feathers. As a 
consequence, more dust is generated. Point source concentrations of inhalable dust at broiler houses 
(at day 30) are about 5–7 mg/m3 [149, Robertson et al. 2002] but average values are between 1 mg/m3 
and 3.5 mg/m3 [ 366, Renault et al 1997 ]. In Austria, an emission factor of 0.1 kg of dust per animal 
place per year is considered for laying hens reared in aviaries [ 373, UBA Austria 2009 ]. 

In duck rearing, an increase in dust emissions with the animals age/live weight is clearly observed, as 
is reported in Table 3.52. 

Table 3.52:  Estimated emissions from fan ventilated littered duck housing in the UK 

Duck age (days) 

20 
27 
34 
41 
47 

NH3 emission 
(g/bird per day) 
0.33 
0.55 
0.82 
1.15 
1.57 

Dust emission 
(g/bird per day) 
0.02 
0.08 
0.12 
0.22 
0.28 

Source: [ 152, Link CR 2006 ] 

The  highest  concentrations  are found  in  guinea fowl houses,  where  indoor  dust concentrations  were 
measured on average 35.7 mg/m3 [ 366, Renault et al 1997 ]. 

Nitrous oxide, methane and other gaseous emissions 
The  development  of  nitrous  oxide  (N2O),  methane  (CH4)  and  non-methane  volatile  organic 
compounds  (NMVOC)  is  associated  with  the  internal  storage  of  manure;  in  general,  their  levels  in 
housing can be considered very low when the manure is frequently removed.  

Hydrogen  sulphide  (H2S)  is  generally  present  in  very  low  quantities,  i.e.  about  1  ppm  [  391,  Italy 
1999 ].  An  overview  of  the  reported  emission  values  (given  as  ranges)  associated  with  housing 
systems for NH3, CH4, N2O, dust and odour, methane, for the different types of poultry, is given in 
Table 3.53. More information on odour emissions is presented in Section 3.3.9. 

184 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 3.53:  Range of reported air emission levels from poultry houses  

Type of poultry 

NH3 

CH4 

N2O 

PM10 

Odour (1) 

kg per bird place per year 

ouE/s per bird  

Chapter 3 

NI 

NI 

0.01–0.04 

0.02–0.15 

0.078–0.2 

0.01–0.15 

0.102–0.68 

0.102–1.53 

0.019–0.36 

0.014–0.21 

0.034–0.078 

0.002–0.180 

0.0017–0.023 

Laying hens – 
Enriched cage 
systems 
Laying hens – 
Non-cage 
systems 
Pullets (cage and 
not cage 
systems) 
Broilers 
Broiler breeders 
Turkeys (female) 
Whole period 
Turkeys (male) 
Whole period 
Ducks 
Guinea fowl (2) 
(1) Odour emissions have been derived from original data expressed in ouE/s per LU. 
(2) Source: [ 43, COM 2003 ] 
NB: Emission levels achieved by air cleaning systems are included. Values derived from EPER are not included;  
NI = no information provided. 

0.004–0.006 (2)  0.009 (2)–0.032 

0.004–0.025 
0.016–0.049 

0.01–0.084 
NI 

0.098–0.49 
NI 

0.004–0.18 
0.025–0.58 

0.05–0.29 
0.80 

0.032–0.7 
0.11–0.93 

0.015 (2) 
0.015  

0.045–0.387 

0.008–0.078 

0.138–0.68 

0.015 (2) 

0.09–0.5 

0.24–0.9 

0.042–0.227 

NI 
NI 

0.71 

0.4 

NI 

NI 

NI 

NI 

NI 

3.3.2.2 

Emissions from pig housing 

Ammonia 
Many factors increase the variability of the level of emissions from pig housing, such as the nutrient 
content of the feed, the indoor climatic conditions, the management of the housing technique and the 
level of maintenance of the housing facilities.  

In slurry-based housing systems, ammonia emissions may vary significantly because of differences in 
the  surface  area  of  the  slurry  channels,  ratio  of  solid  floor  to  slatted  area,  slurry  pH,  TAN 
concentration in the slurry, temperature and ventilation rate. Studies showed that planning the position 
of drinking and feeding areas, the social behaviour in a group and reactions to changes in climate all 
influence the defecating behaviour of the animals and hence can change the emission levels.  

In  particular,  it  is  generally  assumed  that  in  buildings  with  partly  slatted  floors,  the  majority  of  the 
emission arises from the slurry channels and that floor emissions account for between 11 % and 40 % 
of the emission from the pens. The variation on ammonia emissions depends more on the cleanliness 
of the solid floor and the size of the slatted area rather than the quantity of slurry stored beneath the 
slats in partly slatted floors. The magnitude of the soiled area is related to the animal behaviour, which 
can be controlled partly through the design of the pens, the position of feeders and drinkers, and the 
control of the indoor climate [ 439, Sommer et al. 2006 ].  

Normally,  in  ventilated  buildings,  pigs  prefer  to  lie  on  a  warm  solid  floor,  which  contributes  to  a 
tendency  towards  dunging  in  the slatted  floor  area.  Thus,  fattening  pigs  (30–110 kg)  spend  87 %  of 
their time lying, mostly on the solid concrete floor in buildings with a partly slatted floor. However, at 
high  ambient  temperatures,  pigs  prefer  to  lie  on  a  cool  surface,  which  will  be  the  slatted  floor  and, 
consequently, defecate on the warmer (previously lying) surface. This fouling causes an increase in the 
emitting  area,  not  only  from  the  floor  but  also,  to  some  extent,  from  the  fouled  animals  themselves  
[ 439, Sommer et al. 2006 ].  

In a reported example, in pens for group-housed sows designed with functional areas, it was observed 
that care had to be taken to guarantee the accessibility of these areas, as the social order in the group 

Intensive Rearing of Poultry or Pigs 

185 

 
 
 
 
 
 
 
 
 
 
Chapter 3 

prevented younger sows from free and easy access, when older sows blocked small passageways to the 
feeding  and  defecating  areas.  The  young  sows  then  started  to  defecate  outside  the  designed  slatted 
area, causing an increase in ammonia emissions. The use of periodical water shower drizzles has been 
reported as an effective measure to reduce this type of behaviour in the rearing of fattening pigs and 
sows [ 500, IRPP TWG 2011 ].  

Another factor increasing NH3 emission variability from housing is the increase in feed intake during 
the growing period, in particular with fattening pigs, which results in an increased excretion of total 
ammoniacal nitrogen (TAN), leading to a greater emission of ammonia [ 439, Sommer et al. 2006 ]. 
Increasing  the  number  of  animals  per  pen/room,  taking  into  account  animal  welfare  considerations, 
reduces the relative ammonia emissions per unit area [ 439, Sommer et al. 2006 ]. 

In litter-based systems, urine infiltrates the litter (sawdust or straw), thus reducing the surface area in 
contact with the air. Straw also has the effect of reducing the airflow over the emitting surface. At the 
same  time,  dung  can  be  absorbed  by  the  straw  and  transformed  into  organic  nitrogen  by 
microorganisms.  This  would  suggest  that  the  potential  for  nitrogen  losses  via  volatilisation  of  NH3 
from  deep  litter  systems  might  be  smaller  than  from  slurry  systems  due  to  the  immobilization  of 
ammoniacal nitrogen. However, the O2 that diffuses into the porous surface layer is utilised by aerobic 
microbial activity in the litter, resulting in a temperature increase to about 40–50 °C, with consequent 
NH3 losses [ 439, Sommer et al. 2006 ].  

Ammonia emissions may be higher from straw litter floors than from slatted floors, where the straw is 
accumulated  or  removed  at  longer  intervals,  i.e.  once  per  month  [  375,  Philippe  et  al.  2007  ],  or  if 
composting  starts  in  the  straw-based  systems.  If  soiled  bedding  material  is  regularly  removed  and 
replaced (weekly or daily), no significant difference of ammonia and dust emissions should arise from 
straw-bedded  housing  compared  to  slatted  floor  systems  [ 289,  MLC  2005  ]  [  439,  Sommer  et  al. 
2006 ].  

In  houses  where  pigs  are  reared  on  deep  litter  straw  bedding  (i.e.  where  more  straw  is  added  at 
intervals and the manure is removed at the end of the cycle), ammonia emissions can vary from 15–
25 % of the excreted nitrogen to 5–15 %, in the case where bedding exceeds 50–80 kg/animal, or if the 
stocking  density  falls  from  1–1.4  m2/pig  to  2  and  more  m2/pigs  [  378,  Robin  et  al.  2004  ]. 
Nevertheless, the variation in the reported emissions of comparative studies demonstrates that there is 
no consistent difference between slurry-based and deep litter systems [ 439, Sommer et al. 2006 ].  

The  differences  in  the  specific  characteristics  of  the  livestock  and  manure  management  systems,  as 
well  as  different  climatic  conditions  are  reflected  by  differences  in  the  emission  factors  used  by 
Member States. An example of detailed reference emission factors, used in pig housing in the UK, is 
presented in Table 3.54.  

Table 3.54:  Ammonia emission factors for pig housing, used in the UK  

Animal category 

NH3 emission factor  

Sows – straw 
Sows – slats 
Farrowing sows – straw 
Farrowing sows – slats 
Weaners – slats 
Fattening pigs – straw 
Fattening pigs – slats 
Boars – straw 
(1) Values are calculated from the reported emission in g N/LU/d and the average live weight presented in 

kg NH3/ap/yr (1) 
4.47  
3.01 
5.01  
5.32  
0.29 
2.89  
4.01  
5.68  

Average live weight 
kg 
200 
200 
225 
225 
12 
65 
65 
250 

g N/LU/d 
25.2  
17 
25.2  
26.7  
27.7 
50.2  
69.6  
25.2  

Table 9.3. 

Source: [ 614, UK 2013 ] 

186 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
In Germany, the standard emission factor associated with slurry systems for fattening pigs is 2.9 (2.4–
is  applied  but  no  other  mitigation  measures  
6.1) kg  NH3/ap/yr  when  N-adapted  feeding 
[  121,  Germany  2010  ].  Standard  ammonia  emission  factors  for  pig  housing  used  in  Germany  are 
presented  in  Table 3.55;  these  factors  are  not  associated  with  nutritional  measures  nor  ammonia 
mitigation measures. 

Chapter 3 

Table 3.55:  Ammonia emission factors for pig housing by pig category, in Germany  

Pig category 

NH3 emission factor 
(kg NH3/ap/yr) 

Fattening pig farms 
Forced ventilation, liquid manure technique (partially or fully 
slatted floors) 
Forced ventilation, solid manure technique 
Natural ventilation, liquid or solid 
manure technique ((kennel housing, sloped floor housing) 
Outdoor climate house, deep litter technique 
Breeding farms 
All breeding sows including piglets up to 25 kg 
Mating and gestating sows 
Farrowing sows (sows including piglets up to 10 kg) 
Weaners 
Gilts 
Source: [ 474, VDI 2011 ] 

3.64 

4.86 

2.43 

4.2 

7.29 
4.8 
8,3 
0.5 
3.64 

Spain  has  also  compiled  emission  factors  for 
E-PRTR [ 667, Spain 2011 ]. 

the  reporting  obligations  related 

to 

the  

Nitrous oxide and methane  
In  pig  houses  where  no  bedding  is  used,  the  slurry  produced  remains  in  a  predominantly  anaerobic 
+  to  be  nitrified.  As  a  result,  little  or  no  N2O  emissions  are 
state  with  little  opportunity  for  the  NH4
likely to occur from such buildings [ 443, Chadwick et al. 2011 ]. Emissions ranging between 0.66 g 
and 3.62 g N2O/LU per day have been measured from slurry-based pig houses with fully slatted floors. 
Much higher emissions may occur from deep litter systems with fattening pigs, where values between 
4.8 g and 7.2 g N2O/LU per day have been reported [ 443, Chadwick et al. 2011 ]. From a literature 
review  for  solid  manure  systems  in  housing  for  fattening  pigs  in  the  Netherlands,  Germany  and 
Belgium,  the  measured  average  value  for  N2O  emissions  is  2.7  g  N2O-N  per  day  per  animal  place  
[ 441, Webb et al. 2012 ].  

Investigations on methane release from a pig house with indoor slurry storage showed an emission rate 
of 3.8 kg CH4/ap/yr when slurry pits were emptied at the end of the cycle but not cleaned afterwards. 
In  particular,  average  daily  CH4  emissions  ranged  from  0.8 g  to  124 g/day/LU  or  0.1 g  to 
22.5 g/day/pig. CH4 emission rates were very low until day 16–19 of the fattening period. The average 
CH4 emission per animal per year was reduced by 40 % when the slurry removal was combined with a 
complete cleaning of the slurry pit [ 444, Haeussermann et al. 2006 ]. 

Dust  
Dust levels are higher in litter-based systems than in slurry systems. Dust particles function as a carrier 
for  part  of  air  emissions.  The  emission  levels  associated  with  different  housing  techniques  and 
reported during the information exchange have been summarised per animal category (sows, weaners 
and fattening pigs) in Table 3.56, Table 3.57 and Table 3.58. More information on odour emissions is 
given in Section 3.3.9. 

Intensive Rearing of Poultry or Pigs 

187 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.56:  Range of emissions to air from housing systems for sows (mating/gestating, farrowing) 

Housing system 

NH3

CH4

N2O 

PM10 

kg/ap/yr 

Odour 
ouE/s/animal 

NI 

1.0–5.6 

0.21–4.2 

0.035–0.22 

18.2–21.1(1) 

Mating and gestating 
sows (slurry system) 
Mating and gestating 
sows (solid manure 
system) 
Farrowing sows 
(slurry and combined 
slurry/solid manure 
system) 
(1) Source: [ 43, COM 2003 ] 
NB: Emission levels achieved by air cleaning systems are included; NI = no information provided. 

0.03–0.16 

0.42–9.0 

5.5–6.2 

NI 

NI 

NI 

NI 

1.3–57 

6.6 

5.6–100 

Table 3.57:  Range of emissions to air from housing systems for weaners 

Housing system 

NH3 

CH4 

N2O 

PM10 

kg/ap/yr 

0.03–0.8 

Slurry system 
Solid manure system 
and combined slurry/ 
solid manure system 
NB: Emission levels achieved by air cleaning systems are included; NI = no information provided. 

0.006–0.132 

0.29–0.70  

0.02–0.57 

0.28–5.98 

0.11–0.7 

0.08 

NI 

2.25–3 

Odour 
ouE/s/animal 
 1.1–12.1 

Table 3.58:  Range of emissions to air from housing systems for fattening pigs 

Housing system 

NH3

CH4

N2O 

PM10 

kg/ap/yr 

0.015–0.24 

0.42–30 

0.1–4.6  

Slurry system 
Solid manure 
system and 
combined slurry/ 
solid manure 
system 
(1) Source: [ 43, COM 2003 ] 
NB: Emission levels achieved by air cleaning systems are included. 

0.54–18.0 

1.9–7.53 

0.01–3.7 

Odour 
ouE/s/animal 
1.14–29.2 

0.01–0.24 

0.05(1)–2.4 (1) 

4.2–7 

3.3.3 

Emissions from manure storage facilities 

Ammonia losses from buildings and after spreading livestock manure are usually the most important 
emission  sources.  However,  losses  from  stored  slurry  and  solid  manure  can  also  make  a  significant 
contribution to the total emission of ammonia. The storage of solid manure and slurry is a source of 
gaseous emissions of ammonia, methane, nitrous oxide and odorous compounds. The liquid draining 
from  solid  manure  (e.g.  heaps  in  fields)  can  also  be  considered  an  emission  (nitrate  leaching). 
Emissions from manure storage depend on a number of factors: 

Solid manure 
 

chemical composition of manure (i.e. the concentration of NH4-N); 

 

 

 

188 

composting potential (water content, density and C content); 

emitting surface; 

application of covers. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Slurry 
 

chemical composition of slurry (i.e. the concentration of NH4-N); 

 

 

 

 

physical characteristics (dry matter %, pH); 

emitting surface (size, crusts); 

climatic conditions (ambient temperature, rain, wind); 

application of covers. 

Of  the  aforementioned  factors,  the  most  important  are  the  dry  matter  and  nitrogen  content  (in 
particular TAN). Dry matter essentially depends on the manure management, whilst nitrogen depends 
on the feeding practices. In addition, housing techniques that aim for a reduction of emissions from in-
house  collection  of  solid  manure  and  slurry  also  affect  the  manure's  nitrogen  content  and, 
consequently, emissions during storage. 

Quantification  of  ammonia  emissions,  although  not  easy,  can  be  done  through  measurements  by 
means  of  direct  methods,  such  as  the  dynamic  chamber  technique  for  slurry  or  by  enclosing  the 
manure  heap  in  a  large  'polytunnel'  where  emissions  can  be  captured  [  258,  France  2010  ]  
[ 500, IRPP TWG 2011 ]. 

Baseline emissions without any cover on the stored manure surface are assumed to be between 1.4 kg 
and 2.7 kg NH3-N per m2 per year based on data from western European countries; lower values might 
be observed where stored manure is frozen for several months, and higher values in warm countries  
[ 508, TFRN 2014 ]. 

3.3.3.1 

Emissions from solid manure storage  

Measured ammonia and nitrous oxide emissions from solid manure heaps are presented in Table 3.59 
and  Table 3.60.  Data  represent  a  literature  review  derived  from  official  reports  and  peer-reviewed 
articles. A limited number of studies concerned N2O emission from manure heaps.  

Ammonia emission factors vary from being negligible to being very high and may account for more 
+) in the manure, because ammonia emissions may also originate from 
than the initial TAN (NH3+NH4
mineralised organic  nitrogen. This variation in NH3 emission is due to the effect of treatment of the 
manure, i.e. storage time, aeration and temperature [ 590, Batfarm 2013 ] [ 441, Webb et al. 2012 ]. 

Table 3.59:  Average ammonia and nitrous oxide emissions during storage of solid pig manure in heaps 

Type of 
manure 
FYM 
FYM 
Deep litter 
Deep litter 
FYM 
Deep litter 

FYM 

Emissions 

Average 

SD 

No  Max.  Min. 

Source 

NH3-N 
(% of total N) 

N2O-N 
(% of total N) 
Ν2Ο-N 
(g Ν/m2/day) 

30.8 
23.5 
4.8 
30.2 
0.5–2.63 
4.6 

1.9 

37.8 
0.7 
2 
7.7 
NI 
3.5 

1.1 

13 
NI 
4 
NI 
2 
4 

4 

123.4 
NI 
7 
NI 
NI 
9.8 

2.9 

0.1 
NI 
2.4 
NI 
NI 
2.5 

0.7 

[ 441, Webb et al. 2012 ] 
[ 439, Sommer et al. 2006 ] 
[ 441, Webb et al. 2012 ] 
[ 439, Sommer et al. 2006 ] 
[ 443, Chadwick et al. 2011 ] 
[ 441, Webb et al. 2012 ] 

[ 441, Webb et al. 2012 ] 

NB:  No = Number of reports and publications from which the values were derived; SD = Standard deviation. 

FYM = Farmyard manure; NI = no information provided. 

Intensive Rearing of Poultry or Pigs 

189 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.60:  Ammonia and nitrous oxide emissions during storage of solid poultry manure in heaps 

Type of manure 
Litter 
Manure removed 
daily with belt  

Litter 

Emissions 

NH3-N 
(% of total N) 

N2O-N 
(% of total N) 

Average 
8.3 

SD  No  Max.  Min. 
0.3 
5.9 

18.4 

13 

Source 
[ 441, Webb et al. 2012 ] 

2.1 

1.8 

0.17–0.81  NR 

4 

1 

4.5 

0 

[ 441, Webb et al. 2012 ] 

NI 

NI 

[ 443, Chadwick et al. 2011 ] 

NB:  No = Number of reports and publications from which the values were derived. 

SD = Standard deviation; NR = not relevant; NI = no information provided. 

Ranges for national emission factors reported by several Member States are presented in Table 3.61.  

Table 3.61:  Range of ammonia emission factors for solid poultry manure storage as reported by Member 

States  

Poultry category 

Broilers 
Laying hens 
Turkeys 
Broiler breeders 

Ammonia emission factor 
(kg NH3-N/animal place/year) 
0.024–0.04  
0.027–0.067 
0.092–0.14 
0.022 

Source: [ 615, IE EPA 2012 ] [ 612, TWG comments 2012 ] [ 500, IRPP TWG 2011 ] 

An  example  of  emission  factors  used  by  a  Member  State  (the  UK)  for  calculating  overall  ammonia 
emissions from solid manure stores is presented in Table 3.62. 

Table 3.62:  Emission factors reported by the UK for solid manure storage 

Production 

Manure type 

Ammonia emission factors  

Pig manure (FYM)  Manure heap  

1 224 g N/t initial heap mass/yr 

Poultry manure 

Manure belts  

1 956 g N/t initial heap mass/yr 

Poultry manure 

Deep pit 

1 956 g N/t initial heap mass/yr 

Poultry manure 

Litter  

1 435 g N/t initial heap mass/yr 

Source: [ 612, TWG comments 2012 ] [ 614, UK 2013 ] 

1.49 kg NH3/t 
initial heap mass/yr 
2.38 kg NH3/t 
initial heap mass/yr 
2.38 kg NH3/m2/yr 
1.74 kg NH3/m2/yr 

In  Germany,  the  ammonia  emission  factor  associated  with  solid  manure  storage  is  5  g  NH3/m2  of 
surface area per day [ 474, VDI 2011 ].  

Ammonia emissions can be reduced (e.g. by 75–80 % by sheeting) or increased (e.g. by 80–150 % by 
turning the heap), depending on the management strategy applied. Nitrogen losses in leachate from the 
heaps  can  range  between  2.3 %  and  5.3 %  of  the  total  nitrogen  initially  stored  for  pig  manure  and 
between 0.8 % and 8.2 % for broiler litter [ 207, ADAS 2004 ]. 

It has been reported that, within the first 30 days of storage, ammonia losses are over 80 % of the total 
emissions for pig manure and 25–45 % for broiler litter, whereas losses from slurry storage continue at 
a relatively steady pace throughout the storage period [ 253, ADAS 2002 ]. Because the evolution of 
NH3 emissions is basically determined by the tendency for self-heating (composting) which occurs in 
most heaps of porous manure, ammonia emissions can be reduced by covering the heap, in order to 
limit internal air transfer, or by a deliberate compaction of the manure [ 441, Webb et al. 2012 ].  

190 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

A literature review (see Table 3.59 and Table 3.60) concluded that N2O emissions from manure heaps 
are  very  variable,  and  a single  major  condition  affecting  the  emission  could  not  be established. The 
production  of  N2O  that  takes  place  during  storage  is  significant  due  to  nitrification  and  subsequent 
denitrification. Emissions of N2O from poultry manure tend to be smaller [ 441, Webb et al. 2012 ].  

CH4  emissions  occur  only  under  locally  anaerobic  conditions.  Aerobic  decomposition  in  straw-rich 
porous  heaps  of  solid  manure  leads  to  both  high  temperatures  and  anaerobic  hotspots,  causing  CH4 
emissions, even though the heap is largely aerobic. On the other hand, if an airtight cover is used on 
the  heap,  thereby  inhibiting  the  activity  of  aerobic  microorganisms  and  the  associated  temperature 
increase, CH4 emissions will be reduced, even though the heap is largely anaerobic. Another strategy 
that  can  be  used  to  reduce  methane  emissions  from  stored  solid  manure  is  frequent  turning,  which 
reduces anaerobic zones in the heap [ 441, Webb et al. 2012 ] [ 443, Chadwick et al. 2011 ]. 

3.3.3.2 

Emissions from slurry storage 

When storing slurry, some NH3 is initially emitted from the surface layer, but later the impoverished 
surface  layer  blocks  volatilisation.  The  formation  of  a  floating  crust  may  depend  on  the  dry  matter 
content of the slurry, as well as the climatic conditions: heavy rains soak the crust which will tend to 
be  weighed  down,  diluting  the  slurry  at  the  surface,  whereas  warm  and  sunny  climatic  conditions 
allow the quick formation of a crust. An intact crust is an effective barrier against NH3 losses. Low 
volatilisation may also be caused by the neutral pH value. Stirring will obviously raise the dry matter 
to  the  surface  and  increase  the  volatilisation  of  NH3,  thereby  causing  peaks  in  emissions  to  air. 
Ammonia  emission  factors  from  uncovered  stored  pig  slurry,  as  reported  in  a  literature  review,  are 
presented in Table 3.63.  

Table 3.63:  Ammonia emissions from uncovered stored pig slurry  

Concrete store 
Untreated slurry 
2.18 

Ammonia emission (kg NH3-N/m2/yr) 

Lagoon 
Untreated slurry 
0.78 

Concrete store  
Slurry fermented in biogas plant (1) 
2.33 

1.07 

0.68 

Parameter 

Average value 
Standard 
deviation 
(1) Cattle and pig slurry. 
Source: [ 439, Sommer et al. 2006 ] 

2.1 

The  ammoniacal  nitrogen  loss  from  pig  slurry  storage  in  open  tanks  and  lagoons  correspond  to 
between 6 % and 30 % of the total nitrogen in stored slurry, assuming there is an emitting surface over 
the whole year. The emission from pig slurry stored in lagoons appears to be less than that from slurry 
stored in concrete stores, because the TAN concentration is less [ 439, Sommer et al. 2006 ].  

Emission  factors  reported  by  Denmark  for  slurry  storage,  showing  the  effect  of  slurry  covers,  are 
presented in Table 3.64.  

Table 3.64:  Ammonia emission factors for covered and uncovered slurry storage in Denmark 

Raw slurry 

Digested slurry 

NH4-N as % of 
NH4-N ex-house 
11.4 

NH4-N as % of 
total N ex-house 
9 

NH4-N as % of 
NH4-N ex-house 
27.3 

NH4-N as % of 
total N ex-house 
21 

Type of cover 

(natural  crust, 

No cover 
Covered 
straw cover) 
Tent or concrete cover 
Source: [ 442, Hansen et al. 2008 ] 

Intensive Rearing of Poultry or Pigs 

2.5 

1.3 

2 

1 

5.2 

2.6 

4 

2 

191 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Ranges of reported national ammonia emission factors for the storage of pig slurry are presented in  
Table 3.65.  

Table 3.65:  Range of ammonia emission factors for pig slurry storage as reported by Member States  

Pig category 

Growers/finishers (20–100 kg) 
Weaners (6–20 kg) 
Farrowing sows 
Sows in full cycle 
Source: [ 412, Italy 2001 ] [ 258, France 2010 ] [ 439, Sommer et al. 2006 ] [ 616, Spain 2012 ] 

Ammonia emission factor 
(kg NH3-N/animal place/year) 
0.6–2.62 
0.15–1.07 
2.05–6.82 
14.4 

[ 615, IE EPA 2012 ] 

In Germany, the ammonia emission factor for uncovered pig slurry storage is 10 g NH3/m2 of surface 
area  per  day  [  474,  VDI  2011  ].  In  the  UK,  the  corresponding  emission  factor  for  slurry  stores  and 
lagoons is 3.16 g N/m2 of surface area per day [ 614, UK 2013 ].  

Nitrous  oxide  emission  from  slurry  or  liquid  manure  with  no  surface  cover  is  negligible,  as  slurry 
stores remain principally anaerobic unless O2 is introduced as a consequence of a treatment process, or 
unless  windy  conditions  prevail.  Slurry  crust  conditions  can  control  N2O  emissions,  e.g.  when  the 
surface layer has a reduced water content N2O emissions increase and may be as high as 25 mg N2O-
N/h  per  m2  of  surface.  Emissions  are  reduced  or  stopped  at  low  temperatures  and  when  the  surface 
crust  or  surface  straw  layer  has  a  high  water  content  [  443,  Chadwick  et  al.  2011  ].  A  synthetic 
permeable cover can enhance or delay N2O emissions, depending on whether a natural crust will form 
in  the  absence  of  a  synthetic  cover  [  517,  Petersen  et  al.  2011  ].  The  Intergovernmental  Panel  on 
Climate  Change  (IPCC)  assumes  a  N2O  emission  factor  of  0.005 kg  Ν2Ο-Ν/Ν  ex-animal  for  slurry 
stores with a crust [ 659, IPCC 2006 ]; however, there is little knowledge about the extent and control 
of  N2O  emissions  from  slurry  crusts.  Actual  emissions  will  probably  vary  seasonally,  according  to 
local  climatic  conditions,  but  also  depending  on  the  potential  for  nitrification,  which  may  vary 
considerably [ 517, Petersen et al. 2011 ]. 

Slurry stores are sources of methane as the anaerobic environment favours methanogenesis. A higher 
temperature and longer retention time of organic material in the system greatly increase the amount of 
methane produced. Uncovered lagoons have a higher potential for CH4 emissions than other systems 
under  most  circumstances  as  they  are  associated  with  longer  retention  times  [  659,  IPCC  2006  ]. 
Covers were found to have contrasting effects, in particular: 

 

 

 

 

the formation of a slurry crust can reduce CH4 emissions as a result of methane oxidation; 

mixing slurry with straw may enhance the methanogenic formation of CH4; 

covering  slurry  stores  with  porous  surfaces,  e.g.  straw,  expanded  clay  pebbles  or  recycled 
polyethylene, may reduce CH4 emission due to oxidation to CO2; 

high  concentrations  of  cellulose  and  lignin  may  limit  the  rate  of  CH4  production  due  to  the 
reduced hydrolysis of the lignified structures in the biomass.  

Methane emissions are also influenced by the following parameters: 

 

 

192 

mild agitation of the slurry has been to shown to increase CH4 emissions; 

frequent removal of slurry from the store or channel reduces the pool of methanogenic bacteria 
within  this  environment.  Thus,  in  pig  houses  where  slurry  was  removed  from  channels  after 
each  fattening  period,  emissions  were  40 %  lower  than  in  houses  where  channels  were  not 
cleared as frequently; 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 3 

 

 

a positive correlation between CH4 emissions during storage and the temperature of manure or 
slurry has been observed. Methane production is low at temperatures below 15 °C, but increases 
exponentially as the temperature rises above 15 °C [ 443, Chadwick et al. 2011 ];  

reducing  the  organic  matter  content  of  slurry  through  separation  or  fermentation  in  a  biogas 
digester  may  prove  to  be  the  most  efficient  way  of  reducing  CH4  emissions  during  outdoor 
storage. However, it is shown that digested slurry should be cooled to ambient temperatures in 
post-treatment  storage  tanks  to  reduce  CH4  emissions.  Also,  acidification  of  slurry  for  the 
purpose of reducing NH3 emissions from storage has been observed to reduce CH4 emissions. 

3.3.4 

Emissions from manure processing 

For various reasons manure is processed on farm and several techniques are described in Chapter  4, 
together  with  a report on  their  environmental  and  technical  characteristics.  With  regards to reported 
data, consumption and emission levels are indicative and specific for the situation in which they  are 
obtained. 

Input levels of manure and slurry vary with the number of animals on the farm. Various additives are 
used  to  enhance  chemical  reaction(s)  or  to  react  with  unwanted  elements  in  the  reaction  substrate. 
These may affect emissions to water or air. 

During the treatment processes, e.g. lagoon systems, liquid fractions may be produced that have to be 
discharged. Odour may arise due to suboptimal process conditions, although a number of techniques 
aim to reduce odorous components (e.g. composting, aerobic digestion). Incineration  emits dust and 
other flue-gases. Techniques such as biogas reactors deliberately form gaseous compounds, which can 
be used in heaters and engines but from which exhaust gases are then emitted. 

3.3.5 

Emissions from landspreading 

The  level  of  emissions  from  landspreading  depends  mainly  on  the  chemical  composition  of  slurries 
and manures, the prevailing climatic conditions and, mostly, the way in which they are handled. The 
composition varies and depends on the diet, as well as on the method and duration of storage and the 
treatment, if any, applied before application. Values of nitrogen and K2O will be lower for farmyard 
manure (FYM) stored for long periods in the open. Slurries may become diluted by drainage and wash 
water, thus increasing in volume, albeit with a decreasing dry matter content. 

The nitrogen content of livestock manure is present in two main forms: 

 

 

Readily available nitrogen which is potentially available for rapid crop uptake. 

Organic  nitrogen,  which  is  slowly  released  to  become  available  for  crop  uptake  over  a  time 
period of months to years. Organic N contributes only to a small extent to N fertilisation in the 
year of application. In this way, around 10 % of the total nitrogen content may become available 
for the second crop following application. 

Two major processes regulate the loss of nitrogen from landspreading: 

 

 

Ammonia  volatilisation  is  the  most  important  source  of  emissions.  Ammonia  emissions 
following  slurry  or  manure  landspreading  are  strongly  influenced  by  the  readily  available  N 
content of the manure. Slurries and poultry manures are ‘high’ in readily available N (typically 
40–60 %  of  total  N),  compared  with  farmyard  manure  which  is  ‘low’  in  readily  available  N 
(typically 10–25 % of total N).  

Nitrate leaching. Livestock manures are the greatest source of avoidable nitrate leaching losses. 
The NH4-N content of manure is rapidly converted to nitrate-N and can then be used by plants 
or otherwise lost by leaching or by denitrification. The amount of N leached is mainly related to 
the manure application rate, readily available N content and timing of applications. 

Intensive Rearing of Poultry or Pigs 

193 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

There  are  various  manure  management  practices  that  minimise  nitrogen  losses  via  ammonia 
volatilisation,  such  as  rapid  soil  incorporation  on  arable  land  for  solid  manure  and  band  spreading 
(trailing  hose/shoe)  or  shallow  injection  for  slurry.  In  order  to  reduce  nitrate  leaching  losses,  it  is 
important to apply manure throughout the growing season (i.e. in late winter or spring to mid- or late 
summer) depending upon the climatic conditions, soil and crop type applicable to the land on which it 
is  being  spread,  when  there  is  a  crop  demand  for  nitrogen,  rather  than  in  the  autumn/winter  period 
when the demand is low and nitrate in the soil is likely to be leached into the groundwater or surface 
waters. Changing manure application timings from autumn to spring is likely to increase the pool of 
soil  mineral  nitrogen  [  245,  ADAS  2002  ]  which  is  available  for  the  crop  uptake  but  also  for 
-,  N2  and  a 
nitrification-denitrification  microbial  processes  in  the  soil,  leading  to  production  of  NO3
potential increase of ‘direct’ N2O emissions. If needed, additional applications of mineral nitrogen to 
the  soil  should  be  adapted  properly.  A  schematic  representation  of  the  process  regulating  the 
utilisation and losses of nitrogen from manure landspreading is presented in Figure 3.4. 

Source: [ 244, ADAS 2006 ] 

Figure 3.4:  Nitrogen losses from manure landspreading 

3.3.5.1 

Emissions to air 

Ammonia  emissions  during  and  following  slurry  application  are  influenced  by  a  wide  range  of 
interacting variables, which are shown in Table 3.66. 

Table 3.66:  Factors influencing the emission levels of ammonia into air from landspreading 

Factor 

Characteristic 

Influence 

Soil 

pH 
Cation exchange capacity of soil (CEC)  High CEC leads to lower emissions 
Moisture level of soil and porosity 
Temperature 

Low pH gives lower emissions 

Climate factor 

Precipitation 

Wind speed 
Application method 

Manure type 

Management 

Time and dose of application 

Crop 
conditions 
Source: [ 22, Bodemkundige Dienst 1999 ] [ 442, Hansen et al. 2008 ] 

Crop height 

Ambiguous 
Higher temperature gives higher emissions 
Causes dilution and better infiltration and 
therefore lower emissions to air, but increased 
emissions to soil 
Higher speed means higher emissions 
Low emission techniques 
DM content, pH and ammonium concentration 
affect emission level 
Warm, dry, sunny and windy weather should 
be avoided; excessively high doses increase 
infiltration periods 
Limited ammonia losses when slurry is spread 
on crops compared to bare land 

194 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Any  ammonia  conserved  during  housing  and  storage  is  subjected  to  losses  during  and  after 
landspreading.  To  achieve  a  high  overall  reduction  in  ammonia  emissions  in  the  whole  production 
chain,  as  well  as  cost-effectiveness  for  ammonia  abatement,  slurry  or  solid  manure  have  to  be 
incorporated  into  the  soil.  Results  of  field  trials  carried  out  in  the  UK,  illustrating  the  effect  of 
different  storage  conditions,  incorporation  techniques,  and  manure  compositions  on  emissions  after 
landspreading of solid manure, are presented in Table 3.67. 

Chapter 3 

Table 3.67:  Emissions from  solid  manure  landspreading, with or  without  incorporation, reported from 

the UK 

Type of 
manure 

Storage 
before 
landspreading 

Incorporation 

pig 

Fresh 
manure 
Fresh 
broiler litter 

Pig manure  

Broiler litter  

Pig manure  

Broiler litter  

Pig manure  

No 

No 

for 

for 

Conventionally 
(open 
stored 
air) 
6 
months 
Conventionally 
(open 
stored 
air) 
6 
months 
Sheet-covered 
for 6 months 
Sheet-covered 
for 6 months 
Conventionally 
(open 
stored 
air) 
12 
months 

for 

No 

No 

No 

No 

No 

No 

No 

No 

No 

pig 

plough 

plough 

Fresh 
manure 
Fresh 
broiler litter 
pig 
Fresh 
manure 
Fresh 
broiler litter 
NB: NI = no information provided; NR = not relevant. 
Source: [ 207, ADAS 2004 ] 

By 
after 4 hours 
By 
after 4 hours 
plough 
By 
after 24 hours 
By 
plough 
after 24 hours 

No 

No 

Manure 
composition 

Ammonia 
emissions 

NH4-N  
as % total N 
content 

NH4-N  
as % total N 
applied 

26–38 

13–41 

46–52 

16–28 

NI 

20–32 

NI 

40–50 

< 5 

26–38 

46–52 

26–38 

46–52 

8 

16 

22 

29 

< 3 

 NI 

NI 

NI 

NI 

Emission 
reduction after 
incorporation, 
compared with 
surface 
application 

(%) 

NR 

NR 

NR 

NR 

NR 

NR 

NR 

84 

90 

64 

78 

Ranges of NH3 emissions after landspreading of solid manure, as derived from a survey of published 
results, are presented in Table 3.68. Data mainly relate to experiment results obtained under different 
climatic conditions in central and northern Europe. 

Intensive Rearing of Poultry or Pigs 

195 

 
 
 
 
 
 
 
 
Chapter 3 

Table 3.68:  Range  and  average  values  of  ammonia  emissions  measured  after  landspreading  of  solid 

manure without incorporation  

Type of 
manure 

Pigs 

Poultry 

Emissions 
(NH3-N as % of TAN) 
63 (average) 
41–76 
40 (average) 
36–73 

No 

19 

6 

NB: No = number of datasets used. 
Source: [ 441, Webb et al. 2012 ] 

In general, poultry manure is expected to emit less than pig manure, as the hydrolysis of uric acid to 
urea may take several months and is often incomplete, even after application [ 441, Webb et al. 2012 ]. 

The ranges of reported national ammonia emission factors for slurry landspreading for the two main 
pig categories, fattening pigs and sows, are presented in Table 3.69.  

Table 3.69:  Ranges  of  national  ammonia  emission  factors  for  slurry  landspreading,  as  reported  by 

Member States  

Production 

Fattening pigs 
Sows 
Source: [ 612, TWG comments 2012 ] [ 615, IE EPA 2012 ] [ 615, IE EPA 2012 ] 

Ammonia emissions 
(kg NH3-N/animal place/year) 
0.56–1.47 
1.45–3.65 

The  average  emissions  of  ammoniacal  nitrogen  from  slurry  landspreading,  in  relation  to  different 
application  methods,  expressed as a  percentage  of  total  NH4-N  applied,  are presented  in  Table 3.70. 
Data refer to 199 measurements on grassland and 58 measurements on arable land carried out in the 
Netherlands. 

Table 3.70:  Average NH4-N emission factors and ranges of measured values, expressed as percentage of 

total ammoniacal nitrogen applied  

Type of 
land 

Grassland 

Arable land 

Application technique 

Surface spreading 
Narrow band 
Shallow injection 
Surface spreading 
Surface incorporation 
Deep placement 

Source: [ 232, Huijsmans et al. 2009 ] 

Emissions 
(NH4-N as % of TAN applied) 
Average  
74 
26 
16 
69 
22 
2 

Range 
28–100 
9–52 
1–63 
30–100 
3–45 
1–3 

Emissions  of  N2O-N  during  pig  slurry  landspreading  have  been  estimated  by  the  Intergovernmental 
Panel  on  Climate  Change  to  be  equivalent  to  0.01 kg  N2O-N/N  ex-animal,  with  a  minimum  and  a 
maximum value of 0.003 kg N2O-N/N and 0.03 kg N2O-N/N, respectively [ 659, IPCC 2006 ].  

Results of a study reporting N2O losses (average and range) after landspreading and incorporation of 
solid manure, under different storage conditions, are presented in Table 3.71.  

196 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.71:  Emissions of N2O-N from landspreading of solid manures 

Manure management 

Surface-applied manure, conventionally stored 

Stored manure, incorporated into the soil after 4 hours 

Fresh manure, applied on the surface 

Fresh manure, incorporated into the soil after 4 hours 

Source: [ 250, IGER 2004 ]  

Emissions 
(N2O-N as % of total N) 
1.04 (average) 
0.07–3.09 
0.38 
(0.08–1.08) 
0.7 (average) 
0.05–2.17 
1.02 (average) 
0.4–3.27 

A  summary  of  field  test  results  from  a  literature  review,  concerning  landspreading  of  pig  manure 
under  different  soil  textures,  crops,  seasons, application  methods  and  amounts  of  nitrogen  per  ha, is 
presented in Table 3.72 [ 443, Chadwick et al. 2011 ].  

Table 3.72:  Reported N2O-N emissions from pig manure landspreading  

Type of manure 

N2O-N 
(% of total N) 

Nitrous oxide emissions 
N2O-N 
(% of TAN) 

Slurry (No=15) 

0.12–2.95 

0.26–9.55 

Solid (No=12) 

0–3.27 

0–5.3 

Total N2O-N 
(kg/ha) 

0.4–2.51 

0.03–3.27 

NB: No = number of experiments inventoried. 
Source: [ 443, Chadwick et al. 2011 ] 

Emissions of CH4 generally occur only immediately after manure landspreading as methanogenesis is 
inhibited by the presence of O2. In total, the amount of methane emitted from surface application was 
shown to be negligible, whereas, when slurry is applied via shallow injection, the anaerobic nature of 
the slot environment results in higher CH4 emissions [ 443, Chadwick et al. 2011 ]. 

3.3.5.2 

Emissions to soil and water 

A large amount of the nitrogen, phosphorus and potassium in livestock diets is excreted in manure and 
urine.  Manures  contain  useful  amounts  of  these  plant-available  nutrients,  as  well  as  other  major 
nutrients  such  as  sulphur,  magnesium  and  trace  elements.  For  a  number  of  reasons  not  all  of  these 
elements can be used by plants and some may cause environmental pollution. 

Two  types  of  pollution  can  be  distinguished:  point  source  and  diffuse  pollution.  Point  source  water 
pollution can occur through direct contamination of a watercourse from a burst or overflowing slurry 
store, yard run-off, or immediately after landspreading and during heavy rain. Such incidents can have 
catastrophic  effects  on  fish  and  other  aquatic  life,  mainly  because  of  the  high  biochemical  oxygen 
demand (BOD) and dissolved ammonia contained in manures. BOD measures the amount of oxygen 
consumed  by  microorganisms  in  breaking  down  organic  matter  and  typically  ranges  between 
10 000 mg/l and 30 000 mg/l for slurry, compared with 300 mg/l to 400 mg/l for raw domestic sewage  
[ 389, ADAS 2001 ]. 

Diffuse pollution can affect  soil, water and air and, unlike point source pollution, is not easily seen. 
The resulting contamination is associated with farming practices over a wide area and over extended 
time  periods,  rather  than  a  particular  action  or  event,  and  may  have  long-term  effects  on  the 
environment. An example is volatised ammonia deposition, which can contribute to soil acidification 
problems, particularly in woodland soils. It can raise nitrogen levels in soils low in nutrients, causing a 
change  in  the  type  of  plants  that  grow  in  the  affected  area,  e.g.  botanically  rich  habitats  in  old 

Intensive Rearing of Poultry or Pigs 

197 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

meadows  and  heathlands  [  389,  ADAS  2001  ].  Deposited  ammonia  can  also  contribute  to  nitrate 
leaching losses. 

Of the agricultural emissions to soil and groundwater, the most important are the residual emissions of 
nitrogen and phosphorus. The processes involved in their distribution are: 

 

 

for N – leaching (NO3

-), denitrification (NO2, NO, N2) and run-off; 

for P – leaching and run-off. 

Nitrogen  leaching  from  livestock  manure  occurs  mainly  by  percolation  through  soil  layers  when 
manure  is  lansdpread  improperly,  i.e.  without  taking  into  account  existing  regulations  and  fertiliser 
planning.  Similarly,  phosphorus  is  lost  to  the  environment  via  run-off  and  leaching;  although 
phosphorus leaching  is  closely  connected to  soil  erosion  mechanisms  [  218,  Baltic  Sea  2020  2010]. 
Conversely, some part of nitrogen and phosphorus is also stored in the soil for medium- or long-term 
release. 

Nitrogen and phosphorus have completely different turnovers in the agricultural environment. Excess 
fertilisation  with  phosphorus  does  not  necessarily  leach  out  like  in the  case  of nitrogen;  phosphorus 
can accumulate in the soil layers, where it can be slowly converted into other forms. Agricultural soils 
can bind varying amounts of phosphorus, but accumulation increases the amount of labile-P and the 
risk of phosphorus leaching [ 218, Baltic Sea 2020 2010]. Potassium can also be lost by leaching and 
surface  run-off,  causing  a  decrease  in  the  fertiliser  value  of  manure  but  without  posing  an 
environmental risk. 

European  concerns  over  the  environmental  impacts  of  nitrates  leaching  led  to  the  adoption  of  the 
Nitrates  Directive  (Council  Directive  91/676/EEC).  The  Directive  introduced  voluntary  Codes  of 
Good Agricultural Practice, the designation of Nitrate Vulnerable Zones (NVZs) for areas with high 
nitrate levels (or a risk of this) in the waters, and a mandatory Action Programme for farms within the 
NVZs. The Action Programme requires farms to fertilise according to the needs of the crops and not to 
spread  livestock  manure  in  periods  when  lands  are  waterlogged  or  frozen;  indirectly,  this  is  a 
requirement for sufficient manure storage capacity. 

However,  the  nitrogen  that  is  saved  by  measures  to  reduce  ammonia  emissions  from  landspreading 
may increase the potential for nitrate leaching, especially if the application of mineral nitrogen is not 
reduced. In comparison with slurry, solid manures, having an  inherently lower ammoniacal nitrogen 
content, are considered to have less readily available nitrogen for nitrification and subsequent nitrates 
leaching [ 249, Webb et al. 2001 ]. However, the loss of nitrogen during the storage of solid manure 
depends on the potential for composting. 

Emissions to surface water are due to leaching and run-off. Nitrogen leaching is highest in winter and 
on sandy soils. This is more evident where  manure landspreading occurs in autumn and with  empty 
fields in winter, as rainfall is likely to wash nitrate out of the soil before crops can use it. Phosphorus 
loss  in  surface  run-off  following  manure  application  occurs  when  the  soil's  infiltration  capacity  is 
exceeded, or when phosphorus attached to soil particles is eroded. It is most likely to occur if heavy 
rain follows application, or when the soil is already saturated [ 506, TWG ILF BREF 2001 ]. On soils 
with low organic matter content, this will rarely occur. 

Where practically possible, applications during the autumn-early winter period should be avoided, as 
well as over winter. Delaying applications, particularly of manures high in available nitrogen, until the 
late winter or spring will increase the utilisation of manure nitrogen and reduce nitrate pollution. 

198 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 3 

3.3.5.3 

Emissions of metals 

There  are  several  sources  responsible  for  the  introduction  of  heavy  metals  into  agricultural 
ecosystems, such as indigenous sources (e.g. the weathering of rock), atmospheric deposition, manure 
application,  pesticides,  irrigation,  fertilisers,  secondary  material  (such  as  waste  water  sludge, 
compost), crumbling away of riverbanks, feed import, feed additives and animal medication. 

Livestock  manures,  and  pig  slurry  in  particular,  contain  significant  amounts  of  certain  metals, 
specifically  copper  (Cu) and  zinc (Zn),  mainly  because they  are  used  at  high concentrations  as  feed 
additives. Continuous landspreading can lead to the accumulation of these metals and undesirably high 
levels in the soil, which may pose a medium- or long-term toxicity risk to plants and microorganisms. 
The concentration in the soil should be maintained below the level that ensures the non-transference to 
the food chain [ 253, ADAS 2002 ] [ 590, Batfarm 2013 ]. 

In situations where manure landspreading has been applied for a number of years, and will continue to 
be applied, it is advisable to have these soils analysed to determine their metal status and to monitor 
build-up periodically [ 389, ADAS 2001 ]. A proportion of metal inputs from surface-applied manures 
is  recycled  through  the  agricultural  system  in  animal  feeds  grown  and  fed  on  farms  [  253,  ADAS 
2002 ]. 

Copper and zinc are involved in many metabolic functions, and their provision in sufficient amount in 
feeding  is  indispensable  to  ensure  good  performance  and  animal  health.  However,  because  they  are 
used  as  growth  promoters  at  pharmacological  levels,  or  because  large  safety  margins  are  applied, 
copper  and  zinc  may  be  oversupplied  in  pig  diets.  Consequently,  these  elements  are  highly 
concentrated in manure, especially in pig manure. Moreover, when a treatment is applied to the slurry, 
copper  and  zinc  will  follow  the  solid  fraction  where  their  concentration  often  exceeds  the  maximal 
values allowed for the utilisation of these products as organic fertilisers. The only way to decrease the 
concentration of trace elements in manure is to restrict their incorporation in the diet. 

The incorporation of 150–250 ppm (mg/kg) of copper in pig diets has been employed for a long time 
because  of  its  growth-promoting  effect.  This  practice  is  authorised  in  the  EU,  allowing  diets 
containing a maximum of 170 ppm of copper for weaners up to 12 weeks. After 12 weeks of age, the 
use  of  copper  as  a  growth  promoter  is  no longer  allowed  within  the  EU,  and  the  maximum  content 
authorised in feedstuffs is 25 ppm. Nevertheless, the practical supply remains high compared with the 
theoretical requirements (< 10 ppm according to published data), and the average retention efficiency 
is still less than 1 %.  

With Regulation 1334/2003/EC, the maximum zinc incorporation allowed in pig diets was reduced to 
150 ppm,  from  a  previous  concentration  of  250  ppm.  These  levels  are  closer  to  the  theoretical 
requirement found in published literature, which vary between 50 ppm and 100 ppm, depending on the 
growing  stage,  and  according  to  the  different  authors.  However,  in  some  EU  Member  States, 
supplementation  with  2 500  ppm  of  zinc  is  still  allowed  as  medication,  resulting  in  an  increased 
excretion of metal [ 590, Batfarm 2013 ]. 

With the EU Regulation 1334/2003/EC, reported copper and zinc contents in the manure dry matter 
(about  350 mg/kg  DM  and  1 250  mg/kg  DM,  respectively)  are  below  the  maximum  concentrations 
allowed in sewage sludge in France (1 000 mg/kg DM and 3 000 mg/kg  DM, respectively), but they 
exceed  the  concentration  allowed  for  organic  fertilisers  (300 mg/kg  DM  and  600  mg/kg  DM, 
respectively). Assuming that 170 kg N/ha are spread each year, it will take 160–170 years for the soil 
to reach 50 mg Cu or 150 mg Zn per kg of dry matter. However, copper and zinc inputs to soil with a 
manure  application  rate  of  170 kg  N/ha  still  exceed  the  metals  absorbed  by  crops  [  590,  Batfarm 
2013 ]. Emissions of metals associated with landspreading of poultry manure, as reported by France, 
are presented in Table 3.73. 

Intensive Rearing of Poultry or Pigs 

199 

 
 
 
 
 
 
 
 
 
 
Chapter 3 

Table 3.73:  Emissions of metals associated with landspreading of poultry manure 

Type of poultry 

Broilers (1) 

Cu  
(mg/bird place/year) 
342 

Zn  
(mg/bird place/year) 
1 410 

Laying hens 
708 
(1) Calculation based on 6.15 cycles per year. 
Source: [ 617, ITAVI 2012 ] 

3 380 

3.3.6 

Emissions from the whole farm 

In  general,  nitrogen  emission  reductions  achieved  in  one  production  step  influence  the  nitrogen 
quantity in the following steps and, therefore, also the quantity of potential NH3 emissions from each 
step.  A  reduction  of  ammonia  emissions  in  the  pig  house  would  normally  lead  to  more  ammonium 
reaching the slurry store; this will potentially increase the risk of ammonia emissions from the store. 
As a result, part of the reduction effect in the animal house may be lost. At the same time, an emission 
reduction  measure  applied  for  manure  storage  can  become  more  cost-effective  if  more  ammoniacal 
nitrogen reaches the store. In principle, emissions that might be avoided in one step of the production 
may increase emissions in the following step, i.e. due to a higher nitrogen content in the manure. In 
order  to  address  this  important  interrelationship,  animal  husbandry  also  has  to  be  considered  in  the 
entire  process  chain.  For  this  purpose,  nitrogen  emissions  in  the  individual  process  steps:  feeding, 
housing, as well as slurry storage and  landspreading, are combined into an entire chain [ 575, UBA 
Germany 2011 ]. 

3.3.6.1 

Emissions from the whole-farm process chain for the rearing of poultry 

Reported examples of general emissions factors used by some Member States  to define the nitrogen 
flow at each stage of manure management are presented in Table 3.74 and Table 3.75 for broilers and 
laying hens.  

Table 3.74:  Examples of the nitrogen flow through the whole farm chain for broiler manure 

Parameter 

France 

Denmark 

Spain 

N losses 
(%) 

N 
content 
(%) 

N losses 
(%) 

N 
content 
(%) 

N excreted in housing 

In-house losses (% N excreted) 

N available in outside storage 

Storage losses (% N ex-house) 

N available for landspreading 

NR 

30 

NR 

15 

NR 

Spreading losses (% N ex-storage) 

10 

Usable N for crop 

NR 

100 

30 

70 

10.5 

59.5 

5.9 

53.5 

NR 

20 

NR 

7 

NR 

31.4 (1) 

NR 

N losses from whole farm 
(1) Derived from a reported value of 45 % as usable N when applied to the fields.  
NB: NR = not relevant. 

46.5 

NR 

NR 

100 

20 

80 

14.4 

65.6 

20.6 

45 

55 

N 
losses 
(%) 

NR 

19.6 

NR 

11 

NR 

38 

NR 

NR 

N 
content 
(%) 

100 

19.6 

80.4 

8.8 

71.5 

27.2 

44.3 

55.7 

Source: [ 328, CORPEN 2006 ] [ 616, Spain 2012 ] [ 500, IRPP TWG 2011 ] [ 618, DAFC, DK 2013 ] 

200 

Intensive Rearing of Poultry or Pigs 

Table 3.75:  Examples of the nitrogen flow through the whole farm chain for laying hen manure 

Chapter 3 

Parameter 

N excreted in housing 
In-house losses (% N excreted) 
N available in outside storage 
Storage losses (% N ex-house) 
N available for landspreading 
Spreading losses (% N ex-storage) 
Usable N for crops 
N losses of whole farm  
NB: NI = no information provided; NR = not relevant. 

N content 
(%) 

Denmark 
(Hens in cages) 
N 
losses 
(%) 
NR 
10 
NR 
5 
NR 
NI 
NR 
NI 

100 
10 
90 
4.5 
88.5 
NI 
NI 
NI 

Denmark 
(Hens in barns) 

N losses 
(%) 

N content 
(%) 

NR 
14 
NR 
5 
NR 
NI 
NR 
NI 

100 
14 
86 
4.3 
81.7 
NI 
NI 
NI 

Spain 

N  
losses 
(%) 
NR 
28.7 
NR 
8 
NR 
37 
NR 
NR  

N  
content 
(%) 
100 
28.7 
71.3 
5.7 
65.6 
24.3 
41.3 
58.7 

Source: [ 616, Spain 2012 ] [ 618, DAFC, DK 2013 ] 

Data concerning nitrogen losses as ammonia for each step of the poultry production system, reported 
by France for different types of poultry manure, are presented in Table 3.76. 

Table 3.76:  Nitrogen  losses  through  all  stages  of  poultry  manure  management  by  type  of  manure 

produced, in France 

Type of 
manure produced 

Solid manure, indoor rearing on litter 
Solid manure, indoor rearing on litter, 
composting 
Solid manure, broiler, with free range 
Solid manure, force-fed ducks and 
geese, with free range 
Solid manure, broiler breeders 
Slurry  
Droppings, pre-dried, storage in shed 
Droppings, dried 
Droppings, deep pit 
Source: [ 433, CORPEN 2006 ] 

Housing 
losses  
(% N 
excreted) 
30 

Storage 
losses 
(% N ex-
house) 
15 

Losses at 
landspreading 
(% N ex-
storage) 
10 

30 

40 

50 

55 
50 
30 
25 
60 

30 

15 

15 

15 
20 
30 
25 
15 

0 

10 

10 

10 
20 
10 
10 
10 

Available to 
crops (% N 
excreted) 

54 

49 

46 

38 

34 
32 
44 
51 
29 

Another  example  is  presented  in  Figure 3.5  to  illustrate  the  relationship  between  emissions  from 
storage and landspreading of broiler litter. It can be seen that effective storage (with sheeting), which 
preserves the content of available nitrogen in the manure, can lead to an increased overall emission if 
it is followed by poor spreading techniques (e.g. surface spreading without incorporation) [ 536, Sagoo 
et al. 2007 ]. 

Intensive Rearing of Poultry or Pigs 

201 

 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

Source: [ 536, Sagoo et al. 2007 ] 

Figure 3.5:  Cumulative  ammonia  volatilisation  losses  during  storage  and  following  landspreading  of 

broiler litter 

3.3.6.2 

Emissions from the whole-farm process chain for the rearing of pigs 

Reported  examples  of  general  emissions  factors  used  by  France  at  each  stage  of  pig  production  for 
slurry  management  are  presented  in  Table 3.77.  Disaggregated  emissions  factors  for  ammonia 
emissions,  for  each  stage  in  the  production  chain,  have  been  reported  by  Spain  for  different  pig 
categories; data are presented in Table 3.78. 

Table 3.77:  Nitrogen losses through all stages of pig manure management (without manure processing), 

in France  

Parameter 

N excreted in housing 

Slurry 

Solid manure (straw) 

% N losses 
(as N-NH3) (1) 
NR 

N content 
(g) 
1 000 

In-house losses (% N excreted) 

25 (15–30) 

250 

N available in outside storage (N 
ex-house) 

NR 

Storage losses (% N ex-house) 

5 (5–15) 

N available for landspreading (N 
ex-storage) 
Spreading losses (% N ex-storage) 
Usable N for crop (3) 

N losses from whole farm (% N 
excreted) 

NR 

20 (10–50) 
NR 

43 

750 

38 

712 

142 
570 

430 

% N losses (as N-NH3, 
N-N2O and N-N2) 
NR 
24 (5–30) as N-NH3 
4 (2–12) as N-N2O 
29 (20–40) as N-N2 

NR 

N content (g) 

1 000 
240 
40 
290 

510 

10 (0–20) as N-NH3 (2) 

51 as N-NH3 
(2) 

NR 

0 
NR 
29 as N-NH3 
4 as N-N2O 
29 as N-N2 

459 

0 
459 
291 
40 
290 

(1) N losses due to N2O formation are considered low. 
(2) N losses in the form of N2O and N2 are not relevant during storage. 
(3) Average nutrient composition of slurry for landspreading N:P2O5:K2O = 1.00:0.67:0.89. 70 % of nitrogen is considered 

to be ammoniacal. 

NB: NR = not relevant; range of potential losses in brackets. 
Source: [ 329, CORPEN 2003 ]  

202 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Table 3.78:  Examples  of  ammonia  emission  factors  used  as  a  reference  for  housing,  storage  and 

landspreading of slurry in Spain  

Chapter 3 

Housing stage  Storage stage  Landspreading stage 

Total 

0.417 
1.584 
1.904 
2.128 
1.988 
3.421 
4.132 
2.088 
2.763 
1.665 

kg NH3-N/place/year 
0.369 
1.401 
1.684 
1.882 
1.758 
3.025 
3.653 
1.846 
2.443 
1.472 

0.150 
0.570 
0.685 
0.766 
0.716 
1.698 
2.051 
1.036 
1.371 
0.599 

0.936 
3.556 
4.274 
4.776 
4.462 
8.144 
9.836 
4.971 
6.577 
3.736 

Type of pig 

Weaners 
Growers 20–49 kg 
Finishers 50–79 kg 
Finishers 80–109 kg 
Finishers > 110 kg 
Gestating sows 
Farrowing sows 
Gilts 
Boars 
Growers/finishers 20–100 kg 
Source: [ 616, Spain 2012 ] 

3.3.7 

Noise 

Noise originating from intensive farming units is a local environmental issue and has to be considered, 
particularly  in  those  situations  where  units  are  located  close  to  residential  areas.  On  the  farm,  high 
noise  levels  can  also  affect  the  animals’  condition  and  the  production  performance,  and  could 
potentially damage the hearing capacity of farm personnel. Equivalent continuous noise (LAeq) is the 
measure used to assess the noise levels of farms, since it makes it possible to compare noise sources of 
variable intensity or sources that are intermittent. 

Typical  farm  levels  have  not  been  reported.  The  equivalent  noise  level  that  arises  from  a  farm  is  a 
combination of the levels of the different activities listed in Table 3.79 and Table 3.80, together with a 
correction for the time duration. A different combination of activities will obviously lead to a different 
equivalent noise level. Background noise is noise which may be experienced in the environment, for 
example, around a poultry unit. It consists of road traffic, birdsong, aircraft, etc. and may also include 
existing noises in the poultry unit. 

In order to account for all the variable intermittent noises, the background noise level (La90) is taken to 
be  the  noise  level  which  is  exceeded  90 %  of  the  time  over  a  period  of  measurement.  Background 
noise varies over a 24-hour period as a result of changes in activities. In rural areas typical daytime 
background noise is 42 dB, but may fall below 30 dB in the early hours of the morning. 

The final impact at sensitive  receptors in the neighbourhood depends on many factors. For instance, 
land  surface, reflecting  or absorbing  objects,  construction  of  the receiving  object  and the number  of 
noise sources determine the sound pressure level that is measured. In tables in the following sections, 
sound pressure levels have been given for only a few sources at the farm or very close to it. The noise 
level at a sensitive receptor is normally lower further away from the farm. 

The data must be seen as reported examples of what has been measured. Total noise levels will vary 
depending on farm management, the number of animals and animal category, and the equipment used. 
In particular, sources of noise from poultry or pig units are associated with: 

 

 

 

 

 

livestock; 

housing; 

feed production and handling; 

equipment; 

manure management. 

Intensive Rearing of Poultry or Pigs 

203 

 
 
 
 
 
 
 
 
 
Chapter 3 

3.3.7.1 

Sources and emissions on poultry farms 

Typical sources of noise for a number of specific activities are shown in Table 3.79. Sound pressure 
levels are reported next to the source or at a short distance. 

Table 3.79:  Typical sources of noise and examples of noise levels in poultry units 

Noise source 

Duration 

Frequency 

Day/night 
activity 

Sound 
pressure 
levels dB(A) 

Equivalent 
continuous 
LAeq dB(A) 

All year 

Day and night 

43 

House ventilation fans 

Feed delivery 

Mill mix unit: 
- inside building 
- outside building 

Continuous/ 
intermittent 

1 hour 

2–3 times every 
week 

NI 

NI 

Gas fuel delivery 

2 hours 

Emergency generator 
Catching chickens 
(broilers) 
Cleaning out (broilers) 

2 hours 
6 hours up to 
56 hours 

Manure handling 

1 to 3 days 

Power washing, etc. 

1 to 3 days 

Cleaning out (laying hens) 
Manure handling 

Up to 6 days 

6–7 times  
per year 
Every week 
6–7 times per 
year 

6–7 times  
per year 
6–7 times  
per year 

Annually  

Power washing, etc. 

1 to 3 days 

NI 

Day  

NI 

Day 

Day  
Morning/ 
night 

Day  

Day  

Day  

NI 

92 
(at 5 metres) 

90 
63 

NI 

NI 

NI 

NI 

88 
(at 5 metres) 

NI 
88 
(at 5 metres) 

NB: LAeq  = equivalent continuous noise - unit for noise of variable intensity; NI = no information provided. 
Source: [ 393, ADAS 1999 ] [ 24, LNV 1994 ] 

3.3.7.2 

Sources and emissions on pig farms 

Typical sources of noise for a number of specific activities are shown in  Table 3.80. Sound pressure 
levels are reported next to the source or at a short distance. 

Table 3.80:  Typical sources of noise and examples of noise levels in pig units 

Description 

Duration 

Frequency 

Continuous 

Continuous 

1 hour 

Daily 

Sound 
pressure 
levels dB(A) 
67 

Equivalent 
continuous 
LAeq dB(A) 
NI 

Day/night 
activity 

Day 

Day 

3 hours 

2 hours 
2 hours 

2 hours 

Daily 

Day/night 

Daily 
Weekly 

Daily 

Day 
Day 

Day 

93 
99 

90 (inside) 
63 (outside) 
90–110 
92 

88 (85–100) 

Normal housing levels 
Feeding animals: 
pigs 
sows 

Feed preparation 

Stock movement 
Feed delivery 
Cleaning and manure 
handling 

Manure spreading 

Seasonal/weekly 

Day 

95 

Ventilation fans 
Fuel delivery 
NB: LAeq  = equivalent continuous noise - unit for noise of variable intensity; NI = no information provided. 
Source: [ 559, ADAS 1999 ] [ 24, LNV 1994 ] 

Continuous 
Fortnightly 

Day/night 
Day 

43 
82 

8 hours/day for 
2–4 days 
Continuous 
2 hours 

204 

Intensive Rearing of Poultry or Pigs 

NI 

NI 

NI 

NI 

NI 

57–60 

NI 

NI 

NI 

NI 

87 
91 

85 

NI 
NI 

NI 

NI 

NI 
NI 

 
 
 
 
 
 
 
 
 
 
 
3.3.8 

Solid waste from poultry and pig farms 

The amounts and composition of waste that arise from poultry and pig farms vary considerably. No 
representative data for the categories identified in Section 2.11 have been reported for the sector.  

Chapter 3 

3.3.9 

Emissions of odour 

Emissions  of  odour  originate  from  the  activities  described  in  the  previous  sections  such  as  animal 
housing,  manure  storage  structures  and  manure  landspreading.  The  contribution  of  the  individual 
sources  to  the  total  odour  emission  from  a  farm  varies  and  depends  on  many  factors  such  as  the 
general  maintenance  of  the  premises,  the  composition  of  the  manure  and  the  techniques  used  for 
handling and storage of the manure.  

Odour is caused by the microbial degradation of organic substances (e.g. faeces, urine, and feedstuff) 
and is defined by human olfactory perception of a mixture of chemical compounds in the atmosphere 
also known as odorants. The odorant emissions released from animal housing facilities are a complex 
mixture  of  more  than  150  components  in  different  concentrations.  Even  if  all  chemical  substances 
which  lead  to  odour  perception  are  known,  odour  perception  cannot  be  determined  based  on  the 
concentration  of  individual  substances  because  odour  is  defined  by  a  human  physiological  reaction 
[ 474, VDI 2011 ]. 

The most significant sources of odour (odorants) are [ 438, Lacey et al. 2004 ]:  

 

 

 

 

Volatile fatty acids (VFA): the VFA are an intermediate product in the anaerobic fermentation 
of  biological  wastes  to  methane  (CH4).  When  conditions  are  such  that  an  incomplete 
fermentation occurs, then VFA can be volatilised to the atmosphere. 

Ammonia  and  volatile  amines:  these  are  the  product  of  deamination  and  decarboxylation  of 
amino acids. Deamination results in the production of VFA, carbon dioxide, hydrogen gas, and 
ammonia  under  neutral  pH  (from  6  to  7).  For  example,  microbial  breakdown  of  uric  acid  in 
broiler litter is a major source of ammonia. 

Indoles  and  phenols:  these  are  the  by-products  of  amino  acids  metabolised  by  a  variety  of 
intestinal anaerobes. 

Volatile  sulphur-containing  compounds:  these  are  the  by-product  of  anaerobic  digestion  of 
sulphates and sulphur-containing amino acids.  

According  to  the  latest  knowledge  of  the  composition  of  odour,  odour  appears  to  be  dominated  by 
sulphuric compounds, especially at neutral pH and below; in this range ammonia volatilisation is not 
likely to occur [ 500, IRPP TWG, 2011].  

Ammonia  and  hydrogen  sulphide  should  not  be  taken  alone  as  an  indication  of  the  odour  emission 
and/or of the odour nuisance. Ammonia, due to its high perception threshold, contributes to the odours 
emitted by the livestock buildings, but odours may persist even in the total absence of ammonia [ 257, 
France 2010 ]. A clear correlation between odour concentration and ammonia emissions does not exist 
[ 486, Pelletier et al. 2005 ]. In general, measures to abate ammonia and dust emissions also contribute 
to  a  reduction  in  odorant  emissions  but  the  reduction  ratio  can  be  different.  Conversely,  techniques 
that are applied to abate odours generally have only a residual effect on other emissions.  

Data  from  Denmark  show  that,  in  an  integrated  production  unit  with  a  capacity  of  approximately 
100 sows plus fattening pigs, odour emissions from fattening pigs' facilities account for more than two 
thirds  (68–75 %)  of  the  entire  odour  emission  of  an  integrated  production  unit.  The  total  odour 
emission during summer will be 22 900 ouE/s where the farrowing crates for farrowing sows and the 
pens for fattening pigs have fully slatted floors. However, if both the farrowing crates for farrowing 
sows and the pens for finishers have partly slatted floors, the total odour emission will be reduced by 
28 %, which corresponds to 16 600 ouE/s [ 645, Denmark 2005 ].  

Intensive Rearing of Poultry or Pigs 

205 

 
 
 
 
 
 
 
 
 
 
 
Chapter 3 

In the UK, commercial-scale studies have been carried out on four broiler houses, by measuring the 
odour concentration from flocks of approximately 34 000 birds, fed with different protein level diets. 
In  particular,  male  broilers  received  ad  libitum  diets  with  target  protein  levels  (based  on  lysine 
content) of 85 %, 90 %, 100 % or 110 % of the normal commercial level. Odour concentrations were 
fairly  consistent  between  houses,  falling  in  the  range  of  600–800  ouE/s  per  m3  around  day  16,  and
1 300–2 300 ouE/s per m3  around day 30, corresponding to odour emissions in the range of 20 000–
33 000 ouE/s [149, Robertson et al. 2002]. 

Table 3.81  shows  odour  emission  factors  in  use  in  the  Netherlands,  Germany  and  Denmark.  The 
factors  for  the  Netherlands  and  Germany  cover  yearly  average  conditions,  while  for  Denmark 
measurements were carried out in the summer period.  

Table 3.81:  Odour  emission  factors  for  different  animal  categories  and  housing  systems  in  the 

Netherlands, Germany and Denmark 

Type of animal rearing 

Pig farms 
Gestating sows kept in individual crates 
Gestating sows kept loose 
Farrowing sows and piglets kept in crates with 
partly slatted floor 
Farrowing sows and piglets kept in crates with 
fully slatted floor  
Weaners kept in pens with partly slatted floor 
Weaners kept in pens with fully slatted floor 
Finishers kept in pens with partly slatted floor 
Finishers kept in pens with fully slatted floor 
Finishers in deep litter 

Odour emission factors 
(ouE/s per animal) 

DE (1) 

DK (2) (3) 

6.6 
NI 

10 

10 

3 
3 
6.5 
6.5 
4 

16 (7–39) 
16 (7–39) 

72 (40–125) 

100 (56–280) 

7 (4–14) 
7 (4–14) 
19 (8–48) 
29 (13–78) 
NI 

NL 

19 
19 

28 

28 

8 
8 
23 
23 
NI 

Poultry farms 
Layers in a floor system 
Layers in cages (colonies), aerated manure belt 
Layers in cages (colonies), manure belt, no aeration 
Layers in aviary system, aerated belt 
Layers in aviary system, manure belt, no aeration 
Broilers on deep litter 
Female turkeys on solid littered floor 
Male turkeys on solid littered floor 
Ducks on solid littered floor 
(1)  Factors  are  calculated  from  original  figures  given  in  ouE/s/LU  and  the  following  weight  factors  for
live animal mass: gestating sows: 150 kg, farrowing sows: 250 kg, weaners: 20 kg, finishers: 65 kg, 
layers: 1.7 kg, broilers: 1 kg, female turkeys: 6.25 kg, male turkeys: 11.1 kg, Pekin ducks: 1.9 kg.  
(2) The ranges for pigs correspond to 5th percentiles to 95th percentiles. Emissions were calculated from 

0.142 8 
0.102 
0.102 
0.102 
0.102 
0.12 
0.4 
0.71 
0.29 

0.35 
0.34 
NI 
0.34 
0.34 
0.24 
NI 
NI 
NI 

1.53 
0.68 
NI 
NI 
NI 
0.4 
NI 
NI 
NI 

measurements in summer. 

(3) Odour emission factors for poultry are calculated from original figures given in ouE/s/1 000 kg and the

following weight factors per animal: layers: 1.7 kg, broilers: 1 kg. 

NB: NI = no information provided. 

Source: [ 445, VERA 2011 ] [ 645, Denmark 2005 ] [ 474, VDI 2011 ] 

Odour emission factors used in Germany for uncovered manure stores are 3 ouE/s per m2 for pig slurry
stores, 3 ouE/s per m2 for solid manure store with litter and 7 ouE/s per m2 for solid manure without
litter [ 474, VDI 2011 ]. 

206 

Intensive Rearing of Poultry or Pigs 

Chapter 4 

4  TECHNIQUES TO CONSIDER IN THE DETERMINATION OF 

BAT 

This  chapter  describes  techniques  (or  combinations  thereof),  and  associated  monitoring, 
considered  to  have  the  potential  for  achieving  a  high  level  of  environmental  protection  in  the 
activities  within  the  scope  of  this  document.  The  techniques  described  will  include  both  the 
technology used and the way in which the farms are designed, built, maintained, operated and 
decommissioned. 

It  covers  environmental  management  systems,  process-integrated  techniques  and  end-of-pipe 
measures.  Waste  prevention  and  management,  including  waste  minimisation  and  recycling 
procedures  are  also  considered,  as  well  as  techniques  that  reduce  the  consumption  of  raw 
materials, water and energy by optimising use and reuse. The techniques described also cover 
measures used to prevent or to limit the environmental consequences of accidents and incidents, 
as  well  as  farm  remediation  measures.  They  also  cover  measures  taken  to  prevent  or  reduce 
emissions  under  other  than  normal  operating  conditions  (such  as  start-up  and  shutdown 
operations,  leaks,  malfunctions,  momentary  stoppages  and  the  definitive  cessation  of 
operations). 

Annex III to the Directive lists a number of criteria for determining BAT, and the information 
within this chapter will address these considerations. As far as possible, the standard structure in 
Table 4.1  is  used  to  outline  the  information  on  each  technique,  to  enable  a  comparison  of 
techniques and the assessment against the definition of BAT in the Directive. 

This  chapter  does  not  necessarily  provide  an  exhaustive  list  of  techniques  which  could  be 
applied  in  the  sector.  Other  techniques  may  exist,  or  may  be  developed,  which  could  be 
considered in the determination of BAT for an individual farm. 

Table 4.1: 

Information for each technique 

Heading within the sections 

Description 

Achieved environmental benefits 

Cross-media effects 

Environmental performance and operational data 

Technical considerations relevant to applicability 

Economics 

Driving force for implementation 

Example plants 

Reference literature 

In  this  chapter,  the  characteristics  listed  in  the  previous  table are  described  to  provide  all 
elements that are used for the evaluation of techniques, which is carried out to conclude if the 
techniques presented here are BAT or not. 

As  described  in  Chapters  1 to 3,  the  main  emphasis  in  the  application  of  environmental 
measures  in  intensive  farming  is  on  the  reduction  of  emissions  associated  with  manure 
production.  Techniques  that  can  be  applied  at  different  stages  of  the  process  are  linked.  It  is 
clear that the application of reduction measures in the early steps of the animal production chain 
can  influence  the  effect (and  efficiency)  of  any  reduction  measures  applied  in  later  steps.  For 
example, the nutritional composition of the feed and the feeding strategy are important for the 

Intensive Rearing of Poultry or Pigs 

207 

Chapter 4 

animals’ performance, but at the same time they affect the manure composition, and therefore 
influence  emissions  to  air,  soil  and  water  from  housing,  storage  and  landspreading.  The  IED 
puts  the  emphasis  on  prevention;  hence  this  chapter  also  discusses  the  effects  of  nutritional 
management, followed by integrated or end-of-pipe techniques. 

It is important to note that the performance of a reduction technique is closely linked with the 
way in which it is operated, and simply applying a reduction measure may not accomplish the 
highest achievable reduction. This chapter therefore begins with a description of the elements of 
good practice for environmental management, before paying more specific attention to technical 
measures for emissions reduction.  

This  chapter  provides  information  from  techniques  that  are  already  being  implemented  on 
farms, including information on associated costs and the context in which the techniques can be 
used effectively.  

This chapter contains data on excretion and emission levels from specific farms. The quality of 
data is usually indicated, according to the following descriptions: 

 

 

 

 

Derived from measurements: excretion or emission level derived as an average (or with 
conversion units) of measurements carried out in animal houses. 

Measured data: emission level measured on farm. 

Modelled  value:  excretion  or  emission  level  modelled  using  a  modelling  tool,  e.g.  a 
nitrogen mass balance. 

Conclusion  by  analogy:  emission  level  derived  by  analogy  with  a  similar  or  different 
housing system. 

208 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

4.1  Good agricultural practice for environmental 

management 

All organisational activities, products and services interact with and affect the environment and 
are linked to the  health,  welfare  and safety  of both  the  farmer  and the animals,  and  to  all the 
farm  operational  and  quality  management  systems.  Good  farming  management  means  aiming 
for a sound environmental performance, which has been shown to be closely linked to increased 
animal productivity. 

The  key  to  good  practice  is  to  consider  how  activities  on  pig  or  poultry  farms  can  affect  the 
environment and then to take steps to avoid or minimise emissions or impacts by selecting the 
best  mix  of  techniques  and  opportunities  for  each  site.  The  aim  is  to  put  environmental 
considerations  firmly  into  the  decision-making  process.  Managers  should  be  able  to  provide 
evidence that a system is in place to take account of these issues, many of which are referred to 
in ‘Codes of Good Practice’ developed by many Member States. Such action is consistent with 
many of the steps taken by some businesses aiming for formal accreditation under a recognised 
Environmental Management System. 

Each of the various activities that make up farm management can potentially contribute to the 
overall achievement of good environmental performance. It is therefore important that someone 
be  identified  and  given  the  responsibility  to  manage  and  oversee  these  activities.  In  larger 
enterprises in particular, that someone may not necessarily be the owner, but a farm manager, 
who has to make sure that: 

 

 

 

 

 

 

site selection and spatial aspects are considered; 

education and training exercises are identified and implemented; 

activities are properly planned; 

inputs and outputs are monitored; 

emergency procedures are in place; and 

a repair and maintenance programme is implemented. 

The manager and staff should regularly review and evaluate these activities, so that any further 
development and improvements can be identified and implemented.  

Site selection and spatial aspects 
Often the environmental impact of farms is partly due to an unfavourable spatial arrangement of 
activities on the farm site. This can lead to unnecessary transport and additional activities, and 
to emissions close to sensitive receptors. Good farming management can compensate for this to 
a limited extent, but is made easier if attention is paid to spatial planning of farm activities. The 
evaluation and selection of a location for a new livestock farming facility, or the planning of a 
new farm on an existing site, can be considered part of good farming practice, if the following 
conditions are met: 

 

 

 

Unnecessary transport and additional activities are minimised or eliminated. 

Adequate  distances  are  ensured  between  the  house/farm  and  the  sensitive  receptors 
requiring protection, e.g. from neighbours to avoid conflicts arising from odour and noise 
nuisance,  or  from  waters  to  protect  them  from  the  emission  of  nutrients.  Requirements 
regarding the minimum standard distances vary by country, depending also on the type of 
sensitive receptor. Dispersion modelling can also be performed to predict/simulate odour 
concentration in surrounding areas. 

Prevailing climatic conditions (e.g. wind) as well as any specific topographical features, 
such as hills, ridges and rivers are considered. 

Intensive Rearing of Poultry or Pigs 

209 

 
 
 
 
 
 
 
 
Chapter 4 

 

 

 

The potential future development capability of the farm is taken into consideration. 

Any  requirements  of  outline  construction  planning  or  village  development  planning  are 
satisfied. 

The contamination of water is prevented. 

Air pollution can be avoided at sensitive sites by effectively arranging, relocating, or grouping 
emission sources, such as in the case with the main air ducts that collect all the exhaust air from 
all  subdivisions  of  sheds.  For  example,  it  may  be  possible  to  increase  the  distances  of  the 
emission source to any critical sensitive sites, or to relocate the sources so that they lie in a non-
prevailing wind direction. For example, low emission generation areas could  be located closer 
to sensitive receptors whilst farms/houses producing higher emissions could be located further 
away from those same locations. 

Ensuring  adequate  distances  between  the  farm/house  and  the  sensitive  receptors  may  not  be 
generally applicable to existing farms/houses. 

Education and training 
Farm staff should be familiar with production systems and properly trained to carry out the tasks 
for which they are responsible. They should be able to relate these tasks and responsibilities to 
the  work  and  responsibilities  of  other  staff.  This  can  lead  to  a  greater  understanding  of  the 
impacts  on  the  environment  and  the  consequences  of  any  equipment  malfunction  or  failure. 
However, staff may require extra training to monitor these consequences. Regular training and 
updating may be required, particularly when new or revised working practices or equipment are 
introduced. The development of a training record could provide the basis for a regular review 
and evaluation of each person’s skills and competencies. Particular attention should also be paid 
so  that the  staff  is  aware  of  the  relevant  regulations  concerning  animal  health  and  welfare,  as 
well as worker safety. 

Special training may be required for operating and maintaining techniques applied for reducing 
emissions,  above  all  for  the  more  sophisticated  ones  such  as  end-of-pipe  techniques  for  the 
reduction of emissions to air and techniques for the on-farm processing of manure. 

Awareness  of  regulations  and  good  operating  practices  concerning  manure  management, 
planning for manure application, emergency planning and management, repair and maintenance, 
etc.  should  be  part  of  the  training  of  people  responsible  for  transport  and/or  the  spreading  of 
manure in order to prevent emissions to air and water. As an example of the required training, 
some of these aspects are described below:  

 

 

 

 

 

210 

The  rate  of  landspreading  should  follow  a  well-documented  manure  management  plan, 
and  it  should  be  done  evenly  on  the  field.  The  operator  should  be  familiar  with  the 
adjustment of speed, dosing and the capacity of the machinery. 

Slurry  can  vary  widely  in  chemical  composition  in  different  parts  of  the  manure  store. 
The  operator  should  be  familiar  with  possibilities  for  homogenising  the  manure  before 
loading and how to use quick test methods for assessing the amount of plant nutrients in 
the manure. 

Accidental spills happen, mainly in connection  with loading, transport or  landspreading 
of  slurry  or  other  liquid  manure.  The  operator  should  be  able  to  take  precautions,  be 
familiar with alarm systems and safety procedures to avoid spills, as well as be prepared 
to take the right actions in case of spills. 

Manure landspreading and transport can be regulated according to the time of year and 
week, temperature/climate, field slope, buffer zones, etc. The operator should be aware of 
these regulations. 

Any  legal  requirements  regarding  landspreading  technology  should  be  familiar  to  the 
operator. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 4 

Planning activities 
Many activities can benefit from planning, to ensure that they run smoothly and carry reduced 
risks  of  unnecessary  emissions.  An  example  would  be  manure  landspreading.  Other  activities 
that will benefit from a planned approach include the delivery of fuel, feed and other materials 
to the farm (inputs) and the removal of pigs, poultry, eggs, other products, manure and waste 
materials from the farm (outputs). Subcontractors and suppliers also need to be properly briefed. 

Emergency planning and management 
An emergency plan can help the farmer to deal with unplanned emissions and incidents such as 
the pollution of water, if they occur. In the UK, an emergency plan is required under the Code 
of  Good  Agricultural  Practice  for  farmers,  and  land  managers.  This  may  also  cover  any  fire 
risks and the possibility of vandalism. The emergency plan can include: 

 

 

 

 

 

a plan of the farm showing the drainage systems and water sources; 

details of equipment available on the farm, or available at short notice, which can be used 
to  deal  with  a  pollution  problem  (e.g.  equipment  for  plugging  land  drains,  damming 
ditches, or scum boards for holding oil spillages); 

telephone  numbers  of  the  emergency  services,  regulator(s)  and  others,  such  as 
downstream landowners and water abstractors; 

plans of action for certain potential events, such as fires, leaking slurry stores, collapsing 
slurry stores, disease outbreak, uncontrolled run-off from manure heaps, and oil spillages; 

installation  of  standby  electricity  generators  for  emergency  power  to  supply  the 
ventilation during a power surge. 

It  is  important  to  review  procedures  after  any  incident  to  see  what  lessons  can  be  learnt  and 
what improvements can be implemented. 

Repair and maintenance 
It is necessary to check structures and equipment to ensure that they are in good working order. 
Identifying and implementing a structured programme for this work will reduce the likelihood 
of problems arising. Instruction books and manuals should be made available and staff should 
receive appropriate training. 

All  measures  that  contribute  to  the  cleanliness  of  the  farm  help  to  achieve  a  reduction  of 
emissions. These include drying and cleaning the feed store, the housing facilities (defecating, 
feeding  and  lying  areas  in  pig  housing)  and  equipment,  and  the  outlying  areas  around  the 
housing (see Section 4.17 for dust emissions).  

Livestock  buildings  may  have  insulation  and  mechanisms  which  require  regular  cleaning, 
checking, filling and maintenance, for example of fans, cowls, air inlets/outlets, regulating flaps, 
manure  belts,  filters,  temperature  sensors,  electronic  controls,  fail-safe  arrangements,  water 
supply  and  feed  supply  arrangements,  pest  management,  apparatuses  under  pressure,  air 
cleaning systems, fuel and chemical stores.  

Slurry stores could be checked regularly for any signs of corrosion or leakage, and any faults 
need to be corrected, with professional help if necessary. Stores should preferably be emptied at 
least once a year, or as frequently as justifiable, depending on the quality of the construction and 
the  sensitivity  of  the  soil  and  groundwater,  so  that  both  internal  and  external  surfaces  can  be 
checked and any structural problems, damage or degradation put right.  

The operation of manure spreaders (for both solid and liquid manures) can be improved if they 
are cleaned and checked after periods of use and any repairs or refurbishment are carried out. 
Regular checks should be made during operational periods and appropriate maintenance carried 
out as described in the manufacturers’ instructions. Slurry pumps, mixers, separators, irrigators 

Intensive Rearing of Poultry or Pigs 

211 

 
 
 
 
 
 
 
 
 
Chapter 4 

and control equipment will require regular attention and manufacturers’ instructions should be 
followed. 

It is sensible to have a supply of the faster wearing parts available on farm, in order to carry out 
repairs  and  maintenance  quickly.  Usually,  routine  maintenance  can  be  carried  out  by  suitably 
trained farm staff, but more difficult or specialist work will be carried out more accurately by 
experts. 

Feed storage 
No  particular  techniques  have  been  reported  for  a  reduction  of  emissions  to  air  from  feed 
storage on farms. In general, dry matter storage facilities can cause dust emissions, but regular 
inspection and maintenance of the silos and the transport facilities, such as valves and tubes, can 
prevent this. Blowing dry feed into closed silos minimises dust problems. 

When it is considered necessary, silos should be completely emptied to allow inspection and to 
prevent any biological activity building up in the feed. This is particularly important in summer, 
to prevent deterioration of the feed quality and development of odorous compounds. When feed 
bins are emptied, care should be taken not to increase dust emissions. 

4.1.1 

Storage and disposal of dead animals  

Description 
Common practices related to the handling and storage and disposal of dead animals in order to 
prevent  or  reduce  emissions  have  been  described  in  Section  2.12.  For  the  disposal  of  dead 
animals, waste incineration and co-incineration are indicated among the authorised procedures. 
In particular, two distinct pathways exist: 

a. Diversion of dead animals from farms to a centralised, large animal waste incinerator 
Specialised services are commonly used to collect dead animals from farms and to process them 
in  centralised  treatment  facilities.  Large  centralised  incineration  facilities,  treating  different 
types of waste, fall under a regulatory framework and are designed to meet the provisions set 
out in the Industrial Emissions Directive (2010/75/EU), Chapter IV and Annex VI, or equivalent 
requirements.  Plants  incinerating  only  dead  animals  are  regulated  by  the  Animal  By-Products 
Regulation ((EC) 1069/2009). The European Reference Documents reporting the Best Available 
Techniques  for  these  activities  are  the  BAT  Reference  Document  on  Slaughterhouses  and 
Animals By-products Industries [ 581, COM 2005 ]. 

Good  housekeeping  practices  are  essential  to  ensure  hygienic  on-farm  storage  of  the  dead 
animals  which  are  not  going  to  be  incinerated  on  farm.  In  anticipation  of  collection  by  an 
authorised waste collector, fallen stock should be stored in closed, leakproof containers to avoid 
spillage or odour problems. Refrigeration may be necessary, especially in hot climates, when the 
removal frequency is not regular (e.g. more than weekly) [ 624, IRPP TWG 2013 ]. 

b. On-farm incineration in a dedicated incinerator 
Incinerators which incinerate only dead animals such as on-farm incinerators for the disposal of 
fallen stock are exempted from Chapter IV of Directive 2010/75/EU and are instead regulated 
by  Regulations  (EC)  1069/2009  and  142/2011.  Incinerators  must  be  approved  in  accordance 
with Article 24 of Regulation (EC) 1069/2009 and must comply with Article 6 of and Annex III 
to  Regulation  (EC)  142/2011  (i.e.  hygiene  conditions,  operating  conditions,  residue  disposal 
requirements, temperature measurement requirements, requirements for dealing with abnormal 
operating  conditions,  water  discharge  requirements,  storage  of  animal  by-products  that  are 
awaiting incineration and storage of ashes). 
Commission  Regulation  (EU)  142/2011  of  25  February  2011  lays  down  general  and  specific 
operating conditions for incineration and co-incineration plants treating only animal by-products 
and  derived  products,  for  two  different  capacity  thresholds:  more  than  50 kg  per  hour  or  per 

212 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

batch  (high-capacity  incinerators  or  co-incinerators)  and  at  or  less  than  50 kg  per  hour  or  per 
batch (low-capacity incinerators or co-incinerators).  

Achieved environmental benefits 
The  biosecurity  risk  for  contamination  of  humans  or  animals  and  the  risk  of  environmental 
pollution are minimised by the appropriate storage and disposal of dead animals.  

Cross-media effects 
If refrigeration is applied during storage on farm, energy consumption is increased substantially.  
Small-scale incinerators fitted with afterburners produce more emissions of oxides of nitrogen 
than incinerators without afterburners, because of the higher heat input into the incinerator from 
the afterburner. 

Environmental performance and operational data 
a. Diversion of dead animals from farms to a centralised, large animal waste incinerator 
Large,  centralised  incinerators  allow  better  control  than  small-scale  incinerators,  concerning 
issues related to the reduction and supervision of emissions to air. On the other hand, the impact 
on the spread of a disease from farm to farm by collecting and delivering dead animals off-farm 
at a larger centralised plant is difficult to evaluate.  

b. On-farm incineration in a dedicated incinerator 
Emissions from small-scale on-farm incinerators have been reported for different types of fuel, 
and for operating conditions with or without an afterburner. Typical emissions from combustion 
are dust, SOX, NOX, CO2 and CO. 

Carbon dioxide emissions are primarily governed by the carbon content of the fuel burnt and the 
wastes  incinerated.  The  combustion  efficiency  is  an  important  additional  factor,  which 
determines the full oxidation of carbon to CO2. The use of afterburners is essential to minimise 
emissions  of  VOCs  and  CO  and  may  even  reduce  particulate  matter;  however,  it  should  be 
noted that even small-scale incinerators equipped with an afterburner but poorly operated and/or 
maintained (e.g. overloaded) can give rise to much greater emissions of most pollutants than a 
simpler  design  not  equipped  with  an  afterburner  but  with  a  carefully  operated  system  
[ 476, AEAT 2002 ].  

Poor loading of incinerators is considered to be a major problem causing inefficient combustion 
and  increased  emissions.  Where  possible,  the  furnace  should  be  preheated  to  at  least  850  °C 
before feedstock is loaded to prevent smouldering at lower temperatures. If the dead animals are 
loaded  into  a  relatively  cool  furnace,  there  will  be  a  period  of  pyrolysis  followed  by  poor 
combustion. 

When  an  afterburner  is  in  place,  it  should  be  activated  well  before  the  main  combustion 
chamber burner is lit so that it is functioning at an optimum temperature. Indeed operation of the 
main burners should be interlocked with the afterburner chamber temperature. This would help 
to  minimise  emissions  during  the  warm-up  of  the  main  combustion  chamber.  The  burner  and 
afterburner  should  both  be  switched  on  for  the  full  combustion  cycle  to  ensure  minimum 
pollutant emissions [ 476, AEAT 2002 ]. 

Sulphur dioxide emissions are directly proportional to the sulphur content of the fuel used and 
waste incinerated. Refined gaseous fuels have negligible quantities of sulphur compounds and 
consequently  the  sulphur  emissions  are  due  to  sulphur  in  the  animal  remains.  Examples  of 
average  emissions  in  concentration  and  per  operating  cycle  are  presented  in  Table 4.2  and 
Table 4.3.  

Intensive Rearing of Poultry or Pigs 

213 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.2:  Examples  of  emission  concentrations 

in  flue-gases  from  small-scale  on-farm 

incinerators 

Unit 

Incinerators with afterburners 

Incinerators without 
afterburners 

Poultry 
Pigs 
Propane  Diesel 

Poultry 
Propane 
58 
179 
58 
1 030 
381 
61 

Type of animal 
Fuel 
Dust (1) 
SO2 
HCl 
CO 
NOX (2) 
VOCs (3) 

Poultry 
Kerosene 
107 
456 
112 
348 
225 
869 

Pigs 
Gas oil 
173 
127 
26 
1 180 
129 
78 

Dioxins and furans (4) 

90 
34 
8 
1 620 
303 
484 

36 
376 
24 
1 650 
376 
117 

mg/Nm3 
mg/Nm3 
mg/Nm3 
mg/Nm3 
mg/Nm3 
mg/Nm3 
ng I-
TEQ/Nm3 
 % 
CO2 
(1) Dust as total particulate matter. 
(2) NOX as NO2. 
(3) VOCs as total organic carbon. 
(4) I-TEQ = international toxic equivalent. 
NB: Mass concentrations are standardised at 11 % O2, dry gas, temperature 273.15 K, pressure 101.3 kPa. 
Source: [ 476, AEAT 2002 ] 

0.21 

0.19 

0.08 

7.2 

0.1 

7.6 

7.7 

0.1 

6.9 

7.5 

Pigs 
Oil 
277 
313 
56 
5 840 
352 
3 490 

0.05 

9 

Table 4.3:  Examples of total emissions per operating cycle from small-scale on-farm incinerators 

Unit 

Incinerators with afterburners 

Incinerators without 
afterburners 
Pig 

Type of animal 

  Fuel 
Dust (1) 
SO2 
HCl 
CO 
NOX 
VOCs (2) 

Dioxins and furans 

Poultry 
Propane 
0.06 
0.19 
0.06 
1.1 
0.41 
0.07 

190 

106 

Pig 

Poultry 

Poultry 
Propane  Diesel  Kerosene  Gas oil 
0.79 
0.64 
0.12 
5.3 
0.58 
0.35 

0.08 
0.88 
0.06 
3.9 
0.88 
0.27 

0.25 
1.1 
0.26 
0.84 
0.51 
1.8 

0.08 
0.03 
0.01 
1.4 
0.27 
0.43 

Pig 
Oil 
0.3 
0.31 
0.06 
6.3 
0.38 
3.8 

90 

246 

220 

367 

210 

200 

910 

505 

50 

302 

kg/cycle 
kg/cycle 
kg/cycle 
kg/cycle 
kg/cycle 
kg/cycle 
ng I-
TEQ/cycle 
kg/cycle 

CO2 
NB: See footnotes in Table 4.2. 
Source: [ 476, AEAT 2002 ] 

Technical considerations relevant to applicability 
The  storage  of  dead  animals  at  appropriate  temperatures  is  generally  applicable.  The  storage 
time depends on the weather conditions and the frequency of removal.  

Economics, driving force for implementation: no information provided. 

Example plants 
In Belgium (Flanders), fallen stock with a smaller size such as poultry or piglets can be stored in 
closed, airtight containers while dead animals of a medium size such as pigs can be stored on a 
surface  that  is  easy  to  clean  and  disinfect,  covered  appropriately  with  a  durable  and  easily 
maintainable material without permitting access to insects and animals [ 631, Belgium-Flanders 
2013 ]. 

Reference literature 
[  476,  AEAT  2002  ]  [  581,  COM  2005  ]  [  624,  IRPP  TWG  2013  ]  [  631,  Belgium-Flanders 
2013 ] 

214 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.2 

Environmental management systems 

Description 
A formal system to demonstrate compliance with environmental objectives. 

The Directive defines ‘techniques’ (under the definition of 'best available techniques') as ‘both 
the  technology  used  and  the  way  in  which  the  installation  is  designed,  built,  maintained, 
operated and decommissioned’. 

In this respect, an environmental management system (EMS) is a technique allowing operators 
of  installations  to  address  environmental  issues  in  a  systematic  and  demonstrable  way.  EMSs 
are most effective and efficient where they form an inherent part of the overall management and 
operation of an installation. 

An  EMS  focuses  the  attention  of  the  operator  on  the  environmental  performance  of  the 
installation; in particular through the application of clear operating procedures for both normal 
and  other  than  normal  operating  conditions,  and  by  setting  out  the  associated  lines  of 
responsibility. 

All  effective  EMSs  incorporate  the  concept  of  continuous  improvement,  meaning  that 
environmental management is an ongoing process, not one project which eventually comes to an 
end. There are various process designs, but most EMSs are based on the plan-do-check-act cycle 
(which  is  widely  used  in  other  company  management  contexts).  The  cycle  is  an  iterative 
dynamic  model,  where  the  completion  of  one  cycle  flows  into  the  beginning  of  the  next  (see 
Figure 4.1). 

Figure 4.1:  Continuous improvement in an EMS model 

An  EMS  can  take  the  form  of  a  standardised  or  non-standardised  (‘customised’)  system. 
Implementation and adherence to an internationally accepted standardised system, such as EN 
ISO 14001:2015, can give higher credibility to the EMS especially when subjected to a properly 
performed  external  verification.  EMAS  provides  additional  credibility  due  to  the  interaction 
with the public through the environmental statement and the mechanism to ensure compliance 
with  the  applicable  environmental  legislation.  However,  non-standardised  systems  can,  in 
principle, be equally effective provided that they are properly designed and implemented. 

Intensive Rearing of Poultry or Pigs 

215 

Chapter 4 

While both standardised systems (EN ISO 14001:2015 or EMAS) and non-standardised systems 
apply in principle to organisations, this document takes a narrower approach, not including all 
activities of an organisation, e.g. with regard to their products and services, due to the fact that 
the Directive only regulates installations/plants. 

An EMS can contain the following components: 

1.  commitment of management, including senior management; 
2.  definition,  by  the  management,  of  an  environmental  policy  that  includes  the  continuous 

improvement of the environmental performance of the installation; 

3.  planning  and  establishing  the  necessary  procedures,  objectives  and targets,  in  conjunction 

with financial planning and investment; 
implementation of procedures paying particular attention to: 

4. 

a)  structure and responsibility, 
b)  training, awareness and competence, 
c)  communication, 
d)  employee involvement, 
e)  documentation, 
f)  effective process control, 
g)  maintenance programmes, 
h)  emergency preparedness and response, 
i)  safeguarding compliance with environmental legislation; 

5.  checking performance and taking corrective action paying particular attention to: 

a)  monitoring  and  measurement  (see  also  the  JRC  Reference  Report  on  Monitoring  of 

emissions from IED installations - ROM) [ 576, COM 2017 ], 

b)  corrective and preventive action, 
c)  maintenance of records, 
d)  independent  (where  practicable)  internal  or  external  auditing  in  order  to  determine 
whether  or  not  the  EMS  conforms  to  planned  arrangements  and  has  been  properly 
implemented and maintained; 

6.  review  of  the  EMS  and  its  continuing  suitability,  adequacy  and  effectiveness  by  senior 

management; 

7.  following the development of cleaner technologies; 
8.  consideration  for  the  environmental  impacts  from  the  eventual  decommissioning  of  the 

installation at the stage of designing a new plant, and throughout its operating life; 

9.  application  of  sectoral  benchmarking  (e.g.  EMAS  Sectoral  Reference  Document)  on  a 

regular basis. 

Specifically for the intensive poultry or pig rearing sector, the following features are part of the 
EMS in some cases:  

10.  noise management plan (see Section 4.14); 
11.  odour management plan (see Section 4.10.1.5). 

Achieved environmental benefits 
An EMS promotes and supports the continuous improvement of the environmental performance 
of the installation. If the installation already has a good overall environmental performance, an 
EMS helps the operator to maintain the high performance level. 

Environmental performance and operational data 
Farms can vary in scale and complexity, from a single building performing one task only (e.g. 
rearing broilers or finishing pigs) where all materials, such as feed, are purchased ready from the 

216 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

manufacturer  and  employing  one  person,  to  large  farms  with  multiple  activities  and  several 
employees.  

Depending  on  the  level  of  complexity  of  the  farm,  the  implementation  of  an  environmental 
management system may vary significantly, from the basic control of the rearing process and the 
performance of the farm in terms of consumption (i.e. feed, energy, water) and production (e.g. 
live weight of animals, quantity of manure, other waste), to a full implementation with recording 
of  several  operating  parameters,  monitoring  of  emissions,  validation  by  an  external  EMS 
verifier. 

Cross-media effects 
None  reported.  The  systematic  analysis  of  the  initial  environmental  impacts  and  scope  for 
improvements  in the  context  of the  EMS  sets the  basis  for  assessing  the  best  solutions for all 
environmental media. 

Technical considerations relevant to applicability 
The components described above can be applied in full or in part to all installations within the 
scope of this document. The scope (e.g. level of detail) and nature of the EMS (e.g. standardised 
or  non-standardised)  will  be  related  to  the  nature,  scale  and  complexity  of  the  farm,  and  the 
range of environmental impacts it may have. 

Economics 
It  is  difficult  to  determine  accurately  the  costs  and  economic  benefits  of  introducing  and 
maintaining a good EMS. There are also economic benefits that are the result of using an EMS 
and these vary widely from sector to sector.  

External costs relating to verification of the system can be estimated from guidance issued by 
the International Accreditation Forum [ 577, IAF 2010 ]. 

Driving forces for implementation 
The driving forces for the implementation of an EMS include: 

 

 

 

 

 

 

 

improved environmental performance; 

improved  insight  into  the  environmental  aspects  of  the  company  which  can  be  used  to 
fulfil  the  environmental  requirements  of  customers,  regulatory  authorities,  banks, 
insurance companies or other stakeholders (e.g. people living or working in the vicinity of 
the installation); 

improved basis for decision-making; 

improved motivation of personnel (e.g. managers can have confidence that environmental 
impacts  are  controlled  and  employees  can  feel  that  they  are  working  for  an 
environmentally responsible company); 

additional opportunities for operational cost reduction and product quality improvement 

improved company image; 

reduced liability, insurance and non-compliance costs. 

Example plants 
No example farms applying ISO 14001 audited EMSs have been reported. Some MS implement 
an EMS as part of permitting and audit compliance as part of their inspection regime (UK). 

Reference literature 
[ 576, COM 2017 ] [ 577, IAF 2010 ] [ 579, Reg. 1221/2009 ] [ 578, DG Environment 2010 ] 
[ 580, CEN 2015 ] 

Intensive Rearing of Poultry or Pigs 

217 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.3  Nutritional management 

Reducing the excretion of nutrients (e.g. N, P) in manure can reduce emissions, e.g. decreasing 
the amount of N in manure will not only abate ammonia emissions but also other potential N 
losses (leaching, denitrification). Nutritional management covers all techniques to achieve this 
reduction. The aim is to meet the animals’ nutritional needs without causing a negative impact 
on animal health and welfare and taking into account the economics of the production process.  

A goal of nutritionists is to ensure that animals are not fed with more nutrients (in particular N 
and P) than required for the target level of production, with the intention to minimise excretion 
to levels that cannot be avoided due to metabolic activity. In other words, nutritional measures 
aim to reduce the amount of nitrogen waste from undigested or catabolised nitrogen, which is 
mainly  excreted  in  the  form  of  urea  (uric  acid  in  poultry  manure)  and  is  rapidly  degraded  to 
ammonia and ammonium. Moreover, reducing N excretion is effective for emission abatement 
at all stages of manure management (housing, storage, landspreading). 

In practice, protein levels in animal feed are often higher than actually required. Safety margins 
in the protein content of the diet are used to account for:  

 

 

 

 

suboptimal amino acid ratios;  

variations in requirements between animals with different genotypes;  

variations in requirements caused by differences in age or production stages;  

variations in the actual content and digestibility of essential amino acids in the diet.  

Therefore,  the  protein  content  of  the  diet  and  the  resulting  N  excretion  can  be  reduced  by 
matching  the  protein/amino  acids  content  of  the  diet  as  closely  as  possible  to  the  animal’s 
requirements [ 508, TFRN 2014 ]. 

Efforts  over  time  in  increasing  feed  digestibility  have  led  to  the  use  of  large  quantities  of 
enzymes  (phytase,  xylanase,  protease,  glucanase,  etc.)  nowadays  in  the  animal  feed  industry. 
Progress in genetics and nutrition has also led to a considerable improvement in the efficient use 
of  feed.  The  improved  utilisation  of  feed  allows  the  reduction  of  the  feed  nitrogen  input  and 
hence N excretion even further. 

4.3.1 

Nutritional measures  

Description 
The main nutritional strategies to decrease the amount of nitrogen and phosphorus excreted are 
as follows: 

1. 

Reduce the crude protein content by using a N-balanced diet based on net energy for pigs 
and on metabolisable energy systems for poultry, and digestible amino acids [ 506, TWG 
ILF BREF 2001 ] [ 30, Spain 2001 ] [ 281, France 2010 ] [ 624, IRPP TWG 2013 ]. 

In  order  for  the  animals  to  realise  their  growth  potential  and  achieve  the  best  levels  of 
performance through maximum rates of protein synthesis, the proper amount of essential amino 
acids are supplied, avoiding both excesses and deficiencies. Diets that are not properly balanced 
with  the  animal's  requirements  in  terms  of  energy  and  digestible  amino  acids  provide  the 
necessary quantities of the limiting nutrients only with overdoses of others, hence resulting in an 
increase of excreted nutrients that brings about higher emissions to the environment.  

2.  Multiphase feeding with a diet formulation of a diet adapted to the specific requirements 

of the production period (nitrogen and phosphorus). 

218 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Animals’  requirements  change  over  the  growing/production  periods.  Consequently,  adjusting 
better the composition of the diet to the requirements of the individual animal, e.g. according to 
age and weight of animals, is a general method to decrease the amount of nutrients excreted by 
animals (multiphase feeding).  

3. 

Improvement of the feed characteristics, e.g. through the following methods: 

 

 

 

 

application  of  low  crude  protein  (CP)  levels,  use  of  synthetic  amino  acids  and  related 
compounds in low CP-amino acid supplemented diets (nitrogen); 

application  of  low  phosphorus  levels,  use  of  phytase  to  increase  digestibility  and/or 
digestible inorganic feed phosphates (phosphorus); 

use  of  other  authorised  feed  additives,  including  zootechnical  additives,  which  have  a 
favourable effect on the environmental consequences of animal production (nitrogen); 

increased use of highly digestible raw materials (nitrogen and phosphorus). 

Among the strategies presented above, the multiphase feeding and the use of diet formulations 
with  reduced  CP  and  phosphorus  contents  are  described  in  Section  4.3.2  and  Section  4.3.3, 
respectively. Techniques to reduce the phosphate levels in the manure by increasing phosphorus 
digestibility  are  described  in  Sections  4.3.4  and  4.3.5.  The  application  of  other  additives  to 
animal feed, which is another technique that can be implemented in order to reduce excretion of 
nutrients and/or ammonia emissions, (e.g. authorised acidifying salts to reduce the pH of urine 
or enzymes to improve the digestibility of feed) is described in Section 4.3.6.  

Achieved environmental benefits 
Considerable  reductions  in  the  N  and  P  excreted  can  be  achieved  by  limiting  excess  nutrient 
intake  and/or  improving  the  nutrient  utilisation  efficiency  of  the  animal.  A  reduction  in 
excretion  allows  a  reduction  in  emissions  from  pig  or  poultry  rearing,  which  eventually 
improves all further steps of the production chain, resulting in environmental advantages in all 
downstream operations.  

Cross-media effects 
Nutritional management is the most important preventive measure to reduce the pollution load 
in farms. No environmental cross-media effect is reported.  

Environmental performance and operational data 
Across the European agricultural regions, there are many differences in farm practices, species 
used and nutritional management; hence standard production conditions can vary considerably. 
Examples of reported standard levels of excretion of nitrogen (N) and diphosphorus pentoxide 
(P2O5)  are  displayed  in  Table 4.4.  These  values  refer  to  a  baseline  situation  in  which  no 
nutritional measures are applied. 

Intensive Rearing of Poultry or Pigs 

219 

 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.4: 

Standard  levels  of  nitrogen  (N)  and  diphosphorus  pentoxide  (P2O5)  excretion  in 
Germany, Finland and France 

Animal categories 

N 
(kg/animal place/year) 

P2O5 
(kg/animal place/year) 

DE 

FI 

FR 
(1) (2) 

DE 

FI 

FR 
(1) (2) 

4.3 
13.0 
27–36 

NI 
NI 
20.3–29.3 

Pigs 
Weaners 
Growers/Finishers 
Boars and sows 
Poultry 
Laying hens 
Broilers 
Turkeys 
(1) Annual data were calculated for the typical number of production cycles per year, equivalent to 6.5 for 

2.3 
6.3 
14–19 

0.41 
0.16 
0.52 

0.74 
0.29 
1.64 

0.61 
0.31 
1.19 

0.37 
0.21 
0.62 

4.03 
13.7 
24.6 

2.02 
6.30 
14 

NI 
NI 
16.7 

NI 
NI 
NI 

NI 
NI 
NI 

weaners and 3 for fattening pigs. 

(2) Annual data were calculated for the typical number of production cycles per year, equivalent to 6.15 for 

standard broilers and 2.6 for medium-size turkeys. 

NB: NI = no information provided. 
Source: [ 414, Fefana 2001 ] [ 323, Finland 2010 ] [ 329, CORPEN 2003 ]  

In comparison with the standard levels reported in Table 4.4, reduced levels of excreted nitrogen 
and/or phosphorus achieved by applying nutritional measures are reported, from a minimum of 
4 % to > 30 %, depending on the type of technique applied and the animal category. Examples 
of reduction levels of excretion associated with specific nutritional techniques are given in other 
parts  of  Section  4.3.  As  an  example,  a  comparison  of  excreted  nitrogen,  phosphorus  and 
potassium levels for a standard diet and a bi-phase diet applied to the rearing of pigs is given in 
Table 4.5.  

Table 4.5:  Examples of the influence of nutrition measures on excreted nitrogen, phosphorus and 

potassium for the rearing of pigs 

Animal 

Diet/parameters 

Sows 

Weaners  
(8–30 kg)  

Fattening 
pigs 
(30–112 kg)  

Two phases: CP 
14 % gestating; 
16.5 % farrowing 
1 200 kg feed/ap/yr 
Two phases: CP 
20 % (1st phase); 
18 % (2nd phase)  
FCR: 1.74 kg/kg 
Two-phases: CP 
16.5 % (growers); 
15 % (finishers)  
FCR: 2.86 kg/kg 
during fattening 
(+0.006 kg per extra 
kg over 112 kg) 

N (1) 
(kg/ap/yr) 

P (1) 
(kg/ap/yr) 
Standard  Bi-phase  Standard  Bi-phase  Standard  Bi-phase 

K (1) 
(kg/ap/yr) 

24.60 

20.40 

6.11 

4.80 

9.08 

8.00 

4.03  

3.64  

0.91  

0.72  

2.02  

1.89  

13.68  

11.37  

2.76  

1.89  

5.52  

4.82 

Per each 
further kg (2) 
(1) Levels are calculated for the typical number of production cycles per year, equivalent to 6.5 for weaners and 3 for 

0.08  

0.08  

0.20  

0.18  

0.05  

0.03  

NA 

fattening pigs, as reported in the reference. 

(2) Correction to apply when the slaughtering weight is over 112 kg of the LW. 
NB: NA = not applicable. 

Source: [ 329, CORPEN 2003 ]  

220 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

The effects of the various nutritional strategies have independent effects on ammonia emission. 
This means that these effects are additive [ 508, TFRN 2014 ].  

According  to  a  reported  example  of  combining  four  different  nutritional  measures,  a  69 % 
reduction  of  total  ammonia  emissions  could  be  achieved  in  the  rearing  of  fattening  pigs.  The 
reduction was achieved by applying the following measures: 

 

 

 

 

lowering the crude protein intake in combination with addition of amino acids; 

shifting  nitrogen  excretion  from  urine to faeces  by  adding  fermentable carbohydrates to 
the diet; 

lowering the urine pH, by adding acidifying salts to the diet; 

lowering  the  pH  of  faeces,  by  adding  fermentable carbohydrates  to  the  diet  [324, 
Netherlands 2010] [448, Aarnink et al. 2007].  

Nutritional programmes 
In  practically  every  country,  programmes  exist  for  advising  farmers  about  nutrition 
management. Nutritional standards are produced to provide farmers with nutrient requirements 
for  efficient  production,  taking  into  account  animal  welfare  and  the  need  for  environmental 
protection. 

In the Flemish part of Belgium, low-nitrogen or low-phosphorus feed or a combination of both 
are  legally  recognised  through  a  contract  between  feed  manufacturers  and  the  government  
[ 506, TWG ILF BREF 2001 ].  

In  Germany,  the  RAM-feeding  programmes  of  low-nitrogen-and-phosphorus  feeds  were 
developed by farmers and feed manufacturers. They also rely on contracts that are controlled by 
the regional agricultural chambers.  

In France, CORPEN recommends a two-phase feeding programme for each physiological stage 
(e.g.  first  weaner  stage  for  pigs  of  around  8 kg  to  12  kg  and  second  weaner  stage  for  older 
weaners,  lactating/gestating  sows,  grower/finisher  pigs)  based  on  low-protein  and/or  low-
phosphorus diets [ 329, CORPEN 2003 ]. 

Feeding recommendations are prepared for Finland by MTT Agrifood Research Finland and for 
the UK by the British Society of Animal Science [ 323, Finland 2010 ]. 

In Denmark, data on nutritional management (e.g. consumption of all feed compounds, weight 
and age of the animals) from farms are used to calculate the actual average crude protein and 
phosphorus content of all feed mixes used in the period and a norm value for the content of N 
and P in the manure; this information is collected each year as a part of the fertiliser accounting 
management  plan  for  crop  production.  All  documentation  has  to  be  kept  for  5  years  in  a  log 
book [ 330, Denmark 2010 ]. 

Mandatory nutritional management systems are already in place in some Member States and are 
backed up by practical experience. They are mainly run in two ways that are described below. 

Monitoring of the nutrient input and output 
In  those  areas  where  intensive  livestock  production  is  responsible  for  high  environmental 
pressure,  farmers  have  to  keep  a  register  of  their  nitrogen  and/or  phosphate  applications.  The 
mineral bookkeeping systems monitor the input and output flows at the farm level. Examples of 
regulatory tools are: the Act on Classified Installations for Environmental Protection in France, 
the  Manure  Action  Plan  (MAP)  and  the  Sustainable  Nitrogen  Management  in  Agriculture 
(PGDA)  in  Belgium,  the  Mineral  Accounting  System  (MINAS)  in  the  Netherlands,  and  the 
Düngerverordnung in Germany. 

Intensive Rearing of Poultry or Pigs 

221 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Estimation of nutrient excretion from the slurry on the basis of the feed characteristics 
As nutrient output is highly correlated with nutrient intake, it should be calculated based on the 
characteristics of the feeds in terms of the correlation with the mineral content in diets. Indeed, 
this  is  done  in  those  Member  States  where  nutritional  management  systems  are  already 
implemented. Indications of the systems used in France (CORPEN), Belgium (Flanders) (MAP) 
and  Germany  (RAM)  are  given  in  this  section  and  in  the  following  sections  under  'Achieved 
environmental benefits'. 

If  the  feeding  system  is  different  to  and/or  more  efficient  than  the  nutritional  specifications 
used, regression systems allow the actual level of excretion to be calculated as a function of the 
feed  characteristics  (protein  and/or  phosphorus  contents).  As an  example,  the  set  of  equations 
used in Belgium is reported in Table 4.6. 

Table 4.6:  Regressions used in Belgium (Flanders) to calculate the actual level of excretion 

Animal species 

Nitrogen (N) excretion 
(kg/animal/year) 

Weaners weighing from 7 kg to 20 kg 
Other pigs weighing from 20 kg to 110 kg 
Other pigs weighing more than 110 kg 
Sows, including piglets with a weight < 7 kg 
Boars 
Laying hens  
Laying hens/breeders 
Breeding stock of laying hens/breeders 
Broilers  
Broiler breeders 
Breeding stock of broiler breeders  
Y = Production (kg) of N and P2O5 per animal and per year. 
X = Consumption (kg) of crude protein (CP) and phosphorus (P) per animal per year. 

Y = 0.10·X-1.322 
Y = 0.13·X-3.046 
Y = 0.133·X-0.2208 
Y = 0.133·X-0.2208 
Y = 0.133·X-0.2208 
Y = 0.1496·X-0.2455  
Y = 0.1548·X-0.2305 
Y = 0.1492·X-0.1149  
Y = 0.1541·X-0.5283  
Y = 0.1517·X-0.1918  
Y = 0.1571·X-0.1705  

Source: [ 625, BE Flanders 2013 ]  

Diphosphorus 
pentoxide 
(P2O5) excretion 
(kg/animal/year) 
Y = 1.65·X-0.819 
Y = 1.94·X-1.698 
Y = 1.8503·X+0.344 
Y = 1.8503·X+0.344 
Y = 1.8503·X + 0.344 
Y = 2.2254·X-0.0606  
Y = 2.2606·X-0.0587 
Y = 2.2277·X-0.0512  
Y = 2.334·X-0.196  
Y = 2.2606·X-0.0587  
Y = 2.2152·X-0.0770  

In France, the amount of nutrients that are excreted, the amount lost as emissions and those that 
are available for spreading are estimated. For poultry, tables are used for each of the many types 
of animals produced. For pigs, the ‘simplified accounting balance’ takes into account the main 
factors involved in pig excretion, i.e. feeding technique and level of performance, and has been 
published as a calculation sheet and as a computer model. All compound flows are taken into 
consideration. Nutrients that are provided to animals are estimated based on pigs' live weight. 
Elements  associated  with  manure  and  bedding  are  determined  by  the  initial  feed  composition 
and  quantity.  Nitrogen  emission  flows  are  calculated  as  a  function  of  the  excreted  quantity, 
depending  on  the  rearing  system.  Emissions  from  houses  are  then  estimated  as  the  difference 
between input (animal + feed + bedding) and output (animal + gas losses) flows [ 328, CORPEN 
2006 ] [ 329, CORPEN 2003 ]. 

Examples of diet formulations applied in different Member States are reported in Section 9.2. 

Technical considerations relevant to applicability 
Nutritional measures are considered generally applicable and their use is widespread across the 
EU. 

222 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
Cost estimates of nutritional measures take into account the following factors: 

 

 

 

 

 

additional feed costs (or savings depending on raw materials' market prices); 

additional costs for increased storage needs when adding a new phase feeding strategy; 

savings in water costs; 

savings in slurry transport and treatment or spreading costs; 

savings in capital investment, e.g. less storage capacity required for raw materials. 

Where  dietary  protein  levels  decrease  with  increasing  cereal  use  in  feed,  then  the  changes  in 
cereal price are important for the sustainability of the nutritional management measures. With 
successive CAP reforms, the inclusion of higher levels of cereals has been favoured and the cost 
of implementing reduced protein diets has decreased accordingly. The cost and affordability of 
the feeding measure depends on the local commodity supply (such as cereals’ affordability), the 
local land availability for spreading manure (limited availability will enhance the value of the 
feeding measure), and the world market price for protein-rich feedstuffs. High prices of protein-
rich  feedstuffs  increase  the  attractiveness  of  the  feeding  measures,  as  will  the  increasing 
availability of synthetic amino acids. 

The  costs  that  feeding  measures  imply  depend  on  the  market  fluctuations  in  feedstuff  prices. 
These price fluctuations are too large to derive a universal estimate (see Table 4.7). However, as 
a general rule one can assume that the extra feed cost in pigs and poultry will range from 0 to 
3 % of the total feed cost; FEFAC estimated an increase by 2–3 % for poultry and 1–1.5 % for 
fattening pigs [ 704, FEFAC 2001 ]. In periods of extremely low prices of soybean meal, the 
extra  feed  cost  may  increase  by  up  to  about  5 %, depending  on the  prices  of  the  amino  acids 
[ 506, TWG ILF BREF 2001 ]. 

Examples of contract prices for raw materials used in the feed formulation for pigs are given in 
Table 4.7. 

Table 4.7:  Contract  prices  for  raw  materials  and  estimates  of  raw  material  costs  for  balanced 

feed formulations for pigs 

Feedstuff 

Wheat 
Barley 
Maize 
Wheat bran 
Corn gluten feed 
Peas 
Soybean meal 
Rapeseed meal 
Sunflower meal in the husk 
Plant oil 
Molasses of sugar cane 
L-Lysine HCl 
DL-methionine 
L-threonine 
L-tryptophan 
Calcium carbonate  
Calcium phosphate  
3-Phytase 
Balanced growers formula 
Balanced finishers formula 
NB: NI = no information provided. 

February 
2010 
(EUR/tonne) 
116 
99 
125 
84 
144 
170 
329 
199 
143 
741 
168 
2 100 
3 650 
2 200 
21 000 
50 
330 
9 500 
146.9 
135.1 

November 
2010 
(EUR/tonne) 
215 
195 
214 
163 
200 
242 
350 
236 
191 
978 
178 
1 750 
3 800 
1 900 
16 000 
50 
380 
9 500 
228.5 
219.6 

September 
2011 
(EUR/tonne) 
202 
203 
226 
131 
NI 
256 
318 
204 
149 
953 
NI 
1 950 
3 650 
1 880 
10 000 
50 
560 
9 500 
212.6 
207.6 

Source: [ 281, France 2010 ] [ 450, IFIP 2011 ] 

Intensive Rearing of Poultry or Pigs 

223 

 
 
 
 
 
 
 
 
Chapter 4 

An  example  of  the  effect  of  price  fluctuation  of  feed  materials  and  amino  acids  on  the  extra 
costs (or savings) incurred by the implementation of low-protein diets in the rearing of fattening 
pigs is reported in Table 4.22. 

Driving force for implementation 
The  necessity  to  comply  with  nitrogen  loads  in  Nitrate  Vulnerable  Zones  or  with  basin 
management  plans,  according  to  European  legislation  protecting  water,  is  a  major  force  for 
farmers to reduce and control through nutritional management techniques the concentration of 
nutrients  in  animal  nutrition  and  excreta.  The  application  of  nutritional  measures  can  also  be 
driven by animal performance, and the competitiveness and financial viability of  the business. 
Indeed,  these  will  usually  be  the  major  driving  forces  for  the  implementation  of  techniques 
when  the  animal  population  is  within  the  carrying  capacity  of  the  land,  and  where  local  land 
banks have the capability to recover nutrients from produced manures and slurries.  

Market  prices  (for  grains  and  especially  for  soya)  can  produce  cost  savings  when  applying 
nutritional measures.  

Example plants 
Many  farms  located  in  Nitrate  Vulnerable  Zones  (according  to  the  Nitrates  Directive 
(91/676/EEC)),  such  as  those  in  Brittany  (France),  the  Netherlands,  Belgium  and  Germany, 
already  comply  with  some  nutritional  constraints  in  order  to  control  their  pollution  load  
[ 506, TWG ILF BREF 2001 ]. 

In  France,  since  the  publication  of  CORPEN  recommendations  for  pigs  in  1996,  two-phase 
feeding  with  low-protein  feeds  has  been  much  developed,  especially  for  sows.  By  the  end  of 
1997  nearly  one-third  of fattening  pigs  and  nearly  60 %  of  all  sows  were fed  this  way  [  704, 
FEFAC 2001 ]. 

In Germany, N-adapted feeding has been mandatory for intensive livestock farms since 2002. 

In Denmark, the implementation of the Danish BAT system in the framework of the ammonia 
emissions  legislation  set  a  requirement  starting  in  2011  that  the  feed  management  in  farms 
produce a reduction of ammonia emissions of 30 % compared to standard feeding for all new 
houses  and  25 %  compared  to  standard  feeding  for  housing  systems  with  partly  slatted  floors 
(25 % solid floor) [330, Denmark 2010 ]. 

Reference literature 
[ 30, Spain 2001 ] [ 281, France 2010 ] [ 323, Finland 2010 ] [ 324, Netherlands 2010 ] [ 328, 
CORPEN 2006 ] [ 329, CORPEN 2003 ] [ 330, Denmark 2010 ][ 396, LEI 1999 ] [ 414, Fefana 
2001 ] [ 448, Aarnink et al. 2007 ] [ 450, IFIP 2011 ] [ 506, TWG ILF BREF 2001 ] [ 624, IRPP 
TWG 2013 ] [ 625, BE Flanders 2013 ] [ 704, FEFAC 2001 ] 

224 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
4.3.2 

Multiphase feeding 

In multiphase feeding the nutrient content of the diet is adjusted to the different requirements, as 
well  as  to  the  different  feed  intake  of  the  animals  in  the  different  growth  phases.  This  is 
achieved by the provision of different rations or diets to livestock at different stages of growth 
or performance to match the ration closely to the changing requirements of the animals. 

Chapter 4 

4.3.2.1 

Poultry 

Description 
Different  feeding  strategies  have  been  developed  which  aim  at  meeting  the  right  balance 
between  energy  and  amino  acid  requirements  or  which  aim  to  influence  the  nutrient  uptake 
through an improved passage of the feed through the birds’ digestive channel.  

Multiphase feeding for layers is a method of feeding which involves adjustment of the levels of 
Ca and P in the different production stages. A uniform group of animals and a gradual transition 
from one feed to the next is required. 

Achieved environmental benefits 
The  primary  effect  of  multiphase  feeding  is  the  potential  for  reduction  in  the  excretion  of 
nutrients (notably, N and P). 

The  main  environmental  benefit  of  the  implementation  of  multiphase  feeding  in  poultry 
production is reported as a 4–10 % reduction in the amount of N excreted [ 281, France 2010 ] 
[ 414, Fefana 2001 ]. Values as high as 15–35 % are reported for the reduction of N excreted for 
broilers.  

Cross-media effects 
A lower nutrient content of the manure leads to lower nutrient emissions from  landspreading, 
but also to a higher use of mineral fertilisers, in the event that crop nutritional needs cannot be 
met by manure application alone. 

Environmental performance and operational data 
For broilers, multiphase feeding is applied in some EU countries. This involves dividing their 
requirements into three to five phases in which the broilers show a considerable change in their 
nutritional requirements. In each phase, the aim is to optimise the feed conversion ratio (FCR). 
Applying a slightly restricted feeding regime in the first phase results in more efficient growth 
at a later stage. Proteins and amino acids must be fed at a high level and in a balanced way. In 
phase 2 the digestive capacity of the bird will have improved, so it can be fed more feed with a 
higher energy content. In phase 3, the protein and amino acid content decreases resulting in the 
same or a reduced amount of energy. In all phases, the Ca-P balance remains the same, but the 
total concentration in the feed decreases [ 281, France 2010 ]. 

Compared  with  broilers,  turkeys  require  larger  amounts  of  feed.  Their  requirements  in  the 
different  phases  vary  in  the  same  way  as  those  of  broilers.  The  required  concentration  of 
proteins and amino acids decreases with increasing age, but the required feed energy increases. 
Depending on the type of turkey produced, the number of phases applied can vary, with four to 
five  being  normal  practice.  For  instance,  in  the  Netherlands,  five-phase  feeding  is  applied, 
which  means  five  different  feeds,  although  more  phases  can  be  distinguished  and  rations  are 
adapted accordingly. For turkeys, the shape in which the feed is offered influences the FCR and 
growth. Tests have shown that pellets show better FCR and growth than meal. 

Examples  of  diet  formulation  for  multiphase  feeding  regimes  (reduced  crude  protein  and 
supplement of amino acids) are reported in Table 4.8, together with the associated performance 
results, in terms of total nitrogen and ammonia in the excreta. Data refer to farms operated in 
Germany. 

Intensive Rearing of Poultry or Pigs 

225 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.8:  Examples of multiphase feeding regimes and associated emissions in the poultry sector 

Phases (1) 

Broilers 

Pullets 

Phase 1 weeks (days) 
Crude protein (%) 
Amino acids (%) 
Phase 2 weeks (days) 
Crude protein (%) 
Amino acids (%) 

Phase 3 weeks (days) 

Crude protein (%) 
Amino acids (%) 
Phase 4 weeks (days) 
Crude protein (%) 
Amino acids (%) 
Feed efficiency 
(kg feed/kg weight 
gain) 
Starting bird weight 
(kg) 
Final bird weight (kg) 
Number of animals 
per place and year 
Rearing time (days) 
Quantity of manure 
(kg/kg live weight) 
Dry matter content 
(%) 
N total  
(g/kg live weight) 
N total 
(kg animal place/year) 

NH4-N  
(g/kg live weight) 

3 

(1–10) 

22 
0.55 

(11–27/32) 

21 
0.55 
(28/33–
35/42) 
19.5 
0.50 
NA 
NA 
NA 

4 

1–3 

20.5 
0.48 

4–8 

18.5 
0.40 

9–15/16 

14.5 
0.33 
16/17 
17.5 
0.36 

Laying 
hens 
3 
NI 
18 
0.40 
NI 
17 
0.35 

NI 

16.5 
0.35 
NA 
NA 
NA 

Ducks 
(Pekin) 
2 
1–3 
22 
0.44 
4–7 
18 
0.43 

NA 

NA 
NA 
NA 
NA 
NA 

2.3  

Turkeys 
(male) 
4 
5–8 
24 
1.4 
9–12 
20 
1.25 

Turkeys 
(female) 
3 
5/6–8/9 
24.4 
1.45 

9/10–12/13 

20 
1.25 

13–16 

13/14–16/17 

18 
1 
> 17 
16 
0.85 

2.67 

18 
1.05 
NA 
NA 
NA 

2.58 

1.75  

(0.2) (2) 

2.05 (3) 

0.035–
0.045 
1.6–3.3 

0.04–0.05 

1.1–1.5 

0.053–0.06 

1.9–1.95 

1.52–1.59 

1.1–1.5 

1.7–2.2 

2.5–3.4 

19.45–21.4 

9.5–11.5 

6.5–8.1 

2.4–2.9 

NI 

6.6–7.4 

2–2.9 

2.2–2.9 

39–46 
0.6 (0.54–
0.65) 
60 (57–
62.3) 
18.2 (16–
19.6) 
0.207–0.42 
(6) 

12.8 (3.5–
14.8) 

119–140 

360–420 

45 (40–49) 

2.73  

1.4 (4) 

3.2 

52 (50–75) 

55.2 

40 (36–
45.7) (5) 
0.626–
0.794 (7) 

NI 

20.46 
(20.15-22) 
26.5 (25.8–
33.5) 
0.477–
0.752 (6) 
10.38 
(10.38–
11.48) 

66 (66–73)  

NI 

NI 

53.18 
(17.3–
53.18)  

133–154 
1.45 (1.23–
1.53) 
52 (41.7–
59.8) 
39 (28–
41.7) 
1.198–
2.352 (6) 

15.8 (11–
18.4) 

70–84 

1.21 

50 

39 (39–44) 

0.987–
1.212 (6) 

NI 

P2O5  
(g/kg live weight) 

3.79 (3.59–
4) 

20 (8.4–36) 
(5) 

13.7 (8.23–
13.9) 

30.6 (23–
38) 

7 (6.6–9.9) 

NI 

0.146–
0.626 (7) 

0.047–
0.086 (6) 

0.152–
0.312 (6) 

P2O5  
(kg animal place/year) 
(1) The exact feeding programme is presented in Section 9.2.2. 
(2) Value expressed in kg weight gain/kg feed. 
(3) Value expressed in kg weight gain/kg eggs. 
(4) Value expressed in kg manure/kg eggs. 
(5) Value expressed in g/kg eggs. 
(6) The range is calculated from the final animal weight, the number of cycles and the range of reported excretion.  
(7) The range is calculated from an annual production of 278 eggs and an average weight of 1 kg for 16 eggs.  
NB: NI = no information provided; NA = not applicable. 
Source: [327, Germany 2010 ]  

0.984–
2.143 (6) 

0.167–0.25 
(6) 

Technical considerations relevant to applicability 
Multiphase  feeding  is  considered  generally  applicable  in  the  poultry  sector.  The  number  of 
phases and the potential for reducing nitrogen excretion depend on the animal species and might 
need adaptation to local conditions [ 508, TFRN 2014 ]. 

226 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 4 

The availability of animal feedstuffs with a low protein content and synthetic amino acids may 
result  in  some  limitations  to  the  applicability  of  the  technique,  in  particular  in  terms  of 
achievable reduction levels. 

Economics 
When going from one-phase feeding to two-phase feeding, there may be an additional cost for 
supplemental storage. As the number of phases increases, the implementation of the technique 
might  require  high  additional  investment  for  storage,  mixing  and  supplying  devices,  metering 
equipment, conveying technology, etc., which might not be affordable for small farms. 

Driving force for implementation 
Optimisation of animal growth and of feedstuff costs. 

Example plants 
The use of multiphase feeding for the rearing of poultry is reported to be commonly applied in 
several Member States. 

Reference literature 
[ 281, France 2010 ] [ 327, Germany 2010 ] [ 414, Fefana 2001 ] [ 508, TFRN 2014 ] 

4.3.2.2 

Pigs 

Description 
Multiphase  feeding  for  pigs  consists  of  successively  giving  two to  five  feeds  to  pigs  with 
weights that are multiples of 25 kg, up to 100–110 kg (slaughter weight). Feeding programmes 
vary  among  countries.  The  two-phase  feeding  programme  (25–60 kg  and  60–110 kg)  is  well 
developed  but  could  be  further  developed  to  include  environmental  concerns,  as  well  as  to 
improve the economic value. Italian feeding programmes differ substantially from those of other 
EU countries because they work with much higher slaughter weights (140–150 kg). 

Multiphase feeding for pigs also consists of providing pigs with a compound feed that matches 
the  animal  requirements  for  amino  acids,  minerals  and  energy.  This  is  achieved  by  mixing  a 
high  nutrient  feed  with  a  low  nutrient  feed,  on  a  regular  basis  (from  daily  to  weekly),  as  the 
ideal  animal  nutritional  requirements  change  continuously  with  the  increase  in  live  weight. 
Multiphase  feeding  allows  the  nutrient  supply  to  be  adapted  more  closely  to  the  nutritional 
requirements of the animal. 

Achieved environmental benefits 
The  primary  effect  of  multiphase  feeding  is  the  potential  for  reduction  in  the  excretion  of 
nutrients (notably, N and P).  

The  main  achieved  environmental  benefit  of  the  implementation  of  multiphase  feeding  in  the 
production of pigs is reported as a 10–30 % reduction in the amount of N excreted, when used 
in combination with low-protein diets [ 281, France 2010 ] [ 414, Fefana 2001 ]. 

Cross-media effects 
A lower nutrient content of the manure leads to lower nutrient emissions from  landspreading, 
but also to a higher use of mineral fertilisers in the event that crop nutritional needs cannot be 
met by manure application alone. 

Environmental performance and operational data 
For  pigs,  a  different  diet  formulation  for  weaners  (< 30 kg  live  weight  (LW)),  growers  (from 
30 kg  to  60 kg  live  weight)  and  finishers  (from  60 kg  to  112 kg  live  weight)  is  generally 
applied.  In  some  cases,  a  different  diet  formulation  is  used  for  young  weaners  (first  stage 
between 8 kg and 12 kg) and for older weaners (second weaning stage > 12 kg). 

Intensive Rearing of Poultry or Pigs 

227 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

For sows, phase feeding consists of giving at least two different feeds: one for lactation and one 
for  gestation.  This  differentiation  is  well  developed  across  Europe.  In  some  cases,  a  specific 
feed  might  be  given  before  farrowing  [  506,  TWG  ILF  BREF  2001  ].  Examples  of  detailed 
multiphase  feeding  programmes  are  described  in  Annex  9.2.2.  A  summary  of  the  reduction 
potential for ammonia emissions associated with multiphase feeding in fattening pig production 
is shown in Table 4.9 for different feeding strategies and diet formulations. 

Table 4.9:  Reduction potential for ammonia emissions in fattening pig production with different 

crude protein adjusted feeding 

Feeding strategy 

Reduction potential (1) 
(%) 

Remarks 

Up to 10 

Multiphase feeding  
(2 phases) 

Multiphase feeding  
(3–4 phases) 

Adjustment between preliminary feeding and 
main feeding periods (from 18 % to 15 % crude 
protein) 
Adjustment every few weeks; from 18 % to 
13 % crude protein; balancing of essential 
amino acids (lysine, methionine)  
Multiphase feeding 
Daily adjustment; from 18 % to 13 % crude 
plus amino acid 
protein; balancing of essential amino acids 
balancing 
(lysine, methionine) 
(1) Reference feeding regime: No multiphase feeding, 18 % crude protein content.  
Source: [ 571, Eurich-Menden et al. 2011 ] 

Up to 40 

Up to 20 

Examples  of  excreted  nitrogen  reductions  associated  with  the  use  of  two-phase  feeding 
programmes  combined  with  low-protein  diets  applied  in  France  and  Germany  are  reported  in 
Table 4.10, together with an indication of the diet formulation applied. 

Table 4.10:  Examples  of  excreted  nitrogen  reductions  for  two-phase  feeding  programmes  in  the 

pig sector compared to the one-phase feeding 

Animal 

Source 

Diet/parameters 

Weaners 

Fattening pigs 

Sows  

France 
CORPEN 1 
France 
CORPEN 2 
France 
CORPEN 1 
France 
CORPEN 2 
Germany 
RAM 
France 
CORPEN 1 
France 
CORPEN 2 
Germany 
RAM 

Two phases: CP 20 % (1st phase);  
18 % (2nd phase)  
Two phases: CP 20 % (1st phase);  
17 % (2nd phase)  
Two phases: CP 16.5 % (growers);  
15 % (finishers)  
Two phases: CP 15.5 % (growers);  
13.0 % (finishers)  
Two phases: CP 17.0 % (< 60 kg of LW); 
14.0 % (> 60 kg of LW)  
Two phases: CP 16.5 % (lactation);  
14.0 % (gestation)  
Two phases: CP 16.0 % (lactation);  
12.0 % (gestation)  
Two phases: CP 16.5 % (lactation);  
14.0 % (gestation)  

Source: [ 414, Fefana 2001 ] [ 329, CORPEN 2003 ] 

Excreted 
nitrogen 
reduction (1) 
(%) 

9 

18 

17 

30 

19 

17 

27 

19–22 

A  three-phase  feeding  programme  for  growers/finishers  can  reduce  N  excretion  by  16 % 
compared to a one-phase feeding programme [ 448, Aarnink et al. 2007 ].  

228 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Trials  with  five-phase  low-CP/DE  (crude  protein/digestible  energy)  diets  for  fattening  pigs 
(growers/finishers)  were  carried  out  in  the  UK,  which  consistently  showed  that  total  nitrogen 
and  ammonium-N  in  slurry  from  pigs  were  reduced  compared  to  levels  resulting  from  the 
commercial two-phase feeding strategy [ 539, MAFF 1999 ] [ 540, MAFF 1999 ]. A reduction 
of  up  5 %  for  NH3  emissions  and  up  to  10 %  for  soluble  P  emissions  is  recognised  as  the 
effectiveness of this technique in the UK [ 648, DEFRA 2011 ]. 

However,  in  a  field  study  carried  out  in  the  UK,  an  overall  evaluation  of  daily  adjusted 
multiphase feeding for fattening pigs reared  on fully slatted floors or in  a straw-based system 
was performed in comparison with a one-phase diet. The multiphase diet was formulated so that 
the total lysine to digestible energy ratio was adjusted to meet pigs' requirements according to 
their actual live weight, while the one-phase feeding was fixed at the target requirement of 70 
kg live weight (18.5 % CP). No significant effects were found on dust and ammonia emissions, 
slurry generation and composition with this diet formulation [ 654, BPEX 2004 ].  

An example of the performance variation observed by applying a two-phase feeding regime and 
a  five-phase  feeding  regime  for  fattening  pigs  is  presented  in  Table 4.11.  The  detailed 
composition of the different diets used for both feeding strategies is reported in Annex 9.2.2. 

Table 4.11:  Example of the influence of multiphase feeding on excreted nitrogen and phosphorus 

for fattening pigs 

Operating and performance data 

Feeding strategy (1) 

2 phases  

Phases 

Phase 1: 25–60 kg 
Phase 2: 60–110 kg 

5 phases 
Phase 1: 30–40 kg 
Phase 2: 40–60 kg 
Phase 3: 60–80 kg 
Phase 4: 80–100 kg 
Phase 5: 100–110 kg 

7.8 

4.8 

4.9 

7.35 

 5.2 

Excretion parameters 
Total nitrogen (2)  
(kg/animal place/year) 
Nitrogen excreted  
(kg N/m3 manure)  
Total P2O5  
(kg/animal place/year) 
P2O5 excreted 
(kg/m3 manure) 
Quantity of manure (m3/ap/yr) 
Animal performance 
Feed consumption (kg/d) 
Average daily gain (g/d) 
Feed efficiency (kg weight gain/kg feed) 
Rearing time (d) 
Number of animals per place and year 
(1) The exact feeding programmes are presented in Section  9.2.2. Amino acid supplementation and benzoic acid 

2.15 (2.1–2.3) 
720 (650–850) 
0.34 (0.31–0.37) 
125 (110–140) 
2.8 (2.5–3) 

1.5, with 7.5 % dry matter 

 3.0 

 3.2 

4.5 

addition. Phytase and inorganic P addition. 

(2) Housing and stock losses deducted. 
Source: [326, Germany 2010 ] 

Excretion amounts associated with the application of phase feeding and a low-crude protein diet 
with  amino  acid  supplementation  for  weaners,  gestating  and  farrowing  sows  are  presented  in 
Table 4.12.  

Intensive Rearing of Poultry or Pigs 

229 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.12:  Example of the influence of multiphase feeding with amino acid and phytase addition 

on excreted nitrogen and phosphorus for sows and weaners 

Operating and performance data 

Animal category 

Sows 

Feeding strategy 
(1) 

Phases 

Total nitrogen (2) 
(kg/animal 
place/year) 
Nitrogen excreted 
(kg/m3 manure) 
Total P2O5 
(kg/animal 
place/year) 
P2O5 excreted 
(kg/m3 manure) 
Quantity of 
manure 
(m3/animal 
place/year) 

Gestating sows: phase 
feeding with amino acid 
supplementation. 
Phytase and inorganic P 
addition  

Lactating sows: one-
phase feeding with amino 
acid supplementation. 
Phytase and inorganic P 
addition 

Weaners 
Phase feeding with 
amino supplementation, 
benzoic acid and NSP 
enzymes addition. 
Phytase and inorganic P 
addition 

Phase 1: day 1 to day 84 
Phase 2: day 85 to day 
115 and for non-pregnant 
sows 

Phase 1:  25 days (21–
28) 

Phase 1: 8–20 kg 
Phase 2: 20–30 kg 

Excretion parameters 

18 (17.2–18.4) (3) 

1.5 (1.4–1.6) 

 4.5 (4.3–4.6) (3) 

 2.5 (2.3–2.7) 

12.4 (11.2–13.6) 

 3.1 (2.8–3.4) 

2.2 

 3.7 

4 (3.6–7.7) with 4 % DM 

0.6 (0.5–1.1) 

Animal performance 

0.8 (0.65–0.9) 

- 

- 

6.5 (3.5–7) 

2.8 (2.5–3.1) 

Feed consumption 
(kg/d) 
Average daily 
gain (g/d) 
Feed efficiency 
(kg weight 
gain/kg feed) 
Rearing time (d) 
Number of litters 
or animals per 
place and year 
(1) The exact feeding programmes are presented in Section 9.2.2. 
(2) Housing and stock losses deducted. 
(3) Value refers to sows (with 22 reared piglets of 8 kg each) without differentiation between various stages 

0.25 (0.23–0.28) 

0.25 (0.23–0.28) 

25 (21–25) 

47 (41–48) 

6.7 (5–7) 

115 

2.3 

2.3 

0.6 (0.5–0.65) 

500 (450–550) 

(lactating, gestating or non-pregnant). 

Source: [326, Germany 2010 ] 

The  feeding  strategies  with  a  reduced  phosphorus  content  adopted  in  France  are  reported  in 
Annex 9.2.2.5. Compared to the one-phase feeding strategy, the two-phase feeding strategy with 
a  limited  P  content  reduces  P  intake  and  P  excretion  by  19 %  and  28 %,  respectively,  per 
slaughter pig (0–115 kg) [ 590, Batfarm 2013 ]. 

Technical considerations relevant to applicability 
Multiphase  feeding  is  considered  generally  applicable  in  the  pig  sector.  In  large  groups  of 
fattening  pigs,  a  five-phase  feeding  programme  (or  more)  may  not  be  applicable  due  to  the 
variability in the weights of individual pigs within a pen group, which may overlap target start 
and end weights [ 624, IRPP TWG 2013 ].  

230 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

Economics 
When going from one-phase feeding to two-phase feeding, there may be an additional cost for 
supplemental storage. As the number of phases increases, the implementation of the technique 
might  require  high  additional  investment  for  storage,  mixing  and  supplying  devices,  metering 
equipment, conveying technology, etc., which might not be affordable for small farms. Hence in 
Denmark,  the  technique  is  not  considered  applicable  to  farms  with  less  than  approximately 
1 300 animal places [ 330, Denmark 2010].  

Cost  data  from  Spain  [  379,  Spain  2009  ]  report  an  additional  cost  of  EUR 0.7–1.02/animal 
place/year or  EUR 2.4–4.0/t produced when two-phase feeding is applied in the production of 
fattening pigs (one phase for the range 20–60 kg and another for finishers of 60–100 kg). 

In another study in the UK, multiphase feeding with a daily adjustment of feed did not deliver a 
cost  benefit  over  a  single  feeding  phase;  total  finishing  costs  (EUR/kg  of  deadweight)  were 
around  2 %  higher  with  the  multiphase  system  (taking  into  account  all  variable  and  fixed 
production costs) [ 654, BPEX 2004 ].  

Driving force for implementation 
Multiphase feeding offers a cost-effective means of reducing nutrient excretion from pigs and 
could be implemented in the short term [ 508, TFRN 2014 ]. 

Example plants 
Multiphase feeding is a consolidated technique commonly applied across the European Union.  

Reference literature 
[  281,  France  2010  ]  [  326,  Germany  2010  ]  [  329,  CORPEN  2003  ]  [  330,  Denmark  2010  ] 
[ 379, Spain 2009 ] [ 414, Fefana 2001 ] [ 448, Aarnink et al. 2007 ] [ 506, TWG ILF BREF 
2001 ] [ 508, TFRN 2014 ] [ 539, MAFF 1999 ] [ 540, MAFF 1999 ] [ 571, Eurich-Menden et 
al. 2011 ][ 590, Batfarm 2013 ] [ 624, IRPP TWG 2013 ] [ 648, DEFRA 2011 ] [ 654, BPEX 
2004 ]  

4.3.3 

Low-protein, amino-acid-supplemented diets  

Description 
The  crude  protein  content  of  the  diet  can  be  reduced  if  the  amino  acid  supply  is  optimised 
through the addition of synthetic amino acids to meet animal requirements. The low-protein diet 
is formulated with less protein-rich feedstuff, e.g. soybean meal for pigs. Appropriate amounts 
of  essential  amino  acids  needed  for  optimal  performance  are  incorporated  into  the  diet.  The 
amino acid supplementation can be done through a one-phase or a multiphase feeding regime. 
As a result, the ingestion of excess protein is decreased and, consequently, the excreted nitrogen 
is reduced (Figure 4.2).  

The dietary crude protein content can be lowered if at the same time the energy content of the 
diet is controlled and the level of nutritional amino acids is  balanced by synthetic amino  acid 
supplementation  in  appropriate  quantities  and  proportions  and  by  cereals.  Amino  acids  like 
lysine  (L-lysine),  methionine  (DL-methionine  and  analogues),  threonine  (L-threonine), 
tryptophan  (L-tryptophan)  and  valine  (L-valine)  are  registered  as  feed  additives  and  are 
commercially available.  

Intensive Rearing of Poultry or Pigs 

231 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

NB:  

lys = Lysine  
trp = Tryptophan   val = Valine  

m+c = Methyonine+Cysteine  
leu = Leucine 

thr = Threonine  
iso = Isoleucine  

Source: [ 396, LEI 1999 ] 

Figure 4.2:  Example  of  reduced  protein  intake  by  animals  achieved  by  synthetic  amino  acid 
supplementation  to  a  low-protein  diet,  while  maintaining  an  adequate  amino  acid 
supply 

Achieved environmental benefits 
The reduction of dietary protein ingested (input) leads to a significant reduction of the nitrogen 
excreted (output), hence emissions can be reduced at all stages of the manure management. For 
each per cent (absolute value) decrease in the protein content of the animal feed, NH3 emissions 
from  animal  housing,  manure  storage  and  landspreading  are  decreased  by  5 %  to  15 %, 
depending  also  on  the  pH  of  the  urine  and  dung.  Low-protein  animal  feeding  also  decreases 
N2O emissions, and increases the efficiency of N use in animal production [ 508, TFRN 2014 ]. 
A  summary  of  benefits  associated  with  the  use  of  a  low-protein  diet  achieved  by  synthetic 
amino acid supplementation are listed below. 

Poultry 
 

A  reduction  in  dietary  protein  content  of  1  percentage  point  results  in  a  reduction  in 
nitrogen excretion of 10 % for poultry [ 414, Fefana 2001 ].  

 

 

 

 

Low-protein diets contribute to a reduction of ammonia emission from poultry houses. In 
an  experiment  on  growing  broilers,  a  reduction  in  crude  protein  of  2  percentage  points 
resulted in a reduction in ammonia emission of 24 %. 

A  reduction  in  water  consumption  of  8 %  is  possible  when  the  protein  level  in  grower 
feed is decreased by 3 percentage points [ 414, Fefana 2001 ]. 

According to the Dutch model designed for the European Commission, for a reduction of 
10 %  of  the  protein  content  in  feed,  reductions  of  the  nitrogen  content  in  manure  are 
expected  for  laying  hens,  ducks,  turkeys  and  broilers  of  14 %,  15 %,  15 %  and  19 %, 
respectively [ 281, France 2010 ].  

The litter quality is enhanced by a reduced nitrogen content, which results in reductions 
of  the  incidence  of  skin  conditions,  such  as  hock  burn,  sternal  bursitis,  focal  ulcerative 
dermatitis and foot pad dermatitis (also important for improving working conditions for 
farm personnel). 

232 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

Pigs 
 

 

 

 

For every 10 g/kg reduction in the CP content of the diet, a 10 % lower TAN content of 
the pig slurry and 10 % lower NH3 emissions can be achieved in growing/finishing pigs 
relative to a baseline value with a protein content of 170 g/kg [ 508, TFRN 2014 ]. 

It is possible to reduce the nitrogen excretion by up to 20 %, by reducing by up to 2 % the 
initial protein level in feeds for all categories of pigs and without requiring any specific 
technical skills [ 34, Ajinomoto 2000 ]. However, it is necessary to add the four essential 
amino  acids  (lysine,  methionine,  threonine  and  tryptophan)  and  to  formulate  diets 
respecting  net  energy  requirements  to  prevent  a  deterioration  in  growth  and  carcass 
quality. 

Protein  content  is  gradually  reduced  according  to  the  need  for  amino  acids  and,  in  this 
way,  a  high  surplus  of  nitrogen  is  avoided.  The  lower  excretion  of  nitrogen  through 
kidneys  and  faeces  reduces  the  intestinal  problems  and  physiological  'stress'  of  the 
excretion process [ 330, Denmark 2010 ]. 

In  general,  reduced  crude protein  levels  have  a tendency  to  lower  odour emissions (see 
Section  4.10)  and  the  emission  of  odorous  components  like  H2S  [  414,  Fefana  2001  ]. 
This effect is reported as non-existent when a relatively low-protein diet is already used  
[ 330, Denmark 2010 ] [326, Germany 2010 ]. A reduction in water consumption of about 
6–9 % was reported when the protein level in the diet for fattening pigs was decreased by 
3  percentage  points  (from  17.5 %  to  14.5 %  CP)  [  414,  Fefana  2001  ].  The  saving  of 
water results in a decreased volume of manure to be handled. With higher DM contents, 
the slurry may also gain in value in terms of its fertilising quality.  

Cross-media effects 
There are no animal health or animal welfare implications of a reduction of protein level as long 
as the requirements for all essential amino acids are met. 

Environmental performance and operational data 
A  crude  protein  reduction  of  2–3 %  in  the  feed  (20–30  g/kg  of  feed)  can  be  achieved  with 
adequately balanced and optimal digestible amino acid supply depending on the pig production 
category and its starting point. For poultry, a crude protein reduction of 1–2 % (10–20 g/kg of 
their  starting  point 
feed)  can  usually  be  achieved  depending  on 
[ 508, TFRN 2014 ]. The resulting range of dietary crude protein content is reported Table 4.13 
and in Table 4.14.  

the  species  and 

Table 4.13:  Indicative crude protein levels in low-protein feeds for pigs 

Animal type 

Weaner 

Fattening pig 

Sow 

Phases 
< 10 kg 
< 25 kg 
25–50 kg 
50–110 kg 
Gestation 
Lactation 

Crude protein content (% in feed) 
19–21 
17–19 
15–17 
14–15 
13–15 
16–17 

Source: [ 43, COM 2003 ] 

Remark 

With adequately balanced 
and 
amino acid supply  

optimal 

digestible 

Intensive Rearing of Poultry or Pigs 

233 

 
 
 
 
 
 
 
Chapter 4 

Table 4.14:  Indicative crude protein levels in low-protein feeds for poultry 

Animal type 

Broiler 

Turkey 

Layer 

Phases 
Starter 
Grower 
Finisher 
< 4 weeks 
5–8 weeks 
9–12 weeks 
13+ weeks 
16+ weeks 
18–40 weeks 
40+ weeks 

Crude protein content (% in feed) 
20–22 
19–21 
18–20 
24–27 
22–24 
19–21 
16–19 
14–17 
15.5–16.5 
14.5–15.5 

Source: [ 43, COM 2003 ] 

Remark 

adequately 
With 
balanced  and  optimal 
digestible  amino  acid 
supply 

The values of the ranges of the best feed management practices are indicative target levels and 
may need to be adapted to local conditions. The achievable levels depend on the management 
skills  of  the  farmer  and  the  availability  of  the  animal  feedstuffs  with  a  low  protein  content, 
including  synthetic  amino  acids  [  508,  TFRN  2014  ].  A  series  of  examples  is  reported  in 
Table 4.15, showing the environmental and economic effects of the reduction in the amounts of 
crude  protein  (CP)  for  pigs  and  poultry,  together  with  the  corresponding  amino  acid 
supplementation. 

234 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Table 4.15:  Environmental  and  economic  benefits  of  formulating  a  low-crude-protein  diet  with 

synthetic amino acid supplementation 

Feed components 

Source 

Laying 
hens (1) 
[ 316, Fefana 
2010 ] 

Broilers  

[ 312, Fefana 
2010 ] 

Animal category 
Male 
turkeys (2) 
[ 313, Fefana 
2010 ] 

Fattening 
pigs  
[ 314, Fefana 
2010 ] 

Fattening pigs  

[ 315, Fefana 
2010 ] 

Chapter 4 

19 

Phase 1 
Initial CP level (%) 
Initial amino acid 
supplementation (%) 
Reduction of CP level (%) 
Final CP level in diet (%)  
Additional amino acid 
supplementation (%) 
Total amino acid supplementation in the reduced CP diet (% of diet) 

-2.9 
16.1 

-2 
20 

+0.25 

+0.38 

0.35 

0.21 

22 

27.7 

0.32 

-1.9 
25.8 

+0.32 

17.5 

0.202 

-3 
14.5 

17.5 

0.066 

-1.5 
16 

+0.426 

+0.242 

L-Lysine HCl (%) 
DL-Methionine (%) 
L-Threonine (%) 
L-Tryptophan (%) 

0.24 
0.28 
0.07 
NA 

0.20 
0.31 
0.07 
0.02 

0.29 
0.27 
0.08 
NA 

0.49 
NA 
0.124 
0.014 

NA 

20.6 

Phase 2 
Initial CP level (%) 
Initial amino acid 
supplementation (%) 
Reduction of CP level (%) 
Final CP level in diet (%)  
Additional amino acid 
supplementation (%) 
Total amino acid supplementation in the reduced CP diet (% of diet) 

-2.4 
18.2 

NA 
NA 

+0.19 

0.22 

NA 

NA 

23.3 

0.37 

-1.7 
21.6 

+0.31 

L-Lysine HCl (%) 
DL-Methionine (%) 
L-Threonine (%) 
L-Tryptophan (%) 

NA 
NA 
NA 
NA 

0.17 
0.24 
0.07 
0.01 

0.38 
0.22 
0.08 
NA 

NA 

NA 

NA 
NA 

NA 

NA 
NA 
NA 
NA 

NI 

23  

29.2 

22.9 

19.9 

2.511 

0.352 

Overall results 
Reduction of total N in the 
excreta (%) 
Total N in the excreta 
(kg/animal place/year) (3) 
Total N excreted (kg/animal 
place/year)  
Annual savings per animal 
place (EUR) 
Annual savings per production 
(EUR/kg (4) or EUR/egg) 
(1) Four phases. Diet presented under 'Phase 1' represents all phases (18 to 80 weeks). 
(2) Two more phases of the test have not been displayed. 
(3) Obtained by multiplying g N/kg live weight by number of cycles per year and final weight. 
(4) Price calculations are based on amino acid and feed raw materials prices of December 2009.  
NB: NA = not applicable; NI = no information provided. 

(0.0164) 

0.116 

0.018 

0.601 

0.025 

7.09 

0.32 

0.41 

 NI 

NI 

8.006 

5.05  

0.0391 

0.156 
0.088 
0.064 
NA 

15.5 

0.116 

-2.0 
13.5 

+0.325 

0.255 
0.090 
0.096 
NA 

16.2 

6.22 

NI 

5.21 

0.0307 

The effects of two different low-protein diets for fattening pigs (finishers), with partial or total 
substitution of soybeans by synthetic amino acids, have been tested during two field trials; the 
results are presented in Table 4.16. 

Intensive Rearing of Poultry or Pigs 

235 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.16:  Effects  of  two  low-protein  diets  with  partial  or  total  substitution  of  soybeans  by 

essential amino acids on fattening pigs (finishers) 

Parameters 

Diet description and performance data 

Diet 

Time of application 
Animal weight 
Crude protein (%) 
Average reduction in nitrogen, compared to 
standard diet (1) (%) 
Average reduction of 
ammonia emissions to air, 
compared to standard diet 
(1) (%) 
Average reduction of nitrogen to field, after air 
losses, compared to standard diet (1) (%) 
(1) Standard diet with 13–14 % CP. 
Source: [ 325, CRPA 2009 ]  

Estimated 
(Nitrogen balance) 

Measured 

Low-protein diet – 1  
Soybeans are reduced 
and partially substituted 
by synthetic amino acids 
Summer 
98.6–163.8 kg 
11–12 

Low-protein diet – 2 
Without soybeans which 
are fully substituted by 
synthetic amino acids 
Winter 
102.8–160.2 kg 
9 

21.9 

26.2 

26.2 

18 

37.9 

50.3 

54.6 

30 

In a literature review reported by Ajinomoto Animal Nutrition, data from reported trials on the 
effects of low-protein diets (and supplemented with synthetic amino acids) on the nitrogen and 
slurry output from pigs were selected from a large variety of sources within and outside Europe. 
The  conclusion  that  could  be  reached  was  that  the  excretion  of  nitrogen  drops  by  10 %  per 
percentage point reduction in dietary protein for pigs between 25 kg and 110 kg, with a linear 
trend in the range of a 12 % to 20 % CP level [ 34, Ajinomoto 2000 ]. Table 4.17 summarises 
the effects of a reduction in dietary crude protein levels and the use of low-protein diets. 

Table 4.17:  Summary  of  the  effect  of  a  reduction  of  dietary  protein  and  the  use  of  low-protein 

diets on nitrogen excretion and ammonia emission  

Parameters 

Total nitrogen excreted 
Ammonia content in slurry 
Slurry pH 
Ammonia emission to air 
Water consumption  
(ad libitum) 
Slurry volume 
Source: [ 34, Ajinomoto 2000 ] 

Effect of 1 
percentage point 
reduction of 
dietary protein 
(%) 
-10 
-10 
- 
-10 

-2 to -3 

-3 to -5 

Using low-protein diets 

Frequent 
cumulative effect 
(%) 

Best cumulative 
effect 
(%) 

-25 
-30 
-0.5 points 
-40 

-10 

-20 

-50 
-50 
-1 point 
-60 

-28 

-30 

Results  of  a  trial  carried  out  in  a  fattening  pigs  farm  (30–115 kg  in  a  straw  housing  system), 
applying  a  one-phase  feeding  strategy  in  which  the  applied  dietary  CP  level  of  17.5  %  was 
reduced  by  3  percentage  points  with  the  addition  of  supplementary  synthetic  amino  acids 
(lysine, threonine and tryptophan) are presented in Table 4.18. The experiment results are in line 
with those reported in Table 4.19. 

236 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

Table 4.18:  Effects of reduced crude protein levels with amino acid supplementation in one-phase 

feeding of fattening pigs  

Parameters 

Crude protein in diet (%) 
Amino acids in diet (%) 
Total Nitrogen excreted (g/kg live weight) 
NH3 + N2O (N gaseous emissions) reduction (%) 
Savings in feed cost (1) 

EUR/animal place/year 
EUR/kg produced/year 

Standard 
one-phase feeding 
17.5 
0.2019 
15.37 
NA 

Modified 
one-phase feeding 
14.5 
0.6274 
10.88 
30 

NA 
NA 

8.006 
0.0391 

(1) Cost calculations based on amino acids and feed raw materials prices of December 2009. 
NB: NA = not applicable. 

Source: [ 572, Fefana 2010 ] 

The conversion from a one-phase to a two-phase feeding system, with the aim of adapting the 
feed to the pig's physiological stage and, at the same time, reducing the excreted nitrogen, may 
better  fulfil  the  animal's  requirements  during  growth.  In  an  already  applied  phase  feeding 
strategy, based on the needs of the animal at various life stages, the protein intake can be further 
reduced by adding synthetic amino acids to the feed.  

The substitution of a one-phase feeding scheme with 17.5 % CP with a two-phase scheme where 
the CP level is reduced by 1 percentage point in the first phase and by 2 percentage points in the 
second  phase, while integrating the two  diets with proper doses of amino acids (for a total  of 
0.4 %),  provides  a  reduction  in  nitrogen  excretion  of  18.5 %  (see  Table 4.19)  [  317,  Fefana 
2010 ]  [  318,  Fefana  2010  ].  The  introduction  of  a  second  phase  with  a  2  percentage  point 
reduction  of  the  dietary  crude  protein  level  leads  to  a  reduction  of  the  nitrogen  excreted  of 
around 8 % [ 319, Fefana 2010 ]. The substitution of expensive protein meals with small doses 
of synthetic amino acids still allows for reductions in the cost of feed preparation, as shown in 
Table 4.19  for  two  different  formulations  of  two-phase  feeding  in  comparison  with  the  single 
phase previously applied. 

Table 4.19:  Examples  of  emissions  and  costs  reductions  for  two-phase  feeding  schemes  after 

transition from a one-phase feeding scheme for fattening pigs  

Feeding scheme 

CP (%) 

Phase 1 
(growing 
period) 

Phase 2 
(finishing 
period) 

Reduction 
of total 
excreted N 
(%) 

Feed cost 
reduction 
(1) 
(%) 

Feed cost savings 
EUR/kg 
of 
produced 
meat 

EUR/ap 
per year 

17.5 

15.5 

17.5 

Standard one -phase 
feed 
Switch from single 
phase to two-phase 
feeding – Reduction 
of CP level in the 
finishing period 
Switch from one-
phase to two-phase 
feeding – Reduction 
of CP level in both 
growing and finishing 
periods 
(1) Feed costs calculated based on December 2009 prices. 
NB: NA = not applicable.  

15.0 

16.5 

NA 

NA 

NA 

NA 

7.8 % 

5.76 % 

5.675 

0.0334 

18.5 % 

5.47 % 

5.25 

0.0256 

Source: [ 317, Fefana 2010 ] [ 318, Fefana 2010 ] [ 319, Fefana 2010 ] 

Intensive Rearing of Poultry or Pigs 

237 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

In Spain, a trial was carried out in fattening pigs by applying a low-protein diet. In Phase 1, a 
crude  protein  level  of  14.6 %  (1.04 %  lysine)  is  applied  and  in  Phase  2  of  13.6 %  (0.91 % 
lysine).  A  60 %  reduction  of  ammonia  emissions  is  reported  to  be  achieved  for  this  diet 
formulation  [  335,  Spain  2010  ].  In  general,  a  30–40 %  reduction  of  ammonia  emissions  is 
possible when a diet low in protein content and with amino acid supplementation is applied in 
the rearing of fattening pigs [ 379, Spain 2009 ].  

A further step in the feeding strategy might be the transition from a two-phase feeding system to 
a  three-phase  feeding  strategy.  Results  that  were  obtained  in  commercial  farms  in  Belgium, 
concerning three different situations corresponding to a minimal, medium and strong reduction 
of CP in the diet, and related compensation by amino acids supplementation, are summarised in 
Table 4.20 (note that negative savings are, in effect, increased costs). 

Table 4.20:  Effectiveness of transition from two-phase feeding to three-phase feeding for fattening 

pigs and different crude protein reductions 

Parameters 

Two-phase feeding 

Minimal  

Crude protein reduction 
Medium  

High  

Phase 1 
(30–45 kg) 

Phase 2 
(45–110 kg) 

Crude protein content (%) 
Supplemented amino 
acids (%) 
Crude protein content (%) 
Supplemented amino 
acids (%) 

N excretion (kg/animal place/year) 
Three-phase feeding  

17.5 
0.43 
(Lys, Thr, Met) 
15.5 
0.38 
(Lys, Thr, Met) 
10.834 

17.5 
0.43 
(Lys, Thr, Met) 
15.5 
0.38 
(Lys, Thr, Met) 
10.834 

Phase 1 
(30–45 kg) 

Phase 2 
(45–75 kg) 

Phase 3 
(75–110 kg) 

Crude protein content (%) 

17.5  

Supplemented amino 
acids (%) 

0.43 
(Lys, Thr, Met) 

Crude protein content (%) 

16.5 

16.5  
0.61 
(Lys, Thr, Met,  
Trp)  
15.5 

Supplemented amino 
acids (%) 

0.36 
(Lys, Thr, Met) 

0.52 
(Lys, Thr, Met) 

Crude protein content (%) 

14 

13 

Supplemented amino 
acids (%) 

0.48 
(Lys, Thr, Met) 

0.60 
(Lys, Thr, Met) 

607 
215.25 

Growth (g/day) 
Weight gain (kg/animal place/year)  
Nitrogen excretion performance 
N excretion (kg/animal place/year) 
Reduction of excreted nitrogen (%) 
Economics (1) 
2.33 
Savings/animal place/year (EUR) 
2.24  
Savings/animal place/ year (%) 
-0.002 
Savings/kg of produced meat/year (EUR) 
Savings/kg of produced meat/year (%) 
-0.42 
(1) Feed cost savings calculated based on October 2009 prices. 
NB:  Lys = Lysine; Met = Methionine; Thr = Threonine; Trp = Tryptophan. 

9.89 
8.7  

629 
222.77 

9.49 
12.4  

7.15 
6.87  
0.037 
7.85 

17.5 
0.43 
(Lys, Thr, Met) 
15.5 
0.38 
(Lys, Thr, Met) 
10.834 

15.5 
0.79 
(Lys, Thr, Trp, 
Met) 
14.5 
0.69 
(Lys, Thr, Met, 
Trp) 
12 
0.73 
(Lys, Thr, Met, 
Trp) 
631 
224.81 

8.55 
21.1  

7.57 
7.27  
0.042 
8.92 

Source: [ 320, Fefana 2010 ] [ 321, Fefana 2010 ] [ 322, Fefana 2010 ]. 

From Denmark, a reduction of ammonia emission of 6 % to 22 % for fattening pigs is reported 
compared to a standard diet with a crude protein content of 157 g per feed unit (1 Danish feed 
unit for pigs = 7 380 kJ) which is equivalent to 150 g per kg of feed (the average Danish diet for 
fattening  pigs  has  an  energy  content  of  around  1.05  Danish  feed  units  per  kg  of  feed).  In 
particular, three levels of crude protein in the diet for fattening pigs (161 g, 154 g and 148.5 g 

238 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
per Danish feed unit corresponding to approximately 153 g, 147 g and 141.5 g per kg of feed) 
are applied  with  phase feeding  and  use  of  synthetic amino  acids  [  330,  Denmark  2010  ]. The 
effect of applying low crude protein levels on slurry characteristics and N emissions is presented 
in Table 4.21. 

Chapter 4 

Table 4.21:  Effect  of  the  protein  content  of  fattening  pigs'  feed  on  slurry  characteristics  and 

nitrogen emissions 

Dietary CP content 
Slurry composition 
Amount  
Dry matter 
Total N  
Total N-NH4  
pH 
N balance 
N retention  
N excretion 
NH3 emissions 

% 

kg/pig/d 
% 
g N/kg 
g N/kg 
- 

g/pig/d 
g/pig/d 
g/pig/d 

20 

5.7 
4.4 
5.48 
4.32 
8.92 

23.2 
40.7 
17.4 

16 

5.1 
4.6 
4.3 
3.13 
8.61 

23.5 
27.6 
13.8 

12 

3.6 
5.9 
3.05 
1.92 
7.57 

21.9 
15.0 
6.4 

Source: [ 451, Portejoie et al. 2002 ] [ 590, Batfarm 2013 ] 

Technical considerations relevant to applicability 
This technique is already implemented throughout  Europe. No specific technical requirements 
are necessary for the application of low-protein feed diets. However, the applied levels of crude 
protein might differ from country to country. 

The  feeding  of  low-protein  diets  can  reduce  the  animals’  heat  production  caused  by  various 
physiological  processes.  This  is  considered  to  be  an  advantage,  particularly  in  Mediterranean 
Member States during hot summers. This effect is even more pronounced with lactating sows. 
In general, pigs are not sensitive to dietary CP levels as long as they receive the essential amino 
acids in quantities and proportions appropriate to meet their requirements. 

In trials by Portejoie et al. [ 451, Portejoie et al. 2002 ] dietary protein was strongly decreased 
from 20 % to 12 %, ammonia emissions reductions of up to 63 % were observed over the whole 
process  and  the  effect  on  pig  performance  and  carcass  quality  was  negative  [  281,  France 
2010 ]. On the other hand, it might be argued that there is no biological limit to reducing the CP 
content as long as the amino acid profile is balanced and the net energy content of the pigs' diet 
is  adapted.  The  reason  for  the  aforementioned  performance  deterioration  should  be  the 
deficiency of the amino acid valine, which was not supplemented and was found in the diet to 
be in a very low ratio to the amino acid lysine. Recalculation of the amino acid profile based on 
the INRA tables (2004) showed that the valine to lysine ratio in the 12 % CP diet was too low 
(58 %) compared to the recommended ratio of at least 65 %. 

Commercial  broiler  lines  can  become  quite  sensitive  to  reductions  in  protein  levels.  In  many 
commercial diets that are already well optimised with regards to protein content, further crude 
protein reductions  could  compromise  certain amino  acid levels,  which  are  difficult  to balance 
with synthetic amino acids that are not available at commercial prices. The resulting amino acid 
deficiency  would  have  a  negative  effect  on  the  animal  growth  rates.  It  has  been  reported  that 
any  further  crude  protein  reductions  in  UK  diets  are  most  likely  to  compromise  valine  levels 
and, therefore, affect animal growth. 

For  UK  conditions,  poultry  nutritionists  advise  that  for  laying  hens  aged  18  to  40  weeks, 
tryptophan,  which  is  not  added  in  the  feed,  is  also  a  limiting  amino  acid.  Therefore  a  crude 
protein  level  of  15.5–16.5 %  is  not  technically  achievable  and  under  UK  conditions  a  higher 
crude protein level will be needed for this class of poultry. This nutrient management approach 
can be implemented very readily on a large scale since: 

Intensive Rearing of Poultry or Pigs 

239 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

 

 

little investment is needed and no structural alterations are required on the farm; and  

one  feed  mill  generally  covers  a  large  number  of  farms,  therefore  reducing  individual 
farm formulation costs.  

The optimum crude protein level will depend on local raw materials and will vary from region 
to  region,  e.g.  where  higher  protein  cereals  are  predominant  higher  protein  levels  will  result 
from feed  optimisation.  The  substitution  with  amino  acids  is  possible  only  if  cereals  are  also 
available [ 624, IRPP TWG 2013 ]. 

Economics  
A general description on cost assessment of nutritional management is given in  Section 4.3.1. 
For feeding  low-protein diets,  no special equipment has to be applied  and  no  new  investment 
needs to be made.  Changing from conventional diets to low-protein diets may lead to a slight 
increase in feed costs, particularly when protein-rich feedstuffs are inexpensive. The economic 
benefit  will  obviously  change  depending  on  the  relative  cost  of  ingredients;  in  general,  when 
protein-rich  feedstuffs  have  high  prices,  as  in  the  past  few  years,  a  decrease  in  feed  costs  is 
expected. 

Prices of feed materials such as soybean meal and other protein-rich feedstuffs and cereals, as 
well  as  of  synthetic  amino  acids,  are  subject  to  fluctuations  that  define  the  final  feed  costs. 
When lowering the dietary CP level, there may be an additional cost but there may be a gain as 
well  depending  on  the  initial  feed  composition,  the  target  for  lowering  the  NH3  volatilisation 
potential and the market prices of the feed ingredients (cereals, soybean meal and other protein-
rich  feedstuffs)  and  synthetic  amino  acids  (lysine,  threonine,  and  methionine).  When  protein-
rich feedstuffs have high prices, as has been the case in the past few years, a decrease in feed 
costs  is  expected.  The  use  of  other  feed-grade  synthetic  amino  acids  such  as  tryptophan  and 
valine  allows  greater  reductions  but  can  lead  to  an  increase  in  feed  costs  [  337,  Webb  et  al. 
2005 ]. In general, the economic costs range from EUR -2 to EUR +2 per kg of N saved [ 508, 
TFRN 2014 ]. Moreover, reductions in water and slurry handling costs contribute to a decrease 
in production costs [ 290, Univ. of Newcastle 2002 ]. 

An example of the  calculation of the  extra costs of a low-protein diet and of the effect of the 
price fluctuations of feed materials and amino acids in the rearing of fattening pigs is reported in 
Table 4.22.  Figure 4.4  shows  the  calculated  extra  costs  for  a  low-protein  diet  with  the 
supplementation  of  synthetic  amino  acids  in  comparison  to  a  common  diet.  The  evolution  of 
prices for soya and the amino acids used for the selected period is presented in Figure 4.3. 

240 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Table 4.22:  Example of extra costs calculation for low-protein feeding strategies for fattening pigs  

Parameters for the calculation  

Values 

Chapter 4 

diet  with 

Reference diet 
Phase 1 CP level (20–60 kg) 
Phase 2 CP level (60–100 kg) 
Low-protein 
supplementation 
Phase 1 CP level (20–60 kg) 
Phase 2 CP level (60–100 kg) 
Phase 1 duration (20–60 kg) 
Phase 2 duration (60–100 kg) 
Average feed consumption 
Phase 1 (20–60 kg) 
Phase 2 (60–100 kg) 
Feed conversion ratio 
Occupation of the building 
Cleaning and disinfection 
Occupation days (20–100 kg) 
Number of cycles per year 
Production per place 

amino 

acid 

19 % 
16 % 

16.5 % 
13.5 % 
55 days 
45 days 

1.4 kg/pig/day 
2.2 kg/pig/day 
2.93  
85 % 
10 days 
124 days 
2.94 cycles/animal place/year 
294 kg per animal place per year 

amino 

Extra costs (1) 
Low-protein 
acid 
diet  with 
supplementation  with  unfavourable  market 
conditions 
Low-protein 
acid 
diet  with 
supplementation  with  favourable  market 
conditions 
(1) Cost data are based on raw material costs only. The effect of hardware, manipulation, etc. is not 

EUR -1.92/animal place/year (EUR -6.4/t 
of product) 

EUR 1.61/animal place/year (EUR 5.3/t of 
product) 

amino 

included. 

Source: [ 335, Spain 2010 ] [ 500, IRPP TWG 2011 ] [ 338, Piñeiro et al. 2009 ] 

Source: [ 338, Piñeiro et al. 2009 ] 

Figure 4.3:  Fluctuation  of  synthetic  amino  acids  and  high-protein  feedstuff  (soya)  prices  from 

2004 to 2008 

Intensive Rearing of Poultry or Pigs 

241 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 338, Piñeiro et al. 2009 ] 

Figure 4.4:  Example of the cost  difference between a low-protein diet and a conventional diet in 

Spain  

From Denmark, an increase in feed costs of between EUR 0.26 and EUR 0.39 per pig (DKK 1 = 
EUR 0.13) is reported when a low-protein feeding regime is applied to an already standard low-
protein  diet  for  fattening  pigs  achieving  up  to  15 %  ammonia  reduction  [  624,  IRPP  TWG 
2013 ]. The cost of supplementation of amino acids increases when the target protein content in 
the animal feed is lowered. 

Driving force for implementation 
Low-protein  animal  feeding  is  one  of  the  most  cost-effective  and  strategic  ways  of  reducing 
NH3 emissions [ 508, TFRN 2014 ]. Along with the aim of reducing emissions, this technique is 
put in place for a parallel optimisation of animal performance, the health status of the animals, 
and  feed  costs.  Formulating  with  a  constraint  on  each  amino  acid  allows  the  matching  of 
nutrients  to  the  animals'  requirement.  The  reduction  of  protein  excess  in  an  animal's  stomach 
also  decreases the occurrence of  diarrhoea. At an EU scale, reducing the utilisation of proteic 
raw materials allows the reduction of soybean meal imports from non-EU countries. 

Example plants 
Low-protein, amino-acid-supplemented diets are already used throughout Europe. 

Reference literature 
[ 34, Ajinomoto 2000 ] [ 43, COM 2003 ] [ 281, France 2010 ] [ 290, Univ. of Newcastle 2002 ] 
[  312,  Fefana  2010  ]  [  313,  Fefana  2010  ]  [  314,  Fefana  2010  ]  [  315,  Fefana  2010  ]  [  316, 
Fefana  2010  ]  [  317,  Fefana  2010 ]  [  318,  Fefana  2010  ]  [  319,  Fefana  2010  ]  [  320,  Fefana 
2010 ] [ 321, Fefana 2010 ] [ 322, Fefana 2010 ] [ 325, CRPA 2009 ] [ 326, Germany 2010 ] 
[ 330, Denmark 2010 ] [ 335, Spain 2010 ] [ 337, Webb et al. 2005 ] [ 338, Piñeiro et al. 2009 ] 
[ 379, Spain 2009 ] [ 396, LEI 1999 ] [ 414, Fefana 2001 ] [ 451, Portejoie et al. 2002 ] [ 500, 
IRPP TWG 2011 ] [ 508, TFRN 2014 ] [ 590, Batfarm 2013 ] [ 624, IRPP TWG 2013 ] 

242 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

4.3.4 

Addition of phytase to achieve phosphorus-balanced diets for 
poultry and pigs 

Description 
Phosphorus  that  is  contained  within  phytate  (phytic  acid),  the  principal  storage  form  of 
phosphorus in  feed  ingredients  of  plant  origin (see  Table 4.23),  cannot  be readily  digested  by 
monogastric animals like poultry and pigs, as they lack the appropriate enzyme activity in their 
digestive tract. In particular, only about 30 % of the phosphorus in feedstuffs of plant origin is 
digestible by pigs and poultry. Traditionally, inorganic phosphorus is supplemented to feed in 
order  to  meet  the  animals'  nutritional  needs.  The  addition  of  phytase  in  the  diet  allows  the 
release  of  phosphorus  from  phytate,  so  it  becomes  available  for  digestion,  thus  reducing  the 
level  of  supplementation  of  inorganic  phosphorus.  The  reduction  of  phosphorus  excretion  is 
thus achieved by: 

 

 

 

adding phytase; 

increasing the availability (digestibility) of phosphorus in plant feed materials; 

reducing the use of inorganic phosphate in feeds. 

New  approaches  are  being  developed  by  some  plant-breeding  companies  and  which  involve 
developing  plant  varieties  with  high  phytase  activity  and/or  low  phytic  acid  content  
[ 30, Spain 2001 ] [ 453, DEFRA 2011 ].  

Table 4.23:  Total  phosphorus,  phytate-phosphorus  and  phytase  activity  in  selected  plant 

feedstuffs 

Feedstuffs 

Total P 
(%) 
0.28 
0.33 
0.37 
0.37 
0.36 
0.27 
1.16 
1.71 
0.61 
0.68 
1.12 
1 
0.38 

Maize 
Wheat 
Barley 
Triticale 
Rye 
Sorghum 
Wheat bran 
Rice bran 
Soybean meal 
Peanut meal 
Rapeseed meal 
Sunflower meal 
Peas 
Source: [ 452, Fefana 2002 ] 

Phytate-P 
(%) 
0.19 
0.22 
0.22 
0.25 
0.22 
0.19 
0.97 
1.1 
0.32 
0.32 
0.4 
0.44 
0.17 

Phytase activity 
(U/kg) 
15 
1 193 
582 
1 688 
5 130 
24 
2 957 
122 
8 
3 
16 
62 
116 

Achieved environmental benefits 
The data reported below for pigs and poultry can be found in many publications on the use of 
phytase in feedstuffs. They provide a summary of the results obtained with different feeds and 
in different situations, with possible reductions presented in relative terms.  

Benefits for pigs include the following: 

 

 

the inclusion  of  phytase in  feed improves  the  plant  phosphorus  digestibility  by 20 %  to 
30 % in weaners, and 15 % to 20 % for growers and finishers, as well as for sows; 

as a general rule, a reduction of phosphorus of 0.1 % in feed, by using phytase, results in 
a  reduction  in  phosphorus  excretion  of  35 %  to  40 %  for  weaners,  25 %  to  35 %  for 
growers and finishers, and 20 % to 30 % for sows. 

Intensive Rearing of Poultry or Pigs 

243 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Benefits for poultry include the following: 

 

 

The inclusion of phytase in feed improves the plant phosphorus digestibility by 20 to 30 
percentage points in broilers, layers and turkeys. Variations in the results are linked with 
the  level  of  phytate-phosphorus  contained  in  the  plant  materials  used  in  the  diet 
formulation. 

As  a  general  rule,  a  reduction  of  0.1 %  of  total  phosphorus  in  feed  by  using  phytase 
results in a reduction in phosphorus excretion of more than 20 % for layers and broilers. 

The improvement of phytic phosphorus digestibility can be even higher (around 50 percentage 
points) depending upon the feedstuff, phytase type and phytase concentration [ 624, IRPP TWG 
2013 ]. 

Low-phosphorus, phytase-supplemented diets, as used in the trials, did not affect growth, feed 
conversion  ratios  or  egg  production  when  compared  with  reference  diets  containing  a  higher 
phosphorus concentration.  

It  has  been  shown  that  phytase  improves  not  only  phosphorus  digestibility,  but  also  protein 
digestibility [ 170, Spain 2007 ]. Moreover, as the requirement for mineral phosphates addition 
in  the  diets  is  reduced  or  eliminated,  it  allows  the  reduction  of  the  use  of  scarce  and  non-
renewable resources from P mineral reserves.  

A  reduction  of  phosphorus  with  the  addition  of  phytase  should  be  applied  taking  into 
consideration  the  feed  formulation,  in  order  to  avoid  the  uncontrolled  modification  of  the 
phosphorus-calcium ratio. At the farm level, no specific technical skills are needed to use low-
phosphorus, phytase-supplemented feed. 

Cross-media effects 
The  substitution  of  mineral  phosphorus  with  phytase  needs  to  be  followed  by  a  parallel 
reduction of calcium, in order to maintain growth and bone mineralisation at the proper level. 
Calcium reduction cannot be excessive in order not to limit in turn the growth rate [ 281, France 
2010 ]. 

Environmental performance and operational data 
Since  phytase  are feed  additives,  they  are evaluated for  their  efficacy  before authorisation  for 
use in animal nutrition. The evaluation of the scientific information supporting the efficacy of 
phytase  is  carried  out  by  the  European  Food  Safety  Authority’s  Panel  on  Additives  and 
Substances used in animal nutrition (FEEDAP). Different types of phytase have been evaluated 
by the FEEDAP and their evaluation led systematically to the authorisation of these products, 
based on their safety and efficacy. 

Phytase can be incorporated in feedstuffs in powder, granulated coated or liquid form. Powder 
and  granulated  forms  are  used  in  production  processes,  only  where  the  temperature  does  not 
exceed  75–80 °C.  Commercial  coated  forms  exist  that  have  demonstrated  stability  at 
temperatures higher than 80 °C, and up to 90 °C. At a higher conditioning temperature, the use 
of the liquid form (post pelleting) is advised.  

Examples of the reduction of excreted diphosphorus pentoxide (P2O5) associated with the use of 
low-phosphorus diets, with or without the addition of phytase, are reported in Table 4.24 for pig 
production, together with an indication of the diet formulation applied. 

244 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 4.24:  Examples of excreted  phosphorus reduction for different feeding programmes in the 

pig sector, applying a low-phosphorus diet with or without addition of phytase  

Animal 

Source 

Diet/parameters 

P2O5  
reduction (1) 
(%) 

Chapter 4 

Weaners 

Fattening 
pigs 

Sows  

France 
CORPEN 1 

France 
CORPEN 2 

Germany 
RAM 

Belgium (Flanders) 

France 
CORPEN 1 

France 
CORPEN 2 

Germany 
RAM 

Belgium (Flanders) 

France 
CORPEN 1 

France 
CORPEN 2 

Germany 
RAM 

Belgium (Flanders) 

Two phases:  
CP 20 %; P 0.85 % (1st phase)  
CP 18 %; P 0.70 % (2nd phase) 
Two phases:  
CP 20 %; P 0.77 % (1st phase) + phytase 
CP 17 %; P 0.60 % (2nd phase) + phytase 
One phase  
CP 18 %; P 0.55 %  
(< 30 animal weight) 
One phase: 
P 0.60 % (7–20 kg animal weight) 
Two phases:  
CP 16.5 %; P 0.52 % (growers)  
CP 15.0 %; P 0.45 % (finishers)  
Two phases:  
CP 15.5 %; P 0.47 % + phytase (growers)  
CP 13.0 %; P 0.40 % + phytase (finishers)  
Two phases:  
CP 17.0 %; P 0.55 % (< 60 kg of LW)  
CP 14.0 %; P 0.45 % (> 60 kg of LW)  
Two phases: 
P 0.55 % (20–40 kg animal weight) 
P 0.50 % (40–110 kg animal weight) 
Two phases:  
CP 16.5 %; P 0.65 % (lactation)  
CP 14.0 %; P 0.50 %(gestation)  
Two phases:  
CP 16.0 %; P 0.57 % + phytase (lactation)  
CP 12.0 %; P 0.42 % + phytase (gestation)  
Two phases: 
CP 16.5 %; P 0.55 % (lactation)  
CP 14.0 %; P 0.45 % (gestation)  
Two phases: 
P 0.55 % (20–40 kg animal weight) 
P 0.50 % (40–110 kg animal weight) 

Source: [ 414, FEFANA 2001 ] [ 329, CORPEN 2003 ] 

11 

29 

22 

31 

31 

44 

29 

19 

21 

35 

21 

19 

Technical considerations relevant to applicability 
On farm, no specific additional requirements are needed for the application of low-phosphorus, 
phytase-supplemented diets compared to a high-phosphorus diet, when applied under the same 
conditions (one-phase or multiphase feeding programmes). 

This  approach  to  reducing  phosphorus  pollution  can  be  implemented  very  readily  on  a  large 
scale as: 

 

 

 

no investment is needed for powder and granulated phytase, although some investment is 
needed in feed mills using liquid phytase; 

no structural alterations are required on the farm; 

one feed mill generally covers a large number of farms [ 452, Fefana 2002 ].  

Phytase may not be applicable in the case of organic livestock production. 

Intensive Rearing of Poultry or Pigs 

245 

 
 
 
 
 
 
 
 
Chapter 4 

Economics 
For  feeding  low-phosphorus,  phytase-supplemented  diets,  there  is  no  need  for  any  special 
equipment at the farm level or any additional investment. Furthermore, adaptation of the feed, 
by addition of phytase and adaptation of the nutrient levels, can lead to a reduction of the feed 
costs [ 452, Fefana 2002 ]. Phytase is cost-effective for a reduction of the total phosphorus in 
the feed of about 15–20 % of its content (0.1 % in the raw feed), with savings of up to EUR 0.88 
per tonne of feed (exchange rate EUR 1 = GBP 0.88) [ 290, Univ. of Newcastle 2002 ]. 

Driving force for implementation 
The reduction of phosphorus in diets reduces not only the feed costs, but ultimately also reduces 
the land surface requirements for manure spreading, since the phosphorus load in the excreta is 
smaller. Limitations to phosphorus application on the fields are in place in some MS. 

Example plants 
The addition of phytase is a well-established technique and is generally applied. 

Reference literature 
[ 30, Spain 2001 ] [ 170, Spain 2007 ] [ 281, France 2010 ] [ 290, Univ. of Newcastle 2002 ] 
[ 329,  CORPEN  2003  ]  [  414,  FEFANA  2001  ]  [  452,  Fefana  2002  ]  [  453,  DEFRA  2011  ] 
[ 624, IRPP TWG 2013 ]  

4.3.5 

Highly digestible inorganic feed phosphates 

Description 
Phosphorous  digestibility  is  improved  by  using  an  increased  amount  of  highly  digestible 
inorganic  phosphates  in  diets.  Inorganic  feed  phosphates  are  classified  as  mineral  feed 
ingredients. They are listed in the catalogue of feed materials published in accordance with EC 
Regulation  767/2009  on  the  marketing  of  feed.  These  feed  phosphates  differ  with  respect  to 
their  mineral  content  and  their  chemical  composition  and  as  a  result  they  have  different 
phosphorus  digestibilities.  Highly  digestible  phosphates  are  used  to  replace  conventional 
sources of phosphorus in the feed. 

Feed  phosphates  are  incorporated  into  animal  feed  either  in  powder  or  in  granulated  form, 
depending  on  the  physical  properties  of  the  end  product.  Inorganic  feed  phosphates  are 
predictable in  terms  of  their  chemical  composition  and  in  their  digestible  phosphorus  content, 
partly because they are not susceptible to process conditions (such as heat or moisture).  

Achieved environmental benefits 
The reduction of the total amount of phosphorous in the feed formulation results in a reduction 
of P excretion and subsequent losses to the environment.  

Cross-media effects 
There are no cross-media effects of the use of highly digestible phosphorus, as the reduction of 
excretion is a direct consequence of the phosphorus digestibility. There is no impact on phytate-
bound  phosphorus  excretion,  which  transits  unabsorbed  and  is  then  kept  in  the  manure. 
However,  it  should  be  considered  that  supplies  of  the  highest  digestibility  feedstuffs  might 
become  insufficient  to  cover  the  overall  market  need  for  animal  feed,  particularly  when 
phosphorus supplies are tight. 

Environmental performance and operational data 
Table 4.25 gives an example of reduced phosphorous excretion by the use of highly digestible 
feed  phosphates.  The  same  type  of  calculation  can  be  applied  for  pigs,  resulting  in  the  same 
reduction in phosphorus excretion. 

246 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.25:  Calculated  reduction  of  phosphorus  excretion  based  on  digestibility,  for  the  poultry 

sector 

Feed 
phosphate 

Digestibility 
(%) 

Inclusion rate 
(%) 

Inclusion rate 
(g P) 

Absorbed P (1) 
(g) 

Excreted P(1) 
(g) 

Defluorinated 
phosphate 
Monocalcium 
phosphate 

59 

84 

1.56 

0.87 

28.0 

19.6 

16.5 

16.5 

11.5 

3.1 

(1) Originating from the inorganic feed phosphate. 

Source: [ 542, CEFIC 2002 ]  

From Denmark, a nutritional system for fattening pigs is reported aiming to reduce phosphorus 
emissions. This system is a combination of the following combined techniques: 

 

 

 

a higher phytase concentration (1.5 times the standard dose); 

addition of monocalcium phosphate; 

phase feeding with levels of phosphorus in feed around 0.47 % for pigs of 25–50 kg and 
0.45 % for pigs of 50–110 kg. 

Compared  with  a  typical  feeding  strategy  (addition  of  dicalcium  phosphate  and  one-phase 
feeding with 0.63 % P in the feed), the above combination results in a reduction of 17–18 kg of 
P  applied  per  hectare.  The  cost  of  the  above  combined  nutritional  strategy  is  reported  as 
EUR 0.067 per pig produced [ 650, Denmark 2010 ]. 

Technical considerations relevant to applicability 
The use of highly digestible feed phosphates can be implemented very easily. No investments 
are needed, either at the farm level or at the feed compounder level [ 542, CEFIC 2002 ]. 

Economics 
A  general  description  on  the  cost  assessment  of  nutritional  management  is  given  in  Section 
4.3.1. No cost increases for the farmer are involved for the change to the use of highly digestible 
inorganic  feed  phosphates.  Feed  phosphates  are  normally  sold  based  on  the  total  phosphorus 
content.  Highly  digestible  inorganic  feed  phosphates  are,  in  fact,  calculated  on  the  digestible 
phosphorus content, and economy of use over other feed phosphates.  

Less  phosphorus  is  excreted,  resulting  in  lower  manure  processing  costs  for  the  farmer.  
Depending on the inorganic phosphorus availability, the price of these sources of phosphate is 
highly volatile and can lead to an increase of feed prices, and to inorganic phosphorus becoming 
expensive  [  542,  CEFIC  2002  ].  When  a  combination  of  techniques  is  used,  the  amount  of 
phytase  added  depends  on  the  market  price  of  phytase  and  monocalcium  phosphate.  The 
cheapest combination is chosen [ 650, Denmark 2010 ]. 

Driving force for implementation 
Phosphorus is a pollutant that locally raises particular concerns and  it may be  subject to  strict 
compliance requirements. 

Example plants 
Some feed producers and farms in regions which have environmental problems because of the 
high  concentration  of  intensive  animal  rearing  have  already  started  to  use  more  digestible 
inorganic feed phosphates. Notably, this has taken place in the Netherlands, where there was no 
negative impact on animal performance, but there was a positive effect on phosphorus excretion 
[ 542, CEFIC 2002 ]. 

Reference literature 
[ 542, CEFIC 2002 ] [ 650, Denmark 2010 ] 

Intensive Rearing of Poultry or Pigs 

247 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.3.6 

Other feed additives 

Description 
Enzymes and other authorised feed additives are added in small amounts to the feed in order to 
enhance the animal performance by improving  the digestion of nutrients and the utilisation of 
feed.  As  a  consequence,  animals  achieve  higher  growth  rates  and/or  an  improved  feed 
conversion ratio and a reduced amount of nutrients is excreted. Feed additives that are added in 
small amounts to the feed of poultry and pigs are: 

 

 

 

 

enzymes (xylanases, glucanases, proteases, etc.); 

growth enhancers (non-antimicrobial); 

microorganisms; 

organic acids. 

Several  groups  of  feed  additives  used  in  animal  nutrition  are  authorised  and  regulated  at  the 
European Union level (e.g. animal species, withdrawal period, minimum and maximum dosage 
in feeds). Annex I to EC Regulation 1831/2003 of September 2003 reports a list of feed additive 
groups, many of them not included in this section since their use is not associated with specific 
environmental  benefits.  This  is  particularly  the  case  for  many  technological  and  sensory 
additives.  Commission  Regulation  (EC)  429/2008  lays  down  the  implementing  rules  for 
ensuring the efficacy of a feed additive in terms of its environmental performance. 

Achieved environmental benefits 
As  a  consequence  of  the  improved  feed  conversion  rate,  a  reduction  of  the  total  nutrients 
excreted by pigs (as a general approximation) of  3 % can be achieved; for poultry this can be 
approximately  5 %.  These  reductions  are  expected  at  an  improvement  in  the  feed  conversion 
rate of 0.1 units [ 543, Fefana 2002 ]. 

Certain additives, such as enzymes, may also allow the use of feed materials of a lower energy 
content and a high non-starch polysaccharides content in the feed, with a positive influence on 
gut health in pigs.  

Cross-media effects 
No  specific  cross-media  effects  have  been  reported.  Conditions  for  authorisation  of  feed 
additives according to Article 5 of Regulation (EC) 1831/2003 require that they do not have an 
adverse effect on animal health, human health or the environment. 

Environmental performance and operational data 
Information and data concerning the use of different feed additives are reported in the specific 
sections (see Sections 4.3.6.1, 4.3.6.2, 4.3.6.3, and 4.3.6.4). 

Technical considerations relevant to applicability 
Feed additives (e.g. enzymes) are incorporated into feedstuffs in powder, granulated, coated or 
liquid form. Powder and granulated forms are to be used in production processes, only where 
the  temperature  is  not  too  high  (up  to  80–85 °C).  Coated  forms  can  be  used  at  higher 
temperatures, up to 90–95 °C. 

Stability performance may vary from one product to another, hence information on the stability 
may be requested from the supplier. Liquid feed additives are applicable when processes lead to 
high  temperatures  in  the  die  by  means  of  specific  equipment  that  supply  the  product  after 
pelletisation. Some feed mills are already equipped with such systems. 

248 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

There are no specific additional requirements for the application of feed additives on the farm. 
This approach to reducing nutrient excretion can be implemented very readily on a large scale 
as: 

 

 

 

no  investment  is  needed  for  powder  and  granulated  feed  additives,  although  some 
investment is needed in feed mills using liquid additives; 

no structural alterations are required on farm; 

one feed mill generally covers a large number of farms [ 543, Fefana 2002 ]. 

Economics 
A  general  description  of  the  cost  assessment  of  nutritional  management  is  given  in 
Section 4.3.1.  The  introductory  cost  is  generally  covered  by  better  animal  performance  
[ 543, Fefana 2002 ]. 

Driving force for implementation 
The  optimisation  of  animal  performance,  together  with  a  potential  positive  effect  on  animal 
health and a reduction of the excreted nutrients, are the main driving forces for the use of these 
additives. 

Example plants 
Feed additives are generally used in intensive animal production. 

Reference literature 
[ 543, Fefana 2002 ] 

4.3.6.1 

Benzoic acid 

Description  
Benzoic acid is mainly added to feed and it is degraded in the animal to hippuric acid, which 
lowers the urine pH and consequently the pH of the slurry stored in the pig house. The use of 
benzoic  acid  (C6H5-COOH)  as  a  zootechnical  additive  is  covered  by  Regulation  (EC) 
1831/2003.  

Achieved environmental benefits 
At the lower pH, ammoniacal nitrogen is retained in solution and, consequently, is expected to 
volatise less ammonia. However, not all evidence suggests that there is a reduction in ammonia 
emissions, even though benzoic acid is effective at reducing urinary pH [ 664, EFSA 2007 ].  

Since  a  lower  pH  reduces  the  activity  of  bacteria  responsible  for  methanogenesis,  it  can  be 
expected  that  direct  CH4  emissions  from  the  manure  will  be  reduced  as  well.  However,  trials 
with 1 % addition have shown that benzoic acid has no direct effect on odour or greenhouse gas 
emissions [ 288, Wageningen 2007 ] or the effect is not significant (17 % reduction for odour 
emissions after 1 % addition of benzoic acid) [ 651, DAFC 2010 ]. 

An addition of 0.5 % benzoic acid to the feed in fattening pig production has been reported as 
having a positive influence on the digestion of nutrients and the utilisation of feed. In particular, 
a statistically significant reduction of 0.14 is reported for the feed conversion ratio for the whole 
period  of  fattening  observed  in  the  finishing  period  [  281,  France  2010  ].  However,  in  other 
trials with the addition of 0.5 % or 1 % benzoic acid, these improvements have been found to be 
insignificant [ 284, Guingand et al. 2005 ].  

Because more nitrogen can be retained in the manure, it may lead to a reduced consumption of 
mineral  fertilisers  and  lower  indirect  emissions  (associated  with  the  production  of  the 
fertilisers). 

Intensive Rearing of Poultry or Pigs 

249 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
Since a relatively higher quantity of nitrogen is retained in the manure, the subsequent changes 
in the manure composition in the proceeding operations must be taken into consideration, from 
higher  nutrient  supply  to  an  increased  potential  for  NH3  and  GHG  emissions  from 
landspreading. As the addition of benzoic acid is relatively high (from 0.5 % to 1.0 %), this has 
to  be  taken  into account  when  formulating  the  feed,  to  avoid the  nutritional  value  of  the feed 
being reduced. 

An  increase  of  sulphur-based  odour  emissions  has  been  reported  for  higher  doses  (2 %)  of 
benzoic acid for diets supplemented with methioanine [ 454, Eriksen et al. 2010 ]. 

Environmental performance and operational data 
Many research studies have been carried out on this substance, and results are varied. Most of 
the  studies  evaluate  positively  the  environmental effects  which  are summarised in Table 4.26. 
Data reported show that the addition of benzoic acid is consistently associated with lower urine 
pH.  Additional  information  concerning  other  important  characteristics  and  the  results  of  the 
trials, in particular the average dietary protein content or the difference in cost compared to the 
untreated feed, are reported in the table. Effects on the average daily weight gain performance, 
the  feed  conversion  rate  performance,  and  on  the  carcass  quality  have  been  reported  as  not 
significant or having a positive effect. Only in one case, with 1 % benzoic acid addition, has a 
negative effect on the carcass quality been reported. 

Table 4.26 shows that the addition of benzoic acid at a concentration of 1.0 % can reduce the 
ammonia  emissions  from  the  housing  system.  The  reduction  varies  from  6 %  to  24 %, 
depending on the operating conditions. For an addition of 0.5 % of benzoic acid in the feed, an 
ammonia reduction potential of 3.6–5 % is reported. 

Measurements carried out in Denmark with an addition of 1 % benzoic acid in feed for fattening 
pigs revealed reductions in ammonia emissions of 7.5 % and 14 % respectively. The effect of 
benzoic acid on ammonia emission reduction was independent of the dietary protein, while no 
statistical significant difference was found for the slurry pH [ 651, DAFC 2010 ] [ 652, DAFC 
2012 ]. 

250 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

Table 4.26:  Measured results of benzoic acid effects by rate of addition and by the characteristics 

of the tests in growing and finishing pigs 

Benzoic acid in feed 0.5 % (0.5 % in 1st phase; 0.5 % in 2nd phase) 

Source 

Diet 

Test results (1) (2)  

[ 283, Guingand et al. 
2005 ] 

Two-phase feeding:  
CP 16.6–15.1 % 

[ 284, Guingand et al. 
2005 ] 

Two-phase feeding:  
CP 16.6–15.5 % 

[ 285, Fefana 2004 ] 

Three-phase feeding:  
CP 18.0–16.4–15.0 % 

NH3 reduction: 5 % 
 pH urine: 0.45  
Additional costs: EUR 7.7 per animal place 
NH3 reduction: 3.6 % 
 pH urine: 0.3 
Additional costs: EUR 7.93 per animal place 
NH3 reduction: 40 % 
 pH urine: Not available 
Additional costs: EUR –2 per animal place (3) 

Benzoic acid in feed 1 %  
(0.5 % 1st phase; 1 % 2nd phase)  

[ 284, Fefana 2005 ] 

Two-phase feeding:  
CP 16.6–15.5 % 

Two-phase feeding:  
CP 17.0–16.0 % 

Two-phase feeding:  
CP 18.1–15.5 % 

[ 288, Wageningen 2007 ] 
[ 282, Netherlands 2010 ] 

Two-phase feeding:  
CP 18.1–15.0 % 

Two-phase feeding:  
CP 18.1–16.2 % 

NH3 reduction: 24 % 
 pH urine: 0.9 
Additional costs: EUR 11.74 per animal place 
NH3 reduction: 21 % 
 pH urine: 0.96 
Additional costs: EUR 6.94 per animal place 
NH3 reduction: 13 % 
 pH urine: 1.30 
Additional costs: EUR 8.1 per animal place 
NH3 reduction: 6.4 % 
 pH urine: 1.72 
Additional costs: EUR 7.3 per animal place 
NH3 reduction: 6.4 % 
 pH urine: 1.39 
Additional costs: EUR 9.36 per animal place 
Average  NH3  reduction  in  the  above  4  trials: 
15.8 %.  Ammonia  emissions  range  from  2.58 kg 
to 2.17 kg/animal place/year 

Benzoic acid in feed 1 % 
One-phase feeding  

[ 651, DAFC 2010 ]  

CP 17.5 % and CP 
14.5 % 

NH3 reduction: 7.5 %  
 pH urine: 0.56 (CP 17.5 %) – 1.15 (CP 14.5 %) 
Additional  costs:  EUR 2.6  per  pig  (DKK 1 = 
EUR 0.13) 
NH3 reduction: 14.5 %  

[ 652, DAFC 2012 ] 
(1) Feed costs calculated based on March 2010 prices and for pig places at farms from 2.8 to 3.5 pigs/year.  
(2)  pH urine refers to the difference between untreated and treated urine. 
(3) The figure refers to a reduction in the feed cost of EUR 2.00/animal place. 

CP 17.5 % 

An assessment made by EFSA for the authorisation of benzoic acid as a feed additive for pigs 
for  fattening  concluded  that  the  efficacy  of  benzoic  acid  to  reduce  ammonia  emission  is  not 
straightforward even though benzoic acid was consistently effective  at reducing urinary pH in 
pigs for fattening. Not all submitted studies provided evidence of a significant reduction at the 
highest  level  of  10 000  mg  benzoic  acid  per  kg  of
feed,  while  the  lower  dietary  level  of 
5 000 mg per kg was not effective in all studies [ 664, EFSA 2007 ].  

Technical considerations relevant to applicability 
At the time of writing (2013), benzoic acid is authorised in the EU to be used as a zootechnical 
feed additive belonging to the functional group ‘other zootechnical additives’ for improving the 
animal performance, for weaners (Regulation 1730/2006/EC) and pigs for fattening (Regulation 
1138/2007/EC)  in  doses  of  5 000 mg/kg  and  between  5 000 mg/kg  and  10 000 mg/kg  of 
complete feedstuff, respectively.  

Intensive Rearing of Poultry or Pigs 

251 

 
 
 
 
 
 
 
Chapter 4 

Economics 
Data for the cost variations of feed with the addition of the related percentage of benzoic acid 
are reported in Table 4.26, expressed per pig place. This technique does not lead to additional 
investment costs. The addition of benzoic acid in feed is normally done by the feed millers and 
does not require any specific equipment for the farmers. 

Driving force for implementation 
In comparison with other techniques for ammonia reduction, the addition of benzoic acid to pig 
feed appears to be easier and less expensive [ 281, France 2010 ]. The technique is considered a 
best available technique for the reduction of ammonia emissions in the Netherlands. 

Example plants 
Industrial organisations report that benzoic acid use for pig feeding is increasing.  

Reference literature 
[ 281, France 2010 ] [ 282, Netherlands 2010 ] [ 283, Guingand et al. 2005 ] [ 284, Guingand et 
al.  2005 ]  [  285,  Fefana  2004  ]  [  288,  Wageningen  2007  ]  [  454,  Eriksen  et  al.  2010  ]  [  651, 
DAFC 2010 ] [ 652, DAFC 2012 ] [ 664, EFSA 2007 ] 

4.3.6.2 

Probiotics  

Description 
Probiotics are microorganisms that may favourably affect feed efficiency. 

Bacillus  organisms  are  specifically  selected  to  improve  growth  performance  and  manure 
decomposition. Bacillus species produce extracellular degrading enzymes (amylases, cellulases, 
lipases,  proteases,  etc.).  The  addition  of  these  microbes  in  pig  feed  provides  a  source  of 
enzymes  to  animals,  improving  the  nutrient  digestion  and  the  utilisation  of  feed,  and  thereby 
improving  feed  efficiency.  These  enzymatic  activities  are  a  likely  explanation  of  the  faster 
dispersion of manure in pens where pigs are fed with  Bacillus. In fact, spores survive through 
the  digestive  process  and  germinate  within  the  digestive  tract,  so  that  mature  microbes  are 
excreted  with  faecal  matter  and  can  also  produce  an  enzymatic  effect  in  the  external 
environment.  Lactobacillus  and  Enterococcus  faecium  rapidly  install  in  animal  intestines  and 
improve the sanitary state and the growth performance. 

Achieved environmental benefits 
The  enhanced  animal  performance  in  feed  conversion  reduces  the  excretion  of  nitrogen  and 
phosphorus,  since  more  nutrients  are  retained  in  the  animal  bodies.  However,  the  scientific 
evidence is not all conclusively positive on the consistent effectiveness of probiotics. Some test 
results  showed  that  growth  performance,  feed  conversion  ratios  and  mortality  were  not 
significantly different after the use of probiotics in broilers [ 477, O'Dea et al. 2006 ].  

The  improved  manure  degradability  induced  by  Bacillus  improves  pen cleaning,  as  it  reduces 
the time taken to disperse the manure mat.  

Cross-media effects 
No negative effects are reported. 

Environmental performance and operational data 
Bacillus  subtilis  and  Bacillus  licheniformis  strains  are  added  in  the  feed  at  rates  of  around 
0.05 % of a dietary supplement  that contains some 10e+8–10e+9 cfu/g of product. Enterococcus 
faecium  NCIMB  10 415  is  provided  in  doses  of  7.0×10e+8  cfu/kg  of  feed  for  sows  and  starter 
diets, and in doses of 3.5×10e+08 cfu/kg of feed for grower and finisher diets. For both Bacillus 
and Enterococcus, improvements of the feed conversion rates are reported to be in the range of 
0.37–0.38. 

252 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
The  effect  of  these  probiotics  is  a  reduced  excretion  of  nitrogen  and  phosphorus,  due  to  the 
increased  efficiency  of  the  feed  conversion.  The  estimated  effects  in  pigs  are  displayed  in 
Table 4.27. 

Chapter 4 

Table 4.27:  Reductions in excretion with the direct-fed microbial strains in pigs  

Microbial strains 

g of N per 
kg of LW 

kg of N 
per pig 

Excreted nitrogen 

kg of N 
per sow 
per year 
-2.29 
-2.86 

Excreted phosphorus (P2O5) 
kg of P2O5 
per sow per 
year 
-2.02 
-2.52 

g of P2O5 
per kg of 
LW 
-0.65 
NI 

kg of 
P2O5 per 
pig 
-0.068 
-0.085 

Lactobacillus (1) 
Enterococcus (2) 
NB:  Comparisons  are  made  with  the  same  diets  without  additives.  Type  of  data  =  measured  data,  based  on 
statistical analysis. NI = no information provided.  

-0.12 
-0.147 

-1.15 
NI 

Source:  
(1) [ 301, Fefana 2010 ]  
(2) [ 302, Fefana 2010 ] 

The effect of Lactobacillus on broilers may vary depending on the combination of the dose and 
the  protein  content  in  the  diet.  An  example  is  reported  in  Table 4.28,  where  the  effects  on 
finishing broilers are displayed for different doses mixed with different levels of dietary content 
of protein and minerals (Ca and non-phytin phosphorus). The average reduction of total nitrogen 
in excretion is 7.2 %. Some of these Lactobacilli are registered as silage additives.  

Table 4.28:  Reductions  in  excretion  with  the  direct-fed  microbial  strains  of  lactobacillus  in 

finishing broilers 

Type of diet 

Age  
(days) 

Classic high level protein (19 %) 
Medium level protein (17.3 %) 
Medium level protein (16.8 %) 
Medium  level  protein  (17.0 %), 
low Ca, low non-phytin P 
NB: Comparisons are made with the same diets without nutritional additives. 

28–42 
28–42 
32–42 

32–42 

0.45 

-1.6 

Probiotic 
dose 
(kg/tonne) 
0.9 
0.9 
0.95  

Reduction in 
total nitrogen 
(g/bird) 
-0.54  
-4.1 
-0.8 

Reduction 
in P2O5 
(%)  
-3.2 
-7.0 
-8.2 

-2.7 

Type of data = measured data, based on statistical analysis. 

Source: [ 303, Fefana 2010 ] 

Table 4.29 shows the feed conversion rates obtained with a 2 kg dose of commercial probiotics 
per tonne of feed for broilers. The average reduction of total nitrogen in excretion is 7.1 %. 

Table 4.29:  Gains in FCR and value of ingested feed with the use of probiotics in broilers 

Test feed without 
probiotic 
addition 
0.408 

Feed with added 
Lactobacillus 

Feed with added 
Bacillus 

Feed with added 
Pediococcus 

0.510 

0.476 

0 

+35.9 % 

+23.7 % 

0.427 

+6.2 % 

Feed conversion rate 
Economic gain per bird 
(above feed cost) 
Source: [ 306, Fefana 2010 ] 

Technical considerations relevant to applicability 
Probiotics can be easily added to diets for poultry meat. Probiotics are also easily mixed in feed 
for gestating sows, lactating sows, weaners and fattening pigs. Lactobacillus effects in turkeys 

Intensive Rearing of Poultry or Pigs 

253 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

are  in  the  line  with  those  of  broilers.  Protection  from  pathogens  (Salmonella)  has  been 
demonstrated [ 307, Fefana 2010 ]. This technique is only applicable to authorised preparations 
according to Regulation (EC) 1831/2003 which improve feed digestibility leading to a reduction 
of nutrient excretion. 

Economics 
The increased efficiency in feed transformation into meat returns a higher economic gain due to 
the saved feed, as is reported in Table 4.29.  

Driving force for implementation 
Probiotics  are  also  used  to  improve  animal  welfare  by  limiting  pathogenic  intestinal 
colonisation.  This  effect  basically  enhances  the  productive  performances  through  increased 
nutrient  retention.  Consequently,  a  positive  effect  on  piglet  mortality  (around  40 %  fewer 
deaths) is produced, as well as a greater resistance to bone breaks in poultry. 

Example plants 
The use of probiotics has increased significantly in the EU over the last 10 years, in particular 
after  the  ban  of  the  use  of  antibiotics  as  growth  promoters.  The  actual  use  of  these  additives 
varies by type of animal, by country and by customer requirements. The rate of penetration in 
the  pig  feed  market  is  estimated  by  production  companies  at  10 %  on  average,  with  peaks  of 
20 % for liquid feeds and up to 40–50 % in specific countries. For the poultry feed market, the 
penetration of this product is estimated to be from 8 % for layers to 10 % for broilers and up to 
15–20 % for turkeys [ 472, Fefana 2011 ].  

Reference literature 
[  301,  Fefana  2010  ]  [  302,  Fefana  2010  ]  [  303,  Fefana  2010  ]  [  306,  Fefana  2010  ]  
[ 307, Fefana 2010 ] [ 472, Fefana 2011 ] [ 477, O'Dea et al. 2006 ] 

4.3.6.3 

Enzymes  

Description 
When the feed quality is low (high fibre content and low digestibility of the feed), enzymes may 
help  to  increase  the  digestibility.  When  feed  digestibility  decreases  (e.g.  at  high  non-starch 
polysaccharide  levels  -  NSP),  nutrient  excretion  is  increased.  The  non-starch  polysaccharide 
degrading  enzymes  (NSP  enzymes),  such  as  xylanases,  cellulases  and  glucanases,  are 
incorporated  into the animal  feed to allow the breakdown of NSP and, therefore, to achieve a 
faster  and  more  complete  digestion  of  the  feed,  leading  to  an  improved  nutritional  value. 
Additionally, the enzyme protease is supplemented with the feed to increase the digestibility of 
the protein contained in the plant feed materials. 

The use of NSP enzymes and proteases allows the digestibility of a number of feedstuffs with 
low digestibility to be increased, although this beneficial effect is demonstrated to be dependent 
on the wheat cultivar used [ 485, Gutierrez del Alamo et al. 2008 ]. The effect of the cultivar 
applies to most of the cereals [ 624, IRPP TWG 2013 ].  

Enzymes can be used individually or in combination; their synergistic effect depends on the diet 
[  281,  France  2010 ]. The efficacy  of  enzymes  as  digestibility  enhancers  for  pigs  and  poultry 
(see  the  Register  of  Feed  Additives  pursuant  to  Regulation  (EC)  1831/2003)  has  been 
favourably assessed.  

Achieved environmental benefits 
Lower protein contents in feed normally result in lower nitrogen excretion and lower ammonia 
emissions. Therefore, practices that allow a reduction of the crude protein content in feed, either 
by increasing the protein digestibility, as in the addition of the enzyme protease, or increasing 
the global animal performances (e.g. feed conversion), can in turn reduce ammonia emissions. 

254 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
The  use  of  feed  enzymes  often  reduces  the  digestibles’  viscosity  by  degrading  non-starch 
polysaccharides (NSP), thereby decreasing the moisture content of the faeces. Subsequently this 
results in a reduction of the potential development of fermentation in poultry litter, and thus a 
decrease in ammonia emissions [ 543, Fefana 2002 ]. 

Chapter 4 

Cross-media effects 
No cross-media effects have been reported. 

Environmental performance and operational data 
Poultry 
The  response  of  individual  added  enzymes  may  be  dependent  on  the  composition  of  the  diet 
[ 479, Bedford et al. 2011 ] [ 481, Thacker 2005 ]. An improved protein digestibility for a wide 
range of natural ingredients is reported to be in the range of 3–8 % when protease is added to 
broiler diets [ 573, DSM et al. 2012 ].  

The effect of mixtures of protease, xylanase and phytase is a higher retention of nitrogen than 
with  enzyme-free  feed.  Higher  amounts  of  nitrogen  can  be  retained,  hence  lower  amounts  of 
nitrogen are excreted, due to the better digestion efficiency (see Table 4.30).  

Table 4.30:  Average  daily  balance  of  nitrogen  in  broilers  with  and  without  the  addition  of  feed 

additives (enzymes) 

Nitrogen (g/bird) 

Ingested N 
Fixed N 
Excreted N 
Source: [ 305, Fefana 2010 ] 

Control feed 
(no enzymes) 
124.62 
68.52 
56.10 

Feed with added 
NSP enzymes 
123.75 
71.63 
52.12 

Variation in nitrogen  
(%) 
-0.7 
+4.5 
-7.1 

According  to  some  authors,  the  use  of  enzymes  is  beneficial  only  during  the  first  phase  of 
growth. The effectiveness of additives is summarised in Table 4.31, where the positive effect is 
shown with a ‘+’ sign, and a ‘-’ sign indicates no significant effect in that given stage. 

Table 4.31:  Effect of different additives in poultry at various feeding stages 

Animal 

Laying hen 

Broiler 

Duck 

Turkey starter 

Male turkey 

Female turkey 

Type of additive 
Coccidiostatic 
NSP enzyme 
Phytase 
Coccidiostatic 
NSP enzyme 
Phytase 
Coccidiostatic 
NSP enzyme 
Phytase 
Coccidiostatic 
NSP enzyme 
Phytase 
Coccidiostatic 
NSP enzyme 
Phytase 
Coccidiostatic 
NSP enzyme 
Phytase 

1-phase 
- 
- 
+ 
+ 
+ 
+ 
- 
+ 
+ 
+ 
- 
+ 
+ 
+ 
+ 
+ 
+ 
+ 

2-phase 
- 
+ 
+ 
+ 
- 
+ 
- 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 

3-phase 
- 
+ 
+ 
- 
- 
+ 
. 
. 
. 
. 
. 
. 
+ 
+ 
+ 
- 
+ 
+ 

Source: [ 327, Germany 2010 ] 

Intensive Rearing of Poultry or Pigs 

255 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Xylanases are added to commercial wheat-based compound feed for broilers in order to improve 
the  growth  and  the  feed  conversion  ratio.  At  the  same  time,  the  intestinal  viscosity  and  the 
quantity of nutrients excreted are reduced [ 478, Sieo et al. 2005 ]. The combined provision of 
xylanase, amylase and protease improves the utilisation of feed and increases the body weight 
by approximately 6 % to 7 %. By improving the digestibility of some nutrients, enzymes might 
also  improve  the  performance  of  broilers  that  are  fed  with  suboptimal  diets  for  Ca  and  P  
[ 482, Cowieson et al. 2005 ] [ 483, Cowieson et al. 2010 ]. 

Supplementation  of  glucanase  strains  in  chicken  diets  can  reduce  the  intestinal  viscosity  by 
21 % to  46 %  (compared to  an  unsupplemented  feed diet)  [  478,  Sieo et  al.  2005  ].  Protease-
supplemented  diets  can  produce  improvements  in  weight  gain  and  the  feed  conversion  rate 
[ 479,  Bedford  et  al.  2011  ]  [  480,  Yu  et  al.  2007  ]  [  481,  Thacker  2005  ].  In  commercial 
products 
to 
560/250 TXU/TGU (xylanase/glucanase) per kg of complete feed [ 327, Germany 2010 ].  

from  280/125 TXU/TGU 

the  enzyme  activity 

in  Germany, 

ranged 

Pigs 
A  study  carried  out  in  Denmark  calculated  that  the  addition  of  a  NSP  enzyme  (xylanase)  in 
feeds  for  fattening  pigs,  due  to  the  increase  of  digestibility,  allows  the  modification  of  the 
nutritional  characteristics  of  the feed  by  decreasing  protein levels  or  by  improving  the animal 
performance  (e.g.  feed  conversion  ratio).  Modelled  results  showed  that,  with  the  use  of  NSP 
enzymes, the crude protein  level was reduced from 16.59 % to 15.35 % (1.24 points of CP or 
7.8 %  less  compared  to  the  untreated  diet),  feed  consumption  decreased  by  2.5 %  while  feed 
efficiency (FCR) improved from 2.89 to 2.83. Calculations showed that the total N excreted was 
reduced by 6.2 g/kg of live weight and the quantity of manure was reduced by 0.012 kg/kg of 
live weight [ 304, Fefana 2010 ]. 

Technical considerations relevant to applicability 
Only  authorised  feed  additives  according  to  Regulation  (EC)  1831/2003  are  applicable.  The 
technique  is  generally  applicable  to  pigs  and  poultry.  It  can  be  used  alone  or  in  combination 
with other nutritional measures (e.g. industrial amino acid addition, phase feeding) for further 
reductions  in  excreted  nitrogen  [  573,  DSM  et  al.  2012  ].  The  response  of  individual  added 
enzymes  may  be  dependent  on  the  composition  of  the  diet,  its  activity  and  the  origin  of  its 
strains [ 479, Bedford et al. 2011 ] [ 481, Thacker 2005 ] [ 281, France 2010 ].  

Economics 
The  addition  of  enzymes  to  broiler  feed  adds  costs  equivalent  to  that  of  less  than  1 %  of  the 
untreated feed, on average. On this basis, in the case of broiler production, feed costs increase 
by 0.3 %, from EUR 6.78 per broiler place per year, (untreated feed) to EUR 6.80 with added 
enzymes.  Cost  savings  are  also  feasible,  depending  on  the  market  prices  of  protein-rich  feed 
ingredients [ 305, Fefana 2010 ]. Cost savings of EUR 2 to EUR 6 per tonne of feed are reported 
for the addition of protease to broiler diets [ 573, DSM et al. 2012 ]. 

Driving force for implementation 
The  local  availability  of  economical  feed  of  relatively  poor  digestibility  is  a  driving  force. 
Xylanase  enzymes  are  convenient,  most  with  fibre-rich  feed.  The  use  of  enzymes  allows  a 
higher incorporation into the diets of feed materials with lower digestibilities. Therefore, it may 
allow  the  use  of  locally  grown  feed  materials  and  by-products  and,  in  turn,  contribute  to  the 
reduction of costs for the compound feeds. 

Example plants 
This feeding strategy  is already applied in pig and poultry production and can be used  in  any 
production process and does not lead to additional investments. The addition of enzymes in feed 
is done by the feed millers and does not require any specific equipment for farmers. 

Reference literature 
[ 304, Fefana 2010 ] [ 305, Fefana 2010 ] [ 281, France 2010 ] [ 327, Germany 2010 ] [ 478, 
Sieo et al. 2005 ] [ 479, Bedford et al. 2011 ] [ 480, Yu et al. 2007 ] [ 481, Thacker 2005 ] [ 482, 
Cowieson et al. 2005 ] [ 483, Cowieson et al. 2010 ] [ 485, Gutierrez del Alamo et al. 2008 ] 
[ 543, Fefana 2002 ] [ 573, DSM et al. 2012 ] [ 624, IRPP TWG 2013 ] 

256 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

4.3.6.4 

Phytogenic feed additives  

Description 
Phytogenic  feed  additives  are  products  that  are  standardised  for  their  plant-derived  active 
ingredients and are used in animal nutrition mainly with the objective of improving performance 
and  the  health  of  the  animals.  Active  ingredients  from  Oreganum  vulgare,  Piper  Nigrum, 
Syzygium aromaticum, Thymus vulgaris, Yucca schidigera and Quillaja saponaria have proven 
effects on the stabilisation of animals’ intestinal microflora. The specific effects are:  

 

 

 

 

an  antagonistic  activity  to  many  subcultures  of  pathogenic  enterobacteria,  such  as  C. 
perfringens  or  E.  coli,  S.  typhimurium,  L.  monocytogenes,  Y.  enterocolitica  or  of  S. 
aureus; 

improvement of animal metabolism by increased blood circulation (pungent substances); 

reinforcement of the immune system, of the growth and reproductive performance by a 
better permeability of intestinal cell walls; 

inhibition  of  the  activity  of  the  urease  enzyme  and  thus  reduction  of  ammonia 
volatilisation (saponins).  

The standardisation of the active ingredients and dosage recommendations of these additives are 
the  basis  for  achieving  reproducible  results  in  animal  nutrition.  The  leading  substances  are 
defined by product specification. 

Achieved environmental benefits 
Due to the increased secretion of digestive juices, raw protein is increasingly digested in amino 
acids which are absorbed at a greater rate. Furthermore, animals achieve higher rates of growth, 
more  raw  protein  is  used  for  meat  and,  consequently,  reduced  amounts  of  excess  protein  are 
excreted through faeces [ 331, Raumberg 2010 ]. 

Saponins contained in the products reduce the activity of the urease enzyme, which is formed by 
bacteria  in  the  large  intestine  and  which  decomposes  urea  into  ammonia  and  carbon  dioxide. 
The inhibition of activity leads to a lower production of ammonia. 

However,  it  is  also  reported  that  the  consistent  effectiveness  on  ammonia  emissions  remains 
unproven, resulting in uncertainty regarding their performance. The available experiment results 
report  data  concerning  commercial  products  made  from  blends  of  different  phytogenic 
substances. Data on the efficacy of each type and dose of the active compounds contained in the 
commercial  products  and  their  possible  interactions  with  other  feed  ingredients  are  not  yet 
available [ 484, Windisch et al. 2008 ].  

Cross-media effects 
No cross-media effects have been reported. 

Environmental performance and operational data 
In poultry, reductions of indoor ammonia concentrations from 14.4 % to 53.8 % (compared to 
untreated feed) have been reported, along with an improvement in feed conversion of 2 % and 
final body weight of 3.2 % [ 332, Delacon 2010 ] [ 333, Delacon 2010 ]. 

In another study for fattening pigs carried out in Austria, the effectiveness of a phytogenic feed 
additive  on  the  reduction  of  gaseous  emissions  as  well  as  the  effects  on  animal  performance 
were investigated in one trial. The results report the content of nitrogen (both total N and NH4-
N)  in  the  manure  was  reduced  by  60 %  compared  to  that  excreted  by  pigs  that  are  fed  with 
untreated feed, and a consequent decrease in ammonia concentrations in houses of around 38 % 
and 34 % for odours [ 331, Raumberg 2010 ].  

Intensive Rearing of Poultry or Pigs 

257 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Similar results have been reported for the addition of two similar phytogenic additives based on 
ethereal  oils  and  saponins  to  the  feed  of  fattening  pigs,  with  a  reduction  in  the  ammonia 
concentration in the house in the range of 32–38 % [ 458, Veit et al. 2011 ]. However, another 
investigation of fattening pigs in Denmark on the effect of an additive based on a comparable 
active  compound  did  not  show  any  significant  effect  on  ammonia  emissions  [  632,  DAFC 
2010 ]. 

Tests  carried  out  on  lactating  sows  and  piglets  indicate  that  body  weight  loss  is  decreased  in 
sows fed with phytogenic additives compared to sows fed without supplementation. Test results 
vary  from  33 % to 67 %,  depending  on  the  type  of  product.  Also,  the  body  weight  gains  of 
piglets  were  found  to  be  significantly  improved  when  diets  of  lactating  mothers  were 
supplemented from day 90 of gestation to day 25 postpartum [ 455, Männer 2011 ]. 

Technical considerations relevant to applicability  
Only  authorised  feed  additives  according  to  Regulation  (EC)  1831/2003  are  applicable.  No 
particular  management  is  needed,  other  than  mixing  additives  in  feed.  The  technique  is 
generally applicable to both poultry and pigs.  

Economics  
Costs  of  phytogenic  feed  additives  in  broilers  range  between  EUR 0.06  per  place  per  year,  if 
performance  benefits  are  not  accounted  for,  and  EUR -0.05  per  place  per  year  (a  profit),  if 
benefits are taken into account [ 380, Delacon 2011 ]. In pigs, costs range between EUR 2.10 
per place per year, if benefits are not accounted for, and EUR -1.92 per place per year (a profit), 
if benefits are taken into account [ 456, Delacon 2011 ]. 

Driving force for implementation 
The environmental benefits are a consequence of better performances that do not affect either 
slaughter performance or carcass quality. 

Example plants  
In 2010, across the EU, at least 427 million broilers were fed with the addition of one brand of 
natural phytogenic additive, mainly for performance improvement. In particular, about 80 % of 
broilers  in  Czech  Republic  and  60 %  in  the  Netherlands  were  fed  with  supplemented  diets  
[  381,  Delacon  2011  ].  More  than  600  000  fattening  pigs  were  fed  in  2010  with  more  than 
167 000 tonnes of feed with added phytogenic additives [ 457, Delacon 2011 ]. 

Reference literature  
[ 331, Raumberg 2010 ] [ 332, Delacon 2010 ] [ 333, Delacon 2010 ] [ 334, Lipinsky K. 2008 ] 
[ 380, Delacon 2011 ] [ 381, Delacon 2011 ] [ 455, Männer 2011 ] [ 456, Delacon 2011 ] [ 457, 
Delacon 2011 ] [ 458, Veit et al. 2011 ] [ 484, Windisch et al. 2008 ] [ 632, DAFC 2010 ] 

258 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

4.4 

Techniques for the efficient use of water 

Description 
A  reduction  of  water  use  on  farms  can  be  achieved  by  reducing  spillage  when  watering  the 
animals and by reducing all other uses not immediately related to nutritional needs. Sensible use 
of water and reduction of water usage is primarily a matter of good farm management and may 
comprise the following actions: 

 

 

 

 

 

Pre-cleaning (e.g. mechanical dry cleaning) and cleaning animal housing and equipment 
using  high-pressure  cleaners  after  each  production  cycle,  balancing  cleanliness  with 
minimisation of water use.  

Regularly  verifying  the  calibration  and,  if  necessary,  recalibrating  the  drinking-water 
installation to avoid spillages. 

Keeping  a  record  of  water  use  by  metering  the  consumption  (e.g.  every  6  months), 
possibly  differentiating  between  the  physiological  phases  of  the  rearing  cycle  and 
functional  uses  (e.g.  drinking,  washing).  This  procedure  allows  the  establishment  of  a 
water index consumption by animal category. 

Detecting  (e.g.  by  visual  inspection)  and  repairing  leakages  in  the  water  distribution 
circuit. 

Using separately collected uncontaminated rainwater and reusing it for cleaning purposes, 
if it is reasonable for the sanitary implications to do so (see Section 4.15.2.1). 

Achieved environmental benefits 
Reduction of water consumption. 

Cross-media effects 
Typically  in  pig  housing,  the  wash-down  water  enters  the  slurry  system,  which  means  that 
reduced cleaning water usage will lead to thicker slurry; the higher dry matter content will cause 
increased  ammonia  emissions  during  subsequent  slurry  spreading  because  of  the  lower 
infiltration rate into the soil (see Section 4.13.4.1). 

Environmental performance and operational data 
Animal consumption 
Water  provision  always  has  to  satisfy  the  welfare  requirements  set  by  relevant  regulations. 
Reduction of the animals’ water consumption is not considered practical as the animals' need for 
fresh water must not be compromised. The drinking equipment should be selected appropriately 
considering the animals' drinking behaviour.  

For poultry, different types of drinking systems are applied such as (see also Section 2.2.5.3): 

 

 

 

nipple drinkers with or without a drip cup; 

water troughs; 

round drinkers; 

For  pigs,  the  following  types  of  drinking  systems  are  commonly  applied  (see  also 
Section 2.3.3.3): 

 

 

 

 

nipple drinkers with a trough or cup; 

water troughs; 

push-tube drinkers; 

biting drinkers. 

Intensive Rearing of Poultry or Pigs 

259 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.32  shows  the  results  of  six  tests  performed  on  fattening  pigs,  comparing  the  water 
consumption and slurry generation between integrated nipple drinkers in the dry feeding trough 
and  drinkers  separated  from  the  dry  feeder.  Table 4.33  presents  the  results  of  similar  tests 
carried out with gestating sows. 

It can be seen that the total water consumption for separated drinkers is almost double that of 
integrated  nipples,  due  to  water  wasted  by  the  animals;  as  a  consequence,  the  generation  of 
slurry  is  much  greater  too.  The  difference  in  the  growth  rate,  feed  intake  or  feed  conversion 
efficiency of the animals does not appear to be significantly influenced by the drinker designs or 
positions  in  the  pen  and  the  related  increase  in  water  consumption  [  534,  AFBI  2007  ]. 
However,  the  exclusive  use  of  integrated  drinkers  may  not  be  allowed  (e.g.  in  Germany)  
[ 624, IRPP TWG 2013 ]. 

It has been reported that placing drinkers apart, rather than side by side in the pen, leads to a 
reduction in water usage, due to a reduction in swapping between drinkers, especially when low 
flow rates are used [ 534, AFBI 2007 ].  

Table 4.32:  Examples  of  the  effect  of  drinking  equipment  on  the  water  consumption  and  slurry 

generation of fattening pigs 

Water consumption/ 
slurry generation 

Animal  consumption  for 
drinking (water ingested + 
wasted by the animal) 

Water for washing 

Total water consumption 

Integrated nipple drinkers in the 
dry feeder  

Drinkers separated from the dry 
feeder 
Test 1 (1)  Test 2 (2)  Test 3 (2)  Test 4 (3)  Test 5 (3) 

Test 6 (4) 

l/animal/day 

l/animal/day 

6.88 

5.40 

5.97 

13.52 

19.51 

6.14 

0.47 

7.35 

0.29 

5.69 

1.31 

7.28 

0.5 

14.02 

8.98 

0.16 

19.67 

11.80 

2.76 (5) 

8.9 

6.64 

2.70 

3.71 

Slurry generation  
(1) Feed is moistened. 
(2) Feed is not moistened. 
(3) Individual nipple drinker. 
(4) Drinking bowl. 
(5) Extra outside corridors attached to the building were washed daily. 
Source: [ 376, Ferreira et al. 2010 ]  

5.38 

Table 4.33:  Examples  of  the  effect  of  drinking  equipment  on  the  water  consumption  and  slurry 

generation of gestating sows  

Water consumption/slurry 
generation 

Animal consumption for 
drinking (water ingested + 
wasted by the animal) 

Water for washing 

Total water consumption 

Slurry generation  

Vacuum 
trough 
flooding tube 

Drinking 
bowl 

Test 1 
Test 2 
Group housing in pens 

Individual 
nipple 
drinker 

Test 3 

Vacuum 
trough 
flooding 
tube 
Test 4 

Individual housing in stalls 

l/animal/day 

23.99 

0.64 

24.63 

11.51 

9.65 

17.58 

16.34 

2.36 (1) 

12.01 

5.3 

0.26 

17.84 

10.90 

0.24 

16.59 

9.18 

(1) Extra outside corridors attached to the building were washed daily. 
Source: [ 376, Ferreira et al. 2010 ] 

260 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

Feed for pigs can be delivered to the trough in liquid form, therefore involving water addition. 
The volumes of added water depend on many factors and a general rule of quantification is not 
possible. 
As  regards  nutritional  management,  Sections  4.3.2  and  4.3.3  present  the  effects  of  nutritional 
measures  on  water  consumption  and  consequently  on  the  volume  of  slurry  produced.  For 
example,  for  poultry,  it  was  demonstrated  that  a  reduced  protein  level  of  3 percentage  points 
resulted in an 8 % reduction of water intake. 

When  water  is  given  ad  libitum  to  pigs,  they  naturally  reduce  their  water  intake.  Literature 
shows that reduced-protein diets contribute to a decrease in water consumption. The results are 
summarised in Figure 4.5. 

Source: [ 34, Ajinomoto 2000 ] 

Figure 4.5:  Effect of reduced crude protein diets on the intake of water by pigs 

Cleaning water 
Housing  disinfection  is  necessary  to  minimise  infectious  diseases;  provisions  for  regular 
cleaning  and  disinfection  are  also  specified  by  the  welfare  directives  (e.g.  1999/74/EC  and 
2007/43/EC for poultry and 2008/120/EC for pigs). Cleaning water consumption is very much 
related  to  farming  habits  and  housing  architecture  (e.g.  external  pasageways  along  perimeter 
walls  that  need  to  be  frequently  cleaned  to  reduce  the  odour  potential)  [  376,  Ferreira  et  al. 
2010 ]. The use of  authorised cleaning agents and disinfectants can reduce the harmfulness of 
waste water.  

By extensively employing dry cleaning methods with the subsequent use of jet cleaners, water 
consumption and waste water generation can be significantly reduced. The use of high-pressure 
cleaners,  as  well  as  using  hot  water  or  vapour  cleaners  instead  of  cold  water,  reduces  water 
consumption [ 361, France 2010 ]. In particular, the application of warm water can reduce water 
use by 50 %. A tenfold difference in cleaning water use was reported between a Finnish broiler 
farm and a Dutch broiler farm. A steamer, which uses a low water volume, is used widely in 
Finnish farms and may explain the difference [ 624, IRPP TWG 2013 ]. 

From a laying hen farm in Austria operating with an aviary housing system, 40 m3 to 50 m3 of 
waste water is reported to be generated by each house (around 14 500 hens/house) after cleaning 
with high-pressure cleaners without the use of detergents [ 373, UBA Austria 2009 ]. 
Cooling water 

Intensive Rearing of Poultry or Pigs 

261 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

The  water  consumption  and  the  efficiency  of  systems  used  for  temperature  control  in  animal 
houses  in  warm  seasons,  e.g.  fogging,  is  variable  according  to  the  adopted  system.  The  great 
variability of consumption is related to the climatic conditions. 

Air cleaning systems 
Air cleaning systems may require the use of water. From biofilters to biotrickling beds to multi-
stage  scrubbers,  water  is  lost  mainly  by  evaporation  and  also  by  waste.  The  requirements  for 
fresh water range from 5 litres to 7 litres per 1 000 m3 of treated air.  

Metering of water consumption 
The  practice  of  installing  a  metering  device  is  effective  when  a  breakdown  is  obtainable  per 
production  stage.  Different  features  applicable  in  the  production  stages,  namely  the  flooring 
system,  feeding  and  drinking  devices,  ventilation  systems  and  building  characteristics,  can  all 
affect water consumption.  

Technical considerations relevant to applicability 
The needs of the animals for fresh water must always be met.  

A restriction is related to cleaning animal housing and equipment with high-pressure cleaners, 
which is not applicable to poultry plants using dry cleaning systems. 

Economics  
Savings  are  possible  as  a  result  of  conscientious  habits  and  behaviour  and  the  proper 
management of individual specific techniques. A reduction in waste water decreases the volume 
of  liquid  manure  that  will  be  applied  in  agriculture,  thus  reducing  landspreading  costs.  The 
requirements for slurry storage capacity are  reduced, therefore a reduction of construction and 
operating  costs,  associated  with  the  pumping,  transport  or  even  energy  recovery,  may  be 
achieved. 

Driving force for implementation 
Reducing the environmental footprint of the farm and reducing costs are the main driving forces 
for  the  implementation  of  water-saving  measures.  Smaller  volumes  of  waste  water  and  slurry 
result in reduced requirements for slurry storage capacity and lower landspreading costs.  

Example plants 
These measures are widely applied. 

Reference literature 
[ 34, Ajinomoto 2000 ] [ 361, France 2010 ] [ 376, Ferreira et al. 2010 ] [ 373, UBA Austria 
2009 ] [ 534, AFBI 2007 ] [ 624, IRPP TWG 2013 ] 

262 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.5 

Techniques for the efficient use of energy 

4.5.1 

Introduction  

Measures to improve efficiency in the use of energy involve good farming practice, as well as 
the  selection  and  application  of  appropriate  equipment  and  the  proper  design  of  the  animals’ 
housing. Measures taken to reduce the level of energy usage also contribute to a reduction of the 
annual operating costs.  

The opportunities for savings in energy use can be ranked in priority order as reported below: 

 

 

 

 

heating; 

ventilation; 

lighting; 

other consumption (e.g. feed preparation and distribution). 

Factors that affect the indoor temperature are:  

 

 

 

 

 

 

 

 

heat output from the animals, according to their weight and stocking density; 

any heat supply (e.g. gas heater, lamps or heat pads for piglets, input from lighting and 
sun radiation); 

ventilation rate; 

heat absorbed by the indoor air, including by fogging and spraying water; 

heat used to evaporate water from drinkers, feed troughs, spilt water and urine; 

heat loss through walls, roof and floor; 

the presence of trees with a shadowing effect (in warm climates); 

external temperature. 

Control  of  ventilation  rates  is  the  simplest  method  of  controlling  the  indoor  temperature  of 
animal housing. Energy-saving measures are also closely related to the ventilation of livestock 
housing.  The  ventilation  system  should  be  designed  to  remove  the  extra  heat  in  the  warm 
summer  months  at  the  highest  possible  stocking  density,  and  to  also  have  the  capability  to 
provide a minimum ventilation rate in colder winter months at the lowest stocking density. For 
animal  welfare  reasons,  minimum  ventilation  rates  should  be  sufficient  to  provide  fresh  air, 
sufficient humidity and to remove unwanted gases. 

The achieved energy savings are significant when the ventilation rate is properly managed (see 
Section 4.5.4.2.1 and Section 4.5.4.2.2) [ 339, ITAVI 1997 ] [ 349, ITAVI 1998]. For example, 
in pig housing, the yearly average losses associated with the renewal of air represent about 75 % 
of the total heat losses. A bad adjustment of ventilation rates can result in a significant waste of 
energy.  

Electricity demand can be significantly reduced if houses are equipped with natural ventilation, 
rather than with forced ventilation systems. However, this is not always possible or desirable for 
every livestock type and for all farming objectives.  

Another  significant  source  of  energy  consumption  is  the  lighting  of  livestock  houses.  The 
lighting  system  has  to  be  designed  to  meet  the  requirements  of  the  animal  regarding  animal 
welfare and animal health as well as to ensure good working conditions for those working in the 
livestock  house.  To  meet  the  needs  of  the  animals,  a  minimum  intensity  of  light  has  to  be 

Intensive Rearing of Poultry or Pigs 

263 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

ensured, depending on the animal category. Furthermore, a regular change of light and darkness 
has  to  be  provided  for.  Both  factors  significantly  influence  animal  behaviour.  Moreover,  in 
poultry houses, flicker-free lighting is to be provided. 

The energy consumption level is also linked to the high-pressure cleaning devices for livestock 
houses  and  the  removal  of  manure.  The  latter  includes  the  stirring  devices  used  to  mix  the 
manure in the storage tank before spreading. 

4.5.1.1 

General energy-saving measures 

General operational measures to reduce the energy consumption in pig farms are better use of 
the available housing capacity and optimising animal density. 

Where electrical heating and lighting installations are still manually controlled, the adoption of 
simple thermostatic controls with ‘dimmers’ can return considerable energy savings. The use of 
automatically  controlled  management  systems  yields  further  energy  savings.  Investment  costs 
and  cultural  resistance  to  the  use  of  such  equipment  (which  is  often  viewed  as  complex  and 
difficult to operate) are impeding uptake [ 355, Warwick 2007 ]. 

Solar radiation can easily be converted into heat. Both techniques, the ‘indirect’ (panels contain 
hot  water that  transfers  heat  through  a  coil  to  the  fluid  to  be  heated)  and the  ‘direct’  (the  hot 
water from the panel is used directly) are suitable for use in agriculture [ 355, Warwick 2007 ]. 
The  use  of  this  technology  is  increasing  on  farms  as  it  is  cost-effective  in  many  MS  (e.g.  in 
Germany  small  farms  digest  slurry  in  a  profitable  way),  especially  those  with  high  levels  of 
annual  solar  radiation.  In  others,  support  payments  and  lower  capital  costs  resulting  from 
government incentives for renewable heating are motivating adoption [ 624, IRPP TWG 2013 ]. 
However, this technology is unsuitable for use in areas with very hard water. 

The potential use of heat produced by cogeneration of heat and power using biogas and the use 
of other biogenic energy or renewable energy to cover part of the energy demand of the farm are 
also options with positive effects on the environment. 

Another  source  of  electric  energy  consumption  is  represented  by  the  feed  preparation  and 
distribution.  In  the  pig  sector,  energy  use  in  feed  preparation  can  be  reduced  by  about  50 % 
when  meal  is  transferred  mechanically,  rather  than  pneumatically  (blown)  from  the  mill  to 
mixing  or  meal  storage.  Liquid  feed  systems  have  higher  power  requirements  for  mixing  and 
distribution  than  dry  feeding  systems  [  350,  France  2010  ].  An  increase  in  total  electricity 
consumption  of  around  18 %  is  reported  for  an  integrated  farrow-to-finish  farm  using  liquid 
feeding [ 344, ADEME 2008 ]. 

The energy demand can be reduced in hot climates, where there is a need to cool the buildings, 
by trees with a shadowing effect, preferably native species, planted along the long sides of the 
sheds.  Such  trees  also  favour  the  reduction  of  dust  emissions  and  the  dilution  of  odour 
emissions as well as mitigating the impact on the landscape [ 624, IRPP TWG 2013 ]. Potential 
biosecurity risks due to the presence of vegetation near the animal houses (e.g. wild birds may 
be attracted) have to be taken into consideration. 

Detailed  information  on  the  efficient  use  of  energy  is  given  in  the  ENE  BREF  [  703,  COM 
2009 ]. 

4.5.1.2 

Energy management approach 

Establishing an energy action plan is an essential step for the reduction of energy consumption. 
Energy  plans  consider  all  of  the  information  available  to  operators.  Simple  planned  rules,  a 
comparison of performances  with  benchmark figures, and a selection of measures and  actions 

264 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
are  the  key  elements  of  energy  action  plans.  A  timely  correction  of  the  problem  will  lead  to 
energy savings. In general, low-cost and no-cost measures are the first to be implemented.  

Two examples of a benchmark approach applied for a pig farm for comparing performance are 
reported  for  UK  conditions  and  are  presented  below  in  Table 4.34  and  Table 4.35.  If  the 
consumption  is  above  the  typical  figure,  immediate  action  is  required  to  reduce  energy 
consumption. 

Chapter 4 

Table 4.34:  Benchmark figures for energy use in a pig farm 

Energy consumption  
(kWh/pig produced) 

Typical 

Good practice 

Main influence 

Production 
stage 

Farrowing 

Weaning 

Finishing 

Feeding 
system 

8 

9 

10 

3 

Slurry 
management 
Source: [ 356, Carbon Trust 2005 ] 

6 

4 

3 

6 

1 

2 

Use of box creeps with thermostatic control gives the 
lowest  operating  cost.  Underfloor  heating  pads  are 
generally more energy-efficient than infrared bulbs. 
Major  issues  are  the  insulation  of  buildings  (or 
kennels) and, principally, the control of ventilation. 
Efficient  fan  selection,  good  design  of  inlets  and 
outlets  and  system  cleaning  are  the  key  points  to 
minimising energy use. 
Dry  feeding  systems  use  a  small  amount  of  energy 
for  conveying.  Wet  feeding  is  generally  more 
energy-intensive  because  of  the  need  to  mix  and 
pump feed, and pressurise pipework. 
Selection  of  high-efficiency  pumps,  aerators  and 
separators. 

Table 4.35:  Benchmark figures for energy use in a weaning house  

Heating 

Lighting 

Ventilation 

Typical 

Good 
practice 

Typical 

Good 
practice 

Typical 

Good 
practice 

Average annual 
usage (kWh/pig) 
NB: Room measuring 26 m2, 120 pigs housed from 3 to 7 weeks of age, four electric heaters of 1.5 kW, and two 
355 mm fans. 

7.5 

0.8 

0.6 

2 

1 

3 

Source: [ 356, Carbon Trust 2005 ] 

Energy  monitoring  and  understanding  consumption  patterns  are  necessary  before  an  energy 
action plan can be drawn up. Real-time monitoring, often incorporated into ventilation and in-
house  environment  management  systems,  can  provide  necessary  data  in  a  format  in  which 
improvements  and  areas  for  attention  can  be  readily  identified.  The  level  of  data  provided  is 
more comprehensive and of greater value than spot measurements, especially where a number 
of measurements taken simultaneously over a period of time can be viewed together. Measures 
that can be a part of an energy action plan are given below: 

Low-cost or no-cost measures 

 

To take regular meter readings, including to check fuel stock levels, and to record results 
in  a  systematic  way.  This  measure  allows  the  changes  occurring  in  energy  use  to  be 
understood and performances to be compared. As much as possible, collected information 
needs  to  be  related  to  processes,  production  stages,  houses,  and  external  influencing 
parameters (e.g. weather), with sub-metering of separate buildings or processes. 

Intensive Rearing of Poultry or Pigs 

265 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

 

 

 

 

To carry out maintenance and repairs to housing and equipment (e.g. maintain regulating 
flaps, seal buildings to stop draughts). 

Dust  and  corrosion  are  major  problems  for  heaters,  ventilation  components  and 
controllers. All components have to be cleaned at the end of each batch (e.g. cleaning of 
fans and air inlets/outlets). 

To  regularly  check  the  proper  functioning  of  sensors,  e.g.  those  that  are  fitted  for 
temperature, humidity, carbon dioxide and light. 

To  use  information  from  the  control  systems.  A  number  of  monitoring  systems  for 
environmental  and  feed  control  can  be  fitted  with  real-time  devices  to  deliver  recorded 
and live data. Such information may be remotely accessed, e.g. via smartphone devices, 
and/or used at a later date. 

Potential energy savings associated with regular monitoring and benchmarking, are reported to 
be around 10 % of the total energy use, in both the  poultry and pig sectors in the UK, with a 
payback period of 0–2 years [ 355, Warwick 2007 ]. 

Medium- and long-term measures of medium to high cost 

 

 

 

 

 

 

 

To re-insulate buildings. 

To update heating and ventilation controls, e.g. use of improved controlling devices like 
dimmers or thermostatic controls (e.g. for creep heating). 

To install efficient fans and ducts [ 356, Carbon Trust 2005 ]. 

To  consider  high-efficiency  motors,  when  specifying  or  upgrading  motors  on  feed  or 
slurry handling systems, and to consider pumps with variable speed drives when servicing 
a variable demand [ 356, Carbon Trust 2005 ]. 

To  reconfigure  ventilation  to  give  better  control  of  the  minimum  level  [  356,  Carbon 
Trust 2005 ]. 

To install compact fluorescent lighting or high-efficiency tubular fluorescent lighting. 

To achieve a high specific oxygen transfer rate per unit of energy input to the aerator (kg 
O2/kWh), when slurry aeration is applied. 

The most important medium- and long-term actions for energy saving in the intensive rearing 
sector are the following: 

 

 

 

 

 

insulation of the buildings (see Section 4.5.2); 

use of efficient lighting (see Section 4.5.3); 

optimisation of the heating and ventilation in the housing systems (see Section 4.5.4); 

heat recovery (see Section 4.5.5); 

natural ventilation (see Section 4.5.6). 

4.5.2 

Insulation  

Description 
Insulation prevents the passage of heat into or out of the livestock building by interposing non-
heat-conducting material in the walls, floor and roof.  

As humidity is a major cause of deterioration of insulating material, some insulation materials 
are naturally impermeable or provided with an impermeable coating on manufacture to prevent 
moisture  ingress  when  in  use.  Permeable  materials  should  be  provided  with  a  vapour  barrier 

266 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
installed  as  per  the  manufacturer's  instructions  in  order  to  be  protected  against  the  ingress  of 
moisture after installation. Insulation material should also be resistant to wild birds, rodents and 
insects.  

Chapter 4 

The need for insulation also depends on: 

 

 

the  kind  of  ventilation  system;  some  open  climate  housing  systems  do  not  require  any 
insulation at all; 

the insulating properties of the materials used in construction. 

Achieved environmental benefits 
Good  insulation  limits  excessive  energy  losses  through  the  walls,  roof  and  floor;  therefore,  it 
helps to keep buildings warm in winter and cool in summer. When the quality of the insulation 
and  sealing  of the  buildings  is  improved,  there  will  be  substantial  benefits  in  terms  of  energy 
savings for both heating and ventilation. 

Cross-media effects 
Most materials are custom-fitted and non-reusable and hence are disposed of after use. 

Driving force for implementation 
Reducing  the  variability  of  the  indoor  temperature  preserves  or improves  animal  performance 
and  welfare.  Extreme  climatic  conditions  justify  insulation  even  more.  In  littered  housing 
systems,  a  decrease  in  temperature  variations  between  the  ground  and  the  litter  prevents 
condensation. 

4.5.2.1 

Insulation in poultry housing 

Environmental performance and operational data 
Approximately  70 %  of  the  heat losses  occur  from  the  roof,  which  therefore  needs to  be  well 
insulated. Losses depend on the different levels of insulation and the outdoor temperature. 

Sealing is also very important in the control of heating costs, especially in winter and in sites 
exposed to wind. The undesired air intake may come from hatches,  curtains, doors, gates, and 
panel  junctions.  Older  timber  buildings  are  prone  to  leakage  around  structural  joints,  door 
openings and ventilation components. Remedies are quite easy at a reasonable cost. Simple and 
relatively  cheap  adjustments  and  repairs  to  ventilation  flaps,  fan  ducts  and  doors  will  easily 
result in savings in heating costs. 

Common insulation materials in use for livestock housing are shown in Table 4.36, along with 
the average overall heat transfer coefficient (U).  

Table 4.36:  Heat  transfer  coefficients  (U)  for  different  poultry  house  insulation  materials  with  a 

thickness of 2.54 cm  

Insulation type 

Loose-fill fibreglass  
Perlite/vermiculite  
Loose-fill rock wool 
Fibreglass, roll or batt (1) 
Loose-fill cellulose 
Expanded polystyrene board 
Extruded polystyrene board  
Polyisocyanurate board, unfaced  
Spray polyurethane foam  
(1) 'Batt' is a standard commercial way to deliver pre-cut blankets of insulating material. 
Source: [ 459, Overults et al. 2008 ] 

U 
(W/m2 per °C)  
0.44 
0.47 
0.49 
0.56 
0.61 
0.67 
0.84 
1.02 
1.04 

Intensive Rearing of Poultry or Pigs 

267 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

For  north-western  Europe,  U  values  of  0.4  W/m2  per  C  or  better  (lower  U  values)  are 
recommended  for  building  insulation  where  new  poultry  houses  are  planned,  which 
approximates  to  about  50–60  mm  of  extruded  polyurethane  [  95,  UK  2010  ].  In  France,  the 
recommendations  for  the  insulation  of  new  poultry  houses  are  around  0.6  W/m2  per  °C  for 
walls, and 0.35–0.4 W/m2 per °C for roofs. 

In  the  UK,  fibre  wool  insulation  materials  were  widely  used  in  the  past  because  of  their  low 
cost,  but  they  are  being  replaced  by  blown  fibre  and  slab  insulation  products  when  they 
deteriorate [ 355, Warwick 2007 ]. 

A well-insulated poultry housing system allows savings of between 30 % and 50 % of the gas 
consumption,  compared  to  a  poultry  building  with  an  average  degree  of  insulation.  The 
reduction  in energy consumption can range between 2 kg and  4 kg of propane gas per m2  per 
year [ 350, France 2010 ]. 

From Finland, an example of insulation for broiler houses has been reported, with 140 mm of 
mineral  wool  on  vertical walls and  300  mm  of  cellulose  mineral  wool  applied  under  the  roof 
[ 144, Finland 2010 ].  

Table 4.37  shows  the  estimated  thermal  losses  that  may  occur  from  the  roofs  of  laying  hen 
buildings with an area of 1 200 m2. Losses depend on the different levels of insulation and on 
the  outdoor  temperature.  The  thermal  energy  loss  needs  to  be  compensated  by  an  equivalent 
amount  from  propane  gas  heaters.  The  savings  in  gas  requirements  can  be  calculated  by  the 
difference in the amount of gas used. 

Table 4.37:  Estimations  of  heat  losses  during  one  production  cycle  from  roofs  in  laying  hen 

housing, and the requirements for energy replacement (building area: 1 200 m2) 

Outside temperature 

Insulation with 
40 mm of PU foam  
U = 0.780  

Insulation with 
50 mm of PU 
foam  
U = 0.638 

Insulation with 
120 mm of 
fibreglass + 
40 mm of PU 
foam  
U = 0.241 

kWh 

kg of 
propane 

kWh 

kg of 
propane 

kWh 

kg of 
propane 

13 029 

10 967 

972 

1 154 

15 931 

13 410 

4.5 °C 
-4.1 °C to 21.6 °C 
8.5 °C 
-0.1 °C to 25.6 °C 
12.5 °C 
3.9 °C to 29.6 °C 
16.5 °C 
7.9 °C to 33.6 °C 
20.5 °C 
11.9 °C to 37.6 °C 

Average 
Range 
Average 
Range 
Average 
Range 
Average 
Range 
Average 
Range 
NB: PU = Polyurethane; U = Heat transfer coefficient, in W/(m2/°C). 
Source: [ 342, ADEME 2008 ] 

10 889 

5 936 

8 380 

789 

430 

607 

8 905 

6 853 

4 854 

944 

4 925 

375 

795 

4 146 

300 

645 

3 366 

244 

497 

2 591 

188 

1 835 

2 430 

176 

Technical considerations relevant to applicability 
All  new  buildings  can  be  thermally  insulated.  Insulating  older  buildings  may  be  difficult,  as 
fitting  insulated  panels  on  the  inner  surfaces  can  be  hampered  by  pipes,  wires  and  other 
ancillaries. Alternative insulation solutions include filling roof voids with low-density injected 
polyurethane foam, or applying external insulation.  

268 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Insulation of buildings with natural ventilation is less efficient or  is not required. Temperature 
variability within the European Union, but also within a single Member State, may lead to very 
different recommendations concerning the insulation of animal houses. 

The further insulation of existing poorly insulated buildings is assessed on a case-by-case basis 
and according to the state and age of the building at the time of renovation, taking into account 
the  material  choice  and  characteristics  (thermal  conductivity,  thickness  of  the  insulation),  as 
well as the prevailing local climatic conditions. 

Economics 
Costs  for  the  renovation  of  insulation  of  a  typical  poultry  house  of  1 200  m2  are  reported  in 
Table 4.38.  These  costs  generally  vary  according  to  the  type  of  materials  used,  the  type  of 
technique, the dimensions of the building, the number of gates, doors, etc. 

Table 4.38:  Costs  for  the  renovation  of  insulation  and  sealing  in  a  standard  poultry  house  of 

1 200 m2 

Building element 

Cost range 
(EUR/m2)  

FR 
10–25 
Roof 
1–2 
Floors 
15–19 
Side walls 
3–11 
Gables  
1–3 
Gates 
1–2 
Doors 
NB: NI = no information provided. 

UK 
18–25 
4–7 
18–25 
8–15 
NI 
NI 

Source: [ 350, France 2010 ] [ 500, IRPP TWG 2011 ] 

In the UK, the cost for renovation of the insulation in a turkey housing system is reported to be 
around 0.3–0.4 % of the total renovation costs (the approximate total broken-down costs for the 
renovation  are  EUR 6 900/m2  for  roof,  EUR 4 000/m2  for side  walls,  EUR 2 900/m2  for  gables 
with an exchange rate of 1 EUR=0.86 GBP) [ 500, IRPP TWG 2011 ]. 

In the poultry sector in the UK, the potential energy savings achievable with measures related to 
building insulation are reported to be equivalent to 11 % of the total energy use, with a payback 
period of 2 to 5 years [ 355, Warwick 2007 ]. In France, the cost for repairing the sealing of the 
building is reported to be around EUR 1.5 to EUR 2 per m2 [ 342, ADEME 2008 ]. 

Example plants 
Insulation is  widely  applied  to  poultry  housing  systems.  In  France,  poultry  buildings  are  now 
continuously being renovated.  

Reference literature 
[ 95, UK 2010 ] [ 144, Finland 2010 ] [ 339, ITAVI 1997 ] [ 342, ADEME 2008 ] [ 350, France 
2010 ] [ 355, Warwick 2007 ] [ 459, Overults et al. 2008 ] [ 500, IRPP TWG 2011 ]  

4.5.2.1.1 

Heat-reflecting membranes 

Description 
The technique represents a variation of the traditional insulating techniques applied to poultry 
houses.  Walls  and  ceilings  are  lined  on  the  indoor  side  with  laminated  plastic  foils,  to  seal 
poultry housing against air leakage and humidity.  

Intensive Rearing of Poultry or Pigs 

269 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

More than 96 % of the infrared energy from outside can be blocked, allowing the indoor climate 
to  be  kept  under  control  more  easily.  Indoor  energy  is  reflected  back  or  is  not  radiated  away 
from  the  membranes'  surface.  Energy  consumption  for  lighting  can  be  reduced  due  to  the 
reflective properties of the material.  

Achieved environmental benefits 
Better control of indoor temperature and airflow, leading to heating power savings.  

Cross-media effects 
Cleaning  and  disinfection  of  the  housing  are  facilitated,  since  modern  films  can  be  pressure-
washed. Insects and parasite habitats are not favoured. 

Environmental performance and operational data 
Manufacturers claim energy (gas) savings of up to 34 % [ 142, UK 2010 ]. 

Technical considerations relevant to applicability 
This technique can be fitted to new or existing houses. 

Economics 
Costs  per  square  metre  are  about  EUR 33  for  the  insulating  material  and  EUR 9  for  the 
installation [ 500, IRPP TWG 2011 ]. 

Driving force for implementation 
This  solution  is  most  effective  in  the  renovation  of  old  farms,  as  older  timber  buildings  are 
prone to  leakage  around  structural joints,  door  openings  and  components.  Farming  in  warmer 
climates benefits from the improved control over temperature. 

Example plants 
In  the  UK,  a  broiler  farm  of  around  6 000  m2  was  renovated  with  heat-reflecting  membranes.  
[ 142, UK 2010 ]. Farms using heat-reflecting films are well known in the warmest regions of 
around the world. 

Reference literature 
[ 142, UK 2010 ] [ 500, IRPP TWG 2011 ] 

4.5.2.2 

Insulation in pig housing 

Environmental performance and operational data 
Composite panels, containing solid polyurethane insulation, produce good results. These panels 
can be purchased with plastic-coated steel cladding for durability and cleanliness, and can also 
be used as effective structural components (e.g. kennel construction).  

It  has  been  reported  that  in  pig  housing  thermal losses through  walls  account for  25 % of the 
total heat loss [ 351, Marcon M. 2009 ]. 

Recommendations  in  the  UK  are  for  an  insulation  level  of  better  than  0.4W/m2/°C  (60 mm 
polyurethane) [ 356, Carbon Trust 2005 ]. Heat transfer coefficients recommended in France for 
pig  housing  are  presented 
temperatures  
(-5 °C and -15 °C). The lower the U value, the better the building's insulation. 

two  different  extreme 

in  Table 4.39, 

for 

270 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 4.39:  Recommended heat transfer coefficients (U) for two different temperatures, applied in 

France 

Chapter 4 

Type of floor 

Physiological stage 

Solid floor with 
straw 

Partly slatted floor 

Fully slatted floor 

Farrowing 
Post-weaning 
Growing/finishing 
Breeding 
Farrowing 
Post-weaning 
Growing/finishing 
Breeding 
Farrowing 
Post-weaning 
Growing/finishing 
Breeding 

Source: [ 345, France 2010 ] 

Thermal transmission coefficient  
(W/m2/°C) 

Roof 

Walls 

T = -5 °C  T = -15 °C  T = -5 °C  T = -15 °C 

1 

0.6 

1.2–1.5 

0.8 

0.5 

0.8 

0.4 

0.6 

0.35 

0.5 

0.35 

0.4 

0.8 

1.0 

0.6 

0.8 

0.6 

0.7 

0.5 

0.6 

In the UK, fibre wool insulation materials, which were widely used in the past because of their 
low cost, are being replaced by blown fibre and slab insulation products when they deteriorate 
[ 355, Warwick 2007 ]. 

In France, pig houses with insulation rated as good to very good achieve energy savings of up to 
218 kWh/sow/year  or, approximately,  10.4 kWh  per pig  produced,  compared to  buildings  with 
average insulation; the savings account for about 19 % of the total energy consumption  [ 344, 
ADEME 2008 ]. 

Non-insulated  weaner  houses  require  up  to  around  45 %  more  energy  compared  to  well-
insulated houses with 8 cm of insulation in the walls, as can be seen in Table 4.40. In particular, 
the heat consumption of a poorly insulated weaner house (2 cm of insulation) is 20 % higher than 
that  for  the  same  building  with  8  cm  of  insulation  in  good  condition;  this  is  equivalent  to 
10 500 kWh (or EUR 735/year) of potential annual savings [ 350, France 2010 ]. 

Table 4.40:  Effect of insulation thickness on heat consumption in weaner houses 

Thickness of insulation 
0 cm 
Heat consumption (kWh/place)  
121.0 
Heat consumption (kWh/ pig produced) 
18.6 
Difference (1) (%)  
46.6 
(1) The difference in percentage is given as a ratio to the reference of 8 cm of insulation thickness. 
Source: [ 351, Marcon M. 2009 ] 

8 cm 
64.5 
9.9 
Reference 

2 cm 
80.7 
12.4 
20.1 

6 cm 
66.8 
10.3 
3.4 

4 cm 
71.0 
10.9 
9.1 

In  addition,  it  is  also  reported  that  in  weaner  houses  in  France,  where  the  insulation  has 
deteriorated  over  time,  energy  consumption  is  9 %  higher  than  the  average  situation  
[ 344, ADEME 2008 ]. In general, the age of the building reflects the quality of insulation and, 
therefore, the energy consumption of the housing system, as insulation is often based on fibre 
wool-type  materials  subject  to  compression  and  slipping,  with  a  consequent  decrease  of  the 
thickness over time [ 350, France 2010] [ 356, Carbon Trust 2005 ].  

A study in France revealed that in farrow-to-finish houses built before 1992, which correspond 
to  the  development  of  new  building  panels,  the  energy  consumption 
increased  by 
205 kWh/sow/year,  in  comparison  with  houses  built  after  1992  (19 %  increased  consumption 
from  a  value  of  890 kWh/sow/year)  [  344,  ADEME  2008  ].  Another  study  showed  that  by 

Intensive Rearing of Poultry or Pigs 

271 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

adding 1 cm of insulation (on the ceiling and the walls), in a weaners' building of 250 places, 
the energy consumption for heating can be reduced by 11 % to 18 % (for a minimum airflow at 
the beginning of the batch of 3 m3/h/animal up to 7 m3/h/animal, respectively) (See Table 4.44)  
[ 350, France 2010 ]. The insulation of a partly slatted floor is only installed in the solid part. 

Technical considerations relevant to applicability 
All  new  buildings  can  be  thermally  insulated.  Insulation  may  not  be  applicable  to  existing 
buildings due to structural restrictions. 

Insulation of buildings with natural ventilation is less efficient or is not required. Temperature 
variability within the European Union, but also within a single Member State, may lead to very 
different recommendations concerning the insulation of animal houses. 

The further insulation of existing poorly insulated buildings is assessed on a case-by-case basis, 
at  the  time  of  renovation,  taking  into  account  the  material  choice  and  characteristics  (thermal 
conductivity, thickness of the insulation), as well as the prevailing local climatic conditions.  

Economics 
Investment  costs  for  the  renovation  of  the  insulation  in  pig  housing  are  extremely  variable, 
depending on the age of the building, its maintenance and dimensions. 

The application of a layer of 3–5 cm of standard polyurethane foam for a renovation of a pig 
house  might  cost  EUR 18–35/m2.  The  savings  achievable  by  increasing  the  insulation  from 
2 cm to 8 cm in a weaners' house are equivalent to EUR 0.01 per kg of pig produced. 

Potential  energy  savings,  achievable  with  measures  related  to  building  insulation,  have  been 
reported  in  the  UK  for  the  pig  sector  as  equivalent  to  10 %  of  the  total  energy  use,  with  a 
payback period of 2 to 5 years [ 355, Warwick 2007 ].  

Example plants 
Insulation is widely applied. 

Reference literature 
[ 344, ADEME 2008 ] [ 345, France 2010 ] [ 350, France 2010 ] [ 351, Marcon M. 2009 ] [ 355, 
Warwick 2007 ] [ 356, Carbon Trust 2005 ] 

4.5.3 

Low-energy lighting  

Description 
General measures applicable to save energy for lighting are: 

 

 

 

 

 

 

272 

to  replace  conventional  tungsten  incandescent  bulbs,  still  in  use,  with  more  energy-
efficient lights, such as fluorescent, sodium and LED lights (see Table 4.41); 

to use dimmers for adjusting artificial lighting; 

to adopt lighting controls using sensors or room entry switches; 

to apply lighting schemes, for example using intermittent lighting of one period of light to 
three  periods  of  darkness  instead  of  24  hours  of  light  per  day  reduces  the  amount  of 
electricity used by 30–75 % [ 500, IRPP TWG 2011 ]; 

to allow more natural light to enter, e.g. by the installation of vents or roof windows; 

to adopt photoelectric cells to turn artificial lights on, in particular in the poultry sector. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Incandescent light bulbs have been removed from the European market. From September 2011 
onwards, incandescent bulbs of over 60 watts were withdrawn from the market. By 1 September 
2012, all incandescent light bulbs over 7 watts were withdrawn.  
Fluorescent lights (tubular compact shape) can be applied in combination with a device to adjust 
the frequency of microflashes (> 280 000), so the animals will not be able to register the rapid 
fluctuations typical of this light. 

Savings in electricity consumption, associated with the use of artificial lighting, can be foreseen 
at  the  time  of  planning  a  new  house  or  a  complete  rebuild  of  an  existing  house,  by  simply 
allowing more natural light to enter, though avoiding direct radiation (by appropriate placement 
of films or sun visors). 

The  principal  lighting  sources  that  are  available  for  use  in  animal  housing  are  given  in 
Table 4.41. 

Table 4.41:  Principal lighting sources for animal houses  

Type of 
lamp 

Luminosity 
(Lm) 

Power 
(W) 

NI 

13–150 

Incandescent  220–1 420  25–100 
High-
efficiency 
halogen 
Compact 
fluorescent 
T8 
fluorescent 
tube 

1 350–
7 000 

100–1 800 

14–80 

3–23 

Luminous 
efficacy 
(Lm/W) 

Durability 
(hours) 

10–15 

1 000 

15–24 

20–32 

44–70 

2 000–
4 000 

40 000–
15 000 

4 000–
15 000 

Energy saving 
in comparison 
to incandescent 
lamp 
(%) 
0 

30–40 

Relative 
cost 

Recyclable 

€ 

€€ 

No 

No 

80 

€€ - €€€ 

Yes 

30–40 

€€ 

Yes 

Induction 

Metal halide 
(iodine) 
High-
pressure 
sodium 

LED high-
power 

35 000–
12 000 
5 900–
189 000 

1 300–
130 000 

12–100 

70–
2 000 

35–
1 000 

0.2–5 
(each) 
LED) 

55–165 

NI 

60 000 

70–80 

50–80 

50–150 

10 000–
18 000 

120 000–
25 000 

35–45 

60–75 

€€€ 

€€€ 

€€€ - 
€€€€ 

Yes 

Yes 

Yes 

60–250 

50 000 

80–90 

€€€€ 

Yes 

NB: €€€€ highest cost – € lowest cost; NI = no information provided. 
Source: [ 552, IDELE 2012 ] 

Achieved environmental benefits 
Reduced electric energy consumption and easier disposal of waste light bulbs due to the absence 
of mercury. 

Cross-media effects 
An increase in the use of natural light needs to be balanced with the possible heat losses through 
windows or openings, and should also be considered in the context of the geographical climatic 
conditions, with special focus on the duration of light per day [ 500, IRPP TWG 2011 ].  

Reference literature 
[ 500, IRPP TWG 2011 ] [ 552, IDELE 2012 ] 

Intensive Rearing of Poultry or Pigs 

273 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.5.3.1 

Lighting in poultry housing 

Achieved environmental benefits 
The  use  of  a  red  light  during  rest  time  has  been  shown  to  have  a  positive  effect  on  dust 
emissions  in  broiler  housing.  The  light  is  visible  to  chickens  that  are  less  active  [  463,  UR 
Wageningen 2010 ]. 

Cross-media effects 
The number of hours of light and the intensity of the light can cause cannibalistic behaviour in 
the  birds  (pecking,  tearing  and  consuming  of  skin,  tissue,  etc.)  [  500,  IRPP  TWG  2011  ]. 
Natural light may increase scratches and pecking [ 624, IRPP TWG 2013 ]. 

Environmental performance and operational data 
See the general data of Table 4.41. 

New compact fluorescent lamps last longer and are becoming cheaper. Low-energy fluorescent 
tabular  lamps,  with  high-frequency  electronic  control  equipment,  can  be  used.  They  allow 
flicker-free dimming down to a very low output. For lighting outside buildings, it is better to use 
low-energy  discharge  lamps  (high-pressure  sodium  or  metal  halide  lamps)  as  these  are  much 
cheaper to operate than the commonly used tungsten halogen lamps. 

Tungsten  halogen  lamps  are  better  used  where  they  can  be  controlled  by  passive  infrared 
sensors and where they are expected to have very short operating times [ 95, UK 2010 ]. 

LED lighting allows a lower energy consumption and heat output, the opportunity to dim bulbs 
without  affecting  the  spectrum,  and  a  minimal  flicker  (unlike  fluorescent  lighting).  LED 
technology  offers  solutions  specifically  tailored  to  the  spectral  sensitivity  of  poultry  
[  422,  Taylor  N.  2010  ].  Chickens  require  a  more  specific type  of  light  with  a preference  for 
blue and green compared to red [ 461, Glo 2010 ]. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique.  

Economics 
In the replacement of different types of lights, annual operating costs (including amortisation of 
a new installation) depend on electricity prices as well as on the number of replacements that 
need to be purchased. 

The  indicative  investment  costs  required  to  install  an  entire  low-energy  lighting  system 
(including  installation,  accessories,  wiring  and  protection)  in  a  poultry  house  of  1 200  m2  is 
estimated to be between EUR 7.5 and EUR 10 per m2 [ 350, France 2010 ]. 

Driving force for implementation 
The driving force is savings in electricity costs.  

LED lights in poultry flocks reduce aggression. In poultry-specific LED lighting, the red end of 
the  spectrum  is  decreased,  in  order  to  favour  poultry  behaviour  and  welfare  [  422,  Taylor  N. 
2010 ] [ 461, Glo 2010 ]. 

Example plants 
The technique is generally applied. Commercial LED equipment is on the European market and 
being adopted by poultry farmers.  

Reference literature 
[  95,  UK  2010  ]  [  350,  France  2010  ]  [  422,  Taylor  N.  2010  ]  [  461,  Glo  2010  ]  [  463, 
Wageningen UR 2010 ] [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ] 

274 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.5.3.2 

Lighting in pig housing 

Environmental performance and operational data  
Table 4.41 provides general data on types of lighting equipment.  

Pigs seem to rely more on olfaction and audition than on vision. In practice, pigs have a poor 
colour  perception  and  are  unable  to  perceive  the  flicker  of  normally  functioning  fluorescent 
lights.  In  general,  fluorescent  lights  have  a  higher  light  capacity  per  energy  unit  (lumen/watt) 
than  conventional  bulbs.  The  power  rating  and  the  number  of  hours  used  will  determine  the 
annual energy use. The replacement of filament bulbs by compact fluorescent lights could save 
up to 75–80 % of the energy used.  

Compact  fluorescent  lamps  cannot  be  dimmed.  T8  (1.25  inch)  fluorescent  tubes  are  more 
efficient than T12 (1.5 inch) tubes. In fluorescent tabular lamps, electronic control gives a 20 % 
energy  saving  over  conventional  ballasts,  and  extends  lamp  life  by  50 %  [  356, Carbon Trust 
2005  ].  As  two  different  levels  of  lighting  are  generally  required  (depending  on  whether  the 
operator  is  present in  the  room  or  not),  energy-efficient  lighting  can  be split into  two  circuits 
[ 356, Carbon Trust 2005 ]: 

 

 

For  high-level  lighting,  fluorescent  tabular  (strip)  lamps  with  T8  tubes  and  electronic 
control will give the best energy efficiency and most even light distribution; 

For low-level lighting in smaller rooms, a small number of compact fluorescent lamps is a 
good solution; alternatively fluorescent tabular (strip) lamps with dimmable ballasts can 
be used to allow the lights to be turned down during stock lighting periods. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

In  general,  the  use  of  lighting  controls (photoelectric cells)  is  not  commonly  applied;  lighting 
control  is  generally  confined  to  manual  switching.  Proximity  sensors  are  better  used  for 
technical areas or corridors than for areas with animals [ 500, IRPP TWG 2011 ].  

Economics 
Annual operating costs associated with the replacement of lights depend on electricity prices as 
well as on the number of replacements that need to be purchased. 

In  general,  the  necessary  investment  to  equip  a  pig  farm  with  low-energy  lighting  has  to  be 
studied on a case-by-case basis. The cost will depend on the farm size and the organisation of 
the building (use of natural light, size of the rooms, corridor organisation, etc.) 

Driving force for implementation 
One of the driving forces is savings in electricity costs. The manufacturers of LEDs also claim 
an improved physical performance in the animals. 

Example plants 
The technique is generally applied. Commercial LED equipment is on the European market and 
is being adopted by pig farmers.  

Reference literature 
[ 356, Carbon Trust 2005 ] [ 500, IRPP TWG 2011 ]  

Intensive Rearing of Poultry or Pigs 

275 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.5.4 

Optimisation of heating/cooling and ventilation systems and 
management in poultry and pig farms 

Thermal  losses  from  animal  housing  may  be  reduced  by  the  optimised  and  well-balanced 
management of heating and ventilation, adapted to the physiological needs of the animals. This 
is achieved  by  optimising the  minimum  ventilation rates  (manual  or  automated  management), 
taking into account the minimum levels required for the animal performance and welfare (i.e. 
fresh  air  supply,  sufficient  humidity,  removal  of  undesirable  gases).  Bad  management  of 
ventilation can have  a negative impact on  the growth performance of the animals and thus on 
the economics of the farm.  

An overview of the main measures for minimising energy consumption through optimising the 
heating and ventilation in poultry and pig farms is given below. 

4.5.4.1 

Efficient use of energy for heating 

4.5.4.1.1 

General measures for the efficient use of energy for heating in poultry 
farms 

A  building  where  meat  poultry  is  reared  has  specific  requirements  for  heating  (e.g.  32 °C  for 
day-old chicks) and for cooling (e.g. 20 °C for bird stocking densities of up to 34 kg per m2 of 
floor area). All buildings are fitted with large heating and ventilation systems to maintain these 
conditions [ 95, UK 2010 ].  

A considerable reduction in energy consumption for heating and ventilation can be achieved by 
paying attention to the points given below: 

 

 

 

 

Energy  consumption  can  be  reduced  by  separating  heated  spaces  from  other  spaces,  by 
limiting their size.  

In the heated space, energy use can be reduced by correct regulation of equipment and by 
an  even  distribution  of  warm  air  through  the  housing,  i.e.  by  spatially  distributing  the 
heating  equipment  adequately.  An  equal  distribution  would  also  prevent  a  sensor  from 
being located within a cold or hot spot in the housing, which would unnecessarily activate 
the heating or ventilation system. 

Control  sensors  need  to  be  regularly  checked  and  kept  clean  to  correctly  detect  the 
temperature at the stock level (maximum one metre high). 

For poultry farms equipped with gas heaters, regular maintenance of heating devices and 
replacement  of  worn-out  parts  (every  5  to  6  years)  allow  for  better  combustion  and 
savings  in  energy.  Equipment  should  run  at  correct  (full)  power,  since  the  temperature 
decrease is not proportional to the reduction of power. 

  Warm air from just below the roof level can be circulated down to floor level. Airflow 
directed towards animals should be of a sufficiently low velocity to avoid compromising 
the animal welfare. 

 

 

 

276 

Over-ventilating  heated  poultry  meat  housing  during  cold  weather  can  dramatically 
increase heating costs. As small errors in the winter minimum ventilation rate can have a 
big  impact  on  operating  costs  for  heating,  it  is  essential  to  invest  in  good  control 
equipment  and  ventilation  systems,  which  are  capable  of  delivering  low-level  and 
accurate amounts of ventilation. 

Control  of  minimum  ventilation  also  requires  well-sealed  buildings.  Cracks  and  open 
seams in the housing construction should be repaired. 

Placing ventilation vents low down on the walls (as heat tends to rise) will reduce heat 
losses. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 

 

 

 

 

 

 

 

 

 

Chapter 4 

Further insulation with loose material on the floor (e.g. sand used in the Netherlands), i.e. 
on  top  of  the  built-in  insulation  of  the  floor,  will  reduce  heat  losses  and  therefore  fuel 
input (especially with high groundwater levels). 

In  a  laying  hen  house,  heat  may  be  recovered  with  a  heat  exchanger  between  the 
incoming and outgoing air (see Section 4.5.5). This type of system is used to warm the air 
to dry the manure on the belts under the cages, to reduce the emissions of ammonia. 

If heating is required to maintain the moisture content of litter, all sources of unnecessary 
wetness should be rectified (e.g. spillage from drinkers). 

Fans that operate intermittently should be fitted with back-draught shutters to reduce heat 
loss. 

Concentrating chicks at the start of the cycle: barriers can be placed in the house to avoid 
the chicks spreading everywhere in the house to keep them together and warm. 

A good evacuation of rainfall around the building prevents water from rising indoors by 
capillary  action  (especially  where  floors  are  not  made  of  concrete), requiring  additional 
energy for heating. 

The  use  of  heat  exchangers  to  recover  heat  is  another  solution  to  minimise  energy 
consumption. 

Optimising  air  homogenisation  and  air  circuits  is  another  option.  In  buildings  with 
mechanical  ventilation,  the  aim  is  to  heat  the  entering  air  by  forcing  it,  following  the 
under-roof  route,  inside  the  room.  Meanwhile,  in  buildings  with  natural  ventilation  the 
homogenisation is achieved using a mixing fan, which will allow the warm air from the 
ridge of the building to be pulled down towards the animal living area, without generating 
excessive airflow. 

Many control systems used in poultry housing often rely on a single sensor to operate the 
complete heating or ventilation system for the whole house. Better systems have multiple 
electronic sensors, positioned just above bird height, to give a representative reading of 
the true temperature. Control systems which give good feedback in terms of temperature 
records,  as  well  as  information  on  the  historical  operation  of  fans  and  heaters,  help  to 
manage energy more effectively. 

Buildings fitted with separate thermostats for heating and ventilation run the risk of the 
two  systems  operating  at  the  same  time  and,  therefore,  wasting  energy.  Where  cooling 
fans  and  heaters  are  installed  within  the  same  building,  interlocked  controls  should  be 
used  to  stop  the  operation  of  heating  when  fans  are  running  at  anything  above  their 
minimum ventilation setting.  

4.5.4.1.2 

General measures for the efficient use of energy for heating in pig farms 

The rate of air exchange is primarily responsible for the energy requirements for heating. That is 
why  it  is  crucial  to  control  the  flow  of  air,  in  particular  the  minimum  flow  rate.  Heating 
accounts for 46 % of total energy consumption for an integrated breeding-to-fattening farm and 
for  approximately  80 %  of  the  total  energy  consumption  for  the  farrowing  and  post-weaning 
stages. Optimisation of the balance of heating and ventilation, adapting it to the animals' needs, 
may reduce energy consumption by up to 50 %. 

Some possibilities for reducing energy consumption for heating are: 

 

 

 

reducing  ventilation,  taking  into  account  the  minimum  levels  required  for  animal 
performance and welfare; 

lowering the temperature as far as animal welfare and production allow; 

insulating the building, particularly lagging the heating pipes; 

Intensive Rearing of Poultry or Pigs 

277 

 
 
 
 
 
 
Chapter 4 

 

 

 

 

 

 

optimising the position and adjustment of heating equipment; 

considering heat recovery; 

considering using high-efficiency boilers in new housing systems; 

using enclosed creep areas; 

checking the calibration of temperature sensors regularly; 

natural ventilation (see Section 4.5.6). 

In  the  operation  of  biogas  facilities,  the  energy  generated  (power  and  heat)  from  the  biogas 
produced can be used (recovered) to replace that generated by fossil fuels. However, only post-
weaning houses are capable of utilising the heating energy throughout the year.  

Some examples of operational measures applied in the pig sector for reducing heat requirements 
and/or achieving energy savings are indicated below. 

In sow housing, a zone heating system is installed for heating the piglet creep area. Hot water 
floor  heating  is  more  energy-efficient  (if  the  hot  water  is  from  a  renewable  energy  heated 
source) than an electric floor heating system or the use of infrared radiators.  

For houses with natural ventilation, the lying area is located in heat-insulated boxes (‘box and 
bed stalls’) to avoid the need for additional heating. 

Electric  floor  heating  with  warming  plates  allows  for  a  reduction  in  energy  consumption  by 
30 %,  compared  to  over-floor  heating;  however,  the  technique  still  remains  expensive  for 
existing  housing  systems,  and  will  usually  only  be  applied  on  the  occasion  of  a  major 
renovation. The application of electric floor heating, in combination with optimised ventilation, 
is quite expensive in the retrofit of existing housing systems.  

With the use of kennels for piglets, the different thermal needs of sows and newborn piglets can 
be met simultaneously, providing a temperature of around 30 °C for piglets, and not over 24 °C 
for sows [350, France 2010]. 

In  post-weaning,  adjustable infrared  heaters  are  more  energy-efficient  than  standard  heaters. 
Moreover,  the  positioning  and  the  calibration  of  the  temperature  sensor  is  essential.  A  single 
probe, for simultaneously controlling the ventilation and heating, should be applied.  

4.5.4.1.3 

Gas-fired infrared heaters and air blowers 

Description 
Propane-  or  natural-gas-fired  infrared  heating  systems  generate  electromagnetic  (infrared) 
radiation,  which  is  transferred  to  a  body  with  a  lower  temperature  where  it  is  converted  into 
heat. In animal houses, a ceiling-hung gas-fired heater transfers energy directly to the  animals 
and the floor, instead of heating the surrounding air. Eventually, heat is stored in slab floors and 
the air is secondarily  heated as it passes over the warm concrete. In a  forced air heater, air is 
drawn through the heater and blown into the house. The circulating heated air transfers heat to 
whatever it flows over, including the animals and the litter, provided that air circulation in the 
house is good.  

Achieved environmental benefits 
The use of gas-fired radiant heaters provides concentrated heat to the animals without having to 
heat the rest of the house; therefore, fuel savings are achieved. 

278 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
Fossil fuel (propane, natural gas) is a non-renewable energy. Safety considerations  have to be 
implemented with the use of ceiling-hung gas-fired radiant heaters.  

Environmental performance and operational data 
Modulated  radiant  heaters  are  much  more  efficient  in  terms  of  gas  consumption  than 
conventional non-modulated heaters. In modulated heaters, the gas flow and the combustion air 
are continuously adjusted, allowing gas savings of around 20–40 % compared to conventional 
systems, which corresponds to 1.4–3.1 kg of gas/m2 per year. 

Modulated  radiant  heaters,  with  automatic  regulation,  can  operate  gradually  over  a  pressure 
range between 20 mbar and 1 400 mbar, showing a better performance in comparison with two-
stage radiant heaters working at two pressure levels between 50 mbar and 150 mbar.  

In  well-insulated  and  sealed  buildings,  warm  air  generators  (blowers)  are  more  effective  than 
gas-fired infrared heaters, but the latter are more appropriate in larger buildings that are not well 
insulated,  in  particular  for  the  production  of  turkeys.  Warm  air  blowers  require  electricity  to 
induce the air movement; meanwhile, gas-fired radiant heaters can, in principle, operate without 
electricity and, in some cases, be controlled manually.  

Technical considerations relevant to applicability 
This technique is generally applicable as long as a gas supply is available on farm. It is mostly 
employed  in  poultry  rearing  but  can  also  be  used  for  in  pig  houses,  where  it  may  represent a 
good alternative where insufficient electric power is available.  

Economics 
Indicative investment costs for the equipment are EUR 4–9.2/m2 (tax excluded) for a gas-fired 
infrared heater with a modulated gas flow and EUR 3.4–11 per m2 for gas hot air blowers. In the 
case where a warm water heating circuit is also installed, the price for the related hot air blowers 
lies between EUR 5.8 and EUR 6.7 per m2. These prices are evaluated for a building of 1 200 m2 
and vary according to the type and the number of pieces of equipment installed, as well as to the 
selected options. 

The maintenance cost for radiant heaters, by periodic replacement of worn parts, is reported to 
be about EUR 100 (every 6 to 10 years) for a 1 200 m2 house.  

Driving force for implementation 
The difference in prices for electricity and gas can play a role in the choice of this technique. 
Gas heating may be the alternative for farms that are not connected to the electrical network.  

Example plants 
The technique is widely applied. 

Reference literature 
[ 339, ITAVI 1997 ] [ 342, ADEME 2008 ] [ 349, ITAVI 1998 ] [350, France 2010 ] 

4.5.4.1.4 

Wood- and biomass-fired boilers 

Description 
Standard  boilers  or  combined  heat  and  power  systems  are  fuelled  with  wood  and/or  other 
biomass  for  heating  up  water.  Heat  exchangers  serve  the  heating  circuit,  where  hot  water  is 
produced and circulated in the building to warm it up (e.g. by means of fins, hot plates).  

Straw can be also used in broiler farms as a fuel [ 144, Finland 2010 ].  

Intensive Rearing of Poultry or Pigs 

279 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

In  Figure 4.6,  a  heating  system  for  a  broiler  house  in  Spain  based  on  a  biomass  burner  is 
illustrated.  

Source: [ 372, Spain 2013 ] 

Figure 4.6:  Schematic representation of feed, water and heat distribution by a biomass burner in 

a broiler house 

Achieved environmental benefits 
Wood use has a neutral impact on the greenhouse effect. The economic value is given by adding 
value to available copses, farm woodland and agricultural residues that are not fully exploited, 
or by cropped biomass (e.g. miscanthus). 

Cross-media effects 
When peat is used as fuel, the indirect environmental effects of peat exploitation (emissions of 
CH4 and N2O when peat is mined) should be taken into account. 

Use of wood and other biomass to fire boilers for heating up water may result in dust emissions 
in  the  air  and  should  be  also  taken  into  account,  especially  in  areas  with  problems  of 
overcoming air quality limits. A high demand for biomass may cause overexploitation of forests 
or excessive land use for biomass crops [ 624, IRPP TWG 2013 ]. 

Environmental performance and operational data 
This system allows for efficient heating and good temperature control. Heat is well distributed 
in the building. This heating system is profitable when heat needs are large and stable, as is the 

280 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
case with multiple houses or users. An example is reported in Table 4.42 of a mixed poultry and 
dairy farm combined with the farmer’s house. 

Chapter 4 

Table 4.42:  Example  of  a  mixed  farm  benefitting  from  warm  water  heating  served  by  a  wood 

boiler 

Heated houses 

3 000 m2 poultry housing + 230 calf places  
1 800 m2 poultry housing + farmer's house 
600 m2 poultry housing + farmer's house + heated water 
in the milking room 
Source: [ 346, CA Bretagne 2009 ] 

Boiler power 

300 kW 
240 kW 
100 kW or 60 kW + 8 
supplementary infrared heaters  

Information on the quality of fuel (size of particles, humidity, biomass species, absence of wood 
treated with chemicals) is essential for the proper operation of wood and biomass boilers [ 345, 
France 2010 ]. 

Technical considerations relevant to applicability 
Boilers need to be close to animal  housing; otherwise, expensive underground district heating 
pipe networks are needed which could be justified in cases of a high heat demand throughout 
the  year.  Thus,  optimal  planning  of  the  system  is  necessary.  Biomass  should  also  be  readily 
available  [  624,  IRPP  TWG  2013  ].  In  the  pig  sector,  only  pig  nurseries  are  likely  to  use  the 
heating energy throughout the year [ 350, France 2010 ]. 

Economics  
Wood is less expensive than fossil fuels and its price is more stable.  

Poultry farms 
In  France,  the  investment  cost  for  a  wood-fired  boiler  of  240 kW  of  power  is  around 
EUR 90 000 (installation in  2006). This boiler  consumes  110  tonnes  of  wood  per  year from  a 
nearby sawmill and supplies heat to a broiler house of 1 200 m2 and a turkey house of 600 m2. In 
France,  this  investment  may  be  subsidised  for  about  40–50 %,  in  which  case  the  return  on 
investment is around 7 years. Without subsidies, the return on investment would have increased 
by another 3.5 years [ 346, CA Bretagne 2009 ]. 

Pig farms 
For a pig  house of 3 300 m2 (approximately 220 sows), 85 kW of power are needed at a total 
cost  of  EUR 400  per  installed  kW  (except  the  equipment  for  the  hot  water  circuit).  The 
requirement for wood would be around 45 tonnes per year, which is covered by the utilisation of 
9–14 km of copse hedges. 

Driving force for implementation 
The economic value is supplemented by the use of available copse and secondary sources that 
are not otherwise fully exploited, e.g. wood resources produced on the farm. 

Example plants 
In France, about 15 poultry farms are already equipped with biomass boilers. 

Reference literature 
[  144,  Finland  2010  ]  [  345,  France  2010  ]  [  346,  CA  Bretagne  2009  ]  [  350,  France  2010  ] 
[ 372, Spain 2013 ] [ 624, IRPP TWG 2013 ] 

Intensive Rearing of Poultry or Pigs 

281 

 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
Chapter 4 

4.5.4.2 

Efficient use of energy for ventilation  

4.5.4.2.1 

Management of ventilation in poultry houses 

Ventilation  is  one  of  the  main  sources  of  energy  consumption  in  the  poultry  sector;  thus,  the 
management of air circulation in the housing systems is important for controlling energy costs.  

For animal welfare reasons, minimum  ventilation rates should  always  be sufficient to provide 
fresh air, oxygen and sufficient humidity and to remove unwanted gases. General measures to 
reduce electricity for ventilation use are given below [ 95, UK 2010 ]: 

 

 

 

 

 

 

 

 

 

Select the correct type of fans and consider their position in the building. 

Install fans with a low energy use per m3 of air. 

Use the fans efficiently, e.g. operating one fan  at full capacity is more economical than 
operating two at half their capacity. 

Maintain and keep fans and controlling devices clean. 

Select  the  appropriate  size  and  shape  of  air  ducts  and  preserve  internal  smoothness,  in 
order to maintain maximum air throughput.  

Consider new plastic conical profile fan ducts. 

Ensure  that  ventilation  cowls  have  smooth,  slow  internal  bends  to  avoid  restricting 
airflow. 

Use adjustable flap windows to optimise the ventilation needs. 

Use a variable speed drive for three-phase electric motors. Reducing the speed of the fan, 
by tailoring the speed to the exact requirement at any time, may allow significant energy 
savings (about 20 % and up to 50 %). 

Optimisation of energy consumption can be assisted by the use of well-sited, fixed single-speed 
fans.  Additional  controls  give  the  possibility  to  obtain  an  airflow  and  speed  that  match  the 
variable needs for  different ages, animal categories, stocking densities and climatic conditions  
[ 339, ITAVI 1997 ] [ 342, ADEME 2008 ] [ 349, ITAVI 1998 ] [ 355, Warwick 2007 ]. 

4.5.4.2.1.1 

Circulating fans 

Description 
Circulating fans homogenise the speed of airflow at the level of animals without increasing the 
volume of air supplied by the central ventilation. Several types of circulating fans can be used: 
horizontal,  vertical,  or  oscillating  (sweeping).  The  description  of  circulating  fans  in  vertical 
shafts aiming to dry litter is given in Section 4.6.4.2.1.  

Fans are mainly used in meat poultry housing during summer, at the last stage of production. 
The  airflow  cools  the  birds  by  increasing  their  heat  loss  through  convection  [  350,  France 
2010 ]. 

Achieved environmental benefits 
Consumption  of  energy  can  be  reduced  as  the  ventilation  system  does  not  have  to  operate  at 
maximum capacity when the objective is to cool the animals. Circulating fans do not necessarily 
decrease their net energy consumption when they direct warm air to litter. 

In  the  Netherlands,  circulating  fans  in  vertical  shafts  are  integrated  into  litter-based  housing 
systems to reduce ammonia emissions by drying the litter. Details on this technique are given in 
Section 4.6.4.2.1. 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
Dust problems may arise. 

Environmental performance and operational data 
Circulating fans are placed at approximately 1  m  above the litter and achieve air speeds of at 
least 0.8 m/s to every point of the living area, given that the recommended air speed is 1 m/s. 
According  to  the  climatic  conditions,  8  to  12  circulating  fans  with  a  capacity  of  15 000–
20 000 m3/h are needed for every 1 000 m2 [ 350, France 2010 ]. 

Technical considerations relevant to applicability 
Circulating fans cannot be installed where there are many obstacles in the buildings that could 
affect their efficiency or where the movement of people or nearby receptors may limit their use.  

Driving force for implementation 
Depending on the price of electricity, economic savings in heating may be higher than the costs 
induced by the electricity consumption of circulating fans. 

Economics 
Investment costs for the installation of vertical circulating fans with a capacity of 20 000 m3/h at 
15-metre  intervals  along  the  length  of  the  house  and  2-metre  intervals  along  the  width  are 
estimated at EUR 5/m2 [ 350, France 2010 ]. 

Example plants 
In France, 10 % of poultry buildings are equipped with circulating fans. 

Reference literature 
[ 339, ITAVI 1997 ] [ 349, ITAVI 1998 ] [ 350, France 2010 ] [ 354, ITAVI 2004 ] 

4.5.4.2.1.2 

Circulating fans in combination with heat exchangers 

Description 
This technique is fully described in Section 4.6.4.2.2, as it forms part of an integrated housing 
system.  The  technique  consists  of  heating  and  drying  the  litter  by  the  combined  use  of  heat 
exchangers  and  ventilators.  Incoming  air  is  warmed  up  in  a  heat  exchanger  using  the  heat 
recovered from the indoor air. The ventilators spread the warm air equally over the litter. 

Achieved environmental benefits  
The reduction of energy requirements is achieved by means of heat exchangers. An additional 
environmental advantage consists of ammonia emissions reduction, achieved by the use of the 
combined system (heat recovery and circulating fans). 

Cross-media effects 
See Section 4.6.4.2.2. 

Environmental performance and operational data 
See Section 4.6.4.2.2. 

Technical considerations relevant to applicability 
See Section 4.6.4.2.2. 

Driving force for implementation 
See Section 4.6.4.2.2. 

Example plants 
See Section 4.6.4.2.2. 

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283 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
See Section 4.6.4.2.2. 

Reference literature 
[ 464, Netherlands 2010 ] 

4.5.4.2.1.3 

Equal spreading of recirculated air by indoor fans and heaters  

Description 
This technique is fully described in Section 4.6.4.2.3, as it forms part of an integrated housing 
system.  The  technique  consists  of  heating  the  house  by  a  combination  of  heaters  and  indoor 
ventilators. Ventilators drive warm air from the top of the building down to the floor level. The 
air is warmed up by thermal exchange with  hot water produced by an indirectly fired thermal 
heater using propane or natural gas or by central heating. The ventilation system is completed 
with equipment to draw the air out in a horizontal direction, spreading the hot air all over the 
litter. 

Achieved environmental benefits  
An optimal indoor climate is achieved at low heating costs. A reduction of energy consumption 
for heating of around 20 % is achievable, with the related cost reduction, as a result of the good 
mixing  of  warm  air  from  the  ceiling  with  colder  air  just  above  the  housing  floor.  Ammonia 
emissions are also reduced by the drying effect of the warm airflow to the litter.  

Cross-media effects 
See Section 4.6.4.2.3. 

Environmental performance and operational data 
See Section 4.6.4.2.3. 

Technical considerations relevant to applicability 
See Section 4.6.4.2.3. 

Driving force for implementation 
See Section 4.6.4.2.3. 

Example plants 
See Section 4.6.4.2.3. 

Economics 
See Section 4.6.4.2.3. 

Reference literature 
[ 470, Netherlands 2011 ] 

4.5.4.2.1.4 

Energy-saving fans  

Description 
The  housing  ventilation  system  can  be  automatically  controlled  according  to  the  CO2 
concentration, resulting in a reduced air exchange.  

Achieved environmental benefits 
Heat  losses  due  to  the  ventilation  of  buildings,  and  thus  the  extra  consumption  of  energy  for 
heating, can be minimised by optimising the air renewal, in order to achieve the minimum rates 
of  ventilation  in  winter.  In  a  litter-based  system  for  the  rearing  of  broilers,  the  energy 

284 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
consumption is 70 % lower than in the conventional (old) housing system, while ammonia and 
odour emissions are reduced by 20–30 % due to the reduced air exchange.  

Chapter 4 

Cross-media effects 
No reported cross-media effects. 

Environmental performance and operational data 
The  operating  conditions  and  related  energy  consumption  levels  of  a  farm  for  the  rearing  of 
broilers,  equipped  with  'energy-saving  fans',  are  presented  in  Table 4.43.  The  housing  system 
has a capacity of 120 000 bird places and consists of two insulated buildings; each building with 
two compartments for 30 000 birds. 

Table 4.43:  Operating  conditions  and  energy  consumption  of  a  broiler  housing  system  equipped 

with energy-saving fans, in Finland 

Parameter 

Insulation  

Cold season ventilation (1)  
Warm season ventilation (1)  
Annual fuel consumption for heating 
Electricity 
(1) Depending on the size of the birds. 
Source [ 144, Finland 2010 ] 

Characteristics/consumption 

Walls: 140 mm mineral wool 
Ceiling: 300 mm blown wool (cellulose) 
Floor: not insulated 
1 500–150 000 m3/h  
15 000–300 000 m3/h  
1.42 kWh/ap/yr 
0.29 kWh/ap/yr 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
The investment cost of a new broiler farm is reported to be equivalent to EUR 11.67 per animal 
place,  and  EUR 12.5  per  animal  place  if  it  is  equipped  with  energy-saving  fans,  i.e.  the  extra 
cost is equivalent to EUR 0.83 per animal place. 

Driving force for implementation 
The driving force is improved animal performance due to the achieved temperature uniformity. 
The average daily gain is reported to be approximately 3–4 g/d higher than the average value 
observed in Finland. 

Example plants 
Commonly applied in new farms for broiler rearing in Finland. 

Reference literature 
[ 144, Finland 2010 ] 

4.5.4.2.2 

Management of ventilation in pig houses 

Description 
Ventilation in pig housing can be optimised by the following measures:  

 

The  rate  of  air  exchange  is  primarily  responsible  for  energy  requirements  for  heating; 
therefore,  it  is  crucial  to  control  the  flow  of  air  and,  in  particular,  to  always  adjust  the 
minimum  flow  rate  to  the  physiological  needs  of  the  animals,  in  order  to  ensure  their 
health and welfare.  

Intensive Rearing of Poultry or Pigs 

285 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

 

 

 

 

 

 

 

 

Installing  energy-efficient  fans  and  equipment.  Fans  with  the  lowest  possible  specific 
consumption  for  a  given  airflow  rate  and  air  pressure  rise  are  selected  (see  Section 
4.5.4.2.3). 

Forced ventilation systems are designed, built and operated so that the flow resistance of 
the ventilation system is kept as low as possible, e.g.:  

o  having short air ducts; 

o 

o 

o 

incorporating no sudden changes into the air duct cross sections; 

limiting the changes in duct direction, or application obstructions (e.g. baffles); 

removing any dust deposits in the ventilation systems and on the fans; 

o  avoiding having rain protection covers above the discharge points.  

Fans with low-rated rpm (low-speed units) use less energy than those that operate at high 
rpm  (high-speed  units).  Low-speed  fans  can,  however,  only  be  used  if  the  ventilation 
system exhibits a low flow resistance (< 60 Pa). 

Fans designed on the basis of electronic commutation technology exhibit a significantly 
lower  power  requirement,  particularly  over  the  regulated  speed  range,  compared  with 
transformer-regulated  or  electronically  regulated  fans.  If  a  series  of  fans  is  operated  in 
order to ventilate a house, a multiple-series gang-switching arrangement of fans may be 
advisable.  It  means  that  successive  activation  or  deactivation  of  each  individual  fan 
controls the volume of the airflow. For maximum efficiency, in such an arrangement each 
fan  operates  and  contributes  to  the  required  ventilation  volume  at  its  full  capacity.  The 
volume of the airflow corresponds with the number of activated fans. 

The  installation  of  air  cleaning  equipment  significantly  increases  the  flow  resistance  of 
forced  ventilation  systems.  In  order  to  deliver  the  requisite  air  rates,  particularly  in 
summer, higher-capacity fans with a higher specific power requirement may be necessary 
(see Section 4.9). 

The exhaust air in centralised ventilation systems is extracted from the building by using 
only one fan, whose specific consumption (W/m3 of extracted air) is lower than the sum 
of the consumption levels of single fans required in room-by-room forced ventilation. By 
applying  centralised  ventilation,  reported  reductions  of  the  energy  consumption  are 
generally  between  20 %  and  30 %  [  343,  ADEME  2008  ].  Other  measurements  have 
shown a reduction of up to 60 % [ 350, France 2010 ].  

Monitoring  of  yearly  fan  clogging  before  the  warm  season.  Removal  of  settled  dust 
contributes to avoid overconsumption and improve the equipment life span. 

Frequency  converter:  in  practice,  most  ventilators  are  powered  by  a  230 volt  triac 
controller.  An  efficient  control  system  that  can  be  used  to  power  a  ventilator  is  a 
frequency converter, where the ventilators can work at low speeds without any decrease 
in  energy  efficiency.  Fans  must  be  of  the  3 × 400  volt  AC  type  and  can  be  installed  in 
each compartment of any pig or poultry shed. Benefits of the system include less energy 
consumption  and  less  fan  wear-out  for  less  heat  produced.  Above  all,  all  the 
compartments can be adjusted to receive between 5 % and 100 % ventilation, regardless 
of the influences of the weather (e.g. even in windy weather). The system works with the 
aid  of  measuring  fans,  installed  in  the  shed  compartments,  that  measure  the  need  for 
ventilation.  In  connection  to  the  main  frequency  controller,  each  compartment's 
ventilating fans are run at reduced speeds to produce the volume of air that is detected by 
the measuring fans. In practice, fans do not work at maximum speed at most times of the 
year and during the winter period fans seldom work above 25 % of their maximum speed. 
The  power  reduction  achievable  by  using  a  frequency  converter  system  is  up  to  69 %, 
compared to the 230 volt motors with the conventional system.  

286 

Intensive Rearing of Poultry or Pigs 

 
 
Achieved environmental benefits 
Energy  consumption  and  associated  costs  can  be  reduced.  An  optimised  management  of 
ventilation can lead to 50 % savings in heating costs [ 350, France 2010 ]. 

Chapter 4 

Cross-media effects 
No information provided. 

Environmental performance and operational data 
In  France,  ventilation  accounts  for  about  40 %  of  the  total  energy  consumption  at  integrated 
breeding-to-fattening  farms  and  about  90 %  of  the  total  energy  consumption  in  fattening  pig 
housing  systems  [  344,  ADEME  2008  ].  In  Germany,  ventilation  represents  26 %  of the total 
electricity consumption in fattening pig houses [ 624, IRPP TWG 2013 ]. 

From  Table 4.44,  it  can  be  deduced  that  increasing  the  ventilation  rate  from  the  minimum 
recommended (in France) flow rate, at the beginning of the post-weaning cycle, of 3 m3/h per 
animal  (which  fulfils  the  physiological  needs  of  the  weaners),  to  a  standard  ventilation  of 
5 m3/h per animal can result in the doubling of the energy consumption for heating; the energy 
consumption  per  pig  produced  will  be  increased  from  6.7 kWh  to  12.3 kWh)  [  344,  ADEME 
2008] [ 350, France 2010 ]. The combined effect of insulation in reducing heat consumption is 
also  presented.  Good  control  of  the  ventilation  rates  can  thus  allow  appreciable  savings  in 
heating costs, without degrading the environment and without additional investment. 

Table 4.44:  Heat consumption according to minimum ventilation flows and added insulation, for 

weaners at an early post-weaning age 

Ventilation 
m3/h 
per animal 
3 
4 
5 
6 
7 

Heat consumption 

kWh 
per pig produced  
6.68 
9.02 
12.29 
14.82 
17.40 

Source: [ 344, ADEME 2008 ] 

Heat consumption with  
1 cm of insulation added 
kWh 
per pig produced  
6.00 
8.22 
11.00 
12.79 
14.35 

The application of different ventilation rates results in, first of all, a modification of the indoor 
environment. Tests were carried out in France in order to determine the effect of the ventilation 
rate on the performance and health status of fattening pigs. Minimum and optimum ventilation 
rates were tested as presented in Table 4.45. Temperature (24 °C) and relative humidity (65 %) 
were kept constant throughout the experiment. It was found that the application of an optimum 
airflow made it possible to decrease the ammonia concentration by half. It was also found that, 
for  the  same  type  of  floor,  there  were  more  germs  in  the  environment  when  the  minimum 
airflow was applied. Minimum flow was also associated with increased dust levels (20–30 %) 
[ 261, France 2010 ].  

Table 4.45:   Ammonia emissions and germs concentration in relation to the ventilation rate 

Parameter 
Ventilation rate 
(m3/hour/pig) 

NH3 (ppm) 

Germs 
(number/m3) 
NB: NR = not relevant.  

Source: [ 261, France 2010 ] 

Floor characteristics  Optimum flow 

Minimum flow 

NR 

15–50 

Metal slats 
Concrete slats 
Metal slats 
Concrete slats 

7.5 
6.6 
73 
166 

8–19 

15.1 
16.8 
103 
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Intensive Rearing of Poultry or Pigs 

287 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Technical considerations relevant to applicability  
Centralised  ventilation  can  be  applied  only  to  new  buildings.  An  adjustable regulation  of 
temperature  and  ventilation  can  be  applied  in  both  existing  and  new  housing  systems  
[ 261, France 2010 ]. 

Economics 
The  investment  costs  of  a  frequency  converter  system  are  quite  similar  to  those  of  a 
conventional  system.  The  purchase  and  installation  of  one  or  more  regulation  devices  largely 
compensate the potential economic losses generated by poor control of the indoor climate [ 261, 
France 2010 ]. Energy-saving fans are still relatively expensive and their lifespan is short.  

Good control of the ventilation rates can allow appreciable savings in the heating costs without 
degrading the indoor environment and without additional investment. For example, the potential 
energy  cost  savings  in  an  integrated  breeding-to-fattening  farm  of  200  sows  are  equivalent  to 
EUR 1 650 per year.  

The annual costs for the purchase and installation of large fans with a capacity of 100 000 m3/h 
for a house of 250 sows are estimated to be between EUR 0.03 and EUR 0.04 per pig produced, 
equivalent to less than EUR 1 per tonne of fattening pigs produced. This value is calculated with 
a payback period of 10 years [ 350, France 2010 ]. 

Driving force for implementation 
Even though the cost of centralised ventilation is higher than conventional ventilation, it allows 
for the installation of end-of-pipe air cleaning systems and of heat exchanging equipment (air-
air and air-water). 

Example plants  
These measures are widely applied. 

Reference literature 
[ 261, France 2010 ] [ 343, ADEME 2008 ] [ 350, France 2010 ] [ 355, Warwick 2007 ] [ 395, 
ADAS 1999 ] [ 624, IRPP TWG 2013 ] 

4.5.4.2.3 

Use of high-efficiency ventilation systems 

Description 
High-efficiency  ventilation  systems  consist  of  efficient  fans  and  ducts.  Fan  efficiency,  which 
can  vary  significantly,  is  stated  in  airflow  per  unit  of  energy  (e.g.  m3/h  per  W).  The  system 
provides the rated air throughput of the fan at the operational pressure it requires, together with 
the energy rating. Ventilation inlet and outlet ducting should be sized adequately. The internal 
surfaces should be smooth and clean with slight bends. 

The following characteristics should be noted when considering the efficiency of fans: 

 

 

 

 

fan efficiency generally increases with the impeller diameter; 

belt-driven fans are generally more efficient than fans with direct drives; 

fans fitted with patented 'bell-mouths' to smooth the passage of the air will be 10 % more 
efficient than fans fitted into a basic circular diaphragm; 

fitting 'cones' to outlet fans will increase efficiency by 10–15 %. 

Achieved environmental benefits 
Energy consumption is reduced.  

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
None reported. 

Environmental performance and operational data 
In pig farms, energy-saving fans can reduce the associated energy consumption for ventilation 
by up to 60 % [ 350, France 2010 ]. 

Most manufacturers produce performance characteristics measured to ISO 5801, which can be 
used for the selection of the most efficient unit. 

Technical considerations relevant to applicability 
High-efficiency ventilation systems may not be applicable to existing plants. 

Economics 
When  installing  fans,  the  energy  cost  of  the  fan  over  its  operational  life  has  to  be  taken  into 
account as well as its initial capital cost. It is reported that a 10 % higher investment to secure a 
10 % energy saving will pay back in around 18 months.  

Driving force for implementation 
No information provided. 

Example plants 
No information provided. 

Reference literature 
[ 350, France 2010 ] [ 356, Carbon Trust 2005 ] 

4.5.5 

Heat recovery 

4.5.5.1 

Heat exchangers 

Description 
There are three major types of heat exchangers for energy recovery (see Section 2.14.2): 

 

 

 

air-air heat exchangers; 

air-water heat exchangers; 

air-ground heat exchangers. 

In the air-air heat exchanger, the incoming air absorbs heat from the exhaust air from the house, 
without mixing the two airflows. The device can be composed of plates of anodised aluminium 
or PVC tubes [ 344, ADEME 2008 ]. 

In  the  air-water  heat  exchanger,  water  flows  through  aluminium  fins  or  plates  located  in  the 
exhaust ducts and absorbs heat from the exhausted air. Then, the water feeds the fan coil placed 
at the air intake of the housing system. 

Air-ground  heat  exchangers  absorb  heat  from  and/or  dissipate  heat  to  the  ground.  In  the  air-
ground heat exchanger, fresh air is circulated through pipes buried  at a depth of, for example, 
about two metres. Air-ground heat exchangers take advantage of the low seasonal temperature 
variation of subterranean soil in order to warm or cool air.  

Heat recovery is also possible from the scrubbing waters of air cleaning systems or the exhaust 
gases of biogas engines; however, these types of application are not always practicable.  

Intensive Rearing of Poultry or Pigs 

289 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
Heat recovery enables lower energy consumption for heating, by providing an additional source 
of heat.  

In the broiler sector, the use of air-air heat exchangers coupled with circulating fans, to evenly 
distribute  the  heated  air  over  the  litter,  have  shown  promising  ammonia  emission  reductions. 
This technical combination is described in Section 4.6.4.2.2. 

Cross-media effects 
For air-ground heat exchangers, relatively large soil areas are required. For air-air exchangers, 
there is an increase in electricity consumption. In air-water heat exchangers, the pump for the 
recirculation of water consumes electricity.  

Heat exchangers need to be cleaned often, in order to avoid clogging. Cleaning and disinfection 
of air-air exchangers should be done during the sanitary emptying on poultry farms. 

Environmental performance and operational data 
Pig farms 
In  air-air  heat  exchangers  in  pig  rearing,  the  theoretical  maximum  yield  ranges  from  50 %  to 
55 % on an annual basis; this means that, if exhaust air is removed at 24 °C, the incoming air 
can be heated up to 12 °C with an outside temperature close to 0 °C.  

According to a study on energy consumption, 36 % of the total energy of an integrated pig farm 
(breeding and fattening) is used up in weaner production, with the majority of it (80 %) used to 
heat the rooms, i.e. approximately 14 kWh per pig produced [ 344, ADEME 2008 ]. Air-air heat 
exchangers  allow  a  reduction  of  the  electricity  consumption  for  heating  of  30 %  to  50 %  in 
houses  for  weaners.  Therefore,  the  application  of  air-air  heat  exchangers  in  weaner  houses 
would allow for a recovery of 4–7 kWh per pig produced.  

On  the  basis  of  the  theoretical  heat  recovery  achievable  with  the  application  of  air-air  or  air-
water heat exchangers, the necessary higher temperatures needed in the rearing of weaners (e.g. 
at the entry of the piglets or in cold periods) can only be achieved with a complementary heating 
system. 

Air-air heat exchangers achieve higher yields in the cold season when heat is required the most. 
Table 4.46 shows an example of an air-air heat exchanger reported by France.  

Table 4.46:  Example of operational data of an air-air heat exchanger 

Outdoor 
temperature 
(°C) 
-9.4 
-4.9 
0.0 
4.4 
7.8 

Incoming air 
temperature 
(°C) 
2.6 
6.4 
9.2 
11.6 
13.9 

Source: [ 350, France 2010 ] 

Indoor 
warmed air 
(°C) 
12.0 
11.3 
9.2 
7.2 
6.1 

Recovered 
energy 
(W/pig) 
97 
89 
69 
46 
41 

The maximum thermal gain obtained by air-water heat exchangers is reported to be 12 °C when 
the outdoor air temperature is 0 °C [ 345, France 2010 ]. The performance of this type of heat 
exchanger will mainly depend on the technical dimensions of the system (e.g. surface of fins, 
water  flow)  and  proper  maintenance  (e.g.  control  of  dust  contamination  of  fins).  Electricity 
savings  for  heating  requirements  is  estimated  at  about  50 %.  Limited  data  concerning  the 
performance  of  air-water  heat  exchangers  applied  in  the  poultry  or  pig  sectors  were  available 
and a limited number of applications is reported [ 350, France 2010 ].  

290 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The  air-ground  heat  exchanger  requires  careful  dimensioning,  in  order  to  ensure  a  good 
performance. Air is circulated in underground pipes (at a depth of approximately two metres); 
one pipe of 16 cm in diameter and 25 m in length is necessary for every three fattening pigs.  

Poultry farms 
In the Netherlands, air-air exchangers applied in litter-based broiler houses are reported to have 
a  capacity  of  0.35  m3  per  animal  place/hour  for  a  normal  type  of  heat  exchanger,  and  up  to 
1.0 m3 per animal/hour for an improved type [ 464, Netherlands 2010 ]. 

In France, air-air exchangers applied in litter-based houses for broilers, turkeys or guinea fowl 
are reported to have a minimum capacity of 8 m3/h per m2; for organic production and poultry 
breeding, the minimum capacity is reported to be 2.5 m3/h per m2 [ 624, IRPP TWG 2013 ]. 

A survey carried out in France among 200 farmers using air-air exchangers for at least 6 months 
showed a 30 % reduction in gas consumption, as well as a decrease in relative humidity of 11 % 
and  a  15  %  reduction  in  the  quantity  of  litter  produced.  In  40  %  of  the  cases,  an  air  quality 
improvement was reported (e.g. ammonia). The survey also indicated that an average time of 73 
minutes  per  equipment  and  per  batch  was  required  for  cleaning,  while  the  farm's  electric 
consumption was shown to increase by 7 % on average  [ 624, IRPP TWG 2013 ]. In general, 
air-air heat exchangers in poultry production can allow shorter heating periods and can ensure 
the  proper  ventilation  rates  during  the  start-up  of  the  cycle.  They  also  contribute  to  the 
maintenance of a steady indoor temperature and a lower humidity (10 % lower on average). The 
reduction in propane consumption for heating ranges from 25 % to more than 50 % depending 
on the season, and the type and the size of the exchanger [ 345, France 2010 ].  

Results  of  another  investigation  carried  out  over  1  year  of  operation  showed  the  following 
achievements: 

 

 

a decrease in propane consumption for birds aged six days and over; 

radiant heaters were turned off 10 days earlier in the test building, for turkeys. 

Test results concerning propane and electricity consumption  on three different farms applying 
air-air heat exchangers are summarised in Table 4.47.  

Technical considerations relevant to applicability 
There  are  no  serious  limitations  to  the  application  of  heat  exchangers,  except  the  cost  of  the 
equipment, which is still relatively high, and the cost for additional cleaning (see Economics). 
The  ventilation  design  becomes  a  limitation  when  retrofitting  the  technique  in  naturally 
ventilated existing houses. 

Air-ground heat exchangers cannot be implemented when there is not enough available space in 
the  farmyard,  due  to  the  high  demands  for  soil  surface.  Heat  recovery  from  scrubbing  waters 
and  from  exhaust  gases  of  engines  is  often  not  practicable.  In  the  poultry  sector,  air-air  heat 
exchangers are mainly applied [ 350, France 2010 ].  

Economics 
Poultry farms 
In  the  poultry  sector,  for  a  standard  poultry  house  of  1 200  m2,  two  heat  exchangers  with  a 
capacity of 5 000 m3/h are needed. The necessary investment is about EUR 8.3–10/m2 and the 
additional operating costs for electricity about EUR 0.13/m2 per year. In this case, savings due 
to  avoided  propane  consumption  are  around EUR 1/m2  per  year  and  the  investment  payback 
time in the range of 9.5–11.4 years [ 350, France 2010 ]. For a standard density of 22.8 birds/m2, 
the investment costs would be EUR 0.36–0.44 per animal place, the operating costs EUR 0.006 
per animal place and savings around EUR 0.167 per animal place [ 418, ITAVI 2010 ]. 

Intensive Rearing of Poultry or Pigs 

291 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

For one heat exchanger of 15 000 m3/h, serving two buildings of 1 200 m2 each (total surface of 
2 400 m2),  the  investment  costs  amount  to  approximately  EUR 23/m2;  the  related  additional 
electricity  consumption  is  EUR 0.06–0.09/m2  per  year,  and  the  annual  saving  in  gas 
consumption is EUR 2–2.4/m2 (50–60 % savings). The payback time for the investment for the 
heat exchanger will be between 9.7 and 11.9 years [ 350, France 2010 ]. 

Test  results  report  that  yearly  savings  of  propane  gas  range  between  18 %  and  27 %.  The 
additional electric energy consumption, due to the heat exchangers, would cost only 8–27 % of 
the cost saving in propane gas [ 466, Bonnouvrier et al. 2009 ]. Data concerning propane and 
electricity  consumption  and  related  costs  are  reported  in  Table 4.47,  for  three  different 
applications of air-air heat exchangers in the poultry sector. 

Table 4.47:  Propane  and  electricity  consumption  and  costs,  in  three  different  poultry  farms 

applying heat recovery by air-air heat exchangers  

Parameters 
Surface area of building 
Animal type 
Batches/year 

Heating system 

Ventilation 

No of heat exchangers 
Heat exchanger operation 

Unit 
m2 
NA 
NA 

NA 

NA 

NA 

NA 

Propane 
consumption  

Control 
building 
Test 
building 

kg/m2/year 

kg/m2/year 

Propane saving achieved  

kg/year 
 % 
EUR/year (1) 
kWh/year 

98 

2 185 

EUR/year 

Additional electricity 
consumption due to heat 
exchangers  
Investment payback time 
(2)  
Investment payback time 
with 40 % subsidy 
(1) Gas price: EUR 740/t. 
(2) Investment cost for two heat exchangers: EUR 10 000–12 000. 
NB: NI = no information provided; NA= not applicable. 
Source [ 466, Bonnouvrier et al. 2009 ] 

7.7–9.2 

4.6–5.5 

years 

years 

Trial 1 
1 200 
Turkeys 
2.5 
Adjustable 
radiant heaters 
Mechanical 
2, on long wall, 
opposite fans 
Cyclical 

Trial 2 
1 300 
Broilers 
7.5 
Indoor space 
heaters 
Natural 

Trial 3 
1 200 
Broilers 
7.6 
Adjustable 
radiant heaters 
Natural 

3, on long wall 

2, on long wall 

Cyclical 

Progressive 

4.73 

3.47 

1 572 
27 
1 165 

12.4 

10 

3 107 
18 
2 300 

7 946 

486 

NI 

NI 

5.6 

4.6 

1 125 
20 
832 

2 918 

230 

NI 

7.6 

In the poultry sector, cleaning and checking operations are carried out at the end of each cycle 
and require 1.5–2 hours per unit [ 464, Netherlands 2010 ]. 

Pig farms 
The investment cost for an air-air heat exchanger is estimated at EUR 0.7 per m3 of exhaust air 
(capacity  of  25 000  m3/h  for  a  farm  of  250  sows,  amortisation  over  10  years,  interest  and 
subsidies excluded). The air-air heat exchanger would allow a saving of EUR 2 to EUR 4 per 
tonne of pig produced [ 350, France 2010 ]. 

The costs of air-ground systems vary depending on the method of drilling the soil, the type of 
tubes  and  fans,  the  surface  necessary,  etc.  In  the  pig  sector,  the  cost  of  an  air-ground  heat 
exchanger  is  reported  to  be  between  EUR 60  and  EUR 80  per  fattening  pig  place,  which 

292 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

includes  the  excavation  (20 %  of  the  price),  a  concrete  reception  pit  (55 %),  purchase  of  the 
tubes (15 %) and ventilation (10 %). 

Driving force for implementation 
A  reduction  of  energy  costs  may  encourage  the  adoption  of  this  technique.  Heat  exchangers 
allow the improvement of ventilation (i.e. the number of air changes of the indoor air and those 
during  cold  periods)  in  mechanically  or  naturally  ventilated  buildings,  without  decreasing  the 
indoor temperature while improving the environment for the animals. 

Heat exchangers present the advantage of warming the air before it enters the building, which 
reduces the risks related to the effects of cold air on animals and offers more flexibility in the 
management of ventilation. 

At the start-up of the rearing cycle in a broiler farm, an ambient temperature of around 32 °C is 
necessary in order to ensure the thermal comfort of young chicks. At the same time, a minimum 
airflow is required to remove undesirable gases and allow fresh air to enter. Introducing cold air 
into the building, and heating it up to replace the heat extracted with the exhaust air, consumes 
large  amounts  of  energy.  As  a  result,  options  for  recovering  energy  from  the  outgoing  air,  in 
order to heat the incoming air, represent an attractive solution. In the poultry sector, benefits to 
the litter and air quality are also claimed, as well as to birds' physical performances.  

Example plants 
In France, the UK and the Netherlands, these techniques are becoming more common in poultry 
rearing. In 2012 in France, almost 20 % of poultry farmers had invested in air-air exchangers. In 
France, air-air heat exchangers are already common in the pig sector and they are mainly used 
to  preheat  air  in  weaner  houses;  some  air-water  heat  exchangers  are  connected  to  water 
scrubbing systems. 

Reference literature 
[  344,  ADEME  2008  ] [  345,  France  2010  ] [  352, Bartolomeu  2005  ]  [  353, CA  Pays  Loire 
2009 ] [ 350, France 2010 ] [ 418, ITAVI 2010 ] [ 464, Netherlands 2010 ] [ 466, Bonnouvrier 
et al. 2009 ] [ 624, IRPP TWG 2013 ] 

4.5.5.2 

Heat pumps for heat recovery 

Description 
Heat pumps are devices designed to move thermal energy in the opposite to that of the natural 
heat  flow  by  absorbing  heat  from  a  cold  location  and  releasing  it  to  a  warmer  one,  and  vice 
versa.  Heat  is  absorbed  from  various  media  and  circuits,  such  as  slurry  cooling  systems, 
geothermal energy, scrubbing water, slurry biological treatment reactors, biogas engine exhaust 
gases, and is consumed on farm, usually in buildings. For this purpose, a fluid circulating in a 
sealed circuit transfers the heat to another location under the operating principle of the reverse 
refrigeration  cycle  (see  Section 2.14.3  and  Figure 2.43).  Liquids  used  in  other  operational 
circuits are preheated with the heat that is transferred, to produce  sanitised water, or to feed a 
heating system and may even be used in cooling systems. Heat pumps mostly recover heat in 
air-air, air-water and water-water circuits. 

Slurry cooling 
The  technique  is  frequently  combined  with  slurry  cooling  systems,  adding  mutual  benefit  to 
each technique (see Sections 4.7.1.7 and 4.7.1.8). 

Geothermal energy 
As  a  result  of  the  constant  moderate  temperature  that  is  maintained  below  the  surface  of  the 
earth  throughout  the  year  due  to  solar  radiation  absorption,  a  sealed  underground  piping  loop 
filled with circulating water is connected to a heat pump to exchange heat between housing and 
the ground or a shallow aquifer (less than 100 m). The heat pump uses the earth as a heat source 

Intensive Rearing of Poultry or Pigs 

293 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

in  the  winter,  i.e.  water  circulating  in  the  piping  loop  absorbs  heat  and  carries  it  to  the  heat 
pump, or a heat sink in the summer, i.e. the heat pump absorbs heat from the air and transfers it 
to water circulating in the piping loop where it is absorbed by the earth. 

Scrubbing water  
Heat is recovered from the scrubbing water of air cleaning systems which has to be collected in 
sufficiently large basins. 

Biological reactors 
They can provide working temperatures as high as 25 °C. 

Biogas engines' exhaust gases 
Heat can also be recovered from the exhaust gases  from biogas engines in combined heat and 
power units (see Section  4.12.5). The recovered heat is normally used for heating piglet areas  
[ 373, UBA Austria 2009 ]. 

Achieved environmental benefits 
Improvement of the farm's energy balance. 

Cross-media effects 
A heat pump uses some external power to accomplish the work of transferring energy from the 
heat source to the destination (heat sink).  

Environmental performance and operational data 
Compared  to  the  classic  heating  applied  in  weaner  houses  (average  consumption  of 
9 kWh/piglet  per  year),  geothermal  heat  recovery  allows  savings  of about  50 %  while  heating 
energy savings of around 70 % are possible after heat recovery from a biological reactor or from 
scrubbing  waters.  Heat  pumps  based  on  biological  reactors  and  water  from  the  scrubbing 
systems are more efficient than those based on geothermal energy because the temperatures of 
the water of scrubber and of the biological reactor are stable and not associated with climatic 
conditions [ 350, France 2010 ].  

The coefficient of performance of a geothermal heat pump and of a heat pump connected to a 
biological reactor pump is about 2–3 (i.e. for 2–3 kWh recovered, 1 kWh of electric energy is 
consumed); for scrubbing waters at about 20 °C, the coefficient is up to 4. 

Technical considerations relevant to applicability 
The technique can be applied in both the poultry and pig sectors. 

For  geothermal  heat  recovery  when  using  horizontal  pipes,  the  principal  constraint  is  that  a 
surface approximately twice as large as the surface of the building to be heated is required. As a 
consequence, this technique is still not very common and is not suitable for farms with relatively 
small land availability  which cannot meet the surface requirements. Where space is limited, a 
vertical piping loop can be inserted into boreholes. 

The  position  of  buildings,  their  layout  and  available  space  may  limit  the  suitability  of  this 
technology for retrofitting [ 624, IRPP TWG 2013 ]. 

Economics 
The  investment  cost  of  a  heating  system  for  weaners with  warm  water  and  a  geothermal  heat 
pump is reported by France at EUR 45–55 per animal place, which has to be compared with the 
cost of a standard heating system of EUR 35 per animal place.  

The reduction of energy consumption allows savings estimated at about EUR 0.01 per kg of pig 
produced. 

294 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation  
Heat  pumps  can  be  successfully  coupled  to  underfloor  heating,  hence  reducing  the 
inconvenience of the traditional air convection systems. 

Incentive  payments  for  using  renewable  energy  can  justify  the  adoption  of  this  technique. 
Ground  and  water  source  heat  pumps  are  included  in  the  Renewable  Heat  Incentive  financial 
support programme in the UK. 

Example plants  
Geothermal  heat  recovery  is  used  in  Finland.  Heat  pumps  in  air-water  circuits  have  been 
installed  at  existing  pig  units  in  Ireland  [  624,  IRPP  TWG  2013  ].  Heat  pumps  are  used  in 
Denmark and the Netherlands in slurry cooling systems. 

Reference literature 
[  344,  ADEME  2008  ]  [  348,  Bartolomeu  2008  ]  [  350,  France  2010  ]  [  373,  UBA  Austria 
2009 ] [ 624, IRPP TWG 2013 ]  

4.5.5.3 

Heat recovery in broiler housing with heated and cooled littered 
floor (combideck system) 

Description 
This system consists of heat exchangers below the concrete floor. In particular, a closed water 
circuit, serving the house, made of hollow strips (intermediately spaced every 4 cm) is installed 
in an insulated layer below the floor, at a depth of 10–12 cm. Another water circuit is built at a 
deeper level below the floor (2–4 metres) for storing the excess heat or to return it to the broiler 
house when needed. A heat pump connects the two water circuits  (see Figure 4.7). Depending 
on the temperature of the water that flows through the strips, the floor and the litter will either 
be warmed up or cooled down. 

When the  broilers  enter  on  the  first  day  of  the  production  cycle,  water  is  warmed  up  and fed 
through the strips below the floor to warm the floor. Broilers need some heat until about day 21 
(about 28 °C). After a short period of equilibrium, the growing process generates a lot of heat 
and this heat is normally radiated into the soil below the building. This heat is now absorbed by 
the  cold  water in  the  circuit  below the floor and the heat pump  moves  the  heat  to the  second 
water circuit which stores the heat underground. At the same time, the broilers are cooled down 
and the temperature is maintained at about 25 °C. 

After the broilers leave the housing, the floor is emptied and cleaned. Once ready for the next 
production  cycle,  the  warm  water  from  the  underground  storage  is  pumped  up  and  is  run 
through the heat pump, warming the water in the water circuit that serves the house. The floor is 
preheated  and  less  energy  will  be  needed  to  warm  the  floor  to  the  temperature  required  for 
housing young broilers. Once the broilers are in the house (Phase 1), the stored heat is used and 
only a little extra heating may be required. After the short intermediate phase of thermal balance 
(Phase 2), cooling is required again (Phase 3) and the heat dissipated from the housing will be 
stored underground and will be available for the next production cycle.  

Intensive Rearing of Poultry or Pigs 

295 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 36, R&R 2000 ] 

Figure 4.7:  Schematic representation of a heat recovery system installed in a broiler house 

Source: [ 36, R&R 2000 ] 

Figure 4.8:  Graphic representation of the working principle of the combideck system during one 

broiler production cycle 

Achieved environmental benefits 
The reduction of energy use is the main achieved benefit. The amount of energy depends on the 
farm; a reduction of up to 50 % in energy use has been achieved. Furthermore, preheating the 
floor prior to littering and introducing poultry and heating the floor during the first period of the 
rearing cycle keep the litter dry by avoiding moisture condensation, hence preventing ammonia 
volatilisation.  Subsequent  cooling  of  the  floor  at  a  later  stage  of  the  rearing  period  decreases 
microbial activity, which reduces the breakdown of uric acid. 

The NH3 reduction efficiency depends on local conditions and can be up to 40 % at a cost of 
EUR 6 per kg of NH3 abated per year [ 508, TFRN 2014 ]. 

Cross-media effects 
The  storage  of  heat  is  achieved  at  the  (electrical)  expense  of  the  heat  pump.  The  increased 
consumption  of  electricity  for  the  pump  is  offset  by  the  reduced  heat  and  ventilation 

296 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

requirements. The coefficient of performance of ground source heat pumps is usually between 
2.5  and  3;  however,  for  the  specific  application  presented  in  Table 4.48,  the  coefficient  of 
performance was reported as 4.4. 

Environmental performance and operational data 
Data  to  illustrate  the  results  of  a  combideck  application  are  presented  in  Table 4.48.  For 
80 000 broilers, three heat pumps of 0.1 kWe were used. Broilers were stocked at a density of 
18 birds/m2.  

Table 4.48:  Results of the application of the combideck system 

Reference 
situation 

Fuel type/ 
fuel use 

Fuel oil 
Natural gas 
Electricity 

Input 

49.5   m3 
36.1   m3 
40  MWh 

Total 

Combideck 
system applied 

Heating 
Ventilation 
Heat pump(1) 

63.6  MWh 
34.4  MWh 
189  MWh 

Total 

Reduction (as percentage of reference) 

Energy 
equivalent 
(MWh/yr) 
549 
321 
40 
910 
63.6 
34.4 
189 
287 
623 
(70 %) 

Costs (2) 
(EUR) 

CO2  
(tonne) (3) 

6 273 
9 277 
3 757 
19 307 
NI 
NI 
NI 
9 194 
10 113 
(52 %) 

65.0 
158 
14.8 
237 
23.5 
12.7 
44.4 
80.6 
156.4 
(66 %) 

(1) Coefficient of performance heat pump: 4.4. 
(2) Reference year 1999, corrected for low and peak tariffs on electricity prices in the Netherlands. 
(3) CO2 equivalent: oil 3.2, gas 1.8, electricity 0.37. 
NB: NI = no information provided. 
Source: [ 36, R&R 2000 ]  

In the above test, the reference farm emitted 0.066 kg NH3 per broiler place per year, while the 
average  ammonia  emissions  over  four  measured  production  cycles  were  0.045 kg  NH3  per 
broiler place per year. Hence, the reduction of the NH3 emission of this system was about 32 %.  

In  2001,  the  performances  of  raising  broilers  on  one  farm  in  two  different  houses  were 
compared. One house was equipped with the combideck system (House 2) and the other house 
without (House 1). The summary of the achievable performance is given in Table 4.49. 

Table 4.49:  Comparison  of  performance  for  identical  houses  with  and  without  the  combideck 

system 

Total birds 
Mortality (%) 
Harvesting weight (grams) 
1st time at 35 days 
Harvesting weight (grams) 
2nd time at 42 days 
Surplus payment per kg (EUR) 
Feed ratio (1 500 grams) 
Heating costs (per broiler in EUR) 

Source: [ 43, COM 2003 ] 

House 1  House 2 (Combideck) 
33 000 
4.97 

34 000 
2.85 

1 681 

2 250 

0.2 
1.55 
3.13 

1 692 

2 236 

0.4 
1.40 
2.10 

Intensive Rearing of Poultry or Pigs 

297 

 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
Chapter 4 

The  reuse  of  heat  generated  in  an  earlier  production  cycle  can  reduce  the  ventilation  rate  by 
around 14 %. 

Technical considerations relevant to applicability 
This  technique  is  not  applicable  to  pig  plants.  This  system  can  be  applied  in  both  new  and 
existing  poultry  houses.  If  constructed  in  existing  houses,  the  costs  are  higher  because  floors 
need  to  be  ripped  up  and  reconstructed  in  order  to  lay  the  necessary  underfloor  circuits. 
Construction and ground works will be needed in the farmyard, depending on the position of the 
broiler house. 

With  several  broiler  houses,  it  may  be  possible  to  use  heated  water  from  one  house  (being 
emptied) to  warm  another (to  be  stocked),  which  may  reduce the  energy  needed  for pumping 
even further. However, this idea has not yet been put into practice. 

The system can be applied only if soil conditions allow the installation of closed underground 
storage of the circulated water. The technique is less suitable in areas with hard and rocky soils. 
Application of the combideck system in colder climates where the frosts are longer and harder 
and penetrate the soil was not reported. 

Economics 
Investment  costs  (for  new  houses)  are  EUR 2  per  broiler  place  with  20  broilers  per  m2. 
Operating  costs  (depreciation,  interest  and  maintenance)  are  EUR 0.20  per  broiler  place  per 
year. The annual increased yields reportedly outweighs the yearly operating costs by a factor of 
about 3. For instance, veterinarian costs are reduced by about 30 %. Energy costs are reduced by 
about 52 %. The payback time is about 4 to 6 years [ 544, Netherlands 2002 ]. 

Driving force for implementation 
The  system  has  a  better  performance  in  terms  of  broiler  production  (reduction  of  mortality, 
higher  meat  price,  better  feed  ratio)  and  a  positive  effect  on  animal  welfare  (less  heat  stress, 
lower mortality, less veterinary services needed).  

Example plants 
In  the  Netherlands,  around  2  million  places  were  available  in  2008  that  were  built  with  this 
technique [ 468, CBS 2011 ]. Also, 10 systems are reported to have been built in Germany and 
Russia in 2010. 

Reference literature 
[ 36, R&R 2000 ] [ 43, COM 2003 ] [ 468, CBS 2011 ] [ 508, TFRN 2014 ] [ 544, Netherlands 
2002 ] 

4.5.6 

Natural ventilation 

Description 
Natural (or free)  ventilation  in  the  animal  house  is  caused  by  thermal  effects and/or  the  wind 
flow  (pressure  differences).  Naturally  ventilated  animal  houses  should  be  oriented  at  right 
angles to the main wind direction, if possible, and permit a free airflow to the animal house in 
order to enhance an optimal flow of fresh and outgoing air. For this purpose, the animal houses 
should  have  openings  in  the  ridge  and,  if  necessary,  also  on  the  gable  sides  in  addition  to 
controllable openings in the side walls. In contrast to forced ventilation, no defined air volume 
flow can be set. Free ventilation can be combined with elements of forced ventilation (i.e. fan 
assistance in hot weather). 

The  lowering  of  the  indoor  temperature  and  ventilation  rate  must  take  into  account  animal 
welfare  and  production  considerations.  Design  recommendations,  in  particular  for  the 
dimensioning of the fresh and exhaust air openings, are given in the literature. 

298 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Natural ventilation can be automatically controlled. In this case, openings or vents in the sides 
or  roof  are  opened  and  closed  by  electrically  driven  motors  in  response  to  sensors  in  the 
building. 

Achieved environmental benefits 
With regard to energy requirements, energy savings can be obtained from the animal housing as 
in  free  ventilated  houses  ventilation  and  heating  are  not  necessary.  A  reduced  potential  for 
ammonia emissions has also been reported due to the lower temperatures. 

Cross-media effects 
Higher labour requirements are reported due to more difficult cleaning and disinfection as well 
as a greater need for repairs. 

Environmental performance and operational data 
Various  natural  ventilation  systems  applied  in  pig  and  poultry  houses  are  presented  in 
Table 4.50. 

Table 4.50:  Different natural ventilation configurations 

Animal 
category 

Natural ventilation 
system 

Mode of operation 

Pigs, 
poultry 

Cross 
ventilation 

Pigs 

Open front 

Pigs 

Shaft 
ventilation 

Source: [ 474, VDI 2011 ] 

Air  exchange  takes  place  via  large-area  openings  in  the  side 
walls,  whose  cross  section  can  be  varied  using  blinds  or  wind 
protection  nets,  for  example.  The  air  exchange  is  supported  by 
ridge  slits  in  the  winter  and  additionally  by  openings  on  the 
gable side if the airflow is parallel to the ridge in the summer. 
The animal  house,  which is closed on three  sides,  is  ventilated 
through the open front side. The front side can be equipped with 
wind protection nets. 
The  fresh  air  flows  into  the  animal  house  through  flaps  or 
windows in the side or gable walls, while the outgoing air leaves 
the animal house through one or several shafts. In the summer, 
natural  ventilation  should  be  supported  by  opening  doors  and 
gates or by means of additional ventilation. 

In pig production, automatically controlled naturally ventilated housing systems in straw-based 
systems achieve reduced energy consumption as straw allows the animals to self-regulate their 
temperature,  protects  them  from  low  temperatures  and,  thus,  less  energy  is  required  for 
ventilation and heating [ 508, TFRN 2014 ]. 

Technical considerations relevant to applicability 
It  is  not  always  possible  to  reduce  the  overall  energy  consumption  by  applying  natural 
ventilation in animal houses as the energy demand for heating the house may increase. The final 
net  energy  balance  may  depend  on  the  climatic  conditions,  the  species  and  the  physiological 
stage of the animals. For example, in France, buildings with natural ventilation used for broiler 
production  register  higher  energy  demands  for  heating  than  mechanically  ventilated  houses 
[ 350, France 2010 ]. 

In pig houses, natural ventilation may not be applicable to housing systems with littered floors 
in warm climates and to housing systems without littered floors or without covered, insulated 
boxes (e.g. kennels) in cold climates. 

In  poultry  houses,  natural ventilation  may  not  be  applicable  during  the  initial  stage  of rearing 
(apart  from  duck  production),  or  in  those  farms  under  extreme  climatic  conditions.  Natural 
ventilation cannot be implemented in houses with a centralised ventilation system.  

Intensive Rearing of Poultry or Pigs 

299 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
Improved animal welfare.  

Example plants  
The technique is commonly applied. 

Reference literature 
[ 350, France 2010 ] [ 474, VDI 2011 ] [ 508, TFRN 2014 ] [ 575, UBA Germany 2011 ] 

300 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 4 

4.6 

Techniques for the reduction of emissions from poultry 
houses 

In general, the following principles can be applied in order to reduce ammonia emissions from 
poultry houses [ 508, TFRN 2014 ]: 

 

 

 

 

 

 

reducing the ammonia-emitting surface;  

removing the manure frequently to an external store (e.g. with belt removal systems);  

quickly drying the manure;  

using surfaces which are smooth and easy to clean;  

treatment of exhaust air by acid scrubbers or biotrickling filters;  

lowering  the  indoor  temperature  and  ventilation  as  much  as  animal  welfare  and/or 
production allow. 

Emission data reported in the tables may be accompanied (when the information is available or 
considered  relevant)  by  a  note  indicating  the  type  of  data  they  refer  to.  When  available,  this 
information is intended to qualify the origin of the values and it should be read as indicated in 
the footnotes to the tables. 

4.6.1 

Techniques for cage housing of laying hens 

Ammonia emission reduction in enriched cages is achieved by frequent manure removal from 
the house (e.g. twice a week) using manure belts. Equivalent or better results can be achieved by 
drying manure on belts with less frequent (e.g. weekly) removal. Emissions of ammonia from 
laying hen droppings result from chemical reactions in the manure that start immediately after 
excretion.  The  organic  nitrogen  (uric  acid)  is  quickly  transformed  into  ammonia  by  reactions 
that are enhanced by manure temperature and moisture content. Drying the manure is a way to 
inhibit the chemical reactions and thus reduce emissions. The quicker the manure is dried, the 
lower the emission of ammonia. Two main techniques are applied that create an airstream over 
the manure belt, which enhances the drying of the droppings: 

 

Forced  air  manure  drying:  air,  which  is  normally  preheated,  is  blown  over  the  manure 
collected on a manure belt through a perforated tube. 

  Whisk-forced air drying: a series of whisks situated above a manure belt are operated by a 
connecting rod which drives all whisks in the row simultaneously, so moving the indoor 
air and drying the manure.  

A  combination  of  frequent  removal  and  the  drying  of  manure  gives  the  best  reduction  of 
ammonia emissions from housing and also reduces emissions from storage facilities, but with an 
associated energy cost. However, the whisk-forced drying achieves, with lower energy input, a 
similar emission reduction to forced air drying. 

Pre-dried  manure  from  ventilated  belts  has  the  advantage  of  being  easier  to  stack  and  also  to 
heat  up  considerably  in  the  covered  store  with  consequent  further  drying.  Equipment  for 
managing manure is integrated into the manufactured cages, such as manure belts and optional 
ventilation systems. 

The  principles  underlying  the  reduction  of  ammonia  in  Sections  4.6.1.1  and  4.6.1.2  are  the 
same.  A  summary  of  the  reported  emissions  associated  with  the  different  housing  systems  is 
given  in  Table 4.51.  Where  relevant,  information  concerning  the  operating  conditions  and  the 
type of emission data (i.e. measured, estimated) are also given. 

Intensive Rearing of Poultry or Pigs 

301 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.51:  Summary of relevant reported achievable emissions in cage systems for laying hens 

Description 

NH3 

CH4 

N2O 

PM10  Odour 

(kg/ap/yr) 

(ouE/ap/s) 

Source 

[ 56, Denmark 2010 ] 

[57, Denmark 2010] 

[ 508, TFRN 2014] 

[ 614, UK 2013 ] 
[ 667, Spain 2011 ] 
[ 667, Spain 2011 ] 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.05–0.10 

0.01 
(4) 

0.035 (4) 

0.020 (3) 

0.028 (3) 

0.37 (1) (2) 

0.04–0.08 (1) 

0.078 (4)  NI 

0.035–0.038 
(3) 

0.117 (1) 
0.0342 
0.0318 

Section 4.6.1.1 Enriched cages 
Two removals per 
week. No manure 
drying 
Belts without 
drying 
Belts with drying 
At least two 
removals per 
week. No manure 
drying 
Two removals per 
week. No manure 
drying  
Three removals 
per week. No 
manure drying  
One or two 
removals a day. 
No manure drying  
One or two 
removals per 
week. No manure 
drying  
One removal per 
week. With dried 
manure on belt 
Two or three 
removals per 
week. With dried 
manure on belt  
One removal per 
week. No manure 
drying (5) 
Two removals per 
week. No manure 
drying (5)  
0.011–
Two removals per 
0.023 
week. With dried 
(6) 
manure on belt  
Section 4.6.1.2 Small groups in enriched cages 
One removal per 
week. With dried 
manure on belt  
One removals per 
week. No manure 
drying  
One removal per 
week. With dried 
manure on belt 
(1) Derived from measurements.  
(2) Calculated from a reported value of 219 ouE per 1 000 kg of live weight for an average weight of 1.7 kg.  
(3) Modelled values based on experiment results of Table 4.45 and a reference emission of 0.083 kg of 

0.03 (1)  
(0.017–
0.040) (6) 

0.044  
(0.017–
0.071 (6) 

0.010–0.040 
(4) 

0.102 (7) 
(1)  

0.102 (7) 
(1)  

0.078 (4)  NI 

0.0024 
(6) 

0.0017 
(6) 

[ 84, UK 2010 ] 

0.023 
(1) 

0.350 (1) 

0.040 (1) 

0.037 (6) 

0.034 (1) 

0.035 (4) 

0.079 (6) 

0.039 (6) 

0.150 (6) 

0.01 
(4) 

0.01 
(4) 

0.04 
(6) 

0.04 
(1) 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 68, Spain 2010 ] 

[ 69, Spain 2010 ] 

[ 63, Germany 2010] 
[ 474, VDI 2011 ] 

[ 63, Germany 2010] 

[ 635, Le Bouquin et al. 
2013 ] 

[67, Netherlands 2010] 

[ 500, IRPP TWG 2011 ] 

NH3/animal/year. 

(4) Modelled values (e.g. results based on N balance). 
(5) Fogging (see Section 4.8.3) was occasionally used during measurements.  
(6) Measured values. 
(7) Figures derived from the associated emission value of 30 ouE/(LU s) for an average weight of 1.7 kg. 
NB: NI = no information provided. 

302 

Intensive Rearing of Poultry or Pigs 

 
 
Chapter 4 

4.6.1.1 

Enriched cages 

Description 
Cages are enclosures with sloping floors made of welded wire mesh or plastic slats. ‘Furnished’ 
or ‘enriched’ cages provide laying hens with increased space  compared to  conventional cages 
and are equipped with structural features like perches, a nest box and litter or  a scratch area to 
stimulate  natural  behaviour.  Additional  equipment  is  available  for  feeding,  drinking  and  egg 
collection.  The  system  is  described  in  Section 2.2.1.1  and  a  cross  section  is  illustrated  in 
Figure 4.9. 

Source: [ 63, Germany 2010 ] 

Figure 4.9:  Scheme of rows of enriched cages for laying hens  

The cages are arranged vertically on three or more tiers and often organised in two groups, with 
an intermediate platform between the fourth and fifth tier [ 368, France 2010 ].  

A belt is placed under each tier for the removal of manure. When the collection belt is aerated 
by an air duct system, dried droppings with a dry matter content of at least 55 % are obtained 
compared to a dry matter content of 25–35 % without drying. High drying levels are difficult to 
reach when the manure is removed very frequently.  

The reference system for manure removal from enriched cages consists of a belt underneath the 
cages, with two removals a week without drying [ 508, TFRN 2014 ]. 

Achieved environmental benefits 
Ammonia,  odour,  methane  and  N2O  emissions  are  reduced  as  a  consequence  of  the  frequent 
manure  removal  and  of  the  possible  forced  drying.  Reductions  are  higher  with  more  frequent 
removal, but the effect is not directly proportional. 

Intensive Rearing of Poultry or Pigs 

303 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
The energy consumption increases with increasing frequency of use of the  operating conveyer 
belt and manure drying. As the removed  manure has a high N content, N2O emissions during 
storage, handling and application as fertiliser are possible.  

Environmental performance and operational data 
Ammonia  emissions  from  enriched  cage  systems  have  been  reported  to  be  between  0.010 kg 
and 0.10 kg NH3 per hen per year. The range of emissions is due to the different frequency of 
manure  removal,  by  non-ventilated  or  ventilated  manure  belts  placed  underneath  the  cages.  It 
has been estimated that increasing the frequency from twice a week to three times a week or to a 
daily removal allows for the reduction of ammonia emissions by 19 % and 43 %, respectively. 
Examples  of  the  effect  of  manure  removal  frequency  on  ammonia  emissions  are  reported  in 
Table 4.52 and Table 4.53. 

The  effect  on  ammonia  emissions  of  the  frequent  removal  of  manure  without  drying  by 
ventilated belts was reported from Denmark and is presented in Table 4.52. Measured emission 
levels  were  compared  to  a  reference  emission  factor  of  0.083 kg  NH3/ap/yr,  corresponding  to 
one removal of manure per week. 

Table 4.52:  Effect  of  increasing  the  manure  removal  frequency,  without  manure  drying,  on 
ammonia emissions from enriched cages in comparison with weekly manure removal  

Parameter 

Twice per week 

Three times per week 

Daily removal or 
twice per day 

Manure removal frequency 

Ammonia emissions  
reduction (%) 
Source: [ 56, Denmark 2010 ] [ 57, Denmark 2010 ]  

54–58 

66 

76 

The  effect  on  ammonia  emissions  of  the  frequent  removal  of  manure  (and  associated  costs) 
when belts are equipped with drying fans is presented in Table 4.53. Values are compared with 
a  technique  which  removes  manure  twice  per  week,  with  no  ventilated  belt  (no  drying), 
associated with an emission factor between 0.05 kg and 0.1 kg NH3/ap/yr.  

Table 4.53:  Effect  of  manure  removal  frequency,  with  manure  drying  on  ventilated  belts,  on 

ammonia emissions from enriched cages, and associated costs  

Manure removal frequency 

Parameter 

Twice per week  

Ammonia emission reduction (%) (1) 
Associated costs  
(EUR/kg NH3-N abated/year) 
(1) Reduction percentage depends on the ventilation rate of the drying fan. 
Source: [ 508, TFRN 2014 ] 

30–40 

0–3 

More than two times per 
week  
35–45 

2–5 

In Spain, it was measured that increasing the manure removal frequency from once to twice per 
week reduced ammonia emissions by 49 %, from an emission factor of 0.079 kg NH3/ap/yr to 
0.039 kg NH3/ap/yr. Methane and nitrous dioxide were also measured for weekly and biweekly 
manure removal from belts. Methane emissions were not affected by frequent manure removal 
but  by manure drying (31 % reduction), with a variation of the emission factor from 0.035 kg 
CH4/ap/yr  to  0.024  CH4/ap/yr.  The  increase  in  the  manure  removal  frequency  showed  a 
reduction of N2O emissions of 29 %, from 0.0024 kg N2O/ap/yr to 0.0017 kg N2O/ap/yr. 

In the UK, emissions per bird place per year are estimated for methane at 0.078 kg CH4/ap/yr 
and for PM10 at 0.01 kg/ap/yr.  

304 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Measured  odour  emissions  are  reported  to  be  equivalent  to  0.37  ouE/s  per  hen  (219  ouE/s  per 
1 000 kg  of  live  weight  for  an  average  weight  of  1.7 kg)  [  56,  Denmark  2010 ].  Energy 
consumption should not be significantly different from the values reported in Section 4.6.1.2.  

Technical considerations relevant to applicability 
These  systems  are  applied  in  both  new  and  existing  houses.  The  technique  can  replace 
conventional  cages,  without  the  need  for  a  significant  alteration  of  existing  buildings  
[ 508, TFRN 2014 ]. 

Economics 
Increasing  manure  removal  from  once  to  twice  a  week  is  more  efficient  than  increasing  the 
number of removals from two to three times per week. The economic effect of this practice is 
estimated  in  Table 4.54.  The  economic  value  of  the  savings  in  mineral  fertilisers  that  are 
allowed for by the increased nitrogen content in the manure are also taken into consideration. 
The  annual  cost  of  applying  frequent  manure  removal  (twice  per  week  compared  to  once  per 
week) is estimated to be less than 1 % of the total production costs [ 57, Denmark 2010 ]. 

Table 4.54:  Economic consequences of removing  manure  two or  three times per week compared 

to only once per week  

Combined additional 
cost 
excluding the value of the 
saved N 
EUR/layer hen/yr 

Combined additional 
cost 
including the value of the 
saved N 
EUR/layer hen/yr 

Additional costs 
excluding the value of the 
saved N 

EUR/kg N reduced 

No of 
hens (1) 

Frequency: 
twice/week 

Frequency: 
twice/week 

Frequency: 
twice/week 

0.08 
0.07 
0.07 
0.05 

12 000 
2 4000 
30 000 
48 000 
(1) For converting the reported Danish animal units to number of hens, a factor of 200 was used. 
Source: [ 57, Denmark 2010 ] 

0.05 
0.03 
0.03 
0.01 

2.8 
2.1 
2.1 
1.7 

Frequency: 
three 
times/week 
0.12 
0.08 
0.09 
0.07 

Frequency: 
three 
times/week 
0.16 
0.12 
0.13 
0.11 

Frequency: 
three 
times/week 
4.7 
3.5 
3.7 
2.9 

The  investment  required  varies  from  EUR 10–15  per  bird  place  in  Italy  [  83,  Italy  2010  ]  to 
EUR 12–15 in France, where an entire replacement of the existing sheds, with house rebuilding 
and equipment, may cost EUR 25 per bird place [ 368, France 2010 ]. In Spain, the extra cost 
associated with increasing the frequency of manure removal, without drying, from once to twice 
per week is equivalent to EUR 0.013/ap/yr [69, Spain 2010]. 

Driving force for implementation 
The  frequent  removal  of  the  manure  reduces  the  flies'  contamination  and  improves  animal 
welfare. 

Example plants 
Several farms in the UK are equipped with this type of system. In 2012, in France, 100 % of the 
laying hens were raised in enriched cages. One housing system with 60 000 places was reported 
for  Spain  and  two  housing  systems  of  100 000  places  were  reported  for  Italy,  in  the  Veneto 
region. 

Reference literature 
[56,  Denmark  2010]  [57,  Denmark  2010]  [  63,  Germany  2010  ]  [67,  Netherlands  2010]  [68, 
Spain 2010] [69, Spain 2010] [83, Italy 2010] [84, UK 2010] [ 368, France 2010 ] [ 508, TFRN 
2014 ] 

Intensive Rearing of Poultry or Pigs 

305 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.6.1.2 

Small groups in enriched cages 

Description 
This  consists  of  an  enriched  cage  system  providing  birds  with  a  larger  surface  area  per  bird, 
higher  cages  and  more  defined  areas  with  litter  and  nests  compared  to  the  minimum 
requirements for enriched cages defined by Directive 1999/74/EC. 

This housing system was developed for small groups of birds. Nevertheless, the colony size is 
not  fixed.  A  total  area  at  least  2.5 m2  is  provided,  of  which  800 cm2  are  usable  without 
restriction  (if  the  hen  weight  is  over  2 kg,  then  900 cm2  of  space  is  made  available),  in 
comparison with the minimum permitted usable cage area per hen of 600 m2 according to the 
provisions  of  Directive  1999/74/EC.  The  littered  and  the  nest  areas  cover  900  cm2  for  every 
group  of  10  (for  30  animals  or  more,  an  additional  90  cm2  per  animal  are  given).  The  cage 
height is at least 50 cm and at the trough side it is 60 cm. Each animal is provided with 15 cm of 
perches and 12 cm of feed trough. 

Manure belts placed under the cages allow for frequent manure removal from the shed. Forced 
manure drying can be performed on the manure belts by means of pipes that blow air over the 
droppings. 

Achieved environmental benefits 
Ammonia  emissions  are  reduced  by  frequent  droppings  removal,  and  even  more  with  forced 
drying. Dust emissions are lower compared to non-cage systems (but this mainly depends on the 
dust bath material). 

Cross-media effects 
The  increased  animal  movement  and  the  operation  of  belts  cause  higher  dust  emissions.  The 
energy use is higher with forced air drying. 

Environmental performance and operational data 
The manure from ventilated belts is removed weekly, or otherwise twice a week. The dry matter 
content  of  the  manure  at  the  time  of  removal  is  at  least  55 %,  in  the  case  of  air  drying.  The 
manure removed by the belts is stored outside the housing. When the store is not covered, the 
manure is further displaced to a storage depot. 

The air used for the forced air drying system should be fresh. Ventilation rates vary depending 
on  the  season:  in  the  cold  season,  air  volumes  from  0.5 m3/bird  place  per  hour  to  3.2 m3/bird 
place per hour are provided, and in the warm season volumes from 3.1 m3/bird place per hour to 
6.9 m3/bird  place  per  hour  are  provided.  In  the  Netherlands,  the  ventilation  rate  for  the  air 
drying  system  is  reported  to  be  equivalent  to  0.7  m3/h/bird,  with  a  minimum  temperature  of 
17 °C. 

For  each  bird  place  per  year,  emissions  of  0.15 kg  of  ammonia  and  0.04 kg  of  PM10  are 
associated with this system (see Table 4.51). If manure drying is applied, emissions are reduced 
to a range of 0.017–0.040 kg of ammonia per bird place per year and to 0.023–0.04 kg of PM10 
per bird place per year. Odour emissions are estimated to be in the range of 0.102–0.350 ouE per 
bird place per second [ 67, Netherlands 2010 ] [ 63, Germany 2010 ]. 

In Germany, labour requirements have been estimated at 0.085–0.12 hours/ap/yr, on the basis of 
a housing system with 30 000 bird places.  

Energy  consumption  is  considered  to  be  proportional  to  the  number  of  manure  removals  
[  434,  ITAVI  2001  ].  In  Germany,  the  reported  energy  requirements  are  in  the  range 
1.1 kWh/ap/yr to 1.8 kWh/ap/yr for two removals per week; the additional consumption for the 
manure belt ventilation ranging from 0.6 kWh/ap/yr to 1.3 kWh/ap/yr. Energy consumption for 
lighting is reported to be 0.52 kWh/ap/yr. 

306 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Technical considerations relevant to applicability 
The system is in use in consumer egg production only. 

Economics 
The investment requirement varies from EUR 16–20 per bird place in the Netherlands to about 
EUR 31.00 per bird place in Germany, for a housing system with 5 000–10 000 bird places. The 
corresponding  annualised  investment  costs  have  been  reported  as  EUR 2.4–3/ap/yr  for  the 
Netherlands  and  EUR 3.6/ap/yr  for  Germany.  The  average  extra  cost  for  a  new  installation 
reported  by  the  Netherlands  is  equivalent  to  EUR 7.9/ap/yr,  ranging  from  EUR 5.5/ap/yr  to 
EUR 9.5/ap/yr. Annual operating costs have been estimated in the Netherlands as EUR 0.1 per 
bird place. 

Driving force for implementation 
National  or  local  cage  ban  programmes  (Netherlands,  Germany)  are  the  driving  force  for 
implementation.  Animal  welfare  is  improved  compared  to  conventional  cages  and  standard 
enriched cages. 

Example plants 
Since  conventional  enriched  cages  are  not  allowed  in  the  Netherlands  and  in  Germany,  small 
group housing in enriched cages is used.  

Reference literature 
[ 63, Germany 2010 ] [ 67, Netherlands 2010 ] [ 434, ITAVI 2001 ] 

4.6.2 

Techniques for non-cage housing of laying hens 

Non-cage systems for egg production require a different management regime and therefore need 
to be considered separately from the cage housing systems. The legal requirements set within 
Directive 1999/74/EC on the welfare of laying hens and the market acceptation of systems that 
are considered animal-friendly have motivated the proliferation of these systems. A summary of 
the results of emission measurements is presented in Table 4.55 and Table 4.56. 

Intensive Rearing of Poultry or Pigs 

307 

 
 
 
 
 
 
 
 
 
 
 
[66, Germany 
2010 ] 
[ 474, VDI 
2011 ] 
[ 635, Le 
Bouquin et al. 
2013 ] 

Chapter 4 

Table 4.55:  Summary  of  relevant  reported  achievable  emissions  in  deep-litter-based  non-cage 

systems for laying hens 

NH3 

Description 

CH4  
(kg/ap/yr) 
Section 4.6.2.1.1. Forced ventilation system and infrequent manure removal (in the case of deep 
litter with a manure pit) 
Deep litter or deep pit 
with partial litter 

[ 508, TFRN 
2014 ] 

Odour 
(ouE/ap/s) 

Source 

PM10  

N2O  

0.3 

NI 

NI 

NI 

NI 

Deep litter with manure 
pit 

Deep litter, with manure 
pit and veranda  

Deep litter, with manure 
pit, veranda and free 
range 

0.3157 (1) 

NI 

0.006 
(2) 

0.12 (1)  0.143 (1) (3) 

0.3157 (4) 

NI 

NI 

0.12 (1)  0.143 (1) (3) 

[64, Germany 
2010 ]  

[65, Germany 
2010 ] 

0.347 (4) 

NI 

NI 

0.12 (1)  0.143 (1) (3) 

NI 

NI 

NI 

NI 

0.290 (4) 

0.158  
(0.071–
0.248) (5) 

Deep litter, with manure 
pit, manure removal once 
or twice a year, free range 
0.078 
Deep litter with deep 
(4) 
manure pit 
Section 4.6.2.1.2. Manure belt or scraper (in the case of deep litter with a manure pit) 
[70, 
Deep litter with manure 
Netherlands 
pit, with non-ventilated 
2010 ] 
manure belts (twice per 
week) 
Section 4.6.2.1.3. Forced air drying of manure via tubes (in the case of deep litter with a manure 
pit) 

0.052–0.068 
(5) 

0.34–0.61 
(4) 

[85, UK 2010] 

0.084 (4) 

0.020 (4) 

NI 

NI 

NI 

NI 

Deep litter system with 
forced air manure drying 

0.125 (1) 

NI 

NI 

NI 

NI 

[ 638, BE 
Flanders 2014 
] 

Section 4.6.2.1.4. Forced air drying of manure using perforated floor (in the case of deep litter 
with a manure pit) 
Deep litter system with 
perforated floor and 
forced drying 
(1) Derived from measurements. 
(2) Modelled values (e.g. results based on N balance). 
(3) Values have been calculated from an emission of 42 ouE/s per LU and an average weight for laying hens of 

[ 638, BE 
Flanders 2014 
] 

0.110 (5) 

NI 

NI 

NI 

NI 

1.7 kg. 

(4) Conclusion by analogy.  
(5) Measured values.  
NB: NI = no information provided. 

308 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 4 

Table 4.56:  Summary of relevant reported achievable emissions in aviary-based non-cage systems 

for laying hens 

Description 

NH3 

CH4  
(kg/ap/yr) 

N2O  

PM10   Odour 

Reference 

(ouE/ap/s) 

Section 4.6.2.2.1 Manure belts (in the case of aviaries)  

Non-ventilated belts 

Aviaries, perch design, 
manure belts, one 
removal a week 

Litter-based with 
aviaries, veranda and 
free range  

Aviaries, one removal 
a week 

Aviaries, two removals 
a week 

Aviaries, veranda, one 
removal a week 

0.250 (1) 

0.200 (1)  0.180 (1)  0.10 (1) 

NI 

[ 82, Austria 2010 
] 
 [ 373, UBA 
Austria 2009 ] 

0.08 (2) 

0.078 (3) 

NI 

0.02 (3) 

NI 

[ 86, UK 2010]  

0.091 (2) 

NI 

0.002 (4)  0.15 (2) 

0.102  
(2) (5) 

[60, Germany 
2010] 
[ 474, VDI 2011 ] 

0.056 (2) 

NI 

NI 

NI 

NI 

[ 474, VDI 2011 ] 

0.091 (3) 

NI 

0.002 (4)  0.15 (4) 

0.102  
(4) (5) 

[61, Germany 
2010] 
[ 474, VDI 2011 ] 

[ 474, VDI 2011 ] 

[ 474, VDI 2011 ] 

[ 474, VDI 2011 ] 

[62, Germany 
2010] 
[ 474, VDI 2011 ] 

[ 474, VDI 2011 ] 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.100 (3) 

0.046 (2) 

0.046 (2) 

0.056 (3) 

0.0616 (3) 

0.0506 (3) 

0.102  
(2) (5) 

0.002 (4)  0.15 (2) 

Aviaries, veranda, two 
removals a week 
Aviaries, veranda and 
free range, one removal 
a week  
Aviaries, veranda, 
outdoor, two removals 
a week  
Ventilated belts 
Aviaries, one removal 
per week 
Aviaries, veranda, one 
removal per week  
Aviaries, veranda, 
outdoor, one removal 
per week  
Aviaries, perch design, 
ventilation 0.7 m3/h, 
one removal per week 
(30–35 % slatted floor) 
Aviaries, perch design, 
ventilation 0.7 m3/h, 
one removal per week, 
(55–60 % slatted floor) 
Aviaries, perch design, 
ventilation 0.2 m3/h, 
two removals per week 
(50 % slatted floor) 
(1) Modelled values (e.g. results based on N balance).  
(2) Derived from measurements. 
(3) Values derived by expert judgement based on conclusions by analogy.  
(4) Measured values.  
(5) Values have been calculated from an emission of 30 ouE/s per LU and an average weight for laying hens of 

0.037 
(0.0356–
0.0371) (4) 

0.019–0.025 
(4) 

0.065 
(3) 

0.065 
(3) 

0.065 
(3) 

0.055 (2) 

0.34 (2) 

0.34 (2) 

0.34 (3) 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 72, Netherlands 
2010 ] 

[ 73, Netherlands 
2010 ] 

[71, Netherlands 
2010 ] 

[ 474, VDI 2011 ] 

1.7 kg. 

NB: NI = no information provided. 

Intensive Rearing of Poultry or Pigs 

309 

 
 
 
 
  
 
 
Chapter 4 

4.6.2.1 

Deep litter or floor regime systems  

4.6.2.1.1 

Forced ventilation system and infrequent manure removal (in case 
of deep litter with a manure pit) 

Description 
At least a third of the floor area is covered with litter (e.g. sand, wood shavings, straw). The rest 
of  the  floor  area  is  arranged  as  a  pit  covered  with  slats  to  collect  droppings  over  the  laying 
period. The deep litter system is combined with infrequent manure removal, e.g. at the end of 
the cycle (no belt  or scraper is  used). Manure is  removed  from  the  scratching  area by  mobile 
means. Laying nests, feeders and water supply are placed over the slatted area to keep the litter 
dry  (see  Figure 4.10). The housing  system  can  be  combined  with  a  veranda  and/or free-range 
system. 

Achieved environmental benefits 
Ammonia  emissions  can  be  reduced  by  ensuring  a  minimum  dry  matter  content  of  around  
50–60 %.  This  is  achieved  by  an  appropriate  forced  ventilation  system  (e.g.  fans  and  air 
extraction can be placed at floor level), so that a current is generated to dry the droppings below 
the slatted area. 

Cross-media effects 
The  ammonia  emissions  associated  with  this  technique  are  generally  higher  than  those 
associated with other non-cage systems. There are more management requirements compared to 
cage systems. 

Environmental performance and operational data 
Reported  ammonia  emissions  range  from  0.071 kg  to 0.315  kg  NH3/animal  place/year, and to 
0.347 kg/bird place per year in the case where free-range systems are available (see Table 4.55). 
In the case of a free-range system, an increase in NH3 emissions of about 10 % is estimated. 

Technical considerations relevant to applicability 
Retrofitting of an existing cage system may not be applicable due to excessive costs.  

Economics 
Reported  information  on  costs  associated  with  the  implementation  of  a  deep  litter  housing 
system with a deep pit and partly littered floor is presented in Table 4.58. Data on the resources 
demand are presented in Table 4.59. 

Driving force for implementation 
This technique is more animal-friendly compared to enriched cages.  

Example plants 
In  the  system  typically  used  in  France,  manure  is  stored  under the slatted floor  for the  whole 
period and is removed at the end [ 624, IRPP TWG 2013 ]. 

Reference literature 
[ 43, COM 2003 ] [ 624, IRPP TWG 2013 ] 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.6.2.1.2 

Manure belt or scraper (in case of deep litter with a manure pit)  

Description 
The house floor is partly covered with litter, such as sand, wood shavings or the straw used for 
scratching and dust bathing. The littered floor occupies a third to two thirds of the total surface. 
The remainder consists of a slatted floor, the area of which is, at a maximum, two thirds of the 
available  space,  as  required  by  Directive  1999/74/EC.  The  difference  in  height  between  the 
bedding  and  slatted  floor  is  maximum  50  cm.  Each  compartment  (level)  can  have  its  own 
climate  control  system  [  70,  Netherlands  2010  ].  Perches,  laying  nests,  feeding  and  drinking 
systems are situated above the manure pit to keep the litter dry.  

Underneath the slats, there is a deep pit for manure, 80–90 cm in height [ 508, TFRN 2014 ], 
which can be equipped with scrapers or belts, with or without aeration. The removal by scraper 
is periodical; the removal by belts is frequent. If the belts are ventilated, the manure removal can 
be weekly; otherwise, it takes place twice a week. The bedding over the solid area is distributed 
at  the  beginning  of  the  laying  cycle  and  litter  is  collected  at  its  end  by  mobile  means.  A 
schematic  representation  of  a  deep  litter  system,  with  a  manure  pit  and  partly  slatted  floor  is 
shown in Figure 4.10. 

Source: [ 64, Germany 2010 ] 

Figure 4.10:  Schematic representation of a deep litter system with a manure pit for laying hens 

In general, the stocking density in these housing systems is up to 9 hens per m2 of floor area. 
Additional  structures  can be  added  inside  or  outside  the  house  for  better animal  comfort, like 
verandas  and  free-range  system  (see  Section  2.2.1.2.3).  A  schematic  representation  of  the 
system is shown in Figure 4.11. 

Intensive Rearing of Poultry or Pigs 

311 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 64, Germany 2010 ] 

Figure 4.11:  Schematic representation of a deep litter system with a manure pit, a veranda and a 

free-range system for laying hens 

Achieved environmental benefits 
Ammonia  emissions  are  reduced  by  the  frequent  removal  of  the  manure  from  the  belts,  in 
particular when combined with manure drying on the belt through forced ventilation, achieving 
a high dry matter content of the litter in the top compartment. 

No  differences  in  emissions  have  been  reported  from  the  use  of  verandas.  Where  free-range 
systems  are  available,  ammonia  emissions  are  expected  to  be  about  10 %  higher  than  those 
produced indoors. 

Cross-media effects 
As manure is obtained with a dry matter content of up to 80 %, a lot of dust can develop in the 
house  as  the  birds  move  around  freely.  The  use  of  manure  belts  for  the  removal  and  forced 
ventilation  for  manure  drying  are  associated  with  energy  consumption  for  the  production  of 
electricity and related indirect emissions.  

Environmental performance and operational data 
For  the  birds,  this  system  offers  an  almost  full  opportunity  to  display  natural  behavioural 
patterns. The house interior can be structured to offer different functional areas. This makes the 
system more bird-friendly than cage confinement. Also, from a technical perspective, uniform 
house  ventilation  and  lighting  can  be  achieved  more  easily  than  in  a  cage  housing,  and,  also, 
bird observation is simpler. The ammonia emissions vary from 0.052 kg to 0.320 kg NH3/bird 
place  per  year,  to  0.352 kg/bird  place  per  year  where  free-range  systems  are  available  (see 
Table 4.55). In the case of a free-range system, an increase in NH3 emissions of about 10 % is 
estimated. 

In the UK, methane emissions have been estimated at 0.078 kg/bird place per year. In Germany, 
nitrous  oxide  emissions  are  estimated  at  0.006 kg  N2O/bird  place  per  year,  for  a  deep  litter 
system  without  a  manure  belt  or  scraper.  Odour  emissions  have  been  measured  from 
0.34 ouE/bird/second to  0.61 ouE/bird/second  [  70,  Netherlands  2010  ].  Emissions  of  the  PM10 
fraction  of  dust  that  originate  in  belt  systems  can  vary  from  0.020 kg  to  0.084 kg  and  to 
0.240 kg per bird place per year.  

Feeding  and  drinking  features,  as  well  as  the  space  per  animal,  comply  with  Article  4  of 
Directive  1999/74/EC. The  ventilation rates  vary  depending  on the  season: in the  cold season 
rates from 0.5 m3 to 2.8 m3 per bird per year are applied, whereas in the warm season 3.5 m3 to 
6.9 m3 per bird per year may be needed. Some examples of ventilation rates applied in Germany 
and in the Netherlands are reported in Table 4.57. 

312 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Table 4.57:  Ventilation rates applied in deep litter housing systems for laying hens 

Applied ventilation rates 

Chapter 4 

Cold season 
Warm season 
Source: [ 63, Germany 2010 ] [ 64, Germany 2010 ] [ 65, Germany 2010 ] [ 70, Netherlands 2010 ]  

Germany 
m3/h per bird place 
0.5–0.8 
3.1–6.9 

Netherlands 
m3/h per bird place 
1.5–2.8 
3.5–4.4 

If natural ventilation is applied, the energy input is relatively low; however, under the climatic 
conditions of most areas in the European Union, natural ventilation is not applicable. 

In  Germany,  the  energy  consumption  is  reported  as  0.52 kWh/ap/yr  for  lighting  and 
2.2 kWh/ap/yr for ventilation, when non-ventilated belts are used. In the case of ventilated belts, 
the energy consumption is reported as 3.18 kWh/ap/yr. 

Technical considerations relevant to applicability 
A  change  from  a  cage  system  to  this  floor  regime  would  require  a  complete  revision  of  the 
system.  The  width  of  the  existing  house  is  the  most  limiting  factor  for  retrofitting  existing 
constructions.  In  existing  houses,  the  placement  of  a  manure  belt  or  scraper  in  a  manure  pit 
underneath the slatted floor is not always possible and involves additional costs.  

Economics 
The  basic  investment  required  is  in  the  range  of  EUR 20.40  to  EUR 37.00  per  bird  place.  If 
additional  verandas  or  free  ranges  are  added,  the  investment  increases  to  EUR 44.40  per  bird 
place. Reported information on costs associated with the implementation of a deep litter housing 
system  with  a  manure  pit  is  presented  in  Table 4.58.  Data  on  the  resources  demand  are 
presented in Table 4.59. 

Table 4.58:  Cost data associated with different deep litter systems with a manure pit  

System 
configuration 

Investment 
costs 

Annualised 
investment 
costs 

Annual 
operating 
costs 
EUR/ap/yr 

Total 
costs 

Source 

EUR/bird place 
37 

4.7 

3.9 

3.7 

3.2 

38–59 (1) 

With scraper 
With manure belt 
and veranda 
No manure belt or 
scraper, with 
veranda and free 
range 
With non-
ventilated manure 
belt 
(1) Values ranging for housing capacities from 3 000 to 9 000 bird places. 
NB: NI = no information provided. 

20.4 
(18.9–21.9) 

3.05 
(2.85–3.3) 

44.4 

0.05 

3.9 

NI 

7.1 

8.4 

[ 64, Germany 2010 ] 

[ 65, Germany 2010 ] 

NI 

[ 66, Germany 2010 ] 

3.1 

[ 70, Netherlands 2010] 

Table 4.59:  Resource demand associated with the different deep litter systems with a manure pit  

System configuration 

Without veranda or free range 
With veranda 
With veranda and free range 

Labour  
h/ap/yr 
0.21 
0.19–0.26 
0.24–0.41 

Bedding material 
kg/ap/yr 
0.29 
0.5 
0.5 

Source 

[ 64, Germany 2010 ] 
[ 65, Germany 2010 ] 
[ 66, Germany 2010 ] 

Intensive Rearing of Poultry or Pigs 

313 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
The  proliferation  of  alternative  systems  has  been  stimulated  by  welfare  legislation  on  laying 
hens and by some changes in the market towards the consumption  of eggs from more animal-
friendly systems. 

Non-environmental benefits are achievable; the housing system is animal-friendly due to more 
space being provided to the birds (compared to enriched cages) and to additional characteristics, 
like perches, separate functional areas, scratching areas, a dust bath and external/climate stimuli. 

Example plants 
In the Netherlands, about 5 % of laying hens in 2009 were reared with this system. In Germany, 
the system is widespread. 

Reference literature 
[  39,  Germany  2001  ]  [  44,  IKC  2000  ]  [  63,  Germany  2010  ]  [  64,  Germany  2010  ]  [  65, 
Germany 2010 ] [ 66, Germany 2010 ] [ 70, Netherlands 2010 ] [ 85, UK 2010 ] [ 506, TWG 
ILF BREF 2001 ] [ 508, TFRN 2014 ] 

4.6.2.1.3 

Forced air drying of manure via tubes (in case of deep litter with a 
manure pit) 

Description 
The deep litter system with forced air manure drying is based on the previous system but here 
the  ammonia  emissions  are  reduced  by  applying  forced  ventilation  as  shown  in  Figure 4.12. 
Forced ventilation is applied through tubes that blow 1.2 m3 of air per bird place per hour at a 
temperature of 17–20 °C (pullets and layers have different requirements) over the manure stored 
under the slats or over the manure being removed by the (aerated) belts [ 467, BE 2010 ]. 

Source: [ 44, IKC 2000 ] 

Figure 4.12:  Deep litter systems with forced drying via tubes under the slatted floor 

Achieved environmental benefits 
The  application  of  forced  ventilation  and  the  quick  drying  of  the  manure  reduce  ammonia 
emissions. Frequent removal with (aerated) manure belts can give even lower emission levels. 
Reduced odour levels can be expected.  

Cross-media effects 
The energy input in this system is high because a heating system must be installed to achieve 
the  temperature  necessary  in  the  tubes  (20 °C).  Extra  energy  is  also  required  to  maintain  the 

314 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

airflow. Air is drawn in through inlets in the side walls and though an open ridge construction in 
the roof. Aeration may trigger nitrification reactions that may result in an increased emission of 
N2O. In general, due to the dried manure, higher dust emissions are expected. 

Environmental performance and operational data 
Management  of  this  system  is  principally  the  same  as  for  the  reference  deep  litter  design. 
Ammonia emissions of 0.125 kg NH3 per bird place per year are associated with this system in 
the Netherlands [ 640, Netherlands 2013 ]. The associated ammonia reduction is 60 % compared 
to the deep litter system (0.315 kg NH3 per bird place per year). 

Technical considerations relevant to applicability 
The  system  can  only  be  used  in  laying  hen  houses  with  enough  space  underneath  the  slats. 
Traditionally the manure pit has a depth of 80 cm but when using this system it is necessary to 
add an extra 70 cm. The experience of farmers already using the deep floor system is that this 
type of system requires very little change to the traditional design. 

Economics 
The total cost for implementing this system in Belgium (Flanders) is EUR 32/bird place (VAT 
excluded),  which  corresponds  to  an  extra  cost  of  EUR 3.15/bird  place  in  comparison  with  a 
conventional  deep  pit  system  (11 %  higher).  The  additional  energy  requirements  for  the 
ventilation amount to EUR 0.17/ap/yr [ 265, BE Flanders 2010 ]. 

Example plants 
In the Netherlands, around 1 129 000 birds are housed in this type of system, about 3 % of the 
total  Dutch  laying  hen  population  [  468,  CBS  2011  ].  In  Belgium  (Flanders),  10  systems 
(including farms above and below the capacity threshold set by Directive 2010/75/EU, Annex I) 
have been built since 2004. 

Reference literature 
[ 41, Netherlands 2001 ] [ 44, IKC 2000 ] [ 265, BE Flanders 2005 ] [ 467, BE 2010 ] [ 468, 
CBS 2011 ] [ 506, TWG ILF BREF 2001 ] [ 640, Netherlands 2013 ] 

4.6.2.1.4 

Forced air drying of manure using perforated floor (in case of deep 
litter with a manure pit) 

Description 
A perforated floor is placed in the manure pit underneath a partially elevated slatted floor, which 
allows forced air blowing from below to dry the manure on top of it (Figure 4.13).  

The house is a simple traditional building. The bedding area is 30 % and slatted floor 70 % of 
the total area. The laying nest area is included in the slatted floor area. The perforated floor (air 
channel) is situated at least 10 cm from the bottom of the pit (aeration space). The manure pit 
available  under  the  slatted  area  must  be  large  enough  to  store  and  dry  the  manure  generated 
during the entire production period, so the total available height between the slats and perforated 
floor  should  be  at  least  80  cm.  The  perforated  floor  must  be  able  to  support  a  weight  of 
400 kg/m2 (including the weight of the dry manure). This false floor should be evenly perforated 
and the total area of air openings should be at least 20 % of the surface. 

Intensive Rearing of Poultry or Pigs 

315 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 44, IKC 2000 ] 

Figure 4.13:  Deep litter system with perforated floor and forced manure drying  

Achieved environmental benefits 
Ammonia emissions are reduced as an effect of the manure drying. 

Cross-media effects 
Higher energy input is required because of the forced ventilation. Manure aeration may trigger 
nitrification reactions that may cause an increase of N2O emissions. In general, due to the dried 
manure, higher dust emissions are expected. 

Environmental performance and operational data 
The  layer  droppings  fall  through  the  slats  onto  the  perforated  floor.  At  the  beginning  of  the 
laying period, on top of the perforated floor, a 4 cm thick bed of wood shavings or sawdust is 
scattered. Air from the shed is blown from beneath through the small openings in the perforated 
floor under the manure. To dry the manure properly, at least two ventilators with  a minimum 
capacity  of  around  7 m3  air/hour  and  capable  of  overcoming  a  high  pressure  resistance 
(minimum  90 Pa)  need  to  be  installed.  Different  placement  options  are  possible  for  the 
ventilation units (see Section 4.6.5.4). 

The manure stays on the perforated floor for about 50 weeks (laying period) and is then taken 
out of the house. The manure is dried constantly by the continuous flow of air. The dry matter 
content of the manure is about 75 %.  

Bedding is spread at the start of the flock and twice more during the rearing period, in order to 
maintain  a  wood  shavings  bed  density  of  0.7 kg/m2.  Functional  areas  are  above  the  dropping 
area. Reported values of ammonia emissions are 0.110 kg per bird place per year. The drinking 
facilities must be installed on top of the slats, but a good design of the tubes prevents the loss of 
water. 

Technical considerations relevant to applicability 
The technique is applicable to new houses but it could also be installed in existing houses, but at 
an additional cost. 

316 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Economics 
The investment required is EUR 1.20 per bird place and annual costs are EUR 0.18 per bird (see 
also Section 4.6.5.4). 

Chapter 4 

Driving force for implementation 
No information provided. 

Example plants 
In the Netherlands, about 276 000 bird places are built with this technique, representing 1 % of 
the total Dutch availability [ 468, CBS 2011 ]. 

Reference literature 
[ 44, IKC 2000 ] [ 108, BE Flanders 2010 ] [ 111, Netherlands 2010 ] [ 468, CBS 2011 ] [ 506, 
TWG ILF BREF 2001 ] [ 545, Netherlands 2002 ]  

4.6.2.2 

Manure belts (in case of aviary) 

4.6.2.2.1 

Manure belts (in case of aviary), with or without a veranda and free-
range system 

Description 
The  building  is  divided  into  different  functional  areas  for  feeding  and  drinking,  laying  eggs, 
scratching and resting. Nests to lay eggs can be integrated or not integrated with the equipment 
(see  Section  2.2.1.2.2).  Functional  areas  are  arranged  above  the  droppings  area.  The  indoor 
available  surface  area  is  increased  by  means  of  elevated  slatted  floors,  combined  with  tiers, 
allowing a stocking density of up to 18 hens per m2 of floor area. A minimum of two tiers are 
stacked over the slatted floor. The slat coverage can range from 30–35 % up to 55–60 % of the 
total  available  area.  The  remainder  of  the  floor  is  typically  littered  (e.g.  with  straw  or  wood 
shavings). 

Manure  belts  collect  and  remove  the  droppings  under  the  slatted  floors.  The  belts  can  be 
equipped  with  plastic  pipes,  through  which  forced  air  is  blown  in  order  to  dry  the  manure 
(0.2 m3/h per animal, at a minimum temperature of 18 °C, or 0.7 m3/h per animal at a minimum 
temperature of 17 °C). Typically, manure is removed at least twice a week with non-ventilated 
belts  and  once  a  week  when  pre-drying  is  carried  out  on  ventilated  belts. The  removal  of  the 
litter that is not conveyed by belts is done every 3 months [ 82, Austria 2010 ] or at the end of 
the cycle. 

The housing system can be combined with a veranda and free ranges. A scheme of the system is 
given in Figure 4.14. 

Intensive Rearing of Poultry or Pigs 

317 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 60, Germany 2010 ] 

Figure 4.14:  Scheme of a litter-based aviary for laying hens  

Elements  typical  of  aviary  systems  are  placed  in  the  house;  birds  can  use  the entire  available 
space. Variations with a fully solid floor or partly slatted floor are reported. In the first case, the 
aviaries  rest  on  a  continuous  solid  littered  floor;  in  the  second  case,  aviaries  are  placed  on  a 
slatted floor in various combinations as shown in Figure 4.15. The extension of the slatted floor 
in  relation  to  the  total  available  surface  is  also  variable.  In  the  case  of  a  partly  slatted  floor, 
manure  belts  are  installed  underneath  the  floors,  where  manure  can  be  dried  with  forced  air 
through pipes placed above or along the belts. In the solid floor variation, the droppings area is 
equipped with a manure belt. The scratching area is cleaned by mobile means.  

When manure belts are equipped with forced air drying (0.2 m3/h/bird at 20 °C, with removal 
once  per  week),  a  minimum  dry  matter  content  of  55 %  is  reported.  The  birds  are  kept  at 
variable densities, from 0.030 m3 to 0.062 m3 per head. 

318 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 4 

Source: [ 78, Netherlands 2010 ] 

Figure 4.15:  Combinations of slatted floors in aviaries  

Achieved environmental benefits 
The  frequent  removal  and  the  possible  fast  pre-drying  of  droppings  by  ventilated  belts  allow 
ammonia  emissions  reduction.  Odour  emissions  are  also  reduced  due  to  the  pre-drying  of  the 
manure and/or the frequent manure removal. 

Aviary  systems  with  manure  belts  for  frequent  collection  and  removal  of  manure  to  closed 
storage  reduce  ammonia  emissions  by  70–85 %  with  non-ventilated  manure  belts  and  by  80–
95 % with ventilated manure belts compared to the deep litter systems [ 508, TFRN 2014 ]. 

Cross-media effects 
If access to the litter is not restricted, more dust is emitted compared to cage systems, due to the 
presence of litter material and to the increased animal activity. If the system is designed such 
that  the  hens  only  have  access  to  the  litter  via  the  lowest  aviary  level,  less  dust  is  emitted. 
Furthermore, due to the dried manure higher dust emissions are expected.  

Additional  electric  energy  consumption  is  needed  for  the  operation  and  ventilation  of  the 
manure belts, which is associated with indirect emissions. 

Compared  to  the  cage  systems,  there  are  more  management  requirements.  On  a  daily  basis, 
these operations should be performed: control of animals and bedding; collection of eggs that 
have  been  laid  from  the  nests;  and  provision  of  access  to  the  free  range  during  the  daytime. 
Additionally, regular care of the free-range systems and of the parasitological conditions needs 
to be followed.  

Intensive Rearing of Poultry or Pigs 

319 

 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
Depending  on  the  manufacture  and  whether  the  manure  is  removed  once  or  twice  per  week, 
ammonia  emissions  with  the  use  of  ventilated  manure  belts  are  in  the  range  of  0.019 kg  and 
0.055 kg per animal place per year. Emissions from non-ventilated belts have been measured as 
between  0.060 kg  and  0.290 kg  per  animal  place  per  year  (see  Table 4.56  for  a  complete 
summary of the provided emission data). 

Nitrous oxide emissions have been estimated in Germany to be about 0.002 kg N2O per animal 
place  per  year.  PM10  emissions  are  in  the  range  of  0.065 kg  to  0.150 kg  per  animal  place  per 
year. In the Netherlands, odour emissions are estimated at 0.34 ouE per animal place per year. 

In Austria, emission data have been calculated for an aviary system operating with manure belts 
and removal once per week, manual removal of the litter every 3 months and with storage of the 
manure  in  a  closed  barn  until  further  transportation.  The  results  of  the  calculation  showed 
ammonia emissions at 0.25 kg/ap/yr, methane emissions at 0.2 kg/ap/yr, nitrous oxide emissions 
at 0.18 kg N2O/ap/yr and dust emissions at 0.1 kg PM10/ap/yr [ 82, Austria 2010 ] [ 373, UBA 
Austria  2009  ].  In  the  UK,  emissions  are  estimated  as  follows:  ammonia  0.08/ap/yr;  methane 
0.078 kg/ap/yr; PM10 0.02 kg/ap/yr.  

According to information from Germany, an aviary system designed to allow the hens to only 
have access to the litter via the lowest aviary level has lower dust emissions (PM10 emissions 
decrease from 0.15 kg/ap/yr to 0.039 kg/ap/yr) [ 474, VDI 2011 ]. 

Electric consumption per animal place per year is around 0.52 kWh for lighting and 2.1 kWh for 
running  the  system.  Additional  consumption  for  the  ventilation  of  the  manure  belts  is  around 
1.6 kWh/animal place per year [ 60, Germany 2010 ]. The typical ventilation rates reported for 
aviary systems equipped with manure belts are presented in Table 4.60. 

Table 4.60:  Reported  ventilation  rates for  aviary  systems  for  laying  hens  equipped  with  manure 

belts 

Ventilation rate 
(m3/ap/h) 

Cold season 
Warm season 
Source: [ 60, Germany 2010 ] [ 61, Germany 2010 ] [ 62, Germany 2010 ] 

Germany 
0.5–0.8 
3.1–6.9 

Netherlands 
1.9–2.26 
2.8–3.46 

[ 71, Netherlands 2010 ] [ 72, Netherlands 2010 ] [ 73, Netherlands 2010 ] 

Reported ventilation rates for forced air drying are 0.2 m3/h per bird, at a minimum temperature 
of 18 °C and a slat coverage of 45–55 %, or 0.7 m3/h per animal at a minimum temperature of 
17 °C and a slat coverage of 30–35 % [ 72, Netherlands 2010 ] [ 73, Netherlands 2010 ]. 

In the case of aviary systems equipped with a free range, an increase of NH3 emissions of about 
10 %  is  estimated;  however,  in  general  no  major  differences  are  reported  for  ammonia 
emissions for different configurations [ 571, Eurich-Menden et al. 2011 ].  

Technical considerations relevant to applicability 
No  limitations  exist  for  applying  the  systems  in  either  small  or  large  farms.  Retrofitting  an 
aviary in existing houses depends mostly on the shed width. 

Economics 
The cost efficiency of the technique is given  as EUR 1 to EUR 5 per kg of NH3-N abated for 
non-ventilated manure belts and EUR 1 to EUR 7 per kg of NH3-N abated for ventilated manure 
belts [ 508, TFRN 2014 ]. 

320 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The investment cost associated with the installation of an aviary system and a ventilated manure 
belt beneath the slats is reported from the Netherlands as between EUR 12.6 and EUR 16.5 per 
bird  place;  the  annualised  extra  investment  costs  range  from  EUR  1.9  to  EUR  2.5  per  bird 
place/yr  and  the  annual  extra  operating  costs  from  EUR  0.11  to  EUR  0.2  per  bird  place/yr, 
leading to an total annual extra cost between EUR 2.33 and 2.36 per bird place [ 71, Netherlands 
2010] [ 72, Netherlands 2010 ] [ 73, Netherlands 2010 ]. Investment costs for the construction 
of  a  building  intended  for  an  aviary  system  (30 000  hens,  18  m2/bird)  are  calculated  at 
EUR 10.75  per  bird  place (excluding  all  structures  within  housing,  feeding  silos,  egg  storage)  
[ 589, Netherlands 2010 ]. 

A  summary  of  cost  data  given  by  Germany  related  to  different  configurations  of  the  aviary 
systems equipped with no ventilated manure belts is given Table 4.61. 

Table 4.61:  Summary of cost data in Germany for different configurations of aviary systems for 

laying hens 

System 
configuration 

No ventilated belt, 1–
2 removals per week 
No ventilated belt, 
with veranda, 1–2 
removals per week 
No ventilated belt, 
with veranda and free 
range, 1–2 removals 
per week 

Investment  
costs  

EUR/ap 

Annualised 
investment costs 

Annualised 
operating 
costs 
EUR/ap/yr 

Total 
costs 

Source 

31 

31 

3.6 

3.6 

2.8 

2.9 

6.4 

[ 60, Germany 2010 ] 

6.5 

[ 61, Germany 2010 ] 

28–38 

4.4 

4 

8.4 

[ 62, Germany 2010 ] 

The  labour  demand  associated  with  the  implementation  of  aviary  systems  is  reported  to  be 
between 0.16 and 0.19 h/ap/yr. Energy consumption is reported as 0.52 kWh/ap/yr for lighting, 
2.1 kWh/ap/yr for the use of non-ventilated belts and 3.7 kWh/ap/yr for ventilated belts. 

The  quantity  of  bedding  material  used  with  non-ventilated  belts  and  one  or  two  manure 
removals per week is between 0.075 kg/ap/yr and 0.16 kg/ap/yr; values increase in the case of 
configurations  that  include  a  veranda  (0.26 kg/ap/yr),  or  a  veranda  plus  a  free  range 
(0.29 kg/ap/yr). 

Driving force for implementation 
Aviary houses constitute an alternative housing system after the ban of conventional cages. The 
system  allows  reasonable  egg  losses  and  a  high  stocking  density.  Aviaries  are  more  animal-
friendly than enriched cages, allowing the birds to manifest their natural behaviour more easily, 
due to the increased  space provided per bird and the improved benefits of perches, functional 
areas, scratching areas, dust baths and external climate/stimuli. 

Example plants 
In the Netherlands, about 15 % of the farms in 2008 were equipped with systems of this type. 
About 50 farms in Belgium (Flanders) are equipped with this system.  

Reference literature 
[  60,  Germany  2010  ]  [  61,  Germany  2010  ]  [  62,  Germany  2010  ]  [  71,  Netherlands  2010  ]  
[  72,  Netherlands  2010  ]  [  73,  Netherlands  2010  ]  [  82,  Austria  2010  ]  [  86,  UK  2010  ] 
[  373,  UBA  Austria  2009  ]  [  467,  BE  2010  ]  [  474,  VDI  2011  ]  [  508,  TFRN  2014  ]  [  571, 
Eurich-Menden et al. 2011 ] [ 589, Netherlands 2010 ] 

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Chapter 4 

4.6.2.2.2 

Underfloor manure drying (in case of aviary) 

Description 
Aviaries are built with a deep litter under a slatted floor. In the pit, manure drying is performed 
and the manure is stored during the egg-laying period which lasts typically 13–15 months. The 
system  differs  from  traditional  houses  by  having  a  manure  pit  at  least  70 cm  deep  (see 
Figure 4.16).  A  ventilation  outlet  circulates  heated air  in  the  manure  pit  to  dry  the  droppings. 
Drying creates a crust on top of the manure which reduces the degradation of urea to ammonia 
and ammonium. 

Source: [ 59, Denmark 2010 ] 

Figure 4.16:  Scheme of the underfloor manure drying system in aviary with a deep pit  

Achieved environmental benefits 
A reduced volatilisation of ammonia and odour compounds is achieved and as a consequence 
better indoor air quality. A higher nitrogen content in the fertilising manure results. The increase 
in the nitrogen content of the manure allows it to be used as a substitute for mineral fertiliser. 

Cross-media effects 
Additional energy is required to heat and blow air onto the pit surface. 

Environmental performance and operational data 
With  the  droppings  drying,  the  manure  dry  matter  content  is  increased  from  the  typical  40 % 
(without drying) to about 80 %. The energy consumption related to manure drying is reported as 
130 kWh per ‘animal unit’ (one Danish ‘animal unit’ is defined as the livestock that produces 
manure with a content of 100 kg of N), which corresponds to approximately 0.65 kWh per bird 
(an equivalent of 200 laying hens to one Danish animal unit is assumed). The required energy 
consumption is also reported from Denmark as 0.78 kWh/ap/yr.  

Heated ventilation is only required when the indoor house temperature falls below 20 °C. The 
best  results  are  achieved  by  ventilating  1.2 m3  of  air  per  animal  unit  per  hour,  allowing  a 

322 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

possible reduction of 60 % of ammonia emissions in comparison with a similar system without 
the underfloor manure drying. 

Technical considerations relevant to applicability 
The system  is  typically  implemented in  new  constructions.  Manure  drying  can be  installed  in 
existing buildings, but deepening manure pits is a prerequisite for this technique. 

Economics 
The accumulated additional cost of the manure drying is estimated to be approximately 2 % or 
1.5 % of the total annual cost of maintaining each layer hen, depending on whether the value of 
the saved nitrogen is excluded or included in the calculation. Reported cost data from Denmark 
indicate an  additional  investment  cost  of  EUR 0.40/bird/yr,  excluding  the  benefits  from  saved 
nitrogen  (less  mineral  fertiliser),  corresponding  to  EUR 3.9/kg  N  reduced.  Annual  costs, 
including the benefits from saved nitrogen are reported as EUR 0.23/bird/yr, corresponding to 
EUR 2.13/kg N reduced [ 58, Denmark 2010 ]. 

Driving force for implementation 
One driving force is the improved indoor environment, due to the reduced ammonia and odour, 
as a consequence of the dry manure below the slats, resulting in improved animal welfare. Dried 
manure is easier to handle and remove. Increased fertiliser value is another driving force, due to 
the higher nitrogen content. 

Example plants 
Different configurations of the manure drying technique are applied in the Netherlands and  in 
Germany.  

Reference literature 
[ 58, Denmark 2010 ] [ 59, Denmark 2010 ] 

4.6.2.3 

Forced air drying of litter using indoor air (in case of solid floor 
with deep litter) 

Description 
The deep litter system, without a manure pit, is equipped with different ventilation systems used 
to  dry  the  litter.  These  systems  are  also  used  in  the  housing  systems  for  broilers  (see 
Section 4.6.4.2.1). 

Achieved environmental benefits 
See Section 4.6.4.2.1. 

Cross-media effects 
See Section 4.6.4.2.1. 

Technical considerations relevant to applicability 
See Section 4.6.4.2.1. 

Economics 
See Section 4.6.4.2.1. 

Driving force for implementation  
See Section 4.6.4.2.1. 

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Chapter 4 

4.6.3 

Techniques for housing of pullets 

According  to  Article  4(2)  of  the  'Recommendation  concerning  domestic  fowl  (gallus  gallus)' 
adopted  by  the  Council  of  Europe  in  1995,  young  should  be  given  appropriate  experience  of 
management  practices  and  environmental  conditions  to  enable  them  to  adapt  to  the  system 
which  they  will  encounter  later  as  laying  hens,  i.e.  enriched  cages  or  alternative  systems. 
Housing  systems  for  pullets  should  be  designed  to  give  them  appropriate  experience  of 
management  practices  (e.g.  particular  feeding  and  watering  systems)  and  environmental 
conditions (e.g. natural light, perches, litter) to enable them to adapt to the system which they 
will encounter later in life. 

The systems used to rear pullets of laying hens are practically the same as those used to house 
laying  hens.  The  differences  in  the  management  induce  different  environmental  impacts,  as  a 
consequence  of  the  different  heating  needs,  the  different  live  weight  and  the  different 
metabolism of the animals. 

In the following sections, for each technique only data related specifically to pullet rearing are 
given, since techniques have already been described in Section 4.6.1 and Section 4.6.2 for  the 
rearing of layers. The emission values that are associated with pullet rearing and that have been 
measured  are  reported  in  Table 4.62.  In  Germany,  the  dust  and  ammonia  emission  factors 
associated  with  the  rearing  of  pullets  (until  the  eighteenth  week)  are  typically  considered 
equivalent to 70 % of the values applied for the same technique in laying hen housing; the odour 
emission  factors  expressed  as  ouE/s/LU  are  considered  the  same  as  for  the  corresponding 
technique applied in laying hen housing [ 474, VDI 2011 ]. 

324 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Table 4.62:  Summary of reported achievable emissions in systems for rearing pullets 

Description 

NH3 
kg/ap/yr 

PM10 

Odour 

kg/ap/yr  ouE/s/bird 

Source 

Chapter 4 

[ 81, Germany 2010 ] 
[ 474, VDI 2011 ] 

[80, Netherlands 2010 ] 

[ 80, Netherlands 2010 ] 

[ 79, Netherlands 2010 ] 

[ 74, Netherlands 2010 ] 

NI 

NI 

0.045 

0.03 (4) 

0.04 (4) 

0.18 (1) 

0.18 (1) 

0.064 (2) 

0.016 (1) 

0.008 (1) 

0.050  (1) 

0.023  (1) 

0.078 (2)  0.042 (1) (3) 

0.078  (2)  0.042 (1) (3) 

0.029–0.030 
(5) 

Traditional cage system, 
without forced air drying 
Section 4.6.3.1.1 Small groups in enriched cages 
Small groups in enriched 
cages  
Section 4.6.3.1.2 Aviaries 
Aviaries on solid floor 
with litter. Non-ventilated 
manure belts, removal 
once per week 
Aviaries on solid floor 
with litter. Non-ventilated 
manure belts, removal 
twice per week 
Aviaries on solid floor 
with litter. Ventilated 
manure belts, removal 
once per week 
Aviaries on at least 55 % 
slatted floor. Non-
ventilated manure belts, 
removal once per week 
Aviaries on at least 65–
70 % slatted floor. 
Ventilated manure belts 
(0.2 m3/h/bird at 20 °C), 
removal once per week 
Aviaries on at least 35–
45 % slatted floor. 
Ventilated manure belts 
(0.1 m3/h/bird at 18°C), 
removal once per week 
Aviaries on at least 30–
35 % slatted floor. 
Ventilated manure belts 
(0.4 m3/h/bird at 17 °C), 
removal once per week 
Aviaries on at least 55–
60 % slatted floor. 
Ventilated manure belts 
(0.4 m3/h/bird at 17 °C), 
removal once per week 
Section 4.6.3.1.3 Deep litter with or without a manure pit 
Deep litter without a 
manure pit  
Deep litter with a manure 
pit 
(1) Values derived by expert judgement based on conclusions by analogy. 
(2) Modelled values (e.g. results based on N balance). 
(3) Figures derived from the associated emission value of 30 ouE/(LU s) for an average weight of 0.7 kg. 
(4) Derived from measurements.  
(5) Measured values.  
(6) Figures derived from the associated emission value of 42 ouE/(LU s) for an average weight of 0.7 kg. 
NB: NI = no information provided. 

0.181–0.227 
(5) 

0.059 (2)   0.056  (4) (6)  

0.023  (1) 

0.023  (1) 

0.030  (1) 

0.023  (1) 

0.030  (1) 

0.014  (1) 

0.170  (1) 

0.023 (1) 

0.020 (1) 

0.210 (4) 

0.18 (1) 

0.18 (1) 

0.18 (5) 

0.18 (1) 

[ 75, Netherlands 2010 ] 

[ 76, Netherlands 2010 ] 

[ 77, Netherlands 2010 ] 

[ 49, Germany 2010 ] 
[ 474, VDI 2011 ] 

[ 48, Netherlands 2010 ] 

Intensive Rearing of Poultry or Pigs 

325 

 
 
 
 
Chapter 4 

4.6.3.1 

Group cage with manure belts and forced manure drying 

Description 
The pullets' manure is collected on manure belts that are situated under each tier (or cage level) 
and  transported  to  a  closed  storage.  At  the  end  of  the  belt  a  cross  conveyor  transports  the 
manure  further  to  the  external  storage.  The  manure  belts  are  made  of  smooth,  easy-to-clean 
material (e.g. polypropylene) so that no residue sticks to them. Some drying takes place on the 
belts,  especially  in  summer  conditions.  The  higher  the  frequency  of  removal,  the  lower  the 
emission from the housing. 

In improved belt systems, air is blown over the manure to achieve faster drying of the manure. 
The  air  is  introduced  just  under  each  tier  of  cages,  usually  via  rigid  polypropylene  ducts. 
Another  benefit  is  the  introduction  of  fresh  cooling  air  immediately  adjacent  to  the  birds. 
Further improvements consist of the introduction of preheated house air and/or the use of heat 
exchangers to preheat incoming outside air. 

In  the  cages,  pullets  should  be  given  appropriate  experience  of  management  practices  (e.g. 
particular  feeding  and  watering  systems)  and  environmental  conditions  (e.g.  natural  light, 
perches, litter) to enable them to adapt to the husbandry systems which they will encounter later 
in life.  

Achieved environmental benefits 
The emission of ammonia is reduced through frequent removal and/or drying of the manure on 
the belt. Because the manure is transported out of the house and there is no manure residue on 
the manure belts, a lower odour level is obtained, which improves the climate in the house.  

Cross-media effects 
Application of this system needs additional energy to operate the belts and the fans used to blow 
the air over the manure. Additional energy input is also required if preheating is applied.  

Environmental performance and operational data 
No information provided.  

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
No information provided.  

Driving force for implementation 
No information provided.  

Example plants  
No information provided.  

Reference literature 
[ 43, COM 2003 ] 

4.6.3.2 

Small groups in enriched cages  

Description 
See Section 4.6.1.2. 

Achieved environmental benefits 
See Section 4.6.1.2. 

326 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
See Section 4.6.1.2. 

Environmental performance and operational data 
Under the vertical tiered cages, a manure belt is installed. Air is blown through the forced air 
drying system at 0.4 m3/h/bird, with a minimum temperature of 17 °C, and it should be fresh. 
Functional areas for feeding, drinking and resting are arranged above the dropping area. Manure 
is removed weekly, with a minimum dry matter content of 55 %. Birds are kept at a density of 
350–450 cm2 per head. In the Netherlands, the minimum available space per bird is reported to 
be 450 cm2 per head. 

In  the  Netherlands,  estimations  were  derived  from  data  of  laying  hens  housed  in  the  same 
system.  Associated  ammonia  emissions  are  0.016 kg/ap/yr  and PM10  emissions 0.008 kg/ap/yr 
when the manure is dried on belts, with an airflow of 0.4 m3 per animal per hour at 17 °C, and 
removed from the animal house daily. 

Technical considerations relevant to applicability  
See Section 4.6.1.2. 

Economics 
No information provided. 

Driving force for implementation 
It is expected that the use of small group enriched cages, as an alternative system, will increase 
in the future due to animal welfare legislation. See also Section 4.6.1.2. 

Example plants 
No enriched cage systems for rearing pullets are yet in use in the Netherlands. Also in Germany, 
the  system  is  not  yet  described  as  a  technique  for  rearing  young  hens  [  474,  VDI  2011  ]. 
Enriched cages are used for the rearing of pullets in some farms  in the UK [ 624, IRPP TWG 
2013 ]. See also Section 4.6.1.2. 

Reference literature  
[ 80, Netherlands 2010 ] [ 474, VDI 2011 ] [ 624, IRPP TWG 2013 ] 

4.6.3.3 

Aviaries  

Description 
See Section 4.6.2.2. 

Achieved environmental benefits 
See Section 4.6.2.2. 

Cross-media effects 
Aviaries  generate  higher  dust  emissions  compared  to  enriched  cage  systems,  due  to  litter 
material and increased animal activity; dust exposure could be a problem for the farmer and the 
birds. See also Section 4.6.2.2. 

Environmental performance and operational data 
The  emission  levels  that  are  achievable  depend  on  the  extension  of  the  slatted  floor,  on  the 
frequency of manure removal, and on the temperature and volume of the air that is blown over 
the droppings to dry them. The more the surface is slatted floor, the more manure is periodically 
removed by the belts that underlie the raised floors. The figures for different combinations of 
manure belts management are given in Table 4.63. 

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327 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.63:  Emissions  associated  with  combinations  of  slatted  floor  extension,  characteristics  of 
the drying air and frequency of manure removal, for the rearing of pullets 

Animal 
density 

Air 
volume  
m2/animal  m3/ap/h 

Air 
temp. 
°C 

Slatted 
floor 
 % 

Removals 
per week 

PM10

NH3 
emission 
kg/ap/yr  kg/ap/yr 

emission  Reference 

Combination 

Without 
forced air 
drying 

Fresh forced 
air drying 

Fresh forced 
air drying 

Low 
ventilation 

Warm forced 
air drying 

Forced air 
drying 

0.062 

NI 

NI 

55 

0.062 

0.4 

17 

35 

0.062 

0.4 

17 

60 

0.062 

0.1 

18 

50 

0.062 

0.2 

20 

70 

0.030 

NI 

NI 

Solid floor 

0.030 

NA 

NA 

Solid floor 

0.030 

NA 

NA 

0 

0 

0 

1 

1 

1 

1 

1 

1 

1 

2 

0.050 
(1) 

0.014 
(1) 

0.020 
(1) 

0.030 
(1) 

0.030 
(2) 

0.030 
(3) 

0.060 
(3) 

0.040 
(3) 

0.023 
(1) 

0.023 
(1) 

0.023 
(1) 

0.023 
(1) 

0.023 
(1) 

0.080 
(3) 

0.080 
(3) 

0.080 
(3) 

[ 79, 
Netherlands 
2010 ] 
[ 76, 
Netherlands 
2010 ] 
[ 77, 
Netherlands 
2010 ] 
[ 75, 
Netherlands 
2010 ] 
[ 74, 
Netherlands 
2010 ] 
[ 474, VDI 
2011 ] 
[ 81, 
Germany 
2010] 

[ 474, VDI 
2011 ] 

(1) Values derived by expert judgement based on conclusions by analogy. 
(2) Measured values. 
(3) Modelled values (e.g. results based on N balance). 
NB: NI = no information provided; NA = not applicable. 

Technical considerations relevant to applicability 
See Section 4.6.2.2. 

Economics  
In  the  Netherlands,  the  investment  required  is  estimated  to  be  EUR 7.35  per  animal  place  on 
average  (from  EUR 6.25/ap  to  EUR 7.8/ap),  corresponding  to  annualised  investment  costs  of 
EUR 0.92/ap/yr  (from  EUR 0.78/ap/yr  to  EUR 0.98/ap/yr).  In  Germany,  investment  costs  are 
reported  as  EUR 11.20  per  animal  place,  on  average,  corresponding  to  annualised  costs  of 
EUR 1.25/ap/yr. 

Driving force for implementation 
See Section 4.6.2.2. 

Example plants 
In  the  Netherlands,  in  2008  about  33 %  of  pullets  were  housed  in  aviary  systems.  At  least 
15 farms in Belgium (Flanders) are equipped with this system [ 467, BE Flanders 2010 ]. 

Reference literature 
[74, Netherlands 2010] [75, Netherlands 2010] [76, Netherlands 2010] [77, Netherlands 2010] 
[ 78, Netherlands 2010 ] [79, Netherlands 2010] [81, Germany 2010] [ 467, BE Flanders 2010 ] 
[ 474, VDI 2011 ] 

328 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.6.3.4 

Deep litter with or without a manure pit 

Description  
See  also  Section 4.6.2.1.1.  Pullets  are  raised  in  a  house  with  a  concrete  floor  covered  with 
bedding material (wood shavings or chopped straw). In the middle of the house there may be a 
manure pit with a slatted floor above it. The slatted surface is reported not to exceed two thirds 
of the total area. The manure is stored beneath the slatted floor and is removed after delivery of 
the flock. For configurations without a manure pit, manure is removed by mobile means.  

A cross section of a housing system with deep litter and a manure pit, for the rearing of pullets, 
is shown in Figure 4.17. 

NB: 1 = slatted floors; 2 = littered area; 3 = manure pit. 
Source: [ 48, Netherlands 2010 ] 

Figure 4.17:  Cross section of the housing system with deep litter and a manure pit  

Achieved environmental benefits 
See Section 4.6.2.1.1. 

Cross-media effects 
Cross media-effects include higher ammonia and odour emissions, due to manure storage in the 
housing  system  and  removal  only  at  the  end  of  the  rearing  period.  Dust  emissions  are  higher 
compared to cage systems, due to the litter material and increased animal activity; dust exposure 
could be a problem for the farmer and the birds. 

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329 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
Functional  areas  for  feeding,  drinking  and  resting  are  arranged  above  the  dropping  area.  The 
system  has  more  management requirements,  in particular  for  the  rearing  in  confinement  rings 
during the first days after birth (up to seven days), when several checks are necessary on a daily 
basis (e.g. control of chicks and temperature). Later, at least a daily control of the birds and the 
bedding is sufficient.  

The available space provided per bird is reported to be between 0.0625 m2 and 0.07 m2, and the 
duration of the growing period is reported to be between 16 and 18 weeks; the animal weight at 
the end of the rearing period is around 1.3 kg. 

Technical considerations relevant to applicability 
See Section 4.6.2.1.1. 

Driving force for implementation 
Pullets  should  be  raised  in  the  same  system  they  are  placed  in  during  the  laying  period.  The 
system is more animal-friendly due to the increased space availability (compared with cages). 

Economics  
In  Germany,  for  the  configuration  without  a  manure  pit,  the  demand  for  bedding  material  is 
reported  to  be  equivalent  to  2.3 kg/ap/yr,  the  labour  demand  0.03  h/ap/yr,  and  the  energy 
consumption is reported as 0.52 kWh/ap/yr for lighting and 2.2 kWh/ap/yr for ventilation.  

In the Netherlands, for the configuration with a manure pit, investment costs are reported to be 
from  EUR 2.65  to  EUR 4 per  animal  place,  with  an  average  value  of  EUR 3.35 per  animal 
place, and the annualised investment costs vary from EUR 0.33/ap/yr to EUR 0.5/ap/yr, with an 
average value of EUR 0.42/ap/yr. 

Example plants 
In the Netherlands, the deep litter system with a manure pit is the reference housing system for 
raising pullets. The deep litter technique without a manure pit is also widespread in Germany. 

Reference literature 
[48, Netherlands 2010] [49, Germany 2010] 

4.6.4 

Techniques for housing of broilers 

Traditionally, broilers are kept in houses with a fully littered floor (see Section 2.2.2). Both for 
animal welfare reasons and to minimise ammonia emissions, wet litter has to be avoided.  
The dry matter content of the litter and emissions depend on: 

the drinking system design and operation; 

the duration of the growing period; 

the stocking density; 

the use of floor insulation; 

the ventilation rate and airflow direction; 

the climatic conditions; 

the management of rainwater; 

bird health (e.g. diarrhoea); 

the type and amount of bedding material. 

 

 

 

 

 

 

 

 

 

330 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Ammonia  emissions  decrease  with  the  increase  of  the  manure  dry  matter  content;  for  a  dry 
matter  content  higher  than  65 %  approximately,  the  emission  reduction  is  more  than 
proportional [ 90, Italy 2010 ]. 

The stocking  density  and  the  duration  of  the  growing  period  also  have  an  effect  on  ammonia 
emissions, in the sense that the increasing bird body weight during rearing implies that  higher 
manure  volumes  are  produced,  as  well  as  increased  bedding  compaction.  The  latter  effect 
depends  on  the  type  of  litter  material,  the  season  and  the  humidity  of  the  litter,  because  the 
compacted crust that can develop on the surface of a high-density house does not permit air to 
penetrate  and  reach  the  inner  layers  [  90,  Italy  2010  ].  Reported  typical  bedding  material 
consumption is presented in Table 3.31 for chopped straw, wood shavings and peat. A summary 
of the emissions associated with techniques that have been reported is presented in Table 4.64. 

Table 4.64:  Summary  of  reported  emissions  from  broiler  housing  with  different  system 

configurations 

Description 

Slaughter 
weight (rearing 
period) 
kg 

NH3 

PM10 

Odour 

Source 

kg/ap/year 

ouE/s/bird   

4.6.4.1 Forced ventilation and a non-leaking drinking system (in case of solid floor with deep 
litter) 
Ridge ventilation, wood 
shavings bedding, animal 
density 17.5–20.8 kg/m2 
Cross ventilation 

2.1 (females, 39 
days) 

[ 96, UK 2010 ] 
[ 97, UK 2010 ] 

[ 98, UK 2010 ] 

0.034 (1) 

0.025 
(2) 

0.032  
(2) 

Tunnel ventilation  

Side ventilation  

Ridge ventilation  

Tunnel ventilation, animal 
density of 37 kg/m2 

2.1 (females, 6 
weeks)  
3 (males, 7.5 
weeks) 

1.5 
(34 days) 

2 
(42 days) 

Wood shavings bedding, 
animal density of 35 kg/m2 

2.5–3.3 

Straw bedding, animal 
density of 35 kg/m2 

2.5–3.3 

Wood shavings bedding, 
animal density of 30 kg/m2 

2.5–3.3 

Straw bedding, animal 
density of 30 kg/m2 

2.5–3.3 

Straw or rice husk bedding, 
summer/winter 
observations, animal 
density of 24–30 kg/m2 
Non-leaking drinking and 
tunnel ventilation (DM 
78 %), animal density of 
27 kg/m2 (4) 

1.45–1.74 

1.6 (females, 39 
days) 
3.3 (males,57 
days) 

0.035 
(1)–
0.039 (2) 
0.049 
(1)–
0.054 (2) 
0.112 
(0.096–
0.127) 
(3) 
0.12 
(0.114–
0.126) 
(3) 
0.096 
(0.064–
0.142) 
(3) 
0.101 
(0.086–
0.116) 
(3) 
0.079 
(0.055–
0.102) 
(3) 

0.069–
0.073 
(3) 

[ 99, UK 2010 ] 

[ 100, UK 2010 ] 

[ 101, UK 2010 ] 

[87, Germany 2010] 
[ 500, IRPP TWG 
2011 ] 

[ 92, Italy 2010 ] 
[ 90, Italy 2010 ] 

0.015–
0.025 (1) 

0.015–
0.025 (1) 

0.09 (3) 

0.12 (3) 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 91, Italy 2010 ] 

NI 

NI 

[ 89, Italy 2010 ] 

Intensive Rearing of Poultry or Pigs 

331 

 
 
 
 
Chapter 4 

Description 

Non-leaking drinking and 
cross ventilation, animal 
density of 30 kg/m2 (DM 
61 %) (4) 

Slaughter 
weight (rearing 
period) 
kg 
2 (females, 41 
days) 
3.3 (males, 62 
days) 

NH3 

PM10 

Odour 

Source 

kg/ap/year 

ouE/s/bird   

0.082–
0.090 
(3) 

NI 

NI 

[ 88, Italy 2010 ] 

Deep litter 

NI 

0.06–0.1 
(2) 

NI 

NI 

[ 624, IRPP TWG 
2013 ] [ 624, IRPP 
TWG 2013 ][ 656, 
Ponchant et al. 2012 ] 

Deep litter (0.05 m2/bird) 
4.6.4.3–4.6.4.4 Forced air drying of litter using indoor air (in case of solid floor with deep litter) 
Perforated floor with 
forced air drying system 

[ 43, COM 2003 ] 

[ 50, Austria 2010 ] 

(40–54 days) 

0.180 (5) 

0.014 

NI 

NI 

NI 

NI 

NI 

Tiered floor system with 
forced air drying 

2.25 
(49 days) 

0.0203 
(3) 

0.022  
(5) 

0.24 (1) 
(0.19–0.7) 
(3) 

[585, Netherlands 
2010] 

[ 94, Netherlands 
2010 ] [ 640, 
Netherlands 2013 ] 

NI 

0.22 (2) 

0.020 
(2) 

0.018–
0.040 (6) 

4.6.4.5 Separation of hatching and growing broiler chicks for a limited time (in case of tiered 
floor systems) 
Separate hatching and 
rearing up to 13 days, 
finishing in low emission 
houses 
Separate hatching and 
rearing up to 13 days, 
finishing in standard 
emission houses 
Separate hatching and 
rearing up to 19 days, 
finishing in low emission 
houses 
Separate hatching and 
rearing up to 19 days, 
finishing in standard 
emission houses 
4.6.4.2 Forced drying system of litter using indoor air (in case of solid floor with deep litter) 

0.015–
0.038 (6) 

0.020 
(2) 

0.070 

0.017 

0.060 

0.017 

0.22 

0.19 

0.19 

NI 

NI 

NI 

[ 93, Netherlands 
2010 ] [ 640, 
Netherlands 2013 ] 

[473, Infomil 2011] 

[473, Infomil 2011] 

Litter-based systems with 
circulating fans  

2.1–2.34 
(37–42 days) 

Litter-based systems with 
circulating fans and a heat 
exchanger 

2.5  
(38–47 days) 

0.24 (1) 
(0.11–
0.41) (3) 

[ 586, Netherlands 
2010 ] 

0.24 (5) 

[ 464, Netherlands 
2010 ] 

0.022 
(5) 

0.019 
(0.0176–
0.02) (1) 

0.037 (1) 
(0.0102–
0.0418) 
(3) 
0.021 
(0.004–
0.061) 
(3) 
0.035 (1) 
(0.005–
0.128) 
(3) 

2.26–2.37 
(41–49 days) 

Litter-based systems with 
(equally spread) 
recirculated air by indoor 
fans and heaters  
(1) Derived from measurements. 
(2) Modelled values (e.g. results based on N balance). 
(3) Measured values. 
(4) Before sex separation. 
(5) Values derived by expert judgement based on conclusions by analogy. 
(6) The upper end of the range corresponds to a combination with the combideck system and the lower end to a 
combination with the tiered floor system with forced air drying.  

[ 470, Netherlands 
2011 ] 

0.022 (5) 

0.24 (5) 

NB: NI = no information provided. 

332 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Chapter 4 

4.6.4.1 

Natural or forced ventilation with a non-leaking drinking system (in 
case of solid floor with deep litter) 

Description 
A  layer  of bedding material is spread uniformly over the  entire floor  area at the beginning of 
each  growing  period  and  is  removed  at  the  end  of  the  cycle  as  broiler  litter  (solid  manure). 
Bedding is mainly made up of chopped straw, wood shavings, rice husks, peat or other material. 
The absorbent bedding material when mixed with droppings binds urine and faeces in the litter 
and provides a dry area. Drinking water system design and operation are such that leakage and 
spills  on  litter  are  prevented  (e.g.  use  of  nipples  instead  of  bell  drinkers).  The  use  of  floor 
insulation is intended to reduce litter moisture by preventing  air moisture condensation. Floor 
insulation can be achieved by using different materials, such as concrete or clay. The ventilation 
rate  in  forced  ventilated  buildings  is  automatically  controlled  to  remove  moisture  under  all 
weather and seasonal conditions while meeting the physiological needs of the birds. 

Reported variations of the basic litter-based system are:  

 

 

combination with free range and/or a veranda; 

open climate house (natural ventilation); 

Achieved environmental benefits 
Ammonia emissions are reduced by keeping the litter dry.  

Cross-media effects 
Higher dust emissions due to the presence of litter and increased bird movement. 

Environmental performance and operational data 
Ammonia is emitted through an enzymatic decomposition (hydrolysis) reaction of urea: 

(NH2)2CO + H2O (urease)  → NH3 + H2NCOOH → 2NH3(gas) + CO2(gas) 

Drying will inhibit the hydrolysis of  nitrogen in the manure, thereby reducing NH3 emissions. 
At  moisture  levels  in  litter  below  30–35 %,  the  rate  of  reactions  responsible  for  ammonia 
volatilisation are greatly reduced [ 91, Italy 2010]. 

Drinking water spillages increase the litter moisture content. In particular, ammonia losses from 
broiler  houses  using  traditional  bell  drinkers  have  been  found  to  be  three  times  greater 
(3.3 g NH3-N/h  on  average  per  LU)  than  those  using  nipple  drinkers,  although  differences  do 
not seem to be statistically confirmed [ 146, DEFRA 2002 ]. 

A typical emission level associated with this technique, regardless of the effect of the nutritional 
management  on  the  manure  composition,  is  0.08 kg  NH3  per  broiler  place  per  year.  In  fact, 
ammonia emissions depend on the specific housing system; proper ventilation management and 
non-leaking drinking systems are among the important parameters for keeping the litter dry and, 
therefore, reducing  ammonia  emissions. The  NH3  emission  reduction  efficiency  is  reported to 
range from 20 % to 30 % for naturally or insulated, forced ventilated houses, equipped with a 
non-leaking drinking system [ 508, TFRN 2014 ].  

Reported  ranges  of  emissions  to  air  are  presented  in  Table 4.64.  N2O  emissions  of  between 
0.025 kg  and  0.032 kg  N2O/ap/yr  have  been  reported.  The  effects  of  ventilation  on  ammonia 
emissions have been studied in Italy for two different mechanical ventilation settings. Reported 
results  and  operating  conditions  applied  in  two  fully  littered  housing  systems  for  broilers  are 
given in Table 4.65. 

A  good  regulation  of  the  ventilation  system,  avoiding  cold  air  drafts  and  water  vapour 
condensation on the litter, a good control of the water leakage from the drinking line, and use of 

Intensive Rearing of Poultry or Pigs 

333 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

a computerised control system contribute to a higher ammonia reduction. Based on the results 
reported  from  Italy,  an  ammonia  emission  reduction  of  20–30 %  can  be  achieved  with  an 
appropriate  management  system  which  can  be  applied  in  new  and  existing  buildings  
[ 88, Italy 2010 ] [ 89, Italy 2010 ].  

Table 4.65:  Effects  on  emissions  of  controlling  mechanical  ventilation  in  deep  litter  broiler 

housing systems  

Parameters 

Final weight 
Rearing time 

Bird places 

Units 

kg 
days 

places 

Housing system 

Cross ventilation 
2.1 (standard) – 3.3 (heavy) 
39 (standard) – 57 (heavy) 
19 300  
(9 000 female + 10 300 male) 

Tunnel ventilation 
1.6 (standard) – 3.3 (heavy) 
41 (standard) – 62 (heavy) 
12 100  
(6 000 female + 6 100 male) 

% 

m3/ap/h 

N content of three-phase 
feed 
Cold season, ventilation 
rate  
Warm season, 
ventilation rate 
Manure DM content 
NH3 emissions 
Reduction of NH3 
emission  
Source: [ 88, Italy 2010 ] [ 89, Italy 2010 ] 

% 
kg/ap/yr 

m3/ap/h 

% 

3.9–3.5 

1.1  
(0.4–2) 
9.7  
(1.2–28.8) 
61 
0.082–0.09 

20 

4.4–3.3 

1.4  
(0.5–3.6) 
10  
(1.6–23.7) 
78 
0.069–0.073 

30 

Other trials carried out in Italy  also investigated the effect on ammonia emissions of different 
ventilation  conditions  (tunnel  or  cross  ventilation),  animal  densities  (from  24.1 kg/m2  to 
30 kg/m2), bedding materials (straw or rice husks) and weather conditions (summer and winter). 
Tunnel ventilation achieved a more even drying of the manure at the end of the cycle, as well as 
a  higher  average  dry  matter  content  (69 %  in  comparison  to  63 %  for  cross  ventilation).  The 
average  ammonia  emission  factor  was  found  to  be  0.079 kg/bird/year  (average  equal  to 
0.102 kg/bird/year for winter and 0.057 kg/bird/year for summer). During the summer months, 
when  high  ventilation  rates  allow  the  achievement  of  higher  levels  of  dry  matter  in  the  litter, 
regardless of the type of ventilation, ammonia emissions are expected to be lower. As regards 
stocking  density,  in  some  cases  emissions  from  compacted  litter  were  higher  than  from  areas 
with loose litter because in this case air cannot reach the deeper layers in order to dry litter. In 
situations  with  high  densities,  the  formation  of  a  compact  surface  layer  may  slow  down 
emissions  even  though  moisture  is  higher  because  air  exchange  with  the  interior  layers  is 
prevented [ 90, Italy 2010 ] [ 91, Italy 2010 ].  

It  is  also  reported  from  Italy  that  forced  ventilation  systems  with  longitudinal  spread  can  be 
designed so that inlet tubes convey cold air to the ceiling (in winter), forcing hot air to reflux 
down.  In  this  way,  good  air  circulation  is  achieved  and  water  condensation  on  the  litter  is 
avoided, maintaining it sufficiently dry [ 624, IRPP TWG 2013 ].  

Data  reported  by  Finland,  concerning  deep  litter  broiler  houses  equipped  with  energy-saving 
fans,  show  a  reduction  of  ammonia  emissions  by  20–30 %,  as  well  as  a  reduction  in  odour 
emissions (see Section 4.5.4.2.1.4)  [ 144, Finland 2010 ]. In the UK, for all forced ventilation 
designs  in  broiler  housing,  the  same  ammonia  emission  factor  is  used  (see  Table 4.64)  [  148, 
BPC 2009 ]. 

Italy and the UK reported similar ventilation rates in the warm season, which are on average in 
the range of about 10–15 m3 per bird place per hour. Averages recorded in the colder seasons 
differ between the countries, being around 1.1 m3 to 1.4 m3 per bird place per hour in Italy and 
7.5 m3 to 11 m3 per bird place per hour in the UK. Peaks of maximum airflows in the summer 

334 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
have been reported as 23–28 m3 per bird place per hour in Italy. The German welfare standards 
require minimum airflows of 4.5 m3/kg live weight per hour on hot days; hence peaks of up to 8 
m3 per bird place per hour were recorded. Energy requirements have been reported by Germany 
and are displayed in Table 4.66. 

Chapter 4 

Table 4.66:  Breakdown  of  resource  demand  in  kWh  per  bird  place/year  in  deep  litter  broiler 

houses (cycles of 38–42 days)  

Operation 

Open climate 
housing 

Lighting 
Ventilation 
Heating 
Feeding 
Removal/cleaning 
Total 
NB: NI = no information provided; NA = not applicable. 

0.200 
0.100 
NI 
0.140 
0.140 
NA 

Basic 
housing 
system 
0.330 
0.730 
4.500 
0.140 
0.140 
5.84 

Basic housing 
system with free 
range  
0.330 
0.730 
5.500 
0.140 
0.140 
6.84 

Basic housing system 
with a veranda and 
free range  
NI 
NI 
NI 
0.140 
0.140 
NA 

Source: [ 87, Germany 2010 ] 

In  Finland,  data  for  the  consumption  of  resources  have  been  reported  for  electricity,  from 
0.29 kWh/ap/yr to 1.26 kWh/ap/yr, water from 4 litres/ap/yr to 34 litres/ap/yr and labour from 
0.016 hours/ap/yr  to  0.040  hours/ap/yr.  Around  1.42 kWh/ap/yr  are  needed  from  fuels;  in  the 
reported case, straw is used as fuel. 

Naturally  ventilated/open  climate  houses  are  also  in  use.  As  relatively  lower  average 
temperatures are achieved compared to houses with mechanically controlled ventilation, lower 
ammonia emissions are also expected, as well as a better indoor climate, lower energy demands 
and  lower  investment  and  operating  costs.  In  houses  with  natural  ventilation,  floor  insulation 
(e.g.  concrete,  clay,  membrane)  prevents  further  water  condensation  in  the  litter.  Non-leaking 
drinking systems are necessary. Cooling of the incoming air is possible. 

The variant of the litter-based system with free range is applicable from day 20 onwards. Free-
range  areas  include  natural  ground  and  structured  outdoor  areas  with  trees  and  installations 
providing shade and protection from rain as well as from diurnal birds. When a veranda is also 
combined with the free range, it has a solid floor with bedding.  In housing with free range, a 
10 %  higher  ammonia  emission  is  estimated;  odour  emissions  are  expected  to  be  the  same  
[  87,  Germany  2010  ]  [  500,  IRPP  TWG  2011  ].  Veranda  and  free-range  variations  are  not 
intended to reduce NH3 emissions. 
Rice husks can also be used as a bedding material (e.g. in the region of Andalusia in Spain) and 
provide good hygroscopic properties and fire safety when using biomass burners inside farms. 

Technical considerations relevant to applicability 
No  technical  restrictions  are  reported  for  the  implementation  of  the  technique.  For  natural 
ventilation see Section 4.5.6. 

Economics 
Investment  costs  have  been  calculated in  Germany  for  sheds  of  different  sizes,  as  reported  in 
Table 4.67. 

Intensive Rearing of Poultry or Pigs 

335 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.67:  Investment costs for deep litter houses for broilers  

Housing for 35 000–37 000 
bird places 

Housing for 26 500 
bird places 

Type of housing 

Investment cost 
(EUR/ap) 

Basic housing  
Open climate 
housing  
Basic housing with 
free range  
NB: NI = no information provided. 

12.00 

12.00 

NI 

Annualised 
investment cost 
(EUR/ap) 
1.04 

0.99 

1.74 

Investment cost 
(EUR/ap) 

17.00 

16.00 

NI 

Annualised 
investment cost 
(EUR/ap) 
1.45 

1.38 

NI 

Source: [ 87, Germany 2010 ] 

The  annual  operating  cost  is  reported  to  be  equivalent  to  EUR 3.5/bird  place  for  the  standard 
system and the same for the alternative with an open climate house [ 87, Germany 2010 ]. 

Investment data reported from Finland for a farm of 30 000 birds are comparable with the data 
presented  above,  with  a  cost  of  EUR 11.67  per  bird  place  for  the  initial  investment  and 
EUR 0.93  as  the  annualised  cost  (20  years  amortisation,  5 %  interest  rate).  In  the  UK, 
investment costs have been reported to be in the range of EUR 14 and EUR 16 per bird place.  

The cost per bird, for abating ammonia emissions through a reduction in temperature of 1 °C, 
has  been  calculated  in  the  UK  to  be  in  the  range  of  EUR 0.27–0.28  per  bird,  leading  to  a 
reduction of NH3 emissions of 0.04 g per kg of bird per day. However, there are concerns that 
productivity may be reduced and that there may be a related increase in energy consumption due 
to higher ventilation rates [ 151, Link CR 2005 ]. 

Driving force for implementation 
Animal welfare can be improved by the possible combination with verandas and/or free ranges, 
offering  valued  non-environmental  benefits, such  as external  climate/stimuli,  functional  areas, 
more  space  and  more  bird  locomotion.  The  alternative  design  with  a  veranda  and/or  outdoor 
free  range  offers  a  space  per  bird  of  0.085  m2/bird,  in  comparison  with  0.043m2/bird  in  the 
standard housing system.  

Example plants 
This type of housing is the most widespread housing system for broiler production.  

Reference literature 
[ 87, Germany 2010 ] [ 88, Italy 2010 ] [ 89, Italy 2010 ] [ 90, Italy 2010 ] [ 91, Italy 2010 ]  
[ 92, Italy 2010 ] [ 95, UK 2010 ] [ 96, UK 2010 ] [ 97, UK 010 ] [ 98, UK 2010 ] [ 99, UK 2010 ] 
[ 100, UK 2010 ] [ 144, Finland 2010 ] [ 145, Finland 2010 ] [ 146, DEFRA 2002 ] [ 148, BPC 
2009 ] [ 151, Link CR 2005 ] [ 500, IRPP TWG 2011 ] [ 508, TFRN 2014 ] [ 624, IRPP TWG 
2013 ] 

4.6.4.2 

Forced drying system of litter using indoor air (in case of solid 
floor with deep litter) 

4.6.4.2.1 

Litter-based systems with circulating fans 

Description 
The deep litter system is equipped with vertical shafts and a ventilator hanging from the ceiling. 
At the bottom of the shaft, at a maximum height of 1.20 m above the litter, a special element is 
placed to direct the warm air from the roof of the house horizontally over the litter. In addition, 
circulating fans homogenise the airflows at the bird level, without increasing the volume of air 

336 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

supplied  by  the  central  ventilation.  This  system  is  used  in  the  Netherlands  to  reduce  the 
ammonia emissions. 

Achieved environmental benefits 
Drying of the surface litter is achieved and, consequently, ammonia emissions are reduced. The 
positive  effect, in terms  of  ammonia  emission, is  calculated as  a 54 %  reduction  in  emissions 
compared to the reference system used in the Netherlands [ 586, Netherlands 2010 ]. 

Because of mixing the warm ceiling air with the colder air just above the floor, a slight benefit 
(10 %) is calculated for heating costs, i.e. from reduced energy consumption [ 586, Netherlands 
2010 ]. 

Cross-media effects 
Due to the ventilators in the shafts, an extra demand for electricity is expected. However, these 
costs can be partly compensated by the improved heat distribution. 

Environmental performance and operational data 
Vertical shafts should be placed every 150 m2, in two rows along the length of the house, and 
should  not  be  placed  right  opposite  each  other,  in  order  to  ensure  homogenous  spreading  of 
warm  air. The  fans  work  continuously,  with  a reported  minimum  capacity  of  1.8  m3/hour  per 
bird place. At the beginning of the cycle (one-day-old chicks), the ventilators start at a capacity 
of 10 % and progressively reach 100 % capacity by day 40.  

Surface drying of the litter in broiler houses reduces NH3 emissions. Emission factors achieved 
in  the  Netherlands  for  an  installed  ventilation  capacity  of  1.8  m3/hour  per  bird  place  are 
0.037 kg NH3/ap/yr in broiler houses and 0.183 kg NH3/ap/yr in parent houses (broiler breeders) 
[ 469, Netherlands 2011 ]. These ammonia emission levels can only be achieved if the system 
fully complies with the operational requirements. 

Data  concerning  the  emission  values  associated  with  the  application  of  deep  litter  housing 
systems  equipped  with  circulating  fans  in  the  Netherlands  are  reported  in  Table 4.68.  For  the 
same systems, typical ventilation rates are reported to be in the range between 1.1 m3/ap/h and 
1.3 m3/ap/h during the cold season and between 1.9 m3/ap/h and 2.8 m3/ap/h  during the warm 
season, combined with an inlet air cooling system using water fogging.  

Table 4.68:  Reported  emissions  from  broiler  production  in  deep  litter  housing  systems  with 

circulating fans  

Parameter 

Unit 

Ammonia  

kg NH3/ap/yr 

PM10 

Odour 

kg PM10/ap/yr 

ouE/s/ap 

Source: [ 585, Netherlands 2010 ] 

Emission levels 
0.037 
(0.0102–0.0418) 
0.022 
0.24 
(0.11–0.41) 

Technical considerations relevant to applicability  
The technique  is  applicable  to  new  housing  systems  for  broilers  and  in  most  existing  houses; 
however,  for  existing  houses,  the  applicability  may  be  limited  if  the  building  has  a  very  low 
ceiling [ 586, Netherlands 2010 ]. 

The technique may not be applicable in hot climates in summer when there is a need for cooling 
[ 624, IRPP TWG 2013 ]. 

Intensive Rearing of Poultry or Pigs 

337 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
Mixing the air inside the house allows a better indoor climate with positive effects on animal 
health and welfare and labour conditions.  

Economics 
The  extra  investment  costs  associated  with  the  technique  compared  to  the  traditional  housing 
costs are reported to be EUR 1/animal or EUR 0.14/bird place/year [ 586, Netherlands 2010 ]. 

Example plants 
In 2008, in the Netherlands, the housing system with deep litter and circulating fans was applied 
for about 10 % of the total bird places [ 586, Netherlands 2010 ]. 

Reference literature 
[  339,  ITAVI  1997  ]  [  349,  ITAVI  1998  ]  [  350,  France  2010  ]  [  354,  ITAVI  2004  ]  
[  469,  Netherlands  2011  ]  [  585,  Netherlands  2010  ]  [  586,  Netherlands  2010  ]  [  624,  IRPP 
TWG 2013 ] 

4.6.4.2.2 

Litter-based systems with circulating fans and a heat exchanger 

Description 
This technique is intended for ammonia and dust reduction and is based on heating and drying 
the  litter  by  the  combined  use  of  heat  exchangers  and  ventilators  (see  Section  4.5.4.2.1.2  for 
information on circulating fans in combination with heat exchangers). Incoming air is warmed 
up in a heat exchanger using the heat recovered from the indoor air. The ventilators spread the 
warm  air  homogenously  over  the  litter.  An  improved  version,  with  a  higher  capacity  heat 
exchanger,  is  intended  for  extra  dust  abatement.  A  description  of  heat  exchangers  is  given  in 
Section 4.5.5.1.  

Achieved environmental benefits  
In  addition  to  a  reduced  energy  requirement,  achievable  by  using  a  heat  exchanger  (see  also 
Section  4.5.4.2.1.2),  ammonia  reductions  are  achieved  and  dust  is  removed  with  improved 
exchangers. The generic NH3 emission reduction efficiency for techniques using internal air for 
litter drying is reported to range from 40 % to 60 % at a cost of EUR 2 to EUR 4 per kg of NH3 
abated per year [ 508, TFRN 2014 ]. The resulting manure is drier and lighter, which implies a 
lower transport weight and consequently lower associated costs. 

Cross-media effects 
No direct cross-media effects have been reported. 

Environmental performance and operational data  
The capacity of the heat exchanger is at least 0.35 m3/bird place per hour, whereas the capacity 
of the improved heat exchanger for extra dust removal is 1.0 m3/bird place per hour. A removal 
of fine dust equivalent to 13 % is reported for the normal type of heat exchanger, and 31 % for 
the improved type. 

The  placement  of  the  outlet  of  the  heat  exchanger  depends  on  the  type  of  ventilation  (see 
Figure 4.18).  The  ventilators  must  be  placed  no  more  than  20  m  from  each  other  and  at  a 
maximum distance from the ceiling of 1.5 m. A capacity of 6 000 m3/h per ventilator is reported, 
with at least 23 m3 per square metre of litter. 

338 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 465, Netherlands 2011 ] 

Figure 4.18:  Examples of layouts for systems of circulating fans and a heat exchanger 

Measurements were carried out at four farms, with capacities from 21 000 to 39 000 birds, fed 
with  three  or  four  feeding  phases  to  a  final  weight  of  2.5 kg  (one  farm's  final  weight  was 
1.9 kg), with ventilation rates in the range of 0.3–0.9 m3/bird place per hour in the cold season, 
and 2.1–4.8 m3/bird place per hour in the warm season. Recorded ammonia emissions showed a 
maximum  of  0.061 kg NH3/ap/yr and  an  average  value  of  0.021 kg NH3/ap/yr, which is  74 % 
lower than the reference level in the Netherlands. 

Measurements  of  dust  emissions  ranged  from  to  0.02 kg/ap/yr  with  normal  equipment  to 
0.017 6 kg/ap/yr  with  improved  equipment  (10 %  and  20 %  less  respectively  compared  to  the 
Dutch reference). 

Technical considerations relevant to applicability 
The system can be implemented in any new broiler house and in most existing ones depending 
on the ventilation system already in place. 

Intensive Rearing of Poultry or Pigs 

339 

 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
This solution allows for better climate control which is especially beneficial during the first days 
of rearing since it leads to stronger and healthier animals. 

Economics 
In a house with a capacity of around 40 000 birds, the investment requirements are in the range 
of  EUR 0.7–1.0  per  bird  place  and  the  annual  operating  costs  are  around  EUR 0.005  per  bird 
place. Cleaning and checking of the heat exchangers will take 1.5 to 2 hours work per round per 
exchanger. Under Dutch climatic conditions, the savings in heating costs that heat exchangers 
allow can be up to 50 %, corresponding to about EUR 0.38/ap/yr (2011 prices). 

Example plants 
Heat exchangers are well known and becoming widespread in the Netherlands.  

Reference literature 
[ 464, Netherlands 2010 ] [ 465, Netherlands 2011 ] [ 508, TFRN 2014 ] 

4.6.4.2.3 

Litter-based systems with air recirculated (equally spread) by 
indoor fans and heaters 

Description 
A  combination  of  heaters  with  indoor  ventilators  is  used  to  heat  the  house  (see  also 
Section 4.5.4.2.1.3). Ventilators drive warm air from the ceiling down to the floor level. The air 
is warmed up by thermal exchange with hot water produced by an indirectly fired thermal heater 
using propane or natural gas or by central heating. The heaters are provided with equipment to 
let the air come out horizontally, spreading it all over the litter. A schematic representation of 
the  housing  system  with  recirculating  indoor  fans,  combined  with  indirectly  fired  heaters,  is 
given in Figure 4.19. 

View from above 

Source: [ 471, Netherlands 2011 ] 

Section for the configuration with individual heaters 

Figure 4.19:  Plan and cross section of horizontal ventilation with air recirculated by indoor fans 

340 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits  
Ammonia  reduction  is  achieved  by  drying  the  litter  through  warm  air  blowing.  Ammonia 
emissions are reported to be 56 % lower than those corresponding to the reference system used 
in the Netherlands. An optimal indoor air climate is achieved at low heating costs. A reduction 
of energy consumption for heating of around 20 % is achievable, with the related cost reduction, 
as  a  result  of  the  good  mixing  of  warm  air  from  the  ceiling  with  colder  air  just  above  the 
housing floor.  

Cross-media effects 
Around 20 % additional electricity is used by the ventilators compared to the basic litter-based 
housing  systems.  However,  because  of  the  reduced  CO2  and  moisture  levels  inside  the  house 
produced  by  heaters,  the  minimum  ventilation  rate  at  the  start  of  the  rearing  period  can  be 
reduced. This saving can compensate for the extra electric energy used by the ventilators.  

Environmental performance and operational data  
The  number  of  heaters  installed  depends  on  their  heating  capacity.  In  general,  each  heater 
should  cover  a  maximum  area  of  450 m2  and  the  distance  between  two  heaters  should  not 
exceed  25 m.  The  maximum  distance  from  the  rooftop,  where  the  suction  of  warm  air  is 
installed in order to convey it to the heater, is 2 m, whereas the heated air entering the housing 
system is released at 1.5 m, at the most, from the floor.  

Normally,  the  ventilators  are  running  at  least  20 %  of  their  maximum  capacity.  When  the 
temperature  is  low  and  air  needs  to  be  warmed  up,  the  heating  is  turned  on  and  then  the 
ventilators run at full capacity. 

In  the  Netherlands,  the  following  measured  ammonia  emissions  are  associated  with  the 
application of this housing system [ 471, Netherlands 2011 ]: 

 

 

 

 

broilers: 0.005–0.128 kg NH3/ap/yr, with an average value of 0.035 kg/ap/yr; 

broiler breeders: 0.180 NH3/ap/yr; 

turkeys: 0.489 NH3/ap/yr; 

guinea fowl: 0.058 NH3/ap/yr. 

Dust and odour emissions associated with broiler rearing are equivalent to 0.022 kg PM10/ap/yr 
and 0.24 ouE/s per bird. 

Technical considerations relevant to applicability 
This system can be installed in new houses for broilers. When retrofitting existing houses, the 
applicability might depend on the height of the ceiling. 

Driving force for implementation 
The continuous mixing of warm air from the ceiling with the colder air at lower heights allows 
energy savings corresponding to about 20 % of the heating costs. The system can help to create 
a better indoor climate.  

Economics 
Investment and operating costs depend on the choice of fuel and are estimated as follows [ 470, 
Netherlands 2011 ]: 

 

 

 

 

investment requirements: EUR 1.5/ap, (EUR 1.3–1.7/ap); 

annualised investment costs: EUR 0.23/ap/yr, (EUR 0.20–0.26/ap/yr);  

annual operating costs: EUR 0.22/ap/yr, (EUR 0.15–0.28/ap/yr);  

total annual cost: EUR 0.45/ap/yr, (EUR 0.41–0.48/ap/yr). 

Intensive Rearing of Poultry or Pigs 

341 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Example plants 
Around 15 % of the Dutch bird capacity was equipped with this system at the end of 2009. 

Reference literature 
[ 470, Netherlands 2011 ] [ 471, Netherlands 2011 ] 

4.6.4.3 

Perforated floor with a forced air drying system 

Description 
Birds  are  raised  on  an  elevated  and  perforated  double  floor  that  is  covered  with  litter  (see 
Figure 4.20).  Air  is  continuously  blown  through  the  perforations  to  dry  the  litter.  The 
perforations cover a minimum surface area of 4 % of the total floor area and are protected by a 
plastic or metal grid. A continuous upward airstream flows through the perforated floor, with a 
minimum capacity of 2 m3 per hour per broiler place. Manure and litter remain on the floor for 
the whole growing period (about 6 weeks). The continuous airflow dries the litter (> 70 % dry 
matter)  and  this  results  in  reduced  ammonia  emissions.  Improved  designs  can  improve  the 
distribution of the drying air by channelling the airstream. 

342 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

A. 

B. 

C. 

Source:[ 44, IKC 2000 ] 

Figure 4.20:  Schematic  representation  of  a  forced  drying  system  with  a  perforated  floor  for 
broilers (A), an improved design (B), and a detail of the floor of the improved design 
(C) 

Achieved environmental benefits 
The aeration of the litter and droppings leads to a large reduction in ammonia emissions. 

Cross-media effects 
High  energy  input is required because  of  the forced ventilation,  which  doubles the power  use 
and costs compared with the reference. The airflow through a very dry litter may result in higher 
dust emissions. 

Environmental performance and operational data 
The associated emission level for ammonia is 0.014 kg NH3 per broiler place per year. 

Intensive Rearing of Poultry or Pigs 

343 

 
 
 
 
 
 
 
 
 
Chapter 4 

The  dry  matter  content  of  the  manure  is  as  high  as  80 %,  causing  a  lot  of  dust  in  the  broiler 
house. The birds are cleaner but the farmer needs to protect himself with a face mask. Mucking 
out and cleaning between growing periods requires more  labour compared with other housing 
systems for broilers.  

Technical considerations relevant to applicability 
The  system  can  only  be  used  in  new  buildings,  as  a  sufficient  pit  depth  (2 m)  under  the 
perforated floor is necessary and will not normally be available in existing buildings. With an 
improved design, a shallower depth will be required. 

Animal welfare considerations and high levels of dust emissions may preclude the application 
of  this  technique,  unless  it  is  combined  with  other  measures,  such  as  air  cleaning  systems. 
Indeed, the system is no longer applied in Germany, due to the high dust loads in the air and the 
increased energy demand for aerating the litter. 

Economics  
With  the  deep  litter  system  taken  as  a  reference,  this  housing  system  requires  an  extra 
investment of about EUR 3 per broiler place, which means that it is about 25 % more expensive. 
This corresponds to an extra investment of EUR 45.5 per kg NH3 emissions reduced. A further 
calculation can be made to determine the extra investment costs for the perforated floor, which 
are equivalent to EUR 65.90 per m2 and a stocking density of 20 broilers per m2. In this case, 
the  extra  operating  costs  are  EUR 0.37  per  broiler  place  per  year.  Extra  costs  associated  with 
cleaning out should also be considered. This system implies high energy costs and benefits are 
limited to a reduction in the NH3 emissions only [ 506, TWG ILF BREF 2001 ]. 

Driving force for implementation 
None  reported.  An  increase  in  the  DM  content  of  the  manure  may  be  associated  with  other 
advantages, such as a reduction in the required storage space and the volume to be transported.  

Example plants 
In 2012, about 1 695 000 bird places in the Netherlands (2 % of the national broiler population) 
were fitted with this technique [ 468, CBS 2011 ]. 

Reference literature 
[ 44, IKC 2000 ] [ 468, CBS 2011 ] [ 506, TWG ILF BREF 2001 ] 

4.6.4.4 

Litter on manure belt and forced air drying (in case of tiered floor 
systems) 

Description 
The  broilers  are  kept  in  a  multi-floor  system  on  tiers  equipped  with  manure  belts,  where  a 
continuous downward or upward draught is applied through the tiered floor arrangement.  

Bedding  is  added  on  the  manure  belts  before  placing  the  birds  in  the  tiers.  Corridors  for 
ventilation are left between the rows of tiers. One corridor is used to bring the air to the tiers; the 
air is then conveyed towards the other corridor by means of the pressure drop generated by the 
ventilators.  The  air  is  directed  towards  the  bedding  material  on  the  manure  belt.  The  litter  is 
removed  together  with  the  flock,  at  the  end  of  the  cycle.  The  manure  belts  are  also  used  to 
remove the fattened broilers at the end of the cycle. 

The  system  can  be  used  in  combination  with  a  separate  initial  stage  (described  in 
Section 4.6.4.5) where broiler chicks are hatched and grown for a limited time on manure belts 
with bedding in a multi-tiered system [ 473, Infomil 2011 ]. 

344 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
A schematic overview of the tiered floor system, with bedding on manure belts and forced air 
drying,  is  shown  in  Figure 4.21.  A  cross  section  of  the  system,  including  the  airflows,  is 
presented in Figure 4.22. 

Chapter 4 

Source: [ 473, Infomil 2011 ] 

Figure 4.21:  Schematic overview of the tiered floor system with two rows and six floors 

Source: [ 473, Infomil 2011 ] 

Figure 4.22:  Schematic cross section and principle of a tiered floor system  with forced drying for 

broilers 

Achieved environmental benefits 
Ammonia emissions are reduced as a result of the forced drying of the litter with air.  

Cross-media effects 
More electricity is needed to operate the ventilation air fans. 

Intensive Rearing of Poultry or Pigs 

345 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

With the upward movement of the air and a manure dry matter content of 80 %, dust problems 
might arise and the use of a face mask is recommended for farmers. Dust is less of a problem 
with the downward flow design.  

Environmental performance and operational data 
The  amount  of  bedding  material  needed  is  0.6 kg/m2.  Ventilation  is  reported  to  vary  from 
0.5 m3/ap/h in the cold season to 2.4 m3/ap/h in the warm season. The space per bird is reported 
to be equivalent to 0.045 m2 (22 birds per m2). 

Ammonia emissions are reduced to 0.02 kg NH3 per broiler place per year, corresponding to a 
reduction  of  75 %  compared  to  the  reference  system  used  in  the  Netherlands,  for  which  an 
emission of 0.080 kg NH3 per broiler place per year is considered. 

Because of the tiered floor configuration, the number of birds per m3 of house is higher than in 
traditional  Dutch  housing  systems.  The  heat  distribution  is  improved  by  air  blowing  and  the 
heating costs per bird place are reduced by 50 % [ 587, Netherlands 2010 ]. 

The system has high demands on the design of ventilation air to ensure fresh air to all the layers 
and the drying of litter on the belts. Drinkers without leakage are also needed. 

Technical considerations relevant to applicability 
This system can be applied to new and existing broiler houses. As the system is built up in tiers, 
existing buildings must have sufficiently high side walls to accommodate the system.  

Economics 
An  extra  investment  of  EUR 2  per  broiler  place  (equivalent  to  an  annualised  cost  of 
EUR 0.6/ap/yr) is required compared to a conventional housing system. The technique offers a 
benefit  of  EUR 0.6  per  bird  place  per  year,  due  to  the  reduced  energy  use,  which  fully 
compensates the extra costs.  

Driving force for implementation 
In summer there is less heat stress on the animals because of the  airstream close to them. The 
system  improves  the  indoor  climate  in  the  direct  surroundings  of  the  animals.  Less  labour  is 
needed to keep more broilers. 

Example plants 
In  the  Netherlands,  two  farms  with  a  reported  number  of  359 000  bird  places  were  equipped 
with this system in 2008. 

Reference literature 
[ 44, IKC 2000 ] [ 473, Infomil 2011 ] [ 585, Netherlands 2010 ] [ 587, Netherlands 2010 ]  

4.6.4.5 

Separate hatching and growing of broiler chicks for a limited time 
(in case of tiered floor systems) 

Description 
This housing technique is a combination of two housing systems. The first consists of a multi-
tiered system where the incubated eggs are hatched and the chicks are reared for a limited time 
on bedding on manure belts (patio system). The second system is where the broilers are brought 
up  to  their  final  weight;  it  may  consist  of  a  traditional  house  or  the  tiered  floor  system,  as 
described in Section 4.6.4.4, where bedding is used on the manure belts [ 473, Infomil 2011 ].  

Achieved environmental benefits 
This system, combined with a second rearing stage for broilers, allows a more effective use of 
low-emission (but expensive)  systems. Therefore, the overall annual ammonia emissions from 

346 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

the two combined rearing stages are reduced due to the better exploitation of the second housing 
technique. 

Cross-media effects 
No  specific  cross-media  effects  have  been  reported.  The  cross-media  effects  depend  on  the 
combined housing system for the second rearing phase.  

Environmental performance and operational data 
Eggs are placed in the first system three days before hatching until the chicks are 13 or 19 days 
of  age,  when  they  are  moved  to  the  second  housing  system  where  they  will  reach  their  final 
weight. The chicks are kept in a multi-floor system on tiers, with bedding on the manure belts, 
which  are  also  used  to  transport  them  out  of  the  house.  At  the  moment  of  the  transfer,  the 
maximum  bird  density  is  71  or  48  birds  per  m2  for  13  or  19  days  of  age,  respectively.  The 
longer  the  chicks  stay  in  the  separate  hatching  system,  the  shorter  they  stay  in  the  second 
system. 

The corridors between the stacks of tiers are used to direct  the airflow. The side of the stacks 
facing the corridor, where the air is coming from, is closed, except for the air inlets; in this way, 
the flow is directed along the bedding material on the manure belt and then to the other side, 
where it is collected by ventilators placed on top of the house. The manure belts are emptied and 
then covered with new bedding each time a new flock is  introduced. The collected manure is 
stored in covered containers and removed from the farm within 2 weeks.  

The system optimises the start of young broilers  in the first hours  after hatching as they have 
immediate  access  to  water  and  feed.  Additionally,  chicks  need  less  heating  as  they  live  in  a 
small boxed place. Birds are moved at an age when they are stronger and only over a very short 
distance,  as the next rearing system should normally be  on the same farm (in the Netherlands 
the  system  is  only  allowed  on  this  condition).  The  two  housing  occupations  are  synchronised 
through  all  production  stages,  depending  on  the  length  of  the  stages,  in  order  to  optimise  the 
occupation and displacements (see Figure 4.23). 

Source: [ 93, Netherlands 2010 ] [ 94, Netherlands 2010 ] 

Figure 4.23:  Example  of  a  time  flow  pattern  synchronising  the  patio  hatching/raising  cycle 

(19 days) with the finishing cycle in the different houses  

Ammonia emissions from the separate hatching and growing system for young broilers are 3 g 
or 9 g per bird place per year, respectively for the 13 days and 19 days management, including 
the periods when the system is necessarily empty between cycles. These levels do not include 
emissions  from  the  second  system  (second  rearing  stage).  Total  ammonia  emissions  are 
calculated as the sum of the emissions over the total standard length of rearing (6 weeks) in the 
two housing systems used in combination, and largely depend on which system is used for the 
second  rearing  stage,  a  low-emitting  or standard  housing  system. This  variation  is  reported in 
Table 4.64.  

Intensive Rearing of Poultry or Pigs 

347 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Not only is the total space needed at the farm level smaller for the same number of reared birds, 
but cycles in the house for the second stage are also run in shorter turns. The ratio between the 
numbers of bird places in the two systems depends on the duration of growing phases, and can 
vary from 1 : 1 to 1 : 2. The system has a high demand on the design of the ventilation system to 
ensure even distribution of fresh air to all the layers. 

Technical considerations relevant to applicability 
This system can be built in new houses but can only be retrofitted in existing houses that have 
high side walls.  

Economics 
More  birds  can  be  managed  by  one  person.  In  general,  the  economic  benefit  of  the  farm  is 
optimised by keeping more animals. 

Driving force for implementation 
The driving force is increased productivity due to the higher number of cycles per year, which is 
the result of raising young birds while there are also broilers present on the farm at the end of 
the growing period. 

Example plants 
Two farms in the Netherlands are equipped with these systems. Permitting authorities request 
that  the  housing  where  birds  are  moved  to  reach  slaughter  weight  be  equipped  with  low-
emission systems. 

Reference literature 
[ 93, Netherlands 2010 ] [ 94, Netherlands 2010 ] [ 473, Infomil 2011 ] 

4.6.4.6 

Heated and cooled littered floor (combideck system) 

See Section 4.5.5.3. 

4.6.5 

Techniques for housing of broiler breeders  

The  chain  for  producing  broiler  meat  starts  with  the  fertilised  eggs  that  are  produced  in  the 
broiler breeder farms. Hatching eggs are delivered to the hatchery plant, which normally return 
one-day-old  chicks  to  the  broiler  farms.  The  two  groups  of  males  and  females  are  uniformly 
bred.  

In  the  reproduction  phase, animals  need  to  be  reared together  but  should  be  fed  separately  to 
maintain reproductive efficiency. Separate feeding is done by means of feeding lines at different 
heights that hence are accessible only to animals of the right sizes. 

Traditional systems were previously used to house breeders, like cages and fully littered floors 
(see  Section 2.2.2).  New  systems  allow lower  emissions  and  more  effective  management,  and 
are  derived  from  cages,  deep  litter  housing  and  aviaries.  According  to  the  provisions  of  the 
'Recommendation  concerning  domestic  fowl  (gallus  gallus)'  (Appendix  II)  adopted  by  the 
Council of Europe in 1995, cages should be fitted with perches, a litter area and nest. Old cages 
not fulfilling  these requirements  may  only  be  used  till they  are  worn  out.  Descriptions in this 
section are simplified, as basic systems are described in Section 4.6.1 and Section 4.6.2 for the 
rearing of laying hens. A summary of reported achievable emission levels from housing systems 
applied for the rearing of broiler breeders is presented in Table 4.69. 

348 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 4.69:  Summary of emissions in systems for rearing broiler breeders 

Description 

NH3 

PM10 

(kg/ap/yr) 

Odour 
(ouE/ap/s) 

Source 

Chapter 4 

Section 4.6.5.1 Manure removal by belts (in case of cage systems)  
Group cage, manure belt, forced 
drying 

0.080 (1) 

NI 

NI 

[ 108, BE Flanders 
2010 ] 

Section 4.6.5.2 Manure belt or scraper (in case of deep litter with a manure pit) 

Deep litter  

0.58 

0.043 

0.93 

Deep litter with manure belts  

0.245 (4) 
(0.216–0.31) (2) 

0.049–0.8 
(3) (5) 

0.93 (3) 

Deep litter with a scraper  

0.290 (3) 

NA 

NA 

[ 638, BE Flanders 
2014 ] 
[ 110, Netherlands 
2010 ] 
[ 108, BE Flanders 
2010 ] 

Section 4.6.5.3 Forced air drying of manure via tubes (in case of deep litter with a manure pit) 
Forced manure drying by 
horizontal pipes (in case of deep 
litter with a slatted floor) 
Vertical tubes for forced manure 
drying (in case of deep litter 
with a slatted floor) 

0.25 (4) 
(0.183–0.287) 
(2) 
0.435 (4) 
(0.343–0.528) 
(2) 

[ 109, Netherlands 
2010 ] 

[ 112, Netherlands 
2010 ] 

0.043 (3) 
(5) 

0.049 (3) 

0.93 (3) 

0.93 (4) 

Section 4.6.5.4 Forced air drying of manure using perforated floor (in case of deep litter with a 
manure pit) 
Forced drying using perforated 
floor (in case of deep litter) 

0.23 (4)  
0.210–0.248 (2) 

[ 111, Netherlands 
2010 ] 

0.043 (3) 

0.93 (3) 

Section 4.6.5.5 Litter-based system with circulating fans  
Deep 
circulating fans  

0.183 (2) 
0.188 (4) 
Section 4.6.5.6 Manure belts (in case of aviary) 

system  with 

litter 

0.028 (3) 

0.18 (3) 

[ 114, Netherlands 
2010 ] 

Aviary with manure aeration on 
belts  

0.170 (4) 
0.13–0.202 (2) 

0.049 (3) 

0.93 (3) 

0.130 (1) 

Aviary with manure aeration on 
belts and on litter  
(1) Modelled values (e.g. results based on N balance). 
(2) Measured values. 
(3) Values derived by expert judgement based on conclusions by analogy. 
(4) Derived from measurements. 
(5) Values expressed as total dust.  
NB: NI = no information provided. 

NI 

NI 

[ 108, BE Flanders 
2010 ] 
[ 113, Netherlands 
2010 ] 
[ 108, BE Flanders 
2010 ] 

Disease prevention is a particularly critical aspect for parent stock farms (breeders). Biosecurity 
requires the application of practices and procedures (e.g. cleaning, disinfection, 'all-in, all-out') 
aiming to prevent or reduce the entry (to the housing system) and spread of microorganisms that 
might  cause  a  disease.  In  the  evaluation  of  individual  housing  techniques,  the  possible 
interaction with biosecurity must be considered. 

4.6.5.1 

Manure removal by belts, forced manure drying (in case of cage 
systems) 

Description 
The birds are housed in cage systems fitted with perches, a litter area and nest. The manure falls 
through  the  floor  onto  the  underlying  manure  belt  and  is  dried  with  preheated  air,  and  it  is 
removed once a week. An air mixing cabinet may be equipped with a heating unit to preheat the 
air. 

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Chapter 4 

Achieved environmental benefits 
Emission of ammonia is reduced through frequent removal and drying of the manure on the belt. 

Cross-media effects 
See Section 4.6.1.1. 

Environmental performance and operational data 
The drying system and the manure removal from the belt must be dimensioned to allow for  a 
dry matter content in the manure of at least 50 %. Emissions are estimated at 0.080 kg NH3 per 
bird place per year. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
No information provided. 

Driving force for implementation 
No information provided. 

Example plants 
In  Belgium  (Flanders),  two  farms  of  broiler  breeders  reported  using  a  cage  system  [ 467,  BE 
Flanders 2010 ]. 

Reference literature 
[ 467, BE Flanders 2010 ]  

4.6.5.2 

Manure belt or scraper (in case of deep litter with a manure pit) 

Description 
The housing consists of a concrete littered floor where the birds can move around freely. Part of 
the floor is elevated and slatted, under which manure storage takes place. Wet droppings can be 
removed by a manure belt to a covered outside storage. The frequency of manure removal is at 
least  twice  per  week.  The dry  matter  content  of  the manure  at  the time  of  removal  is  at least 
30 %.  

Alternatively, a scraper that is fitted to a shallow manure pit with a polished and non-adhesive 
concrete floor can be used for  daily removal of the manure under the slatted floor to a closed 
external storage. 

Achieved environmental benefits 
Ammonia emissions are reduced by the frequent removal of the droppings, in combination with 
aeration of the manure on the belts. 

Cross-media effects 
Increased  energy  consumption  is  required  for  operating  the  frequent  manure  removal  by  belt, 
with the associated indirect emissions for electric energy production. 

Environmental performance and operational data 
The maximum bird density is restricted to 7–8 animals per m2. The available area is about half 
slatted and half bedded floor.  

The drinking, feeding and resting equipment is situated above the slatted floor. At the start of 
each production cycle, a layer of litter of at least 3 cm has to be applied. The manure is removed 
at least twice a week from the belts, and at least once a day where the scraper is installed. In 

350 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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order to minimise the emissions originating from the droppings in the littered area, the average 
dry matter content of the bedding should be maintained at least 70 %. 

Ammonia  emissions  equivalent  to  0.216–0.310 kg  NH3  per  bird  place  per  year  have  been 
reported for the system using manure belts [ 110, Netherlands 2010 ]. If a scraper is installed, 
NH3 emissions of less than 0.290 kg NH3 per bird place per year have been estimated, based on 
measurements  performed  in  similar  farms  for  laying  hens  [  108,  BE  Flanders  2010  ].  The 
average reported ammonia emissions from the housing system with frequent removal by manure 
belts  (0.245 kg  NH3/ap/yr)  are  58 %  lower  than  the  emission  levels  of  the  reference  system, 
corresponding to the traditional deep litter system used in the Netherlands (0.580 kg NH3/ap/yr). 

Technical considerations relevant to applicability 
The placement of a manure belt or scraper underneath the slatted floor in an existing manure pit 
is  not  always  possible  and  involves  additional  costs,  compared  with  the  application  of  the 
technique to a new housing system. 

Economics 
In the Netherlands, in the case of housing systems equipped with manure belts, the investment 
per bird  place is  evaluated  to  be  in  the range  of  EUR 14.40–19.80  and the  extra cost for  new 
houses is equivalent to EUR 3.5/ap/yr [ 110, Netherlands 2010 ]. 

Driving force for implementation 
Frequent manure removal is an effective alternative to more expensive techniques.  

Example plants 
In the Netherlands, in 2008 around 8 % of broiler breeders were reared in houses with frequent 
manure removal by belts [ 110, Netherlands 2010 ]. The application of the alternative version 
with a scraper is reported in a new farm in Belgium (Flanders) [ 467, BE 2010 ]. 

Reference literature 
[ 108, BE Flanders 2010 ] [ 110, Netherlands 2010 ] [ 467, BE Flanders 2010 ] 

4.6.5.3 

Forced air drying of manure via tubes (in case of deep litter with a 
manure pit) 

Description 
This system consists of a concrete littered floor where the animals can move around freely. Part 
of the floor is elevated and has a slatted floor under which the manure pit is situated. At least 
one third of the available area has to be a littered floor. Ammonia emissions are reduced by the 
aeration  of  the  manure  collected  in  the  pit  with  air  from  an  air  mixing  cabinet  or  a  heat 
exchanger. The  pipes  through  which  the  air  is  blown  are  situated  underneath  the  slatted  floor 
and can be placed horizontally or vertically.  

In  the  horizontal  version,  the  pipes  are  installed  under  the  slatted  floor  parallel  to  the  laying 
nests and can be moved vertically according to the manure level in such a way that the vertical 
distance between the pipes and the manure is always close to 20 cm. Alternatively, the aerating 
tubes can be installed vertically under the slatted floor (see Figure 4.24). The functional areas 
for feeding, drinking and resting are arranged above the slatted floor.  

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Legend: 

1) Laying nests 
3) Litter area 
5) Forced air tubes 
7) Drain away canal 

Source: [ 44, IKC 2000 ] 

2) Slatted floor 
4) Manure pit 
6) Air supply pipes 
→ Direction of airflow 

Figure 4.24:  Cross section of system with forced air drying by vertical tubes  

Achieved environmental benefits 
See Section 4.6.2.1.3. 

Cross-media effects 
The  system  with  the  horizontally  placed  tubes  implies  additional  energy  consumption, 
depending on the air temperature and the amount of forced air used for drying the manure. 

Environmental performance and operational data 
The  maximum  animal  density  is  restricted  to  7–8  animals  per  m2,  including  roosters.  The 
volume of air blown over the manure by horizontal pipes is reported to be 2.5 m3 per bird per 
hour, at a minimum temperature of 24  °C; while 50 % of the inlet air comes from outside the 
house (fresh air). 

The tubes installed vertically are robust. They blow air through small holes at a minimum rate 
of 1 m3 per hour per animal. At least 50 % of the used air comes from outside and is heated to a 
minimum temperature of 20 °C. 

Ammonia  emissions  have  been  reported  for  the  version  with  horizontal  pipes  ranging  from 
0.183 kg/ap/yr to 0.287 kg/ap/yr, and from 0.343 kg/ap/yr to 0.528 kg/ap/yr for the version with 
vertical pipes. The reported average values for ammonia emissions for the vertical configuration 
of  pipes  (0.435 kg  NH3/ap/yr)  and  for  the  horizontal  configuration  (0.25 kg  NH3/ap/yr)  are, 
respectively,  57 %  and  25 %  lower  than  the  emissions  associated  with  the  reference  housing 
system in the Netherlands, consisting of a traditional deep litter system (0.580 kg NH3/ap/yr).  

Technical considerations relevant to applicability 
See Section 4.6.2.1.3. 

Economics 
Cost data concerning deep litter systems with manure pit aeration for both configurations, with 
horizontal and vertical pipes, are presented in Table 4.70. 

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Table 4.70:  Cost data for deep litter systems equipped with manure pit aeration through pipes 

System configuration 

Horizontal pipes 
(drying from above) 

Vertical pipes 

Investment 
costs 

EUR/ap 
17 
(14.3–19.7) 
16.6 
(14–19.3) 

Annualised 
investment 
costs 

Annual 
operating costs 
(energy) 
EUR/ap/yr 

Total cost 

1.7 

1.67 

4.6 

0.51 

6.65 

2.18 

Source: [ 109, Netherlands 2010 ] [ 112, Netherlands 2010 ] 

Data  concerning  extra  investment  and  operating  costs,  in  comparison  with  a  reference 
traditional  deep  litter  system,  are  also  reported  from  the  Netherlands  and  presented  in 
Table 4.71. 

Table 4.71:  Extra costs for  manure pit aeration through pipes (in case of  deep litter systems), in 

comparison with a reference system  

System 
configuration 

Extra investment 
costs 

EUR/ap 

Annualised 
extra 
investment costs 

Annual extra 
operating costs 
(energy) 
EUR/ap/yr 

Total extra 
costs 

Horizontal pipes 
(drying from above) 
Vertical pipes 
Source: [ 589, Netherlands 2010 ] 

3.40 

3.05 

0.36 

0.31 

4.6 

0.51 

4.96 

0.82 

Driving force for implementation 
See Section 4.6.2.1.3. 

Example plants 
In Belgium (Flanders), 10 housing systems are using the technique, including farms above and 
below the IED capacity threshold [ 467, BE 2010 ]. In the Netherlands, 8 % of birds are housed 
in systems equipped with manure pit aeration, applying the configuration with horizontal pipes. 

Reference literature  
[ 44, IKC 2000 ] [ 108, BE Flanders 2010 ] [ 109, Netherlands 2010 ] [ 112, Netherlands 2010 ] 
[ 467, BE Flanders 2010 ] [ 589, Netherlands 2010 ] 

4.6.5.4 

Forced air drying of manure using perforated floor (in case of deep 
litter with a manure pit)  

Description 
See Section 4.6.2.1.4. 

Achieved environmental benefits,  
See Section 4.6.2.1.4. 

Cross-media effects.  
See Section 4.6.2.1.4. 

Environmental performance and operational data 
In Belgium and in the Netherlands, values from 0.210 kg to 0.248 kg NH3 per animal place per 
year for ammonia emissions are associated with this system. 

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353 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Technical considerations relevant to applicability 
The system is applicable to new and existing houses for broiler breeders. 

Economics 
The Netherlands reported investment costs from EUR 12.90 to EUR 17.80 per bird place, with 
annual  operating  costs  of  around  EUR 0.25/ap/yr.  The  annualised  investment  costs  are 
equivalent  to  EUR 1.5  /ap/yr  and  the  total  annual  costs  are  about  EUR 1.75/ap/yr.  The  extra 
costs for a new house are estimated to be equivalent to EUR 1.8 /ap/yr. 

Driving force for implementation 
See Section 4.6.2.1.4. 

Example plants 
In  Belgium  (Flanders),  one  farm  for  broiler  breeders  is  reported to  use this  system  [  467,  BE 
Flanders 2010 ]. 

Reference literature 
[  111,  Netherlands  2010  ]  [  108,  BE  Flanders  2010  ]  [  467,  BE  Flanders  2010  ]  [  589, 
Netherlands 2010 ] 

4.6.5.5 

Litter-based systems with circulating fans  

Description 
In  a  deep  litter  system  without  a  manure  pit  and  where  centralised  ventilation  is  not  fitted, 
vertical shafts equipped with ventilators are hung from the ceiling. At the bottom of the shaft, at 
a maximum of 1.20 m above the litter, a special element is placed to let the air come out in a 
horizontal  direction.  See  Sections  4.5.4.2.1.1  and  4.6.4.2.1  for  a  full  description  of  the 
technique. 

Achieved environmental benefits 
The  ventilators  mix  the  indoor  air  and  allow  for  ammonia  emission  reductions  and  a  better 
environment for the animals. 

Cross-media effects 
See Section 4.6.4.2.1. 

Environmental performance and operational data 
The shafts are placed in two rows along the length of the house at a rate of one ventilator every 
150 m2.  Ventilators  have  a  minimum  capacity  of  1.8  m3/hour  per  bird,  without  any  pressure 
drop. At the beginning of the cycle (one-day-old pullets), the ventilators start at a capacity of 
10 % and progressively reach 100 % capacity on day 40.  

Associated emissions per animal place are 0.183–0.188 kg/yr of ammonia, 0.028 kg/yr of PM10 
and 0.18 ouE/s/bird. 

Technical considerations relevant to applicability 
See Section 4.6.4.2.1. 

Economics 
From the Netherlands, the extra  investment costs for the ventilation system are reported to be 
equivalent  to  EUR 1  per  bird  place.  The  operating  costs  are  reported  to  be  equivalent  to 
EUR 0.135 per bird place per year.  

Driving force for implementation 
See Section 4.6.4.2.1. 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Example plants 
See Section 4.6.4.2.1. 

Reference literature 
[ 114, Netherlands 2010 ] [ 469, Netherlands 2011 ] 

4.6.5.6 

Manure belts (in case of aviary) 

Description 
The  system  is  basically  an  aviary  system  where  the  animals  can  move  freely  throughout  the 
entire house, which consists of different levels (tiers) of slatted floor and littered area on a solid 
concrete floor (see Section 4.6.2.2.1). Manure removal belts are installed underneath the slatted 
floor.  The  manure  is  collected  on  these  belts  and  can  be  dried  by  (preheated)  forced  air, 
conveyed through pipes above or along the belts. Additionally, the manure on the littered floor 
area  can  be  dried  by  preheated  air  (e.g.  from  heating  units),  allowing  a  greater  emissions 
reduction. 

An extra level can be built on top of the laying nest (see Figure 4.25), allowing more birds (10–
15 %)  to  be  placed  in  the  same  house.  Functional  areas  for  feeding,  drinking  and  resting  are 
arranged above the dropping area. 

Source:[ 44, IKC 2000 ] 

Figure 4.25:  Scheme of an additional tier over the nests in an aviary system  

Achieved environmental benefits 
Ammonia emissions are reduced by the frequent removal and drying of the manure on the belts.  

Cross-media effects 
The additional tier above the nest gives the possibility for females to hide from the males. This 
can decrease the fertility and hatchability of the eggs. 

Environmental performance and operational data 
The manure on the manure belt should be removed from the housing at least once a week and at 
that time should have a dry matter content of at least 50 %.  

Ammonia  emissions  were  measured  as  0.170 kg  of  NH3  per  bird  per  year  (ranging  from 
0.130 kg to 0.202 kg NH3/ap/yr), achieved with at least a weekly manure removal and manure 
drying  with  preheated  air.  The  reported  emissions  of  ammonia  are  71 %  lower  than  those 
associated  with  the  use  of  the  traditional  reference  system  adopted  in  the  Netherlands  (deep 
litter with emissions equivalent to 0.580 kg NH3/ap/yr). 

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355 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Technical considerations relevant to applicability 
See Section 4.6.2.2.1. 

Economics 
The  system  configuration  with  the  added  tier,  is  associated  with  investment  costs  from 
EUR 15.00/ap  to  EUR 20.60/ap,  annualised  investment  costs  of  EUR 1.85/ap/yr,  annual 
operating costs of EUR 0.50/ap and total annual costs of EUR 2.35/ap. 

Driving force for implementation 
See Section 4.6.2.2.1. 

Example plants 
See Section 4.6.2.2.1. 

Reference literature  
[ 44, IKC 2000 ] [ 108, BE Flanders 2010 ] [ 113, Netherlands 2010 ] 

4.6.6 

Techniques for housing of turkeys 

4.6.6.1 

Forced ventilation and a non-leaking drinking system (in case of 
solid floor with deep litter) 

Description 
Turkeys are reared in a closed, thermally insulated building, with forced ventilation. The solid 
floor is fully bedded with wood shavings and/or straw. If necessary, additional straw is added 
during the fattening period. No separate functional areas exist. Solid manure is removed at the 
end  of  the  cycle  when  the  building  is  cleaned  prior  to  the  next  cycle.  The  cycle  consists  of 
rearing all turkeys of both genders for  4 to 6 weeks, which can be prolonged, after separating 
the stags, with the finishing period of the hens lasting until week 17. After sex separation, stags 
can  be  fattened  in  this  system  too,  but  more  often  they  are  finished  in  houses  with  natural 
ventilation (see Section 4.6.6.2). The drinking-water system design and operation are such that 
spillage on litter is prevented. See also Section 2.2.3.2. 

Achieved environmental benefits 
The absorbent material (e.g. straw) binds urine and faeces in the litter and provides a dry area; 
therefore  emissions  of  ammonia  are  reduced.  In  addition,  floor  insulation  (e.g. concrete,  clay) 
prevents water condensation in the litter. 

Cross-media effects 
Dust emissions are typically increased in deep litter housing systems. 

Environmental performance and operational data  
The quantity of  bedding added is 9–12 kg/m2 in France, considering possible top-up additions 
during the fattening period. In Germany, the amount of bedding material required for the initial 
mixed  gender  rearing  period  is  reported  to  be  2.2 kg/ap/yr  of  chopped  straw,  and  for  the 
fattening  period  0.8 kg/ap/yr  of  wood  shavings,  plus  5.8 kg/ap/yr  of  chopped  straw.  From 
Finland, the typical quantity of wood shavings required is reported to be 2–5 kg/ap/yr. 

In  the  first  seven  days  after  arrival,  the  birds  are  reared  in  confinement  rings  that  are 
progressively  made  wider.  Daily  controls  are  needed  for  temperature,  litter  moisture  and  the 
height of the feeding and drinking equipment. The ventilation is controlled in order to provide 
the birds with the required air volumes, as reported in Table 4.72. 

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Table 4.72:  Ventilation parameters in turkey rearing  

Chapter 4 

Period 

Young turkeys  Female turkeys   Male turkeys  
m3 per bird per hour 
1–3.6 
6–32 

0.1–1 
Cold season 
Warm season 
0.6–14.6  
Source: [ 118, Germany 2010 ] [ 500, IRPP TWG 2011 ] 

1–5.5 
6–48.6 

Reported emission levels associated with the rearing of turkeys are presented in Table 4.73. Air 
cleaning systems used for the reduction of ammonia emissions from the rearing of broilers can 
be applied to turkey housing systems based on deep litter [ 131, Netherlands 2010 ]. However, 
except for scrubbers, the efficacy of the  ammonia-reducing  techniques will be lower than that 
achievable with broilers, due to the larger amount of manure and higher dry matter content of 
the  litter.  In  the  Netherlands,  the  effectiveness  of  ammonia-reducing  techniques  applied  in 
turkey housing is considered to be half that achievable in broiler housing [ 508, TFRN 2014 ].  

Table 4.73:  Emissions from turkey rearing systems, with forced  or natural ventilation (in case of 

deep litter) 

Rearing phase and 
parameters 

Mixed gender starting 
rearing period  
(4–6 weeks; weight: 2 kg)  

Emission levels 
PM10 

Odour (1) 

kg PM10/ap/yr  ouE/s/bird 

Ammonia 
kg 
NH3/ap/yr 

Source 

0.15 (2) 

0.07 (3) (4) 

0.007 (2) 

[ 118, Germany 2010 ] 

Mixed gender for the whole 
rearing period 

0.263–
0.374 (5) 

NI 

NI 

Female turkeys, fattening 
period (16 weeks; weight: 
10–11 kg), forced/natural 
ventilation 

0.387 (2) 

0.3 (3) (4) 
0.09 (2) 

0.4 (2) 

0.045 (6) 

0.5 (6) 

NI 

[ 624, IRPP TWG 2013 ] [ 
633, ITAVI 2013 ]  
[ 656, Ponchant et al. 2012 ] 
[ 624, IRPP TWG 2013 ] [ 
633, ITAVI 2013 ] 
[ 656, Ponchant et al. 2012 ] 
[ 118, Germany 2010 ] 
[ 119, Germany 2010 ] 
[ 500, IRPP TWG 2011 ] 
(UK) 
[ 118, Germany 2010 ] 

0.138 (3) 

0.710 (2) 

0.680 (2) (7) 

0.8 (3) (4) 
0.24 (2) 
0.9 (6) 

Male turkeys, fattening 
period (20–21 weeks; 
weight: 21 kg), 
forced/natural ventilation 
Starting rearing period plus 
fattening of male turkeys 
(20 weeks; weight: 0.05–
18 kg), forced/natural 
ventilation 
(1) Values have been calculated from an emission of 32 ouE/s per LU and an average weight of 1.1 kg for the 

[ 102, UK 2010 ] 
[ 614, UK 2013 ] 

[ 119, Germany 2010 ] 
[ 500, IRPP TWG 2011 ] 

0.66 (3) (8) 

NI 

NI 

NI 

starting rearing period for turkeys, 6.25 kg for female fattening, and 11.1 kg for male fattening. 

(2) Derived from measurements.  
(3) Measured values.  
(4) Values expressed as total dust. 
(5) Modelled values (e.g. results based on N balance). 
(6) Values derived by expert judgement based on conclusions by analogy. 
(7) An emission level of 0.68 kg NH3/ap/yr is considered as the reference. 
(8) Derived from an emission of 93 g N/LU/d, and an average weight of 8 kg for male turkeys. 
NB: NI = no information provided.  

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357 

 
 
 
 
 
 
 
 
 
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Technical considerations relevant to applicability  
The technique is applicable to both new and existing houses. It is used for the rearing of young 
turkeys and, afterwards, for the fattening of female turkeys; optionally, the technique may also 
be applied for the fattening of male turkeys. 

Economics 
Figures that have been modelled in Germany indicate required investments of between EUR 53 
and  EUR 84  per  bird  place,  corresponding  to  annualised  costs  of  between  EUR 1.70  and 
EUR 7.30 per bird place per year. Annual operating costs are reported to be EUR 4.70 per bird 
place  per  year.  The  labour  demand  is  reported  to  be  0.1–0.13  h/ap/yr,  and  the  energy 
consumption for heating 0.12 kWh/ap/yr and for lighting 0.5 kWh/ap/yr. 

Driving force for implementation 
An  increased  productivity  with  structural  flexibility  combined  with  good  indoor  climate  is 
achieved at low investment and operating costs, since energy requirements are low.  

Example plants 
The system consisting of the starting rearing phase and the fattening period of hens is normally 
used in Germany, in rotation with the system for rearing stags described in Section 4.6.6.2. 

Reference literature 
[  102,  UK  2010  ]  [  118,  Germany  2010  ]  [  119,  Germany  2010  ]  [  131,  Netherlands  2010  ] 
[ 500, IRPP TWG 2011 ] [ 508, TFRN 2014 ] [ 614, UK 2013 ] [ 624, IRPP TWG 2013 ] [ 633, 
ITAVI 2013 ] [ 656, Ponchant et al. 2012 ] 

4.6.6.2 

Natural ventilation with a non-leaking drinking system (in case of 
solid floor with deep litter)  

Description 
After sex separation, stags are usually reared in houses with natural ventilation (with open side 
walls)  until  the  end  of  the  fattening  period.  The  slaughter  weight  for  stags  is  about  
18–21 kg,  achieved  at  an  age  of  20–21  weeks.  A  backup  ventilation  system  can  be  made 
available by  installing  extraction fans  on  one  side  of the shed.  In  the  UK, the  birds  can  often 
access open free ranges. Solid manure is removed at the end of each growing period when the 
building is cleaned prior to the next cycle. This type of housing system can optionally be used 
for  fattening  hens  (from  2 kg  to  10–11  kg)  or  for  the  whole  rearing  cycle  (from  0.05 kg  to 
18 kg).  A  scheme  of  the  deep  litter  housing  system  for  turkeys,  with  natural  ventilation,  is 
shown  in  Figure 4.26.  The  solid  floor  is  fully  covered  with  litter  which  can  be  added  to 
depending  upon  necessity.  The  drinking-water  system  design  and  operation  are  such  that 
spillage on litter is prevented. Naturally ventilated houses are reported to have a damp-proofing 
control applied to the floor to prevent moisture from passing into the interior [ 103, UK 2010 ]. 

358 

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Chapter 4 

Source: [ 119, Germany 2010 ] 

Figure 4.26:  Scheme of a naturally ventilated house for turkey fattening  

Achieved environmental benefits 
Naturally  ventilated  houses  demand  lower  energy  consumption.  A  reduction  of  emissions  is 
considered  possible,  due  to  the  lower  indoor  average  temperatures  associated  with  the  open 
climate design of the housing system. 

Environmental performance and operational data 
The  bedding  needs  frequent  top-ups  which  can  be  applied  daily.  Reported  emissions  from 
naturally ventilated turkey houses, with or without free ranges, do not show a difference from 
forced  ventilated  houses.  Emission  levels  for  both  naturally  ventilated  and  forced  ventilated 
housing systems are presented in Table 4.73. 

Technical considerations relevant to applicability  
No  technical  restrictions are  reported  for  the  implementation  of  the  technique.  Considerations 
for natural ventilation are in Section 4.5.6. 

Economics 
The same cost figures as for the system in Section 4.6.6.2 have been reported. In addition, the 
annual operating cost, calculated for a house of 8 750 bird places in Germany, is reported to be 
equivalent to EUR 4.7/ap/yr. 

Driving force for implementation 
Open climate houses provide a better indoor climate, due to lower average indoor temperatures. 
Systems  with  a  veranda  and/or  a  yard  offering  access  to  external  climate/stimuli  are  more 
animal-friendly.  

Example plants 
It is the most widespread system for stags in Germany. 

Reference literature 
[ 103, UK 2010 ] [ 119, Germany 2010 ] 

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359 

 
 
 
 
 
 
 
 
 
 
 
 
 
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4.6.7 

Techniques for housing of ducks 

4.6.7.1 

Frequent litter addition (in case of solid floor with deep litter)  

Description 
Ducks  are  reared  on  solid  floors  with  bedding,  but  without  separate  functional  areas.  Two 
different rearing systems may be used: 'all-in, all-out' or two separate growing periods. In the 
'all-in, all-out' system, the complete rearing of the birds is carried out, and both the birds and the 
litter  are  removed  at  the  end  of  the  cycle.  With  the  two  separate  growing  periods  system 
(starting  and  finishing  rearing  periods),  the  birds  are  moved  to  another  house  after  the  first 
period. In the starting rearing period, the space per animal is reported to vary between 0.067 m2 
and  0.072 m2.  In  the  'all-in,  all-out'  system  and  in  the  fattening  period  for  the  two  separate 
growing stages, the space per animal is reported to vary between 0.143 m2 and 0.21 m2. Litter is 
maintained dry by frequent addition (e.g. daily) of fresh material upon necessity. 

Houses  can  be  forced  or naturally  ventilated  and  manure  is  always  removed  at  the  end  of the 
cycle. Houses that are used for the starting rearing period and for the 'all-in, all-out' system are 
of a closed type, well insulated, and equipped with forced ventilation and automatic feeding and 
drinking systems. If the finishing period is run separately, it may take place in a simpler open 
climate house, with natural ventilation. This housing system can be combined with a free-range 
system. 

Achieved environmental benefits 
Emissions  are  reduced  as  a  result  of  the  daily  topping  up  with  bedding  material  and  the 
consequent increased absorption of humidity. 

Cross-media effects 
The management of litter in the surroundings of the water source provided  for bathing can be 
difficult. 

Environmental performance and operational data 
The amount of bedding material used for the fully littered floor is reported from Germany to be 
equivalent to 7 kg/ap/yr for the starting rearing period, and 28 kg/ap/yr for the finishing period. 
From the Netherlands, the amount of bedding material is reported to be 1 kg of wheat straw per 
m2,  and  from  the  UK  4 kg/bird,  corresponding  to  around  23 kg/per  bird  place  per  year  for 
4.7 cycles/yr.  

The reported ventilation rates in forced ventilated, fully littered housing systems for Pekin ducks 
are summarised in Table 4.74. 

Table 4.74:  Ventilation rate range for forced ventilated Pekin duck rearing houses 

Rearing phase 

From 0.05 kg to 1.2–1.5 kg  
(1 to 21 days) 
From 1.2–1.5 kg to 3 kg 
(21 to 47 days) 

Warm period 
m3/bird place/h 

Cold period 
m3/bird place/h 

0.3–8 

3.3–11.3 

0.1–0.8 

0.6–1.3 

Source:[ 115, Netherlands 2010 ] [ 116, Germany 2010 ] [ 117, Germany 2010 ] [ 500, IRPP TWG 2011 ] 

In general, the drier the litter, the lower the level of ammonia emitted [ 152, Link CR 2006 ]. 
Emissions have  been  measured in  Germany  for the  two  rearing  periods  and  were found  to  be 
0.05 kg of ammonia and 0.01 kg of total dust per animal place per year for the starting period 
and  0.15 kg  of  ammonia  and  0.04 kg  of  total  dust  per  animal  place  per  year  for  the  finishing 
period.  Emission  figures  for  the  complete  cycle  reported  from  the  Netherlands  and  the  UK 
(estimated)  are  in  the  range  of  0.11 kg  to  0.227 kg  for  ammonia  and  0.078 kg  for  methane. 

360 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Emission  data  for  different  deep  litter  housing  systems  used  in  the  rearing  of  ducks  are 
presented in Table 4.75. 

Chapter 4 

Table 4.75:  Reported emission data from deep litter systems for the rearing of ducks 

[ 117, Germany 2010 ] 

[ 116, Germany 2010 ] 
[ 474, VDI 2011 ] 

Source 

0.05 (1) 

NH3 
kg/ap/yr 

PM10 
kg/ap/yr 

Odour  
ouE/s/bird 

0.01 (3)(4) 

0.1457 (1) 

0.04 (4) (3) 

0.29 (1) (2) 

0.098 (1) (2) 

Production system and 
rearing phase 
Deep litter with forced 
ventilation  
Pekin ducks, rearing (from  
0.05 kg to 1.2–1.5 kg in 1 to 21 
days) 
Deep litter with forced 
ventilation  
Pekin ducks, fattening (from 
1.2–1.5 kg to 3 kg in 21 to 47 
days) 
Deep litter with forced 
ventilation 
Pekin ducks, fattening (up to 
3.3 kg) 
Deep litter with forced 
ventilation 
All-in, all-out (from 0.05 kg to 
3.35 kg in 49 days) 
Deep litter with forced 
ventilation 
All-in, all-out (from 0.04 kg to 
3.3 kg in 49 days) 
Deep litter with forced 
ventilation (from 20 to 41 days) 
Deep litter with natural 
ventilation 
All-in, all-out (from 0.05 kg to 
3.6 kg in 47 days) 
(1)Value is derived from an average of 0.11 g dust/kg of live weight/day, an average weight of 1.9 kg for duck 

0.21  
(0.199–0.227) 
(4) 

0.026 (4)(3)(1) 

0.17 (4)(5) 

0.084 (6) 

0.49 (5) 

0.11 (6) 

0.11 (6) 

0.12 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 106, UK 2010 ] 

[ 152, Link CR 2006 ] 

[ 104, UK 2010 ] 

[ 115, Netherlands 2010 
] 

[ 646, COM 2013 ] 

fattening and 6 cycles per year.  

(2) Values have been calculated from an emission of 75 ouE/s per LU and an average live weight of 0.65 kg for duck 

rearing and 1.9 kg for duck fattening [ 474, VDI 2011 ]. 

(3) Values refer to total dust.  
(4) Measured values. 
(5) Value is derived from an average of 0.713 g NH3/kg of live weight/day, an average weight of 1.9 kg for duck 

fattening and 6 cycles per year. 

(6) Modelled values (e.g. results based on N balance). 
NB: NI = no information provided. 

Air cleaning systems used for the reduction of ammonia emissions from the rearing of broilers 
can  be  applied  to  duck  housing  systems  with  deep  litter.  However,  except  for  scrubbers,  the 
efficacy  of  the  techniques  will  be  lower  than  that  achievable  with  broilers,  due  to  the  larger 
amount  of  manure  and  higher  dry  matter  content  of  the  litter.  In  the  Netherlands,  the 
effectiveness  of  air  cleaning  techniques  applied  in  duck  housing  is  considered  to  be  half  that 
achievable in broiler housing. For ducks provided with water bowls, the efficacy may be even 
lower  [  508,  TFRN  2014  ].  Frequent  fresh  straw  addition  ensures  a  low  concentration  of 
ammonia in indoor air (4–8 ppm) [ 646, COM 2013 ]. 

Technical considerations relevant to applicability  
No technical restrictions are reported for the implementation of the technique. 

Intensive Rearing of Poultry or Pigs 

361 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
Comparable cost data are reported from Germany and the Netherlands, showing an investment 
of EUR 34–35 per bird place, for the 'all-in, all-out' housing systems and for the finishing period 
of the two-phase rearing  system.  The investment  cost  for the  starting  period  of  the  two-phase 
system  is  reported  from  Germany  to  be  equivalent  to  EUR 14  per  bird  place.  In  the  UK,  in 
forced ventilated housing systems, one operator is expected to attend  to 24 000 birds in a 40-
hour working week. In Germany, the labour demand is reported as 0.25 h/ap/yr. 

Driving force for implementation 
The version with deep litter with natural ventilation allows a better indoor climate, lower energy 
demand,  and  lower  investment  and  operating  costs  than  the  closed  version  with  forced 
ventilation.  A  housing  technique  without  an  outdoor  run  minimises  leaching  of  nitrogen  and 
phosphorus [ 115, Netherlands 2010 ].  

Example plants 
The technique is widely applied (e.g. in Poland and the UK) [ 264, Loyon et al. 2010 ]. It is the 
most widespread system used in Germany for the production of ducks. 

Reference literature 
[  104,  UK  2010  ]  [  106,  UK  2010 ] [  115,  Netherlands  2010  ]  [  116,  Germany  2010 ]  [  117, 
Germany 2010 ] [ 152, Link CR 2006 ] [ 264, Loyon et al. 2010 ] [ 474, VDI 2011 ] [ 500, IRPP 
TWG 2011 ] [ 508, TFRN 2014 ] [ 646, COM 2013 ] 

4.6.7.2 

Frequent litter addition (in case of deep litter combined with slatted 
floor) 

Description 
Ducks are reared on solid floors where litter is maintained dry by frequent addition (e.g. daily) 
of  fresh  material  upon  necessity.  At  14  days  old,  young  ducks  have  access  to  a  slatted  area 
where  drinkers  are  placed,  which  cover  around  25 %  of  the  surface.  Manure  is  completely 
removed at the end of the 'all-in, all-out' cycle. 

The  building  is  heated  for  the  first  2  weeks  of  rearing.  The  ventilation  system  can  be  either 
natural or forced with side inlet and ridge extraction. The system can be combined with a free 
range with a hard-surfaced area, with dirty water collection. 

Achieved environmental benefits 
Keeping  the  litter  dry  by  adding  new  bedding  material  daily  reduces  NH3  emissions.  The 
incorporation  of  slatted  areas  in  the  housing  system,  for  accommodating  the  drinkers  for  the 
birds,  allows  the  minimisation  of  moisture  levels  in  the  litter,  whilst  meeting  all  welfare 
regulations concerning drinker provision for the ducks [ 152, Link CR 2006 ]. 

Cross-media effects 
More  water  is  necessary  for  cleaning  the  houses  at  the  end  of  the  cycle,  compared  to  fully 
slatted floor housing systems. 

Environmental performance and operational data 
All the environmental conditions are adjusted automatically or manually, depending on the age 
of the birds. In the UK, in 1 year, six to seven batches of birds are reared. 

As  reported  from  the  UK,  an  example  farm  of  120 000  birds  would  require  annually 
2 160 tonnes  of  bedding  material,  around  152 000 kWh  of  electrical  power,  75  tonnes  of  fuel 
and more than 10 000 m3 of water. Emissions are estimated at 0.11 kg of ammonia and 0.078 kg 
of methane per bird place per year. 

362 

Intensive Rearing of Poultry or Pigs 

Technical considerations relevant to applicability 
For existing plants, applicability depends on the design of the existing structure. 

Economics 
The  reported  annual  operating  costs  for  a  farm  (without  a  free  range)  rearing  annually 
120 000 birds in six batches of 45 days (from 0.05 kg to 3.6 kg) are around EUR 700 000 for the 
production of 1 728 tonnes of meat. 

Chapter 4 

Driving force for implementation 
Improved animal welfare and lower costs [ 624, IRPP TWG 2013 ]. 

Example plants 
The technique is used in farms in the UK and in the Czech Republic [ 264, Loyon et al. 2010 ]. 

Reference literature 
[ 105, UK 2010 ] [ 107, UK 2010 ] [ 152, Link CR 2006 ] [ 264, Loyon et al. 2010 ] [ 624, IRPP 
TWG 2013 ] 

4.6.7.3 

Frequent manure removal (in case of fully slatted floor) 

Description 
Slats cover the pit from where the slurry is collected and transferred to an external store with 
variable frequency. More frequent manure removal than at the end of the cycle is carried out by: 

 
 

permanent gravity flow to an external store; 
scraping with variable frequencies to an external store. 

The  housing  system  can  be  equipped  with  natural  or  forced  ventilation  and  combined  with  a 
free-range system. 

Achieved environmental benefits 
The highest ammonia and odour emissions develop from deep stores and a long residence time 
of the slurry in the pit. The gravity flow with a sloped board or the removal by a scraper reduce 
the time the slurry is exposed to air due to the removal being more frequent than only at the end 
of  the  cycle.  The  emission  reduction  effect  is  greater  in  winter  than  in  summer,  but  odour 
emissions are prevented in the warm season. 

Cross-media effects 
More  water  for  cleaning  is  needed  compared  to  litter-based  housing.  This  technique  was 
evaluated for  its  carbon footprint over the  whole system in a comparative study against litter-
based systems. It was shown that, despite higher greenhouse gas emissions due to the manure 
management, the fully slatted floor housing performs the same or better than systems based on 
straw-bedded housing, especially where straw is supplied from further away [ 475, Merlet et al. 
2010 ].  

For  this  floor  type,  it  is  likely  to  prove  difficult  to  meet  the  requirements  of  including  a 
sufficient  area  covered  with  an  appropriate  bedding  material  to  enable  all  birds  to  rest 
simultaneously  and  of  providing  adequate  litter,  as  far  as  possible,  in  a  dry,  friable  state, 
according  to  the  provisions  of  Article  10  (6)  and  Article  11(4)  of  the  'Recommendation 
concerning  Muscovy  ducks  (cairina  moschata)  and  hybrids  of  Muscovy  and  domestic  ducks 
(anas platyrhynchos)' of the Council of Europe. In some countries (e.g. Sweden), fully slatted 
floors are not allowed due to animal welfare considerations. 

Environmental performance and operational data 
Manure  removal  by  scraping  is  very  common  with  this  housing  system.  Scrapers  are  very 
reliable; the frequency of scraping must be adapted according to the age of animals, the season 

Intensive Rearing of Poultry or Pigs 

363 

Chapter 4 

(temperatures  and  ambient  humidity)  and  the  state  and  volume  of  droppings.  Overly  dry 
droppings and excessively low volumes degrade the state of the scrapers and ground, whereas 
excessively high volumes might harm the functioning of the scrapers.  

Technical considerations relevant to applicability 
The applicability is limited to the rearing of Barbary/Muscovy ducks (cairina moschata), due to 
sanitary reasons. 

Economics 
The  indicative  cost  for  the  purchase  of  a  scraper  (electrical  connections  and  labour  demand 
included)  is  around  EUR 8.3/m2,  excluding  taxes.  In  the  UK,  the  cost  for  the  purchase  of  a 
scraper  is  around  EUR 35–40  per  bird  place  for  a  housing  system  equipped  with  natural 
ventilation, and EUR 40–45 per bird place with forced ventilation. 

Driving force for implementation 
In  France,  the  majority  of  farms  for  the  production  of  ducks  use  fully  slatted  floors  with 
scrapers.  The  system  is  considered  the  best  way  to  rear  Barbary  ducks  as  the  highly  diluted 
manure is considered to cause excessive degradation of the litter, especially in winter, meaning 
that eventually birds are subjected to sanitary problems [ 365, France 2010 ]. Local shortages of 
straw,  due  to  competition  from  other  livestock  (frequent  for  the  major  French  basin  of 
production, the Loire Region and Brittany), make this technique a favourable alternative to deep 
litter housing.  

Example plants 
This system is the reference in France for the rearing of Barbary ducks (cairina moschata). It is 
also used in Poland and Belgium (Wallonia) [ 264, Loyon et al. 2010 ].  

Reference literature  
[ 264, Loyon et al. 2010 ] [ 365, France 2010 ] [ 368, France 2010 ] [ 475, Merlet et al. 2010 ] 

364 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

4.7 

Techniques for the reduction of emissions from pig 
houses 

This section reflects the information submitted on techniques that aim to reduce emissions from 
pig housing facilities. The information available mainly focuses on NH3 emissions to air whilst 
dust, odour and greenhouse gas emissions are also taken into consideration.  

To  enable  easy  comparison,  techniques  are  described  per  pig  category  (mating  and  gestating 
sows, farrowing sows, weaners, fattening pigs). However, due to the fact that in some housing 
techniques  the  basic  characteristics  and  operating  principles  are  common  for  the  various 
categories of pigs and in order to avoid repetition, Section  4.7.1 provides general information 
for the techniques that are similarly applied across several pig categories. 

For  comparing  the  performance  and  the  cost  data  of  reduction  techniques,  it  is  considered 
practical  to  select  a  reference  technique  for  each  pig  category.  This  approach  selects  the 
technique associated with the highest ammonia emission levels and allows other techniques to 
be assessed for their relative environmental performance (reduction percentage); relative values 
give an indication of the achievable level.  

The first technique that is described for each pig category is the fully slatted floor with a deep 
pit, which is generally considered the worst performing system in terms of ammonia emissions, 
and is commonly taken as the reference to calculate the emissions reduction achieved by other 
techniques  [ 508,  TFRN  2014  ].  In  a  similar  way,  economic  data  for  the  implementation  of 
ammonia mitigation techniques are often given as ‘extra costs’ that would be required compared 
to fully slatted floors with a deep pit.  

As regards costs, it has to be indicated that the renovations of existing houses and the associated 
investment  costs  are  highly  dependent  on  the  size  of  the  pens,  the  existing  manure  pit,  the 
discharge points, the existence of a manure pit near load-bearing walls, etc. [ 273, BE Flanders 
2010 ]. 

Note that not all submitted emission data are measured. Some have been calculated or derived 
from  available  information  by  expert  judgment,  in  which  case  this  has  been  indicated.  The 
relationship  between  housing  systems  and  animal  welfare  is  also  considered,  since  some 
techniques may entail potential disadvantages. 

In  pig  housing,  although  techniques  may  be  managed  separately,  they  produce  an  integrated 
environmental  impact  in  the  house  system.  It  is  also  important  to  note  that  all  integrated 
measures to reduce emissions of NH3 from pig housing will lead to a higher amount of nitrogen 
in  the  manure  and  to  the  amount  that  may  potentially  be  emitted  to  air  as  ammonia  during 
storage and landspreading. 

Techniques for reducing emissions from pig housing can be separated into the following general 
categories:  

1.

Nutritional measures to reduce the amount of manure and its nitrogen content.

Nutritional  measures,  as  described  in  Section  4.3,  for  preventing  emissions  from  housing  by 
reducing the concentration of nitrogen in manure and slurry, produce a reduction of emissions at 
all stages of the production chain.  

2.

Control of the indoor housing climate.

Emissions  of  pollutant  gases  increase  at  higher  ambient  temperatures  and  ventilation  rates. 
However, it is important to notice that temperature and ventilation rate are interlinked as a high 
airflow  lowers  the  air  temperature.  Designing  the  ventilation  system  properly  and  controlling 
the  indoor  ventilation  rate,  as  well  as  the  airflow  patterns,  in  order  to  lower  the  indoor 

Intensive Rearing of Poultry or Pigs 

365 

Chapter 4 

temperatures and to reduce the airflow velocity  over the slurry surface and above the housing 
floor,  can  moderate  emissions  from  housing.  Nevertheless,  the  minimum  ventilation  rate  and 
temperature required for animal welfare and health reasons must be ensured, e.g. if too low  a 
ventilation  rate  is  applied,  the  indoor  environment  may  become  highly  concentrated  in 
ammonia, even though the overall emissions will be reduced. 

The  flow  pattern  of  the  air  in  the  housing  can  be  favourably  influenced  by  the  position  and 
dimension of the supply and exhaust air apertures (e.g. side wall or gable extraction, or linear 
extraction  through  exhaust  air  ducting).  If  air  inlets  and  outlets  are  located  near  the  manure 
surface, emissions are increased due to the higher air exchange rate at the interface. Incoming 
air conduction through perforated ducts and porous ceilings results in low air velocities in the 
livestock  area.  Air  inlet  temperatures  and  volume  flows  can  be  reduced  by,  for  example, 
locating the fresh air intake in shady zones, or ducting the air via the feeding passage or through 
a heat exchanger. In Germany, a reduction potential of 10 % for NH3 emissions is reported with 
fresh  air  cooling  achieved with a  geothermal  heat  exchanger  when the  outdoor temperature  is 
more than 25 °C [ 474, VDI 2011 ]. 

Moreover,  the  indoor  climatic  conditions  may  alter  the  pig  behaviour  with  indirect  effects  on 
emissions.  The  control  of  ambient  parameters,  especially  under  hot  conditions,  has  to  ensure 
that  the  pigs  foul  the  excretory  area  while  the lying  and  exercise  areas remain  clean  and  dry. 
Keeping  indoor  temperatures  low  enough  to  avoid  defecation  in  the  solid  part  may  prove 
difficult during the warmer seasons [ 261, France 2010 ]. 

These  factors  must  be  controlled  to  meet  the  pigs’  needs  and  often  require  a  certain  energy 
input. The evaluation and quantification of emission reductions through the application of these 
techniques is complex.  

3.

Optimisation of pig housing design (floor type, pen design and manure management).

In  pig  production,  housing  systems  are  based  on  slatted  or  bedded  floors.  Within  both  floor 
types,  a  large  range  of  techniques  have  been  developed  in  order  to  reduce  the  environmental 
impact of pig production. Pig houses are carefully designed, paying attention to the combination 
of the floor system, arrangement of the functional areas in the pen, manure collection and the 
manure removal system, but also considering the variables influencing the indoor environment. 
The housing systems described involve some or all of the following principles: 

















reducing emitting manure surfaces;

increasing the frequency of slurry (or solid manure) removal from the pit or channel (or
solid floor) to an external store;

cooling the slurry;

changing the chemical/physical properties of the manure, such as decreasing the pH;

using surfaces which are smooth and easy to clean;

controlling  the  characteristics  of  the  indoor  air:  flow  volumes,  speed,  temperature  and
inlet/outlet surfaces;

steering excretory behaviour to minimise the fouled areas;

absorbing  excretions  into  bedding  material  and  properly  managing  the  litter  (keeping  it
dry and clean).

A few general remarks are made below: 

Slatted floor systems 
i. Good  drainage  of  manure  through  the slatted floor limits  fouled  areas  which are  significant
sources of NH3. In general, material characteristics (e.g. concrete roughness and porosity), slat 

366 

Intensive Rearing of Poultry or Pigs 

Chapter 4 

profile  design  (i.e.  a  trapezoidal  cross  section  favours  manure  drainage,  transverse  slats  are 
considered  to  perform  better,  round  or  semi-circular  openings  have  a  greater  risk  of  clogging 
than  traditional  rectangular  openings)  and  the  width  of  openings  (i.e.  increasing  the  size  of 
openings facilitates drainage) influence the drainage properties of the floor. In the same way, the 
application of a smoother material (cast iron- or plastic-coated instead of concrete) to slats with 
the  same  width,  allowing  manure  to  fall  faster  into  the  pit  below  without  sticking,  reduces 
ammonia emissions. Concrete slatted floors perform better with respect to the risk of slipping in 
comparison to slatted floors of plastic or metal but they are colder for the pigs to lie on and have 
less  ability  to  absorb  shocks  [  486,  Pelletier  et  al.  2005  ]  [  487,  Aarnink  et  al.  1997  ]  
[ 488, Pedersen et al. 2008 ] [ 590, Batfarm 2013 ]. 

ii.  Reducing  the  surface  area  of  the  slatted  floor  reduces  the  emitting  slurry  surface  and, 
consequently, reduces NH3 emissions. Thus, partly slatted floor systems with  a reduced slurry 
pit area are known to produce lower levels of NH3 compared to fully slatted floor systems, as 
confirmed by numerous studies [ 590, Batfarm 2013 ]. Partly slatted floors covering 50 % of the 
floor area generally emit 15–20 % less NH3, particularly if the slats are metal- or plastic-coated 
which is less sticky for manure than concrete and the risk of emissions from the solid part of the 
floor  is  avoided.  Further  reduction  of  the  emitting  area  can  be  achieved  by  making  both  the 
partly  slatted  area  and  the  pit  underneath  smaller.  With  the  smaller  slatted  area,  the  risk  of 
greater fouling of the solid area can be mitigated by installing a small second slatted area with a 
water  canal  underneath  at  the  other  side  of  the  pen  where  the  pigs  tend  to  eat  and  drink  
[ 508, TFRN 2014 ]. 

In such systems, the pen is divided into solid lying areas and slatted dunging areas. However, 
pigs  do  not  always  use  these  areas  in  the  desired  way,  using  the  solid  area  to  dung  and  the 
slatted area to cool off in warm weather. Generally, pens should be designed to accommodate 
the  desired  excretory  behaviour  of  pigs  to  minimise  the  fouling  of  solid  floors.  This  is  more 
difficult in regions with a warm climate [ 508, TFRN 2014 ].  

It  is  important  to  choose  the  optimum  ratio  between  slatted  and  non-slatted  surface  areas. 
Increasing  the  non-slatted  area  will  result  in  more  manure  remaining  on  the  solid  part  and 
possibly  a  rise  in  ammonia  emissions.  Whether  this  happens  or  not  depends  largely  on  the 
amount of urine and the speed with which it can run off, as well as with the distance to the pit. 
A convex inclined smooth floor will enhance urine removal, but animal safety needs to be taken 
into account.  

On  the  other  hand,  some  studies  report  similar  emissions  whatever  the  proportion  of  slatted 
floor  or  higher  emissions  with  the  partly  slatted  floor.  Actually,  there  are  cases  when  the 
excretory behaviour of the pigs, which tend to foul the solid area under specific conditions such 
as  hot  temperatures  or  a  high  animal  density,  does  not  allow  a  reduction  in  emissions  with  a 
partly slatted floor compared to fully slatted floor systems [ 590, Batfarm 2013 ]. For example 
in  France,  NH3  emissions  may  increase  by  around  30 %,  in  comparison  to  fully  slatted  floor 
systems, when fattening pigs tend to excrete on the solid floor at around 24 °C. If lower indoor 
temperature conditions (i.e. 18 °C) are applied with partly slatted floors, compared to a higher 
temperature with fully slatted floors (i.e. 24 °C), emissions of ammonia and greenhouse gases 
are  similar,  but a  deterioration of feed intake,  growth  rate,  carcass  backfat thickness  and  feed 
conversion  ratio  (FCR)  is  observed  for  the  lower  temperature  applied.  In  addition,  animal 
welfare  and  health  may  be  affected  by  increased  dirtiness.  There  may  also  be  additional 
economic 
implications  when  dirty  pigs  are  not  accepted  by  slaughter  companies.  
[ 261, France 2010 ] [ 493, Guingand et al. 2010 ]. Furthermore, pen fouling increases towards 
the end of the fattening period due to lack of space and the increased heat generated by the pigs 
themselves as they grow bigger, which will also increase emissions, due to an increased surface 
area emitting ammonia [ 439, Sommer et al. 2006 ].  

In  practical  terms,  the  implementation  of  partly  slatted  floors  implies  a  greater  surface  area 
needed  per  animal,  leading  to  a  reduction  of  the  farm  capacity  compared  to  the  fully  slatted 
floor. 

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The installation of a sprinkler to cool the animals, or sufficient available space, could prevent an 
increase of emissions. Moreover, the proper design of housing conditions respecting the natural 
excretory/lying behaviour of the pig may contribute to limiting emissions, by preventing fouling 
of  the  solid  areas.  This  includes,  for  example,  the  appropriate  location  of  the  feeding  and 
watering facilities as most of the pigs urinate and defecate in the free corner  of the pen, away 
from the feeder or drinker, indicating where the slats have to be placed. The pen partition type 
also impacts on the dunging behaviour. Closed pen partitions reduce air drafts, keep the sleeping 
area warmer and maintain a temperature gradient between the warmer lying area and the cooler 
dunging area [ 590, Batfarm 2013 ]. 

A  reduction  of  the  emitting  manure  surface  can  also  be  achieved  by  modification  of  the  pit 
design,  principally  as  a  result  of  sloped  pit  walls  or  manure  gutters.  Limited  information  is 
available from scientific literature concerning the effect on ammonia and odour emissions of the 
pit  depth  underneath  fully  slatted  floors.  In  general,  a  shallow  pit  will  have  the  same  surface 
area of slurry as a deeper pit and therefore the same potential with regards to ammonia emission 
[  605,  E.Magowan,  AFBI  2010  ].  On  the  other  hand,  higher  emissions  occur  for  a  deep  pit 
where manure may be stored for the whole year and lower emissions for shallow pits (60 cm) 
and regular removal of manure (every few weeks) [ 500, IRPP TWG 2011 ]. 

An increase of the distance between slats and slurry, or an increase of the ventilation rate, will 
have an effect on the average air speed and the airflow pattern over the exposed slurry surface. 
Reducing the headspace (height) in the manure pit increases the air exchange, with an expected 
increase in ammonia emissions. However, a good correlation between ammonia emissions and 
headspace in the manure pit is not established and the effect of the distance from the slats to the 
surface of the slurry on ammonia emissions may be considered modest, especially if the slurry 
pit  walls  are  vertical  [  439,  Sommer  et  al.  2006  ].  In  underfloor  extraction,  higher  emissions 
occur if the distance between the slurry surface and the bottom edge of the slatted floor is less 
than  50 cm  [  43,  COM  2003  ].  However,  no  such  effect  is  verified  in  the  Netherlands  
[ 500, IRPP TWG 2011 ]. In the case of underfloor air extraction, ammonia emissions  depend 
not only on the distance between the slurry surface and the bottom edge of the slatted floors, but 
also  on  the  design  of  the  underfloor  extraction  system  [  606,  Z.Ye  et  al.  2011  ]  
[ 605, E.Magowan, AFBI 2010 ]. 

iii.  Frequent  manure  removal  is  considered  an  effective  technique  for  reducing  ammonia 
emissions  (e.g.  by  scrapers,  belts,  flushing  or  vacuum).  Total  emissions  including  emissions 
from storage will be reduced provided that the outside temperature is lower than the inside one. 
From  a  practical  point  of  view,  the  frequency  of  manure  removal  is  the  principle  that  can  be 
most easily implemented by existing houses, provided there is enough outdoor storage capacity. 
Nevertheless, systems that produce turbulence in the slurry flow generate peaks of odours each 
time slurry pits are emptied, which is more important for farms close to sensitive receptors than 
for isolated farms [ 261, France 2010]. The physical structure of the manure and the smoothness 
of  the  pit  floor  surface  may  affect  the  reducing  effect  on  the  ammonia  emissions  that  the 
removal through scraping usually provides. 

Bedded systems 
The use  of  litter in  pig  housing  has  been  increased  in  many  Member  States  as it  is  related to 
improved welfare and to the need for a better brand image of livestock production. However, in 
some  countries,  particularly  in  Denmark,  the  number  of  littered  systems  is  reported  to  have 
declined  dramatically,  due  to  cross-media  effects  and  economic  considerations  [  500,  IRPP 
TWG 2011 ]. 

Litter  can  be  applied  in  conjunction  with  (automatically)  controlled  natural  ventilation,  in 
housing systems where the litter would allow the animals to control their own temperature, and 
would  thereby  reduce  the  amount  of  energy  needed  for  ventilation  and  heating.  On  the  other 
hand, this technique is associated with increased costs, principally due to the straw used and the 
labour for litter management, even if building costs are usually reduced. For existing buildings, 
this system can be quite easily applied for housing systems with a solid concrete floor.  

368 

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Comparisons between bedded systems and traditional slatted floor systems show contradictory 
results  regarding  NH3  and  CH4  emissions  while  N2O  emissions  were  systematically  increased 
with the former but with a large variation between studies. These discrepancies can be explained 
by  the  wide  range  of  rearing  techniques  for  pigs  on  litter,  the  litter  substrate,  the  amount  of 
supplied litter, the space allowance and the litter management. These parameters influence the 
physical  structure  (density,  humidity)  and  the  chemical  properties  of  the  litter  that  interact  to 
modulate gas emission levels [ 590, Batfarm 2013 ]. 

The production of solid manure instead of slurry manure is considered an advantage from the 
agronomical point of view, in so far as organic matter incorporated into the fields improves the 
physical  characteristics  of  the  soil,  thereby  reducing  run-off  and  the  leaching  of  nutrients  to 
water bodies. 

4.7.1 

Common housing systems for various categories of pigs 

This  section  presents  the  shared  elements  related  to  the  description,  achieved  environmental 
benefits, cross-media effects and applicability restrictions and driving force for implementation 
for  housing  systems  which  have  common  characteristics  for  various  pig  categories.  Housing 
systems  for  mating  and  gestating  sows  are  listed  in  Section  4.7.2.  Housing  systems  only 
applicable to farrowing sows are listed in Section 4.7.3. Housing systems for weaners are listed 
in Section 4.7.4. Housing systems for fattening pigs are listed in Section 4.7.5. 

4.7.1.1 

Deep pit (in case of a fully slatted floor) 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description  
A deep pit lies under a fully slatted floor with concrete slats. The slurry is removed at variable 
intervals, usually after every rearing period, or even less frequently.  

This  type  of  housing  is  usually  equipped  with  forced  ventilation  (normally  with  negative 
pressure)  or  ACNV.  Ventilation  removes  gaseous  components  emitted  by  the  stored  slurry. 
Exhaust  air  is  normally  expelled  through  roof  or  side  wall  vents.  Underfloor  ventilation  may 
also be applied; it is frequently used in some geographical areas, e.g. France.  

Achieved environmental benefits 
Since the emitting surface, which is a key factor concerning ammonia emissions, is as wide as 
the surface at the animals' disposition, emissions are expected to be the highest with this system, 
hence  it  is  considered  the  reference  for  expressing  the  emission  reduction  brought  about  by 
other techniques. Ammonia emissions can be reduced if the technique is combined with other 
mitigation measures such as pH reduction of the slurry, slurry cooling, etc. 

On the other hand, the system does not generate more ammonia emissions than other housing 
systems if it is well managed in terms of temperature and ventilation [ 269, France 2010 ] [ 270, 
France 2010 ]. 

Cross-media effects 
The  use  of  fully  slatted  floors  makes  it  difficult  to  comply  with  the  provisions  of  Directive 
2008/120/EC, as it may be problematic to provide the pigs with permanent access to a sufficient 
quantity  of  material  to  enable  proper  investigation  and  manipulation  activities,  e.g.  due  to 
problems in slurry handling with bedding material [ 510, EFSA 2007 ]. Fully slatted floors have 
been  identified  as  one  of  the  factors  involved  in  a  compound  risk  for  tail  biting  which  is 
essential  to  be  controlled  when  aiming  to  avoid  tail  docking.  For  instance,  a  high  stocking 
density,  associated  with  a  lack  of  enrichment  and  fully  slatted  floors,  has  been  assessed  as  a 

Intensive Rearing of Poultry or Pigs 

369 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

significant  risk  for  tail  biting  [  495,  EFSA  2007  ].  Routine  tail  docking  is  prohibited  by 
Directive 2008/120/EC. In some countries (e.g. Sweden, Finland and Denmark from July 2015), 
fully slatted floors are not permitted by the animal welfare regulations. 

However,  there  are  a  number  of  pieces  of  equipment  and  methods  to  provide  manipulable 
material  to  the  pigs,  such  as  the  provision  of  straw  and  hay  in  feeders  or  racks,  which  allow 
compliance  with  the  provisions  of  the  Directive  if  sufficient  for  the  pigs  to  engage  in 
investigation and manipulation activity [ 510, EFSA 2007 ] [ 624, IRPP TWG 2013 ]. 

Deep pits are not allowed in Denmark due to the risk of hydrogen sulphide formation inside the 
pig house, nor in Sweden for animal welfare reasons [ 624, IRPP TWG 2013 ]. 

Technical considerations relevant to applicability  
No technical restrictions are reported for the implementation of the technique. 

Driving force for implementation 
The  system  is  simple  to  run.  Pigs  remain  clean  and  good  conditions  prevail  for  animals  and 
workers [ 269, France 2010 ] [ 270, France 2010 ]. 

References  
[ 189, Germany 2010 ] [ 261, France 2010 ] [ 269, France 2010 ] [ 270, France 2010 ] [ 495, 
EFSA 2007 ] [ 510, EFSA 2007 ] [ 624, IRPP TWG 2013 ] 

4.7.1.1.1 

Deep pit (in case of a partly slatted floor) 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
Partly slatted floored pens are equipped with a manure pit of a sufficient depth that allows for 
the storage of the slurry between infrequent removals. 

In France, pits of less than 1 metre deep are emptied one to three times per cycle. In Germany, 
overflow  channels  are  preferred,  with  removal  every  1  to  2  months  (twice  per  cycle)  or  after 
every fattening period. 

In  overflow  discharge  systems  (see  Figure 4.27),  the  slurry  flows  continuously  out  into  a 
receiving  pit  (or  external  slurry  store).  At  the  discharge  end  of  the  channel  below  the  slatted 
floor, a barrier (e.g. 15 cm high lip) is built to retain a layer of slurry in the channel that prevents 
the build-up of solids that may block the channel. The slurry forms a 1.5–3 % slope towards the 
discharge, maintaining a freeboard of at least 25–30 cm below the slats [ 498, Cernåk 1977 ]. 

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Chapter 4 

1.  Slatted floor 
2.  1.5–3 % slope on slurry surface 
3.  Reception pit 
4.  Lubricating layer of slurry retained by the lip 
Source: Elaboration from [ 498, Cernåk 1977 ] 

Figure 4.27:  Principle of operation of the overflow slurry channel 

Achieved environmental benefits 
This housing system presents environmental performances comparable to those  observed with 
fully slatted floors with a deep pit. See the general introduction of Section 4.7 on the potential 
benefits of partly slatted floors.  

Cross-media effects 
A  partly  slatted  floor  system  may  entail  increased  requirements  in  terms  of  temperature  and 
general management, as solid floors can become soiled, particularly at high temperatures. Dirty 
floors  also  have  implications  for  pig  hygiene  and  health,  for  odour  emission  and  for  working 
conditions, causing discomfort. See also the general introduction in Section 4.7. Extra costs are 
also associated with the extra time needed for cleaning the pens. Water consumption increases 
with reduced slatted floor areas, due to the cleaning needs of the solid floor [ 500, IRPP TWG 
2011 ]. 

Technical considerations relevant to applicability  
No technical restrictions are reported for the implementation of the technique; however, it is not 
commonly used. 

Economics  
Investment  costs  are  reported  in  Germany  to  be  the  same  as  for  fully  slatted  floors  [192, 
Germany, 2010 ]. 

Driving force for implementation 
Improved animal welfare is the driving force. See also the general information in Section 4.7. 

Reference literature 
[ 192, Germany 2010 ] [ 271, France 2010 ] [ 272, France 2010 ] [ 498, Cernåk 1977 ] [ 500, 
IRPP TWG 2011 ] 

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4.7.1.2 

Vacuum system for frequent slurry removal (in case of a fully 
slatted floor) 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
On the bottom of the pit under a fully slatted floor, outlets are placed that are connected to a 
discharge  system  moving  the  slurry  to  the  external  storage  unit  (see  Figure 4.28).  Slurry  is 
discharged by opening a valve in the main slurry pipe. A slight vacuum develops and allows for 
a thorough slurry removal, better than by  gravity alone. A certain  depth of slurry needs to be 
obtained  before  the  system  can  operate  properly  to  allow  the  vacuum  to  develop  and  empty 
more slurry. The pit can be emptied once or twice a week; the evacuation frequency depends on 
the capacity of the pit or channel and on the weight of the pigs in the pens above, i.e. the same 
pit is filled up faster by 100 kg pigs than 20 kg pigs. The frequency of emptying will determine 
the volume of the external slurry storage required [ 261, France 2010 ] [ 175, Ecodyn 2010 ]. 

Source: [ 292, Italy 2001 ] 

Figure 4.28:  Vacuum system in case of a fully slatted floor 

The exact area covered by each pipe outlet depends on the dimension of the pen. In general, for 
every 10–11 metres in length, one pipe outlet is placed to discharge the slurry contained over 
the  corresponding  surface.  An  excessive  number  of  outlets  might  increase  the  leakage 
possibility.  The  pen  area  served  by  each  outlet  is  not  considered  to  affect  the  emptying 
capability, as the optimum height of slurry required for the system to work is considered to be 
the  same  regardless  of  the  area  covered.  As  a  larger  pen  area  will  accommodate  a 
proportionately  larger  number  of  pigs,  the  optimum  height  will  not  take  longer  to  reach.  An 
optimal  slurry  depth  is  approximately  800 mm,  regardless  of  the  number  of  days  it  takes  to 
reach it. It should be noted that slurry can be removed at a shallower depth, the minimum being 
500 mm; however, this does not allow a sufficient vacuum to develop and results in more slurry 
being left in the system.  

High-powered  submersible  pumps  are  also  used  for  infrequent  intensive  cleaning  (every  2 
years) with high-pressure water to remove crusting from around the tank edges. New houses can 
be 
for  an  easier  and  complete  emptying  
[ 175, Ecodyn 2010 ]. 

fitted  with  pits  with  sloped  bottom 

Achieved environmental benefits 
The  frequent  removal  of  slurry  reduces  ammonia  emissions  and  is  likely  to  reduce  methane 
emissions.  

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Cross-media effects 
As  the  system  is  manually  operated,  no  additional  energy  is  required  nor  is  the  additional 
working time significant. Less water is needed to clean the floor compared with partly slatted or 
solid concrete floors. It is suggested that any aerosols which develop during the discharge of the 
slurry  are  removed  by  the  vacuum  created  when  opening  the  valves.  Because  of  the  reduced 
storage period of the slurry inside the buildings, an additional capacity/volume of the external 
slurry store may be needed. 
This technique can generate odour peaks at the time of emptying the slurry pits. It is proposed 
that  emptying  should  not  be  more  frequent 
times  per  month.  
[ 261, France 2010 ] 

than  one  or 

two 

In Finland and Sweden, housing systems with fully slatted floors are not allowed due to animal 
welfare regulations. See also 'Cross-media effects' in Section 4.7.1.1 for fully slatted floors. 

Environmental performance and operational data 
For the effectiveness of the removal, it is important that it takes place when the slurry is fresh. 
In order to evaluate the residence time of the slurry before being removed, the index of the ratio 
of  volatile  solids  to  total  solids  could  be  used.  A  value  of  about  75–80 %  of  the  above  ratio 
seems to be an index of acceptable fresh slurry [ 624, IRPP TWG 2013 ]. 

Frequent removal of slurry from the pit or channel reduces the pool of methanogenic bacteria 
within  this  environment  [  443,  Chadwick  et  al.  2011  ].  A  reduction  of  methane  emissions 
equivalent to 65 % has been measured in Spain for fattening pigs [ 187, Spain 2010 ]. Reported 
ventilation rates used with this housing system are presented in Table 4.76. 

Table 4.76:  Reported ventilation rates applied in vacuum systems for frequent slurry removal (in 

case of a fully slatted floor) 

Animal category 

Cold season 

Warm season 

Reference 

Fattening pigs 
Weaners 
Mating/gestating sows (group) 
Mating/gestating sows (individual) 

m3/ap/h 
15.7 (1–64) 
3.5 to 7 
14 to 18 
16 

m3/ap/h 
66.6 (15–120) 
20 to 50 
86 to 128 
220 

[ 187, Spain 2010 ] 
[ 182, Germany 2010 ] 
[156, Germany 2010 ] 
[163, Germany 2010 ] 

Average reported consumption data for energy, water and labour are shown in Table 4.77. 

Table 4.77:  Consumption  related  to  the  management  of  FSF  systems  equipped  with  vacuum 

slurry removal 

Animal category 

Cleaning 
water 
l/ap/yr 

Weaners  

150 

210 

Mating/gestating 
sows (group) 
Mating/gestating 
sows (individual) 
Fattening pigs  
(1) 0.55 h/year per productive sow. 
NB: NI = no information provided. 

340 

127 

Electricity 

Fuel 

Labour 

Source 

kWh/ap/yr 
12 
9 (ventilation) 
2 (lighting) 

60 

60 

NI 

kWh/ap/yr 

h/ap/yr 

170 

160 

160 

NI 

0.99 

[ 182, Germany 2010 ] 

0.7 (1) 

[156, Germany 2010 ] 

2.6 

0.6 

[163, Germany 2010 ] 

[ 267, UK 2010 ] 

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Chapter 4 

Technical considerations relevant to applicability 
In existing houses, this technique is difficult to apply as the number of outlets per room cannot 
be modified [ 261, France 2010 ]. It may be applicable with: 

 

 

solid concrete floors with a sufficient height to build on top of the existing floor; 

renovation of an FSF with a storage pit underneath. 

The technique may not be generally applicable to existing plants due to the costly modifications 
required for retrofitting the existing housing system. 

Economics 
The  frequent  removal  of  slurry  by  vacuum  has  practically  no  extra  cost  if  it  is  carried  out 
manually [ 187, Spain 2010 ] [ 508, TFRN 2014 ]. 

Extra costs may also be associated with the need for additional external slurry storage capacity 
[ 261, France 2010 ] [ 648, DEFRA 2011 ].  

Driving force for implementation 
Slurry removal by vacuum is simple and economical to implement and run. 

Reference literature 
[  156,  Germany  2010  ]  [  162,  Germany  2010  ]  [ 163,  Germany  2010  ] [  175,  Ecodyn  2010 ] 
[ 180, Spain 2010 ] [ 182, Germany 2010 ] [ 187, Spain 2010 ] [ 261, France 2010 ] [ 267, UK 
2010 ] [ 292, Italy 2001 ] [ 443, Chadwick et al. 2011 ] [ 508, TFRN 2014 ] [ 624, IRPP TWG 
2013 ] [ 648, DEFRA 2011 ] 

4.7.1.3 

Vacuum system for frequent slurry removal (in case of a partly 
slatted floor) 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
The way slurry is collected below the slatted floor and removed is the same as the one described 
in Section 4.7.1.2, with the only difference being that the dimensions of the manure channels are 
reduced in the same proportion as the slatted floor area is reduced in favour of solid floor (see 
Figure 4.29). 

Source: [ 292, Italy 2001 ] 

Figure 4.29:  Vacuum system in case of a partly slatted floor 

374 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
The principles that lead to emission reductions, in comparison with a fully slatted floor system 
with  a  deep  pit,  are  the  reduction  of  the  emitting  surface  by  reducing  the  manure  surface 
exposed and the frequent removal of slurry. 
Cross-media effects 
Due  to  the  fact  that  pigs  reared  on  a  partly  slatted  floor,  particularly  finishing  pigs,  tend  to 
excrete on the solid floor when a critical temperature is reached, the cleanliness of the area may 
thus  deteriorate  and  ammonia  emissions  may  increase  compared  with  fully  slatted  floors.  For 
this  reason,  a  more  pronounced  reduction  of  the  temperature  in  the  room  is  often  required, 
especially in warm periods. Dirty floors also have implications for pig hygiene and health, for 
odour emissions, as well as for working conditions. Because of the shorter storage period of the 
slurry inside the buildings, an additional capacity of outside storage should be considered. 

This technique can generate odour peaks at the time of emptying the slurry pits. From France, it 
is  proposed  that  the  rate  of  emptying  should  not  be  more  frequent  than  one  or  two  times  per 
month [ 261, France 2010 ]. 

A slight increase of water consumption is associated with a reduction of the slatted floor area, 
due  to  the  greater  cleaning  needs  of  the  solid  floor  [  500,  IRPP  TWG  2011  ]  [  261,  France 
2010 ]. 

Technical considerations relevant to applicability 
The technique may not be generally applicable to existing plants due to the costly modifications 
required  for  retrofitting  the  existing  housing  system.  Since  the  number  of  outlets  per  room 
cannot be modified, it is difficult to implement this technique in existing buildings, at least for 
weaned piglet and fattening pig housing systems. For sows, plates could be placed on the floor 
to  create  a  partly  slatted  floor,  but  the  total  surface  of  the  pit  will  remain  unchanged  [ 261, 
France  2010  ]  [  500,  IRPP  TWG  2011  ].  Moreover,  in  existing  housing  applications,  the 
technique is applicable only in the case of substitution of a partly slatted floor combined with a 
storage pit of a sufficient depth. 

Economics  
The  frequent  removal  of  slurry  by  vacuum  has  practically  no  extra  cost  if  it  is  carried  out 
manually [ 187, Spain 2010 ] [ 508, TFRN 2014 ]. Extra costs may also be associated with the 
need for additional external slurry storage capacity [ 261, France 2010 ] [ 648, DEFRA 2011 ].  

Driving force for implementation 
The vacuum system is considered easy to operate  [ 291, IRPP TWG 2002 ]. The provision of 
areas  with  a  solid  floor  makes  pens  more  comfortable for  animals,  hence  animal  welfare  is 
improved. 

Example plants 
The system is widely applied. 

Reference literature 
[ 163, Germany 2010 ] [ 187, Spain 2010 ] [ 261, France 2010 ] [ 276, Finland 2010 ] [ 291, 
IRPP  TWG  2002  ]  [  292,  Italy  2001  ]  [  500,  IRPP  TWG  2011  ]  [  508,  TFRN  2014  ]  [  648, 
DEFRA 2011 ] 

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4.7.1.4 

Slanted walls in the manure channel (in case of a fully or partly 
slatted floor) 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
The sides of the manure channels beneath the slatted floors slope towards the bottom in order to 
reduce the surface area of manure from where ammonia is emitted. Instead of being square, the 
channel section is V-shaped and the discharge point is placed at the bottom. 

The slanted walls are built with a manure-resistant material and are smooth-surfaced. The slope 
of the slanted walls is at least 45 ° against the floor and at least 60 ° in the middle that forms the 
V-shape. 

Achieved environmental benefits 
One or two slanted pit walls applied in the manure channel result in a decreased emitting surface 
when  the  height  of  slurry  is  lowered,  due  to  frequent  emptying  of  the  channel.  As  a 
consequence,  ammonia  emissions  are  reduced;  in  combination  with  partly  slatted  floors  and 
frequent manure removal, the technique can reduce emissions by up to 65 % [ 508, TFRN 2014 ]. 

Cross-media effects 
When the surface of the slanted walls is not smooth, with no slurry sticking effect, and if slanted 
walls do not have the right sloping angle, manure retention may occur, leading to an increase of 
emissions. A partly slatted floor may entail increased requirements in terms of temperature and 
general management, as solid floors can  become  soiled, particularly at high temperatures (see 
the  general remarks in Section  4.7). See also 'Cross-media effects' in Section  4.7.1.1 for fully 
slatted floors. 

Technical considerations relevant to applicability 
The technique may not be generally applicable to existing plants due to the costly modifications 
required for retrofitting the existing housing system. 

Driving force for implementation 
No information provided. 

Reference literature 
[  165,  Netherlands  2010  ]  [  166,  Netherlands  2010  ]  [  265,  BE  Flanders  2010  ]  [  188,  Spain 
2010 ] [ 179, Spain 2010 ] [ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] 

4.7.1.5 

Scraper for frequent manure removal (in case of a partly or fully 
slatted floor) 

This technique is used for mating/gestating sows, farrowing sows, weaners and fattening pigs in 
combination with fully or partly slatted floors.  

Description 
The  pen  or  the  farrowing  crate  contains  a  slatted  part  (defecating  area)  and,  in  the  case  of  a 
partly  slatted  floor,  a  solid  concrete  part  (lying  area)  with  a  slope  towards  the  slats.  Slurry  is 
collected in a concrete pit or channel underneath the slats, from which the manure, consisting of 
faeces,  urine,  waste  bedding  and  feed,  is  removed  frequently  (e.g.  daily)  by  a  scraper  to  the 
manure pit outside. Urine can drain directly to a collection pit through a drain in the bottom of 
the  manure  channel  (see  Figure 4.51).  The  scraper  is  driven  by  a  stationary  mechanical  or 
hydraulic power unit. It may comprise chains or cables fitted with metal flaps, blades or flights.  

376 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
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The standard flat scraper system consists of a shallow slurry pit with a horizontal steel scraper 
under  the  slatted  floor,  allowing  the  manure  to  be  removed  from  the  building  several  times  a 
day. However, this type of manure removal seems to have no positive effect on NH3 emissions 
as the surface under the slat is always soiled because the scraping spreads faeces and urine over 
the pit and the small film left creates a greater emitting area. In contrast, the V-shaped scraper 
system, which is described above, is effective in reducing emissions since it is associated with 
separation of urine from faeces. This system involves a channel with two inclined surfaces on 
each side  of  a  central  gutter.  A longitudinal slope  of  around  1 %  allows  the  liquid fraction to 
continuously run off by gravity towards the gutter, before being removed outside the building. 
The solid fraction remains on the inclined surface before being scraped off several times a day  
[ 590, Batfarm 2013 ]. 

Achieved environmental benefits 
A reduced slurry surface and the frequent removal of slurry to an external store combined with 
the  separation  of  urine  from  faeces  reduce  NH3  emissions.  The  slat  material,  frequency  of 
removal and smoothness of the pit floor all contribute to the reduction that can be achieved. By 
the installation of a V-shaped scraper under the slats, a general reduction of around 40 % can be 
achieved for NH3 [ 590, Batfarm 2013 ]. 

Cross-media effects 
The  functioning  of  the  system  is  vulnerable  due  to  the  wear  of  the  floor.  The  addition  of  a 
coating on the scraped floor is recommended in order to achieve a smooth surface. In general 
this  system  works  well,  but  operability  is  difficult  because crystals,  which  hinder  the  scraper, 
can be formed on the pit floor [ 291, IRPP TWG 2002 ]. Nowadays, the system is considered 
reliable [ 641, IRPP IWG 2014 ]. 

Operating  the  scraper  requires  energy.  The  power  consumption  of  scraping  varies  with  the 
frequency.  Frequent  maintenance  is  required  for  this  type  of  equipment,  with  a  consequent 
increase in the demand for labour resources. For partly slatted floors, heat stress and defecation 
on the solid part have to be avoided. See also 'Cross-media effects' in Section 4.7.1.1 for fully 
slatted floors. 

Technical considerations relevant to applicability 
Scrapers  can  be  applied  in  new  houses.  In  existing  houses,  the  applicability  depends  on  the 
design of the existing manure pit and the building construction, e.g. walls and foundations. In 
this  context,  sanitary  aspects  also  have  to  be  taken  into  consideration  as  the  scraper  can  go 
through several rooms with several animal categories [ 624, IRPP TWG 2013 ]. 

Driving force for implementation 
The  direct  separation  of  urine  and  the  solid  part  of  the  manure  is  an  advantage  for  this 
technique. The scraper technique in Germany is used when slurry has a high dry matter content, 
or when the construction of a shallow manure pit is necessary because of  the high hydrostatic 
level of groundwater [ 192, Germany 2010 ].  

Example plants 
This system is applied in Italy and Denmark. In the Netherlands, it is no longer allowed in new 
buildings. Scrapers in France are only associated with fully slatted floors, where the technique is 
implemented in some new buildings [ 261, France 2010 ]. 

Reference literature 
[ 42, Netherlands 1999 ] [ 192, Germany 2010 ] [ 261, France 2010 ] [ 391, Italy 1999 ] [ 412, 
Italy 2001 ] [ 590, Batfarm 2013 ] [ 624, IRPP TWG 2013 ] [ 641, IRPP IWG 2014 ]  

Intensive Rearing of Poultry or Pigs 

377 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.7.1.6 

Convex floor and separated manure and water channels (in case of 
partly slatted pens) 

This technique applies to weaners and fattening pigs. 

Description 
The emitting area in partly slatted pens is further reduced  by making both the slatted area and 
the pit underneath smaller. The solid concrete floor is designed to slope in two directions so that 
slurry flows into two channels. Because of the smaller slatted area, the risk of greater fouling of 
the  solid  area  is  mitigated  by  installing  a  small  second  slatted  area  with  a  water  channel 
underneath at the other side of the pen where the pigs tend to eat and drink. The channel is filled 
with water to dilute any manure that might  potentially drop into it.  At least after each rearing 
cycle, the channels are completely washed out and the pens are cleaned. 

The  solid  floor  that  separates  the  channels  can  be  inclined  or  convex.  The  reported  width  is 
1.3 m.  The  water  channel  is  placed  under  the  feeding  system  (the  minimum  water  depth  is 
10 cm  for  fattening  pigs  and  5 cm  for  weaners).  As  the  pigs  do  not  normally  defecate  in  this 
area,  the  water  channel  collects  spilled  water  and  spoiled  feed.  This  slatted  area  has  low 
emissions  because  any  manure  dropped  there  will  be  diluted.  The  water  in  the  channel  also 
prevents  flies  from  breeding  and  can  be  used  to  clean  the  manure  channel  at  the  end  of  the 
cycle. A maximum width of 0.65 m is reported. Water for cleaning the pens may be used to fill 
the water channels. The manure channel can also be built with flushed gutters or with slanted 
walls (see Section 4.7.1.4 and Section 4.7.1.9). 

Achieved environmental benefits 
Reduction of ammonia emissions is achieved by decreasing the emitting surface and reducing 
the  risk  of  fouling  of  the  solid  area  by  the  installation  of  an  inclined  solid  floor  and  a  water 
channel beneath the feeding area. Ammonia emissions can be further reduced by frequent slurry 
removal. 

In general, the combined manure-channel and water-channel system can reduce NH3 emissions 
by 40–50 % in comparison with a fully slatted floor system with a deep pit, depending on the 
size of the water channel [ 508, TFRN 2014 ]. 

Cross-media effects 
Energy consumption varies depending on the slurry removal method, i.e. if slurry is flushed or 
removed by a discharge system. Odour peaks due to flushing may cause a nuisance when there 
are  residential  areas  near  the  farm.  It  has  to  be  decided  on  a  case-by-case  basis  whether  an 
overall  load  (thus  applying  a  no-flushing  system)  or  peak  values  are  more  important  
[ 291, IRPP TWG 2002 ]. For partly slatted floors, heat stress and defecation on the solid part 
have to be avoided. 

Technical considerations relevant to applicability 
In  existing  houses,  the  applicability  depends  on  the  design  of  the  existing  manure  pit; 
retrofitting  the  system  with  two  channels  in  existing  houses  can  be  difficult  and  costly.  The 
entire ground plate of the manure pit may have to be removed in order to construct the discharge 
system  for  emptying  the  slurry  and  water,  and  digging  operations  may  have  to  be  performed 
near the load-bearing walls. 

Driving force for implementation 
The driving force is to achieve a low-cost housing system with a low ammonia emission rate. 
Partly slatted floors are considered to improve animal welfare. Building sloped walls and flush 
gutters is relatively easy in pens with a central convex or a partly slatted floor with an inclined 
concrete floor. Only a few alterations are needed to implement these features.  

378 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Reference literature 
[ 42, Netherlands 1999 ] [ 22, Bodemkundige Dienst 1999 ] [ 176, Netherlands 2010 ] [ 186, BE 
Flanders 2010 ] [ 194, Netherlands 2010 ] [ 195, Netherlands 2010 ] [ 291, IRPP TWG 2002 ] 
[ 508, TFRN 2014 ] 

Chapter 4 

4.7.1.7 

Slurry cooling channels 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
A  cooling  system  is  installed  under  the  manure  pit  or  the  manure  channel  floor  of  a  housing 
system, equipped with vacuum cleaning or with a scraper. Low-density polyethylene pipes for 
the refrigerating liquid are cast in the concrete floor, with a distance of 35–40 cm between each 
pipe loop (see Figure 4.30). Alternatively, cooling pipes can be installed above the concrete, at 
the bottom of  the manure pits, especially for existing buildings. Pipes are connected to a heat 
exchanging device (pump or plate) to recover process energy which might be used for heating 
other parts of the farm (house for weaners, farrowing pens, private farmhouse or greenhouses, 
etc.). In the cooling circuit, glycol or other types of antifreeze can be added in order to allow the 
slurry to be cooled to temperatures even below 0 °C. However, extreme cooling reduces the heat 
pump  efficiency.  Usually,  it  is  recommended  that  the  system  is  designed  to  cool  down  to  a 
temperature of +5 °C [ 499, AgroTech 2008 ]. For heat pumps, see Section 4.5.5.2. 

Source: [ 197, Denmark 2010 ] 

Figure 4.30:  Example of PE pipes ready to be cast in concrete 

Achieved environmental benefits 
A  reduction  of  the  slurry  temperature  is  induced  to  reduce  ammonia  emissions  as  at  a  lower 
slurry temperature less ammonium is volatilised. The ammonia reduction efficiency depends on 
the  cooling  intensity.  Cooling  manure  is  also  expected  to  reduce  greenhouse  gas  emissions 
(primarily CH4) but the performance has not been verified [ 197, Denmark 2010 ].  

Cross-media effects 
Electrical power is needed to run the pumps (heat pump and circulation pump). If the recovered 
heat is utilised in other parts of the farm or for domestic heating, then the indirect greenhouse 
gas emissions, associated with the production of electricity, will be mitigated.  

Due to the cooling effect, the application of this technique may result in a lower ventilation rate 
compared to standard ventilation. In this case, it is important to control it so that the health and 
safety  requirements,  in  particular  exposure  to  dust,  ammonia  and  other  gases  (e.g.  hydrogen 
sulphide), are met [ 499, AgroTech 2008 ]. The technique may present problems related to ice 
formation [ 500, IRPP TWG 2011 ]. 

Environmental performance and operational data 
Channels need to be scraped daily or flushed on a frequent basis. If not, large volumes of slurry 
cannot be cooled by the relatively small heat exchanging surface.  

Intensive Rearing of Poultry or Pigs 

379 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Ammonia emission reduction depends on the type of pen floor design, but mostly on the cooling 
effect per square metre. Danish tests have shown that ammonia emissions are reduced by 10 % 
for every 10 W/m2 of added cooling effect. In other words, ammonia volatilisation is reduced by 
5–10 %  for  every  degree  the  temperature  is  lowered  [  499,  AgroTech  2008  ].  Based  on  the 
experiment  results  from  Denmark,  ammonia  emission  reduction  (compared  to  non-cooled 
manure)  can  be  estimated  by  the  following  formulae  that  refer  to  different  manure  collection 
and removal in the channels, combined with manure cooling: 

 

 

mechanical  scraping  and  frequent  removal:  NH3  emission  reduction  (%)  =  -0.008  x2  + 
1.5; 

traditional manure pit, vacuum removal and a maximum depth of the slurry in the pit of 
40 cm: NH3 emission reduction (%) = -0.004 x2 + x;  

x = cooling effect per surface (W/m2) [ 197, Denmark 2010 ]. 
where  
Cooling programmes are designed taking into account the possibility of reusing the heat. A heat 
exchange pump has a typical operating life of at least 15 years. In Denmark, the  depth of the 
slurry in the pit should be no more than 40 cm. 

Technical considerations relevant to applicability 
This technique is not applicable when heat reuse is not possible. It is also not applicable when 
bedding is used because a layer of floating residue may develop on top of the slurry.  

Manure cooling is not effective  for large slurry volumes; therefore, it may be implemented in 
new  or  existing  housing  systems  where  slurry  is  frequently  removed.  Retrofitting  is  only 
possible in manure pits where the cooling pipes can be placed above the concrete. 

Driving force for implementation 
The  system  can  be  used  on  any  farm  but  it  is  most  convenient  on  integrated  farms,  where 
farrowing  sows  and  weaners  use  the  recovered  heat  from  the  cooled  slurry  in  other  sections. 
Apart from the environmental benefit of reducing ammonia emissions, the technique may offer 
a significant energy saving, e.g. reduction of electric energy consumption by a factor of 3 [ 500, 
IRPP TWG 2011 ]. 

Example plants 
More  than  300  farms  fitted  with  this  technique  exist  in  Denmark.  A  system  with  the  heat 
exchanger has been in operation in Finland since 2004. 

Reference literature 
[  160,  Denmark  2010  ]  [ 197,  Denmark  2010  ]  [ 268,  Denmark  2010  ] [  276,  Finland  2010 ] 
[499, AgroTech 2008 ] [ 500, IRPP TWG 2011 ] 

4.7.1.8 

Slurry surface cooling fins  

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
The cooling of the slurry surface in the underfloor pit is carried out by pumping  groundwater 
through a floating heat exchanger. As the heat exchanger, arrays of plastic or metal fins are used 
which are filled with cold water and placed in the pit to float over the  slurry. In each manure 
channel,  fins  are  connected  to  one  another  in  series  and  in  parallel  between  manure  channels 
('Tichelmann' system), for a uniform cooling effect in all cooling elements over the whole slurry 
surface (see Figure 4.31). 

380 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 546, TWG ILF 2002 ]  

Figure 4.31:  Slurry surface cooling fins 

Cold groundwater circulates through the floating fins as a coolant. By the use of a heat pump 
exchanger, heat can be obtained for floor heating (see Section 4.5.5.2). The temperature of the 
top layer of the manure should not exceed 15 °C, hence the water temperature needs to be lower 
than  12 °C.  The  technique  does  not  require  frequent  slurry  removal.  It  is  applied  in  deep  pit 
systems with reported slurry removal frequency in the range of 3–12 months. 

Achieved environmental benefits 
Ammonia  emissions  are  reduced  with  a  reduction  efficiency  of  45–75 %  depending  on  the 
animal category and  the  surface area of the  cooling fins  [ 508, TFRN 2014 ]. In combination 
with a heat pump, there will be a reduction in fuel consumption for the heating of buildings (e.g. 
heating  floors  in  the  piglet  area).  Cooling  manure  is  also  expected  to  reduce  greenhouse  gas 
emissions, but the performances are unknown. 

In  a  Dutch  study  in  which  cooling  hoses  floated  on  the  surface  of  the  slurry,  a  reduction  of 
odour  emissions  of  20–25 %  was  measured  by  decreasing  the  temperature  by  3 °C  
[ 499, AgroTech 2008 ]. 

Cross-media effects 
The technique  results  in increased  energy  consumption  for  pumping  water;  however,  the  heat 
recovered  by  a  heat  exchanger  can  be  used  for  other  purposes  [169,  Netherlands  2010  ]. 
Lowering  the  temperature  of  the  slurry  and  of  the  housing  in  general  has  to  be  controlled  in 
order not to affect animal welfare and production. 

Technical considerations relevant to applicability 
On  the basis  of the experience in the  Netherlands,  the  technique can be  retrofitted  in  existing 
houses as the design and the size of the pen are not critical for the applicability of the system. 
However, other Member States are not of the same opinion and consider that this technique is 
not easy to operate or to apply. In particular, they have concerns over the fins' buoyancy, with 
the continuous generation of slurry from the pigs over the slatted floor, and the maintenance of 
to  be  difficult  and  expensive  
the  system  and  potential  solutions  are 
[ 291, IRPP TWG 2002 ] [ 500, IRPP TWG 2011 ]. The technique is not applicable when straw 
bedding is used because a layer of floating residue may develop on top of the slurry impeding 
the cooling of the manure surface [ 168, Netherlands 2010 ] [ 508, TFRN 2014 ]. The technique 
is not applicable when heat reuse is not possible. 

reported 

The technique is not applicable if pumping of groundwater is not possible (e.g. because there is 
no aquifer in the zone) [ 261, France 2010 ] [ 624, IRPP TWG 2013 ].  

Intensive Rearing of Poultry or Pigs 

381 

 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
Table 4.78 shows the reported extra investment and annual costs from the Netherlands, together 
with the expected achievable ammonia emissions reduction (compared to an FSF system). 

Table 4.78:  Costs  for  the  implementation  of  cooling  fins  for  different  animal  categories  and 

expected ammonia emissions reduction, in the Netherlands 

Cooling fins' 
surface/slurry surface 
% 
115 for individual 
housing, 
135 for group housing 
150 

Animal category 

NH3 emissions 
reduction 
%   kg/ap/yr  

Extra investment 
cost (1) 
EUR/ap  

Extra annual 
costs (2) 
EUR/ap/yr  

19 

50 

75 

75 

70 

20 

40 

2.2  

240 

110 

2.4  

150 

150 

0.15  

Gestating sows – 
partly slatted 
floor 
Farrowing sows 
Weaners – fully 
slatted floor 
Weaners – partly 
slatted floor 
Fattening pigs – 
concrete slats, 
partly slatted 
floor 
Fattening pigs –  
metal slats, partly 
slatted floor 
Fattening pigs –  
metal slats, partly 
slatted floor 
(1) The extra investment costs are calculated relative to a fully slatted floor with a deep pit. 
(2)  Annual  costs  include  depreciation,  interest,  maintenance  and  other  operating  costs  such  as  energy,  extra 

0.15  

200 

170 

200 

1.4  

1.2  

50  

1.0 

NI 

NI 

50 

35 

60 

14 

27 

6 

2 

5 

3 

manure storage, manure management costs, and the costs of any additives.  

NB: NI = no information provided. 
Source:  [  43,  COM  2003  ]  [  168,  Netherlands  2010  ]  [  169,  Netherlands  2010  ]  [  589,  Netherlands  2010  ]  

[ 640, Netherlands 2013 ] 

This  technique  is  most  economical  if  the  collected  heat  can  be  exchanged  to  warm  other 
facilities [ 508, TFRN 2014 ]. 

Driving force for implementation 
Implementation is easy, both for new buildings and for retrofitting existing houses. 

Example plants 
In  the  Netherlands,  the  system  is  implemented  in  many  rebuild  situations  and  in  some  new 
buildings, where it is applied for fattening pigs, mating and gestating sows, farrowing sows and 
piglets. 

Reference literature 
[  22,  Bodemkundige  Dienst  1999  ]  [  42,  Netherlands  1999  ]  [  43,  COM  2003  ]  [  168, 
Netherlands 2007 ] [ 169, Netherlands 2007 ][ 291, IRPP TWG 2002 ] [ 499, AgroTech 2008 ] 
[ 500, IRPP TWG 2011 ] [ 508, TFRN 2014 ] [ 546, TWG ILF 2002 ] [ 589, Netherlands 2010 ] 
[ 624, IRPP TWG 2013 ] [ 640, Netherlands 2013 ] 

382 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.7.1.9 

Frequent slurry removal by flushing (in case of a fully or partly 
slatted floor) 

This  technique  applies  to  mating  and  gestating  sows,  farrowing  sows,  weaners  and  fattening 
pigs. 

Description 
Slurry  removal  is  performed  once  or  twice  a  day  by  opening  a  gate  valve  or  sluice  gate  and 
flushing  out  the  contents  of  the  collecting  channels  beneath  the  slatted  floors  with  the  liquid 
fraction  of  the  slurry  after  mechanical  separation  (dry  matter  lower  than  approximately  5 %). 
The  liquid  fraction  of  the  slurry  can  also  be  aerated  before  flushing.  The  objective  of  the 
technique  is  to  reduce  emissions  by  frequent  removal  of  the  slurry  with  a  dilute  recirculated 
liquid  fraction.  Water  or  the  digestate  from  a  biogas  installation  can  be  used  as  well.  The 
flushing technique is used in combination with specific individual equipment at the bottom of 
channels or pits, as described below. 

Gutters 
Shallow plastic or metal channels (maximum 60 cm wide, 20 cm deep with sides sloping 60 °) 
are  placed  over  the  surface  of  slurry  channels  under  fully  slatted  or  partly  slatted  floors.  The 
oval shape is intended to reduce the surface of manure exposed to the air and to naturally drain 
the urine (see Figure 4.32). 

Tubes 
PVC tubes are incorporated into the concrete under the slats and liquid drains into these through 
slots  (see  Figure 4.33).  Alternatively,  the  bottom  of  the  pit  is  arranged  in  channels  by  the 
construction of low walls in the blockwork [ 261, France 2010 ]. 

Flushing channels with a permanent slurry layer 
Channels  underneath  the  slatted  floor  are  filled  with  a  10 cm  layer  of  slurry  manure  (see 
Figure 4.34).  A  common  feature  of  all  variations  is  the  inclination  of  the  channels  (around 
0.5 %)  that  facilitates  the  slurry  removal  by  flushing  and  allows  for  the  natural  continuous 
drainage of the urine. 

The mechanically separated liquid fraction of the slurry that is used to flush the channels has a 
low dry matter content (no higher than approximately 5 %); it may be aerated before being used 
for  flushing  (see  Section  4.12.3.1).  The  fermented  slurry  from  the  biogas  installation  is 
odourless and free of solid components and, therefore, optimal for use as a flushing liquid. 

Source: [ 42, Netherlands 1999 ] 

Figure 4.32:  Fully slatted floor with flushing gutters 

Intensive Rearing of Poultry or Pigs 

383 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 391, Italy 1999 ] 

Figure 4.33:  Fully slatted floor with flushing tubes 

Source: [ 292, Italy 2001 ] 

Figure 4.34:  Fully slatted floor with flushing of a permanent slurry layer in channels underneath 

Achieved environmental benefits 
The reduction  of  the  emitting  slurry  surface  (gutters and/or  partly  slatted floors),  the frequent 
removal  of  the  slurry  and  the  continuous  draining  of  the  urine  all  contribute  to  reduce  NH3 
emissions.  No  difference  is  reported  in terms  of  ammonia  emissions  between using  tubes and 
gutters. 

Shallow V-shaped gutters can reduce emissions in pig houses by 40 % to 65 %, depending on 
the  pig  category  and  the  presence  of  partly  slatted  floors,  after  flushing  twice  a  day  with  the 
liquid fraction of the slurry [ 508, TFRN 2014 ]. 

Frequent  emptying  of  the  slurry  channel  and  flushing  the  channel  with  water  or  the  liquid 
fraction of the separated slurry allow a lower emission reduction potential because the emitting 
surface remains the same. It is also reported that the largest reduction in emissions is achieved 
when the slurry is discharged from the gutters prior to flushing, resulting in a decrease in NH3 
emissions  of  about  70 %  compared  to  those  from  a  fully  slatted  floor  system  with  a  deep  pit  
[ 439, Sommer et al. 2006 ]. 

The quality of the flushing liquid influences the efficiency of the system, meaning that ammonia 
volatilisation is facilitated by the transfer of urea during the flushing [ 261, France 2010 ]. The 
use of fresh water as the flushing liquid reduces CH4 emissions as no slurry remains in the pit 
after emptying [ 590, Batfarm 2013 ]. Aerosols may also be reduced by frequent flushing. 

384 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
The  energy  requirements  for  these  systems  show  large  variations,  especially  in  combination 
with  the  aeration  of  the  slurry.  Energy  consumption  depends  on  the  distance  of  the  building 
from the treated slurry store.  

Odour peaks due to flushing may cause a nuisance when there are sensitive receptors near the 
farm. The peaks are higher if flushing is done without aerated slurry. It has to be decided on a 
case-by-case basis whether an overall load (thus applying a no-flushing system) or peak values 
are  more  important  [  291,  IRPP  TWG  2002  ].  When  flushing  with  water,  odour  peaks  are 
avoided  and  less  residues  are  left  in  the  gutters.  Because  of  the  odour  peak  and  the  residue 
problems, flushing with slurry has almost been abandoned in the Netherlands [ 641, IRPP IWG 
2014 ]. Frequent slurry removal by flushing is not considered appropriate in Sweden because it 
could increase the amount of sulphide concentration in the houses [ 624, IRPP TWG 2013 ].  

The frequent flushing, the proper mechanical separation of slurry and the shallow depth of the 
gutters prevent  sediments  from accumulating and the bottoms from dehydrating,  which would 
otherwise make the cleaning of the pit bottom difficult and cause fly infestations, particularly in 
the warm season [ 261, France 2010 ]. It is also reported from France that, when using slurry for 
flushing which underwent only a simple separation, sanitary risks from the flushing liquid exist 
on an integrated farm (e.g. young pigs' and sows' gutters cannot be flushed with liquid coming 
from fattening pigs) [ 500, IRPP TWG 2011 ]. Moreover, flushing with water dilutes the slurry 
and  increases  the  volume  of  slurry  produced  in  the  unit.  As  a  consequence,  the  minimum 
storage  capacity  required  increases,  as  well  as  the  cost  of  transportation  [  508,  TFRN  2014 ] 
[ 624, IRPP TWG 2013 ].  

Slurry aeration, as a technique for treating manure, is associated with potential negative effects 
(see Section 4.12.3.1). For partly slatted floors, heat stress and defecation on the solid part have 
to be avoided. See also 'Cross-media effects' in Section 4.7.1.1 for fully slatted floors. 

Technical considerations relevant to applicability 
In general, the applicability in existing houses depends on the design of the existing manure pit. 
Construction  adaptations  are  only  minor  if  the  housing  system  is  already  equipped  with  a 
manure channel. In the event that the existing house consists of a fully slatted floor with a deep 
pit,  major  construction  adaptations  are  required  [  500,  IRPP  TWG  2011  ].  Implementation  in 
existing  houses  may  be  possible  but  costly  for  gutters,  not  practicable  for  tubes,  and  possible 
with little construction adaptations for the channels with a permanent layer of slurry. 

With  this  technique,  only  over-floor  extraction  can  be  used  in  the  ventilation  system  
[ 261, France 2010 ]. The use of aerated slurry for flushing is possible only for farms already 
equipped for this type of slurry treatment. The possibility of using the effluent from the on-farm 
biological treatment of the liquid fraction of separated pig slurry is being explored in Belgium 
(Flanders). 

Economics  
Most  Italian  farms  equipped  with  these  systems  are  also  fitted  with  natural  ventilation  which 
makes  the  investments  of  the  farm  interesting.  In  comparison  to  houses  with  deep  pits,  these 
systems are also advantageous for the reduced building needs  in terms  of digging the shallow 
manure pits that are required. As a consequence of these preconditions, the investment costs that 
were  calculated  in  the  past  sometimes  gave  negative  results,  meaning  that  economic  benefits 
resulted. 

Only enlargements of farms with these systems already in place are known to be implemented. 
No  economic  values  have  been  provided.  In  the  case  of  existing  houses,  the  costs  for 
modification  of  the  ventilation  system  should  be  considered  when  the  buildings  are  equipped 
with underfloor extraction [ 261, France 2010 ]. The cost of an additional external slurry store 
should also be taken into account. 

Intensive Rearing of Poultry or Pigs 

385 

 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
The indoor air quality significantly improves, as does animal health as a consequence.  

Example plants 
Some  farms  in  Italy  are  still  equipped  with  these  systems.  Several  farms  in  the  Netherlands 
(350 farms in 2007 and 84 in the province of North Brabant alone in 2012) are equipped with 
the gutters systems and operate with non-aerated slurry. In France, the system is little developed 
and is only applied for fattening pigs and mating/gestating sows on fully slatted floor. 

Reference literature 
[ 42, Netherlands 1999 ] [ 261, France 2010 ] [ 291, IRPP TWG 2002 ] [ 292, Italy 2001 ] [ 391, 
Italy  1999  ]  [  412,  Italy  2001  ]  [  439,  Sommer  et  al.  2006  ]  [  500,  IRPP  TWG  2011  ]  [ 508, 
TFRN 2014 ] [ 590, Batfarm 2013 ] [ 624, IRPP TWG 2013 ] [ 641, IRPP IWG 2014 ] 

4.7.1.10 

Kennel or hut housing (in case of a partly slatted floor) 

This technique applies to mating and gestating sows, weaners and fattening pigs. 

Description 
The building is open and non-insulated (only the ceiling can be insulated) with a free (natural) 
ventilation system and separate functional areas in the pen. The lying area consists of a levelled 
insulated concrete floor with covered insulated boxes (huts or kennels) with a hinged roof that 
can be raised or lowered to control temperature and ventilation. The activity and feeding area 
can  be  located  over  a  perforated  or slatted floor. The  manure  generated  is  managed  as  slurry. 
Kennels have openings for air exchange. 

Due  to  the  sheltering  effect  of  covered  lying  boxes,  the  room  temperature  can  be  lower  than 
normal.  Kennels  are  kept warm  by  the  animals  in  winter  and  do  not  require  heating.  For  this 
reason, the system is particularly suitable for naturally ventilated houses.  

Achieved environmental benefits 
The operating principle is that ammonia emission reduction is brought about due to the smaller 
emitting manure surface in the pit below the partly slatted floor. Ammonia emissions are also 
reduced due to the lower room temperature requirements and the separation of functional areas. 
Providing  some  straw  on  the  solid  concrete  floor  in  the  activity  area  prevents  the  floor  from 
getting dirty and, therefore, reduces emissions to air. This system has a low energy demand due 
to the lower room temperature.  

Cross-media effects 
Careful management is required for the control of the indoor climate (temperature, airflow rate, 
etc.) [ 261, France 2010 ]. In hot climates, it must be ensured that pigs are offered the possibility 
of cooling down. For partly slatted floors, heat stress and defecation on the lying area have to be 
avoided. 

Increased  labour  requirements  for  the  management  of  the  system,  such  as  cleaning  of  the 
concrete  floor  area  in  the  lying  kennel,  are  necessary.  Water  consumption  always  slightly 
increases after reducing the slatted floor area, due to the cleaning needs of the solid floor.  

Technical considerations relevant to applicability 
This  technique  is  only  applicable  to  existing  plants  with  natural  ventilation.  It  is  applied  for 
fattening  pigs,  weaners,  mating  and  gestating  sows;  it  is  not  applied  for  farrowing  sows.  The 
benefits of natural ventilation are achieved when  the building orientation is at a right angle to 
the  main  wind  direction.  In  France,  this  technique  is  considered  as  an  outdoor  system  for  the 
implementation of Commission Regulation 2075/2005/EC on trichinellosis and leptospirosis.  

386 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Driving force for implementation 
Improved  animal  welfare  is  the  driving  force.  The  main  motivation  for  the  construction  of  a 
naturally ventilated house is generally  the  animal-friendly housing and the securing of a good 
health status. Kennel housing is needed for organic farming [ 624, IRPP TWG 2013 ].  

Chapter 4 

Example plants 
The technique is available and is frequently used in southern Germany.  

Reference literature 
[ 155, Germany 2010 ] [ 183, Germany 2010] [ 190, Germany 2010 ] [ 261, France 2010 ] [ 547, 
IMAG-DLO 2001 ] [ 575, UBA Germany 2011 ] [ 624, IRPP TWG 2013 ] 

4.7.2 

Housing systems for mating and gestating sows  

Mating and gestating sows can be housed either individually or in groups. However, Directive 
2008/120/EC requires that Member States ensure that sows and gilts are kept in groups, during a 
period  starting  from  4  weeks  after  service  to  1  week  before  the  expected  time  of  farrowing 
[ 158, EC 2008 ]. 

Requirements  for  flooring  surfaces  are  included  in  the  Directive.  In  particular,  for  gilts  after 
service  and  pregnant  sows  when  gilts  and/or  sows  are  kept  in  groups,  the  total  unobstructed 
floor  area  available  to  each  gilt  and  to  each  sow  should  be  at  least  1.64 m2  and  2.25 m2, 
respectively.  When  these  animals  are  kept  in  groups  of  fewer  than  six  individuals,  the 
unobstructed floor area should be increased by 10 %. When these animals are kept in groups of 
40  or  more  individuals,  the  unobstructed  floor  area may  be  decreased by  10 %.  In  addition, a 
part of the  above  available  area equal  to  at least  0.95  m2  per  gilt  and  at  least  1.3  m2  per  sow 
should  be  of  continuous  solid  floor,  of  which  a  maximum  of  15 %  is  reserved  for  drainage 
openings. Finally, when concrete slatted floors are used for sows kept in groups, the maximum 
width of the openings should be 20 mm for gilts after service and sows, and the minimum slat 
width should be 80 mm. Pens designed with a separate excretion area, with different functional 
areas and for larger group of sows, have a lower emission potential due to the reduced emitting 
surface [ 474, VDI 2011 ].  

Ammonia emissions associated with the techniques used to rear mating and gestating sows are 
summarised  in  Table 4.79.  Data  concerning  emissions  of  methane,  dust  and  odour  are  also 
presented, when available. 

Intensive Rearing of Poultry or Pigs 

387 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.79:  Emission levels of system-integrated housing techniques for mating and gestating sows 

Section 

Housing system 

Variant 

4.7.2.1 

Deep  pit  (in  case  of  a  fully  or 
partly slatted floor) 

4.7.2.2 

Vacuum  system  for  frequent 
slurry removal (in case of a fully 
slatted floor) 

4.7.2.3 

4.7.2.4 

4.7.2.5 

4.7.2.6 

system 

frequent 
Vacuum 
slurry removal (in case of a partly 
slatted floor) 

for 

Slanted  walls 
the  manure 
in 
channel  (in  case  of  a  fully  or 
partly slatted floor) 

for 

frequent 

slurry 
Scraper 
removal  (in  case  of  a  partly  or 
fully slatted floor) 
Frequent 
removal  by 
slurry 
flushing  (in  case  of  a  fully  or 
partly slatted floor) 

Individual 
housing 

Group housing 

Group housing, 
concrete slats 

Metal slats 

Concrete slats 
Individual housing 
(mating sows), 
concrete slats 

Concrete slats 

Metal slats 

Metal slats 

Concrete slats 

FSF 

PSF 

Group housing  

4.7.2.7 

Reduced  manure  pit  (in  case  of  a 
partly slatted floor) 

Individual housing 

4.7.2.8 

4.7.2.9 

Kennel or hut housing (in case of 
a partly slatted floor) 
Slurry cooling channels 

Slurry cooling fins 

PSF 

PSF 
Individual or group 
housing 

NH3 
kg/ap/yr 

4.2 

3.12–3.7 

4.2 

NI 

4.8 (1) 

2.40 

2.77 

4.8 (1) 

2.50 (1) 
2.60  
2.15 (4) 
2. 30 
1.85 

2.22–3.12 

1.66–2.59  

1.48–1.85  

2.96 

1.23 
2.272 (4) 

2.40 

3.75 (2) 

NI 

2.2 (2) 

CH4 
kg/ap/yr 

PM10  
kg/ap/yr 

Odour 
ouE/s/animal 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

18.2 

NI 

NA 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

57 

0.16 (2) (3) 

6.6 (4) 

Source 

[ 508, TFRN 2014 ]  

[ 43, COM 2003 ] 

[ 508, TFRN 2014 ] 

 [ 634, BE Flanders 2013] 

[ 156, Germany 2010 ] 
[ 162, Germany 2010 ] 

NI 

NI 

NI 

NI 

[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

0.16 (2) (3) 

6.6 (5) 

0.22 (6) 

0.22 (6) 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

18.7 

18.7 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.16(2) (3)  

6.6 (2) (5) 

NI 

0.22 (2) 

NI 

NI 

[ 163, Germany 2010 ] 
[ 474, VDI 2011 ] 

[ 165, Netherlands 2010 ] 
[ 186, BE Flanders 2010 ] 
[ 166, Netherlands 2010 ] 
[ 186, BE Flanders 2010 ] 
[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

[ 164, Spain 2010 ] 

[ 43, COM 2003 ] 
[ 155, Germany 2010 ] 
[ 474, VDI 2011 ] 
NI 
[ 168, Netherlands 2010 ] 
[ 169, Netherlands 2007 ] 

388 

Intensive Rearing of Poultry or Pigs 

Section 

Housing system 

Variant 

4.7.2.10 

Full  litter  system  (in  case  of  a 
solid concrete floor) 

Full litter (no 
separate functional 
areas) 
Slatted defecating 
area 
Bedded lying area, 
separate defecating 
area and feeding 
area with electronic 
sow feeders 
Separate feeding 
area  

4.7.2.11 

Feeding/lying  boxes  on  a  solid 
floor (in case of litter-based pens) 

Solid floor 

NH3 
kg/ap/yr 

2.5–5.6 

3.7–5.2 

4.8 (2) (7) 

4.8 (2)  

2.6 

CH4 
kg/ap/yr 

PM10  
kg/ap/yr 

Odour 
ouE/s/animal 
NI 

NI 

NI 

NI 

0.8(2) (3) 

6.6 (2) (5) 

0.8(2) (3) 

6.6 (2) (5) 

NI 

NI 

NI 

NI 

NI 

Chapter 4 

Source 

[ 261, France 2010 ] 

[ 43, COM 2003 ] 
[ 157, Germany 2010 ] 
[ 474, VDI 2011 ] 
[ 161, Germany 2010 ] 
[ 474, VDI 2011 ] 

1.96–3.5 (4) (6) 

5.5–6.2 (6) 

1 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 186, BE Flanders 2010 ] 

[ 230, Philippe et al. 2009 ] 

[ 186, BE Flanders 2010 ] 

(1) Values derived from measurements.  
(2) Values derived by expert judgement based on conclusions by analogy.  
(3) All stages of breeding sows, including piglets up to 25 kg.  
(4) Measured values.  
(5) Values calculated from an emission of 22 ouE/s per LU and an average weight of 150 kg for early-pregnant or non-pregnant sows.  
(6) The upper value is related to ad libitum feeding; the lower value is related to restricted feeding. 
(7) In the event that there is a yard, additional emissions are likely. 
NB: NI = no information provided. 

Intensive Rearing of Poultry or Pigs 

389 

 
 
  
 
 
 
Chapter 4 

4.7.2.1 

Deep pit (in case of a fully or partly slatted floor) 

Description 
See Section 4.7.1.1 for fully slatted floors and Section 4.7.1.1.1 for partly slatted floors. Group 
housing  is  compulsory  for  all  mating  and  gestating  sows  (except  for a  four-week  period  after 
insemination and 1 week before farrowing).  

Achieved environmental benefits 
See Section 4.7.1.1 (fully slatted floors) and Section 4.7.1.1.1 (partly slatted floors). 

Cross-media effects 
See Section 4.7.1.1 (fully slatted floors) and Section 4.7.1.1.1 (partly slatted floors). 

Environmental performance and operational data 
The  emission  levels  associated  in  the  original  ILF  BREF  [  43,  COM  2003  ]  with  a  housing 
system with a fully slatted floor, forced ventilation and an underlying deep collection pit were 
between  3.12 kg  and  3.70  kg  NH3  per  sow  place  per  year,  whereas  individual  housing  was 
associated with higher levels at 4.2 kg NH3 per sow place per year. However, according to the 
UNECE  guidance  document  on  'Options  for  ammonia  mitigation',  group  housing  has  similar 
emission levels to individual housing and ammonia emissions for the system are considered  to 
be equal to 4.2 kg NH3 per sow place per year [ 508, TFRN 2014 ].  

Odour emissions have been measured at 57 ouE/animal/s [ 634, BE Flanders 2013 ]. Ventilation 
rates  reported  by  Belgium  (Flanders)  are  6–20 m3/h/sow  for  the  cold  season  and  20–
80 m3/h/sow  for  the  warm  season  [  637,  BE  Flanders  2012  ].  The  energy  required  for  forced 
ventilation is variable, but on average in Italy this has been estimated as 42.2 kWh per sow per 
year [ 292, Italy 2001]. 

Technical considerations relevant to applicability 
No information provided. 

Economics 
The  average  investment  required  in  the  Netherlands  for  a  new  integrated  building  for  sow 
housing with a manure pit 0.8 m deep (including 130 farrowing pens with a fully slatted floor 
and 4.5 m2 per pen; 2016 weaner places with 0.4 m2 total surface per animal place and a partly 
slatted floor with a 60 % convex solid floor; 477 mating and gestating sow places with 2.25 m2 
total  surface  per  place  with  a  60 %  solid  floor)  are  reported  as  EUR  2 240  per  sow  place, 
excluding  any  additional  system  aiming  to  reduce  ammonia  emissions.  Investment  costs  per 
gestating sow place range from EUR 1 040 to EUR 1 160 depending on the volume and size of 
the pens [ 589, Netherlands 2010 ]. 

Driving force for implementation 
See Section 4.7.1.1 for fully slatted floors and Section 4.7.1.1.1 for partly slatted floors. 

Example plants 
No information provided. 

Reference literature 
[ 43, COM 2003 ] [ 292, Italy 2001 ] [ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] [ 634, BE 
Flanders 2013 ] [ 637, BE Flanders 2012 ] 

390 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.7.2.2 

Vacuum system for frequent slurry removal (in case of a fully 
slatted floor) 

Description 
See  also  Section  4.7.1.2.  A  housing  system  implementing  slurry  removal  by  vacuum  (with  a 
frequency of 2–8 weeks) is reported from Germany for gestating sows, where the lying area is 
drained by a perforated floor [ 156, Germany 2010 ]. The system is illustrated in Figure 2.14.  

Achieved environmental benefits 
See Section 4.7.1.2. A reduction of 25 % for NH3 emissions is reported due to frequent removal 
of slurry in comparison with a fully slatted floor system with a deep pit [ 508, TFRN 2014 ].  

Cross-media effects 
See Section 4.7.1.2. 

Environmental performance and operational data 
Italian data reported about 2.77 kg NH3 per sow place per year. The slurry removal frequency by 
vacuum  is  reported  by  Germany  as  2  to  8  weeks,  without  any  effect  on  ammonia  emissions 
(4.8 kg NH3/ap/yr) [ 156, Germany 2010 ] [ 162, Germany 2010 ]. Ventilation rates reported by 
Germany  are  14–18  m3/h/animal  for  the  cold  season  and  86–128 m3/h/animal  for  the  warm 
season [ 156, Germany 2010 ]. See also Section 4.7.1.2. 

Technical considerations relevant to applicability 
See Section 4.7.1.2. 

Economics  
See Section 4.7.1.2.  

Driving force for implementation 
See Section 4.7.1.2.  

Example plants 
This technique is widely used in Germany. In France, this is the most commonly used system in 
buildings  with  shallow  pits;  however,  slurry  is  stored  during  the  whole  rearing  cycle  [  261, 
France 2010 ]. 

Reference literature 
[ 156, Germany 2010 ] [ 162, Germany 2010 ] [ 261, France 2010 ] [ 292, Italy 2001 ] [ 508, 
TFRN 2014 ] 

4.7.2.3 

Vacuum system for frequent slurry removal (in case of a partly 
slatted floor) 

Description 
See  also  Section  4.7.1.3.  A  housing  system  with  vacuum  removal  (with  a  frequency  of  2–8 
weeks)  is  reported  from  Germany  for  mating  sows  with  temporary  fixing  in  the  insemination 
area  in  combination  with  a  partly  slatted  floor  (service  centre)  [  163,  Germany  2010  ].  The 
system is illustrated in Figure 2.9. 

Achieved environmental benefits 
See  also  Section  4.7.1.3.  A  reduction  of  25 %  for  NH3  emissions  is  reported  due  to  frequent 
removal of slurry in comparison with a fully slatted floor system with a deep pit [ 508, TFRN 
2014 ]. 

Cross-media effects 
See Section 4.7.1.3. 

Intensive Rearing of Poultry or Pigs 

391 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
With a partly slatted floor and a vacuum system, NH3 emissions are reduced to 2.77 kg per sow 
place per year on concrete slats, and to 2.40 kg per sow place per year on metal slats for group 
housing  of  gestating  sows.  The  system  was  credited  with  allowing  an  emission  reduction, 
compared to fully slatted floors with a deep pit, of 25 % with concrete slats or 35 % with metal 
slats,  where  less  manure  is  retained  [  43,  COM  2003  ].  In  Germany,  no  ammonia  emission 
reduction is associated with this housing system (emission factor of 4.8 kg NH3/ap/yr) where the 
perforation or not of the lying area has no effect on ammonia emissions [ 162, Germany 2010 ].  

Technical considerations relevant to applicability 
See Section 4.7.1.3. 

Economics 
See Section 4.7.1.3. 

Driving force for implementation 
See Section 4.7.1.3. 

Example plants 
See Section 4.7.1.3. 

Reference literature 
[ 43, COM 2003 ] [ 162, Germany 2010 ] [ 163, Germany 2010 ] [ 291, IRPP TWG 2002 ] 
[ 508, TFRN 2014 ] 

4.7.2.4 

Slanted walls in the manure channel (in case of a fully or partly 
slatted floor) 

Description 
See  also  Section  4.7.1.4.  This  housing  system  is  reported  to  be  applied  for  group  housing  of 
gestating sows on partly slatted floors without straw bedding, where the minimum surface per 
sow  is  2.25 m2,  of  which  at  least  1.3  m2  (60 %)  per  sow  is  solid  floor.  A  maximum  emitting 
surface of 0.55 m2 in the channel corresponds to each animal. A cross section and a plan view of 
the technique are shown in Figure 4.35. 

392 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 167, Netherlands 2010 ] 

Figure 4.35:  Cross section and plan view of the floor in a housing system for gestating sows with a 

manure channel with slanted walls 

Achieved environmental benefits 
See Section 4.7.1.4. An emission reduction efficiency of 45 % is reported for group housing of 
gestating sows with feeding stalls in comparison with a fully slatted floor system with a deep pit 
[ 508, TFRN 2014 ]. 

Cross-media effects 
See Section 4.7.1.4. 

Environmental performance and operational data 
A  potential  reduction  of  ammonia  emissions  of  up  to  50 %  is  reported  when  combined  with 
frequent emptying of the slurry channels [ 439, Sommer et al. 2006 ]. From the Netherlands, the 
room temperature in housing systems for gestating sows is reported to be around 20 °C and the 
minimum frequency for slurry removal twice a week. Triangular metal slats will further reduce 
ammonia  emissions.  Reported  emissions  associated  with  the  technique  are  shown  in 
Figure 4.79. 

Intensive Rearing of Poultry or Pigs 

393 

 
 
 
 
 
 
 
Chapter 4 

Table 4.80:  Emission levels associated with slanted walls in the manure channel (in case of partly 

slatted floors) 

Animal 

Gestating sows, 
metal slats, 
emitting surface 
< 0.55 m2/animal 

Gestating sow, 
concrete slats, 
emitting surface 
< 0.50 m2/animal 

NH3 

CH4 

PM10  

Odour 

kg/ap/yr 

ouE/s/animal  

2.15 
(1.76–2.53) (1) 

NI 

0.175 (1)  

18.7 (1) 

2.3 

NI 

NI 

2.5 (2) 

0.175 (1) 

18.7 (1) 

NI 

2.6  

NI 

NI 

Slurry 
removal 
frequency 

Once every 
2 weeks 

Once each 
week 

Once every 
2 weeks 

Once each 
week 

Source 

[166, 
Netherlands 
2010] 
 [ 186, BE 
Flanders 2010 ] 
[ 165, 
Netherlands 
2010 ] 
[ 186, BE 
Flanders 2010 ] 

(1) Measured data. 
(2) Values derived from measurements. 
NB: NI = no information provided. 

Technical considerations relevant to applicability 
In  general,  the  system  can  be  easily  adapted  to  existing  gestation  pens,  especially  when 
individual housing is converted into group housing and the free run area between the rows of 
crates is wide enough. If this area is not wide enough, the crates can be placed above the control 
corridor. The solution can also fit other group housing systems without crates, for example those 
equipped  with  feeding  stations  [  166,  Netherlands  2010  ].  When  the  technique  is  adapted  to 
existing gestation pens, and if the existing manure pit is already shallow (0.80 m to 1.2 m), the 
location  of  the  already  existing  discharge  openings will  be crucial for  retrofitting  this system. 
See also Section 4.7.1.4. 

Economics 
In the Netherlands, depending on the material the slats are made from, extra investment costs 
for the implementation of the technique are reported as EUR 130 per animal place for triangular 
iron slats, and EUR 100 per animal place for concrete slats. The corresponding annual costs are 
EUR 15/ap/yr and EUR 10/ap/yr respectively (including depreciation, interest, maintenance and 
all other operating costs, such as energy) [ 165, Netherlands 2010 ] [ 166, Netherlands 2010 ] [ 
589,  Netherlands  2010  ].  The  annual  extra  costs  are  reported  as  equal  to  EUR  16  per  animal 
place and the cost efficiency EUR 10 per kg of NH3-N reduced [ 508, TFRN 2014 ]. 

In  Belgium  (Flanders),  the  extra  cost  (compared  to  a  fully  slatted  floor  with  a  deep  pit)  is 
reported  as  EUR 292  per  animal  place (23 %  higher)  [  300,  BE  Flanders  2010  ].  In  the  event 
that  the  existing  manure  pit  is  already  shallow  and  existing  discharge  openings  are  usable, 
retrofitting costs are reported to amount to EUR 472 per gestating sow place (group-housed). If 
the  existing  discharge  openings  cannot  be  used,  costs  will  be  substantially  higher  [  273,  BE 
Flanders 2010 ].  

Driving force for implementation 
The  technique  offers  an  efficient  solution  for  adapting  existing  sow  housing  systems  from 
individual  housing  to  group  housing  (in  compliance  with  Directive  2008/120/EC)  with  lower 
ammonia emissions. With this housing system, the pens and the crates can be used for the group 
housing by using the central slatted floor between the rows of crates as a free run for the sows.  

Example plants 
In  Belgium  (Flanders),  this  technique  is  widely  applied,  with  a  total  of  244  sow  farms 
authorised (including farms below and above the production capacity threshold set by Directive 
2010/75/EU). It is also widely applied throughout the Netherlands.  

394 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Reference literature 
[ 165, Netherlands 2010 ] [ 166, Netherlands 2010 ] [ 167, Netherlands 2010 ] [ 186, BE 
Flanders 2010 ] [ 273, BE Flanders 2010 ] [ 300, BE Flanders 2010 ] [ 439, Sommer et al. 
2006 ] [ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] 

Chapter 4 

4.7.2.5 

Scraper for frequent slurry removal (in case of a fully or partly 
slatted floor) 

Description 
See Section 4.7.1.5.  

Achieved environmental benefits 
See Section 4.7.1.5.  

Cross-media effects 
See Section 4.7.1.5.  

Environmental performance and operational data 
NH3 emission levels reported by Italy of 1.85 kg (on metal slats) and 2.22 kg (on concrete slats), 
and  by  Denmark  of  3.12 kg  (concrete  slats)  per  sow  place  per  year  are  achieved  with  the 
technique.  These  levels  represent  a  reduction  of  50 %  for  metal  slats  and  15 %  to  40 %  for 
concrete  slats  compared  to  a  fully  slatted  floor  with  a  deep  pit.  Clearly,  the  frequency  of 
scraping  and  the  smoothness  of  the  pit  floor  surface  are  factors  which  help  determine  the 
reduction that can be achieved. These emission levels were obtained under average conditions. 
The frequency of scraping was once a day. Application of metal slats gives lower emissions as 
slurry is removed faster into the pit. 

Technical considerations relevant to applicability 
See Section 4.7.1.5.  

Economics 
Data on capital costs are not available, but the operating costs per pig per year are considered to 
be high [ 291, IRPP TWG 2002 ]. 

Driving force for implementation 
See Section 4.7.1.5.  

Example plants 
There  are  very  few  applications  with  an  external  alley  design  in  Italy.  This  system  is  also  in 
operation in Denmark and in the Netherlands, where it is no longer applied in new buildings. 
Scrapers in France are only associated with fully slatted floors [ 261, France 2010 ]. 

Reference literature 
[ 42, Netherlands 1999 ] [ 261, France 2010 ] [ 291, IRPP TWG 2002 ] [ 391, Italy 1999 ] [ 412, 
Italy 2001 ]  

4.7.2.6 

Frequent slurry removal by flushing (in case of a fully or partly 
slatted floor) 

Description 
See  Section  4.7.1.9.  Application  is  possible  in  pens  with  a  partly  or  fully  slatted  floor,  in 
individual  stalls  and  in  group  housing  systems.  A  design  with  flushing  gutters  in  individual 
housing is illustrated in Figure 4.36. The manure surface should be no larger than 1.10 m2 per 
sow. 

Intensive Rearing of Poultry or Pigs 

395 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 42, Netherlands 1999 ] 

Figure 4.36:  Flushing gutters in individual mating/gestating sow housing (in case of a partly slatted 

floor) 

For group housing, the same description applies as that given in  Figure 4.32. The pictures are 
only different in the sense that the concrete floor surface is larger and the slatted part with the 
slurry gutters/tubes underneath is smaller. 

Achieved environmental benefits 
See Section 4.7.1.9. An ammonia emission reduction of 40 % is reported for the flushing gutters 
technique when applied in gestating sow housing systems [ 508, TFRN 2014 ].  

Cross-media effects 
See Section 4.7.1.9. 

Environmental performance and operational data 
Emission  data  from  flushing  frequently  channels,  equipped  with  gutters  or  tubes  or  having  a 
permanent slurry layer, with aerated slurry or non-aerated slurry, are presented in Table 4.81. 

Table 4.81:  Ammonia  emissions  from  mating/gestating  sow  houses  with  frequent  slurry  removal 

by flushing  

Variant 

Floor 

NH3 emission (1) 

Aerated 
Non-aerated 
slurry 
slurry 
kg/animal place/year 
1.11 
1.66 

1.48 
2.22 

NH3 emission reduction 
Aerated 
slurry 

Non-aerated 
slurry 

(%) 

60 
40 

30 

50 

70 
55 

55 

60 

PSF 
FSF 

Gutters/tubes 
Gutters/tubes 
Channels with a 
permanent slurry layer 
Channels with a 
permanent slurry layer 
(1) Elaboration based on data from the ILF BREF (2003).  

2.59 

1.85 

FSF 

PSF 

1.66 

1.48 

NB: Comparison with a system with FSF and a deep pit. 
Source: [ 43, COM 2003 ] [ 292, Italy 2001 ] [ 42, Netherlands 1999 ] 

Energy consumption levels for operating the flushing systems, for separating the slurry and for 
aeration are reported in Table 4.82. 

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Table 4.82:  Energy requirements for flushing systems applied in gestating sow houses  

Chapter 4 

System 

Energy requirement by operation 
(kWh/ap/yr) 
Mechanical 

Total 
(kWh/ap/yr) 

Flushing 

separation of slurry  Aeration  Non-aerated 

Aerated 
slurry 
32.4 
FSF with flushing gutters 
30 
PSF with flushing gutters 
40.3 
FSF with flushing channels 
PSF with flushing channels 
38.5 
NB: An extra energy consumption of 0.5 kWh per sow place is required for extra pumping when flushing is done 

slurry 
18.5 
14.4 
22.8 
21.7 

14.6 
12.03 
14.6 
18.3 

13.9 
15.6 
17.5 
16.8 

3.9 
2.4 
8.2 
3.4 

twice a day. 

Source: [ 43, COM 2003 ] 

Technical considerations relevant to applicability 
See Section 4.7.1.9. 

Economics 
The  extra  annual  cost  for  new  houses  equipped  with  flushing  gutters  in  comparison  to  fully 
slatted floors with a deep pit is estimated at EUR 33 per animal place and the cost efficiency at 
EUR 23/kg of NH3-N abated [ 508, TFRN 2014 ]. For other designs, no cost data are reported. 

Driving force for implementation 
See Section 4.7.1.9. 

Example plants 
See Section 4.7.1.9. In 2001, in Italy, about 5 000 sows were kept on FSF with gutters and 7 000 
sows  on  FSF  with  tubes.  Examples  with  partly  slatted  floors  were  found  in  Italy  and  in  the 
Netherlands. 

Reference literature 
[ 42, Netherlands 1999 ] [ 43, COM 2003 ] [ 292, Italy 2001 ] [ 391, Italy 1999 ] [ 412, Italy 
2001 ] [ 508, TFRN 2014 ] 

4.7.2.7 

Reduced manure pit (in case of a partly slatted floor) 

Description 
Ammonia emissions can be reduced by applying the principle of reducing the manure surface 
area,  in  particular  by  applying  a  small  manure  pit  with  an  approximate  width  of  0.60 m.  The 
manure pit is equipped with triangular metal slats or concrete slats.  

Substantial  reductions  of  the  channel  width  are  possible  when  sows  are  individually  housed. 
Urine  and  faeces  fall  at  the  back  of  the  stall  into  the  narrow  pit.  As  a  consequence,  the 
cleanliness and the welfare for animals and workers are improved. Gilts houses need a wider pit 
[ 261, France 2010 ]. 

The slurry is usually removed via a central sewer system by opening a valve and using a sloping 
manure channel. Some systems are equipped with scrapers (see Section 4.7.1.5). 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Source: [ 42, Netherlands 1999 ] 

Figure 4.37:  Individual housing with a small manure pit  

In  Italy,  a  house  for loose gestating  sows  and  fattening  pigs  was  reported  to be  in  use  with  a 
fully  slatted  external  alley  with  the  slurry  pit  underneath.  Indoors,  the  animals  are  kept  on  a 
solid concrete floor and a hatched opening gives access to the external alley (see Figure 4.38). 
The  environmental  performance  and  operating  conditions  are  comparable  to  those  of  the 
standard indoor system, but costs may be different. 

Source: [ 292, Italy 2001 ] 

Figure 4.38:  Solid concrete floor and fully slatted external alley with a storage pit underneath 

Achieved environmental benefits 
The reduction of emitting surfaces, attained by the smaller manure pit and the fast discharge of 
the  manure  (by  using  triangular  slats),  reduces  the  NH3  emissions  by  20 %  to  40 %.  The 
efficiency  of  the  technique  depends  on  the  cleaning  of  the  slats,  otherwise  there  will  be  no 
positive effect. 

Cross-media effects 
In  the  case  of  the  external  slurry  pit,  a  reduced  emission  will  not  benefit  the  internal 
environment, which can be considered one of the advantages of reducing the pit inside. A slight 

398 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
increase of water consumption is associated with a reduction of the slatted floor area, due to the 
greater cleaning needs of the solid floor [ 500, IRPP TWG 2011 ] [ 261, France 2010 ]. 

Environmental performance and operational data 
Reported  emission  data,  concerning  ammonia  and  methane,  are  summarised  in  Table 4.83.  In 
Spain, a 49 % ammonia reduction was measured for individual housing of gestating sows [ 164, 
Spain 2010 ]. 

Chapter 4 

Table 4.83:  Emissions from housing systems for gestating sows with a reduced manure pit 

Housing system 

Gestating sows, group 
housing, solid concrete floor 
and external alley 
Gestating sows, individual 
housing, (maximum width 
of the pit of 0.60 m) 
(1) Measured data. 
NB: NI = no information provided. 

NH3 emission 
kg/ap/yr 

CH4 emission 
kg/ap/yr 

Source 

2.96 

NI 

[ 43, COM 2003 ] 

1.23–2.40 

2.272 (1) 

NI 
18.2 
(1.5–55.5) (1) 

[ 43, COM 2003 ] 

[164, Spain 2010 ] 

These houses can be naturally or mechanically ventilated. In Denmark, mechanical ventilation is 
applied  and  dimensioned  for  an  output  of  a  maximum  of  100  m3  per  hour  per  sow  place.  In 
areas  with  low  outdoor temperatures,  these  units can  also be  equipped  with  auxiliary  heating. 
Energy input is unchanged. 

Technical considerations relevant to applicability 
In existing houses, the applicability depends on the design of the existing manure pit, but it is 
mostly difficult, if not impossible, to apply. For existing housing with an internal solid concrete 
floor, an extension with an external alley with a storage pit might be possible [ 292, Italy 2001 ]. 
The application of a maximum  width of 0.60 m  may require more pit depth or more frequent 
removal and consequently increased outside manure storage. If a minimum pit size is imposed 
then, consequently, a reduction of emissions may not be possible (e.g. Ireland: > 0.90 m). 

Economics 
Extra  costs  have  been  calculated  in  Spain  for  the  implementation  of  the  technique  (50 % 
reduction  of  the  width  the  manure  pit  by  reforming  a  fully  slatted  floor  with  a  deep  pit  to  a 
partly  slatted  floor  with  50 %  solid  floor).  Results  are  given  in  Table 4.84,  including  the  cost 
efficiency of the technique. Additional emission reductions that can be achieved with increased 
removal frequency are not taken into account.  

Table 4.84:  Calculated  extra  costs  for  installing  a  reduced  manure  pit  for  gestating  sows  in 

existing houses with a fully slatted floor 

NH3 emission 
reduction (%) 

35 

Extra cost 
(EUR/place per 
year) 
5.69–6.83 

Extra cost (EUR/t 
pig produced) (1) 

Extra cost (EUR/kg 
NH3 reduced) 

Additional reduction 
for frequent removal 

2.1–3.0 

6.0–7.0 

25 % 

(1) Calculated on the basis of an annual production of 2 666 kg of pig meat per gestating place. 
Source: [ 338, Piñeiro et al. 2009 ] [ 379, Spain 2009 ] 

In Belgium (Flanders), in individual housing for mating and gestating sows, the reported extra 
costs  (including  all  construction  works  inside  the  pit,  as  well  as  the  cost  for  the  additional 
required  storage  capacity) for the  housing  construction,  compared to  houses  with  fully  slatted 
floors and a deep pit of 1.2 m depth, are equivalent to EUR 450 per animal place in the case of 

Intensive Rearing of Poultry or Pigs 

399 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

new houses, and EUR 671 per animal place for rebuilding existing housing. For group-housed 
sows, extra investment costs are reported to  be EUR 292 per animal place in the case of new 
houses, and EUR 472 per animal place for retrofitting existing houses [ 274, BE Flanders 2010 ] 
[ 273, BE Flanders 2010 ]. 

Driving force for implementation 
Partly slatted floors are considered to improve animal welfare Energy savings are possible when 
forced ventilation is not required [292, Italy 2001]. 

Example plants 
A common housing system for mating and gestating sows.  

Reference literature 
[ 42, Netherlands 1999 ] [ 43, COM 2003 ] [ 164, Spain 2010 ] [ 261, France 2010 ] [ 273, BE 
Flanders 2010 ] [ 274, BE Flanders 2010 ] [ 292, Italy 2001 ] [ 338, Piñeiro et al. 2009 ] [ 379, 
Spain 2009 ] [ 391, Italy 1999 ] [ 500, IRPP TWG 2011 ] 

4.7.2.8 

Kennel or hut housing (in case of a partly slatted floor) 

Description 
See Section 4.7.1.10 and to Figure 4.39. The activity and feeding area are placed on a perforated 
floor. Slurry is produced and removed at frequent intervals (every 2 to 8 weeks).  

Source: [ 155, Germany 2010 ] 

Figure 4.39:  Kennel housing system for gestating sows  

In  a  variant  of  the  technique  (see  Figure 4.40),  sow  feeders  are  located  in  partly  slatted 
individual  stalls  and  the  lying  area  in  the  kennels  (huts)  is  littered.  A  covered  yard  is  also 
combined. In this system, solid manure and slurry are produced.  

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Chapter 4 

Source: [ 155, Germany 2010 ] 

Figure 4.40:  Kennel housing for mating and gestating sows with individual feeding stalls  

Achieved environmental benefits 
See  Section  4.7.1.10.  From  Germany,  a  reduction of  25 %  of  ammonia  emissions  is reported.  

Cross-media effects  
See Section 4.7.1.10 

Environmental performance and operational data 
The  ammonia  emission  factor  for  naturally  ventilated  kennel  housing  for  gestating  sows  in 
  emissions  are  0.22  kg/ap/yr  and  odour 
Germany  is  reported  as  3.75  kg  NH3/ap/yr;  PM10
emissions  8  ouE/s/animal  [  155,  Germany  2010  ].  Data  concerning  energy  consumption  and 
labour requirements are presented in Table 4.85. 

Table 4.85:  Consumption  and  labour  requirements  for  kennel  housing  systems  for  mating  and 

gestating sows 

Bedding 
kg/ap/yr 
140 (1) 

Electricity 
kWh/ap/yr 

Fuel 
kWh/ap/yr 

Cleaning water 
l/ap/yr 

Labour 
h/ap/yr 

16 

0 

250–360 (1) 

1 

(1) These values apply when the system with the littered hut is used.  
Source: [ 155, Germany 2010 ] 

In  naturally  ventilated  kennel  systems  in  Germany,  mating  and  gestating  sows  are  kept  in 
groups of at least 40 animals. The reported available space per animal, applied in Germany, is 
2.9 m2/sow. 

Technical considerations relevant to applicability 
See Section 4.7.1.10. For mating and gestating sows, forced ventilation can be applied.  

Intensive Rearing of Poultry or Pigs 

401 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
No information provided. 

Driving force for implementation, Example plants 
See Section 4.7.1.10. 

Reference literature 
[ 155, Germany 2010 ] 

4.7.2.9 

Slurry cooling 

Description 
Slurry cooling channels or slurry surface cooling fins can be used. See Section 4.7.1.7 for slurry 
cooling channels and Section 4.7.1.8 for surface cooling fins. 

Achieved environmental benefits 
See Sections 4.7.1.7 and 4.7.1.8. 

Cross-media effects 
See Sections 4.7.1.7 and 4.7.1.8. 

Environmental performance and operational data 
Danish tests with slurry cooling channels in gestating sow houses equipped with partly slatted 
floors and mechanical scrapers showed an ammonia reduction of 31 % for an average cooling 
intensity of 24 W/m2 (the warmest period of 37 days in summer was omitted, as the cooling was 
switched  off).  The  cooling  programme  was  guided  by  the  need  to  heat  the  piglet  floors  in 
farrowing  pens  [  197,  Denmark  2010  ].  In  Denmark,  the  maximum  ammonia  emissions 
reduction that can be achieved  in gestating sows houses with pens and a partly slatted floor is 
reported  to  be  30 %,  compared  to  a  corresponding  housing  system  without  cooling  
[ 499, AgroTech 2008 ]. The energy requirements for sows are in the range of 151–452 kWh per 
animal place per year, based on the cooling programme (see Table 4.86).  

Table 4.86:  Expected electricity consumption depending on the cooling programme applied 

Pen design 

Group housing, partly slatted floor 
Source: [ 197, Denmark 2010 ] 

Cooling area 
per pig place 
m2 
1.75 

10 W/m2 

20 W/m2 

30W/m2 

151 

kWh/ap/yr 
302 

452 

Ammonia  emissions  have  been  measured  at  2.2 kg  NH3  per  sow  place  per  year  for  slurry 
cooling fins. The corresponding ammonia emission reduction is equal to 50 %  in houses with 
partly slatted floors compared to  houses with fully slatted floored with a deep pit. To achieve 
this performance, for individual housing, the manure surface under the slatted floors  has to be 
adjusted to at least 1.0 m2 per sow place and the ratio of the fins' cooling surface to the manure 
surface should be at least 115 %. For group housing, the corresponding values are 1.1 m2  per 
sow  place,  and  the  ratio  of  cooling  fins'  surface  to  manure  surface  is  135 %.  Dust  and  odour 
emissions  per  sow  place  and  year  are  estimated  at  0.22 kg  and  18.7 ouE  respectively  
[ 168, Netherlands 2010 ] [ 169, Netherlands 2010 ] [ 640, Netherlands 2013 ]. 

For slurry cooling fins, the extra energy consumption is estimated at 19 kWh per gestating sow 
place per year for partly slatted floors [ 589, Netherlands 2010 ]. 

Technical considerations relevant to applicability 
See Sections 4.7.1.7 and 4.7.1.8. 

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Chapter 4 

Economics 
The extra costs for the implementation of the slurry cooling channels  technique  in a gestating 
sow house operating with a scraper system are reported from Denmark to vary between EUR -8 
to  EUR 38  per  animal  place  per  year.  This  means  that  a  benefit  of  EUR 8  will  be  generated 
when 100 % of the recovered heat is used on farm to replace conventional fuels, while the cost 
of EUR 38/ap/yr corresponds to the situation in which no heat is utilised and a cooling effect of 
30 W/m2 is applied. In Denmark, the slurry cooling channels technique is reported to have lower 
maintenance  costs,  compared  with  other  slurry  cooling  systems  (i.e.  floating  surface  cooling 
fins). 

The  extra  investment  costs  for  the  application  of  surface  cooling  fins  are  calculated  as 
EUR 110 per  animal  place  and  the  extra  annual  costs  as  EUR  20  per  animal  place  (see 
Table 4.78). An extra cost of EUR 19 per animal place per year for new buildings equipped with 
surface cooling fins and a cost efficiency of EUR 12 per kg  of NH3-N reduced are reported [ 
508, TFRN 2014 ].  

Driving force for implementation 
See Sections 4.7.1.7 and 4.7.1.8. 

Example plants 
See Sections 4.7.1.7 and 4.7.1.8. 

Reference literature 
[  160,  Denmark  2010  ]  [  197,  Denmark  2010  ]  [  168,  Netherlands  2010  ]  [  169,  Netherlands 
2010  ]  [  499,  AgroTech  2008  ]  [  508,  TFRN  2014  ]  [  589,  Netherlands  2010  ]  [  640, 
Netherlands 2013 ] 

4.7.2.10 

Full litter system (in case of a solid concrete floor) 

Description 
Groups of sows are kept in pens on a fully concrete floor that is almost completely covered with 
a  layer  of  straw  or  other  lignocellulosic  materials  to  absorb  urine  and  incorporate  faeces  (see 
Figure 2.11). Solid manure is obtained, which has to be frequently removed in order to prevent 
the  litter  from  becoming  too  moist.  This  housing  system  can  have  either  natural  or  forced 
ventilation.  

Litter is managed by the deep litter system (manure is removed at the end of the rearing period 
or  after  several  successive production  cycles)  or  the littered-floor  system  (manure  is removed 
one to three times per week or more frequently and straw is replaced) [ 261, France 2010 ].  

In a variant of the technique for gestating sows, reported from Germany for naturally ventilated 
buildings,  separate  functional  areas  are  organised  on  a  plane  solid  floor,  combined  with  an 
external yard. The activity and lying area is on an insulated solid concrete floor covered with 
straw  (about  1.4  m2  per  sow);  the  feeding  area  can  be  on  a  raised,  slatted  floor  (producing 
slurry)  and  the  external  yard  is  on  a  concrete  level  (about  1  m2  per  head),  fully  littered  with 
straw.  Feeding  and  drinking  systems  are  automatic.  Manure  is  removed  from  the  slatted  area 
daily [157, Germany 2010 ]. The system is illustrated in the following figure (Figure 4.41). 

Intensive Rearing of Poultry or Pigs 

403 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 157, Germany 2010 ] 

Figure 4.41:  Littered floor with a slatted feeding area  

In another design, the available space in the housing system is subdivided into a lying area, a 
dunging  area  on  a  solid  floor  and  a  feeding  area.  For  each  group  of  sows,  a  clear  division 
between these areas should be provided. The lying area is fully littered and used by the sows as 
a  resting  area,  and  only  a  limited  amount  of  manure  spots  should  be  present.  The  lying  area 
commonly covers 1.31.5 m2/animal place in Belgium. The bedding has a depth of at least 0.15 
m  and  0.40  m  at  the  most.  The  activity  area  consists  of  the  following  functional  areas: 
passageway,  waiting  area,  feeding  area  and  drinking  area.  In  the  feeding  area,  electronic  sow 
feeders (ESF) can be installed. The emitting manure surface is reported to be at a maximum 1.1 
m2 per animal place. In Belgium (Flanders), the total available pen area per sow is reported to 
be  2.5  m2  maximum  [  186,  BE  Flanders  2010  ].  A  tractor-mounted  scraper  is  used  daily  to 
remove the manure from the solid floor area. The litter in the deep straw littered lying area is 
removed only once or twice a year [ 549, IMAG-DLO 1999 ]. Natural or forced ventilation can 
be applied. 

A schematic representation of a solid concrete floor system with straw and electronic feeders is 
shown in Figure 4.42. 

404 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 4 

Source: [ 262, France 2010 ]  

Figure 4.42:  Solid concrete floor system with straw and electronic sow feeders 

Another design of the technique also is applied in naturally ventilated houses for mating sows. 
Separate functional areas are organised: a deep littered activity area, a raised concrete feeding 
area,  and  a  raised  area  with  lockable  insemination  stalls;  feeding  and  drinking  systems  are 
automatic.  Group  sizes  are  reported  to  be  larger  than  40  sows  and  the  space  per  animal  is 
3.75 m2. Solid manure is removed after each rearing period by tractor. Straw is provided each 
week and animals distribute it themselves [ 161, Germany 2010 ]. 

Achieved environmental benefits 
Energy savings are achieved due to natural ventilation. The energy use is very low because this 
system does not usually require forced ventilation or heating.  

The  benefit  of  applying  the  system  with  separate  functional  areas  depends  on  the  animal 
behaviour, which is influenced by the pen design. Ammonia emissions are lowered by reducing 
the emitting manure surface, by steering the defecating behaviour of the sows and, in the cases 
when  a  slatted  floor  is  also  present,  by  altering  the  manure  composition.  This  is  achieved 
through a specific housing design aimed at encouraging the natural behaviour of the sows and 
the application of specific management of manure and straw [ 186, BE Flanders 2010 ]. 

Cross-media effects 
The  system  requires  increased  management  for  handling  of  litter  and  manure  removal.  An 
increase  in  nitrous  oxide  emissions  is  generally  expected  due  to  the  existence  of  aerobic  and 
anaerobic zones in the litter, as well as higher dust emissions; reported nitrous oxide emissions 
vary in the range of 0.03–10 g/day [ 506, TWG ILF BREF 2001 ] [ 261, France 2010 ].  

The effect of straw on methane emissions is controversial; methane emissions may increase due 
to the high dry matter content of manure, but aerobic conditions due to straw do not favour CH4 
production.  

Environmental performance and operational data 
Indicatively,  in  deep  litter  systems,  fresh  bedding  material  is  added  once  a  week,  and  the 
frequency of addition is adjusted according to the cleanliness of the litter and the season. In full 
litter  systems,  ventilation  is  dimensioned  for  a  maximum  output  of  100  m3  per  hour  per  sow 
place.  Although  the  sows  are  capable  of  compensating  for  low  temperatures  by  hiding  in  the 
deep litter mat, auxiliary heating is applied in colder parts of Europe to reduce humidity during 
reduced ventilation. 

Intensive Rearing of Poultry or Pigs 

405 

 
 
 
 
 
 
 
 
 
Chapter 4 

From Germany, the ventilation requirements for the naturally ventilated system for mating sows 
with separate functional areas are reported as at least 16 m3/ap/yr for the cold season and up to 
220 m3/ap/yr for the warm season [ 161, Germany 2010 ]. 

Comparative measurements with fully slatted floor systems and a deep pit for gestating sows in 
Spain  resulted  in  a  reduction  of  ammonia  and  methane  emissions  of  14 %  and  66 %, 
respectively,  and  in  an  increase  of  N2O  emissions  of  178 %,  for  a  properly  managed  littered 
system (two  functional areas with weekly removal of litter) [ 379, Spain 2009 ]. In Germany, 
the emission factor for dust for integrated sow housing systems operating with solid manure is 
five times higher than for those following a slurry technique [ 474, VDI 2011 ]. 

Ammonia emissions of straw-based deep litter housing systems are reported in Table 4.87. 

Table 4.87:  Emissions of mating and gestating sows housed in littered systems 

Housing system 

Deep litter 

NH3 emissions 
kg/ap/yr 
2.5–5.6 
3.7–5.2  
2.6 

PM10  

Odour 

kg/ap/yr  ouE/s/animal 

NI 

NI 

Source 

[ 261,France201] 
[ 43, COM 2003 ] 
[ 186, BE Flanders2010] 

NI 

NI 

4.8 (1)  

Bedded lying area, separate 
defecating area and feeding 
area with electronic sow 
feeders 
Bedded lying area, slatted 
defecating area 
(1) Values derived by expert judgement based on conclusions by analogy.  
(2) Measured data. 
(3) For all stages of breeding sows including piglets up to 25 kg. 
(4)  Value  calculated  from  an  emission  of  22 ouE/s/LU,  and  an  average  weight  of  150 kg  per  for  early-

0.8 (2) (3) 

 0.8 (2) (3) 

4.8 (1) (5) 

6.6 (4) 

6.6 (4) 

[ 161, Germany 2010] 
[ 474, VDI 2011 ] 

[ 157, Germany 2010 ] 
[ 474, VDI 2011 ] 

pregnant or non-pregnant sows.  

(5) Additional emissions are likely due to emitting surfaces in the yard. 
NB: NI = no information provided. 

Trials  in  Belgium  (Wallonia)  on  group-housed  gestating  sows  kept  on  straw  deep  litter  have 
shown  that  feeding  an  ad  libitum  fibrous  diet  increased  NH3  emissions  (3.52 kg  NH3/animal 
place/year)  in  comparison  with  gestating  sows  kept  on  deep  litter  and  offered  a  restricted 
conventional  diet  (1.96 kg  NH3/animal  place/year)  [  230,  Philippe  et  al.  2009  ].  Resource 
requirements,  as  reported  from  Germany  for  two  alternatives  of  the  system,  are  presented  in 
Table 4.88. 

Table 4.88:  Resources demand associated with solid floor housing systems covered with litter for 

mating/gestating sows, in Germany 

System 

Labour 

Energy 

h/ap/yr 

kWh/ap/yr 

Bedding 
material 
kg/ap/yr 

Cleaning 
water 
l/ap/yr 

Source 

2.6 

60 

640 

NI 

[ 161, Germany 
2010 ]  

1.8 (1.5–
2) 

15 

420 (300–
450) 

220 

[ 157, Germany 
2010 ] 

litter 

Deep 
for  group-
housed  mating  sows  with 
separate  functional  areas. 
Natural ventilation 
for  group-
Deep 
litter 
housed  gestating 
sows 
with  a  yard  and  a  slatted 
feeding 
area.  Natural 
ventilation 
NB: NI = no information provided. 

406 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The quantity of straw required daily for gestating sows is 2.4 kg/sow for the deep litter housing 
system  (weekly  straw  input  and  manure  removal  every  2  to  3  weeks,  up  to  1  month)  and 
1.7 kg/sow  for  the  littered-floor  housing  system  (scraping  manure  and  adding  straw  once  or 
twice a week) [ 262, France 2010 ]. 

Technical considerations relevant to applicability 
Limitations  for  applying  the  technique  were  reported  only  for  the  electronic  sow  feeders  in 
existing houses, for which the applicability depends on the design of the existing manure pits. 
The system may not be applicable to naturally ventilated plants located in warm climates. 

Economics 
Extra costs, as reported from Spain, in comparison with fully slatted floor systems, are shown in 
Table 4.89. 

Table 4.89:  Extra  costs  for  the  implementation  of  straw-littered  solid  floors  with  weekly 

replacement of bedding, in Spain 

Production 

Type of house 

Gestating 
sows 
Source: [ 379, Spain 2006 ] 

New houses 
Existing houses 

Extra costs 

EUR/ap/yr 

72.71–80.45 
47.61–55.35 

EUR/tonne pig 
produced 
27.3–30.2 
17.9–20.8 

Driving force for implementation 
This system favours group housing. The technique improves animal welfare conditions as sows 
benefit from the group life, the comfortable lying area, the improved indoor conditions due to 
natural  ventilation  and 
is  a  good 
occupational/investigation material for the animals. 

large  space  available  for  movement.  Straw 

the 

Example plants 
This system can be found in several Member States. In the Netherlands, more than 50 % of new 
buildings apply this system, and it is also implemented in retrofitted existing houses. In Belgium 
(Flanders), 27 farms have received authorisation for the system [ 300, BE Flanders 2010 ]. 

Reference literature 
[ 43, COM 2003 ]  [ 157, Germany 2010 ] [ 161, Germany 2010 ] [ 186, BE Flanders 2010 ] 
[ 230, Philippe et al. 2009 ] [ 261, France 2010 ] [ 262, France 2010 ] [ 300, BE Flanders 2010 ] 
[ 379, Spain 2009 ] [ 397, Denmark 2000 ] [ 412, Italy 2001 ] [ 474, VDI 2011 ] [ 506, TWG 
ILF BREF 2001 ] [ 549, IMAG-DLO 1999 ] 

4.7.2.11 

Feeding/lying boxes on a solid floor (in case of litter-based pens) 

Description  
Sows are housed in pens of 6 to 12 animals. Each pen is divided into two functional areas: the 
feeding/lying  cubicles  and  the  littered  (straw)  activity  area.  One  cubicle  with  a  solid  floor  is 
provided for each sow. The cubicles are 0.50 m to 0.65 me wide and the length of the solid floor 
of the cubicle is at least 1.55 m (see Figure 4.43). 

At the beginning of each production cycle, the bedding area is littered with 30–40 cm of straw 
and, in any case, a sufficient quantity to ensure that the difference in height between the bedding 
area and the cubicle level is no more than 10 cm. 

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Chapter 4 

Source: [ 435, Van Gansbeke et al. 2011 ] 

Figure 4.43:  Scheme of the floor levels in litter-based pens with feeding/lying boxes 

The bedded area is situated behind the feeding/lying cubicle at 0.30 m to 0.40 m below the floor 
level; a minimum littered surface of 1.5 m2 is provided for each animal place. 

Achieved environmental benefits 
Lower  ammonia  emissions  are  achieved  by  keeping  the  bedding  clean  and  dry,  with  regular 
supply and replacement of the straw. 

Cross-media effects 
It  is  generally  considered  that  inefficient  management  of  the  bedding  may  lead  to  increased 
greenhouse gas emissions. 

Environmental performance and operational data 
Topping up of straw is done at least three times a week, so that no wet manure spots emerge in 
the  bedding  area.  The  bedding  material  is  replaced  every  5  weeks  or  when  it  reaches  the 
maximum height of 50 cm. The total consumption of straw is estimated at around 2 kg per sow 
per day. A reported ammonia emissions factor for this housing system is  1 kg NH3 per animal 
place per year (indicative measurements) [ 186, BE Flanders 2010 ]. 

Technical considerations relevant to applicability 
The system can be applied in all new housing. It is not applicable to existing buildings without 
solid concrete floors. 

Economics 
No information provided. 

Driving force for implementation 
Compliance with Directive 2008/120/EC.  

Example plants 
In Belgium (Flanders), the system is applied in 18 farms (including farms above and below the 
capacity threshold set by Directive 2010/75/EU, Annex I). 

Reference literature 
[ 435, Van Gansbeke et al. 2011 ] 

408 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.7.3 

Housing systems for farrowing sows  

In  Europe,  farrowing  sows  are  generally  housed  in  individual  farrowing  crates  with  metal, 
concrete or plastic slatted floors and a deep pit or channel underneath. In farrowing crates, sows 
are confined with restricted movement to prevent them lying on the piglets while the piglets are 
free  to  walk  around.  All  houses  have  controlled  ventilation  and  often  a  heated  area  for  the 
piglets during their first few days after birth (see also Section 2.3.1.2.1). 

The difference between fully and partly slatted floors is not as distinct for farrowing sows as it 
is for other pig categories because the sow is confined and excretion generally takes place in the 
same  slatted  area.  Reduction  techniques  therefore  focus  on  alterations  in  the  manure  pit  
[ 508, TFRN 2014 ].  

Other  housing  systems  allow  free  movement  of the sow  in  individual  pens  with  partly  slatted 
floors to collect slurry and separate lying areas with a solid floor for the sow and the piglets (see 
Section  4.7.3.9).  Farrowing  sows  are  also  kept  in  group  pens  on  a  solid  concrete  floor  with 
plenty of litter. In this system solid manure is generated. No specific data are provided for such 
housing systems. 

General  information  on  techniques  using  one  or  a  combination  of  measures  for  reducing 
ammonia  emissions  which  apply  to  other  pig  categories  as  well  is  given  in  Section 4.7.1 and, 
thus, is not repeated in the following sections.  

The  reported  ammonia  emissions  for  techniques  that  are  used  to  rear  farrowing  sows  are 
summarised  in  Table 4.90.  Data  concerning  emissions  of  dust  and  odour  are  also  presented, 
when available. 

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Table 4.90:  Emission levels of system-integrated housing techniques for farrowing sows 

Section 
number 

Housing system 

Deep pit (in case of a fully 
slatted floor) 

4.7.3.1 

4.7.3.1.1 

4.7.3.2 

4.7.3.3 

4.7.3.4 

4.7.3.5 

4.7.3.6 

4.7.3.7 

4.7.3.8 

4.7.3.9 

system 

Deep pit (in case of a partly 
slatted 
(slurry 
floor) 
removal once a month) 
Deep pit (in case of a partly 
slatted  floor)  (removal  by 
vacuum system) 
Reduced  manure  pit  (in 
case  of  a  partly  slatted 
floor) 
Vacuum 
for 
frequent  slurry  removal  (in 
case  of  a  fully  or  partly 
slatted floor) 
Slanted walls in the manure 
channel  (in  case  of  a  fully 
or partly slatted floor) 
Scraper  for  frequent  slurry 
removal (in case of a partly 
or fully slatted floor) 
Frequent slurry removal by 
flushing  (in  case  of  a  fully 
or partly slatted floor) 
Slurry cooling (FSF or PSF 
with  slurry  surface  cooling 
fins) 
A  combination  of  water 
and  manure  channels  (in 
case of a fully slatted floor) 
Manure pan (in case of a 
fully or partly slatted floor) 
Littered 
with 
combined 
manure 
generation 

pens 

NH3 

PM10 

kg/ap/yr 

Odour 
ouE/s/animal 

8.3–8.7 

8.3 

NI 

84.4 (1) 

9.0 (2) 

Source 

 [ 43, COM 2003 ] 
[ 508, TFRN 2014 ]  
[ 634, BE Flanders 2013 ] 
[ 261, France 2010 ] 

8.6 (2) 

NI 

NI 

[ 159, Austria 2010 ] 

8.3 (2) 

0.16 

8.0 (3) 

[ 171, Germany 2010 ] 
[ 474, VDI 2011 ] 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

3.2  

NI 

NI 

[ 186, BE Flanders 2010 ] 

4–5.65 

NI 

3.3 

NI 

2.4 

4 

2.9  

2.9  

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

8.3 (2) 

0.16 

8.0 (3) 

 [ 43, COM 2003 ] 

 [ 43, COM 2003 ] 

 [ 43, COM 2003 ] 

 [ 43, COM 2003 ] 

[ 640, Netherlands 2013 ]  

[ 186, BE Flanders 2010 ] 
 [ 43, COM 2003 ] 

[ 172, Germany 2010 ] 
[ 474, VDI 2011 ] 

(1) Measured data. 
(2) Values derived by expert judgement based on conclusions by analogy. 
(3) Values calculated from an odour emission of 20 ouE/s per LU, and animal mass= 0.4 LU. 
NB: NI = no information provided.  

410 

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Chapter 4 

4.7.3.1 

Deep pit (in case of a fully or partly slatted floor) 

Description  
In a forced ventilated building that is closed and insulated, individual slatted farrowing pens are 
equipped  with  crates.  The  floor  in  the  farrowing  crate  can  be  fully  or  partly  slatted.  In  fully 
slatted floors, a combination of different materials can be used for slats, e.g. plastic floors can be 
used for the comfort of suckling piglets. In the case of partly slatted floors, piglets are provided 
with a level concrete and heated nest. Slurry from the deep pit or slurry channel is removed once 
or twice a farrowing cycle. A scheme of the system is presented in Figure 4.44 and Figure 2.15. 

Source: [ 171, Germany 2010 ] 

Figure 4.44:  Farrowing crate with a partly slatted floor (solid floor in the lying areas)  

The  UK  reported  a  variation  of  the  standard  farrowing  crate  (the  'Nooyen  system'),  which 
consists of a lifting farrowing crate with a movable flooring arrangement. Operated by air, the 
pen floor on both sides of the sow rises and falls depending on the sow’s position. In particular, 
as soon as the sow lies down, the sow's floor will drop to the level of the piglet floor allowing 
piglets to suckle, and when the sows gets up again, the sow's floor will rise to a safe height; in 
this way the number of smothered and crushed piglets is reduced. The system design also aims 
to  improve  the  ventilation  and  feeding  management.  The  forced  ventilation  in  an  insulated 
building is controlled with real-time monitoring, with the air inlet next to the sow’s snout, with 
cooling pipes installed under the sow and an air cooling system with a heat exchanger in place. 
The solid part of the floor can raise its temperature by 5 °C. Slurry is removed with a vacuum 
system (every 2 to 4 weeks). Suckling piglets do not have access to a nest. Feeding is controlled 
automatically [ 174, UK 2010 ] [ 494, EFSA 2007 ]. 

Achieved environmental benefits 
With an improved ventilation design, fuel savings are reported, and a consequent reduction of 
indirect  emissions  from  fossil  fuel  combustion.  Ammonia  emissions  can  be  reduced  if  the 
technique is combined with other mitigation measures such as pH reduction of the slurry, slurry 
cooling, etc. 

Cross-media effects 
Housing  of  sows  in  farrowing  crates  severely  restricts  their  freedom  of  movement  which 
increases  the  risk  of  frustration  [  494,  EFSA  2007  ].  It  is  anticipated  that  future  consumer 
standards  will  not  favour  techniques  that  limit  farrowing  sows'  freedom  of  movement,  due  to 
animal welfare considerations. Fixation of sows is not allowed in Sweden. 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Nesting material is lacking in existing systems with fully slatted floors when the slurry system is 
not built for use of such nesting  material; however, it is possible to use fully slatted floors in 
newly built farrowing systems in accordance with the provisions of Directive 2008/120/EC for 
the supply of suitable nesting material [ 494, EFSA 2007 ]. 

Environmental performance and operational data 
Ammonia  emissions  from  farrowing  crates  with  fully  slatted  floors  are  reported  to  range 
between 8.3 kg and 9.0 kg NH3/ap/yr [ 261, France 2010 ] [ 508, TFRN 2014 ]. From Belgium 
(Flanders), odour emissions are reported to be 84 ouE/s/sow [ 634, BE Flanders 2013 ]. 

From Austria, an emission for NH3 of 8.6 kg/ap/yr is reported, associated with a deep pit under 
a  partly  slatted  floor  (one  third  slatted  and  2.05 m2  per  animal  place)  with  a  slurry  removal 
frequency of once a month [ 159, Austria 2010 ].  

In Germany, emissions for forced ventilated housing with partly slatted floors (solid lying areas 
for the  sow and  the  piglets)  are  reported  as  8.3/ap/yr for  NH3,  0.16 kg/ap/yr  for PM10  (for  all 
stages of breeding sows including piglets up to 25 kg) and 8 ouE/s/sow for odour (value derived 
from the reported emission factor of 20 ouE/s/LU, for an average weight of sow with the piglets 
of  200 kg)  [  474,  VDI  2011  ].  Ventilation  rates  of  22–27 m3  per  animal  per  hour  in  the  cold 
season  and  125–127 m3  per  animal  per  hour  in  the  warm  season  are  applied.  Demand  for 
resources is specified per animal place per year as 60 kWh for electricity, 850 litres of cleaning 
water,  680 kWh  for  piglet  nest  heating  and  180 kWh  for  room  heating.  Labour  needs  are 
estimated at 3.9 hours per animal place per year [ 171, Germany 2010 ]. 

For  the  housing  system  with  the  lifting  farrowing  crate,  a  higher  weaning  weight  of  1 kg  is 
reported because of a higher feed intake. In addition, fuel savings of 40 % are reported for the 
system [ 174, UK 2010 ]. 

Technical considerations relevant to applicability 
No information provided. 

Economics 
Costs for newly built houses are reported to be between EUR 2 800 and EUR 2 900 per animal 
place,  from  Germany  for  180  farrowing  pens,  and  are  calculated  as  being  equivalent  to 
EUR 2 877 per animal place in Belgium (Flanders) for a new farm with 95 farrowing pens [ 265, 
BE Flanders 2005 ]. For the housing system with the lifting farrowing crate, an increase in cost 
of at least 35 % is reported from the UK [ 174, UK 2010 ]. 

Driving force for implementation 
Piglet mortality due to crushing has been reported to be lower in farrowing crates than in loose-
housing  systems,  even  though  the  primary  cause  of  piglet  mortality  is  often  unknown  
[  494,  EFSA  2007  ].  The  housing  system  offers  production  and  technological  advantages  
[  171,  Germany  2010  ].  For  the  housing  system  with  the  lifting  farrowing  crate  and  better 
control  of  ventilation  and  feeding  management,  pig  health  is  improved  and  an  increased 
weaning weight and lower mortality are achieved.  

Example plants 
This housing system technique is commonly applied system in Member States.  

Reference literature 
[ 159, Austria 2010 ] [ 171, Germany 2010 ] [ 174, UK 2010 ] [ 261, France 2010 ] [ 265, BE 
Flanders 2005 ] [ 474, VDI 2011 ] [ 494, EFSA 2007 ] [ 508, TFRN 2014 ] [ 634, BE Flanders 
2013 ] 

412 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.7.3.1.1 

Reduced manure pit (in case of a partly slatted floor) 

Description 
Sows  are  individually  housed  in  farrowing  crates  in  systems  with  partly  slatted  floors  with  a 
narrow, shallow slurry pit. The design of this system is comparable with the design of the basic 
system (see Section 4.7.3.1) Slurry is often drained by means of discharge pipes, in which the 
individual sections of the manure channels are emptied via plugs. The manure channels can also 
be drained by means of gates. The channels are cleaned after each farrowing when the farrowing 
crates  are  disinfected,  i.e.  at  intervals  of  about  4  to  5  weeks.  Some  manual  cleaning  is 
sometimes necessary.  

This housing system is fitted with mechanical ventilation either in the form of negative pressure 
or  balanced  pressure  plants.  Ventilation  is  dimensioned  for  a  maximum  output  of  250  m3  per 
hour per farrowing crate [ 397, Denmark 2000 ]. Ventilation can also be natural (ACNV with 
fan assistance in hot weather). In this case, zone heating is applied with heating elements in the 
floor or ceiling [ 173, UK 2010 ].  

Achieved environmental benefits 
A reduction of NH3 emission is expected due to the reduction of the emitting slurry surface area. 
From Denmark, it is reported that systems for farrowing sows with partly slatted floors and a 
reduced  manure  pit  have  about  half  the  emissions  of  systems  with  fully  slatted  floors  [  500, 
IRPP TWG 2011 ]. In  ILF BREF, an ammonia reduction efficiency of 34 %  was reported for 
the technique [ 43, COM 2003 ].  

Cross-media effects 
See Section 4.7.3.1.  

Environmental performance and operational data 
No information provided.  

Technical considerations relevant to applicability 
It is assumed that in existing houses the applicability will depend on the design of the existing 
manure pit, but that it is generally difficult, if not impossible, to apply. 

Economics 
In  the  UK,  the  investment  cost  for  a  new  farm  with  ACNV  for  farrowing  sows  is  around 
EUR 2 500 per farrowing crate, including building costs but not labour [ 173, UK 2010 ]. 

Driving force for implementation 
See  Section  4.7.3.1  for  farrowing  crates.  The  solid  floor  offers  benefits  in  terms  of  animal 
welfare.  For  the  system  design  with  natural  ventilation  a  better  pig  health,  higher  weaning 
weights and lower mortality is reported by the UK. 

Example plants 
This technique is widely practised in Denmark. The design with natural ventilation is common 
in the UK. 

Reference literature 
[ 43, COM 2003 ] [ 173, UK 2010 ] [ 397, Denmark 2000 ] [ 500, IRPP TWG 2011 ] 

Intensive Rearing of Poultry or Pigs 

413 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.7.3.2 

Vacuum system for frequent slurry removal (in case of a fully or 
partly slatted floor) 

See Section 4.7.1.2 and Section 4.7.3.1 for farrowing crates. 

4.7.3.3 

Slanted walls in the manure channel (in case of a fully or partly 
slatted floor) 

Description 
Slurry is collected in a manure channel which has two sloped side walls in order to reduce the 
emitting surface; the back side wall has a slope of 60 ° and the front side wall a slope of 45 ° in 
relation to the bottom of the manure channel. Slurry is removed from the housing every 2 days 
by  means  of  a  discharge  system.  See  also  Section  4.7.1.4  and  Section  4.7.3.1  for  farrowing 
crates. 

At the bottom of the manure channel there are discharge openings (at a maximum distance of 
two metres). Slurry is discharged before the slurry level reaches a height of 10 cm. To guarantee 
this  height,  an  overflow  is  provided  in  the  manure  channel.  A  layer  of  slurry  of  2 cm  always 
remains in the channel to avoid manure sticking to it.  

Achieved environmental benefits 
See Section 4.7.1.4. 

Cross-media effects 
See Section 4.7.1.4 and Section 4.7.3.1. 

Environmental performance and operational data 
Associated ammonia emissions with the technique are reported as 3.2 kg NH3/ap/yr [ 186, BE 
Flanders 2010 ].  

Technical considerations relevant to applicability 
In existing houses, the applicability depends on the dimensions of the existing manure pit. 

Economics 
No information provided.  

Driving force for implementation 
No information provided. See Section 4.7.3.1 for farrowing crates. 

Example plants 
The technique is used in Belgium (Flanders) as a low-NH3 emission housing system.  

Reference literature 
[ 186, BE Flanders 2010 ] 

4.7.3.4 

Scraper for frequent slurry removal (in case of a fully or partly 
slatted floor) 

Description 
See Section 4.7.1.5 and Figure 4.45. Also, see Section 4.7.3.1 for farrowing crates. 

414 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 42, Netherlands 1999 ] 

Figure 4.45:  Farrowing crate with a manure scraper (in case of a partly slatted floor) 

Achieved environmental benefits 
See  Section  4.7.1.5.  A  reduction  in  NH3  emissions  is  achieved  by  reducing  the slurry  surface 
and by the frequent scraping of slurry and draining of the urine.  

Cross-media effects 
The  power  consumption  of  scraping  varies  with  the  frequency,  with  it  being  reported  as 
2.4 kWh (Italy) and 3.5 kWh (Netherlands) per sow per year. See also Section 4.7.1.5 for cross-
media effects related to farrowing crates; for fully slatted floors, see Section 4.7.3.1. 

Environmental performance and operational data 
Ammonia emissions for the partly slatted design are 35 % (5.65 kg NH3 per sow place per year 
(Italy)) to 52 % (4.0 kg NH3 per sow place per year (Netherlands and Belgium)).  

Technical considerations relevant to applicability 
See Section 4.7.1.5. 

Economics 
No information provided. 

Driving force for implementation 
See Section 4.7.1.5 and Section 4.7.3.1 for farrowing crates. 

Example plants 
A few in the Netherlands although it is no longer applied in new buildings. Scrapers in France 
are only associated with fully slatted floors [ 261, France 2010 ]. 

Reference literature 
[ 42, Netherlands 1999 ] [ 261, France 2010 ] [ 391, Italy 1999 ] [ 412, Italy 2001 ]  

4.7.3.5 

Frequent slurry removal by flushing (in case of a fully or partly 
slatted floor) 

Description 
See  Section  4.7.1.9  and  to  Section  4.7.3.1  (farrowing  crates).  Application  is  possible  in  pens 
with a partly or fully slatted floor.  

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Source: [ 42, Netherlands 1999 ] 

Figure 4.46:  Flushing system with a manure gutter  

Achieved environmental benefits 
See Section 4.7.1.9. 

Cross-media effects 
See Section 4.7.1.9. For cross-media effects related to farrowing crates and fully slatted floors, 
see Section 4.7.3.1. 

Environmental performance and operational data 
Reducing the manure surface in the manure channel, in combination with the fast discharge of 
the  manure  from  the  slatted  area  by  using  triangular  plastic  or  iron  bars,  and  removal  of  the 
manure twice a day by flushing reduce NH3 emissions by 60 % (3.3 kg NH3 per sow place per 
year  (Netherlands  and  Belgium)).  However,  data  for  other  pig  categories  (fattening  pigs  and 
mating/gestating sows) suggest a 40 % emission reduction with the flushing gutters  technique 
[ 508, TFRN 2014 ]. This system has an extra energy consumption of 8.5 kWh per sow place 
per year, relative to the flushing of the gutters. 

Technical considerations relevant to applicability 
See Section 4.7.1.9. 
Economics 
No information provided. 

Driving force for implementation 
See Section 4.7.1.9. 

Example plants 
See Section 4.7.1.9.  

Reference literature 
[ 42, Netherlands 1999 ] [ 508, TFRN 2014 ] 

4.7.3.6 

Slurry cooling 

Description 
Slurry cooling channels or slurry surface cooling fins can be used. See Section 4.7.1.7 for slurry 
cooling channels and Section 4.7.1.8 for slurry surface cooling fins. 

Achieved environmental benefits 
See Section 4.7.1.7 and Section 4.7.1.8. 

416 

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Cross-media effects 
See Section 4.7.1.7 and Section 4.7.1.8. 

Chapter 4 

Environmental performance and operational data 
The  ammonia  emission  factor  associated  with  the  surface  cooling  fins  technique  in  the 
Netherlands  is  2.4  kg  NH3/ap/yr  which  corresponds  to  a  70 %  ammonia  emission  reduction 
efficiency 
source  
surface/slurry 
[ 508, TFRN 2014 ], the reduction achieved for the technique for farrowing sows is reported to 
be  45  %. The  extra  energy  consumption  is  estimated as  73 kWh  per  farrowing  sow  place  per 
year for surface cooling fins [ 589, Netherlands 2010 ]. No information is  provided for slurry 
cooling channels. 

surface).  From 

another 

cooling 

(150 % 

fins' 

Technical considerations relevant to applicability 
See Section 4.7.1.7 and Section 4.7.1.8. 

Economics 
The  extra  investment  costs  for  implementation  of  surface  cooling  fins  in  comparison  with 
farrowing  pens  with  fully  slatted  floors  and  4.5  m2  per  pen  are  calculated  as  EUR  240  per 
animal place and the extra annual costs as EUR 40 per animal place (See Table 4.78). An extra 
cost of EUR 45 per animal place per year for new buildings and a cost efficiency of EUR 15 per 
kg of NH3-N reduced are reported [ 508, TFRN 2014 ]. No information is provided for slurry 
cooling channels. 

Driving force for implementation 
See Section 4.7.1.7 and Section 4.7.1.8. 

Example plants 
See Section 4.7.1.7 and Section 4.7.1.8. 

Reference literature 
See Section 4.7.1.7 and Section 4.7.1.8. 

4.7.3.7 

A combination of water and manure channels (in case of a fully 
slatted floor) 

Description 
The sow has a fixed place and as a result the defecating area is clearly identified. The manure 
pit is split up into a wide water channel at the front and a small manure channel at the back (see 
Figure 4.47  and  Figure 4.48)  with  a  reduced  emitting  slurry  surface.  In  this  way,  the  manure 
surface is greatly reduced, which in turn reduces ammonia emissions. The front channel is partly 
filled with water. The slats are made of metal or plastic. 

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417 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 42, Netherlands 1999 ] 

Figure 4.47:  Combination of water and manure channels  

Source: [ 265, BE Flanders 2010 ] 

Figure 4.48:  Shallow slurry pits separating manure and water channels during construction 

Achieved environmental benefits 
The  achieved  environmental  benefit  is  the  reduced  ammonia  emission  due  to  the  limited 
emitting manure surface and frequent slurry removal by a discharge system.  

Cross-media effects 
See  Section  4.7.3.1  for  farrowing  crates  and  fully  slatted  floors.  The  frequent  removal  of  the 
slurry may require extra energy. Water is needed to fill the front pit. 

Environmental performance and operational data 
An  emission  level  of  4.0 kg  NH3  per  sow  place  per  year  (Netherlands  and  Belgium)  can  be 
achieved,  which  is  more  than  50 %  lower,  in  comparison  with  the  typical  emission  levels  of 
8.3–8.6 kg NH3 per sow place per year reported for a crate housing system with a partly slatted 
floor with a deep pit. A 50 % ammonia emission reduction is reported for the technique [ 508, 
TFRN  2014 ].  In  the  Netherlands,  the  emission  factor  associated  with  the  technique  is  2.9 kg 
NH3 per place per year [ 640, Netherlands 2013 ].  

418 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

Supposedly  the  two pits are  emptied  into the same  slurry  sewerage  system  towards  the  slurry 
store.  Water  is  changed  after  each  cycle  (approximately  every  4  weeks).  The  front  section  is 
drained completely, cleaned, disinfected and then filled up again with fresh water. 

Technical considerations relevant to applicability 
For retrofitting this system into existing buildings equipped with fully slatted floors, the design 
of the pen is not critical in itself but the implementation depends on the conditions of the pit. 
Openings to  a  discharge  system  (e.g.  tubing) are  required to  be  placed  underneath each  crate. 
This  means  that  the  entire  existing  manure  pit  has  to  be  removed  and  rebuilt  in  order  to 
construct  the  discharge  system  and  the  openings.  Proper  support  has  to  be  considered  when 
digging operations need to be performed near the load-bearing walls.  

In  cases  where  the  existing  house  has  crates  with  partly  slatted  floors,  new  crates  have  to  be 
installed  as  the  existing  crates (fixed  on  the  previous  portion  of  solid  floor)  can  no  longer  be 
used. 

Economics 
Investment cost data for a fully slatted floor housing system with water and manure channels in 
the slurry pit, as reported from Belgium (Flanders), are presented in the Table 4.91. Calculations 
are based on a compartment with 95 farrowing pens. Investment costs are 15 % higher than for a 
system  with  a  fully  slatted  floor  and  a  deep  pit;  extra  investment  costs  are  equivalent  to 
EUR 433 per farrowing pen in new farms. Included in this extra cost is the cost of an additional 
storage volume consisting of a concrete storage tank of 300 m3, to compensate for the reduced 
slurry storage volume underneath the slats. Without the additional storage, the extra costs would 
be equivalent to EUR 316 per farrowing place. 

Table 4.91:  Investment  costs  reported  for  a  fully  slatted  floor  housing  system  with  water  and 

manure channels, in comparison with a fully slatted floor system with a deep pit 

Parameter 

Deep pit (conventional system) 
Water and manure channels 
Extra cost  
Source: [ 265, BE Flanders 2010 ] 

Building costs  Additional costs 

Total 

EUR/sow place 

1 354 
1 354 
0 

1 523 
1 956 
433 

2 877 
3 310 
433 

From Belgium (Flanders), cost data for the retrofitting of the technique in existing houses are 
also reported which amount to EUR 2434 per sow place for fully slatted floors and EUR 4 565 
per sow place for partly slatted floors [ 274, BE Flanders 2010 ]. 

Extra costs for the implementation of the technique, in comparison to crates with fully slatted 
floors  with  a  deep  pit,  are  reported  from  Spain  and  the  cost  efficiency  is  calculated  for  the 
measured ammonia abatement. Figures are given in Table 4.92.  

Table 4.92:  Extra  costs  for  installing  in  FSF  a  combination  of  water  and  manure  channels 

compared to a deep pit 

Housing  

Ammonia 
emissions reduction  

Extra costs 

% 

EUR/ap/yr 

Retrofitted existing house 
New house 
(1) The pig meat produced is calculated on the basis of 8 000 kg of yearly production per farrowing sow place. 
Source: [ 379, Spain 2009 ] [ 338, Piñeiro et al. 2009 ] 

16.74–20.09 
3.29–3.95 

52 

EUR/tonne pig 
produced (1) 
2.1–2.5 
0.4–0.5 

EUR/kg NH3 
reduced 
8.63–10.36 
1.70–2.04 

Intensive Rearing of Poultry or Pigs 

419 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

An  extra  cost  of  EUR  2  per  animal  place  per  year  for  new  buildings  and  a  cost  efficiency  of 
EUR 0.5 per kg of NH3-N reduced are reported [ 508, TFRN 2014 ].  

Driving force for implementation 
See  Section  4.7.3.1  for  farrowing  crates.  The  technique  is  relatively  easy  to  implement  in 
existing buildings. 

Example plants 
In  Belgium  (Flanders),  157  farms  are  equipped  with  this  system  (including  farms  above  and 
below  the  capacity  threshold  set  by  Directive  2010/75/EU)  [  300,  BE  Flanders 2010  ].  In  the 
province of North Brabant in the Netherlands, 126 farms with farrowing sows are equipped with 
the system. 

Reference literature 
[ 22, Bodemkundige Dienst 1999 ] [ 42, Netherlands 1999 ] [ 265, BE Flanders 2005 ] [ 274, BE 
Flanders 2010 ] [ 300, BE Flanders 2010 ] [ 338, Piñeiro et al. 2009 ] [ 379, Spain 2009 ] [ 500, 
IRPP TWG 2011 ] [ 508, TFRN 2014 ] [ 640, Netherlands 2013 ] 

4.7.3.8 

Manure pan (in case of a fully or partly slatted floor) 

Description 
A prefabricated container (pan) is placed under the slatted floor to collect slurry. Its dimensions 
have  to  encompass  the  entire  slatted  area  (see  Figure 4.49).  The  manure  pan  consists  of  a 
shallow recipient with a slope of at least 3 ° and slurry drainage at the lowest point towards a 
central slurry channel connected to a sewerage system. The slurry is discharged before its level 
reaches 12 cm. A reachable and clearly visible overflow drain assures the level is maintained. 
The pan can be subdivided into a water channel and a manure channel. Manure pans are made 
of smooth, corrosion-resistant, nonadhesive (to manure) and easy-to-clean material. A farrowing 
crate is combined with this system. 

Source: [ 42, Netherlands 1999 ] 

Figure 4.49:  A manure pan (in case of fully slatted floor) 

The inner diameter of the discharge openings should be at least 90 mm and the diameter of the 
discharge tube should be at least 110 mm. Where a dedicated water channel is in place, the level 
of the water needs to be maintained at at least 5 cm at all times. In addition, at the end of each 
production cycle the water and manure channels have to be discharged, after which the crate can 
be cleaned. 

Achieved environmental benefits 
Ammonia  emissions  are  lowered  by  reducing  the  emitting  manure  surface  to  a  maximum  of 
0.8 m2  per  animal  place  and  by  providing  a  manure  pan  with  water  and  manure  channels 

420 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

underneath the crate. Frequent removal of the slurry by a sewerage system also contributes to a 
reduction of ammonia emissions. Overall, a reduction of 65 % in NH3 emissions is achieved, in 
comparison  with  the  emission  of  8.3 kg  NH3/ap/yr  associated  with  the  technique  of  crate 
housing  with  a  slatted  floor  and  a  deep  pit.  An  ammonia  emission  reduction  of  65  %  for  the 
technique  is  also  reported  by  the  UNECE  guidance  document  for  ammonia  mitigation  
[ 508, TFRN 2014 ]. 

Cross-media effects 
See  Section  4.7.3.1  for  farrowing  crates  and  fully  slatted  floors.  This  technique  typically  has 
problems with flies. 

Environmental performance and operational data 
Emissions  of  2.9 kg  NH3  per  sow  place  per  year  were  reported  from  the  Netherlands  and 
Belgium  (Flanders).  From  trials  carried  out  in  Spain,  the  measured  ammonia  emissions 
reduction is reported to be 32 % compared to control pens with fully slatted floors with a deep 
pit.  Ventilation  requirements  have  been  reported  from  Spain  as  325  m3/h/ap  for  the  warm 
season, with a maximum of 465 m3/h/ap. 

Technical considerations relevant to applicability 
The  application  does  not  depend  on  the  pen  design  (e.g.  crates  placed  either  straight  or 
diagonally) or on whether it is with a fully or a partly slatted floor. Although this system is easy 
to implement in retrofits of existing buildings, as well as in new buildings, in practice it may be 
costly to alter the slurry drainage system [ 508, TFRN 2014 ]. 

Economics  
The  extra  costs  have  been  calculated  in  Spain  and  are  stated  in  Table 4.93.  A  comparison  is 
made  between  fully  slatted  floors  pens  with  a  manure  pan  and  control  pens  with  fully  slatted 
floors with a deep pit. The cost efficiency is also reported for a measured ammonia abatement of 
32 %.  

Table 4.93:  Extra costs for installing in a FSF a manure pan in comparison to a deep pit, in Spain 

Housing 

Ammonia emissions 
reduction  

% 

EUR/ap/yr 

New house 
17.52–21.02 
30.98–37.18 
Retrofitting existing house 
Source: [ 170, Spain 2007 ] [ 379, Spain 2009 ] [ 338, Piñeiro et al. 2009 ] 

32 

Extra costs 

EUR/tonne 
pig produced 
2.2–2.6 
3.9–4.6 

EUR/kg NH3 
abated 
14.7–17.62 
26–31.23 

In  the  Netherlands,  the  reported  extra  investment  costs  compared  to  the  standard  system  are 
EUR 270  per  animal  place,  and  the  annual  costs  are  equivalent  to  EUR 40/ap/yr  (including 
depreciation, interest, maintenance and all other operating costs, such as energy). In the case of 
a manure pan with water and manure channels, extra investment costs are reported as EUR 295 
per animal place, and annual costs as EUR 40/ap/yr [ 589, Netherlands 2010 ]. 

An extra cost of EUR 40 to 45 per animal place per year for new buildings and a cost efficiency 
of EUR 9 per kg of NH3-N reduced are reported [ 508, TFRN 2014 ]. 

Driving force for implementation 
See  Section  4.7.3.1  for  farrowing  crates.  The  technique  is  relatively  easy  to  implement  in 
existing buildings. 

Intensive Rearing of Poultry or Pigs 

421 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Example plants 
In  the  Netherlands  this  system  has  been  implemented  in  many  retrofits,  as  well  as  in  new 
buildings. In the province of North Brabant alone, 126 farms with farrowing sows are equipped 
with this system.  

Reference literature 
[  42,  Netherlands  1999  ]  [  170,  Spain  2007  ]  [  186,  BE  Flanders  2010  ]  [  338,  Piñeiro  et  al. 
2009 ] [ 379, Spain 2009 ] [ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] 

4.7.3.9 

Littered pens with combined manure generation (slurry and solid 
manure)  

Description 
Farrowing  pens  are  equipped  with  separate  functional  areas:  the  lying  area  is  bedded,  the 
walking and defecating dung areas have slatted or perforated floors and the feeding area is on a 
solid floor. Piglets are provided with a littered and covered nest. Slurry is frequently (e.g. daily) 
removed  under  the  slatted  floor  with  a  scraper.  Solid  manure  is  manually  removed  from  the 
solid floor areas on a daily basis. Litter is provided regularly. A yard can be combined with the 
system. 

A  schematic representation  of a  housing  system  with littered  pens  with  a  yard  is  presented  in 
Figure 4.50. 

Source: [ 172, Germany 2010 ] 

Figure 4.50:  Littered farrowing pens with a yard 

Achieved environmental benefits 
No difference is reported in comparison to the commonly applied system with farrowing crates 
and a deep pit. 

Cross-media effects 
The system implies an increased risk of death for piglets especially in the first few hours after 
farrowing [ 624, IRPP TWG 2013 ]. Increased management requirements (e.g. frequent littering 
and regular cleaning of the yard). Additional emissions are likely due to emitting surfaces in the 
yard. 

Environmental performance and operational data 
In Germany, emissions are assumed to be 8.3 kg ammonia per animal place per year, 0.16 kg 
PM10  dust  per  animal  place  per  year  (for  all  stages  of  breeding  sows  including  piglets  up  to 
25 kg) and 8 ouE/s per sow (value derived from the reported emission factor of 20 ouE/s/LU and 

422 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

an average weight of a sow with piglets of 200 kg) [ 474, VDI 2011 ]. Ventilation is applied at 
rates of 22–27 m3/h/animal in the cold season and 125–187 m3 h/animal in the warm season. It 
is necessary to provide around 180 kg of bedding each year to the 7 m2 of space per sow. 

Technical considerations relevant to applicability 
When retrofitting, applicability depends on the specific design of the existing pen. 

Economics 
The technique entails additional labour costs for daily mucking out, as well as the extra cost of 
the increased straw usage. 

Driving force for implementation 
The bedded housing improves animal welfare. A yard is mandatory in organic farming.  

Example plants 
This system is the standard for organic farming in Germany. 

Reference literature 
[ 172, Germany 2010 ] [ 474, VDI 2011 ] [ 624, IRPP TWG 2013 ] 

4.7.4 

Housing systems for weaners  

Emissions  associated  with  the  techniques  related  to  the  rearing  of  weaners  (also  known  as 
weaned piglets) are summarised in Table 4.94. Data concerning emissions of methane, nitrous 
oxide, dust and odour are also presented, when available. 

Intensive Rearing of Poultry or Pigs 

423 

 
 
 
 
 
 
 
 
 
 
 
CH4 

PM10 

Odour 

kg/ap/yr 

kg/ap/yr 

ouE/s/animal 

Source 

Chapter 4 

Table 4.94:  Emission levels of system-integrated housing techniques for weaners 

Section 
number 

Housing system 

4.7.4.1  Deep pit (in case of a fully slatted floor) 

4.7.4.2 

4.7.4.3 

4.7.4.4 

4.7.4.5 

4.7.4.6 

4.7.4.7 

4.7.4.8 

Vacuum system for frequent manure removal (in case 
of a fully slatted floor) 
Vacuum system for frequent manure removal (in case 
of a partly slatted floor) 
Slanted walls in the manure channel (in case of a fully 
or partly slatted floor) 
Scraper (in case of a partly slatted floor) 
Scraper (in case of a fully slatted floor) 
Frequent slurry removal by flushing, with: 
- non-aerated flush 
- aerated flush 
Kennel or hut housing (in case of a partly slatted 
floor) 
Straw flow system (in case of a solid concrete floor) 

4.7.4.9 

Convex floor and separated manure and water 
channels (in case of partly slatted pens) 

4.7.4.10 

Manure surface cooling fins (in case of a fully or 
partly slatted floor) 

NH3 emission 

kg/ap/yr 
0.6–0.8 
0.78 (1) 
0.600.75 
0.5 (2) (0.2–0.7) 
0.06–0.40 (3) 

0.39–0.60 

0.17 (1) 
0.029–0.324 (3) 
0.180.36 
0.39 

0.36 (non-aerated flush) 
0.30 (aerated flush) 

0.38 (2) (0.20.7) (1) 

0.21 (2) 
0.26 (frequent discharge) 
0.21(flushing) 
0.20 (discharge) 
0.14–0.22 (slanted walls) (3) 

0.15 

0.53 (two-climate system) 

4.7.4.11  Pens for weaning pigs, with a partly slatted floor 

0.34 (with convex or sloped floor) 

4.7.4.12 

Pens or flat decks with fully slatted flooring and a 
concrete sloped underground floor to separate faeces 
and urine 

0.5 (1) (0.20.7) (3) 

0.42 

NI 

2.81–5.86 

NI 

1.8–5.98 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.074 

0.08 

NI 

NI 

NI 

NI 

0.08 

NI 

0.132 
(slanted 
walls) 

NI 

NI 

NI 

0.08 

NI 

4.7.4.13  Manure collection in water 

0.13 (3)–0.16 (1) 

NI 

0.132 

0.13–0.15 (3) 

0.28–0.30 

NI 

12.1 

3 (4) 

NI 

NI 

NI 

NI 

3 (4) 

NI 

5.4 
(slanted walls) 

NI 

NI 

NI 
3 (4) 

NI 

5.4 

NI 

 [ 43, COM 2003 ] 
[ 261, France 2010 ] 
[ 634, BE Flanders 2013 ] 
[182, Germany 2010 ] 
[ 180, Spain 2010 ] 

 [ 43, COM 2003 ] 

 [ 640, Netherlands 2013 ] 
[ 179, Spain 2010 ] 

 [ 43, COM 2003 ] 

 [ 43, COM 2003 ] 

[ 183, Germany 2010 ] 

 [ 535, UK 2011 ] 
 [ 43, COM 2003 ] 

[ 186, BE Flanders 2010 ] 
[ 176, Netherlands 2010 ] 

 [ 43, COM 2003 ] 

 [ 43, COM 2003 ] 

 [ 43, COM 2003 ] 

[ 184, Germany 2010 ] 

 [ 43, COM 2003 ] 

[ 177, Netherlands 2010 ] 
 [ 608, Netherlands 2010 ] 

 [ 147, Cabaraux et al. 2009 ] 

424 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Section 
number 

Housing system 

NH3 emission 

kg/ap/yr 

CH4 

PM10 

Odour 

kg/ap/yr 

kg/ap/yr 

ouE/s/animal 

Source 

Chapter 4 

0.5 (1) (0.20.7) (3) 

4.7.4.14 

Full litter system (in case of a solid concrete floor) 
Full litter and forced or natural ventilation. Manure 
removal at the end of the cycle 
 Full litter and forced ventilation: 
 - straw (manure removal after 5 cycles) 
 - sawdust (manure scatter every 10 days) 
Full litter and forced ventilation: 
- straw (manure removal after 2 cycles) 
- sawdust (manure scatter every 10 days and manure 
removal after 2 cycles) 
(1) Values derived from measurements. 
(2) Values derived by expert judgement based on conclusions by analogy. 
(3) Measured values. 
(4) Calculation based on an emission factor of 75 ouE/LU per second and an average weight of 20 kg. 
NB: NI = no information provided. 

0.25 (3) 
0.22 (3) 

0.43 (1)  
0.11 (1) 

NI 

NI 

3 (4) 

 [ 181, Germany 2010 ] 

0.60 
0.29 

0.70 
0.48 

NI 

NI 

 [ 532, Nicks et al. 2002 ] 

 [ 147, Cabaraux et al. 2009 ] 

Intensive Rearing of Poultry or Pigs 

425 

 
 
 
 
 
 
Chapter 4 

4.7.4.1 

Deep pit (in case of a fully or partly slatted floor) 

Description 
Weaners are group-housed in pens or on flat decks (raised pens). The system is a combination 
of the classic pen with a fully slatted floor or partly slatted floor with slats made of plastic or 
metal elements, with slurry removal at the end of the cycle.  This type of housing is equipped 
with mechanical ventilation, either negative-pressure or balanced-pressure ventilation. Auxiliary 
heating is also applied in the form of gas radiant heaters, electric fan or convection heaters or by 
a central heating plant with heating pipes.  

Achieved environmental benefits 
See Section 4.7.1.1 for fully slatted floors and Section 4.7.1.1.1 for partly slatted floors. 

Cross-media effects 
See Section 4.7.1.1 for fully slatted floors and Section 4.7.1.1.1 for partly slatted floors. 

Environmental performance and operational data 
The  associated  emission  factor  in  the  UNECE  guidance  document  on  'Options  for  ammonia 
mitigation' is equal to 0.65 kg NH3/animal place/yr [ 508, TFRN 2014 ].  

In  France,  measured  ammonia  emissions  in  fully  slatted  floor  systems  with  a  deep  pit  for 
weaners  are  between  70 mg/h  and  120  mg/h  per  weaned  piglet,  with  an  average  of  97 mg/h. 
This  figure corresponds  to  130  grams  per  piglet  produced  in  the  56  days  of  the  cycle 
(6 batches/yr),  equivalent  to  0.78 kg  NH3  per  weaner  place  per  year  [  261,  France  2010  ]. 
Measured  NH3  emissions  for  the  system  with  a  fully  slatted  floor  reported  by  Belgium 
(Flanders)  are  0.6–0.75 kg  NH3/animal  place/yr  and  odour  emissions  12.1 ouE/animal/s  
[ 634, BE Flanders 2013 ] [ 638, BE Flanders 2014 ]. 

Table 4.95  presents  ventilation  rates  reported  from  Spain,  Belgium  (Flanders)  and  Germany 
applied to houses with fully slatted floors. 

Table 4.95:  Ventilation rates (m3/h per animal place) applied to weaner houses with fully slatted 

floors 

Spain 
18.2 (7.5–57.8)  

Cold season 
Germany 
3.5–7.0  

Belgium (FL) 
2–6 

Spain 
39.2 (10.7–50.3)  

Warm Season 
Germany 
20–50  

Belgium (FL) 
10–18  

Source: [ 179, Spain 2010 ] [ 182, Germany 2010 ] [ 637, BE Flanders 2012 ] 

Technical considerations relevant to applicability  
See Section 4.7.1.1 for fully slatted floors and Section 4.7.1.1.1 for partly slatted floors. 

Economics 
Investment costs for a new house for weaners with a partly slatted floor (0.4 m2 total surface per 
animal) are reported to be between EUR 210 and EUR 240 per animal place [ 589, Netherlands 
2010 ].  

Driving force for implementation 
See Section 4.7.1.1 for fully slatted floors and Section 4.7.1.1.1 for partly slatted floors. 

Example plants 
Commonly applied technique.  

426 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Reference literature 
[  179,  Spain  2010  ]  [  182,  Germany  2010  ]  [  261,  France  2010  ]  [  508, TFRN  2014  ]  [  589, 
Netherlands 2010 ] [  634, BE  Flanders  2013  ]  [ 637,  BE  Flanders  2012 ]  [  638,  BE  Flanders 
2014 ] 

Chapter 4 

4.7.4.2 

Vacuum system for frequent slurry removal (in case of fully slatted 
floor) 

Description 
See Section 4.7.1.2.  

Achieved environmental benefits 
See Section 4.7.1.2. A reduction of 25 % for NH3 emissions is reported due to frequent removal 
of slurry in comparison with a fully slatted floor system with a deep pit [ 508, TFRN 2014 ].  

Cross-media effects 
See Section 4.7.1.2.  

Environmental performance and operational data 
An emission factor of 0.5 kg NH3/ap/yr is associated with the system in Germany when plastic 
slats  are  used  with  a  slurry  removal  frequency  of  4  to  8  weeks.  A  shorter  manure  removal 
interval can also be applied (2 weeks) [ 182, Germany 2010 ]. From Spain, ammonia emissions 
of up to 0.4 kg NH3/ap/yr were measured for a weekly removal [ 180, Spain 2010 ]. See also 
Section 4.7.1.2. 

Technical considerations relevant to applicability 
See Section 4.7.1.2.  

Economics 
Investment  costs  for  the implementation  of this  housing  system  for  weaners  are  equivalent  to 
EUR 195/ap/yr; the corresponding annualised investment costs are EUR 18 per animal place per 
year [ 182, Germany 2010 ]. See also Section 4.7.1.2. 

Driving force for implementation  
See Section 4.7.1.2.  

Example plants 
See Section 4.7.1.2.  

Reference literature 
[ 180, Spain 2010 ] [ 182, Germany 2010 ] [ 508, TFRN 2014 ] 

4.7.4.3 

Vacuum system for frequent slurry removal (in case of partly 
slatted floor) 

Description 
See Section 4.7.1.3. 

Achieved environmental benefits 
See  also  Section  4.7.1.3.  A  reduction  of  25 %  for  NH3  emissions  due  to  frequent  removal  of 
slurry in comparison with a fully slatted floor system with a deep pit is reported [ 508, TFRN 
2014 ]. 

Cross-media effects 
See Section 4.7.1.3. 

Intensive Rearing of Poultry or Pigs 

427 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
In  the  ILF BREF [ 43, COM 2003 ], the  ammonia emission reduction is assumed by analogy 
between  25 %  and  35 %  in  comparison  to  fully  slatted  floor  systems  with  a  deep  pit,  which 
corresponds  to  emissions  of  0.45 kg  to  0.60 kg  NH3/ap/yr  and  0.39 kg  to  0.52 kg  NH3/ap/yr 
respectively.  

Technical considerations relevant to applicability 
See Section 4.7.1.3. 

Economics 
See Section 4.7.1.3. 

Driving force for implementation 
See Section 4.7.1.3. 

Example plants 
See Section 4.7.1.3. 

Reference literature 
[ 43, COM 2003 ] [ 292, Italy 2001 ] [ 508, TFRN 2014 ] 

4.7.4.4 

Slanted walls in the manure channel (in case of a fully or partly 
slatted floor) 

Description 
See Section 4.7.1.4. 

Achieved environmental benefits 
See Section  4.7.1.4. Having one or two slanted pit walls, in combination with  a partly slatted 
floor  and  frequent  manure  removal,  can  reduce  emissions  by  up  to  65 %  for  weaners  in 
comparison with a fully slatted floor system with a deep pit [ 508, TFRN 2014 ]. 

Cross-media effects 
See Section 4.7.1.4. 

Environmental performance and operational data 
In  Spain,  with  a  continuous  removal  system,  ammonia  and  methane  emissions  have  been 
recorded in weaner houses equipped with fully slatted floors and manure channels with slanted 
walls; in particular, NH3 emissions have been measured up to 0.324 kg/ap/yr, corresponding to 
approximately  a  50 %  emission  reduction,  and  CH4  emissions  have  been  measured  from 
1.08 kg/ap/yr  to  5.98 kg/ap/yr,  corresponding  to  about  a  65 %  emission  reduction,  in 
comparison  with  a  deep  pit  system  [  179,  Spain  2010  ].  From  the  Netherlands,  ammonia 
emissions  associated  with  a  partly  slatted  floor  with  slanted  walls  in  the  manure  channel  are 
reported to be equal to 0.17 kg per animal place per year for a maximum  emitting surface per 
animal in the channel of 0.7 m2 [ 640, Netherlands 2013 ].  

Technical considerations relevant to applicability 
The conversion of an existing house for weaners to this system is only possible if the pen has a 
length of at least 2.75 m [ 273, BE Flanders 2010 ]. See also Section 4.7.1.4. 

Economics 
From Belgium (Flanders), investment costs for implementing the technique in existing housing 
systems, with water and manure channels, are reported as EUR 51/ap, for houses equipped with 
partly slatted floors and EUR 44/ap for houses equipped with fully slatted floors. Reported extra 
costs  for  installation  in  new  houses  in  Belgium  (Flanders)  are  EUR 19  per  weaner  [  265,  BE 
Flanders 2010 ]. In the Netherlands, the reported extra investment costs for the implementation 

428 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

of  the  technique  are  equivalent  to  EUR 13/ap  and  the  total  annual  costs  are  EUR 2/ap/yr 
(including  depreciation,  interest,  maintenance  and  all  other  operating  costs,  such  as  energy) 
[ 589, Netherlands 2010 ]. 

Extra costs compared to a fully slatted floor system with a deep pit emptied at the end of the 
cycle  reported  by  Spain  range  from  EUR 1.27/ap/yr  (existing  buildings  with  PVC  pens)  to 
EUR 2.67/ap/yr (existing buildings with fixed metallic pens) for retrofitting existing houses and 
up  to  EUR 0.23/ap/yr  for  new  houses  [  179,  Spain  2010  ].  Extra  costs  expressed  per  kg  of 
marketed pig (on the basis of a production of 579 kg of pigs per weaner place annually) range 
from EUR 2.2 to EUR 4.64/tonne of pig produced for existing houses while for new houses they 
are  reported  to  be  EUR 0.4/tonne  of  pig  produced.  The  cost  efficiency  of  the  technique 
corresponding to a 60 % ammonia abatement is calculated at EUR 0.5 per kg  of NH3 for new 
houses and up to EUR 6.2 per kg of NH3 for existing houses [ 338, Piñeiro et al. 2009 ].  

The  annual  extra  costs  are  reported  to  be  equal  to  EUR  2  per  animal  place  and  the  cost 
efficiency EUR 5–6 per kg of NH3–N reduced [ 508, TFRN 2014 ].  

Driving force for implementation 
No information provided. 

Example plants 
The technique is applied in Spain and the Netherlands. 

Reference literature 
[ 179, Spain 2010 ] [ 265, BE Flanders 2005 ] [ 273, BE Flanders 2010 ] [ 338, Piñeiro et al. 
2009 ] [ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] [ 640, Netherlands 2013 ] 

4.7.4.5 

Scraper for frequent slurry removal (in case of fully or partly slatted 
floor) 

Description 
See Section 4.7.1.5 and Figure 4.51. In pens or flat decks for weaners, plastic and metal slats are 
used. 

Source: [ 292, Italy 2001 ] 

Figure 4.51:  Flat deck system with a scraper under a fully slatted floor 

Achieved environmental benefits 
See Section 4.7.1.5.  

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Chapter 4 

Cross-media effects 
See  Section  4.7.1.5.  The  energy  required  for  operating  the  scraper  is  estimated  to  be  from 
0.24 kWh per weaner place per year (fully slatted floor) to about 0.15 kWh per weaner place per 
year (partly slatted floor). 

Environmental performance and operational data 
Weaners  in  pens  or  on  flat  decks  with  fully  slatted  floors  are  associated  with  ammonia 
emissions of 0.39 kg NH3/ap/yr (35 % reduction compared to  a fully slatted floor with a deep 
pit)  when  the  removal  of  the  manure  to  the  pit  outside  the  building  is frequent  and  there is  a 
separate  urine  drain.  In  pens  with  a  partly  slatted  floor  and  a  manure  scraper,  frequently 
removing  the  manure from  the  manure  pit  outside  the  building  reduces  emissions  by  between 
40 % (0.36 kg NH3 per pig place per year (Italy)) and 70 % (0.18 kg NH3 per pig place per year 
(Netherlands and Belgium)) compared to a fully slatted floor with a deep pit [ 42, Netherlands 
1999 ] [ 391, Italy 1999 ].  

Technical considerations relevant to applicability 
See Section 4.7.1.5.  

Economics 
No information provided. 

Driving force for implementation 
See Section 4.7.1.5.  

Example plants 
Piglet places with partly slatted floors have been equipped in the Netherlands. See also Section 
4.7.1.5. 

Reference literature 
[ 42, Netherlands 1999 ] [ 292, Italy 2001 ] [ 391, Italy 1999 ] 

4.7.4.6 

Frequent slurry removal by flushing (in case of a fully or partly 
slatted floor) 

Description  
See Section 4.7.1.9. Application is possible in pens with a partly or fully slatted floor.  

Achieved environmental benefits 
See Section 4.7.1.9. A 65 % emission reduction for the technique of flushing gutters applied in 
weaner housing systems is adopted by the UNECE guidance [ 508, TFRN 2014 ]. 

Cross-media effects  
See Section 4.7.1.9.  

Environmental performance and operational data 
In  pens  or  on  flat  decks  with  a  fully  slatted  floor,  limiting  the  manure  surface  in  the  manure 
channel and removing the manure twice a day by flushing achieves a reduction of 40 % (0.36 kg 
NH3 per pig place per year) with non-aerated slurry, and of 50 % (0.30 kg NH3 per pig place per 
year)  with  aerated  slurry.  Extra  energy  requirements  for  flushing  fully  slatted  housing  for 
weaners  are  reported  to  be  between  1.9 kWh/ap/yr  (non-aerated  slurry)  and  3.1  kWh/ap/yr 
(aerated slurry) [ 391, Italy 1999 ].  

In  pens  with  partly  slatted  floors,  removing  the  manure  twice  a  day  by  flushing  and  fast 
discharge  of  the  manure  on  the  slatted  area  by  using  triangular  iron  bars  achieves  a  65 % 
reduction (0.21 kg NH3 per pig place per year). The energy requirements for flushing housing 
with partly slatted floors for weaners are 0.75 kWh/ap/yr [ 42, Netherlands 1999 ].  

430 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Technical considerations relevant to applicability 
See Section 4.7.1.9.  

Economics 
The extra annual cost, in comparison with fully slatted floors with  a deep pit,  for new houses 
equipped with flushing gutters is EUR 5 per animal place and the cost efficiency is EUR 14/kg 
of NH3-N reduced [ 508, TFRN 2014 ].  

Chapter 4 

For other designs, no information is provided.  

Driving force for implementation 
See Section 4.7.1.9.  

Example plants 
See  Section  4.7.1.9.  In  1999,  in  the  Netherlands,  about  75 000  weaned  piglet  places  were 
equipped with this system in combination with partly slatted floors. 

Reference literature 
[ 42, Netherlands 1999 ] [ 391, Italy 1999 ] [ 508, TFRN 2014 ] 

4.7.4.7 

Kennel or hut housing (in case of a partly slatted floor) 

Description 
See  Section  4.7.1.10.  Along  the  width  of  the  pen,  kennels  are  placed  side  by  side,  whilst  the 
defecating areas are situated on the short sides of the pen.  In the middle of the area is a solid 
floor with feeders. The floor can be littered with a small amount of straw for enrichment. Slurry 
is generated and removed at the end of the rearing period.  

Source: [ 547, IMAG-DLO 2001 ]  

Figure 4.52:  Kennel housing system for weaners  

Intensive Rearing of Poultry or Pigs 

431 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

In  a  variant  of  the  technique,  bedding  is  provided  and,  therefore,  solid  manure  is  produced 
which is removed by tractor [ 183, Germany 2010 ]. Forced ventilation is also an option for the 
kennel system with partly slatted floors [ 547, IMAG-DLO 2001 ].  

Achieved environmental benefits 
See Section 4.7.1.10. From Germany, a reduction of 25 % of ammonia emissions is reported for 
weaners in naturally ventilated houses with kennels. 

Cross-media effects  
See Section 4.7.1.10. Under extreme climatic conditions, the reliability of the ventilation system 
in weaner houses must be assured. 

Environmental performance and operational data 
The ammonia emission factor for naturally ventilated kennel housing for weaners in Germany is 
  emissions  are  0.08  kg/ap/yr  and  odour  emissions  2.25 ouE/s/animal  
0.38 kg  NH3/ap/yr.  PM10
[  183,  Germany  2010  ].  Data  concerning  energy  consumption  and  labour  requirements  are 
presented in Table 4.96. 

Table 4.96:  Consumption and labour requirements for kennel housing systems for weaners 

Bedding 

Electricity 

Fuel 

kg/ap/yr 
26 (1) 

kWh/ap/yr 
2–3 (2) 

kWh/ap/yr 

80 

150 

Cleaning 
water 
l//ap/yr 

Labour 

h/ap/yr 

1.37 

(1) When the variant with bedding is used. Equivalent to the provision of 80 g of straw per 

animal place per day. 

(2) This value can be achieved when a kennel of 20 piglets, from 3 to 5 weeks of age, is fitted 
with automatically controlled natural ventilation and when 1 kWh of heating is provided by 
underfloor heating elements [ 356, Carbon Trust 2005]. 

Source: [ 183, Germany 2010]  

In  naturally  ventilated  kennel  systems  in  Germany,  weaners  are  kept  in  groups  of  up  to 
100 animals. Kennels for weaners can be heated with warm water piping. The solid floor covers 
40 %  of  the  floor  area.  The  reported  available  space  per  animal,  applied  in  Germany,  is 
0.41 m2/weaned piglet.  

Technical considerations relevant to applicability  
See Section 4.7.1.10. 

Economics 
For new houses in Germany, the reported investment needed per animal place is EUR 249. The 
corresponding  total  annualised  costs  are  EUR 28  per  animal  place  per  year  for  weaners.  In 
addition,  more  labour  is  needed,  e.g.  for  the  cleaning  of  the  lying  kennels.  The  additional 
expenses generated by these factors, however, are compensated for by energy cost savings in the 
unheated naturally ventilated housing.  

Driving force for implementation  
See Section 4.7.1.10. 

Example plants 
See Section 4.7.1.10. 

Reference literature 
[ 183, Germany 2010 ] [ 356, Carbon Trust 2005 ] [ 547, IMAG-DLO 2001 ] 

432 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4.7.4.8 

Straw flow housing system (in case of a solid concrete floor) 

Description 
See Section  4.7.5.9. The system combines  a regular straw supply,  a sloped floor and frequent 
manure scraping. Weaners can be provided with littered kennels in cooler months in naturally 
ventilated houses.  

Chapter 4 

Achieved environmental benefits  
See Section 4.7.5.9. 

Cross-media effects 
See Section 4.7.5.9. 

Environmental performance and operational data 
Ammonia emissions from a naturally ventilated house with daily straw addition and scraping of 
the manure in the dunging passage are estimated as 0.21 kg NH3/ap/yr [ 535, UK 2011 ].  

Technical considerations relevant to applicability 
See Section 4.7.5.9. 

Economics 
Labour requirements are low. From the UK, it has been reported that the total investment cost 
for a new house equipped with natural ventilation is around EUR 160 per animal place (EUR 1 
= GBP 0.88) [ 535, UK 2011 ]. Buildings are simple, and easy to clean and maintain; hence, a 
long lifespan is expected. 

Driving force for implementation 
See Section 4.7.5.9. 

Example plants 
The system is used in farms in the UK. 

Reference literature 
[ 535, UK 2011 ] 

4.7.4.9 

Convex floor and separated manure and water channels (in case of 
partly slatted pens) 

Description 
See Section 4.7.1.6. 

With this system, the total space available per weaner is reported as 0.4 m2 with at least 0.12 m2 
solid floor corresponding to each animal. The reported minimum width of the manure channel is 
0.6–0.9 m. The maximum emitting surface per animal, in the manure channel, is 0.10 m2 when 
slanted walls are used in the manure channel. Slats over the manure channel are metal or plastic. 
The  system  can  be  combined  with  a  flushing  system  or  slanted  walls  in  the  manure  channel. 
Two different designs are illustrated in Figure 4.53 and Figure 4.54. 

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433 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 42, Netherlands 1999 ] 

Figure 4.53:  Partly  slatted  floor  with  a  shallow  manure  pit  and  a  water  channel  for  spoiled 

drinking water in combination with a convex floor 

Source: [ 42, Netherlands 1999 ] 

Figure 4.54:  Convex floor with triangular metal slats in combination with a discharge system and 

slanted walls in the manure channel 

Achieved environmental benefits 
See  Section  4.7.1.6.  A  65 %  ammonia  emission  reduction  is  reported  when  the  technique  is 
combined with slanted walls in the manure channel [ 508, TFRN 2014 ]. 

Cross-media effects 
See  Section  4.7.1.6.  Flushing  twice  a  day  has  an  extra  energy  consumption  of  0.75 kWh  per 
weaner place per year. 

Environmental performance and operational data 
Ammonia  emissions  vary  depending  on  the  manure  collection  system  and  the  emitting  slurry 
surface per animal (see Table 4.97). 

Table 4.97:  Emissions of housing systems equipped with a convex solid floor and separate manure 

and water channels  

Housing system 
variation 

PM10 

Odour 

kg/ap/yr  ouE/s/animal  

Reference 

NH3 
kg/ap/yr 
0.26 
0.20 
0.21 

NI 

NI 

Frequent discharge, 
metal slats 
Flushing gutters 
Slanted walls, metal 
0.18 
slats  
0.18 (1) 
Slanted walls, metal 
slats, 0.1 m2/ap 
(0.14–0.22) (2) 
(1) Values derived by expert judgement based on conclusions by analogy. 
(2) Measured data. 
NB: NI = no information provided. 

0.132 (1) 

5.4 (1) 

NI 

NI 

NI 

NI 

[ 43, COM 2003 ] 
[ 186, BE Flanders 2010 ] 
[ 43, COM 2003 ] 

[ 497, BE Flanders 2010 ] 

 [ 176, Netherlands 2010 ] 

434 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Technical considerations relevant to applicability 
See Section 4.7.1.6. 

A  minimum  length  of  2.75 m  is  reported  as  necessary  for  retrofitting  pens  for  weaners  
[ 273, BE Flanders 2010 ]. 

Economics 
Extra investment costs for the implementation of the technique with slanted walls in the manure 
channel, as compared to standard housing with a partly slatted floor with a 60 % solid floor and 
0.4  m2  available  total  surface  per  weaned  piglet,  are  reported  from  the  Netherlands  as  being 
equal  to  EUR 13  per  animal  place  and  the  annual  costs  EUR 2  per  animal  place  per  year  
[ 589, Netherlands 2010 ].  

Retrofitting a house for weaners, with a system with a manure pit with a combination of water 
and  manure  channels,  equipped  with  slanted  side  walls,  is  reported  to  cost  about  EUR 45 per 
animal place [ 273, BE Flanders 2010 ].  

No cost data are available for the combination of the technique with flushing gutters. 

Driving force for implementation 
See Section 4.7.1.6. 

Example plants 
In the Netherlands, this system has been implemented in most new buildings and modifications 
of existing houses [ 176, Netherlands 2010 ]. 

Reference literature 
[ 42, Netherlands 1999 ] [ 43, COM 2003 ] [ 176, Netherlands 2010 ] [ 186, BE Flanders 2010 ] 
[ 273, BE Flanders 2010 ] [ 497, BE Flanders 2010 ] [ 508, TFRN 2014 ] [ 589, Netherlands 
2010 ] 

4.7.4.10 

Slurry cooling 

Description 
Slurry cooling channels or slurry surface cooling fins can be used. See Section 4.7.1.7 for slurry 
cooling channels and Section 4.7.1.8 for slurry surface cooling fins. 

Achieved environmental benefits  
See Section 4.7.1.7 and Section 4.7.1.8. 

Cross-media effects 
See Section 4.7.1.7 and Section 4.7.1.8. 

Environmental performance and operational data 
From  the  Netherlands,  the  ammonia  emission  reduction  achieved  by  slurry  cooling  fins  is 
reported  as  75 %  for  weaner  houses  compared  to  FSF  with  a  deep  pit  (150 %  cooling  fins' 
surface/slurry  surface)  and 
is  0.15 kg  NH3/ap/yr  
the  associated  emission 
[ 640, Netherlands 2013 ]. 

factor 

The  ammonia  emission  reduction  attained  by  the  technique  of  surface  cooling  with  fins 
combined with partly slatted floors is given as 75 % [ 508, TFRN 2014 ]. 

For  surface  cooling  fins,  the  extra  energy  consumption  is  estimated  to  be  3 kWh  per  weaner 
place  per  year  for  partly  slatted  floors  and  7 kWh  per  weaner  place  per  year  for  fully  slatted 
floors [ 589, Netherlands 2010 ]. No information is provided for slurry cooling channels. 

Intensive Rearing of Poultry or Pigs 

435 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Technical considerations relevant to applicability 
See Section 4.7.1.7 and Section 4.7.1.8. 

Economics 
The  extra  investment  costs  for  the  implementation  of  surface  cooling  fins  are  calculated  at 
EUR 14 to EUR 19 per animal place and the extra annual costs at EUR 2 to EUR 3 per animal 
place (see Table 4.78). An extra cost of EUR 3–4 per animal place per year for new buildings 
equipped with partly slatted floors and  surface cooling fins and a cost efficiency of EUR 7 to 
EUR 10 per kg of NH3-N reduced are reported [ 508, TFRN 2014 ]. No data are available for 
slurry cooling channels. 

Driving force for implementation 
See Section 4.7.1.7 and Section 4.7.1.8. 

Example plants 
See Section 4.7.1.7 and Section 4.7.1.8. 

Reference literature 
[ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] [ 640, Netherlands 2013 ] 

4.7.4.11 

Pens for weaning pigs with partly slatted floor 

Description 
A partly slatted floor combined with a solid concrete floor with a smoothly finished surface is 
applied.  The  solid  floor  can  be  slightly  inclined  covering  one  side  of  the  pen  or  convex  with 
slats at both sides and two manure channels (see Figure 4.55). The slats can be metal, or plastic; 
concrete slats can also be used. In general, the buildings (walls and roof) are insulated.  

Manure is handled as slurry and it is often drained through a pipe discharge system where the 
individual  sections  of  the  manure  channels  are  drained  via  plugs  or  gates.  The  channels  are 
usually  drained  after  the  removal  of  each  group  of  pigs,  in  connection  with  disinfecting  the 
pens, i.e. at intervals of 6 to 8 weeks. 

This  housing  system  is  normally  equipped  with  mechanical  ventilation,  either  in  the  form  of 
negative-pressure  or  balanced-pressure  ventilation.  The  ventilation  is  dimensioned  for  a 
maximum output of around 40–50 m3 per hour per place. Auxiliary heating is available in the 
form of either electric fan heaters (room heating) or a central heating plant with heating pipes 
(floor heating). Naturally ventilated designs are also applied. 

In Denmark, houses with partly slatted floors are called ‘two-climate systems’: the floor below 
the covered lying area is heated with hot water pipes during the first couple of weeks; heating is 
then turned off since the heat production of the pigs is sufficient for keeping them warm.  

Source: [ 42, Netherlands 1999 ] 

Figure 4.55:  Partly slatted floor with a convex or sloped concrete floor 

436 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
Reducing the emitting surface in the manure channel achieves an ammonia emission reduction. 
The  emission  reduction  is  enhanced  with  the  use  of  a  convex  or  sloped  floor  as  the  risk  of 
emissions from the solid part decreases. 

The 'two-climate' design can offer a lower energy consumption. The naturally ventilated design 
uses less energy compared to the reference system. 

Cross-media effects 
A  partly  slatted  floor  may  entail  increased  requirements  in  temperature  control  and  general 
management,  as  solid  floors  can  get  soiled,  in  particular  at  high  temperatures  (see  general 
remarks in Section 4.7). Dirty floors have implications for pig hygiene and health and for odour 
emissions.  Water  consumption  is  higher  when  the  ratio  of  solid  to  slatted  floor  increases  
[ 261, France 2010 ]. 

Environmental performance and operational data 
The proportion of slatted to solid floor is commonly around one to one. The average ammonia 
emissions are estimated at 0.5 kg NH3 per animal place per year [ 184, Germany 2010 ]. Dust 
emissions  are  considered  to  be  on  average  0.08 kg  PM10  per  animal  place  per  year  [ 184, 
Germany 2010 ]. 

Odour emissions are reported from Germany as being equivalent to 75 ouE/s per livestock unit 
(LU). Odour emission factors vary depending on the growth stage of the animals, as displayed 
in Table 4.98. 

Table 4.98:  Odour emission factors for weaners, in Germany  

Unit 

Variable 
Live weight 
Live mass  
Emission factor   ouE/s/animal 
Source: [ 474, VDI 2011 ] 

kg 
LU/animal 

Up to 10 
0.02 
1.5 

Stage of growth 
Up to 25 
0.03 
2.25 

Up to 30 
0.04 
3.0 

The  'two-climate'  system  applied  in  Denmark  is  reported  to  have  ammonia  emissions  40 % 
lower than those from a fully slatted floor system [ 500, IRPP TWG 2011 ]. An emission factor 
equal  to  0.53 kg  NH3/ap/yr  was  associated  with  the  'two-climate'  system,  analogous  to  a 
reduction of 34 % in relation to a fully slatted floor with a deep pit [ 397, Denmark 2000 ]. For 
pens with a partly slatted floor and a sloped or convex solid floor, the respective emission factor 
was reported as 0.34 kg NH3/ap/yr by the Netherlands, corresponding to a reduction of 43 % in 
relation to a fully slatted floor with a deep pit [ 42, Netherlands 1999 ]. 

Technical considerations relevant to applicability 
In  existing  houses,  the  applicability  depends  on  the  design  of  the  existing  manure  pit.  An 
adaptation  of  existing  slatted  floor  pens  would  be  possible  by  filling  part  of  the  slatted  floor 
(without changing the total surface area of the pit). 

Economics  
Extra  costs  related  to  the  retrofitting  of  this  technique  in  existing  buildings  with  fully  slatted 
floors are shown in Table 4.99. 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Table 4.99:  Extra costs associated to the retrofitting of partly slatted floors in existing fully slatted 

floored pens for weaners, in Spain  

System 

Ammonia 
emissions 
reduction (1) 

Extra costs 

 % 

EUR/ap/yr 

EUR/tonne 
pig produced 

EUR/kg NH3 
reduced 

Pens with partly slatted floor 
retrofitted in existing houses 
(piglets from 6 kg to 20 kg) 
(1) Data refer to a comparison made against fully slatted floored pens. 
Source: [ 500, IRPP TWG 2011 ] 

25–35 

0.88–2.25 

1–2.6 

3.49–12.50 

Driving force for implementation 
Partly slatted floors are considered more welfare friendly.  

Example plants 
Partly  slatted  floor  systems  for  weaners  are  applied  in  the  Netherlands  and  Germany.  In 
Denmark, only housing systems with partly slatted floored pens are built, where it is estimated 
that at least 80 % of all weaners are housed in the 'two-climate' system. Dutch legislation does 
not allow this system in new buildings. 

Reference literature 
[ 42, Netherlands 1999 ] [ 184, Germany 2010 ] [ 261, France 2010 ] [ 397, Denmark 2000 ] [ 
474, VDI 2011 ] [ 500, IRPP TWG 2011 ] 

4.7.4.12 

Pens or flat decks with a fully slatted floor and a concrete sloped 
underground floor to separate faeces and urine 

Description 
A board (concrete or  another material) with a very smooth surface is placed under the slatted 
floors. The size can be adapted to the dimensions of the pen. The board has a slope of at least 
12 °  towards  a  central  slurry  pit  that  allows  the  urine  to  drain  continuously  and  the  slurry  to 
move towards the central pit. The slurry is removed weekly to a store by gravity or by pumping. 
Also,  frequent  emptying  of  the  central  slurry  channel  will  enhance  the  emissions  reduction. 
Emissions  predominantly  come  from  any  slurry  remaining  on  the  board  (Figure 4.56).  At  the 
end of the weaning period, dry faeces are easily removed by water jets. 

Source: [ 391, Italy 1999 ] 

Figure 4.56:  Flat decks or pens with an underground concrete slope to separate faeces from urine 

438 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Achieved environmental benefits 
The immediate removal of manure to the central channel and the immediate draining of urine 
achieves a 30 % reduction of ammonia emissions. The benefit of applying this system depends 
on the smoothness of the board surface to allow the urine to drain continuously and the slurry to 
move towards the central pit. 

Chapter 4 

Cross-media effects 
Flies  can  be  a  serious  problem,  especially  when 
[ 261, France 2010 ]. See also ´Cross-media effects´ in Section 4.7.1.1 for fully slatted floors. 

the  manure  sticks 

to 

the  slope  

Environmental performance and operational data 
An  emission  factor  of  0.42 kg  NH3  per  pig  place  per  year  is  reported  by  Italy.  No  additional 
energy consumption is required. 

Technical considerations relevant to applicability 
With a manure pit of a sufficient depth, this technique can be easily applied to existing housing, 
but only if a discharge system is located in a central position in the pen for emptying the manure 
channel.  If  this  is  not  the  case,  the  entire  floor  plate  of  the  manure  pit  has  to  be  removed  to 
install the discharge system, which is only possible at significant extra costs. 

Economics 
No information provided. 

Driving force for implementation 
No information provided. 

Example plants 
A few farms in Italy. 

Reference literature 
[ 261, France 2010 ] [ 292, Italy 2001 ] [ 391, Italy 1999 ]  

4.7.4.13 

Manure collection in water 

Description 
Slurry  is  collected  in  the  water  that  is  kept  in  the  channel  after  cleaning.  After  each  rearing 
cycle,  and  before  the  pens  are  cleaned,  slurry  is  removed  from  the  manure  channel.  Cleaning 
water  is  kept  in  the  channel  which  is  automatically  refilled  until  a  level  of  around  
120–150 mm is reached. The system can be combined with a fully slatted floor, a partly slatted 
floor with a slurry channel or a partly slatted floor with a central convex floor and slats at the 
back and the front side of the pen (see Figure 4.57). 

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Chapter 4 

Source:[ 178, Netherlands 2010 ] 

Figure 4.57:  Cross section of a variation of a system for rearing weaners with manure collection in 

water 

The minimum depth of the channel is 500 mm. The installation of slanted walls in the channel is 
possible  for  the  further  reduction  of  the  ammonia-emitting  surface.  In  the  Netherlands,  one 
slanted wall is installed. 

Achieved environmental benefits 
Ammonia  emissions  are  reduced  due  to  a  reduced  emitting  surface  and lower emissions from 
the diluted slurry in the manure channels. 

Cross-media effects 
Large quantities of water are required. Dilute slurry entails higher transport costs for storage and 
subsequent landspreading; furthermore, it is not suitable for biogas production. 

Environmental performance and operational data 
In the Netherlands, measured ammonia emissions are reported to be in the range of 0.13 kg per 
animal place per year if the available total surface area in a partly slatted floor system is lower 
than 0.35 m2 per animal, and 0.16 kg per animal place per year when the available surface area 
per  animal  is  higher  than  0.35 m2  [  640,  Netherlands  2013  ].  In  addition,  dust  and  odour 
emissions have been measured in the Netherlands at 0.132 kg PM10/ap/yr and 5.4 ouE/s/animal, 
respectively.  

In  trials  carried  out  in  Belgium  (Wallonia),  ammonia  emissions  in  fully  slatted  floor  systems 
were  measured  in  the  range  0.13–0.15  kg  NH3/animal  place  per  year  when  water  was  poured 
into the pit at the start of the rearing cycle with the aim of establishing a water layer of 50 mm 
(values calculated from measured data reported in g/head per day, for 53 days' rearing time and 
6.33 cycles a year) [ 147, Cabaraux et al. 2009 ]. 

Economics 
Extra  investment  costs  for  a  system  with  a  partly  slatted  floor  pen  with  a  slanted  wall  in  the 
manure  channel  are  reported  from  the  Netherlands  as  being  equivalent to  EUR  13  per  animal 
place,  with  annual  costs  equivalent  to  EUR 2/ap/yr  (including  depreciation,  interest, 
maintenance and all other operating costs) in comparison with a fully slatted floor system with a 
deep pit [ 589, Netherlands 2010 ]. 

Technical considerations relevant to applicability 
The  technique  is  difficult  to  implement  in  existing  buildings  due  to  the  costly  modifications 
required for retrofitting the existing housing system. 

440 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
This system is relatively inexpensive for new buildings. 

Example plants 
In the Netherlands, this system was very popular in new housing systems, for the reduction of 
ammonia emissions, before air cleaning systems (wet scrubbers) became widespread. In 2010, 
at least 50 000 weaners were kept in this housing system in the Netherlands. 

Reference literature 
[  147,  Cabaraux  et  al.  2009  ]  [  177,  Netherlands  2010  ]  [  178,  Netherlands  2010  ]  [  589, 
Netherlands 2010 ] [ 608, Netherlands 2010 ] [ 640, Netherlands 2013 ] 

4.7.4.14 

Full litter system (in case of solid concrete floor) 

Description 
The  solid  concrete  floor  is  almost  completely  bedded  with  a  layer  of  straw  or  other 
lignocellulosic  materials  (e.g.  sawdust)  to  absorb  urine  and  to  incorporate  faeces.  Bedding 
material is regularly supplied to prevent wet surfaces. Solid manure is obtained, which has to be 
frequently  removed  in  order  to  avoid  the  litter  becoming  too  wet.  In  cooler  regions,  the  floor 
area may be divided such that a fully insulated kennel or creep (heated) provides a lying area for 
the  weaned  pigs  with  access  to  a  fully  bedded  dunging  area.  Some  straw  is  provided  in  the 
kennel or creep. Automatic feeding and drinking systems are used and the group size is up to 
100  animal  places.  Post-weaning  rearing  houses  are  mainly  based  on  a  manure  management 
system with deep litter [ 262, France 2010 ]. The technique typically operates in open-climate, 
naturally ventilated houses. A schematic representation of the pen in a house with deep litter is 
given in Figure 4.58. 

Source: [ 181, Germany 2010 ] 

Figure 4.58:  Housing system with deep litter for weaners 

The  technique  can  also  be  applied  in  closed,  insulated,  mechanically  ventilated  houses,  in  a 
variation  that  uses  a  smaller  quantity  of  bedding  for  the  littered  floor  at  the  beginning  of  the 
rearing period and regular addition during the cycle [ 185, Germany 2010 ].  

The  plane  littered-floor  variation  can  be  combined  with  a  fully  bedded  yard  with  a  concrete 
floor,  which  is  a  requirement  for  organic  farming.  In  a  variation  of  this  technique,  a  covered 
lying  area  is  present.  A  plane  littered-floor  system  with  a  bedded  yard  (with  and  without  a 
covered lying area) is illustrated in Figure 4.59.  

Intensive Rearing of Poultry or Pigs 

441 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

An  elevated  plane  concrete  feeding  area  may  be  constructed,  to  lead  weaners  to  prepare 
themselves  a  defecating  area  where  sufficient  space  is  available  [ 185,  Germany  2010  ]  
[ 420, Ramonet 2003 ]. 

Source: [ 185, Germany 2010 ] 

Figure 4.59:  Housing system with a littered floor and a yard (with or without a covered lying area) 

for weaners 

Achieved environmental benefits 
See  also  Section  4.7.5.13.  If  the  dunging  area  is  cleaned  regularly  or  an  adequate  quantity  of 
straw is added in order to absorb urine to avoid wet surface areas, ammonia emissions are low. 
For naturally ventilated systems, low energy consumption is achieved. No additional energy for 
heating is required. 

Cross-media effects 
Poorly  maintained  litter  (inadequate  quantity  of  straw  and  insufficient  frequency  of  addition) 
can lead to emissions of odours and ammonia higher than those measured with  a fully slatted 
floor [ 261, France 2010 ]. Emission of greenhouse gases is also possible. 

In the closed littered-floor system, the straw bed might warm up in the summer. The functional 
reliability  of  the  system,  under  extreme  climatic  conditions,  is  not  always  guaranteed. 
Management  requirements  are  higher,  due  to  the  necessary  regular  littering  of  the  floor  and 
possible need for dung removal.  

Environmental performance and operational data 
Buildings  are  kept  cool,  with  plenty  of  straw  to  absorb  urine.  They  are  cleaned  and  dried 
completely between batches [ 535, UK 2011 ]. 

It is expected that the use of straw will allow weaners to control the temperature themselves in 
systems where insulated kennels or creeps are not used, thus requiring no additional energy for 
heating. The system requires cleared concrete areas in summer at feeding places for the pigs to 
cool  down.  If  a  covered  lying  area  is  present,  the  litter  quantity  needs  to  be  adjusted  to  the 
temperature and the cover must be removed at high temperatures. Manual dung removal from 
the covered lying area may also be necessary. 

In order to  maximise their exposure to wind, naturally  ventilated  houses  should be situated at 
right  angles  to  the  main  wind  direction  [  181,  Germany  2010  ].  The  ventilation  rate  for  the 
mechanically ventilated configuration is reported as 3.5–7 m3/h/ap for the cold season and 20–
50 m3/h/ap for the warm season [ 185, Germany 2010 ]. 

In Germany, for both the littered and the deep litter system and for a final live weight of 28 kg, 
the provided space per animal is reported to be up to 0.35 m2, while in France with kennels the 
available space per animal is reported to be 0.5 m2 to 0.6 m2 in the deep litter housing system. In 

442 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

the deep litter system, bedding is spread every week and manure is removed at the end of the 
rearing period.  

In France, in deep litter systems for rearing weaners, a quantity of 6 kg of straw is used at the 
beginning  of  the  cycle  and  straw  is  added  once  to  twice  a  week.  The  total  required  straw 
quantity is 10–15 kg per piglet per cycle and the quantity of generated manure is estimated  as 
30 kg to 50 kg per animal [ 329, CORPEN 2003 ] [ 261, France 2010 ]. 

Sawdust  can  also  be  used  instead  of  straw.  A  quantity  of  approximately  15 kg  of  sawdust  is 
equivalent to 6 kg of straw per piglet per cycle (having about the same amount of dry matter), 
which  results  in  the  production  of  about  17 kg  of  'composted'  manure  containing  sawdust  or 
straw at the end of rearing cycle [ 261, France 2010 ]. On a yearly basis, the quantity of straw 
used is approximately 30 kg to 60 kg per animal place.  

The  resources  demand,  as  reported  from  Germany  for  two  variations  of  the  technique,  are 
presented in Table 4.100. 

Table 4.100:  Resources demand for two different variations of solid concrete floor housing systems 

with litter for weaners (8–28 kg) 

System 

Electricity 

kWh/ap/yr 

2 

Deep litter, open 
climate, with natural 
ventilation 
Littered floor 
combined with yard, 
with forced 
ventilation  
(1) 150 g/animal per day. 
NB: NI = no information provided. 

12 

Bedding 
material 
kg/ap/yr 
53 (1) 
40–60 

Cleaning 
water 
l/ap/yr 

Fuel 

kg/ap/yr 

150 

NI 

35 

150 

170 

Source 

[ 181, Germany 
2010 ] 

[ 185, Germany 
2010 ] 

Reported emissions from weaner houses have been measured under different conditions and are 
summarised in Table 4.101. Tests carried out in France showed that rearing weaners in a deep 
litter  system  with  sawdust  produced  four  times  less  ammonia  than  rearing  them  in  the  same 
system with straw,  while the quantity of manure produced per piglet was identical. Emissions 
are presumed to be higher due to the external yard but have not been estimated [ 181, Germany 
2010 ].  

Intensive Rearing of Poultry or Pigs 

443 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.101:  Emission levels associated with straw-littered systems for rearing of weaners 

System 

NH3 

CH4  N2O  PM10 
kg/ap/yr  

Odour 
ouE/s/animal 

Source 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.16 

0.60 

0.43 

0.11 

3 (3) 

3 (3) 

[ 532, Nicks et al. 
2002 ] 

0.5 (1) 
(0.2–0.7) (2) 
0.5 (1) 
(0.2–0.7) (2) 

[ 185, Germany 
2010 ] 
[ 181, Germany 
2010 ] 

Littered floor with straw and 
forced ventilation 
Deep litter with straw and 
natural ventilation 
Deep litter with straw and 
forced ventilation, removal of 
litter after 5 consecutive 
batches, regular addition of 
straw (4) (2) 
Sawdust litter and forced 
ventilation, no regular addition 
of sawdust, manual scattering 
of manure every 10 days (4) (2) 
Deep litter with straw and 
forced ventilation, removal of 
litter after two batches, regular 
addition of straw (4) (5) 
Deep litter with sawdust and 
forced ventilation. Removal of 
litter after two batches, no 
sawdust addition, manual 
scattering of manure every 
10 days, manure removal after 
2 cycles (4) (5) 
(1) Conclusion by analogy. 
(2) Values derived from measurements. 
(3)  Values  have  been  calculated from  an  emission  factor  of  75 ouE/s/LU  (0.04  LU/head),  for  weaners  up  to 30 kg 

 [ 147, Cabaraux et 
al. 2009 ] 

 [ 147, Cabaraux et 
al. 2009 ] 

[ 532, Nicks et al. 
2002 ] 

0.22 

0.48 

0.16 

0.25 

0.29 

0.57 

0.70 

0.02 

NI 

NI 

NI 

NI 

NI 

NI 

(average weight 20 kg)). 

(4) Values calculated from measured data reported in g/head per day, for 53 days' rearing time and 6.33 cycles a 

year. 

(5) Measured values. 
NB: NI = no information provided. 

Technical considerations relevant to applicability 
In  houses  with  natural  ventilation,  the  technique  may  not  be  applicable  to  houses  located  in 
regions  with  a  warm  climate.  The  system  can  be  applied  in  all  new  housing.  The  scarcity  of 
bedding materials in some geographical areas may be a limitation to the use of such a system. 

Economics 
The  annual  operating  costs  are  expected  to  be  higher  than  for  the  reference  system.  
[ 291, IRPP TWG 2002 ]. The cost of straw is reported to be increasing.  

Driving force for implementation 
Improved animal welfare.  

Example plants 
The technique is applied in Germany. According to a survey carried out in 2008 on livestock 
buildings  (SCEES  Survey  of  2008),  around  7 %  of  post-weaning  places  in  France  were  using 
littered systems. About 4 % of the weaning pigs in Italy are kept on fully bedded systems. In the 
UK, kennels and creeps (with heat) in association with a fully bedded system are common, with 
group sizes of around 100 pigs of 7 kg (weaning) up to 15 kg or 20 kg. 

444 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Reference literature 
[ 147, Cabaraux et al. 2009 ] [ 181, Germany 2010 ] [ 185, Germany 2010 ] [ 261, France 2010 ] 
[ 262, France 2010 ] [ 291, IRPP TWG 2002 ] [ 329, CORPEN 2003 ] [ 420, Ramonet 2003 ] 
[ 532, Nicks et al. 2002 ] [ 535, UK 2011 ] 

Chapter 4 

4.7.5 

Housing systems for growing and finishing pigs (fattening pigs) 

Performances  of  housing  techniques  for  fattening  pigs  concerning  NH3,  CH4,  N2O,  dust  and 
odour are summarised in Table 4.102.  

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Table 4.102:  Emission levels of system-integrated housing techniques for fattening pigs 

Section 
number 

Housing system 

Deep pit (in case of a fully slatted floor) 

Deep pit (in case of a fully slatted floor) 
Removal every 2 months 

4.7.5.1 

Deep pit (in case of a fully slatted floor) 
Removal at the end of cycle  

Deep pit (in case of a partly slatted floor)  
Removal 2–3 times per cycle 
Deep pit (in case of a partly slatted floor) 
Removal twice per cycle  
Vacuum  system  for  frequent  slurry  removal 
(in case of a fully slatted floor) 
Vacuum  system  for  frequent  slurry  removal 
(in  case  of  a  partly  slatted  floor)  with  metal 
slats 
Vacuum system for frequent slurry removal 
(in case of a partly slatted floor) with concrete 
slats 
Slanted  walls  in  the  manure  channel  (in  case 
of a fully slatted floor) 
Slanted  walls  in  the  manure  channel  (in  case 
of a partly slatted floor) 
Scraper for frequent slurry removal (in case of 
a fully slatted floor) 
Scraper for frequent slurry removal (in case of 
a partly slatted floor) 

4.7.5.2 

4.7.5.3 

4.7.5.4 

4.7.5.5 

446 

4.6 (2) 

3.64 (3) 

2.91 (1.37–3.95) (1) 

2.56 (1) 
1.83 (3) 
(1.51–2.14)  
4.9 (2) (4) 

2.63 (1) 

3.64 (1) 
3.6 (1) 
2.25 
0.54–1.85 (1) 

1.55–1.95 

1.8–2.25 

NH3 

2.39–3.0 
3.0 

CH4 

kg/ap/yr 

NI 
NI 

N2O 

NI 
NI 

PM10 

NI 
NI 

Odour 
ouE/s/animal 
NI 
NI 

2.2 (0.8–3.6) (1) 

10.4 (1–19.8) 

0.015  
(0.003–0.028) 

0.1  
(0.07–1.3) 

29.2 

Source 

[ 43, COM 2003 ] 
[ 508, TFRN 2014 ] 
[ 642, BE Flanders 2013 ] 
[ 643, Van Ransbeeck et al. 
2013 ]  
[ 634, BE Flanders 2013 ] 

NI 

NI 

NI 

NI 

[ 266, Austria 2010 ] 

1.0–6.0 (1) 

0.02–0.15 (1) 

0.24 (2) 

6.5 (1) 

[ 189, Germany 2010 ] 
[ 474, VDI 2011 ] 

1.28 (1) 

[ 269, France 2010] 

NI 

2.1 (1) 

5.6 (1) 

10.5 

NI 

0.035 (1) 

0.24 (1) 

1.1 

2.42 (1) 

4–30 (1) 
NI 
NI 
0.42–2.35 (1) 

0.0432 (1) 

0.02–0.15 (1) 
NI 
NI 
NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.24 (2) 
NI 
NI 
NI 

7 (2) 
1.14 (1) (5) 
NI 
NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 270, France 2010] 

[ 662, Philippe et al. 2007 ] 

[ 373, UBA Austria 2009 ] 

[ 271, France 2010 ] 

[ 192, Germany, 2010 ] 
[ 272, France 2010 ] 
[ 292, Italy 2001 ] 
[ 187, Spain 2010 ] 

[ 43, COM 2003 ] 

[ 292, Italy 2001 ] 

[ 188, Spain 2010 ] 

[ 589, Netherlands 2010 ] 

NI 

[ 292, Italy 2001 ] 

Intensive Rearing of Poultry or Pigs 

1.23–1.61 (1) 

0.59–1.46 (1) 

1.0–1.2 

NI 

1.5–1.8 

NI 

NI 

NI 

Section 
number 

Housing system 

4.7.5.8 

4.7.5.7 

4.7.5.6 

Frequent slurry removal by flushing 
PSF, concrete slats, aerated 
PSF, concrete slats, non-aerated 
PSF, triangular slats, non-aerated 
FSF, permanent slurry layer, non-aerated 
FSF, permanent slurry layer, aerated 
PSF, permanent slurry layer, non-aerated 
PSF, permanent slurry layer, aerated 
Reduced manure pit (in case of a partly slatted 
floor) 
Kennel or hut housing (in case of a partly 
slatted floor) 
Straw flow system (in case of a solid concrete 
floor) 
Convex floor and separated manure and water 
channels  (in  case  of  partly  slatted  pens), 
slanted  walls,  metal  bars,  0.18  m2  emitting 
surface/animal 
Slanted walls, metal bars, 0.27 m2 emitting 
surface/animal 
Slanted walls, concrete slats, 0.18 m2 emitting 
surface/animal 
4.7.5.11  Manure collection in water 

4.7.5.10 

4.7.5.9 

Slurry  cooling  channels  (in  case  of  a  partly 
slatted  floor)  25–49 %  solid  floor,  frequent 
removal by vacuum, no bedding and 10 W/m2 
cooling effect 
50–75 % solid floor, frequent removal by 
vacuum, no bedding and 10 W/m2 cooling 
effect 
Partly  slatted  floor,  manure  scraper,  straw 
addition in the solid part  
10–50 W/m2 cooling effect 
FSF or PSF with manure surface cooling fins 
Concrete slats 
Metal slats 
Full litter system (in case of a solid concrete 
floor) 

4.7.5.12 

4.7.5.13 

NH3 

0.90 

1.20 
1.00 
2.1 
1.35 
1.5 
1.2 

CH4 

kg/ap/yr 

N2O 

PM10 

Odour 
ouE/s/animal 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

Chapter 4 

Source 

[ 43, COM 2003 ] 

[ 43, COM 2003 ] 

[ 292, Italy 2001 ] 

[ 196, Spain 2010 ] 

0.89–1.69 (1) 

0.9–1.82 (1) 

2.4 (3) 
(1.0–6.0) (1) 
1.9–2.1 (1) 
4.89 (3.62–6.15) (1) 

1.01 
(0.99–1.02) (1) 

1.4 (3) 

1.2 

NI 

1.16 (3) 

1.52 (3) 

2.2–2.6 (3) 

1.4 (3) 

1.2 

1–4 (1) 

0.11–0.15 (1) 

0.24 (2) 

7 (2) (6) 

[ 190, Germany 2010 ] 

0.54–1.24 (1) 
3.26 (1) 

0.025–0.04 (1) 
0.25 (1) 

NI 
NI 

NI 
NI 

[ 519, Amon et al. 2007 ] 
[ 662, Philippe et al. 2007 ] 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

0.153 

17.9 (1) 

[ 194, Netherlands 2010 ] 

0.153 

17.9 (1) 

[195, Netherlands 2010 ] 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

NI 

[ 186, BE Flanders 2010 ] 

NI 

[ 268, Denmark 2010 ] 

[ 268, Denmark 2010 ] 

[ 160, Denmark 2010 ] 

[ 589, Netherlands 2010 ] 

[ 640, Netherlands 2013 ] 

Intensive Rearing of Poultry or Pigs 

447 

Chapter 4 

Section 
number 

Housing system 

Deep litter floor system with straw  

Deep litter floor with sawdust or soft wood 
particles (removal at the end of cycle) 

Littered floor with removal once a week 

4.7.5.14 

4.7.5.15 

4.8.5 

Littered  external  alley  (in  case  of  a  solid 
concrete floor) 
V-shaped  manure  belts  (in  case  of  a  partly 
slatted floor) 
Floating balls in slurry channels 

NH3 

4.2 (3) 
(1–6) (1) 
4.58–5.12 (1) 
4.46 (4.24–4.67) (3) 

5.65–7.53 (1) 

2.43 (3) 
(1.0–5.0) (1) 

2.4 

1.05–1.20 (3) 

2.3 (1) 

CH4 

kg/ap/yr 

1.6–18 (1) 
1.87–2.78 (1) 
NI 

NI 

0.8–2.8 (1) 

NI 

0.94 (1) 

NI 

(1) Measured values. 
(2) Values derived by expert judgement based on conclusions by analogy. 
(3) Values derived from measurements. 
(4) Includes emissions during storage. 
(5) Value derived from an emission of 36 × 106 ouE/year per animal place 
(6) Calculation based on an emission factor of 50 ouE/LU per second and an average weight of 70 kg. 
(7) Calculation based on an emission factor of 30 ouE/LU per second and an average weight of 70 kg. 
NB: NI = no information provided. 

N2O 

PM10 

Odour 
ouE/s/animal 
4.2 (2) (7) 

NI 
NI 

NI 

0.32 (2) 

NI 
NI 

NI 

0.32 (2) 

4.2 (6) 

NI 

NI 

NI 

NI 

5.9 (1) 

NI 

Source 

[ 193, Germany 2010 ] 
[ 474, VDI 2011 ] 
[ 530, Nicks et al. 2003 ] 
[ 375, Philippe et al. 2007 ] 

[ 531, Ramonet et al. 2002 ] 

[ 474, VDI 2011 ]  
[ 191, Germany 2010 ] 

[ 292, Italy 2001 ] 

[ 198, Netherlands 2010 ] 
[ 200, Netherlands 2010 ] 
[ 213, Netherlands 2010 ] 

0.6–3.7 (1) 
0.01–0.79 (1) 
NI 

NI 

NI 

NI 

0.11 (1) 

NI 

448 

Intensive Rearing of Poultry or Pigs 

 
 
 
Chapter 4 

4.7.5.1 

Deep pit (in case of a fully or partly slatted floor) 

Description 
Pigs are group-housed in thermally insulated houses that are forced or naturally ventilated and 
divided  into  pens  with  a  fully  slatted  floor  system  with  no  physical  separation  between  the 
lying, feeding and dunging areas. Partly slatted floor systems are similar except that the floor is 
divided into a slatted area (for dunging) and a solid, non-slatted area (for feeding and lying).  

Slurry  is  collected  in  a  deep  pit  beneath  concrete  slats.  The  slurry  is  removed  at  variable 
intervals such as two or three times per cycle or, usually, after every fattening period, or even 
less frequently. Overflow channels can also be used to lead slurry to the storage pit (see Section 
4.7.1.1.1). 

Achieved environmental benefits 
See Section 4.7.1.1 (fully slatted floor) and Section 4.7.1.1.1 (partly slatted floor). 

In  general,  higher  ammonia  emissions are  expected  for longer storage  of  the slurry  in  the  pit. 
Emptying  the  slurry  pit  once  or  twice  within  a  fattening  period  has  the  potential  to  reduce 
ammonia  emission  but  the  effect  cannot  always  be  proven  or  is  proven  insufficiently  
[ 474, VDI 2011 ]. 

Cross-media effects 
See Section 4.7.1.1 (fully slatted floor) and Section 4.7.1.1.1 (partly slatted floor). 

In general, higher ammonia emissions are expected for longer storage of the slurry in the pit. 

Environmental performance and operational data 
Fully slatted floor systems 
An  overview  of  the  reported  emission  data,  including  some  data  already  included  in  the  ILF 
BREF [ 43, COM 2003 ], is presented in Table 4.103. 

Intensive Rearing of Poultry or Pigs 

449 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.103:  Emissions  associated  with  a  deep  pit  (in  case  of  a  fully  slatted  floor)  or  with  an 

overflow channel for various categories of pigs 

Description 

Deep pit - 
Manure 
removal every 
2 months 
Overflow 
channel - 
Manure 
removal at the 
end of cycle 

Deep pit - 
Manure 
removal at the 
end of cycle 

NH3  

CH4 

N2O 

kg/ap/yr 

Odour 
ouE/animal/s 

Source 

4.6 (1) 

NI 

NI 

NI 

[ 266, Austria 2010 ] 

3.64 (2) 

1.0–6.0 (3) 

0.02–0.15 
(3) 

6.5 (4) 

[ 189, Germany 2010 ] 
[ 474, VDI 2011 ] 

2.91 (1.37–3.95) 
(3) (5) 

NI 

NI 

1.28 (3) (6) 

[ 269, France 2010 ] 

2.56 (3) (7) 

2.1 (3) 

0.035 (3) 

 4.9 (1) (8) 

10.5 (9) (8) 

2.39–3.0 
3.0 

NI 
NI 

1.1 (9) 
(8) 
NI 
NI 

NI 

NI 

NI 
NI 

2.2 (0.8–3.6) (3) 

1.83 (1.51–2.14) 
(2) (10) 

10.4 
(1–19.8) (3) 

0.015 
(0.003–
0.028) (3) 

29.2 (3) 

5.6  

0.24 

NI 

[ 270, France 2010 ] 

 [ 373, UBA Austria 
2009 ] 
 [ 43, COM 2003 ] 
[ 508, TFRN 2014 ] 
[ 634, BE Flanders 
2013 ] [ 642, BE 
Flanders 2013 ] 
[ 643, Van Ransbeeck et 
al. 2013 ] 
 [ 662, Philippe et al. 
2007 ] 

(1) Values derived by expert judgement based on conclusions by analogy. 
(2) Values derived from measurements. 
(3) Measured values. 
(4) Calculation on the basis of an emission factor of 50 ouE/s/LU and an average weight of 65 kg for fattening pigs 

from 25 kg to 110 kg. 

(5) The reported range corresponds to the minimum and maximum values measured at the beginning and at the end of 

the fattening period during the warm season.  

(6) Value is calculated from a reported emission of 3.8 X 107 ouE/animal place per year and 342 days in the finishing 

unit annually. 

(7) Average for the cold season. 
(8) Modelled values (e.g. results based on N balance). 
(9) Values include emissions during storage. 
(10) Value calculated from a measured mean daily emission (e.g. 4.98 ± 0.85 g/animal/day for NH3) and for a typical 

mean rearing period of 117 days and 3.14 cycles per year. 

NB: NI = no information provided. 

The  resources  demand  and  the  breakdown  for  the  different  uses  reported  from  Germany  are 
presented in Table 4.104.  

Table 4.104:  Resources demand for the rearing of fattening pigs in houses with a fully slatted floor 

with an overflow channel 

Resources 

Unit 

Demand 

Energy  

kWh/ap/yr 

26 (21–31) 

Fuel  
Cleaning water  

kWh/ap/yr 
litres/ap/yr 

70 (60–80) 
55 (45–65) 

Labour  

hours/ap/yr 

0.90 (0.88–0.94) 

Source: [ 189, Germany 2010 ] 

Breakdown values 
Lighting: 4 (3–5) 
Ventilation: 20 (16–24) 
Feeding: 1 (0.8–1.2) 
Cleaning: 0.3 (0.2–0.5) 
Manure removal: 0.1 
Heating 
For a large group of over 100 animals: 45  
Routine: 0.66–0.72 
Special work: 0.22 

450 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
The  energy  required  for  forced  ventilation  is  variable,  but  on  average  in  Italy  this  has  been 
estimated  at  21.1 kWh  per  grower/finisher  place  per  year  [  292,  Italy  2001].  Table 4.105 
presents  ventilation  rates  reported  from  Spain,  Belgium  (Flanders)  and  Germany  applied  to 
houses with fully slatted floors.  

Chapter 4 

Table 4.105:  Ventilation  rates  (m3/h  per  animal  place)  applied  to  fattening  pig  houses  with  fully 

slatted floors 

Cold season 
Germany 
7–15  

Spain 
15.7 (1–64)  

Spain 
66.6 (15–120)  
Source: [ 187, Spain 2010 ] [ 189, Germany 2010 ] [ 637, BE Flanders 2012 ] 

Belgium (FL) 
6–20 

Warm season 
Germany 
50–115 

Belgium (FL) 
20–80 

The maximum required ventilation rates, on which the design of fattening pig houses is based, 
are reported to be equivalent to 80 m3/h/ap in the Netherlands and 100 m3/h/ap in Denmark. 

Partly slatted floor systems 
A summary of reported emission data associated with partly slatted floor systems for fattening 
pigs is presented in Table 4.106.  

Table 4.106:  Emissions from partly slatted floor systems for fattening pigs with infrequent manure 

removal  

NI 

NI 

CH4 

NH3 

N2O 

PM10 

Source 

Odour  

2.63 (2) 

2.42 (2) 

kg/ap/yr  

0.0432 (2) 

ouE/s/animal  

Slurry storage 
and frequency of 
 removal 
Deep pit - Manure 
removal at least 
twice (2–3 times) 
in the cycle (1) 
Overflow channel - 
Manure removal at 
the end of the cycle 
or twice in the 
cycle (every 1–2 
months) 
Deep pit - Manure 
removal twice in 
the cycle  
(1) Indoor temperature 20.1. ± 1.0 °C (set-point temperature 18 °C). 
(2) Measured data. 
(3) Values derived by expert judgement based on conclusions by analogy. 
(4) Values have been calculated from an emission of 50 ouE/s per LU and an average weight for fattening pigs of 

[ 192, 
Germany 
2010] [ 474, 
VDI 2011 ] 

[ 271, France 
2010 ] 

[ 272, France 
2010 ] 

3.64 
 (2–7) (2) 

0.02–0.15 (2) 

4–30 (2) 

0.24 (3) 

1.21(5) 

3.6 (2) 

7 (4) 

NI 

NI 

NI 

70 kg.  

(5) Value derived from an emission of 36  106 ouE/year per animal place and 342 days of annual production time.  
NB: NI = no information provided. 

Values  reported  from  Germany  indicate  a  ventilation  rate in the  range  of  7–15  m3/h/ap  in  the 
cold season and 50–115 m3/h/ap in the warm season [ 192, Germany 2010 ].  

Technical considerations relevant to applicability  
See Section 4.7.1.1 (fully slatted floor) and Section 4.7.1.1.1 (partly slatted floor). 

Economics 
The reported investment and operating costs for fattening pig houses with a fully slatted floor 
and an overflow channel are presented in Table 4.107, as well as the breakdown values. 

Intensive Rearing of Poultry or Pigs 

451 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.107:  Investment and operating costs for fattening pig houses with a fully slatted floor with 

an overflow channel 

Parameter 

Average 

Range 

Investment costs 
(EUR/ap) 
Annualised investment costs 
(EUR/ap/yr) 

Annual operating costs 
(EUR/ap/yr) 

379 

375–383 

Total cost  
(EUR/ap/yr) 
NB: NI = no information provided; NA = not applicable. 

410 

NI 

350 

350–420 

Breakdown values  
For a large group of over 100 animals: 
324 

31 

30–34 

For a large group of over 100 animals: 33 

Feed: 200; animal: 138 
Water, energy, heating: 13.5 
Other: 12; labour: 14 

NA 

Source: [ 189, Germany 2010 ]  

Investment  costs  per  fattening  pig  place  in  partly  slatted  floor  housing  (new  plant  of 
4 200 places  and  with  0.8  m2  pen  surface  per  pig  place  and  40 %  solid  floor)  without  any 
additional system to reduce ammonia emissions are reported to be EUR 370 per fattening pig 
place [ 589, Netherlands 2010 ]. 

Driving force for implementation 
See Section 4.7.1.1 (fully slatted floor) and Section 4.7.1.1.1 (partly slatted floor). 

Example plants 
In Germany, the variation with the overflow channel is the standard system used.  In Belgium 
around 85 % and in France more than 80 % of the fattening and post-weaning animal places are 
on fully slatted floors [ 269, France 2010] and in Spain about a half [264, Loyon et al. 2010 ].  

In France, 10 % of fattening pigs are reared on partly slatted floors with a deep pit; generally, in 
small  and  very  old  houses.  Partly  slatted  floors  with  a  deep  pit  are  also  reported  to  be  rarely 
applied in Germany. 

Reference literature 
[ 43, COM 2003 ] [ 187, Spain 2010 ] [ 189, Germany 2010 ] [ 192, Germany 2010 ] [ 264, 
Loyon et al. 2010 ] [ 266, Austria 2010 ] [ 269, France 2010 ] [ 270, France 2010 ] [ 271, France 
2010 ] [ 272, France 2010 ] [ 292, Italy 2001 ] [ 373, UBA Austria 2009 ] [ 474, VDI 2011 ] 
[ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] [ 634, BE Flanders 2013 ] [ 637, BE Flanders 
2012 ] [ 642, BE Flanders 2013 ] [ 643, Van Ransbeeck et al. 2013 ] [ 662, Philippe et al. 2007 ] 

4.7.5.2 

Vacuum system for frequent slurry removal (in case of a fully 
slatted floor) 

Description  
See Section 4.7.1.2.  

Achieved environmental benefits 
See Section 4.7.1.2. A reduction of 25 % for NH3 emissions is reported due to frequent removal 
of slurry in comparison with a fully slatted floor system with a deep pit [ 508, TFRN 2014 ].  

Cross-media effects 
See Section 4.7.1.2.  

Environmental performance and operational data 
In  fattening  pig  houses  in  France,  emptying  the  slurry  every  15  days  reduces  ammonia 
emissions  by  20 %,  compared  to  housing  where  slurry  is  stored throughout  the whole  rearing 
and fattening/finishing period [ 261, France 2010 ] [ 491, Guingand N. 2000 ].  

452 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Reductions of NH3 emissions of between 30 % and 60 % are reported from Spain for fattening 
pigs. Ammonia emissions ranging from 0.54 kg to 1.85 kg NH3/ap/yr were measured in Spain 
with  a  weekly  removal  of  slurry  [  187,  Spain  2010  ].  In  the  UK,  a  reduction  of  ammonia 
emissions of up to 25 % has been estimated, compared to fully slatted floors with a deep pit, due 
to the frequent removal of slurry by a vacuum system operated at least twice per week [ 648, 
DEFRA  2011  ]  [  500,  IRPP  TWG  2011  ].  The  same  performance  for  ammonia  emission 
reduction  (25 %)  was  reported  by  Italy,  corresponding  to  an  emission  factor  of  2.25  kg 
NH3/ap/yr [ 292, Italy 2001 ].  

Nitrous  oxide  emissions,  from  fully  slatted  floor  housing  systems  with  frequent  removal  of 
manure  by  vacuum,  have  been  estimated  in  Germany  for  fattening  pigs  to  be  in  the  range  of 
0.02–0.15 kg N2O/ap/yr [ 474, VDI 2011 ]. See also Section 4.7.1.2 

Technical considerations relevant to applicability 
See Section 4.7.1.2.  

Economics 
In UK, the investment costs for the implementation of this housing system in ACNV houses for 
fattening pigs are equivalent to EUR 270/ap/yr [ 267, UK, 2010 ]. See also Section 4.7.1.2. 

Driving force for implementation 
See Section 4.7.1.2.  

Example plants  
In  Germany,  the  system  represents  the  standard  system  for  fattening  pigs  [  500,  IRPP  TWG 
2011 ]. 

Reference literature 
[ 187, Spain 2010 ] [ 261, France 2010 ] [ 267, UK, 2010 ] [ 292, Italy 2001 ] [ 474, VDI 2011 ] 
[ 491, Guingand N. 2000 ] [ 500, IRPP TWG 2011 ] [ 508, TFRN 2014 ] [ 648, DEFRA 2011 ] 

4.7.5.3 

Vacuum system for frequent slurry removal (in case of a partly 
slatted floor) 

Description  
See Section 4.7.1.3. 

Achieved environmental benefits 
See  also  Section  4.7.1.3.  A  reduction  of  25 %  for  NH3  emissions  is  reported  due  to  frequent 
removal of slurry in comparison to a fully slatted floor with a deep pit [ 508, TFRN 2014 ]. 

Cross-media effects 
See Section 4.7.1.3. 

Environmental performance and operational data 
In the ILF BREF [ 43, COM 2003 ], the ammonia emission reduction is assumed by analogy to 
be  between  25 %  (concrete  slats)  and  35 %  (metal  slats)  in  comparison  to  fully  slatted  floor 
systems  with  a  deep  pit,  which  corresponds  to  ammonia  emissions  of  1.8 kg  to  2.25 kg 
NH3/ap/yr and 1.55 kg to 1.95 kg NH3/ap/yr respectively.  

A consumption of around 330 l/ap/yr of water is reported from Finland, representing about 1 % 
of the total water consumption (99 % drinking water); a labour demand of 1 h/ap/yr and bedding 
material consumption of 8.7 kg/ap/yr are also reported [ 276, Finland 2010 ]. 

Technical considerations relevant to applicability 
See Section 4.7.1.3. 

Intensive Rearing of Poultry or Pigs 

453 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
For  a  farm  for  3 000  fattening  pigs  in  Finland  with a  70 % solid  floor,  providing  0.92 m2  per 
animal in the pen, investment costs are reported to be EUR 400 per animal place [ 276, Finland 
2010 ].  

In  the  Netherlands,  the  investment  costs  for  a  fully  equipped  housing  system  that  comprises 
4 200 fattening  pig  places (40 %  convex  solid  floor  and  0.8  m  deep  manure  channels  without 
other  ammonia  abatement  techniques)  are  reported  as  EUR 387  per  fattening  pig  place 
(240 places per section, 0.8 m2 pen surface per pig place) [ 589, Netherlands 2010 ]. See also 
Section 4.7.1.3 

Driving force for implementation 
See Section 4.7.1.3. 

Example plants 
See Section 4.7.1.3. 

Reference literature 
[  43,  COM  2003  ]  [  276,  Finland  2010  ]  [  292,  Italy  2001  ]  [  508,  TFRN  2014  ]  [  589, 
Netherlands 2010 ] 

4.7.5.4 

Fully or partly slatted floor with slanted walls in the manure 
channel 

Description  
See Section 4.7.1.4. 

Achieved environmental benefits 
See Section 4.7.1.4. An ammonia reduction of up to 65 % can be attained for partly slatted floor 
system with a manure channel with one or two slanted walls in comparison with a fully slatted 
floor system with a manure pit [ 508, TFRN 2014 ]. 

Cross-media effects 
See Section 4.7.1.4. 

Environmental performance and operational data 
Reported emissions associated with this technique are shown in Table 4.108. 

Table 4.108:  Emission levels associated with slanted walls in the manure channel 

Animal 

NH3 

CH4 

PM10  

Odour 

kg/ap/yr 

ouE/s/animal  

Fully slatted floor, 
concrete slats 

1.23–1.61 (1)  0.59–1.46 (1) 

Slurry 
removal 
frequency 

Monthly 

1.0  

Partly slatted 
floor, metal slats 
Partly slatted 
floor, concrete 
slats 
(1) Measured data. 
NB: NI = no information provided. 

1.2 

NI 

NI 

NI 

NI 

Source 

[ 188, Spain 
2010 ] 

[ 589, 
Netherlands 
2010 ] 

Technical considerations relevant to applicability 
See Section 4.7.1.4. 

454 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
Extra costs for retrofitting the system in existing houses with fully slatted floors with a deep pit 
have been reported from Spain as being equivalent to EUR 6.45–7.74 per animal place per year. 
Referring  to  the  produced  pig,  extra  costs  are  calculated  in  the  range  of  EUR  21.9–26.3  per 
tonne of pig produced. For new houses, the corresponding extra costs in comparison with a fully 
slatted floor system with a deep pit are reported from Spain to be in the range of EUR 0–0.73 
per  animal  place  or  EUR 0–2.5  per  tonne  of  pig  produced  [  188,  Spain  2010  ]  [  379,  Spain 
2009 ]. 

In  Belgium  (Flanders),  the  investment  costs  for  retrofitting  this  system  in  existing  houses, 
operating with a fully slatted floor with a deep pit, are reported as EUR 344 per animal place, 
including  the  modification  of  the  manure  pit  to  a  water  and  manure  channel  system  (see 
Section 4.7.1.6) [ 273, BE Flanders 2010 ]. In the case where the floor remains fully slatted after 
rebuilding, the above costs are reported to be equal to EUR 168 per animal place. 

In  the  Netherlands,  the  reported  extra  investment  costs  for  implementing  the  technique  to 
standard  housing  with  a  partly  slatted  floor  are  EUR 39  per  animal  place  when  slats  are 
triangular and made of metal, and EUR 30 per animal place when slats are made of concrete. 
The  corresponding  annual  costs  are  EUR 5/ap/yr  and  EUR 3/ap/yr,  respectively  (including 
depreciation,  interest,  maintenance  and  all  other  operating  costs,  such  as  energy)  [  589, 
Netherlands 2010 ]. The same range of annual extra costs is reported by the UNECE guidance 
document on 'Options for ammonia mitigation' whereas the cost efficiency is equal to EUR 2 to 
EUR 3 per kg of NH3-N reduced [ 508, TFRN 2014 ].  

Driving force for implementation 
No information provided. 

Example plants 
The technique is applied in Spain and the Netherlands.  

Reference literature 
[ 188, Spain 2010 ] [ 273, BE Flanders 2010 ] [ 379, Spain 2009 ] [ 508, TFRN 2014 ] [ 589, 
Netherlands 2010 ] 

4.7.5.5 

Scraper for frequent slurry removal (in case of a fully or partly 
slatted floor) 

Description 
See Section 4.7.1.5. Concrete slats are used for fattening pigs. 

Achieved environmental benefits 
See Section 4.7.1.5. A study carried out in Denmark regarding growing/finishing pigs showed 
no difference in ammonia emissions between systems with scrapers and a slurry system which 
was emptied regularly by a vacuum system [ 500, IRPP TWG 2011 ]. 

Cross-media effects 
See  Section  4.7.1.5.  From  the  previously  mentioned  Danish  study,  it  was  also  observed  that 
odour  emissions  are  higher  in  systems  with  scrapers  compared  to  a  slurry  system  which  was 
emptied regularly by a vacuum system [ 500, IRPP TWG 2011 ]. 

Environmental performance and operational data 
In the ILF BREF [ 43, COM 2003 ], the ammonia reduction achieved for systems equipped with 
a partly slatted floor and a scraper was 40 % (concrete slats) to 50 % (metal slats).  

The  manure removal  frequency  in fattening  pig  houses  with a  partly  slatted  floor,  as reported 
from  Germany,  is  once  to  twice  per  day  [  192,  Germany  2010  ].  A  possible  influence  of  the 

Intensive Rearing of Poultry or Pigs 

455 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

design of the slatted floors on the performance of this technique is also reported (transverse slats 
are considered to perform better) by Denmark [ 500, IRPP TWG 2011 ].  

Technical considerations relevant to applicability  
See Section 4.7.1.5.  

Economics 
No information provided. 

Driving force for implementation 
See Section 4.7.1.5.  

Example plants 
See Section 4.7.1.5.  

Reference literature 
[ 43, COM 2003 ] [ 192, Germany 2010 ] [ 500, IRPP TWG 2011 ] 

4.7.5.6 

Frequent slurry removal by flushing (in case of a fully or partly 
slatted floor) 

Description  
See  Section  4.7.1.9.  A  combination  with  a  convex  floor  with  separate  slurry  and  manure 
channels is shown in Figure 4.60 (see also Section 4.7.5.10). 

Source [ 42, Netherlands 1999 ] 

Figure 4.60:  Convex floor in combination with a gutter system 

The technique of flushing channels having a permanent slurry layer is also used in Italy for the 
management  of  slurry  in  external  channels  that  run  adjacent  to  the  external  walls  (see 
Figure 4.61). See also Section 4.7.2.7 and Section 4.7.5.7. 

456 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 292, Italy 2001 ] 

Figure 4.61:  Partly slatted floor and external alley with the flushing of a permanent slurry layer in 

channels underneath  

Achieved environmental benefits 
See  Section  4.7.1.9.  A  40 %  ammonia  emission  reduction  is  reported  for  the  flushing  gutters 
technique when applied in fattening pig houses [ 508, TFRN 2014 ]. 

Cross-media effects 
See Section 4.7.1.9. 

Environmental performance and operational data 
Emission  data  from  frequently  flushing  channels  equipped  with  gutters  or  tubes  or  having  a 
permanent slurry layer with aerated slurry or no aerated slurry are presented in Table 4.133. 

Table 4.109:  Ammonia  emissions  from  fattening  pig  houses  with  frequent  slurry  removal  by 

flushing  

Variant 

Floor 

FSF 
PSF concrete slats 
PSF metal slats 

Gutters/tubes  
Gutters/tubes  
Gutters/tubes 
Channels with 
permanent slurry layer 
Channels with 
permanent slurry layer 
(1) Elaboration based on data from the ILF BREF (2003). 
(2) Comparison with a system with a FSF and deep pit. 

FSF 

PSF 

2.1 

1.5 

NH3 emission (1) 

Non-aerated 
slurry 

Aerated 
slurry 
kg/animal place/year 
1.35 
0.9 
NI 

1.8 
1.2 
1 

1.35 

1.2 

NH3 emission reduction (2) 
Aerated 
Non-aerated 
slurry 
slurry 

(%) 

40 
60 
67 

30 

50 

55 
70 
NI 

50 

60 

NB: NI = no information provided. 
Source: [ 43, COM 2003 ] [ 292, Italy 2001 ] [ 42, Netherlands 1999 ] 

According to the data of the ILF BREF [ 43, COM 2003 ], in housing systems consisting of a 
partly slatted floor and separate manure and water channels, the energy consumption levels for 
flushing  gutters  are  reported  to  be  1 kWh  to  1.5  kWh  per  pig  place  per  year  for  flushing, 
5.1 kWh  per  pig  place  per  year  for  liquid  separation  and  7.2 kWh  per  pig  place  per  year  for 
aeration (13.8 kWh per pig place per year in total). Overall energy requirements for houses with 
a  fully  slatted  floor  and  flushing  gutters  range  from  18.5 kWh  per  pig  place  per  year  (no 

Intensive Rearing of Poultry or Pigs 

457 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

aeration) to 32.4 kWh per pig place per year (aeration). For flushing channels in  partly slatted 
floor systems with a permanent slurry layer, the energy requirements are reported to be between 
21.7 kWh per pig place per year (no aeration) to 38.5 kWh per pig place per year (aeration).  

A  study  carried  out  in  France  showed  that  the  system  with  a  fully  slatted  floor  and  flushing 
gutters or flushing tubes allows the reduction of ammonia emissions, compared to the reference 
system,  only  at  the  beginning  of  fattening  period.  The  emission  levels  are  equivalent  or  even 
higher in the second half of the fattening period (finishing) [ 261, France 2010 ]. 

Technical considerations relevant to applicability 
See Section 4.7.1.9. 

Economics 
The  extra  annual  cost  reported  for  new  houses  equipped  with  flushing  gutters  in  comparison 
with fully slatted floor systems with a deep pit are estimated at EUR 10–15 per animal place and 
the cost efficiency at EUR 10–15/kg of NH3-N reduced [ 508, TFRN 2014 ].  

For other designs, no information is provided.  

Driving force for implementation 
See Section 4.7.1.9. 

Example plants 
See Section 4.7.1.9. 

Reference literature 
[ 42, Netherlands 1999 ] [ 43, COM 2003 ] [ 261, France 2010 ] [ 292, Italy 2001 ] [ 508, TFRN 
2014 ] 

4.7.5.7 

Reduced manure pit (in case of a partly slatted floor) 

Description 
A partly slatted floor with a narrow manure pit. The manure pit is equipped with concrete slats. 
For the system using an external slatted alley, see Figure 4.38. 

Achieved environmental benefits 
The  reduction  of  the  emitting  surface  area  reduces  ammonia  emissions.  A  15 %  to  20 % 
ammonia emission reduction is reported [ 508, TFRN 2014 ]. 

Cross-media effects 
For partly slatted floors, heat stress and defecation on the solid part have to be avoided. 

Environmental performance and operational data 
Reported  emission  data,  concerning  ammonia  and  methane,  are  summarised  in  Table 4.110. 
From  Spain,  a  42 %  ammonia  reduction  was  measured  for  group  housing  of  fattening  pigs  
[ 196, Spain 2010 ]. 

458 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 4.110:  Emissions from housing systems for fattening pigs with a reduced manure pit 

Chapter 4 

Animal category 

Fattening pigs, solid concrete 
floor and fully slatted external 
alley with storage pit  
Fattening pigs, partly slatted floor 
with concrete slats, manure 
removal at the end of the cycle, 
maximum width of the pit 0.60 m 
(1) Measured data. 
NB: NI = no information provided. 

NH3 emission 
kg/ap/yr 

CH4 emission 
kg/ap/yr 

Source 

2.4 

NI 

[ 292, Italy 2001 ] 

0.89–1.69 (1) 

0.9–1.82 (1) 

[196, Spain 2010 ] 

Technical considerations relevant to applicability 
In France, this system is used outdoors with wider channels (about 1.2 m). It is used for specific 
programmes against trichinellosis, with individual control before departure for slaughter.  

Economics 
No extra cost in comparison with a fully slatted floor system with a deep pit is reported for new 
houses  [  508,  TFRN  2014  ].  Extra  costs  for  the  implementation  of  the  technique  in  existing 
houses (i.e. narrowing of the manure pit by reforming a fully slatted floor with a deep pit to a 
partly slatted floor with one third solid floor) are reported by Spain and given in  Table 4.111, 
including the cost efficiency of the technique. Any additional emission reduction due to frequent 
manure removal is not taken into account.  

Table 4.111:  Calculated  extra  costs  for  installing  a  reduced  manure  pit  in  existing  houses  with  a 

fully slatted floor, in Spain  

NH3 emission 
reduction (%) 
30  

Extra cost (EUR/place 
per year) 
3.61–4.33 

Extra cost (EUR/t pig 
produced) (1) 
12.3–14.7 

Extra cost (EUR/kg 
NH3 reduced) 
3.8 

(1) Calculated on the basis of an annual production of 294 kg of pig meat per place. 
Source: [ 379, Spain 2006 ] [ 338, Piñeiro et al. 2009 ] 

Driving force for implementation 
Partly slatted floors are considered to improve animal welfare.  Emission reduction is possible 
for new houses without extra costs in comparison to a deep pit with a fully slatted floor. 

Example plants 
In  2001  in  Italy,  40 %  of  growers/finishers  were  kept  in  houses  with  an  external  slatted  alley 
[ 292, Italy 2001 ].  

Reference literature 
[ 196, Spain 2010 ] [ 292, Italy 2001 ] [ 338, Piñeiro et al. 2009 ] [ 379, Spain 2009 ] [ 508, 
TFRN 2014 ] 

4.7.5.8 

Kennel or hut housing (in case of partly slatted floor) 

Description 
See Section 4.7.1.10. The pen design is similar to the one illustrated in Figure 4.52 for weaners. 
The defecating areas are situated on the short sides of the pen. The covered lying area is situated 
along the width of the pen. Another design is shown in Figure 4.62 with the activity and feeding 
area  over  a  slatted  floor.  Slurry  is  reported  to  be  removed  at  the  end  of  the  cycle  (overflow 
channel). 

Intensive Rearing of Poultry or Pigs 

459 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 190, Germany 2010 ]  

Figure 4.62:  Kennel housing system for fattening pigs  

Achieved environmental benefits 
See Section 4.7.1.10.  

Cross-media effects 
See Section 4.7.1.10.  

Environmental performance and operational data 
For  fattening  pigs,  the  potential  for  ammonia  emissions  is  approximately  35 %  lower  in 
naturally  ventilated  houses  than  in  forced  ventilated  houses  with  fully  slatted  floors  
[  575,  UBA  Germany  2011  ].  From  the  Netherlands,  a  reduction  of  36 %  is  reported  for  the 
technique, compared to the fully slatted floor system, corresponding to an ammonia emission of 
1.9 kg NH3 per pig place per year [ 547, IMAG-DLO 2001 ]. 

Ammonia  emissions  for  naturally  ventilated  kennel  housing  for  fattening  pigs  are  given  at 
  emissions  are  estimated  at  0.24 kg/ap/yr  and  odour  emissions  at 
2.4 kg  NH3/ap/yr.  PM10
6.5 ouE/s/animal  [  190,  Germany  2010  ].  In  the  following  table,  data  concerning  energy 
consumption and labour requirements are presented. 

Table 4.112:  Consumption and labour requirements for kennel housing systems for fattening pigs 

Bedding 

Electricity 

Fuel 

kg/ap/yr 
0 

kWh/ap/yr 
2.5 (2–3) 

kWh/ap/yr 
0 

Source: [ 190, Germany 2010 ]  

Cleaning 
water 
l//ap/yr 
75 (60–90) 

Labour 

h/ap/yr 
1 

460 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
In naturally ventilated kennel systems in Germany, fattening pigs are kept in large groups of up 
to 60 animals. The solid floor covers 50 % of the floor area. The reported available space per 
animal, applied in Germany, is 1.1 m2/fattening pig.  

Chapter 4 

Technical considerations relevant to applicability 
See Section 4.7.1.10.  

Economics 
Pig  fattening  in  naturally  ventilated  houses  requires  greater  investments,  which  means  higher 
houses  
fixed 
[  575,  UBA  Germany  2011  ].  Additionally,  the  system  requires  a  greater  surface  area  per 
animal. 

compared  with 

ventilated 

expenses 

slatted 

forced 

floor 

fully 

For new houses, the investment costs for naturally ventilated houses with a partly slatted floor 
and kennels are reported from Germany to be to EUR 470 per animal place. The corresponding 
total annualised costs are EUR 51 per animal place per year [ 190, Germany 2010 ]. The total 
additional costs of the technique in fattening pig housing, in comparison with a forced ventilated 
fully slatted floor house, are EUR 11 per animal place per year, which is equivalent to EUR 9.18 
per  kg  of  NH3  removed,  in  comparison  with  forced  ventilated  fully  slatted  floor  housing  
[ 575, UBA Germany 2011 ]. 

In  addition,  more  labour  is  needed,  e.g.  for  the  cleaning  of  the  lying  kennels.  The  additional 
expenses generated by these factors, however, are compensated for by energy cost savings in the 
unheated naturally ventilated housing.  

Driving force for implementation 
See Section 4.7.1.10.  

Example plants 
See Section 4.7.1.10.  

Reference literature 
[ 190, Germany 2010 ] [ 547, IMAG-DLO 2001 ] [ 575, UBA Germany 2011 ] 

4.7.5.9 

Straw flow system (in case of a solid concrete floor) 

Description 
Pigs  are  reared  in  pens  with  solid  floors,  where  a  slightly  sloped  concrete  lying  area  and  an 
excretion area are clearly defined. Straw is provided to the animals daily, from a supply rack at 
the top  of  a  sloped  pen  or dispensed  from  bales  manually  dropped into the pen.  Pigs'  activity 
pushes  and distributes  the litter  down  the  pen's  slope  (4–10 %)  to  the  solid  manure collection 
aisle outside the pen (see Figure 4.63).  

In the so-called straw flow system, only a small part of the pen is soiled with excreta because 
the pigs only excrete in the rear of the pen and keep the lying area dry and clean. The excretion 
area  is  operated  as  a  straw-based  system  where  farmyard  manure  is  produced.  As  the  straw 
travels down the slope, it is mixed with excreta; the daily use of straw absorbs urine, avoiding 
wet open surface areas. The solid fraction of the manure is removed frequently (e.g. daily) from 
the manure collection channels with a scraper or manually, whereas there is a drainage system 
for the effluent from the manure which is removed at the end of each batch or can be pumped 
automatically from the manure passage to a closed tank. Alternatively, the excretion area can be 
fitted with a slatted floor to operate the system as a slurry-based system, since only low amounts 
of straw are added.  

Intensive Rearing of Poultry or Pigs 

461 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 519, Amon et al. 2007 ] 

Figure 4.63:  Design of the straw flow system for fattening pigs 

The ventilation is frequently natural (e.g. in the UK), with systems placed in houses with open 
fronts or  with curtains or vertical  wooden planks  not  butted together.  From  the  UK, it is also 
reported that the technique can be combined with kennels made of boards, curtains or bales of 
straw,  in  naturally  ventilated  houses  with  daily  manure  removal  and  with  long  straw  addition 
[535, UK 2011].  

Achieved environmental benefits 
The  absorption  of  urine  into  the  straw  and  the  collection  of  manure  in  the  adjacent  channel, 
which reduces the emitting surface, in combination with the frequent removal of manure from 
the dung channel, result in lower ammonia emissions. However, spreading of faeces and urine 
over  the  floor  may  enhance  NH3  volatilisation  in  place  of  promoting  microbial  nitrogen 
assimilation [ 590, Batfarm 2013 ]. The technique is efficient to reduce N2O and CH4 emissions 
due to the aeration of the manure during its management [ 590, Batfarm 2013 ]. 

Cross-media effects 
The frequent scraping of the manure, which is removed outside, may require the covering of the 
manure  store,  in  order  to  prevent  ammonia  and  greenhouse  gas  emissions  from  storage  
[ 519, Amon et al. 2007 ] [ 535, UK 2011 ]. 

There  is  an  associated  risk  of  straw  causing  blocked  slat  voids  and  slurry  channel  blockages  
[ 624, IRPP TWG 2013 ]. 

Environmental performance and operational data 
The length to width ratio of the pens is around 1.5 : 1 and the lying area to excretion area ratio is 
around  2 : 1,  to  induce  pigs  to  dung  in  the  rear  of  the  pen.  Sprinklers  are  installed  in  the 
excretion area, in order to avoid excretion on the lying area due to thermal stress in hot months  
[ 375, Philippe et al. 2007 ]. 

The reported straw consumption ranges from around 650 g/day per pig to as low as 50 g/day per 
pig,  which  is  sufficient  for  ensuring  animal  welfare.  With  such  small  amounts  of  fibres,  the 
excretion area can be fitted with slats or scrapers for the separation of the liquid fraction. Straw 
is normally provided in the form of long stems.  

Reported emissions from straw flow systems are presented in Table 4.113. 

462 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Table 4.113:  Emission levels from straw flow systems for fattening pigs  

Housing system 

NH3 

CH4 

N2O 

kg/ap/yr 

Source 

Chapter 4 

1.9 (1) 

2.1 (1) 

0.54 (1)  0.024 5 (1) 

[ 519, Amon et al. 2007] 

Frequent manure 
removal with a scraper 
(twice a day) 
Infrequent manure 
removal without a 
scraper in the channel 
Daily manual manure 
removal from the 
channel  
(1) Measured values. 
(2)  Value  calculated  from  a  measured  mean  daily  emission  of  13.3  ±  3.45 g/animal  per  day  for  NH3, 
8.88 g/animal/day  for  CH4  and  0.68  g/animal/day  for  N2O  and  for  a  typical  mean  rearing  period  of 
117 days and 3.14 cycles per year. 

(3.62–6.15) (1) (2)  3.26 (1) (2)  0.25 (1) (2)  [ 662, Philippe et al. 2007 ] 

[ 519, Amon et al. 2007 ] 

1.24 (1)  0.039 9 (1) 

4.89  

However, in a study in Belgium (Wallonia), this system showed ammonia emissions 2.7 times 
higher than a deep litter system using straw and, in addition, they were much higher compared 
to a conventional slurry system with slats, presumably due to the fast degradation of urea on the 
soiled surface of the pen, despite the separation of the liquid and solid fractions of manure and 
the storage of the liquid fraction (around a fifth of the total) in a closed tank. Moreover, daily 
manipulation  in  scraping  solid  manure  may  have  favoured  NH3  emissions  by  aeration.  In  the 
 emissions were measured but there was no difference in N2O emissions 
same study, lower CH4
in  comparison  with  a  fully  slatted  floor  system  with  slurry  removal  at  the  end  of  the  cycle  
[ 662, Philippe et al. 2007 ]. 

Technical considerations relevant to applicability  
This technique is applicable to existing plants already equipped with a solid concrete floor, but 
it may not be applicable to naturally ventilated plants located in warm climates.  

Driving force for implementation 
This system gives the benefit of a reduced need for surface area, straw, labour and for manure 
storage, combined with improved animal welfare, as it allows the pigs to express their natural 
behaviour such as rooting, chewing and manipulation. 

Economics  
No information provided.  

Example plants 
The  system  is  applied  in  many  different  Member  States,  in  particular  in  the  UK,  Belgium 
(Wallonia) and Austria. 

Reference literature 
[ 375, Philippe et al. 2007 ] [ 519, Amon et al. 2007 ] [ 535, UK 2011 ] [ 590, Batfarm 2013 ] 
[ 624, IRPP TWG 2013 ] [ 662, Philippe et al. 2007 ] 

4.7.5.10 

Partly slatted pens with a convex floor and separated manure and 
water channels 

Description 
See Section 4.7.1.6. The minimum available surface area provided on the solid floor is 0.30 m2 
per  fattening  pig.  The  manure  channel  has  a  width  of  at  least  1.10  metres.  The  maximum 
emitting surface per animal, in the manure channel, is reportedly between 0.18 m2 and 0.27 m2. 
If  two  slanted  plastic  walls  are  placed  in  the  manure  channel,  the  emitting  surface  can  be 

Intensive Rearing of Poultry or Pigs 

463 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

reduced  further  to  0.11  m2  per  pig.  A  maximum  of  37 %  of  slatted  floor  for  fattening  pigs  is 
reported. Slats over the manure channel are metal or concrete. 

The system can be combined with a flushing system or slanted walls in the manure channel.  

Achieved environmental benefits 
See Section 4.7.1.6. A 40 % ammonia emission reduction is reported for fattening pigs and this 
increases  to  60–65 %  when  combined  with slanted walls in  the  manure  channel  [  508, TFRN 
2014 ]. 

Cross-media effects 
See Section 4.7.1.6. 

Environmental performance and operational data 
Emissions are reported for the technique combined with the use of slanted walls in the manure 
channel and are summarised in Table 4.114. 

Table 4.114:  Emissions  of  housing  systems  equipped  with  a  convex  solid  floor  and  separated 

manure and water channels  

Housing system 
variation 

NH3 
kg/ap/yr 

PM10 
kg/ap/yr 

Odour 

ouE/s/animal  

Reference 

1.01 
(0.99–1.02) (1) 

Slanted walls, metal 
slats, emitting surface 
0.18 m2/animal 
Slanted walls, metal 
slats, emitting surface 
0.27 m2/animal 
Slanted walls, concrete 
slats, emitting surface 
0.18 m2/animal  
(1) Measured data. 
(2) Values derived from measurements. 
NB: NI = no information provided. 

1.2 

1.4 (2) 

0.153 

17.9 (1) 

[ 194, Netherlands 2010 ] 

0.153 

17.9 (1) 

[ 195, Netherlands 2010 ] 

NI 

NI 

[ 186, BE Flanders 2010 ] 

Technical considerations relevant to applicability  
See Section 4.7.1.6. 

Economics 
The extra annual costs in relation to a fully slatted floor system with a deep pit reported for new 
houses are EUR 2 per animal place and the cost efficiency is EUR 2 per kg of reduced NH3-N 
and  EUR 2–3  per  kg  of  NH3-N  reduced  when  combined  with  slanted  walls  at  the  manure 
channel [ 508, TFRN 2014 ]. 

Extra investment costs for the implementation of slatted pens with a convex floor and a manure 
channel  with  slanted  walls  are  reported  from 
to  range  between  
EUR 30 (concrete slats) and EUR 39 (metal slats) per animal place and the annual extra costs 
between  EUR  3  and  EUR  5  per  animal  place  per  year  respectively.  The  comparison  is  made 
with a housing system with a partly slatted floor with 60 % solid floor, a total available surface 
of  0.8 m2  per  fattening  pig  and  manure  channels  of  0.8 m  [  194,  Netherlands  2010  ]  
[ 195, Netherlands 2010 ] [ 589, Netherlands 2010 ].  

the  Netherlands 

In  Belgium (Flanders), the investment costs for implementing this technique (manure pit with 
water  and  manure  channels,  with  slanted  side  walls)  in  an  existing  housing  system  with 
880 animal places (operating with a fully slatted floor with a deep pit) are reported as EUR 344 
per  animal  place  for  partly  slatted  floors  or  EUR 168  per  animal  place  for  fully  slatted  floors  

464 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
[ 273, BE Flanders 2010 ] [ 274, BE Flanders 2010 ]. For newly built houses, the reported extra 
cost for implementing the above variation of the technique is in the range of EUR 86–109 per 
animal place for fully slatted floors [ 265, BE Flanders 2005 ]. 

Chapter 4 

Driving force for implementation 
See Section 4.7.1.6. 

Example plants 
In the Netherlands, this system has been implemented in most new buildings and modifications 
of existing houses. 

Reference literature 
[ 42, Netherlands 1999 ] [ 186, BE Flanders 2010 ] [ 194, Netherlands 2010 ] [ 195, Netherlands 
2010 ] [ 265, BE Flanders 2005 ] [ 273, BE Flanders 2010 ] [ 274, BE Flanders 2010 ] [ 508, 
TFRN 2014 ] [ 589, Netherlands 2010 ] 

4.7.5.11 

Manure collection in water 

Description  
See Section 4.7.4.13. 

Achieved environmental benefits 
See Section 4.7.4.13. 

Cross-media effects 
See Section 4.7.4.13. 

Environmental performance and operational data 
The system is under development for fattening pigs in France [ 500, IRPP TWG 2011 ]. 

Technical considerations relevant to applicability 
See Section 4.7.4.13. 

Economics 
No information provided. 

Driving force for implementation 
See Section 4.7.4.13. 

Example plants 
See Section 4.7.4.13. 

Reference literature 
[ 500, IRPP TWG 2011 ] 

4.7.5.12 

Slurry cooling 

Description 
Slurry cooling channels or slurry surface cooling fins can be used. See Section 4.7.1.7 for slurry 
cooling channels and Section 4.7.1.8 for slurry surface cooling fins. 

Achieved environmental benefits  
See Section 4.7.1.7 and Section 4.7.1.8. 

Cross-media effects 
See Section 4.7.1.7 and Section 4.7.1.8. 

Intensive Rearing of Poultry or Pigs 

465 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
Ammonia emission values achieved by the slurry cooling channels for different housing systems 
and cooling effect levels are presented in Table 4.115.  

Table 4.115:  Ammonia emission values achieved by slurry  cooling channels for different fattening 

pig housing systems and cooling effect levels 

Housing system 

Partly slatted floor (25–49 % solid floor), frequent 
removal by vacuum, no bedding 
Partly slatted floor (50–75 % solid floor), frequent 
removal by vacuum, no bedding 
Partly slatted floor, combined slurry and solid 
manure system with straw addition in the solid 
part, manure scraper 
Source: [ 160, Denmark 2010 ] [ 268, Denmark 2010 ] 

Cooling effect 

W/m2 

10 

Ammonia 
emissions 
kg NH3/ap/yr 

1.16 

1.52 

10–50 

2.2–2.6 

In Denmark, in fattening pig houses with partly slatted floors and scrapers in manure channels, 
the  assessed  maximum  ammonia  emissions  reduction  achieved  by  slurry  cooling  channels  is 
40 %  compared  to  a  conventional  house  with  a  fully  slatted  floor,  and  30 %  compared  to  a 
partly slatted floor [ 499, AgroTech 2008 ].  

Depending on the pen floor and system design, large variations in energy consumption may be 
observed. The energy requirements for the cooling channels technique for fattening pigs range 
between 21 kWh and 63 kWh per animal place per year depending on the cooling programme 
and the cooling surface of the partly slatted floor (see Table 4.116). 

Table 4.116:  Electricity  consumption  of  cooling  channels  in  partly  slatted  floors  by  the  cooling 

effect applied  

Pen design 

25–49 % solid floor  
50–75 % solid floor  
Source: [ 197, Denmark 2010 ] 

Cooling area per 
pig place 
m2 
0.47 
0.23 

10 W/m2  20 W/m2  30W/m2 

kWh/ap/yr 
42 
21 

21 
11 

63 
32 

From a farm for fattening pigs in Finland, where the slurry cooling  technique is implemented, 
but  also  where  additives  that  may  have  an  influence  on  emissions are  used in the  slurry,  it  is 
reported that ammonia and odour emissions are reduced by approximately 25 % compared with 
the  system  without  the  applied  measures.  Fuel  savings  are  reported  to  be  in  the  range  of  70–
80 %,  due  to  heat  recovery;  approximately  90 %  of  the  energy  used  for  heating  the  housing 
system  was  obtained  by  recovered  heat  from  slurry  cooling.  The  annual  fuel  consumption  is 
reported  to be  equivalent to 10 kWh per animal place per year, which roughly  corresponds to 
one  litre  of  oil  per  animal  place  per  year.  On  the  other  hand,  electricity  requirements  are 
reported as 60 kWh/ap/yr (the effect of energy-saving fans is also included in the value) [ 276, 
Finland 2010 ]. 

In a Danish study, in which cooling pipes were cast into the manure channels and the manure 
was scraped out daily, no reduction of odour emissions was observed [ 499, AgroTech 2008 ].  

From  the  Netherlands,  the  ammonia  emission  reduction  achieved  by  slurry  cooling  fins  is 
reported  to  range  between  50 %  and  60  %  in  partly  slatted  floor  systems  compared  to  fully 
slatted  floor  systems  with  a  deep  pit  and  the  associated  emission  factors  range  from  1.2 kg 

466 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

NH3/ap/yr (200 % cooling fins' surface/slurry surface and partly slatted floor with metal slats) to 
1.4 kg NH3/ap/yr respectively (170 % cooling fins' surface/slurry surface and partly slatted floor 
with metal slats or 200 % with concrete slats) [ 640, Netherlands 2013 ]. An ammonia emission 
reduction  of  45  %  is  reported  for  fattening  pig  houses  with  partly  slatted  floors  and  slurry 
surface cooling [ 508, TFRN 2014 ]. 

For slurry cooling fins applied to partly slatted floors, the extra energy consumption is estimated 
as 10 kWh per fattening pig place per year [ 589, Netherlands 2010 ].  

Technical considerations relevant to applicability 
See Section 4.7.1.7 and Section 4.7.1.8. 

Economics 
In  Denmark,  the  cooling  channels  technique  is  reported  to  have  lower  maintenance  costs, 
compared with surface cooling fins. 

From  Denmark,  the  extra costs for  the implementation  of  the cooling  channels  technique  in  a 
fattening pig house operating with a vacuum system are reported to vary in the range of EUR 0–
6.8  per  animal  place  per  year,  or  from  EUR -0.4  to  EUR 1.7  per  pig  produced,  meaning  that 
there will be a surplus if all heat is reused elsewhere in the production.  

The  effect  on  costs  of  heat  utilisation  for  different  levels  of  slurry  cooling  (temperature 
reductions)  applied  to  a  housing  system  for  fattening  pigs,  with  a  50–75 %  solid  floor  is 
illustrated in Figure 4.64. It shows that slurry cooling for the abatement of ammonia emissions 
is profitable when the system converts more than 50–60 % of the recovered energy from slurry 
pits into heating energy for other purposes.  

Source: [ 197, Denmark 2010 ] 

Figure 4.64:  Effect on costs of heat utilisation for different levels of slurry cooling  

From  a  farm  with  3 000  fattening  pigs  in  Finland,  the  reported  extra  investment  costs  are 
equivalent  to  EUR 100/ap/yr,  including  the  cost  of  energy-saving  fans  and  the  heat  pump  
[ 276, Finland 2010 ]. 

Intensive Rearing of Poultry or Pigs 

467 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The extra investment costs for implementation of surface cooling fins are calculated as EUR 27 
to EUR 35 per animal place and the extra annual costs as EUR 5 to EUR 6 per animal place (see 
Table 4.78).  An  extra  cost  of  EUR  5  to  EUR 7  per  animal  place  per  year  for  new  buildings 
equipped with partly slatted floors and  surface cooling fins and a cost efficiency of EUR 4 to 
EUR 6 per kg of NH3-N reduced are reported [ 508, TFRN 2014 ].  

Driving force for implementation 
See Section 4.7.1.7 and Section 4.7.1.8. 

Example plants 
See Section 4.7.1.7 and Section 4.7.1.8. 

Reference literature 
[  160,  Denmark  2010  ]  [ 197,  Denmark  2010  ]  [ 268,  Denmark  2010  ] [  276,  Finland  2010 ] 
[ 499, AgroTech 2008 ] [ 508, TFRN 2014 ] [ 589, Netherlands 2010 ] [ 640, Netherlands 2013] 

4.7.5.13 

Full litter system (in case of a solid concrete floor)  

Description 
Pigs are kept in one large pen or two smaller ones at both sides of the house with a central alley 
in between used for feeding and control. The solid floor is covered by an organic layer usually 
made  of  straw  or  lignocellulosic  materials  (e.g.  sawdust).  The  organic  layer  absorbs  urine, 
incorporates  faeces  and  provides  the  animals  with  the  opportunity  to  express  their  natural 
exploratory  behaviour.  Two  basic  systems  are  typically  used  for  solid  concrete  floor  houses: 
'deep litter' and 'littered-floor' (see Section 2.3.1), depending on the amount of bedding material 
and the way it is managed, as well as on the manure removal frequency. 

Littered-floor systems may be enhanced with outdoor yards; this configuration is mandatory in 
Germany in organic farming. 

In  the  deep  litter  system,  bedding  is  spread  every  week  and  manure  is  removed  by  front-end 
loaders at the end of the rearing period or after more cycles. In the littered-floor system, litter 
spreading and removal is carried out weekly in the indoor area and twice a week in the yard.  

Generally,  the  main  objective  of  the  technique  is  to  keep  the  bedding  dry  and  clean.  The 
abundance  of  bedding  also  provides  protection  against  low  temperatures.  A  schematic 
representation of a housing system with a solid concrete floor with litter is given in Figure 4.65.  

468 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 548, TWG ILF 2002 ]  

Figure 4.65:  Pens with a solid concrete straw-bedded floor and natural ventilation 

Littered-floor  or  deep litter  floor  houses  for  fattening  pigs  are  mostly  naturally  ventilated.  An 
exception is reported for deep litter systems, where a thin sawdust layer is used as bedding; in 
this case, closed buildings with forced ventilation are normally used [420, Ramonet 2003 ].  

In pens with the deep litter system, the feeding area can be placed on a raised level in relation to 
the bedded defecating areas.  

In  both  types  of  litter  management  (deep  litter  and  littered-floor),  automatic  feeding  and 
drinking systems are used. In general, 20–40 animals are housed per pen; the space provided per 
animal for the deep litter configuration is 1.1 m2 and for the littered floor with an outdoor yard it 
is 1.5 m2/animal (0.5 m2 in the yard and 1 m2 in the house).  

Achieved environmental benefits 
Odour  emissions  are  reduced  compared  to  slurry-based  housing  systems,  if  the  system  is 
managed according to the best agricultural practices (e.g. supply of enough bedding material). 

Energy  requirements  are  reduced  because  straw,  in  conjunction  with  naturally  ventilated 
housing systems, allows the animals to self-regulate their temperature with less ventilation and 
heating.  The  production  of  solid  manure  instead  of  liquid  manure  (slurry)  is  considered  an 
advantage  due  to  the  organic  matter  content  of  the  litter.  Organic  matter  incorporated  in  the 
fields  improves  the  physical  characteristics  of  the  soils,  reducing  run-off  and  the  leaching  of 
nutrients to water bodies. 

According  to  some  authors  [  289, MLC  2005  ]  [  530,  Nicks  et  al. 2003  ], the  NH3  emissions 
arising from deep litter systems and from slatted floors are identical.  

Cross-media effects 
Increased dust emissions are reported. In general, in the case of poor management of the litter, 
ammonia,  odour  and  nitrous  oxide  emissions  are  expected  to  be  higher  than  from  housing 
systems based on slurry. The composting process that may take place in the litter is associated 
with  higher  NH3  and  N2O  emissions  (up  to  1.5–3  times  higher  compared  to  slurry-based 
systems) [ 261, France 2010 ].  

Intensive Rearing of Poultry or Pigs 

469 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Methane emissions are considered to be low, unless anaerobic conditions prevail in the bedding 
material. Methane emissions are reduced if, in a deep litter system, the litter is used only for one 
batch [ 530, Nicks et al. 2003 ]. It is also reported that deep litter with sawdust produces lower 
NH3 and CH4 emissions than straw litter, but higher N2O emissions [ 530, Nicks et al. 2003 ]. 
Management requirements for the littered-floor system are increased, since regular littering and 
cleaning  of  the  yard  are  necessary.  A  more  difficult  control  of  sanitary  risks  is  also  reported 
from France and Denmark [ 500, IRPP TWG 2011 ].  

Animal growth performance is generally affected. The average daily feed intake is reduced by 
8 % and, at the same time, the average daily gain is reduced by 3 % and the food conversion 
ratio is reduced by 7 %. Finally, the carcass quality is slightly affected: fat and lean thickness at 
loin  eye  depth  (positions  G2  and  M2)  are  increased  by  1.3 mm  and  reduced  by  2.8  mm, 
respectively  [  261,  France  2010  ].  However,  overall,  the  growth  rate  of  animals  is  not 
significantly affected and the worst performance observed in litter-based farms, in comparison 
with slurry-based farms, is attributed partly to the specific type of production (higher age and 
weight at slaughter) [ 329, CORPEN 2003 ]. Other studies have found no significant differences 
in  the  performance  and  carcass  quality  of  pigs  housed  on  fully  slatted  floors  in  straw-based 
housing [ 289, MLC 2005 ].  

Due to the higher nitrogen losses during storage and application of solid manures (by ammonia 
volatilisation and denitrification), there is a higher loss of fertiliser value compared to a slurry-
based housing system; consequently, the use of mineral fertilisers may increase.  

Environmental performance and operational data 
It  is  expected  that  the  use  of  straw  will  allow  pigs  to  control  the  temperatures  themselves  in 
systems where insulated kennels or creeps are not used, thus requiring no additional energy for 
heating. The system requires cleared concrete areas in summer at feeding places for the pigs to 
cool  down.  If  a  covered  lying  area  is  present,  the  litter  quantity  needs  to  be  adjusted  to  the 
temperature and the cover must be removed at high temperatures. 

Emissions from fattening pig houses have been measured under various conditions of bedding 
material and management of the litter and are summarised in Table 4.117. Emissions due to the 
external yard have not been estimated [ 181, Germany 2010 ]. 

470 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Table 4.117:  Emission levels from housing systems with full litter for the rearing of fattening pigs  

Type of litter 

NH3 

CH4 

N2O 

PM10 

kg/ap/yr 

Odour 
ouE/s/animal 

Deep litter with 
straw, natural 
ventilation  

4.2 (1) 
(1.0–6.0) (2) 

1.6–18.0 (2)  0.6–3.7 (2)  0.32 (1) 

3.9 (3) (4) 

Source 

[ 193, Germany 
2010] 
[ 474, VDI 
2011 ] 

Chapter 4 

Deep litter with 
straw, forced 
ventilation, removal 
of litter after three 
consecutive batches, 
addition according 
to cleanliness (5) 
Deep litter with 
straw, removal at 
the end of cycle  

Littered floor with 
straw, weekly 
removal 

4.58–5.12 
(2) 

1.87–2.78 
(2) 

0.01–0.79 
(2) 

NI 

NI 

[ 530, Nicks et 
al. 2003 ] 

4.46  
(4.24–4.67) 
(6) (1) 

2.43 (1)  
(1.0–5.0) (2) 

NI 

NI 

NI 

NI 

0.8–2.8 (2) 

NI 

0.32 (4) 

6.5 (7) (4) 

[ 375, Philippe 
et al. 2007 ] 

[ 191, Germany 
2010 ]  
[ 474, VDI 
2011 ] 

5.65–7.53 
(2) 

Deep litter floor 
with sawdust or soft 
wood particles, 
mechanically 
ventilated, removal 
at the end of cycle 
(8)  
(1) Values derived from measurements. 
(2) Measured data. 
(3) Value calculated from an emission of 30 ouE/s/LU and an average weight for fattening pigs of 65 kg.  
(4) Values derived by expert judgement based on conclusions by analogy. 
(5) Calculations were made from measured data reported in g/head per day, for 120 days' rearing and 3.14 cycles a 

[ 531, Ramonet 
et al. 2002 ] 

NI 

NI 

NI 

NI 

year. 

(6) Value calculated from a measured mean daily emission measurement of 12.1 ± 0.6 g/animal per day for NH3 and 

for a typical mean rearing period of 117 days and 3.14 cycles per year.  

(7) Value calculated from an emission of 50 ouE/s/LU for an average weight for fattening pigs of 65 kg.  
(8) Calculations were made from measured data reported per animal place and for 3.14 cycles a year. 
NB: NI = no information provided. 

The amount of straw or other bedding material varies for different animal categories. For deep 
litter floors, the amounts of applied straw are approximately 1–1.2 kg per fattening pig per day, 
or  275–400 kg/animal  place  per  year 
apply  
250–300 kg/ap/year [ 624, IRPP TWG 2013 ]. For littered-floors, the amount of straw is in the 
range  of  250–300 kg/animal  place  per  year 
in  Germany,  while  UK  farms  apply  
125–150 kg/ap/year (see summary of resources demand in Table 4.118).  

in  Germany,  while  UK 

farms 

A  summary  of  resource  requirements  as  reported  from  Germany,  for  the  two  variants  of  the 
technique, is presented in Table 4.118. 

Intensive Rearing of Poultry or Pigs 

471 

 
 
 
 
 
Chapter 4 

Table 4.118:  Resource  requirements  associated  with  deep  litter  and  littered-floors  applied  to 

fattening pigs housing systems (1) 

System 

Deep litter 

Electricity  Bedding material  Water 
l/ap/yr 
kWh/ap/yr 
120 
8 (2) 
100–180 

kg/ap/yr 
350 
275–400 

Fuel 
kg/ap/yr 

Source 

NI 

[ 193, Germany 2010] 

Littered floor 
combined with 
yard 
(1) Data refer to open, non-insulated buildings, naturally ventilated, with solid concrete floors for fattening pig 

275 
250–300 

115 
90–140 

3 
2.5–4 

[ 191, Germany 2010] 

0 

housing (28–118 kg). 

(2) Energy breakdown (kWh/ap/yr): feeding: 1; manure removal/cleaning: 4.8; lighting: 2. 
NB: NI = no information provided. 

From France, it is reported that in deep litter systems when thick sawdust bedding (from 60 cm 
to 80 cm) is used, the average requirement for sawdust is about 60 kg per fattening pig, when 
only  the  surface  layer  is  removed  and,  consequently,  the  deep  layer  can  be  used  for  several 
fattening periods. In thin sawdust bedding, the thickness of the litter is reduced to approximately 
20  cm,  and  then  the  average  requirement  will  be  30 kg  per  animal.  When  straw  is  used,  the 
average requirement per pig is 70 kg for the deep litter system and 45 kg for the littered-floor 
system [ 329, CORPEN 2003 ]. 

Sawdust  bedding  should  be  replaced  at  least every  two  successive  batches, in order to reduce 
ammonia emissions [ 530, Nicks et al. 2003 ]. The substitution of straw with other types of litter 
is done for similar amounts of dry matter [ 531, Ramonet et al. 2002 ] [ 532, Nicks et al. 2002 ].  

The average characteristics of the solid manure, produced with the use of straw and sawdust as 
bedding  material,  are  presented  in  Table 4.119,  based  on  experimental  datasets  gathered  in 
France for fattening pigs in deep litter. 

Table 4.119:  Average characteristics of solid  manure produced by deep litter housing systems for 

fattening pigs, in France 

Unit 

Straw 

Sawdust 

Type of bedding 

Quantity of bedding used 

kg/pig 

Quantity of produced manure 

kg/pig 

62.2 ± 15.4 (mixed) 
54.4 ± 14.2 (dry) 
202 ± 52 (mixed) 
61 ± 14 (dry) 

58.1 ± 21.8 (mixed) 
40.5 ± 11.7 (dry) 
141 ± 44 (mixed) 
53 ± 18 (dry) 

Manure composition 
Dry matter 
Total N 
Ammoniacal N 
P 
K 
Source: [ 329, CORPEN 2003 ] 

 % 
g/kg of manure 
g/kg of manure 
g/kg of manure 
g/kg of manure 

30.5 ± 8 
9.7 ± 1.9 
1.4 ± 0.7 
3.6 ± 1.5 
11.6 ± 3.9 

37.5 ± 6.3 
7.7 ± 2.5 
1.2 ± 0.7 
4.2 ± 1.6 
11 ± 3.9 

Technical considerations relevant to applicability 
In  houses  with  natural  ventilation,  the  technique  may  not  be  applicable  to  houses  located  in 
regions  with  warm  climates.  The  system  can  be  applied  in  all  new  housing.  For  existing 
housing, this technique may be applicable in buildings with solid concrete floors. Design details 
will vary. The scarcity of bedding materials in some geographical areas may be a limitation to 
the use of these systems. 

472 

Intensive Rearing of Poultry or Pigs 

Chapter 4 

Economics 
Investment  costs  are  reported  from  Germany  as  EUR 400  per  animal  place  for  the  deep  litter 
system, which corresponds to an annualised investment cost of EUR 40/ap/yr, and EUR 454 per 
animal place for the littered floor with yard.  

Straw  prices  and  bedding  availability  vary  considerably  from  area  to  area,  inducing  different 
economic  results.  Examples  of  extra  costs,  in  comparison  with  the  fully  slatted  floor  system 
with a deep pit, as reported from Spain are shown in Table 4.120. 

Table 4.120:  Extra costs for implementation of straw littered housing systems for fattening pigs in 

comparison to a fully slatted floor system with a deep pit 

Type of litter 

Type of house 

Extra costs (1) 
(EUR/ap/yr) 

Littered system with weekly 
replacement of bedding and 
two functional areas  
(1) Extra costs include the cost of construction of a store (60 m2) for manure until landspreading. 
Source: [ 379, Spain 2009 ] [ 338, Piñeiro et al. 2009 ] 

Existing houses 

36.51–42.07 

20.16–25.72 

New houses 

Extra costs (1) 
(EUR/tonne pig 
produced) 
124.2–143.1 

68.6–87.5 

From the UK, the extra cost of production in a straw-based housing system, in comparison with 
a  fully  slatted  floor  system,  was  measured  as  approximately  EUR 34  per  tonne  of  pig  meat 
produced  (EUR 1  =  GBP 0.88),  due  to  the  increased  labour  input  and  the  requirement  for 
bedding material [ 289, MLC 2005 ]. 

In  Denmark,  even  though  this  system  is  less  expensive  than  a  traditionally  insulated  house 
operating  with  slurry,  other  economic  factors  do  not  favour  the  implementation  of  littered 
housing systems, such as: 











extra operating cost for purchasing straw;

poorer growth performance;

difficulty in controlling certain diseases;

extra labour requirements;

reduced utilisation of nitrogen (lower fertiliser value which will result in the need to use
1.1 kg of additional nitrogen from mineral fertilisers to compensate for the loss of 1 kg of
nitrogen from the manure as compared to the use of slurry).

Concerning  all  these  aspects,  an  extra  cost  of  at  least  EUR 10  per  pig  produced  is  added  for 
Danish conditions [ 500, IRPP TWG 2011 ]. 

Driving force for implementation 
Improved  animal  welfare  due  to  the  comfort  provided  by  the  straw  and  the  increased  space 
available per animal is a driver. The energy requirements are also lower in the case of natural 
ventilation.  

Example plants 
In  France,  around  5 %  of  the  fattening  places  were  using  littered  housing  systems  in  2008. 
Furthermore,  the  use  of  deep  litter  systems  with  straw  or  thin  sawdust  bedding  is  increasing 
compared to the littered-floor systems with straw and the deep litter system with deep sawdust 
bedding [ 261, France 2010 ].  

Intensive Rearing of Poultry or Pigs 

473 

Chapter 4 

Reference literature 
[ 39, Germany 2001 ] [ 157, Germany 2010 ] [ 181, Germany 2010 ] [ 185, Germany 2010 ] 
[ 191, Germany 2010 ] [ 193, Germany 2010 ] [ 261, France 2010 ] [ 289, MLC 2005 ] [ 291, 
IRPP TWG 2002 ] [ 292, Italy 2001 ] [ 329, CORPEN 2003 ] [ 338, Piñeiro et al. 2009 ] [ 375, 
Philippe et al. 2007 ] [ 379, Spain 2009 ] [ 420, Ramonet 2003 ] [ 474, VDI 2011 ] [ 500, IRPP 
TWG 2011 ] [ 519, Amon et al. 2007 ] [ 530, Nicks et al. 2003 ] [ 531, Ramonet et al. 2002 ] 
[ 532, Nicks et al. 2002 ] [ 548, TWG ILF 2002 ] [ 624, IRPP TWG 2013 ] 

4.7.5.14 

Littered external alley (in case of a solid concrete floor)  

Description 
The system combines an indoor solid concrete floor with no litter and a littered external alley. A 
small door allows the pigs to go out to defecate in an external alley with a concrete floor that is 
covered with straw (0.3 kg straw per pig per day) and that has a slight slope (4 %) that ends in a 
manure  alley  with  a  scraper  (see  Figure 2.23).  By  moving  around  in  the  external  alley,  the 
animals push the straw with the manure into the lateral channel. All the manure falls into the 
channel  and  is  scraped  one  step  down,  and  once  a  day  it  is  scraped  onto  a  manure  belt.  The 
lateral channel is fenced off, allowing space for the sludge to pass. 

A scraper removes the sludge (3–7 kg solid matter per pig per day) to a solid manure heap. The 
sludge  is  moved  along  a  channel  that  has  a  perforated  area  just  before  where  the  sludge  is 
dragged upwards towards the manure heap and this allows most of the fluid to be drained. The 
manure  heap  itself  is  also  drained,  and  the  liquid  is  collected  (approximately  0.5–2  litres  of 
liquid per pig per day) in a suitable basin underneath the storage. 

Achieved environmental benefits 
A reduction in ammonia emissions of 20 % to 30 % is achieved compared to the fully slatted 
floor system. 

Cross-media effects 
The energy use of the system is about 6 kWh operating 0.5 hours per day in a housing unit for 
450 pigs (2.43 kWh/animal place/year). Odour might be a problem if not enough straw is used 
[ 291, IRPP TWG 2002 ]. 

Environmental performance and operational data 
Ventilation  is  natural  and  operated  manually.  Automatic  (phase)  feeding  and  watering  is 
applied.  Heating  is  not  required.  A  reported  associated  emission  factor  is  2.4  kg  NH3/animal 
place/year. 

Technical considerations relevant to applicability 
Systems with an external alley are not applicable in cold climates. In France, this system is used 
for  specific  programmes  against  trichinellosis,  with  individual  control  before  departure  for 
slaughter. 

The use of litter on the solid floor inside the house is not recommended for Italian heavy pigs 
because they are normally fed with liquid feed, and the litter becomes too moist in a very short 
time.  Using  litter  only  in the  external  alley  prevents this  negative  effect and at the same  time 
maintains the solid manure production. The solid manure is landspread where it has a positive 
effect on soil structure.  

Economics  
The costs for implementing and running this system are not expected to differ significantly from 
those given in Section 4.7.5.13.  

Example plants 
One farm in Italy (Reggio E. – Maccacani farm). 

474 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Reference literature 
[ 291, IRPP TWG 2002 ] [ 292, Italy 2001 ] 

Chapter 4 

4.7.5.15 

V-shaped manure belts (in case of a partly slatted floor) 

Description 
V-shaped  manure  belts  roll  inside  the  manure  channels  of  partly  slatted  pens,  covering  the 
whole  channel  surface,  so that  all  faeces  and  urine  are  dropped  onto  them.  Belts  are  made  of 
plastic, polypropylene or polyethylene and operate frequently (at least twice a day) to separately 
discharge urine and faeces from the animal house to closed manure storage. 

Manure belts can fit channels in partly slatted pens with an inclined solid floor (4.5–5 °) at the 
front of the pen or with a convex solid floor with two manure channels at the front and at the 
back of the pen. The housing system is generally designed to provide a surface area in the pen in 
the range of 0.75–1 m2 per animal place, of which at least 0.30 m2 per animal should be solid. 

In farms using this technique, one or two floors are possible in the  house. Proper operation is 
monitored by the rotation frequency of the manure belts.  

Source: [ 199, Netherlands 2010 ] 

Figure 4.66:  Schematic plans and sections of housing systems equipped with V-shaped belts 

Intensive Rearing of Poultry or Pigs 

475 

Chapter 4 

Achieved environmental benefits 
The  system  allows  a  notable reduction  of  ammonia  and  odour  emissions  due  to  the  daily 
separate  removal  of  urine  and  solid  manure,  by  means  of  the  V-shaped  belt,  compared  to  a 
conventional house. 

Cross-media effects 
The system requires slightly increased energy consumption, to operate the manure belts. 

Cleaning  of  the  belts  is  needed  after  each  production  round.  A  maintenance  contract  is  also 
reported as necessary, for a complete check of the belts and the whole equipment at least once a 
year.  

If the equipment breaks down, then manure and urine accumulate rapidly, making the service 
more difficult and complex. In this case, alternative arrangements are necessary for the housed 
pigs [ 624, IRPP TWG 2013 ]. 

Environmental performance and operational data 
Reported emissions are shown by surface in Table 4.121. 

Table 4.121:  Emissions  associated with the use of  the V-shaped  belt system  in  partly slatted floor 

systems 

Available surface area per pig 

Ammonia 
kg/ap/yr 

Methane 
kg/ap/yr 

N2O 
kg/ap/yr 

Odour 
ouE/s/animal 

0.8 m2, of which 0.3 m2 is solid 
floor 
1 m2, of which 0.3 m2 is solid 
floor 
Source: [ 198, Netherlands 2010 ] [ 200, Netherlands 2010 ] 

1.05 

1.20 

0.94 

0.11 

5.9 

With this technique, ammonia emissions measured in the Netherlands are 58–70 % (depending 
on the area per pig) lower than from a conventional housing system with a deep pit below the 
slatted floor, while odour emissions are 74 % lower in comparison with the standard emission 
factor used in the Netherlands for fattening pig houses (23 ouE/s/animal).  

Technical considerations relevant to applicability 
The  technique  is  applicable  to  both  fattening  pig  farms  and  sow  farms.  However,  it  is  only 
suitable for new buildings.  

Economics 
The  total  costs  of  the  technique  (including  investment  costs,  electricity  and  gas  costs  and 
manure  management  costs)  have  been  calculated  in  comparison  with  a  conventional  housing 
system; the results show an annual cost benefit equivalent to approximately EUR 8 per animal 
place for a house with one floor, and EUR 10 for a house with two floors due to the following 
reasons: 







476 

In the Netherlands, separated urine has lower management costs than slurry. An average
slurry generation of 1.1 m3 per animal place per year is assumed.

The  lower investment costs  reported for  the  system,  in  comparison  with  a conventional
house,  are  due  to  the  higher  share  of  steel  among  the  materials  for  construction  of  the
system and are based on early 2007 prices. If steel prices rise by 25 %, then an additional
cost  of  EUR 0.8  per  animal  place  for  the  house  with  a  single  floor  and  EUR 1.35  per
animal place for the house have to be considered.

In the house  with two floors, energy costs are lower, because the heat from the bottom
floor partly heats up the top floor.

Intensive Rearing of Poultry or Pigs 

Detailed  investment  and  annual  costs  reported  from  the  Netherlands,  in  comparison  with  a 
conventional system for growing/fattening pigs are presented in Table 4.122, including the case 
of a house with two floors. 

Chapter 4 

Table 4.122:  Investment and operating costs for partly slatted floor systems with V-shaped manure 

belts, compared to conventional houses, in the Netherlands 

PSF with  
V-shaped manure 
belts (one floor) 
2 160 

Animal places 
Investment costs, VAT included 
(EUR/ap) 
Annualised investment cost (1) 
(EUR/ap/yr) 
Electricity and gas costs 
(EUR/average present pig) 
Manure management costs 
(EUR/average present pig) 
Total costs 
(1) Costs include buildings plus devices. 
 Source: [ 609, UR Wageningen 2007 ] 

436 

50.26 

6.9 

14.08 

71.24 

Conventional 
house 

2 160 

501 

55.91 

6.9 

16.5 

79.31 

PSF with  
V-shaped manure 
belts (two floors) 
4 320 

423 

48.02 

3.5 

14.08 

65.6 

Conventional 
house 

4 320 

467 

52.19 

6.9 

16.05 

75.9 

Driving force for implementation 
The direct separation of urine and the solid part of the manure is an advantage. This system has 
been designed in the Netherlands, where the pressure on the environment from livestock rearing 
is considered excessive, hence the system is seen as a way to improve the sustainability of pig 
rearing.  

Example plants 
This system is in use in two Dutch farms. 

Reference literature 
[  198,  Netherlands  2010  ]  [  199,  Netherlands  2010  ]  [  200,  Netherlands  2010  ]  [  609,  UR 
Wageningen 2007 ] [ 624, IRPP TWG 2013 ] 

Intensive Rearing of Poultry or Pigs 

477 

Chapter 4 

4.8 

Techniques for the reduction of emissions to air within 
housing 

4.8.1 

Introduction 

Emissions  to  air  arise  from  the  bedding  and  manure  that  are  kept  inside  livestock  houses. 
Techniques are in use to improve the indoor air quality and remove air pollutants before they are 
released  from  the  housing.  At  the  same  time,  an  improvement  of  the  animals’  living 
environment  and  the  working  conditions  is  attained  as,  mainly,  excessive  heat  and  dust  are 
removed.  

In  general,  it  can  be  expected  that  all  process-integrated  measures  for  the  reduction  of  dust 
emissions  contribute  to  the  prevention  of  epizootic  diseases  and  the  reduction  of  bioaerosol 
emissions [ 474, VDI 2011 ]. 

These techniques are presented separately from the end-of-pipe techniques that treat air as a last 
step  before  releasing  it  to  the  environment  (see  Section 4.9).  Techniques  presented  in  this 
section do not include those concerning the housing systems or techniques that achieve emission 
abatement by changing the properties of manure and, in this way, have an effect on the whole 
chain  of  manure  management,  e.g.  slurry  acidification.  Techniques  presented  in  the  next 
sections  are  mostly  ‘secondary’  measures,  being  additional  processes  that  do  not  change  the 
fundamental operation of the core process and that, in general, are characterised by a low level 
of complexity. 

4.8.2 

Ionisation  

Description 
The negative air ionisation system consists of two units. A high-voltage unit is used to convert 
the AC of the power supply system to a DC at -30 kV and a low amperage of below 2.0 mA to 
ensure safety. The unit is connected to a system of wires (discharge electrodes or ion generators) 
with needle-shaped pins that run along the length of the house, underneath the ceiling surface. 
The high voltage on the wires creates an electrical field between the wires and the ceiling and 
any other grounded surfaces (e.g. a grounded collection plate). The electrons emitted from the 
pins move over the field towards the ceiling, thereby charging negatively dust particles that are 
encountered,  which  are  then  directed  towards  the  grounded  plates  and  are  collected  by 
electrostatic attraction on grounded room surfaces or collector plates. The deposited fine dust is 
removed after each growing cycle by normal cleaning (see Figure 4.67).  

Source: [ 377, Netherlands 2010 ] 

Figure 4.67:  Effect of dust attraction caused by ionisation on the roof of a poultry shed 

478 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
The indoor dust concentration and dust emissions are reduced.  

Cross-media effects 
Increased energy use is necessary to supply the high-voltage unit. Care has to be taken to ensure 
that the model of ioniser does not release significant quantities of ozone. 

Environmental performance and operational data 
Fine  dust  emissions  are  reduced  by  36 %  for  PM10  and  10 %  for  PM2.5  fractions  during  the 
whole  broiler  growing  period  [  137,  Netherlands  2010  ];  with  average  concentrations  of 
1.01 mg/m3  and  0.07 mg/m3  for  PM10  and  PM2.5,  respectively  [  569,  UR  Wageningen  2009  ]. 
Reported  values  for  dust  emissions  per  broiler  place  per  year  are  0.0117–0.0201 kg  for  PM10 
and 0.00058–0.00142 kg for PM2.5 [ 137, Netherlands 2010 ]. 

The minimum current intensity from the high-voltage power supply is 1.3 mA. At least 0.45 m 
of discharge electrodes are placed per square metre of ground area. The minimum height of the 
discharge electrodes is 2.5 m above the floor. The minimum distance to the grounded surfaces is 
0.2 m. The roof and equipment in the housing should be grounded to prevent the accumulation 
of electrostatic voltage. Emitters cannot be installed under fans or ventilation channels.  

Adequate safety measures need to be applied. The installation needs to be made to the highest 
professional standards and checked by an expert before connecting to the power source. Weekly 
control is needed to maintain the correct functioning. 

Technical considerations relevant to applicability 
The technique may not be applicable to pig plants or to existing poultry houses due to technical 
and/or economic reasons. 

Economics 
Investment costs for the acquisition of the necessary equipment (source of ionising radiation and 
200 m of wire with emitters), for treating a surface of approximately 450–600 m2 in a fattening 
pig house, is reported as approximately EUR 2 000. The corresponding annual operating costs, 
including higher energy consumption, were reported as approximately EUR 8 per animal place 
[ 154, Czech Republic 2010 ].  

For broilers, in the case of a Dutch farm with 90 000 bird places, the extra investment costs per 
animal  place  are  reported  as  EUR 0.65,  while  the  annual  operating  costs  are  EUR 0.01  per 
animal place. After amortisation (7 years) of the extra investment costs, the total annual extra 
cost is calculated as about EUR 0.1 per animal place [ 503, Vermeij 2011 ]. 

Driving force for implementation 
Workers and animals can enjoy better conditions because of the lower dust concentration. The 
abatement of dust concentration also reduces the transportation of airborne transferable diseases. 

Example plants 
The technique is in use on two Dutch farms for broiler production, where extra measurements 
are carried out for validating the effective reduction of dust emissions.  

Reference literature 
[  137,  Netherlands  2010  ]  [  154,  Czech  Republic  2010  ]  [  377,  Netherlands  2010  ]  [  503, 
Vermeij 2011 ] [ 569, UR Wageningen 2009 ] 

Intensive Rearing of Poultry or Pigs 

479 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.8.3 

Water fogging 

Description 
Water is sprayed by nozzles at a high pressure to produce fine droplets that fall by gravity to the 
floor, moistening dust particles of a similar size that become heavy enough to drop as well. At 
the same time, indoor air is cooled as water droplets absorb heat and evaporate. The frequency 
of the water injections is controlled by the ambient temperature or by the relative humidity.  

At  a  droplet  size  of  up  to  around  10 micrometres  size  (reached  at  a  pressure  of  70–100 bar), 
evaporation takes place very quickly, so that walls or animals are not moistened. The operation 
of these systems at a lower pressure (7–17 bar) produces a misting effect with the spraying of 
droplets of around 200 micrometres size.  

Achieved environmental benefits 
Dust  emission  reduction  is  achieved.  Odour  and  ammonia  emission  reduction  is  possible  by 
limiting  the  dispersion  of  dust  particles,  to  which  odorous  compounds  are  attached,  and  by 
lowering  indoor  temperatures.  However,  positive  results  are  not  always  consistent  [  360, 
Boulestreau 2006 ]. 

Cross-media effects 
Water and energy consumption are increased. Fogging can have a significant impact on energy 
consumption, in  particular at  the  start  of  the  poultry  rearing  period.  At  the  end of  the  rearing 
period for solid manure systems, when the nitrogen excretion is significant, it can provoke high 
ammonia  and  odour  emissions  due  to  excessive  fogging  or  the  big  droplets  applied  
[  624,  IRPP  TWG  2013].  In  addition,  moist  bedding/litter  needs  to  be  avoided  as  this  may 
impact negatively on animal welfare, especially for poultry. 

Environmental performance and operational data 
The abatement of pollution in the indoor air of fattening pig houses is achievable in the range of 
22–30 % for ammonia, 14–46 % for dust and 12–23 % for odour [ 261, France 2010 ].  

The water and energy consumption depends on the climatic conditions where the technique is 
also used for cooling the indoor housing environment. In tests carried out in France for 3 years, 
average consumption levels of 264 kWh for electricity and 17 m3 for water were measured for 
each summer period of 90 days in a gestating sow house with 100 places, where a compressor of 
1.1 kW was used for spraying 18 hours a day in a cycle of maximum length of 30 seconds.  

Tests  carried  out  in  fattening  pigs  after  the  installation  of  a  fogging  system  showed  that  a 
reduction  of  the  water  consumption  by  animals  of  about  0.5 litres  per  pig  per  day  can 
compensate  the  water  consumption  of  the  fogging  system  (about  70 litres  per  pig)  
[ 361, France 2010 ]. 

The  fogging  system  can  reduce  the  ambient  temperature  by  4 °C  to  7 °C  during  the  warmer 
hours of the day, whereas a traditional cooling system allows a maximum reduction of around 
4 °C [ 358, France 2010 ]. 

Technical considerations relevant to applicability 
The technique is applicable to new and existing  houses, for both pigs and poultry production. 
The applicability may be restricted for solid manure systems at the end of the rearing period due 
to high ammonia emissions. 

Animals  can  feel  a  thermal  decrease  during  fogging.  Therefore,  for  the  use  of  the  technique, 
care  must  be  taken  at  sensitive  stages  of  the animals'  life  and  with the  climatic conditions.  In 
cool  areas  with  high  humidity  levels,  maintaining  suitable levels  of  relative  humidity  without 
over-ventilating  heated  pig  houses  is  a  challenge,  in  order  to  avoid  the  risk  of  provoking 
respiratory problems in the pigs [ 624, IRPP TWG 2013 ]. 

480 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Economics 
Investment  costs  to  equip  fattening  pig  housing  are  as  low  as  EUR 3.8  to  EUR 6  per  animal, 
while  costs  per  sow  reach  EUR 10.  Table 4.123  compares  fogging  to  other  water  spraying 
techniques that are in use for the purpose of cooling the indoor environment. 

Chapter 4 

Table 4.123:  Parameters  and  performances  of  fogging  in  poultry  housing  compared  to  other 

cooling systems techniques  

Cooling system 

Use 

Investment 
(EUR/m2) 

Pressure 
(bar) 

Advantages  Disadvantages 

Water spraying 
of incoming air 

Medium-
pressure water 
fogging 

High-pressure 
fogging 

Pad cooling 

Not used with 
natural ventilation. 
Only for 
temperatures below 
35 °C 
When ventilation is 
natural, internal 
mixing of air is 
needed. 
 Temperature 
> 35 °C 
When ventilation is 
natural, internal 
mixing of air is 
needed. 
Temperature 
> 35 °C 

Not used with 
natural ventilation. 
Temperature 
> 35 °C 

Source: [ 354, ITAVI 2004 ] 

1.5–2 

3–5 

Low costs 

Low cooling 
effect, higher 
water 
consumption 

2.5–3 

20–70 

Good 
cost/efficiency 
rate  

Risk of 
moistening the 
litter, medium 
cooling effect 

5–8 

> 70 

5–8 

< 3 

Highly 
efficient and 
homogenous 
cooling 

High cooling 
efficiency 
behind the 
pad, low 
sensitivity to 
the water 
quality 

Sensitive to 
water quality  

Sensitive to 
pathogen 
development 

The  estimated  costs  for  the  application  of  a  fogging  system  to  a  standard  broiler  house  of 
1 000 m2 are presented in Table 4.124. 

Table 4.124:  Estimation of the annual operating costs for a fogging system 

Cost factor 

Consumption of resources 

Water consumption  
Maintenance 

Replacement parts 

Electric consumption 

100 m3 (EUR 0.76/m3) 
1 maintenance visit 
1  filter  per  year,  oil  for  pump  circuit,  nozzles 
maintenance, pump replacement parts every 3 years 
5 CV pump  
(EUR 0.05/kWh) 

Costs  
(EUR) 
76 
150 

150 

55 

NB: Data reported for a system operating 30 days for 10 hours/day in a standard broiler house of 1 000 
m2 in France. 
Source: [ 354, ITAVI 2004 ] 

For  an  amortisation  over  5  years,  the  total  annual  costs  (investment:  EUR 8/m2,  annualised 
investment  cost:  EUR 1.6/m2,  annual  operating  cost:  EUR 0.43/m2,  total  annual  costs: 
EUR 2.03/m2)  would  range  from  EUR 0.078  to  EUR 0.156  per  broiler  place  (animal  density 
from 13 to 16 birds/m2). 

Intensive Rearing of Poultry or Pigs 

481 

 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
The reduction of mortality, especially in poultry, and the improvement of fertility parameters in 
sows  are  the  most  significant  improvements  achievable  for  animal  productivity.  The  average 
improvement of fertility in mating/gestating sows in hot summers is  reported to be 10 % after 
the installation of a fogging system [ 358, France 2010 ]. 

In  hot  summers,  animal  mortality  due  to  heatstroke  causes  economic  losses  of  about  12 %  in 
chicken  rearing  and  6.5 %  in  turkey  rearing.  A  reduction  of  these  losses  by  about  90 %  for 
broilers and 80 % for turkeys can be achieved with fogging (for a temperature of 35 °C and a 
humidity level of 40 %) [ 354, ITAVI 2004 ].  

Example installations 
Fogging has also been reported to be used at latitudes as high as Finland where it is financially 
supported for improving animal welfare [ 144, Finland 2010 ]. 

Reference literature 
[ 144, Finland 2010 ] [ 261, France 2010 ] [ 354, ITAVI 2004 ] [ 358, France 2010 ] [ 360, 
Boulestreau 2006 ] [ 361, France 2010 ] [ 368, France 2010 ] [ 624, IRPP TWG 2013 ] 

4.8.3.1 

Misting of capturing and reactive agents  

Description 
The same equipment used for fogging is used. Specific hydrosoluble compounds are dispersed 
in  a  mist  through  diffusion  devices  operating  at  a  high  pressure.  Their  molecular  structure 
allows  them  to  capture  odorant  molecules  (gaseous  or  dust-conveyed),  to  inactivate  them  and 
eventually to transform them into their stable and non-odorant form. Dispersion in a mist also 
maximises the compounds' reactive surface in contact with the odorous substances to eliminate 
them,  or  to  transfer  them  from  the  gaseous  phase  to  the  liquid  phase;  in  this  way,  the 
biodegradation of the odorous pollutants is accelerated. 

Sprayed chemicals may have patented formulations. These products are formulated from active 
ingredients of plant origin and, from a chemical standpoint, the active substances are derivatives 
of carboxylic acids.  

Achieved environmental benefits 
Odours may be reduced.  

Cross-media effects 
Water consumption is increased. Documentation on the absence of environmental consequences 
or effects on animal or human health of the chemical compounds used was not provided for the 
drafting of this document. In general, chemical substances need to be registered and produced 
complying with the REACH regulation (Regulation 2006/1907 of the European Parliament and 
of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and 
Restriction of Chemicals). Producers are requested to certify the absence of cross-media effects 
on health and the environment. 

Environmental performance and operational data 
The  applied  amounts  are  adapted  to  the  rearing  conditions,  temperature  and  humidity.  The 
application in pig sheds can be done for example with diluted products at 1 % sprayed through 
nozzles with a capacity of 4 l/h, in treatments of 14 seconds at 6-minute intervals. For poultry, 
one example of dilution is 0.8 %, with spraying intervals of 30 seconds every 10 minutes.  

The reduction efficiency achieved for indoor ammonia concentrations is reported to be 79 % for 
a  fattening  pig  house,  and  90 %  for  a  broiler  farm,  with  final  NH3  concentrations  of  around 
2 ppm. Odours are reported no to be detected by experts within a range of 200–300 m around 
the buildings [ 279, Fefana 2010 ]. Achieved abatement efficiencies for a group of substances, 

482 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
monitored on the basis of their nature and odour in laboratory trials, are reported in Table 4.125. 
A complete olfactory measurement was not provided. 

Chapter 4 

Table 4.125:  Odour  abatement  efficiencies  achieved  by  misting  of  reactive  agents  in  laboratory 

trials  

Compound type 

Formula 

NH3 
Ammonia 
Hydrogen sulphide  H2S 
Trimethylamine 
Butyraldehyde 
Butyric acid 
Source: [ 279, Fefana 2010 ] 

(CH3)3-N 
C3H7-COH 
C3H7-COOH 

Odour threshold 
(mg/m3) 

20 
1×10-3–5×10-3 
0.5×10-3 
20×10-3–50×10-3 
4×10-3–50×10-3 

Abatement 
efficiency 
 (%) 
91.4 
54.0 
89.2 
50.2 
89.6 

Type of odour 

Pungent, irritant  
Bad egg 
Bad fish 
Apple 
Rancid butter 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
Costs per  animal produced have been reported, depending on the amount of atomised product 
needed per capita. Average costs are shown in Table 4.126. 

Table 4.126:  Estimates of average costs for the atomisation of patented odour-abating chemicals by 

animal produced  

Animal 
produced 

Fattening 
pigs 

Product consumption 

1 (0.25–1.5) g/day per pig 

Average  
operating cost 
(EUR/animal 
produced) 

No of 
cycles  

Average 
operating 
cost 
(EUR/animal) 

1.70 

3.14 

5.34 

in 

the 

Turkeys 

Broilers  

29.8 mg/day per broiler (25 kg per 
30 000  broilers) 
final 
4 weeks of rearing 
66.2 mg/day  per  turkey  (50 kg  per 
12 000 
final 
turkeys) 
9 weeks of rearing 
29.8 mg/day  per  duck  (25 kg  per 
18 000 ducks) in the final 10 weeks 
of rearing 
Source: [ 279, Fefana 2010 ] 

Ducks 

the 

in 

0.014 

6 

0.084 

0.071 

2.5 

0.18 

0.024 

8.6 

0.21 

The  installation  costs  and  operating  costs  are  largely  the  same  as  for  the  fogging  technique 
described in Section 4.8.3. 

Driving force for implementation 
The improvement of animal respiratory comfort results in an improved FCR and growth rate of 
the animal. 

Example plants 
Less than 10 farms for weaned pigs are reported to use this technique [ 384, Fefana 2011 ]. 

Reference literature 
[ 278, Fefana 2010 ] [ 279, Fefana 2010 ] [ 384, Fefana 2011 ] [ 360, Boulestreau 2006 ] 

Intensive Rearing of Poultry or Pigs 

483 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.8.4 

Oil spraying 

Description 
In  littered  houses,  pure  vegetable  oil  is  sprayed  on  the  bedding  by  nozzles  fitted  on  pipes. 
Circulating dust particles are bound to the oil drops and are collected in the litter. Also, a thin 
layer  of  vegetable  oil  is  applied  on  the  bedding,  thus  preventing  dust  becoming  airborne.  Oil 
spraying is also possible in pig houses with slatted floors as a mixture of water and around 3 % 
vegetable oil.  

Achieved environmental benefits 
The reduction of fine dust emissions is an achieved benefit.  

Cross-media effects 
Issues  concerning  contamination  from  oil  particles  are  still  unsolved.  Oil  residues  may  cause 
slippery floors or even fire hazards. The safety of animals and workers has to be demonstrated 
and the medium- to long-term potential for wall dirtiness is unknown [ 500, IRPP TWG 2011 ]. 
Also,  moist  or  sodden  bedding/litter  needs  to  be  avoided  as  this  may  impact  negatively  on 
animal  welfare,  especially  for  poultry.  The  application  of  an  oil  film  results  in  a  slightly  less 
loose  bedding  [  582,  Wageningen  NL  2009  ].  Additional  work  is  required  to  clean  the  oil 
residues from the walls and to clean the system itself. 

Environmental performance and operational data 
In broiler houses, less than 1 % of the oil droplets should be smaller than 10 micrometres size. 
Oil  should  be  spread  evenly  over  the  total  area  of  the  house.  Oil  and  air  are  sprayed 
simultaneously into the nozzles. Pipes and nozzles can be placed in the middle of the house or 
along the side walls (see Figure 4.68). There should be one nozzle per 28 m2 of living area. A 
minimum of 12 ml of oil per square metre should be spread once a day. Operators should keep 
out of the house during application. The system lifetime is around 10–15 years. The extra time 
required for cleaning after treatment is approximately equivalent to a quarter of the time needed 
for cleaning when no treatment is applied [ 582, Wageningen NL 2009 ]. 

Dust reductions of 54 % were achieved in the Netherlands for the PM10 fraction and 75 % for 
the PM2.5 fraction. In Denmark, the effect of low-pressure oil spraying (a mixture of water and 
3 %  rapeseed  oil  at  5 bar)  on  respirable  dust  was  investigated  in  farrowing  pens  with  partly 
slatted  floors  (where  spray  nozzles  were  placed  above  the  slatted  floor),  and  finishing  pig 
houses with fully slatted floors. At a spraying rate of 8 g of oil/day for farrowing sows and 2–
3 g  of  oil/day  for  finishers,  there  was  a  reduction  of  respirable  dust  emissions  of  40 %  for 
farrowing sows and 50 % for fattening pigs and a reduction of total dust emissions of 33 % for 
farrowing sows and 40 % for fattening pigs respectively. The dust concentration in the finisher 
unit on all days of measurement was less than 3 g/m3 [ 649, DAFC 1999 ].  

In Germany, dust absorption by sprinkling a mixture of oil and water is considered an effective 
technical measure in order to reduce dust emissions in both pig and poultry farms [ 474, VDI 
2011 ]. 

Technical considerations relevant to applicability 
The system can be easily fitted in new and existing pig and poultry houses. For poultry plants, 
the technique is only applicable to birds older than around 21 days. Oil spraying is better suited 
for  broilers  than  for  layers,  because  less  equipment  is  present  in  the  shed  that  could  become 
contaminated.  It  is  also  suitable for  turkeys  and  pullets  of  broiler  breeders  [  138,  Netherlands 
2010 ]. 

484 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 140, Netherlands 2010 ] 

Figure 4.68:  Schematic view of an oil spraying system 

Economics 
Extra costs were estimated in the Netherlands for common broiler and turkey housing systems 
and are presented in Table 4.127. 

Table 4.127:  Extra costs related to the technique of oil spraying in poultry housing 

Type of animal 

Extra 
investment 
(EUR/ap) 

Annualised 
extra 
investment 
(EUR/ap) 

Annual 
operating 
extra cost 
(EUR/ap) 

Total 
annual 
extra cost 
(EUR/ap) 

Total annual 
extra cost 
(EUR/produced 
animal) 

0.5 

Broiler, housing 
for 90 000 birds 
Turkey, housing 
for 20 000 birds 
Source: [ 503, Vermeij 2011 ] 

2.2 

0.09 

0.39 

0.09 

0.93 

0.18 

1.32 

0.026 

0.46 

Driving force for implementation 
Better working conditions due to lower dust concentrations are a driving force. The application 
of an oil film reduces personal dust exposure by 75 % to 95 %, which is an important advantage 
in comparison with the use of end-of-pipe techniques for cleaning the exhaust air, such as wet 
scrubbers [ 582, Wageningen NL 2009 ]. 

Intensive Rearing of Poultry or Pigs 

485 

 
 
 
 
 
 
 
 
 
Chapter 4 

Example plants 
The system is in use on two farms in the Netherlands. 

Reference literature 
[ 138, Netherlands 2010 ] [ 140, Netherlands 2010 ] [ 474, VDI 2011 ] [ 500, IRPP TWG 2011 ] 
[ 503, Vermeij 2011 ] [ 582, Wageningen NL 2009 ] [ 649, DAFC 1999 ] 

4.8.5 

Floating balls in slurry channels 

Description 
Balls half-filled with water and made of special plastic (e.g. high-density polyethylene) with a 
non-sticky  coating  float  on  the  surface  of  manure  channels  below  slatted  floors,  allowing  the 
reduction of the ammonia-emitting surface. The ball axis changes when faeces drop on it and 
the ball tilts to drop the dung into the slurry in the channel. When slurry is removed, the balls 
remain  in  the  pit  and  continue  floating.  The  balls'  diameter  is  around  225 mm.  A  schematic 
representation of the functioning principle of the technique is shown in Figure 4.69. 

Source: [ 583, Netherlands 2010 ] 

Figure 4.69:  Schematic representation of the functioning principle of floating balls 

Achieved environmental benefits 
The  emitting  surface  in  the  slurry  channels  is  notably  decreased  as  most  of  the  surface  is 
covered by balls, hence emissions are reduced.  

Cross-media effects 
Balls  have  to  be  disposed  of  at  the  end  of  their  useful  life.  Additional  work  is  needed  for 
cleaning the balls after each rearing cycle, if necessary. 

Environmental performance and operational data 
The  maximum  potential  reduction  of  the  emitting  surface  is  70 %  and  it  is  achieved  with 
18 balls per m2, which is the maximum number of balls that fit on 1 m2 of the manure surface. 
The manure level in the pit should not be kept too high, in order to allow free mobility of the 
balls that need to tilt when faeces are dropped on them. Similarly, during the manure removal, a 
sufficient level of slurry has to be left to allow the balls to continue to float. The maintenance of 
the  floating  balls  is  minimal  (no  real  costs),  although  it  is  recommended  to  regularly  check 
manure  adherence.  Balls  are  cleaned  after  each  rearing  cycle,  if  needed.  On  delivery,  the 
supplier should provide a certificate with at least the number and type of balls installed. 

Tests  carried  out  in  the  Netherlands  credit  this  system  with  an  average  ammonia  emissions 
reduction  of  28 %,  compared  to  the  same  housing  system  without  floating  balls.  Measured 
ammonia emissions after the application of this technique in fattening pig housing systems are 
reported to be equivalent to 2.3 kg NH3/ap/yr. In the case of a combination of the floating balls 
with the addition of 1 % benzoic acid, the ammonia emissions reduction is increased to 42 %. 

486 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The UNECE guidance document on 'Options for ammonia mitigation' indicates a 25 % emission 
reduction efficiency for the technique for all pig categories [ 508, TFRN 2014 ]. 

Technical considerations relevant to applicability 
This system fits every pig production type but at the moment has only been applied and verified 
for fattening  pigs.  This  system  fits in existing  pig  houses  equipped  with  pits that  do  not  have 
slanted walls (i.e. only applicable to pits with vertical walls). No particular specification of floor 
is  needed.  The  technique  is  not  compatible  with  channel  flushing  or  other  techniques  that 
remove all slurry from the pit. 

Economics  
Investment costs depend on the surface of the manure pit and, on average, are around EUR 31 
(excluding taxes) per fattening pig place (around 1 m2). Extra costs are reported as EUR 2 per 
animal place per year and the cost efficiency of the technique as EUR 4 per kg of NH3-N abated 
[ 508, TFRN 2014 ]. 

Driving force for implementation 
The system is easy to use. The technique of floating balls, as it is used in the Netherlands, can 
be used in combination with other ammonia-reducing measures, e.g. benzoic acid addition.  

Example plants  
In  2013,  approximately  10  housing  systems  in  the  Netherlands  were  equipped  with  floating 
balls, rearing around 4 000 fattening pigs. 

Reference literature 
[  213,  Netherlands  2010  ]  [  508,  TFRN  2014  ]  [  583,  Netherlands  2010  ]  [  584,  Netherlands 
2010 ] 

4.8.6 

Biological additives in poultry litter  

Description 
Biological additives are used to improve the quality of bedding. Additives consist of complexes 
of microorganisms containing Lactobacillus and Bacillus, a mixture of bacteria and mushrooms. 
The  process  of  organic  matter  degradation  is  modified  and  a  fast  humification  process  starts 
after  the  addition,  which  improves  the  physical  conditions  and  the  performance  of  the  litter 
(drier, low-emitting litter).  

Achieved environmental benefits 
Less  ammonia  is  emitted  into  the  air;  the  quality  of  the  indoor  environment  is  improved  
[ 368, France 2010 ]. The selected strains of microbes (Bacillus subtilis) included in the additive 
have a positive influence on the litter properties, according to their defined metabolic criteria. 
The physical status of the litter is improved and more nitrogen is bound in the humified form. 

Cross-media effects 
An increase in average nitrous oxide emissions has been observed, which is consistent with a 
drier litter [ 647, Rousset et al. 2012 ].  

Environmental performance and operational data 
The bedding inoculation is done at the beginning of the rearing cycle and no later than the tenth 
day of life of the chicks. 

Experimental  tests  were  carried  out,  on  the  basis  of  mass  balances,  comparing  treated  to 
untreated  litters.  Litters  treated  with  biological  additives  always  showed  a  higher  overall 
nitrogen content, whereas the portion of ammoniacal nitrogen was not increased (same or lower 
NH3-N/Ntotal ratio). This means that nitrogen is better linked and conserved in an organic form 
in  the  treated  litter.  The  C/N  ratio,  which  reflects  the  degree  of  degradation  of  the  organic 

Intensive Rearing of Poultry or Pigs 

487 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

matter, is as low as 10–15, in comparison with the level of 20–40 observed for untreated litter. 
Experimental data concerning the characteristics of treated and untreated litter are presented in 
Table 4.128 [ 502, Guinebert et al. 2005 ].  

Table 4.128  Composition of treated and untreated turkey manure  

Parameters 

Straw bedding 

Shavings bedding 

Type of litter 

Organic matter (% of DM) 
Total N (% of DM) 
NH3 (% of DM) 
C/N ratio 
Source: [ 502, Guinebert et al. 2005 ] 

Untreated 
40–50 
2–2.5 
0.5–0.8 
20–40 

Treated 
60–72 
5–6 
0.5–0.8 
8–15 

Untreated 
50–60 
2–3 
0.6–0.8 
20–40 

Treated 
60–75 
3.5–4.5 
0.1–0.3 
2–10 

The reduction in ammonia emissions, as a consequence of the litter treatment, is reported to be 
from 8.5 % to 36 %, as an average [ 501, Aubert et al. 2011 ] [ 647, Rousset et al. 2012 ]. The 
competition of the added bacteria with harmful microorganisms inside the litter enables a drastic 
reduction  of  the  population  of  microorganisms  such  as  enterobacteria  and  coliforms,  with  a 
consequent reduction of the risk of contamination of the birds [ 502, Guinebert et al. 2005 ]. A 
reduced  animal  mortality  of  about  27 %  (from  4.3 %  to  3.1 %)  has  been  recorded  
[ 501, Aubert et al. 2011 ].  

Technical considerations relevant to applicability 
These products are especially used for broiler and turkey rearing, spread or pulverised over the 
bedding.  

Driving force for implementation 
Litters are richer in nitrogen, which can be used efficiently in landspreading. Animal mortality 
and  pododermatitis  also  appear  to  be  reduced,  especially  during  a  long  rearing  period  
[  501,  Aubert  et  al.  2011  ]  [  647,  Rousset  et  al.  2012  ].  However,  there  is  no  regulatory 
framework adopted for manure additives in order to safeguard their performance. 

Example plants 
In France, the use of this technique is increasing in meat poultry production; one French farm 
has been using this technique since 1996. 

Reference literature 
[ 368, France 2010 ] [ 501, Aubert et al. 2011 ] [ 502, Guinebert et al. 2005 ] [ 647, Rousset et 
al. 2012 ]  

488 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
4.9 

End-of-pipe measures for the reduction of emissions to 
air from housing  

Chapter 4 

4.9.1 

Introduction 

The  treatment  of  the  exhaust  air  from  animal  houses  is  a  method  that  has  lately  gained 
importance  since  intensive  farming  needs  to  comply  with  stricter  regulations  and  emission 
limits.  Biofilters,  biotrickling  filters,  acid  scrubbers  and  multi-stage  air  cleaning  systems  are 
applied  as  an  end-of-pipe  technique  for  the  removal  of  certain  pollutants  such  as  ammonia, 
odour  and  dust  from  the  exhaust  air  of  animal  housing.  An  effective  reduction  of  dust  also 
reduces  the  emission  of  bioaerosols.  Air  cleaning  system  operate  on  the  basis  of  different 
physical,  biological  and/or  chemical  removal  principles.  They  also  differ  in  applicability  and 
removal  performance.  The  general  operating  principles  of  the  two  main  categories  of  air 
cleaning systems (wet scrubbers and biofilters) are briefly described in Section 2.4. 

The different air cleaning systems and their combinations in use are presented in Table 4.129, 
together  with  an  indication  of  their  applicability  to  the  various  animal  categories  and  their 
removal performances. 

Table 4.129:  Types  of  exhaust  air  cleaning  systems  in  animal  housing,  their  applicability  and 

Applicability 

Removal performance 

removal performance 

Type of air cleaning system 

Biofilter  

Biotrickling filter  

Acid scrubber  

Animal 
category 

Pigs  

Pigs 

Pigs, dry 
manure store 

Manure removal 
system 
Liquid manure system  
Solid and liquid manure 
system  
Solid and liquid manure 
system  

MULTI-STAGE AIR CLEANING SYSTEMS 
Two stages 

Water scrubber + acid scrubber  

Water scrubber + biofilter 

Acid scrubber + biofilter  

Acid scrubber + biotrickling filter  

All animal 
categories  
All animal 
categories 
All animal 
categories 
All animal 
categories 

Liquid and solid manure 
system  
Liquid and solid manure 
system  
Liquid and solid manure 
system  
Liquid and solid manure 
system  

Odour  NH3  Dust 

++ 

+ 

NS 

NS 

+ 

++ 

0/+ 

++ 

++ 

++ 

+ 

0/+ 

++ 

++ 

+ 

+ 

+ 

++ 

++ 

++ 

++ 

Three stages 
All animal 
Water scrubber + water scrubber + 
categories 
acid scrubber 
All animal 
Water  scrubber  +  acid  scrubber  + 
biofilter  
categories 
NB: NS= not suitable; 0 = conditionally suitable; + = suitable ++ = good; +++ = very good 

Liquid and solid manure 
system  
Liquid and solid manure 
system  

++ 

+++ 

+ 

+++ 

+++ 

+++ 

Source: [ 424, VERA 2010 ] 

Wet scrubbers are required in some Member States in order to comply with acceptable emission 
levels  for  ammonia,  PM10  and  odour,  particularly  in  densely  populated  areas,  in  regions 
characterised by a high animal density or in vulnerable natural protected areas (e.g. Natura 2000 
sites).  However,  they  are  still  considered  costly  installations.  Specific  emission  reduction 
efficiencies are usually associated with each type of air cleaning system.  

Achieved environmental benefits  
The  maximum  average  ammonia  removal  efficiency  that  can  be  achieved  with  the  different 
systems ranges from 70 % to over 90 %. In Germany, the required minimum removal efficiency 

Intensive Rearing of Poultry or Pigs 

489 

 
 
 
 
 
 
 
 
 
Chapter 4 

of air cleaning systems for ammonia and total dust is 70 % at any time. Ammonia separation is 
assessed with the aid of a nitrogen balance covering the entire production system. Dust removal 
efficiencies from 80 % up to more than 95 % are reported as achievable [ 514, KTBL 2008 ]. 

Odour  removal  is,  on  average,  30 %  for  acid  scrubbers  and  45 %  for  biotrickling  filters, 
although  wide  ranges  are  reported  for  individual  measurements,  since  the  efficiency  of  odour 
reduction  is  highly  dependent  on  the  raw  gas  concentration.  The  minimum  requirement  for 
odour  reduction  of  air  cleaning  systems  applied  in  Germany  is  defined  as  an  odour 
concentration  in  the  clean  gas  not  exceeding  300  ouE/m3  and  no  typical  process  odours  (e.g. 
animal house odour) are perceptible in the clean gas [ 514, KTBL 2008 ]. Odour intensity is a 
logarithmic  function  of  concentration.  Therefore,  a  90 %  removal  might  only  reduce  the 
intensity by around half [ 624, IRPP TWG 2013 ]. 

Environmental performance and operational data 
In  Germany,  the  Netherlands  and  Denmark,  air  cleaning  systems  are  officially  tested  and 
reduction  efficiency  factors  are  certified  for  the  removal  of  ammonia,  odour  and  dust  before 
being  implemented  on  the  farm.  In  order  to  harmonise  the  testing  procedures  and  facilitate 
acceptance  of  the  results  in  different  countries,  a  joint  initiative  of  parties  from  the 
aforementioned  Member  States  developed  a  standardised  protocol  for  testing  and  verifying 
different air cleaning systems: the 'Test Protocol for Air Cleaning Technologies'  [ 424, VERA 
2010 ]. Hence, by applying the test protocol, it is possible to fit a housing unit with an end-of-
pipe  technique  that  ensures  a  certain  level  of  ammonia,  odour  and/or  dust  emissions.  The 
assessment of the efficiency of air cleaning systems in animal housing is described in Section 
4.18.6. 

The maximum capacity of the scrubber in terms of airflow is designed in accordance with the 
maximum required airflow rate (warmer season) for the animals housed in the building, pen or 
compartment coupled to the unit. However, the airflow rate over the course of the year varies 
considerably,  depending  mainly  on  the  outdoor  temperature,  and  consequently  the  ventilation 
rate  is  only  running  at  maximum  capacity  for  a limited  time  over  the  year.  As  an  example,  a 
yearly average airflow  of around 50 % of the maximum capacity is reported for Germany.  In 
northern European coastal climates, for about half of the year the ventilation is applied at about 
25 % of capacity in pig houses. That means, if an air cleaning system is able to clean the first 25 
% of the maximum ventilation rate, then 100 % of the exhaust air is cleaned for about 50 % of 
the time during a year.  

The  example  given  in  Figure 4.70  reflects  the  strategy  of  partial  treatment  of  exhaust  air  at 
lower than the maximum ventilation capacity, for two different emission limit concentrations of 
ammonia  in  the  treated  air.  According  to  the  data  presented,  an  air  cleaning  system  with  a 
cleaning capacity at 50 % of the maximum ventilation capacity still enables around 70–80 % of 
ammonia removal, with 20–30 % of the total ammonia emissions to be vented untreated. This 
strategy  reduces  investment  and  operating  costs  but  hardly  affects  the  average  ammonia 
emission levels [ 13, Melse 2009 ] [ 55, Denmark 2010 ]. However, it may not be effective for 
the control of odour nuisance [ 624, IRPP TWG 2013 ]. 

490 

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Chapter 4 

Source: [ 626, Denmark 2010 ] 

Figure 4.70:  Ammonia removal efficiency as a function of the proportion of the treated air by the 

air cleaning system 

The highest odour removal efficiency of air cleaning systems is achieved by adjustment of  the 
design  and  operational  strategy.  Another  approach  is  that  of  multi-stage  scrubbing  systems, 
where each stage aims to remove one type of compound.  

The air that is treated in wet scrubbers typically leaves the systems with high levels of humidity, 
over 95 %. In order to avoid aerosol discharge,  droplet separators can be installed at the point 
where the clean air leaves the system [ 121, Germany 2010 ]. The generation of aerosols from 
these air cleaning systems raises concerns about the potential presence of Legionella. 

Technical considerations relevant to applicability  
An essential constraint for the implementation of air cleaning system is the centralisation of air 
extraction;  in  existing  buildings,  the  ventilation  configuration  does  not  always  permit  central 
ducting  of  exhaust  air.  Additionally,  air  cleaning  systems  significantly  increase  the  flow 
resistance  of  the forced  ventilation  system.  Therefore,  the  ventilation  system  must  be  planned 
and designed efficiently, which is relatively easy in newly planned houses as these requirements 
(i.e. channelling of the air to a single point, sufficiently powerful fans) can easily be taken into 
account at a reasonable cost [ 51, BE Flanders 2010 ]. 

Retrofitting  existing  houses  will  be  difficult  and  expensive  in  most  cases  as  the  ventilation 
system  is  rarely  adequate  to  support  a  scrubber  since  multiple  air  outlets  may  be  present  and 
flows might not be channelled to a single outlet point where the air could enter the scrubber. In 
addition,  the  design  and  capacity  of  the  installed  fans  might  not  meet  the  increased  capacity 
required to overcome the extra flow resistance that is inevitably introduced by the presence of a 
scrubber. Not only are the costs for the installation of air cleaning systems in existing houses 
normally significantly higher than those for the implementation of the same techniques in new 
houses,  but  the  operating  costs  are  also  expected  to  be  higher  (compared  to  new  housing), 
because of the difficult optimisation of the existing ventilation system. Air cleaning systems are 
not applicable to existing naturally ventilated houses. 

Intensive Rearing of Poultry or Pigs 

491 

 
 
 
 
 
 
 
Chapter 4 

In existing pig houses, separate air cleaning system may be also utilised to treat the exhaust air 
from each pen or compartment; in this way, the constraint of channelling the air extraction of 
the whole building can be overcome [ 261, France 2010 ]. 

Economics 
Investment  and  operating  costs  of  air  cleaning  systems  for  livestock  operations  are  generally 
high  and  this  limits  the  widespread  take-up  of  the  system  across  the  EU.  The  fixed  costs  are 
related to the air cleaning system size. Costs for energy use are notable, to run water pumps and 
to  overcome  the  increased  resistance  to  the  mechanical  ventilation  due  to  the  presence  of  the 
filters.  The  maximum  ventilation  capacity  is  of  great  importance  for  the  cost  of  air  cleaning, 
since  the  size  of  the  air  scrubber  is  proportional;  recommendations  for  maximum  ventilation 
capacity across Europe are not the same. 

Example plants 
An  example  of  the  locally  widespread  application  of  air  cleaning  techniques  can  be  found  in 
Germany  in  only  three  districts,  Cloppenburg,  Vechta  and  Emsland  of  Lower  Saxony,  where 
between  370  and  400  pig  farms  (around  17 %  of  all  pig  farms)  had  installed  air  abatement 
techniques  (as  of  2010).  Two  out  of  three  newly  built  houses  are  fitted  with  air  cleaning 
systems, of which 75 % are bioscrubbers and multi-stage devices and 25 % are biofilters [ 504, 
KTBL 2010 ]. 

The two main categories of air cleaning techniques (wet scrubbers and biofilters), applied alone 
or in combination within the sector for the intensive rearing of poultry or pigs, are presented in 
the following sections. 

Reference literature 
[ 13, Melse 2009 ] [ 51, BE Flanders 2010 ] [ 55, Denmark 2010 ] [ 121, Germany 2010 ] [ 261, 
France 2010 ] [ 424, VERA 2010 ] [ 504, KTBL 2010 ] [ 514, KTBL 2008 ] [ 624, IRPP TWG 
2013 ] [ 626, Denmark 2010 ] 

4.9.2 

Water scrubber 

Description 
The exhaust air from the housing is blown through a packed filter medium by transverse flow. 
Water is continuously sprayed on the packing material. The dust is taken up by water and settles 
in the water tank, which is emptied when full. No flushing with water is required. Water and air 
can  also flow in  the  same  direction. The  technique is  also used in  combination with  other  air 
cleaning systems in multi-stage scrubbers (see Section 4.9.6.2).  

Achieved environmental benefits 
Reduction of dust from the exhaust air is an environmental benefit of the technique. 

Cross-media effects 
The collected dust needs to be disposed of. Water requirements increase as well as the energy 
consumption for running the pumps. As a result of the relatively low pressure drop in the filter, 
the extra energy for ventilation is negligible. 

Environmental performance and operational data 
For a filter surface load of 4 300 m3/m2 per hour, and a thickness of the contact bed packing of 
0.6 m, the reduction of fine dust (PM10) is calculated in a pullet farm to be approximately 30 %. 
The reported average flow rate over the course of the year, in percentage of the maximum flow 
rate, is equivalent to 30 % [ 124, Netherlands 2010 ].  

Every  week  the  packing  material  should  be  controlled  for  blocking  by  dust,  as  should  the 
amount  of  circulating  water  to  be  sprayed  on  the  column.  The  packing  material  should  be 
cleaned once a year.  

492 

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Technical considerations relevant to applicability 
In existing plants, the system is applicable only where a centralised ventilation system is used. 
Where the ventilation system has multiple fans or multiple outlet points, the implementation is 
hardly practicable.  

Economics 
The  extra  costs  associated  with  the  implementation  of  water  scrubbers,  estimated  in  the 
Netherlands for poultry housing, are reported in Table 4.130. 

Table 4.130:  Extra costs related to water scrubbers in poultry housing 

Type of 
animal 

Housing 
capacity in 
animal places 
(ap) 

Extra 
investment 
costs 
(EUR/ap) 

Annualised 
extra 
investment 
costs 
(EUR/ap) 

Annual 
operating 
extra costs 
(EUR/ap) 

Total 
annual 
extra 
costs 
(EUR/ap) 

Total annual 
extra costs 
(EUR per 
animal 
produced)  

Pullets 

Laying  hens 
(aviary) 
Broiler 
grandparents 
Broiler 
breeders  

Broilers 

50 000 

40 000 

33 000 

19 000 

90 000 

2.32 

2.97 

3.34 

6.26 

3.26 

Turkeys 

20 000 

22.36 

Ducks 

40 000 

4.84 

Source: [ 503, Vermeij 2011 ] 

0.32 

0.41 

0.47 

0.87 

0.46 

3.15 

0.68 

0.33 

0.45 

0.48 

0.92 

0.46 

3.19 

0.70 

0.66 

0.86 

0.94 

1.79 

0.92 

6.34 

1.38 

0.25 

0.98 

0.46 

1.75 

0.134 

2.19 

0.21 

Driving force for implementation 
In the Netherlands, the incorporation of the system in new or existing farms makes it possible to 
grant  an  environmental  permit  in situations  where this  would  otherwise  not  be possible  under 
the  local  legislation,  due  to  exceeding  the  maximum  permissible  values  for  fine  dust 
concentrations. 

Example plants 
This  system  has  been  applied  in  the  Netherlands  since  2009,  where  several  farms  use  this 
technique. 

Reference literature 
[ 124, Netherlands 2010 ] [ 503, Vermeij 2011 ] 

4.9.3 

Bioscrubber (or biotrickling filter) 

Description 
This  is  a  packed  tower  trickling  filter  with  inert  packing  material  that is  normally  maintained 
continuously wet. Pollutant removal is achieved by means of absorption of the contaminants in 
the  liquid  and  breakdown  by  microorganisms  on  the  filter.  The  terms  bioscrubber  and 
(bio)trickling filter are used as synonyms.  

Contaminated  exhaust  air  is  passed  upwards  (counter-current  in  vertical  bioscrubbers)  or 
horizontally  (cross-current  in  horizontal  bioscrubbers)  over  the  filter  elements  which  are 
continuously  sprinkled  with  water.  Due  to  an  intensive  contact  between  air  and  water,  dust, 

Intensive Rearing of Poultry or Pigs 

493 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

ammonia  and  odour  contained  in  the  contaminated  air  are  absorbed  in  the  liquid  phase  and 
subsequently  degraded  by  microorganisms,  settling  on  the  filter  elements  as  a  biofilm.  The 
effluent is collected in a storage tank before being recycled back to the top of the scrubber. In 
this way, the biomass in the system grows partly as a film on the packing material of the filter 
and is partly suspended in the water that is recirculated [ 13, Melse 2009 ]. 

Ammonia  is  degraded  by  bacterial  conversion  into  nitrites  and  nitrates  (nitrification),  while 
odorous compounds are oxidised by bacteria to CO2, H2O and by-products; dust is dissolved in 
water.  Water  circulation  keeps  the  biolayer  moist  and  provides  the  nutrients  for  the 
microorganisms;  the  accumulated  nitrites  and  especially  nitrates  (which  may  be  toxic  to  the 
microorganisms)  are  discharged  with  the  scrubbing  water,  so  that  the  pH  remains  in  a 
favourable  range  (between  6.5  and  7.5)  for  microorganisms.  The  pH  is  determined  by  two 
counteracting processes: oxidation of NH3 reduces the pH value in the scrubbing water whereas 
NH3  input  causes  the  pH  value  to  increase.  For  this  reason,  a  pH  controller  is  often 
recommended with an acid metering system to maintain the pH value within the  target range, 
even in unfavourable operational conditions (such as starting up, excessive ammonia input and 
temperatures < 12 °C) [ 514, KTBL 2008 ]. 

The bioscrubber can be preceded by a simpler filtering stage to reduce dust and odour as a first 
step, which often is done by a ‘water curtain’, where a simple flush of water and air flow in the 
same  direction.  A  droplet  separator  can  be  installed  before  the  cleaned  air  leaves  the  system. 
The typical workflow of a bioscrubber is shown in Figure 4.71. 

Source: [ 121, Germany 2010 ] 

Figure 4.71:  Bioscrubber workflow 

Achieved environmental benefits 
Ammonia,  odour  and  dust  emissions  are  simultaneously  reduced.  The  odour  reduction  is 
effective for neutral compounds, as well as for odorous substances attached to dust particles.  

494 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
Increased energy use is required to operate the pumps for water circulation and to overcome the 
increased flow resistance for ventilation. In addition, water consumption is increased, as is the 
requirement to discharge waste water. A discharge of water up to 10 times higher than with a 
chemical  scrubber  may  result.  If  conditions  in  the  bed  media  are  not  properly  controlled, 
transient aerobic/anaerobic zones might risk N2O emissions formation.  

Environmental performance and operational data 
Ammonia  emission  reductions  between  70 %  and  90 %  have  been  reported.  Removal 
efficiencies  higher  than  90 %  have  been  measured  only  at  high  elutriation  rates  or  at  a  pH-
regulated and conductivity-controlled elutriation rate [ 121, Germany 2010 ] [ 129, Netherlands 
2010 ] [ 127, Netherlands 2010 ] [ 135, Netherlands 2010 ] [51, BE Flanders 2010 ].  

The  odour  reduction  strongly  depends  on  the  raw  gas  concentration;  the  average  achievable 
odour removal efficiency varies between 45 % and 76 %. The minimum requirement for odour 
reduction of air cleaning systems applied in Germany is defined as an odour concentration in the 
clean gas not exceeding 300 ouE/m3 and no typical process odours (e.g. animal house odour) are 
perceptible in the clean gas [ 514, KTBL 2008 ]. A removal of total dust of at least 70 % can 
usually be obtained, while the reduction of the PM10 fraction is reported to reach at least 70 %, 
and can be as high as 95 %, especially with the use of a dedusting filtering stage. 

A summary of the emission reductions achieved by applying bioscrubbing in pig production is 
shown in Table 4.131, as reported by different Member States. 

Table 4.131:  Emission reductions achieved by the application of bioscrubbers in pig production 

Achieved emission reductions 
(%) 

Ammonia 

Odour 

Total dust 

PM10 

Reference 

92 (1) 

76 (1) 

70 (2)–90 (2) 

90 (70–95) 

70 (50–90) (3) 

70–96 

NI 

80 

[ 665, Riis 2012 ] 

[121, Germany 2010]  

70 

45 

NI 

60 

[135, Netherlands 2010] 

(1) The level is achieved after two filters. 
(2) The level is achieved after three filters in summer. 
(3)  The  minimum  requirement  in  Germany  for  odour  concentration  in  the  clean  gas  is 

< 300 ouE/m3, which is comparable to a reduction efficiency of about 70 %. 

NB: NI = no information provided. 

Specific  emission  levels  achieved  with  the  application  of  bioscrubbers  are  presented  in 
Table 4.132, as reported by Denmark and the Netherlands.  

Intensive Rearing of Poultry or Pigs 

495 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.132:  Reported emission levels achieved with the application of bioscrubbers 

System 

NH3 
reduction 
efficiency  
(%) 

Animal category 

Ammonia 

PM10 

kg/ap/yr 

g/ap/yr 

Reference 

Bioscrubber 
with partial air 
treatment 

50–85 

Fattening pigs 

Bioscrubber 
with droplet 
separator (3) 

Bioscrubber (3) 

Weaners 
Farrowing sows 
Mating/gestating 
sows 
Fattening pigs 
Fattening pigs 
Laying hens 

70 

70–95 
70 

0.44 (100 % 
air cleaned) 

0.56 (60 % air 
cleaned) 

0.88 (20 % air 
cleaned)  

0.18–0.23 (1) 
2.5  

1.3  

NI 
NI 

NI 

0.8–1.1 (1)  
0.12–0.75 (2) 
0.095  

NI 
NI 
21–33 

NI 

[53, Denmark 2010] 

[ 135, Netherlands 
2010 ]  

[ 121, Germany 2010 ] 
[ 640, Netherlands 
2013 ]  
[ 644, Netherlands 
2014 ]  

70 

Broilers 

0.024 

5–9 

(1) The higher end of the range is with more space available per animal. 
(2) Values are calculated from a standard emission from the housing system of 2.9 kg/ap/yr. 
(3) Ammonia emission data listed are based on the implementation of an air cleaning system in the reference 

housing system in the Netherlands. 

NB: NI = no information provided. 

Energy  is  required  to  operate  pumps  for  water  circulation.  In  addition,  in  order  to  ensure  the 
requisite air rates, particularly in the summer, higher capacity fans with a higher specific power 
requirement  may  be  necessary  due  to  the  increased  flow  resistance.  Airflow  rates  related  to 
these systems are typically from 10 000 m3/h to 100 000 m3/h; volumes up to 255 000 m3/h are 
reported for farms with a capacity of 3 000 pigs.  

Electricity consumption is associated with modules of 1 000 m3/h of the installed capacity of the 
scrubbing  system  (around  11.8  pig  places  covered  at  a  flow  rate  of  85  m3/animal  place  per 
hour). On a yearly basis, the electricity consumption is around 12.7–15.3 kWh/animal place for 
the  system’s  requirements  (pumps,  control,  etc.)  and  11–20 kWh/animal  place  to  compensate 
for  the  additional  pressure  drop  required  to  operate  the  ventilation  system  (up  to  150 Pa  for 
biotrickling  beds)  [  121,  Germany  2010  ].  In  France,  for  a  bioscrubber  with  a  capacity  of 
150 000  m3/h  in  a  farm  with  2  100  fattening  pig  places,  it  is  necessary  to  install  a  pump  of 
3 kW, which is equivalent to an electricity consumption of 12.5 kWh/fattening pig place/year [ 
261, France 2010 ]. 

The  total  water  consumption  is  composed  of  the  required  water  discharge  and  the  quantity 
which  is  evaporated.  Evaporative  losses  range  between  5 litres  and  7  litres  per  1  000  m3  of 
treated  air.  In  general,  a  sufficient  discharge  of  the  contaminated  scrubbing  water  is  of  vital 
importance for the operational reliability and the removal efficiency of the bioscrubber [ 514, 
KTBL  2008  ].  For  example  in  Germany,  for  bioscrubbers  without  pH  control,  a  removal 
efficiency of at least 70 % for ammonia emissions is only achieved at an elutriation rate of 0.2–
0.3 m3 per kg of NH3 input which corresponds approximately to 0.6–0.9 m3 water discharge per 
animal  place  per  year  [  121,  Germany  2010  ]  [  514,  KTBL  2008  ].  Also  in  Germany,  water 
consumption in the range of 1.6–2.4 m3/pig place per year is reported for modern systems, with 
pH control (in order not to exceed a set pH value above which ammonia is released from the 
scrubbing water into the exhaust air), and elutriation based on water conductivity; otherwise the 

496 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

consumed volumes are higher. Furthermore, in Germany, around 0.3–0.4 m3 of waste water per 
fattening pig place per year are reported for systems equipped with pH control and elutriation 
based on water conductivity [ 500, IRPP TWG 2011 ]. In Denmark, the total water consumption 
per pig produced is estimated at around 0.25 m3 [ 53, Denmark 2010 ]. 

Data  concerning  total  water  consumption  and  the  amount  of  water  discharged  from  the 
scrubbing system are presented in Table 4.133 for different farms applying bioscrubbers for air 
treatment. 

Table 4.133:  Examples  of  water  consumption  and  water  discharges  for  fattening  pig  farms 

applying bioscrubbers 

Location 

Total water 
consumption 
(m3/ap/yr) 

Water discharged 
from the air 
cleaning system 
(m3/ap/yr) 

Denmark 

1 

0.43 

Germany 

1.6–2.4 

0.3–0.4 

The 
Netherlands 

0.9–3.1 

1–4  

The 
Netherlands 

0.8–1.8 

0. 17–0.68  

Remarks 

according 

elutriation 

Calculated  values  with  the  assumption  of  4 
fattening  pigs  produced  per  year  per  animal 
place  (values  reported:  0.108  m3/pig  produced, 
respectively) 
from  4 800–7 200 m3/yr 
Calculated  values 
reported  for  fresh  water  requirements  (with  pH 
to  water 
control, 
conductivity) for a capacity of 255 000 m3/h and 
for 85 m3/fattening pig/yr of airflow capacity 
With  water  curtain.  Calculated  values  from  the 
reported  data:  1.9  m3/day  for  winter  and 
6.5 m3/day 
farm  of 
summer, 
520 fattening pigs and 240 weaners 
With  water  curtain.  Calculated  values  from  the 
reported  data:  2.27  m3/day  for  winter  and  5.25 
m3/day for summer, for a farm of 1 080 fattening 
pigs.  This  unit  is  reported  to  have  a  relatively 
low  amount  of  flushing  water  due 
to  an 
optimised flushing water management. 

for  a 

for 

Source: [ 53, Denmark 2010 ] [ 121, Germany 2010 ] [ 135, Netherlands 2010 ] [ 127, Netherlands 2010 ]  

[ 129, Netherlands 2010 ] [ 624, IRPP TWG 2013 ] 

The  waste  water  is  usually  stored  with  the  slurry  and  landspread,  taking  into  account  the 
additional  supply  of  nitrogen.  It  might  also  be  treated  in  a  subsequent  denitrification  stage, 
where in a separate reactor the nitrogen compounds are transformed into gaseous N2, allowing 
for the reuse of the process water and its final discharge at lower costs. 

Technical considerations relevant to applicability 
In  principle,  this  system  is  easy  to  implement,  both  as  an  addition  to  new  buildings  and  in 
refurbishing existing buildings already applying forced artificial ventilation under a negative air 
pressure with centralised air extraction. In practice, the installation of a scrubber in an existing 
house requires, in most cases, a redesign of the ventilation system and the installation of new, 
more powerful, fans. Where the ventilation system has multiple fans or multiple outlet points, 
the 
the  primary  condition  governing 
implementation  in  existing  houses  is  the  technical  possibility  to  operate  with  centralised  air 
extraction which depends on the configuration of the building [ 261, France 2010 ]. 

is  not  practicable.  Therefore, 

implementation 

In  pig  housing,  the  design  and  the  size  of  the  pens  are  not critical  for  the  applicability  of  the 
system. A dust filter may be necessary where dust levels are higher (straw systems), which will 
increase pressure in the system and also increase energy use. 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Bioscrubbers are more suitable for pig production as in poultry houses the high dust and feather 
load of the ventilation air increases the risk of blockage of the packing bed, which decreases the 
efficiency of the scrubber and increases maintenance costs. To overcome this, a dust filter may 
be applied but with a consequent increase of the pressure drop and energy use [ 51, BE Flanders 
2010 ]. In addition, in the all-in all-out system that is used at poultry farms, the microbes of the 
biolayer  will  be  left  without  nutrients  by  the  contaminated  air  for  a  certain  period  of  time  
[ 135, Netherlands 2010 ]. During the periods when the animal house is empty, the bioscrubber 
can be fed by recirculating the liquid [ 624, IRPP TWG 2013 ]. 

Economics 
Reference  costs  related  to  the  application  of  bioscrubbers  in  the  Netherlands  are  reported  in 
Table 4.134. 

Table 4.134:  Associated costs for bioscrubbers in the Netherlands by pig category  

Pig category 

Housing 
capacity 
(animal 
places) 

Associated costs (1) (2) 

Investment costs 
(EUR/ap) 

Annual costs (3) 
(EUR/ap/yr) 

Without 
water curtain 
15 
170 

With water 
curtain 
16 
170 

Without 
water curtain 
3.0 
30 

477 

2 016 
130 

Weaners 
Farrowing sows 
Mating and 
gestating sows 
Fattening pigs 
12 
(1) Bioscrubbers designed for 70 % ammonia removal efficiency and combined with a denitrification stage. 
(2) All cost data are given without VAT. 
(3) Annual costs include depreciation, interest, maintenance and all other operating costs.  
Source: [ 135, Netherlands 2010 ] [ 589, Netherlands 2010 ] 

4 200 

100 

10 

20 

90 

23 

40 

50 

With water 
curtain 
4 
35 

Examples  of investment,  operational  and total costs  are  presented  in Table 4.135  for different 
housing capacities in pig production, expressed also by 1 000 m3/hour of capacity. For existing 
houses,  higher  costs  are  expected  because  of  the  additional  costs  for  the  adaptation  of  the 
ventilation  system.  From  this  table,  it  is  deduced  that,  for  example  for  applications  to  pig 
housing  in  Germany  with  3 000  animal  places,  an  investment  of  EUR 470  to  EUR 720  is 
necessary for each 1 000 m3/hour of capacity. At the condition of standard ventilation of 85 m3/h 
per  animal  place,  the  annualised  investments  are  around  EUR 4–7  per  animal  place  per  year, 
and the annual  operating costs vary between EUR 7.5 and EUR 9.5 per animal place per year  
[ 121, Germany 2010 ]. This system’s lifetime is expected to be around 10 years. 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.135:  Cost  ranges  associated  with  the  use  of  bioscrubbers  for  exhaust  air  treatment  in 

fattening pig production, in Germany and Denmark 

Associated costs (1) 

Housing 
capacity 

Investment costs 

EUR per 
1 000 m3/h 

EUR/ap 

Annualised 
investment costs 
EUR per 
1 000 
m3/h per 
yr 

EUR 
per 
ap/yr 

Operating costs 

Total costs 

EUR per 
1 000 
m3/h per 
yr 

EUR 
per  
ap/yr 

EUR per 
1 000 m3/h 
per year 

EUR per 
ap/yr 

61–71 

83–96 

47–54 

62–70 

8.1–9.1 

95–107 

5.2–6.0 

156–178 

201–226 

463–542 

552–638 

728–820 

13.3–
15.1 

17.1–
19.3 

10.0–
11.1 

7.1–8.2  118–130 

Germany 
460–700  
animal places 
(39 000–
60 000 m3/h) (2) 
1 060–1 180 
animal places 
(90 000–
100 000 m3/h) 
(2) 
1 700–1 850 
animal places 
(150 000–
157 000m3/h) (2) 
3 000 animal 
places  
(255 000 m3/h) 
(3) 
Denmark 
400 animal 
places (4) 
(40 000 m3/h)  
(1) All cost data are given excluding VAT and are related to new houses. 
(2) Costs are calculated on the following assumptions: amortisation period of 10 years for the installation and 20 years 
for  the  building,  6 %  interest  rate  for  50 %  of  the  investment,  labour  costs  EUR 20/h,  electricity  EUR 0.12/kWh, 
water  EUR 0.5/m3,  acid  EUR 0.25/kg,  landspreading  of  waste  water  EUR 2.6/m3,  maintenance  1 %  of  investment, 
additional costs for larger slurry store EUR 120/m3, additional costs for more powerful fans EUR 3 per 1 000 m3 of 
installed air capacity. 

165 
(140–190) 

600 
(470–720) 

100 
(90–110)  

65 
(50–80) 

12.1–
13.5 

142–159 

4.4–4.9 

7.5–9.5 

90–101 

7.7–8.6 

12–16 

40–61 

39–46 

52–58 

678 

4–7 

NI 

NI 

NI 

NI 

NI 

(3) Costs are calculated on the following assumptions: amortisation period of 10 years for the installation and 20 years 
for  the  building,  4 %  interest  rate,  labour  costs  EUR 15/h,  electricity  EUR 0.15/kWh,  water  EUR 0.5/m3,  acid 
EUR 0.35/kg,  application  of  waste  water  EUR 3/m3,  maintenance  1 %  of  investment,  additional  costs  for  larger 
slurry store and additional costs for more powerful fans are included. 

68 

12 

(4) Average from different system suppliers in Denmark. 
NB: NI = no information provided. 

Source: [ 121, Germany 2010 ] [ 514, KTBL 2008 ] [ 53, Denmark 2010 ]  

An example of costs for a biotrickling filter applied to a pig house, broken down for each cost 
factor, is given in Table 4.136.  

Intensive Rearing of Poultry or Pigs 

499 

 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.136:  Investment and annual operating costs for a biotrickling filter applied to a newly built 

facility for pig production 

Investment costs (1) 
Operating costs 

EUR/ap/yr 
43.5 

Annualised investment cost (10 %)  
Maintenance (3 %)  
Interest (6 %)  
Electricity use (EUR 0.11/kWh) 
Water use (EUR 1.0/m3)  
Chemical use (EUR 0.6/litre H2SO4, 98 %)  
Water discharge (2) 
Total annual operating costs 

3.4 
1.8 
1.0 
3.8 
1.7 
NA 
2.5 
10.8 
Total annual costs  
14.3 
(1) The investment costs are based on a maximum ventilation capacity of 60 m3/ap/h. 
(2) Waste water disposal costs are assumed to be equivalent to EUR 2/m3 for discharge from biotrickling 

scrubber. 

NB: NA = not applicable. 

Source: [ 568, Melse et al. 2010 ] 

The annual costs associated with the installation of a bioscrubber correspond on average to EUR 
3  per  pig  produced  in  Denmark.  Costs  are  lower  with  partial  air  cleaning;  the  cost  per  pig 
produced  is  reduced  to  EUR 1.9  when  cleaning  60 %  of  exhaust  air  and  EUR 0.7  when  only 
40 %  of  the  exhaust  air  is  treated  [  55,  Denmark  2010  ].  Cost  data  for  the  application  of 
bioscrubbers in poultry housing are presented in Table 4.137. 

Table 4.137:  Extra costs related to the application of bioscrubbers in poultry housing 

Size of 
housing 
in 
animal 
places 
(ap) 
50 000 

Type of animal 

40 000 

Pullets 
Laying hens 
(aviary) 
Pullets of broiler 
breeders 
Broiler breeders  
Broilers 
Turkeys 
Ducks 
Source: [ 503, Vermeij 2011 ] 

19 000 
90 000 
20 000 
40 000 

33 000 

Extra 
investment 
(EUR/ap) 

Annualised 
extra 
investment 
(EUR/ap) 

Annual 
operating 
extra cost 
(EUR/ap) 

Total 
annual 
extra 
cost 
(EUR/ap) 

2.93 

3.41 

4.24 

8.26 
3.71 
25.83 
5.75 

0.41 

0.50 

0.60 

1.15 
0.55 
3.57 
0.78 

0.59 

0.63 

0.86 

1.76 
0.64 
4.71 
1.15 

1.00 

1.13 

1.46 

2.90 
1.19 
8.28 
1.93 

Total 
annual 
extra cost 
(EUR per 
bird 
produced) 
0.40 

1.29 

0.70 

2.83 
0.173 
2.86 
0.30 

Driving force for implementation 
In some Member States, air treatment systems are frequently required by environmental permits 
in situations where it would otherwise not be possible to comply with the maximum ammonia or 
odour emissions allowed by local regulations. 

Example plants 
This system is commonly  used. In the Flemish part of Belgium, 190 farms  have installed  this 
technique. At least 243 German farms are using this technique  [ 505, Hahne J. 2011 ]. In the 
Netherlands, the installed capacity of bioscrubbers for ammonia removal in 2008 was reported 
to be 14 million m3/hour for 90 farms [ 568, Melse et al. 2010 ].  

500 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Reference literature 
[  13,  Melse  2009 ]  [  42,  Netherlands  1999  ] [  51,  BE  Flanders  2010  ]  [  53,  Denmark  2010  ] 
[ 121, Germany 2010 ] [ 127, Netherlands 2010 ] [ 129, Netherlands 2010 ] [ 135, Netherlands 
2010 ] [ 261, France 2010 ] [ 500, IRPP TWG 2011 ] [ 503, Vermeij 2011 ] [ 505, Hahne J. 
2011 ] [ 514, KTBL 2008 ] [ 568, Melse et al. 2010 ] [ 589, Netherlands 2010 ] [ 624, IRPP 
TWG 2013 ] [ 640, Netherlands 2013 ] [ 644, Netherlands 2014 ] [ 665, Riis 2012 ] 

Chapter 4 

4.9.4 

Wet acid scrubber 

Description 
The  ventilation  air  of  an  animal  house  is  passed  through  a  filter  (e.g.  packed  wall)  where  a 
circulating acid scrubbing liquid is sprayed. When the contaminated exhaust air is brought into 
contact with the scrubbing liquid, ammonia is absorbed in the low-pH solution and the clean air 
2-).  The  ammonium  salt  produced  is 
leaves  the  system  (2  NH3  +  H2SO4    2  NH4
removed  from  the  system  with  the  discharge  water.  Filters  can  be  packed  walls  or  made  of 
lamellae  of  synthetic  polymer  fibres  or  plastic  pads.  No  biofilm  is  formed  on  the  contact 
surfaces. Diluted sulphuric acid is mostly used in this system and is automatically added to keep 
the pH of the circulating scrubbing water below 5 (1.5–5). Hydrochloric acid may also be used. 
The  scheme  of  a  wet  acid  scrubber  does  not  differ  substantially  from  the  general  design 
presented in Figure 2.27 (see Section 2.4).  

+  +  SO4

Achieved environmental benefits  
A  significant  reduction  of  ammonia  emissions  to  air  can  be  achieved.  Also,  dust  can  be 
removed. Acid scrubbers are less effective in reducing odorous compounds, due to the low pH 
value  that  inhibits  the  development  of  microorganisms  in  the  filter  wall,  and,  therefore, 
microbial odorant degradation. Odour reduction is limited to compounds  of an  alkaline nature 
that can be diluted in an acid solution, as well as to odorous substances that can be attached to 
dust particles. 

Cross-media effects 
Where sulphuric acid is used, the discharged effluent contains ammonium sulphate that can be 
used as a  fertiliser,  taking  into  account the possible  need  to  correct the acidity  of the effluent 
(e.g.  by  liming).  Smaller  quantities  of  water  have  to  be  discharged  in  comparison  with 
bioscrubbers. With the use of different acids, sludges might have to be disposed of.  

Air cleaning systems result in increased energy use for ventilation, due to counter pressure in 
the filter material and ducting, plus power for water and acid pumps. The fan should be able to 
overcome  a  pressure  difference  of  at  least  100 Pa  in  addition  to  the  flow  resistance  of  the 
animal house without noticeable capacity loss.  

Specific  safety  measures  are  required  for  the  storage  and  handling  of  acids  and  chemical 
substances,  according  to  national  or  local  regulations.  These  may  include  constructional 
requirements,  which  may  pose  some  limits  to  the  possible  implementation  of  the  technique. 
Training of the staff on acid management minimises the risks to human health and environment.  

Environmental performance and operational data 
An ammonia reduction of at least 70 %, and up to 99 %, in the exhaust air can be achieved. The 
odour  reduction  efficiency  varies  between  30 %  and  40 %,  and  raw  gas  odours  can  still  be 
perceived in the clean gas. Acid usage also makes the scrubber ineffective at scrubbing odorous 
organic acids [ 624, IRPP TWG 2013 ]. As a result, acid scrubbers are not generally considered 
suitable for odour elimination as a single-step process.  

A  fine  dust  (PM10)  removal  efficiency  of  around  60 %  can  usually  be  obtained.  If  combined 
with  a  dedusting  neutral  stage,  the  removal  efficiency  of  the  system  is  expected  to  improve. 
(see Section  4.9.4).  Data  concerning  the  removal  efficiency  of  chemical  scrubbers  applied  in 
different animal types are reported in Table 4.138. 

Intensive Rearing of Poultry or Pigs 

501 

 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.138:  Examples  of  removal  efficiencies  of  chemical  scrubbers  applied  in  pig  and  poultry 

housing systems  

Animal category 

Source 

Pigs 
Pigs 

Pigs 

[514, KTBL 2008] 
[54, Denmark 2010 ] 
[130, Netherlands 2010] 
[132, Netherlands 2010]  
[133, Netherlands 2010]  
[134, Netherlands 2010]  
[ 374, Denmark 2010 ] 

Emissions reduction  
(%) 

Ammonia  Odour 

70–95 
90–99 

95–99 
70 (1) 

NI 
NI 

30 

Dust 
> 70 
NI 

PM10 
NI 
NI 

NI 

60 

80–90 

Broilers 
Laying hens 
Pullets 
Broiler breeders 
Broilers 
Ducks 
Turkeys 
(1) A lower removal efficiency (about 70 %) is achieved when the filter is operated with a higher filter 

[ 131, Netherlands 2010 ] 
[ 644, Netherlands 2014] 

70–90  

NI 

NI 

NI 

NI 

35 

40 

surface area and, consequently, at lower costs. 

NB: NI = no information provided. 

In Table 4.139, reported ammonia emissions after treatment with an acid scrubber are presented. 

502 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Table 4.139:  Reported emission levels achieved with the application of acid scrubbers 

System 

NH3 
reduction 
efficiency  
(%) 

Animal 
category 

Ammonia 

Odour 

PM10 

kg/ap/yr 

ouE/s/animal  g/ap/yr 

Reference 

0.4 (100 % air 
cleaned) 

Chapter 4 

90 

Fattening 
pigs 

0.56  (60 %  air 
cleaned) 

NI 

NI 

[ 54, Denmark 
2010 ] 

Acid scrubber 
with partial air 
treatment 

Acid scrubber 
(6 500 m3/m2/h 
surface filter 
load, pH 3–4, 
bed thickness 
0.9 m) 

Acid scrubber 
(10 000 m3/m2/h 
surface filter 
load, pH 0.5–4, 
bed thickness 
0.5 m) 
Acid scrubber 
(6 500 m3/m2/h 
surface filter 
load, pH 3–4, 
bed thickness 
0.9 m) 

Acid scrubber 
(10 000 m3/m2/h 
surface filter 
load, pH 0.5–4, 
bed thickness 
0.5 m) 

1 (20 % air 
cleaned) 

0.13–0.18 (1)  12.5–16.1 (2)  31–99 

0.03–0.04 (1) 

3.8–5.5 (2) 

0.21 

13.1 

53 

88 

0.42 

19.5 

83 

0.8–1.1 (1) 

12.5–16.1(2) 

31–99 

0.18–0.23 (1) 

3.8–5.5 (2) 

1.3 

13.1 

53 

88 

2.5 

19.5 

83 

Fattening 
pigs 
Weaners 
Mating and 
gestating 
sows 

Farrowing 
sows 

Fattening 
pigs 
Weaners 
Mating and 
gestating 
sows 

Farrowing 
sows 

95 

70 

90 

0.2 
0.14 
0.93 
0.11 

0.032 
0.008 
0.07 
0.017 

Acid scrubber 
with droplet 
separator 

Laying hens 
Broilers 
Turkeys 
Pullets 
Pullets of 
broiler 
breeders 
Broiler 
breeders 
(1) The upper end of the range corresponds to more space being available per animal. 
(2) The lower end of the range is associated with low-NH3-emitting housing systems.
NB: NI = no information provided. 

0.025 

0.058 

0.11 

0.56 

59 
15 
16 
21 

16 

30 

The pH at which each system operates is different: generally, when the liquid reaches pH 4, acid 
is  added  to  the  circulating  liquid  to  obtain  pH  values  of  3,  1.5  or  as  low  as  0.5.  The 
concentration  of  ammonium  sulphate  should  not  exceed  2.1 mol/l  to  prevent  the  risk  of 
crystallisation. On average, 90 litres of water and 3 litres of 96 % sulphuric acid are needed to 
remove  1 kg  of  ammonia  from  input  air,  which  means  a  concentration  of  0.3 mol/l 
[ 55, Denmark 2010 ]. The replacement of the circulating liquid is automatic and can  be done 
after the pH has been corrected to the value needed a number of times (e.g. pH correction to 0.5 
five times) [ 134, Netherlands 2010 ] [ 130, Netherlands 2010 ]. Hence the system management 

Intensive Rearing of Poultry or Pigs 

503 

[ 130, 
Netherlands 
2010 ] 
[ 133, 
Netherlands 
2010 ] 

[ 132, 
Netherlands 
2010 ] 
[ 134, 
Netherlands 
2010 ] 

[ 131, 
Netherlands 
2010 ] 

Chapter 4 

can  be  controlled  by  using  electronic  devices  to  control  operating  parameters.  Filters  and 
components need frequent maintenance and control. 

Under optimal conditions, it is reported from Germany that approximately 40 litres of scrubbing 
water need to be drained per fattening pig place per year in slurry-based pig housing. The fresh 
water requirements to compensate for evaporation losses amount to 5–7 l/1 000 m3 exhaust air 
[ 514, KTBL 2008 ]. For the high NH3 removal efficiency of 95 %, the waste water production 
is  about  0.2  m3/kg  of  NH3  removed  per  year,  which  equals  a  yearly  amount  of  70  litres  per 
fattening pig place or 2 litres per broiler place [ 13, Melse 2009 ]. 

In broiler houses, emissions are significant only after days 15–20 of the cycle and only at this 
time does cleaning of exhaust waste air become justifiable (see Figure 4.72).  

Source: [ 374, Denmark 2010 ]  

Figure 4.72:  Ammonia emissions from a broiler house  

Table 4.140  presents  data  from  Denmark  concerning  the  additional  energy  consumption  in 
relation to the proportion of airflow at the maximum ventilation rate that is treated.  

Table 4.140:  Additional  energy  consumption  associated  with  air  cleaning  by  an  acid  scrubber 

applied in pig farms in Denmark  

Animal type 

Fattening pigs (30–100 kg) 
Weaners (30 kg) 
Weaners (30 kg) 
Gilts 
(1) These values correspond to 8–16 kWh/ap/yr. 
Source: [ 55, Denmark 2010 ] 

Partial air cleaning capacity at the 
maximum ventilation rate 
(%) 
31 
100 
34 
100 

Additional energy 
consumption 
(kWh/animal produced) 
2–4 (1) 
6.8 
1.3 
24 

Technical considerations relevant to applicability 
This system can be implemented in new and existing housing applying forced ventilation with 
centralised  air  extraction.  Implementation  in  existing  houses  may  be  technically  difficult 
depending on the configuration of the building due to the required installation of the necessary 
ducts for channelling the exhaust air (see Section 4.9.1). 

504 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

In  pig  housing,  the  design  and  the  size  of  the  pen  are  not  critical  for  the  applicability  of  the 
system. In poultry housing, high dust levels in the exhaust air from the housing can affect the 
scrubbing performance; hence a dust filter may be necessary, which will increase pressure in the 
system  and  increase  the  energy  use.  The  system  can  be  easily  turned  on  and  off,  making  it 
suitable for poultry farms that apply all-in, all-out animal management. 

Economics 
Average costs have been calculated in the Netherlands and are reported in Table 4.141.  

Table 4.141:  Associated extra costs for acid scrubbers by associated ammonia reduction efficiency 

and animal category in the Netherlands 

Animal category 

Housing capacity 
(animal places) 

NH3 removal efficiency  

Associated costs (1)  

Investment costs 
(EUR/ap) 

70 % 

90 % 

Total annual extra costs  
(EUR/ap/yr) (2) 

70 % 

90 % 

Pigs 

Weaners 
Farrowing sows 
Mating and 
gestating sows 
Fattening pigs 
Poultry 

2 016 
130 

477 

4 200 

10 
105 

60 

30 

12 
120 

70 

35 

2 
20 

15 

8 

90 000 
25 000 
30 000 (aviary) 
30 000 (deep litter) 

Broilers 
Broiler breeders 
Laying hens 
Laying hens 
(1) All cost data are given without VAT. 
(2) Annual costs include depreciation, interest, maintenance and all other operating costs.  
NB: NI = no information provided. 

2.7 
8.55 
3.10 
3.95 

NI 
NI 
NI 
NI 

NI 
NI 
NI 
NI 

3.5 
30 

20 

11 

0.63 
2.37 
0.96 
1.09 

Source: [ 131, Netherlands 2010 ] [ 132, Netherlands 2010 ] [ 133, Netherlands 2010 ]  

[ 589, Netherlands 2010 ] 

An example of investment and annual costs for an acid scrubber applied to a newly built facility 
for  pig  production,  broken  down  for  each  cost  factor,  is  given  in  Table 4.142  with  separate 
values for each cost factor.  

Table 4.142:  Investment  and  annual  operating  costs  for  an  acid  scrubber  applied  to  a  new  house 

for pig production 

Investment costs (1) 
Operating costs 

Annualised investment cost (10 %)  
Maintenance (3 %)  
Interest (6 %)  
Electricity use (EUR 0.11/kWh) 
Water use (EUR 1.0/m3)  
Chemical use (EUR 0.6/litre H2SO4, 98 %)  
Waste water discharge (2) 
Total annual operating costs 

EUR/animal place/yr 
32.8 

2.6 
1.5 
0.8 
3.3 
0.6 
1.4 
0.6 
8.2 
10.8 

Total annual costs  
(1) The investment costs are based on a maximum ventilation capacity of 60 m3/ap/h. 
(2) Waste water disposal costs are assumed to be equivalent to EUR 10/m3 for discharge from acid scrubbing. 
Source:[ 568, Melse et al. 2010 ] 

Intensive Rearing of Poultry or Pigs 

505 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

From Denmark, extra costs for the installation of new systems are reported to be in the range of 
EUR 0.5–5/ap/yr, depending on the farm size [ 54, Denmark 2010 ]. Extra costs based on the 
share  of  the  maximum  ventilation  rate  treated  by  the chemical  scrubber range from  EUR 2  to 
EUR 2.4  per  pig  produced  when  the  air  cleaning  capacity  of  the  scrubber  is  equal  to  the 
maximum  ventilation  rate.  Meanwhile,  extra  costs  of  between  EUR 0.1  and  EUR 1.2 per  pig 
produced are reported for a 20 % partial air cleaning capacity of the maximum ventilation rate, 
with the low value corresponding to a large farm with approximately 8 000 fattening pig places 
[55, Denmark 2010]. 

Examples of extra cost data, for different animal categories and sizes of housing in the rearing 
of poultry, are presented in Table 4.143. 

Table 4.143:  Extra costs related to the application of acid scrubbers in poultry housing 

Type of 
animal 

Size of 
housing  
animal 
places  
(ap) 

Extra 
investment 
(EUR/ap) 

Annualised 
extra 
investment 
(EUR/ap) 

Annual 
operating 
extra cost 
(EUR/ap) 

Total 
annual 
extra cost 
(EUR/ap) 

2.77 

3.44 

0.37 

0.46 

0.50 

0.63 

0.87 

1.10 

Total 
annual 
extra cost 
(EUR per 
animal 
produced) 
0.34 

1.25 

50 000 

33 000 

40 000 

Pullets 
Laying hens 
(aviary) 
Growing 
pullets of 
broiler 
breeders 
Broiler 
breeders 
Broilers 
Turkeys 
Ducks 
Source: [ 503, Vermeij 2011 ] 

90 000 
20 000 
40 000 

19 000 

3.95 

0.52 

0.71 

1.23 

0.60 

7.59 

3.69 
24.7 
5.65 

1.00 

0.50 
3.39 
0.76 

1.40 

0.62 
4.37 
0.93 

2.40 

1.12 
7.76 
1.69 

2.35 

0.163 
2.68 
0.26 

Driving force for implementation 
Local  regulations  on  ammonia  emissions  can  set  maximum  emission  loads.  In  some  Member 
States,  air  treatment  systems  are  frequently  required  by  environmental  permits  in  situations 
where it would otherwise not be possible to comply with ammonia emission limit values.  

were 

reported 

Example plants 
This  system  is  commonly  used  in  the  Netherlands,  Germany  and  Denmark.  About  25–30  pig 
Denmark  
applying 
farms 
[54,  Denmark  2010],  whereas  one  broiler  farm  was  reported  for  the  poultry  sector  
[ 374, Denmark 2010 ]. In the Netherlands, the installed capacity of acid scrubbers for ammonia 
removal,  referring  to  the  year  2008,  was  reported  as  64  million  m3/h  installed  on  a  total  of 
790 farms [ 568, Melse et al. 2010 ]. In the Flemish part of Belgium, 145 farms are equipped 
with acid scrubbers. 

scrubbers 

acid 

be 

to 

in 

Reference literature 
[ 13, Melse 2009 ] [ 42, Netherlands 1999 ] [ 54, Denmark 2010 ] [ 55, Denmark 2010 ] [ 130, 
Netherlands  2010  ]  [  131,  Netherlands  2010  ]  [  132,  Netherlands  2010  ]  [  133,  Netherlands 
2010 ] [ 134, Netherlands 2010, ] [ 374, Denmark 2010 ] [ 503, Vermeij 2011 ] [ 514, KTBL 
2008  ]  [ 568,  Melse  et  al.  2010  ]  [  589,  Netherlands  2010  ]  [  624,  IRPP  TWG  2013  ]  [  644, 
Netherlands 2014 ] 

506 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.9.5 

Biofilter 

Description 
The exhaust air of the animal house is led through a filter bed of organic material, such as root 
wood  or  wood chips,  coarse  bark,  compost  or  peat.  These  materials are  generally  arranged  in 
layers, i.e. the filter bed consists of coarse material on the untreated exhaust air side and finer 
material  on  the  clean  air  side.  Fine-grained  filter  materials  have  a  relatively  large  specific 
surface area that facilitates mass transfer but, on the other hand, causes higher pressure losses.  

The filter material is kept sufficiently moist at all times, so that microorganism populations can 
form a film. This is achieved by either humidifying the exhaust air to a relative humidity of at 
least  95 %  and/or  by  controlled  intermittent  sprinkling  of  the  surface  of  the  filter  material. 
Moistening of the entire filter surface is required in order not to compromise performance, even 
if the air entering is saturated; in particular in summer and in open surface filters, it is necessary 
to compensate for evaporation losses. Gaseous compounds are absorbed by the moisture film of 
the biofilter material and are oxidised or degraded by microorganisms living on the moisturised 
filter material. 

Achieved environmental benefits 
Biofilters  are  mainly  used  to  eliminate  odours  arising  from  houses  with  no  bedding  material. 
They  can  also  be  used  in  litterless  housing  for  dust  separation,  if  coarsely  structured  filter 
material (which does not tend to clog) is used at least on the crude gas side.  

Ammonia  is also  degraded  in  biofilters,  but  the  possible  cross-media  effects  need  to  be  taken 
into  account.  This  aspect,  together  with  the  unknown  decline  of  the  performance  over  time, 
makes the ammonia removal efficiency of biofilters controversial.  

Cross-media effects 
The system involves an extra pressure drop of roughly 30–150 Pa [ 514, KTBL 2008 ], which 
depends  on  the  filter  surface  load,  the  type  and  height  of  the  filter  material  and  its  age. 
Ventilating  fans  must  be  able  to  overcome  the  added  resistance;  therefore,  additional  energy 
consumption  is  required  for  ventilation.  The  water  consumed  for  moistening  the  substrate  is 
reported to be in the range of 5–7 litres per 1 000 m3 of exhaust air. 

The  system  is  not  suitable as  a  sole  process  for  ammonia  reduction  from  exhaust  air  from 
livestock  houses  with a  high  ammonia  load.  Due  to the separation  of  ammonia,  the  microbial 
activity  is influenced  and  the  pH  value  is  significantly  lowered (no  adjustments  are  possible), 
while the formed salts cannot be removed. Finally, secondary trace  gases are formed, such as 
nitrous oxides and N2O, which risk the functionality of the whole system.  

If  the  bed  scrubber  filter material  consists  of  peat,  a  significant  emission  of  greenhouse  gases 
(GHG) would be associated with the peat mining process, while GHG emissions from the farm 
system itself may become significant due to the potential formation of N2O. 

Environmental performance and operational data 
Biofilters function properly if: 

 

 

 

the pollutants to be treated are water-soluble and biodegradable; 

the residence time of the exhaust air to be cleaned is long enough that the odorants can be 
separated  and  degraded  by  microorganisms  without  these  components  or  reaction 
products accumulating in the biofilter material; 

the operating conditions guarantee a sufficient supply of oxygen, water and nutrients to 
the microorganisms at temperatures of 10 °C to 35 °C [ 514, KTBL 2008 ].  

Intensive Rearing of Poultry or Pigs 

507 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

A capacity of 440 m3/h of exhaust air per m2 of filter surface has been reported. Based on this 
value and knowing the airflow rate that has to be treated, the dimensions for a filter module can 
be  estimated.  The  thickness  of  the  active  filter  layer  is  normally  between  0.3 m  and  1.4  m, 
depending on the material (for coarser materials a large bed height is necessary), whereas the 
residence (contact) time ranges from 4 seconds to 20 seconds depending on the filter height and 
surface load. Upscaling or downscaling of the treatment capacity, due to the modular design, is 
possible. 

The  sprinkling  of  the  filter  with  fresh  water  (approximately  5–7  litres  of  water/1 000  m3  of 
outgoing air, achieving a 60–70 % material moisture) is automatically controlled on the basis of 
the airflow volume. The filter is moistened from the surface by two nozzles per filter module.  

The  resource  demand  for  operating  a  biofilter  with  a  capacity  of  255 000  m3/h  exhaust  air 
volume, corresponding to an animal house of 3 000 animal places for fattening pigs, is reported 
in  Table 4.144.  About  21 kWh/animal  place  per  year  of  energy  is  needed  for  pressure 
compensation  in  the  ventilation  system.  Furthermore,  1.53 m3/animal  place  per  year  of  water 
consumption is necessary. 

Table 4.144:  Annual resources demand for the operation of a biofilter, in Germany  

Resource 

Unit 

Consumption 
(per 1 000 m3/h 
capacity) (1) 

Average annual 
consumption for  
255 000 m3/h of capacity 

Energy – Operation of the air 
cleaning system 
Energy – Additional 
consumption for ventilation 
Fresh water  

Labour 
NB: NA = not applicable. 
Source: [ 120, Germany 2010 ] 

kWh/yr 

3.3 

kWh/yr 

250 (220–280) 

m3/yr 

h/yr 

18 (14–22.5) 

0.35–0.40 

840 

63 400 

4 600 

90 

As  for  all  air  cleaning  systems,  the  odour  removal  efficiency  depends  on  the  crude  gas 
concentration and is reported to be from 84 % to 97 % [ 120, Germany 2010 ]. The minimum 
requirement  for  odour  reduction  of  air  cleaning  systems  applied  in  Germany  is  defined  as  an 
odour concentration in the clean gas not exceeding 300 ouE/m3 and no typical process odours 
(e.g.  animal  house  odour)  are  perceptible  in  the  clean  gas.  Biofilters  achieving  a  removal 
efficiency for odour of over 70 % have only been verified in pig housing [ 514, KTBL 2008 ].  

The  dust  abatement  efficiency  is  reported  to  be  from  80 %  to  100 %  [  120,  Germany  2010  ]  
[ 644,  Netherlands  2014  ].  Measurements  of  the  finest  dust  fraction,  PM2.5,  indicate  an 
abatement efficiency of 63 % [ 515, UR Wageningen 2010 ]. 

In Germany, the application of biofilters for ammonia reduction is not recommended, but, at the 
same  time,  it  is  acknowledged  that  a  biofilter  can also  be  operated  as  an  ammonia  abatement 
technique  under  certain  conditions  (e.g.  in  combination  with  a  water  curtain)  and  if  carefully 
operated  (comparable  to  the  requirements  for  bioscrubbers)  [  500,  IRPP  TWG  2011  ].  The 
ammonia abatement efficiency is reported to be over 70 % [ 516, TÜV 2009 ] and up to 89 %, 
but it is not clear whether the removal efficiency can stay high over time due to the secondary 
effects  previously  described  (see  'Cross-media  effects')  [  515,  UR  Wageningen  2010  ]  
[ 500, IRPP TWG 2011 ]. 

In order not to undermine the removal capacity of the bed, regular replacement of the biofilter 
packing is necessary. Pretreating the air in order to remove the main part of the ammonia load 
before it enters the biofilter minimises the formation of nitrite/nitrate salts and allows a much 

508 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

longer packing lifespan and thus reduces refilling costs [568, Melse et al. 2010]. Used biofilter 
materials are applied to land. No additional waste water is produced. 

Technical considerations relevant to applicability 
Biofilters are mainly used in houses with no bedding material (slurry-based plants). As the filter 
area  requirement  is  approximately  0.2–0.25  m2  per  animal  place,  a  sufficient  area  must  exist 
outside the facilities to accommodate the filter packages. 

The  implementation  in  existing  houses  with  forced  ventilation  must  be  planned  with  the 
adaptation  of  exhaust  air  ducts  and  with  significant  additional  requirements  for  ventilation, 
making biofilters in practice only applicable where a centralised ventilation system is used. 

Economics 
Data are given for a capacity of 255 000 m3/h exhaust air volume, equivalent to 3 000 fattening 
pig  places.  A  total  annual  cost  of  between  EUR 11.60/ap  and  EUR 13.10/ap  results  from  the 
amortisation  (20  years  for  construction  and  4 % interest  rate)  of  the  investment  requirements 
(EUR 59–64/ap, annualised investment costs from EUR 6.5/ap to EUR 6.8/ap) added to annual 
operating costs of EUR 5.10–6.30 per animal place. 

Driving force for implementation 
Local  high  emission  loads  or  insufficient  spatial  distances  from  odour-sensitive  receptors  are 
drivers.  

Example plants 
At least 267 German farms are using this technique [ 505, Hahne J. 2011 ].  

Reference literature  
[ 52, BE Flanders 2010 ] [ 120, Germany 2010 ] [ 500, IRPP TWG 2011 ] [ 514, KTBL 2008 ]  
[ 515, UR Wageningen 2010 ] [ 516, TÜV 2009 ] [ 568, Melse et al. 2010 ] [ 644, Netherlands 
2014 ] 

4.9.6 

Multi-stage scrubber 

Multi-stage air cleaning system clean exhaust air from forced ventilation livestock buildings that 
usually  comprise  two  or  three  stages  that  work  on  different  principles,  e.g.  acid  scrubber  to 
remove  ammonia  and  a  biofilter  to  remove  odour.  As  a  consequence,  theoretically,  there  are 
many possible combinations. At least 438 German farms are using techniques of this type [ 505, 
Hahne J. 2011 ]. There are several two- and three-stage exhaust air treatment techniques, which 
can  differ  substantially  each  other.  The  following  descriptions  are  limited  to  a  two-stage  acid 
scrubber with a downstream bioscrubber and a three-stage installation with a water scrubber and 
acid scrubber as well as a downstream biofilter. 

4.9.6.1 

Two-stage scrubber: wet acid scrubber combined with bioscrubber  

Description 
The air cleaning system consists of two stages in series: a chemical scrubber and a bioscrubber. 
The first stage is an acid scrubber to separate ammonia and dust (see Section 4.9.4). It consists 
of  filter  beds  made  of  synthetic  polymer  fibres  arranged  in  parallel  with  a  high  water  storage 
capacity, followed by a drip separator. The filter beds are intermittently sprinkled with acidified 
water.  Ammonia  reacts  with  sulphuric  acid,  forming  ammonium  sulphate.  With  the  aid  of  a 
controlled acid metering system, the pH value of the scrubbing water of the chemical stage is 
kept  within  a  certain range  (e.g.  at  a  level  of  1.5).  When  the pH  value  reaches a  higher  level 
(e.g. 4) due to ammonia absorption, acid is added until the pH value is reduced again. This cycle 
repeats  itself  a  fixed  number  of  times  (e.g.  five  times).  If  again  a  high  pH  value  has  been 
achieved,  complete  blowdown  takes  place.  Afterwards,  the  water  storage  tank  is  refilled  with 

Intensive Rearing of Poultry or Pigs 

509 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

fresh  water and  acid  with a  low  pH  value  (e.g.  1.5). In  the  case  of  implementation  in  littered 
houses where dust loads are high, more frequent elutriation  and cleaning  are indispensable on 
the basis of differential pressure measurements [ 514, KTBL 2008 ]. 

The second stage is a biologically active wet scrubber, which is completely separated from the 
acid stage. Due to the biological activity in this step, odour is mainly reduced; fine dust is also 
reduced. The filter bed packing is made of plastic and is permanently sprinkled with water. The 
scrubbing  water  from  this  stage  flows  back  into  the  water  tank,  which  is  equipped  with  an 
additional submerged contact bed for the improvement of the biological degradation of residual 
emissions of odorants. For the separation of aerosols from this stage, another drip separator is 
installed at the clean air outlet. Both stages are of transverse flow of exhaust air.  

A scheme of a two-stage system for air scrubbing is presented in Figure 4.73. 

Source: [ 122, Germany 2010 ]  

Figure 4.73:  Two-stage scrubber: acid scrubber combined with bioscrubber 

Another  reported  option  for  the  first  treatment  stage  is  to  install  a  water  curtain  before  the 
bioscrubber,  which  is  operating  as  a  water  scrubber  [  127,  Netherlands  2010  ]  [  129, 
Netherlands 2010 ].  

Achieved environmental benefits 
Reduction of emissions of odorants, ammonia, and dust is an achieved environmental benefit. 

Cross-media effects 
The energy consumption is increased as the fans have to overcome a maximum pressure loss of 
150–200 Pa (total for the ventilation system in the housing and the air cleaning system) without 
any loss of capacity. 

The scrubbing water in the chemical stage, which contains ammonium sulphate, must be stored 
in  a  separate  storage  tank,  whereas  the  scrubbing  water  from  the  separate  water  stage  can  be 
pumped  into  the  external  slurry  store.  Nitrogen  has  to  be  taken  into  account  for  fertiliser 
planning. Compared to a single-stage acid scrubber, the elutriation rate of the two-stage system 
corresponds to approximately threefold the amount. 

510 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
The amount of water that has to be rejected from the chemical stage amounts to 0.05 m3 per kg 
of NH3 input, and from the biological stage 0.04 m3 per kg of NH3 input. Its volume generally 
corresponds  to  1.65  m3  per  1 000 m3/h  (0.14  m3/pig  place  per  year)  in the  first  cleaning  stage 
(acid  scrubber),  and  to  1.34 m3  per  1 000 m3/h  (0.11 m3/pig  place  per  year)  in  the  second 
cleaning stage (bioscrubber). Water losses due to evaporation and the necessary elutriation have 
to be compensated by fresh water addition; this supply is automatically controlled and separate 
for each stage [ 122, Germany 2010 ]. Ranges for the resource demand related to a capacity of 
1 000 m3/h are shown in Table 4.151. 

Ammonia  reductions  are  achievable  in  the  range  of  70 %  to  96 %,  along  with  a  total  dust 
reduction  from  85 %  to  98 %.  The  minimum  requirement  for  odour  reduction  of  air  cleaning 
systems applied in Germany is defined as an odour concentration in the clean gas not exceeding 
300 ouE/m3 and no typical process odours (e.g. animal house odour) are perceptible in the clean 
gas [ 514, KTBL 2008 ]; on average, these results are equivalent to 70 % efficacy.  

Data  concerning  the  emission  reductions  achieved  by  applying  two-stage  scrubbers  in  pig 
production are presented in Table 4.145. Reported emissions in pig production after treatment of 
exhaust air with two-stage air scrubbers are presented in Table 4.146.  

Table 4.145:  Emission  reductions  achieved  by  the  application  of  two-stage  scrubbers  in  pig 

production 

Achieved emission reduction 
(%) 

Ammonia 

Odour 

Dust 

PM10 

70–96 
80 (average) 

84–93 
85 (average) 

84–93 
85 (average) 

87–98 

60–77 
70 (average) 

40–72 
70 (average) 

40–72 

75 

NB: NI = no information provided. 

85–98 
96 (average) 

94–96 

94–96 

94–96 

NI 

80 

80 

80 

Reference 

[122, Germany 2010] 

[125, Netherlands 2010] 

[129, Netherlands 2010] 

[127, Netherlands 2010] 

Table 4.146:  Emission levels achieved with the application of two-stage scrubbers in pig production 

System 

NH3 
reduction 
efficiency  
(%) 

Animal 
category 

Ammonia 
(1) 

Odour (2) 

PM10 

kg/ap/yr 

ouE/s/animal  g/ap/yr 

Bioscrubber 
combined with 
water curtain  

Acid scrubber 
combined with 
biological/water 
scrubber  

85 

85 

Weaners 
Farrowing sows 
Mating/gestating 
sows 

0.09–0.11 
1.25 

1.4–2.0 
7.0 

0.63 

4.7 

Fattening pigs 

0.38–0.53 

4.5–5.8 

Weaners 
Farrowing sows 
Mating/gestating 
sows 
Fattening pigs 

0.09–0.11 
1.25 

1.6–2.3 
8.4 

0.63 

5.6 

0.38–0.53 

5.4–6.9 

26 
42 

44 

55 

26 
42 

44 

55 

Reference 

 [ 127, 
Netherlands 
2010 ] 
[129, 
Netherlands 
2010] 

[ 125, 
Netherlands 
2010 ] 

(1) The higher end of the range for weaners and fattening pigs corresponds to more space being available per animal. 
(2) The lower end of the range for weaners and fattening pigs is associated with low-NH3-emitting housing systems. 

Intensive Rearing of Poultry or Pigs 

511 

 
 
 
 
 
 
 
Chapter 4 

Ammonia  emissions between  0.062 kg  and  0.065  kg/animal  place/year  were  reported  from  an 
animal house for ducks, equipped with a two-stage scrubber, in Germany [ 646, COM 2013 ]. 

Technical considerations relevant to applicability 
Two-stage air cleaning systems are also applicable to littered housing. The bioscrubber stage is 
preceded by  the acid  scrubber,  which contributes to dust and feather  removal.  Additionally,  a 
simpler filtering stage (water curtain) can be added to reduce dust as a first step.  

The housing ventilation system requires proper planning (air inlet/outlet) and design (sufficient 
capacity  of  the  fans  for  the  increased  pressure  loss).  In  retrofitting  existing  houses,  there  are 
significant  additional  requirements  for  the  adaptation  of  the  air  ventilation  outlets  and  for  the 
upgrading of the fans, making the system applicable only where a centralised ventilation system 
is used. Additionally, significant space must be available to host the various hardware. 

Economics 
Economic figures have been modelled in Germany for modules with a capacity of 1 000 m3/h, 
equivalent to 11.8 pig places at a standard ventilation of 85 m3/h per animal place. Results are 
given in Table 4.147.  

Table 4.147:  Cost  ranges  associated  with  the  use  of  two-stage  scrubber  systems  for  exhaust  air 

treatment in fattening pig production, in Germany 

Investment costs 

Annualised 
investment costs 

Operating costs 

Total costs 

Associated costs (1) 

Housing 
capacity 

EUR 
per 
1 000 
m3/h 

EUR/ap 

EUR 
per 
1 000 
m3/h 
per yr 

EUR/ap/yr 

EUR 
per 
1 000 
m3/h 
per yr 

EUR/ap/yr 

EUR 
per 
1 000 
m3/h 
per 
year 

EUR/ap/yr 

68–72 

70–75 

8.7–9.1 

9.1–9.5 

796–851 

826–884 

9.1–10.0 

9.9–10.8 

19.0–20.3 

102–
107 

107–
112 

209–
225 

107–
118 

223–
239 

116–
127 

460–700 animal 
places 
(39 000–
60 000 m3/h) (2) 
1 060–1 180 
animal places 
(90 000–
100 000 m3/h) 
(2) 
1 700–1 850 
animal places 
(150 000–
157 000 m3/h) 
(2) 
3 000 animal 
places 
(255 000 m3/h) 
(3) 
(1) All cost data are given without VAT and are related to hew houses. 
(2) Costs are calculated on the following assumptions: amortisation period of 10 years for the installation and 20 years 
for the building, 6 % interest rate for 50 % of the investment, labour costs EUR 20/h, electricity EUR 0.12/kWh, 
water EUR 0.5/m3, acid EUR 0.25/kg, landspreading of waste water EUR 2.6/m3, maintenance 1 % of investment, 
additional costs for larger slurry store equal EUR 120/m3, additional costs for more powerful fans are EUR 3 per 
1 000 m3 of installed air capacity. 

130 
(120–
140) 

215 
(200–
225) 

745 
(720–
770) 

85 (80–
85) 

102–
113 

196–
212 

17.8–19.1 

16.7–18.0 

746–802 

8.0–8.4 

8.7–9.6 

6.8–7.2 

63–68 

61–65 

17–19 

94–99 

10–12 

(3) Costs are calculated on the following assumptions: amortisation period of 10 years for the installation and 20 years 
for  the  building,  4 %  interest  rate,  labour  costs  EUR 15/h,  electricity  EUR 0.15/kWh,  water  EUR 0.5/m3,  acid 
EUR 0.35/kg, landspreading of waste water EUR 3/m3, maintenance 1 % of investment, additional costs for larger 
slurry store and additional costs for more powerful fans are included. 

Source:[ 514, KTBL 2008 ] [ 122, Germany 2010 ] 

512 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Data related to the investment and total costs are reported  in Table 4.148 for different system 
capacities in pig production in the Netherlands. 

Chapter 4 

Table 4.148:  Costs  associated  with  the  use  of  two-stage  scrubbers  with  an  85 %  NH3  reduction 

efficiency, in the Netherlands  

Pig category 

Housing 
capacity 
(animal places) 
2 016 
130 

Associated costs (1) 

Investment costs 
(EUR/animal place) 
16 
170 

Annual costs (2) 
(EUR/animal place/year) 
4 
35 

Weaners 
Farrowing sows 
Mating  and  gestating 
sows 
4 200 
Fattening pigs 
(1) All cost data are given without VAT. 
(2) Annual costs include depreciation, interest, maintenance and all other operating costs. 
Source: [ 589, Netherlands 2010 ] 

477 

100 

50 

23 

12 

Driving force for implementation 
In  densely  populated  areas  (e.g.  the  Netherlands)  or  in  areas  with  a  high  animal  density,  air 
cleaning systems give farmers the only possibility to construct new housing facilities or expand 
the existing farming activity and still comply with  the maximum allowed levels for ammonia, 
dust or odour emissions. It allows large-scale farms to remain in operation in areas located close 
to residential areas and sensitive ecosystems.  

The  capacity  to  remove  PM10  and  PM2.5  has  made  multi-pollutant  air  cleaning  systems  more 
interesting  for  application  in  poultry  facilities  located  in  areas  exceeding  fine  dust  threshold 
levels in the air [ 424, VERA 2010 ]. 

Example plants 
Several farms in Germany use the technique. 

Reference literature 
[ 122, Germany 2010 ] [ 125, Netherlands 2010 ] [ 127, Netherlands 2010 ] [ 129, Netherlands 
2010 ] [ 424, VERA 2010 ] [ 514, KTBL 2008 ] [ 589, Netherlands 2010 ] [ 646, COM 2013 ] 

4.9.6.2 

Three-stage scrubber: water scrubber combined with wet chemical 
scrubber and biofilter  

Description 
This combination consists of three stages (see Figure 4.74). The first stage is a water scrubber 
that generally removes dust and converts part of the ammonia into nitrate and nitrite by means 
of the microbial activity in the washing water. Different materials and designs can be used for 
the plastic packing of the  filter beds (e.g. having a specific surface area of around 320 m2/m3 
and one filter bed with a thickness of 0.15 m). The recirculating water is not mixed with water 
from the next stage. Given the large filter bed surfaces, it is particularly important for this type 
of  installation  that  the  ventilation  system  can  achieve  an  even  airflow  under  all  climatic 
conditions.  

The  second  stage  is  an  acid  scrubber.  The  filter  bed  is  continuously  sprayed  with  diluted 
sulphuric acid solution and removes the main part of the ammonia content, as long as the pH is 
kept low (e.g. below 5), and dust. It is possible to use different combinations of specific surface 
area  and  filter  bed  thickness.  A  complete  blowdown  is  needed  after  a  fixed  interval  (e.g. 
2 months).  Water  losses  due  to  evaporation  and  elutriation  are  compensated  by  fresh  water 
addition.  

Intensive Rearing of Poultry or Pigs 

513 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The  third  and  last  treatment  stage  is  a  biofilter  (see  Section 4.9.5)  made  of  a  column  packed 
with coarse root wood, which is frequently sprayed with water to keep it moist. The spraying 
frequency depends on the weather conditions. This filter has a larger bed height (at least 0.6 m) 
compared to the scrubbing stages. In this third step, microbes that are present on the root wood 
substrate remove odour compounds and part of the ammonia left from the previous stages. 

Source: [ 139, Netherlands 2010 ] 

Figure 4.74:  Three stage scrubber: water scrubber combined with wet acid scrubber and biofilter  

Achieved environmental benefits 
Emissions  to  air  of  ammonia,  odour  and  dust  are  reduced.  A  reduced  waste  water  volume  is 
produced, 
the  application  of  a  bioscrubber,  as  reported  under 
'Environmental performance and operational data'. 

in  comparison  with 

Cross-media effects 
Additional  energy  consumption  is  required  to  run  pumps  and,  especially,  fans  in  order  to 
overcome  the  increased  pressure  drop  without  any  capacity  loss  (up  to  150 Pa);  the  resulting 
energy consumption may double. Increased water consumption is required due to the necessary 
elutriation. Waste water can be disposed of or reused as fertiliser, e.g. together with the slurry 
for  landspreading  (see  'Environmental  performance  and  operational  data'),  in  which  case  the 
related  load  of  nitrogen  has  to  be  taken  into  account  for  a  correct  planning  of  the  fertiliser. 
Water  from  the  acid  scrubbing  stage  must  be  stored  separately.  Noise  emissions  can  be 
associated with the intense operation of the fans. 

Environmental performance and operational data 
Emission  reductions  have  been  measured  in  pig  farms  in  the  Netherlands  under  the  Dutch 
Livestock Farming Regulation. Ranges for ammonia reduction were from 64 % to 84 %, and for 
odour reduction ranges were from 64 % to 87.9 %. The achievable dust removal is from 94.8 % 
to 97.8 %, of which 80 % is related to PM10. The performance of three-stage systems applied in 

514 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
housing  for  pigs  and  sows  is  reported  in  Table 4.149,  expressed  as  removal  efficiencies  for 
ammonia, odour and dust.  

Chapter 4 

Table 4.149:  Examples of removal  efficiencies achieved with a three stage scrubber system (water 

scrubber, wet acid scrubber and biofilter)  

Housing system 
characteristics  

3 000  animal  places 
for fattening pigs 

1 320  animal  places 
for fattening pigs 

Filter  surface  load 
3 020 m3/(m2 h)  

600  animal  places 
for sows 

Ammonia 
(%) 

70–95 

82.5–97.5  
(warm period) 

Removal efficiencies 

Odour 
(%) 

50–90 

Dust 
(%) 

70–95 

PM10 
(%) 

NI 

79–87.9 (warm period) 
71.1–82.3 (cold period) 

68.1–96 (cold period) 

85 (Dutch ammonia and 
livestock farming 
regulation) 
70.1–79 

75 (based on Dutch 
odour nuisance and 
livestock farming 
regulation) 

64–84 

94.8–97.8 

80 

Filter  surface  load 
3 020 m3/(m2 h)  
NB: NI = no information provided. 

70 (Dutch ammonia and 
livestock farming 
regulation) 

80 (Dutch odour 
nuisance and livestock 
farming regulation) 

95 

80 

Source: [ 123, Germany 2010 ] [ 126, Netherlands 2010 ] [ 128, Netherlands 2010 ] [ 514, KTBL 2008 ]  

Reported  emissions  in  pig  production  after  treatment  of  exhaust  air  with  three-stage  air 
scrubbers are presented in Table 4.150. 

Table 4.150:  Emission  levels  achieved  with  the  application  of  three-stage  scrubbers  in  pig 

production 

NH3 
reduction 
efficiency  
(%) 

System 

Water 
scrubber + 
acid scrubber 
+ biofilter 
combined with 
water curtain  

Water 
scrubber + 
acid scrubber 
+ biofilter 
combined with 
water curtain  

70 

85 

Ammonia  

Odour (2) 

PM10 

Animal 
category 

kg/ap/yr 

ouE/s/animal  g/ap/yr 

Reference 

Weaners 

0.18–0.23 (1) 

1.1–1.6 (2) 

Farrowing sows 

Mating/gestating 
sows 

2.49 

1.26 

5.6 

3.7 

Fattening pigs 

0.75–1.05 (1) 

3.6 (2) 

Weaners 

0.09–0.11(1) 

1.4–2 (2) 

Farrowing sows 

Mating/gestating 
sows 

1.25 

0.63 

7 

4.7 

Fattening pigs 

0.38–0.53(1) 

4.5–5.8 (2) 

26 

42 

44 

55 

26 

42 

44 

55 

 [ 128, 
Netherlands 
2010 ] 

 [ 126, 
Netherlands 
2010 ] 

(1) The higher end of the range corresponds to more space being available per animal. 
(2) The lower end of the range is associated with low-NH3-emitting housing systems. 

Data for energy consumption and other  resources demand, related to a capacity of 1 000 m3/h 
that is equivalent to 11.8 fattening pig places, are shown in Table 4.151. 

Intensive Rearing of Poultry or Pigs 

515 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.151:  Annual resources demand for the operation of a multi-stage scrubber, in Germany 

Resource  

Unit 

Three-stage scrubber 
(consumption per 
1 000 m3/h of capacity) 

Two-stage scrubber 
(consumption per 
1 000 m3/h of capacity) 

kWh/yr 

Energy - Operation of the air 
cleaning system 
Energy – Additional consumption 
for ventilation  
Fresh water  
Sulphuric acid  
Labour 
Source: [ 122, Germany 2010 ] [ 123, Germany 2010 ] 

m3/yr 
kg/yr 
h/yr 

kWh/yr 

130 (100–150) 

190 

215 (180–250) 

20 (16–25) 
27 (20–34) 
0.3–0.4 

250 (220–280) 

21 (14.9–25.5) 
100 
0.4 

The  waste  water  arising  from  the  bioscrubber,  equivalent  to  about  1.8 m3  per  1 000 m3/h 
(0.15 m3/pig place/yr) should be stored (e.g. pumped into the slurry container) and reused taking 
into account the added nitrogen load. Waste water from the acid scrubber stage needs a separate 
storage; their volumes are around 0.7 m3 per 1 000 m3/h (0.06 m3/pig place/yr). 

A reduced amount of waste water is produced by a three-stage scrubber in comparison with a 
bioscrubber. While in the bioscrubber, a good removal efficiency can only be guaranteed if at 
least 0.2 m3/kg NH3 input are elutriated; in three-stage installations, whose removal efficiency is 
at  least  equal  to  bioscrubbers,  only  0.055–0.083 m3/kg  NH3  input  has  to  be  discharged 
separately. The  difference in  the scrubbing  waste  water  produced  is  presented in  Table 4.152, 
for a house of 1 000 pigs located in Germany. 

Table 4.152:  Waste  water  volume  produced  by  air  cleaning  system  in  a  housing  system  for  1 000 

fattening pigs 

Air cleaning system 

Bioscrubber  
Three-stage scrubber  

Elutriation rate  
(m3/kg NH3 input)  

0.2 
0.055–0.083 

Quantity of waste 
water 
(m3/year)  
730 
200–300 

NB: Results are based on an emission factor of 3.64 kg NH3/ap/yr (no crude-protein-adapted feed). 

Acid consumption can be reduced considerably if the system is operated in such a way that the 
nitrification  provides  biogenous  acid  formation  at  the  first  scrubbing  stage  and  the  scrubbing 
water is changed often [ 123, Germany 2010 ]. 

Technical considerations relevant to applicability 
Three-stage  air  cleaning  systems  are  also  applicable  to  littered  housing  since  the  biofilter  is 
preceded by the wet scrubbers which remove dust and/or feathers. 

The ventilation system requires proper planning (air inlet/outlet) and design (sufficient capacity 
of  the  fans  for  the  increased  pressure).  In  retrofitting  existing  houses,  there  are  significant 
additional requirements for the adaptation of the air ventilation outlets and for the upgrading of 
the  fans,  making  the  system  applicable  only  where  a  centralised  ventilation  system  is  used. 
Additionally, significant space is needed to host the various pieces of hardware. 

Economics 
Economic  data  for  exhaust  air  treatment  have  been  modelled  in  Germany  for  modules  of  a 
capacity  of  1 000  m3/h,  equivalent  to  11.8  pig  places  at  a  standard  ventilation  of  85  m3/h  per 
animal  place.  Results  for  different  system  capacities  in  fattening  pig  production  are  given  in 
Table 4.153.  

516 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.153:  Cost  ranges  associated  with  the  use  of  three-stage  scrubber  systems  (combining  a 
water scrubber, wet acid scrubber and biofilter) in fattening pig houses  

Associated costs (1) (2) 

Housing 
capacity 

Investment 
costs 

EUR 
per 
1 000 
m3/h 

EUR/
ap 

Annualised 
investment costs 
EUR per 
1 000 
m3/h per 
yr 

EUR/a
p/yr 

Operating costs 

Total annual costs 

EUR per 
1 000 
m3/h per 
yr 

EUR/
ap/yr 

EUR per 
1 000 
m3/h per 
year 

EUR/ap/yr 

60–68 

60–
94 

45–
57 

82–116 

5.1–5.8 

103–122 

128–166 

163–190 

210–282 

8.8–
10.4 

7.0–
9.96 

531–
671 

17.9–24.00 

700–
1100 

10.9–
14.1 

460–700 
animal places 
(39 000–
60 000 m3/h) 
1 060–1 180 
animal places 
(90 000–
100 000 m3/h) 
1 700–1 850 
animal places 
(150 000–
157 000 m3/h) 
3 000 animal 
places 
(255 000m3/h) 
(1) All cost data are given excluding VAT. 
(2) Costs are calculated on the following assumptions: amortisation period of 10 years for the installation and 20 years 
for the building, 6 % interest rate for 50 % of the investment, labour costs EUR 20/h, electricity EUR 0.12/kWh, 
water  EUR 0.5/m3,  acid  EUR 0.25/kg,  landspreading  of  waste  water  EUR 2.6/m3,  maintenance  1 %  of 
investment, additional costs for larger slurry store equal EUR 120/m3, additional costs for more powerful fans are 
EUR 3 per 1 000 m3 of installed air capacity. 
Source:[ 514, KTBL 2008 ] [ 123, Germany 2010 ] 

6.80–
8.5 

500–
615 

474–
589 

14.9–16.6 

13.4–15.1 

8.6–
9.5 

130–160 

153–171 

101–112 

11–13.5 

4.4–5.0 

80–100 

43–
52 

40–
50 

50–60 

52–59 

4.2–5 

Investment  and  operating  costs  related  to  the  application  on  a  newly  built  facility  of  a  three-
stage  system  with  a  bioscrubber  as  the  third  stage,  in  place  of  a  biofilter,  are  reported  in 
Table 4.154. 

Table 4.154:  Investment  and  annual  operating  costs  for  a  three-stage  scrubber  (water  and  acid 

scrubber + biotrickling) applied to a newly built facility for fattening pig production 

Investment costs (1) 
Operating costs 

Annualised investment cost (10 %)  
Maintenance (3 %)  
Interest (6 %)  
Electricity use (EUR 0.11/kWh) 
Water use (EUR 1.0/m3)  
Chemical use (EUR 0.6/litre H2SO4, 98 %)  
Water discharge (2) 
Total annual operating costs 

EUR/animal place/yr 
50.3 

4.2 
2.0 
1.2 
3.7 
0.6 
0.7 
1.0 
9.2 
13.5 

Total annual costs  
(1) The investment costs are based on a maximum ventilation capacity of 60 m3/ap/h. 
(2) Waste water disposal costs are assumed to be equivalent to EUR 10/m3 for discharges from acid scrubbing 
and EUR 2/m3 for discharges  from biotrickling or water  scrubbing. Discharge  water  from the biotrickling 
and water scrubbing stages is reused in the acid scrubbing stage. 

Source:[ 568, Melse et al. 2010 ] 

Intensive Rearing of Poultry or Pigs 

517 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
In  individual  cases  of  insufficient  spatial  distance  from  the  nearest  existing  or  planned 
residential buildings or other odour-sensitive constructions, as is the case in densely populated 
areas (e.g. in the Netherlands), or from nitrogen-sensitive ecosystems (e.g. forests), air cleaning 
systems  give  farmers  the  only  possibility  to  expand  the  activity  and  still  comply  with  the 
maximum levels allowed for ammonia, dust or odour emissions.  

The  capacity  to  remove  PM10  and  PM2.5  has  made  multi-pollutant  air  cleaning  systems  more 
interesting  for  application  in  poultry  facilities  located  in  areas  exceeding  fine  dust  threshold 
levels in the air [ 424, VERA 2010 ]. 

Example plants 
The system is in operation in several pig farms in the Netherlands and Germany.  

Reference literature 
[  122,  Germany  2010  ]  [  123,  Germany  2010  ]  [  126,  Netherlands  2010  ]  [  128,  Netherlands 
2010 ] [ 139, Netherlands 2010 ] [ 424, VERA 2010 ] [ 514, KTBL 2008 ] [ 568, Melse et al. 
2010 ] 

4.9.7 

Partial air treatment in air cleaning systems 

Description 
In  forced  ventilated  houses,  ventilation  rates  depend  on  the  production  stage  and  climatic 
conditions; the ventilation system does not operate at its maximum capacity over the course of 
the year. Therefore, maximum (for summer) and average exhaust airflow rates can be defined 
and air cleaning systems can be dimensioned accordingly. In this case, it is possible to install an 
air bypass system so that a portion of the exhaust air can be expelled from the  house without 
being treated, whilst the remaining exhaust air passes through the air cleaning system. Hence the 
air  cleaning  systems  are  operated  at  designated  airflow  rates,  which  are  lower  than  the 
maximum ventilation rates that can occur in the animal house. 

Achieved environmental benefits 
The size of the air cleaning system is reduced, resulting in an increased efficiency of scrubber 
utilisation (kg of NH3 removed per m3 of scrubber volume). The technique of partial treatment 
of exhaust air ensures that ventilation needs are met for the health and welfare of the animals 
and that air cleaning systems can be still operated efficiently. 

Cross-media effects 
The  disadvantage  of  this  technique  is  that  peak  emission  management  is  not  possible  (e.g. 
summer  heat,  heavier  animals  requiring  high  ventilation  rates).  For  ammonia  emission  levels, 
which  are  generally  set  in  terms  of  yearly  averages,  this  disadvantage  may  be  irrelevant; 
however, for other pollutants such as dust and odour, for which peak emission levels are usually 
established, it may cause an above average nuisance to the neighbourhood.  

Environmental performance and operational data 
Ammonia  emission  levels  and  the  associated  costs  for  implementing  the  cleaning  system  are 
presented  in  Table 4.155.  Data  for  a  two-stage  bioscrubber  and  for  a  two-stage  chemical 
scrubber are reported for different percentages of exhaust air treated by the air cleaning system. 

518 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 4.155:  Emission levels and cost data for different percentages of exhaust air treated by two-

stage air cleaning systems 

Chapter 4 

Type of cleaning 
system 

Percentage of exhaust 
air treated (%) 
100 
60 
40 
20 
100 
60 
20 

Bioscrubber 
Bioscrubber 
Bioscrubber 
Bioscrubber 
Acid scrubber 
Acid scrubber 
Acid scrubber 
(1) Cost data are calculated on the basis of a production of four pigs per animal place per year. 
NB: NI = no information provided. 

Ammonia emissions 
(kg NH3/ap/yr) (1) 
0.44 
0.56 
NI 
0.88 
0.40 
0.56 
1 

Total costs 
(EUR/ap/yr) (1) 
12 
7.6 
2.8 
NI 
NI 
NI 
NI 

Source: [ 53, Denmark 2010 ] [ 54, Denmark 2010 ] 

Technical considerations relevant to applicability 
Bypasses may only be installed if local regulations allow (e.g. in the Netherlands, bypasses are 
not allowed). The principle of the technique is independent of the animal category; therefore, it 
is applicable in pig and poultry rearing. 

Economics 
The investment cost per m3 of exhaust air to be treated will be only slightly higher due to the 
additional  costs  of  the  bypass  itself.  On  the  other  hand,  the  total  costs  for  air  cleaning  are 
reduced as the investment and operating costs of scrubbers are related to their size. 

Driving force for implementation 
Low emission levels can be achieved at reduced costs of treatment with air cleaning system. In 
this  way,  it  is  possible  to  design  the  ventilation/cleaning  system  on  the  basis  of  the  required 
reduction levels set for a specific location by the competent authorities.  

Example plants 
This technique is commonly used in Denmark upon permit specification. 

Reference literature 
[ 13, Melse 2009 ] [ 53, Denmark 2010 ] [ 54, Denmark 2010 ] [ 514, KTBL 2008 ] 

4.9.8 

Dry filters 

Description 
The air being drawn to the exhaust outlet passes through a filter, placed in a plenum chamber in 
front of the exhaust fan, made of multi-layered plastic or paper filters for example, which forces 
the  air  to  change  direction  many  times  within  the  body  of  the  filter  (see  Figure 4.75).  The 
centrifugal force of air circulating in the many cavities of the filter separates the dust from the 
airflow, allowing dust particles to fall and be collected in V-shaped filter pockets.  

Intensive Rearing of Poultry or Pigs 

519 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 136, UK 2009 ] 

Figure 4.75:  Schematic of a dry filter installed in a broiler house 

Achieved environmental benefits 
Reduction of dust emissions is the achieved environmental benefit. 

Cross-media effects 
The filters need to be cleaned regularly, and the collected dust can be spread on land with the 
manure.  Filters  do  present  a  resistance  to  airflow,  so  fans  must  operate  at  a  higher  pressure. 
Therefore, the system must allow for the high air volume and air speed necessary for heat stress 
relief in broilers. 

Environmental performance and operational data 
Commercial  results  suggest  a  70 %  reduction  in  visible  exhaust  dust.  The  dust  removal 
efficiency has been measured in one broiler farm as 41 % ± 4 for PM2.5 and 64 % ± 6 for PM10 
fractions. Bacteria and fungi concentrations  were reduced by 1 % and 20 % (on a logarithmic 
scale), respectively.  

Technical considerations relevant to applicability 
The system can be retrofitted in poultry houses with a tunnel ventilation system. 

Economics 
Investment,  operating  and  maintenance  costs  are  significantly  reduced  compared  to  wet 
scrubbing systems used for air treatment. The capital cost for the installation of a dry filter is 
estimated  to  be  about  EUR 1.14  (EUR 1  =  GBP 0.88)  per  30  m3  of  air,  the  same  cost  as  for 
treating 3–4 m3 of air with a wet scrubbing system.  

Driving force for implementation 
Local regulations imposing limit values for dust emissions are the driving force. 

Example plants 
Several examples have been fitted in UK broiler farms. 

Reference literature 
[ 136, UK 2009 ] 

520 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
4.9.9 

Water trap 

Description 
The  exhaust  air  is  directed  downwards  onto  a  water bath  (e.g.  15 cm  pit  containing  water) to 
soak  up  dust  particles,  and  then redirected  180 °  upwards  to  the air to  disperse any  pollutants 
further  (see  Figure 4.76).  The  water  bath  needs  to  be  filled  regularly  to  compensate  for 
evaporation. 

Chapter 4 

Source: [ 136, UK 2009 ] 

Figure 4.76:  Scheme of the water trap 

Achieved environmental benefits 
Dust emissions are reduced. 

Cross-media effects 
None reported. 

Environmental performance and operational data 
Abatement of emissions has been reported for PM2.5 and PM10 as 19 % and 22 %, respectively. 
Abatement  of  bacteria  and  fungi  has  also  been  reported  to  be  equivalent  to  16 %  and  4 %, 
respectively, on a logarithmic scale. Water can be landspread. 

Technical considerations relevant to applicability 
The system can be retrofitted in poultry houses with a tunnel ventilation system. 

Economics 
No information provided. 

Driving force for implementation 
Local regulations may impose limit values for dust emissions. 

Example plants 
The technique is used in poultry farms in the UK. One example has been reported from a farm 
that rears more than 30 000 broilers.  

Reference literature 
[ 136, UK 2009 ] 

Intensive Rearing of Poultry or Pigs 

521 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.10  Techniques for the reduction of odour emissions 

Odours are indigenous to all livestock production operations. Odour mainly originates from the 
microbial  conversion  of  feed  (protein  and  fermentable carbohydrates)  in  the  intestinal  tract  of 
pigs  and  by  the  microbial  conversion  of  urinary  and  faecal  compounds  in  the  manure  under 
anaerobic  conditions.  Odour  is  a  complex  mixture  of  many  different  compounds,  such  as 
sulphurous compounds (e.g. H2S,  mercaptans), indolic and phenolic compounds, volatile fatty 
acids  (e.g.  acetic  acid,  n-butyric  acid),  ammonia  and  volatile  amines  [  511,  Le  et  al.  2007  ] 
[ 270, France 2010 ].  

Odour is the principal concern of local communities in relation to both pig and poultry farms. 
Odour arises from animal housing, as well as from manure transfer, storage, and spreading. The 
odours are diffused in gas form and/or are conveyed by dust. 

The level of odour that arises from pig  or poultry farms varies significantly and the degree of 
nuisance  of  a  particular  odour 
location  and  context  
[  204,  IMPEL  2009 ].  Small  volumes  of  very  strong  odours  can,  under  unfavourable 
circumstances,  travel  far  and  cause  a  strong  odour  intensity  to  be  perceived  by  persons 
downwind.  As  this  perception  can  be  of  a  high  intensity,  this  can  trigger  annoyance  and 
exacerbate nuisance [ 668, IE EPA 2001 ].  

level  varies  according 

to 

4.10.1 

General measures for odour prevention 

Odour can be reduced in a number of other ways, including: 

 

 

 

 

by good housekeeping; 

by storing the manure outside under a cover; 

by preventing an airstream from passing over the manure; 

by keeping straw-based manure under aerobic conditions in order to rapidly break down 
the odorous substances. 

For  reasons  relating  to  odour,  application  times  and  techniques  have  been  developed  for 
landspreading.  Some  additional  techniques  to  reduce  odour  in  the  vicinity  of  the  farm  are 
applied on farm to animal houses with forced ventilation. These include: 

 

 

horizontal air outlet channel, which does not mean a reduction of odour, but which diverts 
the emission point of air from the housing to a different side of the farm, so as to reduce 
the potential impact for odour-sensitive receptors (e.g. residential areas);  

dilution of the concentration, which is explained below and is based on the proper design 
of the housing and dimensioning of the ventilation. 

4.10.1.1 

Dilution of odorants 

The odorant concentration depends, essentially, on the degree of dilution of the odorants emitted 
the  airstream.  Important  factors  affecting  pollutant 
during  atmospheric 
concentration are: 

transport 

in 

 

 

 

 

522 

the odorant flow rate; 

the distance from the source; 

the effective source height and relative elevation of the source and the receptor;  

atmospheric conditions, local topography and features (surface roughness). 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

In addition, atmospheric dilution increases with the degree of turbulence in the atmosphere and 
the airstream. Mechanical turbulence can be achieved through the effective placement of flow 
barriers (e.g. vegetation). 

The interaction of the above factors and the share of each one will finally determine the odour 
dilution. In many cases, distancing the source from the receptor is the only meaningful way to 
dilute  odorants  since  the  alternative  measures  described  in  this  section  may  entail  restrictions 
and disadvantages (e.g. outlet height, exhaust speed). Using standard distances for new farms in 
land use planning is a good practice [ 204, IMPEL 2009 ]. 

In many MS, in order to protect residents against significant odour nuisance, minimum distance 
regulations  for  the  assessment  of  odour  and  the  spatial  separation  of  farms  and  dwellings  or 
residential areas have been established, for instance in Germany by the Association of German 
Engineers (VDI; Guideline VDI 3894/2  'Emissions from and impacts of livestock operations  - 
Method to determine separation distances  – Odour', 2012-11). In Germany, odour impacts are 
assessed  as  significant  and  legally  not  allowed  if  a  frequency  of  odour  perception  of  10 % 
(general  residential  areas)  or  15 %  (village  areas)  of  the  time  is  exceeded  for  an  odour 
concentration of 1 ouE/m3 [ 590, Batfarm 2013 ]. 

In the Netherlands, the regulatory system is also based on the principle that the odour loads on 
surrounding  areas  of  livestock  operations  are  predicted  by  a  standardised  odour  dispersion 
model.  This  model  (V-Stacks),  modified  from  the  national  Gaussian  plume  model,  calculates 
98th  percentile  values  for  the  surrounding  residential  homes,  and  makes  use  of  nationally 
standardised  odour  emission  values.  In  the  case  of  permitting  procedures  for  livestock 
operations (new or modified farms), the odour load is calculated for the applied new situation 
and the calculated percentile values are checked to ensure that they do not exceed the allowed 
maximum  percentile  values  in  specific  residential  areas.  Default  maximum  odour  loads  are 
nationally  defined  by  the  Ministry  of  Environment  for  different  types  of  residential  areas. 
Municipalities  are  allowed  to  deviate  from  this  default  value  and  to  define,  within  a  preset 
range,  their  own  local  standard.  The  model  input  is  based  on  a  regulatory  national  list  with 
odour emission factors for the different animal categories and their housing systems expressed 
as ouE/s/animal [ 153, Netherlands 2010 ]. 

4.10.1.2 

Discharge conditions 

The principles of natural ventilation and forced ventilation result in different waste air discharge 
conditions. While the exit apertures for the housing air are limited to a narrow cross section in 
the  case  of  forced  ventilated  housing,  with  naturally  ventilated  housing,  they  are  occasionally 
quite large. In those housing systems, the cross sections through which air enters and exits are 
adjustable in  accordance  with  the  meteorological  and  local  climatic  conditions  outside  the 
housing, and with the livestock-specific ventilation requirements inside the housing. Common 
to both systems are thermal upcurrents in the housing caused by the heat output of the livestock 
and the possible presence of heating equipment. 

Essentially,  an  unimpeded  incoming  and  outgoing  flow  of  outside  air  must  be  ensured  in  the 
immediate vicinity of the housing (approximately three to five times the building height). With 
forced ventilation, the use of the area in the immediate vicinity of the housing determines the 
discharge  conditions  to  be  selected,  e.g.  side  wall  ventilation  leading  into  the  yard,  or  high 
discharge stacks above the ridge. In the case of naturally ventilated housing, a local odour may 
be  regarded  as  acceptable,  where  the  emphasis  is  predominantly  on  the  effect  of  the  housing 
emissions further afield. 

Forced ventilation 
As a rule, with forced ventilated housing the focus in terms of impact reduction is on achieving 
sufficient dilution of the waste air  by the wind. In order to protect the local neighbourhood, it 
may  be  generally  advisable  to  ensure  that  the  emission  airstreams  pass  at  a  certain  minimum 

Intensive Rearing of Poultry or Pigs 

523 

 
 
 
 
 
 
 
 
Chapter 4 

height over and beyond local dwellings by raising the source height, so that entrainment of the 
waste air plume in the wake zone of the building (downwash effect) can be kept to a minimum. 
This effect can be achieved by increasing the waste air exit velocity and/or raising the height of 
the waste air discharge stack. 

The exhaust air should be discharged through sufficiently high stacks vertically upwards above 
the roof level without any flow-inhibiting hoods or covers. To this end, the local area and the 
farm/plant  location  should  be  examined  to  determine  whether,  for  example,  the  exhaust  air 
discharge  stack  could  be  raised  to  a  higher  level  at  the  gable  of  a  barn  building  for  example 
where this barn towers over the livestock building. 

The waste air plume can be given a further upward boost by imparting to it greater mechanical 
momentum  by  increasing  the  waste  air  discharge  velocity.  The  waste  air  velocity  can,  for 
example, be increased upon necessity, e.g. by gang-switching multiple series of fans in a main 
central air duct. 

The installation of an additional bypass fan is effective as an impact-reducing measure only in 
certain cases and for the local area, and usually tends to have no effect. Apart from the increase 
in  investment  outlay  and  energy  consumption,  the  additional  noise  emissions  also  have  to  be 
taken into account. 

When  planning  a  waste  air  discharge  system,  it  is  important  to  consider  the  influences  of 
livestock buildings and flow barriers in the immediate environment on both the windward and 
lee  sides  of  the  facility  (e.g.  the  roof  ridge  of  neighbouring  buildings,  and  trees).  Livestock 
buildings and flow barriers give rise to a plume downwash effect. 

In  the  case  of  a  single  livestock  building,  the  downwash  effect  depends  on  the  relationship 
between the effective source height and the building height. The downwash effect describes the 
influence of the building on the waste air plume and the subsequent reduction in the effective 
source  height.  Undisturbed  airflow  is  attained  at  a  height  which  corresponds  to  twice  the 
building height. 

Side  wall  ventilation  apertures  may  be  regarded  as  desirable  in  individual  cases  if  they  are 
provided with a deflector cover which directs the waste air towards the ground, and if the air is 
dispersed on the housing side which faces away from the sensitive receptor requiring protection. 
When  comparing  the  effects  caused  by  side  wall  ventilation  on  the  one  hand  and  exhaust  air 
discharge  via  the  ridge  on  the  other,  the  air  pollution  encountered  in  locations  further  afield 
tends to be similar. 

In the case of facilities with several livestock buildings, the position and height of the waste air 
sources  play  a  subordinate  role  in  relation  to  their  impact  in  terms  of  air  pollution  at  remote 
locations. In such cases, the total area of the facility may be so large that the waste air plumes 
descend to ground level within the facility site, even if the original source heights are large. The 
overall  facility  is  then  considered  to  have  the  same  effect  as  a  single  ground-level  surface 
source. 

With  a  different  approach,  forced  ventilation  has  the  advantage  of  allowing  the  easy 
implementation of air cleaning techniques. 

524 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Natural ventilation 
In order to ensure sufficient functional efficiency with natural ventilation, certain requirements 
have to be met, for example the following: 

 

 

 

 

 

roof  pitch  angle  of  at  least  20 °  for  eaves-ridge  ventilation  in  order  to  generate  the 
necessary thermal upcurrent; 

mean height difference of at least 3 metres between the inlet air apertures and the waste 
air apertures with shaft ventilation; 

dimensioning  of  the  air  inlet  and  waste  air  apertures  in  accordance  with  the  livestock 
occupancy and thermal upcurrent lift height; 

guaranteed disturbance-free flows of incoming fresh air and outgoing waste air into and 
from the housing; 

ridge axis aligned transverse to the prevailing wind direction for new plants. 

If  buildings  are  located  upstream  and/or  downstream  of  an  open  housing  system,  it  must  be 
ensured  that  the  livestock  building  is  not  located  in  zones  with  very  low  or  significantly 
accelerated air movement. The distance from the housing to the neighbouring buildings should 
be at least three to five times the height of the neighbouring buildings. 

In the case of pig and poultry housing systems, the installation of devices for changing the air 
inlet and waste air aperture cross sections has proven to be successful. 

By  aligning  a  new  livestock  building  in  relation  to  the  prevailing  wind  direction,  a  decisive 
influence can be exerted on both the internal environmental conditions of the housing and the 
emissions  emanating  from  it.  Different  concentration  and  velocity  fields  occur,  depending  on 
whether  the  housing  is  subjected  to  transverse,  diagonal  or  ridge-parallel  through-flow.  With 
ridge-parallel  flow  patterns  in  particular,  the  degree  of  ventilation  compared  with  cross-flow 
patterns is reduced by approximately 50 %. It is under these conditions that the highest odorant 
and ammonia concentrations arise in the housing. 

In order to combat this effect, apertures in the gable wall can enhance the wind-induced volume 
flow. Apertures at the centre of the ridge additionally assist thermal upcurrent flow. With a slot 
aperture running along the entire ridge, higher throughput rates are achieved than with shafts. 
The ridge axis of the housing should therefore be aligned to the wind so that in the course of the 
year the prevailing direction of wind flow produces the best possible through-ventilation effect. 

The air inlet and waste air apertures of housing systems with eaves-ridge ventilation have to be 
dimensioned so that in times of high outdoor temperatures there is still sufficient air circulation. 
Otherwise,  doors  must  be  opened,  which  generally  results  in  the  emissions  dispersing  at  the 
ground level and in an uncontrolled fashion. 

Housing systems of an open design with large lateral cross sections, ridge slots and gable-end 
apertures, located in a free-standing position, can be regarded as desirable in terms of the impact 
effects encountered further afield (e.g. box stalls with separate functional areas). 

4.10.1.3 

Dietary effects 

Dietary protein is a precursor of odour production in the intestines of animals and in manure as 
the excretion of protein and its metabolites (e.g. urea) in the excreta of pigs provides substrates 
for bacteria to generate odour; thus, it is logically expected that odour emissions can be reduced 
as the dietary crude protein level decreases.  

Intensive Rearing of Poultry or Pigs 

525 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

On the other hand, it is also reported that there is no significant influence of feeding strategies 
on odour emissions, although the odour quality may change [ 513, Mol and Ogink 2002 ]. Other 
trials  on  the  effect  of  reduced  protein  levels  in  the  diet  found  no  difference  at  all  when  a 
relatively low-protein diet was already used [ 330, Denmark 2010 ] [ 326, Germany 2010 ]. 

Some  experiment  results  reported  a  decrease  in  odour  concentration  and  emission  from  pig 
manure, when dietary crude protein was reduced (by nearly 80 % by reducing the crude protein 
from  18 %  to  12 %  and  supplementing  essential  amino  acids  [  511,  Le  et  al.  2007  ]).  This 
reduction  was  relevant  for  specific  odorous  substances  (idolic,  phenolic  and  sulphurous 
compounds). Other results show that the composition and the quality of odour are influenced by 
the  protein  level  supplied  in  the  diet,  while  the  odour  concentration  hardly  reacts  
[ 512, Andree et al. 2003 ]. 

Also,  fermentable NSP  (non-starch  polysaccharides)  are  important  dietary  components  that 
determine  the  concentration  of  volatile  fatty  acids  in  the  manure  and,  consequently,  have  an 
influence on odour emissions [ 513, Mol and Ogink 2002 ]. It is suggested that odour emissions 
can  be  reduced  by  decreasing  protein  fermentation  through  an  optimum  balance  between 
available  protein  and  fermentable carbohydrates  in  the  large  intestine  [  448,  Aarnink  et  al. 
2007 ]. 

Odour strength and offensiveness are measured by olfactometry and results are not always clear 
as it is difficult to assess odours objectively [ 512, Andree et al. 2003 ] [ 590, Batfarm 2013 ]. 
This  might  explain  the  difference  in  reported  effects  of  dietary  modifications  on  odour 
emissions. As a concluding remark for the relationship between nutrition and odour emission, 
more  research  is  needed  but  it  seems  that  there  is  great  potential  for  environmental  benefits 
[ 324, Netherlands 2010 ]. 

4.10.1.4 

Air cleaning systems 

Local  conditions  may  be  decisive  for  the  adoption  of  abatement  techniques,  as  is  the  case  of 
densely  populated  areas  in  the  Netherlands.  The  applicability,  cross-media  effects  and  costs 
might generally limit the adoption of the techniques given below or, alternatively, the positive 
effect on odour abatement in addition to the ammonia emission reduction may encourage their 
implementation.  

Once  the  air  can  be  ducted  to a  central  point  for treatment,  there  are a  number  of  options  for 
reducing the odour concentration in the exhaust air. A number of options have been listed here: 

 

 

Bioscrubber, see Section 4.9.3.  

Biodegradation,  by  leading  the  air from  the  housing  through  a  biofilter of fibrous  plant 
material,  odorous  elements  are  broken  down  by  bacteria.  The  effectiveness  depends  on 
moisture content, composition, airflow per square metre of filter bed, and filter height. In 
particular, dust can be a problem, creating high air resistances (see Section 4.9.5). 

 

Two-stage or three-stage air cleaning system, see Section 4.9.6. 

4.10.1.5 

Odour management plan 

Description  
An odour management plan is compatible with the concept of the environmental management 
system (EMS) approach as described in Section 4.2. The odour management plan can be a part 
of the EMS of the farm. 

526 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
As odour arises from different operational areas, it is good practice for the odour management 
plan to include all potential sources of  odour in the  farm operations (housing, manure storage 
and spreading) and to seek to control them in an integrated way [ 204, IMPEL 2009 ].  

An odour management plan includes the following elements: 

Chapter 4 

 

 

 

 

 

a protocol containing appropriate actions and timelines; 

a protocol for conducting odour monitoring; 

a protocol for response to identified odour nuisance; 

an  odour  prevention  and  elimination  programme  designed,  for  example,  to  identify  the 
source(s),  to  monitor  odour  emissions  (see  Section  4.18.4),  to  characterise  the 
contributions of the sources and to implement elimination and/or reduction measures; 

a  review  of  historical  odour  incidents  and  remedies  and  the  dissemination  of  odour 
incident knowledge. 

Some MS, such as the UK, implement an odour management plan when there is an issue with 
odour from the site, as a first step in reducing odour emissions [ 624, IRPP TWG 2013 ]. The 
approved odour management plan may be made available to the public. 

Achieved environmental benefits  
The  minimisation  of  odorous  emissions  is  the  achieved  environmental  benefit.  Many  of  the 
management techniques to reduce odour will also simultaneously reduce other emissions to air, 
including ammonia. 

Cross-media effects  
There are no cross-media effects associated with the implementation of this technique.  

Environmental performance and operational data  
No information provided.  

Technical considerations relevant to applicability  
The  technique  is  applicable  to  new  and  existing  farms  provided  that  an  odour  nuisance  at 
sensitive receptors is expected and/or has been substantiated.  

Economics 
No information provided.  

Driving force for implementation  
Management  systems  are  likely  to  be  less  of  a  cost  burden,  or  may  even  improve  financial 
returns for producers, as they often imply lower capital costs and lower resource (energy, water, 
chemicals etc.) usage than end-of-pipe treatments.  

Example plants 
No information provided.  

Reference literature  
[ 19, Environment Agency (England and Wales) 2011 ] [ 204, IMPEL 2009 ] [ 624, IRPP TWG 
2013 ] 

Intensive Rearing of Poultry or Pigs 

527 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.10.2 

Good operational practice in pig housing 

Sources  of  odour  in  and  around  buildings  and  practices  to  reduce  odour  emissions  in  pig 
housing include the following: 

 

 

 

Cleanliness: It is good operational practice to keep the pigs and the surfaces in and around 
buildings clean. Pigs with manure on their skin will have a significantly increased odour 
emission,  as  the  body  heat  of  the  animal  will  accelerate  the  release  of  odours 
significantly. In addition, reducing the exposed area of manure and avoiding spilled feed 
induce a direct reduction in odour emissions.  

Dryness: Optimum control of the housing environment, particularly during summer, can 
contribute to ensuring that pigs excrete in the dunging area while the lying and activity 
area remain clean and dry. Drinking water losses should be avoided by employing low-
loss  drinking  equipment.  For  litter-based  systems,  the  level  of  odorant  emissions 
decreases as the quantity of litter per livestock unit increases. 

Slurry removal: In liquid manure systems, the odorant emissions from the houses can be 
reduced  if  the  dung  and  urine  are  removed  from  the  housing  at  short  intervals  or  in  a 
continuous  process.  Long  residence  times  in  a  manure  storage  pit  and  large  storage 
volumes increase the emissions of odorants. As a general principle, pig manure has to be 
removed  to  adequate  storage  pits or be  subjected to an  appropriate  treatment,  including 
landspreading, as quickly as practicable, e.g. by shallow channels with a flushing system 
for rapid discharge.  

It  is  generally  considered  that  most  techniques  described  in  the  previous  sections  which  are 
mostly intended for abating ammonia and dust emissions can have a reducing effect on odour 
emissions. However, a research programme carried out in the Netherlands [ 513, Mol and Ogink 
2002 ] [ 153, Netherlands 2010 ] showed that odour emissions from livestock operations were 
highly variable both within individual farms (in time) and between farms. Measured differences 
reflect  to  a  major  extent  uncontrolled  management  effects.  Even  when  corrected  for  the 
significant effect of the ventilation rate, it was difficult to make significant distinctions between 
the various systems. The major conclusions were: 

 

 

 

ammonia-reducing housing systems do not necessarily reduce odour emission;  

this  effect  is  not  consistent  throughout  all  animal  categories,  depending  on  the 
characteristics of their odour emissions; 

small  significant  differences  between  conventional  and  low-ammonia-emission  housing 
systems were proved only for fattening pigs. 

In some circumstances, such as housing systems for pigs with frequent removal of manure by 
flushing  gutters  underneath  the  slats,  ammonia  emissions  can  be  significantly  reduced,  while 
odour emissions may be high, with levels during flushing events 3 to 3.5 times higher than those 
from other housing systems. Various other factors, like farm hygiene, type and feeding regime, 
and water to feed ratio, have a significant influence on odour emissions from livestock buildings 
and  can  conceal  the  emission-reducing  effects  of  the  housing  systems  [  513,  Mol  and  Ogink 
2002 ].  

A  measurement  research  campaign  in  the  Netherlands,  aiming  to  minimise  the  effects  of 
management  factors,  showed  that  on  three  of  the  five  tested  farms  statistically  significant 
differences  between  the  conventional  housing  system  (partly  slatted  floor)  and  an  ammonia-
reducing  housing  system  (restricted  emission  surface  or  a  manure-cooling  system)  were  only 
found  for  weaners  and  fattening  pigs.  The  average  odour  reduction  percentages  for  these 
systems  were  35 %  (restricted  emission  surface)  and  23 %  (manure  cooling)  respectively  
[ 153, Netherlands 2010 ]. 

528 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

In general, with regard to odorant emissions per unit of live animal mass, generally only small 
differences between the different housing techniques have been proven [ 474, VDI 2011 ]. 

The main principles utilised by low-ammonia-emission housing systems for reducing emissions 
to air from pig housing are: 

 

 

 

 

 

 

limiting the exposed area of stored manure; 

frequent removal of manure by a sewerage system, flushing or scraping; 

cooling manure, lowering the temperature of stored manure; 

faster discharge of the manure from slats, by using triangular iron bars, which are easily 
cleaned; 

decreasing the temperature of the indoor environment, the airflow and velocity over the 
manure surface while maintaining an acceptable living environment for the animals; 

keeping the litter dry and under aerobic conditions in litter-based systems. 

Further  details  on  specific  housing  systems  for  pig  housing  and  on  their  associated  odour 
emissions can be found in Section 4.7. 

4.10.3 

Good operational practice in poultry housing 

Odour from broiler housing is reported to increase in offensiveness with the moisture content of 
the litter. 

Sources  of  odour  in  and  around  buildings  and  practices  to  reduce  odour  emissions  in  poultry 
housing include the following: 

 

 

Cleanliness and dryness: Drinking water losses should be avoided by employing low-loss 
drinking equipment (e.g. nipple drinkers). The level of odorant emissions decreases as the 
quantity of litter per livestock unit increases.  

Manure removal: In liquid manure systems, the odorant emissions from the housing can 
be reduced if the manure is removed from the housing at short intervals or in a continuous 
process. Long residence times in a manure storage pit and large storage volumes increase 
the emissions of odorants. As a general principle, manure must be removed to adequate 
storage  pits  or  be  subjected  to  an  appropriate  treatment,  including  landspreading,  as 
quickly as practicable.  

A Dutch research programme did not show consistent differences in odour emissions between 
conventional housing systems and those designed for low ammonia emission (e.g. with drying 
of  the  manure  collected  on  belts)  in  each  specified  poultry  category.  The  assigned  odour 
emission value was based on all available measurements. For air scrubbers, the observed mean 
removal  percentage  of  chemical  scrubbers  (30 %)  was  included  for  the  different  poultry 
categories [ 153, Netherlands 2010 ].  

4.10.4 

Slurry storage  

Slurry storage can be a highly significant source in terms of odour annoyance potential. Under 
anaerobic  conditions,  high  concentrations  of  odorants  can  be  formed  in  slurry,  which  can  be 
released in highly concentrated ‘puffs’ when slurry is being handled. Turbulence, resulting from 
stirring  and  pumping,  can  increase  the  emissions  from  the  surface  by  an  order  of  magnitude 
(factor  10)  compared  to  a  still  surface.  In  assessing  the  relevance  of  slurry  storage  for  odour 

Intensive Rearing of Poultry or Pigs 

529 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

annoyance potential, it helps to realise that odour concentrations over slurry, or in headspaces, 
can reach tens or even hundreds of thousands of ouE/m3, whereas the odour concentration in pig 
house ventilation air rarely exceeds 5 000 ouE/m3 [ 668, IE EPA 2001 ].  

The techniques for storage having a significant effect on odour emissions are (see Section 4.11): 

 

 

 

covering of slurry or solid manure during storage; 

location of the store taking into account the general wind direction and/or adopt measures 
to reduce the wind speed around and above the store (e.g. trees, natural barriers); 

minimisation of the stirring of slurry. 

4.10.5  Manure processing  

The  techniques  for  manure  (solid  or  slurry)  processing  having  a  significant  effect  on  odour 
emissions are (see Section 4.12): 

 

 

 

aerobic digestion (aeration) of liquid manure/slurry; 

composting of solid manure; 

anaerobic digestion. 

4.10.6 

Landspreading 

The  techniques  for  landspreading  having  a  significant  effect  on  odour  emissions  are  (see 
Section 4.13): 

 

 

use of a band spreader, shallow injector or deep injector for landspreading of slurry; 

incorporation of manure as soon as possible. 

530 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.11  Techniques for the reduction of emissions from manure 

storage 

The  Nitrates  Directive  (91/676/EEC)  lays  down  minimum  provisions  on  manure  storage  in 
general with the aim of providing all waters with a general level of protection against pollution, 
and additional provisions on storage in designated Nitrate Vulnerable Zones. As a general rule, 
it  is  essential  to  take  national  and/or  regional  regulations  concerning  the  avoidance  of  water 
pollution  into  account  when  designing  and  locating  manure  stores.  Techniques  for  reducing 
emissions from manure storage are described in the sections below. 

4.11.1 

Reduction of emissions from storage of solid manure 

This section refers to techniques to reduce emissions to air, soil and water from the storage of 
solid  manure.  These  techniques  are  also  applied  to  the  solid  fraction  from  the  mechanical 
separation of slurry (see Section 4.12.2). 

4.11.1.1 

General practice for the batch storage of solid manure in the field 

Description  
The storage of solid manure after removal from livestock housing can be carried out in heaps (or 
stacks) in the field in separate batches before landspreading.  

In temporary heaps in the field, solid manure is stacked directly on the soil over a limited period of 
time prior to landspreading (e.g. for a few days or for several weeks, such as in the UK where 
storage  in  separate  batches  before  landspreading  lasts  for  at  least  90  days).  An  adequate 
separation distance  between  field  heaps  and surface and/or  underground  watercourses  such  as 
drains, boreholes, wells, surface waters and springs reduces the risk of any leachate from a heap 
running  over  the  soil  surface  directly  into  a  watercourse  or  flowing  through  the  soil  and 
transporting  nutrients,  faecal 
to 
watercourses.  

indicator  organisms  and  oxygen-depleting  pollutants 

Temporary  field  heaps  should  be  located  at  different  places  each  year;  this  procedure  is 
mandatory  in  some  Member  States,  e.g.  France.  Where  clay  soils  prevail  and  heaps  change 
location, no accumulation of harmful amounts of nutrients is expected and special measures do 
not  need  to  be  applied to  the  bottom  of  the  heap. To  prevent  water  from  entering  the  manure 
heap, the accumulation of rainwater at the base of the heap needs to be avoided.  

For field heaps that are made in the same place every year or for stockpiles located on soils with 
high  water  tables,  solid  impermeable  floors  are  applied  for  the  storage  of  solid  manure  to 
prevent water and soil pollution by leaching. Equipping the store with drains and/or applying a 
convenient  slope  on  the  floor  and  connecting  the  drains  with  a  closed  container  allow  the 
collection of liquid fractions and of any run-off caused by rainfall. For impermeable floors made 
of  concrete  with  leachate  collection  facilities,  further  information  is  presented  in  Section 
4.11.1.4. 

Storage areas away from sensitive receptors are preferred, and any advantage that can be taken 
of natural barriers, such as trees or height differences, should be exploited. Walls (wood, bricks 
or concrete) can also be erected to surround storage heaps. These can serve as windscreens, with 
the opening of the storage on the lee side of the prevailing wind direction. 

The smaller the ratio between the emitting surface area and the volume of the manure heap, the 
lower the ammonia and odour emissions. In order to reduce the manure surface exposed to air, 
manure can be compacted or a three-sided wall store can be constructed to increase the height.  

Intensive Rearing of Poultry or Pigs 

531 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Compacting solid manure when stored is a management option for reducing ammonia emissions 
to air. The high density achieved by compaction reduces the air transfer in the heap so that self-
heating (i.e. passive composting) can be avoided. A high density may be also a consequence of 
a  high  water  content  and  of  a  low  content  of  bedding  material  like  straw  or  wood  chips  
[ 441, Webb et al. 2011 ]. The air exchange in combination with the elevated heap temperature 
due to aerobic decomposition will promote losses of ammoniacal nitrogen [517, Petersen et al. 
2011 ]. 

Achieved environmental benefits  
Siting  temporary solid manure field heaps  as far as possible  from surface and/or underground 
watercourses reduces risks of pollution of soil and water by surface run-off. Benefits are likely 
to be greatest on medium/heavy soils where surface run-off risks are highest and field drains are 
likely to be present. The direct loss of pollutants in surface run-off and drain flow is prevented if 
the storage of solid manure takes place on an impermeable base with leachate collection. 

Microbial  pathogen  emissions  during  landspreading  are  reduced  compared  with  fresh  manure 
applications  (i.e.  immediately  after  removal  from  housing).  Reducing  the  ratio  between  the 
emitting surface area and the volume of the manure heap can reduce ammonia losses to air.  

Cross-media effects  
If the heaps are uncovered or not covered completely or compacted to reduce air transfer, then 
composting  (self-heating)  may  occur.  In  this  case,  ammonia  emissions  will  increase  with  the 
increasing heap temperature [ 590, Batfarm 2013 ] [ 441, Webb et al. 2012 ]. 

Nitrous oxide emissions may rise when increasing the manure density, due to the stimulation of 
nitrification and heterotrophic denitrification by an increased number and volume of sites with 
relatively low oxygen availability [ 517, Petersen et al. 2011 ] [ 441, Webb et al. 2012 ]. 

Environmental performance and operational data  
In  Finland,  the  heap  must  be  at  least  100  m  from  watercourses,  main  ditches,  or  from  a  well 
from which water is drawn for household use, and 5 m from (small) ditches [ 624, IRPP TWG 
2013  ].  In  the  UK,  the  applied  distances  are  10 m  from  watercourses  and  50 m  from  springs, 
wells,  boreholes  or  other  sources  of  water  intended  for  human  consumption  [  506,  TWG  ILF 
BREF  2001  ].  In  France,  the  minimum  distance  from  watercourses  is  reported  to  be  100  m 
[ 500, IRPP TWG 2011 ]. In Belgium (Wallonia), the dry farmyard manure has to be stored at 
least  20  m  from  any  drain,  well  or  surface  water.  In  Ireland,  the  national  legislation 
implementing  the  Nitrates  Directive  demands  the  heap  to  be  placed  within  250  m  of  an 
abstraction point, 50 m of any borehole, spring or well used for abstraction of water for human 
consumption, 20 m of a lake, 50 m of exposed cavernous or karst limestone features, 10 m of 
any surface water. In Italy, temporary manure storage is not permitted within a distance of 5 m 
from  drains,  30  m  from  river  sides,  and  40  m  from  the  bank  of  lakes,  as  well  as  from  the 
coastline [ 624, IRPP TWG 2013 ]. 

Additional  requirements  in  Member  States  for  temporary  field  heaps  are  presented  in 
Table 2.20. Microbial pathogen numbers decline during solid manure storage, with the rate of 
decline  accelerated  if  self-heating  (i.e.  passive  composting)  occurs  in  the  heap;  this  happens 
naturally in most FYM and poultry litter heaps. Hence, there are fewer microbial pathogens in 
the manure when it is spread and therefore less risk of microbial pathogens in surface run-off 
and  drain  flow.  Storage  is  effective  at  reducing  bacterial  numbers,  but  is  less  effective  at 
reducing populations of the protozoan parasite Cryptosporidium [ 648, DEFRA 2011 ]. 

The effect of temperature in solid manure heaps is significant and is related to the porosity, air 
permeability and water content of the heap because temperature is related to aerobic microbial 
activity. The heap temperature declines with an increasing heap density [ 590, Batfarm 2013 ].  

On  the  basis  of  experimental  data,  the  following  algorithms  have  been  proposed  to  calculate 
ammonia  emission  factors  in  relation  to  the  heap  density:  F(D)  =  6.5  -  7.6·D.  F(D)  is  an 

532 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

ammonia emission factor given as ln (% of TAN) in manure and D is the heap density in kg/m3. 
The  algorithm  reflects  that  the  NH3  emission  declines  exponentially  with  an  increasing  heap 
density [ 441, Webb et al. 2012 ].  

Technical considerations relevant to applicability  
The  storage  of  solid  manure  on  an  impermeable  base  equipped  with  a  drainage  system  and  a 
collection tank for the run-off is generally applicable. The storage of solid manure in field heaps 
placed  away  from  surface  and/or  underground  watercourses  is  only  applicable  to  temporary 
field heaps which change location each year. 

Economics 
Costs  based  on  the  construction  of  a  concrete  floor  and  leachate  collection  facilities  and  the 
associated  areas  for  vehicle  movements  (amortised  over  20  years)  in  the  UK  are  reported  as 
EUR 1.15/tonne of solid manure (EUR 1 = GBP 0.87).  

Driving force for implementation  
Where field heaps can be used for batch storage prior to landspreading, siting solid manure field 
heaps away from watercourses and field drains is simple to implement. 

Example plants  
The techniques for solid manure storage in heaps in the field are commonly applied.  

Reference literature 
[  441,  Webb  et  al.  2012  ]  [  500,  IRPP  TWG  2011  ]  [  506,  TWG  ILF  BREF  2001  ]  [  517, 
Petersen et al. 2011 ] [ 590, Batfarm 2013 ] [ 624, IRPP TWG 2013 ] [ 648, DEFRA 2011 ] 

4.11.1.2 

Application of a covering to solid manure heaps  

Description 
Covering materials are applied to solid manure heaps in the field or manure stores. These can be 
peat, sawdust, wood chips or a tight UV-stabilised plastic cover. The purpose of the cover is to 
provide a physical barrier reducing the release of ammonia from the manure heap to the air and 
preventing  the  run-off  of  rainwater.  Air  exchange  and  microbial  activity  (self-heating)  in  the 
manure heap decrease, resulting in a reduction of emissions to air. Covering the heaps tightly 
will most probably stop air from being exchanged between the heaps and surrounding air and 
NH3  emission  from  heaps  may  be  assumed  to  be  negligible  [  590,  Batfarm  2013  ]  
[  441,  Webb  et  al.  2012  ].  This  technique  mainly  applies  to  broiler  manure  and  dried  layer 
droppings but could be applied to all solid manures in outdoor stores. 

Manure heaps are often covered with 500–1 000 gauge plastic sheeting (1 gauge = 0.0254 mm) 
[  205,  ADAS  2000  ].  Geotextile  covers  let  gases  flow  from  the  mass  below  while  being 
waterproof but are relatively expensive. Other types of covers on the market are those used for 
silage and weaved covering [ 259, France 2010 ], or membrane-covered enclosed systems [ 624, 
IRPP TWG 2013 ]. 

If a cover is to be applied, heaps must be covered as soon as possible after they are made, since 
most  of  the  ammonia  evaporates  during  the  first  few  days.  Applying  the  covers  is  relatively 
easy, as no complex equipment or machinery is involved. Long, low field heaps would require 
large  amounts  of  sheeting  for  covering;  so  heaps  should  be  shaped  to  minimise  their  overall 
surface area [ 648, DEFRA 2011 ]. 

The principle behind the application of peat was reported by Finland [ 26, Finland 2001 ]. The 
use of peat (as a 10 cm layer) is based on its ability to bind cations. Ammonia is absorbed into 
the peat in a chemical reaction in which the NH3 molecule is transformed into a fixed NH4 ion. 
The higher the acidity of the peat, the more ammonia it can absorb. The peat-littered manure of 

Intensive Rearing of Poultry or Pigs 

533 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

broilers is very suitable for depositing in heaps on the field, because liquid does not seep from it 
and nearly all rainwater is absorbed in the heap. Peat used as litter absorbs ammonia effectively. 

Achieved environmental benefits 
Benefits 
prevention/reduction of leaching due to rainwater.  

include 

the  reduction  of  ammonia  and  odour  emissions,  as  well  as 

the 

Cross-media effects 
Peat is a non-renewable resource whose extraction is associated with high CO2 emissions; the 
environmental benefit of its use for manure heaps is debated [ 506, TWG ILF BREF 2001 ].  

Environmental performance and operational data 
Ammonia emissions from covered heaps of solid manure are estimated to be reduced by up to 
50 % compared to uncovered heaps [ 227, Denmark 2010 ].  

In the UK, experimental studies have shown a wide range of reduction efficiencies by covering 
solid manure heaps with an impermeable sheet (from 14 % to 89 %), with an average ammonia 
emissions  reduction  value  of  65 %.  The  reported  values  are  associated  with  conditions  where 
the manure heap is created, sheeted and left undisturbed. This condition might apply to broiler 
farms, where the sheds are cleared and the manure is stored and left undisturbed until the end of 
the next crop cycle, or to laying hen farms where manure from deep pit housing is cleared from 
the shed and stored. Where frequent additions to the heap are performed, for instance at farms 
with a weekly manure removal by belts, and the sheeting has to be removed and replaced, the 
evidence suggests that there is no significant reduction of ammonia  emissions when compared 
to  a  conventional  manure  heap  without  a  cover.  The  same  effect  is  also  reported  where 
polyethylene covers were damaged by high winds and, even though they were replaced within 
24 hours, there was no difference in ammonia losses from covered and uncovered stores. These 
cases should therefore be treated as an uncovered store [ 500, IRPP TWG 2011 ]. 

Comparing  different  types  of  poultry  manure,  experiment  results  showed  that  ammonia 
emissions were highest during the first 100 days of storage (uncovered or covered), while the 
heap covers reduced ammonia emissions by 33 % for broiler litter, 52 % for laying hen manure 
from  a  deep  pit,  and  74 %  for  laying  hen  manure  removed  by  belts.  These  differences  in 
ammonia  emissions  reduction  reflect  the  higher  available  ammoniacal  nitrogen  content  and 
higher temperatures measured during storage of the broiler litter and laying hen manure from a 
deep  pit,  compared  with  the  laying  hen  manure  removed  by  belts,  which  favour  ammonia 
volatilisation during the early storage period [ 205, ADAS 2000 ]. 

Data  concerning  ammonia  emissions  from  covered  and  uncovered  poultry  manure  heaps  are 
reported in Table 4.156. 

Table 4.156:  Ammonia emissions from covered and uncovered poultry manure heaps  

Parameters 

Broiler litter 

Manure from 
laying hens, with 
a deep pit 

Manure from 
laying hens, with 
removal belts 

Ammonia emissions  
(g NH3/m2 ground surface area) 

Losses during first 100 
days of storage  

Total losses for a 350-
day storage period (2) 

Uncovered 
Covered (1) 
Reduction 
Uncovered 
Covered (1) 
Reduction 

(1) Covered with 1 000 gauge polythene sheeting. 
(2) Including emissions from heap disturbance. 
Source: [ 205, ADAS 2000 ] 

169 
113 
33 % 
271 
245 
10 % 

110 
53 
52 % 
192 
156 
19 % 

116 
30 
74 % 
159 
56 
65 % 

534 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Data  concerning  nitrogen  losses  as  a  percentage  of  the  total  nitrogen  content  in  solid  manure 
(ex-housing),  stored  for  more  than  100  days,  with  or  without  a  cover,  are  presented  in 
Table 4.157.  Values  reported  are  the  result  of  large-scale  field  experiments  carried  out  under 
different climatic conditions in northern Europe. 

Chapter 4 

Table 4.157:  Nitrogen losses from covered and uncovered solid manure heaps  

Manure type 

Type of storage 

N-NH3 

Pigs (FYM or litter) 

Laying hens (FYM or litter) 

Broilers, ducks and turkeys (litter) 

(1) Estimated values. 
Source: [ 442, Hansen et al. 2008 ] 

Uncovered 
Covered 
Uncovered 
Covered 
Uncovered 
Covered 

25 
13 
10 
5 
15 
8 

Nitrogen losses 
(% of total N (ex-housing)) 
N denitrification 
(1) 
15 
15 
10 
10 
10 
10 

Total N 
losses  
40 
28 
20 
15 
25 
18 

Covers also reduce leachate, in volume and content (N, P, K) [ 205, ADAS 2000 ]. Total N and 
NH4-N leachate losses were equivalent to about 0.5 % and 0.25 % of total N and NH4-N inputs 
to the uncovered heaps, and were less than 0.1 % of total N and NH4-N inputs to the covered 
heaps, respectively. Total P and K losses were equivalent to 0.2–0.3 % and 2–3 % of total P and 
K  inputs  to  the  poultry  manure  heaps.  At  the  same  time,  the  covers  were  very  effective  in 
reducing leachate production, as the mean volume of leachate from the covered heaps was 85 % 
lower than from the uncovered heaps. No significant effect of heap covering on ammonia losses 
during landspreading was reported [ 205, ADAS 2000 ].  

The  results  of  a  Danish  study  show  that  the  application  of  an  airtight  cover  to  prevent 
composting during the storage of slurry fibre fractions results in a reduction of NH3, N2O, and 
CH4 emissions by 12 %, 99 % and 88 %, respectively. During a 120-day storage period without 
a cover, 4.8 % of the total nitrogen was lost as N2O, while only 0.04 % was lost when using a 
cover.  Nitrification  activity  is  a  precondition  for  N2O  emissions,  which  may  explain  the 
mitigation potential of an airtight cover [ 526, Hansen et al. 2006 ]. 

Nitrous oxide emissions from broiler litter  were found to  range from 0.55 %  to 0.70 % of the 
total  N  of  the  manure  stored  in  a  sheeted  heap,  while,  for  the  conventionally  stored  litter 
(uncovered), the values ranged from 0.17 % to 0.81 % [250, IGER 2004 ]. The effects on the 
balance of N2O emissions at the farm scale are uncertain [ 648, DEFRA 2011 ].  

Dry peat and sawdust absorb rainwater. Straw is not a good covering material because it does 
not  absorb  ammonia  and  it  also  prevents  a  natural  crust  from  forming  on  the  surface  of  the 
manure.  A  crust  prevents  the  volatilisation  of  ammonia  from  the  fresh  surface  of  the  manure 
under  it  better  than  a  covering  of  straw  does.  It  is  clear  that  tight  covers  can  be  reused  if 
properly applied, whereas other covering materials will need to be purchased for each new heap. 
These other covering materials, such as peat, will be incorporated and then treated (applied) as 
part of the manure. Peat will not create a hazard for grazing animals.  

Technical considerations relevant to applicability 
The  technique  is  generally  applicable  when  solid  manure  is  dried  or  pre-dried  in  animal 
housing.  A  sheet  covering  may  not  be  appropriate  for  undried  solid  manure  management 
systems that involve the regular additions of material to existing manure heaps (e.g. daily, twice 
weekly), as there would be a continual need for sheet removal and replacement.  

Intensive Rearing of Poultry or Pigs 

535 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
Reported costs of covers (tax included) from France are EUR 1.45–2.45/m2 for geotextile cover, 
EUR 0.95–1.10/m2 for weaved cover, and EUR 0.17–0.24/m2 for cover for silage [ 259, France 
2010 ].  

In the UK, costs for the provision of sheeting are estimated as EUR 0.57/tonne of solid manure 
(EUR 1 = GBP 0.87) [ 648, DEFRA 2011 ]. Calculations have shown that the covering of solid 
manure heaps is economically profitable, as the cost of the covering material is lower than the 
value  of  the  amount  of  nitrogen  retained  in  the  manure  [  499,  AgroTech  2008  ].  Investment 
costs, related to a farm producing 17 500 fattening pigs per year, may reach EUR 5 per animal 
place, depending on the type of cover (ranging from a simple shelter cover to a closed manure 
shed). 

Driving force for implementation 
Covering  manure  stores  (or  heaps)  reduces  the  total  ammonia  emissions  of  the  production 
process,  albeit  by  a  smaller  proportion  compared  to  emissions  from  housing  and/or  manure 
landspreading  which  are  much  more  significant;  however,  it  is one  of  the  easiest  measures  to 
monitor and control. Indeed, covers are important where stores are sited near residential areas or 
other sensitive receptors [ 337, Webb et al. 2005 ]. 

This  technique  is  a  less  expensive  alternative  to  silos,  to  enable  on-field  storage  to  protect 
ground  or  surface  water  from  nutrient  run-off  or  leaching.  Sheeting  may  have  the  additional 
benefit of minimising contamination by flies. 

Example plants 
In  France,  the  application  of  a  covering  to  solid  manure  heaps  is  an  obligation  for  poultry 
manure only. In the Netherlands, covering is mandatory for manure heaps situated in the field 
for more than  2 weeks. In  the  UK, it is mandatory to cover field heaps of  laying hen  manure 
with an impermeable sheet in NVZs.  In the Netherlands and the UK, covers are used on solid 
manure heaps to prevent odour when there are homes near the heaps [ 641, IRPP IWG 2014 ]. 
In  Denmark,  covered  storage  of  the solid  fraction  from  the  mechanical separation  of  slurry  is 
mandatory. 

Reference literature 
[  26,  Finland  2001 ]  [  205,  ADAS  2000  ]  [  227,  Denmark  2010  ]  [  250,  IGER  2004  ]  [  259, 
France 2010 ] [ 337, Webb et al. 2005 ] [ 441, Webb et al. 2012 ] [ 442, Hansen et al. 2008 ] 
[ 499, AgroTech 2008 ] [ 500, IRPP TWG 2011 ] [ 526, Hansen et al. 2006 ] [ 506, TWG ILF 
BREF 2001 ] [ 590, Batfarm 2013 ] [ 624, IRPP TWG 2013 ] [ 641, IRPP IWG 2014 ] [ 648, 
DEFRA 2011 ]  

4.11.1.3 

Storage of dried solid manure in a barn 

Description 
Dried solid manure is normally stored in a barn. It is removed from the animal housing by front-
end  loaders  or  by  means  of  a  belt,  and  transported  to  the  shed,  where  it  can  be  stored  for  a 
longer  period  of  time  without  the  risk  of  remoistening.  The  barn  is  usually  a  simple, 
straightforward closed construction with an impermeable floor and a roof. It is equipped with 
sufficient  ventilation  openings  to  avoid  anaerobic  conditions  and  condensation,  and  an  access 
door for transport. 

To keep emission of gaseous compounds low, the relatively high dry matter percentage of solid 
manure has to be maintained, e.g. remoistening of the droppings should be prevented as this will 
lead to a release of odorants. This is helped by keeping solid manure protected against outdoor 
influences such as rain and sunlight. Droppings storage sheds should not be built so high as to 
allow self-heating to occur in the stored droppings.  

536 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
Drying manure in the housing reduces the emissions to air of gaseous compounds (ammonia).  

Cross-media effects 
Odour  levels  may  be  kept  low,  but  aerobic and  anaerobic  conditions  can  affect this.  If  a  new 
barn is planned, it is a potential source of odour, so thought should be given to its location with 
respect  to  sensitive  receptors  in  the  vicinity  of  the  farm.  It  is  important  to  have  sufficient 
ventilation to avoid anaerobic conditions. A monitor of the internal temperature of the manure 
pile is necessary, to prevent litter overheating and spontaneous autoignition (combustion). 

Environmental performance and operational data 
The manure is protected against the outdoor climate by the barn construction. 

Technical considerations relevant to applicability 
If sufficient space is available in the farmyard there are no limits to the construction of a new 
barn for the storage of solid manure. Existing barns may be used, but attention must be paid to 
the impermeability of the floor. 

Economics 
Costs are for the construction and maintenance of a barn. For an existing barn, renovation of the 
flooring may be needed. 

Driving force for implementation 
In cases where poultry manure is already dry (e.g. litter from broilers and laying hens, air-dried 
laying  hen  excreta  collected  on  manure  belts),  a  barn  with  an  impermeable  floor  and  sufficient 
ventilation will keep the manure dry and prevent remoistening, compared with any further long-
term storage elsewhere [ 508, TFRN 2014 ]. With permanent storage structures, field heaps and, 
consequently, the associated pollution risks are also avoided or reduced. 

Example plants 
The storage of poultry manure in barns is applied in nearly all Member States. 

Reference literature 
[ 24, LNV 1994 ] [ 26, Finland 2001 ] [ 508, TFRN 2014 ] 

4.11.1.4 

Concrete silo for solid manure storage 

Description 
This  is  a  three-sided,  rectangular  or  square  structure  with  a  concrete  floor.  The  floor  slopes 
towards the open side (e.g. gradient of 2 %) where a gutter collects seepage/drainage from the 
stacked  manure  that  is  stored  separately  in  a  concrete  leak-tight  pit  underneath  the  storage 
platform. Elevated edges, supporting side walls or other constructional means, e.g. a perimeter 
channel, are necessary to make sure that liquid fractions can flow into the storage pit underneath 
and  to  prevent  run-off  from  surrounding  areas  from  entering  the  platform.  Roofing  over  the 
storage  platform  helps  to  decrease  the  volume  requirement  of  the  storage  pit.  The  reinforced 
concrete side walls allow manure stacking in a space-efficient way. 

Achieved environmental benefits 
Benefits  include  improved  protection  of  the  soil,  surface  and  groundwater,  by  a  complete 
control of leakages. 

Cross-media effects 
The liquid fraction collected in the pit has to be managed. It can be spread at a later date when 
soil conditions are suitable and the nutrients can be utilised by crops, or it may be readded to the 
heap or to a slurry store. In the case of pig manure storage, it is treated as slurry.  

Intensive Rearing of Poultry or Pigs 

537 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
In  addition  to  proper  planning  and  construction,  in  accordance  with  the  relevant  regulations, 
water protection is ensured by careful operation and, particularly, by proper maintenance of the 
facility. In Germany, the facility operator is required to run regular checks of the leakproofness 
of  containers,  pipes,  etc.  Leak  testing  (e.g.  pressure  tests)  of  underground  pipes  should  be 
repeated approximately every 10–12 years. In areas with water protection legislation in place or 
in special cases, shorter testing intervals are required following the instructions of the competent 
authorities.  Stores  with  an  area  of  up  to  2 000  m2  can  be  built  with  manure  stacked  up  to 
5 metres high. 

In  order  to  store  broiler  manure  for  4  months,  from  a  building  of  1 000 m2  (150 tonnes  of 
manure/year), a surface of between 48 m2 and 80 m2 is needed, depending on the height of the 
side  walls  and  their  number  (three  or  four).  A  pig  house  of  550  places  for  fattening  pigs, 
producing  1 tonne  of  manure/place  per  year  (460 kg/m3  approximately),  will  need  a  400 m2 
concrete  platform  with  three  walls  of  1 metre  high  to  store  the  manure  for  4 months  
[ 259, France 2010 ]. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
From Germany, the investment  costs  are reported to be in the range of EUR 65–77 per m3 of 
manure storage capacity, including the storage pit for drainage collection. The total annual costs 
are  between  EUR 5.8  and  EUR 6.8  per  m3  of  storage  capacity.  Cost  data  related  to  the 
construction of a silo for the storage of solid pig manure are presented in Table 4.158. 

Table 4.158:  Cost data of a silo for the storage of solid pig manure 

Parameters 
Silo characteristics 
Storage capacity 
Surface area 
Height of side walls 
Durability 
      Manure density 
Cost data 

Investment costs 

Total costs  

Source [ 212, Germany 2010 ] 

Value 

1 100 m3 
520 m2 
2 m 
30 years 
0.8–0.9 t/m3 

Remarks 

For 2 000 pig places 

EUR 73/m3 
(EUR 65–77/m3) 

EUR 6.4/m3/yr 
(EUR 5.8–6.8/m3/yr) 

Additional pit with a volume of 1 000 m3 
for urine and seepage is included 
(EUR 3/m3) 
Including additional costs for a liquid 
manure pit for seepage/drainage 
collection (EUR 0.27/m3/yr) 

Driving force for implementation 
This technique is used to efficiently store solid manure in cases when a storage capacity  over 
several months is legally required. Other driving forces are:  

 

 

manure management is easier and the volume of manure to be transported is reduced;  

the use of field heaps and associated pollution risks are also avoided or reduced.  

Example plants 
This technique is reportedly in use in Belgium (Flanders), Germany and in the UK. 

Reference literature 
[ 212, Germany 2010 ] [ 259, France 2010 ] [ 648, DEFRA 2011 ] 

538 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.11.2 

Reduction of emissions from the storage of slurry 

4.11.2.1 

General aspects  

It  is  common  practice  for  farmers  to  have  storage  facilities  for  pig  slurry  with  a  sufficient 
capacity  to  hold  the  slurry  until  further  treatment  or  application  is  carried  out  (see  also 
Section 2.6). The required capacity depends on the climate, and the duration of the periods in 
which landspreading is not possible. For example, the capacity can differ from the manure that 
is produced on a farm over a 4- to 5-month period in a Mediterranean climate to that produced 
over  a  7- to 8-month  period  in  Atlantic  or  continental  conditions,  and  again  to  that  produced 
over a 9- to 12-month period in boreal areas [ 537, COM 1999 ]. Specific examples, concerning 
procedures applied in different Member States, are presented in Table 2.15. 

Not only should the store be of a sufficient size to avoid landspreading at times of the year when 
there is a risk of emission to water (e.g. through nitrate leaching) but it should also be adapted to 
allow  landspreading  at  the  ideal time  with  regard  to the  nitrogen  demand  of  the  crops.  Slurry 
stores  can  be  constructed  in  such  a  way  that  the  risk  of  leakage  of  the  liquid  fraction  can  be 
minimised (see also Section 2.6.5.1 and Section 4.11.2.6). They are built using the appropriate 
concrete  mixtures,  and,  in  many  cases,  a  lining  is  applied  to  the  concrete  tank  wall  or  an 
impermeable layer to steel sheets. Bags, lined or unlined earth-banked lagoons, or GRP tanks 
are also used. 

Ammonia emissions from liquid manure (slurry) mainly depend on the chemistry of the liquid 
ammonia  dissolved  in  the  transfer  mechanism  of  gaseous  ammonia  at  the  manure  surface. 
Various  parameters  have  an  influence  on  ammonia  emissions  from  manure  storage,  among 
them: manure surface area, temperature, and wind speed [ 439, Sommer et al. 2006 ].  

Emissions to air during the storage period can be reduced by applying the measures given below 
related to the design and management of the slurry store: 

 

 

 

Reducing the emitting surface area/volume (i.e. capacity) (SA/V) ratio of the storage. For 
example, the surface area of a 1 000 m3 slurry store can be reduced by 40 % if the height 
of the container is increased by 2 m, from 3 m to 5 m. The container then has a diameter 
of 16 m instead of 20.6 m. In order to enable mixing in circular stores, the height of the 
store should be at least one fourth to one third of its diameter [ 337, Webb et al. 2005 ]. 
For rectangular stores, the proportion of height to surface area should be 1: 30–50. On the 
other  hand,  an  excessive  height  of  the  slurry  store  above  the  soil  surface  represents  an 
added safety risk. Other cross-media effects are the higher consumption of energy due to 
increased  pumping  requirements,  potential  problems  in  the  gravity  flow  of  slurry  from 
houses to the tank, construction costs for increased tank heights, and visual effects on the 
landscape  [  624,  IRPP  TWG  2013  ].  For  uncovered  tanks,  the  height  of  the  store  is 
recommended to be at least 3 m [ 508, TFRN 2014 ]. This technique may not be generally 
applicable to existing tanks. 

Operating a lower level of fill in uncovered stores to take advantage of the wind shielding 
effect  created  by  the  freeboard.  As  a  result  the  wind  velocity  and  air  exchange  on  the 
slurry surface are reduced.  When dimensioning the store, annual precipitation has to be 
taken  into  account  in  order  to  maintain  a  sufficiently  high  freeboard  for  safety  
[  624,  IRPP  TWG  2013 ].  This  technique  may  not  be  generally  applicable  to  existing 
tanks. 

Emptying  the  stores  in  spring,  before  the  onset  of  the  warm  season,  so  that  the  lowest 
possible slurry quantity is stored during summer. The stored slurry temperature in above-
ground tanks follows the air temperature, and at higher temperatures gaseous emissions 
will increase. This procedure applies for above-ground tanks in regions where there is a 
significant temperature rise in the summer. The temperature of the slurry in underground 
storage tanks warms up at a slower rate. 

Intensive Rearing of Poultry or Pigs 

539 

 
 
 
 
 
 
Chapter 4 

 

 

 

Frequently  transferring  slurry  from  a  housing  facility  to  an  outdoor  store.  Since  the 
temperature  of  the  slurry  tends  to  match  the  ambient  temperature,  this  technique 
represents a relevant ammonia mitigation option in cool and temperate regions, whereas 
in  warmer  climates  the  effect  may  be  limited  or  even  negative  [  517,  Petersen  et  al. 
2011 ].  

Performing the discharge of liquid manure in open storage containers as close to the base 
of such containers as possible (infilling below the liquid surface level) without impairing 
the  emission  control  effect  of  the  crust  or  cover.  Unnecessary  homogenisation  and 
circulation  pumping  of  slurry  should  be  avoided  and  should  preferably  be  performed 
when the wind is blowing away from any sensitive sites requiring protection. 

Reducing the NH3 volatilisation from the slurry surface. A low volatilisation rate can be 
maintained if the stirring of slurry is kept to a minimum and is done only before emptying 
the slurry tank for the homogenisation of the suspended matter. 

Apart  from  the  above  general  measures,  the  main  abatement  technique  to  reduce  ammonia 
losses  and  odour  emissions  from  slurry  stores  consists  of  covering  open  stores,  therefore 
increasing  the  transport  resistance  from  the  manure  surface  (source  of  emission)  to  the 
atmosphere.  A  distinction  is  made  between  covers,  as  various  types  of  covers  can  be applied. 
The  main  types  are  rigid  covers,  tent  covers,  floating  covers,  or  a  floating  layer  of  straw  or 
natural crust. 

In  particular,  covers  in  the  form  of  roofs  of  PVC,  wood  or  similar  materials  that  create  an 
impermeable  lid  over  the  storage  will  reduce  emissions.  Porous  floating  surface  material  has 
also  been  shown  to  reduce  NH3  emissions,  because  it  creates  a  stagnant  air  layer  above  the 
slurry, through which NH3 has to be transported by the slow process of diffusion. This material 
may be porous textiles, a natural surface crust formed by solids floating on the surface, a cover 
of straw, peat or floating expanded clay particles. The lowest reductions occur when the surface 
is  covered  by  a  natural  crust,  the  air  temperature  is  low  or  the  cover  on  the  treated  slurry  is 
submerged. At low air temperatures, NH3 emissions from stored uncovered slurry are low and 
emissions  from  covered  storage  are  therefore  not  much  lower  than  those  from  the  reference 
system [ 590, Batfarm 2013 ]. 

An  overview  of  the  different  types  of  covers  applied  in  slurry  storage  is  presented  in 
Table 4.159,  with  an  indication  of  their  applicability  to  round  containers  and  earth-banked 
lagoons. 

540 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Table 4.159:  Overview of the different types of covers applied in slurry storage  

Chapter 4 

General 
category 

Rigid covers 

Flexible 
covers 

Floating 
covers 

Type of cover 

Concrete covers 
Fibreglass panels 
Tent cover, dome-shaped or 
tended flat 
Floating sheeting covers 
Air-inflated covers 
Natural crust 
Straw (crust) 
Peat 
Light bulk material (e.g. LECA, 
perlite, zeolite) 
Plastic pellets (polystyrene balls)  
Rapeseed oil 
Plastic blankets and foil 
Geometrical plastic tiles  

NB: NA = not applicable; NI = no information provided. 

Applicability 

Round container 
(concrete or steel) 
X 
X 

Earth-banked 
lagoon 
NA 
NA 

X 

X 
X 
X 
X 
X 

X 

X 
X 
X 
X 

NA 

X 
X 
X 
X 
X 

X 

NI 
NI 
X 
X 

Care  must  be  taken  to  prevent  the  temperature  of  the  slurry  from  rising  to  a  point  at  which 
biochemical  reactions  can  occur,  otherwise  these  may  result  in  unwanted  odorant  production 
and a degradation of the quality of the slurry [ 443, Chadwick et al. 2011 ]. 

Covering reduces or eliminates the oxygen exchange between manure and air and results in an 
increase of temperature of the slurry by approximately 2 °C.  Under these conditions, methane 
can be formed; its recovery and use for energy production is possible but involves an extra cost 
[ 259, France 2010 ]. Generally, the covering of slurry stores is an effective means of reducing 
ammonia  emissions,  but  may  pose  problems  in  application,  operation  and  safety.  The  lack  of 
oxygen  reduces  nitrification  and  (consequently)  denitrification,  and  hence  nitrous  oxide 
emissions could be significantly reduced or prevented. With some covers, e.g. LECA, oxygen 
can  still  enter  the  slurry,  which  means  that  (de-)nitrification  processes  can  occur  and  hence 
emissions of nitrous oxide are likely to increase.  

Closed  impermeable  covers  prevent  rainfall  diluting  the  slurry,  so  that  a  reduced  volume  of 
slurry  is  achieved  and  an  increased  effective  storage  period  is  provided  by  the  store.  In  areas 
with moderate to high rainfall, these types of cover can be cost-effective, limiting transportation 
and spreading costs [ 525, BPEX 2011 ] [ 259, France 2010 ].  

In  the  UK,  for  pig  slurries  with  a  very  low  dry  matter  content  of  less  than  1 %  produced  by 
diluting slurry with washing water or contaminated rainwater run-off, the store may not need to 
be  covered.  The  criterion  for  this  to  be  acceptable is  a  regular  control  of  the  slurry  store  to 
confirm that the DM remains annually below 1 % [ 524, UK EA 2012 ].  

Ammonia  emissions  from  storage  over  6  to  12  months  have  been  measured  or  estimated  in 
Denmark and are shown in Table 4.160. 

Intensive Rearing of Poultry or Pigs 

541 

 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.160:  Ammonia emissions as a percentage of the total stored nitrogen in slurry containers in 

Denmark 

Type of cover 

Emission (%  
of total N) (ex-housing) 

Untreated slurry 
Uncovered  
Natural organic cover  
Floating fabric cover  
Tent  
Concrete cover  

Digested slurry 
Uncovered  
Covered (chopped straw, plastic, natural crust, etc.)  
Tent or concrete cover  

(1) Estimation. 
Source: [ 210, Denmark 2010 ] [ 442, Hansen et al. 2008 ] 

9.0 
2.0 
1.5 
1.0 (1) 
1.0 

21 
4 
2.0 

Slurry bags are large prefabricated bags made from reinforced fabric bags coated with PVC or 
polyester  sitting  within  an  earth  structure,  for  storing  slurry  or  liquid  manure.  They  are 
restrained  at  the  sides,  fitted  with  gas  vents  to  prevent  the  build-up  of  gases,  and  the  cover 
provides part of the structural integrity of the store [ 525, BPEX 2011 ]. They are an alternative 
to  steel  or  concrete  stores  and  can  provide  long-term  storage  and  make  a  cost-effective 
alternative.  This  technique  is  mainly  suitable for  small  farms  (e.g.  < 150  fattening  pigs). 
Available  bag  sizes  may  limit  the  use  on  larger livestock  farms. The  cost  of  this  technique  is 
reported to be EUR 2.5/m3 per year including both the storage structure and the cover. Ammonia 
emissions reduction is reported as almost 100 % [ 508, TFRN 2014 ].  

4.11.2.2 

Application of a rigid cover to slurry stores  

Description 
Rigid covers are tight covers (e.g. a roof or a lid) which are made from inflexible material such 
as  concrete,  fibreglass  panels  or  polyester  sheets  with  a  flat  deck  or  conical  shape  (see 
Figure 4.77). They should be well sealed or 'tight', in order to minimise air exchange, but fitted 
with  gas  vents  to  prevent  the  accumulation  of  flammable  gases.  They  fully  cover  the  slurry 
surface,  preventing  rain  and  snow  from  entering,  and  so  enable  a  more  predictable storage 
capacity.  Covering  small  slurry  stores  is  in  general more  straightforward  than covering  larger 
ones.  If  the  cover  is  made  of  a  lighter  material,  then  the  span  can  be  larger  than  for  concrete 
covers exceeding 25 m and with a central support. 

542 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

Source: [ 204, IMPEL 2009 ] 

Figure 4.77:  Rigid cover for slurry storage, with conical shape  

Achieved environmental benefits 
The covering of store surfaces is known to significantly reduce odour and ammonia emissions.  

Cross-media effects 
Accumulation  of  toxic  (e.g.  H2S)  or  explosive  (methane)  gases  may  occur  which  must  be 
considered  for  safety  reasons.  Some  small  openings  (which  do  not  undermine  the  minimum 
sealing required), or a facility for venting, are needed to prevent the build-up of such gases.  

Environmental performance and operational data 
A concrete cover allows the achievement of ammonia emission reductions of 90 % [ 575, UBA 
Germany 2011 ]. Purpose-built (rigid) covers are reported to give reductions of at least 80–90 % 
for  ammonia  and  odour  emissions  associated  with  manure  storage.  Generally,  NH3  emission 
levels from slurry storage under warm climates are higher than under cold climates; therefore, 
the  reduction  efficiency  of  covering  slurry  stores  is  expected  to  be  higher  in  warm  climates 
when it is expressed in relation to an uncovered store. 

Gaseous  emissions  were  measured  during  field  experiments,  for  the  relatively  warm  and  cold 
climates related to Austria. The experiment concerned the storage of slurry produced by a straw 
flow system, with the use of a solid cover in underground pilot stores, compared with uncovered 
stores. The observation periods were 50 days and 200 days of storage in warm conditions and 
50  days  of  storage  in  cold  conditions.  A  summary  of  the  results  is  given  in  Table 4.161. 
Ammonia  and  methane  emissions  are  reduced  in  both  climatic  conditions.  The  rigid  cover 
seems to only have a positive effect on nitrous oxide emissions in cold conditions.  

Intensive Rearing of Poultry or Pigs 

543 

 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.161:  Reduction of gaseous emissions from the storage of slurry with the use of a rigid cover 

in underground pilot stores, compared to uncovered stores 

Reduction (%) 

Parameter 

Warm conditions (1) (2) 
28–44 

Cold conditions (1) (3) 
15 

Ammonia (NH3) 
Methane (CH4) 
Nitrous oxide (N2O) 
(1) The results for warm conditions have been tested for 50 and 200 days of storage. For cold 

32–70 
-4 (4)–30 

38 

50 

conditions, the observation period was equivalent to 50 days of storage. 

(2) Average slurry temperature 17 °C (from 13.6 °C to 21.9 °C). 
(3) Average slurry temperature 12 °C (from 8.1 °C to 16.6 °C).  
(4) Increase of 4 %.  
Source: [ 519, Amon et al. 2007 ] 

Technical considerations relevant to applicability 
Rigid  covers  are  usually  installed  at  the  same  time  as  the  store.  A  fixed  cover  may  not  be 
suitable for retrofitting  in existing  tanks,  as it  requires  the  store  to  be structurally  suitable and 
may  involve  additional  reinforcement  to  withstand  the  extra  load  [  525,  BPEX  2011  ]  
[  508, TFRN  2014 ].  For technical reasons,  rigid  covers  cannot  fit  widely  dimensioned earth-
banked lagoons and geomembrane-lined stores, such as the typical French slurry stores used for 
duck manure [ 259, France 2010 ]. 

Economics 
Retrofitting  a  cover  to  an  existing  store  is  reported  to  be  expensive.  In  the  UK,  the  cost  of  a 
covered store is 50 % more expensive than the cost of an uncovered one [ 175, Ecodyn 2010 ]. 
Costs for rigid covers are reported from France and presented in Table 4.162.  

Table 4.162:  Costs for rigid polyester covers reported from France 

Type of cover 

EUR/t pig produced (1) 

EUR/m3 slurry/year (2) 

Investment cost 

10 

Rigid  resin  polyester  cover 
without central post (3) 
Polyester  cover  with  central 
post (4) 
(1) Farm with 550 fattening pig places. 
(2) Farm of 1 000 m2, for duck rearing. 
(3) Tax excluded, on-farm installation included. 
(4) Tax and on-farm installation excluded. 
NB: Costs calculated for a depreciation period of 20 years (without interest charges and subsidies). 
Source: [ 259, France 2010 ] 

0.8–1 

5 

- 

From Germany, cost data associated with various types of covers, applied for slurry storage, are 
reported,  expressed  per  m3  of  slurry  stored,  per  m2  of  surface  or  per  kg  of  NH3  abated.  
[  575,  UBA  Germany  2011  ].  Comparisons  of  costs  for  rigid,  flexible  and  floating  covers 
applied  to  round  slurry  tanks  of  different  capacities  are  presented  in  Table 4.163.  Emission 
reduction  costs  for  the  different  types  of  covers  are  given  in  Table 4.164,  together  with 
mitigation costs, which take into account the fertiliser value (conserved nitrogen) and the costs 
associated with the extra volume of water from precipitation that would have to be landspread, 
and the tank freeboard needed to contain precipitation water. 

544 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 4.163:  Cost data for different covers of slurry tanks, in Germany 

Usable 
storage 
capacity  
Diameter 

Type of 
cover 

Dimensions (1) 

1 000 m3 

3 000 m3 

500 m3 

13.7 m 

Investment 
costs 

27.9 m 

17.7 m 
Investment and annual costs (2) 
Annual 
storage 
costs 
(EUR/m3/yr) 

Annual 
storage  
costs 
(EUR/m3/yr) 

(EUR/m2) 

Annual 
storage costs 
(EUR/m3/yr) 

Chapter 4 

5 000 m3 

35.5 m 

Annual 
storage costs 
(EUR/m3/yr) 

Investment 
costs 

(EUR/m2) 

NI 

NR 

NR 

100 

1.96 

1.29 

2.38 

1.57 

1.17 

2.74 

3.67 

1.78 

Uncovered 
(reference) 
Concrete 
cover 
Tent cover  
Floating 
flexible 
cover  
Light bulk 
materials  
Geometrical 
plastic tiles 
Straw (3) 
NR  
(1) A residual volume of 0.5 m (depth) and a freeboard of 0.2 m have been considered.  
(2) For the cost calculation, a storage duration of 6 months was assumed; the expenses presented are based on an annual 

1.35 

2.03 

2.42 

1.82 

1.74 

1.47 

1.86 

2.74 

2.14 

1.73 

2.11 

1.49 

10.2 

39.5 

2.00 

1.66 

1.43 

1.73 

39.5 

NR 

NI  

2.2 

2.7 

1.3 

7.6 

1.6 

34 

46 

16 

slurry quantity which is twice as large as the usable capacity.  

(3) Costs are based on two coverings per year. Additional operating costs depend on the thickness of the layer.  
NB: NI = no information provided; NR = not relevant. 

Source: [ 575, UBA Germany 2011 ] 

Table 4.164:  Ammonia emissions mitigation costs for different covers of slurry tanks, in Germany 

Usable storage 
capacity  

Type of cover 
Concrete 
cover 

Tent cover  

Floating 
flexible cover  
Light bulk 
materials  
Geometrical 
plastic tiles 
Straw 

(1) 

(1) 

(1) 

(1) 

(1) 

500 m3 

Storage capacity 
1 000 m3 

3 000 m3 

5 000 m3 

Emission reduction and mitigation costs 
EUR/kg NH3 
1.25 
(0.45) 
1.81 
(1.01) 
0.94 
(1.29) 
0.28 
(0.09) 
0.88 
(0.67) 
0.53 

EUR/kg NH3 
1.25 
(0.44) 
2.45 
(1.64) 
1.27 
(1.07) 
0.36 
(0.17) 
0.88 
(0.67) 
0.63 

EUR/kg NH3 
1.25 
(0.47) 
1.33 
(0.55) 
0.73 
(0.52) 
0.28 
(0.09) 
0.88 
(0.67) 
0.43 

EUR/kg NH3 
NI 
NI 
1.09 
(0.32) 
0.60 
(0.40) 
0.27 
(0.08) 
0.88 
(0.67) 
0.41 

(1) 

2 times per 
year (2) 
4 times per 
year (2) 
(1) Cost data take into account the value of conserved nitrogen, the expenses for landspreading of precipitation 

(0.36) 

(0.94) 

(0.47) 

(0.26) 

(0.24) 

(1.17) 

(0.74) 

(0.69) 

(1) 

water and the cost of the tank freeboard for precipitation water. 

(2) Costs are given for slurry application frequencies of two and four times per year. 
Source: [ 575, UBA Germany 2011 ] 

NB: NI = no information provided. 

Intensive Rearing of Poultry or Pigs 

545 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
Rigid covers like plastic or concrete lids and roofs are characterised by a long service period. 
The dilution of the slurry, as can occur in uncovered manure pits due to rain lowering the solid 
matter and the nutrient content, is avoided. In some  Member States, all new and substantially 
enlarged  slurry  stores  are  required  to  be  covered  (e.g.  the  UK).  In  Denmark,  it  has  been  a 
requirement since 1986 to store slurry in tanks with a tight cover. 

Example plants 
Several applications of rigid covers are present throughout the European Union. 

Reference literature 
[  26,  Finland  2001  ]  [  11,  ADAS  2000  ]  [  175,  Ecodyn  2010  ]  [  204,  IMPEL  2009  ]  [  259, 
France 2010 ] [ 508, TFRN 2014 ] [ 519, Amon et al. 2007 ] [ 525, BPEX 2011 ] [ 575, UBA 
Germany 2011 ] 

4.11.2.3 

Application of a flexible cover to slurry stores  

Description 
A cover made from flexible or pliant sheet material such as reinforced plastic sheeting or strong 
canvas that is stretched taut over the store. Various types of flexible covers exist. Descriptions 
of the main types and characteristics are given below. 

Tent covers (or covers held up by a central post) 
Tent  covers  have  a  central  supporting  pole  with  spokes  radiating  from  the  top.  A  fabric 
membrane or a polyester material with a high density (800–900 g/m2) is spread over the spokes 
and is secured at the edge of the tank, e.g. tied to a rim brace which is a circular pipe that is 
located on the outside around the circumference, just below the top of the store. The cover is 
tightened over the store by evenly spaced vertical straps between the rim brace and the tent rim. 

The pole and spokes are designed to withstand wind and snow loads. Whilst it is important to 
guarantee that covers are well sealed to minimise air exchange, there must be small openings or 
a  facility  for  venting  to  prevent  the  build-up  of  gases  under  the  cover.  The  cover  also 
incorporates  an  opening  for  an  inlet  pipe  and  a  hatch  that  can  be  opened  for  inspecting  the 
store’s contents. 

Dome-shaped covers 
Curved  structural  frames  are  installed  over  round  stores  without  needing  a  central  pole.  Steel 
components  are  assembled  by  bolted  joints  during  the  installation  on  farm.  Installations  can 
have around 600 m2 of round surface. Inspection windows can be adjusted in the flexible cover. 

A  similar  design  for  rectangular  pits  exists  consisting  of  galvanised  steel  arches  holding  a 
tunnel-shaped cover (600 g/m2) [ 259, France 2010 ].  

Flat covers 
These  covers  consist  of  a  flexible  and  self-supporting  composite  material,  held  by  stainless 
plugs on a galvanised steel structure all around the pit. For geomembrane pits, the construction 
of a concrete longitudinal beam around the pit is necessary. A system is generally incorporated 
to carry away the rainwater (impluvium with pump).  

Achieved environmental benefits 
Reductions  of  ammonia  emissions  of  80–90 %  have  been  reported  for  tent  covers  or  plastic 
covers, compared to storage tanks with no cover. During necessary stirring and pumping, odour 
emissions may arise, but, overall, odour emissions are reduced.  

546 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
Accumulation  of  toxic  and  flammable  gases  may  occur,  which  must  be  considered  for  safety 
reasons. The development of H2S may cause some corrosion, which can affect the structure and 
the cover. The recovery and utilisation of methane from the biogas may be a possibility, but at 
an extra cost.  

Environmental performance and operational data 
Covers must be durable and need to completely cover the slurry surface. Normally, masts are 
erected after the container is emptied and cleaned, although some installers can fit masts while 
slurry  is  in  the  tank.  Ammonia  reductions  are  in  the  range  of  50 %  compared  to  the  natural 
floating layer (see Table 4.160).  

Technical considerations relevant to applicability 
Flexible covers are not applicable in areas where prevailing weather conditions can compromise 
their structure. The larger the diameter of the store the more difficult the application of the cover 
will be, as the cover must be evenly taut in all directions to avoid uneven loads. 

From a UK survey, it appeared that tent-type covers can be applied to 50–70 % of the existing 
steel-type  stores  with  only  modest  modifications  needed.  Typically  this  consists  of  fitting  an 
additional stiffening angle strip around the rim of the store. Tent covers can be fitted to existing 
concrete  stores  without  modifications  for  diameters  under  30 m,  but  a  technical  survey  is 
recommended beforehand. It is important to calculate the required strength of the construction 
to ensure it can withstand wind and snow loads, for both the store and the store with cover. 

Most tent covers are held by structures that cannot be applied to existing square or rectangular 
concrete stores, which are common in many EU countries [ 506, TWG ILF BREF 2001 ]. With 
earth-banked  slurry  lagoons,  this  system  presents  significant  technical  difficulties  for  its 
implementation. In Belgium (Flanders), flexible covers should maintain their characteristics for 
at least 10 years [ 255, BE Flanders 2010 ]. 

Economics 
The  installation  of  a  tent  cover  on  an  existing  container  normally  requires  that  the  tank  be 
emptied  first  and  cleaned,  an  operation  that  costs,  in  Denmark,  approximately  EUR 1/m3 
(EUR 2 000  for  a  2 000  m3  store).  The  installation  of  the  tent  itself  costs  around  EUR 10  per 
cubic  metre  for  a  slurry  storage  capacity  of  7 700  m3,  which  corresponds  to  17 500  fattening 
pigs produced annually. The annualised investment costs are reported as EUR 0.2/m3 and costs 
expressed per fattening pig are equivalent to EUR 0.25, including savings from reduced use of 
mineral fertiliser, and due to reduced ammonia emissions [ 210, Denmark 2010 ].  

Costs for the purchase in France of flexible covers are given in Table 4.165. 

Table 4.165:  Costs for different types of flexible covers in France 

Investment costs (1) 

Type of cover 

EUR/t pig produced (2) 
10 
10–20  
 10–20 (4) 

Tent covers 
Flat covers 
Tunnel-shaped cover 
(1) Tax and installation cost excluded. Includes capital payback time of 10 years (8 years for tunnel-shaped 
covers).  
(2) Refers to a farm with 550 places for fattening pigs. 
(3) Refers to a duck rearing farm of 1 000 m2. 
(4) Installation costs included in the upper end of the range. 
Source: [ 259, France 2010 ] 

EUR/m3 slurry/year (3) 
0.9–2.9 
1.2–2.6 
1–2 (4) 

Annual  costs,  as  well  as  ammonia  reduction  costs,  reported  from  Germany  for  tent  covers 
applied on slurry storage are included in Table 4.163 and Table 4.164 (see Section 4.11.2.2), in 

Intensive Rearing of Poultry or Pigs 

547 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

comparison with a concrete cover and floating covers. Cost data for a fixed flexible tent cover 
applied to an above-ground slurry tank with a capacity of 1 037 m3 and a surface area of 314 m3 
(20 m in diameter and 3.6 m in height) are reported from the UK and presented in Table 4.166. 

Table 4.166:  Costs for covering an above-ground slurry tank with flexible covers, in the UK  

Type of cover 
Fixed flexible tent cover (3) 
(1) Cost data based on exchange rate EUR 1 = GBP 0.88. 
(2) Includes capital payback time of over 20 years, interest costs and maintenance costs. 
(3)  Investment  costs  include  tank  strengthening,  central  supporting  pole,  radial  webbing  straps,  etc.;  potential 

Annualised cost 
(EUR/year) (1) (2) 
2 050 

Investment cost 
(EUR/m2) (1) 
68.2  

Investment cost 
(EUR) (1) 
21 400 

savings, due to avoided rainfall to be spread with slurry, are not included.  

Source: [ 524, UK EA 2012 ] 

Driving force for implementation 
Slurries that are the output from biogas production, or from slurry separation processes, cannot 
develop  natural  floating  layers  because  of  their  low  dry  matter  content.  In  these  cases,  a  tent 
cover could be relevant. 

In some Member States, all new and substantially enlarged slurry stores are required be covered 
(e.g. the UK). In the UK, all existing slurry stores also have to be covered by 2020 [ 524, UK 
EA 2012 ]. In Denmark, it has been a requirement since 1986 to store slurry in containers with a 
tight cover [ 499, AgroTech 2008 ]. 

Example plants 
Applications  have  been  reported  in  the  UK  and  the  technique  is  widely  spread  in  France.  In 
Denmark, there are roughly 1 500 slurry tanks with tent covers applied on containers of 500 m3 
and over. On smaller containers, concrete covers are normally used.  

Reference literature 
[ 11, ADAS 2000 ] [ 210, Denmark 2010 ] [ 255, BE Flanders 2010 ] [ 259, France 2010 ] [ 499, 
AgroTech 2008 ] [ 506, TWG ILF BREF 2001 ] [ 524, UK EA 2012 ] 

4.11.2.4 

Application of a floating cover to slurry stores  

Description 
Floating  covers comprise a substance or material that rests on the surface  of the slurry. There 
are different types of floating covers, such as: 

 

 

 

 

 

 

 

 

 

548 

natural crust; 

straw (crust); 

peat; 

light bulk material (e.g. LECA, LECA-based products, perlite, zeolite); 

plastic pellets (polystyrene balls); 

oil-based liquids (e.g. rapeseed oil); 

floating flexible cover (e.g. plastic sheets, blankets); 

geometrical plastic tiles; 

air-inflated cover. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Natural crust 
This represents the simplest method of slurry covering. A floating crust is formed on the surface 
of stored slurry with a high dry  matter content, to which  the crust thickness is closely related 
[ 575, UBA Germany 2011 ]. Slurry containing litter and feed residues will naturally separate 
into a fraction with a high solids content and a fraction with virtually no solids. Depending on 
the type of feed residues and litter  contained in the  slurry, solids will either sink (e.g. usually 
feed residues)  or  rise to the  surface (e.g.  straw  bedding)  [499,  AgroTech  2008].  Natural  crust 
formation  over  the  slurry  is  enhanced  by  gasification,  i.e.  the  release  of  gases  that  are 
transported from the slurry to the store surface by means of bubbles which adhere to fibres and 
particles  that  will  float  on  the  store  surface.  During  winter,  with  little  anaerobic  activity  and 
ebullition,  the  crust  layer  may  sink  and  leave  the  slurry  uncovered.  This  may  not  be  a  major 
problem because ammonia emissions from uncovered slurry are low during cold seasons [ 590, 
Batfarm 2013 ]. Crusting is unlikely to occur in stores with a slurry dry matter content of < 2 % 
[439,  Sommer  et  al.  2006  ].  Under  Mediterranean  (e.g.  Spain)  climatic  conditions,  a  natural 
crust is easily formed at a rate of about 1 cm in  2 weeks. Minimising stirring and introducing 
new  slurry  below  the  surface  of  stored  slurry  help  the  build-up  of  a  natural  crust.  Emptying 
slurry from the bottom prevents the breaking of the crust. 

Straw or manure with a high content dry matter  
The formation of a fibrous floating layer on the surface of stored slurry is facilitated by adding 
chopped  straw or  other fibrous  material.  Straw  is  a  floating  cover  that  is  not  suitable for  very 
dilute pig slurry, as it may sink immediately, or, if it floats, it will be easily affected by wind 
and rain. It may also lead to blocked pumps and drains. However, when the pig slurry has a dry 
matter content of 5 % or higher, it is then possible to obtain a straw-induced crust that performs 
well [  11,  ADAS  2000 ]  [  209,  Denmark  2010  ].  Longer  chopped  straw in  a thick  layer  (e.g. 
4 cm long) can bind and float more easily [ 624, IRPP TWG 2013 ].  

Straw covers should be at least 10 cm thick. A thick layer of coverage consisting of manure or 
deep litter with a high dry matter content is very similar to a straw layer and will therefore have 
the same effect. 

Peat and light bulk material (e.g. LECA, LECA-based products, perlite, zeolite)  
A  floating  layer  is  formed  on  the  surface  of  stored  slurry  or  liquid  manure  produced  by  the 
addition of a suitable material. These covers have been more extensively researched and, from 
literature, appear to be easily applied. They cannot be reused and have to be replenished every 
year.  

When granulates such as light expanded clay aggregates (LECA) are used, material losses are 
lower than in the case of straw. Granules float up again shortly after the slurry has been stirred, 
therefore only a small amount of them is spread with the slurry [ 575, UBA Germany 2011 ].  

Polystyrene balls (EPS)  
Tank  covers  made  of  polystyrene  balls  of  20 cm  in  diameter  and  100 g  in  weight  (density  of 
23.8 kg/m3) are used and are easy to implement [ 259, France 2010 ]. 

Oil-based liquids (e.g. rapeseed oil)  
Generation of a floating, biodegradable cover on the slurry. 

Floating flexible covers (blankets, sheets)  
Canvas  (porous  textile  membranes)  or  flexible  plastic  sheets  rest  on  the  slurry  surface.  The 
cover is fixed to the rim of the store (e.g. by vertical ropes) or is designed to float freely on the 
surface.  They  are  equipped  with  an  inspection  hatch,  ventilation  openings,  and  openings  for 
filling and mixing the slurry. Also, a pump is used to drain any rainwater collected on top of the 
cover. Plastic sheets consist of a treated flexible synthetic fabric (anti-UV, salt spray, moulds, 
etc.) of variable density (660 g/m2 to 950 g/m2). 

Intensive Rearing of Poultry or Pigs 

549 

 
 
 
 
 
 
 
 
Chapter 4 

The canvas can be fixed, or kept in place by counterweights hanging over the rim of the store. 
Floating  covers  in  round  stores  may  rise  and  fall  with  the  slurry  depth,  sliding  their  floating 
edges on a galvanised steel structure, or they may be stretched over and tensed around a plastic 
hoop,  which  floats  on  the  surface  by  the  perimeter  walls.  This  metal  structure  channels  the 
rainwater  to  the  centre  of  the  cover.  The  rainwater  is  generally  collected  in  a  sump  and 
evacuated using a pump. An opening generally allows easy access to the inside (for mixing of 
the slurry, etc.). 

Geometrical plastic tiles  
Hexagonal  plastic  bodies  (bricks)  fit  together  on  the  slurry  surface  to  maximise  the  covering 
(see  Figure 4.78). These bodies are modular, can practically cover a surface of any shape and 
size  and  adapt  to  changes  in  the  slurry  level.  They  can  also  be  placed  on  empty  stores. 
Depending on the geometry of the container and the slurry's dry matter content, around 95 % of 
the surface can be covered. These covers can stop light rainfall from entering the slurry due to 
their design [ 525, BPEX 2011 ]. An enhanced version with an activated carbon filter allows the 
filtering of gaseous emissions [ 14, Spain 2014 ].  

Figure 4.78:  Geometrical plastic tiles in a slurry tank 

Source: [ 14, Spain 2014 ] 

Air-inflated covers  
A  treated  high-density  (915  g/m2)  PVC  fabric  is  supported  by  an  inflatable pocket  that  floats 
over the slurry. The fabric is fixed by a guy rope to a structure peripheral to at the pit, made out 
of galvanised steel. The  inflatable pocket is supplied by a low-pressure blower. An inspection 
door allows frequent inspection [ 259, France 2010 ]. 

Achieved environmental benefits 
Covering  the  slurry  surface  with  floating  covers  has  a  significantly  restrictive  effect  on 
ammonia volatilisation from slurry stores and thus reduces ammonia emissions. Covers greatly 
decrease the air exchange rate between the surface of the slurry and the atmosphere by creating 
a  stagnant  air  layer  above  the  slurry  through  which  NH3  has  to  be  transported  by  the  slow 
process of diffusion, which also decreases the ammonia losses [ 439, Sommer et al. 2006 ].  

Odour  emissions  are  reduced  because  the  surface  covering  forms  a  physical  barrier,  but  also 
because the biological conversion of odorous substances (oxidation of the odorous components 
by  microorganisms)  can  take  place  in  the  covering,  as  is  the  case  for  straw  covers  [  209, 
Denmark 2010 ]. There is some evidence that floating covers may reduce CH4 emissions from 
slurry stores [ 518, Sommer et al. 1999 ]. Geometrical plastic tiles with an activated carbon filter 
allow an extra reduction of ammonia, odour and other emissions to air. 

Cross-media effects 
Obviously,  some  floating  covers  that  mix  with  or  are  dissolved  in  the  slurry  may  affect  the 
quality  of  the  slurry  or  be  harmful  to  grazing  animals.  The  disposal  of  end-of-life  inorganic 
floating materials also has to be taken into account. A slight effect on N2O emissions has been 
observed.  It  appears  that,  in  relation  to  the  water  balance  of  the  crust,  a  cover  could  increase 
N2O emissions when dry conditions prevail.  

550 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Natural crust and straw crust 
Organic floating layers, like straw covers,  might increase CH4 and N2O emissions but there is 
still  great  uncertainty  about  the  quantification  of  how  much  of  this increase  is due  to  floating 
crusts.  The  Intergovernmental  Panel  on  Climate  Change,  IPCC  (2006  IPCC  Guidelines  for 
National  Greenhouse  Gas  Inventories)  suggests  an  emission  factor  for  N2O  emissions  of 
0.005 kg  of  N2O-N  per  kg  of  nitrogen  excreted  from  slurry  with  an  organic  crust,  which, 
compared to the emission factor for direct emissions from manure landspreading (0.01 kg N2O-
N), is  considered  substantial  [ 659, IPCC 2006 ]. The effect of straw and crust  on the  overall 
emissions of greenhouse gases is not fully known; however, covering slurry stores with organic 
floating  layers  is  not  expected  to  significantly  modify  the  emissions  of  greenhouse  gases, 
compared to uncovered stores [ 209, Denmark 2010 ]. It is estimated that stirring of the slurry 
would need approximately 10–12 litres of gasoline per tonne of added straw. 

Peat and light bulk material (e.g. LECA) 
Peat is a non-renewable resource and its digging is related to high indirect CO2 emissions. It has 
been measured that peat covers increase methane emissions by 30 % [ 259, France 2010 ]. Peat 
mixes  with  slurry  during  stirring,  gets  waterlogged  and  has  to  be  renewed  after  each  stirring. 
However, peat is a natural product and does not create a waste problem. 

Polystyrene balls (EPS)  
When plastic balls roll around, they expose the slurry sticking to the previously submerged face 
to  the  open  air  and therefore increase  emissions.  Wide  stores  are  subjected to the  wind effect 
and  loose  material  (i.e.  plastic  pellets  and  balls)  can  accumulate  on  one  side  and  uncover  the 
slurry surface. Therefore, it is necessary to regularly add balls to cover the uncovered zones, due 
to  the  turbulence  induced  by  the  configuration  of  the  containers  [  259,  France  2010  ][  522, 
Loyon et al. 2007 ].  

Oil-based liquids (e.g. rapeseed oil)  
Effects due to a reaction between the floating biodegradable cover (rapeseed oil by about 60 %) 
and  the  slurry  may  increase  the  emission  of  methane.  In  the  case  of  rapeseed  oil,  anaerobic 
reactions may produce surfaces with a strong, rancid odour.  

Floating flexible covers  
Accumulation of gases generated by slurry under closed (plastic) covers may occur which must 
be considered for safety reasons, hence the necessity for vents. If practicable, gases may be used 
in a biogas installation. 

Geometrical plastic tiles 
No information provided. 

Environmental performance and operational data 
In general, floating covers are easily applied, but cannot be placed on empty stores.  

Natural crust and straw crust 
In order to maintain the crust, stores are preferably filled from below [ 337, Webb et al. 2005]. 
Straw  should  not  be  chopped  too  short,  to  prevent  it  flying  away.  For  the  same  reason,  good 
operation  to  reduce  wind  blowing  consists  of  mixing  straw  with  slurry  at  the  time  of  slurry 
addition. Agitation is done with a pump or with a tractor-driven propeller in large slurry tanks 
[209, Denmark 2010]. 

In Germany, the minimum requirement in order to build up a floating cover of chopped straw 
with a reduction efficiency for ammonia emissions of 80 % is achieved with a layer of 10 cm 
(addition  of  5–10 kg  of  straw  per  m2  slurry  surface)  [  474,  VDI  2011  ].  In  Denmark,  it  is 
recommended  to  use  10–15 kg  of  straw  per  m2  slurry  surface,  which  will  result  in  an 
approximately  15–20  cm  thick  floating  layer.  A  reduction  in  ammonia  emissions  of  between 
60 % and 70 %, on average, is reported from the UK [ 11, ADAS 2000 ].  

Intensive Rearing of Poultry or Pigs 

551 

 
 
 
 
 
 
 
 
 
Chapter 4 

Application  of  straw  to  the  slurry  surface  is  preferably  done  with  a  forage  harvester  
[ 575, UBA Germany 2011 ]. The abatement achieved is effective at a low cost but has a short 
lifetime, as it deteriorates with rainfall and due to the climate. The floating layer of straw has a 
short lifespan and should be regenerated every year. 

Natural organic covering, whether a natural floating layer or with the addition of chopped straw, 
is used in Denmark as the reference for emissions from slurry stores. A factor of 2 % is assumed 
for nitrogen losses from the total stored nitrogen (total N). 
Farmyard manure or deep litter can also be used to establish a floating layer. A recommended 
quantity to use is 0.2–0.4 m3 of manure per m2 of slurry surface [ 499, AgroTech 2008 ] [ 591, 
Denmark 2009 ]. However, this type of cover is rarely used in pig farms, although it is typically 
found in cattle farms [ 591, Denmark 2009 ]. 

Peat and light bulk material (e.g. LECA, perlite) 
Light  bulk  materials,  such  as  LECA,  LECA-based  products,  perlite  and  zeolite,  or  peat  are 
added  to  the  slurry  surface  to  form  a  floating  layer.  A  floating  layer  of  10–12 cm  is 
recommended. Smaller LECA particles are generally more effective than larger particles; they 
can be relatively effective with a 3–5 cm layer. LECA is a permeable floating cover. It allows 
air to penetrate the floating layer and provides sufficient moisture and an adequate surface area 
for  a  population  of  aerobic  bacteria  to  develop.  In  this  way,  an  improved  effect  on  odour 
reduction  is  provided  [  592,  R.Burns,  L.Moody  2007  ].  The  material  does  not  prevent  rain 
entering the slurry store. Wet LECA is less effective, so a greater thickness of the cover could 
achieve a better efficiency. An annual replacement of 10 % of the material is required. It is easy 
to install in new and existing slurry stores and has a relatively long lifetime.  

LECA  can  provide  a  maximum  emission  reduction  of  about  80 %.  In  Germany,  a  reduction 
efficiency in ammonia emissions of 80–90 %, compared to an open store, is achieved with the 
use of LECA [ 474, VDI 2011 ]. 

The efficiency of floating peat covers for reducing ammonia emissions is reported to be in the 
range  of  80–90 %.  However,  in  France,  the  results  of  field  tests  were  not  completely 
satisfactory, with an ammonia emission reduction of approximately 25 %, in comparison with 
uncovered pig slurry storage.  

Perlite floats easily on the slurry surface, but its effectiveness in reducing ammonia emissions is 
variable and it was found to be easily blown by wind [ 592, R.Burns, L.Moody 2007 ]. The size 
of the lightweight aggregate material used for floating covers is 4–8 mm in Denmark; it can be 
delivered by truck, and spread evenly on the slurry. The reported quantity necessary is 20 kg per 
m2 of slurry surface, resulting in a floating layer of 10–12 cm [ 499, AgroTech 2008 ]. 

Polystyrene balls (EPS)  
As for light bulk materials, plastic pellets can be distributed in smaller layers. Turbulence over 
the  surface  are  induced  by  the  geometry  of  the  container,  hence  uncovered  spots  and 
deteriorated elements need to be regularly refilled or replaced [ 259, France 2010 ]. A study has 
shown that the use of a layer of polystyrene balls reduced ammonia emissions during storage by 
up to 80 % whatever the season [ 522, Loyon et al. 2007 ]. 

Oil-based liquids (e.g. rapeseed oil)  
Rapeseed  oil  (or  derivatives  with  high  percentages  of  rapeseed  oil)  is  very  easy  to  apply  and 
does not easily mix with pig slurry. However, it is biodegradable, loses its surface integrity over 
time  and  also  greatly  increases  methane  emissions.  Oil  covers,  tested  in  pilot  studies,  have 
shown to reduce emissions; while a 3 mm of oil layer had little effect, a 6 mm layer proved to 
be very efficient [ 590, Batfarm 2013 ].  

Floating flexible covers  
No  structural  alteration  is  necessary.  Agitation  is  possible.  Rainwater  can  be  pumped  off. 
Access for desludging is difficult. 

552 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
  
 
 
Chapter 4 

Geometrical plastic tiles 
This type of cover is easy to install in both new and existing slurry stores. However, they do not 
prevent  rain  from  entering  the  store.  Emissions  are  reduced  by  50–95 %,  compared  with 
uncovered containers. The degree of reduction depends on the amount of covered surface, e.g. a 
reduction of 90 % in ammonia emissions is assumed for a surface coverage of 95 % and 80 % 
for a 90 % surface coverage. Odour abatement is estimated to be in the range of 80–90 %. For 
the  enhanced  version  with  an  activated  carbon  filter,  the  reduction  efficiency  for  NH3  is 
reportedly  79 %  and  for  odour  compounds  (mercaptans,  phenol,  acetic  acid  and  putrescine) 
> 94 % and at least 50 % in all cases and for all emissions to air. 

Emissions 
The emission reduction efficiency varies with the cover type applied and is generally higher in 
summer than in winter. Table 4.167 gives an overview of the reduction efficiencies reported for 
different  types  of  floating  covers  applied  on  slurry  stores.  The  baseline  for  estimating  the 
mitigation efficiency of different covers is the emission from the same type of store, without any 
cover on the surface. 

Intensive Rearing of Poultry or Pigs 

553 

 
 
 
 
H2S 
(%) 

NI 

Cover 
durability 
(years) 

NI 

NI 
10–90 
NI 

0.5 or more 
NI 
NI 

Chapter 4 

Table 4.167:  Performance of different types of floating covers 

Type of cover 

Source 

NH3 
(%) 

CH4 
(%) 

Odour 
(%) 

Natural crust 

Straw crust 

Peat 

LECA 

Zeolite 

Perlite 
Plastic pellets 
(EPS balls) 

Rapeseed oil 

Floating 
flexible  covers 
(blankets, 
sheets) 

Geometrical 
plastic tiles 

[ 575, UBA Germany 
2011 ] 
[ 208, Spain 2010 ] 
[ 520, Fleming R. 2006 ] 
[ 209, Denmark 2010 ] 
[ 214, Germany 2010] 
[ 575, UBA Germany 
2011 ] 
[ 209, Denmark 2010 ] 
 [ 43, COM 2003 ] 
[ 520, Fleming R. 2006 ] 
[ 26, Finland 2001 ] 
 [ 43, COM 2003 ] 
[ 259, France 2010 ] 
[ 26, Finland 2001 ] 
[ 521, Portejoie et al. 
2003 ] 
[ 474, VDI 2011 ] 
[ 592, R.Burns, 
L.Moody 2007 ] 
[ 26, Finland 2001 ] 
[ 474, VDI 2011 ] 
[ 217, Denmark 2010 ] 
[ 521, Portejoie et al. 
2003 ] 
[ 520, Fleming R. 2006 ] 
[ 522, Loyon et al. 
2007] 
 [ 43, COM 2003 ] 
[ 26, Finland 2001 ] 
[ 520, Fleming R. 2006 ] 
 [ 43, COM 2003 ] 
[ 26, Finland 2001 ] 
[ 521, Portejoie et al. 
2003 ] 

[ 216, Denmark 2010 ] 

[ 520, Fleming R. 2006 ] 

Geometrical 
tiles 
plastic 
with  activated 
carbon 
NB: NI = no information provided. 

[ 14, Spain 2014 ] 

20–70 

28 
10–90 
80 

80 (Up to 
90) 

80 
60–70 
60–90 
71 
Up to 90 
25 
92 

77–100 

80–90 

65–95 

75–82 
80–90 
80 

93–98 

63–91 

NI 

NI 
NI 
NI 

NI 

NI 
NI 
NI 
NI 
NI 
+ 30 
NI 

NI 

NI 

NI 

NI 
NI 
NI 

NI 

NI 

NI 

NI 
NI 
NI 

NI 

80 
NI 
40–90 
NI 
Up to 90 
NI 
NI 

NI 

NI 

90 

NI 
NI 
NI 

NI 

NI 

NI 
NI 
80–95 
NI 
NI 
NI 
NI 

NI 

NI 

NI 

NI 
NI 
NI 

NI 

30–93 

64–84 

Up to 80 

+ 20 

NI 

NI 

Up to 90 
92–93 
85 
Up to 90 
92 

99 

80 
(50–95) 
95 

+ 60  Up to 90 
NI 
NI 
NI 
NI 

NI 
NI 
Up to 90 
NI 

NI 
NI 
NI 
90–95 
NI 

NI 

NI 

NI 

NI 

80–96 

NI 

NI 

NI 

NI 

82 

79 

65 

> 94 

NI 

1.2 
NI 
NI 
NI 
2 
NI 
NI 

NI 

NI 

NI 

NI 
NI 
NI 

NI 

NI 

NI 

NI 
NI 
NI 
10 
NI 

NI 

25 

NI 
25 
 (10 % filter 
replacement 
each year) 

Technical considerations relevant to applicability 
Floating bodies such as plastic pellets, light bulk materials and geometrical plastic tiles are only 
suitable for slurry without a natural floating layer. When the slurry is stirred and discharged, it 
should be ensured that floating bodies are not sucked in with the slurry in order to avoid losses, 
clogging and damages [ 575, UBA Germany 2011 ]. In particular, for viscous slurry capable of 
forming  a  natural  floating  layer,  expanded  clays  and  perlite  are  not  suitable as  they  cannot 
automatically distribute on the slurry surface and cover it. Similarly geometrical plastic tiles can 
be only used in low dry matter slurry without a natural crusting tendency (e.g. digestate from 
anaerobic digestion) [ 624, IRPP TWG 2013 ]. 

554 

Intensive Rearing of Poultry or Pigs 

 
 
 
Chapter 4 

Agitation  during  stirring,  filling  and  emptying  may  preclude  covering  with  some  floating 
materials.  They  may  cause  sedimentation  or  blockages  in  pumps  [  524,  UK  EA  2012  ].  For 
example, geometrical plastic tiles are not suitable where a frequent spreading of slurry requires 
mixing [ 624, IRPP TWG 2013 ]. 

Natural crust formation is an option for farms that do not have to mix the manure and disturb the 
crust in order to spread slurry frequently. A crust may not form in cool climates and/or on slurry 
with a low dry matter content [ 508, TFRN 2014 ].  

The use of straw covers in large slurry stores (i.e. lagoons) may be problematic, since the larger 
the slurry storage structure the more difficult it is to achieve a uniform application of materials. 
In rainy climates, the use of dry straw is not recommended because, when rained on, the rate at 
which the straw sinks dramatically increases [ 592, R.Burns, L.Moody 2007 ]. 

The use of floating flexible covers on slurry stores that are emptied on an annual or semi-annual 
basis or that have high sides [ 508, TFRN 2014 ], and hence have a large variation in manure 
level, also requires special installation considerations, to allow an impermeable synthetic cover 
to move up and down as the level of stored manure changes [ 592, R.Burns, L.Moody 2007 ].  

Economics  
Normally, floating covers have the same costs for both new and existing tanks. Where natural 
crusts  with  a  sufficient  thickness  are  possible,  and  slurry  is  introduced  below  the  crust,  a 
significant ammonia reduction can be achieved at little or no cost [ 508, TFRN 2014 ].  

The straw price varies locally and as a function of annual climatic conditions. In 2012, the price 
per kg of straw reported from Spain was around EUR 0.04–0.10.  

The initial purchase of straw represents about 55 % of the total costs, while the remaining 45 % 
is distributed on machine and staff hours. The floating straw layer may have a lifespan of 1 to 
2 years [ 209, Denmark 2010 ].  

Annual costs, as well as ammonia reduction costs, reported from Germany for floating covers 
are  presented  in  Table 4.163  and  Table 4.164  (see  Section  4.11.2.2),  in  comparison  with  a 
concrete  cover  and  a  tent  cover.  Investment  cost  data  for  some  types  of  floating  covers  in 
Denmark are summarised in Table 4.168.  

Table 4.168:  Investment costs for some types of floating covers, in Denmark  

Type of cover 

Investment costs  

EUR/m3  EUR/m2 

Annualised 
investment costs  
EUR/m3/yr 

Remarks 

Geometrical 
plastic tiles 

8–10 

35–40 

LECA 

1.75 

Straw cover 

NI 

7 

1 

NB: NI = no information provided. 

0.5 

0.2 

0.25 

Based on a durability of 25 years and a surface 
area  of  approximately  1 000 m2  (height  of 
storage tank: 4 m) 
Based  on  a  supplement/refill  of  10 %  of  the 
surface material 
The 
to  be 
regenerated every year (height of storage tank: 
4 m) 

is  assumed 

floating 

layer 

Source: [ 216, Denmark 2010 ] [ 217, Denmark 2010 ] [ 209, Denmark 2010 ] 

Intensive Rearing of Poultry or Pigs 

555 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Some indicative cost data reported by France are shown in Table 4.169. 

Table 4.169:  Investment costs for different types of floating covers in France 

Investment costs (1) 

EUR/t pig produced (2) 
10 
3–10 

Type of cover 
Air-inflated covers (4)  
Floating flexible covers (5) 
(1) Tax and installation costs excluded. Includes capital payback time of 10 years. 
(2) Refers to a farm with 550 places for fattening pigs. 
(3) Refers to a duck rearing farm of 1 000 m2. 
(4) For an air-inflated cover, the energy consumption for the blower is considered negligible.  
(5) For a floating cover, the energy consumption for operating the pump for the drainage of rainwater 
is negligible.  
Source: [ 259, France 2010 ] 

EUR/m3 slurry/year (3) 
1.8 
0.4–1.3 

Cost data for a floating flexible cover applied to an above-ground slurry tank with a capacity of 
1 037 m3 and a surface area of 314 m3 (20 m in diameter and 3.6 m in height) are reported from 
the UK and presented in Table 4.170.  

Table 4.170:  Costs  for  covering  an  above-ground  slurry  tank  with  floating  flexible  covers,  in  the 

UK  

Investment cost 
(EUR/m2) (1) 
28.4 

Type of cover 
Floating flexible cover (3) 
(1) Cost data based on exchange rate EUR 1 = GBP 0.88. 
(2) Includes capital payback time of over 20 years, interest costs and maintenance costs. 
(3) Potential savings, due to avoided rainfall to be spread with slurry, are not included.  
Source: [ 524, UK EA 2012 ] 

Investment cost 
(EUR) (1) 
9 000 

Annualised cost 
(EUR/year) (1) (2) 
910 

From  Spain,  the  investment  cost  for  the  use  of  a  floating  flexible  cover  is  reported  to  be 
EUR 20/m2,  corresponding  to  an  extra  cost  of  EUR 2.3/m3  or  EUR 28.8/t  of  pig  produced  
[ 379, Spain 2009 ]. Investment costs for geometrical plastic tiles with activated carbon filters 
are  reported  to  be  EUR 123/m2  and  the  annualised  costs  EUR 2.3/m3  (tanks)  or  EUR 5.8/m3 
(lagoons) [ 14, Spain 2014 ]. 

Driving force for implementation  
In some Member States, local regulations require that slurry stores are covered (e.g. Denmark 
and Germany from the mid-1980s). In the UK, all new and substantially enlarged slurry stores 
should  be  covered  before  use  and  all  existing  slurry  stores  must  be  covered  by  2020  
[ 524, UK EA 2012 ]. 

Inorganic covers, like geometrical plastic tiles, are an alternative to organic material covers, and 
require less maintenance. The ammonia that is not emitted can potentially generate more yield 
on  the  field,  due  to  the  increased  nitrogen  application  per  hectare.  Inorganic  covers  may  be 
useful for slurries that, coming from other treatments (biogas, separation, etc.) for example, do 
not  have  the  ability  to  create  natural floating  layers because  of their low  dry  matter  content  [ 
216, Denmark 2010 ].  

Example plants 
It is estimated that 10 % of the Danish covers are made of light bulk material [ 217, Denmark 
2010  ].  In  Denmark,  natural  floating  covers  or  straw  crusts  are  estimated  to  represent  the 
majority of the total covered slurry surface (about 80 %) [ 209, Denmark 2010 ]. In 2004, the 
proportion of stores with a natural crust applied on Danish pig farms was less than 50 %; 5 % 
were equipped with a fixed roof, around 5 % used peat or LECA, and almost half of stores were 
covered with straw added without stirring. 

Peat is used in Finland. 

556 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Reference literature 
[  11,  ADAS  2000  ]  [  14,  Spain  2014  ]  [  26,  Finland  2001  ]  [  43,  COM  2003  ]  [ 208,  Spain 
2010 ] [ 209, Denmark 2010 ] [ 214, Germany 2010 ] [ 216, Denmark 2010 ] [ 217, Denmark 
2010 ] [ 259, France 2010 ] [ 379, Spain 2009 ] [ 439, Sommer et al. 2006 ] [ 474, VDI 2011 ] 
[ 499, AgroTech 2008 ] [ 506, TWG ILF BREF 2001 ] [ 508, TFRN 2014 ] [ 520, Fleming R. 
2006  ]  [  521,  Portejoie  et  al.  2003  ]  [  522,  Loyon  et  al.  2007  ]  [  524,  UK  EA  2012  ]  [  556, 
ADAS  2000  ]  [  575,  UBA  Germany  2011  ]  [  590,  Batfarm  2013  ]  [  592,  R.Burns,  L.Moody 
2007 ] [ 624, IRPP TWG 2013 ] 

4.11.2.5 

Application of covers to earth-banked slurry stores (lagoons)  

Description 
Lagoons tend to have a larger surface area per unit volume than tanks. Emissions to air can be 
reduced by decreasing the airflow across the surface by installing floating covers. 

Flexible  plastic  sheet  covers for earth-banked  slurry stores are  based  on  flexible  impermeable 
UV-stabilised plastic sheets (e.g. HDPE) that are secured at the bank tops. Floats and tubes are 
installed to keep the cover in place (prevent the cover from turning during manure mixing and 
being lifted off by wind) and to allow it to float over the slurry as the level of liquid increases 
and  decreases,  while  maintaining  a  void  beneath  the  cover  for  the  purpose  of  gas  collection. 
Covers may be fitted with collection piping (gas vents) for the gases that develop on the covered 
surface  or  to  negatively  pressurise  the  cover  [  520,  Fleming  R.  2006  ].  Rainwater  can  be 
pumped off the top, preventing dilution [525, BPEX 2011 ].  

Other  applied  floating  covers  are  geometrical  plastic  tiles  (e.g.  hexagonal  bodies),  chopped 
straw,  peat  or  a  natural  crust  (see  Section  4.11.2.4).  The  use  of  LECA  and  LECA-based 
products is also possible for smaller lagoons.  

Achieved environmental benefits 
Reductions in ammonia and odour emissions can be achieved. Ammonia emission reductions of 
about 95 % or more have been reported. Reduced ammonia emissions of 82 % are reported with 
the application of LECA. Chopped straw covers are reported to reduce ammonia emissions by 
70 %, whilst natural covers reduce them by 28 % [ 379, Spain 2009 ]. 

Cross-media effects 
For covering a lagoon, a large amount of plastic is needed. This can measure up to 70 % more 
than  the  actual  lagoon  surface  area,  depending  on  the  depth  and  inclination  of  the  edges.  A 
benefit is that the cover can be reused, whereas other covers are consumables. 

Floating  covers  such  as  chopped  straw,  LECA,  peat,  and  oil-based  liquids  do  not  divert 
rainwater  and  require  management  time  during  store  filling,  mixing  and  emptying  [  648, 
DEFRA 2011 ].  

There  is  the  potential  to  apply  the  rainwater  that  gathers  on  top  of  plastic  sheet  covers  to 
irrigation,  but  it  would  require  careful  monitoring  of  the  water  for  slurry  leakage  or  other 
contamination.  Farmers  are  not  in  favour  of  recycling,  for  reasons  of  hygiene  and  disease 
control. 

Stirring  of  the  slurry  would  mix  the  slurry  and  its  LECA  layer,  which  would  then  increase 
ammonia emissions temporarily. It has been observed that the LECA cover re-establishes itself 
very quickly after stirring and that emissions again drop to a reduced level. However, LECA as 
a cover does create problems with landfilling. N2O emission may be enhanced by the organic 
crust that develops on the surface. 

Intensive Rearing of Poultry or Pigs 

557 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Environmental performance and operational data 
By keeping rainwater out, plastic covers could effectively increase the capacity of a lagoon by 
as much as 30 %. This would either give more storage flexibility over time or provide a larger 
capacity in case of an expansion in farm stocking. 

The lagoon must be emptied completely of slurry and sludge to allow  the fitting of the cover. 
Wind damage is not a problem if the cover is well fixed on the sides and if some rainwater is 
kept on top to weigh it down. Modifications to current agitation and emptying methods may be 
necessary but, with the relatively low dry matter content of pig slurry, mixing is not a problem. 
If adequate agitation cannot be performed, problems with sludge accumulation may arise after a 
number of years. 

Lifetimes of flexible plastic sheet covers of up to 10 years have been reported. Precautions are 
recommended for the winter season to prevent the plastic sheet cover from tearing, i.e. removal 
of rainwater on top of the cover to minimise ice formation [ 520, Fleming R. 2006 ].  

LECA  can  be  blown  onto  the  slurry  surface  or  pumped  with  the  slurry.  The  latter  technique 
causes less dust and loss of material and has a higher rate of distribution. Mixing and pumping 
with slurry may damage the material and should be performed gently. 

An artificial floating crust cover is the minimum mandatory requirement in Germany (5–10 kg 
of  chopped  straw  per  m2,  depending  on  the  kind of slurry)  to  obtain  a  minimum  reduction of 
80 % of ammonia emissions compared to the uncovered surface.  

Technical considerations relevant to applicability 
Plastic sheeting is well tested on small earth-banked lagoons [ 508, TFRN 2014 ]. Plastic sheets 
can be difficult to fit and manage on larger lagoons [ 648, DEFRA 2011 ] If lagoon walls are not 
accessible or structurally sound to allow anchoring of the plastic sheet, secured covers cannot be 
used;  then  the  application  of  floating  materials  is  possible  [  524,  UK  EA  2012  ].  Therefore, 
plastic sheets may not be applicable to large existing lagoons due to structural reasons. 

Straw and light bulk materials may not be applicable to large lagoons where wind drift does not 
permit  the  lagoon  surface  to  be  kept  fully  covered.  The  use  of  light  bulk  materials  is  not 
applicable to naturally crusting slurries. 

Agitation  of  the  slurry  during  stirring,  filling  and  emptying  may  preclude  the  use  of  some 
floating  materials  which  may  cause  sedimentation  or  blockages  in  the  pumps.  Natural  crust 
formation may not be applicable in cold climates and/or on slurry with a low dry matter content. 
Natural crusts are not applicable to lagoons where stirring, filling and/or discharging of slurry 
frequently disturbs the surface. 

Economics 
Total  annual  costs  and  emission  reduction  costs  for  different  covers  of  earth-banked  slurry 
stores  (lagoons),  in  comparison  with  uncovered  lagoons,  are  reported  in  Table 4.171  from 
Germany. 

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Table 4.171:  Cost data for different covers of earth-banked slurry stores (lagoons), in Germany  

Investment and annual costs 
(1) 

Emission reduction and mitigation 
costs  

Type of cover 

Uncovered (reference) 
Floating flexible cover  
Light bulk materials 

Straw  

Annual costs 
(EUR/m3/yr) 

1.08 
1.34 
1.23 

1.35 

Investment 
costs 
(EUR/m2) 
NI 
11.5 
NI 

NI 

EUR/kg 
NH3 

EUR/kg NH3 
(2) 

NI 
0.42 
0.26 

0.48 

NI 
0.22 
0.07 
0.31 (2 times per year)  
0.84 (4 times per year) (3) 

(1) Cost data refer to a lagoon with a capacity of 7 500 m3 (75 X 25 m). A storage duration of 6 months was assumed; 
the expenses presented are based on an annual slurry quantity which is twice as large as the usable capacity.  
(2) Cost data take into account the value of conserved nitrogen, the expenses for landspreading of precipitation water 

and the cost of the tank freeboard for containing precipitation water. 

(3) Costs are given for slurry application frequencies of two and four times per year. 
NB: NI = no information provided. 

Source: [ 575, UBA Germany 2011 ] 

From  the  UK,  examples  of  costs  are  reported  for  covering  a  slurry  lagoon  with  a  capacity  of 
4 540 m3 and a surface area of 2 000 m2 (50 m × 40 m at the top of the lagoon and 4 m deep).  

Table 4.172:  Investment costs for covering a slurry lagoon in the UK  

EUR  
75 000 
75 000 
56 800 

Type of cover 

Investment costs (1) 

EUR/m2 
37.5  
37.5 
28.4 

Annualised costs (2) 
EUR/yr 
5 681 
NI 
4 261 (5) 

Floating flexible cover (3) 
Light bulk material (LECA) (4) 
Geometrical plastic tiles 
(1) Values in EUR as per exchange EUR 1 = GBP 0.88. 
(2) Include capital repayment over a 20-year payback period, interest costs and maintenance costs. 
(3)  Investment  costs  include  the  supporting  grid  and  pump  to  remove  rainwater,  but  do  not  include  potential 

savings due to not having to spread rainfall with slurry.  

(4) 10 % annual replacement is included for 20 years. 
(5) Geometrical plastic tiles are 25 % cheaper than a floating flexible cover, but they do not prevent rainfall from 

entering the store, with the consequent need to dispose of the water with the slurry. 

NB: NI = no information provided. 

Source: [ 524, UK EA 2012 ] 

The cost of constructing or expanding an impermeable lagoon store ranges between EUR 12.74 
and EUR 24 per m3 of slurry in Spain. The variation depends on the soil type, dimensions of the 
lagoon  and  material  utilised.  Furthermore,  the  unit  cost  for  chopped  straw  used  for  floating 
covers is reported as EUR 0.04–0.1/kg of straw [ 379, Spain 2009 ]. 

Additional costs will be incurred on farms where modifications are needed to the structure, or to 
emptying and agitation methods. Efficient rainwater management determines the differences in 
operating costs, where LECA-covered lagoons may coincide with higher slurry application costs 
and where application costs will be higher where rainwater can enter the slurry.  

The cost of spreading the rainfall collected from an uncovered lagoon is estimated at EUR 1.6 
per  m3.  Rainwater  collected  on  the  top  of  a  floating  flexible  cover  remains  clean  and  can  be 
pumped to ditches and watercourses. Every 500 mm of rainfall on a 2 000 m2 slurry lagoon is 
equivalent  to  1  000 m3  of  water.  Not  having  to  spread  it,  at  a  cost  of  EUR 1.60 m3,  gives  a 
saving of EUR 1 600 per year. In areas with high rainfall, a cover could almost be cost-neutral  
[ 524, UK EA 2012 ]. 

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With plastic coverings, net costs depend on the possibilities for reuse of water for irrigation. The 
use  of  biogas  (methane)  depends  on  the  purpose  (heating  or  engine)  and  on  the  installation 
requirements. It might be profitable but the cost recovery period might be quite long (over 20 
years). 

Driving force for implementation 
In areas with high rainfall, placing a plastic sheet cover over the slurry surface can result in a 
significant  reduction  in  overall  slurry  volumes  with  subsequent  savings  due  to  not  having  to 
transport  and  landspread  the  avoided  larger  volume  of  slurry  and  rainwater  [  524,  UK  EA 
2012 ]. 

Example plants 
In the Netherlands, covers on lagoons have been in use for many years [ 11, ADAS 2000 ]. 

Reference literature 
[ 11, ADAS 2000 ] [ 208, Spain 2010 ] [ 379, Spain 2009 ] [ 508, TFRN 2014 ] [ 520, Fleming 
R. 2006 ] [ 524, UK EA 2012 ] [ 525, BPEX 2011 ] [ 556, ADAS 2000 ] [ 575, UBA Germany 
2011 ] [ 648, DEFRA 2011 ] 

4.11.2.6 

Techniques to protect soil and water against emissions from slurry 
storage 

Emissions of nitrate and phosphate to soil and water can be prevented by implementing certain 
requirements  for  the  construction,  maintenance  and  inspection  of  installations  used  for  the 
collection and piping of liquid manure (channels, drains, pits, pipes, slide gates) and the storage 
of slurry.  

4.11.2.6.1 

Storage tank construction and auxiliary equipment for slurry 
collection and transfer  

Description 
Above-ground  storage  tanks  are  large,  normally  open-top,  circular  vessels  made  of  steel  or 
concrete.  The  base  plate  is  concrete  cast  in  situ,  without  joints  whenever  possible.  Walls  are 
concrete or made of circular sections of prefabricated steel with corrosion-resistant coating. The 
structure  may  have  a  covering  lid.  Slurry  flows  over  the  rim  or  below  the  slurry  surface. 
Unloading  pipes  are  fitted  with  at  least  two  safety  devices  and  sliding  gates  and  pumps  are 
easily accessible. The reinforced concrete that is used should be impermeable, with high frost 
and chemical resistance (see also Section 2.6.5.1).  

For tanks made of prefabricated concrete elements and a concrete framework, the internal wall 
surfaces  and  a  0.5 m  wide  strip  of  the  base  need  to  be  protected  with  a  suitable permanently 
elastic  coating  or  lining  to  bridge  the  cracks.  The  suitability  of  this  should  be  attested  by  an 
inspection certificate. 

Above-ground steel tanks require a coating (enamel or paint) to protect against corrosion. The 
suitability of the seal at the joint of the wall with the tank base needs to be certified. Base plates 
are made of concrete in situ and should be at least 18 cm thick.  

Underground silos are built in situ with the same characteristics as the  above-ground concrete 
silos, but obviously the base is not observable from the outside. In Germany, leakage checks are 
mandatory (geomembrane with drainage and leakage control) (see also Section 2.6.5.1). 

Slurry pits are constructed of precast blocks or bricks, reinforced concrete, coated steel, polymer 
plastics  and  other  suitable materials;  they  need  to  be  leak-proof  with  an  internal  sealing  or 

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lining. The same requirements apply to tanks of precast concrete blocks. The maximum slurry 
level may rise no higher than 10 cm below the pit cover or the floor grille.  

Collection facilities such as channels, drains, pits, pipes and gate valves for the collection and 
piping of liquid manure, slurry and effluents (manure removal channels), the inlet to the slurry 
pit  or  pump  station,  and  the  slurry  pit  or  pump  station  itself  should  all  be  fabricated  of 
corrosion-resistant  material.  Return  flow  pipes  of  the  storage  tank  are  fitted  with  at  least  two 
safety devices. Gate valves have to be adjusted in such a way that they are easily accessible and 
are in an impermeable shaft. Pumps should be easily accessible. Constructions of the slurry pit 
and pump station have to be sealed and impermeable.  

Transfer  facilities  are  all  structural/technical  facilities  intended  for  the  homogenisation  and 
transfer of slurry. This category also includes transfer areas with the relevant installations used 
for transfer (pumps, gate valves). Areas in which slurry is transferred must be impermeable to 
water and designed to drain into a tank without an outlet (e.g. slurry tank, pump station). 

An  example  of  an  underground  slurry  tank  made  of  concrete  cast  in  situ  with  a  liquid-tight 
geomembrane fixed to the tank is shown in Figure 4.79. 

Source: [ 593, UBA Germany 2013 ] 

Figure 4.79:  Underground slurry tank with liquid-tight geomembrane  

Achieved environmental benefits 
Nutrient input (nitrates and phosphates) into underground and surface water is prevented.  

Cross-media effects 
None reported. 

Environmental performance and operational data 
After emptying a slurry store, inspection and maintenance will prevent a further risk of leakage. 
The application of double valves in pipes used for emptying the tank will minimise the risk of 
an  unwanted  discharge  of  slurry  into  the  farmyard  and  surrounding  premises  (surface  water). 
The use of block floodgates is an extra tool to limit leak risks [ 259, France 2010 ]. In Germany, 
construction  of  underground  silos  in  areas  with  water  protection  legislation  in  place  is  not 
allowed. 

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Technical considerations relevant to applicability 
The  building  of  storage  tanks  that  are  able  to  withstand  mechanical,  chemical  and  thermal 
influences  is  generally  applicable.  The  construction  of  leakproof  facilities  and  equipment  for 
collection and transfer of slurry is generally applicable.  

Economics 
The investment costs for underground tanks are higher than for above-ground tanks. Cost data 
reported  for  the  construction  of  above-ground  and  underground  silos  for  slurry  storage  are 
presented in Table 4.173.  

Table 4.173:  Cost data for above-ground and underground slurry silos 

Type of silo (1) 

Above-ground 

Above-ground, in 
water protection area 

Underground 

Investment costs 
(EUR/m3) 
35 
(30–39) 
40 
(35–45) 
55 
(45–60) 

Total costs  
(EUR/m3/yr) 
3.2 
(3.0–3.5) 
3.7 
(3.5–4) 
5 
(4.4–5.5) 

Source 

[ 426, Germany 2010 ] 

[ 214, Germany 2010 ] 

 [ 215, Germany 2010 ] 

(1) Silos with 1 500 m3 storage capacity; usable net volume (diameter 20 m, building height 5.2 m, usable height 

4.7 m, freeboard 0.5 m). 

Driving force for implementation 
Local regulations and location in areas with water protection legislation in place are drivers. 

Example plants 
In Germany, the procedures for defining the dimensions, constructional design and materials for 
slurry  stores,  together  with  instructions  on  maintenance  and  inspection,  are  described  in  DIN 
Standards and are widely applied. 

Reference literature 
[  214,  Germany  2010  ]  [  215,  Germany  2010  ]  [  259,  France  2010  ]  [  426,  Germany  2010  ] 
[ 593, UBA Germany 2013 ] 

4.11.2.6.2 

Measures to prevent and inspect leakage from slurry stores  

Description  
In  order  to  allow  inspection  of  storage  tanks  for  leaks  during  operation,  the  construction  of  a 
drainage system below the base plate is necessary, in addition to the basic requirements for the 
construction of slurry tanks to prevent leakage as described in Section 4.11.2.6.1.  

Leakage inspection systems collect liquids in a leak-proof space below the base plate of slurry 
tanks. They consist of the following components:  

 

 

 

 

impermeable layer; 

drainage layer; 

drainage pipe; 

inspection pipe or shaft. 

The impermeable layer is usually made of a heat-sealed flexible geomembrane, which is fixed 
liquid-tight  to  the  tank  to  prevent  infiltration  of  rainwater  (see  Figure 4.79).  Alternatively, 
membranes  may  only  overlap  if  there  is  a  slope.  Above  the  impermeable  layer,  the  drainage 
layer is built up of gravel or plastics. Drainage pipes are embedded as a circumferential or area 
drainage  system  to  discharge  leaked  slurry  from  the  tank  to  the  inspection  pipe  or  shaft. 

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Chapter 4 

Circumferential drainage systems are adequate only in the case of heat-sealed geomembranes. 
They consist of a drainage pipe that is located below the rim of the base plate around the whole 
tank [ 214, Germany 2010 ]. 

In the case of area drainage systems, the drainage pipes are located in an array below the base 
plate. The drainage layer should have a minimum thickness of 20 cm and drainage pipes should 
be covered with a layer of at least 10 cm. The single drainage pipes are bundled in an inspection 
shaft. 

Inspection  pipes  are  placed  at  the  above-ground  level.  They  should  be  at  least  20 cm  in 
diameter,  in  order  to  allow  sampling  of  water.  Inspection  shafts  are  usually  made  from  shaft 
rings with a diameter of 80 cm (see Figure 4.80). Inspection pipes and the shaft are covered and 
liquid-tight to prevent infiltration of rainwater.  

If  water  occurs  in  the  inspection  devices,  contamination  by  slurry  will  be  detected  in  water 
samples  that  will  indicate  a  leakage  of  the  slurry  tank.  The  distance  between  the  inspection 
devices should not exceed 15 m. 

Achieved environmental benefits  
Leakage inspection systems are an effective measure to protect soil and water against nutrient 
(N and P) losses.  

Cross-media effects 
Not relevant. 

Source: [ 593, UBA Germany 2013 ] 

Figure 4.80:  Inspection shaft for area drainage pipes from a slurry store 

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Environmental performance and operational data 
In addition to proper planning and construction according to the relevant local regulations, water 
protection requires careful operation and facility maintenance. The responsibilities of the facility 
operator include regular checks of the tightness of slurry tanks, pipes, and fittings, as well as the 
operability  of  the  inspection  equipment.  The  operator  of  a  facility  is  required  to  monitor  its 
compliance with regards to operation and leak-proofing at all times before and during operation 
of a slurry tank. In the case the filling-level inspection or inspection of the structural condition 
of the facility give rise to any suspicion of leakage, an immediate notification to the competent 
authorities is required. 

In  Germany,  leakage  checks  (e.g.  pressure  tests)  of  underground  pipes  must  be  repeated 
approximately  every  10–12  years.  The  results  of  the  tests  have  to  be  kept  on  file  and  made 
available to the competent authorities on request.  

Technical considerations relevant to applicability  
The  installation  of  a  leakage  detection  system  is  only  applicable  to  new  stores.  Checking  the 
structural integrity of stores at least once a year is generally applicable.  

Economics  
Examples  of  investment  costs  for  slurry  tanks  equipped  with  leakage  inspection  systems  are 
reported by Germany and presented in Table 4.174.  

Table 4.174:  Investment costs for slurry tanks and leakage inspection systems in Germany 

Useable storage capacity (1) 
Height  
Inner diameter 

Dimensions 
500 m3 
4.0 m 
13.5 m 
Investment costs (EUR) 

1 500 m3 
5.0 m 
20.5 m 

3 000 m3 
6.0 m 
26.5 m 

5 000 m3 
6.0 m 
34.0 m 

Construction and materials 
29 800 
Concrete (in situ) 
34 800 
Precast concrete elements 
39 200 
Steel, enamelled 
Additional leakage inspection system (2) 
400 
(1) With 20 cm freeboard and 30 cm buffer for rainwater. 
(2) Circumferential drainage system with two inspection shafts. 
Source: [ 593, UBA Germany 2013 ] 

48 500 
56 500 
63 800 
7 300 

80 500 
97 000 
107 200 
10 500 

115 300 
139 600 
153 300 
15 000 

Driving force for implementation  
General  requirements  of  water  legislation  (Nitrates  Directive,  Water  Framework  Directive) are 
drivers. A leakage inspection system is mandatory for most slurry tanks in Germany and, at least, 
for  tanks  in  areas  where  water  resource  management  is  a  priority  (e.g.  areas  with  water 
protection legislation in place).  

Example plants  
Several hundred slurry tanks with leakage inspection systems are in operation in Germany. 

Reference literature 
[ 593, UBA Germany 2013 ] 

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4.11.2.6.3 

Impermeable lining for earth-banked slurry lagoons 

Description  
Earth-banked lagoons are constructed with water-impermeable base and walls, e.g. with clay or 
plastic lining (see Section 2.6.5.2). Clay can be applied in situ or an appropriate clay lining is 
applied. A double-layered geomembrane can also be used. 

Chapter 4 

Achieved environmental benefits  
Nutrient leaching to surface and groundwater is prevented. 

Cross-media effects 
Not relevant. 

Environmental performance and operational data  
In Germany, for double-layered geomembrane lagoons, leakage control is mandatory. Pipelines 
are made of corrosion-resistant material and those for the return flow from the storage tanks are 
fitted with at least two safety devices. Slide gates and pumps are easily accessible. The slurry pit 
and  pump  station  are  sealed  in  an  impermeable  construction.  Areas  in  which  liquid 
manure/slurry is transferred are fenced and are designed to drain into a tank without an outlet 
(e.g. slurry tank, pump station). In addition to proper planning and construction according to the 
relevant regulations,  water  protection  requires  careful  operation and facility  maintenance. The 
facility operator is required to perform regular checks of the leakproofness of containers, pipes 
and  fittings,  as  well  to  verify  the  good  operating  condition  of  the  control  equipment.  Leak 
testing (e.g. pressure tests) of underground pipes  should be repeated approximately every 10–
12 years. Within areas with water protection legislation in place, the intervals are shorter. 

Technical considerations relevant to applicability  
Storing slurry in earth-banked stores (lagoons) with an impermeable base and walls, e.g. with 
clay or plastic lining (or double-lined), is generally applicable.  

Economics  
In  Germany,  for  double-layer  lining,  investment  requirements  range  from  EUR 18  to  EUR 24 
per  m3,  for  lagoons  with  a  usable  volume  of  1 500  m3.  The  reported  total  annual  costs  are 
EUR 1.9–2.0/m3/yr.  

Driving force for implementation  
The solution implies lower investment  costs than those for concrete silos. Water legislation in 
Germany requires that earth-banked lagoons are built with a double-layered geomembrane and a 
floating crust cover as a minimum. 

Example plants 
This technique is commonly applied. 

Reference literature 
[ 211, Germany 2010 ] 

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4.12  Techniques for the on-farm processing of manure 

4.12.1 

Introduction 

Several techniques are available for manure processing and can be classified into four main categories: 

 

 

 

 

techniques for treating raw manure or a mixture with other organic matter;  

techniques for treating slurries (raw manure);  

techniques for treating liquid fractions after separation of raw manure;  

techniques for treating solid fractions or solid manures [ 594, Agro Business Park 2011 ]. 

Site-specific conditions, constraints and opportunities present at the local level, as well as farm requirements 
reflecting the local environmental conditions, determine the optimal combination of techniques belonging to 
the above groups (e.g. the nitrogen surplus) [ 590, Batfarm 2013 ]. In the event that local conditions are such 
that  alternative  costs  (i.e.  transport  out  of  the  region)  are  lower  than  the  treatment  itself,  the  treatment  of 
manure is not to be pursued (e.g. in Ireland poultry manure is exported off site for use in the production of 
mushroom compost). 

For example, in particular areas it is possible to find a combination of a high concentration of farms together 
with a lack of available land for spreading the manure in the vicinity of the farm. In these cases, in order to 
avoid an excess of nutrients in the soil, manure processing by one or more techniques which have the ability 
to reduce the nitrogen content in the slurry is an option. In other cases, treatment is necessary as there may be 
a critical situation in terms of odour nuisance due to landspreading, because of the proximity of residential 
areas. Treatment to minimise odour emissions can then allow  more flexibility for identifying suitable sites 
and weather conditions for landspreading [ 624, IRPP TWG 2013 ]. 

Manure  processing  is  mainly  applied  with  the  objective  of  improving  manageability  and  utilisation  of 
livestock manure; this includes balancing the quantity of nutrients with the crop requirements, wider options 
for returning the organic matter and nutrients to land in a more controlled way and improving the stability 
and plant availability of nitrogen and phosphorus. However, if conditions allow (e.g. large enough spreading 
area, local nutrient demand, compliance with local regulations), the spreading of untreated slurry in order to 
fertilise  crops  has  to  be  preferred.  For  example,  in  the  Baltic  region,  the  over-supply  of  phosphorus  with 
fertilisation  has  been  studied  and  more  than  40  techniques  for  manure  processing  have  been  identified  
[ 218, Baltic Sea 2020 2010]. 

Other objectives of manure processing may be the reduction of emissions to the atmosphere (NH3, odours, 
GHG, etc.), the production of energy through anaerobic digestion, the removal of pathogens, or the removal 
of xenobiotic compounds (emerging pollutants). A processing strategy can consist of a single process or a 
combination  of  various  unitary  processes.  Schematic  representations  of  a  number  of  manure  processing 
strategies, which can be applied in cases of nutrient surplus, are presented in Figure 4.81.  

566 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Diagram of the processing scheme 

Chapter 4 

Process and 
objective 

Solid-liquid 
separation with 
composting of the 
solid fraction.  

External use of 
compost; on-farm 
use of the liquid 
fraction as 
fertiliser 

Anaerobic 
digestion with 
solid-liquid 
separation; 
composting of the 
solid fraction and 
ammonia stripping 
with consequent 
absorption. 

Production of 
biogas (energy), 
external use of 
compost and 
ammonia 
concentrate; on-
farm use of the 
liquid fraction for 
irrigation 
Solid-liquid 
separation and 
nitrification-
denitrification of 
the liquid fraction. 

Partial nitrogen 
removal, and on-
farm use of the 
remaining 
products 
Source: [ 594, Agro Business Park 2011 ] 

Figure 4.81:  Examples of manure processing strategies 

The  technical  and  environmental  performances  of  a  manure  processing  technique,  or  a 
combination of different techniques (processing strategy), can be affected by: 

 

 

 

the characteristics of the manure; 

the features of the individual treatments applied; 

the way the techniques are operated. 

The  off-farm  treatment  of  manure  is  not  within  the  scope  of  this  document,  but  it  is  widely 
applied and is likely to increase further in the future.  

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The  attention  given  to  manure  processing  is  strongly  influenced  by  the  management  costs  of 
untreated  manure.  In  the  Netherlands,  the  on-farm  treatment  of  manure  is  mainly  based  on 
mechanical  separation  techniques  that  are  applied  for  intensive  livestock  farms  without 
sufficient land and which have problems with manure transportation to other places. The basic 
separation  techniques  were  developed  in  the  1990s  and,  although  new  separation  techniques 
have  been  developed  on  an  experimental  scale  (like  membrane  separation),  the  practical 
application of the techniques at the farm level has not really changed since then.  

In  Belgium  (Flanders),  the  total  costs  of  the  most  common  techniques  vary  between  EUR 20 
and EUR 30 per treated m3. The economic analysis performed showed that manure processing is 
only economically feasible for 30 % of the pig farms. In areas with a medium to high manure 
pressure, slurry treatment is feasible only if farms are able to spread at least 80 % on their own 
farmland.  In  areas  with  a  high  quantity  of  manure  produced,  the  pressure  for  implementing 
manure processing is even higher. 

Economic analyses showed that large-scale, high-tech processing techniques are expensive and 
may  only  be  affordable  for  farms  with  a  high  turnover,  or  in  regions  with  high  livestock 
densities, where all alternative solutions for manure management are even more expensive. In 
these cases, the cooperation between several farmers in the processing facility is necessary.  

A summary of the main characteristics of the techniques for processing manure, as described in 
this section, is given in Table 4.175. Full descriptions and references are given in the relevant 
subsections. 

Table 4.175:  Summary of the main characteristics of techniques for processing manure  

Section 

Processing technology 

Aim 

4.12.2 

Mechanical solid-liquid 
separation of slurry by: 
 
 
 
 
 
 
 

screw press 
decanter centrifuge 
coagulation-flocculation 
sieves-drum filters 
filter press 
air flotation 
natural settling  

Separation and 
concentration of the 
solid and liquid 
fractions of slurry 

Main environmental 
benefits 
Solid fractions easily 
exported outside the 
farm, reducing 
problems derived from 
nutrient surplus, 
reducing phosphorus 
accumulation and 
nitrate leaching to 
water 

4.12.3 

Aeration of liquid 
manure/biological treatment: 
 
 

aerobic digestion 
nitrification-
denitrification 

Biological 
decomposition of 
organic matter. 
Removal of 
ammoniacal nitrogen 
as N2 gas 

Pathogen and odour 
emissions reduction.  
Removal of 
biodegradable organic 
matter 

Main cross-
media effects 

Risk  of  gaseous 
emissions. 
Indirect 
CO2 
emissions  due  to 
electricity 
consumption 

Under non-
optimal 
conditions, odour, 
CH4 and N2O 
emissions may 
occur. NH3 
emissions and loss 
of N fertilising 
value of slurry 
when combined 
with a 
nitrification-
denitrification 
stage 

568 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Section 

Processing technology 

Aim 

4.12.4 

Composting of solid 
manure: 
 
 

composting  
co-composting of 
poultry manure with 
green residues 
composting with a 
biological inoculum 

 

Obtain a 
stable product with a 
low moisture content 
and retaining most of 
the initial nutrients, 
free of pathogens  

4.12.5  Anaerobic treatment  

Production of biogas. 
Mineralisation and 
stabilisation of 
organic matter  

Chapter 4 

Main cross-
media effects 

Emissions of NH3, 
odour and CH4 
during the process 
operation 

Uncontrolled 
leakages of biogas 
with a consequent 
emission of CH4. 
Potential 
emissions from 
digestate storage 
(CH4, H2S, NH3, 
N2O) 

Main environmental 
benefits 
Substantial reduction 
of transport costs and 
related CO2 emissions, 
due to significant 
reduction of mass 
(water evaporation). 
Production of organic 
fertiliser. Removal of 
pathogens. Reduction 
of odour emissions 
Reduction of GHG 
emissions by: 
- decreasing potential 
CH4 emissions  
- decreasing fossil fuel 
consumption 

Reduction of pathogen 
content and increased 
hygienisation. 
Reduction of offensive 
odour 

4.12.6  Anaerobic lagoon system 

Combined slurry 
stabilisation, 
separation and 
storage 

Improved quality of 
solid and liquid 
fractions 

High CH4 
emissions 

4.12.7 
4.12.13 

Evaporation and drying of 
manure. 
Slurry and wet manure belt 
dryer 

Increase nutrients 
and organic matter 
concentration. 
Reduced volume for 
easier and cheaper 
transport 

Dried, concentrated 
and hygienised product 
easy to handle, with 
moderate-high 
concentration of 
nutrients (N and P)  

4.12.8 

External tunnel for manure 
drying 

4.12.9  Slurry acidification 

4.12.10  Combustion of poultry litter  

Reduction of 
ammonia emissions 
by drying droppings 
collected by manure 
belts  
Reduction of 
ammonia emissions 
by lowering the pH 
of manure, with 
consequent 
ammonium (NH4-N) 
retention in the 
manure  
Energy production 
by thermal oxidation 
of organic material. 
Energy recovery 
with possible 
transformation into 
electricity 

Reduction of ammonia 
and odour emissions 

Reduction of ammonia 
emissions 
Possible reduction of 
CH4 emissions 

Energy savings. 
Fertiliser value of the 
produced ashes  

Heavy metals are 
concentrated in 
the concentrate 
stream that can 
limit product 
application or 
landspreading. 
Direct or indirect 
CO2 emissions, 
depending on the 
energy source 
used. High NH3 
volatilisation 

Energy 
consumption, with 
indirect CO2 
emissions 

Emissions of 
VOCs and odours 
from the oxidation 
reaction due to the 
addition of a 
strong acid 

Emissions to air 
from combustion 
(NOX, SOX, etc.). 
Loss of N as 
fertiliser and 
organic matter of 
manure 

Intensive Rearing of Poultry or Pigs 

569 

 
Chapter 4 

Section 

Processing technology 

Aim 

4.12.11  Ammonia stripping 

4.12.12  Manure additives 

Removal of 
ammonia through 
volatilisation from a 
liquid phase, with 
subsequent recovery 
in an acidic solution 
as ammonium salt or 
by condensation 

Facilitate handling 
and management of 
manure. Stabilisation 
of manure and 
reduction of the 
pathogen contents 

Main environmental 
benefits 
Less nitrogen content 
in slurries, with 
consequent easier 
management on farm. 
Reduced odour 
emissions from 
manure landspreading. 
Recovery of a valuable 
nutrient (nitrogen) 

Reduced ammonia, 
odour and GHG 
emissions. 
Reduced content of 
pathogens 

Main cross-
media effects 

Energy 
consumption, with 
indirect CO2 
emissions 

High variability in 
efficiency 

Other  techniques  are  being  studied,  with  promising  results.  These  techniques  are  not  yet 
available 
reasonable  costs,  but  are  worth  mentioning  
[ 256, VITO 2006 ]: 

for  on-farm  application  at 

 

 

 

 

 

Membrane  filtration:  after  pre-filtration,  reverse  osmosis  is  used  to  separate  nitrogen, 
potassium and phosphorus salts from water. 

Struvite (magnesium ammonium phosphate) precipitation: the addition of MgO or MgCl2 
and  H3PO4  results  in  the  precipitation  of  magnesium  ammonium  phosphate,  with  the 
consequent  possible  recovery  of  both  phosphorus  and  ammoniacal  nitrogen.  Treatment 
plants based on this technique have been set up in the Netherlands and Germany. 

Algae culture. 

Activated carbon filtration. 

Ion exchange. 

  Wet oxidation.  

4.12.2  Mechanical separation of slurry 

4.12.2.1 

Introduction 

Description 
The  mechanical  separation  of  coarse,  fibrous  material  from  liquid  manure,  especially  slurry, 
aims  to  produce  a  more  free-flowing  liquid  fraction  and  a  stackable  solid  fraction.  These 
products are easier to manage than slurry. 

The liquid fraction can be stored and/or transported/pumped to fields for landspreading with a 
lower nutrient content. It can also be further processed in situ (e.g. aeration) before its use for 
rinsing/cleaning  purposes  or  as  fertiliser.  The  liquid  fraction  requires  less  power  for  pumping 
through pipes, for mixing and for aeration and is less likely to form a crust or sediment during 
storage. 

The solid fraction is managed as solid manure (e.g. it can be stored on a concrete pad) and can 
be  spread  on  remote  areas  with  a  nutrient  demand  or  can  be  applied  in  other  processes  (e.g. 
composted, anaerobically digested). Nutrients (N, P, K) and organic matter are concentrated in 
the solid fraction, thus enhancing the capability of manure/slurry management. 

570 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
There are several different types of machines with different principles of operation that produce 
liquid and solid fractions in different proportions and with different dry matter contents. These 
include: 

Chapter 4 

 

 

 

 

screw press separator (see Section 4.12.2.2); 

decanter-centrifuge separator (see Section 4.12.2.3); 

separation by sieves (see Section 4.12.2.5); 

filter pressing (see Section 4.12.2.6). 

Separation  can  be  enhanced  by  coagulation-flocculation  of  solid  particles  as  part  of  the 
treatment process (see Section 4.12.2.4).  

Achieved environmental benefits 
Mechanical separation of slurry does not create any environmental benefits in itself. However, 
positive environmental effects can be derived from how the liquid and solid fractions are stored 
and  used after separation.  The benefits  of  slurry  separation  strongly  depend  on the  separation 
efficiency, which can vary significantly, making slurry separation unattractive if the efficiency 
of the process is poor. The management of two separated fractions, the liquid with the higher 
nitrogen  content  and  the  solid  richer  in  phosphorus, allows  for  a  more  accurate  dosing  of  the 
nutrients, thus limiting the risk of an excess supply of nitrogen and phosphorus. 

Mechanical separation of slurry may help to reduce an excess of nutrient supply at a local level 
(nitrate  leaching  and  phosphorus  accumulation),  e.g.  in  areas  that  drain  to  vulnerable  aquatic 
environments  such  as  Natura  2000  sites,  lakes,  fjords,  and  sensitive  zones  for  drinking  water 
supply. In this case, it is assumed that the solid fraction is not delivered as fertiliser in the same 
area along with the liquid fraction but, instead, is further processed (e.g. as substrate in biogas 
plants)  or  used  for  purposes  other  than  agriculture  (e.g.  for  incineration),  or  delivered  as 
fertiliser in areas with a low livestock density and/or nutrient deficiency or where fields are not 
commonly supplied with organic matter [ 223, Denmark 2010 ].  

In  Denmark  in  2007,  over  half  of  the  solid  fraction  produced  was  applied  to  the  farmland, 
around 40 % was delivered to biogas plants, while only a small proportion was incinerated or 
utilised in some other way [ 227, Denmark 2010 ].  

Landspreading  of  the  thinned,  separated  liquid  fraction  results  in  a  faster  penetration  into  the 
soil,  because  of  the  low  dry  matter  content,  with  consequently  lower  ammonia  and  odour 
emissions and lower contamination of the crops. The organic load in terms of COD and BOD is 
lower.  The  faster  infiltration  into  the  soil  also  allows  better  handling  and  evenness  of  spread 
[ 203, ADAS 2005 ]. 

An overall assessment of the environmental benefits achievable with slurry separation includes 
avoided  CO2  emissions  from  reduced  transport  (which  are  counterbalanced  by  increased 
electricity  demand  during  the  process  of  separation  and  depend  on  the  distance  that  the  solid 
fraction  is  transported)  and  from  possible  biogas  production,  as  well  as  reduced  indirect 
emissions  associated  with  the  avoided  production  of  the  mineral  fertilisers  for  the  supply  of 
phosphorus [ 499, AgroTech 2008 ]. 

Cross-media effects 
A  common  potential  cross-media  effect  for  all  separation  techniques  is  that  during  operation 
some ammonia volatilisation and odour emissions may occur, depending on the specific system 
in operation, as a result of the high level of exposure to air due to increased mixing of the slurry 
or systems that employ considerable stirring. In closed systems (e.g. a centrifuge separator or a 
press  auger),  and  when  coverings  are  in  place,  the  release  of  odour  is  limited.  Likewise,  the 
slurry separation may result in a marked increase in NH3 and N2O emissions during the storage 
phase of the two fractions, because of the large emissions from the stored solid fraction, if it is 

Intensive Rearing of Poultry or Pigs 

571 

 
 
 
 
 
 
 
 
Chapter 4 

not covered [ 624, IRPP TWG 2013 ]. The solid fraction may result in N2O emissions of up to 
4.8 % of the initial total N over a 4-month period of storage [ 443, Chadwick et al. 2011 ]. 

Additionally,  in  areas  where  only  low-phosphate  fertilisation  is  allowed,  a  cross-media  effect 
will be that that the organic material cannot be spread on agricultural soils [ 624,  IRPP TWG 
2013 ]. 

Environmental performance and operational data 
The main technical characteristics of some of the applied techniques for mechanical separation 
are summarised in Table 4.176, as reported by the Netherlands. Among other factors, the energy 
consumption  needed  to  separate  manure  depends  on  its  dry  matter  content.  Efficiencies  and 
solid  phase  characteristics  normally  depend  on  the  slurry  type  and  equipment  used  for  the 
separation. 

In general, a high dry matter content yields a better separation result of all dry matter, N, P, and 
K, hence separation of fresh manure is preferred because stored manure usually has a lower dry 
matter content [ 219, Netherlands 2010 ]. 

Table 4.176:  Characteristics and technical data of common slurry separators in the Netherlands 

Technique 

Flow rate  
(m3/h) 

Capital 
cost 
(thousand 
EUR) 

Phosphorus 
separation 
efficiency 
(%) 

Dry matter 
content in 
solid phase 
(%) 

Specific 
energy 
consumption 
(kWh/m3 
slurry) (1) 

Remarks 

0.5  

< 30 

< 25 

> 25 

4–15 

10–20 

10–30 

Screw press 

Inclined sieve, 
drum filter, 
drum filter with 
press rolls, etc. 

Some types have 
very low P 
separation 
efficiency 
Average 
separation 
efficiency 
Additives needed, 
high efficiency 
High efficiency, 
Centrifuge-
Decanter 
high maintenance  
(1) The energy consumption of a slurry separation installation is often given excluding the basic peripherals such 
as mixers, pumps, conveyor belt systems, compressors, etc. This leads to an underestimation of the costs in this 
table. For example: a mobile centrifuge with a high capacity could be outfitted with a generator for the required 
electrical  power.  Fuel  consumption  of  this  generator  could  be  estimated  to  be  1 litre  of  diesel/m3  of  manure 
processed (this yields about 10 kWh/m3 of manure treated). 

Filter belt press 

50–75 (2) 

60–70 (3) 

4–100 

20–40 

25–35 

20–25 

25–30 

> 100 

4–30 

> 70 

1.0  

0.1  

4.0  

(2) Using additives. 
(3) Without using additives. 
Source: [ 219, Netherlands 2010 ] 

Sequential separation using different techniques with recycling of liquids and solids can yield a 
higher  concentration  of  the  solid  fraction.  With  the  use  of additives,  the  phosphate separation 
efficiency can be increased to over 60 %.  

It should be considered that a single separation process is very rarely sufficient to achieve both a 
highly concentrated solid fraction and a clarified liquid. A multi-stage process, with recycling of 
liquids and solids, is needed if both objectives are important [ 203, ADAS 2005 ]. When the size 
of  solids  in  the  slurry  is  very  heterogeneous,  a  combination  of  separation  systems  may  be 
applied, such as the use of a grid followed by a finer separation stage, in order to separate big 
particles that can block transfer elements such as pumps and pipes.  

572 

Intensive Rearing of Poultry or Pigs 

  
 
 
 
 
 
 
 
 
 
Separation,  but also  other manure  processing  techniques,  should  be  carried out in  such  a  way 
that the final product is competitive with mineral fertilisers and untreated manure by adjusting 
its properties (e.g. nutrient composition) according to the needs of farmers. 

Chapter 4 

Technical considerations relevant to applicability 
The technique is only applicable when: 

 

 

the farm is situated in an area with a nutrient surplus and a reduction of the nitrogen and 
phosphorus content is needed due to the limited land available for manure application; 

manure cannot be transported for landspreading at a reasonable cost. 

Economics 
Costs vary widely reflecting sophistication and performance. Normal depreciation periods could 
be 5, 7 or 10 years, whereas maintenance costs could represent between 2.5 % and 40 % of the 
initial  investment.  Mobile  separation  units  serve  several  sites  but  have  higher  maintenance 
needs  than  on-farm  separator  units.  Costs  of  mechanical  separators  in  the  Netherlands  are 
presented in Table 4.177.  

Table 4.177:  Costs  of  slurry  mechanical  separation  in  the  Netherlands  for  an  annual  capacity  of 

5 000 m3  

Technique 

Investment  Depreciation  Electricity  Maintenance  Additives 

Total 

EUR  

EUR per treated m3 of liquid manure 

Sieve separators 

25 000 

Screw press 

30 000 

Filter belt press 

70 000 

0.50 

0.60 

1.40 

0.06 

0.12 

0.01 (1) 

100 000 

Centrifuge 
separator 
(1)  1 kWh equals EUR 0.12. 
(2)  Additionally needed: flushing water (10 bar), compressed air (8 bar). 
(3)  Additionally needed: anti-foam agent (PM). 
Source: [ 219, Netherlands 2010 ] 

2.00 

0.48 

0.25 

0.30 

0.70 

1.00 

0 

0 

0.81 

1.02 

1.00 (2) 

3.11 

Option (3) 

3.48 

Driving force for implementation 
The  major  driving  force  for  implementing  slurry  separation is related  to  local  regulations  and 
conditions, such as scarce availability of land for manure application (e.g. in the Netherlands) or 
restrictions on the application of phosphorus. 

The separated fractions (solid and liquid) are easier to transport. In addition, separation enables 
greater  flexibility  in  manure  management  and  application  timing.  Storage  requirements  and 
transportation  costs  of  the  liquid  fraction  are  reduced  as  a  5–10 %  reduction  of  volume  is 
typically  achieved  by  separation  [  648,  DEFRA  2011  ],  the  solid  fraction  can  be  transported 
more easily and material is more homogeneous for landspreading. 

Example plants 
A survey showed that slurry separation was practised in about 11 000 farms of different sizes, 
with 80 % of the farms located in Italy, corresponding to about 45 % of the total treated manure 
covered by the survey. The most commonly used separation techniques are drum filters, screw 
pressing and separation by sieves, representing respectively 42 %, 33 %, and 18 % of the total 
European farms applying a slurry separation system [ 595, Agro Business Park 2011 ]. 

In the district of Vendée in France, a mobile separator moves from farm to farm to separate the 
duck slurry. The solid fraction is composted [ 259, France 2010 ]. 

Intensive Rearing of Poultry or Pigs 

573 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Reference literature 
[ 203, ADAS 2005 ][ 219, Netherlands 2010 ] [ 220, Germany 2010 ] [ 221, Denmark 2010 ] 
[ 222,  Denmark  2010  ]  [  223,  Denmark  2010  ]  [  227,  Denmark  2010  ]  [  259,  France  2010  ] 
[ 443, Chadwick et al. 2011 ] [ 499, AgroTech 2008 ] [ 595, Agro Business Park 2011 ] [ 624, 
IRPP TWG 2013 ] [ 648, DEFRA 2011 ] 

4.12.2.2 

Screw press separator 

Description 
This  technique  is  based  on  the  application  of  pressure  to  separate  by  filtration  the  suspended 
solids contained in the slurry into a solid and a liquid fraction. A screw or auger rotates inside a 
cylindrical metal tube, squeezing out the liquid fraction and discharging the solid fraction at the 
end of the tube. 

Slurry is either pumped into the separator directly or it flows through a funnel with the aid of a 
vibration  unit  to  facilitate  the  even  material  flow  into  the  press,  in  particular  when  slurry  is 
thick.  At  the  press,  the  slurry  enters  a  cylindrical  screen  (0.5–1  mm)  by  means  of  a  rotating 
screw, which conveys the slurry into the pressure zone. The liquid passes through the screen and 
is collected in a container surrounding the screen. At the end of the axle, the fraction rich in dry 
matter  is  pressed  against  a  cylindrically  shaped  screen.  The  slurry  filter  cake  is  compressed 
during pressure filtration, producing a solid fraction with a high dry matter content. Increasing 
the applied pressure increases the dry matter content of the solid fraction. 

A schematic representation of a screw press is given in Figure 4.82. 

Source: [ 221, Denmark 2010 ] 

Figure 4.82:  Screw press scheme 

574 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
The  separation  of  the  initial  nitrogen  and  phosphorus  content  of  the  slurry  into  two  fractions 
(liquid  and  solid)  allows  a  reduction  of  the  problems  related  to  a  nutrient  surplus,  i.e. 
phosphorus accumulation and nitrate leaching to water. See also Section 4.12.2.1. 

Cross-media effects 
Cross-media  effects  may  include  energy  consumption  (electricity)  to  run  the  equipment,  with 
associated  indirect  emissions.  During  operation,  ammonia  volatilisation  and  odour  emissions 
may occur, depending on the specific system in operation.  

Environmental performance and operational data 
4–20 tonnes of slurry per hour can be treated, depending on the type of separator used and the 
dry  matter  content  of  the  slurry.  Examples  from  Germany  and  Denmark,  concerning  the 
characteristics of input and output materials, show that after processing slurry with a dry matter 
content of 6.5–7 % in a screw press, a liquid fraction of 3–4.4 % and a solid fraction of 20–30 % 
of dry matter content can be separated. The range of performance of a screw press is presented 
in Table 4.178.  

Table 4.178:  Separation performance range of a screw press  

Parameter 

Liquid fraction 

Solid fraction 

% of input 

Mass flow 
Total solids 
Volatile solids 
COD 
Nitrogen 
Phosphorus 
Source: [ 561, Flotats et al. 2004 ] 

75–85 
40–80 
30–70 
40–70 
60–90 
20–70 

15–25 
20–60 
30–70 
30–60 
10–40 
30–80 

The energy consumption (electricity) to run the equipment depends on the input material (slurry, 
digestate) and varies from 0.3 kWh to 1 kWh per tonne of input material.  

Technical considerations relevant to applicability 
The technique  is  generally  applicable  to  a  wide  range  of  dry  matter  contents  of  the  slurry,  as 
well as for processing digestate from biogas production. Only slight adaptation is necessary in 
existing farms, e.g. inclusion of a storage plate for the solid fraction.  

Economics 
Investment costs for a unit with a capacity of 8–20 tonnes/hour are reported to be in the range of 
EUR 20 000–45 000.  Depending  on  the  capacity  of  the  processing  unit  and  the  dry  matter 
content of the slurry, investment costs can also be expressed as EUR 2 000–5 000 per tonne per 
hour. With an amortisation period of 10 years and a 6 % interest rate, the annualised investment 
costs are EUR 260–650 per tonne of treated slurry or EUR 3 300–4 600 per unit. From a plant 
located  in  Spain  treating  10 000  m3/year,  the  estimated  investment  cost  of  the  screw  press  is 
reported to be EUR 28 000 [ 594, Agro Business Park 2011 ]. 

Extra operating costs are reported from Germany in the range between EUR 0.6 and EUR 1.25 
per animal place per year, or between EUR 0.9 and EUR 1.87 per tonne of treated slurry. These 
are calculated for a unit with a treatment capacity of 10 m3/h, 5 kW of power installed (cost of 
electricity EUR 0.15/kWh), serving farms of 2 000 or 5 000 animal places, respectively, which 
produce  1.5 m3  of  slurry  per  animal  place  annually.  Treatment  costs  are  also  reported  as 
EUR 0.5–0.9  per  m3  of  input  slurry;  for  a  unit  with  a  treatment  capacity  of  10 000 m3/h, 
operating costs are reported as EUR 0.66/m3 [ 594, Agro Business Park 2011 ]. 

Intensive Rearing of Poultry or Pigs 

575 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

From Denmark, annual operating costs are estimated to be in the range of EUR 0.14–0.17 per 
tonne of input. The labour demand in Denmark is estimated to be approximately 0.1–0.25 hours 
per working day. In the Netherlands, for a capacity of 4–15 m3/h and an annual treated quantity 
of 5 000 m3, investment costs of over EUR 30 000, and operating costs of at least EUR 1.02/m3, 
are reported (see Table 4.176). 

Driving force for implementation 
Local restrictions on nutrient supply and lower transportation costs due to reduced transported 
volumes are drivers. See also Section 4.12.2.1. 

Example plants 
In 2009, at least 3 600 screw presses for the separation of slurry were in operation in Europe. 

Reference literature 
[ 220, Germany 2010 ] [ 221, Denmark 2010 ] [ 561, Flotats et al. 2004 ] [ 594, Agro Business 
Park 2011 ] [ 595, Agro Business Park 2011 ] 

4.12.2.3 

Decanter-centrifuge separator 

Description 
This  mechanical  separator  relies  on  rapid  rotation  generating  a  sufficient  centrifugal  force  to 
cause the separation of solids from the liquid. There are vertical and horizontal types of decanter 
centrifuges. The slurry enters the decanter centrifuge in the centre of the machine, which rotates 
at a high speed, typically 3 000–5 000 rpm. The centrifugal force separates solids and liquids at 
the wall into an inner layer with a high dry matter concentration and an outer layer consisting of 
a liquid containing a suspension of colloids, organic components and salts. The solid particles of 
the  slurry  are  conveyed  towards  the  conical  end  and  let  out  through  the  solid  discharge 
openings, whereas the supernatant flows towards the larger end of the cylinder formed by the 
bowl  and  the  flights  of  the  conveyor.  The  liquid  phase  is  discharged  through  openings  at  the 
wide end of the decanter centrifuge. A macerator can be used before the decanter to shred the 
large particles into smaller ones. 

A schematic representation of a decanter-centrifuge slurry separator is shown in Figure 4.83. 

Source: [ 222, Denmark 2010 ] 

Figure 4.83:  Schematic of a decanter centrifuge for slurry separation 

576 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Achieved environmental benefits 
The  separation  of  the  initial  nitrogen  and  phosphorus  content  of  the  slurry  into  two  fractions 
(liquid  and  solid)  allows  a  reduction  of  the  problems  related  to  a  nutrient  surplus,  i.e. 
phosphorus accumulation and nitrate leaching to water. See also Section 4.12.2.1. 

Cross-media effects 
Energy  consumption  (electricity)  is  required  to  run  the  equipment,  with  associated  indirect 
emissions.  

Environmental performance and operational data 
Fixed  systems  have  a  capacity  of  approximately  6 tonnes  per  hour,  whereas  mobile  units  can 
have a larger capacity of 10–25 tonnes per hour. In order to enhance the separation efficiency, 
the  use  of  polyelectrolytes  is  normally  considered.  The  main  characteristics  of  the  input  and 
output flows of a decanter centrifuge for separation of typical pig slurry in Denmark are shown 
in Table 4.179. 

Table 4.179:  Characteristics  of  the  separated  fractions  from  a  decanter-centrifuge  separation  of 

typical pig slurry in Denmark 

Treated matter 

Input 
Output: separated liquid phase 
Output: separated solid phase 
Source: [ 222, Denmark 2010 ] 

Dry matter 
(%) 
5.0 
2.2 
18 

Total N 
(kg/t) 
4.0 
3.2 
6.6 

Total P 
(kg/t) 
1.0 
0.3 
4.3 

Centrifugation  is  the  technique  that  reports  the  higher  separation  efficiencies.  The  average 
efficiency  of  centrifugation,  as  a  separation  technique,  expressed  as  proportions  of  the  solid 
fraction, is reported to be: 14 vol-%, 61 % dry  matter, 28 % Total N, 16 % NH4-N, and 71 % 
Total  P.  In  Denmark,  the  proportion  of  total  nitrogen  in  the  dry  matter  fraction  from  the 
centrifuge is between 18 % and 28 % and the proportion of phosphorus in the solid fraction after 
separation is between 60 % and 70 %. Additional operational data are reported in Table 4.176. 

Increasing the retention time by reducing the volumetric feed rate has been observed to increase 
the efficiency of the separation of slurry. The separation efficiency of dry matter increases with 
a  higher  dry  matter  content  of  the  slurry.  There  are  differences  in  the  capacity  between  fixed 
centrifuges and mobile centrifuges. In Denmark, fixed systems have a capacity of approximately 
5–7 tonnes/hour, whereas mobile units can have a higher capacity of 10–25 tonnes/hour [ 596, 
Denmark 2009 ]. 

The energy consumption for the operation of a decanter centrifuge is reported to be in the range 
between 2 kWh/m3 and 4 kWh/m3 [ 594, Agro Business Park 2011 ]. From Denmark, the energy 
consumption is reported as about 2.5 kWh per tonne of treated slurry.  

Technical considerations relevant to applicability 
There are no restrictions for the application of this technique.  

Economics 
The  cost  of  the  fixed  configuration  of  the  equipment  is  reported  from  Denmark  to  be  in  the 
range of EUR 19 000–21 000 per hourly tonne of capacity, or approximately EUR 115 000 for a 
system  with  a  capacity  of  six  tonnes  per  hour.  The  operating  costs  have  been  measured  as 
EUR 0.3–0.6 per tonne of treated slurry. Labour requirements are estimated to be approximately 
0.25 h/working day. 

Other  reported  data  indicate  investment  costs  of  between  EUR 40 000  and  EUR 60 000,  for  a 
treatment capacity of 1.5–2 m3/h, and treatment costs are reportedly in the range of EUR 0.6–
2.3  per  m3  of  input  slurry  [  594,  Agro  Business  Park  2011  ].  From  the  Netherlands,  for  a 
capacity  of  4–100 m3/h,  investment  costs  are  reported  to  be  over  EUR 100 000  and  operating 
costs at least EUR 3.48/m3 for an annual treated quantity of 5 000 m3 (see Table 4.176). 

Intensive Rearing of Poultry or Pigs 

577 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
Local  restrictions  on  nutrient  supply  for  agriculture  can  force  the  use  of  systems  that  reduce 
transport costs by means of reduced volumes to be transported. See also Section 4.12.2.1. 

Example plants 
The technique itself is known and widely used in the industry, in waste water treatment, and in 
biogas plants. In Denmark, five units, mobile or fixed, are in use for the separation of pig slurry; 
another three units are reported to be in operation in Spain. The system is widely used in France, 
combined with biological treatment (aerobic and anaerobic) and for on-farm filtration.  

Reference literature 
[ 222, Denmark 2010 ] [ 594, Agro Business Park 2011 ] [ 596, Denmark 2009 ] 

4.12.2.4 

Coagulation-flocculation  

Description 
Coagulation-flocculation is not a separation treatment in itself; it is a chemical pretreatment that 
improves  the  subsequent  mechanical  solid-liquid  separation  of  the  slurry.  Multivalent  cations 
(e.g. Al2(SO4)3, FeCl3) and/or polymer flocculants (e.g. polyacrylamide, chitosan) are added to 
the slurry in order to achieve particle aggregation.  

Flocculant  agents  aggregate  suspended  particles  into  larger  particles  whose  size  and  other 
physical properties make them easy to separate from the liquid fraction. The addition is done in 
a small mixer tank, to achieve a satisfactory particle aggregation, before mechanical separation 
in a screw press, band filter, or decanter-centrifuge system. Prior to flocculation, a pretreatment 
step may be needed (e.g. by a  filter belt press to remove 1–2 % of the dry  matter content) in 
order to avoid the risk of clogging during the process and to lower the required consumption of 
chemicals. The aggregated clumps can be removed by sedimentation, filtration or flotation. 

A schematic representation of the coagulation-flocculation process is shown in Figure 4.84. 

Source: [ 223, Denmark 2010 ] 

Figure 4.84:  Schematic  representation  of  a  coagulation-flocculation  pretreatment  for  slurry 

separation  

578 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

If  both  additives  are  used,  the  multivalent  ion  is  added  first  to  the  slurry.  Several  minutes  of 
slow stirring are necessary to ensure homogeneous distribution of ions and dry matter and for 
charge  neutralisation  and  coagulation  to  occur.  Afterwards,  the  polymer  is  slowly  added  in 
small doses during vigorous stirring, followed by slow stirring, which is necessary for polymer 
bridging  and  patch  flocculation  to  occur.  The  stirring  conditions  applied  by  the  impeller  (i.e. 
time and speed) have a large impact on the formation of the aggregates; too slow stirring causes 
the aggregates to be non-uniform and unstable with a low particle catchment, while too  much 
stirring causes the aggregates to be destroyed [ 594, Agro Business Park 2011 ]. 

Achieved environmental benefits 
The technique can significantly increase the efficiency of the separation of organic matter and 
nutrients in the solid fraction compared with  other solid-liquid separation techniques. See also 
Section 4.12.2.1. The liquid fraction resulting from a mechanical separation treatment which is 
enhanced  by  chemical  flocculation  contains  very  low  levels  of  phosphorus  and has  a  low  dry 
matter  content  (e.g.  about  1 %)  which  allows  a  fast  infiltration  of  slurry  into  soil  after 
landspreading and, therefore, NH3 emissions to air are reduced. 

Cross-media effects 
Electrical  energy  is  needed  to  run  the  pretreatment  (coagulation-flocculation),  with  associated 
indirect emissions. The environmental and health consequences of emission of flocculants to the 
environment,  when  applied  to  land,  have  not  been  fully  investigated.  The  monomers  of 
polyacrylamide  (PAM),  used  in  most  slurry  separation  studies,  can  be  toxic,  and  potentially 
carcinogenic. It has been shown that PAM degradation is rather limited in soil; it accumulates in 
the  environment,  does  not  degrade  in  the  biogas  production  process,  and  easily  dissolves  in 
water, making it difficult to trace [ 527, Hamelin et al. 2010 ].  

On the other hand, the results of a study carried out on separated slurry products report the risk 
to  be  minimal  if  a  biological  post-treatment  is  applied,  since  PAM  is  degraded  in  biological 
processes without acrylamide accumulation [ 594, Agro Business Park 2011 ]. 

Environmental performance and operational data 
The characteristics of the treated  fractions are shown in  Table 4.180, for typical pig slurry, in 
Denmark and in Finland. 

Table 4.180:  General  characteristics  of  the  incoming  slurry  and  the  produced  fractions  after  a 

mechanical separation process including flocculation  

Treated matter 

Input 
Separated liquid fraction  
Separated solid fraction  
Source: [ 223, Denmark 2010 ] [ 447, Finland 2013 ] 

Dry 
matter 
(%) 
5.0 
1.0–1.5 
30 

Total N 
(kg/t) 

3.78–4.0 
1.8–2.9 
8.6–11.0 

Total P 
(kg/t) 

1.0–1.1 
0.1–0.3 
7.0–7.9 

In  Denmark,  the  proportion  of  total  nitrogen  in  the  dry  matter  fraction  after  separation  with 
flocculation  and  a  screw  press  is  equal  to  27 %.  The  respective  proportion  of  phosphorus  is 
reported  to  be  55 %  [  223,  Denmark  2010  ].  In  Finland,  a  flocculation-enhanced  separation 
consisting  of  a  belt  filter  and  a  screw  press  removes  from  the  raw  slurry  almost  50 %  of  the 
nitrogen and more than 90 % of  the phosphorus [ 447, Finland 2013 ]. Additional operational 
data from the Netherlands are also presented in Table 4.176 (see Section 4.12.2.1). 

The  process  is  reported  to  be  very  sensitive  to  the  polyacrylamide  concentration;  an  increase 
from  120 mg/kg  to  140 mg/kg  is  capable  of  almost  tripling  the  total  dry  matter  of  the  solid 
fraction,  but  increases  the  ammonia  and  organic  contents.  As  a  result,  the  use  of  a 

Intensive Rearing of Poultry or Pigs 

579 

 
 
 
 
 
 
 
 
 
Chapter 4 

polyacrylamide  concentration  greater  than  120 mg/kg  is  not  recommended  where  further 
anaerobic treatment is required [ 203, ADAS 2005 ]. 

Energy  consumption  for  the  application  of  this  pretreatment  (coagulation-flocculation)  in 
combination  with  sieve  separation  treatment  is  reported  to  be  in  the  range  of  0.7 kWh  to 
2.0 kWh  per  tonne  of  manure.  In  a  combined  system  in  Finland,  consisting  of  a  filter  belt, 
flocculation  and  a  screw  press,  the  energy  requirement  is  reportedly  around  3 kWh  per  m3  of 
treated  manure  [  447,  Finland  2013  ].  Flocculation  is  often  used  in  combination  with  screw 
presses. 

Technical considerations relevant to applicability 
The  technique  is  generally  applicable  to  all  types  of  slurry.  The  use  of  polyacrylamide  as  a 
flocculant may not be applicable due to the risk of acrylamide formation. 

Economics 
From  Denmark,  a  cost  of  EUR 20 000  is  reported  for  each  tonne/hour  of  capacity,  for  the 
application  of  coagulation-flocculation  in  combination  with  a  sieve  separator,  which  means 
approximately  EUR 140 000  for  a  system  with  a  capacity  of  7 tonnes  per  hour.  The  annual 
operating  costs  have  been  calculated  as  EUR 1.3  per  treated  tonne.  From  other  sources, 
operating  costs  are  reported  as  EUR 0.8  per  tonne  of  input  slurry,  and  the  investment  costs 
around  EUR 50 000  [  594,  Agro  Business  Park  2011  ].  From  Finland,  the  annual  cost  of 
polymers  for  flocculation  is  reported  to  be  EUR 3 000  for  treating  6 000  tonnes  of  slurry  per 
year [ 447, Finland 2013 ]. The labour demand in Denmark is estimated at approximately 0.25 h 
per working day. 

Driving force for implementation 
Sedimentation  and  separation  are  enhanced.  A  higher  efficiency  of  mechanical  separation 
techniques  is  achieved  by  modification  of  the  particle  properties,  especially  for  separating 
particles  belonging  to  the  smallest  particle  fraction.  The  sediment  of  the  flocculation  and  the 
solids  from  the  subsequent  mechanical  separation  treatment  can  be  dried  or  further  separated 
(e.g. using a screw press) into a solid fraction that contains most of the phosphorus from the raw 
slurry. The costs of manure storage, transport and application are reduced, which are key factors 
in areas with intensive livestock production. See also Section 4.12.2.1. 

Example plants 
The  technique  is  relatively  well  known  and  is  widely  used  for  waste  water  and  sewage 
treatment.  It  is  estimated  that  in  2009  there  were  between  30  and  40  units  in  operation  in 
Denmark  for  the  separation  of  slurry  with  chemical  precipitation  by  coagulation-flocculation, 
most of which are for pig slurry. In 2013 in Finland, this technique was in use on two pig farms 
and one dairy farm. The technique is also applied in France and Spain.  

Reference literature 
[ 203, ADAS 2005 ] [ 223, Denmark 2010 ] [ 447, Finland 2013 ] [ 527, Hamelin et al. 2010 ] 
[ 594, Agro Business Park 2011 ] [ 447, Finland 2013 ] 

4.12.2.5 

Sieve separation  

Description 
Sieve separators may be static (inclined), vibrating or rotating (drum). The liquid slurry flows 
through a screen of a specified pore size, which allows only solid particles smaller in size than 
the openings to pass through,  and is drained off. Sieve separation is used as a pretreatment in 
order to avoid sedimentation during slurry storage, as a conditioning process before pumping, or 
in combination with more efficient separation systems. 

In vibrating sieves, slurry is fed onto a mechanically vibrated, perforated screen so that a liquid 
fraction  drains  through.  In  inclined  sieves,  slurry  flows  down  a  sloping  wedge-wire  screen 

580 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
designed so that a liquid fraction drains through. In drum sieves, slurry is squeezed through a 
large perforated metal cylinder by a pair of rollers. The material flows through the inside and 
the liquid passes through the drum. Eventually, the drum can be mounted with a fibre cloth on 
the outside to optimise the separation. An example of a rotating (drum) sieve separator is given 
in Figure 4.85. 

Chapter 4 

Source: [ 594, Agro Business Park 2011 ] 

Figure 4.85:  Illustration of a rotating (drum) sieve separator used for slurry  

Achieved environmental benefits 
The  separation  of  the  initial  nitrogen  and  phosphorus  content  of  the  slurry  into  two  fractions 
(liquid  and  solid)  allows  a  reduction  of  the  problems  related  to  a  nutrient  surplus,  i.e. 
phosphorus accumulation and nitrate leaching to water. See also Section 4.12.2.1. 

Cross-media effects 
See Section 4.12.2.1.  

Environmental performance and operational data 
This  type  of  separator  generally  works  better  for  slurry  with  a  low  solids  content  (< 2 %).  A 
compromise  between  sieve  size,  separation  performance  and  risk  of  clogging  is  normally 
selected. Indeed, sieve clogging is one of the most common problems of static screens. This risk 
is lower in vibrating sieves due to the vibration. If the flow is too high, a large amount of water 
can  remain  in  the  solid  fraction.  On  the  other  hand,  such  devices  need  a  constant  supply  of 
slurry to prevent the particles drying out.  

The  separation  efficiency  for  drum  filters,  expressed  as  a  proportion  of  the  solid  fraction,  is 
reported  to  be:  nitrogen 20 %,  phosphorus  30–55 %,  total  volume  25–27 %,  and  dry  matter 
12 %. An example of drum separation applied to pig slurry is presented in Table 4.181. 

Table 4.181:  Example of pig slurry separated with a drum sieve 

Dry matter 
(%)  
4.9 
Untreated slurry 
10.4 
Solid fraction 
Liquid fraction 
2.9 
Source: [ 594, Agro Business Park 2011 ] 

Total N 
(kg/t) 
5.0 
5.3 
4.7 

NH4 
(kg/t) 
3.5 
3.5 
3.4 

P 
(kg/t) 
1.0 
1.4 
0.8 

K 
(kg/t) 
3.5 
3.8 
3.3 

Drum filtration is often used in combination with chemical flocculation. The drum sieve often 
has  a  lower  capacity  compared  to  a  centrifuge,  but  it  has  fairly  good  separation  efficiency  in 

Intensive Rearing of Poultry or Pigs 

581 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

relation to its low investment cost. The energy consumption for a drum sieve is reported to be 
equal to 1 kWh/m3 of slurry. Additional operational data are presented in Table 4.176. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
Investment  costs  are  reported  to  be  EUR 3 500–8 000  for  a  static  sieve,  EUR 15 000  for  a 
vibrating sieve and EUR 25 000 for a drum sieve (with a capacity of 2–3 m3/h). The operating 
costs for the drum sieve are reported as EUR 0.35 per m3 of slurry. 

For a capacity of 10–20 m3/h, investment costs ranging between EUR 10 000 and EUR 30 000 
are reported from the Netherlands, with operating costs of at least EUR 0.81/m3 for an annual 
treated capacity of 5 000 m3 (see Table 4.176). 

Driving force for implementation 
See Section 4.12.2.1.  

Example plants 
Several plants are reported to exist, with sieve separators accounting for more than 40 % of the 
total slurry separation systems in use on farms [ 594, Agro Business Park 2011 ]. 

Reference literature 
[ 594, Agro Business Park 2011 ] 

4.12.2.6 

Filter presses  

Description 
Most filter-press separators are screen-type devices with a large variety of designs in use. The 
main presses are as follows: 

 

 

Rotary press: Slurry is squeezed through a pair of curved perforated screens by rotating 
rollers  and  brushes.  The  liquid  fraction  passes  through  the  screens  as  the  solid  fraction 
advances within the channel. The solid material continues to dewater as it travels through 
the channel, eventually forming a cake near the outlet of the press. The frictional force of 
the  slow-moving  screens,  coupled  with  the  controlled  outlet  restriction,  results  in  the 
extrusion  of  a  dry  cake.  The  use  of  a  polyelectrolyte  is  normally  included,  in  order  to 
enhance the separation efficiency.  

Filter  belt:  Slurry  is  fed  onto  a  perforated,  moving  belt  and  it  is  pressed  between 
constantly turning rollers, and thereby, the liquid part passes through the filter. The filter 
cake is continuously removed as the belt rotates, so that the raw slurry loading area and 
solid  fraction  unloading  area  change  over  and  are  continuously  cleaned.  Often  the  belt 
separator is followed by a screw pressing unit, to further increase the dry matter content 
in the fibre fraction.  

A schematic representation of a filter-pressing separator is given in Figure 4.86. 

582 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

L = Liquid fraction. 
S = Solid fraction. 
Source: [ 594, Agro Business Park 2011 ] 

Figure 4.86:  Schematic representation of a filter-pressing separator  

Achieved environmental benefits 
The  separation  of  the  initial  nitrogen  and  phosphorus  content  of  the  slurry  into  two  fractions 
(liquid  and  solid)  allows  a  reduction  of  the  problems  related  to  a  nutrient  surplus,  i.e. 
phosphorus accumulation and nitrate leaching to water. See also Section 4.12.2.1. 

Cross-media effects 
See Section 4.12.2.1. 

Environmental performance and operational data 
Polyelectrolytes  (for  coagulation-flocculation)  are  normally  applied  in  combination  with  filter 
pressing,  in  order  to  the  enhance  separation  efficiency.  In  this  case,  attainable  separation 
efficiencies  of  30 %  total  Kjeldahl  nitrogen  and  70 %  phosphorus,  in  the  solid  fraction,  are 
reported. The dry matter of the separated solid fraction is in the range of 25–35 %. For a rotary 
presses, the energy consumption is reported to be 0.5 kWh per m3 of input slurry.  

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. 

Economics 
Investment  costs  are  reported  to  be  in  the  range  of  EUR 25 000–125 000,  depending  on  the 
dimensions and type of separator. For a band filter (filter belt), operating costs are reported to be 
equivalent to EUR 1.5 per tonne of input slurry. 

From the Netherlands, investment costs for a system with a capacity of 4–30 m3/h are reported 
to be over EUR 70 000, with operating costs of at least EUR 3.11 per m3, for an annual treated 
capacity of 5 000 m3 (see Table 4.176). 

Driving force for implementation 
See Section 4.12.2.1. 

Example plants 
At least 100 plants are reported to exist. 

Reference literature 
[ 594, Agro Business Park 2011 ] 

Intensive Rearing of Poultry or Pigs 

583 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.12.3 

Biological treatment of slurry  

4.12.3.1 

Aerobic digestion (aeration) of slurry  

Description 
Aerobic digestion consists of the biological decomposition of organic matter to carbon dioxide 
and water by exposing organic matter to biological growth under aerobic conditions. Sufficient 
oxygen  is  dissolved  in  liquid  manure  through  aeration  to  stimulate  the  growth  of  aerobic 
bacteria.  Heat  released  by  the  decomposition  of  the  organic  matter  results  in  thermophilic 
temperatures  inside  the  reactor  above  45 °C  and  up  to  75 °C.  Under  thermophilic  conditions, 
only the biodegradable organic matter can be removed, and nitrogen is conserved in the liquid 
phase.  The  technique  may  thus  be  combined  with  another  stage  for  the  removal  of  nitrogen 
through nitrification-denitrification. 

The  main  variables  concerning  aerobic  digestion  are  the  retention  time,  the  aeration  intensity 
and  whether  the  process  is  continuous  or  carried  out  in  batch  mode.  Variations  in  the  slurry 
characteristics  and  incomplete  mixing  can  considerably  reduce  the  treatment  efficiency  and 
consistency. 

Stored  slurry  is  aerated  by  means  of  submerged  or  floating  aerators  in  a  continuous  or  batch 
process (see also Section 2.7.2.). The residue can be used as fertiliser (composted or not) after 
concentration. 

Achieved environmental benefits 
Aerobic  digestion  produces  an  odourless  product  with  a  lower  pathogen  content,  due  to  the 
biological  oxidation  of  volatile  organic  compounds  and  the  associated  heat  generation  and 
thermophilic  temperatures of  the  process.  Up to  60 %  of the organic  load  (COD)  is removed, 
depending on the level of aeration. Organic matter is also stabilised.  

Cross-media effects 
Associated  cross-media  effects  are  linked  to  the  effort  of  changing  the  conditions  from 
anaerobic to aerobic by aeration, which is energy-intensive. The temperature increase generated 
by  aeration  and  the  possible  presence  of  anaerobic  zones  lead  to  a  high  risk  of  increased 
methane  emissions,  compared  to  a  well-covered  conventional  anaerobic  storage.  Moreover,  if 
anaerobic/aerobic transition zones arise as a result of the process, N2O emissions will occur. 

Inadequate control of the aeration process can lead to increased releases of sulphides and other 
odorous  organic  compounds  when  anaerobic  conditions  resume.  Furthermore,  gaseous 
emissions  may  occur  in  the  form  of  ammonia  when  the  aeration  intensity  is  too  high,  and  as 
methane and nitrous oxide at low pH levels and in other suboptimal conditions.  

When aerobic digestion is combined with nitrification-denitrification, ammoniacal nitrogen may 
be  partly  (or  completely)  removed  from  the  manure  and  emitted  into  the  air  (as  nitrogen), 
resulting  in  a  loss  of  fertiliser  value.  Technical  assistance  to  the  farmer  may  be  necessary  for 
running the aerobic treatment installation properly [ 43, COM 2003 ]. 

If  additives  are  used  for  the  sedimentation  of  floating  substances,  the  residual  sludge  may  be 
difficult  to  dispose  of.  Aeration  requires  significant  energy  consumption,  which  is  associated 
with  indirect  emissions  for  electricity  production.  Using  this  technique  on  duck  slurry,  a 
notable quantity  of  foam  is  produced  which  has  to  be  controlled  by  means  of  biological 
additives [ 561, Flotats et al. 2004 ]. 

Environmental performance and operational data 
Batch aeration (especially at thermophilic temperatures) is better at reducing pathogen numbers 
and, in theory, is a more consistent process than continuous treatment. However, it is difficult to 
control and leads to wide variation in aeration levels. In batch treatments of a short duration, the 
rapid increase in biological activity in the first days can exceed the aeration capacity, resulting 

584 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

in  an  excessive  foam  release  and  increased  NH3  loss.  Following  an  incomplete  aerobic 
treatment, anaerobic conditions can occur in the stored slurry, with a consequent formation of 
nitrous oxide or denitrification of nitrates to nitrogen gas (N2); in this way, nitrogen losses in the 
range  of  50–70 %  are  reported  [  203,  ADAS  2005  ].  It  is  important  to  monitor  the  redox 
potential or oxygen content of the slurry closely, as partially anoxic conditions can result in the 
formation of nitrous oxide (N2O). 

The aeration of pig manure may lead to a sludge that is difficult to precipitate and a dosage of 
chalk may then be necessary. Temperature is an important factor, particularly in colder regions 
where  it  may  be  difficult  to  maintain  the  required  aeration  level  during  winter.  However, 
intermittent  aeration  (15 minutes/hour),  in  combination  with  an  achieved  BOD5  reduction  of 
about 50 %, results in good deodorisation and very limited sludge production [ 506, TWG ILF 
BREF 2001 ]. 

Aeration requires a high amount of energy, but the levels vary with the equipment applied and 
the  size  of  the  installation.  Air  is  added to  the system  at  an  approximate rate  of  1.5 kg  O2/kg 
organic matter oxidised. Energy consumption also depends on the composition of the slurry, in 
terms  of  BOD  and  nitrogen  (when  nitrification  is  allowed).  Levels  of  10–38 kWh  per  m3  of 
aerated  liquid  manure  have  been  reported.  Good  management  of  the  aeration  frequency  may 
reduce the energy consumption, but will lead to ammonia volatilisation.  

Technical considerations relevant to applicability 
The technique can be applied on pig slurry, and other types of liquid manure such as duck slurry 
or the liquid fraction coming from the mechanical separation of slurry [ 259, France 2010 ]. 

Due to cross-media effects, the technique is only applicable when pathogen and odour reduction 
is important prior to landspreading. In cold climates, it may be difficult to maintain the required 
level of aeration during winter. 

Economics 
Investment  costs  for  slurry  treatment  plants  operated in  Brittany,  France,  are  reported  to  vary 
between EUR 45 and EUR 53 per m3 of annual capacity [ 203, ADAS 2005 ]. The total costs, 
including investment and operating costs, are reported to vary greatly, depending on the level of 
treatment and the annual volumes involved. Costs for an aerobic treatment without mechanical 
separation,  with  an  annual  capacity  of  4100 m3,  are  reported  to  be  about  EUR 8.2 per  m3,  in 
Brittany,  France.  In  cases  where  a  mechanical  separation  stage  is  coupled  with  the  aerobic 
treatment plant, total costs were reported to range from EUR 10.7 per m3 for the smaller plants 
(5 600 m3 slurry per year) to EUR 7.6 per m3 for the larger plants (16 300 m3 slurry per year). It 
is  also  reported  that  in  France  the  on-farm  use  of  aerobic  treatment  receives  incentives  of 
financial support [ 203, ADAS 2005 ]. 

In the UK, the typical net cost of aeration was found to be around EUR 4.7 per m3 of pig slurry 
(EUR  1  =  GBP  0.88).  Costs  reported  by  Finland  ranged  from  EUR 0.7–2  per  m3  of  aerated 
liquid manure in a storage tank to EUR 2.7–4 per m3 of aerated liquid manure in a separate tank.  
In France, the cost of duck slurry aeration is estimated as EUR 2.2 per m3 of slurry, including 
the cost of the anti-foam treatment [ 370, Franck et al. 2003 ].  

Driving force for implementation 
A  homogenised  product  with  reduced  odour  is  more  convenient  for  landspreading.  Pathogen 
dissemination is also avoided. The resulting aerated liquid manure can be used for the flushing 
of manure gutters, tubes or channels to reduce ammonia emissions from housing.  

Example plants 
This technique is applied in a number of Member States, e.g. about 90 farms are reported in the 
UK and 20 in Finland. In Spain, the technique is applied to large facilities treating an average of 
55 000–65 000 tonnes of pig slurry annually [ 595, Agro Business Park 2011 ]. 

Intensive Rearing of Poultry or Pigs 

585 

 
 
 
 
 
 
 
 
 
Chapter 4 

Community facilities for aerobic digestion form an integral part of the NVZ Action Programme 
in parts of Brittany, France and Flanders, Belgium. In 2005, around 190 aerobic treatment units 
were reported to be in operation in Brittany, France [ 203, ADAS 2005 ].  

Reference literature 
[ 26, Finland 2001 ] [ 43, COM 2003 ] [ 203, ADAS 2005 ] [ 259, France 2010 ] [ 370, Franck 
et al. 2003 ] [ 409, VITO 1997 ] [ 506, TWG ILF BREF 2001 ] [ 561, Flotats et al. 2004 ] [ 594, 
Agro Business Park 2011 ] [ 595, Agro Business Park 2011 ] 

4.12.3.1.1 

Aerobic biological manure processing in a serial tank configuration  

Description 
This technique represents a special configuration of an aerobic digestion process in combination 
with specific features. The input material is the homogeneous liquid fraction with a dry matter 
content of about 1 % that results from an enhanced solid separation step prior to treatment. This 
step  combines  techniques  of  mechanical  separation  (band  filter  and  screw  press)  and 
flocculation (see Section 4.12.2.4).  

The liquid fraction of  the  slurry is continuously pumped into an aerated continuous-flow tank 
system  consisting  of  six  treatment  tanks  connected  in  series.  The  design  of  the  serial  reactor 
configuration aims to enhance the treatment efficiency and stability, to achieve improved odour 
reduction and to provide more advanced process control. 

The initial stage of the process is biological based on an amendment of an enriched soil microbe 
population. Under aerobic conditions, liquid manure is converted to  an odourless effluent  and 
organic  molecules  to  a  form  that  is  easy  to  precipitate  and  separate.  Rotameters  are  used  to 
regulate aeration in each tank using high-pressure blowers through membrane diffusers for fine 
bubble  aeration.  Limited  aeration  is  applied  in  a  system  in  order  to  keep  nitrogen  in  the 
ammonia  form,  preventing  nitrate  formation.  Feedback  effluent  from  the  last  tank  is  used  to 
inoculate the first tank.  

The treatment tanks are covered and insulated.  Ammonia released during aeration is collected 
and led to a sulphuric acid scrubber. During the biological treatment, the process is producing 
heat  (the  temperature  in  the  insulated  treatment  tanks  increases  above  40 °C)  that  can  be 
recovered by a heat pump  to heat the farm building. The biologically treated liquid manure is 
used as nitrogen fertiliser. The separated solid fraction can be used as concentrated phosphorus 
fertiliser on the field, composted or used for biogas production. 

Achieved environmental benefits 
The final effluent after the treatment (enhanced solid separation and biologically treated liquid 
manure)  is  completely  odourless  and  considerably  lower  in  pathogenic  organisms.  Due  to  the 
consistently low level of dry matter content, the treated liquid fraction can easily infiltrate into 
soil, thus reducing NH3 emissions to air.  

Cross-media effects  
Electrical energy is required to operate the system.  

Environmental performance and operational data 
Data  are  reported  from  a  pig  farm  in  Finland  with  an  annual  manure  production  of  about 
2 200 m3  (about  6  m3  of  slurry  per  day)  that  applies  a  combination  of  an  enhanced  solid 
separation  stage  and  aerobic  biological  treatment  in  tanks  connected  in  series.  The  quantities 
and composition of the different streams are summarised in Figure 4.87. 

586 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 398, Finland 2013 ] 

Figure 4.87:  Mass balance and composition of the different streams resulting from a combination 
of a mechanical separation stage with flocculation and a biological aeration treatment 
with serial tank configuration 

The  energy  use  for  the  biological  aeration  treatment  is  reported  as  5.83 kWh per  m3  of  raw 
manure. 

Technical considerations relevant to applicability 
No restriction is reported for the application on either existing or new farms. 

Economics 
Depending  on  the  size  and  the  system,  the  costs  of  an  installation  consisting  of  the  complete 
biological  treatment  system  (including  the  air  scrubber)  may  vary  from  EUR 80 000  to 
EUR 160 000  when  the  system  is  combined  with  an  enhanced  separation  stage  prior  to 
treatment. The energy cost is estimated to be around EUR 0.88 per tonne of treated manure. In 
the case of heat recovery by the application of heat exchange technology (35  °C → 4 °C), the 
energy production can have a value of EUR 4.5/tonne of manure.  

Driving force for implementation 
Pathogen and odour reduction can be key factors in areas with intensive livestock production.  

Example plants 
In  Finland,  three  farms  applying  a  combination  of  an  enhanced  solid  separation  stage  and 
biological aeration treatment are in operation.  

Reference literature 
[ 224, Finland 2010 ] [ 398, Finland 2013 ] [ 621, Alitalo et al 2011 ] 

4.12.3.2 

Nitrification-denitrification of slurry  

Description 
Biological conversion of ammoniacal nitrogen is performed in two main steps: nitrification and 
denitrification.  In  the  nitrification  stage,  the  ammoniacal  nitrogen  is  oxidised  into  nitrate  by 
nitrifying bacteria which use an inorganic carbon source for growing (autotrophic organisms). 
This process takes place under aerobic conditions, in the presence of free oxygen and agitation. 

Intensive Rearing of Poultry or Pigs 

587 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

In  the  denitrification  stage,  the  nitrate  is  biologically  reduced  to  gaseous  nitrogen  (N2). 
Denitrification takes place under anoxic conditions (i.e. absence of free dissolved oxygen) and 
in the presence of organic carbon by denitrifying bacteria (heterotrophic organisms).  

The  activated  sludge  and  treated  liquid  flow  from  the  aeration  basin  into  another  (secondary) 
settling basin. In this basin, the sludge settles, with part of it being reused in the aeration basin. 
The  mass  of  separated  solids  is  captured  in  a  storage  basin  to  concentrate  it  further.  This 
concentrated  residue  can  be  used  as  fertiliser  (sometimes  it  is  composted  first).  The  typical 
treatment system has two different outputs: treated liquid effluent and biological sludge. 

Achieved environmental benefits 
Ammoniacal nitrogen is removed from the slurry in the form of inert N2 gas. Nitrogen removal 
can  improve  the  manageability  of slurry, especially in areas with  a nitrogen surplus. Odour is 
reduced compared to untreated slurry. COD reduction occurs as a function of aeration.  

With  the  application  of  a  biological  treatment,  emissions  of  greenhouse  gases  (methane  and 
nitrous  oxide),  as  well  as  ammonia  emissions,  are  reported  to  be  reduced,  compared  with 
manure storage alone (based on 6 months storage before spreading) [ 597, Loyon et al. 2007 ].  

Cross-media effects 
Energy  consumption  is  increased  in  comparison  with  a  solid-liquid  separation,  due  to  the 
operation  of  aeration  and  pumps.  A  higher  quantity  of  sludge  is  produced  (from  microbial 
activity) compared with anaerobic treatment systems. The fertilising value of slurry is decreased 
when  there  is  no  nutrient  surplus,  and,  therefore,  nitrogen  has  to  be  provided  by  mineral 
fertilisers.  Mineral  nitrogen  production  is  very  energy-intensive  and  consumes  a  lot  of  fossil 
energy sources.  

Another disadvantage is that part of the nitrogen emitted into the air is not in the form of N2 but, 
potentially, NH3 or N2O, if the process is not well managed. The design and proper functioning 
of this technique are very important to prevent environmental problems being transferred from 
water to air media. 

Environmental performance and operational data 
The  maximum  attainable  nitrogen  removal  efficiency  is  up  to  70 %  of  the  total  N  in  the 
untreated slurry (the rest of the nitrogen will be separated in the solid fraction, assimilated by 
the biological sludge, or will remain in the liquid effluent). If the nitrogen removal efficiency is 
evaluated on the liquid phase, it may be higher than 90 %. 

Aeration  is  one  of  the  main  operational  parameters  during  nitrification,  with  theoretical 
requirements of around 4.6 kg O2 per kg of nitrogen. The organic load during denitrification is 
required to be approximately 6.0 kg COD per kg of nitrate-N. Pretreatment, such as separation 
and anaerobic digestion, may constrain the availability of biodegradable organic carbon during 
denitrification. 

A prior mechanical separation treatment of slurry can reduce the oxygen demand, and thereby 
energy costs, and avoid possible problems during the process due to the high sludge production 
level, sedimentation and clogging of the equipment. The optimal process temperature is 35 °C.  

The results of a study comparing a nitrification-denitrification treatment (intermittent aeration) 
to a conventional slurry storage of 6 months before spreading report a reduction of 30–52 % in 
ammonia emission for a biological system combined with mechanical separation (centrifuge or 
screw  press).  A  higher  ammonia  emissions  reduction  (68 %)  is  reported  for  a  combination 
without  separation,  consisting  of  storage,  biological  treatment  and  decanting.  A  reduction  of 
greenhouse gas emissions (CH4 and N2O) of about 55 % (calculated as CO2 equivalent) is also 
reported for any type of biological treatment plant [ 597, Loyon et al. 2007 ]. 

588 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
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The technique requires the control of a number of operating parameters, such as composition of 
the effluent, applied loads, bacteria populations, and temperature. The process is sensitive to the 
presence  of  toxic  substances  and  other  substances  which  can  inhibit  microbial  activity.  The 
resulting sludge needs proper management. 

The  biological  process  needs  continuous  operation.  It  is  necessary  to  ensure  that  slurry  has 
sufficient inorganic carbon for the nitrification stage, and organic carbon for the denitrification 
process.  During  the  process,  the oxygen  consumption  to  oxidise  organic  matter in  the  aerobic 
stage  should  be  carefully  controlled.  Intensive  aeration  to  remove  excess  nitrogen  from 
livestock slurries has been shown to increase N2O emissions by up to 19 % of the total N in pig 
slurry [ 443, Chadwick et al. 2011 ]. 

The energy consumption depends on the composition of the stream to be treated, the efficiency 
of transferring oxygen of the aeration equipment, the operational conditions applied, etc. Values 
in  the  range  of  10–25 kWh/m3  are  reported,  in  comparison  with  an  effective  solid-liquid 
separation, for which the energy consumption can be less than 10 kWh/m3 [ 594, Agro Business 
Park 2011 ]. 

Data are shown below for a farm in Brittany with 250 sows and 5 000 finishers per year with a 
yearly manure production of about 5 000 m3. The solids are sieved from the liquid. The results, 
in terms of mass balance, quantities and composition of the products for mechanical separation 
and biological treatment at this specific farm are summarised in Table 4.182 and Table 4.183. 

Table 4.182:  Mass balance of the mechanical separation and biological treatment of pig slurry 

Component 

In 

Manure 

Mass 
Dry matter 
Susp. solids 
Water 
COD 
BOD 
N 
P2O5 
K2O 
Cl 
NB: NI = no information provided. 

1 000 
56 
48 
944 
52 
6.6 
4.4 
3.3 
3.5 
1.9 

Separated 
solid 
fraction 
57 
20 
NI 
37 
NI 
NI 
0.5 
0.6 
0.2 
NI 

Out 

Sludge 

Effluent 

Total 

Calculated 
emissions 
to air 

260 
21 
NI 
239 
NI 
NI 
0.7 
2.0 
0.9 
NI 

580 
5 
0.3 
575 
1 
0.05 
0.05 
0.4 
1.8 
0.8 

897 
46 
NI 
851 
NI 
NI 
1.25 
3 
2.9 
NI 

103 
10 
NI 
93 
NI 
NI 
3.15 
0.3 
0.6 
NI 

Source: [ 409, VITO 1997 ] 

Table 4.183:  Composition of manure and products in g/kg 

Component 

Manure 

56 
Dry matter 
48 
Susp. solids 
944 
Water 
52 
COD 
6.6 
BOD 
4.4 
N 
3.3 
P2O5 
3.5 
K2O 
Cl 
1.9 
NB: NI = no information provided. 

Source: [ 409, VITO 1997 ] 

Separate
d solid 
fraction 
350 
NI 
650 
NI 
NI 
8.1 
9.9 
3.4 
NI 

Influent to 
secondary basin 

Sludge 

Effluent 

39 
29 
961 
36 
6.1 
4.2 
2.9 
3.4 
1.9 

80 
NI 
920 
NI 
NI 
2.7 
7.5 
3.4 
NI 

8.5 
0.5 
991.5 
1.8 
0.09 
0.08 
0.6 
3.0 
1.4 

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589 

 
 
 
 
 
 
 
 
 
Chapter 4 

The  sieve  removes  a  small  mass  with  a  relatively  high  DM  content  and  phosphate  level.  The 
solid fraction contains about 35 % dry matter and can be stacked. The tables show that much of 
the  nitrogen  (72 %)  is  lost  into  the  environment  due  to  nitrification  and  denitrification.  Only 
about 1 % of the nitrogen appears in the effluent. Most of the P2O5 is retained in the activated 
sludge. It should be noted that the information source did not report if BOD was measured over 
5, 7 or 20 days. 

Technical considerations relevant to applicability 
The technique is not applicable to new plants/farms due to the cross-media effects. In existing 
farms, it is only applicable when the removal of nitrogen is necessary due to there being limited 
land available for manure application. The applicability is limited by the high investment costs 
and the operating costs for the electrical energy required for aeration.  

Proper  process  control  is  essential,  but  may  be  difficult  on  farm;  outsourcing  could  thus  be  a 
solution. Particularly in colder areas, the minimum winter temperatures required for sufficient 
biological activity to occur may be difficult to maintain. Ammonia levels can rise and lead to 
inhibited nitrification. 

With  more  solid  types  of  manure,  such  as  the  manure  of  finishers,  large  amounts  of  residual 
sludge can be expected. In practice, this limits the application of this technique to the treatment 
of sow manure with a DM content of no more than 6 %. A mechanical separation stage can be 
utilised to reduce the dry matter content. 

Concerning  the  poultry  sector,  the  technique  is  theoretically  suitable for  duck  slurry,  but  the 
volume  needed  and  the  treatment  costs  are  still  not  economical  for  its  common  on-farm  use 
[ 259, France 2010 ]. 

Economics 
For a unit with a capacity to treat 15 000 m3 of pig slurry per year, the reported investment costs 
are EUR 240 000–300 000. For a capacity of 50 000 m3 of pig slurry per year, the investment 
costs are EUR 700 000–1 200 000.  

Operating costs are dependent on the composition of the manure to be treated and are reported 
to  be  in  the  range  of  EUR 0.5–3.0  per  tonne  of  slurry  [  594,  Agro  Business  Park  2011  ] 
[ 561,  Flotats  et  al.  2004  ].  In  the  case  when  solid-liquid  separation  is  carried  out  prior  to 
nitrification-denitrification,  and  the  solid  fraction  is  composted  as  a  post-treatment,  costs  can 
increase to EUR 2.5–5.2 per tonne. 

Driving force for implementation 
In areas with a nitrogen surplus, the economic investment and operating costs for the removal of 
nitrogen from slurry could be attractive, if they are lower than the costs for transportation to and 
application in areas far away where there is no nitrogen surplus.  

Example plants 
In Brittany, France, around 300 units are in use. About 240 farms in the region of Brittany, most 
of which is classified as a Nitrate Vulnerable Zone under the EC Nitrates Directive, have opted 
biological treatment using nitrification-denitrification (intermittent aeration) [ 597, Loyon et al. 
2007 ]. In Belgium (Flanders), Spain and the Netherlands, the technique is also widely applied [ 
595, Agro Business Park 2011 ]. 

Reference literature 
[ 259, France 2010 ] [ 409, VITO 1997 ] [ 410, Greece 2001 ] [ 443, Chadwick et al. 2011 ] 
[ 561, Flotats et al. 2004 ] [ 594, Agro Business Park 2011 ] [ 595, Agro Business Park 2011 ] 
[ 597, Loyon et al. 2007 ] 

590 

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Chapter 4 

4.12.4 

Composting of solid manure  

Composting  can  be  applied  as  a  further  treatment,  after  the  drying  of  fresh  (poultry)  manure, 
after  mechanical  separation  of  the  solid  fraction  of  slurry  or  after  the  addition  of  enough  dry 
organic material (bulking agent) to liquid manure in order to obtain a solid mixture.  

Composting installations handling  manure are subject to the  specific provisions of Regulation 
(EC) 1069/2009, concerning  animal by-products, and have to be approved in accordance with 
Article  24  of  the  Regulation.  The  requirements  applicable  to  composting  plants  regarding 
hygiene, operational parameters and standards of derived product are set out in Article 10 and 
Annex V of Regulation (EC) 142/2011. The competent authority shall only approve composting 
plants if they comply with the above-mentioned requirements. Furthermore, it has to be ensured 
that the obtained final product corresponds to the specifications set by potential buyers. 

4.12.4.1 

Composting  

Description 
Composting  is  the  controlled  aerobic  degradation  of  organic  matter.  In  the  IRPP  sector,  solid 
manure, mixed or not with vegetal organic matter, is used in the process. Aerobic conditions can 
be achieved by mechanically turning or mixing a heap or pile with a tractor loader, for example, 
to incorporate air or by more specialised equipment.  

The aim of the technique is to facilitate naturally occurring microflora to degrade cellulose and 
other  carbon  compounds  in  the  manure  to  produce  a  material  that  is  friable  and  sufficiently 
stable  for  storage  and  transport  and  that  has  a  reduced  volume.  Compost,  which  is  the  final 
product, consists of stabilised organic matter, has a low moisture content and retains most of the 
initial nutrients.  

In the initial phase of the process (decomposition), exothermic reactions produce a temperature 
increase  in  the  composting  matrix,  above  50 °C  in  the  thermophilic  temperature  range  up  to 
70 °C,  with  consequent  hygienisation  of  the  product  by  the  elimination  of  pathogens  in  the 
manure.  Aerobic  conditions  are  needed  in  order  to  enable  the  microorganisms  to  convert  the 
input  material  by  using  the  available  nutrients,  oxygen  and  water.  When  oxygen  is  depleted, 
manure heaps cool down and aeration should be restored by mechanical turning of the heap, as 
well as by forced aeration [ 528, ITAVI 2001 ]. 

In a second, curing, stage, complex organic matter is degraded and humic and fulvic acids are 
produced. The temperature slowly decreases in the mesophilic temperature range (below 40 °C) 
to  room  temperature.  The  whole  process  lasts  between  8  and  16  weeks.  Run-off  liquids  are 
collected by shafts and pumped to a tank, from where they can be recycled on the composting 
silo or windrow [ 257, France 2010 ]. 

The different composting systems are described below. 

Composting with mechanical reversal of heaps 
On  farm,  the  manure  is  usually  arranged  in  windrows  (long  heaps  with  a  trapezoidal  or 
triangular section, typically 1–3 metres high, 2–5 metres wide and of indeterminate length) and 
monitored  for  temperature  and  moisture.  The  temperature  needs  close  monitoring,  especially 
during  the  first  days.  Run-off  waters  or  slurry  can  also  be  added  to  increase  moisture.  The 
windrows are turned over and mixed periodically using conventional loading machinery (e.g. a 
bucket loader) or other available farmyard machinery (e.g. windrow turner).  

In the first week of composting, it is recommended to turn the solid manure windrow twice to 
facilitate aeration and the development of high temperatures within the windrow [ 648, DEFRA 
2011 ]. Later, reversals are necessary at intervals of 10 days to 3 weeks, in order to maintain the 
airflow in the middle of the heap. After the last reversal, it is then necessary to wait at least 3 
more weeks [ 528, ITAVI 2001 ]. 

Intensive Rearing of Poultry or Pigs 

591 

 
 
 
 
 
 
 
 
 
 
 
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Reversals have an immediate effect on the temperature. Several reversals are essential to ensure 
that all the compost has been subjected to a high temperature. The operation of reversal ensures 
homogenisation of materials, increases passive aeration, and provides the proper conditions for 
the aerobic decomposition. The period that active composting normally lasts ranges from 8 to 
12 weeks.  

Static aerated piles  
This  is  an  alternative  method,  which  uses  air  supplied  by  perforated  piping  or  a  porous  floor 
below the pile, therefore avoiding the reversal and mixing. Aeration can be forced (air is forced 
into  the  composting  material)  or  passive  (convective  movement  of  air  into  the  composting 
material). 

Composting in-vessel (with forced aeration) 
Composting  is  carried  out  in  closed,  aerated  concrete  silos/tanks  or  channels  (composting 
vessels). The bottom of these modules is equipped with a system of perforated pipes, allowing 
forced  aeration  by  blowing  air  into  the  substrate.  The  system  is  controlled  by  temperature 
sensors, allowing the aeration to be recorded and adjusted. Once the silo is charged with solid 
manure, a cover is anchored on the walls of the silo. Forced aeration is maintained for 6 weeks 
and then the silo is uncovered and emptied for the compost to mature in a heap [ 257, France 
2010 ]. Composting drums can also be used. 

Achieved environmental benefits 
The  technique  produces  an  organic  fertiliser  (compost)  with  part  of  the  original  inorganic, 
readily available nitrogen content converted to organic forms, and most of the phosphorus in a 
concentrated form (due to water evaporation). The organic matter is humified and the product is 
odourless  and  pathogen-free.  As  a  result,  during  landspreading  of  the  composted  product, 
reduced  odour  and  NH3  emissions,  and  emissions  of  nitrogen  compounds  from  leaching,  are 
expected [ 203, ADAS 2005 ] [ 257, France, 2010 ]. 

The  benefits  in  terms  of  the  fertiliser  product  obtained  depend  on  the  type  of  manure,  the 
pretreatment  technique,  the  additives,  and  on  the  composting  technique,  and  cannot  be 
quantified in a general sense.  

In  France,  the  product  of  composting  (compost  manure)  is  considered  an  organic  fertiliser, 
deodorised  and  hygienised.  It  supplies  organic  matter  to  the  ground,  and  the  organic  form  of 
nitrogen allows a gradual release to the plants. A priori, compost manure may be applied in the 
autumn and winter without risking an increase in nitrate leaching [ 528, ITAVI 2001 ]. 

Cross-media effects 
In partly aerobic conditions, such as in unsealed  manure heaps, part of the inorganic nitrogen 
(10–55 % of the nitrogen) is lost through volatilisation as ammonia emissions. N2O emissions 
-  losses  as  leachate  may  also  occur  [  624,  IRPP  TWG  2013  ].  The  nitrogen  losses 
and  NO3
reduce  the  fertiliser  value  of  the  manure,  resulting  in  the  need  for  supplementing  it  with  a 
mineral  fertiliser,  with  consequent  increased  indirect  emissions  for  its  production.  Loss  of 
carbon during composting also reduces the nutrient content of the resulting product.  

Conditions during composting imply a risk of increasing emissions of greenhouse gases, since 
aeration  leads  to  a  temperature  increase  and,  thereby,  also  to  much  higher  activity  of  the 
anaerobic bacteria. Methane emissions are very likely to occur if anaerobic zones are developed 
inside the composting mass, as are nitrous oxide emissions in the case of improper aeration of 
the  whole  manure  heap  (i.e.  anaerobic  zones  in  the  centre  imply  that  there  may  be 
aerobic/anaerobic transition zones in the compost). 

The volatilisation of nitrogen can also be reduced by means of a cover. Peat is suggested as the 
cover,  as  acid  sphagnum  peat  (Sphagnum  fuscum)  has  a  better  nitrogen-binding  capacity  than 
straw, sawdust or cutter chips for example. However, peat is a non-renewable resource and its 
extraction  leads  to  significant  emissions  of  greenhouse  gases.  On  the  other  hand,  it  is  also 

592 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

reported  that  covers  were  not  found  to  have  any  significant  effect  on  aerial  emissions  during 
composting in a study carried out in France [ 528, ITAVI 2001 ]. 

Air scrubbing systems for manure composting facilities are well tested as an additional method 
to reduce NH3 emissions from this source, but have significant costs  [ 508, TFRN 2014 ]. No 
composting installation at  the  farm scale is reported to be equipped with air cleaning  systems  
[ 595, Agro Business Park 2011 ]. 

If the heap is put on soil and not on an impermeable base, part of the nitrogen that sinks into the 
soil evaporates, and plants use part of it after the heap is removed. Depending on the amount of 
run-off, the  soil surface and  the soil type, part of the nitrogen may also leach into the surface 
waters or groundwater. 

About half of the potassium in manure may be lost due to composting. Potassium is lost only in 
run-off  water,  and  these  emissions  can  be  reduced  by  means  of  a  watertight  cover  over  the 
compost.  The  cover  prevents  the  leaching  caused  by  rainwater,  but  it  does  not  prevent  the 
liquids produced in the compost from sinking into the ground. If composting is performed in a 
barn, losses to the soil or from leaching during the composting process are non-existent. 

In  the  composting  process,  suboptimal  conditions  may  eventually  result.  Odour  emissions 
would  be  indicative  of  the  occurrence,  as  odorous  compounds  are  mostly  volatile  organic 
sulphur compounds produced under anaerobic conditions. In the case of silo composting with 
forced aeration, odours are controlled by incorporation of a neutralising product into the dry air.  
Energy  consumption  is  required,  in  particular  when  forced  aeration  is  used  for  composting. 
Water  is  needed  in  the  process  to  maintain  a  suitable moisture  content  of  the  manure  
[ 594, Agro Business Park 2011 ]. 

Environmental performance and operational data 
Composting periods may last up to 6 months or more, but can be shortened by frequent turning 
and  aeration.  The  required  operational  parameters  for  composting  using  animal  by-products 
(including manure) are specified in European Regulation 142/2011, as well as the specifications 
of  the final compost  products. The  key  operating  parameters  and transformation  requirements 
are reported below. 

 

 

 

 

 

Moisture  content  between  40 %  and  70 %  [  203,  ADAS  2005  ].  Below  30 %,  bacteria 
activity is inhibited. In general, solid manures from deep litter housing systems (broilers, 
turkeys, guinea fowl)  are not  suitable for a smooth composting process, due to the high 
dry matter content, ranging between 65 % and 80 %. The ideal dry matter content should 
be  about  40 %  to  50 %;  for  the  purpose,  moisture  (water,  slurry,  etc.)  in  sufficient 
quantity  has  to  be  added  at  the  beginning  of  composting,  at  the  time  of  building  the 
windrows. As an example, one tonne of solid manure with a dry matter content of 75 % 
requires 500 litres of water in order to reach a dry matter content of 50 %. A very moist 
mixture does not favour composting because it prevents aeration [ 528, ITAVI 2001 ].  

Oxygen supply > 0.5 mg/l. 

Porosity of the heap between 30 % and 60 % (as air-filled porosity). 

Carbon/Nitrogen ratio (C/N) in the range of 20–35.  

Temperature of the heap between 50 °C and 60 °C. Product hygienisation is ensured by 
monitoring the temperature as an indicator. In general, if the material remains at 50 °C for 
over 6 weeks, most pathogens will be destroyed (viruses, bacteria and parasites), while, at 
a  temperature  of  between  40 °C  and  50 °C  for  6  weeks,  only  parasitic  worms  are 
destroyed.  At  a  temperature  below  40 °C  for  6  weeks,  no  sanitation  occurs.  A  general 
practice 
to  30  days  
[ 528, ITAVI 2001]. Hygienisation is also achieved if the temperature is kept above 55 °C 
for 2 weeks or above 65 °C for 1 week [ 561, Flotats et al. 2004 ]. 

temperature  above  55 °C 

to  maintain 

for  25 

the 

is 

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593 

 
 
 
 
 
 
Chapter 4 

Regulation  142/2011  sets  the  minimum  temperature  (70 °C)  that  all  material  must  remain  at 
without interruption for 60 minutes. However, the competent authority may authorise the use of 
other  specific  requirements  provided  that  they  guarantee  an  equivalent  effect  regarding  the 
reduction of pathogens. 

The use of tarpaulins for covering the windrows limits odour emissions and flies, allows better 
integration of windrows in the landscape (positive psychological effect on the neighbourhood), 
provides health protection from birds and rodents, and essential protection in case of heavy rain. 
A semi-permeable geotextile cover offers the advantage of being permeable to gas and allows 
good drainage of water on the surface of the windrow [ 528, ITAVI 2001 ]. 

For  the  application  of  the  composting  technique  in  the  UK,  the  readily  available  nitrogen 
content of FYM is typically reduced from 20–25 % to 10–15 % of total N (in composted FYM) 
due to NH4-N conversion to NO3-N and organic nitrogen. Composting has a smaller effect on 
the proportion of readily available nitrogen in poultry manure. Composting typically results in 
40–50 % of the total N in FYM and around 15–20 % in poultry litter being lost (either as NH3, 
N2O or in leachate) [ 648, DEFRA 2011 ].  

For composting poultry manure in France, if reversals are very frequent, losses can be as high as 
50–60 % of the total N present. With three reversals, losses are generally around 30–40 % of the 
total  N  present.  After  composting  solid  poultry  manure,  the  volume  and  weight  reduction  is 
reported to be typically in the range of 30–50 % [ 528, ITAVI 2001 ].  

Ammonia emissions can be reduced by composting manure with a high C/N ratio (20–35), and 
by  carefully  balancing  the  frequency  of  heap  reversals,  in  order  to  achieve  sufficient  aeration 
with  minimum  disturbance.  Nitrogen  losses  as  high  as  70 %  have  been  reported,  through 
ammonia volatilisation [ 594, Agro Business Park 2011 ]. The supply of air to composting (and 
aerobic  digestion  systems)  requires  a  fine  balance;  too  high  airflows  encourage  NH3 
volatilisation,  while  low  flows  encourage  methane  and  nitrous  oxide  emissions  [  203,  ADAS 
2005 ]. 

typical  dimensions  of  windrows  do  not  exceed  1.8–2  m 

The 
in  height  and  
3.5–4 m in width [ 528, ITAVI 2001 ]. If the windrow height is excessive (more than 3 m), the 
resulting compression will not let air pass. If windrows are too small, they will be susceptible to 
cooling down easily [ 561, Flotats et al. 2004 ]. The area needed for composting manure coming 
from a 1 000 m2 building is reported to be 800 m2 for turkeys and between 750 m2 and 1 000 m2 
for  broilers  [  528,  ITAVI  2001  ].  Windrows  of  approximately  3.5 m  wide  and  2 m  high 
(corresponding  to  6 m3/m  of  linear  length)  are  needed.  Also,  a  traffic  lane  of  4 m  for  the 
machines  and  10 m  to  15 m  at  the  end  of  windrows  is  generally  needed  for  facilitating 
manoeuvres. 

The energy use depends on the composting technique applied. Without aeration and turning of 
the  heaps,  the  energy  use  would  be  negligible.  The  energy  consumption  varies  between 
5 kWh/tonne  of  raw  manure  for  turning  only,  and  between  8 kWh  and  50 kWh/tonne  of  raw 
manure  for  farms  that  apply  ventilation  through  or  over  the  heaps  as  well.  From  France,  the 
energy  consumption  for  composting  by  forced  ventilation  is  reported  to  be  1 980 kWh  of 
electricity  per  year  and  480  l  of  fuel  per  year,  to  treat  600  t  of  manure  [  259, France  2010  ]. 
Water needs are reported to be between 250 l and 650 l/tonne of manure [ 594, Agro Business 
Park 2011 ]. A comparison of composting applied to different pig solid manures are described 
below in Table 4.184, as reported by France. 

594 

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Chapter 4 

Table 4.184:  Nitrogen and weight losses during composting of solid pig manure, in France  

Composting material 
Straw-based pig manure 
Sawdust- and pine-bark-based pig 
manure 
Sawdust-based pig manure  

Nitrogen loss (%) 
40–50 

Weight reduction (%) 
30–35 

40–48 

20 

15–30 

4 

(1) Manure removed after two cycles of fattening pig production (8 months). 
NB:  Three  reversals  carried  out  during  composting  at  day  0,  day  10  and  day  20,  and  4  months  of 

composting. 

Source: [ 259, France 2010 ] 

Technical considerations relevant to applicability 
Due to cross-media effects, the technique is applicable when manure cannot be transported for 
landspreading  at  a  reasonable  cost  and  pathogen  and  odour  reduction  is  important  prior  to 
landspreading. The technique requires enough space available for windrows to be established.  

The  process  is  relatively  simple  and  can  be  applied  on  small-scale  individual  farms,  using 
standard  farm  equipment,  but  it  needs  proper  control  to  avoid  anaerobic  processes  that  could 
lead  to  an  odour  nuisance.  If  process  control  and  emission  reduction  are  required,  then  the 
composting installation needs to be larger for (cost-)efficient operation. 

In France, the process can  also  be implemented  for temporary field heaps of solid manure on 
flat soil with low permeability (in different places every year and without using the same field 
for at least 3 years). The process should not last more than 2 months. 

Composting should not be carried out on filtering soils, on waterlogged soils, or on sloped land. 
All  measures  should  be  taken  to  avoid  stagnation  of  storm  water  under  windrows  and  to 
accommodate  the  disposal  of  contaminated  water  [  528,  ITAVI  2001  ].  Specially  designed 
composting machines or windrow turners do a more efficient job, but the high costs limit their 
use  to  large  individual  farms  only.  As  a  result,  composting  machinery  is  usually  provided  by 
cooperatives or machinery rings [ 203, ADAS 2005 ].  

Economics 
Composting with mechanical reversal of heaps (windrow composting)  
The operating cost, including the clearing out of the buildings, the formation of the windrows, 
two reversals and the spreading of the compost, is reported from France as follows [ 259, France 
2010 ]: 

 

 

for  a  pig  farm  with  550  fattening  places,  the  cost  is  EUR 0.01–0.02  per  kg  of  pig 
produced; 

in a poultry meat farm of 1 000 m2, the cost is between EUR 7.9 and EUR 9.9 per tonne 
of manure produced per year.  

The purchase of necessary reversing tools in France is often shared, e.g. in CUFE (Cooperative 
of Use of Farm  Equipment). The investment cost for a machine of 4 m  in width,  for working 
with  windrows,  is  reported  to  be  about  EUR 42 000  [  259,  France  2010 ].  Other  examples  of 
investment costs for the necessary composting equipment are reported in Table 4.185. 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Table 4.185:  Investment costs for equipment used in composting plants  

Type of machinery 

Windrow turner 
Windrow turner 
Windrow turner 
Tractor 
Mixers 
Drum sieve 
Composting plant using 
mechanical reversal of 
heaps 
NB: NI = no information provided. 

Investment costs 
(EUR) 
30 000 
100 000 
180 000 
50 000 
20 000–50 000 
70 000 

35 000–100 000 

Source: [ 594, Agro Business Park 2011 ] 

Capacity 
(m3/h) 
100 
1 000–15 000 
2 500 
NI 
10–100 
100 

2 000 t/yr manure + 1 360 t/yr sawdust 
Cost  depends  on  the  buildings  or  covers 
constructed 

The  operating costs are reported to be  equal to EUR 20/tonne produced,  and the income from 
compost sales ranges from EUR 15 to EUR 30 per tonne [ 594, Agro Business Park 2011 ].  

Composting in vessels with forced aeration 
This  system  is  economically  viable  only  for  large  manure  volumes  in  France.  In  a  reported 
example,  the  investment  costs  for  the  equipment  to  treat  600  tonnes  of  manure  per  year  is 
amortised over 10 years, resulting in an annualised investment cost of EUR 10 per tonne of pig 
produced (manure resulting from 2 700 fattening pigs per year), or EUR 6.2 per tonne of poultry 
manure  (four  buildings  of  1 000  m2  each  with  150  t  of  manure  per  building  per  year).  The 
operating cost of the system (including clearing out of the buildings, handling of the silos and 
spreading of the compost) is obviously variable, depending on the production and the size of the 
farm.  From  France,  the  operating  cost  is  reported  to  be  equal  to  EUR 0.02  per  kg  of  pig 
produced and EUR 11.4 per tonne of poultry manure [ 259, France 2010 ]. 

Driving force for implementation 
Composted  solid  manure  has  little  odour,  is  more  stable,  contains  fewer  pathogens  and  is 
relatively  dry.  This  improves  handling,  storage,  transportation  and  landspreading  without  the 
risk of transferring diseases (e.g. landspreading on ready-to-eat crops) [ 506, TWG ILF BREF 
2001  ]  [  648,  DEFRA  2011  ].  Transport  costs  are  reduced  due  to  the  significant  reduction  of 
mass due to water evaporation.  

Example plants 
The  technique  is  applied  at  farm  level,  as  well  as  in  centralised  plants,  in  various  Member 
States; for example, 400 farm-scale plants are reported in the UK, 127 in Spain (Catalonia), 32 
in Romania and 100 in France [ 595, Agro Business Park 2011 ]. In France, around 200 farms 
are  affiliated  with  one  commercial  organisation  using  the  forced  aeration  variant  of  the 
technique.  

Reference literature 
[ 26, Finland 2001 ] [ 203, ADAS 2005 ] [ 257, France 2010 ] [ 259, France 2010 ] [ 409, VITO 
1997 ] [ 410, Greece 2001 ] [ 506, TWG ILF BREF 2001 ] [ 508, TFRN 2014 ] [ 528, ITAVI 
2001 ] [ 561, Flotats et al. 2004 ] [ 594, Agro Business Park 2011 ] [ 595, Agro Business Park 
2011 ] [ 624, IRPP TWG 2013 ] [ 648, DEFRA 2011 ] 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.12.4.2 

Co-composting of poultry manure with green residues  

Description 
See  also  Section 4.12.4.1.  To  control  the  composting  process  and  to  achieve  a  better  quality 
final  product,  substances  of  plant  origin  can  be  added  to  raise  the  carbon  content.  The 
application  of  additives  aims  to  increase  the  porosity  and  binding  of  the  nitrogen,  thereby 
avoiding emissions to air. 
Poultry  manure  can  be  mixed  with  green  residues,  preferably  woody  crushed  residues,  by 
avoiding  moving,  in  proportions  from  1  to  1  (and  up  to  3  to  1)  in  weight  (manure/green 
residues).  Pig  manure  or  slurry  (liquid  or  solid  fraction)  can  also  be  blended  with  organic 
materials for composting. 

Achieved environmental benefits 
Depending  on  the  origin  of  the  manure  and  the  co-substrate  (vegetal  matter)  that  is  co-
composted, a dilution effect of the nitrogenised load by 30 % to 60 % can be obtained. 

Cross-media effects 
NH3 emissions can be controlled by proper management of the process, on the basis of the C/N 
ratio;  otherwise,  they  can  be  considerable.  Greenhouse  gas  emissions  are  very  likely  to  occur 
during composting (see also Section 4.12.4.1). 

Environmental performance and operational data 
A  typical  poultry  manure  composition  is  18 %  bedding  material,  50 %  droppings  and  32 % 
water, even though generally this does not correspond to the ideal composition for composting. 
Poultry  manure  contains  cellulose  and  nitrogen,  but  moisture  and  the  C/N  ratio  are  relatively 
low. A more favourable C/N ratio for composting is 25–30, which is achieved by adding green 
wastes.  Regarding  moisture,  it  is  necessary  to  increase  the  level  by  adding  water  from  an 
external  supply.  Indicative  values  of  the  C/N  ratio  for  different  materials  are  presented  in 
Table 4.186.  

Table 4.186:  Indicative values of the C/N ratio for different materials 

Material 

Slurry solid fraction 
Cattle manure 
Laying hen manure 
Garden residues 
Straw 
Sawdust 
Pine bark 
Source: [ 561, Flotats et al. 2004 ] 

C/N 
9 
18 
13 
23 
128 
511 
723 

In one example, poultry manure was mixed with pine bark, at an excreta/bark ratio of 3/1 on a 
total  weight  basis.  In  a  comparison  with  other  kinds  of  auxiliary  substances,  the  pine  bark 
showed  the  best  results  for  pH  level,  nitrogen  volatilisation  and  carbon  content  (organic 
material).  

The  composting  took  place  at  a  temperature  of  55–60 °C.  A  minimum  porosity  of  the 
manure/bark mixture was maintained to allow an adequate oxygen supply. The test on compost 
produced  with  the  addition  of  pine  bark  showed  an  unchanged  (70 %)  organic  matter  content 
(on  a  DM  basis)  after  90  days.  The  nitrogen  losses  reached  about  35 %  (on  a  DM  basis)  at 
90 days  and increased by  1–2 % over  the  next  90  days.  The pH  at  90  days  was  below  8,  and 
reached 7.5 at 180 days. 

In  another  reported  example,  straw  pig  manures  were  co-composted  with  woody  pig  manures 
(containing  wood  chips  or  sawdust).  The  weight  reduction  was  24–30 %  and  the  nitrogen 

Intensive Rearing of Poultry or Pigs 

597 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

reduction  35–50 %.  The  presence  of  straw  allowed  a  temperature  increase  of  10–15 °C,  in 
comparison with composting the sawdust manure alone, over the last 3 months of composting 
[ 259, France 2010 ].  

The maturation time for compost in a heap, after a co-composting treatment, is reported to be 
longer.  In  particular,  a  duration  of  4  to  5  months  is  needed  for  maturation  when  manure  is 
composted with wood waste, in comparison with 6 weeks of active composting when only solid 
manure is composted [ 528, ITAVI 2001 ]. 

The composition of turkey manure composted with wood waste in a proportion of 1/1 in weight 
is shown in Table 4.187. 

Table 4.187:  Composition variation of turkey manure co-composted with green residues (ratio 1/1 

in weight)  

Before composting 

After composting 

Parameter 

Unit 

Untreated manure 

Dry 
matter 
NI 
% 
Dry matter 
31 
% 
Minerals 
69 
% 
Organic matter 
NI 
NA 
C/N 
3.9 
% 
N 
1.5 
% 
NH4 
2.4 
% 
Organic N 
3.7 
% 
P2O5 
3.7 
% 
K2O 
86 
mg/kg 
Cu 
Zn 
238 
mg/kg 
NB: NI = no information provided; NA = not applicable. 

Raw 
product 
65 
17 
53 
8.5 
3.0 
1.0 
1.9 
2.7 
2.9 
62 
215 

Source: [ 528, ITAVI 2001 ] 

Humified 
mix of green 
residues and 
manure 
Raw 
product 
50 
15 
34 
9.8 
1.9 
0.7 
1.2 
1.8 
1.9 
43 
144 

Final compost 

Raw 
product 
74 
33 
41 
9.4 
2.2 
0.5 
1.7 
2.2 
1.9 
89 
253 

Dry 
matter 
NI 
44 
56 
NI 
3.0 
0.7 
2.2 
2.9 
2.6 
121 
344 

Data on energy consumption for the equipment used in composting and co-composting plants 
are presented in Table 4.188.  

Table 4.188:  Energy consumption of equipment used in composting and co-composting plants 

Equipment/operation 

Drum sieve 
Magnet separator 
Shredding and crushing 
Container composting (11 days) 
Waste  gas  purification  (11  days  of 
intensive composting) 
Waste gas purification (8 weeks)  
Source: [ 594, Agro Business Park 2011 ] 

Energy consumption 
(kWh/t) 
3 
0.5 
2.6 
10 

8.1 

19.3 

Technical considerations relevant to applicability 
See also Section 4.12.4.1. The bark needs to be dried and ground before it can be added to the 
manure. Green residues can be pre-composted before their use. 

598 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
When co-composting is applied with wood waste, the necessary available area that composting 
normally needs should be multiplied by 1.5, in order to take into account the increased volume 
[ 528, ITAVI 2001 ]. 

Chapter 4 

Economics 
See Section 4.12.4.1. 

Driving force for implementation 
See also Section 4.12.4.1. Properly composted solid manure significantly reduces the volume of 
material to be transported and landspread and the amount of odour released. During composting, 
a high temperature is achieved and the product is stabilised and sanitised.  

Composting and co-composting allow the reduction of the quantity of nitrogen to be spread, at 
relatively low investment costs, where constraints to manure landspreading may exist and where 
local markets for alternatives to conventional fertilisers can be found.  

Farmers can participate in recovering compostable residues on behalf of the local community, 
offering an opportunity to solve problems of green waste locally. 

Example plants 
The technique is widely applied in Catalonia, Spain, where it is reported that there are 127 farm-
scale  plants  and  21  medium-scale  plants  where  organic  materials  are  mixed  with  manure  in 
aggregated composting activities [ 595, Agro Business Park 2011 ]. In general, across Europe, 
the  technique  is  widespread,  mainly  at  centralised  plants  where  other  organic  wastes  may  be 
included for co-composting [ 203, ADAS 2005 ]. 

Reference literature 
[  259,  France  2010  ]  [  528,  ITAVI  2001  ]  [  561,  Flotats  et  al.  2004  ]  [  594,  Agro  Business  Park 
2011 ] [ 595, Agro Business Park 2011 ] 

4.12.4.3 

Composting of poultry manure with a biological inoculum 

Description 
Microorganisms of the optional aerobic-anaerobic type (which do not necessarily need oxygen 
to develop) are used to degrade the organic matter. The manures are inoculated by sprinkling, 
preferably before exiting the building. They are then placed in windrows in the same way as for 
conventional  composting.  Windrow  reversal  is  not  necessary.  At  the  end  of  6  weeks  to  2 
months, the compost is moved from the windrow to a maturation heap.  

The bacterial inoculum is a complex of bacteria of the types Bacillus and Lactobacillus (1 dose 
= 10 ml of lactic bacteria and 10 ml of Bacillus), selected according to their metabolic criteria 
and for their aptitude to develop on an environment which has not significantly degraded. They 
all  belong  to  the  classification  AFNOR  IA,  posing  no  danger  to  humans,  animals  or  the 
environment. Oxygen addition may not be necessary when biological inoculums are used.  

Achieved environmental benefits 
Fermentation  which  takes  place  make  it  possible  to  reduce  10 %  to  55 %  of  the  nitrogenised 
load, essentially the ammoniacal nitrogen. This reduction varies according to the origin of the 
manure, the type of litter used (straw, sawdust, conifer shavings, etc.) and the mode of housing 
for the pigs (deep litter, scraped litter, etc.). 

Emissions  of  odour  are  considerably  decreased,  since  bacteria  preferentially  use  the  volatile 
fatty  acids  (odorous  substances)  as  energy  nutrients.  Nitrogen  losses  by  volatilisation  in  the 
form of NH3 are also lower than with other composting systems [ 259, France 2010 ]. 

Intensive Rearing of Poultry or Pigs 

599 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Spreading volumes of manure are reduced, with a consequent energy saving associated with less 
transport  being  required  for  spreading.  Less  energy  is  required  compared  to  the  other 
composting processes that require reversal or forced ventilation. 

Cross-media effects  
In the event that there is no aeration, the risk of methane formation is high. 

Environmental performance and operational data 
The  bacterial  inoculum  presents  no  danger;  it  is  harmless  to  humans,  animals  and  the 
environment.  It  is  pulverised  with  one  dose in 10 litres  of  water  for  10  tonnes of  matter.  The 
composting  can  be  carried  out  within  a  period  of  6  to  8  weeks,  without  needing  to  turn 
windrows over. If a platform is necessary, it is of the same dimensions as for normal windrow 
composting. 

In a reported example of this technique, a mixture made of 57 % poultry manure and 43 % hen 
slurry was composted after inoculation with a bacterial complex (aqueous solution of 5–8 litres 
for  10  tonnes  of  mixture  to  compost).  After  127  days  of  composting,  the  dry  matter  content 
reached  about  69 %  (an  increase  of  more  than  50 %),  ammoniacal  nitrogen  decreased  from 
54 % to 24 %, whereas the organic matter was around 79 % of the dry matter and therefore very 
high. Temperatures inside the windrow ranged between 45 °C and 60 °C, and were maintained 
until the end of the test, without reversal. Complete sanitisation was achieved on day 52 of the 
trial, eliminating the original contaminants, including salmonella and Listeria. Odour emissions 
were substantially reduced [ 371, Penaud et al. 2007 ]. 

Technical considerations relevant to applicability 
See also Section 4.12.4.1. There are no specific technical restrictions for on-farm application. 

Economics 
Indicative  operating  costs  are  EUR 0.02  per  kg  of  fattening  pig  produced  and EUR 10.2–11.9 
per tonne of poultry manure per year. Investment and labour costs are lower, in comparison with 
conventional composting techniques. 

Driving force for implementation 
This technique makes composting simpler than the process with periodically reversed windrows 
or  with  forced  aeration.  Less  material,  machinery,  space  and  energy  than  for  other  processes 
(with reversal of the windrows or forced ventilation) are needed and no reversal is required. As 
for the conventional composting, the degradation leads to the formation of a product that is rich 
in organic matter, more stable and properly hygienised.  

Example plants 
This technique is used in France for poultry manure. The technique is also used in hatcheries, by 
mixing hatchery waste with poultry manure. 

Reference literature 
[ 257, France 2010 ] [ 259, France 2010 ] [ 371, Penaud et al. 2007 ] 

4.12.5 

Anaerobic digestion of manure in a biogas installation 

Description 
Anaerobic microorganisms decompose the organic matter in manure, in an airtight and heated 
vessel  or  reactor  in  the  absence  of  oxygen,  leading  to  biogas  production.  The  controlled 
degradation  of  the  organic  matter,  without  oxygen,  is  influenced  by  the  pH  value  and 
temperature. The main components of biogas are methane (50–70 %) and carbon dioxide (40–
50 %) depending on the substrate used. Other minor components are: H2S, H2O, NH3 and N2O. 
The  higher  the  methane  content,  the  richer  in  energy  is  the  gas.  Biogas  production  strongly 
depends on the type of biomass feedstock used in the process. During anaerobic decomposition, 
four  biochemical  processes  are  distinguished:  hydrolysis,  acidogenesis  (fermentation), 
acetogenesis and methanogenesis. 

600 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

The  produced  biogas  is  collected  and  can  be  used  to  produce  heat,  i.e.  hot  water  in  a  boiler, 
combined electricity and heat in a CHP plant, or it can be used as an alternative fuel in vehicles 
or as a substitute for natural gas after upgrading to biomethane. Some of the heat generated may 
be recycled in the process.  

Anaerobic digestion of slurry generates a slurry-like digestate. Solid poultry and pig manure or 
the solid fraction from mechanically separated slurry can be co-digested with slurry and other 
organic co-substrates in wet digestion. The stabilised residue (i.e. digestate) can be landspread 
as a soil conditioner and source of nutrients (see also  Section 2.7.4). Composting is an option 
before  landspreading  of  digestate  in  the  case  of  sufficiently  solid  digestate.  An  example  of  a 
biogas installation following anaerobic treatment of manure is presented in Figure 4.88. 

Source: [ 594, Agro Business Park 2011 ] 

Figure 4.88:  Example  of  biogas  installation,  following  anaerobic  treatment  of  manure,  located  in 

Denmark  

The requirements for plants producing biogas using animal by-products (including manure) are 
specified  in  Regulation  (EC)  142/2011  (e.g.  hygiene  requirements,  equipment,  location  and 
other parameters). 

Achieved environmental benefits 
Environmental benefits (direct and indirect) of the process of anaerobic digestion, with energy 
recovery from the produced biogas, are as follows:  

 

 

 

 

 

 

Reduction of CH4 emissions, which would otherwise have been emitted from the outdoor 
storage of untreated slurry.  

Substitution of fossil fuel consumption by electricity and/or heat produced by power-heat 
biogas  cogeneration  and/or  by  biomethane  produced  from  biogas,  avoiding  associated 
indirect greenhouse gas emissions.  

Reduction  of  NH3  emissions  at  landspreading  compared  to  untreated  manure;  since  the 
digestate is more homogenous and spreadable, it can seep more easily and evenly into the 
crop root area, enabling better nutrient uptake by crops.  

Improved  bio-availability  of  nitrogen,  leading  to  decreased  use  of  mineral  fertilisers. 
Anaerobic digestion does not change the overall N/P ratio but converts part of the organic 
nitrogen  into  ammonium,  which  is  readily  available  for  the  crops.  This  results  in  an 
increased  concentration  of  ammonium  in  digested  slurry,  up  to  30 %  depending  on  the 
manure digested, compared to untreated slurry. Due to the higher NH4-N content of the 
digestate,  overall  ammonia  emissions  are  reduced  provided  the  digestate  storages  are 
covered and the digestate is spread with low-emission methods. 

Reduction of pathogens in digested manure (higher in a thermophilic range). 

Reduction of odour emissions. The odour from digestate is not as strong and pungent as 
from untreated slurry, and it also disappears faster from a fertilised field, partly because 
the  digested  slurry  percolates  faster  into  the  soil  due  to  its  lower  DM  content,  lower 
particle size and viscosity. 

 

Substantial reduction of COD and BOD, due to organic matter breakdown. 

Intensive Rearing of Poultry or Pigs 

601 

 
 
 
 
 
 
 
 
Chapter 4 

Slurry can also be mechanically separated at the farm with only the solid fraction transported to 
a  centralised  biogas  plant  for  digestion.  A  study  reports  that  the  associated  environmental 
benefits in comparison with slurry landspreading without any prior treatment are dependent on 
the  efficiency  of  the  separation  technology  used.  The  separation  of  volatile  solids 
(biodegradable  carbon)  should  be  as  high  as  possible;  a  polymer  addition  may  increase  the 
efficiency.  In  addition,  the  solid  fraction  should  be  transported  directly  to  the  plant  and 
immediately fed into the digester. If storage is needed, it should be short and in covered storages 
to  minimise  emissions  of  ammonia  and  greenhouse  gases  [  527,  Hamelin  et  al.  2010  ]  
[ 624, IRPP TWG 2013 ]. 

In all biogas plants digesting manure, the digestate directly from the digester is still biologically 
active and contains degradable organic matter, the degradation of which continues in the vessel 
into which the digestate is directed. This vessel should be made into a gas-tight post-digestion 
tank which collects the biogas still produced. With energy use of this post-biogas in conjunction 
with  the  biogas  from  the  digester,  significant  reductions  in  greenhouse  gas  emissions  can  be 
obtained [ 624, IRPP TWG 2013 ]. 

Cross-media effects 
Emissions of unburnt biogas through the biogas motor/engine are around 2 % but can be up to 
4 % from older technology engines. Leakages of biogas (e.g. from the anchoring points of the 
meters) can lead to significant emissions of CH4 and other biogas components (NH3, H2S, etc.). 
Such  emissions  are  known  to  vary  significantly  with  equipment  quality  and  the  standard  of 
maintenance.  Best  practice  should  aim  to  minimise  fugitive  methane  emissions,  since  the 
operational  efficiency  of  the  digestion  process  will  also  be  enhanced,  thus  maximising  the 
production  of  energy  [  206,  Silsoe  2000  ].  Including  emissions  during  storage,  total  methane 
emissions of 6 kg CH4 per tonne of pig slurry, or 4–6 tonnes CH4 per tonne of poultry manure 
are reported from Belgium (Flanders). 

In general, anaerobically digested slurry has a larger share of total N in the form of NH4-N. The 
higher content of NH4-N, in combination with the increased pH of the digested slurry, can lead 
to higher ammonia losses from storage and/or landspreading, compared with raw slurries. Due 
to the reduced content of organic matter, a natural crust is seldom formed on top of the liquid 
when  it  is  stored  in  tanks,  leading  to  a  higher  potential  for  emissions  to  air  [  533,  Baltic  Sea 
2020  2011  ].  Ammonia  emissions  from  storage  of  the  digested  slurry  can  be  high  and  stores 
should be covered and/or slurry immediately cooled, although losses during landspreading  are 
reported  to  be  lower  than  for  untreated  slurry  [  500,  IRPP  TWG  2011  ].  These  effects  may 
counterbalance  the  positive  effect  of  a  faster  infiltration  to  the  soil,  so  overall  losses  may  be 
similar with untreated slurry after surface application. 

A high level of technical knowledge is needed on-farm to manage the whole process. 

Environmental performance and operational data 
In  general,  digesters  operate  with  a  maximum  dry  matter  content  of  12 %,  and  at  a  constant 
temperature  (with  up  to  2  °C  variation)  of  30–45 °C  (mesophilic)  or  52–55 °C  (thermophilic, 
with  an  accepted  temperature  variation  of  only  0.5 °C).  Plants  operating  at  mesophilic 
temperatures are therefore easier to run, so most farm-scale plants, as well as many centralised 
plants, are of this type [ 594, Agro Business Park 2011 ].  

The process of mesophilic anaerobic digestion takes place in large digestion tanks, in one or two 
stages, and the hydraulic retention time is 15–40 days. Propellers are normally installed in the 
digestion tanks to ensure the digestate remains homogeneous and gives a maximum release of 
biogas. In the case of thermophilic digestion, the digester is heated to 55 °C and digestion takes 
12–14  days.  However,  the  technology  is  more  expensive,  since  more  energy  and  more 
sophisticated  control  instrumentation  are  needed.  The  advantages  of  thermophilic  plants  are 
higher levels of biogas production, faster throughput, improved hygienisation of the digestate, 
and lower viscosity during the process, facilitating mixing [ 594, Agro Business Park 2011 ]. 

602 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 4 

Very  short  retention  times  decrease  the  level  of  degradation  and  thus  may  result  in  higher 
emissions  later  in  the  management  of  the  digestate  [  624,  IRPP  TWG  2013  ].  The  condition 
necessary for the successful formation of methane is a minimum water  content of 50 % in the 
initial substrate [ 373, UBA Austria 2009 ]. 

The  biogas  production  potential  depends  largely  on  the  type  of  manure.  Around  14–25 m3  of 
biogas production per m3 of slurry may be obtained (or even higher when pig slurry is digested), 
containing  around  60–65 %  methane.  Calculations  for  biogas  plants  in  Denmark  show  an 
average  production  of  22 m3  of  biogas  per  tonne  of  pig  slurry  containing  6 %  dry  matter  (on 
average) [ 594, Agro Business Park 2011 ]. 

In  order  to  maintain  digestion,  part  of  the  heat  produced  during  CHP  production  is  used  to 
maintain  the  temperature  of  the  biogas  plant.  About  a  third  of  the  heat  produced  from  such 
combined heat and power (CHP) units is typically used for the anaerobic digestion process itself  
[  355,  Warwick  2007  ].  This  amount  depends  on  scale  and  configuration.  Net  biogas  power 
production is reported as 2.5 kWh per m3 of biogas and net biogas heat production as 2.0 kWh 
per m3 of biogas (after own use of heat and power in the process) [ 594, Agro Business Park 
2011 ]. 

To reach the required temperature, manure may be warmed up using part of the produced biogas 
or by heat exchange with the water cooling the gas engines. In farm-scale applications, heating 
of the manure is not always applied. The required parasitic energy load to maintain the digester 
is estimated to be around 5–20 % of the gross energy production of the installation, depending 
on  the  scale and configuration. The  use  of  20–25  m3  of biogas  in  the  CHP  plant  can  produce 
35 kWh to 40 kWh of electricity and 55 kWh to 75 kWh of heat energy [ 203, ADAS 2005 ].  

From Germany, net biogas power production is reported to be 2.5 kWh per m3 of biogas, and, 
2.0 kWh  per  m3  of  biogas  as  net  heat  production  (after  own  use  of  heat  and  power  in  the 
process)  [  594,  Agro  Business  Park  2011  ].  The  resource  efficiency  of  a  combined  heat  and 
power  (CHP)  system  is  about  35 %  for  the  electrical  production,  or  about  85 %  if  all  the 
produced heat is recovered [ 259, France 2010].  

The biogas is stored in a gas buffer before being used in a heater or a gas engine. Before the 
biogas can be used, sulphur must be removed by a biological, adsorptive (active coal or ferro-
chloride)  or  chemical  technique (quenching)  in  larger  installations, in  order to protect the  gas 
engine. A double membrane cover system is used to collect a quantity of biogas from the heated 
slurry  digestate  storage 
the  cooling  phase  of  a  continuous  digester  
[517, Petersen et al. 2011 ]. 

tank  during 

Due to the general manure management required by the anaerobic digester, it is estimated that 
total farm emissions in Finland are reduced by 40 % for ammonia, while odour and methane are 
reduced by 80 % [ 229, Finland 2010 ]. N2O emissions associated with anaerobic digestion are 
reported to be negligible, compared to the overall annual N2O emissions from the farm. 

Since  only  a  small  proportion  of  the  total  manure  mass  is  decomposed  in  a  sealed  anaerobic 
digester,  the  total  content  of  nutrients  in  the  digested  manure  does  not  differ  much  from  raw 
slurries.  However,  data  show  a  reduction  in  the  slurry  dry  matter  content  of  around  25 % 
between raw and digested slurries. The organic forms of nitrogen and phosphorus are converted 
into water-soluble and readily available ΝΗ4-N and phosphorus. Digested manures show a 10–
30 % higher proportion of ΝΗ4-N.  

Calculations  made  for  the  quantification  of  avoided  greenhouse  gas  emission,  as  a  result  of 
fossil fuel  substitution  with  biogas,  show  that the  CO2-neutral  energy  produced  by  the  biogas 
process saves 2 kg CO2 equivalent emissions per m3 of biogas. In addition, model calculations 
applied  in  Denmark  show  a  reduction  of  naturally  developed  greenhouse  gases  (methane  and 
nitrous oxide) of approximately 1.2 kg CO2 equivalent per m3 of biogas. In total, a potential of 

Intensive Rearing of Poultry or Pigs 

603 

 
 
 
 
 
 
 
 
Chapter 4 

3.2 kg CO2 equivalent reduction in greenhouse gases emissions per m3 of biogas are estimated 
[ 499, AgroTech 2008 ]. 

Technical considerations relevant to applicability 
This technique may not be generally applicable due to the high implementation cost. There are 
no technical restrictions to its on-farm application. The cost efficiency is likely to increase with 
an increasing volume of fermented manure. The minimum farm size according to the literature 
(see Reference literature below) is 50 LU [ 506, TWG ILF BREF 2001 ]. 

The  biogas  production  capacity  of  pig  slurry  is  relatively  low;  hence,  it  often  requires  the 
addition of a proper co-substrate to increase efficiency. Possible sources of such substances are 
energy plants, green wastes, sewage sludge, and food residues [ 373, UBA Austria 2009 ]. For 
this reason, in France, Denmark and Spain, biogas production is not considered technically and 
economically  viable  with  only  slurry  as  a  substrate  [  259,  France  2010  ].  In  Spain,  a  slurry 
biodigestion  plan  has  been  developed,  with the  objective  of  reducing  greenhouse  gases  in  the 
livestock sector.  

Economics 
The  economics  of  anaerobic  digestion  systems  are  highly  site-specific  and  depend  on  factors 
such as land and labour costs, effluent discharge regulations, and prices for energy produced by 
other  sources.  Where  government  incentives  include  a  premium  price  for  the  electricity 
produced and in the case of environmental pressures that force farmers and related industries to 
consider alternative means to manage manure and organic wastes, the technique with associated 
biogas production can be economically viable.  

A reported example from Finland of a farm with 263 places for farrowing sows and 784 places 
for  weaners  indicates  an  investment  of  EUR 3 536  per  animal  place  and  an  operating  cost  of 
EUR 40 per animal place per year. The annualised costs are given as EUR 656 per animal place. 
Electricity  generated  on-farm  is  reported  to  be  453 000 kWh  and  the  produced  heat 
700 000 kWh (equivalent to 77 000 litres of fuel oil), allowing the farm to be self-sufficient in 
heat and electricity [ 229, Finland 2010 ]. 

An example of a biogas plant for a small-scale farm is reported from Denmark, where pig slurry 
alone  is  used  as  a  substrate  for  biogas  production.  The  farm  has  a  capacity  equivalent  to 
2 950 fattening pig places (> 30 kg) and 500 sow places. Operational data and costs associated 
with the production of biogas are presented in Table 4.189. 

Table 4.189:  Operational and cost data for a biogas plant applied on a small-scale farm, operating 

with pig slurry only 

Parameter 

Slurry produced (tonnes/year) 

Products sold 

Prices for products (EUR/kWh) 

Values 
9 650 
100 % electricity 
50 % excess heat 
Electricity: 0.103 
Heat: 0.040 
118 985 
624 000 
43 405 
60 118 
103 523 
55 040 
-48 483 

Methane produced (Nm3/year) 
Total investment costs (EUR) (1) 
Annual operating costs (EUR) 
Annual capital costs (EUR) (2) 
Total annual costs (EUR) 
Annual income (EUR) 
Annual (negative) earnings after tax (EUR) 
(1) No financial incentives were received. 
(2) Interest rate of 7.0 %, inflation rate of 1.5 %, taxation of 30 % and amortisation over 15 years. 
Source: [ 533, Baltic Sea 2020 2011 ] 

604 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
High  investment  and  operating  costs  are  a  major  deterrent  for  the  implementation  of  this 
technique;  therefore,  the  availability  of  grants  and  high  renewable  energy  prices  would  be 
needed to motivate the implementation of on-farm anaerobic digestion facilities [ 648, DEFRA 
2011  ].  For  this  reason,  in  some  Member  States,  the  use  of  biogas  in  connection  with  the 
covering  of  the  pig  slurry  stores  is  stimulated  by  financial  incentives  (e.g.  Italy,  France, 
Germany and Spain).  

Farms  can  achieve  self-sufficiency  in  electricity  [  229,  Finland  2010 ]. The  heat  produced  by 
cogeneration of heat and power can also be transferred to external users for residential district 
heating and commercial heating requirements.  

Environmental policy targets for renewable energy, together with uncertainty about oil prices, 
may encourage the use of this technique. Co-processing with animal wastes from the food and 
meat industry may increase due to the increased costs of disposal brought about by the Animal 
By-products (ABP) Regulations [203, ADAS 2005 ]. 

Example plants 
Centralised  manure  co-digestion  installations  where  manure  and/or  energy  crops  and  organic 
biological waste are used as inputs are common. In 2011, there were 180 anaerobic digesters in 
the  Netherlands  and  23  in  agricultural  areas  of  Belgium  (Flanders).  Around  30  farm-scale 
digesters are located in the UK and 3 in Belgium (Flanders). A biogas plant in Austria has been 
reported  to  be  in  operation  since  1995.  In  2003,  in  Italy  about  50  low-cost  digesters  were 
installed,  using  gas  which  develops  under  the  covers  on  slurry  storage  operating  at  low 
temperatures.  

For  the  Baltic  Sea  region,  the  number  of  existing  biogas  plants  for  manure  digestion  and  the 
amount of manure digested (estimated for the year 2012) are presented in the following table. 

Table 4.190:  Number  of  existing  biogas  plants  for  manure  digestion  and  the  amount  of  manure 

digested in the Baltic Sea region countries (estimated for year 2012) 

Country 

No of biogas 
plants 
treating 
manure 

Finland 
Sweden 
Denmark 
Germany 
Poland 
Latvia 
Estonia 
NB: NI = no information provided.  
Source: [ 658, Baltic Manure 2013 ] 

17 
40 
80 
7 320 
16 
30 
2 

Small-scale 
manure 
digestion 
(reactor volume 
< 1 000 m3) 
13 
25 
60 
NI 
0 
0 
0 

Large-scale 
manure 
digestion 
(reactor volume 
> 1 000 m3) 
4 
15 
20 
NI 
16 
30 
2 

Amount of 
manure 
digested 
(t/year) 

180 000 
350 000 
2 500 000 
NI 
269 000 
725 000 
140 000 

An example plant is reported from Austria (Hirnsdorf) where a farm-scale biogas plant is loaded 
with  pig  slurry  and  other  materials  (laying  hen  manure  or  wastes).  The  biogas  reactor  has  a 
volume of 750 m3 and treats around 4 500 m3 of substrate every year in bimonthly batches (the 
residence time is 50–60 days on average). The gas that is produced is desulphurised and fed to a 
CHP plant made up of two engines, with a maximum electrical power of 2 × 57 kW. Excess gas 
is  stored  in  a  dry  gas  silo  reservoir.  The  electricity  produced  supplies  the  farm's  own 
requirements  and  the  excess  power  is  fed  into  the  public  grid  (between  2 000 kWh  and 
6 000 kWh  per  month).  However,  for  the  in-farm  peak  demands,  external  power  has  to  be 
bought. The waste heat from the process is recovered and used in winter to heat the sorting hall 

Intensive Rearing of Poultry or Pigs 

605 

 
 
 
 
 
 
 
 
 
Chapter 4 

and the pig houses, as well as to fully condition the gas reactor itself. From March to September, 
the heat is also used to feed the maize-drying facility in the continuous flow dryer system. 

Reference literature 
[  39,  Germany  2001 ]  [  203,  ADAS  2005 ] [  206,  Silsoe  2000 ] [  229,  Finland 2010 ]  [  259, 
France  2010  ]  [  355,  Warwick  2007  ]  [  373,  UBA  Austria  2009  ]  [  203,  ADAS  2005  ]  
[  355,  Warwick  2007  ]  [  499,  AgroTech  2008  ]  [  500,  IRPP  TWG  2011  ]  [  506,  TWG  ILF 
BREF 2001 ] [ 517, Petersen et al. 2011 ] [ 527, Hamelin et al. 2010 ] [ 533, Baltic Sea 2020 
2011 ] [ 594, Agro Business Park 2011 ] [ 595, Agro Business Park 2011 ] [ 624, IRPP TWG 
2013 ] [ 648, DEFRA 2011 ] [ 658, Baltic Manure 2013 ] 

4.12.6 

Anaerobic lagoon system 

Description 
This type of liquid manure storage system is designed and operated to combine manure storage 
and slow anaerobic treatment under ambient temperature conditions. Slurry is stored in lagoons 
of  at least  2  m  deep  where  microorganisms  break  down  organic  matter in  the  absence  of free 
oxygen. The lagoon may be covered to retain heat and collect biogas.  

Slurry is placed in a settling basin (or lagoon), from where it overflows or is pumped into the 
anaerobic  lagoon  system  (often  three  to  five  earth-banked  structures).  The  solid  part  (sludge 
sedimentation) is used in landspreading, while the liquid fraction, after anaerobic treatment, is 
used to  irrigate  and  fertilise  fields  or  may  be  recycled  as  flushing  water.  Anaerobic treatment 
can be followed by a final aerobic stage before the liquid fraction is applied or discharged, if the 
characteristics and legal conditions allow for it [ 364, Portugal 2010 ].  

The  technique  may  involve  mechanical  separation  of  slurry  before  filling  the  lagoon,  with 
subsequent separate treatment of the solid and liquid fractions; with the liquid being sent to the 
lagoon  system.  Mechanical  separation  of  slurry  can  prevent  the  capacity  decrease  of  lagoons 
caused by sludge sedimentation and can reduce the organic matter in the liquid part.  

Anaerobic  lagoons  are  designed  for  varying  lengths  of  storage  (up  to  1  year  or  longer), 
depending  on  the  climate,  the  content  of  volatile  solids  of  the  slurry,  and  other  operational 
factors. 

Achieved environmental benefits 
The  aim  of  the  treatment  is  to  improve  the  characteristics  of  both  solid  and  liquid  manure 
fractions so  that they  can be  used as fertiliser.  In  particular,  the  organic load (BOD,  COD)  is 
reduced. Manure is stabilised and odour is reduced. More homogeneous manure is produced 
that is easier to manage and pump.  

Information  on  anaerobic  lagoons  also  refers  to  the  discharge  option  or  to  application  in 
situations  where  otherwise  this  would  have  had  an  unwanted  environmental  impact.  It  is 
questioned  whether  in  these  cases  anaerobic  lagoons  solve  or  add  to  the  problem  of  manure 
application.  

Cross-media effects 
In general, CH4 emissions from an anaerobic system are expected to be significant. Odour may 
develop from the lagoons, as well as NH3 and N2O emissions [ 506, TWG ILF BREF 2001 ]. 
After  separating  out  the  liquid fraction,  a solid fraction  remains,  which  then has  to  be  treated 
(e.g. composting). 

Energy is required for the separation of the solid fraction and for pumping the liquid between 
basins. Natural height differences in the countryside are used to make the liquid flow by gravity 
from one lagoon to another. At the end of the separation, a liquid fraction remains that has to be 
disposed of. 

606 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Large  surfaces,  especially  in  warmer  climates,  are  subjected  to  high  evaporation  rates  and  a 
consequent increase of salt content in the slurry. This effect needs to be taken into consideration 
at the time of landspreading.  

Environmental performance and operational data 
The  lagoon  system  is  considered  to  be  relatively  easy  to  operate.  Generally,  an  installation 
separates  the  solid  fraction  mechanically.  The  liquid  manure  that  remains  can  stay  in  the 
different lagoons for up to a year. The final aerobic step is optional, consequently not all farms 
have an aeration installation.  

In cold weather (below 22 °C), CH4 emissions are linearly related to the slurry temperature. At 
higher  temperatures,  the  variation  of  CH4  emissions  depends  on  the  slurry  composition,  wind 
speed  and  air  temperature  [  496,  Sharpe  et  al.  1999  ].  IPCC  guidelines  (2006)  propose  a 
methane  emission  factor  for  uncovered  anaerobic  lagoons  from  66 %  to  80 % of  the  methane 
potential of the volatile solids, for temperatures in the range of 10–28 °C; the technique is the 
manure management method with the highest methane emissions [ 659, IPCC 2006 ]. 

Results  reported  by  Portugal  for  slurry  treatment  in  anaerobic  lagoons  as  the  final  step  of  a 
combination of treatments are presented in Table 4.191. The associated emission levels for the 
most  important  parameters  indicate  that  effluents  from  anaerobic  lagoons  could  be  used  for 
landspreading,  but  would  not  be  compatible  with  discharge  in  watercourses,  since  the  liquid 
would  not  comply  with  the  emission  limit  values  set  for  waste  water  discharges  to  surface 
waters, in particular for BOD5 (40 mg/l O2) and total suspended solids (60 mg/l) [ 364, Portugal 
2010 ]. 

Table 4.191:  Characteristics of effluents from slurry treated in anaerobic lagoons  

Treatment 

BOD5  
(mg/l O2) 

Total suspended 
solids 
(mg/l) 

Total N 
(mg/l) 

Total P 
(mg/l) 

Mechanical separation, plus 4–5 
anaerobic lagoons 
NB: Data refer to annual averages of analyses carried out in three different farms. 
Source: [ 364, Portugal 2010 ] 

147–200 

191–500 

526–1 100 

21–27 

Technical considerations relevant to applicability 
Anaerobic lagoons are applied to farms with sufficient land to allow for a series of lagoons to be 
applied  to  cover  the  different  treatment  steps.  Lagoons  are  particularly  suitable for  large 
capacities. Note however that the temperature requirements for the anaerobic process make the 
technique less suitable for areas that experience cold winters. 

Economics 
Costs vary, depending on the geophysical characteristics of the soil, the size of the farm, and on 
the intended purpose for the treated slurry. 

Driving force for implementation 
Lagoon  systems  offer  odour  abatement,  a  long-term  reservoir  for  liquid  manure,  and  high 
flexibility  for  the  timing  of  landspreading  of  the  manure.  The  technique  provides  combined 
slurry stabilisation, separation and storage. 

Legislation  on  landspreading  of  waste  water or  discharge  to  surface  waters  has contributed  to 
the  application  of  anaerobic  lagoons  in  some  Member  States,  such  as  Portugal  and  Greece, 
Legislation  in  Portugal  was  enforced  to  limit  the  discharge  in  watercourses,  setting  stricter 
values, which are seldom achievable by the use of anaerobic lagoons. 

Intensive Rearing of Poultry or Pigs 

607 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Example plants 
In Portugal, the treatment of pig slurry in anaerobic lagoons, preceded by mechanical separation 
of the solids, is usually applied. The technique is also applied on farms in Greece and Italy. 

Reference literature 
[ 364, Portugal 2010 ] [ 410, Greece 2001 ] [ 496, Sharpe et al. 1999 ] [ 506, TWG ILF BREF 
2001 ] [ 659, IPCC 2006 ] 

4.12.7 

Evaporation and thermal drying of manure 

Description 
The objective of this treatment is to obtain a dried, easy-to-handle product from solid manure or 
slurry, retaining most of the nutrients (nitrogen, phosphorus) and organic matter of the original 
material.  Depending  on  the  required  moisture  content  of  the  final  product,  a  preliminary 
evaporation step is required, where water is removed from the slurry. The heat source employed 
for  the  evaporation  may  consist  of  recovered  waste  heat  from  a  combined  heat  and  power 
engine or from other processes. There are two variations of the evaporation technique:  

 

 

Vacuum  evaporation:  At  temperatures  lower  than  100 °C  (typically  50–60 °C)  and 
pressure  conditions  below  the  vapour  pressure  of  the  liquid,  water  and  other  volatile 
components  evaporate  and  are  subsequently  recovered  by  condensation.  Evaporation 
units  are  usually  formed  by  two  or  multiple  steps.  If  the  pH  inside  the  evaporator  is 
maintained  under  5.5,  it  is  ensured  that  the  ammonium  will  be  recovered  in  the 
concentrate. 

Atmospheric  evaporation:  Evaporation  takes  place  at  atmospheric  pressure  and  a 
moderate temperature from the liquid fraction of aerobically treated slurries. In this case, 
the manure is ground and mixed first. Using a heat exchanger, the manure is then heated 
to 100 °C by means of warm condensate and kept at this temperature for about 4 hours, 
while degassing occurs. Any foam that has been formed is degraded.  

Following  the  evaporation  stage,  the  manure  is  dried  by  a  drying  machine  and  compressed 
(1.4 bar).  Any  water  vapour  that  is  formed  is  compressed,  which  raises  the  temperature  to 
110 °C. This hot vapour is then used in a heat exchanger, thereby drying the manure using the 
sensible heat of the vapour. The vapour is finally recovered as condensate. 

Achieved environmental benefits 
The technique allows a dried product to be obtained with a higher nutrient concentration, which 
facilitates its management, with a relatively low energy consumption and reduced emissions to 
air  and  water.  Organic  matter  is  sanitised  (depending  on  the  time  and  temperature  of  the 
process).  

Cross-media effects 
Energy  consumption  is  required  for  the  thermal  drying  of  manure.  For  an  industrial-scale 
facility,  a  reported  estimation  of  the  thermal  requirements  is  15–18  kW/m3  for  an  acidified 
digested  slurry  entering  the  evaporator  with  a  dry  matter  content  of  25–30 %  [  594,  Agro 
Business Park 2011 ]. The application of mechanical vapour compression (drying machine) has 
an energy consumption of about 30 kWh per tonne of water evaporated.  

In  the  case  of  atmospheric  evaporation,  emissions  of  ammonia,  VOCs  and  non-condensable 
odorous compounds occur, while, with vacuum evaporation, there are no emissions to air, since 
the evaporated  fraction is recovered  as  condensate.  If  atmospheric  evaporation  is  preceded by 
aerobic treatment (aerobic digestion and total or partial nitrification-denitrification, with carbon 
and nitrogen removal), emissions will be limited [ 256, VITO 2006 ] [ 594, Agro Business Park 
2011 ]. 

608 

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The potential gaseous emissions from the drying step have to be recovered (e.g. by scrubbing), 
in particular to avoid ammonia (NH3) or organic volatiles (VOC) emissions. If the input slurry 
comes from the anaerobic digestion process, the volatilisation of organic matter is reduced and 
the heat from  a  CHP  engine  using  biogas  produced  by  the  anaerobic  digestion  can  cover part 
(10–20 %)  of  the  thermal  energy  needs.  Ammonia  emissions  from  the  dryer  can  also  be 
controlled by using the input slurry from a previous nitrification-denitrification or acidification 
process.  

Copper, zinc and other metals are present in the dried product (depending on their concentration 
in the raw manures); this could limit the landspreading of dried manure. The product of drying, 
because of the NH3 volatilisation, will not have an equilibrium between carbon and nitrogen for 
subsequent uses [ 624, IRPP TWG 2013 ]. The volume of slurry/manure is reduced  (reducing 
the transport costs). 

Environmental performance and operational data 
The  products  of  this  technique  are  pulverised  manure  with  85 %  dry  matter  content  and  an 
effluent, which is the residual condensate. This condensate is low in  nitrogen and phosphorus 
and has a COD of less than 120 mg/l. A water removal efficiency of over than 85 % is reported. 
In addition, 95 % of the nitrogen (if previously acidified), and almost all of the phosphorus and 
potassium of the input manure could be conserved in the dried product. 

The  maximum  dry  matter  content  of  the  concentrate  that  can  be  achieved  with  the  vacuum 
evaporation technique is around 25 % [ 256, VITO 2006 ]. It is also reported that a pig slurry 
with  2.5–3.5 %  dry  matter  can  be  concentrated  up  to  25–30 %.  If  the  pH  is  maintained 
below 5.5, the recovery of nitrogen remaining in the concentrate will be higher than 98.0 %. The 
efficiency  of  atmospheric  evaporation  is  high  (up  to  90 %  nutrient  recovery),  but  highly 
dependent  on  previous  treatments  (organic  matter  removal/nitrogen  removal  or  acidification 
treatment) [ 594, Agro Business Park 2011 ]. 

The system is affected by the heterogeneity of the manure, foam formation and corrosion. The 
selection  of  the  construction  materials  is  of  great  importance,  in  particular  resistance  to  high 
temperature and corrosion.  

Concerning  energy  consumption,  an  increasing  number  of  evaporation  steps  results  in  a 
significant decrease in energy consumption. A single-step evaporator requires 1.1–1.25 tonnes 
of  steam  for  each  tonne  of  water  evaporated,  while  a  five-stage  vacuum  evaporator  requires 
0.25 tonnes  of  steam  per  tonne  of  water  evaporated  [  256,  VITO  2006  ].  The  estimated  heat 
needed for a large-scale unit, operating with vacuum evaporation, treating 6–8 m3/h of acidified 
pig  slurry  with  a  dry  matter  content  of  0.9–1.2 %,  is  reported  as  250–280 kW/m3  [594,  Agro 
Business Park 2010 ]. 

Technical considerations relevant to applicability 
The technique has been developed for use on large farms. The maximum capacity is 15–20 m3 
per  day.  Subsidies  (e.g.  for  power  production)  are  usually  necessary  to  make  these  kind  of 
treatment facilities economically feasible [ 594, Agro Business Park 2011 ]. 

Economics 
Costs  depend  on  several  factors  and  a  general  indication  is  difficult.  Investment  costs  are 
(partly)  determined  by  the  water  evaporation  capacity,  type  of  evaporator,  configuration  used 
(e.g. number of stages), the construction material, available heat, etc. An example of investment 
and operating costs reported from Belgium (Flanders) is presented in Table 4.192, for a vacuum 
evaporation  plant  with  a  capacity  of  14 000 tonnes  per  year,  treating  pig  slurry  [  256,  VITO 
2006 ].  

Intensive Rearing of Poultry or Pigs 

609 

 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.192:  Costs  for  a  vacuum  evaporation  plant  for  pig  slurry,  with  a  capacity  of  14 000 

tonnes/year 

Parameter 

Investment costs  
Annualised investment costs 
Operating costs (including pretreatment) 
Total costs (including storage, buildings, infrastructure) 
Source: [ 256, VITO 2006 ]  

Unit 
EUR  
EUR/t 
EUR/t 
EUR/t 

Costs 
490 000 
6 
4.5 
17 

At the industrial scale, vacuum evaporation units are usually formed by two or multiple steps. 
The energy consumption for single-step evaporators is very high and accounts for most of the 
cost of the evaporation system. Each added evaporation step reduces the energy consumption by 
33 % (although investment costs are increased).  

Driving force for implementation 
Local restrictions on nutrient supply may force the use of such a technique, since the resulting 
concentrated product is easier and cheaper to transport and spread on the land. Another benefit 
of  the  concentration  by  vacuum  evaporation  is  that  it  has  practically  no  negative  effects 
regarding  direct  emissions,  including  odours,  since  evaporated  water  is  recovered  as  a 
condensate, which could then be reused [ 203, ADAS 2005 ] [ 594, Agro Business Park 2011 ]. 

The dried product could be considered as sterilised (depending on the time and temperature of 
the  process)  and,  depending  on  its  quality,  it  may  represent  a  source  of  income  as  organic 
fertiliser.  

Example plants 
The technique is used in Belgium (Flanders) in several manure processing systems. Three plants 
are reported to operate in Spain with atmospheric evaporation. Vacuum evaporation is applied 
in at least three plants in Spain and one plant in France [ 594, Agro Business Park 2011 ]. 

Reference literature 
[ 409, VITO 1997 ] [ 203, ADAS 2005 ] [ 256, VITO 2006 ] [ 594, Agro Business Park 2011 ] 
[ 624, IRPP TWG 2013 ] 

4.12.8 

External tunnel for manure drying  

Description 
Manure  is  collected  on  manure  belts  from  the  laying  hen  house  and  is  conveyed  to  separate, 
perforated belts in a ventilated tunnel for drying. The tunnel is ventilated with warm air that is 
extracted from the hen house. The manure is dried in about 2 to 3 days, reaching an average dry 
matter content of 60–80 %. The tunnel is usually built at the side of the hen house.  

In the design shown in Figure 4.89, the incoming manure is sent to the top of the tiered belt and 
is carried along each belt from one end to the other and then drops to the lower belt that rolls in 
the opposite direction. Droppings have to be spread in relatively thin layers (5–15 cm) over the 
perforated  belts  in  which  the  holes  or  perforations  increase  airflow  through  the  droppings  for 
drying. After drying, the manure is sent to a separate covered storage facility or to a container. 

610 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 44, IKC 2000 ] 

Figure 4.89:  Principle of external drying tunnel with perforated manure belts  

Achieved environmental benefits 
The high dry matter content that is achievable with this technique reduces ammonia and odour 
emission from subsequent manure storage and landspreading, in comparison to systems with a 
lower dry matter content in the manure. 

Cross-media effects 
Only limited extra energy (electricity) is needed to operate this system, because the fans for the 
drying tunnel are the same as those used for the ventilation of the hen house; however, at the 
same time more belts have to be operated, so extra energy is required to run the additional belts. 
The  ventilation  system  needs  20–30 %  more  power  to  overcome  the  resistance  due  to  the 
additional room where the drying system is hosted [ 150, CRPA 2008 ].  

If the process is not fast or complete enough to dry the droppings (e.g. 80 % in 72 h), an inverse 
effect  may  occur  where  NH3  is  formed  and  extracted  to  the  air  by  the  blowing  drying  air.  If 
regular container transport is not possible, a separate storage facility will be necessary for the 
dried manure. 

Environmental performance and operational data 
From Italy it is reported that the dry matter content of the manure leaving the hen house varies 
by season from 26 % to 47 %; it can be dried in the tunnel to a dry matter content ranging from 
55–60 %  in  winter  to  over  85 %  in  summer.  If  the  manure  is  dried  to  60 %  DM  as  fast  as 
possible  before  uric  acid  hydrolysis  takes  place,  then  further  drying  will  not  lead  to  NH3 
emission [ 508, TFRN 2014 ]. In France, manure drying is sometimes coupled with a system for 
pelletising the droppings [ 368, France 2010 ]. 

Emissions  during  storage  and  landspreading  of  the  dried  manure  are  significantly  reduced. 
Measurements during storage show that ammonia losses amounted to 4 % of the total N in the 
heap and that during landspreading they amounted to 1.1 % of the applied total N and to 10.4 % 
of  TAN.  The  reduction  of  ammonia  emissions  from  landspreading  of  dried  hen  manure  with 
respect to wet droppings was over 90 % with respect to total nitrogen and 65 % with respect to 
N-NH4 [ 141, Italy 2010 ]. Similar results are obtained by other studies where losses of total N 
after landspreading amounted to 1.1 % in summer and 0.5 % in autumn for the dried manure, in 
comparison with 15.2 % and 7.7 % of total N for the untreated manure [ 150, CRPA 2008 ].  

Over  the  whole  year,  average  emissions  of  ammonia  and  some  greenhouse  gases  from  the 
laying hen house and from the drying tunnel are those reported in Table 4.193. 

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Table 4.193:  Average  ammonia,  methane  and  nitrous  oxide  emissions  from  the  laying  hen  house 

and drying tunnel 

Emission 

NH3  
N2O  
CH4  
Source: [ 141, Italy 2010 ] 

Layers house 

Drying tunnel 

Yearly 
average 
kg/ap/yr 
0.152 
0.002 
0.094 

Min.–Max. 

kg/ap/yr 
0.044–0.290 
0.000–0.017 
0.000–0.354 

Yearly 
average 
kg/ap/yr 
0.167 
0.001 
0.010 

Min.–Max. 

kg/ap/yr 
0.126–0.210 
0.000–0.003 
0.003–0.028 

During  operation  of  the  drying  tunnel,  ammonia  emissions  are  higher  at  the  first  stage  of 
processing but decline steadily over the second and third day. 

Considering the seasonal trends of overall emissions of the hen house and of the drying tunnel, 
it is measured that emissions from the hen house are higher in summer and that those from the 
drying tunnel are higher in winter. This is due to the drastic reduction of NH4 emissions when 
the dry matter content of the manure goes over 60 % which is achieved early in the first part of 
the  tunnel  during  the  summer  with  a  minimal  contribution  to  emissions  from  the  final  part, 
whereas, in winter, the manure from the laying hen house is wetter and most of the dehydration 
occurs in the tunnel, which shows higher emissions than from the house itself. 

Measurements  of  odour  concentration  in  the  air  extracted  from  both  the  hen  house  and  the 
drying  tunnel  fans  showed  low  values,  on  average  equal  to  63  ouE/m3  (23 144  ouE/m3)  in  the 
case  of  the  hen  house  and  86 ouE/m3  in  the  case  of  the  tunnel  (26 195 ouE/m3)  [  141,  Italy 
2010 ]. 

Technical considerations relevant to applicability 
This  system  is  only  applicable  to  manure  from  laying  hen  houses.  It  is  applicable  to  existing 
houses  with  manure  belts  as  it  hardly  interferes  with  the  existing  structures.  It  just  requires  a 
means of extracting warm air to supply the drying tunnel. 

Economics 
Cost data relate to its application in Italy. Although investment costs have not been reported, the 
extra  investment  costs  for  the  tunnel  may  be  offset  by  the  fact  that  the  cost  for  the  external 
manure storage is lower. The extra costs for energy are limited, equal to only EUR 0.03 per bird 
place per year. The total extra operating cost (including capital + operating costs) is EUR 0.06 
per bird place per year. This means that, with a 70 % NH3 reduction, the cost is EUR 0.37 per 
kg of NH3 abated [ 43, COM 2003 ]. 

Driving force for implementation 
Once  the  manure  is  very  dry,  only  very  low  levels  of  emissions  of  ammonia  and  odour  will 
occur  in  the  storage  period.  This  technique  could  offer  an  advantage  where  odour  is  a  local 
social constraint. 

Example plants 
It  has  been  reported  that  the  system  has  gained  interest  among  Italian  poultry  farmers. 
Variations of the technique have been developed in France.  

Reference literature 
[ 43, COM 2003 ] [ 44, IKC 2000 ] [ 141, Italy 2010 ] [ 150, CRPA 2008 ] [ 259, France 2010 ] 
[ 368, France 2010 ] [ 508, TFRN 2014 ] 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.12.9 

Slurry acidification 

Description 
Slurry  acidification  is  a  technique for  reducing  ammonia  emissions from  pig  farms  by  adding 
sulphuric acid to the slurry. The equilibrium between NH4-N and NH3 in solutions depends on 
the pH (acidity). A low pH favours retention of NH4-N (in the form of ammonium sulphate) at 
the expense of ammonia (NH3-N) volatilisation. 

The slurry is pumped from the pig houses to a process tank by means of a valve pit, where the 
right  dose  of  sulphuric  acid  is added  to  lower the  pH  to  5.5. The  amount of  sulphuric  acid is 
controlled  by  a  pH  sensor.  In  the  process  tank,  slurry  is  also  aerated  and  homogenised  by 
injecting compressed air, to prevent sulphate ions changing into noxious hydrogen sulphide and 
to  improve  the fluidity  of the  slurry  as  part  of  the  dry  matter  content is  degraded.  Part  of  the 
treated  slurry  may  be  used  to  flush  the  storage  pits  under  the  housing  floors,  in  a  sufficient 
quantity to allow 10–15 cm of slurry, ensuring that the pH in the slurry pits is kept at about 5.5. 
In this way, ammonia volatilisation from further dung dropping into pits is inhibited.  

The rest of the treated slurry is pumped from the process tank into a storage tank, from where it 
can  be  transported  and  spread  on  the  field  as  fertiliser  at  a  later  stage.  All  process  steps  are 
automatically controlled and monitored [ 594, Agro Business Park 2011 ]. 

A schematic representation of the slurry acidification system is shown in Figure 4.90. 

Source: [ 228, Denmark 2010 ] 

Figure 4.90:  Schematic representation of a slurry acidification system 

One reported variation of the technique is based on the acidification of the slurry directly in the 
storage tank, by adding sulphuric acid while the slurry is agitated, just before it is transferred to 
the field for landspreading (see Figure 4.91). 

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Chapter 4 

NB: In the picture on the left, the aggregate is agitating the slurry via pumping, while sulphuric acid is added to the 

pipe. In the picture on the right, slurry is agitated by a propeller, while sulphuric acid is added to the pipe. 

Source: [ 599, Denmark 2012 ] 

Figure 4.91:  Systems for slurry acidification directly in the storage tank 

Acidification  can  also  be  applied  continuously  during  landspreading  of  the  slurry.  Sulphuric 
acid is transported and stored in a suitable (officially approved) container mounted on the front 
of the tractor that pulls the liquid manure spreader/slurry tanker (see  Figure 4.92). The acid is 
pumped through pipes, from the container positioned in front of the tractor to the outlet of the 
manure  spreader,  where  the  liquid  manure  is  mixed with the  acid in  a static  mixer before the 
slurry is pumped into the device used to apply the acidified slurry on the soil, such as a trailing 
hose. The system continuously controls the rate of acid being added to the slurry by online pH 
measurement of the acidified slurry. The amount of spread slurry is also continuously measured. 

Source: [ 598, Denmark 2011 ] 

Figure 4.92:  Equipment for slurry acidification during spreading 

Achieved environmental benefits 
Slurry  acidification  strongly  inhibits  ammonia  volatilisation,  by  formation  of  ammonium 
sulphate, from all production stages of pig rearing where acidified slurry can be used: housing, 
storage and landspreading. As a result of inhibition of ammonia  volatilisation, acidified slurry 
retains more nitrogen, making the treated slurry richer in nutrient value, which will eventually 
result  in  measurably  higher  crop  yields  when  spread  as  fertiliser.  The  reduction  of  ammonia 
emissions  significantly  improves  the  air  quality  in  the  animal  houses,  providing  improved 
animal welfare and a better working environment. 

In theory, methane emissions from housing and outdoor storage could be substantially reduced, 
due  to  inhibition  of  methanogenic  bacteria  at  the  low  pH.  Similarly,  potential  nitrous  oxide 

614 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

emissions from storage could be reduced, if acidification prevents a surface crust formation, due 
to the reduced microbial activity in the slurry. 

Cross-media effects 
Handling  strong  acids  on  farms  is  hazardous  [ 508, TFRN  2014  ].  A  fully  automated  system, 
with no manual contact with sulphuric acid and automated management of the slurry (including 
discharging operations), is necessary for safety reasons [ 228, Denmark 2010 ]. Also, corrosion 
may occur [ 571, Eurich-Menden et al. 2011 ]. 

Slurry acidification leads to qualitative changes in odour emissions, rather than an increase in 
overall  odour.  Odour  peaks  can  arise  as  a  result  of  daily  aeration/mixing  and  pumping  of 
manure. There is potential for gaseous hydrogen sulphide emission if sulphate is reduced to H2S 
in stored slurry, provoking odour problems [598, Denmark 2012 ]. If acidified slurry is used in a 
plant  producing  biogas,  there  is  a  theoretical  risk  of  bacterial  inhibition  based  on  the  high 
proportion of acidified slurry. 

The  technique  may  lead  to  marginal  soil  acidification,  increasing  the  need  for  liming.  All 
practical  experience  shows  this  is  a  minor  issue  corresponding  to  less  than  10 %  of  the 
additional liming needed. Theoretically, 1.4 kg lime should be landspread to neutralise each kg 
of sulphuric acid used for slurry acidification. In Denmark, most farmers take soil samples about 
every  fourth  year,  to  estimate  the  need  for  fertilisers  and  lime.  If  acidified  slurry  has  been 
applied within that period of time, a larger amount of lime than usual will have to be added to 
neutralise  the  soil  pH,  but  the  frequency  of  application  does  not  change.  Liming  and 
landspreading  of  acidified  slurry  do  not  necessarily 
time  
[ 598, Denmark 2012 ].  

take  place  at 

the  same 

In  the  case  of  acidification  inside  the  slurry  storage  tank,  due  to  foaming  of  the  slurry,  a 
freeboard of 0.8–1 m is required in the tank; therefore, the storage capacity of the tank cannot be 
fully utilised. 

Environmental performance and operational data 
Untreated slurry has typically a pH of 6.5–8. In order to ensure the reducing effect on ammonia 
volatilisation, the acidification should bring the pH to a level no higher than 6.0. In commercial 
operations, the pH is often brought down to a value of 5.5, in consideration of the instability of 
acidified  slurry  and  its  varying  buffer  effect.  The  target  pH  depends  on  the  time  span  from 
acidification until landspreading. Therefore, slurry that is acidified to a pH below 6.0 should be 
landspread as fertiliser within 24 hours; the pH should be maintained below 5.5 in cases when 
the slurry is not spread on the fields within 21 to 90 days. If spreading of the acidified slurry is 
delayed more than 90 days, then the pH should be verified in order to ensure that it is still less 
than 6.0, or more acid should be added. 

In  general,  the  amount  of  sulphuric  acid  needed  for  a  tonne  of  slurry  is  approximately  2.5–
3 litres, corresponding to about 4.6–5.5 kg of acid [ 599, Denmark 2012 ]. Other sources report 
a  consumption  of  sulphuric  acid  in  the  range  of  5 kg  to  7 kg  for  each  tonne  of  raw  slurry,  to 
reduce the pH to between 5.5 and 6 [ 594, Agro Business Park 2011 ]. 

Installations  are  farm-fitted  with  a  process  tank,  automated  valves,  and  piping  systems  where 
necessary.  The  technology  typically  requires  the  slurry  to  be  treated  only  once.  The  whole 
process  is  fully  automated,  allowing  the  farmer  to  continuously  monitor  all  operational  and 
environmental  aspects  of  the  slurry  management  system  (continuous  measurement  of  pH, 
amount of slurry treated and stored, and status of sulphuric acid supply).  

Comparative  data  from  a  whole-farm  assessment  carried  out  in  Denmark,  concerning  the 
application  of  slurry  acidification,  report  that  gaseous  nitrogen  emissions  produced  per 
growing/finishing  pig  (30–100 kg live weight) without slurry acidification are 0.50 kg N from 
housing,  0.24 kg  N  from  manure  storage,  and  0.25 kg  N  from  application  of  slurry  to  land. 
When using acidified slurry, emissions are 0.15 kg N, 0.03 kg N, and 0.10 kg N, respectively, 

Intensive Rearing of Poultry or Pigs 

615 

 
 
 
 
 
 
 
 
Chapter 4 

for  housing,  storage  and  landspreading.  The  nitrogen  balance  at  the  base  of  the  whole-farm 
assessment  is  presented  in  Figure 4.93,  where  data  for  the  acidified  slurry  are  compared  with 
those for untreated slurry.  

Source: [ 600, P.Kai et al. 2008 ] 

Figure 4.93:  Whole-farm assessment of the slurry acidification effect on the nitrogen available for 

plant uptake 

From  a  whole-farm  assessment  carried  out  in  Denmark  on  the  basis  of  laboratory  tests 
simulating slurry storage, the reduction of methane is reported as being from 3.29 kg to 2.2 kg 
per tonne of  slurry  stored in houses, and 1.94 kg to 0.78 kg per tonne  of slurry in stores.  The 
reduction  of  N2O  is  reported  as  being  from  0.013 kg  to  0.0022 kg  per  tonne  of  slurry  from 
housing, and 0.033 kg to 0.021 kg per tonne of slurry from stores [ 228, Denmark 2010 ]. 

A  total  reduction  of  65–70 %  for  ammonia  emissions  is  also  reported  by  another  source,  for 
housing and slurry storage [ 594, Agro Business Park 2011 ]. An estimated 60 % reduction in 
ammonia  emissions 
landspreading  
[ 508, TFRN 2014 ]. In summary, emissions are reduced by 75 % in houses with fully slatted 
floors, and by approximately 80 % in houses with partly slatted floors. Another 50 % reduction 
is induced in covered storages, 90 % in uncovered storages, and 67 % in landspreading of slurry 
by trailing hoses. 

is  acidified  during 

reported  when 

slurry 

is 

The increased energy, associated with the use of slurry, is estimated as 1.8–3 kWh/m3 of slurry 
[ 594, Agro Business Park 2011 ]. Examples of increased odour problems have been reported as 
occurring locally near the process tank of the acidification unit. Elimination of the problem is 
feasible by mounting a carbon filter in the process tank. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. Around 80 % of 
existing Danish houses can be retrofitted with the technique without major renovations.  

616 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

The alternative of acidification during spreading has not been tested with irrigation systems and 
broadcast spreading. With injection techniques, the effect of the emissions reduction is expected 
to be limited.  

Economics 
The investment required for the installation of one acidification unit for a pig house (which can 
handle  up  to  six  sections,  with  400 m3  of  slurry  each) is  about  EUR 200 000.  The  annualised 
investment  cost  is  around  EUR 13 300,  based  on  a  15-year  depreciation  period.  The  annual 
operating costs consist of the maintenance cost (EUR 2 000), the extra electricity consumption 
(about  3 kWh  per  tonne  of  treated  slurry),  and  the  costs  for  the  sulphuric  acid.  Suppliers' 
estimations of the total annual costs range from EUR 1 to EUR 2 per tonne of treated slurry.  

The extra costs for the technique are reported to vary between EUR 1.4/ap/yr and EUR 7/ap/yr. 
The extra operating costs for the slurry acidification technique, reported by Denmark in relation 
to the number of fattening pigs produced, are presented in Table 4.194.  

Table 4.194:  Cost  data  reported  for  slurry  acidification  in  relation  to  the  number  of  pigs,  in 

Denmark 

Fattening pigs (32–
107 kg) produced 

Total annual 
extra costs (1) 
EUR/yr 

Total extra costs per 
pig produced (2) (3) 
% 
EUR/pig 

Total extra cost per kg N 
reduced incl. value of saved N 
EUR/kg N reduced 

20 130 
22 300 
24 600 
33 000 
41 600 
48 100 

2 700 
5 400 
9 000 
18 000 
27 000 
34 200 
(1) Value of N is excluded. 
(2) Value of saved N is included.  
(3) Reference for production cost: EUR 69 per pig produced. 
Source: [ 594, Agro Business Park 2011 ] 

6.8 
3.4 
2.1 
1.2 
0.8 
0.7 

10 
5 
3 
2 
1 
1 

14.4 
7.5 
4.4 
2.5 
2.0 
1.6 

For a slurry acidification unit treating 10 000 m3 of slurry per year, the breakdown of estimated 
operating costs is reported in Table 4.195.  

Table 4.195:  Operating costs for a slurry acidification unit treating 10 000 m3/yr, in Denmark 

Parameter 

Energy consumption 
Acid consumption 
Maintenance and service  
Total costs 
Source: [ 594, Agro Business Park 2011 ] 

EUR/m3 
0.17 
0.72 
0.29 
1.18 

A  total  additional  cost  of  approximately  EUR 20  per  ha  is  reported  where  acidified  slurry  is 
applied,  for  both  variations  of  slurry  acidification:  in  storage  tanks  and  during  landspreading; 
this extra cost includes depreciation of the investment.  

Driving force for implementation 
The reduction of ammonia emissions significantly improves the air quality in the animal houses, 
providing improved animal welfare and a better working environment. Farmers in Denmark are 
required  to  adopt  low-emission  measures  to  obtain  an  environmental  permit  to  expand  their 
production capacity. The higher  nitrogen content of slurry generates economic benefits due to 

Intensive Rearing of Poultry or Pigs 

617 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

the  lower  use  of  mineral  fertilisers.  The  use  of  slurry  acidification  during  landspreading 
facilitates the application of the acidification technique, since it is not dependent on alterations 
within the pig housing. 

Example plants 
Slurry  acidification  is  reported  to  be  in  operation  in  Denmark  (around  125  farms)  and  Spain 
(over  20  farms  with  medium-  and  large-scale  applications)  [  508,  TFRN  2014  ]  [  595,  Agro 
Business  Park  2011  ].  The  systems  for  slurry  acidification  in  storage  tanks  and  during 
landspreading are relatively new technologies. 

Reference literature 
[  228,  Denmark  2010  ]  [  508,  TFRN  2014  ]  [  571,  Eurich-Menden  et  al.  2011  ]  [  594,  Agro 
Business Park 2011 ] [ 598, Denmark 2012 ] [ 599, Denmark 2012 ] [ 600, P.Kai et al. 2008 ] 

4.12.10  Combustion of poultry litter for energy recovery 

In  general,  on-farm  combustion  plants  for  poultry  litter  have  capacities  below  the  threshold 
value of three tonnes per hour set by the Industrial Emissions Directive (2010/75/EU), Annex I, 
Activity  5.2:  'Disposal  or  recovery  of  waste  in  waste  incineration  plants  or  in  waste  co-
incineration plants for non-hazardous waste'.  

Description 
Untreated  deep  poultry  litter,  the  solid  fraction  from  slurry  mechanical  separation,  thermally 
dried or other solid manure with a low moisture content can be combusted and converted into 
energy. The recovered thermal energy can also be transformed into electricity.  

Air  (oxygen)  is  introduced  in  excess  to  thermally  oxidise  (T  > 900 °C)  carbon,  hydrogen  and 
sulphur contained in manure's organic matter. In the case of complete combustion, all volatile 
solids are transformed to gases and the ashes will contain only inorganic material. If combustion 
is not complete (insufficient oxygen or low degree of turbulence), volatile solids can be found in 
the ashes  and  CO  in the  exhaust  gases.  Once the  installation  has  started,  no additional fuel  is 
necessary to incinerate the litter given its DM content of 55 %. 

A steam generator is used to recover thermal energy. The steam generated can be transformed to 
electricity in a steam turbine. For manure with a high moisture content, a previous drying (and 
pelletising)  process  may  be  appropriate in  order to  increase  the  energy  efficiency  of  the  plant 
[ 594, Agro Business Park 2011 ]. 

Different types of furnaces can be used, such as grate incinerators, rotary kilns or fluidised bed 
reactors.  See  the  WI  BREF  for  more  detailed  information  about combustion technologies  and 
thermal treatment systems [ 705, COM 2017 ].  

Conventional combustion chambers (grate incinerators) 
Broiler litter is automatically fed from storage into a first combustion chamber at a temperature 
of 400 °C, where it is gasified on a moving  grate by an airflow supplied at the bottom of the 
litter  layer.  During  the  gasification  process,  the  poultry  litter  is  transported  over  the  grate 
through  a  second  combustion  chamber  where  the  mixture  is  rapidly  heated,  (i.e.  within 
3 seconds), up to a temperature of 1 000 °C to 1 200 °C with a controlled oxygen supply.  The 
hot  flue-gases  leaving  the  second  chamber  go  through  a  heat  exchanger,  in  which  water  is 
heated to a temperature of about 70 °C. 

Fluidised bed combustion 
Combustion  air  is  blown  from  below  through  a  'bed'  of  sand  or  other  inert  material  at  a  high 
enough velocity to keep the material suspended. The sand is preheated to raise the temperature 
so that incoming material will ignite and burn efficiently. The constantly moving mass provides 
good heat transfer within the bed, which helps to deal with the high ash and variable moisture 

618 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

content. Fluidised beds suspend solid fuels on upward-blowing jets of air during the combustion 
process.  The  result  is  a  turbulent  mixing  of  fuel,  gas  and  solid  sand  particles.  The  tumbling 
action  provides  more  effective  chemical  reactions  and  heat  transfer  [  553,  bhsl  2011  ]  
[ 500, IRPP TWG 2011 ]. 

A tall furnace maintains combustion gases at a temperature over 850 °C for over 2 seconds in 
accordance with the Animal By-Product Regulation (EC) 1069/2009. Temperature is regularly 
monitored. The retention time is calculated based on the flow rates of gas and the height of the 
stack.  

The litter is transferred from poultry sheds to a bio-secure storage area, from where no further 
contact takes place with the farm production or operatives. The fuel is automatically transferred 
into the combustion chamber and the whole process is remotely managed. The heated water that 
is produced after the combustion is used for heating production houses. 

Achieved environmental benefits 
The combustion of poultry litter as fuel for the production of heat allows for the substitution of 
fossil  fuels  with  renewable  sources.  The  calorific  value  of  poultry  litter  is  reported  to  range 
between 10.8 MJ/kg and 12 MJ/kg of dry matter [ 564, bhsl 2012 ] [ 553, bhsl 2011 ] in the UK 
and between 14 MJ/kg and 16 MJ/kg of dry matter in Belgium (Flanders) [ 256, VITO 2006 ].  

The  main  factor  affecting  energy  recovery  is  the  water  content  of  the  manure.  Based  on  data 
from incinerators in the UK, the combustion of poultry manure can produce about 500 kWh of 
electrical energy from each tonne of chicken manure with 60 % dry matter [ 256, VITO 2006 ]. 

Changing  from  indoor  LPG  or  propane  combustion  to  biomass  heating  reduces  moisture 
production and therefore humidity in the poultry houses, thus avoiding the generation of a damp 
atmosphere and the acceleration of NH3 formation from droppings. The reduced humidity in the 
houses  also  enables  a  more  efficient  management  of  the  ventilation  and  reduced  litter 
requirements (up to 20 %).  

Another benefit of this technique is the production of an ash that can be used as a fertiliser since 
it is rich in phosphorus and potassium. However, the availability of phosphate to crops is still 
under study [ 594, Agro Business Park 2011 ] [ 256, VITO 2006 ]. 

Cross-media effects 
There  is  a  potential  risk  of  emissions  (e.g.  NOX,  SOX,  H2S,  HCl,  PCDD  and  PCDF,  dust, 
metals). Equipment to control emissions from the combustion process  is required in all cases. 
Odour emissions are low due to the high temperatures achieved in the combustion chamber. SO2 
emission can be limited as a result of added chalk. Losses of nutrients and organic  matter are 
due  to  manure  combustion,  which  have  to  be  replaced  by  manufactured  mineral  fertilisers  
[ 624, IRPP TWG 2013 ]. 

The  flue-gases  are  filtered  through  a  dust  filter  that  reduces  the  dust  concentration.  Ashes 
removed  by  the  air  cleaning  system  have  to  be  disposed  of  in  controlled  landfills  
[ 594, Agro Business Park 2011 ].  

Environmental performance and operational data 
Poultry  litter  comprises  a  heterogeneous  mixture  of  manure,  bedding  material,  waste  feed, 
broken  eggs  and  feathers  removed  from  the  poultry  sheds.  The  composition  seems  consistent 
enough  over  geographic  areas  due  to  animal  by-product  rules  and  the  industry’s  own  quality 
production  standards  (e.g.  bedding  materials  and  feed  used).  The  technique  results  in  a 
substantial reduction of volume and mass (70–90 % mass reduction). This residue can be sold as 
fertiliser. 

Reported fluidised bed combustion units have a range of capacities of 2.4 tonnes, 5.5 tonnes and 
12–13 tonnes  per  day  of  litter  manure,  with  thermal  outputs  from  200 kWh  to  995 kWh.  Any 

Intensive Rearing of Poultry or Pigs 

619 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

fall  in  combustion  temperature  is  detected  by  the  automatic  control  system  that  allows 
supplementary fuel to be used to keep the operating temperature at 850 °C. This temperature is 
required  to  ignite  moist  fuels,  to  prevent  the  agglomeration  of  potassium,  to  achieve  100 % 
combustion  of  fixed  carbon,  and  to  thermally  decompose  all  organic  pollutants  present  in 
poultry litter. 

Examples of associated emission levels from a fluidised bed combustion plant for poultry litter, 
in comparison with the combustion of virgin wood shavings, are given in Table 4.196. Data are 
compared with the emission limit values (ELVs) for waste incineration plants set by Directive 
2010/75/EU,. The plant used for combustion of the poultry litter has a capacity of 5 tonnes/day, 
a thermal output of 500 kW of heat and 50 kW of electricity (wood shavings used as bedding 
material).  The  plant  is  equipped  with  a  dust  abatement  system  and  continuous  monitoring  of 
emissions.  

Table 4.196:  Achievable emission levels from a fluidised bed combustion plant for poultry litter, in 
comparison with fresh wood shavings and ELVs set by Directive 2010/75/EU for waste 
incineration plants  

Parameter 

Unit 

NOX 
SO2 
Dust 
Heavy metals  
Mercury 
Cd and Tl 
Dioxins and furans 
PAH 

mg/Nm3 
mg/Nm3 
mg/Nm3 
mg/Nm3 
mg/Nm3 
mg/Nm3 
ng/Nm3 
g/Nm3 
mg/Nm3 

Directive 2010/75/EU 
ELVs  
(daily average) (1) 

400 
50 
50 (3)  
0.5 
0.05 
0.05 
0.1 
Value not specified 

Associated emission levels 

Emissions from 
poultry litter (2) 

359.86 
0.03 
0.97 
0.04 
0 
0 
0.09 (4) 
40.40 

Emissions from 
virgin wood 
shavings 
380.91 
5.21 
56.13 
NI 
NI 
NI 
NI 
NI 

CO 
(1) All values refer to standard conditions: temperature 273.15 K, pressure 101.3 kPa, dry gas. Concentrations are 

88.71 

30.67 

100 

corrected to reference conditions of 11 vol-% oxygen. 

(2) Bedding material: virgin wood shavings with < 40 % moisture content. 
(3) Emission limit value for co-incineration of biomass (waste). 
(4) Euro environmental emissions data. 
NB: NI = no information provided. 

Source: [ 553, bhsl 2011 ] 

NOX emissions ranging from 258 mg/Nm3 to 498 mg/Nm3 at 6 % O2 are reported from Belgium 
(Flanders).  Several  techniques  are  available  for  controlling  solid  and  gaseous  emissions  from 
combustion plants applied for incinerating poultry litter. The techniques are described in detail 
in the WI BREF [ 705, COM 2017 ]. 

Technical considerations relevant to applicability 
No  technical  limitations  are  reported  to  its  application  on  a  farm  scale;  however,  the  energy 
recovery  from  manure  with  a  high  moisture  content  may  not  be  sufficient  to  justify  the 
implementation of the technique. For manure with a dry matter content below 30 %, the process 
would result in a net energy consumption. For a dry matter content of 30 % and above, energy 
can,  in  theory,  be  recovered  in  a  well-designed  combustion  plant,  with  higher  net  energy 
production  for  dry  matter  contents  of  about  60 %.  If  pre-drying  of  the  manure  is  needed,  the 
applicability of the technique should be assessed on a case-by-case basis.  

High investment costs for emission control equipment and detailed measurements, requested for 
compliance with Chapter IV of Directive 2010/75/EU, make the technique difficult for farms to 
apply.  

620 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Economics 
Cost data are reported for an farm in the UK with an annual capacity of around 3 200 tonnes of 
poultry  litter,  75 %  of  which  (around  2 400  tonnes)  comes  from  a  farm  with  378 000  broiler 
places. The plant operates 5 976 hours per year, producing hot water which is piped to the bird 
houses  to  heat  the  next  batch  of  broilers.  The  approximate  investment  costs  amount  to 
EUR 1.58 million  (based  on  EUR 1 =  GBP 0.88),  which  comprises  the  following  [  564,  bhsl 
2012 ]: 

 

 

 

Plant and fuel handling: EUR 810 000. This includes the installation of the fluidised bed 
combustion system, all material and labour costs. 

Building  a  bio-secure  fuel  storage  area:  EUR 160 000.  This  automatically  conveys  the 
litter to the combustion unit without contact from farm staff.  

Heating  network  (water  supply,  buffer  tanks,  internal  and  external  piping,  pumps  and 
controls, etc.): EUR 510 000. This refers to the heating infrastructure that stores, pumps 
and delivers heat into the poultry houses, including all installation and materials. 

 

Project management and contingency: 7.5 % of expenditure. 

The  payback  time  of  the  above  investment,  on  a  farm  using  LPG  as  the  energy  source,  is 
reported to be 3.64 years and the free cash flow over 10 years is EUR 4.7 million, taking into 
account the following assumptions:  

1. 

2. 

3. 

approximately 10 % of the litter used in the plant is recovered as ash, having a value after 
transportation of around EUR 68 per tonne;  
UK incentives equivalent to EUR 53 per MWh of heat used for the first 1 313 MWh each 
year, followed by EUR 22 for each subsequent MWh [ 564, bhsl 2012 ]; 
benefits deriving from improved housing conditions for the birds (from optimised heating 
and ventilation) and consequent better performance. 

For  an  installation  that  is  operated  for  about  5 000  hours  per  year  and  a  yearly  input  of 
2 500 tonnes  of  manure,  the  gross  operating  costs  are  reported  to  be  about  EUR 18/tonne  of 
litter,  based  on  cost  data  and  emissions  monitoring  requirements  [  565,  NFU  2012  ]. 
Comparable costs are reported for a farm with a capacity of 0.5 tonnes manure per hour, with a 
dry matter content of 55 %. Investment costs in the range of EUR 300 000–350 000 are reported 
from  Belgium  (Flanders),  with  operating  costs  of  EUR 18  per  tonne,  assuming  an  annual 
operation of 5 000 hours [ 256, VITO 2006 ].  

An  approximate  estimation  of  the  investment  cost  for  the  required  emission  monitoring 
equipment and testing, in order to comply with Directive 2010/75/EU, Annex VI, Part 6, is in 
the  range  of  EUR 130 000–150 000.  These  costs  may  be  considered  too  high,  making  the 
technique unviable and unsustainable for small, farm-scale plants [ 553, bhsl 2011 ].  

Driving force for implementation 
Farms can become self-sufficient in heat supply.  Excess heat, not needed by the farm, can be 
supplied  to  a  local  public  heating  system  or  used  to  generate  electricity.  The  sales  of  energy 
will,  therefore,  bring  revenue,  depending  on  individual  EU  Member  State  regulations  and  the 
market price.  

Example plants 
In general, incineration of solid manure is a technology growing within the broiler production 
sector [ 264, Loyon et al. 2010 ]. The technique is applied in Germany. In the Netherlands, one 
large centralised installation is in operation, with an installed capacity of 36 MW, designed to 
transform 420 000 tonnes of poultry litter (with a minimum dry matter content of 55 %) per year 
into electricity (240 GWh annually) and reusable minerals for agriculture. Farmers from all over 
the country can bring their poultry litter to be incinerated. A large-scale centralised installation 
was  also  reported  from  the  UK,  where  12.7 MW  are  produced  using  approximately 

Intensive Rearing of Poultry or Pigs 

621 

 
 
 
 
 
 
 
Chapter 4 

140 000 tonnes of litter per year. Around 30 % of broiler and turkey litter is sent for incineration 
in England [ 648, DEFRA 2011 ]. 
In  France,  companies  attempted  to  set  up  systems  of  smaller  dimensions;  however,  no 
installation  of  this  kind  has  been  successful  due  to  technical  and  legislative  problems  
[ 259, France 2010 ].  

In  2010,  a  small-scale  fluidised  bed  combustion  system  was  installed  in  Norfolk,  England 
operating on virgin wood chips and awaiting appropriate regulation to operate with poultry litter 
[ 565, NFU 2012 ]. Around 30 % of broiler and turkey litter is sent for incineration in England 
[ 648, DEFRA 2011 ]. 

Reference literature 
[ 256, VITO 2006 ] [ 259, France 2010 ] [ 264, Loyon et al. 2010 ] [ 409, VITO 1997 ] [ 500, 
IRPP TWG 2011 ] [ 553, bhsl 2011 ] [ 564, bhsl 2012 ] [ 565, NFU 2012 ] [ 594, Agro Business 
Park 2011 ] [ 624, IRPP TWG 2013 ] [ 648, DEFRA 2011 ] 

4.12.11  Ammonia stripping 

Description 
Removal  of  ammonia  is  achieved  through  volatilisation  from  a  liquid  phase,  by  means  of  pH 
and temperature increase and a gaseous counter-flow (air or steam), and subsequent recovery by 
absorption in an acidic solution as ammonium salt or by condensation.  

The  liquid  phase  is  charged  in  the  upper  part  of  a  vertical  column  (stripping  tower),  where  a 
stripping gas is introduced from the bottom (air or steam for ‘air stripping’ or ‘steam stripping’). 
The  gas  flows  through  the  column  countercurrently  to  the  liquid,  thus  extracting  ammonia 
(stripping)  in  gas  form.  To  enhance  the  liquid-gas  contact,  the  columns  are  filled  with 
specifically shaped pieces of inert material (packed column). The treated  liquid is collected at 
the  bottom  of  the tower and  the  ammonia-loaded  gases  leave  the tower  at the  top,  for  further 
treatment.  

Stripped  ammonia  is  recovered  by  absorption  in  a  second  column  (absorber),  where  the 
ammonia-laden gases are washed countercurrently with acid solution (e.g. sulphuric acid, iron 
sulphates,  iron  oxides)  to  dissolve  ammonia  and  to  produce  a  concentrated  ammonium  salt 
solution. In steam stripping, the output gas from the stripping tower is condensed to eventually 
produce  a  water  solution  of  ammonia.  The  end  product  of  the  technology  can  be  used  as  a 
fertiliser. 

Achieved environmental benefits 
The removal of ammonia from the slurry results in a mitigation of potential ammonia emissions. 
During slurry landspreading, odours are also reduced. Nitrogen is recovered in a concentrated 
form as a salt or in a liquid solution, therefore nutrient management is easier and transport costs 
are reduced.  

Cross-media effects 
Energy  consumption  is  increased.  Depending  on  the  working  temperature,  heating  energy 
requirements may play a primary role in energy consumption [ 594, Agro Business Park 2011 ]. 

Environmental performance and operational data 
The two fundamental control parameters of the process are the temperature and the pH, as they 
+). The pH is usually set 
establish the equilibrium between ammonia (NH3) and ammonium (NH4
between 9 and 10, by adding an alkaline solution of soda or lime, or by previous CO2 stripping, 
so that ammonia can be released as a gas. For air stripping, typical working temperatures are set 
below 100 °C, whereas higher temperatures are characteristic of steam stripping. An ammonia 
reduction of up to 95 % is reported, under optimal conditions [ 594, Agro Business Park 2011 ]. 
Organic nitrogen, nitrites and nitrates are not removed.  

622 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

The electricity consumption for air stripping is dependent on the process temperature, since, at 
higher temperatures, less air needs to be sent through the column. The consumption of electrical 
energy  is  reported  from  Belgium  (Flanders)  as  2.3 kWh/m3  of  liquid,  if  the  process  is  run  at 
20 °C, and 0.85 kWh/m3 if the operating temperature is 50 °C. The energy consumption for the 
stripping column only is reported as 14 kWh/kg of stripped nitrogen [ 594, Agro Business Park 
2011 ]. In the case of steam stripping, the electricity consumption is 0.45 kWh/m3 liquid, while 
the consumption for thermal energy is equivalent to the production of 100 kg of steam per m3.  

Technical considerations relevant to applicability 
The  quality  of  the  ammonia  salts  or  ammonia  concentrate  obtained  increases  when  volatile 
organic  matter  has  been  previously  removed.  Therefore,  mechanical  separation  of  the  solid-
liquid fractions is usually required as a pretreatment, to reduce the dry matter content and avoid 
clogging. 

The  technique  may  be  used  in  combination  with  anaerobic  digestion,  as  a  pretreatment  that 
improves  the  ammonia  stripping  efficiency,  reduces  contamination  of  the  final  product  by 
organic  matter,  and  provides  energy  and  heat  required  for  the  process.  Due  to  the  high  heat 
demand, the technique may not be economically sustainable if heat from biogas production is 
not available [ 624, IRPP TWG 2013]. 

Economics 
Investment  costs  are  reported  from  Italy  as  EUR 350 000.  For  a  plant  located  in  Slovenia, 
treating 15 m3/h of slurry, the estimated investment cost for the stripping column was reported 
to be EUR 250 000 [ 594, Agro Business Park 2011 ].  

For  a  mobile  unit  combining  a  centrifugal  solid-liquid  separator  and  ammonia  stripping 
equipment, followed by a catalytic ammonia process, investment costs are reported to be in the 
range of EUR 350 000–400 000. The related operating costs are EUR (125  2) per m3 of treated 
slurry, for the displacement of the integrated mobile unit, EUR 3.10 per m3 for the separation 
stage,  and  EUR 4.46–4.95  per  m3,  for  ammonia  stripping  plus  the  catalytic  oxidation  stage 
[ 256, VITO 2006 ] [ 529, Veneto Agricoltura 2012 ]. 

Operating  costs  have  been  reported  as  EUR 2.5–4.5  per  kg  of  stripped  nitrogen  (only  for  the 
stripping  column).  For  the  absorption  stage,  at  least  an  equivalent  range  of  costs  should  be 
considered.  In  Denmark,  ammonia  stripping  is  considered  disproportionately  expensive  [  499, 
AgroTech 2008 ].  

Driving force for implementation 
Both liquid ammonia solution or solid ammonia salts obtained by condensation and evaporation 
can be used directly as fertilisers, as feedstock in the fertiliser industry or sold to other industrial 
applications  (e.g.  waste  water  treatment  in  the  paper  industry).  The  reported  income  is  up  to 
EUR 0.35  per  kg  of  nitrogen  recovered  in  a  0.1  ammonium  sulphate  solution,  to  be  sold  to 
fertiliser manufacturers. The end product concentrate (which contains phosphorus and nitrogen) 
is partially hygienised (depending on the operation time/temperature).  

Example plants 
In Belgium (Flanders), a mobile system is in use. A farm in Slovenia and one in Italy (with an 
annual  capacity  of  32 000 tonnes  of  manure)  are  also  reported  to  operate  the  technique  
[ 594, Agro Business Park 2011 ] [ 595, Agro Business Park 2011 ].  

Reference literature 
[  256,  VITO  2006  ]  [  499,  AgroTech  2008  ]  [  529,  Veneto  Agricoltura  2012  ]  [  594,  Agro 
Business Park 2011 ] [ 595, Agro Business Park 2011 ] [ 624, IRPP TWG 2013 ] 

Intensive Rearing of Poultry or Pigs 

623 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.12.12  Manure additives 

Description 
Manufactured  or  naturally  occurring  products  or  substances  are  added  to  manure  or  feed  to 
change  the  biological,  chemical  or  physical  properties  of  manure.  The  objectives  for  the 
addition of each additive may be different: reducing ammonia and odour emissions, improving 
the  indoor  environment  in  animal  housing,  stabilising  pathogenic  microorganisms  and 
preventing  insects'  development,  increasing  the  fertilising  value  of  the  manure,  or  facilitating 
the  handling  and  use  of  manure  by  increasing  its  fluidity.  The  use  of  some  specific  feed 
additives is covered in Section 4.3.6.  

Many types and categories of manure additives are commercially available. These include:  

 

 

 

 

 

 

 

 

masking and neutralising agents; 

absorbents; 

urease inhibitors; 

pH regulators; 

oxidising agents; 

flocculants; 

disinfectants and antimicrobials; 

biological agents. 

Achieved environmental benefits 
A better use and management of manure on the farm can be achieved with a more homogeneous 
manure,  namely  because  having  greater  homogeneity  makes  it  easier  to  dose  the  manure  in 
landspreading. A lesser volume of manure can be produced due to less water being used in the 
easier cleaning of the pits. In some cases, a decrease in ammonia and odour emissions could be 
achieved.  Savings  of  energy  are  possible  because  of  a  reduced  use  of  cleaning  machines. 
Savings  in  water  are  also  achieved.  Specific  potentially  achieved  environmental  benefits  are 
also reported under 'Environmental performance and operational data'. 

Cross-media effects 
No significant cross-media effects have been reported. Specific cross-media effects are reported 
under 'Environmental performance and operational data'. 

Environmental performance and operational data  
One  of  the  main  problems  is  the  lack  of  standard  techniques  to  test  and  analyse  the  results. 
Another problem with their use is that many trials have only been developed under experimental 
conditions in laboratories and not on-farm, where large variations in nutrition, the management 
of  nutrition,  pH  and  temperature  can  be  found.  Besides  this,  there  is  also  sometimes  a  huge 
volume  of  manure  to  be  mixed  with  the  additive  in  a  pit  or  lagoon,  and  the  results  achieved 
often depend a lot more on the mixing efficiency than on the lack of efficacy of the additive. 
Improving the flow characteristics seems to be strongly related to a good mixing. 

The effectiveness of each additive is highly dependent on the correct dosing, right timing and 
good  mixing  with  the  manure.  It  is  also  reported  that  satisfactory  results  are  not  always 
achievable  [  561,  Flotats  et  al.  2004  ]  [  499,  AgroTech  2008  ].  For  example,  trial  results  in 
France demonstrated that the efficiency of slurry additives aiming to reduce ammonia and odour 
emissions from pig housing is not consistent, and it varies according to the product and season 
(e.g.  efficiency  for  odour  abatement  ranged  from  0 %  to  40 %)  [  257,  France  2010  ]  
[ 259, France 2010 ]. In general, for most of the manure additives, the effects documented by 
scientific trials are poor so their effectiveness is uncertain [ 594, Agro Business Park 2011 ]. 

624 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 

 

Chapter 4 

Masking  and  neutralising  agents.  These  are  a  mix  of  aromatic  compounds  (e.g. 
heliotropin, vanillin) with a strong scent that work by either masking the manure odour 
with  a  more  pleasant  odour  or  neutralising  the  odorous  volatile  compounds.  The 
effectiveness of masking agents is difficult to predict due to varying odour characteristics 
and  changing  weather  conditions.  The  individual  constituents  of  odours  remain 
unchanged and the additive tends to separate from the odour downwind. Masking agents 
are susceptible to degradation by the microorganisms in the slurry. Frequent application is 
required [ 560, IGER 2000 ]. Masking agents can also be added to the feed (e.g. artemisia 
extract, mint oil) [ 561, Flotats et al. 2004 ]. 

Absorbents. There  are a  large  number  of  substances  such  as  peat  or  clay  minerals  (e.g. 
zeolite) that depend on physical absorption (e.g. for  ammonia, odorous compounds) for 
their  effect.  These  materials  have  a  high  surface  area  and  the  quantities  required  for 
effective abatement could be very large [ 561, Flotats et al. 2004 ] [ 624, IRPP TWG 2013 ]. 
Some types of zeolites called 'clinoptilolites' can be added either to the manure or to feed 
+.  Clinoptilolites  have  been 
for their  high  cation  exchange  capacity  and  affinity  for  NH4
extensively  studied,  but  results  of  nitrogen  binding  are  controversial  and  costs  are 
relatively  high  [  151,  Link  CR  2005  ]  [  205,  ADAS  2000  ].  An  increase  in  ammonia 
emission  in  duck  rearing  was  reported  in  association  with  the  use  of  clinoptilolites  
[  152,  Link  CR  2006  ].  The  use  of  other  clay  minerals,  such  as  bentonite,  has  been 
reported as having odour-reducing effects [ 560, IGER 2000 ] [ 561, Flotats et al. 2004 ]. In 
experiments with the addition of zeolite and bentonite to pig slurry, it has been found that 
microbial activity sharply decreases, with a consequent reduction of odorous substances 
released by manure. Other reported results of trials  carried out in Denmark suggest that 
the addition of a rock mineral containing silicon, derived from zeolite, had no effect on 
odour  or  ammonia  emissions  [499,  Agro  Tech  2008].  The  substances  mentioned  above 
are also able to improve soil structure and have the added benefit that they are not toxic or 
hazardous. Peat gives similar results and is also sometimes used. However, the extraction 
of peat is associated with significant biogenic CO2 emissions.  

 

Urease inhibitors. These compounds stop the degradation of urea, which is contained in 
the urine, to ammonium, the breakdown of which releases ammonia. There are three main 
types of urease inhibitor: 

o 

o 

o 

Phosphoramides. Applied directly to the soil, they show a good effect. They work 
better in acid soils, but could affect soil microorganisms. 

Yucca extract (Y. schidigera). Many trials have been done to assess its potential but 
the information available is controversial, showing good results in some cases, but 
no effect at all in others. It is added in the feed and not absorbed by the animals; 
thus, it reaches manure in a uniform way. There is also evidence that it improves 
the  feed  conversion  ratio  and  weight  gain.  Nevertheless,  the  way  these  additives 
function is not well investigated [ 561, Flotats et al. 2004 ] (see Section 4.3.6.4). 

Straw,  considered  an  adsorbent  in  many  references.  However,  besides  the 
absorbing effect, it also increases the C : N ratio. Its use is controversial because in 
many works it shows an increase in ammonia emissions.  

 

pH regulators. There are three main types: 

o 

Acidifying  agents.  Inorganic  acids  (phosphoric,  hydrochloric,  sulphuric)  or 
chemical compounds that decrease the pH of liquid manure. The addition of acids 
(e.g. H2SO4) for lowering the pH (pH 4 to 5) keeps nitrogen in the NH4 form which 
does  not  volatilise  as  ammonia;  it  slows  down  the  activity  of  methanogenesis 
bacteria preventing the formation of CH4 and allowing the carbon to remain in the 
manure  [  228,  Denmark  2010  ].  More  details  are  given  in  Section  4.12.9.  In  the 
case  of  broiler  litter,  aluminium  sulphate  has  been  used  to  reduce  the  pH  of  the 
litter; 
this  will  reduce  ammonia  emissions  during  housing,  storage  and 
landspreading and precipitate P into a form that is not water-soluble which is less 
susceptible  to  soluble  P  loss  in  run-off.  Aluminium  sulphate  is  added  to  poultry 

Intensive Rearing of Poultry or Pigs 

625 

Chapter 4 

o 

o 

litter at a rate equivalent to 5–10 wt-%, which is equivalent to adding 50–90 g per 
bird [ 648, DEFRA 2011 ] [ 508, TFRN 2014 ]. 

Lime.  Lime  addition  stabilises  manure  and  reduces  the  content  of  pathogens.  By 
mixing quicklime (CaO) with solid manure, the temperature rises exothermically to 
between  55 °C  and  70 °C  and  the  pH  increases  to  9–11,  with  a  resulting 
bactericidal effect which blocks fermentation in litter. The reactive lime used in the 
process promotes drying of the manure; it is also a 'liming agent' for changing the 
soil pH, in view of manure application. 

Ca and Mg salts. These salts interact with manure carbonate, decreasing the pH and 
therefore  reducing  the  potential  for  ammonia  emissions.  They  could  increase  the 
fertilising  value  of  the  manure  but  could  also  increase  the  salinity  of  the  soil 
(chlorides).  They  are  used  mainly 
in  combination  with  other  additives. 
Superphosphate (mixture of calcium salt and orthophosphoric acid)  is the product 
most often used in poultry farms; it has a draining action on the litter. It has been 
used in doses of 100–200 g/m2 and remains active over five days. Superphosphate 
and  phosphoric  acid  were  studied  in  poultry  farms  in  France,  as  inhibitors  of 
microbial  growth  [  259,  France  2010  ].  On  the  other  hand,  the  addition  of 
phosphorus  to  manure  may  represent  a  local  problem,  where  specific  regulations 
concerning phosphorus are applied (e.g. in the Netherlands). 

 

Oxidising agents. These are intended to have a similar effect to aerobic treatment. Their 
effects are through: 

o 

o 

oxidation of the odour compounds (e.g. sulphides); 

providing  oxygen  to  aerobic  bacteria;  aerobic  conditions  promote  oxidation  of 
hydrogen sulphide and other malodorous gases by microorganisms; 

inactivating the anaerobic bacteria that generate odorous compounds. 

o 
The  most  active  oxidising  agents  are  hydrogen  peroxide,  potassium  permanganate, 
chlorine gas, or sodium hypochlorite. They are hazardous and not recommended for farm 
use. Some of them (e.g. formaldehyde) could be carcinogens. Ozone (O3) is also used as a 
strong  oxidant  that  can  react  with  specific  odorous  compounds  in  the  slurry  and  also 
reduce  microbial  activity.  Its  use  to  treat  the  slurry  results  in  a  pH  increase,  with 
consequent increased ammonia emissions and a lower fertiliser value of the treated slurry. 
Ozone treatment can be combined with acidification. Ozone application has demonstrated 
its efficacy, but operating costs are very high. 
Flocculants.  These  are  mineral  compounds  (ferric  or  ferrous  chloride  and  other  iron  or 
zinc salts) or organic polymers. These additives react with sulphides [ 561, Flotats et al. 
-3 in the liquid stream, generating an 
2004 ] and reduce BOD, suspended solids, and PO4
insoluble precipitate, usually with a high content of P (see Section 4.12.2.4). 

Disinfectants  and  antimicrobials.  These  are  chemical  compounds  that  are  intended  to 
have  a  sanitation  effect  on  liquid  manure.  Consequently,  they  inhibit  the  activity  of  the 
microorganisms  involved  in  odour  generation.  They  are  expensive  to  use,  and  with 
sustained use an increase in dosing is needed.  

Biological  agents.  The  addition  of  microorganisms  and  nutrients  in  the  slurry  increases 
the  microbial  activity,  which  degrades  organic  matter  not  digested  by  animals.  In 
addition,  odorous  substances  are  reduced  and  N  is  transformed  to  its  organic  form. 
Furthermore, thinner slurry is expected, which is easier to handle and deliver. Nutrients 
may  be  fats,  sugars,  or  extracts  from  plants  and  algae  [  499,  AgroTech  2008  ]  [  561, 
Flotats et al. 2004 ]. Biological agents are available as lyophilised preserved cultures or 
live  cultures  of  natural  strains  or  adapted  decomposition  strains  (stimulators  of 
microorganisms that are naturally present in the substrates). They can be divided into the 
following: 

o 

Enzymes. Enzymes are complex protein structures, promoting catalytic regulation 
and direct/indirect stimulation of biochemical processes and decomposition of the 

 

 

 

626 

Intensive Rearing of Poultry or Pigs 

organic structures [ 287, Jelínek et al. 2007]. Their use is to liquefy solids. They are 
not  hazardous.  The  actual  effect  depends  strongly  on  the  type  of  enzyme,  the 
substrate and proper mixing. 

o 

Bacteria (see also Section 4.8.6): 

Chapter 4 

  Exogenous strains. Their competition with natural strains makes getting 
good  results  more  difficult.  Their  use  is  better  in  anaerobic  pits  or 
lagoons  to  reduce  the  organic  matter  producing  CH4  (sowing  of 
methanogenic  bacteria  is  more  efficient  and  sensitive  to  pH  and 
temperature).  The  efficacy  is  high  but  frequent  resowing  has  to  be 
carried out. 

  Natural  strains  adding  carbonate  substrates  (increased  C : N  ratio). 
Their  effect is  based  on the  use of ammonia  as  a  nutrient,  but  natural 
strains of bacteria need a sufficient source of C to develop an efficient 
synthesis process, changing ammonia into the organic  nitrogen of cell 
tissue.  Resowing  has  to  be  carried  out  too,  to  avoid  reverting  to  the 
starting  point.  They  are  not  hazardous  and  no  significant  cross-media 
effects have been reported. 

o 

Some  biotechnological  agents,  containing  a  selected  absorbent,  adsorb  odour 
substances  or  other  harmful  gaseous  catabolites  of  organic  matter  decomposition. 
According  to  their  nature,  biotechnological  agents  can  be  applied  to  the  feed  or 
drinking  system,  litter,  floor  or  under  slats.  New  biotechnological  agents  are 
marketed  to  reduce  ammonia  and  greenhouse  gases,  but  their  efficacy  is 
controversial  and  should  be  verified  on  a  case-by-case  basis  [  287,  Jelínek  et  al. 
2007]. The way these additives function is not well investigated [ 561, Flotats et al. 
2004 ]. 

Of all the additives described, those aimed at changing the physical properties of the manure to 
make  it  easier  to  handle,  in  particular  biological agents,  are  most  commonly  used  at  the  farm 
level,  and  in  most  cases  have  a  positive  effect.  These  additives  are  not  hazardous.  Their  use 
results in an increase in manure flow, the elimination of natural crusts, a reduction of soluble 
and suspended solids and a reduction in the stratification of the manure. However, these effects 
were  not  demonstrated  in all,  comparable,  cases. Moreover, the  increased  homogeneity  of the 
manure facilitates its agricultural use (i.e. allowing for better dosing).  

A summary of the main characteristics reported for the different groups of manure additives is 
given in Table 4.197. 

Intensive Rearing of Poultry or Pigs 

627 

 
 
 
 
Chapter 4 

Table 4.197:  Summary of the main characteristics for different groups of manure additives 

Type of additive 

Characteristics 

Advantages 

Aromatic oils with a 
strong odour that 
masks manure's 
odours 

  Quick effectiveness 
  Low cost 
 

Simple and safe to 
use 

Aromatic oils that 
neutralise the volatile 
compounds causing 
odours 

  Relatively quick 
effectiveness 
Simple and safe to 
use 

 

 

Disadvantages 
Short-term 
efficiency and not 
predictable 
  No effect on 
ammonia 
  Highly variable 

efficacy, difficult to 
reproduce 
  No effect on 
ammonia 

Masking agents 

Blocking/Neutralising 
agents 

Absorbents 

Chemical additives 

Compounds with a 
high surface area that 
absorb odorant 
compounds 
  Oxidising agents 
 
Precipitating 
agents 
pH control 
agents 

 

  Electron 
acceptors 

  Can reduce odour 
under specific 
circumstances 

  Highly variable 
efficacy 

  Can have 

undesirable effects 
on other compounds 

  Occasionally, 

dangerous products 
or difficult to 
manipulate 

  Very variable 
efficacy, not 
reproducible 
  Efficacy on-farm 
not as good as in 
laboratory trials 

  Can reduce 

emissions of some 
compounds 

  Can reduce odour 
and gaseous 
emissions 
  Can reduce crust 
formation and 
improve fluidity 

  Can transform 

ammoniacal N into 
organic N 
  Can improve 

efficiency of solid-
liquid separation of 
slurry 

Microbiological agents 

Bacterial populations 
degrading the 
organic substances 

Source: [ 561, Flotats et al. 2004 ] 

The  purchase  cost,  quantity  required,  frequency  of  application,  and  hazard  potentials  of  an 
additive  are  the  most  important  parameters  for  its  use.  As  slurry  will  be  continually 
accumulating in a store, manure additives will need to be added at some frequency. The use of 
additives  can  be  considered  situation-specific,  mainly  depending  on  the  needs  of  the  farmer 
[ 560,  IGER  2000  ].  Additional  equipment  for  distributing  and  mixing  the  products  might  be 
required. 

Technical considerations relevant to applicability 
In most cases, additives can be used in existing or new farms with no technical restrictions.  

Economics 
In  general,  the  operating  costs  are  typically  equivalent  to  the  type  and  price  of  the  additive. 
Estimated  costs  are  reported  as  being  from  EUR 5  to  EUR 30  per  fattening  pig;  while  other 
studies  report  levels  of  EUR 0.25–1.25  per  fattening  pig  [  561,  Flotats  et  al.  2004  ].  Costs  of 
aluminium sulphate in poultry litter are estimated as EUR 3.5/t of litter (EUR 1 = GBP 0.86) 
[ 648,  DEFRA  2011  ].  Costs  for  urease  inhibitors  are  reported  to  be  very  high  by  Germany  [ 
474, VDI 2011 ]. 

628 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 4 

Driving force for implementation 
In general, the benefits of manure additives, compared to end-of-pipe solutions, are that a better 
indoor air quality is provided to both the animals and farmers and, at the same time,  they are 
relatively easy to implement in existing housing [ 499, AgroTech 2008 ] [ 259, France 2010 ]. 
As  problems  with  slurries  are  influenced  in  some  way  by  microbially  mediated  processes, 
manipulation  of  these  processes  by  bacterial/enzymic  agents  may  be  an  effective  means  of 
control.  

Example plants 
There  are  many  commercial  products  available.  Many  farms  in  different  Member  States  use 
them routinely. 

In Czech Republic, about 35 tested biotechnological agents are offered as manure additives. The 
efficacy  of  the  products  is  validated  on  a  case-by-case  basis  [287,  Jelínek  et  al.  2007  ].  In 
France, the use of biological (see Section 4.8.6) and chemical additives in poultry litter (broilers 
and turkeys) is increasing [ 624, IRPP TWG 2013 ] [ 257, France 2010 ]. A survey carried out in 
France  showed  that  more  than  80  products  are  available  for  treating  pig  slurry  [ 257,  France 
2010 ].  

Two farms in Belgium use manure additives (excluding pH regulators). In the UK, 500 farms 
use additives in the form of bacteria and enzymes in livestock manure (assuming 10 % of them 
to be pig farms and 90 % cattle farms). In France, 20 farms use additives, especially in response 
to odour problems [ 595, Agro Business Park 2011 ].  

Reference literature 
[ 151, Link CR 2005 ] [ 152, Link CR 2006 ] [ 205, ADAS 2000 ] [ 228, Denmark 2010 ] [ 257, 
France 2010 ] [ 259, France 2010 ] [ 287, Jelínek et al. 2007 ] [ 405, Tengman C.L. et al. 2001 ] 
[ 474, VDI 2011 ] [ 499, AgroTech 2008 ] [ 560, IGER 2000 ] [ 561, Flotats et al. 2004 ] [ 594, 
Agro Business Park 2011 ] [ 595, Agro Business Park 2011 ] [ 624, IRPP TWG 2013 ] [ 648, 
DEFRA 2011 ] 

4.12.13  Slurry and wet manure belt dryer 

Description 
This  technique  is  used  to  dry  the  non-stackable  solid  fraction  that  is  obtained  in  mechanical 
slurry separation processes, the solid residue produced from biogas plants, or the non-separated 
slurry  mixed  with  dried  manure.  It  aims  at  a  product  with  a  reduced  volume  and  higher  dry 
matter content by using heat convection for drying. The input material is dried by means of a 
belt through which warm air flows. 

The  transport  belts  are  made  of  wire  material  or  perforated  steel  plates,  and  heated  air  flows 
through  them.  In  drying  chambers,  one  or  several  transport  belts  are  arranged  one  above  the 
other (see Figure 4.94), allowing matter to drop from each.  

Intensive Rearing of Poultry or Pigs 

629 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 226, Germany 2010 ] 

Figure 4.94:  Scheme of a manure belt dryer 

When the material reaches the lower belt, it is mixed and homogenised. The lowest degree of air 
turbulence  and  the  optimal  vapour  content  are  sought,  in  order  to  minimise  dust  and  to 
maximise moisture removal. 

Achieved environmental benefits 
Relatively  solid  matter  is  processed  into  a  dry,  stable product  that  is  suitable for  storage  and 
transportation and that develops no, or only slight, odour. The technique is commonly used in 
combination with biogas production and also in a CHP system. 

Cross-media effects 
The  exhaust  drying  air  can  contain  high  levels  of  ammonia  and  so  needs  to  be cleaned by  an 
acid scrubber. The  ammonium salt produced is removed from the scrubber with the discharge 
water  and  has  a  fertilising  value  (6–7 %  of  nitrogen  in  ammonium  sulphate  solution).  In  the 
scrubber, 8–12 kg of sulphuric acid are needed per tonne of digestate. 

Specific thermal energy consumption of 700 kWh per tonne of solid matter is required to heat 
up the drying air, which is available on-farm at no additional cost when a CHP system is used to 
burn the biogas. Additional electric energy is needed to run the belt system, about 2–5 kWh per 
tonne of raw slurry, before separation.  

Environmental performance and operational data 
Equipment  is  available  with  a  capacity  of  1–2  tonnes  per  hour  of  separated  solid  fraction 
(corresponding  to  5–10  tonnes  per  hour  of  raw  slurry,  before  separation).  An  example  of  the 
input/output characteristics of manure processed with a belt dryer is presented in Table 4.198.  

Table 4.198:  Input  and output characteristics of the  manure  processed in the  manure belt drying 

process 

Dry matter 
kg/t 
300 
800 

Input 
Output  
Source: [ 226, Germany 2010 ] 

Total N 
kg/t 
8.4 
14.5 

NH4-N 
kg/t 
2.7 
0.74 

P2O5  K2O 
kg/t 
kg/t 
3.0 
10.1 
8.0 
27.11 

It is assumed that around 90 % of NH4-N is extracted from the treated matter during the drying 
process, which corresponds to 0.30 kg of nitrogen per tonne, or to 0.66 % of the total nitrogen 

630 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

load.  When  the  technique  is  combined  with  an  acid  scrubber,  almost  all  the  ammoniacal 
nitrogen would be collected; otherwise it would be lost as emissions. 

The solid fraction obtained after separation is stabilised and reduced in volume. Non-separated 
slurry can be dried by mixing it with previously dried material. From a treated digestate, a solid 
mass  is  obtained  having  8–9 %  of  the  original  volume,  which  is  also  sanitised  of  most 
pathogens. 

Technical considerations relevant to applicability 
Only  slight  adaptation to the  farm  equipment  is  necessary,  since only  a  screw press  separator 
(see  Section  4.12.2.2)  is  required  for  raw  slurry  for  the  first  slurry  separation  stage.  The 
technique  is  preferably  used  in  farms  with  over  2 000  animal  places,  or  in  combination  with 
biogas production, to dry the fermentation residues by using the heat from CHP plants. 

Economics 
Investment  costs  for  drying  units  are  reported  from  Germany  to  be  in  the  range  between 
EUR 300 000 and EUR 400 000 per unit, which corresponds to EUR 80 000–120 000 per tonne 
per hour. With an amortisation period of 10 years and 6 % interest rate, the investment can be 
annualised as EUR 10 000–15 600 per tonne, or EUR 39 000–52 000 per year, per drying unit. 

A  complete  installation  for  biogas  digestate,  inclusive  of  building  and  stores,  costs  about 
EUR 700 000 in Italy. Annualised investment costs are reported as EUR 3–4 per tonne of dried 
material  produced,  while  annual  operating  costs  are  reported  from  Italy  to  range  between 
EUR 0.8 and EUR 1.5 per tonne of dried digestate produced. The maintenance and control of 
the system requires 0.01–0.02 hours of labour per tonne of dried material per year.  

Driving force for implementation 
This  technique  may  have  an  economic  value  depending  on  the  transport  costs  of  undried 
manure. Storage volumes are significantly reduced. 

Example plants 
It has been reported that one farm in Italy is running the technique, and that others are planning 
to be equipped with the system. 

Reference literature 
[ 226, Germany 2010 ] [ 231, Italy 2010 ] [ 259, France 2010 ] 

Intensive Rearing of Poultry or Pigs 

631 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.13  Techniques for the reduction of emissions from manure 

landspreading 

Manure (liquid or solid) landspreading and the irrigation of waste water are commonly applied 
techniques. Slurries and solid manures are valuable fertilisers but may also be potential sources 
of pollution. Different amounts of valuable mineral elements (i.e. plant nutrients) contained in 
the manure can be lost as emissions during and after landspreading, if landspreading is not done 
properly. 

The  amount  of  farm  manure  available  and  its  nutrient  content  depend  on  the  farm-specific 
animal  feeding  practice,  animal  performance  and  the  use  of  extra  water  (see  Sections 4.3  and 
4.4). Manure landspreading is the last stage of farm manure handling and represents a crucial 
step to reduce emissions and maintain the benefit of abatement techniques applied upstream to 
control emissions.  

Seasonal timing of manure application, to synchronise with crop nutrient needs, is as important 
as  the  equipment  or technology  applied  for  landspreading  [  590,  Batfarm  2013  ].  In  addition, 
soil  characteristics  and  other  factors,  such  as  proximity  of  watercourses  and  climate/weather 
conditions,  are  important  factors  to  consider  particularly  with  regard  to  crop  nutrient  use 
efficiency and environmental impacts. The chemical analysis of the soil is a useful method in 
order  to  define  the  real  needs  of  fertilisation  and  evaluate  possible  overloads  caused  by 
excessive and repeated landspreading. 

Landspreading involves a number of tasks or actions that need to be coordinated, including the 
following: 

 

 

 

 

 

 

 

 

 

Assessing the land receiving the manure, in order to identify risks of run-off and prevent 
water pollution and the transfer of pathogens to water, and then deciding whether or not 
to landspread. In Nitrate Vulnerable Zones (NVZ), this aspect is essential. 

Avoiding weather conditions in which the soil could be seriously damaged or when the 
risk of run-off and the leaching of nutrients could be significant. 

Keeping  safe  distances  from  watercourses,  boreholes  and  neighbouring  properties 
(including hedges) to prevent run-off to water and spread of pathogens. 

Identifying  an  appropriate  application  rate,  taking  into  account  a  risk  assessment  plan, 
when  it is  required (e.g.  in  NVZ),  the  specific  nitrogen  and  phosphorus  contents  of  the 
manure derived from testing a representative sample or from typical values of the nutrient 
content of manures based on the analysis of a large number of samples, the seasonal crop 
requirements, and the characteristics of the soil (e.g. nutrient content). 

Checking  that  machinery  is  in  good  working  order  and  properly  set  at  the  correct 
application rate. 

Setting travel routes to avoid bottlenecks. 

Ensuring  that  there  is  adequate  access  to  the  slurry  store  and  that  loading  can  be  done 
effectively  and  without  spillage,  i.e.  by  checking  the  operation  of  pumps,  mixers  and 
sluice gates or valves. 

Assessing  the  spreading  fields  at  regular  intervals  to  check  for  any  sign  of  run-off  and 
respond properly when necessary. 

Ensuring  that  all  staff  are  trained  for  their  responsibilities  so  that  they  can  prevent 
accidents and take the right action if something goes wrong. 

However,  as NH3 emissions occur mainly at the soil surface, specific abatement measures are 
needed  to  reduce  ammonia  emissions,  such  as  application  of  technologies  like  liquid  manure 
injection or fast incorporation [ 337, Webb et al. 2005 ]. 

632 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 4 

National  Codes  of  Good  Agricultural  Practice  are  required  by  the  Gothenburg  Protocol  (see 
Section 1.4.1)  to  reduce  emissions  of  acidifying  and  ozone-producing  gases,  in  particular  to 
reduce  NH3  emissions.  Codes  should  take  into  account  local  soil  conditions,  the  manure  type 
and farm structure.  

The knowledge of the real content of nutrients contained in the manure is another crucial factor 
in  limiting  unnecessary  fertilisation.  Published  typical  nutrient  content  figures  provide  useful 
estimates.  The  testing  of  manure,  in  order  to  establish  its  nutrient  content,  provides  the  best 
information but may not always facilitate accurate assessments, as it is affected by the sample 
representativeness.  Technologies  are  developed  for  instant  analysis  of  nutrient  content  with 
portable equipment. Of these new technologies, NIRS (near-infrared reflectance spectroscopy) 
and EC meters (electrical conductivity meters) are now commercially available and in use for 
on-farm testing of slurries (e.g. in the UK).  

The manure application equipment should operate accurately to ensure that the intended amount 
of  nutrients  in  the  manure  is  applied  to  the  crop  with  an  even  spread  pattern  [  390,  ADAS 
2001 ]. 

Techniques to reduce the emissions from landspreading could be divided into two categories: 

 

 

techniques  that  reduce  emissions  that  occur  during  or  immediately  after  manure 
landspreading; these are predominantly emissions to air (ammonia and odour) and noise;  

techniques to reduce emissions after or as a consequence of manure landspreading; these 
concern  emissions  to  soil,  to  surface  water  and  groundwater  (N,  P,  etc.),  and  to  some 
extent to air. 

4.13.1 

Balancing the spreading of manure with the available land and 
soil/crop requirements 

Description 
Essentially,  emissions  from  manure  application  to  soil  and  groundwater  can  be  minimised  by 
balancing  the  application  rate  with  the  requirements  of  the  soil,  expressed  in  terms  of  the 
capacity for nutrient uptake by soil and vegetation, in order to avoid the application of excess 
nutrient levels. 

Nutrient storage by soil and nutrient uptake by vegetation are complex processes and depend on 
the  soil  characteristics  and  weather  conditions  during  application,  the  season,  and  the  type  of 
grass  or  crop  that  is  grown.  Ideally,  to  prevent  the  application  of  excess  nutrients,  no  more 
manure should be applied than the soil/crop requirements allow. Given a certain nutrient content 
in the manure and manure volume to apply, a maximum amount for manure application can be 
determined  for  the  requirements  of  a  given  crop.  In  addition,  available  nitrogen  and  nitrogen 
potentially mineralised in the soil should be taken into account, in order to avoid an excessive 
nitrogen addition with the manure. 

Achieved environmental benefits 
It is difficult to directly quantify the effect of the use of the soil nutrient balance. The aim is to 
avoid  having  an  excess  of  nutrients  in  the  soil  from  manure  landspreading.  Sometimes  it  is 
possible to deliberately cause a temporary excess of a nutrient, such as phosphorus, to make it 
available to crops to be grown on the same land.  

Balancing  the  nutrients  can  reduce  the  environmental  impact  on  soil  and  groundwater.  If  it 
results in lower application rates, the use of a soil nutrient balance will also affect emissions to 
air associated with manure application). On mixed livestock farms, between 10 % and 40 % of 
the nitrogen surplus is related to NH3 emissions [ 508, TFRN 2014 ]. 

Intensive Rearing of Poultry or Pigs 

633 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
None reported. 

Environmental performance and operational data 
Tools  that  can  be  used  for  balancing  the  amount  of  nutrients  applied  with  manure  to  the 
available land are: 

 

 

 

a soil nutrient balance; 

a rating system, i.e. rating the number of animals to the available land; 

fertilising norms for nitrogen and phosphorus and manure standards. 

A field nutrient balance calculates the difference between the total input of nutrients applied to 
the soil and the total output of nutrients, e.g. by harvest in a defined space-time  unit. Various 
tools  have  been  developed  to  calculate  the  amounts  of  nutrients  (nitrogen  and  phosphorus) 
applied and removed from the field in order to estimate the efficiency of nutrients used in crop 
production. Calculations for nutrient input consider the soil buffer, the use of mineral fertiliser, 
manure and other organic wastes, the atmospheric deposition of nitrogen and biological nitrogen 
fixation, as well as crop use. 

In general, the application rate is calculated by the ratio of nutrients content in the manure and 
the manure volume applied, considering the area available for landspreading and the time period 
(kg/ha per year). Typically, in pig and poultry manure, the ratio between P2O5 and the nitrogen 
content is roughly equivalent to the typical crop demand ratio for these nutrients. 

In  most  EU  Member  States,  decision  support  systems  and  nutrient  balancing  tools  for  crop 
production  are  in  use  to  help  farmers  make  effective  'fertilising  plans'  and  calculations. 
Furthermore,  these  tools  support  the  farmers  by  recording  input  and  output  data  at  the  field 
level.  Nutrient  recommendations  for  crops  and  grassland  are  also  available.  These  tools  are 
typically used to achieve NVZ compliance in relevant areas and are mandatory in some Member 
States  for  legal  reporting.  Fertiliser  planning  is  a  regulatory  requirement  within  some  MS 
regulations (e.g. UK in NVZ). 

An  example  of  a  tool  used  for  determining  a  proper  balance  between  manure  spreading  and 
available land in the UK is the ‘Tried & Tested Nutrient Management Plan’. This software tool 
guides  farmers  in  planning  and  recording  plant  nutrients  applications  [  336,  UK  2010  ].  It  is 
complemented  by  a  decision  support  system  that  can  accurately  predict  the  fertiliser  nitrogen 
value  of  applied  manures  on  a  field-specific  basis,  taking  into  account  the  manure  type, 
composition (total N, ammonium N and uric acid N), soil type, application date and technique, 
ammonia  and  nitrate  losses,  and  organic  nitrogen  mineralisation.  It  can  be  used  either  before 
applying manure, to check the likely effect of a spreading policy, or to assess the actual fertiliser 
nitrogen value of a spread manure using manure application details and weather data. Another 
tool  in  use  in  the  UK  is  called  'PLANET',  a  nutrient  management  software  tool  available  for 
farmers. It consists of several modules that carry out different calculation, record-keeping and 
reporting functions. 

Rating the number of animals to the available land is a more pragmatic approach at farm level, 
and is applied in, for example, Italy, Portugal and Finland. The EC has calculated the nitrogen 
balance and Nitrogen Production Standards for different animal categories [ 558, COM 1999 ]. 
Table 4.199  gives  an  example  for  the  maximum  allowable  number  of  animals  per  hectare  of 
land, calculated on the basis of 'standard' emission factors for nitrogen (kg N/ap/yr), applied in 
the  EU  and  a  yearly  maximum  load  of  nitrogen  per  hectare  of  soil  equivalent  to  170 kg 
N/ha/year (Nitrates Directive). 

634 

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Chapter 4 

Table 4.199:  Calculated maximum allowable animal number per hectare 

Type of livestock 

N production standard 
(kg N/animal/year) 

Sows with piglets (till 25 kg) 
Fattening pigs (25–105) 
Laying hens 
Broilers (1.8 kg) 
Ducks (3.3 kg) 
Turkeys (13 kg) 
Source: [ 558, COM 1999 ] 

21–32 
7.5–13.1 
0.35–0.82 
0.23–0.52 
0.41–0.97 
0.90–1.68 

Maximum allowable number of 
animals per hectare to comply with 
the EU limit of 170 kg N/ha 
5.3–8.1 
13–23 
207–486 
327–739 
175–415 
101–189 

Fertilising norms enable the balanced dosing of nutrients in the manure in relation to the crop 
requirements.  The  presence  of  manure  standards  is  a  prerequisite  for  the  efficient  use  of 
phosphorus and nitrogen norms on a large scale. Manure standards are official references that 
describe  as  a  minimum  the  amount  of  manure  produced  per  animal  per  year  or  per  animal 
produced and the composition of that manure in terms of the dry matter percentage and nitrogen 
and  phosphorus  content  (potassium  is  normally  part  of  official  manure  standards  as  well). 
Phosphorus fertilisation norms are presented in Section 4.13.1.1. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the technique. On the basis of 
these estimates, necessary reductions of nutrient inputs from manure (and fertilisers)  could be 
predicted and used as recommendations in policy instruments for reducing nutrient loads. These 
recommendations  will  affect  the  application  of  techniques  used  to  reduce  nutrient  losses  (e.g. 
volatilisation  of  ammonia,  nitrate  leaching)  and  will  encourage  the  development  of  new 
application techniques.  

Economics 
Costs are  associated  with  the  administrative  tasks  of the application  of  a  soil  nutrient  balance 
on-farm.  However,  cost  benefits  exist  when  over-application  of  fertiliser  is  prevented  and  the 
crop yield is maintained or improved.  

Driving force for implementation 
In  several  Member  States,  the  application  of  a  nutrient  balance  has  been  made  obligatory  by 
legislation.  The  designation  of  Nitrate  Vulnerable  Zones  (NVZ)  as  defined  in  the  Nitrates 
Directive (91/676/EEC)  and  increasing  economic  and  environmental  pressures  have  promoted 
an increased use of nutrient balances (N-balance). 

Concerning phosphorus, it is likely that the implementation of Programmes of Measures under 
the  Water  Framework  Directive  (2000/60/EC)  will  require  action  in  some  drainage  basins  to 
reduce phosphorus losses and this may result in further restrictions on manure spreading [ 204, 
IMPEL 2009 ]. 

Example plants 
This type of management appears to be common all over Europe. In the Netherlands, a nutrient 
balance system is applied. In the UK, the ‘Tried & Tested Nutrient Management Plan’ is in use; 
tools and publications such as the 'UK MANNER-NPK' and DEFRA fertiliser recommendations 
are  also  used  for  fertiliser  planning.  In  France,  the  national  regulation  requires  farmers  to 
manage their fertilisation by using a proper fertilising programme. In Denmark, a system where 
each  farmer  has  to  report  his  fertilising  plan  for  the  next  growing  season  is  used.  Several 
software systems or publications can be used for computing the 'fertilising plan'. The rating of 
the number of animals to the available land is applied in different countries (e.g. Italy, Portugal 
and Finland). 

Intensive Rearing of Poultry or Pigs 

635 

 
 
 
 
 
 
 
 
 
Chapter 4 

Reference literature 
[ 44, IKC 1993 ] [ 204, IMPEL 2009 ] [ 249, Webb et al. 2001 ] [ 336, UK 2010 ] [ 500, IRPP 
TWG 2011 ] [ 508, TFRN 2014 ] [ 555, MAFF 1998 ] [ 558, COM 1999 ] [ 624, IRPP TWG 
2013 ] 

4.13.1.1 

Phosphorus fertilisation norms 

Using  phosphorus  fertilisation  norms  is  a  way  to  reduce  the  risk  of  over-application  of 
phosphorus when fertilising with livestock manure. Over-application of phosphorus is common 
when  fertilising  planning  merely  considers  the  stipulated  nitrogen  fertilising  norm  in  the 
Nitrates Directive (maximum 170 kg N/ha per year). 

Sweden,  Estonia,  Finland  and  Germany  have  adopted  official  maximum  allowed  phosphorus 
norms,  whilst  Denmark,  Lithuania  and  Poland  have  recommended  norms.  There  are  two 
important differences between official and recommended phosphorus fertiliser norms: 

 

 

official norms specify the maximum permitted use of plant nutrients to reduce leaching of 
phosphorus to water from the fields, while recommended norms describe how the crops 
should be fertilised as a minimum, in order to give an expected yield; 

official  norms  are  built  into  the  legislation,  and  are  enforced  via  control  and  sanctions, 
while recommended norms are simply advisory. 

Phosphorus  fertilisation  norms  can  be  flat  rate  (without  respect  to  the  specific  crop  or  other 
parameters)  or  more  detailed  (considering  for  example  the  type  of  crop  and  the  phosphorus 
content of the soil). When flat-rate norms are used, the exact phosphorus norm is determined on 
a national basis according to prevailing crop rotations on land where manure is used as fertiliser. 
In Sweden and Estonia the official norms are determined as a maximum allowed flat rate, while 
Finland  and  Germany  have  adopted  a  more  detailed  regulation,  considering  the  specific 
conditions on fields and for crops. The efficiency of a phosphorus fertiliser norm increases if it 
is used in combination with a P Index (see below), especially when flat-rate phosphorus norms 
are used. 

Reference literature 
[ 619, Baltic Sea 2020 2011 ] 

4.13.2 

Groundwater protection schemes 

Description 
The main components of a groundwater protection scheme are: 

 

 

a  land  surface  mapping  to  display  groundwater  sources  and  resources  (aquifers),  which 
together define groundwater protection zones; 

the  groundwater  protection  responses  for  potentially  polluting  activities,  depending  on 
factors such as risk (hazard) and aquifer category. 

Achieved environmental benefits 
Defined  vulnerable  areas  (e.g.  groundwater)  can  be  protected  from  contamination  by  excess 
nitrogen, phosphorus microbial pollutants or specific heavy metals. The schemes are considered 
tools  that  can  direct  landspreading  (e.g.  advise  on  distances  to  vulnerable  zones)  to  less 
vulnerable areas. 

636 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Cross-media effects 
The  application  of  groundwater  protection  schemes  is  likely  to  restrict the  surface area  where 
landspreading  is  allowed,  and  as  a  consequence  less  area  is  available  to  apply  the  manure 
produced. Furthermore, it may be necessary to develop a programme in parallel that deals with 
the  possible  ways  to  treat  the  excess  manure,  such  as  on-farm  treatment  as  discussed  in 
Section 4.12. 

Environmental performance and operational data 
Every case is assessed individually, taking into account all local factors in order to find the best 
solution, achieve sustainability and match the standards set within the specific area. This means 
different  decisions  may  be  taken  if  the  farm  is  located  within,  or  is  impacted  by,  a  water 
protection zone; here a decision should be made concerning the technique to apply in order to 
meet the requirements, taking into account costs and profitability. 

Technical considerations relevant to applicability 
Groundwater schemes  can be  applied  wherever  a  potential risk  of  groundwater contamination 
exists. 

Economics  
The economic impact of groundwater schemes is related to the individual measures that can or 
must be applied.  

Driving force for implementation 
Schemes  have  been  developed  in  many  Member  States  based  on  the  European  Water 
Framework  Directive  (2000/60/EC),  the  Groundwater  Directive  (2006/118/EC)  and  national 
legislation for the protection of groundwater. 

Example plants 
Groundwater protection schemes are applied in several Member States. 

Reference literature 
[ 23, EPA (UK) 1999 ] 

4.13.3  Manure landspreading management practices  

Description 
A  proper  management  of  manure  landspreading  takes  account  of  the  nutrient  balance  (see 
Section  4.13.1),  as  well  as  surface  water  and  groundwater  protection  schemes  (see 
Section 4.13.2). It combines the following aspects: 

 

 

 

 

application on suitable areas; 

defining and observing buffer zones; 

proper timing of application;  

defining of spreading rate (in relation to nutrient content). 

Codes  of  practice  advise  setting  up  an  application  plan  and  distinguishing  between  different 
planning stages [ 386, DEFRA 2009 ].  

In  the  first  stage,  suitable areas  are  selected.  Land  is  excluded,  where  manure  should  not  be 
spread at any time or where there is a considerable risk of run-off, such as (very) steep slopes 
and surroundings sensitive to smell. Buffer zones should be defined and observed, in particular 
to avoid contamination of watercourses or the farmyard. Specific rules apply, such as minimum 
distances (50–100 m) to springs, wells or boreholes. These distances increase when the springs 

Intensive Rearing of Poultry or Pigs 

637 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

or shallow wells are downhill. Decisions at this stage may benefit from the latest developments 
in soil testing and field mapping. 

In the second stage, the amount of nutrients supplied by the manure must be matched with the 
potential nutrient uptake of the crop to be grown. Determination of the spreading rate (kg/ha or 
m3/ha)  should  be  based  on  land  availability,  crop  (or  grass)  nutrient  requirements,  and  the 
nutrient  content  in  the  slurry,  taking  into  account  the  nutrient  status  of  the  crop  and  other 
manures  and  mineral  fertilisers  applied.  In  most  reports,  reference  is  made  to  the  potential 
leaching  of  nitrate  and  a  maximum  of  250 kg  of  total  N/ha  from  manure  per  year  is 
recommended for land outside NVZ. This amount should be lower where already high available 
phosphorus contents in the soil limit the potentially applicable amount of manure.  

The third stage optimises seasonal application timing by estimating the risk of emissions from 
spreading.  The  aims  are  to  minimise  run-off  and  run-through  to  field  drainage  systems, 
according to the characteristics of the land concerned, as well as emissions to air (e.g. ammonia, 
odour),  considering  in  particular soil  and  weather  conditions  (e.g.  spreading  when  it  is  cooler 
and less windy) [ 508, TFRN 2014 ].  

Achieved environmental benefits 
A management system for seasonal timing landspreading operations, and for recording solid and 
liquid  manure  application  amounts  at  different  times,  may  result  in  quantifiable  farm-scale 
reductions in ammonia emissions. The planning of landspreading can also reduce emissions of 
odour, loss of nutrients due to leaching, and run-off. Potential emission reductions achievable 
through these measures will vary depending on farm-specific soil and climatic conditions [ 508, 
TFRN 2014 ].  

Cross-media effects 
Individual  manure  management  strategies  may  present  some  adverse  effects  when  mitigating 
one  pollutant,  with  possible  shifting  from  one  environmental  media  to  another  or  increased 
emissions of other pollutants. Safety aspects associated with machinery operations carried out at 
certain times, particularly during hours of darkness, should also be considered. 

Environmental performance and operational data  
The  seasonal  timing  of  the  application  aims  to  optimise  the  use  of  the  available  nutrients  in 
manures. Soil, nutrient status, weather conditions and the crop requirements in accordance with 
its growing season must be taken into account when planning manure application. 

Soil type and conditions 
Land  with  a  very  high  risk  of  run-off  (water-saturated,  snow-covered,  frozen,  flooded  areas, 
watercourses, etc.) should be avoided. Limits to the spreading rate are suggested at 50 m3/ha for 
slurry and 50 tonnes/ha for dry manure (UK) on high-risk land. For poultry, this usually means 
5–15 tonnes/ha.  Manure  should  not  be  landspread  on  fields  that  are  cracked,  or  on  fields  that 
have been drained within the last year either. 

As  an  example,  the  application  of  50 m3/ha  of  a  pig  slurry  with  4 %  dry  matter,  containing 
4.0 kg/m3  of  total  N,  will  supply  200 kg/ha  of  total  N.  If  this  is  applied  in December  to  the 
surface of arable land on a heavy-textured soil, it  will provide 80 kg/ha  of N (i.e. 40 % of the 
200 kg/ha total N) for the nitrogen requirement of the crop that will grow towards spring. If the 
same amount of slurry with the same characteristics is applied on a sandy soil, the amount of 
available  nitrogen  for  the  next  crop  would  be  50 kg/ha  of  N  (25 %  of  the  200 kg/ha  total  N)  
[ 389, ADAS 2001 ]. 

Weather conditions  
Landspreading should be avoided in periods that are too dry and windy, such as in the summer 
months. However, in some areas where heavy winter rains occur, the soil has a reduced bearing 
capacity and will compact faster in those periods, so the drier season needs be taken advantage 
of.  Ammonia  emissions  can  be  reduced  by  optimising  the  timing  of  application,  i.e.  cool  and 

638 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Chapter 4 

humid conditions, in the evening and night, before or during light rain (though water-logging of 
soils  can  make  spreading  conditions  unfavourable),  and  by  avoiding  spreading  during  warm 
weather [ 508, TFRN 2014 ].  

Crop growing season 
Manure  should  be  spread  as  close  as  possible  to  the  main  uptake  period  of  crops  so  that  a 
maximum nutrient uptake will occur.  
Results of studies carried out in the UK investigating the timing of manure application on free 
draining soils and for different types of plants have concluded the following: 

 

 

For winter cereals, for the application of pig slurry in autumn on cropped land, N leaching 
losses were equivalent to 20 % of the total N applied, which indicates a lack of crop N 
uptake  (by  the  winter  wheat  crops).  Compared  with  the  autumn  application,  spring 
landspreading results in lower leaching losses of the nitrogen applied and the highest crop 
nitrogen uptake of the applied manure. However, different soil conditions, such as water-
saturated arable soils in spring and ‘dry’ grassland soils in summer, may potentially lead 
to increased ammonia emissions, because infiltration rates into the soil are lower than at 
other times of year; warmer weather conditions could also increase ammonia emissions. 
Therefore, slurry applications are often limited to the period between February and May, 
due  to  the  highest  crop  nitrogen  uptake  being  during  this  period  and  the  potential 
mechanical crop damage caused by application after this period. 

On grassland, spring slurry applications before silage harvest (first cut) are likely to cause 
the least diffuse pollution from N compounds, because the risks of nitrate leaching losses 
are low and crop N uptake will be the greatest, reducing the soil mineral N pool available 
for  nitrous  oxide  production.  However,  slurry  applications  to  short  grass  swards  in 
summer are likely to lead to elevated levels of ammonia emissions compared with autumn 
to spring application timings [ 244, ADAS 2006 ]. 

In another study, carried out using a fertilising planning tool called 'MANNER' simulating UK 
conditions  (e.g.  rainfall,  soil  and  crop  conditions),  results  suggest  that,  in  order  to  avoid 
- leaching from NH4-N conserved in the manure, as a consequence of measures to 
increased NO3
reduce NH3 emissions, manures and slurries should not be incorporated to autumn-sown crops, 
but should be applied from October onwards to grassland and, where possible, to late autumn-
sown  combinable  crops,  or  to  arable  land  which  will  be  planted  in  the  spring.  Additional 
conclusions  of  the  study  propose  that  manure  from  laying  hens  and  broilers  should  not  be 
- leaching  is to be avoided, 
incorporated before October, on any type of soil. If increased NO3
incorporation  needs  to  be  delayed  until  January  on  most  soil  types,  and  until  early  March  on 
light soils in wet areas [ 249, Webb et al. 2001 ].  

Of  the  many  complaints  about  unpleasant  odours  from  farms,  most  relate  to  manure 
landspreading. The following points should, therefore, be considered before spreading: 

 

 

 

 

 

respect  the  recommended  or  mandatory  timing  set  by  local  rules,  and  avoid  spreading 
when people are more likely to be at home, unless it is absolutely necessary; 

pay attention to wind direction in relation to neighbouring houses; 

avoid spreading in warm humid conditions; 

use spreading systems which minimise the production of dust or fine droplets; 

cultivate land as soon as possible after landspreading. 

Technical considerations relevant to applicability 
The  management  of  manure  application  can  be  performed  without  any  limitation  or 
requirements.  The  planning  of  manure  application  should  play  a  vital  role  in  the  planning  of 
new units and should consider any limitations that already exist. 

Intensive Rearing of Poultry or Pigs 

639 

 
 
 
 
 
 
Chapter 4 

Economics 
In most cases, in order for farmers to comply with an application management plan, which will 
result in increased efficiency of slurry nitrogen utilisation and a reduction of emissions (nitrate 
leaching, ammonia and/or nitrous oxide emissions), extra storage capacity is required. A greater 
manure storage capacity enables farmers to shift manure application from autumn/early winter 
to spring. In addition, advanced spreading equipment, in particular for slurry application, will be 
necessary (e.g. band spreaders, injectors), to optimise nitrogen utilisation by crops with minimal 
soil  compaction  and  crop  damage  [  244,  ADAS  2006  ].  From  the  UK,  in  particular,  costs 
associated with an application management plan combined with extra storage capacity, shift of 
the  application  technique  from  broadcast  spreaders  to  trailing  hose,  and  designed  to  avoid 
autumn/winter slurry applications, are presented in Table 4.200. 

Table 4.200:  Costs for implementing spring slurry application practices in a typical pig farm in the 

UK in order to limit nitrate leaching losses  

Parameter 

Investment 
costs 
EUR (2) 

Annual amortised 
costs (1) 
EUR/year (2) 

Remarks 

Assumed slurry storage costs: 
EUR 40/m3. Annual amortised 
repayment costs based on an 
interest rate of 5 % over a 20-year 
period 
Annual amortised repayment costs 
based on an interest rate of 5 % 
over a 10-year period 
NI 
Based on a N fertiliser cost of 
EUR 0.34/kg 
Amortised over 10–20 years 

Extra storage capacity 

50 000 

3 980 

Slurry tanker fitted with 
a trailing hose boom 

28 400 

3 700 

NI 

Total cost 
Savings in fertiliser N 
applications (1) 
Net cost 
(1) Savings in N mineral fertiliser applications, resulting from reduced nitrate leaching losses in spring, compared 

465–750 

~ 9 600  

7 680 

NI 

NI 

with autumn/winter application timings and from reduced ammonia emissions from band spreading. 

(2) Costs calculated at the exchange rate of EUR 1 = GBP 0.88. 
NB: NI = no information provided. 

Source: [ 244, ADAS 2006 ] 

Driving force for implementation 
Requirements for compliance with existing legislation and Codes of Good Agricultural Practice.  

High  fertiliser  prices,  improved  handling  and  advanced  spreading  equipment,  and  improved 
awareness and knowledge of farmers and advisers facilitate better planning and use of manure 
as a valuable fertiliser during landspreading. The improved nitrogen availability achieved by the 
efficient  manure  utilisation  soon  return  a  profit  on  the  investment  in  low-emission  spreading 
equipment.  Once  the  benefits  become  evident,  measures  related  to  a  proper  application 
management plan tend to be adopted routinely. 

Legal  procedures  from  neighbouring  residential  areas  and  fines  for  pollution  of  watercourses 
can  be  avoided  by  properly  planning  the  application.  It  is  considered  that  planned  manure 
application management can save costs rather than generate costs. 

Example plants 
‘Codes  of  Good  Agricultural  Practice’  describing  farm  manure  management  are  commonly 
applied. 

Reference literature 
[ 31, MAFF 1999 ] [ 244, ADAS 2006 ] [ 249, Webb et al. 2001 ] [ 386, DEFRA 2009 ] [ 389, 
ADAS 2001 ] [ 390, ADAS 2001 ] [ 508, TFRN 2014 ] [ 554, EPA (IE) 1998 ] [ 624, IRPP 
TWG 2013 ] 

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Chapter 4 

4.13.4  Manure application systems 

4.13.4.1 

Use of low-emission manure (solid or liquid) application techniques  

Description 
Different application techniques are used for solid manure and for slurry. Generally, their use is 
followed  by  incorporation  of  the  manure  (solid  or  liquid),  except  for  the  direct-injection 
techniques used for the application of slurry.  

Application of solid manure 
Section 2.8.3  describes  the  following  three  main  types  of  spreaders  used  for  spreading  solid 
manure: 

 

 

 

Rotaspreader: a side-discharge spreader with a rotor that throws the solid manure out to 
the side, while spinning.  

Rear  discharge  spreader:  a  trailer  body  fitted  with  a  moving  floor  or  other  mechanism 
which  delivers  solid  manure  to  the  rear  of  the  spreader.  The  spreading  mechanism  can 
have either vertical or horizontal beaters, plus in some cases spinning discs.  

Dual-purpose  spreader:  a  side-discharge  spreader  with  an  open-top  V-shaped  body 
capable of handling both slurry and solid manure. 

The  latter  two  are  much  better  for  achieving  an  accurate  application  rate  and  even  spread 
distribution.  However,  for reducing  ammonia  emissions  from  landspreading  solid  manure,  the 
important factor is not the technique on how to spread but rather the incorporation. 

Application of slurry  
Nitrogen is preserved better during the storage and spreading of liquid manure than in the solid 
manure handling chain. Ammonia losses mostly occur immediately after spreading. 

The following slurry application systems are applied (see also Section 2.8): 

 

 

 

 

 

 

 

low-pressure broadcast spreader; 

band spreader;  

trailing shoe; 

injector (open slot); 

injector (closed slot); 

high-pressure injector;  

irrigator.  

The  low-pressure  broadcast  spreader  and  the  techniques  described  in  Sections 4.13.4.2.1, 
4.13.4.3  and  4.13.4.4  are  spreading  systems  for  slurry  that  can  each  be  fitted  onto  a  vacuum 
tanker or pumped tanker or used with an umbilical system as described in Section 2.8.  

The low-pressure broadcast spreader consists of a tanker equipped with a discharge nozzle and a 
splash  plate  applicator.  It  spreads  the  slurry  over  the  whole  soil  surface  ('broadcasts')  and  is 
considered  the  reference  (baseline)  for  assessing  emission  reduction  efficiencies  from  slurry 
applications  performed  with  other  techniques,  when  not  followed  by  quick  incorporation  
[ 508, TFRN 2014 ]. This technique does not significantly contribute to lower ammonia losses. 
In  addition,  if  slurry  is  applied  on  a  growing  arable  crop,  incorporation  is  not  possible  
[  35,  Netherlands  2010  ].  Due  to  the  aforementioned  characteristics,  the  technique  is  not 
discussed further in the following sections.  

Intensive Rearing of Poultry or Pigs 

641 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

High-pressure injection forces the slurry into the soil under pressure, without needing to break 
the  soil  using  tines  or  discs.  The  technique  does  not  seem  to  have  gained  widespread 
application; therefore, it is not discussed in the sections below.  

Acidification  of  slurry,  prior  to  or  while  spreading,  is  also  applied  using  standard  equipment 
(see  Section  4.12.9).  A  summary  of  the  main  characteristics  of  slurry  distribution  systems 
(excluding irrigators because of the lack of data) is presented in  Table 4.201 and some further 
information is given in the text. 

642 

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Table 4.201:  Characteristics of four different slurry application techniques 

Features 

Broadcast 
spreader 

Diluted slurry 
irrigators 

Band spreader 
(Trailing hose) 

Band spreader 
(Trailing shoe) 

Reduction of NH3 emissions (%) 

Reference 

30 

30–50  

Land use 

NI 

Grassland, arable 
land 

Grassland, arable land 

Range of dry matter 

Up to 12 % 

< 2 % 

Flat land, any 
cultivation growth 
stage, size and 
shape of fields 

Not applicable 
where irrigation is 
not required 

Clarification 

●●● 

●●● 

●●● 

Applicability 

NI 

Requires separation or chopping 

Relative work rate  

Uniformity across spread width 

Crop damage 
NB: NI = no information provided. 

● 
●● 
●●● 

Normal (lowest grade). 
Improved. 
Advanced (best evaluation). 

No 

●●● 

● 

●● 

Up to 9 % 
Slope (for tankers < 15 %, 
for umbilical systems 
< 25 %), not for viscous 
slurry or with high straw 
content, size and shape of 
fields should be considered, 
growing crop 

Can be used on solid-seeded 
crops and wide units may be 
compatible with tramlines 

Up to 6 % no 
Over 6 % yes 

●● 

● (simple) 
●●● (advanced) 
●●● 

Chapter 4 

Closed slot 
(deep) 
80–90 

Arable land, 
bare soil 

Up to 6 % 

(See open slot)  

Injector 

Open slot (shallow)  

56–80  

Arable land, grassland 

Up to 6 % 
Slope < 12 %, greater 
limitations for soil type and 
conditions, not viscous slurry 

Unsuitable on high stone 
content, shallow soils, high 
clay soils (> 35 %) in very 
dry conditions, peat soils 
(> 25 % organic matter 
content). Tile-drained soils 
susceptible to leaching 

40–65  
Mainly grassland and 
 arable at early stages or 
with widely spaced rows 
Up to 6 % 
Slope (for tankers < 20 %, 
for umbilical systems 
< 30 %), not viscous slurry, 
size and shape of the field, 
grass height should be  
> 8 cm 

suitable in  growing 
Not 
solid-seeded 
but 
possible  use  in  the  rosette 
stage and in row crops 

crops, 

Yes 

●● 

●●● 

●●● 

Yes 

●● 

●●● 

●●● 

Yes 

● 

●●● 

●●● 

Source: [ 42, Netherlands 1999 ] [ 389, ADAS 2001 ] [ 390, ADAS 2001 ] [ 236, Denmark 2010 ] [ 237, Denmark 2010 ] [ 238, Denmark 2010 ] [ 500, IRPP TWG 2011 ] [ 35, NL 2010 ] [ 440, 
Webb et al. 2010] [ 508, TFRN 2014 ] [ 575, UBA Germany 2011 ] [387, Denmark 2010 ] [ 603, Denmark 2009 ] [ 604, Denmark 2009 ] [ 234, Spain 2010 ] [ 235, Spain 2010 ] [ 236, Denmark 
2010 ] [ 237, Denmark 2010 ] [ 238, Denmark 2010 ] [ 500, IRPP TWG 2011 ] 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

Achieved environmental benefits 
Each technique has its limitations and is not applicable in all circumstances and/or on all types 
of  land.  Techniques  that  inject  slurry  give  the  highest  reduction,  but  techniques  that  spread 
slurry  on top of the  soil  followed  by  incorporation  shortly  afterwards  can  also  achieve  a  high 
reduction [ 35, Netherlands 2010 ]. 

The  emission  reduction  levels  achieved  by  applying  different  techniques  are  considered  to  be 
very site-specific and vary according to the slurry's dry matter content, the prevailing weather 
conditions,  the  soil  type  and  conditions,  and  the  crop  conditions,  but  mostly  according  to  the 
amount of ammoniacal nitrogen (TAN) spread on the land.  

Techniques  for  landspreading  solid  manure  do  not,  in  general,  influence  ammonia  emissions. 
Incorporation by ploughing or harrowing after application reduces ammonia losses by burying 
the majority of the manure [ 441, Webb et al. 2011 ].  

Cross-media effects 
The use of heavy equipment causes soil compaction and damage, with a consequent potential 
risk of water pollution, especially in late winter/early spring. Surface broadcasting is typically 
uneven, especially under windy conditions, and may also damage grass swards and contaminate 
crops with microorganisms that could impede silage fermentation. Techniques that reduce NH3 
emissions may induce an increase in N2O emissions, due to the higher rate of nitrogen entering 
the  soil  and  the  less  aerobic  conditions  (deeper  and  wetter  soils).  However,  under  some 
circumstances, such increases do not always occur [ 440, Webb et al. 2010].  

Environmental performance and operational data 
The  conditions  during  slurry  application  greatly  affect  the  performance  of  the  techniques.  In 
particular, ammonia abatement efficiencies vary depending on the following: 

 

 

 

 

 

Ammonia  volatilisation.  This  may  be  reduced  by  minimising  exposure  of  the  manure 
surface to air and by increasing contact with the soil.  

Slurry dry matter content. Dilution of the slurry, or separating out the solids, reduces NH3 
emissions.  It  is  considered  that  from  a  slurry  with  6 %  dry  matter  (DM),  ammonia 
emissions  are  typically  20 %  higher  than  those  from  a  2 %  DM  slurry.  Reduced  losses 
from low-DM slurries are associated with faster infiltration into the soil, compared with 
high-DM slurries which remain longer on the soil  or plant surface [ 389, ADAS 2001]. 
Dilution  requires  water  and  creates  a  larger  volume  to  be  applied,  whereas  removing 
solids requires the handling of a solid fraction and a liquid fraction as well. The higher the 
accuracy  of  application,  the  lower  the  dry  matter  content  of  the  slurry  can  be,  thus 
requiring  some  chopping  or  separation  before  the  slurry  can  be  applied.  Injection  or 
incorporation of manure minimises exposure to the air. 

Prevailing  weather  conditions.  Ammonia  emissions  increase  with  increasing  air 
temperature, wind speed and solar radiation [ 508, TFRN 2014 ] [ 440, Webb et al. 2010]. 

Soil  type.  Well-draining  and  dry  soils,  which  allow  faster  infiltration,  can  give  rise  to 
lower emissions than wet soils with a reduced infiltration rate. However, some soils may 
become  hydrophobic  when  very  dry,  which  can  also  reduce  infiltration  and  therefore 
increase emissions [ 508, TFRN 2014 ].  

Crop  conditions.  Spreading  slurry  with  trailing  hoses  on  crops  reduces  ammonia  losses 
compared  with  application  on  bare  soil,  as  crops  can  restrict  solar  heating  and  wind 
speed, and as a certain proportion of the volatilised ammonia can be absorbed by the crop. 
The  crop  height  is  important,  mainly  in  band  spreading  in  cereal  crops,  which  are 
significantly tall. In contrast, slurry application on grass crops takes place in early spring 
or immediately after cutting. At these times, the grass crop height is so short that the crop 
does not influence volatilisation of ammonia from the applied manure [ 442, Hansen et al. 
2008 ]. 

644 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Chapter 4 

 

Nitrogen  application  rate.  Ammonia  emissions  are  normally  increased  with  increasing 
TAN  concentration  and  application  rate.  The  level  of  emission  also  varies  for  different 
manure types [ 508, TFRN 2014 ].  

The  application  of  solid  manure is always  followed  by  incorporation.  Even short  delays  (4 to 
6 hours)  in  incorporating  the  manure  after  application  will  reduce  the  efficacy  of  controlling 
ammonia  emissions.  Hence,  incorporation  should  be  done  as  soon  as  possible  (see 
Section 4.13.5) [ 440, Webb et al. 2010]. Other factors that may influence ammonia and nitrous 
oxide emissions following solid manure spreading are as follows:  

 

 

 

Higher application rates, increasing the proportion of nitrogen lost as ammonia. 

Climatic  conditions,  such  as  air  temperature,  radiation,  wind  speed  and  rainfall,  may 
affect emissions. Ammonia losses are expected to increase with increasing temperature. 
However,  crusting  of  the  surface  layer  of  manure  at  higher  temperatures  may  reduce 
emissions. The formation of N2O increases with temperature. 

Rainfall is a parameter which influences NH3 emissions in a contradictory way. On one 
hand, due to NH4-N leaching from manure to the soil, less ammonia is emitted but, on the 
+,  more  NH3  can  then 
other  hand,  due  to  increased  hydrolysis  of  uric  acid  to  NH4
volatilise. 

  While  no  influence  of  soil  type  on  NH3  emissions  from  solid  manure  has  been 
demonstrated to date, N2O emissions from agricultural soils were found to be higher from 
fine  soils  than  from  coarse-textured  soils.  Nitrous  oxide  production  can  increase  with 
increasing soil moisture. However, increasing soil moisture and decreasing temperatures 
(e.g. over the winter period) are expected to favour the reduction of N2O to N2. 

Technical considerations relevant to applicability 
A  number  of  factors  must  be  taken  into  account  in  determining  the  applicability  of  each 
technique. These factors include: 

 

 

 

 

soil type, condition and texture (soil depth, stone content, wetness, travelling conditions);  

topography (slope, size of field, evenness of ground); 

manure type and composition (slurry or solid manure); 

crop type and its growth stage.  

Economics 
The costs of landspreading techniques are in the range of EUR 0.1–5/kg NH3‐N saved, with the 
lowest  costs  corresponding  to  application  with  immediate  incorporation.  Costs  are  very 
sensitive to farm size and whether or not specialist contractors are involved [ 601, ALTERRA-
IIASA 2012 ] [ 508, TFRN 2014 ]. 

The  investment  costs  of  slurry  spreading  systems  vary  considerably,  depending  on  the 
specifications  for  each  machine,  and  whether 
they  have  hydraulic/electric  controls, 
single/double/triple  axles  or  other  extras.  Slurry  tankers  constructed  to  take  attachments  will 
have a stronger chassis or special brackets fitted, compared to stand-alone slurry tankers.  

Examples  of  cost  data,  estimated  in  the  UK  and  Germany,  in  relation  to  reduction  rates  of 
ammonia emissions, and expressed as the value of the extra nitrogen uptake due to conserved 
nitrogen  (bonus),  are  presented  in  Table 4.202.  The  value  of  the  conserved  nitrogen  (bonus) 
depends  on  fertiliser  prices  and  the  ammonia  abatement  efficiency.  A  reduction  technique  is 
cost-neutral if the reduction costs are identical or lower than the amount of the corresponding 
bonus.  The  estimations  have  been  made  in  comparison  with  the  use  of  a  broadcast  spreader, 
assumed as the reference technique.  

Intensive Rearing of Poultry or Pigs 

645 

 
 
 
 
 
 
 
 
Chapter 4 

Table 4.202:  Bonus  for  conserved  nitrogen,  achieved  by  applying 

low-emission  spreading 

techniques for slurry 

Technique 

Bonus 
(EUR/m3 
slurry) 

Example from Germany 
Associated 
NH3 emission 
reduction 
(%) 
30 
50 
60 
90 
NI 
90 
70 

0.27 
0.45 
0.54 
0.81 
NI 
0.81 
0.63 

Trailing hose 
Trailing shoe 
Open slot injector (discs) 
Closed slot injector (cultivator) 
Immediate incorporation  
Incorporation within 1 h 
Incorporation within 4 h 
Source 
(1) Values are calculated at the exchange rate of EUR 1 = GBP 0.88. 
NB: NI = no information provided. 

 [ 575, UBA Germany 2011 ]  

Example from UK 

Associated 
NH3 emission 
reduction 
(%) 
40 
65 
80 
NI 
95 
NI 
NI 

Bonus (1) 
(EUR/m3 
slurry) 

0.53 
0.85 
1.07 
NI 
1.27 
NI 
NI 

[ 254, Webb J.M. et al. 2009 ]  

Costs for the spreading of slurry and associated ammonia emission reduction costs depend on 
the  equipment  used,  the  exploitation  of  its  capacity  for  slurry  application,  and  the  farm  size. 
Cost  data  from  Germany,  related  to  the  spreading  of  slurry,  are  presented  in  Table 4.203  for 
different spreading and incorporation techniques and farm sizes. In general, the capital cost of 
ownership is high; most individual UK farmers use contractors [ 440, Webb et al. 2010 ].  

646 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Table 4.203:  Costs  for  slurry  spreading  and  associated  ammonia  emission  reduction  costs  for 

different application techniques and farm sizes, in Germany 

Chapter 4 

Annual process 
capacity (m3/year) 

Characteristics 

Process capacity 
(m3/h) 

Broadcast 
spreader (1) 
Trailing hose 
Trailing shoe 
Open slot injector 
(discs) 
Closed slot 
injector 
(cultivator) 
Incorporation 
within 1 h 
Incorporation 
within 4 h 
Dilution with 
water 1:1 

Farm size and characteristics 

1 000 

3 000 

10 000 

30 000 

100 000 

Single farm, 
with necessary 
equipment 

Slightly larger farm or a 
cooperative of smaller 
farms, sharing 
equipment 

A cooperative 
or a larger 
farm 

Contractors and 
large farms 

Low 

High 

Low 

Low 

NI 

NI 

Spreading costs (EUR/m3 slurry) 

6.61 

8.76 
9.68 

9.97 

3.22 

3.99 
4.63 

4.89 

4.31 

5.08 
5.87 

6.16 

3.04 

3.38 
4.11 

4.37 

3.19 

3.32 
4.10 

4.67 

2.49 

2.57 
NI 

2.89 

10.38 

5.71 

7.49 

4.96 

5.30 

3.04 

7.43 

7.10 

11.1 

4.04 

3.71 

6.08 

5.13 

4.80 

8.81 

3.86 

3.53 

6.49 

Ammonia emissions reduction costs (EUR/kg NH3) 

3.16 
2.89 

2.28 

3.16 
3.20 

2.53 

1.42 
2.20 

1.82 

4.02 

3.31 

3.69 

2.98 

5.95 

4.4 

0.50 
1.86 

2.02 

0.34 
NI 

0.55 

2.27 

2.89 

1.75 

1.91 

0.50 

0.75 

0.81 

4.69 

0.75 

0.81 

7.37 

0.75 

0.81 

5.65 

0.75 

0.75 

0.81 

0.81 

4.52 

3.13 

4.60 

3.43 

8.80 
6.29 

Trailing hose 
Trailing shoe 
Open slot injector 
(discs) 
Closed slot 
injector 
(cultivator) 
Incorporation 
within 1 h 
Incorporation 
within 4 h 
Dilution with 
water 1:1 
(1) Reference system. 
NB: NI = no information provided. 

0.75 

0.81 

7.37 

Source: [ 575, UBA Germany 2011 ]  

Driving force for implementation 
High  fertiliser  prices,  improved  handling  and  spreading  equipment,  improved  awareness,  and 
farmers' and advisers' knowledge facilitate better operability and manure utilisation. 

Reduced ammonia losses result in a reduced use of expensive mineral fertilisers. Therefore, the 
improved nitrogen availability makes the investment in low-emission spreading equipment more 
profitable.  

Compared  to  broadcast  spreading,  these  techniques  minimise  the  occurrence  of  herbage 
contamination; this is particularly relevant for grassland, where slurry contamination can reduce 
grazing  palatability  or  silage  quality  and  can  transfer  pathogens  between  farms  if  manure  or 
equipment is shared. 

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647 

 
 
 
 
 
 
 
Chapter 4 

These  techniques  also  allow  slurry  application  for  growing  arable  crops  (particularly  cereals), 
which,  in  general,  are  not  suitable to  receive  slurry  applied  by  broadcast  spreaders  (splash 
plate).  The  use  of  low‐emission  techniques  can  increase  the  flexibility  of  slurry  application 
[ 601, ALTERRA-IIASA 2012 ]. 

Band spreading and injection techniques considerably reduce the odour associated with manure 
application,  therefore  allowing  application  on  areas  or  at  times  that  would  otherwise  be 
unavailable due to complaints. Additionally, band spreading and injection techniques can allow 
more  accurate  slurry  application  rates  than  broadcasting  (reference  technique)  [  508,  TFRN 
2014 ].  

Example plants 
All techniques are applied in Europe. In the UK, there has been a large general increase in the 
uptake of reduced-NH3-emission machines over the past years [ 440, Webb et al. 2010 ]. 

In the last decade, several livestock farmers have outsourced manure application to specialised 
contracting  firms,  which  use  large  machines  with  high  capacities  in  terms  of  m3  of  manure 
and/or m2 of land applied per man-hour. This has led to considerably lower costs and to the use 
of available techniques on a much larger scale in many more countries [ 601, ALTERRA-IIASA 
2012 ].  

Reference literature 
[ 35, Netherlands 2010 ] [ 42, Netherlands 1999 ] [ 234, Spain 2010 ] [ 235, Spain 2010 ] [ 236, 
Denmark 2010 ] [ 237, Denmark 2010 ] [ 238, Denmark 2010 ] [ 254, Webb J.M. et al. 2009 ] 
[387, Denmark 2010 ] [ 389, ADAS 2001 ] [ 390, ADAS 2001 ] [ 406, Netherlands 2002 ] [ 
440, Webb et al. 2010 ] [ 441, Webb et al. 2012 ] [ 442, Hansen et al. 2008 ] [ 500, IRPP TWG 
2011 ] [ 508, TFRN 2014 ] [ 575, UBA Germany 2011 ] [ 601, ALTERRA-IIASA 2012 ] [ 603, 
Denmark 2009 ] [ 604, Denmark 2009 ] 

4.13.4.2 

Slurry dilution 

Ammonia  emissions  from  dilute  slurry  (less  than  2 %  dry  matter  content)  application  are 
generally less than for undiluted slurry because of  the  faster infiltration into the soil. Dilution 
can be achieved in water irrigation systems or by adding water before  landspreading either in 
the slurry store or in the mobile tank. Other methods to reduce the dry matter content of slurry 
include  anaerobic  digestion  (see  Section  4.12.5)  and  solid-liquid  mechanical  separation  (see 
Section 4.12.2).  

4.13.4.2.1 

Low-pressure water irrigation systems 

Description 
Controlled  quantities of untreated slurry, or the  clarified fraction from mechanically separated 
slurry, can be mixed with irrigation waters and applied to grassland or growing crops on arable 
land.  The  amounts  of  slurry  are  calculated  to  match  the  nutrient  requirements  of  the  crops. 
Slurry is pumped from the stores, injected into the irrigation water pipeline and brought to low-
pressure sprinklers, pivots or travelling irrigators, which spray the mix onto land [ 508, TFRN 
2014 ] (see Figure 4.95).  

648 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 242, CRPA 2009 ] 

Figure 4.95:  Irrigation boom fitted with hanging nozzles to spray the water-slurry mixture close to 

the soil surface 

Achieved environmental benefits 
Ammonia  emissions  from  dilute  slurries,  with  a  low  DM  content,  are  lower  than  those  from 
undiluted  slurries,  due  to  the  faster  infiltration  into  the  soil,  which  prevents  both  ammonia 
volatilisation  and  formation  of  crusts  on  the  ground,  and  also  due  to  the  lower  NH4-N 
concentration in the slurry [ 508, TFRN 2014 ]. The use of intermittent operation may also limit 
the  odour  nuisance.  The  energy  requirement  for  low-pressure  irrigators  is  low.  Reduced  soil 
damage and compaction are also achieved.  

Cross-media effects 
With  dilute  slurry  irrigation  systems,  the  duration  of  landspreading  is  much  longer.  Also,  the 
high  volumes  of  dilute slurry  applied  by  irrigation  may  exceed  the  infiltration  capacity  of the 
soil, leading to higher emission rates in the period immediately after landspreading. 

When diluting slurry, extra storage capacity may also be needed. Since volumes for storage and 
application  increase,  the  associated  costs  are  also  amplified  [  508,  TFRN  2014  ]  [  624,  IRPP 
TWG 2013 ]. 

Environmental performance and operational data 
The  emission  reduction  is proportional  to  the  extent of  dilution.  For undiluted slurry,  dilution 
with water (reduction in dry matter content) of 50 % (1 : 1 water to slurry) can reduce emissions 
by  30 %  [  508,  TFRN  2014  ].  Dilution  rates  may  be  up  to  50  :  1  water  to  slurry  [  601, 
ALTERRA-IIASA  2012  ].  If  the  system  is  properly  operated,  sprays  are  directed  close  to  the 
ground, reducing losses from evaporation and aerosol drifts. 

Ammonia emissions during irrigation (before reaching the soil) of dilute pig slurries (0.5–0.9 % 
DM) were measured as 0.1 % to 2.6 % of the TAN applied, with an average of 1.3 %. Emissions 
are expected to be greater from a high-pressure raingun than from boom-mounted splash plate 
systems.  Emissions  following  irrigation  are  estimated  as  approximately  10 %  of  the  applied 
TAN.  

Technical considerations relevant to applicability 
Landspreading  of  diluted  slurry  by  water  irrigators  is  possible  at  almost  any  growth  stage, 
allowing  the  maximum  utilisation  of  nitrogen  by  plants.  Due  to  the  risk  of  contamination, 
irrigation with diluted slurry would not be appropriate for crops grown to be eaten raw. 

Application of the technique is often only possible in areas easily connected to a farmstead by 
fixed pipework. The pumping distance is influenced by the pump capacity, topography and the 
pipe  dimensions;  therefore,  it  may  pose  an  added  limitation.  The  application  of  dilute  slurry 
with  irrigators  should  meet  crop  water  needs;  otherwise,  dilution  of  slurry  would  result  in 

Intensive Rearing of Poultry or Pigs 

649 

 
 
 
 
 
 
 
 
 
Chapter 4 

increased  hauling  costs  and  may  exacerbate  nitrate  leaching  or  manure  run-off,  especially  on 
sloped fields. Application volumes and soil type and conditions (e.g. not saturated with water, 
not very compacted) should allow for rapid infiltration. 

Economics 
Costs are in the range of EUR 0.5–1.0 per kg of NH3 abated [ 508, TFRN 2014 ]. 

Driving force for implementation 
The technique can be used where there is a need for water irrigation systems.  

Example plants 
It is estimated that approximately 20 % of the total pig slurry output in the UK is landspread by 
irrigation systems, including rainguns, boom-mounted, pulse-jet and rotary boom systems. The 
technique  of  low-pressure  irrigators  is  in  common  use  in  the  UK,  particularly  for  dirty  water 
application.  Static  sprinklers  are  used  for  smaller  applications,  whereas  travelling  low-rate 
irrigators  are  used  for  larger  applications.  Irrigation  techniques  with  sprinkler  systems  are 
moderately spread in Italy in farms with anaerobic digestion plants [ 240, Italy 2010 ]. 

Reference literature 
[  240,  Italy  2010  ]  [  242,  CRPA  2009  ]  [  247,  IGER  2003  ]  [  508,  TFRN  2014  ]  [  601, 
ALTERRA-IIASA 2012 ] [ 624, IRPP TWG 2013 ] 

4.13.4.2.2 

Pulse-jet irrigator 

Description 
A hosepipe is mounted on a rotating arm and delivers a pulse of slurry or dirty water every 30–
150 seconds over some 60 m along the radius of the circle. The arm rotates in 9 ° steps to give a 
circular pattern and achieve full coverage over a number of rotations (see Figure 4.96). 

About  100  litres  of  liquid  are  gradually  pumped  into  a  pressure  accumulator  tank  and  are 
discharged when the pressure reaches a preset level. The slurry emerges from large jets (49 mm 
and 19 mm diameter) as a solid stream for about 3.5 seconds and breaks up into large droplets 
as it passes through the air. Then, the pressure tank refills, the nozzle moves round and the next 
pulse is discharged, typically about 45 seconds later, depending on the size of pump used.  

650 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 246, Basford 2010 ] 

Figure 4.96:  Pulse-jet irrigator in operation 

Achieved environmental benefits 
There  is  virtually  no  risk  of  soil  compaction  and  minimal  risk  of  water  pollution  due  to  the 
controlled landspreading. 

Cross-media effects 
The disadvantage of increased aerial emissions compared to low-level placement techniques is 
relatively low, due to the very large droplet size. The energy use of the technique is about 0.5–
0.8 kWh/m3.  

Environmental performance and operational data 
The ultra-low application rate (0.1–2 mm/hour) and high degree of accuracy allow nitrogen to 
be supplied to crops when needed. There is virtually no risk of soil compaction and minimal risk 
of water pollution as the application rate can be kept below the rate of infiltration into the soil, 
for  any  soil  type  (e.g.  4  mm/hour  for  a  clay  soil  on  level  ground,  and  1 mm/hour  on  a  16 ° 
slope).  

Adjoining  circles  are  overlapped  by  placing  centres  approximately  105 m  from  one  another, 
normally using a triangular arrangement. A central area of 7.5 m around the machine receives a 
low  application  rate  and  represents  1.6 %  of  the  full  60  m  circle,  or  2 %  of  the  overlapped 
52.5 m  circle.  In  the  overlapping  pattern,  small  roughly  triangular  areas  are  not  fully  covered 
and therefore also receive a lower application rate. These account for 1.3 % of the area of the 
60 m circle, and neither type of area with low-application areas is considered significant.  

The average precipitation rate achieved by the pulse-jet irrigator is 0.3–1.0 mm per hour, while 
the maximum precipitation rate for slurry to avoid run-off is 5 mm per hour [ 624, IRPP TWG 
2013 ]. 

Emissions are estimated to be similar to or less than those of any broadcast system (depending 
on  weather  and  humidity).  While  the  exposure  may  be  greater  at  the  time  of  discharge, 
applications well below the infiltration rate reduce emissions by allowing rapid absorption and 

Intensive Rearing of Poultry or Pigs 

651 

 
 
 
 
 
 
 
 
Chapter 4 

by  reducing  the  residence  time  on  the  ground.  Slurry  infiltration  is  also  improved  by  causing 
very  little  ground  compaction.  The  energy  use  of  the  technique  is  also  very  low  at  0.5–
0.8 kWh/m3 [ 246, Basford 2010 ]. 

Technical considerations relevant to applicability 
The  irrigator  should  not  be  sited  closer  than  75 metres  to  any  watercourse,  to  allow  for  an 
effective 15 m spreading distance. Grassland, cereals, root crops and brassicas are suitable for 
slurry spreading by this technique  provided that the plants are sturdy enough to  withstand the 
large droplet size. The pulse-jet irrigator can handle undiluted pig slurry at up to 5 % dry matter 
content.  It  can  also  be  used  to  apply  dirty  water  [  246,  Basford  2010  ].  Due  to  the  risk  of 
contamination, this technique is not appropriate for crops grown to be eaten raw.  

Economics 
The  approximate  total  cost  of  an  operating  system  is  between  EUR 12 750  and  EUR 22 150, 
varying  depending  on  the  system's  dimension  and  capacity.  Irrigators  cost  EUR 4 700  or 
EUR 9 400, for a coverage of 0.5 hectare or 1.0 hectares, respectively. The cost of pumps with a 
capacity of 3 m3 to 10 m3 per hour vary from EUR 5 650 to EUR 10 350. Connecting pipework 
in medium-density polyethylene needs to be sized based on the slurry's dry matter content, the 
pumping capacity per hour, and the size of the pipe network. The cost of 1 000 m of pipe and 
fittings  for  3 %  DM  slurry  pumped  at  6 m3/hour  (that  requires  a  63 mm  medium-density 
polyethylene  main  pipe)  can  cost  around  EUR 2 400  (values  based  on  an  exchange  rate  of 
EUR 1 = GBP 0.85). 

Driving force for implementation 
The  low  application  rate  and  high  degree  of  accuracy  allow  nitrogen  to  be  supplied  to  crops 
when needed. 

Example plants 
Over 700 units have been sold in the UK by one producer over the past 20 years, with numbers 
varying between 15 and 100 units per year. 

Reference literature 
[ 246, Basford 2010 ] [ 624, IRPP TWG 2013 ] 

4.13.4.2.3 

Landspreading of diluted slurry using drip lines 

Description 
The  liquid  fraction  of  mechanically  separated  slurry  can  be  distributed  onto  crops  using  drip 
lines, mixing it with irrigation water. 

Achieved environmental benefits 
Nitrogen  utilisation  by  plants  is  improved,  therefore  related  emissions  are  reduced.  The  low 
water consumption is implicit in this irrigation method. 

Cross-media effects 
Drip lines are foreseen to be replaced annually. 

Environmental performance and operational data 
In a trial carried out in Italy, the effects of the application of drip line technology to distribute 
the liquid fraction of digested pig slurry after mixing with irrigation water have been compared 
with those of the technique of band spreading of untreated pig slurry  [ 241, Italy 2010 ]. The 
drip line system was fed by a pump supplying a mixture of about one part slurry to three parts 
water.  Disc  filtration  was  performed  after  mixing.  The  system  was  tested  on  maize  placed  in 
rows 0.7 m apart from one another, each drip line being positioned between alternate rows and 
thus 1.4 m from one another. The water-slurry mixture supply was always followed by 1 hour of 
irrigation of water alone in order to wash the drip lines. The mixture was distributed four times 

652 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
on the crop at a rate of 2.5–3 l/m2/h, for a total of 12 hours over a period of 3 weeks. The water-
slurry mixture after filtration that was distributed had the following average characteristics. 

Chapter 4 

Table 4.204:  Average chemical characteristics of the water-slurry mixture  

Parameters 

pH 
Dry matter content 
Total suspended solids 
Volatile solids 
Total Kjeldahl nitrogen 
Ammoniac nitrogen  
Source: [ 241, Italy 2010 ] 

Unit 

 % 
g/l 
g/kg 
mg/kg 
mg/kg 

Average value 
8.2 
0.31 (0.26–0.35) 
0.27 
0.81 
627 
540 

Comparison with the traditional band spreading technique  revealed the same  maize yields but 
significantly low emissions were measured, varying from 0.003 kg to 0.013 kg of ammonia per 
m3 of slurry applied. 

Applicability 
Drawbacks still remain in the operational implementation of this system, requiring the setting up 
of the slurry separation and distribution equipment, the maintenance of the pump and filter and 
rodent control.  

Economics 
The  annual  costs  are  estimated  at  EUR 840/ha  including  the  annualised  investment  plus  the 
annual operating costs. 

Example farms 
Five farms are reported to use the system in Italy. 

Reference literature 
[ 240, Italy 2010 ] [ 241, Italy 2010 ] 

4.13.4.3 

Band spreader (or trailing hoses) and trailing shoes 

Description 
Flexible (plastic or rubber) hoses or pipes are supported by a 12–28 m wide bar mounted onto 
the slurry trailer, at intervals of 25–50 cm. The bar is positioned at a height so that hoses either 
hang a short distance (< 150 mm) above the soil or are dragged along the soil surface. Slurry is 
discharged just above ground level, in a series of 5–10 cm wide parallel bands (see Figure 4.97). 
The working width can be as low as 6 m and as wide as 36 m [ 575, UBA Germany 2011 ]. 

Intensive Rearing of Poultry or Pigs 

653 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 223, Denmark 2010 ] 

Figure 4.97:  Example of trailing hoses mounted on a bar 

A  development  of  the  band  spreader  is  the  trailing  shoe  application  system.  Trailing  shoe 
spreaders can have a working width of 3 m to 18 m but typically it is limited to 6–8 m [ 508, 
TFRN  2014  ].  The  individual  trailing  hoses  are  generally  situated  16–35 cm  apart.  The 
difference with trailing hoses is that the outlet of each slurry application pipe is equipped with a 
special distributing unit, which is usually designed as a shoe-like reinforcement that slides (or 
floats) on the soil surface. The design of the distributor is such that the crops are pushed aside or 
the herbage is parted more effectively than by the hose during the distribution process, even if 
the  hose is  very  close to the  ground.  In  this  way,  slurry  is deposited in  bands below the crop 
canopy,  onto  the  soil  surface,  with  the  minimum  herbage  or  crop  contamination  (see 
Figure 4.98) [ 575, UBA Germany 2011 ]. 

Source: [ 575, UBA Germany 2011 ] 

Figure 4.98:  Scheme of a trailing shoe spreader 

With  short  herbage,  the  distinction  between  the  two  techniques  can  be  less  obvious,  and 
therefore the ammonia emissions reduction efficiency of both machines is expected to be similar 
in  shorter  crops.  By  contrast,  for  taller  canopies,  a  trailing  shoe  can  be  more  effective  at 
reducing ammonia emissions than a trailing hose, not only due to the more precise delivery of 
the  slurry  to  the  ground  surface  and  the  reduced  degree  of  canopy  contamination,  but  also 
because the slurry discharge below the canopy reduces the air movement and temperature in the 
emitting zone [ 601, ALTERRA-IIASA 2012 ] [ 440, Webb et al. 2010] [ 508, TFRN 2014 ]. 

Achieved environmental benefits 
Because the slurry is placed directly on the ground in narrow bands, dispersion is avoided and, 
therefore,  the  total  surface  of  the  slurry  in  contact  with  air  is  significantly  smaller  than  if  the 
slurry was spread by a splash plate, and thereby the potential emission of ammonia and odour 
will be much smaller. 

654 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

The  efficiency  of  these  machines  can  vary  depending  on  the  height  of  the  crop.  In  particular,  the 
ammonia emission abatement potential is higher when slurry is applied below well-developed 
grass or crop canopies, rather than on bare soil, as the canopy protects the applied slurry from 
wind and solar radiation. With the use of the trailing shoe spreader, ammonia emissions can be 
further  reduced  because  slurry  can  be  precisely  placed  below  the  grass  canopy  with  the 
minimum canopy contamination. In fact, the trailing shoe allows the slurry to be incorporated 
into  the  upper  soil  layer  (0–3 cm)  [  575,  UBA  Germany  2011  ].  Therefore,  the  emission 
reduction efficiency of band spreading is dependent on the crop canopy and on the application 
precision  below  the  crop  canopy  with  a  minimal  contamination  of  herbage.  For  the  above 
reason, NH3 emission reductions have typically been found to be larger from trailing shoes than 
from trailing hoses [ 508, TFRN 2014 ]. 

Slurry  trailing  hoses  increases  nitrogen  utilisation,  with  a  consequent  reduced  purchase  of 
mineral  fertiliser  nitrogen,  thus  reducing  the  energy  consumption  and  associated  indirect 
emissions  for  manufacturing  the  fertiliser  [  602,  Denmark  2010  ].  Odour  emissions  are  also 
reduced compared to broadcast spread systems [233, Denmark 2010 ]. 

Cross-media effects 
As  for  the  broadcast  spreader,  there  is  a  potential  risk  of  emissions  of  nitrous oxide from  the 
surface application of slurry with trailing hoses. In a reported study, it was found that emissions 
of  nitrous  oxide  from  grassland  treated  with  slurry  were  0.2 kg  N2O-N  per  hectare  (which 
corresponds  to  an  emission  of  approximately  0.25–0.50 %  of  the  applied  nitrogen)  [  602, 
Denmark 2010]. However, reduced-NH3-emission application techniques do not always lead to 
greater emissions of N2O [ 440, Webb et al. 2010 ]. 

Trailing hoses may result in wide bands; therefore, in the Netherlands, they are not allowed on 
grasslands  [  35,  Netherlands  2010  ].  Band  spreading  also  increases  the  hydraulic  loading  rate 
per unit area, which can on some occasions (usually for high dry matter content slurries) impede 
infiltration into the soil [ 648, DEFRA 2011 ]. 

Environmental performance and operational data 
The system is commonly credited with 30–50 % ammonia emissions abatement in comparison 
with broadcast spreading [ 500, IRPP TWG 2011 ]. From Spain, a reduction efficiency of 25–
58 % is reported [ 235, Spain 2010 ] for band spreaders, whilst from Denmark 42 % is reported 
[ 233, Denmark 2010 ].  

With  the  use  of  trailing  shoes,  ammonia  emissions  are  reduced  by  around  50 %  [  234,  Spain 
2010  ]  [  248,  ADAS  2001  ],  and  up  to  60 %  [  35,  Netherlands  2010  ].  For  applications  to 
grasslands or to lands with a crop height over 10 cm, the advantages are increased. 

From  the  UK,  NH3  reduction  efficiencies  for  trailing  hose  and  trailing  shoe  slurry  spreading 
equipment  are  reported  typically  30 %  when  the  grass  is  short,  and  60 %  for  trailing  shoe 
equipment  when  the  grass  is  long  (> 10 cm)  compared  with  broadcast  application  [  648, 
DEFRA 2011 ].  

Technical considerations relevant to applicability 
Trailing  hoses  can  be  used  for  all  types  of  slurry,  e.g.  untreated  slurry,  digested  slurry  from 
biogas plants, the liquid fraction from slurry separation, and acidified slurry.  

The technique is applicable to grass and arable land, e.g. for applying slurry between rows of 
growing crops. The system with trailing hoses is less restrictive than that with shoes because it 
can be more widely used in standing crops without damage and is amenable to tramline systems. 
The system with trailing shoes is mainly applicable to grassland and arable crops at early stages 
or  with  widely  spaced  rows;  it  is  not  recommended  for  growing  solid-seeded  arable  crops, 
where the action of the shoe can result in excessive plant disturbance [ 508, TFRN 2014 ]. 

Intensive Rearing of Poultry or Pigs 

655 

 
 
 
 
 
 
 
 
 
Chapter 4 

Because of the width of the machine, the technique is not suitable for small, irregularly shaped 
fields or steeply sloping land due to the run-off potential. The hoses may also become clogged if 
the  dry  matter  content  of  the  slurry  is  high  (> 10 %),  or  if  the  slurry  contains  large  solid 
particles,  e.g. if  the  straw content  of  the slurry  is too  high.  However,  the  clogging  of  pipes  is 
usually  avoided  by  including  a  chopping  system  but  this  adds  significantly  to  the  cost  of  the 
system [ 508, TFRN 2014 ]. 

In cases where contractors are not used to carry out the slurry application, it is necessary for the 
farm  operator  to  be  able  to  handle  the  technology  correctly,  and  have  the  necessary  skills  to 
navigate big equipment on the field, in order to achieve the potential environmental benefits of 
the  technology  [  233,  Denmark  2010  ].  The  technology  depends  on  an  adequate  slurry  trailer 
with sufficient strength, and also on the equipment for mounting the trailing hose bar. 

Economics 
Ammonia emission reduction costs and spreading costs reported by Germany for different farm 
sizes are presented in Table 4.203. Compared with splash plates, band spreaders have a slower 
work rate and, therefore, higher tractor costs per unit of spread slurry. In comparison with splash 
plate machinery, repair costs are higher, due to the increased contact between the  soil and the 
machine and the increased number of moving parts [254, Webb J.M. et al. 2009 ]. 

A trailing hose system with the same capacity as  a broadcast spread system has an additional 
price  of  EUR 12 000–25 000.  Annual  operating  costs  are  considered  to  be  around  EUR 1  per 
m3/year (from EUR 0.9 to EUR 1.1 per m3/year) [ 233, Denmark 2010 ]. 

From the UK, the approximate investment costs for trailing shoe machines, without the tractor, 
are  reported  (February  2009  prices,  at  the  exchange  rate  of  EUR 1  =  GBP 0.88)  as  being 
between  EUR 32 000  and  EUR 46 500  for  a  tanker-mounted  machine  and  EUR 15 500  for  an 
umbilical-system-mounted  machine  [  254,  Webb  J.M.  et  al.  2009  ].  Operating  costs  for  the 
combined tractor and band spreader, in comparison with the use of a broadcast spreader (splash 
plate),  are  reported  in  Table 4.205.  The  reported  cost  data  take  into  account  machinery 
depreciation, the interest rate, insurance, fuel, maintenance and labour.  

Table 4.205:  Estimated operating costs for a band spreader system and a broadcast system for the 

application of slurry 

EUR/man-hour 

EUR/m3 of slurry 

30.6 
19.9 
50.5 

Band spreading 
Tractor 
Band spreader 
Total  
Broadcast spreading  
30.6 
Tractor 
7.7 
Splash plate 
Total 
38.3 
NB: Cost data are based on the following assumptions: 
 
  Assumed purchase prices: EUR 58 000 for a 150–180 HP tractor; EUR 13 600 for the splash plate tanker; 

Exchange rate of EUR 1 = GBP 0.88.  

1.02 
0.26 
1.28 

1.13 
0.74 
1.87 

 
 

EUR 32 000 for the band spreader. 
1 000 hours/year and 500 hours/year of operation respectively, for the tractor and the band spreader. 
The spreading rate of the broadcast spreader is assumed to be 9 % higher (30 m3/h) than the band spreader 
(27 m3/h). 

Source: [ 254, Webb J.M. et al. 2009 ] 

Extra  costs  calculated  in  Spain  are  shown  in  Table 4.206.  Cost  comparisons  are  made  with  a 
broadcast spreader (splash plate) without incorporation within 24 hours. 

656 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 4.206:  Extra  costs  related  to  slurry  application  with  band  spreading  techniques  in 

comparison with a broadcast spreader, in Spain 

Chapter 4 

Technique 

Trailing hose 
Trailing shoe 

Ammonia 
emissions 
reduction 
(%) 
40–51 
50 

EUR/m3 
slurry 

0.79–1.21 
0.92–1.41 

Extra costs 

EUR/tonne pig 
produced  

9.9–15.1 
11.5–17.6 

EUR/kg NH3 
abated 
3.6 (1)–5.5 (2) 
3.3 (3)–5.1 

(1) Calculated value. NH3 reduction 40 %. 
(2) NH3 reduction 40 %. 
(3) Calculated value.  
Source: [ 234, Spain 2010 ] [ 235, Spain 2010 ] [ 338, Piñeiro et al. 2009 ] [ 379, Spain 2009 ] 

It is estimated that the fuel consumption  for using trailing hoses is the same as for the splash 
plate technology. 

Driving force for implementation 
Nitrogen utilisation by plants is improved as emissions are reduced. Application of slurry with 
trailing hoses increases nitrogen utilisation compared to the splash plate technology. Therefore, 
there is an increased saving potential from a lower purchase of nitrogen mineral fertilisers [ 602, 
Denmark  2010  ]  [  440,  Webb  et  al.  2010  ].  Both  systems  of  slurry  band  spreading  allow 
spreading closer to field margins with a low risk of contaminating adjacent areas [ 508, TFRN 
2014 ]. 

In  addition,  the  time  available  for  spreading  is  increased.  As  contamination  with  slurry  is 
avoided  in  grassland,  the  required  period  between  slurry  application  and  grazing  or  silage 
harvest is reduced, extending the window of opportunity for slurry application. For arable crops, 
this extends the window for slurry application later into the spring when the crop height would 
normally exclude conventional surface broadcast slurry application because of crop damage and 
contamination risks [ 648, DEFRA 2011 ]. 

Finally,  the  possible  working  width  of  trailing  hoses  is  much  larger  than  for  the  splash  plate 
reference  system  (6–9  m)  [  508,  TFRN  2014  ].  An  added  advantage  for  trailing  shoes  is  the 
ability to apply slurry to relatively tall grass (e.g. to be cut for silage) with considerably reduced 
contamination of the crop or herbage by the slurry. 

Example plants 
As broadcast spreading (splash plate) has been banned in Denmark for approximately 10 years, 
all slurry  surface  applications  are  done  using  trailing  hoses.  Hence  the  practical  experience  is 
extensive and the durability of the system is very well tested. 

Reference literature 
[  35,  Netherlands  2010  ]  [  223,  Denmark  2010  ]  [  233,  Denmark  2010  ]  [  234,  Spain  2010  ] 
[ 235,  Spain  2010  ]  [  248,  ADAS  2001  ]  [  254,  Webb  J.M.  et  al.  2009  ]  [  379,  Spain  2009  ] 
[ 338,  Piñeiro  et al.  2009  ]  [  440, Webb  et  al.  2010 ]  [  500,  IRPP  TWG  2011  ]  [  508, TFRN 
2014 ] [ 575, UBA Germany 2011 ] [ 601, ALTERRA-IIASA 2012 ] [ 602, Denmark 2010 ] [ 
648, DEFRA 2011 ] 

4.13.4.4 

Shallow injector (open slot) 

Description 
Tines  or  disc  harrows  are  used  to  cut  slots  in  the  soil,  forming  grooves  into  which  slurry  is 
deposited. The injected slurry is fully or partially placed below the soil surface at a depth of 3–
8 cm  (typically  4–6 cm),  with  grooves  normally  left  open  after  slurry  application.  Open  slot 
injectors have a working width of ≤ 6 m to 12 m and individual hoses are generally situated at a 
spacing of around 20–30 cm from each other (see Figure 4.99). 

Intensive Rearing of Poultry or Pigs 

657 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 575, UBA Germany 2011 ] 

Figure 4.99:  Scheme of an open slot injector  

The application rate is adjusted so that excessive amounts of slurry do not spill out of the open 
slots onto the surface. 

Achieved environmental benefits 
In open slot injection, only a limited part of the slurry is in contact with the open air, reducing 
the ammonia and odour emissions. The actual odour and ammonia emissions reduction depends 
on how large a proportion of the applied slurry can be accommodated in the grooves formed. 

Experiments  on  grassland  show  that  nitrogen  utilisation  is  higher  after  shallow  injection  than 
after  surface  spreading  [  35,  Netherlands  2010  ].  This  means  that  the  potential  for  nitrate 
leaching to the environment is decreased.  

Slurry  application  with  injection  systems  increases  nitrogen  utilisation,  with  a  consequent 
reduced  purchase  of  mineral  fertilisers,  thus  reducing  the  energy  consumption  and  associated 
indirect emissions for manufacturing the fertiliser [ 602, Denmark 2010 ].  

Cross-media effects 
Since the slurry is placed under the soil surface, N2O emissions may be enhanced by the lack of 
oxygen,  which  facilitates  denitrification.  It  has  been  reported  that,  in  winter  crops  and  for 
grassland,  slurry  injection  increased  the  emissions  of  nitrous  oxide  by  25–100 %,  which 
corresponds to an emission of approximately 0.5–1.0 % of the applied nitrogen [ 237, Denmark 
2010 ] [ 238, Denmark 2010 ]. 

Slurry injection systems require greater tractor power (higher fuel consumption) than broadcast 
or  band  spreading  equipment  given  that  a  tine  or  a  disc  is  to  be  pulled  through  the  soil.  In 
comparison with a trailing hose system, the extra traction caused by injection with a narrow tine 
at a depth of  approximately 10 cm is  reported to be equivalent to  1.4–1.8 kW per tine (or per 
unit of injection aggregate) and it is estimated to be equivalent to 7.5 kW extra power per tonne 
of applied slurry. Generally, depending on the design of the injector tools, an extra force of 2–
4 kW per metre of injector boom is needed.  

Environmental performance and operational data 
Most  commercial  systems  available  in  Denmark  are  disc  aggregates.  The  injection  system  is 
dependent on an adequate slurry trailer with sufficient strength and equipment for mounting the 
injection bar; it is expected to last 10 years. 

Application by slot discs, through which the slurry is applied, avoids crop soiling; however, the 
turf is damaged. Other slot techniques aim to minimise this damage by means of a smaller slot 
depth  [  575,  UBA  Germany  2011  ]  or  minimum-till  cropland  prior  to  planting  [  601, 
ALTERRA-IIASA 2012 ]. 

658 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Ammonia  volatilisation  after  slurry  application  depends  on  various  factors  (e.g.  high 
temperatures), among which the most important are the time elapsing until incorporation and the 
amount  of  manure  that  is  left  in  contact  with  air.  Therefore,  the  actual  emissions  reduction 
achieved depends on the extent to which slurry is incorporated into the soil, i.e. on how large a 
proportion of the applied slurry can be accommodated in the grooves formed. To be effective in 
both  reducing  ammonia  emissions  and  increasing  the  availability  of  nitrogen  to  the  crop, 
injection should reach a depth of ≥5 cm and the space between injector tines should be ≤ 30 cm. 
The effect of slurry injection depends on the soil type, soil dryness, and the technique used.  

In France, the spreading of slurry using deep open slot injection (150 mm) allows a reduction of 
NH3 volatilisation of 60 % [ 259, France 2010 ]. For shallow open slot injection in grassland or 
cropland,  it  is  estimated  that  the  odour  reduction  after  slurry  application  is  between  0 %  and 
50 %, compared with the trailing hose system [ 236, Denmark 2010 ] [387, Denmark 2010 ]. 

Ammonia emissions associated with slurry application with injectors and relative improvements 
compared to broadcast and band spreading (trailing hose) are presented in Table 4.207.  

Table 4.207:  Ammonia emissions reduction achieved by slurry injection in comparison with surface 

application techniques, in Denmark 

Emissions of NH3-N  
(% of total N)  

Emissions reduction 
rates (%) 

Injection 

Soil/Crop/Season 

Trailing 
hoses 

Injectio
n 

Compared 
with 
trailing 
hose  

Compared 
with 
broadcast 
spreading 
(1) 

Source 

Open 

Open 

Open 

Closed 

Cropland with 
growing crops; spring 

11.7 

6.4 

Grassland; spring 

13.5 

10.1 

Grassland; summer 

17.6 

13.2 

Bare soil (cropland 
without crops;  
ploughed land); spring 

4 

0.68 

45 

25 

25 

83 

68 

56 

44 

90 

[ 603, Denmark 
2009 ] 
[387, Denmark 
2010 ] 
[387, Denmark 
2010 ] 

[ 604, Denmark 
2009 ] 

(1)  Data  calculated  on  the  basis  of  emissions  of  broadcast  spreading  technique  a  factor  of  1.7  higher  than 

compared to trailing hose, for Danish conditions. 

Source: [ 442, Hansen et al. 2008 ] 

Technical considerations relevant to applicability 
The  technique  is  applicable  to  many  types  of  slurry,  such  as  slurry  from  biogas  production, 
mechanically  separated  slurry,  acidified  or  untreated  slurry.  The  technique  is  suitable for 
application on grassland and on growing crops. It is not applicable on stony soil or on shallow 
or  compacted  soils,  where  it  is  impossible  to  achieve  a  uniform  penetration  to  the  required 
working depth. The applicability may be limited where crops may be damaged by  machinery. 
The method may not be applicable on very steeply sloping fields due to the risk of run-off along 
the injection slots. 

Economics 
Ammonia emission reduction costs and spreading costs reported by Germany for different farm 
sizes are presented in Table 4.203. 

For  the  purchase  of  the  injection  equipment,  an  extra  investment  of  EUR 33 000  is  needed 
compared to the trailing hose. Operating costs are EUR 2.4–2.6 per tonne of slurry applied on 
growing  winter  crops  and  EUR 2.2–2.4  per  tonne  of  slurry  distributed  on  grassland.  The 
additional costs compared to trailing hoses are presented in Table 4.207. 

Intensive Rearing of Poultry or Pigs 

659 

 
 
 
 
 
 
 
 
 
Chapter 4 

In a comparison with a broadcast spreader (splash plate) without incorporation within 24 hours 
after spreading, extra costs have been calculated under Spanish conditions (assuming at least a 
50 %  reduction  in  emissions),  ranging  between  EUR 1.01  and  EUR 1.41  per  m3  of  applied 
slurry, or, in other units, from EUR 12.6 to EUR 17.6 per tonne of pig produced [ 379, Spain 
2009 ]. 

Table 4.208  reports  additional  fuel  requirements,  as  well  as  extra  costs  associated  with  open 
(shallow)  and  closed  (deep)  slot  injection,  for  different  operating  conditions  applied  in 
Denmark. 

Table 4.208:  Extra energy and costs associated with open (shallow) and closed (deep) slot injection 

for different operating conditions applied in Denmark 

Injection 
type 

Scope of 
application 

Open 

Open 

Closed 

Cropland with 
growing crops 
Grassland 
Bare soil 
(cropland without 
crops; ploughed 
land) 

Working 
depth 

Extra fuel consumption 

cm 

Litres/ha 

Litres/tonne of 
applied slurry (2) 

Extra annual 
operating costs (1) 
EUR/m3 slurry 
applied annually 

3–8 

3–8 

2–5 

2–5 

0.1–0.2 

0.1–0.2 

0.9–1.1 

0.7–1 

10–15 

4.9 

0.2 

0.66 

(1) Costs are compared to the trailing hose system with a total cost of EUR 1.5/m3. 
(2) Slurry application at 25 tonnes per hectare. 
Source: [ 236, Denmark 2010 ] [ 237, Denmark 2010 ] [ 238, Denmark 2010 ] 

Driving force for implementation 
The  improved  efficiency  in  nitrogen  distribution  results  in  improved  ammonia  utilisation  by 
plants which ultimately results in economic savings from the reduced use of mineral fertilisation 
for the same quantity of crop.  

Example plants 
The technique with deep injection (150 mm) is largely applied in France [ 259, France 2010 ]. 
In  Denmark,  about  15 %  of  pig  slurry  and  53 %  of  cattle  slurry  were  applied  by  injection  in 
2004.  Injection  of  slurry  to  grassland  and  bare  soil  has  been  growing  in  Denmark;  it  is 
considered an available and proven technique.  

Reference literature 
[ 35, Netherlands 2010 ] [ 236, Denmark 2010 ] [ 237, Denmark 2010 ] [ 238, Denmark 2010 ] [ 
259, France 2010 ] [ 379, Spain 2009 ] [387, Denmark 2010 ] [ 442, Hansen et al. 2008 ] [ 508, 
TFRN  2014 ]  [  575,  UBA  Germany  2011  ]  [ 601,  ALTERRA-IIASA  2012  ]  [ 602,  Denmark 
2010 ] [ 603, Denmark 2009 ] [ 604, Denmark 2009 ] 

4.13.4.5 

Deep injector (closed slot) 

Description 
Cultivators with sharp S-shaped tines or disc harrows are used to cultivate the soil and deposit 
slurry  into  it,  before soil  closes  the  groove  again, fully  covering  the  slurry  by  means  of  press 
wheels or rollers fitted behind the injection tines or discs. Typically, the working depth of the 
closed  slot  deep  injector  ranges  between  10 cm  and  15 cm  or,  in  some  cases,  deeper,  up  to 
20 cm. The working width is generally 3–6 m, and the individual injectors are normally placed 
at intervals of 20–40 cm (see Figure 4.100).  

660 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 575, UBA Germany 2011 ] 

Figure 4.100:Scheme of a closed slot injector  

Achieved environmental benefits 
Since the exposed slurry surface area is eliminated by covering almost all slurry below the soil 
surface, odour and ammonia emissions are effectively reduced. Higher nitrogen utilisation may 
result in a decreased potential for nitrate leaching to the environment.  

Cross-media effects 
See Section  4.13.4.4. Deeper injection may not lead to higher N2O emissions as the increased 
length  of  the  diffusion  path  from  the  area  of  denitrification  to  the  soil  surface  may  lead  to  a 
greater proportion of denitrified nitrogen being emitted as N2 [ 508, TFRN 2014 ]. 

Environmental performance and operational data 
Most  commercial  systems  available  on  the  Danish  market  are  tine  aggregates.  The  system 
requires  an  adequate  slurry  trailer  with  sufficient  strength  and  equipment  for  mounting  the 
injection bar. The injection system is expected to last 10 years. 

Compared  with  the  surface  distribution  on  bands  (trailing  hose),  the  reduction  of  ammonia 
emissions is about 85 %, which corresponds to an average reduction of around 90 %, compared 
to  broadcast  spreading  [  35,  Netherlands  2010  ].  The  effectiveness  of  ammonia  abatement 
increases  with  working  depth.  An  example  of  ammonia  emission  reduction  for  closed  slot 
injection  is  reported  in  Table 4.207,  in  comparison  with  open  slot  injection.  The  ammonia 
volatilisation rate of the technique of deep injection on arable land is not influenced by weather 
conditions [ 232, Huijsmans et al. 2009 ]. For the deep injection of slurry into bare soil, odour 
emissions  are  reduced  to  a  minimum,  at  least  for  a  number  of  odoriferous  substances  [  236, 
Denmark 2010 ].  

An  increased  utilisation  of  the  applied nitrogen  (and therefore  higher  yields)  has  been proven 
with the use of the technique, resulting in a potential for decreased leaching of nitrates to the 
environment. The slurry is fully covered after injection, by closing the slots. Deeper injection is 
required  when  greater  volumes  of  manure  have  to  be  injected,  in  order  to  avoid  manure 
oozing/leaking to the surface [ 601, ALTERRA-IIASA 2012 ].  

The working depth and ease of soil penetration increase with the soil's water content. Thus, an 
estimate of soil strength can be used as one parameter to determine the optimum timing for the 
slurry injection, in order to achieve sufficient working depths [ 440, Webb et al. 2010]. On the 
other hand, it has to be stressed that deep injection has to be performed within the capacity of 

Intensive Rearing of Poultry or Pigs 

661 

 
 
 
 
 
 
 
 
Chapter 4 

the soil to hold water to avoid drainage. In the UK, for example, soil moisture deficits should be 
no less than 20 mm for an application of 100 m3/ha [ 624, IRPP TWG 2013 ]. 

Technical considerations relevant to applicability 
The  technique  is  applicable  to  many  types  of  slurry,  such  as  slurry  from  biogas  production, 
separated fractions and acidified or untreated slurry. 

It is applicable on arable land without vegetation. It is not applicable during the vegetation of 
the  crops.  It  is  mainly  restricted  to  the  pre‐sowing  season  and  widely  spaced  row  crops  (e.g. 
maize).  Mechanical  damage  (cutting  of  the  roots  during  injection)  may  decrease  yields  in 
growing solid-seeded arable crops. Yield reductions may also derive from drying of the soil and 
anaerobic and toxic conditions from concentrating the manure in the injection slots. This effect 
may be greater with multiple applications over the season [ 440, Webb et al. 2010]. 

Other  limitations  include  soil  depth,  soil  wetness,  clay  and  stone  content,  and  slope.  The  soil 
type and conditions have to allow effective closure of the slot; otherwise, the added benefit of 
the full coverage of slurry is not attained [ 508, TFRN 2014 ]. Deep injection is limited to times 
when  soils  are  dry  enough;  otherwise,  there  may  be  a  high  risk  of  run-through  and  leaching 
below the crop root zone [ 624, IRPP TWG 2013 ]. 

Considerable tractor power is required. An increased risk of leaching is reported in the case of 
tile-drained  soils  [  601,  ALTERRA-IIASA  2012  ].  Deep  injection  should  be  avoided  until 
spring when the soil has dried out sufficiently. A lower application rate, in connection with the 
prevailing farm and soil conditions, can reduce the risk of nitrates loss [ 657, Bailey T. 2012 ]. 
Deep injection on grassland has been proven not to be practicable [ 35, Netherlands 2010 ]. The 
technique is applicable to grassland when changing to arable land or when reseeding. 

Economics 
For  the  purchase  of  the  injecting  equipment,  an  extra  investment  of  EUR 33 000  is  needed 
compared  to  the  trailing  hose.  Systems  would  run  for  around  EUR 2.2  per  tonne  of  slurry 
applied  on  bare  soil  [  236,  Denmark  2010  ].  The  additional  costs  of  closed  slot  injection,  in 
comparison with open slot injection, are presented in Table 4.207. Ammonia emission reduction 
costs  and  spreading  costs  reported  by  Germany  for  different  farm  sizes  are  presented  in 
Table 4.203 [ 575, UBA Germany 2011 ]. 

Driving force for implementation 
The driving force is increased utilisation of the applied nitrogen, with savings from the reduced 
use of mineral fertilisers.  

Example plants 
Injection of slurry to bare soil has been growing in Denmark and is considered  a well-known, 
available and proven technology. 

Reference literature 
[ 35, Netherlands 2010 ] [ 232, Huijsmans et al. 2009 ] [ 236, Denmark 2010 ] [ 440, Webb et 
al. 2010 ] [ 508, TFRN 2014 ] [ 575, UBA Germany 2011 ] [ 601, ALTERRA-IIASA 2012 ] [ 
624, IRPP TWG 2013 ] [ 657, Bailey T. 2012 ] 

662 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.13.5 

Incorporation of solid manure or slurry 

Description 
Incorporation of solid manure (or the solid fraction generated from the mechanical separation of 
slurry)  or  slurry  (or  the  liquid  fraction  generated  from  the  mechanical  separation  of  slurry) 
spread  on  the  soil  surface,  e.g.  by  trailing  hoses,  is  carried  out  either  by  ploughing  or  other 
shallow  cultivation  equipment,  such  as  tine  or  disc  harrows  depending  on  the  soil  type  and 
conditions. The manure is completely mixed with the soil or buried underneath it as rapidly as 
possible after spreading on the surface.  

Achieved environmental benefits 
As  ammonia  losses  take  place  quickly  after  spreading,  ammonia  emissions  and  odour  are 
reduced by limiting the time of exposure of the manure to air.  

The reduction of NH3 volatilisation depends on the incorporation procedures, in particular the 
time  lag  between  application  and  incorporation,  as  well  as  the  weather  conditions  between 
application  and  incorporation,  and  the  degree  of  burial  in  the  soil  [  508,  TFRN  2014  ].  High 
emission  reductions  can  be  achieved  with  immediate  incorporation  (as  soon  as  possible  after 
spreading);  in  contrast,  a  large  part  of  the  ammonia  emission  has  already  occurred  when 
incorporation is carried out after 4, 6, 12 or 24 hours [ 35, Netherlands 2010 ]. 

Cross-media effects 
Single-run equipment is heavy and can produce problems of soil compaction, while equipment 
for double-run incorporation is lighter but the tractor consumes more fuel.  

Incorporation  of  solid  manure  into  soil  may  increase  direct  emissions  of  N2O.  The  nitrogen 
availability of solid manure for a growing crop is lower than that of liquid manure, due to the 
higher  concentration  of  organic  matter  which  enhances  nitrogen  immobilisation  and 
denitrification.  Whether  solid  manure  leads  to  higher  NH3  and  N2O  emissions  than  slurry  or 
mineral fertilisers depends on several factors, including the manure C : N ratio and the organic 
matter degradability [ 517, Petersen et al. 2011 ]. On the other hand, the results of other studies 
remain ambiguous on the impact of incorporation of solid manure after application, with respect 
to N2O emissions [ 441, Webb et al. 2012 ]. 

For untreated and treated slurry, contrasting results have been reported on N2O emissions. The 
variability  depends  mainly  on  the  soil  properties  and  the  organic  matter  content  of  the  slurry  
[ 517, Petersen et al. 2011 ].  

If no crops are present to take up the readily available nitrogen, manure incorporation increases 
the risk of nitrogen loss via leaching, with a possible shift of pollution from air to water, but it 
reduces the risk of surface run-off from subsequent rainfall events. For this reason, the timing of 
slurry and solid manure application needs to balance all these aspects [ 508, TFRN 2014 ].  

Environmental performance and operational data 
To  achieve  incorporation  immediately  after  spreading,  a  second  tractor  is  needed  for  the 
incorporation  machinery,  which  must  follow  closely  behind  the  manure  spreader.  Usually  the 
incorporation  is  carried  out  by  a  second  person  working  with  the  plough,  or  another  tool, 
depending  on  the  type  and  the  conditions  of  the  soil.  However,  it  could  also  be  done  by  one 
person,  in  which  case  the  manure  spread  on  the  field  (one  tank  load)  is  incorporated  before 
reloading the tank.  

Figure 4.101  shows  incorporation  equipment  combined  with  a  large  tanker  owned  by  a 
contractor, but this combination is also possible with a smaller tanker and a separate tractor. In 
this way, the incorporation can be done together with the manure spreading in only one handling 
[ 406, Netherlands 2002 ]. 

Intensive Rearing of Poultry or Pigs 

663 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Source: [ 406, Netherlands 2002 ] 

Figure 4.101:Incorporation equipment combined with a big tanker 

For  immediate  incorporation  on  small  fields  (approximately  2  ha),  if  only  one  person  is 
available to spread and incorporate the manure, there is a significant advantage in incorporating 
the manure as soon as each pass of the spreader is complete (except for very small fields). This 
causes an increase of 15 % in the time spent on the operation. 

Using two people (simultaneous pass) does not reduce NH3 emission, compared with one person 
operating both machines (spreading and then incorporating at the end of each pass), because the 
work rate of the incorporator is usually lower than that of the applicator. Using two operators 
does,  however,  save  time,  ranging  from  36 %  on  a  2  ha  field  to  51 %  on  a  20  ha  field.  The 
absolute duration of the operation may be more important than the percentage of time saved. On 
a 2 ha field, a reduction in time spent from 3.5 h to just over 2 h may be of little importance in 
the  overall  farm  management;  however,  on  a  10 ha  field,  a  reduction  in  time  from 
approximately 20 h to 10 h would allow the job to be completed in 1 day [ 243, Webb J. et al 
2006 ]. As a conclusion, the incorporation strategy needs to be properly designed, according to 
the size of the field, the work rates of incorporation equipment, and the available workforce.  

Immediate  incorporation,  and  thus  a  minimal  time  delay  between  manure  application  and 
incorporation,  is  not  always  achievable.  Some  time  may  pass  between  surface  spreading  and 
incorporation  during  which  ammonia  volatilisation  takes  place  from  the  manure  spread  on  the 
surface.  

The degree of ammonia emissions reduction also depends on the method of incorporation. Direct 
incorporation of manure by a mouldboard plough results in a higher reduction efficiency than 
incorporation  by  a  fixed  tine  cultivator  or  a  disc  harrow,  due  to  the  deeper  working  depth 
achieved  by ploughing [ 35, Netherlands 2010 ] [ 243, Webb J. et al 2006 ] and the burial of 
100 %  of  the  slurry/manure.  However,  it  is  sometimes  possible  that  tines  or  discs  are  more 
efficient  than  ploughing,  because  of  the  faster  work  rates  achieved  that  let  the  slurry  remain 
exposed  on  the  surface  for  a  shorter  time  before  being  well  mixed  with  the  soil  by  cultivation. 
Meanwhile,  with  mouldboard  ploughing,  there  will  be  a  longer  overall  time  lag  between 
spreading and incorporation [ 35, Netherlands 2010 ] [ 243, Webb J. et al 2006 ] [ 500, IRPP 
TWG, 2011 ].  

664 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
A summary of experiment results concerning  the  ammonia emissions reduction achieved with 
the use of different types of application machinery is presented in Table 4.209. 

Chapter 4 

Table 4.209:  Summary  of  experiment  results  on  ammonia  emissions  reduction  with  different 

manure incorporation equipment 

Slurry 

Type of manure  

Incorporation 
equipment 

Reduction in NH3 emissions,  
compared with surface broadcast application  
Average value (1) 
(%) 
92 
80 
66 
68 
91 
63 
57 
90 

Range (2) 
(%) 
78–99 
69–90 
NI 
60–69 
86–95 
NI 
NI 
NI 

Plough 
Disc 
Tine 
Harrow 
Plough 
Disc 
Tine 
Harrow 
(1) Data represent the average of the reported reduction efficiencies.  
(2) The range is obtained by calculating the average values of each publication considered.  
NB: NI = no information provided. 

Solid 

Source: [ 440, Webb et al. 2010] 

Other  experiment  results,  presenting  ammonia  emissions  expressed  as  kg/ha  NH3-N  or  as a 
percentage of the TAN applied, and the effect of different incorporation methods, are presented 
in Table 4.210. Ploughing results in greater emission reductions than other types of machinery 
for shallow cultivation. 

Table 4.210:  Average  ammonia  emissions  and  reduction  efficiencies  from  the  spreading  of  solid 
manures followed by immediate incorporation using different equipment  

Manure 
type 

Plough 

No 
incorporation 
NH3-N  TAN   NH3-N  TAN  Reduction  NH3-N  TAN  Reduction  NH3-N  TAN  Reduction 
kg/ha 
63.1 
71.5 
27.6 

 %  kg/ha 
68 
67 
56 

kg/ha 
25.4 
22.3 
5.6 

kg/ha 
26.2 
33.7 
5.2 

 % 
95 
96 
100 

 % 
60 
69 
80 

 % 
58 
53 
81 

 % 
26 
21 
13 

 % 
26 
31 
11 

 % 
4 
3 
2 

Tine 

Disc 

Pig 
3.2 
Layer 
2.6 
0.0 
Broiler 
Source: [ 243, Webb J. et al 2006 ] 

The  effect  of  the  machinery  used  for  incorporation  and  the  time  delay  after  spreading  solid 
manure until incorporation, in comparison with the ammonia emissions without incorporation, 
are  presented  in  Table 4.211.  Data  are  derived  from  a  review  of  reports  and  peer-reviewed 
articles. 

Intensive Rearing of Poultry or Pigs 

665 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Table 4.211:  Reduction of ammonia emissions achieved by the incorporation of solid manure after 

application 

Animal 
category 

Fattening pigs 
Broilers 
Broilers 
Broilers 
Laying hens 

Incorporation  
(time lag after application) 
4 h 

≥ 24 h 

< 4 h 

Ammonia emissions reduction  
as % of emissions measured without 
incorporation 
64 (9) 
61 (5) 
81 (2) 
44–53 (3) 
NI 

63 (8) 
37 (5) 
77 (2) 
24 (2) 
NI 

92 (4) 
NI 
NI 
NI 
97 (1) 

Laying hens 

79–83 (3) 

NI 

NI 

Average emission reduction as % of emissions 
measured without incorporation 

Equipment used for 
incorporation 

Plough 
Disc 
Plough 
Disc - Harrow 
Mouldboard plough 
Harrow - Chisel plough - 
Rotary cultivator 

Pigs 
Poultry 
NB: The number of datasets used is indicated in brackets; NI = no information provided. 

4–24 h 
56 
50 

< 4 h 
92 
85 

Source: [ 441, Webb et al. 2012 ] 

From  Denmark,  calculated  emissions  for  the  application  of  solid  pig  manure  followed  by 
incorporation with different time lags and equipment are presented in Table 4.212. 

Table 4.212:  Calculated ammonia emissions from  the  application of  solid  pig  manure followed by 

incorporation, with different equipment and time lags 

Incorporation 
method 

Ploughing 
Ploughing 
Ploughing 
Ploughing 
Harrowing 
Harrowing 
Harrowing 
Harrowing 

Season 

No incorporation 

6 hours 

4 hours 

1 hour 

NH3-N emission as a % of TAN 

Incorporation 

Spring 
Summer 
Autumn 
Winter 
Spring 
Summer 
Autumn 
Winter 

65 
80 
55 
45 
65 
80 
55 
45 

39 
48 
33 
27 
41 
54 
30 
22 

22 
32 
12 
7 
36 
48 
27 
20 

13 
16 
11 
9 
27 
35 
21 
17 

Source: [ 442, Hansen et al. 2008 ] 

An extensive literature review [ 441, Webb et al. 2012 ], supported by a statistical analysis of 
measurement  results,  concluded  that  incorporation  of  solid  pig  and  poultry  manure  after 
application  results  in  increased  N2O  emissions.  However,  a  wide  variability  of  data  has  been 
observed. Results are presented in Table 4.213. 

Table 4.213:  Emissions of N2O after spreading and incorporation of solid manure 

Parameter 

Average value after spreading 
Median value after spreading 
Average value after incorporation 
Source: [ 441, Webb et al. 2012 ] 

Emissions of N2O-N as % of TAN 

Pig manure 
0.3 
2.8 
3.5 

Poultry manure 
0.1 
0.6 
8.9 

666 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
The influence of the contrasting effects of ammonia emissions reduction during manure storage, 
nitrogen  loss  during  spreading  and  incorporation  of  broiler  litter,  and  nitrate  losses  through 
leaching have been investigated; the results are presented in Table 4.214. 

Chapter 4 

Table 4.214:  Example of the effect of storage conditions and application conditions of broiler litter 

on subsequent emissions during application 

Storage conditions 

Conventionally stored 

Sheeted heap 

Application 
conditions 
Surface spreading 
Surface spreading and 
ploughing the soil 
within 4 hours 

Source: [ 536, Sagoo et al. 2007 ] 

NH4-N losses as % of 
total N ex-housing 
24.6 

NO3-N losses as % of 
total N ex-housing 
5.9 

4 

13.7 

Data from different geographical areas report that reductions in ammonia emissions of 70–80 % 
are achievable when solid manure is directly incorporated within 2 hours, and a reduction of 60– 
70 %  if  it  is  incorporated  within  4  hours  [  35,  Netherlands  2010  ]  [  259,  France  2010  ].  The 
incorporation  within  6–24  hours  after  application  with  a  broadcast  spreader  reduces  ammonia 
emissions  by  16–42 %,  under  Spanish  climatic  conditions,  compared  to  broadcast  spreading 
without incorporation within 24 hours [ 239, Spain 2010 ]. In France, it is considered that, for a 
satisfactory ammonia reduction rate, incorporation has to be carried out less than 12 hours after 
spreading [ 500, IRPP TWG 2011 ]. 

Table 4.215 shows that the incorporation of broiler litter is always effective  compared to non-
burial, but also that emissions from landspreading depend on the readily available nitrogen that 
may be left in manure that has been covered during storage. The results in the table imply losses 
during  storage  of  13.2 %  and  1.3 %  for  the  conventionally  uncovered  stored  manure  and  the 
sheet-covered manure, respectively [ 207, ADAS 2004 ]. This means that the readily available 
nitrogen that is not lost during storage may be largely lost at landspreading if incorporation is 
not quick enough or if it is not applied. In other words, rapid incorporation is necessary in order 
to realise the reductions in ammonia loss from sheeted storage. If the sheeted broiler litter is not 
rapidly incorporated into the soil following landspreading, the ammonia saved during storage is 
subsequently easily lost at landspreading. 

Table 4.215:  Comparison  of  ammonia  losses  from  different  procedures  for  landspreading  of 

differently stored broiler litters 

Type of application and 
incorporation 

Surface 
Ploughed within 4 hours 
Incorporation  by  discs  within  4 
hours 
Ploughed within 24 hours 
Incorporation  by  discs  within  24 
hours 
Source: [ 207, ADAS 2004 Gleadthorpe] 

Losses upon spreading 
Sheeted 
25.8 
2.8 
10.8 

Conventional 
11.4 
2.4 
6.3 

System losses 

Conventional 
24.6 
15.6 
19.5 

Sheeted 
27.1 
4.1 
12.1 

2.5 
8.0 

6.9 
21.9 

15.7 
21.2 

8.2 
23.2 

Technical considerations relevant to applicability 
The  manure  landspreading  itself  only  takes  a  very  short  time  (hours)  and  there  is  no 
organisational  need  to  wait  for  the  incorporation.  Incorporation  within  4  hours  may  be 
considered  difficult  to  organise,  because  the  farmers  do  not  usually  own  all  the  machinery 
required  and  do  not  have  enough  personnel.  The  field  size  and  the  available  machinery  for 
incorporation might also affect the timely completion of manure incorporation, as the spreading 

Intensive Rearing of Poultry or Pigs 

667 

 
 
 
 
 
 
 
 
 
Chapter 4 

rate is usually higher than the ploughing rate. Furthermore, because field works often need to be 
completed on a task-by-task basis or a field-by-field basis, interruption of spreading (i.e. after 4 
hours)  in  order  for  the  operator  to  change  task  to  ploughing,  having  to  swap  tractors  or  even 
attached implements, will cause a delay [ 624, IRPP TWG 2013 ]. The farmers therefore need to 
rely on contractors and therefore the timing of operations is not completely under their control. 
Additionally, weather conditions or poor light can stop working progress; for example, it would 
not be good practice to work on waterlogged land as it is harmful for soil management. 

However, it is also reported that it is doubtful whether organising incorporation within a shorter 
time than 12 or 24 hours may cause a logistical problem [ 35, Netherlands 2010 ]. Where labour 
or machinery requirements limit the option for immediate incorporation, manure incorporation 
within 4 hours is reported to be feasible, even for small farms [ 508, TFRN 2014 ]. 

In  the  Netherlands,  the  technique  of  incorporating  the  manure  within  4  hours  is  commonly 
applied. A good matching of logistics (tank spreading capacity and incorporation capacity) is a 
very important factor for achieving incorporation within 4 hours [ 406, Netherlands 2002 ].  

The  applicability  of  the  technique  is  limited  to  arable  land  that  can  easily  be  cultivated  after 
spreading  solid  manure  or  slurry.  For  grassland  or  conservation  tillage,  incorporation  is  not 
possible, or it is only possible when changing to arable land (e.g. in a rotation system) or when 
reseeding. It is not applicable to cultivated land with growing crops that can be damaged by the 
incorporation  of  solid  manure  or  slurry.  For  slurry,  the  technique  is  not  applicable  after 
landspreading using shallow or deep injectors. 

Economics 
Extra  costs  reported  by  Spain  for  slurry  incorporation  after  application  by  a  splash  plate 
(broadcast spreader) are presented in Table 4.216.  

Table 4.216:  Extra  costs  for  the  incorporation  of  slurry  applied  by  a  broadcast  spreader  with  a 
splash plate, in comparison with no incorporation within 24 hours, in Spain 

Method of 
incorporation 

Mouldboard 
plough  
Cultivator  

Ammonia 
emissions 
reduction 
(%) 

16–40 

EUR/m3 
slurry 

0.53–0.61 

0.23–0.26 

Extra costs 

EUR/tonne pig 
produced  

6.6–7.6 

2.9–3.3 

EUR/kg NH3 
abated 

3.2 (1)–3.7 (2) 

NI 

(1) Calculated value. NH3 reduction 30 %.  
(2) NH3 reduction 30 %.  
NB: NI = no information provided.  
Source: [ 338, Piñeiro et al. 2009 ] [ 379, Spain 2009 ] 

Costs  for  direct  incorporation  of  solid  manure  are  reported  to  be  in  the  range  of  EUR 0.5  to 
EUR 2 per kg of NH3-N saved [ 601, ALTERRA-IIASA 2012 ]. Ammonia emission reduction 
costs,  spreading  and  incorporation  costs,  reported  by  Germany  for  different  farm  sizes,  are 
presented in Table 4.203 [ 575, UBA Germany 2011 ]. 

Driving force for implementation 
Regulations in many Member States are enforcing slurry/manure incorporation after spreading. 
For example, in Denmark, slurry applied on bare soil must be incorporated within 6 hours [236, 
Denmark  2010  ].  In  Germany  and  the  Netherlands,  there  is  an  obligation  for  immediate 
incorporation.  In  the  UK,  24  hours  is  the  maximum  incorporation  time  interval  after  manure 
spreading  [  624,  IRPP  TWG  2013  ].  Fast  incorporation  of  solid  manure  or  slurry  improves 
nitrogen  availability  (fertiliser  value  of  manure)  for  crop  production  by  preventing  nitrogen 
losses [ 517, Petersen et al. 2011 ]. 

668 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Some incorporation activities may be seen as a tillage operation that a farmer already planned to 
do (including when no manure was applied). In that case, incorporation is not an extra activity 
(labour, energy, costs) that should be counted as contributing to extra costs for the reduction of 
emissions [ 35, Netherlands 2010 ]. 

Chapter 4 

Example plants 
Incorporation is widely applied. 

Reference literature 
[ 35, Netherlands 2010 ] [ 207, ADAS 2004 ] [ 236, Denmark 2010 ] [ 239, Spain 2010 ] [ 243, 
Webb J. et al 2006 ] [ 259, France 2010 ] [ 338, Piñeiro et al. 2009 ] [ 379, Spain 2009 ] [ 406, 
Netherlands  2002  ]  [  440,  Webb  et  al.  2010  ]  [  442,  Hansen  et  al.  2008  ]  [  441,  Webb  et  al. 
2012 ] [ 500, IRPP TWG 2011 ] [ 536, Sagoo et al. 2007 ] [ 508, TFRN 2014 ] [ 517, Petersen 
et al. 2011 ] [ 575, UBA Germany 2011 ] [ 601, ALTERRA-IIASA 2012 ] [ 624, IRPP TWG 
2013 ] 

Intensive Rearing of Poultry or Pigs 

669 

 
 
 
 
Chapter 4 

4.14  Techniques to reduce noise emissions 

Description 
Noise is still not considered an issue of great environmental importance in the sector, but, with 
rural  areas  becoming  increasingly  populated,  noise  (as  well  as  odour)  emissions  may  become 
more relevant. In general, measures to prevent or reduce noise emissions are necessary when the 
farm  is  located  close  to  an  area  that  requires  protection  (e.g.  residential  area)  and  a  noise 
problem occurs. At the same time, reduced on-farm noise levels are considered to be beneficial 
for animal production itself as it requires a quiet and peaceful environment. 

In the case of new farms, a basic preventive measure is to select a location for the farm and/or 
the equipment with sufficient distance to existing or planned sensitive receptors, e.g. residential 
areas. In general, noise reduction can be achieved by: 

 

 

 

 

 

planning of activities on the farm premises; 

using natural barriers; 

applying low-noise equipment; 

applying technical measures to equipment (limited); 

applying additional noise abatement measures. 

For ventilation systems, preference should be given, wherever possible, to high-efficiency fans. 
Noise radiation increases with impeller diameter and speed. For a given diameter, a low-speed 
fan is quieter than a high-speed fan. 

In  order  to  reduce  noise  emissions  from  machinery  and  implements,  it  is  possible  in  certain 
cases  to  adopt  passive  noise  abatement  measures  (encapsulation  or  sound  screens,  e.g.  made 
from  straw  bales  which  absorb  and  deflect  the  radiated  sound).  Silencers/sound  attenuation 
devices in waste airshafts have not proven successful, as they quickly become ineffective due to 
dust deposits. Potential techniques to control or reduce noise emissions from a number of on-
farm activities are described below.  

Achieved environmental benefits 
Noise emissions are reduced. 

Cross-media effects 
Side-mounted  fans  are  less  effective  in  dispersing  ammonia,  odour  and  dust  emissions  than 
roof-mounted fans. Increasing the number of fans combined with a reduction of their size would 
increase  the  energy  consumption  and  may  compromise  animal  welfare  [  624,  IRPP  TWG 
2013 ]. 

Environmental performance and operational data 
Noise management plan 
The first step to deal with noise emissions, when are identified as having a potential impact, is 
to  produce  a  noise  management  plan,  i.e.  a  noise  prevention  and  reduction  programme.  It  is 
designed  to  identify  the  source(s),  to  measure  noise  emissions,  to  measure/estimate  noise 
exposure, to characterise the contributions of the sources and to implement elimination and/or 
reduction  measures,  according  to  their  cost  and  ease  of  implementation  [  624,  IRPP  TWG 
2013 ]. 

670 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
A noise management plan includes the following elements:  

Chapter 4 

 

 

 

 

 

a protocol containing appropriate actions and timelines; 

a protocol for conducting noise monitoring; 

a protocol for response to identified noise events; 

a noise reduction programme designed, for example, to identify the source(s), to monitor 
noise  emissions,  to  characterise  the  contributions  of  the  sources  and  to  implement 
elimination and/or reduction measures; 

a  review  of  historical  noise  incidents  and  remedies  and  the  dissemination  of  noise 
incident knowledge. 

Management measures 
The  impact  of  activities  with  potentially  high  noise  levels  can  be  reduced  considerably  by 
avoiding operating at nights and on weekends. Unnecessary disturbance of the animals during 
feeding and inter-house transfer should also be avoided, as this generally gives rise to increased 
noise levels. However, it is less stressful for birds to be handled in the dark and this is why bird 
catching  and  subsequent  transport  often  take  place  at  night  or  in  the  early  morning  [ 40, 
NFU/NPA 2001 ].  

The noise of the highest intensity in pig farms is created during  the  blood testing of pigs and 
nose-ringing  of  sows  (when  it  is  permitted  in  accordance  with  Directive  2008/120/EC  and 
national legislation) [ 624, IRPP TWG 2013 ].  

Other operational measures include provisions for noise control during maintenance activities. 

Prevention of continuous noise 
i.  Choice of ventilation system or equipment 

One method of eliminating noise from fans is to employ natural ventilation systems, including 
ACNV, which also have energy-saving benefits. Fans can be selected to minimise noise. High-
speed  fans  with  two  pole  motors  should  be  avoided  because  they  tend  to  be  very  noisy.  In 
addition,  the  smaller  dimensions  of  these  fans  are  also  associated  with  smaller  openings  and 
cowls that have a higher resistance to airflow. Generally, the slower the fan, the less noise it will 
make. Particularly for poultry, cowls and air inlets can be designed with a sufficient area so as 
to avoid any unnecessary pressure drops. 

In certain circumstances, fan noise can be reduced by inlet silencers. The nature of the exhaust 
air from livestock units makes this option suitable only for fan-pressurised ventilation systems, 
which are not commonly applied. 

ii.  Design of ventilation and building construction 

The  location  of  the  fans  is  a  significant  factor.  Employing  low-level  extraction  fans  on  side 
walls will be more effective for reducing the propagation of noise from within buildings than 
roof-mounted units, as the noise can be better absorbed by the building structure or by the earth 
or vegetation. For poultry farms, low-level fans can also facilitate dust control, but they may be 
less effective at dispersing odour than high-level fans. In other cases, roof fans when operated 
properly  generate  similar  noise  levels  as  those  installed  on  the  sides  of  the  walls  
[ 624, IRPP TWG 2013 ].  

System resistance affects  the fan and ventilation system performance. Fan installations should 
be  designed  with  adequate  inlet  and  outlet  areas  to  ensure  an  optimum  performance.  An 
efficient  design  enables  the  minimum  number  of  fans  to  be  employed  in  ventilating  the 
buildings. Fan outlet cowls and stacks should be rigidly constructed of timber or purpose-built 
prefabricated plastic or GRP. The use of unstiffened sheet metal, which can vibrate, should be 
avoided. 

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671 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

The characteristics of a building's structure affect the noise pattern. The build-up of noise in and 
around a building is determined by its absorption properties. Smooth reflective surfaces cause 
noise  levels  to  build  by  multiple  reflection.  By  contrast,  rough  surfaces,  such  as  straw  bales, 
absorb sound. 

The  application  of  high-efficiency  fans,  design  measures  to  reduce  airflow  resistance,  and 
operational  measures  (intermittent  operation)  can  all  reduce  energy  consumption.  However, 
low-level  wall-mounted  fans  are  considered  to  be  less  efficient  than  roof-mounted  fans  so 
additional  fan  capacity  would  be  required.  In  addition,  it  was  reported  that  low-level  wall-
mounted fans create more odour around the unit than roof-mounted fans. 

iii.  Operational measures 

For  the  minimum  required  ventilation  of  poultry  housing,  a  small  number  of  fans  operating 
continuously is less noticeable than a large number of fans operating intermittently to achieve 
the same ventilation rate. An increase of 3 dB(A) as a result of twice as many fans running will 
be highly significant with night-time background noise levels below 30 dB. 

Control of noise from discontinuous on-farm activities 
Many  on-farm  activities  are  carried  out  in  a  discontinuous  way.  Measures  to  reduce  noise 
emissions  from  these  activities  generally  relate  to  proper  timing  and  careful  location  of  the 
activity on the farm. The measures apply to the following activities: 

i.  Feed preparation 

On-farm  milling  and  mixing  of  feed  produce  noise  levels  of  63 dB(A).  Mills  are  often 
automated so that they can be used during the night to reduce operating costs by using lower 
cost  ‘off-peak’  night  rate  electricity.  If  complaints  are  likely  then  this  option  should  be 
reconsidered.  Mills  and  other  noisy  equipment  should  be  housed  within  an  acoustically 
insulated enclosure or building. Mills which use mechanical rather than pneumatic meal transfer 
systems are likely to be both quieter and substantially more energy-efficient. The main noise-
generating units, such as hammer mills and pneumatic conveyors, should be operated at times 
when background noise is known to be highest. 

ii.  Feed-conveying equipment 

Noise from pneumatic conveyors can be reduced by minimising the length of the delivery pipe. 
Low-capacity  systems,  which  operate  for longer, are likely  to  generate less  overall  noise  than 
large,  high-output  units.  Conveyors,  including  augers,  are  quietest  when  full  of  material. 
Conveyors or augers should not run empty. 

iii.  Feed delivery 

Many  units  do  not  prepare  feed  on  farm.  Feed  delivered  to  a  plant  is  usually  pneumatically 
conveyed into holding bins. Noise from feed delivery vehicles comes from: 

 

 

vehicles moving around the farm; 

pneumatic conveying equipment. 

The impact of these sources of noise can be minimised by: 

 

 

 

672 

locating feed bins or feed storage silos as far away as practical from residential and other 
sensitive properties; 

organising feed bin locations to reduce delivery vehicle movements on farm; 

avoiding long conveyor distances, and minimising the number of bends on fixed pipes, so 
that the maximum unloading rates can be achieved (to minimise noise duration). 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

iv.  Feeding operations in pig units 

Noise levels of 97 dB(A) and higher have been measured from excited stock in anticipation of 
feeding.  This  excitement  is  often  associated  with  manual  feeding  or  noisy  conveyor  systems 
delivering  feed  at  feeding  time.  These  peaks  of  animal  noise  can  be  reduced  by  the  use  of 
appropriate  mechanical  feeding  systems.  If  stocks  are  to  be  hand-fed  then  they  should  be  in 
small batches (separate from other batches) or, if noise is inevitable, stock should be fed at times 
of higher background noise levels. Feeders can be used that have holding hoppers, which can be 
filled  before  feeding  time  so  the  pigs  have  no  pre-feeding  stimulus  to  create  excitement  and 
noise. Passive ad libitum feeders can be used for some classes of stock and they greatly reduce 
stress and minimise noise. For new feeding equipment installations, this should be considered 
the preferred option. Compact feeders are also reported as fit for the purpose [ 624, IRPP TWG 
2013 ]. 

v.  Building openings 

Whenever  possible,  all  doors  and  other  major  openings  of  the  pig  buildings  should  be  closed 
during feeding time. 

vi. 

Fuel delivery 

Fuel  storage  tanks  should  be  located  as  far  away  as  possible  from  other  property  such  as 
residential  housing  as  far  as  this  is  convenient  and  practical.  Locating  fuel  storage  tanks  in  a 
position  where  the  livestock  buildings  lie  between  the  gas/oil  storage  and  other  property  can 
reduce sound propagation. 

vii.  Manure and slurry handling on pig farms 

Measures to reduce noise produced when pig manure is handled are listed below: 

 

 

 

Design  and  maintain  opening  gates  along  scraped  passages  in  manure  systems  with 
scrapers so that the pigs are unable to rattle gates and their fittings. 

Keep to a minimum scraped areas outdoors to reduce noise from scraper tractors. 

Locate  slurry  and  manure  storage  areas  away  from  nearby  dwellings.  Pressure  washers 
and  compressors  generate  considerable  noise  and  should  normally  be  used  inside 
buildings. Their use outside, e.g. to clean vehicles, should be avoided on sensitive sites. 
Wherever possible, machinery should be washed under cover and in locations away from 
residential housing and other sensitive properties. 

viii.  Manure and slurry handling on poultry farms 

Measures to reduce noise produced when poultry manure is handled are listed below: 

  When cleaning out poultry buildings, the movement and  manoeuvring of loaders filling 
trailers outside the building is organised to minimise the amount of machinery movement. 
If there is sufficient headroom, trailers are loaded inside the building. 

  Well-maintained exhaust systems and silencers of loaders and tractors. 

 

 

 

Teaching and training staff in the operation of loaders. 

Performing of manure and product handling at the ends of buildings furthest away from 
other property such as residential housing. 

In some egg production units, manure is conveyed directly to a separate storage building. 
This enables trailers to be loaded mainly within the building. 

Intensive Rearing of Poultry or Pigs 

673 

 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

 

Conveyors used for manure handling are a source of noise. They are located within the 
building structure as much as possible. Where they pass between buildings, the length of 
run  is  as  short  as  possible  and  the  provision  of  sound-absorbing  barriers  such  as  straw 
bales or more permanent panelling should be considered. Conveyors are not allowed to 
run empty. Use pressure washers and compressors inside buildings. Their use outside, to 
clean  vehicles,  is  avoided  on  sensitive  sites.  Wherever  possible,  machinery  is  washed 
under cover and in locations away from residential housing and other sensitive properties. 

ix.  Application of noise barriers 

Noise  propagation  can  be  reduced  by  inserting  obstacles  between  emitters  and  receivers. 
Appropriate obstacles may include protection walls, embankments and fences. Barriers are most 
effective against high-frequency noise. Long-wavelength, low-frequency noise will pass around 
or over the barriers.  

Earth banks can be used to combine the effect of barriers with the absorption of vegetation, and 
can be useful when constructed along the boundaries of pig units. Straw bales can be used to 
provide  a  tall,  effective,  temporary  noise  barrier  because  of  their  thickness  and  mass,  and 
because  of  their  absorbent  surfaces.  Straw  bales  should  not  be  used  in  or  near  pig  buildings 
where they may increase the risks of fire. Tall, solid, wooden fences reduce noise propagation. 
These can be sited on top of earth banks to increase the overall height of the obstacle.  

Woodland and hedges limit the diffusion of noise from pig farm buildings. A deep belt of tree 
planting  will  both  reduce  noise  and  mask  noise  generated  by  the  wind.  Noise  reduction  is 
relatively low at about 2 dB for 30 m of plantation. Hedges also reduce the diffusion of odours 
and facilitate the integration of farms in the landscape. 

Indicative effects of some applied measures are given in Table 4.217. 

Table 4.217:  Reducing effect of different noise measures 

Category 

Reduction measure 

Technical 

Design and construction 

Operational 

Natural ventilation 
High-efficiency fans 
Application of silencers 
Low-level side walls 
Hedge/vegetation barrier 
Small number of fans/continuous 
operation 

NB: NI = no information provided. 

Reduction effect 
(dB(A)) 
Variable 
NI 
NI 
NI 
2 

3 

Technical considerations relevant to applicability 
The  implementation  of  a  noise  management  plan  is  only  applicable  to  cases  where  an  odour 
nuisance  at  sensitive  receptors  is  expected  and/or  has  been  substantiated.  The  choice  of  fans 
(and  their  diameter)  is  primarily  based  on  the  needs  of  the  animals.  In  addition,  the 
implementation of multiple fans and the relocation of farm equipment (e.g. feed bins) in existing 
houses is reported to be difficult and costly.  Ad libitum  feeders are not applicable when some 
animals require restricted feeding for health and productivity reasons, e.g. sows and gilts. 

The noise-absorbent materials to be used have to be able to be cleaned easily, without having a 
negative effect on the hygiene of the herd [ 624, IRPP TWG 2013 ]. In the case of new farms, 
many of the siting measures can be applied as part of the farm planning. In that case, use should 
be made of any natural contours. For existing systems, the relocation of activities or equipment 
may  be  technically  possible  for  only  some  activities  due  to  restrictions  in  space  or  excessive 

674 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
costs,  but  relocation  of  large  constructions,  such  as  animal  housing,  may  be  constrained  as  it 
requires relatively high investments. 

Measures related to the operator’s practice and timing can be applied at any time, for both new 
and existing farms. Vegetation obstacles, such as hedges, may not be generally applicable due to 
biosecurity reasons. 

Chapter 4 

Economics  
No information provided. 

Driving force for implementation 
New pig and poultry developments should take account at the design stage of the noise control 
benefits of low-level and side-mounted fans and of acoustic barriers. The applicability of natural 
ventilation systems should also be considered. 

Example plants 
In  the  UK,  a  noise  management  plan  is  required  for  permit  holders  where  noise  has  been 
identified as an emission with a potential impact [ 624, IRPP TWG 2013 ]. 

Reference literature 
[ 40, NFU/NPA 2001 ] [ 43, COM 2003 ] [ 393, ADAS 1999 ] [ 559, ADAS 1999 ] [ 624, IRPP 
TWG 2013 ] 

Intensive Rearing of Poultry or Pigs 

675 

 
 
 
 
 
 
 
 
Chapter 4 

4.15  Techniques for the treatment and disposal of residues 

other than manure and dead animals  

4.15.1 

Solid residues 

Description 
Solid  residues  to  be  handled  on  a  farm  and  common  treatment  practices  are  listed  in 
Section 2.11. 

There are various ways to dispose of solid residues. The burning or landfilling of residues in the 
field is forbidden. For solid wastes to be incinerated, the incineration plant must hold a permit 
from  the  competent  authority  in  accordance  with  the  Industrial  Emissions  Directive 
(2010/75/EU),  Chapter  IV  and  Annex  VI,  where  technical  provisions  relating  to  waste 
incineration plants and waste co-incineration plants are given. Measures to prevent or to reduce 
as  far  as  possible  negative  effects  on  the  environment  (air,  soil  and  water)  caused  by  the 
incineration of waste are described in the WI BREF [ 705, COM 2017 ]. Waste incineration or 
co-incineration plants may be equipped with heat recovery systems. 

Achieved environmental benefits 
Achievable benefits are all related to the type of material and potential for saving energy. 

Cross-media effects 
None reported.  

Environmental performance and operational data 
The duty of care relates to everyone who handles waste, from the person producing the waste to 
the person who finally disposes of or recovers it. Waste must be kept secure so it does not leak, 
spill or blow away and can only be given to an authorised person (e.g. a registered waste carrier) 
and be transferred with the release of signed transfer notes [ 386, DEFRA 2009 ].  

Treatment of solid residues 
The  treatment  should  follow  the  waste  hierarchy  framework  (reduction,  reuse,  recovery, 
disposal)  and  apply  principles  of  proximity  (treatment  of  waste  as  close  as  possible)  and  of 
precaution  (immediate  application  of  cost-effective  measures  to  prevent  environmental 
degradation). Within this framework, the following on-farm options can be applied: 

 

 

 

reuse of residues; 

composting of residues; 

energy recovery. 

Reuse focuses on reusable or refillable packaging. Possibilities for the on-farm composting of 
residues other than manure appear very limited, with secondary cardboard packaging having the 
most opportunities. Energy recovery includes the already applied oil burners, but other materials 
may  be  applied  with  the  new  developing  energy  recovery  technologies.  Techniques  typically 
applied on intensive poultry and pig farms have not been reported. 

Treatment of hazardous waste 
Examples of farm wastes that are classified as hazardous include waste oil, asbestos, lead acid 
batteries  and  agro-chemicals  containing  dangerous  substances.  Hazardous  wastes  must  not  be 
mixed  with  them  or  with  non-hazardous  waste  or  other  substances  and  materials.  Hazardous 
wastes  must  be  collected  and  disposed  of  separately,  complying  with  local  rules  and  must  be 
transferred accompanied by 'consignment notes' [ 386, DEFRA 2009 ]. 

Technical considerations relevant to applicability 
No technical restrictions are reported for the implementation of the techniques. 

676 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Economics 
Some costs are associated with the treatment techniques applied. In particular, incineration and 
landfill  of  residues  will  have  to  observe  increasing  legislative  requirements  that  will  raise  the 
costs of applying and operating these techniques. 

Costs for other forms of disposal or recovery include: 

Chapter 4 

collection and transport costs; 

 
  disposal and recovery costs; 
 

landfill tax (if disposed of by landfill). 

Costs to the farmer will depend on a number of factors, including: 

farm location and distance to suitable facilities; 

 
  quantity of the residues; 
  nature and classification of the residues; 
 
  market demand for secondary materials. 

final treatment method; 

Driving force for implementation 
It  is  expected  that  agricultural  residues  will  increasingly  be  considered  as  industrial  waste. 
Requirements  laid  down  in  various  directives  concerning  waste,  such  as  the  EU  Landfill 
Directive  (1999/31/EC),  the  Industrial  Emissions  Directive  (2010/75/EU),  Chapter  IV  and 
Annex VI on waste incineration, and the Waste Framework Directive (2008/98/EC), are major 
forces to change the treatment of agricultural residues.  

Other forces that drive the change in the treatment of residues are considered to be the demands 
from  retailers  and  consumers,  growing  public  concern  about  the  environmental  and  human 
health impacts of products, increasing costs for disposal, and developing EU directives applying 
the ‘polluter pays’ principle. 

Example plants 
The measures described are commonly applied. 

Reference literature 
[ 43, COM 2003 ] [ 403, EA 2001 ] [ 386, DEFRA 2009 ] 

4.15.2 

Generation, segregation and treatment of liquid residues 

4.15.2.1 

Segregation, collection and prevention of waste water generation  

Description 
Waste  water  originating  from  livestock  facilities,  also  called  dirty  water,  is  comprised  of  the 
following: 

  Wash-down water from livestock farming facilities. Cleaning water can contain residues 
of dung and urine, litter and feedstuffs, as well as cleaning agents and disinfectants. 

 

 

Rejected water from air cleaning systems. 

Contaminated  rainwater  run-off  commonly  interfering  with  manure.  The  quantity 
depends  very  much  on  the  amount  of  rainfall  and  it  can  contain  some  or  all  of  the 
following in various amounts ranging from gross contamination to traces: faecal matter, 
feed, bedding, feathers, veterinary medicines, etc.  

Intensive Rearing of Poultry or Pigs 

677 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

It  is  in  the  best  interest  of  the  operator  to  effectively  separate  relatively  dirty  and 
uncontaminated  run-off.  The  contamination  of  rainwater  can  be  prevented  by  segregating  it 
from  waste  water  streams  that  require  treatment.  Poorly  designed  or  badly  maintained  drains 
and  gutters  can  allow  clean  rainwater  from  non-fouled  yards  and  roofs,  or  that  flowing  from 
higher grounds to the farmyard, to mix with dirty water and therefore increase the waste water 
volume.  

It is also good practice to keep yards, concrete surfaces and roofs as clean as possible, so that 
any rainfall coming into contact with these surfaces can be treated as 'lightly contaminated' or 
uncontaminated, depending on the local water protection regulations. Keeping the fouled yard 
area as small as possible minimises the volume of water required to wash it down and hence the 
volume of dirty water produced. Roofing such yards and covering storage heaps of solid manure 
would avoid additional inputs from rainwater.  

Avoiding  the  excessive  use  of  water  in  washing  down  fouled  yards,  buildings,  etc.  is  another 
way to minimise the volume of waste water generated. The mixing of waste water with slurry 
followed by further treatment and/or landspreading is common practice. The techniques for the 
processing and landspreading of slurry are described in Sections 4.12 and 4.13. 

When  waste  water  is  not  drained  to  the  slurry  store,  it  is  collected  and  settled  in  tanks  or 
lagoons. The solid fraction can be landspread. Subsequently, the liquid fraction has to be treated 
in  accordance  with  the  local  regulations  resulting  from  the  Water  Framework  Directive 
(2000/60/EC) and in relation to the level of contamination (see Section 4.15.2.2). Waste water 
may  also  be  landspread,  preceded  by  a  sedimentation  treatment,  with  a  low-rate  irrigation 
system (see Section 4.15.2.3). 

Uncontaminated precipitation water from roofs and roadways can, as a rule, be allowed to soak 
away locally or be discharged into drainage ditches or main outfalls. Any possibilities for reuse 
(such  as  cleaning  or  storing  in  reservoirs  for  firefighting)  involving  collection  and  separate 
storage could be considered if they do not pose a biosecurity risk.  

Precipitation water from uncovered exercise yards, outdoor feeding areas, and dung slabs should 
be collected and treated. When dimensioning the storage capacity for liquid manure and dung 
water,  the  volume  of  precipitation  water  to  be  taken  into  account  has  to  match  the  average 
precipitation volumes and the size of the areas involved, less any evaporative loss. 

Achieved environmental benefits 
The interception and treatment of waste water before it enters any watercourse or is landspread 
prevents water pollution. 

Cross-media effects 
Storing  of  separately  collected  uncontaminated  rainwater  over  a  longer  period  may  be 
problematic  due  to  biological  activity  in  the  stored  water  and  malodour.  It  may  also  involve 
risks to the health of livestock and farm staff. 

Technical considerations relevant to applicability 
The  construction  of  a  proper,  separate  collection  or  drainage  system  for  the  segregation  of 
uncontaminated water may not be applicable to existing farms due to high costs. The reuse of 
uncontaminated rainwater for cleaning is applicable to new farms and as part of major upgrades. 
In  some  areas  it  is  unnecessary  to  collect  such  water,  and  volumes  collected  may  exceed  the 
requirement. Collected water may also have to be stored inside heated buildings during winter. 
Collection  of  rainwater  for  cleaning  within  animal  housing  is  not  advised  due  to  biosecurity 
risks. Only in the case of an adequate pretreatment can the risk of contamination be completely 
excluded. 

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Economics 
The total annual costs (amortised over 20 years) for additional roofing over dirty concrete areas 
and the diversion of clean water are reported as EUR 1 820 for a pig farm and EUR 2 500 for a 
poultry farm (EUR 45/m2 of roof and EUR 1 = GBP 0.88) [ 648, DEFRA 2011 ]. 

Driving force for implementation 
Separate handling of dirty water from slurry offers more flexibility in slurry management, i.e. 
less  storage  volume  is  required,  and  less  needs  to  be  spread  by  slurry  application  techniques. 
Preventing unnecessary inputs of rainwater will be most beneficial in high rainfall areas. 

Example plants 
The  measures  described  are  commonly  applied.  A  survey  has  identified  a  few  management 
systems to collect rainwater for reuse for cleaning [ 264, Loyon et al. 2010 ]. 

Reference literature 
[ 264, Loyon et al. 2010 ] [ 403, EA 2001 ] [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ] [ 
648, DEFRA 2011 ] 

4.15.2.2 

Treatment of waste water 

Description  
For the treatment of waste water, relevant information on the applied techniques can be found in 
Section 3.3 of the CWW BREF [ 507, COM 2016 ]. 

The pollutant loads of waste water resulting from livestock f can vary considerably. The level of 
contamination  will  rank  run-off  from  clean  rainwater  as  it  depends  on  the  local  regulations. 
Authorisation permits may require operators to appropriately handle and treat contaminated run-
off water (e.g. see [ 524, UK EA 2012 ]).  

The treatment  of  lightly  contaminated  waters can  reduce  the  contaminant  load  or  potency,  by 
allowing pathogens to die off before they reach the natural surface or groundwater, by trapping 
sediments  containing  nutrients  and  heavy  metals,  and  by  plant  uptake  of  some  of  nutrients, 
thereby keeping them out of the natural ecosystem. Treatment methods that mimic some of the 
properties of natural wetland systems are simple and effective. 

The  process  chain  for  treating  lightly  contaminated  run-off  water  from  a  pig  or  poultry  unit 
comprises collection, treatment and final discharge. Either one or a combination of the methods 
described below can be tailored to meet the specific requirements associated with run-off types, 
loading, farm characteristics (slope gradient, expected rainfall volume, soil infiltration rate and 
space availability), and discharge standards.  

Swales are shallow grass-lined channels designed to collect run-off and move it gradually away 
downslope.  They  encourage  infiltration  along  their  route  as  the  grass  can  filter  off  suspended 
sediments, as well as take up nutrients. Commonly, check dams are built along the swale length 
to increase the storage capacity and to slow the water flow. 

Ponds  are  intended  to  allow  suspended  solids  to  settle  out  from  run-off  and/or  to  be  used  as 
buffers  for  storm  events  by  providing  temporary  storage  and  to  allow  biological  treatment. 
Ponds  can  help  remove  excessive  sediment  but  do  not  offer  the  full  treatment  potential  of  a 
constructed wetland, so they are often used as a pretreatment in constructed wetlands. They can 
also be used after a swale or another water collection system.  

Constructed wetlands are a constructed, semi-natural area of land typically comprising beds of 
specialised plant such as reeds (Phragmites spp) and gravel-filled channels. They mimic natural 
systems of ponds and marsh zones, where degrading depths appear in a sequence, giving room 
for  a  variety  of  habitats  and  vegetation  types.  They  have  potential  for  the  treatment  of  dilute 

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farm effluents (e.g. removal of BOD and plant nutrients, sediment entrapment). A constructed 
wetland can provide excellent treatment potential but requires dedicated space.  

Soakaways are used where soils are sufficiently permeable and the water table is low enough. 
Treated waters must have very low contaminant levels, since soakaways permit the seepage of 
run-off  through  the  surrounding  soil  above  the  water  table.  The  soil  provides  the  medium  in 
which bacterial treatment takes place, and cleaned water eventually reaches the water table. 

One method for separating highly contaminated from lightly contaminated fractions of run-off 
water before further treatment is by means of a dedicated first flush system (e.g. when leakages 
can  occur  from  silage  stores).  The  first,  highly  concentrated,  fraction  of  run-off  water  can  be 
characterised  by  high  organic  pollutant  loads  (e.g.  COD,  BOD  and  suspended  solids)  and 
usually by small volumes. Besides this fraction, a bigger volume of lightly contaminated silage 
run-off water can occur. The two fractions can be physically separated (using a combination of 
gravity, flow rate and inflow rate) by a dedicated first flush system.  

First flush systems consist of a brickwork pit, with a thin partition in the middle. The run-off 
water  enters  the  system  through  an  intake  system  with  a  bypass.  The  highly  contaminated 
fraction settles quickly, under gravity, in the first compartment, in combination with a limited 
flow  and  a  low  inflow  rate  (see  Figure 4.102).  From  there,  this  fraction  is  transported  to  a 
separate storage facility. The lightly contaminated fraction settles, under gravity, in the second 
compartment (goes further before settling down) in combination with a higher flow and a higher 
inflow  rate.  This  fraction  is  removed  by  a  second  outlet  from  the  second  compartment  to  a 
biological treatment, such as one of those described before. There is no movement of fractions 
between the two compartments. 

Source: [ 462, VITO 2005 ] 

Figure 4.102:Scheme of a first flush system 

Achieved environmental benefits  
These  systems  are  effective  at  improving  water  quality  by  combining  biological  and  physical 
treatment,  trapping  sediments  containing  nutrients  and  heavy  metals,  and  allowing  for 
controlled plant uptake of some of the nutrients. In this way, nutrients are not released into the 
soil, groundwater, and/or surface water through leaching. Moreover, treatment of contaminated 
rainwater run-off can reduce the contaminant load or potency by allowing pathogens to die off 
before they reach natural surface water or groundwater. 

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Cross-media effects  
Ponds need to be desludged from time to time. A constructed wetland can provide effluent that 
is suitable for use in crop and pastureland irrigation. 

Environmental performance and operational data  
A long swale (70 m or more in length) gives time for the entrapment or settlement of suspended 
solids. Optimal parameters are a 5 ° gradient, only gentle curves and not too steep sides (ratio 
1: 3). An established grass sward is beneficial to avoid standing water.  

The volume of the swale is calculated by multiplying the area to be drained by 12. This latter 
parameter represents the treatment volume and is the amount of rain (i.e. 12 mm) that generally 
lifts any light contamination from the surface, so that further rain after that is likely to run clean. 
An  increasing  number  of  check  dams  are  needed  on  the  path  for  increasing  slopes  (one  dam 
every 25 m for 2 ° of slope, 10 dams for 5 ° of slope). An example is given in Figure 4.103. 

Source: [ 362, UK 2010 ] 

Figure 4.103:Location of a system of swales and wetland for a poultry farm 

Ponds are relatively deep water bodies with shallow margins. Vegetation at the edges helps with 
sediment  capture,  habitat  creation,  and  safety.  Sediments  (e.g.  heavy  metals)  settle  at  the 
bottom.  

Constructed wetlands are intentionally flooded areas designed to simulate natural wetlands, with 
a combination of deep and shallow water. They can have a deeper channel winding from inlet to 
outlet, or a wetland that gradually gets deeper, with the shallow water areas planted with aquatic 
and/or  emergent  vegetation  (reedbeds).  The  deep  pond  always  appears  first  and  at  the  outlet 
marsh zone waters can be as shallow as 10 cm. 

There are two basic designs of constructed reed beds: vertical flow and horizontal flow, though 
both types can be combined. Vertical flow reed beds are designed to add oxygen to the effluent 
and remove any pollutants by allowing water to flow down through the reeds and gravel before 
being discharged. Any particles become attached to the gravel and plants as the water percolates 
down, which forms a slime. The slime then helps break down remaining pollutants as it contains 
microorganisms, which are supplied oxygen by the reeds. The microorganisms also help reduce 
NH3  levels.  Horizontal  flow  reedbeds  are  designed  to  allow  water  to  flow  laterally  through 
gravel and reeds and out the other side via overflow. This flooding effect creates an anaerobic 

Intensive Rearing of Poultry or Pigs 

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Chapter 4 

environment,  enabling  microorganisms  to  convert  nitrates  into  nitrogen  gas.  The  thriving  and 
very active population of microorganisms in this environment can help reduce pathogen levels 
[ 203, ADAS 2005 ]. 

A  nitrogen  removal  efficiency  of  20–60 %  is  reported,  which  can  reach  90 %  with  floating 
aquatic  macrophytes.  Denitrification  is  the  most  important  nitrogen  removal  pathway  while 
adsorption on solids is the main mechanism for phosphorus removal [ 594, Agro Business Park 
2011 ]. 

A  study  was  conducted  in  Lorca  (Murcia,  Spain)  by  GARSA  (Sustainable  Use,  Management 
and  Reclamation  of  Soil  and  Water  Research  Unit)  from  the  Universidad  Politécnica  de 
Cartagena  over  5  years  where  pig  slurry  was  treated  using  a  purification  system  based  on 
constructed  wetlands,  according  to  Figure  4.104.  The  purification  system  tested  in  this  study 
achieved  noticeable  decreases  in  pollutants  from  pig  slurry:  89 %  for  TSS,  90 %  for  BOD5, 
91 % for COD, 97 % for total phosphorus, 96 % for Cu, 92 % for Zn, 89 % for total nitrogen, 
87 % for NH4+-N, and 100 % for Salmonella, Shigella, and E. coli [ 672, Faz A. 2015 ]. 

NB:  (1)  Subterranean  tank,  (2)  fan  press  screw  separator,  (3)  storage  tank  with  an  intermittent  aeration  disc,  (4) 
sludge  thickener,  (5)  sedimentation  tank,  (6)  stopcocks,  (7)  intermittent  horizontal  subsurface  flow  constructed 
wetlands  by  batch  mode,  (8)  reservoir  tank,  and  (9)  storage  pond.  (A),  (B),  (C),  (D),  (E),  and  (F)  indicate  the 
sampling points. 
Source: [ 672, Faz A. 2015 ] 

Figure 4.104:Layout of a system for purifying slurry based on constructed wetlands 

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Constructed  wetlands  for  free-range  poultry  units  should  be  shallow  with  no  open  water  to 
attract wild birds, therefore reducing risks from avian influenza. An appropriate design might be 
a  small  four-cell  constructed  wetland  fully  planted  with  reeds.  Soakaways  only  need  to  be 
dimensioned  on  maximum  flows,  at  the  lower  level  of  the  system  and  with  the  highest 
infiltration rate. The choice of system should be based on a number of variables including slope 
gradient, expected rainfall volume, soil infiltration rate and space availability. 

Technical considerations relevant to applicability 
No  technical  restrictions  are  reported  for  the  implementation  of  the  technique.  The  treatment 
options  for  waste  water  depends  on  farm-specific factors.  Biosecurity  should  always  be  taken 
care of when waste water is stored separately before or after treatment. 

For  the  systems  treating  waste  water  with  a  low  pollutant  load,  land  availability  is  necessary. 
They should not be located close to natural sites of ecological importance, so as not to disturb 
the  existing  biodiversity.  These  ponds  are  designed  to  hold  water  and  are  not  normally  lined. 
They should lie on a watertight deep area, preferably with a clay content of at least 20 %. 

In general, these systems can withstand significant daily and seasonal fluctuations in load and 
this makes them  suitable for a wide variety of settings and weather patterns.  In cold climates, 
such as in northern Europe, the systems described may work for part of the year only, i.e. during 
the  growing  period.  For  this  reason,  a  parallel  treatment  system  (or  a  reservoir  to  collect  and 
store waste water during winter) is needed [ 500, IRPP TWG 2011 ]. These systems are used 
more  in  poultry  farms,  as  pig  farms  generally  have  the  possibility  to  manage  waste  water  in 
combination with slurry. 

Economics 
Costs vary significantly depending on farm-specific factors, but an indicative cost for a typical 
narrow  swale  is  in  the  region  of  EUR 6.00  per  metre.  Wetlands  constructed  on  suitable soil 
types will require excavation, fencing, gates, weirs, plants and professional fees for design. An 
indicative  cost  based  on  design  parameters  set  out  in  the  UK  sustainable  drainage  systems 
manual  (SUDS)  is  equivalent  to  EUR 0.9–1.1  per  m2  of  impermeable  area  drained,  the  cost 
possibly falling for larger wetlands. 

One example of  an  existing wetland system (Thornton Poultry Sheds, Glenrothes, Fife, in the 
UK)  was  designed  to  treat  and  attenuate  an  area  of  22 005  m2  and  cost  about  EUR 70 000  to 
construct. (exchange rate: 1 GB pound = 1.17 EUR, November 2011). 
The cost of a separation system can vary depending on the embodiment, dimensions, etc. The 
investment  costs  (excluding  VAT,  sumps  and  placement)  are  about  EUR 750;  the  total 
investment and installation costs are in the range of EUR 1 500–2 500. 

Driving force for implementation 
The systems provide a natural way to treat lightly contaminated run-off waters originating from 
a  wide  variety  of  sources and  with  varying  contamination  problems.  These  features  can  fit  in 
well  with  the  landscape  and  offer shelter to  wildlife. The  recovered  biomass can  have  a  wide 
range of applications (e.g. substrate for biogas or bioethanol production). They are cheaper to 
construct than piped systems and offer a low-maintenance option that is easy to control. 

Example plants 
These solutions are increasingly common for new poultry units in the UK.  

Constructed  or  natural  wetlands  are  widely  used  worldwide  to  treat  waste  water,  mainly 
receiving  dilute  effluents  with  a  typical  BOD5  of  100–250  mg/l.  The  BOD5  of  waste  water 
associated with livestock production can be considerably higher.  In some Member States (e.g. 
Austria), only rainwater is expected to be treated, as described in this section. 

Reference literature 
[  203,  ADAS  2005  ]  [  362,  UK  2010  ]  [  363,  EHS  2006  ]  [  462,  VITO  2005  ]  [  594,  Agro 
Business Park 2011 ] [ 672, Faz A. 2015 ] 

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4.15.2.3 

Landspreading of waste water by using an irrigation system  

Description 
Waste water encompasses all the water from a farm that contains residues from the cleaning of 
farm installations and farmyard run-off, and generally has a high BOD level (1 000–5 000 mg/l). 
Irrigation is applied as far as the available land is suitable. The same restrictions  as for slurry 
landspreading apply. 

This  technique  can  use  settlement  tanks  or  lagoons  to  collect  the  waste  water,  before  it  is 
pumped onto land. Particles can settle to prevent the system from clogging, or solids removal 
can be carried out in the machine itself. This fraction will have to be landspread. 

The waste water is pumped from the stores and brought into a pipeline that goes to a sprinkler or 
travelling irrigator for example, which sprays the water onto land. Irrigation can also be carried 
out  using  a  pulse-jet  irrigator  (see  Section  4.13.4.2.2),  a  tanker  or  an  umbilical  injector.  A 
schematic  representation  of  a  sprinkler  or  travelling  irrigation  system  for  dirty/waste  water  is 
shown in Figure 4.105. 

Source: [ 704, MAFF 1998 ]  

Figure 4.105:Example of a sprinkler or travelling irrigation system 

Achieved environmental benefits 
The  technique  is  considered  to  have  benefits  in  preventing  waste  water  entering  the  sewer 
system  or  being  discharged  into  nearby  surface  waters.  However,  irrigation  should  be  carried 
out within the capacity limits of the receiving soil and should follow the general rules of good 
landspreading management (see Section 4.13.3). 

Cross-media effects 
Energy  is  required  to  operate  the  system.  Sufficient  land  must  be  available  for  spreading. 
However,  it  may  reduce  the  amount  of  land  available  for  applying  slurry.  Odour  can  arise 
during spreading, and weather and soil conditions must be taken into account.  

Environmental performance and operational data 
Irrigation systems use suitable tanks or earth-banked stores to collect liquids and let them settle. 
They use an electric pump, small bore piping and sprinklers (up to 5 mm per hour) or a small 
travelling  irrigator  (up  to  50 m3/ha  or  5 mm  per  run)  to  spread  liquids  onto  the  land.  The 
required  storage  period  will  depend  on  the  risks  of  causing  pollution  from  run-off  when 
spreading the waste water. 

684 

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The system requires an emergency overflow to store water in excess of its capacity (in case of 
heavy rainfall). The pump must be designed for the required pressure, depending on the distance 
to the sprinkling system. The capacity is variable and adapted to the average volume expected. 

Technical considerations relevant to applicability 
Sufficient land adjacent to the farm is preferred, as it avoids the use of long pipelines covering 
large distances. The sprinkler system will have to be moved regularly to prevent contamination 
of  the  soil.  The  system  requires  regular  maintenance  to  avoid  clogging  of  the  pipes  and  to 
prevent  odour  from  residues  from  collecting  in  the  system.  Only  lightly  contaminated  waste 
water can be used for this system.  

Economics  
No information provided. 

Driving force for implementation  
Separate handling of waste water from slurry offers more flexibility in slurry management, i.e. 
less storage volume is required, and less needs to be spread by slurry application techniques.  

Example plants 
The technique is widely applied in the UK. 

Reference literature 
[ 242, CRPA 2009 ] [ 386, DEFRA 2009 ] [ 704, MAFF 1998 ] 

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4.16  Optimisation of the whole-farm environmental impact – 

Adoption of an integrated approach  

Description 
Ammonia emission reduction measures applied to a specific stage of the manure production and 
handling  have  an  influence  on  the  emissions  potential  of  the  next  stage,  due  to  the 
interdependency of the various phases of livestock manure management. In general, a reduction 
of ammonia emissions from the housing system results in a higher concentration of nitrogen in 
the stored manure. Meanwhile, a measure to reduce emissions from manure storage results in an 
increased  amount  of  available  nitrogen  for  landspreading,  with  a  consequent  higher  risk  of 
ammonia  emissions  during  landspreading  and  higher  potential  for  nitrate  leaching  to  water. 
Moreover, controlling emissions from manure landspreading is particularly important, because 
these are generally a large component of  the total emissions and because landspreading is the 
last stage of manure handling; without abatement at this stage, much of the benefit of abating 
during  housing  and  storage,  which  is  often  more  costly,  may  be  lost.  Likewise,  controlling 
emissions  from  landspreading  will  have  less  benefit  for  total  farm  losses  and  nitrogen  use 
efficiency  if  large  losses  occur  in  barns  and  storages.  On  the  basis  of  these  observations, 
strategies  for  ammonia  emissions reduction  which  retain  nitrogen  during  one  process step  are 
only beneficial if they do not subsequently exacerbate losses from the following step.  

Combinations of measures/techniques applied at the different production stages do not simply 
add  up  in  terms  of  the  overall  emission  reduction  efficiency;  in  addition,  the  abatement 
efficiency  of  a  technique  may  depend  on  the  measures/techniques  applied  in  the  previous 
production stages. Furthermore, techniques may have associated cross-media effects that result 
in significant indirect emissions related to the use of energy (fossil fuel, electricity), chemical 
products (fertilisers, additives) or materials whose extraction/production may cause damage to 
the environment.  

Therefore,  an  integrated  approach  for  a  whole-farm  emissions  reduction  should  be  promoted, 
based  on  a  manure  management  strategy  that  avoids  pollution  swapping.  In  other  words,  the 
reduction  efficiency  in  relation  to  the  whole  production  chain  (i.e.  application  of  combined 
techniques) has to be assessed in parallel when making a decision on a choice of a technique. 

Because  of  the  above  interrelation,  involved  parties  (i.e.  competent  authorities,  regulators, 
farmers,  researchers),  in  order  to  optimise  their  abatement  strategies  and  environmental 
outcomes  can  make  use  of  models  or  available  calculation  tools  with  an  integrated  approach 
where  the  overall  mass  flow  of  ammonia  nitrogen  is  assessed  in  relation  to  the  induced 
environmental cross-media effects. A whole-farm environmental and/or economic assessment of 
the combination of techniques may be determined by calculations based on available data (e.g. 
emission  factors,  reduction  rates,  consumption  of  energy  and  other  resources,  costs)  and 
estimations of cross-media effects. This approach allows distinguishing between techniques or 
combinations of techniques that lead to an overall environmental improvement and techniques 
which may result in a trade-off of pollutants. 

Achieved environmental benefits 
The  benefit is  an  overall  emissions reduction  from  the  whole farm  through  optimised  manure 
management and use of manure nutrients (particularly nitrogen). Pollution swapping from one 
production stage to another is avoided.  

Cross-media effects 
None reported.  

Environmental performance and operational data 
Tools have been developed for the environmental and economic assessment of the combination 
of techniques.  

686 

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Chapter 4 

Different combinations of techniques, applicable to the main stages of the rearing process, have 
been  assessed for  the  main  animal  categories (fattening  pigs,  laying  hens  and  broilers)  on  the 
basis  of  a  methodology  developed  by  Denmark.  The  assessment  has  been  carried  out  in 
comparison  with  reference  techniques  and  combinations  of  techniques  considered  to  be 
commonly  used  for  the  specific  animal  category  and  associated  with  a  basic  environmental 
performance. Some indicative examples of the selected combinations of techniques used for the 
assessment are indicated below. It should be noted that these combinations are not intended to 
define  BAT  for  the  specific  animal  category;  the  aim  is  to  present  examples  of  the 
environmental performance for the whole farm and, in general, to illustrate the usefulness of the 
approach. The specific assessment tool takes into account not only ammonia emissions but also 
nitrogen emissions to water and greenhouse gas emissions.  

The  environmental  assessment  is  also  combined  with  an  economic  analysis,  which  is  used  to 
assess economic constraints to the applicability of techniques and their possible combination, in 
particular with regards to the size of the farm. All assessments were based on information, i.e. 
ammonia  emission  reduction  efficiency  and  information  on  costs,  reported  in  the  previous 
sections.  

Some  indicative  examples  of  the  combinations  of  techniques  submitted  to  environmental  and 
economic assessment are presented in Table 4.218, Table 4.219, Table 4.220 and Table 4.221. 

Table 4.218:  Examples of assessed combinations of techniques for fattening pigs  

Nutrition 

Housing 
system 

Manure 
storage 

Landspreading 

Low-
protein 
feed 
[16 %] 

Phase 
feeding 
with 
addition 
of amino 
acids 
[19 %] 

Two-
phase 
feeding 
[8 %] 

Two-
phase 
feeding 
[8 %] 

FSF with 
vacuum 
system 
[10 %] 

FSF with 
vacuum 
system 
[10 %] 

FSF with 
vacuum 
system 
[10 %] + air 
cleaning 
system 
[90 %] 
FSF with 
vacuum 
system 
[10 %] + 
slurry 
acidification 
[75 %] 

Floating 
cover 
(natural 
crust) 
[28 %] 

Band spreader 
(trailing hose) 
[42 %] 

Tent cover 
[90 %] 

Open slot 
shallow 
injection 
[68 %] 

Floating 
cover 
(straw) 

Band spreader 
(trailing hose) 
[42 %] 

Slurry 
acidification 
+ storage 
without 
cover 
[75 %] 

Band spreader 
(trailing hose) 
[42 %] 

Total 
NH3 
reduction 
(%) 

Additional 
production costs 
(EUR/ap) (1) 
Animal places 

Cost efficiency 
(EUR/kg NH3) (1) 

Animal places 

2 000  4 000  8 000  2 000  4 000  8 000 

35.8 

0.5 

0.5 

0.5 

0.3 

0.3 

0.3 

55.0 

3.1 

3.1 

3.1 

1.3 

1.3 

1.3 

69.3 

15.9  15.3  15.1  5.1 

4.9 

4.9 

81.4 

10.3  7.1 

5.2 

2.8 

1.9 

1.4 

(1) The fertilising value of N is excluded from calculations. 
NB:  Baseline:  One-phase  feeding,  FSF  with  a  deep  pit,  uncovered  storage,  broadcast  spreading,  no  incorporation 
within 24 hours. The NH3 emission reduction achieved by each technique in comparison to the baseline that was 
used in the calculations is cited in brackets. For nutrition, the reduction efficiency is associated with N excretion. 

Source: [ 629, Denmark 2013 ] [ 661, Denmark 2013 ] 

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Table 4.219:  Examples of assessed combinations of techniques for broiler production  

Nutrition 

Housing 
system  

Manure 
storage 

Landspreading 

Phase 
feeding with 
amino acid 
[20 %] 

Phase 
feeding with 
amino acid  
[10 %] 

Deep litter 

Deep litter 
+ air 
cleaning 
(acid 
scrubber, 
100 % air 
cleaning) 
[70 %]  

Covered 
storage 
[28 %] 

Incorporation 
within 4 hours 
[81 %] 

Covered 
storage 
[28 %] 

Incorporation 
within 4 hours 
[81 %] 

Total 
NH3 
reduction  
(%) 

Additional 
production costs 
(EUR/ap) (1) 

Cost 
efficiency 
(EUR/kg NH3) 
(1) 

Bird places 

40 000  80 000  40 000  80 000 

44.9 

0.01 

0.01 

0.2 

0.2 

66.6 

1.47 

1.29 

14.4 

12.6 

(1) The fertilising value of N is excluded from calculations. 
NB: Baseline: Phase feeding, deep litter, uncovered storage, broadcast spreading, no incorporation within 24 hours. 
The NH3 emission reduction achieved by each technique in comparison to the baseline that was used in the 
calculations is cited in brackets. For nutrition, the reduction efficiency is associated with N excretion. 

Source: [ 629, Denmark 2013 ] [ 661, Denmark 2013 ] 

Table 4.220:  Examples of assessed combinations of techniques for laying hens in enriched cages  

Nutrition 

Housing 
system 

Manure 
storage 

Landspreading 

Additional 
production costs 
(EUR/ap) (1) 

Cost 
efficiency 
(EUR/kg 
NH3) (1) 

Bird places 

Total 
NH3 
reduction  
 (%) 

40 000  80 000  40 000  80 000 

Phase 
feeding with 
amino acid 
[10 %] 

Phase 
feeding with 
amino acid  
[10 %] 

Enriched 
cages, non-
ventilated 
belt, manure 
removal 2 
times a 
week 
[51 %] 
Enriched 
cages, 
ventilated 
belt with 
manure 
drying 
(weekly 
removal) 
[58 %] 

No 
storage 

Immediate 
incorporation 
[95 %] 

58.9 

0.1 

0.1 

1.0 

1.0 

Covered 
storage 
[25 %] 

Incorporation 
within 4 hours 
[81 %] 

56.4 

2.8 

2.8 

21.4 

21.4 

(1) The fertilising value of N is excluded from calculations. 
NB: Baseline: Phase feeding, non-ventilated belt, uncovered storage, broadcast spreading, no incorporation within 
24 hours. The NH3 emission reduction achieved by each technique in comparison to the baseline that was used 
in the calculations is cited in brackets. For nutrition, the reduction efficiency is associated with N excretion. 

Source: [ 629, Denmark 2013 ] [ 661, Denmark 2013 ] 

688 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Table 4.221:  Examples of assessed combinations of techniques for laying hens on litter  

Chapter 4 

Housing 
system 
(with or 
without 
end-of-
pipe 
technique) 
Aviaries, 
ventilated 
belt, 
removal 2 
times per 
week 
[72 %] 
Aviaries, 
ventilated 
belt, 
removal 2 
times per 
week 
[72 %] 
Deep litter, 
forced 
drying of 
manure in 
pit [88 %] 

Nutrition 

Phase feeding 
with amino 
acid [10 %] 

Phase feeding 
with amino 
acid [20 %] 

Phase feeding 
with amino 
acid [10 %] 

Manure 
storage 

Landspreading 

Total 
NH3 
reduction  
(%) 

Additional 
production 
costs 
(EUR/ap) (1) 

Cost efficiency 
(EUR/kg NH3) 
(1) 

Bird places 

40 000  80 000  80 000  40 000 

Covered 
storage 
[25 %] 

Immediate 
incorporation 
[95 %]  

69.8 

6.4 

6.4 

37.7 

37.7 

Covered 
storage 
[25 %] 

Immediate 
incorporation 
[95 %]  

Covered 
storage 
[25 %] 

Incorporation 
within 4 hours 
[81 %] 

73.2 

6.4 

6.4 

36.2 

36.2 

79.4 

2.3 

2.3 

12.4 

12.4 

(1) The fertilising value of N is excluded from calculations 
NB: Baseline: Phase feeding, deep litter, uncovered storage, broadcast spreading, no incorporation within 24 hours. 
The  NH3  emission  reduction  achieved  by  each  technique  in  comparison  to  the  baseline  that  was  used  in  the 
calculations is cited in brackets. For nutrition, the reduction efficiency is associated with N excretion. 

Source: [ 629, Denmark 2013 ] [ 661, Denmark 2013 ] 

Technical considerations relevant to applicability 
There are no restrictions to the applicability.  

Economics 
Estimated  costs  for  implementing  the  combinations  of  techniques  chosen  as  examples  of  the 
whole-farm approach are based on economic data provided for each technique and reported in 
the relevant sections of Chapter 4. In [ 661, Denmark 2013 ], the detailed cost data used for the 
assessment  are  presented,  together  with  general  economic  assumptions.  However,  the  results 
presented  in  the  tables  above  should  be  interpreted  with caution,  due to the limited  economic 
data reported [ 661, Denmark 2013 ]. 

The total costs have been calculated as increased production costs (EUR per animal place) and 
as costs of emission reduction (EUR per kg reduced NH3 emission). Cost estimations have been 
determined for different capacity farms, in particular for: 

 

 

 

 

sows: 750, 1 500 and 3 000 animal places; 

fattening pigs: 2 000, 4 000 and 8000 animal places; 

laying hens: 40 000 and 80 000 bird places; 

broilers: 40 000 and 80 000 bird places. 

Intensive Rearing of Poultry or Pigs 

689 

 
 
 
 
 
 
 
 
 
Chapter 4 

The comparison of cost estimates for various combinations of techniques, with different overall 
emission reduction performances, provides the following indications: 

 

 

 

combinations  of  techniques  that  include  end-of-pipe  measures  are  significantly  more 
expensive in terms of EUR/animal place; 

the economic impact on different size farms is evident in the pig sector, with higher costs 
for farms with a capacity between 750 and 1 500 places for sows and between 2 000 and 
4 000 places for fattening pigs;  

in  general,  higher  costs  are  associated  with  higher  ammonia  removal  efficiencies; 
however,  some  combinations  showing  comparable  environmental  performances  may  be 
associated with significantly different costs. 

The results of the economic assessment for combinations of techniques indicate the importance 
of  using  a  whole-farm  approach  in  order  to  determine  the  overall  environmental  efficiency 
generated from the combination of measures taken at all steps of the production process, from 
nutritional measures to manure management.  

Driving force for implementation 
Livestock  manure  is  a  valuable  source  of  nutrients  for  soil  and  crops.  The  efficient  use  of 
manure nutrients on agricultural land can substantially reduce the need for mineral fertiliser. An 
effective  use  of  manure  nutrients,  in  particular  nitrogen,  requires  consideration  of  the  whole 
manure management system.  

A  whole-system  approach  can  prevent  or  limit  the  environmental  consequences  further  up  or 
down the production chain and/or ensure adjoining systems are taken into account when making 
a decision on emission control techniques. Regulators are seeking to drive down emissions, and 
producers  are  trying  to  drive  down  costs  of  production,  whilst  improving  resource  efficiency 
and  produce a  product  for which there  is  a  market  demand  within the  financial constraints  of 
what the market will pay for that product. A whole-system approach enables the identification 
of  the  most  cost-efficient  techniques  or  combination  of  techniques  that  can  achieve  the  same 
level of environmental protection. 

Example plants 
Decision  support  tools  for  the  environmental  and  economic  assessment  of  techniques  or 
combinations of various techniques are available within the European Union.  

Reference literature 
[  204,  IMPEL  2009  ]  [  500,  IRPP  TWG  2011  ]  [  508,  TFRN  2014  ]  [  612,  TWG  comments 
2012 ] [ 629, Denmark 2013 ] [ 661, Denmark 2013 ]  

690 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 4 

4.17  Techniques for the reduction of dust emissions 

4.17.1 

Techniques to reduce dust generation inside livestock buildings 

Description 
Littering technique and litter management 
The  kind  and  quality  of  bedding  material  influence  the  emissions.  Finely  structured  material 
(e.g.  chopped  straw)  is  expected  to  emit  more  particles  than  coarse  material  (e.g.  long  straw, 
wood  shavings)  or  dedusted  bedding  materials.  In  addition,  the  frequency  of  littering  and  the 
quantity of bedding material influence the  emissions. The dust load in the animal house air is 
particularly high during the littering process. Littering techniques which release little dust (e.g. 
manual  littering,  no  distribution,  deposition  of  bales  in  the  pen,  by  rack)  are  more  favourable 
than techniques which emit large quantities of dust (e.g. the use of a bale dissolver with a throw 
blower, bale dropping from a platform).  

The dust content  of  the straw also  has an effect, as  does the way the initial crop is harvested, 
collected, sorted and distributed [ 624, IRPP TWG 2013 ]. 

Animal activity 
The  airflow,  density  and  activity  of  the  animals  in  the  animal  house  (whirling  up  of  dust 
particles  which  had  already  settled)  are  factors  that  influence  the  quantity  of  dust  emissions 
from  animal  houses.  Housing  techniques  which  offer  the  animals  only  little  freedom  of 
movement  (e.g. individual housing  of sows in crates) emit less dust than those which provide 
more freedom of movement (e.g. large group housing, aviary housing, floor husbandry, outdoor 
free range). 

Feeding regime (type of feedstuff and feeding practice) 
Feed  is  one  of  the  main  dust  sources  [  655,  Takai  et  al.  1998  ].  In  pig  housing,  the  dust 
concentration over the course of the day is determined by the feeding technique. During the day, 
during  feeding  or  when  the  animals  are  disturbed  (e.g.  during  inspection  rounds),  generally 
higher  concentrations  are  measured  than  at  night  and  in  resting  phases.  The  feeding  regime 
particularly  influences  animal  activity  and  emissions.  If  feed  is  dispensed  in  rations,  which 
means that feedstuff is offered at certain times of the day and is not constantly available to the 
animals,  the  concentration  values  during  feeding  time  are  significantly  higher  than  usual.  For 
this reason, ad libitum feeding is considered more favourable. 

It  is  reported  from  Germany  that  the  kind  of  feedstuff  used  and  the  way  it  is  dispensed  also 
influence the emissions. The formation of dust can be reduced by, for example: 

 

 

 

use of moist feed or pelleted dry feedstuff; 

use of floury feed mixtures in liquid feed dispensers; 

addition of oily raw materials or binders to dry feed. 

Feed  concentrate  should  be  stored  in  a  closed  system  (feed  concentrate  silo).  Dry  feed  stores 
which are filled pneumatically have to be equipped with dust separators.  

Ventilation design and operation  
Ventilation  air  dilutes  and  removes  indoor  airborne  contaminants  at  a  rate  dependent  on  the 
effective  rate  of  ventilation  and  outdoor  air pollutant  concentrations.  Designing  and  operating 
the ventilation system with a low air speed within the house is a way to reduce dust emissions 
from livestock buildings. 

A  high  ventilation  rate  is  not  always  desirable,  because  it  would  result  in  increased  heating 
costs, high air velocities and cold draughts. A short period of high ventilation (purge) reduces 
the dust  concentration,  but  the  dust  concentration increases  rapidly  after  the  purge.  By  timing 

Intensive Rearing of Poultry or Pigs 

691 

 
 
 
 
 
 
 
 
 
 
Chapter 4 

the purge, workers could be exposed to lower dust concentrations during tasks such as weighing 
and feeding pigs. 

Regular cleaning 
Generally, the equipment and all areas in the animal house should be as smooth and as easy to 
clean as possible. Dust deposits should be removed regularly (e.g. once a week), with a vacuum 
cleaner for example [ 655, Takai et al. 1997 ].  

In systems operating with the all-in all-out management principle, careful cleaning of the animal 
house  is  necessary  after  all  animals  leave  the  house.  During  the  cleaning  of  littered  poultry 
houses, manure should only be agitated (e.g. turned with the aid of a rotary cutter) rarely or not 
at all because this increases not only gaseous emissions, but also particle emissions. 

Achieved environmental benefits 
Emitted particulate matter such as PM10 and PM2,5 from livestock farms is reduced.  

Cross-media effects 
Regular  cleaning  is  labour-intensive  and  may  result  in  workers  being  exposed  to  greater  dust 
concentrations.  Lower  ventilation  rates  reduce  dust  emission  but  can  lead  to  increased  dust 
concentrations in the building with negative effects on animals' and workers' health [ 655, Takai 
et  al.  1998  ].  Other  limitations  associated  with  animal  welfare  may  also  exist,  especially  in 
summer.  

Environmental performance and operational data 
In  Table 4.222  and  Table 4.223,  emission  factors  associated  with  the  animal  category  and 
housing  system  are  reported  based  on  measurements  carried  out  for  the  national  dust 
measurement programme in the Netherlands [ 644, Netherlands 2014 ]. 

Table 4.222:  Emission  factors  for  dust  (PM10)  reported  for  various  pig  categories  and  types  of 

manure management  

Pig categories and manure management 

Weaners (slurry systems) 
Weaners (slurry systems) + air cleaning 
Farrowing sows (with piglets until weaning) (slurry 
systems) 
Farrowing sows (with piglets until weaning) + air 
cleaning system 
Mating - gestating sows (slurry system) 
Mating - gestating sows (slurry system) + air cleaning 
Sows including piglets up to 25 kg (slurry system) (1) 
Sows including piglets up to 25 kg (solid system) (1) 
Fattening pigs (slurry systems) 
Fattening pigs (solid systems) 
Fattening pigs (slurry systems) + air cleaning 
(1) All rearing stages. 
NB: NI = no information provided. 
Source: [ 644, Netherlands 2014 ] [ 474, VDI 2011 ]  

kg PM10/animal place/year 

NL 
0.056–0.074 
0.015–0.048 

0.16 

0.032–0.104 

0.175 
0.035–0.113 
NI 
NI 
0.153 
NI 
0.031–0.099 

DE 
0.08 
NI 

NI 

NI 

NI 
NI 
0.16 
0.8 
0.24 
0.32 
0.0096–0.072 

692 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 4.223:  Emission factors for dust (PM10) reported for various poultry categories and types of 

Chapter 4 

manure management 

Poultry categories and manure 
management 

Broilers 
Broilers + air cleaning 
Laying hens (deep litter)  
Laying hens (deep litter) + air cleaning 
Laying hens (aviary)  
Laying hens (enriched cages) 
Pullets (aviaries) 
Pullets (deep litter) 
NB: NI = no information provided. 
Source: [ 644, Netherlands 2014 ] [ 474, VDI 2011 ] [ 500, IRPP TWG 2011 ] 

NL 
0.017–0.022 
0.005–0.014 
0.084 
0.017–0.054 
0.065 
0.023 
0.023 
0.03 

kg PM10/animal place/year 
DE 
0.015–0.025 
NI 
0.12 
NI 
0.078 
0.006 
0.078 
0.059 

UK 
0.025 
NI 
0.02 
NI 
NI 
0.01 
NI 
NI 

A  reported  conversion factor  for  PM10 from  total  dust  in  pig  production is  40 %  and  between 
40–60 %  for  poultry  production  [  474,  VDI  2011  ].  A  research  programme  in  broiler  houses 
carried out in the Netherlands did not find any effect on PM10 emissions when different bedding 
materials  were  tested  (sawdust  versus  cut  straw)  or  with  different  lighting  schedules  (in 
compliance  with  welfare  regulations)  in  order  to  achieve  less  animal  activity  [  27,  UR 
Wageningen 2012 ]. Adding oily raw materials minimised feed dust and reduced (35–70 %) the 
dust concentration in some pig buildings [ 655, Takai et al. 1998 ]. 

Technical considerations relevant to applicability 
The  applicability  of  designing  and  operating  the  ventilation  system  with  low  ventilation  rates 
may be limited by animal welfare considerations. Long straw is not applicable in slurry-based 
systems. The rest of the techniques are generally applicable. 

Driving force for implementation 
Process-integrated measures for the reduction of dust emissions contribute to the prevention of 
epizootic  diseases  and  the  reduction  of  bioaerosol  emissions.  The  performance  and  operating 
duration of equipment in animal housing are improved (e.g. electronic devices, fan motors, heat 
exchangers). 

Reference literature 
[ 27, UR Wageningen 2012 ] [ 474, VDI 2011 ] [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 
2013 ] [ 644, Netherlands 2014 ] [ 655, Takai et al. 1998 ] 

4.17.2 

Techniques to reduce the dust concentration inside animal 
houses 

It  is  possible  to  simultaneously  reduce  dust  emissions  and  the  dust  concentration  in  animal 
housing  by  applying  technical  measures  within  the  house.  Ionisation,  oil  spraying  or  water 
fogging in the animal house are techniques to decrease dust dispersion by making dust particles 
adhesive  (see  Section  4.8.3). These techniques  reduce  personnel and animal exposure  to  dust, 
which is an important advantage in comparison with the use of air cleaning systems. 

4.17.3 

Air cleaning systems 

Treatment of exhaust air by air cleaning techniques  has been successfully employed in several 
countries. For instance, acid scrubbers and bioscrubbers can remove between 70 % and 95 % of 
NH3; both also remove fine dust and odour (see Section 4.9). To deal with the high dust loads, 
multi-stage  air  scrubbers  with  pre-filtering  of  coarse  particles  have  been  developed  
[ 508, TFRN 2014 ]. 

Intensive Rearing of Poultry or Pigs 

693 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

4.18  Monitoring 

Monitoring  is  an  important  aspect  for  all  livestock  farms,  in  order  to  assess  their  operational 
conditions  and  environmental  performance.  It  is  essential  to  understand  the  level  of  use  of 
inputs (i.e. feed, energy, water) and the generation of solid or liquid manure in order to consider 
whether and how changes may be made to improve profitability and to benefit the environment. 
Regular monitoring of water usage, energy usage (gas, electricity, fuel), livestock performance 
(especially amounts of feed and efficiency) and landspreading of mineral fertiliser and manure 
will form the basis for the review and evaluation. Where possible, the monitoring, review and 
evaluation by comparison should be related to groups of livestock, seasons, buildings or specific 
operations,  or  done  on  a  field-by-field  basis,  as  appropriate,  to  give  the  best  chance  of 
identifying  areas  for  improvement.  Also,  monitoring  should  help  in  identifying  abnormal 
situations and enable the appropriate actions to be taken. 

In general, a range of monitoring obligations is required on poultry and pig farms, which may 
include: 

 

 

 

 

 

 

 

recording of animal numbers; 

recording of inputs (e.g. feed, water, energy) 

manure management procedures; 

integrity of manure stores; 

emissions to air (e.g. ammonia, odour and dust); 

emissions to water (e.g. groundwater quality); 

keeping records of spreading activities (e.g. timing, amount, location, quality). 

An assessment of the environmental performance of techniques applied at the different stages of 
the manure management chain is based on the monitoring of emissions. The complex interaction 
between the production stages is generally monitored by determining the nitrogen flow through 
them:  starting  from  feed  selection  and  nutritional  management,  then  continuing  with  housing, 
and ending up with storage and manure application.  

4.18.1 

Excretion of nitrogen and phosphorus 

4.18.1.1 

Mass balance 

Description 
This technique consists of the calculation of the annual excretion of nitrogen (or phosphorus) by 
the animals (e.g. kg N/animal place/year), using a mass balance based on the feed intake, dietary 
content of crude protein (CP) and animal retention. The same procedure can be applied for the 
calculation of phosphorus excretion. 

Achieved environmental benefits 
Decreasing  nitrogen  and  phosphorus  excretion  is  considered  one  the  most  cost-effective  and 
strategic  ways  of  reducing  emissions  from  the  whole  farm.  Monitoring  of  excretion  helps  to 
identify  the  efficiency  of  the  nutritional  measures  carried  out  on  the  farm.  It  also  helps  to 
identify the effect of the housing conditions (e.g. temperature, ventilation, floor conditions) on 
the animal performance. 

Cross-media effects 
Some  equipment,  ancillary  materials  and  energy  can  be  required  for  carrying  out  monitoring 
(e.g. sampling of carcass). 

694 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
Environmental performance and operational data 
The mass balance is based on Equation 4.1: 

Equation 4.1:  Nexcreted= Ndiet – Nretention =

Chapter 4 

where: 
Nexcreted 
FINGi 

CPi 

Nretention 

Annual N excreted, in kg N/animal place/year. 
Annual  amount  of  feed  ingested  during  the 
feed/animal/year. 
Crude protein content of the i feeding phase, in %. Indicative contents are given 
in Table 4.13 and Table 4.14. FINTi and CPi can be calculated by: 
- accompanying documentation in the case of external feed supply; 
-  sampling  of  feedstuff  compounds  from  the  silos  or  the  feeding  system  for 

i  feeding  phase,  in  kg 

analysing the CP content, in the case of self-processing of feed. 

Annual N retention, in kg N/animal place/year. This can be estimated by one of 
the following methods: 
-  analysis  of  the  N  content  of  a  representative  sample  of  the  carcass  (or  the 

eggs, in the case of laying hens); 

- equations or models derived by statistics; 
- standard retention factors for the N content of the carcass (or of the eggs, in 

the case of laying hens). 

The values in Table 4.13 and Table 4.14 are indicative target levels of crude protein and may 
need to be adapted to local conditions. 

Technical considerations relevant to applicability 
This monitoring technique is applicable to all farms. 

Economics 
The  costs associated  with monitoring  of excretion relate to  personnel  and equipment  used  for 
sampling and documentation. 

Driving force for implementation 
Monitoring  of  the  nitrogen  excreted  is  linked  to  the  mass-balance  technique  for  monitoring 
ammonia  emissions  from  the  housing  system,  manure  storage  and/or  landspreading.  This 
technique  allows  information  to  be  collected  on  excretion  taking  into  account  the  specific 
characteristics of individual farms. 

Reference literature 
[ 43, COM 2003 ] 

4.18.1.2 

Manure analysis 

Description 
This technique consists of the calculation of the annual excretion of nitrogen (or phosphorus) by 
the  animals  (kg  N/animal  place/year),  using  an  analysis  of  the  nitrogen  content  of  a 
representative manure sample of the bulk of the material from which it is taken. 

The total nitrogen content of a representative composite sample of the manure is measured and 
the total nitrogen excreted is estimated on the basis of records for the volume (for slurry-based 
systems)  or  weight  (for  solid  manure  systems)  of  the  manure.  For  solid  manure  systems,  the 
nitrogen content of the litter should be considered. The same procedure can be applied for the 
calculation of phosphorus excretion.  

Intensive Rearing of Poultry or Pigs 

695 

 
 
 
 
 
 
 
 
 
 
 
 
 
  
Chapter 4 

Achieved environmental benefits 
Decreasing  nitrogen  and  phosphorus  excretion  is  considered  one  the  most  cost-effective  and 
strategic  ways  of  reducing  emissions  from  the  whole  farm.  Monitoring  of  excretion  helps  to 
identify  the  efficiency  of  the  nutritional  measures  carried  out  on  the  farm.  It  also  helps  to 
identify the effect of the housing conditions (e.g. temperature, ventilation, floor conditions) on 
the animal performance. 

Environmental performance and operational data 
In order for the composite sample to be representative, samples should be taken from at least 10 
different  places  and/or  depths to  make  the  composite  sample.  In  the  case  of  poultry  litter,  the 
bottom of the litter is sampled. If possible, the liquids should be agitated before collecting the 
sample. 

Technical considerations relevant to applicability 
This monitoring technique is applicable to all farms. 

Economics 
The  costs associated  with monitoring  of excretion relate to  personnel  and equipment  used  for 
sampling and documentation. 

Driving force for implementation 
Monitoring  of  the  nitrogen  excreted  is  linked  to  the  mass-balance  technique  for  monitoring 
ammonia  emissions  from  the  housing  system,  manure  storage  and/or  landspreading.  This 
technique  allows  information  to  be  collected  on  excretion  taking  into  account  the  specific 
characteristics of individual farms. The analysis of nutrients (nitrogen and phosphorus) allows 
the determination of the fertiliser value of the manure to be landspread. 

Reference literature 
[ 627, EEA 2013 ] 

4.18.2 

Ammonia emissions 

4.18.2.1 

Mass balance 

Description 
The estimation of ammonia emissions based on a nitrogen mass balance is the most commonly 
applied monitoring method. This technique consists of starting with the farm-specific amount of 
nitrogen excreted by a defined livestock category and using the total nitrogen (or the TAN) flow 
and the efficiency factors (EF) over each manure management stage, i.e. the proportion of the 
annual flow of total N or TAN that is emitted to air.  

Achieved environmental benefits 
Monitoring of ammonia helps to identify the efficiency of the measures carried out in relation to 
the housing system, storage and/or landspreading. 

Environmental performance and operational data 
The  ammonia  losses  between  the  moment  of  nitrogen  excretion  and  the  moment  of  removing 
the manure from the housing system and/or its landspreading are estimated. These losses depend 
on the housing system and manure storage techniques: 

Equation 4.2:  Nmanure = Ndiet – Nretention – Ngaseous losses from buildings and manure storage 

where: 

Amount of N contained in the diet consumed (kg N/animal/year) = 

Ndiet  
Nretention   Amount of N retained by the animal (live weight  N content) and related products 

(i.e. piglets for sows, eggs for laying hens)  

696 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
  
Equation 4.3:  Nexcreted= Ndiet – Nretention  

Chapter 4 

Nitrogen loss factors depend on the type of housing, animal and manure management, and, to 
some  extent,  on  climatic  conditions.  The  equations  to  be  applied  in  each  of  the  manure 
management stages are: 

Equation 4.4:  Ehousing = Nexcreted · VChousing 

Equation 4.5:  Estorage = Nstorage · VCstorage  

Equation 4.6:  Espreading = Nspreading · VCspreading 

where: 
Ehousing 
Estorage 

Espreading 

Nexcreted 
Nstorage 
Nspreading 

VChousing 

VCstorage 

VCspreading 

Annual NH3 emission from the animal house, e.g. in kg NH3/animal place/year.  
Annual NH3 emission from the manure storage system, e.g. in kg NH3/animal 
place/year. 
Annual  NH3  emission  from  manure  landspreading,  e.g.  in  kg  NH3/animal 
place/year. 
Annual total nitrogen or TAN excreted, e.g. in kg N/animal place/year. 
Annual total nitrogen or TAN stored, e.g. in kg N/animal place/year. 
Annual  total  nitrogen  or  TAN  applied  in  manure  landspreading,  e.g.  in  kg 
N/animal place/year. 
Volatilisation  coefficient 
(dimensionless), as a proportion of TAN or total nitrogen emitted to air.  
Volatilisation  coefficient 
techniques 
to 
(dimensionless),  as  a  proportion  of  TAN  or  total  nitrogen  emitted  to  air.  If 
appropriate,  N  additions  (e.g.  related  to  floor  bedding,  recycling  of  scrubbing 
liquids) and/or N losses (e.g. related to manure processing) can be considered. 
Volatilisation  coefficient  related  to  the  manure  landspreading  techniques 
(dimensionless), as a proportion of TAN or total nitrogen emitted to air. 

the  housing 

the  manure 

techniques 

storage 

system 

related 

related 

to 

In  order  to  have  reliable  monitoring,  volatilisation  coefficients  (VC)  are  recommended  to  be 
derived from measurements designed and performed according to a national or an international 
protocol  (e.g.  VERA  protocol)  and  validated  for  an  identical  type  of  technique  and  similar 
climatic  conditions.  Alternatively,  information  to  derive  VC  can  be  taken  from  European  or 
other internationally recognised guidance. 

Technical considerations relevant to applicability 
This  monitoring  technique  is  applicable  to  all  farms.  Data  concerning  the  protein  intake  of 
animals,  the  conversion  rate  and  the  growth  performance  are  well  known  and  are  commonly 
used to determine production costs. 

Economics 
The  costs associated  with monitoring  of excretion relate to  personnel  and equipment  used  for 
documentation. 

Driving force for implementation 
This technique allows information to be collected on ammonia emissions taking into account the 
specific characteristics of individual farms. 

Example plants 
Models  in  use  (e.g.  NEMA  in  NL)  in  different  MS  in  the  framework  of  the  national  NH3 
emission inventory apply a mass balance approach [ 628, Veltholf 2012 ]. Ammonia emission 
factors for different livestock categories and housing systems are generally available at Member 
State level. Loss factors for the type of housing and manure management have been developed 

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through several field studies carried out in different geographical areas throughout the European 
Union. 

Reference literature 
[ 628, Veltholf 2012 ] 

4.18.2.2 

Ammonia emission measurements 

Description 
A  protocol  has  been  developed  by  environmental  authorities  and  experts  from  Denmark, 
Germany and the Netherlands  outlining a measurement strategy and the conditions for testing 
ammonia emissions from livestock housing and management systems [ 445, VERA 2011 ]. The 
purpose  of  the  approach  presented  below,  based  on  the  VERA  protocol,  is  to  calculate  the 
annual  emissions  (emission  factors)  of  a  single  farm.  The  test  is  carried  out  over  a  one-year 
period  to  take  on  board  annual  variations  in  emission  levels  due  to  seasonal  and  production 
differences.  

Achieved environmental benefits 
Monitoring of ammonia helps to identify the efficiency of the measures carried out in relation to 
the housing system, storage and/or landspreading. 

Environmental performance and operational data 
Samples  from  the  farm  location  are  taken  on  at  least  6  days  distributed  over  1  year.  By  this 
procedure,  seasonal  variations  that  influence  NH3  concentrations  and  ventilation  rates 
throughout a year are equally distributed and well balanced in the sampling scheme.   

The distribution of the 6 sampling days within the year depends on the emissions pattern of the 
animal  category  to  be  considered.  For  animal  categories  with  a  stable emissions  pattern  (e.g. 
laying hens), the sampling days should be randomly selected in every two-month period.  

For  animal  categories  with  a  linear  increase  in  emissions  during  the  production  cycle  (e.g. 
fattening  pigs),  it  is  prescribed  as  an  additional  requirement  that  measurements  are  equally 
divided  over  the  growing  period.  In  order  to  achieve  this,  half  the  measurements  should  be 
performed in the first half of the production cycle, and the remainder in the second half of the 
production  cycle.  Furthermore,  the  sampling  days  in  the  second  half  of  the  production  cycle 
should be equally distributed within the year (same number of measurements per season). 

For  animal  categories  with  an  exponential  emissions  pattern  (e.g.  broilers),  the  following 
procedure should be applied to distribute the sampling days: 

 

 

The production cycle should be divided into three periods of equal length (same number 
of days). 

One  measurement  day  should  fall  in  the  first  period,  two  measurements  in  the  second 
period, and three measurements in the third period. In addition, sampling days in the third 
period of the production cycle should be equally distributed within the year (same number 
of measurements per season). 

In  cases  where  regular  management  practices  can  be  expected  to  affect  emission  levels,  care 
should be taken that these practices are incorporated in the sampling scheme in such a way that 
samplings are well distributed over these management practices. Sampling six times at one farm 
location is considered sufficient to deal with the on-farm location variance and at the same time 
ensures that observations are sufficiently spread in time to be independent from each other.  

All  measurements  will  be  based  on  24-hour  sampling  periods.  This  implies  that  diurnal 
variation patterns do not contribute to the overall measurement variation. For ammonia emission 

698 

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Chapter 4 

measurements to be representative of the emissions of the housing systems, normal management 
procedures and no exceptional situation within the animal house are necessary. When reporting 
ammonia  emission  results,  detailed  descriptions  of  the  housing  system  and  the  management 
system in place should be given.  

Many other parameters can be measured simultaneously that may influence the emissions. As 
indicative  examples  (apart  from  the  required  ventilation  rate),  they  can  be  the  indoor  and 
outdoor temperature, number and weight of animals in a housing unit, floor space per animal, 
air volume per animal, or feed composition parameters. 

The  daily  average  NH3  emission rate (g/h) is estimated  from  the  product of the  daily  average 
NH3  concentration  (g/m3)  measured  at  the  air  outlet/inlet  and  the  measured  daily  average 
ventilation  rate  (m3/h),  and  expressed  either  per  animal  or  per  livestock  unit  (500 kg  body 
weight). For the estimation of the ventilation rate, see Section 4.18.3. 

The  emission  rate  (E)  in  test  compartment  (i)  on  sampling  day  (j)  during  time  interval  (k)  is 
calculated from the ventilation rate (V) and the difference between concentrations at the outlet 
and inlet (C_out, C_in):  

Equation 4.7:  Eijk = Vijk × (C_outijk – C_inijk) 

For animal categories with a stable emissions pattern or with a linear increase in emissions, the 
daily average NH3 emission can be calculated from the average over all sampling days, and the 
standard deviation.  

For calculating the emission factor of animal categories with an exponential emission pattern, 
the production cycle must be divided into three periods of equal length (same number of days). 
Within each period, the average emissions are calculated from the available daily average values 
(periodic averages). The emission factors for each test compartment are then calculated as the 
average of the three periodic averages.  

Finally, the yearly average emission of the housing system can be calculated by multiplying by 
365  days  and  corrected  for  any  non-occupation  period.  It  can  be  expressed  in  the  following 
units:  kg  NH3/animal  place/year  or  kg  NH3/LU/year.  Ammonia  emissions  may  also  be 
expressed  relatively  as  a  fraction  of  the  total  nitrogen  or  total  ammoniacal  nitrogen  excreted. 
The  proposed  sampling  scheme  for  the  ammonia  measurement  protocol  is  summarised  in 
Table 4.224.  

Table 4.224:  Sampling  strategy  and  monitoring  conditions  for  testing  ammonia  emissions  in  a 

livestock housing system  

Parameter [Units] 

Sampling strategy 

• Ammonia 
• [mg·m-3] 
• Minimum number of sampling days: 6 measurement days in 1 year 
(distributed according to the emission pattern) 

Sampling conditions 

Monitoring method 

Source: [ 445, VERA 2011 ] 

• Cumulative sampling over 24 hours  
• Continuous measuring methods: based on hourly values (24 samples) 
• Sampling location: Air inlet and air outlet 
• Correction of background concentration is required (i.e. concentration of 
aerial pollutants in the incoming air) 
• Photo-acoustic monitor (NDIR)  
• FTIR spectrometer  
• NOX chemoluminescence monitor  
• Impinger system  
• Open-path Tuneable Diode Laser 

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Measurements  of  ammonia  emissions  require  the  employment  of  skilled  technical  operators, 
generally from independent and certified laboratories, able to perform the sampling and analysis 
of  ammonia,  together  with  the  measurement  of  other  additional  parameters  (i.e.  airflow, 
temperature,  humidity),  necessary  to  determine  the  concentration  of  the  pollutant,  and  to 
calculate the related emission factor.  

Technical considerations relevant to applicability 
This technique is only applicable to ammonia emissions from a housing system, in both natural 
and  forced  ventilated  houses.  The  monitoring  of  ammonia  emissions  from  manure  storage  or 
landspreading is described in Sections 4.18.1.1 and 4.18.2.3. 

Due  to  the  cost  of  measurements  and  technical  implementation  difficulties,  this  technique  is 
only  applicable  to  farms  located  close  to  sensitive  receptors  and/or  in  areas  with  a  high 
concentration of farms. 

Economics 
The  costs associated  with monitoring  of excretion relate to  personnel  and equipment  used  for 
sampling and documentation. 

Driving force for implementation 
This technique is linked to the mass-balance technique for monitoring ammonia emissions from 
the housing system, manure storage and/or landspreading.  

Reference literature 
[ 445, VERA 2011 ]  

4.18.2.3 

Emission factors 

Given the complexity and costs associated with NH3 measurements on livestock farms, the use 
of  emission  factors  is  a  possible  technique.  This  technique  is  mentioned  as  an  example  of 
quantification  of  diffuse  emissions  by  the  JRC  reference  report  on  Monitoring  of  IED-
installations [ 576, COM 2017 ]. In order to have reliable monitoring, emission factors should 
be  derived  from  measurements  designed  and  performed  according  to  a  national  or  an 
international  protocol  (e.g.  VERA  protocol)  for  an  identical  type  of  technique  (related  to  the 
housing  system,  manure  storage  and/or  landspreading)  and  similar  climatic  conditions.  This 
technique is also applicable to manure storage and landspreading. 

An  example  of  the  assignment  of  emission  factors  to  animal  housing  systems  exists  in  the 
Netherlands [ 153, Netherlands 2010 ]. 

4.18.3 

Ventilation rate 

Determination of the ventilation rate is a requirement for the measurement of diffuse emissions. 
The  assessment  of  airflow  rates  depends  on  the  type  of  ventilation  (forced  or  natural). 
Anemometers can be used in low-pressure, forced ventilated houses, to measure continuously in 
the ventilation shaft the airflow rate of extracted air. The specific ambient conditions inside an 
animal  house  (dust,  high  moisture,  ammonia)  can  increase  the  calibration  drift  of  the  sensors 
(e.g. sensitivity of hot wire anemometers to dust). The fan wheel anemometer requirements of 
fluid mechanics must be respected. In housing units with partial air cleaning, the ventilation rate 
is also measured for the whole housing [ 424, VERA 2010 ]. 

Methods  for  determining  ventilation  rates  may  differ  considerably  between  naturally  and 
mechanically  ventilated  buildings.  Normally,  errors  of  measured  ventilation  rates  tend  to  be 
higher in naturally ventilated buildings, which may lead to higher errors of measured emissions. 
In  mechanically  ventilated  buildings,  errors  associated  with  measuring  ventilation  rate  are 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

probably  the  most  relevant  error  source  of  emission  measurements.  The  main  differences 
between  emission  measurements  from  naturally  and  mechanically  ventilated  buildings  are  the 
magnitude of random errors and the significance of bias. In  mechanically ventilated buildings 
potential biases have been identified and can be avoided, whereas random error may be reduced 
to acceptable levels (i.e. 10–20%). However, in naturally ventilated buildings bias is difficult to 
identify  and  correct  and  random  error  is  likely  substantially  greater  than  in  mechanically 
ventilated buildings [ 33, Calvet et al. 2013 ]. 

In  naturally  ventilated  buildings,  ventilation  rates  cannot  be  measured  by  fans  and  must 
therefore be estimated using the tracer gas technique which is the only method for performing 
quantitative  measurements  of  ventilation  [  670,  Kiwan  et  al.  2012  ].  However,  this  approach 
cannot be applied when naturally ventilated buildings are too open to allow proper mixing of the 
tracer  gas.  The accuracy  of  this  method relies  on  the  perfect  mixing  of the tracer  gas  and  the 
homogeneity of concentrations and ventilation inside the barn. 

The  ventilation  rate  of  a  building  can  be  estimated  using  one  of  the  following  tracer  gas 
methods: (1) constant tracer gas injection; (2) variable tracer gas injection; and (3) concentration 
decay  [  630,  VDI  2011  ].  A  certain  amount  of  a  tracer  gas  is  released  in  the  room  (or  barn) 
under  study  and  its  concentration  is  then  recorded  as  a  function  of  time  and  space  by 
portable samplers or portable gas chromatographs which permit calculation of the air exchange 
rate.  Subsequently,  the  ventilation  rate  can  be  calculated  from  the  air  exchange  rate  and  the 
volume of the room (or barn). 

The use of sulphur hexafluoride (SF6) or any gas containing chlorofluorocarbons has a strong 
greenhouse  effect  potential  [  624,  IRPP  TWG  2013  ].  Ventilation  rates  can  also  be  predicted 
using  the  CO2  produced  by  the  animals  and  the  manure  or  the  associated  heat  production. 
Nevertheless,  most  heat  production  knowledge  concerns  animal  production  in  northern 
European countries. When the animal metabolism is different from those animals (growth rate, 
adult  weight,  heat  or  CO2  production  of  manure,  diurnal  variations  due  to  activity,  etc.),  the 
assumption relating to heat and CO2 production will induce a bias in the ventilation estimates.  

4.18.4 

Odour emissions 

Odour  concentration,  as  measured  by  olfactometry,  has  been  the  primary  method  to  quantify 
odours. Intensity, character and hedonic tone (offensiveness) are equally important criteria for 
public perception as well as the frequency and duration of the odour.  

The relationship between odour concentration and odour intensity is important  for establishing 
the effect of the odour on the public and in determining effective abatement strategies. Odours 
are controlled by reducing the amount of odorants in a given volume of air (concentration), but 
the  reduction  in  the  nuisance  quality  of  the  odour  is  related  to  the  strength  of  the  odour 
(intensity). There is a nonlinear relationship between odour concentration and odour intensity; 
the multiple compounds make it difficult to draw conclusions about the effect of the odour on 
the public. Because of the challenges and costs of sensory measurements, there have been some 
efforts to relate odour concentration to ammonia concentration or dust concentration but these 
have not been successful in all cases (e.g. for broilers) [ 438, Lacey et al. 2004 ].  

Odour  emissions  can  be  measured  by  dynamic  olfactometry  in  accordance  with  the  European 
CEN  standard  (EN  13725:2003)  in  a  sampling  time  of  usually  half  an  hour  (additionally,  the 
actual airflow is measured in the given time). The odour concentration cod is given in European 
odour units per cubic metre of air (ouE/m3). One odour unit (ouE) is defined as equivalent to the 
response  elicited  by  one  European  reference  odour  mass,  most  commonly  123 μg  n-butanol 
evaporated into 1 m3 of neutral gas [ 428, GEC 2008 ]. Spot measurement figures are given as 
ouE/m3  per  second.  Emission  factors  are  set  up for  the  animal  mass  that  may  be  reared  in  the 
shed (animal place or LU) or alternatively linked to the source area (ouE/m2 per s).  

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Other alternative techniques based on selected and trained panel members (e.g. measurement of 
odour  impact  by  determining  odour  intensity  and  hedonic  tone  in  the  field)  or  odour  surveys 
(e.g.  measurement/estimation  of  annoyance  caused  by  odour  exposure  in  the  survey  area, 
complaints  registers)  are  also  applied.  A  number  of  these  methods  are  standardised  at  the 
national level (e.g. VDI 394 Part 3: 2010 on monitoring with panels) (see also the ROM REF 
[ 576,  COM  2017  ]).  Odour  intensity  observations by  workers  in an  odorous  environment  are 
unreliable due to sensory adaptation [ 624, IRPP TWG 2013 ].  

Two new EN standards are under development by the Technical Committee CEN/TC 264/WG 
27 for the determination of odour exposure in ambient air using selected and trained panels in 
the field [ 576, COM 2017 ]. In German regulations, odour impacts are assessed as significant 
and legally not allowed, in order to avoid annoyances in the vicinity of farms, if a frequency of 
odour perception of 10 % (general residential areas) or 15 % (village areas) of the yearly hours 
for an odour concentration of 1 ouE /m3 is exceeded [ 590, Batfarm 2013 ]. 

4.18.5 

Dust emissions 

As for ammonia emissions, dust emissions can be measured or estimated using emission factors. 
Measurements  of  dust  emissions  are  also  covered  by  the VERA  protocol,  and the  operational 
procedure  is  very  similar  to  the  one  used  for  ammonia  emissions  (see  Section 4.18.2.2).  The 
main differences are related to the measuring methods, which are summarised in Table 4.225. 

Table 4.225:  Sampling strategy and  monitoring conditions for testing dust emissions in a livestock 

housing system 

Parameter [Units] 

Sampling strategy 

• Total dust, PM10, PM2.5  
• [mg·m-3] 
• Minimum number and distribution of sampling days: 

6 measurement days in 1 year 

• Cumulative sampling over 24 hours  
• Continuous measuring methods: based on hourly values (24 

Sampling conditions 

samples) 

• Sampling time: 24 hours for PM10 and PM2.5 
• Sampling location: Air inlet and air outlet. 
Gravimetric: 
EN 13284-1:2001  
EN 13284-2:2004  
EN 15259:2007 
EN 14907:2005 
EN 12341 

Measuring method 

Source: [ 445, VERA 2011 ] 

4.18.6 

Air cleaning systems 

Protocols  have  been  developed  (e.g.  VERA  protocol)  in  order  to  specify  the  procedure  for 
testing  the  efficiency  of  air  cleaning  systems  in  animal  housing,  including  definitions, 
requirements  and  conditions  for  parties  involved  in  the  testing,  measurement  and  sampling 
methods, processing and interpretation of measurement results, and reporting.  

Measurement  of  emissions  from  air  cleaning  system  can  be  waived  by  verifying  and 
continuously  ensuring  the  efficiency  of  the  emission  control  system.  This  can  be  done  by  an 
acceptance inspection (verification) and continuously monitoring process parameters.  

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Chapter 4 

4.18.6.1 

Verification of air cleaning systems 

After a period of at least 4 months from the start of operation of the air cleaning system but no 
more than 18 months, an acceptance inspection with measurement of ammonia, odour and dust 
in the raw and the clean gas and an evaluation of all additional parameters relevant for operation 
(e.g. airflow rate, pressure drop, temperature) has to be carried out by an independent body (e.g. 
certified laboratory). 

Inspection testing has to be performed under summer conditions (a period of at least  8 weeks 
with  a  ventilation rate  above  80 %  of the  maximum  ventilation  rate)  and  winter  conditions  (a 
period of at least 8 weeks with a ventilation rate below 30 % of the maximum ventilation rate), 
representative management and with the housing at full capacity and if a representative period 
of time (e.g. 4 weeks) has elapsed since the last change of wash water. Inspection testing also 
includes an analysis of the wash water used during the period of measurement. 

The following sampling strategy is based on the VERA protocol: 

 

 

 

 

Ammonia:  24-hour  continuous  sampling  once  a  week  during  each  of  the  2  eight-week 
periods. 

Odour: weekly during each of the 2 eight-week periods, two samples per day, minimum 
sampling  period  30  minutes  (one  sample  per  day  is  enough  if  the  sampling  time  is 
120 minutes).  

Dust: Total dust: one 24-hour sample in each of the eight-week periods. Measurements of 
PM10 and PM2.5 are optional. 

Recirculated  liquid  of  the  air  cleaning  system:  on  all  days,  with  odour  and  ammonia 
measurements analysed for pH, conductivity, NH4

- and NO3

+, NO2

-. 

Establishing a N-balance, when relevant, in order to document possible secondary trace  gases 
formation  and secure long-term  operational  stability  of  the  air  cleaner, requires a  period  of  at 
least 2 weeks within the eight-week periods with online gas (NH3, NOX, N2O) and volumetric 
flow measurements (gas and liquid) and water analyses (fresh and blowdown water). 

After  the  acceptance  inspection,  regular  check-ups  of  the  air  cleaning  system  have  to  be 
conducted every year by a certified laboratory on an unannounced farm visit. These check-ups 
include  inspection  of  the  technical  condition  and  function  of  the  air  cleaning  system,  odour 
measurement  of  the  inlet  and  outlet air,  ammonia  measurement  and  a review of  all  additional 
parameters relevant for operation (e.g. condition and cleanliness of the filter material). Periodic 
(at least yearly) maintenance also has to be performed by the supplier or a qualified contractor. 
Protocols  of  the  maintenance  can  be  provided  to  the  competent  authority.  The  ammonia 
emission rate (kg NH3/animal place/year) for a scrubber system is calculated by multiplication 
of an assigned reduction percentage (assigned as above) with the ammonia emission rate for a 
conventional housing system without a scrubber. 

The verification review of the air cleaning system is considered unnecessary in the Netherlands 
when  the  design  of  the  system  is  similar  to  already  existing  systems  or  when  the  targeted 
efficiency of the system is not greater than 70 % [ 153, Netherlands 2010 ]. 

4.18.6.2 

Monitoring of process parameters of air cleaning systems 

Description 
In principle, an electronic logbook has to be installed and operated in order to record relevant 
information  (measurement  and  environmental  performance  and  operational  data)  in  order  to 
evaluate  operational  stability  and  document  the  proper  operation  of  the  exhaust  air  cleaning 
system.  Continuous  logging  of  key  parameters  can  take  place  over  a  period  of  up  to  5  years. 

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Among the parameters that may be recorded are: pressure drop, ventilation rate, pump running 
times,  pH  level,  conductivity,  water  and  acid  consumption,  acid  and  alkali  consumption, 
conductivity.  Parameters  to  be  recorded  depend  on  the  type  of  air  cleaning  system  and  the 
requirements of the permit. It is advisable to use half-hourly averages for the first  7 days and 
daily average values after that [ 624, IRPP TWG 2013 ]. 

Additional general information is recorded manually such as number and type of animals kept, 
average  live  weight, special  incidents  (e.g.  failure  of pumps,  measuring  devices),  invoices  for 
chemicals,  condition  of  filter  material  and  spray  pattern  of  nozzles,  regular  checks  of  the 
installation. Monitoring of the operating parameters is necessary, both for proper operation and 
for regulatory control. Some of the parameters listed in Table 4.226 may be stored in electronic 
operation logs, depending on the equipment used. 

Table 4.226:  Parameters to be recorded in the operations logbook 

Parameter 

Biofilter 

Pressure loss in the exhaust air treatment system 
Airflow rate 
Pump running times (separate for the circulation 
pumps and the elutriation pumps) 
Sprinkling intervals 
Total water consumption of the exhaust air 
treatment system 
Proof of acid consumption (with receipts) 
Elutriated water quantity and its discharge 
pH regulation  
Water pressure 
Raw gas temperature 
Clean gas temperature 
Calibration of the pH sensor 
System control – sprinkling pattern 
Maintenance and repair times (including the kind of 
work) 
Change of filter material 
NB: x = electronic recording; m = manual recording.  

Source: [ 514, KTBL 2008 ] 

x 
x 

x 

x 

x 
x 

m 

m 

m 

Trickle bed 
reactor 
(bioscrubber) 
x 
x 

Acid scrubbers 
and multi-stage 
scrubbers 
x 
x 

x 

x 

x 

m 
x 
x 
x 
x 
x 
m 
m 

m 

x 

x 

x 

m 
m 
x 
x 
x 
x 
m 
m 

m 

Continuous  monitoring  of  electrical  conductivity,  pH,  discharge  volume,  electricity 
consumption  and  pressure  drop  are  considered  to  allow  a  sufficient  estimation  of  the  system 
functionality. 

In  the  event  that  there  is  no  electronic  monitoring  of  process  parameters,  the  operational 
stability of the system can also be verified by  visits with an overall check-up and checking of 
the logbook and testing of discharge water and NH3 measurement [ 424, VERA 2010 ].  

Some key parameters for the evaluation are given below: 

 

 

 

 

 

704 

Residence  time  at  maximum  airflow  (i.e.  the  airflow  at  a  high  animal  weight  on  hot 
summer days). 

Amount of water that is sprinkled over the packing sufficient for its complete wetting. 

In bioscrubbers, sufficient amount of water discharge in order to prevent inhibition of the 
bacteria. 

In  acid  scrubbers,  sufficient  amount  of  water  discharge  and  pH  in  order  to  prevent 
precipitation of ammonium salts.  

Comparison with existing scrubber designs that have been tested in the field and/or have 
been evaluated before. 

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Economics 
The costs of measurements of emissions to air are generally considered high and therefore not 
viable  for  the  majority  of  farms.  For  this  reason,  the  control  of  surrogate  parameters  is 
commonly used as an alternative to emission measurement. 

Driving force for implementation 
Continuous monitoring of pressure drops over the air cleaning systems, combined with alerts, 
provides farmers with a timely indication of when to clean packing material, thus saving energy 
and  costs.  In  the  case  of  other  than  normal  operating  conditions,  the  proper  operation  of  the 
system can be documented.  

Example plants 
Monitoring of the proper operation of several hundred air cleaning systems has been carried out 
in Germany in recent years. 

Reference literature 
[ 153, Netherlands 2010 ] [ 424, VERA 2010 ] [ 514, KTBL 2008 ] [ 624, IRPP TWG 2013 ]  

4.18.7 

Emissions to water  

Water  contamination  from  livestock  farms  may  arise  from  leakage  of  manure  stores,  poor 
management  of  run-off  waters  and  inappropriate  management  of  manure  landspreading. 
Monitoring of local groundwater can be a means to detect leakages rapidly, in particular where 
earth-banked 
lagoons  without  a  double  geomembrane  are  used  for  slurry  storage  
[ 204, IMPEL 2009 ]. The typical parameters to be measured are the following: 

 

 

 

nutrients: nitrogen compounds and phosphorus;  

pathogens, such as coliforms, E. coli; 

metals, such as Zn, Cu.  

However,  a  straightforward  correlation  of  a  specific  farm  with  groundwater  quality  cannot 
- in the groundwater can be a 
always be established, as the increase of pollutants such as NO3
slow procedure and because of the diffuse character of water pollution from agricultural sources  
[ 624, IRPP TWG 2013 ]. The impact depends on many factors such as the geology of the area. 
Groundwater mapping and protection schemes are usually implemented at national or regional 
level due to the high costs. 

4.18.8 

Process parameters 

Water consumption 
Suitable meters or invoices can be used for recording the water consumption. The main water-
consuming  processes  in  animal  houses  (cleaning,  feeding,  etc.)  can  be  monitored  separately 
depending on the configuration of the water supply network.  

Electric energy consumption 
Suitable meters  or  invoices  can  be  used  for  recording  the  electric  energy  consumption.  The 
electricity consumption of animal houses is monitored separately from other plants in the farm. 
The main energy-consuming processes in animal houses (heating, ventilation, lighting, etc.) can 
be monitored separately depending on the configuration of the energy supply network. 

Fuel consumption 
Suitable meters or invoices can be used for recording the fuel consumption. 

Intensive Rearing of Poultry or Pigs 

705 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 4 

Animal register and feed consumption 
The number of incoming and outgoing animals, including births and deaths when relevant, can 
be  recorded  using  invoices  or  existing  registers.  Feed  consumption  can  be  recorded  using 
invoices or existing registers for example. 

Manure generation 
Manure generation can be recorded using existing registers for example. 

706 

Intensive Rearing of Poultry or Pigs 

Chapter 5 

5  BAT CONCLUSIONS 

SCOPE 

These BAT conclusions concern the following activities specified in Section 6.6 of Annex I to 
Directive 2010/75/EU, namely '6.6. Intensive rearing of poultry or pigs':  

(a)  with more than 40 000 places for poultry 

(b)  with more than 2 000 places for production pigs (over 30 kg), or 

(c)  with more than 750 places for sows. 

In particular, these BAT conclusions cover the following on-farm processes and activities: 















nutritional management of poultry and pigs;

feed preparation (milling, mixing and storage);

rearing (housing) of poultry and pigs;

collection and storage of manure;

processing of manure;

manure landspreading;

storage of dead animals.

These BAT conclusions do not address the following processes or activities: 



disposal  of  dead  animals;  this  may  be  covered  in  the  BAT  conclusions  on
Slaughterhouses and Animal By-products Industries (SA).

Other  BAT  conclusions  and  reference  documents  which  are  of  relevance  for  the  activities 
covered by these BAT conclusions are the following: 

Reference documents 

Waste Incineration (WI) 
Waste Treatment Industries (WT) 
Monitoring of emissions from IED-installations 
(ROM) 
Economics and Cross-media Effects (ECM) 
Emissions from Storage (EFS) 
Energy Efficiency (ENE) 
Food, Drink and Milk Industries (FDM) 

Activity 

Incineration of manure 
Composting and anaerobic digestion of manure 

Monitoring of emissions to air and water 

Economics and cross-media effects of techniques 
Storage and handling of materials 
General aspects of energy efficiency 
Feed production 

Where  these  BAT  conclusions  address  manure  storage  and  landspreading,  this  is  without 
prejudice to the provisions of Council Directive 91/676/EEC (1). 

Where  these  BAT  conclusions  address  the  storage  and  disposal  of  dead  animals  and  manure 
processing and landspreading this is without prejudice to the provisions of Regulation (EC) No 
1069/2009 of the European Parliament and of the Council (2). 

These  BAT  conclusions  apply  without  prejudice  to  other  relevant  legislation,  e.g.  on  animal 
welfare. 
_____________________ 
(1)  Council  Directive  91/676/EEC  of  12  December  1991  concerning  the  protection  of  waters  against pollution  caused by  nitrates 
from agricultural sources (OJ L 375/1, 31.12.1991, p.1) 
(2) Regulation (EC) No 1069/2009 of the European Parliament and of the Council of 21 October 2009 laying down health rules as 
regards animal by-products and derived products not intended for human consumption and repealing Regulation (EC) No 1774/2002 
(Animal by-products Regulation) (OJ L 300/1, 14.11.2009, p.1) 

Intensive Rearing of Poultry or Pigs 

707 

Chapter 5 

DEFINITIONS 

For the purposes of these BAT conclusions, the following definitions apply. 

Term used 

Ad libitum 

Animal place 

Conservation tillage 

Existing farm 

Existing plant 

Farm 

Manure 

New farm 

New plant  

Plant 

Sensitive receptor  

Slurry 

Solid manure 

Total ammoniacal nitrogen 

Total nitrogen 

Total nitrogen excreted 

Total phosphorus 

Total phosphorus excreted 

Waste water 

Definition 
The  provision  of  free  access  to  feed  or  water  thereby  allowing  the 
animal to self-regulate intake according to its biological needs. 
Space provided per animal in a housing system taking into account the 
maximum capacity of the plant.  
Any  method  of  soil  cultivation  that  leaves  the  previous  year's  crop 
residue (such as corn stalks or wheat stubble) on fields before and after 
planting the next crop, to reduce soil erosion and run-off. 
A farm which is not a new farm. 

the  publication  of 

A plant which is not a new plant. 
An  installation  as  defined  in  Article  3(3)  of  Directive  2010/75/EU 
where pigs or poultry are reared. 
Slurry and/or solid manure. 
A  farm  first  permitted  following  the  publication  of  these  BAT 
conclusions  or  a  complete  replacement  of  a  farm  following  the 
publication of these BAT conclusions. 
A plant first permitted at the site of the farm following the publication 
of these BAT conclusions or a complete replacement of a plant on the 
existing  foundations,  following 
these  BAT 
conclusions. 
A part of the farm where one of the following processes or activities is 
carried  out:  animal  housing,  manure  storage,  manure  processing.  A 
plant  consists  of  a  single  building  (or  facility)  and/or  the  necessary 
equipment to carry out processes or activities. 
Area which need special protection from nuisance, such as: 
- Residential areas. 
- Areas where human activities are carried out (e.g. schools, day care 
centres, recreational areas, hospitals or nursing homes). 
- Sensitive ecosystems/habitats. 
Faeces and urine mixed or not with some litter material and some water 
to give a liquid manure with a dry matter content up to about 10 % that 
flows under gravity and can be pumped. 
Faeces or droppings and urine mixed or not with litter material that do 
not flow under gravity and cannot be pumped. 
Ammonium-N (NH4-N) and its compounds, including uric acid, which 
are readily broken down to NH4-N. 
Total nitrogen, expressed as N, includes free ammonia and ammonium 
(NH4-N),  nitrites  (NO2-N),  nitrates  (NO3-N)  and  organic  nitrogen 
compounds. 
Total  nitrogen  eliminated  from  animal  metabolic  processes  through 
urine and faeces. 
Total  phosphorus,  expressed  as  P2O5,  includes  all  inorganic  and 
organic phosphorus compounds, dissolved or bound to particles. 
Total phosphorus eliminated from animal metabolic processes through 
urine and faeces. 
Rainwater run-off commonly  mixed  with  manure,  water derived from 
the cleaning of surfaces (e.g. floors) and equipment, and water derived 
from the operation of air cleaning systems. This may also be referred to 
as soiled water.  

708 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
Definitions for certain animal categories 

Term used 

Definition 

Chapter 5 

Breeders 
Broilers  
Broiler breeders 
Farrowing sows 

Fattening pigs  

Gestating sows 
Laying hens 
Mating sows 

Pig 

Piglets 

Poultry 

Pullets 

Sows  

Weaners 

Parent stock (males and females) kept to lay eggs for hatching. 
Chickens reared for meat production. 
Parent stock (males and females) kept to lay eggs for broilers production. 
Sows between the perinatal period and the weaning of the piglets. 
Production pigs typically reared from a live weight of 30 kg to slaughter 
or  first  service.  This  category  includes  growers,  finishers  and  gilts  that 
have not been serviced. 
Pregnant sows, including gilts. 
Grown female chickens for egg production after 16 to 20 weeks of age. 
Sows ready for service and before gestation. 
An  animal  of  the  porcine  species  of  any  age,  kept  for  breeding  or 
fattening. 
Pigs from birth to weaning. 
Fowl  (chickens),  turkeys,  guinea  fowl,  ducks,  geese,  quails,  pigeons, 
pheasants  and  partridges  reared  or  kept  in  captivity  for  breeding,  the 
production of meat or eggs for consumption, or for restocking supplies of 
game. 
Young  chickens  below  the  age  for  laying  eggs.  When  reared  for  egg 
production a pullet becomes a laying hen when it begins to lay eggs at 16 
to 20  weeks of age. When reared for breeding,  young  female  and  male 
chickens are defined as pullets until 20 weeks of age. 
Female pigs during the rearing periods of mating, gestating and 
farrowing. 
Young pigs reared from weaning until fattening, typically reared from a 
live weight of around 8 kg to 30 kg. 

Intensive Rearing of Poultry or Pigs 

709 

 
 
 
 
 
Chapter 5 

GENERAL CONSIDERATIONS 

The  techniques  listed  and  described  in  these  BAT  conclusions  are  neither  prescriptive  nor 
exhaustive.  Other  techniques  may  be  used  that  ensure  at  least  an  equivalent  level  of 
environmental protection. 

Unless otherwise stated, the BAT conclusions are generally applicable. 

Unless  otherwise  stated,  emission  levels  associated  with  the  best  available  techniques  (BAT-
AELs)  for  emissions  to  air  given  in  these  BAT  conclusions  refer  to  the  mass  of  substances 
emitted  per  animal  place,  for  all  rearing  cycles  carried  out  during  1  year  (i.e.  kg 
substance/animal place/year). 

All values for concentrations expressed as mass of emitted substance per volume in air refer to 
standard conditions (dry gas at a temperature of 273.15 K, and a pressure of 101.3 kPa). 

710 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
5.1  General BAT conclusions  

Chapter 5 

The sector-specific or process-specific BAT conclusions included in Sections 5.2 and 5.3 apply 
in addition to these general BAT conclusions. 

5.1.1 

Environmental management systems (EMS) 

BAT 1. 
In order to improve the overall environmental performance of farms, BAT is 
to  implement  and  adhere  to  an  environmental  management  system  (EMS)  that 
incorporates all of the following features: 

1. 
2. 

3. 

4. 

commitment of the management, including senior management;  
definition, by the management, of an environmental policy that includes the continuous 
improvement of the environmental performance of the installation; 
planning and establishing the necessary procedures, objectives and targets, in conjunction 
with financial planning and investment;  
implementation of procedures paying particular attention to: 
structure and responsibility; 
(a) 
training, awareness and competence; 
(b) 
communication; 
(c) 
employee involvement; 
(d) 
documentation; 
(e) 
effective process control; 
(f) 
(g)  maintenance programmes; 
(h) 
(i) 

emergency preparedness and response; 
safeguarding compliance with environmental legislation. 

5. 

checking performance and taking corrective action, paying particular attention to: 
(a)  monitoring and measurement (see also the JRC Reference Report on Monitoring of 

emissions from IED installations - ROM); 
corrective and preventive action; 

(b) 
(c)  maintenance of records; 
(d) 

independent (where practicable) internal or external auditing in order to determine 
whether or not the EMS conforms to planned arrangements and has been properly 
implemented and maintained; 

6. 

7. 
8. 

9. 

review  of  the  EMS  and  its  continuing  suitability,  adequacy  and  effectiveness  by  senior 
management; 
following the development of cleaner technologies; 
consideration  for  the  environmental  impacts  from  the  eventual  decommissioning  of  the 
installation at the stage of designing a new plant, and throughout its operating life; 
application  of  sectoral  benchmarking  (e.g.  EMAS  Sectoral  Reference  Document)  on  a 
regular basis. 

Specifically  for  the  intensive  poultry  or  pig  rearing  sector,  BAT  is  also  to  incorporate  the 
following features in the EMS:  

10. 
11. 

implementation of a noise management plan (see BAT 9); 
implementation of an odour management plan (see BAT 12). 

Technical considerations relevant to applicability 
The scope (e.g. level of detail) and nature of the EMS (e.g. standardised or non-standardised) is 
related to the nature, scale and complexity of the farm, and the range of environmental impacts 
it may have.  

Intensive Rearing of Poultry or Pigs 

711 

 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

5.1.2 

Good housekeeping 

BAT 2. 
performance, BAT is to use all the techniques given below. 

In order to prevent or reduce the environmental impact and improve overall 

 

Technique 
Proper location of the plant/farm and spatial arrangements of 
the activities in order to: 
 

reduce  transport  of  animals  and  materials  (including 
manure); 
ensure  adequate  distances  from  sensitive  receptors 
requiring protection;  
take  into  account  prevailing  climatic  conditions  (e.g. 
wind and precipitation); 
consider  the  potential  future  development  capacity  of 
the farm;  
 
prevent the contamination of water. 
Educate and train staff, in particular for: 
 

relevant  regulations,  livestock  farming,  animal  health 
and welfare, manure management, worker safety; 

 

 

planning of activities;  
emergency planning and management; 
repair and maintenance of equipment. 

  manure transport and landspreading; 
 
 
 
Prepare  an  emergency  plan  for  dealing  with  unexpected 
emissions  and  incidents  such  as  pollution  of  water  bodies. 
This can include: 
 

a  plan  of  the  farm  showing  the  drainage  systems  and 
water/effluent sources; 
plans of action for responding to certain potential events 
(e.g.  fires,  leaking  or  collapsing  of  slurry  stores, 
uncontrolled run-off from manure heaps, oil spillages); 
available equipment for dealing with a pollution incident 
(e.g.  equipment  for  plugging  land  drains,  damming 
ditches, scum boards for oil spillages). 

a 

b 

c 

 

 

Regularly  check,  repair  and  maintain  structures  and 
equipment, such as: 
 

slurry  stores  for  any  sign  of  damage,  degradation, 
leakage; 
slurry pumps, mixers, separators, irrigators; 
water and feed supply systems; 
ventilation system and temperature sensors; 
silos and transport equipment (e.g. valves, tubes); 
air cleaning systems (e.g. by regular inspections). 

 
 
 
 
 
This  can 
management. 
Store  dead  animals  in  such  a  way  as  to  prevent  or  reduce 
emissions. 

include  cleanliness  of 

the  farm  and  pest 

d 

e 

Applicability 

May  not  be  generally  applicable  to 
existing plants/farms. 

Generally applicable. 

Generally applicable. 

Generally applicable. 

Generally applicable. 

712 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
5.1.3 

Nutritional management 

BAT 3. 
In  order  to  reduce  total  nitrogen  excreted  and  consequently  ammonia 
emissions  while  meeting  the  nutritional  needs  of  the  animals,  BAT  is  to  use  a  diet 
formulation  and  nutritional  strategy  which  includes  one  or  a  combination  of  the 
techniques given below. 

Chapter 5 

Technique (1) 
Reduce  the  crude  protein  content  by  using  a  N-
balanced diet based on the energy needs and digestible 
amino acids. 
Multiphase  feeding  with  a  diet  formulation  adapted  to 
the specific requirements of the production period. 

a 

b 

c 

Addition  of  controlled  amounts  of  essential  amino 
acids to a low crude protein diet. 

Applicability 

Generally applicable. 

Generally applicable.  

Applicability  may  be  restricted  when  low-
protein  feedstuffs  are  not  economically 

available.  Synthetic  amino  acids  are  not 

applicable to organic livestock production.  

d 

Use of authorised feed additives which reduce the total 
nitrogen excreted. 

Generally applicable. 

(1) A description of the techniques is given in Section 5.4.10.1. Information on the effectiveness of the techniques for 
ammonia  emission  reduction  can  be  taken  from  recognised  European  or  international  guidance  e.g.  UNECE 
guidance document on 'Options for ammonia mitigation'. 

Table 5.1:  BAT-associated total nitrogen excreted  

Parameter 

Animal category 

Total nitrogen 
excreted, expressed 
as N. 

Weaners 
Fattening pigs  
Sows (including piglets) 
Laying hens 
Broilers 
Ducks 
Turkeys  

BAT-associated total  
nitrogen excreted (1) (2) 
(kg N excreted/animal place/year) 
1.5–4.0  
7.0–13.0 
17.0–30.0 
0.4–0.8  
 0.2–0.6  
0.4–0.8  
 1.0–2.3 (3)  

(1) The lower end of the range can be achieved by using a combination of techniques. 
(2) The BAT-associated total nitrogen excreted is not applicable to pullets or breeders, for all poultry species. 
(3) The upper end of the range is associated with the rearing of male turkeys. 

The associated monitoring is in BAT 24. The BAT-associated total nitrogen excreted levels may 
not  be  applicable  to  organic  livestock  production  and  to  the  rearing  of  poultry  species  not 
indicated above. 

Intensive Rearing of Poultry or Pigs 

713 

 
 
 
 
 
 
 
 
 
 
Chapter 5 

BAT 4. 
In  order  to  reduce  the  total  phosphorus  excreted,  while  meeting  the 
nutritional  needs  of  the  animals,  BAT  is  to  use  a  diet  formulation  and  a  nutritional 
strategy which includes one or a combination of the techniques given below. 

Technique (1) 
Multiphase  feeding  with  a  diet  formulation  adapted  to  the 
specific requirements of the production period. 
Use  of  authorised  feed  additives  which  reduce  the  total 
phosphorus excreted (e.g. phytase). 

Use of highly digestible inorganic phosphates for the partial 
replacement  of  conventional  sources  of  phosphorus  in  the 
feed. 

a 

b 

c 

(1) A description of the techniques is given in Section 5.4.10.2.  

Table 5.2:  BAT-associated total phosphorus excreted  

Applicability 

Generally applicable.  

Phytase  may  not  be  applicable  in  case 
of organic livestock production. 
Generally 
constraints 
availability 
inorganic phosphates. 

applicable  within 
associated  with 
highly 
of 

the 
the 
digestible 

Parameter 

Animal category 

Total  phosphorus 
excreted, 
expressed as P2O5. 

Weaners 
Fattening pigs  
Sows (including piglets) 
Laying hens 
Broilers 
Turkeys 

BAT-associated total phosphorus 
excreted (1) (2) 
(kg P2O5 excreted/animal place/year) 
1.2–2.2  
3.5–5.4  
9.0–15.0  
0.10–0.45  
0.05–0.25  
0.15–1.0  

(1) The lower end of the range can be achieved by using a combination of techniques. 
(2) The BAT-associated total phosphorus excreted is not applicable to pullets or breeders, for all poultry species. 

The associated monitoring is in BAT 24. The BAT-associated total phosphorus excreted levels 
may not be applicable to organic livestock production and to the rearing of poultry species not 
indicated above. 

5.1.4 

Efficient use of water 

BAT 5. 
given below. 

In order to use water efficiently, BAT is to use a combination of the techniques 

a  Keep a record of water use. 

Generally applicable. 

Technique 

Applicability 

b  Detect and repair water leakages. 

c 

d 

e 

Use  high-pressure  cleaners  for  cleaning  animal  housing 
and equipment. 
Select  and  use  suitable equipment  (e.g.  nipple  drinkers, 
round  drinkers,  water  troughs)  for  the  specific  animal 
category while ensuring water availability (ad libitum). 
Verify  and  (if  necessary)  adjust  on  a  regular  basis  the 
calibration of the drinking water equipment. 

f  Reuse uncontaminated rainwater as cleaning water. 

Generally applicable. 
Not  applicable  to  poultry  plants  using 
dry cleaning systems. 

Generally applicable. 

Generally applicable. 

May  not  be  applicable  to  existing 
farms, due to high costs.  
Applicability  may  be  restricted  by 
biosecurity risks. 

714 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
5.1.5 

Emissions from waste water 

BAT 6. 
of the techniques given below. 

In order to reduce the generation of waste water, BAT is to use a combination 

Chapter 5 

Technique (1) 

Applicability 

a  Keep the fouled yard areas as small as possible. 

Generally applicable. 

b  Minimise use of water. 

c 

Segregate  uncontaminated  rainwater  from  waste  water 
streams that require treatment. 

(1) A description of the technique is given in Section 5.4.1. 

Generally applicable. 
May  not  be  applicable  to  existing 
farms. 

BAT 7. 
combination of the techniques given below. 

In order to reduce emissions to water from waste water, BAT is to use one or a 

Technique (1) 
Drain  waste  water  to  a  dedicated  container  or  to  a  slurry 
store. 

a 

Applicability 

Generally applicable. 

b  Treat waste water. 

c 

Landspreading  of  waste  water  e.g.  by  using  an  irrigation 
system  such  as  sprinkler,  travelling  irrigator,  tanker, 
umbilical injector. 

(1) A description of the techniques is given in Section 5.4.1. 

Generally applicable. 
Applicability  may  be  restricted  due  to 
the limited availability of suitable land 
adjacent to the farm.  
Applicable only for waste water with a 
proven low level of contamination. 

Intensive Rearing of Poultry or Pigs 

715 

Chapter 5 

5.1.6 

Efficient use of energy 

BAT 8. 
techniques given below. 

In order to use energy efficiently in a farm, BAT is to use a combination of the 

a 

b 

Technique (1) 
High efficiency heating/cooling and 
ventilation systems. 
Optimisation  of  heating/cooling  and 
ventilation  systems  and  management, 
especially where air cleaning systems 
are used. 

c  

Insulation of the walls, floors and/or 
ceilings of animal housing. 

d   Use of energy-efficient lighting. 

Use of heat exchangers. One of the 
following systems may be used: 

e 

1. 
2. 
3. 

air-air; 
air-water; 
air-ground. 

f  Use of heat pumps for heat recovery. 

g  

Heat recovery with heated and cooled 
littered floor (combideck system). 

h  Apply natural ventilation. 

Applicability 

May not be applicable to existing plants. 

Generally applicable. 

May not be applicable to plants using natural ventilation. 

Insulation may not be applicable to existing plants due to 
structural restrictions. 
Generally applicable. 

Air-ground  heat  exchangers  are  only  applicable  when 
there  is  available  space  due  to  the  need  for  a  large  soil 
surface. 

The  applicability  of  heat  pumps  based  on  geothermal 
heat recovery is limited when using horizontal pipes due 
to the need for space availability. 
Not applicable to pig plants. 
Applicability depends on the possibility to install closed 
underground storage for the circulating water.  
Not  applicable  to  plants  with  a  centralised  ventilation 
system. 
In pig plants, this may not be applicable to: 
- housing systems with littered floors in warm climates; 
-  housing  systems  without  littered  floors  or  without 
in  cold 
insulated  boxes  (e.g.  kennels) 

covered, 
climates. 

In poultry plants, this may not be applicable:  
-  during  the  initial  stage  of  rearing,  apart  from  duck 

production; 

- due to extreme climate conditions. 

(1) A description of the techniques is given in Section 5.4.2. 

5.1.7 

Noise emissions 

BAT 9. 
In order to prevent or, where that is not practicable, to reduce noise emissions, 
BAT is to set up and implement a noise management plan, as part of the environmental 
management system (see BAT 1), that includes the following elements: 

i. 
ii. 
iii. 
iv. 

v. 

716 

a protocol containing appropriate actions and timelines; 
a protocol for conducting noise monitoring; 
a protocol for response to identified noise events; 
a  noise reduction  programme  designed  to  e.g.  identify  the  source(s),  to  monitor  noise 
emissions, to characterise the contributions of the sources and to implement elimination 
and/or reduction measures; 
a  review  of  historical  noise  incidents  and  remedies  and  the  dissemination  of  noise 
incident knowledge. 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Applicability 
BAT 9  is  only  applicable  to  cases  where  a  noise  nuisance  at  sensitive  receptors  is  expected 
and/or has been substantiated.  

Chapter 5 

BAT 10. 
BAT is to use one or a combination of the techniques given below. 

In order to prevent, or where that is not practicable, to reduce noise emissions, 

Technique 

Ensure 
adequate 
distances  between 
the  plant/farm  and 
sensitive 
the 
receptors. 

a 

b 

Equipment 
location. 

Description 

Applicability 

At  the  planning  stage  of  the  plant/farm, 
adequate  distances  between  the  plant/farm 
and  the  sensitive  receptors  are  ensured  by 
applying minimum standard distances. 

Noise levels can be reduced by:  
i. increasing the distance between the emitter 
and  the  receiver  (by  locating  equipment 
as  far  away  as  practicable  from  sensitive 
receptors); 

ii.  minimising  the  length  of  feed  delivery 

pipes; 

May 
not 
applicable 
plants/farms. 

be 
to 

generally 
existing 

In the case of existing plants, 
the  relocation  of  equipment 
may be restricted by the lack 
of space or excessive costs. 

iii. Locating feed bins and feed silos so as to 
minimise  the  movement  of  vehicles  on 
the farm.  

These include measures, such as: 

i. closure of doors and major openings of the 
building,  especially  during  feeding  time, 
if possible; 

c 

Operational 
measures. 

d 

Low-noise 
equipment. 

e 

Noise-control 
equipment. 

ii. equipment operation by experienced staff; 
iii. avoidance of noisy activities at night and 

during weekends, if possible; 

iv.  provisions  for  noise  control  during 

maintenance activities; 

v. operate conveyers and augers full of feed, 

if possible; 

vi. keep outdoor scraped areas to a minimum 
in  order  to  reduce  noise  from  scraper 
tractors. 

This includes equipment, such as: 
i. high efficiency fans, when natural 

ventilation is not possible or sufficient; 

ii. pumps and compressors; 
iii. feeding system which reduces the pre-
feeding stimulus (e.g. holding hoppers, 
passive ad libitum feeders, compact 
feeders). 

This includes: 
i. noise reducers; 
ii. vibration isolation; 
iii. enclosure of noisy equipment (e.g. mills, 

pneumatic conveyers); 
iv. soundproofing of buildings. 

f  Noise abatement. 

Noise  propagation  can  be 
reduced  by 
inserting  obstacles  between  emitters  and 
receivers.  

Generally applicable.  

is 

only 

BAT 
7.d.iii 
applicable to pig plants. 
Passive  ad  libitum  feeders 
are only applicable  when the 
equipment is new or replaced 
or  when  animals  do  not 
require a restricted feeding. 

may 
to 

be 
Applicability 
restricted  due 
space 
requirements,  and  health  and 
safety issues. 
Not  applicable 
to  noise-
absorbent materials impeding 
the  effective  cleaning  of  the 
plant. 
May 
generally 
be 
applicable  due  to  biosecurity 
reasons. 

not 

Intensive Rearing of Poultry or Pigs 

717 

 
 
 
 
 
 
 
Chapter 5 

5.1.8 

Dust emissions 

BAT 11. 
or a combination of the techniques given below. 

In order to reduce dust emissions from each animal house, BAT is to use one 

Technique (1) 
Reduce  dust  generation  inside  livestock 
buildings. For this purpose, a combination 
of the following techniques may be used:  
1.  Use  coarser  litter  material  (e.g.  long 
straw  or  wood  shavings  rather 
than 
chopped straw); 
2.  Apply  fresh  litter  using  a  low-dust 
littering technique (e.g. by hand); 
3. Apply ad libitum feeding; 

4.  Use  moist  feed,  pelleted  feed  or  add 

oily  raw  materials  or  binders  in  dry  feed 
systems; 
5.  Equip  dry  feed  stores  which  are  filled 
pneumatically with dust separators; 
6.  Design  and  operate  the  ventilation 

system  with  low  air  speed  within  the 

house. 
Reduce dust concentration inside housing 
by  applying  one  of 
following 
techniques:  

the 

a 

b 

1.Water fogging; 

2. Oil spraying; 

3. Ionisation. 

c 

Treatment  of  exhaust  air  by  an  air 
cleaning system, such as: 

1. Water trap; 

2. Dry filter; 

3. Water scrubber; 
4. Wet acid scrubber; 
5. Bioscrubber (or biotrickling filter); 
6.  Two-stage  or  three-stage  air  cleaning 
system; 

7. Biofilter. 

Applicability 

Long straw is not applicable to slurry-based systems. 

Generally applicable. 

Generally applicable. 

Generally applicable. 

Generally applicable. 

Applicability  may  be 
considerations. 

limited  by  animal  welfare 

Applicability may be restricted by the animal sensation 
of  thermal  decrease  during  fogging,  in  particular  at 
sensitive stages of the animal's life, and/or for cold and 
humid climates. 
Applicability  may  be  also  restricted  for  solid  manure 
systems  at  the  end  of  the  rearing  period  due  to  high 
ammonia emissions. 
Only  applicable  to  poultry  plants  with  birds  older  than 
around  21  days.  The  applicability  to  plants  for  laying 
hens may be limited due to the risk of contamination of 
the equipment present in the shed. 
May  not  be  applicable  to  pig  plants  or  to  existing 
poultry plants due to technical and/or economic reasons. 

Only  applicable  to  plants  with  a  tunnel  ventilation 
system.  
Only  applicable 
ventilation system. 

to  poultry  plants  with  a 

tunnel 

This  technique  may  not  be  generally  applicable  due  to 
the high implementation cost. 
Applicable  to  existing  plants  only  where  a  centralised 
ventilation system is used. 

Only applicable to slurry-based plants. 
A sufficient area outside the animal house is needed to 
accommodate the filter packages.  
This  technique  may  not  be  generally  applicable  due  to 
the high implementation cost. 
Applicable  to  existing  plants  only  where  a  centralised 
ventilation system is used.  

(1) A description of the techniques is given in Sections 5.4.3 and 5.4.11. 

718 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

5.1.9 

Odour emissions 

BAT 12. 
In  order  to  prevent,  or  where  that  is  not  practicable,  to  reduce  odour 
emissions  from  a  farm,  BAT  is  to  set  up,  implement  and  regularly  review  an  odour 
management  plan,  as  part  of  the  environmental  management  system  (see  BAT 1),  that 
includes the following elements: 

i. 
ii. 
iii. 
iv. 

v. 

a protocol containing appropriate actions and timelines; 
a protocol for conducting odour monitoring; 
a protocol for response to identified odour nuisance; 
an odour prevention and elimination programme designed to e.g. identify the source(s), 
to  monitor  odour  emissions  (see  BAT 26),  to  characterise  the  contributions  of  the 
sources and to implement elimination and/or reduction measures; 
a  review  of  historical  odour  incidents  and  remedies  and  the  dissemination  of  odour 
incident knowledge. 

The associated monitoring is in BAT 26. 

Applicability 
BAT 12 is only applicable to cases where an odour nuisance at sensitive receptors is expected 
and/or has been substantiated.  

BAT 13. 
In  order  to  prevent  or,  where  that  is  not  practicable,  to  reduce  odour 
emissions and/or odour impact from a farm, BAT is to use a combination of the techniques 
given below. 

a 

Technique (1) 
Ensure  adequate  distances  between  the  farm/plant 
and the sensitive receptors. 
Use  a  housing  system  which  implements  one  or  a 

combination of the following principles: 

- keeping the animals and the surfaces dry and clean 
(e.g.  avoid  feed  spillages,  avoid  dung  in  lying 
areas of partly slatted floors); 

-  reducing  the  emitting  surface  of  manure  (e.g.  use 
metal  or  plastic  slats,  channels  with  a  reduced 
exposed manure surface); 

- removing manure frequently to an external 

b 

(covered) manure store; 

- reducing the temperature of the manure (e.g. by 
slurry cooling) and of the indoor environment; 

- decreasing the air flow and velocity over the 

Applicability 
May  not  be  generally  applicable  to  existing 
farms/plants. 

Decreasing  the  temperature  of  the  indoor 
environment,  the  air  flow  and  the  velocity 
may  not  be  applicable  due  to  animal  welfare 
considerations. 
Slurry  removal  by  flushing  is  not  applicable 
to  pig  farms 
to  sensitive 
located  close 
receptors due to odour peaks. 
See  applicability  for  animal  housing 
in 
BAT 30,  BAT 31,  BAT 32,  BAT 33  and 
BAT 34. 

manure surface; 

- keeping the litter dry and under aerobic conditions 

in litter-based systems. 

Optimise  the  discharge  conditions  of  exhaust  air 
the  animal  house  by  using  one  or  a 

from 
combination of the following techniques: 

- increasing the outlet height (e.g. exhaust air above 
roof  level,  stacks,  divert  air  exhaust  through  the 
ridge instead of through the low part of the walls); 
- increasing the vertical outlet ventilation velocity; 
-  effective  placement  of  external  barriers  to  create 
(e.g. 

the  outgoing  air 

flow 

in 

turbulence 
vegetation); 

c 

Alignment of the ridge axis is not applicable 
to existing plants. 

-  adding  deflector  covers  in  exhaust  apertures 
located  in  low  parts  of  walls  in  order  to  divert 
exhaust air towards the ground; 

Intensive Rearing of Poultry or Pigs 

719 

 
 
 
 
 
 
 
 
Chapter 5 

Technique (1) 
-  dispersing  the  exhaust  air  at  the  housing  side 

which faces away from the sensitive receptor; 

Applicability 

-  aligning  the  ridge  axis  of  a  naturally  ventilated 
the  prevailing  wind 
to 

transversally 

building 
direction. 

d 

Use an air cleaning system, such as: 
1. Bioscrubber (or biotrickling filter); 
2. Biofilter; 
3. Two-stage or three-stage air cleaning system. 

e 

Use  one  or  a  combination  of 
techniques for storage of manure:  

the  following 

1. Cover slurry or solid manure during storage; 

the 

2.  Locate  the  store  taking  into  account  the  general 
wind  direction  and/or  adopt  measures  to  reduce 
wind  speed  around  and  above  the  store  (e.g.  trees, 
natural barriers); 
3. Minimise stirring of slurry. 
Process  manure  with  one  of 
following 
techniques  in  order  to  minimise  odour  emissions 
during (or prior to) landspreading: 
1. Aerobic digestion (aeration) of slurry; 
2. Compost solid manure; 
3. Anaerobic digestion. 
Use  one  or  a  combination  of 
techniques for manure landspreading: 
1.  Band  spreader,  shallow  injector  or  deep  injector 
for slurry landspreading; 
2. Incorporate manure as soon as possible. 

the  following 

f 

g 

technique  may  not  be  generally 
This 
applicable  due  to  the  high  implementation 
cost. 
Applicable  to  existing  plants  only  where  a 
centralised ventilation system is used.  
A biofilter is only applicable to slurry-based 
plants. 
For  a  biofilter,  a  sufficient  area  outside  the 
animal  house  is  needed  to  accommodate  the 
filter packages.  

See applicability of BAT 16.b for slurry.  
See  applicability  of  BAT 14.b  for  solid 
manure. 

Generally applicable. 

Generally applicable. 

See applicability of BAT 19.d. 
See applicability of BAT 19.f. 
See applicability of BAT 19.b. 

See  applicability  of  BAT 21.b,  BAT 21.c  or 
BAT 21.d. 
See applicability of BAT 22. 

(1) A description of the techniques is given in Sections 5.4.4 and 5.4.11.  

5.1.10 

Emissions from solid manure storage 

BAT 14. 
BAT is to use one or a combination of the techniques given below. 

In order to reduce ammonia emissions to air from the storage of solid manure, 

Technique (1) 
the  ratio  between 

Reduce 
the  emitting 
surface  area  and  the  volume  of  the  solid 
manure heap. 

a 

Applicability 

Generally applicable. 

b 

Cover solid manure heaps. 

Store dried solid manure in a barn. 

c 
(1) A description of the techniques is given in Section 5.4.5. 

Generally applicable  when  solid  manure is dried 
or  pre-dried  in  animal  housing.  May  not  be 
applicable  to  not  dried  solid  manure  in  case  of 
frequent addition to the heap. 
Generally applicable. 

720 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
BAT 15. 
In  order  to  prevent,  or  where  that  is  not  practicable,  to  reduce  emissions  to 
soil  and  water  from  the  storage  of  solid  manure,  BAT  is  to  use  a  combination  of  the 
techniques given below in the following order of priority. 

Chapter 5 

Technique (1) 

Applicability 

Store dried solid manure in a barn. 

a  
b   Use a concrete silo for storage of solid manure. 

Generally applicable 
Generally applicable. 

c 

d  

e 

Store  solid  manure  on  solid  impermeable  floor 
equipped with a drainage system and a collection 
tank for the run-off. 
Select a storage facility with a sufficient capacity 
to hold the solid manure during periods in which 
landspreading is not possible. 
Store  solid  manure  in  field  heaps  placed  away 
from  surface  and/or  underground  watercourses 
which liquid run-off might enter. 

(1) A description of the techniques is given in Section 5.4.5. 

5.1.11 

Emissions from slurry storage 

Generally applicable. 

Generally applicable. 

Only  applicable  to  temporary  field  heaps 
which change location each year. 

BAT 16. 
a combination of the techniques given below. 

In order to reduce ammonia emissions to air from a slurry store, BAT is to use 

Technique (1) 
Appropriate  design  and  management  of  the 
slurry  store  by  using  a  combination  of  the 
following techniques: 

1.  Reduce  the  ratio  between  the  emitting 
surface  area  and  the  volume  of  the  slurry 
store; 

2. Reduce wind velocity and air exchange on 
the slurry surface by operating the  store at a 
lower level of fill; 
3. Minimise stirring of slurry. 
Cover the slurry  store. For this purpose, one 
of the following techniques may be used: 

a 

b 

Applicability 

May  not  be  generally  applicable  to  existing 
stores. 
Excessively  high  slurry  stores  may  not  be 
applicable due to increased costs and safety risks. 

May  not  be  generally  applicable  to  existing 
stores. 

Generally applicable. 

1.  Rigid cover; 

2.  Flexible covers; 

3.  Floating covers such as: 

 
 
 
 
 
 
 

plastic pellets; 
light bulk materials; 
floating flexible covers; 
geometrical plastic tiles; 
air-inflated cover; 
natural crust; 
straw. 

and 

considerations 

May  not  be  applicable  to  existing  plants  due  to 
economic 
structural 
limitations to withstand the extra load.  
Flexible covers are not applicable to areas where 
prevailing  weather  conditions  can  compromise 
their structure. 
The use of plastic pellets, light bulk materials and 
geometrical  plastic  tiles  is  not  applicable  to 
naturally crusting slurries.  
Agitation of the slurry during stirring, filling and 
emptying  may preclude the  use  of some  floating 
materials  which  may  cause  sedimentation  or 
blockages in the pumps. 
Natural crust formation may not be applicable to 
cold climates and/or to slurry with low dry matter 
content.  
Natural  crust  is  not  applicable  to  stores  where 
stirring,  filling  and/or  discharging  of  slurry 
renders the natural crust unstable.  
Generally applicable. 

Slurry acidification. 

c 
(1) A description of the techniques is given in Sections 5.4.6.1 and 5.4.12.3. 

Intensive Rearing of Poultry or Pigs 

721 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

BAT 17. 
store (lagoon), BAT is to use a combination of the techniques given below. 

In  order  to  reduce  ammonia  emissions  to  air  from  an  earth-banked  slurry 

Technique (1) 

a  Minimise stirring of the slurry. 

b 

Cover 
the  earth-banked  slurry  store 
(lagoon)  with  a  flexible  and/or  floating 
cover such as: 
 
 
 
 

flexible plastic sheets; 
light bulk materials; 
natural crust; 
straw. 

Applicability 

Generally applicable. 
Plastic  sheets  may  not  be  applicable  to  large  existing 
lagoons due to structural reasons. 
Straw and light bulk materials may not be applicable to 
large  lagoons  where  wind  drift  does  not  permit  the 
lagoon surface to be kept fully covered.  
The  use  of  light  bulk  materials  is  not  applicable  to 
naturally crusting slurries. 
Agitation  of  the  slurry  during  stirring,  filling  and 
emptying  may  preclude  the  use  of  some  floating 
materials which may cause sedimentation or blockages 
in the pumps.  
Natural crust formation  may  not be  applicable  to cold 
climates and/or to slurry with low dry matter content.  
Natural  crust  is  not  applicable  to  lagoons  where 
stirring, filling and/or discharging of slurry renders the 
natural crust unstable. 

(1) A description of the techniques is given in Section 5.4.6.1. 

BAT 18. 
In order to prevent emissions to soil and water from slurry collection, piping, 
and from a store and/or an earth-banked storage (lagoon), BAT is to use a combination of 
the techniques given below. 

Technique (1) 

Applicability 

a 

b 

c 

d 

e 

f 

Use stores that are able to withstand mechanical, 
chemical and thermal influences. 
Select  a  storage  facility  with  a  sufficient 
capacity  to  hold  the  slurry  during  periods  in 
which landspreading is not possible. 
Construct leak-proof facilities and equipment for 
collection  and  transfer  of  slurry  (e.g.  pits, 
channels, drains, pump stations). 
Store  slurry  in  earth-banked  stores  (lagoons) 
with  an  impermeable  base  and  walls  e.g.  with 
clay or plastic lining (or double-lined). 
Install  a 
system,  e.g. 
consisting  of  a  geomembrane,  a  drainage  layer 
and a drainage pipe system. 
Check structural integrity of stores at least once 
every year. 

leakage  detection 

Generally applicable. 

Generally applicable.  

Generally applicable. 

Generally applicable to lagoons. 

Only applicable to new plants. 

Generally applicable. 

(1) A description of the techniques is given in Section 5.4.6.2. 

722 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
5.1.12 

On farm processing of manure 

Chapter 5 

BAT 19. 
If  on-farm  processing  of  manure  is  used,  in  order  to  reduce  emissions  of 
nitrogen,  phosphorus,  odour  and  microbial  pathogens  to  air  and  water  and  facilitate 
manure storage and/or landspreading, BAT is to process the manure by applying one or a 
combination of the techniques given below. 

Technique (1) 
Mechanical  separation  of  slurry. 
This includes e.g.: 
  Screw press separator; 
  Decanter-centrifuge separator; 
  Coagulation- Flocculation; 
  Separation by sieves;  
  Filter pressing. 
Anaerobic digestion of manure in a 
biogas installation. 
Use of an external tunnel for 
manure drying. 

Aerobic digestion (aeration) of 
slurry. 

a 

b 

c 

d 

e 

Nitrification-denitrification of 
slurry. 

Applicability 

Only applicable when: 
-  a  reduction  of  nitrogen  and  phosphorus  content  is  needed 

due to limited available land for manure application; 

-  manure  cannot  be  transported  for  landspreading  at  a 

reasonable cost. 

The  use  of  polyacrylamide  as  a  flocculant  may  not  be 
applicable due to the risk of acrylamide formation. 
This  technique  may  not  be  generally  applicable  due  to  the 
high implementation cost. 
Only applicable to manure from plants for laying hens. Not 
applicable to existing plants without manure belts. 
Only  applicable  when  pathogen  and  odour  reduction  is 
important prior to landspreading. In cold climates, it may be 
difficult  to  maintain  the  required  level  of  aeration  during 
winter. 
Not  applicable  to  new  plants/farms.  Only  applicable  to 
existing  plants/farms  when  the  removal  of  nitrogen  is 
necessary  due 
land  for  manure 
limited  available 
application. 
Only applicable when: 
-  manure  cannot  be  transported  for  landspreading  at  a 

to 

reasonable cost;  

f  Composting of solid manure. 

-  pathogen  and  odour  reduction  is  important  prior  to 

landspreading; 

-  there  is  enough  space  in  the  farm  for  windrows  to  be 

established. 

(1) A description of the techniques is given in Section 5.4.7 

Intensive Rearing of Poultry or Pigs 

723 

 
 
 
 
 
 
 
Chapter 5 

5.1.13  Manure landspreading 

BAT 20. 
In  order  to  prevent  or,  where  that  is  not  practicable,  to  reduce  emissions  of 
nitrogen,  phosphorus  and  microbial  pathogens  to  soil  and  water  from  manure 
landspreading, BAT is to use all the techniques given below. 

Technique 

soil type, conditions and slope of the field; 
climatic conditions; 
field drainage and irrigation; 
crop rotations; 
water resources and water protected zones. 

Assess the manure receiving land to identify risks of run-off, taking into account: 
 
 
 
 
 
Keep sufficient distance between manure spreading fields (leaving an untreated strip of land) and: 
1. areas where there is a risk of run-off to water such as watercourses, springs, boreholes, etc.; 
2. neighbouring properties (including hedges). 
Avoid  manure  spreading  when the  risk of run-off can be significant.  In particular,  manure is  not 
applied when: 
1. 
2. 

the field is flooded, frozen or snow-covered; 
soil  conditions  (e.g.  water  saturation  or  compaction)  in  combination  with  the  slope  of  the 
field and/or field drainage are such that the risk of run-off or drainage is high; 
run-off can be anticipated according to expected rainfall events. 

3. 
Adapt the  manure landspreading rate  taking into account the  nitrogen and phosphorus content of 
the  manure  and  taking  into  account  the  characteristics  of  the  soil  (e.g.  nutrient  content),  the 
seasonal crop requirements and weather or field conditions that could cause run-off. 

a 

b 

c 

d 

e  Synchronize manure landspreading with the nutrient demand of crops. 

f 

g 

h 

Check the spreading fields at regular intervals to identify any sign of run-off and properly respond 
when necessary. 
Ensure  adequate  access  to  the  manure  store  and  that  loading  of  manure  can  be  done  effectively 
without spillage.  
Check  that  machinery  for  manure  landspreading  is  in  good  working  order  and  set  at  the  proper 
application rate. 

BAT 21. 
is to use one or a combination of the techniques given below.  

In order to reduce ammonia emissions to air from slurry landpsreading, BAT 

Technique (1) 

Slurry  dilution,  followed 
by  techniques  such  as 
low-pressure 
water 
irrigation system. 

by 
the 

Band 
spreader, 
applying  one  of 
following techniques:  
1. Trailing hose; 
2. Trailing shoe. 

Shallow 
slot). 

injector  (open 

injector 

(closed 

Deep 
slot). 

a 

b 

c 

d 

Applicability 
Not  applicable  to  crops  grown  to  be  eaten  raw  due  to  the  risk  of 
contamination. 
Not applicable when the soil type does not allow rapid infiltration of 
dilute slurry into the soil. 
Not applicable when crops do not require irrigation. 
Applicable to fields easily connected to the farm by pipework. 

Applicability may be limited when the straw content of the slurry is 
too high or  when the dry  matter content of the slurry is  higher than 
10 %. 
Trailing shoe is not applicable to growing solid-seeded arable crops. 

Not  applicable  on  stony,  shallow  or  compacted  soil  where  it  is 
difficult to achieve a uniform penetration. 
Applicability  may  be  limited  where  crops  may  be  damaged  by 
machinery. 
Not  applicable  on  stony,  shallow  or  compacted  soil  where  it  is 
difficult to achieve a uniform penetration and an effective slit closure. 
Not applicable during the vegetation of the crops. Not applicable on 
grassland, unless changing to arable land or when reseeding. 
Generally applicable. 

Slurry acidification. 

e 
(1) A description of the techniques is given in Sections 5.4.8.1 and 5.4.12.3. 

724 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Chapter 5 

BAT 22. 
BAT is to incorporate the manure into the soil as soon as possible.  

In  order  to  reduce  ammonia  emissions  to  air  from  manure  landspreading, 

Description 
Incorporation of  manure spread on the soil surface is done by either ploughing or using other 
cultivation equipment, such as tines or disc harrows, depending on the soil type and conditions. 
Manure is completely mixed with soil or buried. 

Solid manure spreading is carried out by a suitable spreader (e.g. rota-spreader, rear discharge 
spreader, dual-purpose spreader). Slurry landspreading is carried out according to BAT 21. 

Applicability 
Not  applicable  to  grassland  and  conservation  tillage,  unless  changing  to  arable  land  or  when 
reseeding. Not applicable to cultivated land with crops that can be damaged by the incorporation 
of manure. Incorporation of slurry is not applicable after landspreading using shallow or deep 
injectors. 

Table 5.3:  BAT-associated time delay between manure landspreading and incorporation into the 

soil 

Parameter 

BAT-associated time delay between manure landspreading and 
incorporation into the soil (hours) 
0 (1)–4 (2) 
Time 
(1) The lower end of the range corresponds to immediate incorporation.  
(2)  The  upper  end  of  the  range  can  be  up  to  12  hours  when  conditions  are  not  favourable  for  a  faster 

incorporation, e.g. when human and machinery resources are not economically available.  

5.1.14 

Emissions from the whole production process 

BAT 23. 
In order to reduce ammonia emissions from the whole production process for 
the  rearing  of  pigs  (including  sows)  or  poultry,  BAT  is  to  estimate  or  calculate  the 
reduction  of  ammonia  emissions  from  the  whole  production  process  using  the  BAT 
implemented on the farm. 

5.1.15  Monitoring of emissions and process parameters 

BAT 24.  BAT is to monitor the total nitrogen and total phosphorus excreted in manure 
using one of the following techniques with at least the frequency given below. 

Technique (1) 
Calculation  by  using  a  mass  balance  of 
nitrogen  and  phosphorus  based  on  the 
feed intake, crude protein content of the 
diet, 
total  phosphorus  and  animal 
performance. 
Estimation by using manure analysis for 
total  nitrogen  and 
total  phosphorus 
content. 

a 

b 

Frequency 

Applicability 

Once every year for each animal 
category. 

Generally 
applicable. 

(1) A description of the techniques is given in Section 5.4.9.1.  

Intensive Rearing of Poultry or Pigs 

725 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

BAT 25.  BAT  is  to  monitor  ammonia  emissions  to  air  using  one  of  the  following 
techniques with at least the frequency given below. 

a 

b 

Technique (1) 
Estimation  by  using  a  mass 
balance  based  on  the  excretion 
and 
total 
total 
ammoniacal) nitrogen present at 
each  manure  management 
stage. 

the 

(or 

Frequency 

Applicability 

Once  every  year  for  each 
animal category. 

Generally applicable. 

Calculation  by  measuring  the 
ammonia  concentration  and  the 
ventilation 
ISO, 
national 
international 
standard  methods  or  other 
methods  ensuring  data  of  an 
equivalent scientific quality. 

rate  using 
or 

time 

there 

Every 
are 
significant  changes  to  at  least 
one 
following 
the 
parameters: 
(a)  the 

type  of 

livestock 

of 

reared at the farm; 

(b)  the housing system. 

c 

Estimation  by  using  emission 
factors. 

Once  every  year  for  each 
animal category. 
(1) A description of the techniques is given in Section 5.4.9.2. 

Only  applicable  to  emissions 
from each animal house. 
Not applicable to plants with an 
air cleaning system installed. In 
this case, BAT 28 applies. 
Due 
of 
cost 
the 
measurements,  this  technique 
generally 
be 
not 
may 
applicable. 

to 

Generally applicable. 

BAT 26.  BAT is to periodically monitor odour emissions to air. 

Description 
Odour emissions can be monitored by using: 
-  EN  standards  (e.g.  by  using  dynamic  olfactometry  according  to  EN  13725  in  order  to 

determine odour concentration).  

-  When  applying  alternative  methods  for  which  no  EN  standards  are  available  (e.g. 
measurement/estimation  of  odour  exposure,  estimation  of  odour  impact),  ISO,  national  or 
other  international  standards  that  ensure  the  provision  of  data  of  an  equivalent  scientific 
quality can be used.  

Applicability  
BAT 26 is only applicable to cases where an odour nuisance at sensitive receptors is expected 
and/or has been substantiated.  

BAT 27.  BAT  is  to  monitor  dust  emissions  from  each  animal  house  using  one  of  the 
following techniques with at least the frequency given below. 

Technique (1) 

Frequency 

a 

rate 

the 
Calculation  by  measuring 
the 
dust 
and 
concentration 
using  EN 
ventilation 
other 
standard  methods 
methods 
or 
international) ensuring data of an 
equivalent scientific quality. 

or 
national 

(ISO, 

Once every year. 

b 

Estimation  by  using  emission 
factors. 

Once every year. 

(1) A description of the techniques is given in Section 5.4.9.2. 

Applicability 
Only  applicable  to  dust  emissions 
from each animal house. 
Not  applicable  to  plants  with  an 
air  cleaning  system  installed.  In 
this case, BAT 28 applies. 
Due  to  the  cost  of  measurements, 
this 
technique  may  not  be 
generally applicable. 
Due  to  the  cost  of  establishing 
emissions  factors,  this  technique 
may not be generally applicable. 

726 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
BAT 28.  BAT is to monitor, ammonia, dust and/or odour emissions from each animal 
house equipped with an air cleaning system by using all of the following techniques with at 
least the frequency given below. 

Chapter 5 

Technique (1)  
Verification  of  the  air  cleaning  system 
performance  by  measuring  ammonia, 
odour  and/or  dust  under  practical  farm 
conditions  and  according  to  a  prescribed 
measurement  protocol  and  using  EN 
standard  methods  or  other  methods  (ISO, 
national  or  international)  ensuring  data  of 
an equivalent scientific quality. 
Control of the effective function of the air 
cleaning  system  (e.g.  by  continuously 
recording  operational  parameters  or  using 
alarm systems). 

a 

b 

Frequency 

Applicability 

Once 

Not  applicable  if  the  air  cleaning 
in 
system  has  been  verified 
similar 
combination  with 
housing  system  and  operating 
conditions. 

a 

Daily 

Generally applicable. 

(1) A description of the techniques is given in Section 5.4.9.3. 

BAT 29.  BAT is to monitor the following process parameters at least once every year. 

Parameter  

Description 

a  Water consumption.  

b 

Electric energy 
consumption.  

c  Fuel consumption.  

d 

Number of incoming 
and outgoing animals, 
including births and 
deaths when relevant. 

e  Feed consumption.  

f  Manure generation. 

Recording using e.g. 
suitable meters or invoices. 
The main water-consuming 
processes in animal houses 
(cleaning, feeding, etc.) can be 
monitored separately. 

Recording using e.g. 
suitable meters or invoices. 
Electricity consumption of 
animal houses is monitored 
separately from other plants in 
the farm. The main energy-
consuming processes in animal 
houses (heating, ventilation, 
lighting, etc.) can be monitored 
separately. 
Recording using e.g. 
suitable meters or invoices.  

Recording using e.g. existing 
registers.  

Recording using e.g. invoices or 
existing registers. 
Recording using e.g. existing 
registers. 

Applicability 
Monitoring the main 
water-consuming processes 
separately may not be 
applicable to existing 
farms, depending on the 
configuration of the water 
supply network. 

Monitoring the main 
energy-consuming 
processes separately may 
not be applicable to 
existing farms, depending 
on the configuration of the 
energy supply network. 

Generally applicable. 

Intensive Rearing of Poultry or Pigs 

727 

 
 
 
 
 
 
 
 
 
 
Chapter 5 

5.2  BAT conclusions for the intensive rearing of pigs  

5.2.1 

Ammonia emissions from pig houses 

BAT 30. 
use one or a combination of the techniques given below. 

In order to reduce ammonia emissions to air from  each pig house, BAT is to 

Technique (1) 

Animal 
category 

Applicability 

a 

One of the following techniques, 
which apply one or a combination 
of the following principles:  
i) reduce the ammonia emitting 

surface; 

ii) increase the frequency of slurry 
(manure) removal to external 
storage;  

iii) separate urine from faeces; 
iv) keep litter clean and dry. 
0.  A  deep  pit  (in  case  of  a  fully  or 
partly  slatted  floor)  only  if  used  in 
combination  with  an  additional 
mitigation measure, e.g.: 
- a combination of nutritional 
management techniques; 
- air cleaning system; 
- pH reduction of the slurry; 
- slurry cooling. 

1.  A vacuum system for frequent 
slurry removal (in case of a 
fully or partly slatted floor). 

2.  Slanted walls in the manure 
channel (in case of a fully or 
partly slatted floor). 

3.  A scraper for frequent slurry 
removal (in case of a fully or 
partly slatted floor). 

4.  Frequent slurry removal by 

flushing (in case of a fully or 
partly slatted floor). 

All pigs 

All pigs 

All pigs 

All pigs 

All pigs 

5.  Reduced manure pit (in case of 

a partly slatted floor). 

6.  Full litter system (in case of a 

solid concrete floor). 

7.  Kennel / hut housing (in case of 

a partly slatted floor). 

Mating and 
gestating sows 
Fattening pigs 
Mating and 
gestating sows 
Weaners 
Fattening pigs 
Mating and 
gestating sows 
Weaners 
Fattening pigs 

Not applicable to new plants, unless a 
deep pit is combined with an air cleaning 
system, slurry cooling and/or pH 
reduction of the slurry.  

May not be generally applicable to 
existing plants due to technical and/or 
economic considerations. 

May not be generally applicable to 
existing plants due to technical and/or 
economic considerations. 
When the liquid fraction of the slurry is 
used for flushing, this technique may not 
be applicable to farms located close to 
sensitive receptors due to odour peaks 
during flushing.  
May not be generally applicable to 
existing plants due to technical and/or 
economic considerations. 
Solid manure systems are not applicable 
to new plants unless it can be justified for 
animal welfare reasons.  
May not be applicable to naturally 
ventilated plants located in warm climates 
and to existing plants with forced 
ventilation for weaners and fattening pigs.  
BAT 30.a7 may require large space 
availability. 

728 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Technique (1) 

8.  Straw flow system (in case of a 

solid concrete floor). 
9.  Convex floor and separated 

manure and water channels (in 
case of partly slatted pens). 

10.  Littered pens with combined 

manure generation (slurry and 
solid manure). 

11.  Feeding/lying boxes on solid 
floor (in case of litter-based 
pens). 

12.  Manure pan (in case of a fully 

or partly slatted floor). 

13.  Manure collection in water. 

14.  V-shaped manure belts (in case 

of partly slatted floor). 
15.  A combination of water and 

manure channels (in case of a 
fully slatted floor). 

Chapter 5 

Applicability 

May not be generally applicable to 
existing plants due to technical and/or 
economic considerations. 

Animal 
category 
Weaners 
Fattening pigs 
Weaners 

Fattening pigs 

Farrowing sows 

Mating and 
gestating sows 

Not applicable to existing plants without 
solid concrete floors. 

Farrowing sows  Generally applicable. 

Weaners 
Fattening pigs 

Fattening pigs 

Farrowing sows 

May not be generally applicable to 
existing plants due to technical and/or 
economic considerations. 

Not applicable to cold climates. 
May not be generally applicable to 
existing plants due to technical and/or 
economic considerations. 

Not applicable when: 
- heat reuse is not possible;  
- litter is used.  

16.  Littered external alley (in case 
of a solid concrete floor). 

Fattening pigs 

b  Slurry cooling. 

All pigs 

Use of an air cleaning system, such 
as:  
1.  Wet acid scrubber;  
2.  Two-stage or three-stage air 

c 

cleaning system;  

3.   Bioscrubber (or biotrickling 

filter). 

All pigs 

May  not  be  generally  applicable  due  to 
the high implementation cost. 
Applicable to existing plants only where a 
centralised ventilation system is used.  

d  Slurry acidification. 

All pigs 

Generally applicable. 

e 

Use of floating balls in the manure 
channel. 

Fattening pigs 

Not applicable to plants equipped with 
pits that have slanted walls and to plants 
that apply slurry removal by flushing. 

(1) A description of the techniques is given in Sections 5.4.11 and 5.4.12. 

Intensive Rearing of Poultry or Pigs 

729 

 
 
 
 
Chapter 5 

Table 5.4:  BAT-AEL for ammonia emissions to air from each pig house 

Parameter 

Animal category 

Ammonia expressed as NH3 

Mating and gestating sows 

Farrowing sows (including 
piglets) in crates 

Weaners 

Fattening pigs 

BAT-AEL (1)  
(kg NH3/animal place/year) 
0.2–2.7 (2) (3) 

0.4–5.6 (4) 

0.03–0.53 (5) (6) 

0.1–2.6 (7) (8) 

(1) The lower end of the range is associated with the use of an air cleaning system.  
(2) For existing plants using a deep pit in combination with nutritional management techniques, the upper end of the 

BAT-AEL is 4.0 kg NH3/animal place/year.  

(3) For plants using BAT 30.a6, 30.a7 or 30.a11, the upper end of the BAT-AEL is 5.2 kg NH3/animal place/year.  
(4) For existing plants using BAT 30.a0 in combination with nutritional management techniques, the upper end of the 

BAT-AEL is 7.5 kg NH3/animal place/year.  

(5) For existing plants using a deep pit in combination with nutritional management techniques, the upper end of the 

BAT-AEL is 0.7 kg NH3/animal place/year.  

(6) For plants using BAT 30.a6, 30.a7 or 30.a8, the upper end of the BAT-AEL is 0.7 kg NH3/animal place/year. 
(7) For existing plants using a deep pit in combination with nutritional management techniques, the upper end of the 

BAT-AEL is 3.6 kg NH3/animal place/year.  

(8)  For  plants  using  BAT 30.a6,  30.a7,  30.a8  or  30.a16,  the  upper  end  of  the  BAT-AEL  is  5.65  kg  NH3/animal 

place/year. 

The  BAT-AELs  may  not  be  applicable  to  organic  livestock  production.  The  associated 
monitoring is in BAT 25. 

730 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 5 

5.3  BAT conclusions for the intensive rearing of poultry  

5.3.1 

Ammonia emissions from poultry houses 

5.3.1.1 

Ammonia emissions from houses for laying hens, broiler breeders 
or pullets 

BAT 31. 
In order to reduce ammonia emissions to air from each house for laying hens, 
broiler  breeders  or  pullets,  BAT  is  to  use  one  or  a  combination  of  the  techniques  given 
below. 

a 

b 

Technique (1) 
Manure  removal  by  belts  (in  case  of 
enriched  or  unenriched  cage  systems)  with 
at least: 
- one removal per week with air drying; or 
- two removals per week without air drying. 
In case of non-cage systems: 
0.  Forced  ventilation  system  and  infrequent 
manure removal (in case of deep litter with a 
manure pit) only if used in combination with 
an additional mitigation measure, e.g.: 
- achieving a high dry matter content of the 
manure; 
- an air cleaning system. 

1.  Manure belt or scraper (in case of deep 

litter with a manure pit). 

2.  Forced  air  drying  of  manure  via  tubes 
(in case of deep litter with a manure pit) 
3.  Forced  air  drying  of  manure  using 
perforated  floor  (in  case  of  deep  litter 
with a manure pit). 

4.  Manure belts (in case of aviary). 

Applicability 

Enriched  cage  systems  are  not  applicable  to 
pullets and broiler breeders. 
Unenriched  cage  systems  are  not  applicable  to 
laying hens. 

Not  applicable  to  new  plants,  unless  combined 
with an air cleaning system. 

Applicability to existing plants may be limited by 
the  requirement  for  a  complete  revision  of  the 
housing system.  
The technique can be applied only to plants with 
sufficient space underneath the slats. 

Due to high implementation costs, applicability to 
existing plants may be limited. 

Applicability  to  existing  plants  depends  on  the 
width of the shed. 

5.  Forced  drying  of  litter  using  indoor  air 

(in case of solid floor with deep litter). 

Generally applicable. 

Use of an air cleaning system, such as:  
1.  Wet acid scrubber;  
2.  Two-stage  or  three-stage  air  cleaning 

c 

system;  

3.  Bioscrubber (or biotrickling filter). 

May  not  be  generally  applicable  due  to  the  high 
implementation cost.  
Applicable  to  existing  plants  only  where  a 
centralised ventilation system is used.  

(1) A description of the techniques is given in Sections 5.4.11 and 5.4.13.1. 

Table 5.5:  BAT-AELs for ammonia emissions to air from each house for laying hens 

Parameter 

Type of housing 

Ammonia  expressed  as 
NH3 
(1) For existing plants using a forced ventilation system and an infrequent manure removal (in case of deep litter 
with  a  manure  pit),  in  combination  with  a  measure  achieving  a  high  dry  matter  content  of  the  manure,  the 
upper end of the BAT-AEL is 0.25 kg NH3/animal place/year.  

Cage system 
Non-cage system 

BAT-AEL  
(kg NH3/animal place/year)  
0.02–0.08 
0.02–0.13 (1) 

The  associated  monitoring  is  in  BAT 25.  The  BAT-AEL  may  not  be  applicable  to  organic 
livestock production. 

Intensive Rearing of Poultry or Pigs 

731 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

5.3.1.2 

Ammonia emissions from houses for broilers 

BAT 32. 
BAT is to use one or a combination of the techniques given below. 

In  order  to  reduce  ammonia  emissions  to  air  from  each  house  for  broilers, 

a 

b 

c 

d 

e 

f 

Technique (1) 
Forced  ventilation  and  a  non-leaking 
drinking  system  (in  case  of  solid  floor 
with deep litter). 

Forced  drying  system  of 
litter  using 
indoor air (in case of solid floor with deep 
litter). 

Natural  ventilation,  equipped  with  a  non-
leaking  drinking  system  (in  case  of  solid 
floor with deep litter). 

Litter  on  manure  belt  and  forced  air 
drying (in case of tiered floor systems). 

Heated and cooled littered floor (in case 
of combideck systems). 

Use of an air cleaning system, such as:  

1.  Wet acid scrubber; 
2.  Two-stage or three-stage air 

cleaning system; 

3.  Bioscrubber (or biotrickling 

filter). 

Applicability 

Generally applicable. 

For  existing  plants,  the  applicability  of  forced  air 
drying systems depends on the height of the ceiling. 
Forced  air  drying  systems  may  not  be  applicable  to 
warm climates, depending on the indoor temperature. 
Natural  ventilation  is  not  applicable  to  plants  with  a 
centralised ventilation system. 
Natural  ventilation  may  not  be  applicable  during  the 
initial  stage  of  rearing  of  broilers  and  due  to  extreme 
climate conditions. 
For  existing  plants,  the  applicability  depends  on  the 
height of the side walls.  
For  existing  plants,  the  applicability  depends  on  the 
possibility to install closed underground storage for the 
circulating water. 

May  not  be  generally  applicable  due  to  the  high 
implementation cost. 
Applicable to existing plants only where a centralised 
ventilation system is used. 

(1) A description of the techniques is given in Sections 5.4.11 and 5.4.13.2.  

Table 5.6:  BAT-AEL  for  ammonia  emissions  to  air  from  each  house  for  broilers  with  a  final 

weight of up to 2.5 kg 

Parameter 

BAT-AEL (1) (2)  
(kg NH3/animal place/year) 
0.01–0.08 

Ammonia expressed as NH3 
(1) The BAT-AEL may not be applicable to the following types of farming: extensive indoor, free-range, 
traditional free-range and free-range–total freedom, as defined in Commission Regulation (EC) No 
543/2008 of 16 June 2008 laying down detailed rules for the application of Council Regulation (EC) 
No 1234/2007 as regards the marketing standards for poultrymeat (OJ L 157, 17.6.2008, p. 46). 

(2) The lower end of the range is associated with the use of an air cleaning system. 

The  associated  monitoring  is  in  BAT 25.  The  BAT-AEL  may  not  be  applicable  to  organic 
livestock production. 

732 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
5.3.1.3 

Ammonia emissions from houses for ducks 

BAT 33. 
ducks, BAT is to use one or a combination of the techniques given below. 

In  order  to  reduce  ammonia  emissions  to  air  from  each  animal  house  for 

Chapter 5 

Technique (1) 
One  of  the  following  techniques  using 
natural or forced ventilation:  

Applicability 

a 

b 

1.  Frequent  litter  addition  (in  case  of 
solid  floor  with  deep  litter  or  deep 
litter combined with slatted floor). 

For  existing  plants  with  deep  litter  combined  with 
slatted  floor  the  applicability  depends  on  the  design 
of the existing structure. 

2.  Frequent manure removal (in case of 

fully slatted floor). 

Only  applicable  to  the  rearing  of  Barbary/Muscovy 
ducks (Cairina Moschata), for sanitary reasons.  

Use of an air cleaning system, such as:  
1.  Wet acid scrubber;  
2.  Two-stage or three-stage air cleaning 

system;  

3.   Bioscrubber (or biotrickling filter). 

May  not  be  generally  applicable  due  to  the  high 
implementation cost. 
Applicable to existing plants only where a centralised 
ventilation system is used. 

(1) A description of the techniques is given in Sections 5.4.11 and 5.4.13.3.  

5.3.1.4 

Ammonia emissions from houses for turkeys 

BAT 34. 
turkeys, BAT is to use one or a combination of the techniques given below. 

In  order  to  reduce  ammonia  emissions  to  air  from  each  animal  house  for 

Technique (1) 

a 

b 

Natural or forced ventilation with a non-
leaking drinking system (in case of solid 
floor with deep litter). 

Use of an air cleaning system, such as:  
1.  Wet acid scrubber; 
2.  Two-stage  or  three-stage  air  cleaning 
system; 
3. Bioscrubber (or biotrickling filter). 

Applicability 
Natural  ventilation  is  not  applicable  to  plants  with  a 
centralised ventilation system. 
Natural ventilation  may not be  applicable during the 
initial  stage  of  rearing  or  due  to  extreme  climate 
conditions. 

May  not  be  generally  applicable  due  to  the  high 
implementation cost. 
Applicable to existing plants only where a centralised 
ventilation system is used. 

(1) A description of the techniques is given in Sections 5.4.11 and 5.4.13.4.  

Intensive Rearing of Poultry or Pigs 

733 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

5.4  DESCRIPTION OF TECHNIQUES 

5.4.1 

Techniques for reducing emissions from waste water  

Technique 

Minimise use of water. 

Segregate  rainwater  from  waste 
water 
require 
treatment. 

streams 

that 

Treat waste water. 

Landspreading of waste water e.g. 
by using an irrigation system such 
as  sprinkler,  travelling  irrigator, 
tanker, umbilical injector. 

Description 
The  volume  of  waste  water  can  be  reduced  by  using  techniques 
such  as  pre-cleaning  (e.g.  mechanical  dry  cleaning)  and  high 
pressure cleaning. 

Segregation is carried out by implementing separate collection in 
the form of properly designed and maintained drainage systems.  

Treatment  can  be  performed  by  sedimentation  and/or  biological 
treatment.  For  waste  water  with  a  low  pollutant  load,  treatment 
can  be  carried  out  by  means  of  swales,  ponds,  constructed 
wetlands,  soakaways,  etc.  A  first  flush  system  can  be  used  for 
separation before biological treatment. 
Waste  water  streams  can  be  settled,  e.g.  in  tanks  or  lagoons, 

before  landspreading.  The  resulting  solid  fraction  can  also  be 

landspread. The water can be pumped from the stores and brought 
into a pipeline that goes to e.g. a sprinkler or travelling irrigator, 
which  landspreads  the  water  at  a  low  application  rate.  Irrigation 
can  also  be  carried  out  using  equipment  with  controlled 
application  to  ensure  a  low  trajectory  (low  spread  pattern)  and 
large droplets. 

5.4.2 

Techniques for efficient use of energy 

Technique 

Optimisation of heating/cooling and 
ventilation systems and 
management, especially where air 
cleaning systems are used. 

Insulation of walls, floors and/or 
ceilings of housing.  

the  air  flow,  while 

fans  controlled  according 

Description 
This  takes  into  account  animal  welfare  requirements  (e.g. 
concentration  of  air  pollutants,  appropriate  temperatures),  and 
can be obtained through several measures: 
-  automation  and  minimisation  of 
maintaining thermal comfort zone for the animals; 
- fans with the lowest possible specific power consumption; 
- flow resistance is kept as low as possible;  
- frequency converters and electronically commutated motors; 
-  energy-saving 
concentration in the housing; 
-  correct  distribution  of  heating/cooling  and  ventilation 
equipment, temperature sensors and separate heated areas. 
Insulation  material  can  be  naturally  impermeable  or  provided 
with an impermeable coating. Permeable materials are provided 
with a vapour barrier installed, as humidity is a major cause of 
insulation material deterioration. 
A  variant  of  insulation  material  for  poultry  farms  can  be  heat-
reflecting  membranes,  consisting  of  laminated  plastic  foils  to 
seal off housing from air leakage and humidity. 
More energy-efficient lighting can be attained by:  
i.  Replacing  conventional  tungsten  light  bulbs  or  other  low 
efficiency  light  bulbs  with  more  energy-efficient  lights 
such as fluorescent, sodium, and LED lights; 

the  CO2 

to 

Use of energy-efficient lighting. 

ii.  Using  devices  to  adjust  the  frequency  of  micro  flashes, 
dimmers to adjust artificial lighting, sensors or room entry 
switches to control the lighting;  

iii.  Allowing more natural light to enter, e.g. by using vents or 
roof  windows.  Natural  light  has  to  be  balanced  with 
potential heat losses; 

iv.  Applying  lighting  schemes,  using  a  variable  lighting 

734 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Technique 

Description 

period. 

Chapter 5 

Use of heat exchangers. One of the 
following systems may be used: 
- air-air;  
- air-water;  
- air-ground.  

Use of heat pumps for heat 
recovery.  

Heat recovery with heated and 
cooled littered floor (combideck 
system).  

Apply natural ventilation. 

In an air-air heat exchanger, the incoming air absorbs heat from 
the exhaust air from the plant. It can be composed of plates of 
anodised aluminium or PVC tubes. 
In the air-water heat exchanger, water flows through aluminium 
fins  located  in  the  exhaust  ducts  and  absorbs  heat  from  the 
exhausted air.  
In the air-ground heat exchanger, fresh air is circulated through 
buried pipes (e.g. at a depth of about 2 metres) taking advantage 
of the low seasonal temperature variation of soil. 
Heat is absorbed from various media (water, slurry, ground, air, 
etc.) and transferred to another location, via a fluid circulated in 
a  sealed  circuit  using  the  reverse  refrigeration  cycle  principle. 
The  heat  can  be  used  to  produce  sanitised  water  or  to  feed  a 
heating system or a cooling system. 
The  technique  can  absorb  heat  from  various  circuits,  such  as 
slurry  cooling  systems,  geothermal  energy,  scrubbing  water, 
slurry  biological  treatment  reactors,  or  biogas  engine  exhaust 
gases. 
A closed water circuit is installed below the floor and another is 
built at a deeper level for storing the excess heat or to return it 
to  the  poultry  house  when  needed.  A  heat  pump  connects  the 
two water circuits. 
At the beginning of the rearing period, the floor is heated with 
the  stored  heat  in  order  to  keep  the  litter  dry  by  avoiding 
moisture  condensation;  during  the  second  rearing  cycle,  birds 
produce an excess of heat that is preserved in the storing circuit 
while cooling down the  floor  which reduces the breakdown of 
uric acid by reducing microbial activity. 
Free ventilation in the animal house is caused by thermal effects 
and/or wind flow. The animal houses can have openings in the 
ridge  and,  if  necessary,  also  on  the  gable  sides  in  addition  to 
controllable  openings  in  the  side  walls.  The  openings  can  be 
equipped with wind protection nets. Fan assistance can be used 
during hot weather.  

5.4.3 

Techniques for reducing dust emissions 

Technique 

Water fogging  

Ionisation 

Oil spraying 

Description 
Water is sprayed by nozzles at high pressure to produce fine droplets 
that  absorb  heat  and  fall  by  gravity  to  the  floor,  moistening  dust 
particles  that  become  heavy  enough  to  drop  as  well.  Wet  or  moist 
litter needs to be avoided. 
An electrostatic field is created in the house to produce negative ions. 
Circulating airborne dust particles are charged by free negative ions; 
particles are collected on the floor and room surfaces by gravitational 
force and electrostatic field attraction. 
Pure vegetable oil is sprayed by nozzles inside the house. A mixture 
of water and around 3 % vegetable oil can be also used for spraying. 
Circulating dust particles are bound to the oil drops and collected in 
the litter. A thin layer of vegetable oil is also applied on the litter to 
prevent dust emissions. Wet or moist litter needs to be avoided. 

Intensive Rearing of Poultry or Pigs 

735 

 
 
 
 
 
Chapter 5 

5.4.4 

Techniques for reducing odour emissions  

Technique 

Ensure  adequate  distances between the 
plant/farm and the sensitive receptors. 

Cover  slurry  or  solid  manure  during 
storage. 
Minimise stirring of slurry. 
Aerobic  digestion  (aeration)  of  liquid 
manure/slurry. 
Compost solid manure. 
Anaerobic digestion. 
Band spreader, shallow injector or deep 
injector for slurry landspreading. 
Incorporate  manure 
possible. 

soon 

as 

as 

Description 
At  the  planning  stage  of  the  plant/farm,  adequate  distances 
between  the  plant/farm  and  the  sensitive  receptors  are 
ensured  by  applying  minimum  standard  distances  or 
performing  dispersion  modelling  to  predict/simulate  odour 
concentration in surrounding areas. 
See description in Section 5.4.5 for solid manure. 
See description in Section 5.4.6 for slurry. 
See description in Section 5.4.6.1. 

See description in Section 5.4.7. 

See descriptions in Section 5.4.8.1. 

See descriptions in BAT 22. 

5.4.5 

Techniques for reducing emissions from the storage of solid 
manure  

Technique 

Store dried solid manure in a barn.  

Use a concrete silo for storage. 

Store 
solid 
solid  manure  on 
impermeable floor equipped with a 
drainage  system  and  a  collection 
tank for run-off. 

Select  a  storage  facility  with  a 
sufficient  capacity 
the 
manure  during  periods  in  which 
landspreading is not possible.  

to  hold 

Store  solid  manure  in  field  heaps 
placed  away  from  surface  and/or 
underground  watercourses  which 
liquid run-off might enter. 

the 

ratio  between 

Reduce 
the 
emitting  surface  area  and  volume 
of the manure heap.  

Cover solid manure heaps.  

Description 
The barn is usually a simple  construction  with an impermeable 
floor  and  a  roof,  with  sufficient  ventilation  to  avoid  anaerobic 
conditions  and  an  access  door  for  transport.  Dried  poultry 
manure (e.g. litter from broilers and laying hens, air-dried laying 
hen  excreta  collected  on  belts)  is  transported  by  belts  or  front-
end loaders from the poultry  house  to the  barn  where  it can be 
stored for a long period of time without the risk of remoistening. 
A  foundation  slab  of  water-impermeable  concrete  that  can  be 
combined with walls on three sides and with a cover e.g. roofing 
over the manure platform, UV-stabilised plastic, etc. The floor is 
sloped  (e.g.  2 %)  towards  a  front  drain  gutter.  Liquid  fractions 
and  any  run-off  caused  by  rainfall  are  collected  in  a  leak-tight 
concrete pit and handled afterwards.  

The  storage  is  equipped  with  a  solid  impermeable  floor,  a 
drainage  system  such  as  drains,  and  connected  to  a  tank  for 
collection of liquid fractions and any run-off caused by rainfall. 

The  periods  when  manure  landspreading  is  allowed  depend  on 
the local climatic conditions and legislation, etc.; thus, requiring 
a storage area with a suitable capacity. 
The available capacity also allows the landspreading time to be 
aligned to the nitrogen requirements of the crops. 
Solid manure is stacked directly on the soil in the field prior to 
landspreading over a limited period of time (e.g. for a few days 
or several weeks). The storage location is changed at least every 
year  and  situated  as  far  as  possible  from  surface  and 
groundwater. 

Manure  can  be  compacted  or  a  three-sided  wall  store  can  be 
used.  

Materials such as UV-stabilised plastic covers, peat, sawdust, or 
wood chips can be used. Tight covers decrease air exchange and 
aerobic  decomposition  in  the  manure  heap,  resulting  in  a 
reduction of emissions to air. 

736 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
5.4.6 

Techniques for reducing emissions from slurry storage 

5.4.6.1 

Techniques for reducing ammonia emissions from slurry stores 
and earth-banked storage 

Chapter 5 

Technique 

the 

Reduce 
ratio  between 
emitting  surface  area  and 
volume of the slurry store. 

the 
the 

Reduce  wind  velocity  and  air 
exchange  on  the  slurry  surface  by 
operating at a lower level of fill. 

Minimise stirring of slurry. 

Rigid cover. 

Flexible covers. 

Floating covers. 

Natural crust. 

Straw.  

Plastic pellets. 

Light bulk materials. 

Description 
For  rectangular  slurry  stores,  the  proportion  of  height  and 
surface  area  is  equivalent  to  1:30–50.  For  circular  stores, 
favourable  container  dimensions  are  obtained  with  a  height–
diameter ratio of 1:3 to 1:4.  
The side walls of the slurry store may be increased in height. 
Increasing  the  freeboard  (the  length  between  the  slurry  surface 
and  the  upper  rim  of  the  slurry  store)  of  the  uncovered  store 
provides a windshield effect. 
Keep the stirring of slurry to a minimum. This practice involves: 
- filling the store below surface level;  
- discharging as close as possible to the base of the store; 
- avoiding unnecessary homogenisation and circulation of slurry 
(before emptying the slurry store). 
A roof or a lid which can be made of concrete, fibreglass panels 
or polyester sheets with a flat deck or conical shape, applied to 
concrete  or  steel  tanks  and  silos.  It  is  well-sealed  and  'tight'  to 
minimise  air  exchange  and  to  prevent  rain  and  snow  from 
entering. 
Tent Cover: A cover with a central supporting pole and spokes 
radiating  from  the  tip.  A  fabric  membrane  is  spread  over  the 
spokes and tied to a rim brace. Non-covered openings are  kept 
to a minimum. 
Dome-shaped  cover:  A  cover  with  a  curved  structural  frame 
installed over round stores with the use of steel components and 
bolted joints. 
Flat cover:  A cover consisting of a flexible and self-supporting 
composite material held by plugs on a metal structure. 

A crust layer can be  formed  on the surface  of slurry that  has a 
sufficient dry  matter (DM) content (at least  2 %)  depending on 
the nature of the slurry solids. In order to be effective, the crust 
must  be  thick,  not  be  disturbed  and  cover  the  whole  slurry 
surface. The store is filled from below the surface once the cover 
is formed to avoid breaking it up. 
Chopped straw is added to the slurry and a straw-induced crust 
is formed. This generally works well for DM higher than 4–5 %. 
A  layer  thickness  of  at  least  10  cm  is  recommended.  Air 
blowing  can  be  reduced  by  adding  straw  at  the  time  of  slurry 
addition.  Straw  layers  may  need  to  be  partially  or  completely 
renewed  during  the  year.  The  store  is  filled  from  below  the 
surface once the cover is formed to avoid breaking it up. 
Polystyrene balls of 20 cm in diameter and 100 g in weight are 
used  to  cover  the  slurry  surface.  A  regular  replacement  of 
deteriorated  elements  and  a  refill  for  uncovered  spots  are 
necessary. 
Materials  such  as  LECA  (Light  expanded  clay  aggregates), 
LECA based products, perlite or zeolite are added to the  slurry 
surface to form a floating layer. A floating layer of 10–12 cm is 
recommended.  A  thinner  layer  can  be  effective  for  smaller 
LECA particles. 

Intensive Rearing of Poultry or Pigs 

737 

 
 
 
 
 
Chapter 5 

Technique 

Floating flexible covers. 

Geometrical plastic tiles. 

Air-inflated cover. 

Flexible plastic sheets. 

Description 
Plastic floating covers (e.g. blankets, canvas, films) rest over the 
slurry surface. Floats and tubes are installed to keep the cover in 
place,  while  maintaining  a  void  beneath  the  cover.  This 
technique  can  be  combined  with  stabilising  elements  and 
structures  to  allow  vertical  movements.  Venting  is  needed  as 
well as removal of rainwater that gathers on top. 
Floating  hexagonal  plastic  bodies  are  automatically  distributed 
on the slurry surface. About 95 % of the surface can be covered. 
A  cover  made  of  PVC  fabric  supported by  an  inflatable pocket 
that floats over the slurry. The fabric is fixed by guy ropes to a 
peripheral metal structure. 
Impermeable  UV-stabilised  plastic  sheets  (e.g.  HDPE)  are 
secured at the bank tops and supported on floats.  This prevents 
the  cover  from  turning  during  manure  mixing  and  being  lifted 
off by wind. The covers can also be fitted with collection piping 
for  removal  of  gases,  other  maintenance  openings  (e.g.  for  the 
use  of  homogenisation  equipment)  and  a  system  for  rainwater 
collection and removal.  

5.4.6.2 

Techniques for reducing emissions to soil and water from slurry 
stores  

Technique 

stores 

that  are  able 

to 
Use 
withstand  mechanical,  chemical 
and thermal influences. 
Select  a  storage  facility  with  a 
sufficient  capacity 
the 
manure  during  periods  in  which 
landspreading is not possible. 

to  hold 

Description 
Appropriate  concrete  mixtures  and,  in  many  cases,  lining  on 
concrete  walls  or  impermeable  layers  on  steel  sheets  can  be 
applied. 

See Section 5.4.5. 

5.4.7 

Techniques for on farm manure processing  

Technique 

Mechanical separation of slurry. 

Anaerobic digestion of manure in a 
biogas installation. 

Use of an external tunnel for 
manure drying. 

to  serve  energy  generation 

Description 
Separation of liquid and solid fractions with different dry matter 
content,  using  e.g.  screw  press  separators,  decanter-centrifuge 
separators,  separation  by  sieves  and  filter  pressing.  Separation 
can be enhanced by coagulation-flocculation of solid particles. 
Anaerobic  microorganisms  decompose  the  organic  matter  of 
manure in a closed reactor in the absence of oxygen. Biogas is 
produced  and  collected 
i.e. 
production of heat,  combined heat and power, and/or transport 
fuel. Some of the heat produced is recycled in the process. The 
stabilised  residue  (digestate)  can  be  used  as  fertiliser  (with 
sufficiently solid digestate after composting).  
Solid  manure  can  be  co-digested  with  slurry  and/or  other  co-
substrates, while ensuring a dry matter content lower than 12 %. 
Manure is collected from the laying hen houses and removed by 
belts  that  convey  it  outdoors  to  a  dedicated  closed  structure, 
containing a series of perforated overlapping belts that form the 
tunnel. Warm air is blown through the belts, drying the manure 
in  about  two  or  three  days.  The  tunnel  is  ventilated  with  air 
extracted from the laying hens' house. 

738 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Technique 

Aerobic digestion (aeration) of 
slurry.  

Nitrification-denitrification of 
slurry. 

Composting of solid manure. 

Chapter 5 

Description 
The  biological  decomposition  of  organic  matter  under  aerobic 
conditions.  Stored  slurry  is  aerated  by  means  of  submerged  or 
floating  aerators  in  a  continuous  or  batch  process.  Operating 
variables  are  controlled  to  prevent  nitrogen  removal,  such  as 
keeping slurry agitation as low as possible. The residue can be 
used as fertiliser (composted or not) after concentration. 
Part  of  the  organic  nitrogen  is  transformed  into  ammonium. 
Ammonium  is  oxidised  by  nitrifying  bacteria  into  nitrite  and 
nitrate.  By  applying  anaerobic  periods,  the  nitrate  can  be 
transformed  into  N2  in  the  presence  of  organic  carbon.  In  a 
secondary basin, the sludge settles, with part of it being reused 
in  the  aeration  basin.  The  residue  can  be  used  as  fertiliser 
(composted or not) after concentration.  
The  controlled  aerobic  decomposition  of  solid  manure  by 
microorganisms  producing 
(compost) 
a 
sufficiently  stable  for  transport,  storage  and  landspreading. 
Odour,  microbial  pathogens  and  water  content  of  manure  are 
reduced. The solid fraction of the slurry can also be composted. 
The  supply  of  is  achieved  by  mechanical  reversal  of  the 
windrows  or  by  forced  aeration  of  the  heaps.  Drums  and 
composting tanks can also be used. Biological inoculum, green 
residues  or  other  organic  wastes  (e.g.  digestate)  can  be  co-
composted with solid manure.  

final  product 

5.4.8 

Techniques for manure landspreading 

5.4.8.1 

Techniques for slurry landspreading 

Technique 

Slurry dilution 

Low-pressure  water 
system 

irrigation 

Band spreader (trailing hose) 

Band spreader (trailing shoe) 

Shallow injector (open slot) 

Deep injector (closed slot) 

Slurry acidification 

Description 
Dilution  rate  of  water:slurry  is  from  1:1  up  to  50:1.  The  dry 
matter  content  of  diluted  slurry  is  less  than  2 %.  The  clarified 
liquid fraction from the mechanical separation of slurry and the 
digestate from anaerobic digestion can be used as well.  

Diluted slurry is injected into the irrigation water pipeline and is 
pumped  under  low  pressure  to  the  irrigation  system  (e.g. 
sprinkler or travelling irrigator). 

A  series of  flexible  hoses  hang  from a  wide  bar  mounted onto 
the slurry trailer. The hoses discharge slurry at ground level in 
wide parallel bands. Application between the rows of a growing 
arable crop is feasible.  
Slurry  is  discharged  through  rigid  pipes  which  terminate  in 
metal 'shoes', designed to apply slurry directly in narrow bands 
to  the  soil  surface  and  below  the  crop  canopy.  Some  types  of 
trailing shoes are designed to cut a shallow slit in the soil to aid 
infiltration. 
Tines or disc harrows are used to cut vertical slots (typically 4–
6  cm  deep)  in  the  soil,  forming  grooves  into  which  slurry  is 
deposited. The injected slurry is fully or partially placed below 
the soil surface and grooves will normally be open after slurry 
application. 
Tines or disc harrows are used to cultivate the soil and deposit 
slurry into it, before covering the slurry fully by means of press 
wheels  or  rollers.  The  depth of  the  closed  slot  ranges  between 
10 cm and 20 cm. 
See Section 5.4.12.3.  

Intensive Rearing of Poultry or Pigs 

739 

 
 
 
 
 
 
 
Chapter 5 

5.4.9 

Techniques for monitoring 

5.4.9.1 

Techniques for monitoring N and P excretion 

Technique  

Description 
The mass balance is calculated for each animal category reared 
on the farm, coinciding  with  the  end of a rearing cycle, on the 
basis of the following equations: 

Nexcreted = Ndiet – Nretention 
Pexcreted = Pdiet – Pretention 

Ndiet is based on the amount  of feed  ingested and on the crude 
protein content of the diet. Pdiet is based on the amount of feed 
ingested  and  on  the  total  phosphorus  content  of  the  diet.  The 
crude protein and the total phosphorus contents can be obtained 
by one of the following methods: 
 

in  the  case  of  external  feed  supply:  in  the  accompanying 
documentation; 
in  the  case  of  self-processing  of  feed:  by  sampling  of 
feedstuff compounds from the silos or the feeding system 
for  analysing  the  total  content  of  phosphorus  and  crude 
accompanying 
protein 
documentation or using standard values of total content of 
phosphorus and crude protein of the feedstuff compounds. 

alternatively, 

the 

or, 

in 

Calculation  by  using  a  mass 
balance of nitrogen and phosphorus 
based  on  feed  intake,  crude  protein 
content of the diet, total phosphorus 
and animal performance. 

 

Nretention  and  Pretention  can  be  estimated  by  one  of  the  following 
methods: 
 
 

statistically derived equations or models; 
standard retention factors for the nitrogen and phosphorus 
contents  of  the  animal  (or  of  eggs,  in  the  case  of  laying 
hens); 
analysis  for  nitrogen  and  phosphorus  contents  of  a 
representative sample of the animal (or of eggs, in the case 
of laying hens). 

 

by 

Estimation 
using  manure 
analysis  for  total  nitrogen  and  total 
phosphorus contents. 

The  mass  balance  considers  especially  any  significant  changes 
to the diet commonly applied (e.g. change of a compound feed). 
The total content of nitrogen and phosphorus of a representative 
composite  sample  of  manure  is  measured  —  and  the  total 
excretion of  nitrogen and phosphorus is estimated  — based on 
records for the volume (for slurry) or weight (for solid manure) 
of  manure.  For  solid  manure  systems,  the  nitrogen  content  of 
litter is also considered. 
In order for the composite sample to be representative, samples 
must be taken from at least 10 different places and/or depths to 
make  the  composite  sample.  In  the  case  of  poultry  litter,  the 
bottom of the litter is sampled. 

740 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
5.4.9.2 

Techniques for ammonia and dust monitoring 

Chapter 5 

Technique  

Estimation  by  using  a  mass 
balance  based  on  the  excretion 
and  the  total  (or  ammoniacal) 
nitrogen present at each manure 
management stage. 

Description 
Ammonia emissions are estimated based on the amount of nitrogen 
excreted  by  each  animal  category  and  using  the  total  nitrogen  (or 
the  total  ammoniacal  nitrogen  –  TAN)  flow  and  the  volatilisation 
coefficients  (VC)  over  each  manure  management  stage  (housing, 
storage, landspreading). 
The  equations  applied  for  each  of  the  manure  management  stages 
are: 
Ehousing = Nexcreted · VChousing 
Estorage = Nstorage · VCstorage 
Espreading = Nspreading · VCspreading 

where: 

E  is  the  annual  NH3  emission  from  the  animal  house,  manure 
storage or landspreading (e.g. in kg NH3/animal place/year). 
N is the annual total nitrogen or TAN excreted, stored or applied 
in 
in  kg  N/animal  place/year).  If 
appropriate, nitrogen additions (e.g. related to litter, recycling 
of  scrubbing  liquids)  and/or  nitrogen  losses  (e.g.  related  to 
manure processing) can be considered. 

landspreading  (e.g. 

VC is the volatilisation coefficient (dimensionless, related to the 
housing system,  manure storage or landspreading techniques) 
representing the proportion of TAN or total N emitted to air.  

and 

similar 

VC  are  derived  from  measurements  designed  and  performed 
according  to  a  national  or  an  international  protocol  (e.g.  VERA 
protocol)  and  validated  for  a  farm  with  an  identical  type  of 
technique 
conditions.  Alternatively, 
climatic 
information  to  derive  VC  can  be  taken  from  European  or  other 
internationally recognised guidance. 
The mass balance considers especially any significant change to the 
type of livestock reared at the farm and/or to the techniques applied 
for housing, storage and landspreading. 
Ammonia  (or  dust)  samples  are  taken  on  six  days,  as  a  minimum, 
distributed over one year. Sampling days are distributed as follows:  
- For animal categories  with  a stable emissions pattern (e.g. laying 
hens), the sampling days are randomly selected in every two-month 
period. The daily average is calculated as a mean over all sampling 
days. 
-  For  animal  categories  with  a  linear  increase  in  emissions  during 
the rearing cycle (e.g. fattening pigs), the sampling days are equally 
distributed over the growing period. In order to achieve this, half the 
measurements  are  performed  in  the  first  half  of  the  rearing  cycle, 
and  the  remainder  in  the  second  half  of  the  rearing  cycle.  The 
sampling  days  in  the  second  half  of  the  rearing  cycle  are  equally 
distributed  within  the  year  (same  number  of  measurements  per 
season). The daily average is calculated as a mean over all sampling 
days. 
-  For  animal  categories  with  an  exponential  increase  in  emissions 
(e.g.  broilers),  the  rearing  cycle  is  divided  into  three  periods  of 
equal length (same number of days). One measurement day falls in 
the  first  period,  two  measurements  in  the  second  period,  and  three 
measurements in the third period. In addition, sampling days in the 
third  period  of  the  rearing  cycle  are  equally  distributed  within  the 
year (same number of measurements per season). The daily average 
is calculated as the average of the three periodic means. 
Sampling is based on 24-hour sampling periods and is performed at 
the air inlet/outlet. Ammonia (or dust) concentration at the air outlet 
is  then  measured,  corrected  for  the  concentration  of  the  incoming 

(or 

and 

Calculation  by  measuring  the 
dust) 
ammonia 
the 
concentration 
ventilation 
ISO, 
international 
national 
standard  methods  or  other 
methods  ensuring  data  of  an 
equivalent scientific quality. 

rate  using 
or 

Intensive Rearing of Poultry or Pigs 

741 

 
 
 
Chapter 5 

Technique 

Estimation by using emission 
factors. 

Description 
air,  and  daily  ammonia  (or  dust)  emissions  are  derived  by 
measuring and multiplying the ventilation rate and the ammonia (or 
dust)  concentration.  From  the  daily  average  of  ammonia  (or  dust) 
emissions, the yearly average ammonia (or dust) emissions from an 
animal house can be calculated, if multiplied by 365 and corrected 
for any non-occupation periods. 
The ventilation rate, necessary to determine the emission mass flow, 
is  determined  either  by  calculation  (e.g.  fan  wheel  anemometer, 
records of ventilation control system) in forced ventilated houses, or 
by  means  of  tracer  gases  (excluding  the  use  of  SF6  and  any  gas 
containing  CFCs)  in  naturally  ventilated  houses  which  allow  a 
proper mixing of air. 
For plants  with  multiple air inlets and outlets, only those  sampling 
points  considered  representative  (in  terms  of  expected  mass 
emissions) of the plant are monitored. 
Ammonia (or dust) emissions are estimated on the basis of emission 
factors  derived  from  measurements  designed  and  performed 
according  to  a  national  or  an  international  protocol  (e.g.  VERA 
protocol) in a farm with an identical type of technique (related to the 
housing  system,  manure  storage  and/or  landspreading)  and  similar 
climatic  conditions.  Alternatively,  emission  factors  can  be  taken 
from European or other internationally recognised guidance. 
The  use  of  emission  factors  considers  especially  any  significant 
change  to  the  type  of  livestock  reared  at  the  farm  and/or  to  the 
techniques applied for housing, storage, landspreading. 

5.4.9.3 

Techniques for monitoring of air cleaning systems 

Technique 

a 

Verification  of 
the  air  cleaning 
system  performance  by  measuring 
ammonia,  odour  and/or  dust  under 
practical farm conditions, according 
to 
prescribed  measurement 
protocol  and  using  EN  standard 
methods  or  other  methods  (ISO, 
national  or  international)  ensuring 
data  of  an  equivalent  scientific 
quality. 

Control  of  the  effective  function  of 
the  air  cleaning  system  (e.g.  by 
continuously  recording  operational 
parameters or using alarm systems). 

Description 
The  verification  is  done  by  measurement  of  ammonia,  odour 
and/or  dust  in  the  inlet  and  outlet  air  and  of  all  additional 
parameters  relevant  for  operation  (e.g.  air  flow  rate,  pressure 
drop,  temperature,  pH  level,  conductivity).  Measurements  are 
performed  under  summer  climatic  conditions  (a  period  of  at 
least  eight  weeks  with  a  ventilation  rate  > 80 %  of  the 
maximum  ventilation  rate)  and  winter  climatic  conditions  (a 
period of at least eight weeks with a ventilation rate < 30 % of 
the maximum ventilation rate), with representative management 
and  full  capacity  of  the  housing  and  only  if  an  adequate  time 
period  (e.g.  four  weeks)  has  elapsed  after  the  last  change  of 
wash water. Different sampling strategies can be applied. 
Operation  of  an  electronic  logbook  in  order  to  record  all 
measuring  and  operational  data  over  a  period  of  1–5  years. 
Recorded parameters depend on the type of air cleaning system 
and may include: 
1.
pH and conductivity of scrubbing liquid;
2.
air flow and pressure drop of the abatement system;
3.
pump operating time;
4.
water and acid consumption.
Other parameters can be recorded manually. 

742 

Intensive Rearing of Poultry or Pigs 

5.4.10 

Nutritional management 

5.4.10.1 

Techniques for reducing nitrogen excreted 

Chapter 5 

the 

energy  needs 

Technique 
Reduce the crude protein content 
by using a N-balanced diet based 
on 
and 
digestible amino acids.  
Multiphase  feeding  with  a  diet 
the 
formulation 
specific 
the 
production period. 

adapted 
to 
requirements  of 

Addition  of  controlled  amounts 
of essential amino acids to a low 
crude protein diet. 

Use  of  authorised  feed  additives 
which 
total  nitrogen 
excreted. 

reduce 

Description 
Reduce  excesses  in  the  crude  protein  supply  by  ensuring  that  it 
does not exceed feeding recommendations. The diet is balanced to 
meet  the  animal  requirements  of  energy  and  digestible  amino 
acids. 

The feed mix matches the animal requirements more accurately in 
terms  of  energy,  amino  acids  and  minerals,  depending  on  the 
animal weight and/or production stage. 

A certain amount of protein-rich feedstuffs is substituted by low-
protein  feedstuffs,  in  order  to  further  reduce  the  crude  protein 
content. The diet is supplemented with synthetic amino acids (e.g. 
lysine,  methionine,  threonine,  tryptophan,  valine)  so  that  there  is 
no deficiency in the amino acid profile.  
Authorised  (according  to  Regulation  (EC)  N°  1831/2003  of  the 
European  Parliament  and  of 
substances, 
microorganisms  or  preparations  such  as  enzymes  (e.g.  NSP 
enzymes,  proteases)  or  probiotics  are  added  to  feed  or  water  in 
order  to  favourably  affect  feed  efficiency  e.g.  by  improving  the 
digestibility of feedstuffs or affecting the gastrointestinal flora.  

the  Council(1)) 

(1)  Regulation  (EC)  No  1831/2003  of  the  European  Parliament  and  of  the  Council  of  22  September  2003  on 
additives for use in animal nutrition (OJ L 268, 18.10.2003, p. 29). 

5.4.10.2 

Techniques for reducing phosphorus excreted 

Technique 
Multiphase  feeding  with  a  diet 
the 
formulation 
the 
specific 
production period. 

adapted 
to 
requirements  of 

Use  of  authorised  feed  additives 
which  reduce  total  phosphorus 
excreted (e.g. phytase).  

Description 

The feed consists of a mix matching the phosphorus supply to 
requirements  more  accurately 
the  phosphorus  animal 
depending on the animal weight and/or production stage. 

Authorised  (according  to  Regulation  (EC)  N°  1831/2003  of 
the  European  Parliament  and  of  the  Council)  substances, 
microorganisms  or  preparations  such  as  enzymes  (e.g. 
phytase)  are  added  to  feed  or  water  in  order  to  favourably 
affect  feed  efficiency  e.g.  by  improving  the  digestibility  of 
phytic  phosphorus 
the 
gastrointestinal flora.  

the  feedstuffs  or  affecting 

in 

Intensive Rearing of Poultry or Pigs 

743 

 
 
 
 
 
 
 
 
 
Chapter 5 

5.4.11 

Techniques to treat emissions to air from animal housing 

Technique 

Biofilter 

Bioscrubber 
filter) 

(or  biotrickling 

Dry filter 

Two-stage  or 
cleaning system 

three-stage  air 

Water scrubber 

Water trap 

Wet acid scrubber 

Description 
The exhaust air is led through a filter bed of organic material, such 
as  root  wood  or  wood  chips,  coarse  bark,  compost  or  peat.  The 
filter material is always kept moist by intermittent sprinkling of the 
surface. Dust particles and odorous air compounds are absorbed by 
the wet film and are oxidised or degraded by microorganisms living 
on the moistened litter material. 
A packed tower filter with inert packing material which is normally 
maintained continuously wet by sprinkling water. Air pollutants are 
absorbed  in  the  liquid  phase  and  subsequently  degraded  by 
microorganisms  settling  on  the  filter  elements.  An  ammonia 
reduction of between 70 % and 95 % can be achieved. 
The exhaust air is blown against a screen made of e.g. multi-layered 
plastic placed in front of the end wall ventilator. The passing air is 
subject  to  strong  changes  of  direction  causing  the  separation  of 
particles by centrifugal force.  
In a two-stage system, the first stage (wet acid scrubber) is usually 
combined  with  a  bioscrubber  (second  stage).  In  a  three-stage 
system,  a  first  stage  consisting  of  a  water  scrubber  is  usually 
combined  with  a  second  stage  (wet  acid  scrubber),  followed  by  a 
biofilter (third stage). An ammonia reduction of between 70 % and 
95 % can be achieved. 
The  exhaust  air  is  blown  through  a  packed  filter  medium  by 
transverse  flow.  Water  is  continuously  sprayed  on  the  packing 
material.  Dust  is  removed  and  settles  in  the  water  tank,  which  is 
emptied before refilling. 
The  exhaust  air  is  directed  by  ventilation  fans  down  onto  a  water 
bath  where  dust  particles  get  soaked.  The  flow  is  then  redirected 
180 ° upward. The water level is topped up regularly to compensate 
for evaporation. 
The exhaust air is forced through a filter (e.g. packed wall) where a 
circulating acid liquid (e.g. sulphuric acid) is sprayed. An ammonia 
reduction of between 70 % and 95 % can be achieved. 

5.4.12 

Techniques for pig houses 

5.4.12.1 

Description of floor types and techniques for reducing ammonia 
emissions in pig houses 

Type of floor 

Fully slatted floor 

Partly slatted floor 

Solid concrete floor 

Description 
A floor where the whole area is slatted using metal, concrete or 
plastic floor with openings that allows faeces and urine to drop 
into a channel or a pit beneath. 
A  floor  that  is  partly  solid  and  partly  slatted  using  metal, 
concrete  or  plastic  floor  with  openings  that  allows  faeces  and 
urine to drop into a channel or a pit beneath. Fouling of the solid 
floor is prevented by proper management of the  indoor climate 
parameters,  especially  under  hot  conditions,  and/or  by  proper 
design of the housing systems. 
A  floor  where  the  entire  area  consists  of  solid  concrete.  The 
floor can be covered  with litter (e.g. straw) to varying degrees. 
The floor is usually sloped to facilitate the drainage of urine.  

The floor types listed above are used in the described housing systems, when appropriate: 

744 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Technique 
A  deep  pit  (in  case  of  a  fully  or 
partly  slatted  floor)  only  if  used  in 
combination  with  an  additional 
mitigation measure, e.g.: 
-  a  combination  of  nutritional 
management techniques; 
- air cleaning system; 
- pH reduction of the slurry; 
- slurry cooling. 

A  vacuum  system  for  frequent 
slurry removal (in case of a fully or 
partly slatted floor). 

the  manure 
in 
Slanted  walls 
channel (in case of a fully or partly 
slatted floor). 

for 

A  scraper 
frequent  slurry 
removal (in case of a fully or partly 
slatted floor). 

Convex floor and separated manure 
and  water  channels  (in  case  of 
partly slatted pens). 

V-shaped  manure  belts  (in  case  of 
partly slatted floor). 

Reduced  manure  pit  (in  case  of 
partly slatted floor). 

Chapter 5 

Description 

Pens  are  equipped  with  a  deep  pit  below  the  slatted  floor  that 
allows for the storage of the slurry between infrequent removals. 
For  fattening  pigs,  an  overflow  manure  channel  can  be  used. 

Removal  of  slurry  for  landspreading  or  to  outdoor  store  takes 

place  as  frequent  as  possible  (e.g.  at  least  every  two  months) 
unless there are technical restrictions (e.g. storage capacity). 

Outlets  at  the  bottom  of  the  pit  or  channel  are  connected  to  a 
discharge  pipe  underneath  which  transfers  slurry  to  outdoor 
storage. Slurry is frequently discharged by opening a valve or a 
plug  in  the  main  slurry  pipe,  e.g.  once  or  twice  every  week;  a 
slight vacuum develops and allows the complete emptying of the 
pit  or  channel.  A  certain  depth  of  slurry  needs  to  be  obtained 
before  the  system  can  operate  properly  to  allow  the  vacuum  to 
be effective. 
The  manure  channel  creates  a  V  section  with  the  point  of 
discharge  at  the  bottom.  The  slope  and  the  smoothness  of  the 
surface facilitate the slurry discharge. Manure removal is carried 
out at least twice every week. 
There is a V-shaped channel with two inclined surfaces on each 
side  of  a  central  gutter,  where  urine  can  be  drained  to  a 
collection  pit  through  a  drain  in  the  bottom  of  the  manure 
channel.  From  the  pit,  the  solid  fraction  of  the  manure  is 
extracted frequently (e.g. daily) by a  scraper. The addition of a 
coating on the scraped floor is recommended in order to achieve 
a smooth(er) surface. 
Manure  and  water  channels  are  built  at  opposite  sides  of  the 
convex  and  smooth  solid  concrete  floor.  The  water  channel  is 
installed  underneath  the  side  of  the  pen  where  the  pigs  tend  to 
eat and drink. Water for cleaning the pens may be used to fill the 
water  channels.  The  channel  is  partially  filled  with  at  least  10 
cm  of  water.  The  manure  channel  can  be  built  with  flashed 
gutters or slanted walls which are normally flushed twice every 
day for example with water from the other channel or the liquid 
fraction  of 
(dry  matter  content  no  higher 
the  slurry 
than approximately 5 %).  
V-shaped manure belts roll inside the manure channels covering 
the  whole  surface,  so  that  all  faeces  and  urine  are  dropped  on 
them. Belts are run at least twice every day to separately  carry 
urine  and  faeces  to  closed  manure  storage.  Belts  are  made  of 
plastic (polypropylene or polyethylene). 

The  pen  is  equipped  with  a  narrow  pit  with  a  width  of  about 
0.6 m. The pit can be placed in an external alley. 

slurry 

by 
Frequent 
flushing  (in  case  of  fully  or  partly 
slatted floor). 

removal 

Kennel  /  hut  housing  (in  case  of 
partly slatted floor). 

A  very  frequent  removal  (e.g.  once  or  twice  per  day)  of  the 
slurry  is  performed  by  flushing  the  channels  with  the  liquid 

fraction  of  the  slurry  (dry  matter  content  no  higher  than 

approximately 5 %)  or  water.  The  liquid  fraction  of  the  slurry 
can  also  be  aerated  before  flushing.  This  technique  can  be 
combined with individual variations of the bottoms of channels 
or pits, e.g. gutters, tubes or a permanent slurry layer.  
Separate  functional areas are organised in the pens of  naturally 
ventilated  houses.  The  lying  area  (about  50–60 %  of  the  total 
area) consists of a levelled insulated concrete floor with covered, 
insulated huts or kennels, with a hinged roof that can be raised 
or  lowered  to  control  temperature  and  ventilation.  The  activity 
and  feeding  areas  lie  on  a  slatted  floor  with  a  manure  pit 
underneath and frequent manure removal, e.g. by vacuum. Straw 
can be used on the solid concrete floor.  

Intensive Rearing of Poultry or Pigs 

745 

Chapter 5 

Technique 

Full  litter  system  (in  case  of  solid 
concrete floor). 

Littered  external  alley  (in  case  of 
solid concrete floor). 

Feeding/lying  boxes  on  solid  floor 
(in case of litter-based pens). 

Manure collection in water. 

A  combination  of  water  and 
manure  channels  (in  case  of  fully 
slatted floor). 

Manure  pan  (in  case  of  fully  or 
partly slatted floor). 

Straw flow system (in case of solid 
concrete floor). 

Littered  pens  with 
combined 
manure generation (slurry and solid 
manure). 

Description 
A fully concrete floor almost completely covered with a layer of 
straw or other lignocellulosic material.  
In the litter-floored system, solid manure is frequently removed 
(e.g.  twice  per  week).  Alternatively  in  the  deep  litter  system, 
fresh  straw  is  added  on  top  and  the  accumulated  manure  is 
removed  at  the  end  of  the  rearing  cycle.  Separate  functional 
areas  can  be  organised  into  lying,  feeding,  walking  and 
defecating areas.  
A small door allows the pig to go out to defecate in an external 
alley  with  a  concrete  littered  floor.  The  manure  falls  into  a 
channel from where it is scraped once every day.  
Sows  are  kept  in  a  pen  divided  into  two  functional  areas,  the 
main one littered and a series of feeding/lying boxes over a solid 
floor.  Manure  is  captured  in  the  straw  or  other  lignocellulosic 
material, which is regularly supplied and replaced. 
Manure  is  collected  in  the  cleaning  water  that  is  kept  in  the 
manure  channel  and  refilled  up  to  a  level  of  around  120–150 
mm.  Slanted  channel  walls  are  optional.  After  each  rearing 
cycle, the manure channel is emptied.  

The  sow  is  kept  in  a  fixed  place  (by  using  a  farrowing  crate) 
with a specific defecating area. The manure pit is split up into a 
wide  water  channel  at  the  front  and  a  small  manure  channel  at 
the  back,  with  a  reduced  manure  surface.  The  front  channel  is 
partly filled with water. 
A prefabricated pan (or pit) is placed under the slatted floor. The 
pan is deepest at one end with a slope  of at least 3 ° towards a 
central  manure  channel;  the  manure  discharges  when  its  level 
reaches around 12 cm. If a water channel exists, the pan can be 
subdivided into a water section and a manure section.  
Pigs  are  reared  in  pens  with  solid  floors,  where  a  sloped  lying 
area and an excretion area are defined. Straw is provided to the 
animals daily. Pig activity pushes and distributes the litter down 
the  pen's  slope  (4–10 %)  to  the  manure  collection  aisle.  The 
solid  fraction  can  be  removed  frequently  (e.g.  daily)  with  a 
scraper. 
Farrowing  pens  are  equipped  with  separate  functional  areas:  a 
bedded  lying  area,  walking  and  dung  areas  with  slatted  or 
perforated floors, and a feeding area on a solid floor. Piglets are 
provided  with  a  littered  and  covered  nest.  Slurry  is  frequently 
removed  with  a  scraper.  Solid  manure  is  manually  removed 
from  the  solid  floor  areas  on  a  daily  basis.  Litter  is  regularly 
provided. A yard can be combined with the system. 

Use of floating balls in the manure 
channel. 

Balls  half-filled  with  water  and  made  of  special  plastic  with 
non-sticky coating, float on the surface of the manure channels.  

746 

Intensive Rearing of Poultry or Pigs 

 
 
5.4.12.2 

Techniques for cooling slurry 

Chapter 5 

Technique 

Slurry cooling pipes 

Description 

A  reduction  of  slurry  temperature  (usually  less  than  12  °C)  is 
achieved by installing a cooling system placed above the slurry, 
above  the  concrete  floor  or  cast  into  the  floor.  The  applied 
cooling intensity can be from 10 W/m2 to 50 W/m2 for gestating 
sows  and  fattening  pigs  housed  on  partly  slatted  floors.  The 
system  consists  of  pipes  in  which  a  refrigerant  or  water  is 
circulated. The pipes are connected to a heat exchange device to 
recover  energy  that  may  be  used  for  heating  other  parts  of  the 
farm. The pit or the channels need to be frequently emptied due 
to a relatively small exchanging surface of the pipes. 

5.4.12.3 

Techniques for reducing the pH of slurry 

Technique 

Slurry acidification 

Description 
Sulphuric  acid  is  added  to  slurry  in  order  to  lower  the  pH  to 
about 5.5 in the slurry pit. The addition can be carried out in a 
process tank, followed by aeration and homogenisation. Part of 
the  treated  slurry  is  pumped  back  to  the  storage  pit  under  the 
housing  floors.  The  treatment  system  is  fully  automated.  Prior 
to (or after) landspreading on acid soils, lime addition  may be 
required  to  neutralise  the  pH  of  the  soil.  Alternatively, 
acidification  can  be  performed  directly  in  the  slurry  store  or 
continuously during landspreading. 

5.4.13 

Techniques for poultry housing 

5.4.13.1 

Techniques for reducing ammonia emissions from houses for 
laying hens, broiler breeders or pullets 

Housing system 

Unenriched cage system 

Enriched cage system 

Deep litter with manure pit 

Description 
Broiler  breeders  are  housed  in  unenriched  cage  systems  fitted 
with  perches,  litter  area  and  nest.  Pullets  should  be  given 
appropriate experience of management practices (e.g. particular 
feeding  and  watering  systems)  and  environmental  conditions 
(e.g. natural light, perches, litter) to enable them to adapt to the 
husbandry  systems  which  they  will  encounter  later  in  life.  The 
cages are usually arranged on three or more tiers. 
Enriched cages are built with sloping floors, are made of welded 
wire  mesh  or  plastic  slats  and  are  equipped  with  fixtures  and 
increased  space  for  feeding,  drinking,  nesting,  scratching, 
perching and egg collection. The capacity of the cages can vary 
from around 10 to 60 birds. The cages are  usually arranged on 
three or more tiers. 
At  least  one-third  of  the  total  floor  in  the  housing  is  covered 
with  litter  (e.g.  sand,  wood  shavings,  straw).  The  remaining 
floor area is slatted, with a manure pit underneath. Feeding and 
drinking  fixtures  are  located  over  the  slatted  area.  Additional 
structures can be present inside or outside the housing, such as 
verandas and free-range system. 

Intensive Rearing of Poultry or Pigs 

747 

 
 
 
 
 
 
 
 
 
 
 
Chapter 5 

Housing system 

Aviaries 

Manure  removal  by  belts  (in  case 
of  enriched  or  unenriched  cage 
systems) with at least: 
-  one  removal  per  week  with  air 
drying; 
or  
-  two  removals  per  week  without 
air drying. 
Manure  belt  or  scraper  (in  case  of 
deep litter with a manure pit). 
Forced  ventilation 
system  and 
infrequent manure removal (in case 
of  deep  litter  with  a  manure  pit) 
only if used in combination with an 
additional mitigation measure, e.g.: 
-  achieving  a  high  dry  matter 
content of the manure; 
- an air cleaning system. 

Forced  air  drying  of  manure  via 
tubes  (in  case  of  deep  litter  with  a 
manure pit). 

Forced  air  drying  of  manure  using 
perforated  floor  (in  case  of  deep 
litter with a manure pit). 

Manure belts (in case of aviary). 

Forced drying of litter using indoor 
air (in case of solid floor with deep 
litter). 

Description 
Aviaries  are  divided  into  different  functional  areas  for  feeding, 
drinking,  egg  laying,  scratching  and  resting.  The  usable  area  is 
increased  by  means  of  elevated  slatted  floors  combined  with 
tiers. The slatted area ranges between 30 % and 60 % of the total 
floor area. The remaining floor is typically littered. 
In plants for laying hens and broiler breeders, the system can be 
combined with verandas with or without free-range system. 

Belts  are  placed  under  the  cages  for  manure  removal.  The 
frequency of removal can be once every week (with air drying) 
or  more  (without  air  drying).  The  collection  belt  may  be 
ventilated for drying the manure. Whisk-forced air drying in the 
manure belt can be also used. 

Manure  is removed by scrapers (periodically) or by belts (once 
every week for dried manure, twice every week without drying). 

The deep litter system (see above for description) is combined 
with infrequent manure removal, e.g. at the end of the rearing 
cycle. A minimum dry matter content of manure of around 50–
60 % is ensured. This is achieved by an appropriate forced 
ventilation system (e.g. fans and air extraction placed at floor 
level).  

The  deep  litter  system  (see  above  for  description)  is  combined 
with  manure  drying  by  means  of  forced  ventilation  applied 
through  tubes  that  blow  air  (e.g.  at  17–20  °C  and  1.2 m3/bird) 
over the manure stored under the slatted floor.  
The  deep  litter  system  (see  above  for  description)  is  equipped 
with  a  perforated  floor  placed  underneath  the  manure  which 
allows  for  forced  air  blowing  from  below.  The  manure  is 
removed at the end of the rearing cycle.  
Manure is collected on belts under the slatted floor and removed 
at  least  once  every  week  by  ventilated  or  not  ventilated  belts. 
Littered and solid floors can be combined in aviaries for pullets. 
In  a  deep  litter  system  without  a  manure  pit,  indoor  air 
recirculation systems can be used to dry the litter, while meeting 
the  physiological  needs  of  the  birds.  To  this  end,  fans,  heat 
exchangers and/or heaters can be used. 

748 

Intensive Rearing of Poultry or Pigs 

5.4.13.2 

Techniques for reducing ammonia emissions from broiler houses 

Chapter 5 

Technique 

Natural or forced ventilation with a 
non-leaking  drinking  system  (in 
case of solid floor with deep litter). 

Forced drying system of litter using 
indoor  air  (in  case  of  solid  floor 
with deep litter). 

Litter on manure belt and forced air 
drying  (in  case  of  tiered  floor 
systems). 

Description 
The building is closed and well-insulated, equipped with natural 
or  forced  ventilation,  and  can  be  combined  with  a  veranda 
and/or a free-range system. The solid floor is fully covered with 
litter  which  can  be  added  to  upon  necessity.  Floor  insulation 
(e.g. concrete, clay,  membrane) prevents  water condensation in 
the  litter.  Solid  manure  is  removed  at  the  end  of  the  rearing 
cycle.  The  design  and  operation  of  the  drinking  water  system 
prevents leakage and spillage of water on the litter. 
Indoor  air  recirculation  systems  can  be  used  to  dry  the  litter, 
while meeting the physiological needs of the birds. To this end, 
fans, heat exchangers and/or heaters can be used. 
A  multi-floor  system  on  tiers  equipped  with  manure  belts 
covered with litter. Corridors for ventilation are left between the 
rows of tiers. Air enters through one corridor and is directed to 
the  litter  material  on  the  manure  belt.  Litter  is  removed  at  the 
end of the rearing cycle. The system can be used in combination 
with a separate initial stage where broiler chicks are hatched and 
grown for a limited time on manure belts with litter on a multi-
tiered system. 

Heated and cooled littered 
floor 
systems). 

(in  case  of  combideck 

See Section 5.4.2. 

5.4.13.3 

Techniques for reducing ammonia emissions from duck houses 

Technique 

Frequent  litter  addition  (in  case  of 
solid  floor  with  deep  litter  or  deep 
litter combined with slatted floor). 

Frequent  manure  removal  (in  case 
of fully slatted floor). 

Description 
Litter is maintained dry by frequent addition (e.g. daily) of fresh 
material upon necessity. Solid manure is removed at the end of 
the rearing cycle. 
The  housing  system  can  be  equipped  with  natural  or  forced 
ventilation and combined with a free-range system.  
In  case  of  deep  litter  combined  with  slatted  floor,  the  floor  is 
equipped with slats in the drinker area (about 25 % of the total 
floor area). 
Slats cover the pit where the manure is stored and evacuated to 
the external store. Frequent manure removal to an external store 
can be done:  

1.
2.

by permanent gravity flow;
by scraping with variable frequencies.

The  housing  system  can  be  equipped  with  natural  or  forced 
ventilation and combined with a free-range system. 

5.4.13.4 

Techniques for reducing ammonia emissions from turkey houses 

Technique 

Natural or forced ventilation with a 
non-leaking  drinking  system  (in 
case of solid floor with deep litter). 

Description 
The  solid  floor  is  fully  covered  with  litter  which  can  be  added 
upon necessity. Floor insulation (by e.g. concrete, clay) prevents 
water condensation in the litter. Solid manure is removed at the 
end  of  the  rearing  cycle.  The  design  and  operation  of  the 
drinking water system prevents leakage and spillage of water on 
the litter. Natural ventilation can be combined with a free-range 
system. 

Intensive Rearing of Poultry or Pigs 

749 

750 

Intensive Rearing of Poultry or Pigs 

Chapter 6 

6  EMERGING TECHNIQUES 

6.1  Rearing of poultry 

6.1.1 

Low-litter flooring system for broilers 

Description  
Broilers  are  reared  with  significantly  reduced  bedding  (e.g.  up  to  one  inch  of  wood 
shavings/sawdust litter material to help prevent footpad lesion) on a ventilated plenum floor that 
reduces ammonia generation.  

The system consists of two layers of polymer flooring with an air plenum in between. The top 
layer is perforated and supported by specially designed conical structures attached to the lower 
layer, to allow the downward wicking of moisture from poultry  faeces, which results in much 
dryer manure. The litter can be removed in accordance with usual practices. 

Achieved environmental benefits 
The  system  intends  to  drastically  reduce  ammonia  emissions  by  the  fast  drying  of  manure 
combined with a forced ventilation system. The accelerated drying in combination with an inert 
polymer  allows  for  the  manure  to  maintain  an  acidic  pH  which  leads  to  a  drastic  reduction 
(quasi-elimination) of ammonia and darkling beetle populations (a major disease vector).  

Cross-media effects 
The low-litter flooring system may not go down well with consumers. 

Environmental performance and operational data 
A series of experiments were undertaken at the University of Maryland (US) over a five-year 
period. Results indicated that as the technique and design were improved, better results for feed 
efficiency and growth rate were obtained. Although not measured, dust levels were significantly 
reduced. 

Driving force for implementation 
As a result of the improved indoor environment, animals can perform more efficiently. 

Applicability - Economics - Example plants 
No information on cost or availability has been reported. The technique may not be applicable 
in  the  EU-28  as  it  should  be  recalled  that  Council  Directive  2007/43/EC  laying  down  the 
minimum rules for the protection of chickens kept for meat production states in paragraph 3 of 
Annex I that all chickens shall have permanent access to litter which is dry and friable on the 
surface. 

Reference literature 
[ 369, Harter-Dennis 2010 ] 

Intensive Rearing of Poultry or Pigs 

751 

Chapter 6 

6.1.2 

Sequential feeding in poultry 

Description  
Sequential feeding is a cyclic feeding programme of two feeds, one high protein-low energy and 
one high energy-low protein, during one or several days. The nutritional balance that is provided 
during the growth cycle is no different to standard feeding, so sequential feeding permits the use 
of  a  wide  spectrum  of  feed  materials,  including  those  which  are  difficult  to  incorporate  into 
traditional feed formulae [ 281, France 2010 ]. 

Achieved environmental benefits 
Sequential  feeding  allows  the  separation  of  the  calcium  supply  from  that  of  phosphorus. 
Therefore it should be possible to reduce the phosphorus intake and its release. Additionally, the 
impact of the utilised raw materials can also be reduced. 

Cross-media effects 
No information provided. 

Environmental performance and operational data 
An  experiment  was  carried  out  in  France  to  investigate  the  energy  (2 800 kcal/kg  and 
3 200 kcal/kg) and protein (230 g/kg and 150 g/kg) content effects on the daily feed intake of a 
48-hour sequential feeding cycle, compared to a standard diet. Feed intake was similar with both 
sequential feeding and the standard diet but high-energy feed was overconsumed during the first 
hour of distribution, but this was compensated for over the rest of the day. Growth performance 
was not modified. 

It  was  also  found  that  there  was  a  strong  link  between  the  feed  composition  and  its 
characteristics (colour and energy content) and birds could learn to recognise the types of feed 
and therefore self-select for a preferential ingestion.  

Applicability 
The technique requires more research into the commercial application and potential impacts. 

Economics 
No information provided. 

Driving force for implementation 
The technique allows a great flexibility in the diet formulation in order to reduce the feed costs. 
The technique makes it possible to decrease the incidence of locomotive disorders by increasing 
the animals' activity. Animals would spend more time pecking less attractive feed. 

Example plants 
No information provided. 

Reference literature 
[ 281, France 2010 ] [ 446, Bouvarel et al. 2007 ] 

752 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 6 

6.2  Rearing of pigs 

6.2.1 

Air cleaning of underfloor exhaust airflow with fully slatted 
floors 

Description 
In addition to the room air extraction outlet, the pen is equipped with an underfloor pit exhaust 
above the slurry surface. Only the exhaust air extracted from the underfloor pit is treated by an 
air cleaning system (e.g. wet scrubber). The mass flow of the discharged air passing through the 
air  treatment  system  is  thus  only  a  small  fraction  of  the  overall  air  renewal  rate,  which  is 
determined by the fresh air requirements of the animals. In contrast, the partial flow directed to 
the  air  treatment  unit  contains  a  large  fraction  of  the  air-polluting  substances  (ammonia  and 
odour). The exhaust air passing through the above-floor ventilation system is less polluted and 
is  released  without  air  cleaning.  The  openings  area  of  the  slats  in  the  fully  slatted  flooring  is 
reduced by 40 % in order to improve the underfloor extraction efficiency. Still, because of the 
width of the slatted floor and the pressure distribution, it is not possible to completely prevent 
air passing from the underfloor compartment into the above-floor compartment. A layout of the 
system is shown in Figure 6.1. 

Source: [ 489, Pedersen et al. 2010 ] 

Figure 6.1:  Layout  of  the  ventilation  system  (left)  and  the  floor  design  (right)  with  reduced  slat 

openings 

Intensive Rearing of Poultry or Pigs 

753 

Chapter 6 

In  another  configuration  of  the  technique,  exhaust  air  is  sucked  out  via  linear  outlet  channels 
located  under  the  ceiling  and  via  underfloor  air  extraction  above  the  slurry  surface  with 
following air cleaning [ 620, Germany 2013 ] [ 671, Krause et al. 2009 ]. 

Achievable environmental benefits 
The system reduces aerial pollutant emissions. 

Cross-media effects 
No information provided. 

Environmental performance and operational data 
An experimental study in Denmark comparing the technique with a conventional system with 
only room exhaust has shown that a pit ventilation rate of only 10 m3/hour per pig improves the 
indoor  environment  substantially  and  reduces  the  emissions  from  the  room  exhaust.  In 
particular, at least 70 % of the ammonia emissions, 50 % of the odour emissions and 90 % of 
the hydrogen sulphide emissions are expected to be avoided in comparison with the system with 
only  room  extraction.  Measured  odour,  hydrogen  sulphide  and  ammonia  concentrations  and 
emissions are presented in Table 6.1 for different pit ventilation rates and suction point locations 
in comparison with a control room having only conventional room exhaust.  

Table 6.1:  Odour, hydrogen sulphide and ammonia concentrations and emissions 

Measurement 

Ventilation rate, m3/h/pig 
Odour concentration, ouE/m3
Odour emission, ouE/s per 1 000 kg 
H2S-concentration, ppb 
H2S-emission, mg H2S/h per pig 

Measurement 

Ventilation rate, m3/h per pig 
NH3 concentration, ppm 
NH3 emission, g NH3-N/h per pig 

Measurement 

Ventilation rate, m3/h/pig 
Odour concentration, ouE/m3
Odour emission, ouE/s per 1 000 kg 
H2S concentration, ppb 
H2S emission, mg H2S/h per pig 

Measurement 

Control 
room 
53 
360 
80 
197 
4.3 

Control 
room 
50 
7.4 
7.3 

Control 
room 
52 
480 
99 
246 
4.8 

Experiment 1 
Room 
Pit 
43 
20 
140 
820 
22 
64 
70 
505 
1.1 
3.8 

Experiment 1 
Room 
Pit 
33 
22 
1.5 
14 
1.0 
5.2 

Experiment 3 
Room 
Pit 
49 
10 
170 
890 
33 
31 
87 
485 
1.4 
2.0 

Experiment 2 
Room 
Pit 
39 
19 
170 
910 
27 
71 
30 
475 
0.4 
4.0 

Experiment 2 
Room 
Pit 
31 
18 
1.1 
18 
1.1 
6.4 

Experiment 4 
Room 
Pit 
48 
10 
200 
1 230 
38 
47 
22 
777 
0.3 
3.0 

Experiment 4 
Room 
Pit 
39 
11 
2.2 
27 
1.5 
4.7 

Control 
room 
50 
9.3 
8.2 

Experiment 3 
Room 
Pit 
43 
10 
2.6 
20 
2.0 
3.6 

Ventilation rate, m3/h per pig 
NH3 concentration, ppm 
NH3 emission, g NH3-N/h per pig 
NB: Data measured at a pit exhaust rate of 10 m3/h and 20 m3/h per pig (32 pigs per pen). 
Experiment 1: Suction point underneath the dunging area, 20 m3/h per pig in the pit exhaust. 
Experiment 2: Suction point underneath the resting area, 20 m3/h per pig in the pit exhaust. 
Experiment 1: Suction point underneath the dunging area, 10 m3/h per pig in the pit exhaust. 
Experiment 2: Suction point underneath the resting area, 10 m3/h per pig in the pit exhaust. 
Source: [ 489, Pedersen et al. 2010 ] 

It  is  expected  that,  by  cleaning  around  20 %  of  the  maximum  ventilation  capacity  of  a  house 
with  an  air  scrubber  with  95 %  ammonia  reduction  efficiency,  more  than  65 %  of  the  total 
emitted ammonia can be abated by the air treatment system. 

754 

Intensive Rearing of Poultry or Pigs 

Chapter 6 

In Germany, ammonia concentrations in the animal house air above the slatted floor have been 
shown  to  reach  maximum  values  of  about  4  ppm  when  both  underfloor  and  above-floor 
ventilation systems are running and of about 2 ppm during wintertime when only the underfloor 
ventilation  system  is  running.  The  ammonia  emissions  are  expected  to  be  reduced  by  around 
70 % in total. In addition, emissions of dust and odour are reduced. A homogeneous flow field 
with moderate flow velocities of the air throughout the whole animal house can be attained by 
optimising the location and dimension of the supply and the exhaust openings. Thus the transfer 
of ammonia from the slurry surface into the animal house air is minimised. 

Applicability 
The technique is applicable to pig housing systems with a slatted floor. 

Economics 
As only a fraction of the exhaust air has to be cleaned, the dimension of the air treatment unit 
and  the  operating  costs  for  energy  and  water  are  reduced.  The  cost  saving  is  expected  to  be 
about 50 % compared to standard air treatment systems.  

Driving force for implementation 
The optimised airflow reduces the concentration of ammonia and other pollutants in the indoor 
air which improves animal welfare and occupational safety.  

Example plants 
The technique is under development for a full-scale implementation. Attention is focused on the 
design of a central pit ventilation system to ensure uniform pit ventilation and the dimensioning 
of partial pit ventilation with an efficient air cleaning system to create a cost-efficient solution. 

Reference literature 
[ 489, Pedersen et al. 2010 ] [ 620, Germany 2013 ] [ 671, Krause et al. 2009 ] 

6.2.2 

Air cleaning of underfloor exhaust flow with partly slatted floors 
with a scraper and urine separation 

Description 
In this pig housing system ('Perstrup system'), the partial underfloor air extraction is combined 
with the in-house separation of faeces and urine. In particular, the technique features pens with a 
partly  slatted  floor  and  a  sloped  manure  channel  with  a  gutter  for  urine  drainage  from  where 
manure is frequently removed using a scraper. Partial air extraction from the manure channel is 
done directly through a ventilation channel under the solid part of the pen floor (see Figure 6.2) 
while the remaining exhaust air is evacuated through a separate outlet in the room.  

Intensive Rearing of Poultry or Pigs 

755 

Chapter 6 

Source: [ 490, Pedersen et al. 2011 ] 

Figure 6.2:  Drawing of the partly slatted floored 'Perstrup' pens 

Achieved environmental benefits 
The  underfloor  air  evacuation  is  very  efficient  at  reducing  the  ammonia  concentration  in  the 
room.  

Cross-media effects 
An increase in the odour emissions of the underfloor exhaust air is reported after the installation 
of the in-house urine separation system.  

Environmental performance and operational data 
In  a  study  conducted  in  Denmark,  the  system  was  evaluated  in a  fattening  pig  farm  against a 
system with only a manure channel (without separation) and partial underfloor evacuation, with 
respect  to  ammonia  and  odour  concentrations  and  the  pig  manure  emissions  and  separation 
efficiency. Results are shown in Table 6.2. 

Table 6.2:  Average concentrations and emissions of ammonia and odour measured in trials with 

underfloor ventilation  

Parameter 

Units 

ppm 

ppm 

Room ammonia concentration 
Underfloor ammonia 
concentration 
Ammonia emission per 
section 
Room odour concentration 
Underfloor odour 
concentration 
Odour emission 
ouE/s per 1 000 kg 
NB: The 95 % confidence interval is reported in brackets. 

g NH3-N/h 
ouE/m3
ouE/m3

Housing system 

Slurry channel without 
in-house separation 
0.3 

Slurry channel with 
in-house separation 
0.3 

5.6 

59 

5.5 

60 

483 (388–601) 

474 (381–589) 

737 (609–890) 

913 (757–1 102) 

313 (266–368) 

363 (309–426) 

Source: [ 490, Pedersen et al. 2011 ] 

The statistical analysis showed no differences in ammonia emissions between the control room 
and the room equipped with in-house separation. However, the ammonia concentrations in the 
room  were  very  low  compared  with  the  exhaust  air  beneath  the  slats  due  to  a  very  efficient 
underfloor evacuation. On average, the NH3 concentration was below 0.5 ppm in the room and 
about 10 times lower than at the underfloor outlets. In conclusion, the slurry surface below the 
slats was the major source of ammonia emissions.  

756 

Intensive Rearing of Poultry or Pigs 

Chapter 6 

It  was  also  shown  that  even  at  ventilation  rates  below  20 %  of  the  maximum  capacity,  i.e. 
20 m3/h per pig place, the underfloor air evacuation was very efficient. Former Danish studies 
have  shown  that  an  average  air  velocity  of  0.1–0.2 m/s  through  the  slats  is  crucial  to  obtain 
efficient underfloor air evacuation. At a ventilation rate of 20 m3/h per pig place, the air velocity 
can be calculated as 0.14 m/s in the Perstrup pig house. 

With  an  efficient underfloor  air evacuation,  more  than  90 %  of  the  ammonia  emission  can  be 
collected in just 20 % of the maximum ventilation capacity.  

On the other hand, odour emissions were 16 % higher in the room with in-house separation due 
to the higher odour concentrations in the outlets from the underfloor air evacuation. 

The in-house separation of urine showed high separation efficiencies; in particular, the collected 
solid manure contained on average 22 % DM or 93 % of the total amount of DM. However, the 
dry  matter  content in  the solid fraction  was too  low and  the  amount  of  solid  manure  was  too 
large  (53 %  of the  total) to  make  the  system  economically  viable. There  is  a further  need  for 
improvement  in  order  to  increase  the  dry  matter  content  and  reduce  the  amount  of  manure 
collected in the solid fraction to less than 25 % of the total amount.  

Driving force for implementation 
In areas where farmers are obliged to transport slurry over long distances, there is an incentive 
to reduce bulk slurry volumes. The natural separation of the manure inside the pig house will 
reduce the volume to be transported. If an air scrubber is installed for ammonia reduction, costs 
will be substantially lower. 

Reference literature 
[ 490, Pedersen et al. 2011 ] 

6.2.3 

Near-zero-emission stall housing system  

Description 
The  near-zero-emission  stall  pig  housing  system  (NZES)  through  which  the  formation  and 
release of aerial pollutants can be reduced to close to zero. This is achieved by a combination of 
different  measures  concerning  slurry  management  (slurry  cooling  with  periodic  removal  by  a 
scraping  system),  building  design  (single  room  in  high-capacity  housing  with  a  large  air 
volume)  and  ventilation  (high-efficiency  ventilation).  An  exhaust  air  treatment  system  is 
installed  too.  The  system  also  combines  design  elements  which  offer  advantages  concerning 
animal welfare (e.g. fully automatic dosage of corn silage to be used as occupational material 
and  offering  more  space  per  sow).  Feeding  crates  for  gestating  sows  are  also  provided  to 
minimise stress and aggression in group housing.  

The several existing measures that are now combined are as follows: 

 

 

 

Slurry below the slatted floor is cooled by water pipes, which are enclosed in the concrete 
of the channels (see Figure 6.3). Cooling slurry down to approximately 15 °C reduces the 
formation of air pollutants, in particular ammonia, very efficiently. Heat pumps allow the 
extracted heat to be recovered, e.g. for the piglets' nest. This in turn causes a significant 
energy saving. 

Manure channels are shallow. Approximately three times a week the slurry is removed by 
a manure scraping system. In this way, the amount of slurry inside the animal house, and 
therefore the emission of air pollutants, is reduced to a minimum.  

House construction (the building is shaped in such a way that the roof also makes up the 
ceiling and the various production areas are located in only one space) offers three times 
more air volume per animal than conventional pig housing systems (see Figure 6.4). This 
leads to a distinctly lower ventilation rate, and hence enables energy savings. In addition, 

Intensive Rearing of Poultry or Pigs 

757 

 
 
 
 
 
 
 
 
 
 
Chapter 6 

as heat rises, this housing system allows a continuous discharge of heat out of the animal 
area, which results in lower temperatures in the slurry area.  

 

A  certified  air  cleaning  system  removes  at  least  70 %  of  the  ammonia,  odour  and  dust 
from the waste air. Due to the lower ventilation rates and concentration of harmful gases, 
it  is  possible  to  reduce  the  size  of  the  exhaust  treatment  unit.  This  lessens  the  use  of 
resources  (energy,  water,  and  auxiliary  material),  as  well  as  lowering  investment  and 
operating costs.  

Source: [ 623, Germany 2013 ] 

Figure 6.3:  Scheme of slurry cooling in the shallow manure channels and heated piglet area 

Source: [ 623, Germany 2013 ] 

Figure 6.4:  Gestating sow room of the near-zero-emission pig housing system  showing the  'roof-

ceiling' construction principle 

758 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
Chapter 6 

Achieved environmental benefits 
Ammonia, odour and dust emissions are reduced to a very low level. 

The  integrated  ventilation  and  heat  exchange  concept  enables  significant  energy  savings.  The 
use  of  resources  for  the  operation  of  the  exhaust  air  treatment  (energy,  water  and  auxiliary 
materials) is reduced. 

The  lower  in-house  temperature  results  in  a  better  indoor  air  quality  due  to  the  lower 
concentration of harmful gases.  

Economics 
Compared to standard systems, the building costs per piglet are expected to be lower, based on 
the  sophisticated  construction  of  the  roof,  the  one-room  design,  and  the  shallow  manure 
channels.  

Lower  levels  of  pollutants  in  the  housing  air  and  a  lower  ventilation  rate  will  result  in  less 
investment  and lower  operating  costs for  exhaust  air treatment  in comparison  to  conventional 
systems. 

The complete system is designed to minimise labour costs.  

Driving force for implementation 
The system offers benefits in animal welfare and working conditions due to the improved indoor 
air quality and housing climate. Animals are supplied with considerably more space than legally 
required. The improvement of animal welfare in combination with the better housing climate is 
expected  to  lead  to  improved  performances.  Additionally,  staff  should  suffer  less  respiratory 
tract infections, e.g. caused by ammonia. 

The  reduction  of  the  total  emissions  to  close  to  zero  provides  the  possibility  to  locate  bigger 
animal housing units close to residential areas and nature reserves. 

Piglet  mortality  rates  are  expected  to  decrease,  especially  with  the  spacious  farrowing  pen, 
because the sow's cooled surroundings will force piglets to move quickly back to their nest. 

By  providing  'self-protecting  feeding  crates',  stress  and  aggression  among  gestating  sows  are 
expected to be reduced.  In addition, within the farrowing area, management will be improved 
considerably by having all farrowing pens in one room.  

Example plants 
The first housing project has started and is under construction (2013).  

Reference literature 
[ 623, Germany 2013 ] 

Intensive Rearing of Poultry or Pigs 

759 

 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 6 

6.2.4 

Photocatalytic titanium dioxide coating paints 

Description  
Titanium dioxide (TiO2) catalytic paint can be used for coating the walls of pig houses in order 
to reduce the indoor concentration of ammonia and its release to the outdoor environment. 

Through photocatalytic oxidation, TiO2 can degrade ammonia in water solutions and in the air 
leading to the production of N2, N2O or NO and water along one of the three following main 
paths: 

 
 
 

2 NH3 + 1.5 O2 = N2 + 3 H2O 
2 NH3 + 2 O2 = N2O +3 H2O 
2 NH3 + 2.5 O2 = 2 NO + 3 H2O. 

Photocatalysis  is  an  accelerated  photoreaction  in  the  presence  of  a  catalyst  consisting  of  the 
chemical transformation of a substrate, without it undergoing any transformation itself.  

Cross-media effects 
In the Safety Data Sheet available from producers, it is stated that paints have no negative effect 
on animal and operator health. 

Achieved environmental benefits 
Field experiments tested the difference in ammonia concentration between houses  coated with 
conventional  paint  and  others  painted  with  TiO2  paint.  The  average  daily  concentration  of 
ammonia  was  lower  for  the  TiO2  paint  treatment  by  1.65 mg/m3.  The  ammonia  reduction 
efficiency of the paint treatment was 30.50 %. GHG measurements were also lower in houses 
coated with TiO2 paints. 

Economics 
The cost of treating a surface of 150 m2 with TiO2 paint at 70 g/m2 is EUR 126. Hence the cost 
of abating 1 kg of ammonia is estimated to be EUR 3.1. 

Reference literature 
[ 286, Guarino et al. 2008 ] 

6.2.5 

Alternative farrowing pens 

Description 
A non-crate alternative farrowing pen for indoor accommodation has been developed in the UK 
under  the  PigSAFE  project  (Piglet  and  Sow  Alternative  Farrowing  Environment).  In  this 
system, sows are not confined in their movement and there are embedded design features which 
provide adequate protection to piglets. Furthermore, no practical constraints exist on the types 
of enrichment which can be commercially used to allow expression of nest-building behaviour. 
The farrowing system comprises a nest area with straw and piglet protection features, a heated 
creep, a slatted dunging area and a lockable sow feeder (see Figure 6.5). 

760 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Chapter 6 

Source: [ 449, Edwards et al. 2012 ] 

Figure 6.5:  An illustration of a design for an alternative farrowing sow pen  

Achieved environmental benefits 
No information provided. 

Environmental performance and operational data 
The  system  has  been  initially  evaluated  at  two  farms  against  conventional  farrowing  crates 
under  the  same  commercial  management.  At  the  first  farm  the  system  was  implemented  on  a 
partly slatted floor with minimal straw addition and at the second on a straw-based solid floor 
with  a  slatted  dunging  passage.  At  both  sites  results  were  promising,  with  no  significant 
performance  differences  between  the  alternative  pens  and  the  conventional  farrowing  crates 
(e.g. regarding mortality of live-born piglets until weaning, and sow and piglet performance), or 
even better results were achieved with the PigSAFE design, for example concerning the labour 
to perform daily husbandry routines. 

Economics 
Modelling  of  the  production  costs  of  different  housing  systems  for  farrowing  sows  indicated 
that  the  costs  of  pig  production  using  the  PigSAFE  system  would  be  approximately  3.5 % 
higher  than  using  a  standard  farrowing  crate,  assuming  equitable  pig  performance  and  taking 
account of both capital and operating costs (feed, labour, bedding, etc.). This arises because of 
the higher capital cost associated with the greater space requirements (almost double) and more 
complex pen  construction in the PigSAFE design. Any improvement in pig performance (e.g. 
through reduced piglet mortality, improved weaning weight or sow re-breeding) would narrow 

Intensive Rearing of Poultry or Pigs 

761 

 
 
 
 
 
Chapter 6 

the cost difference. An indicative capital cost is reportedly around EUR 5 000/sow place and the 
total  annual  costs  of  the  system  around  EUR  580/sow  place/year  in  comparison  with 
EUR 3600/sow place and EUR 420/sow place/year respectively for a conventional system with 
farrowing crates (values in EUR as per exchange EUR 1 = GBP 0.88). 

Driving force for implementation 
The  system  can  offer  a  better  welfare  alternative  for  housing  during  farrowing  and  lactation, 
incorporating  features  to  reconcile  the  behavioural  needs  of  the  animals  with  good  piglet 
survival rates and farm practicality.  

Example plants 
The  alternative  pens  are  installed  in  two  commercial  farm  production  systems  for  their 
evaluation. 

Reference literature 
[ 449, Edwards et al. 2012 ] 

762 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Chapter 6 

6.3  Manure processing  

6.3.1 

Combined biological manure processing and ammonia stripping  

Description 
The  manure  processing  system  is  based  on  a  combination  of  mechanical  separation  and 
biological treatment followed by nitrogen separation by ammonia stripping. 

In the first treatment stage, the slurry is separated into solid and liquid fractions using a series of 
mechanical  and  flocculation  processes.  Raw  slurry  is  pumped  from  a  temporary  storage  tank 
onto a filter belt press, which removes 1–2 % of the dry matter content. The liquid fraction is 
then treated with polymers to increase the flocculation and sedimentation of the remaining dry 
matter.  The  sediment  from  flocculation  and  the  solids  from  the  belt  press  are  then  further 
separated, using a screw press, into a solid fibre fraction that contains most of the phosphorus 
from the raw slurry (> 90 %). The liquid fraction leaving this treatment stage has a dry matter 
content of about 1 %. 

The  next  stage  is  an  aerobic  biological  treatment  carried  out  in  treatment  tanks  connected  in 
series  to  separate  nitrogen  from  the  liquid  fraction  (see  Section  4.12.3.1.1).  Gases  released 
during the aerobic biological activity are collected and led to a sulphuric acid air scrubber. Heat 
produced during the biological treatment can be recovered. 

After  biological  treatment,  NH3  stripping  is  carried  out  by  conducting  a  series  of  repeated 
stripping cycles. At first, the biologically treated liquid fraction is air-stripped without chemical 
use  in  order  to  take  advantage  of  the  pH  rise  achieved  with  biological  treatment.  The  first 
stripping reduces  the  buffering capacity of the slurry due to ammonia and carbonate removal, 
and thus reduces the chemical additions needed.  

Before  the  second  stripping,  the  pH  of  the  stripped  effluent  is  raised  by  the  addition  of 
chemicals  such  as  MgO,  Ca(OH)2  or  NaOH.  Further  stripping  cycles  can  be  carried  out, 
increasing  the  pH  by  increments,  until  the  desired  ammonia  level  in  the  liquid  fraction  is 
obtained. Air from the stripping tower is led to an acid scrubber, which is independent of the 
scrubber used for the biological treatment described above. 

After the stripping procedure, the treated effluent is devoid of nitrogen and phosphorus and can 
be directly landspread or further fractionated if organic matter is precipitated by the addition of 
a  small  amount  of  ferric  sulphate.  The  end  products  of  the  whole  process  (including 
fractionation)  are  phosphorus  fertiliser,  NH4SO4  concentrate  as  liquid  fertiliser  and  irrigation 
water. 

Intensive Rearing of Poultry or Pigs 

763 

 
 
 
 
 
 
 
 
 
Chapter 6 

Source: [ 224, Finland 2010 ] 

Figure 6.6:  Schematic  representation  of  the  combined  treatment  system  including  the  solid 

separation step, biological treatment procedure and ammonia stripping stages 

Achieved environmental benefits 
The solid fraction from the separation process contains high levels of phosphorus (> 90 %), and 
is  easily  transportable  over  further  distances.  The  final  effluent  after  aeration  treatment  and 
ammonia stripping is completely odourless and free of pathogenic organisms.  

The combination of various processes in a sequence (aerobic biological treatment, air stripping 
and chemical treatment) allows efficient ammonia removal with minimal chemical use. 

Cross-media effects 
Electrical energy is required to operate the system. 

Environmental performance and operational data 
Reported data on nitrogen reduction with the stripping sequence are summarised in Table 6.3. 

764 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Table 6.3:  Nutrient content of the resulting fractions after the multi-step biological and chemical 

Chapter 6 

manure processing 

Untreated slurry (1) 

Separated P fraction 

NH4SO4 solution 

Separated water 

(1) Dry matter 3.14 %. 
NB: NA = not applicable. 
Source: [ 500, IRPP TWG 2011 ] 

Total P 
kg/m3 
0.72 

Soluble P  Total N  NH4-N 
kg/m3 
kg/m3 
1.90 
2.40 

kg/m3 
0.26 

NO3-N 
kg/m3 
0.0 

 % 
2.0 

mg/l 
0–1 

 % 
0.51 

NA 

mg/l 
0 

 % 
0.64 

mg/l 
0–50 

 % 
0.09 

 % 
14.00 

mg/l 
0–30 

 % 
0.01 

NA 

 % 
0 

Applicability 
No restriction is reported for the application of either existing or new farms. 

Economics 
Depending  on  the  size  and  the  system,  costs  of  installation  may  vary  from  EUR 150 000  to 
EUR 200 000.  With  an  expected  lifespan  of  15  years  and  5 %  amortisation,  the  annualised 
investment costs would be around EUR 18 330. 

Driving force for implementation 
Separation  reduces  the  costs  of  manure  storage,  transportation  and  application  which  are  key 
factors in intensive livestock areas.  

Reference literature 
[ 224, Finland 2010 ] [ 500, IRPP TWG 2011 ] [ 622, Alitalo et al 2011 ] [ 401, Finland 2013 ] 

6.3.2 

Phosphorus separation by gypsum-based precipitate  

Description 
Gypsum-  and  magnesium  oxide-based  precipitate  is  mixed  with  slurry  (2–6 kg  per  tonne  of 
slurry  depending  on  the  dry  matter  content  of  the  slurry)  or  solid  manure.  After  reaction,  the 
dissolved phosphorus in the slurry is precipitated as cadmium and magnesium salts and settles 
with fibrous phosphorus at the bottom of the slurry store. The two fractions can be pumped out 
of  the  tank  separately:  the  liquid  fraction  (rich  in  nitrogen  and  potassium)  can  be  landspread 
where phosphorus fertilisation is not needed and the sediment fraction (rich in phosphorus) can 
be transported to fields where phosphorus is required. 

Achieved environmental benefits 
A  more  focused  balance  of  phosphorus  fertilisation  is  achieved.  A  more  efficient  phosphorus 
utilisation in agriculture will result in decreased  phosphorus losses to water. According to the 
preliminary results, the precipitation also decreases ammonia volatilisation. 

Cross-media effects 
Gypsum  addition  to  slurry  or  manure  can  enhance  the  potential  of  H2S  generation  
[ 624, IRPP TWG 2013 ].  

Environmental performance and operational data 
Depending  on  the  slurry  temperature,  the  fractionation  and  sedimentation  of  phosphorus  will 
take between 3 days and 3 weeks.  

Intensive Rearing of Poultry or Pigs 

765 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Chapter 6 

Only  conventional  farm  machinery  is  needed.  The  precipitate  is  handled  in  600–700 kg  bags 
and can be applied with a forklift and mixed with the propeller mixer (1 to 10 hours depending 
on the volume of the slurry store). Gypsum and MgO can be added from separate bags. Both 
fractions  are  pumped  out  of  the  tank  with  a  transfer  pump  to  be  transported  and  spread  with 
conventional spreading equipment. 

Applicability 
Applicability may be restricted due to the possibility of harmful H2S emission; a risk assessment 
is necessary.  

Economics 
No  particular  investment  is  needed.  Compared  to  conventional  slurry  management,  additional 
costs include raw material and extra work due to the precipitate application. Process profitability 
depends  on  the  price  of  the  chemicals  needed  and  the  transport  distance  for  the  phosphoric 
deposit. 

Driving force for implementation 
Phosphorus  from  manure  can  be  directed  to  those  fields  in  which  crops  would  benefit  from 
phosphorus fertilisation. The low phosphoric liquid fraction is spread on phosphorus-rich fields 
which are usually located near the animal houses, while the fibrous fraction could be transported 
at  a  reasonable  cost  and  spread  on  more  distant  fields  with  a  lower  soil  phosphorus  content. 
Additionally,  when  spread  on  the  field,  gypsum  and  MgO  act  as  sources  of  cadmium, 
magnesium and sodium nutrients for the plants. 

Reference literature 
[ 225, Finland 2010 ] 

6.3.3 

Electro-oxidation/electro-coagulation  

Description 
The objective of the electro-oxidation technique is to oxidise components such as organic matter 
in the anode of an electrochemical reactor by means of an external electric current. The electro-
coagulation  technique  consists  of  destabilising  suspended,  emulsified  or  dissolved  particles 
within an aqueous media by applying an electric current. The electricity will favour aggregation 
of  colloidal  particles  in  the  same  way  as  chemical  reagents  do in  a  conventional  coagulation-
flocculation process.  

The techniques are used separately or combined in the following way: 

 

 

 

Oxidation. Aluminium and iron are used as electrodes. By electrolysis of water, 'nascent' 
active oxygen is generated on anodes that oxidises material in suspension which leads to 
the  degradation  of  different  organic  complexes.  In  this  way,  there  is  no  need  to  add  a 
large amount of chemicals to the liquid or to feed O2 to the cathodes. A prior mechanical 
filtration of slurry is required in order to maintain the oxidation efficiency. 

Flotation. Electrolysis of water also generates hydrogen on the cathode which forms small 
bubbles rising to the surface while carrying previously suspended joined particles. 

Coagulation.  The  aluminium  and  iron  electrodes  that  can  be  used  in  the  anode  are 
dissolved as 'sacrifice electrodes'. Fe+2, as an example, is solubilised in the slurry and acts 
as a coagulant agent, resulting in the separation of organic matter from water and in the 
formation  of  little  flakes.  The  injection  of  a  flocculant  in  the  reactor  outlet  line  will 
produce an increase in the size of the flakes. Subsequently, these flakes may be removed 
from the liquid phase by using some separation device such as a band filter. The output of 
electro-coagulation can also be the input to electro-oxidation. 

The presence of colloidal organic matter can interfere with the oxidation efficiency.  

766 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Chapter 6 

Achieved environmental benefits 
A  high  COD  removal  and  organic  nitrogen  conversion  to  N-NH4  is  reported  for  electro-
oxidation. The technique also offers the possibility for recalcitrant  matter degradation, such as 
phenols, without reagent addition or electrode sacrifice. 

When separated slurry (1.1–1.3 % total solids) is treated with the electro-coagulation technique 
in  combination  with  a  band  filter  (e.g.  a  filter  press),  the  proportion  concentrated  in  the  solid 
fraction is reported for TSS and total P to be > 99 %, for total N > 60 %, and for COD > 90 %. 
As  is  common  for  solid-liquid  separation  techniques,  nutrients  (nitrogen,  phosphorus  and 
potassium)  are  concentrated  in  the  solid  fraction,  enhancing  the  capability  of  manure 
management. 

With the combined use of the techniques, organic matter and nitrogen compounds are removed 
from the produced effluent.  

Cross-media effects 
During  the  electrochemical  treatment  of  slurry,  there  is  a  potential  risk  of  NH3  and  odour 
emissions. Sacrifice electrodes in electro-coagulation should be regularly replaced. 

Environmental performance and operational data 
Table 6.4  provides  an  overview  of  the  characteristics  of  the  matter  deriving  from  pig  slurry 
before and after the treatment. 

Table 6.4:  Example of concentration levels obtained before and after treatment of pig slurry by 

electro-coagulation 

Parameter 

Concentration 
in pig slurry 
(mg/l) 
68 700 
COD 
8 120 
BOD 
4 650 
Total N 
3 630 
NH4-N 
4 970 
Total P 
NI 
Ca 
NI 
Mg 
NI 
K 
0.41 
Pb 
0.17 
Cd 
0.09 
Cr 
48 
Cu 
0.49 
Ni 
< 0.001 
Hg 
Zn 
67 
NB: NI = no information provided. 

Source: [ 256, VITO 2006 ]  

Concentration in 
the solid fraction 
(mg/kg) 
84 200 
10 400 
1 258 
981 
2.52 
NI 
NI 
NI 
5.6 
6.5 
12 
98 
< 2 
< 0.1 
154 

Concentration 
in the effluent 
(mg/l) 
1 053 
449 
478 
538 
0.85 
16 
43 
734 
< 0.02 
< 0.01 
< 0.05 
< 0.02 
0.10 
< 0.001 
< 0.02 

Other experiment results from laboratory trials with slurry are presented below.  

Table 6.5:  Efficiency of a combination of electro-coagulation and electro-oxidation in laboratory 

trials 

Parameter 

Concentration in slurry 
(mg/l) 
12 300 
6 200 
4 350 

COD 
Total N 
N-NH4 
Source: [ 594, Agro Business Park 2011 ] 

Concentration in the effluent 
(mg/l) 
86 
22 
4 

Efficiency  
(%) 
99.3 
99.9 
99.9 

Intensive Rearing of Poultry or Pigs 

767 

 
 
 
 
 
 
 
 
 
 
 
Chapter 6 

Economics 
The  operational  cost  that  has  been  reported  for  a  mobile  unit,  including  the  separation  and 
electro-coagulation/flotation, is reported to be EUR 12/m3 of slurry. 

Example plants 
A mobile system in Flanders operating at a capacity of 60 000 m3/year for 8 hours per day. 

Reference literature 
[ 256, VITO 2006 ] [ 594, Agro Business Park 2011 ] 

6.3.4 

Struvite precipitation  

Description 
The  technique  aims  to  recover  nitrogen  and  phosphorus  from  slurry  in  the  form  of  an 
amorphous  magnesium-nitrogen-phosphate  salt  called  struvite  (MgNH4PO4·6H2O).  It  is 
naturally  found  in  the  excreta  of  seabirds,  which  is  a  valuable  and  slow  nitrogen-releasing 
fertiliser for field crops. It forms as a calcified substance in pipes at waste water treatment plants 
but  can  also  be  recovered  from  animal  manures,  via  a  crystallisation  process,  and  reused 
separately.  

Achieved environmental benefits 
A nutrient concentration that can enhance the management of manure/slurry, especially in areas 
with a nutrient surplus. 

Cross-media effects 
Stirring needs a small amount of additional energy.  

Environmental performance and operational data 
To obtain struvite from animal manure, the magnesium content has to be increased by a factor 
of six (by introduction of the Mg+2 ion, for instance in the form of Mg(OH)2 or MgCl2·6H2O) 
and  the  phosphorus  content  by  a  factor  of  three  or  four  by  addition  in  a  soluble  form.  The 
resultant  crystallised  sludge  in  the  reactor  is  easily  removed  at  the  end  of  the  process.  pH 
adjustment will often be necessary to force the process (8.5–10).  

Applicability 
The  precipitation  of  phosphates  from  pig  slurry  appears  difficult  because  90 %  of  the 
phosphates in pig slurry are not present in a soluble form. Therefore, a preceding biological or 
chemical  treatment  is  always  needed.  Applicability  is  limited  as  it  is  not  considered  cost-
effective  in  comparison  with  aerobic  digestion  and  mechanical  phase  separation  for  a  similar 
rate of nitrogen and phosphorus removal. 

Economics 
Investment  costs  from  a  pig  slurry  pilot  plant  are  reported  to  range  from  EUR 4.85  to 
7.25 per m3.  In  a  facility  capable  of  treating  10 m3  of  pig  manure  daily,  the  operating  cost  of 
electric power can be estimated as EUR 500–1 000 per year. The total cost of chemicals needed 
for the precipitation of 1 m3 of pig slurry (with the assumption that the nitrogen concentration in 
manure is 8 kg per m3) is reported to be EUR 48 ([ 203, ADAS 2005 ]). The commercial value 
of  the  final  product  is  unlikely  to  cover  the  investment  and  operating  costs.  A  modified 
precipitation process has been considered where phosphorus is a serious local pollutant.  

Driving force for implementation 
Struvite  can  be  used  directly  as  a  fertiliser  with  a  slow  release  of  nutrients.  Dried  struvite, 
depending  on  the  nutrient  concentration,  can  represent  an  income  of  EUR 200  per  tonne. 
Struvite precipitates as crystals that can be removed as a dry product which can be transported 
as a stable fertiliser. This is favoured where phosphorus removal is important. 

768 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Example plants 
The technique is reported to be in use in the Netherlands in cattle manure processing plants (in 
cattle manure half of the phosphates are in soluble form). 

Reference literature 
[ 203, ADAS 2005 ] [ 256, VITO 2006 ] [ 594, Agro Business Park 2011 ] 

Chapter 6 

Intensive Rearing of Poultry or Pigs 

769 

 
 
 
 
Chapter 6 

6.4  Manure landspreading 

6.4.1 

P Index 

Description 
The  purpose  of  a  P  Index  is  to  assess  the  risk  of  the  release  of  phosphorus  to  surface  waters 
and/or to measure the soil phosphorus content, thus avoiding excessive build-up of phosphorus 
in soils. 

The  index  is  an  empirical  model  for  weighing  several  risk  parameters  into  a  combined  risk 
factor.  It  is  calculated annually,  using  specific  parameters for a  given  field.  In  addition  to  the 
crop  requirements  for  phosphorus,  the  formula  considers,  for  example,  run-off  components 
(based on soil tests, rate time and the method of manure application), as  well as internal field 
drainage components (e.g. the presence of tiles, water flow to tile lines, surface water recharge 
to subsurface flow, soil tests). Furthermore, the P Index considers parameters such as sheet and 
rill  erosion,  phosphorus  enrichment,  total  soil  phosphorus,  filter  strip,  sediment  delivery, 
distance  to  a  stream,  the  long-term  biotic  availability  of  particulate  phosphorus  in  a  surface 
water ecosystem, etc. 

Achieved environmental benefits 
The index is a tool to help conservation planners, landowners and land users to evaluate the risk 
of  phosphorus  reaching  surface  waters  from  a  specific  site,  and  to  determine  which  factors 
present the highest risks and should therefore be considered. 

Environmental performance and operational data 
A nationally or regionally developed P Index methodology would be preferred, as the relevance 
of  the  parameters,  as  well  as  the  associated  phosphorus  loss  risk,  varies  between  regions  and 
countries. Practical examples are reported below. 

Denmark: a P Index has been developed by researchers and tested in cooperation with the farm 
advisory service with positive results. The index tool is web-based, consisting of precalculated P 
Index maps covering all of Denmark as well as phosphorus mitigation planning tools. The major 
challenges to face before its implementation at farm level are the lack of data (mainly on soils' 
phosphorus  status),  and  the  need  for  additional  validation  of  the  model.  The  user  interface 
requires some practice for prior knowledge. 

Finland: researchers have sound experience and competence in assessing risks for  phosphorus 
losses through modelling and research on erosion. Nevertheless, no P Index has been developed 
yet.  

Germany:  two  tools  were  developed  and  introduced  as  official  regulations  in  2010:  the  'risk 
maps  associated  with  compulsory  use  of  cultivation  practices'  and  the  'P  balance  calculation'. 
These  P  measures  are  not  similar  to  a  P  Index,  but  focus  on  the  P  balance,  and  they  are 
considered more advanced than a mere P norm. 

Norway: a P Index has been developed which is used on a voluntary basis by farmers and their 
advisers.  It  is  simple  and  effective  in  its structure,  has  an  introductory  presentation  via  a  web 
tool and has been proven in practical use. Farmers and their advisers can test the effects on the P 
Index calculation of different management practices. 

Sweden: a P Index has been developed and tested in practice, but has not yet been implemented 
in agricultural practices. The large amount of baseline data and the individual software required 
discouraged  the  practical  implementation  of  the  system  at  farm  level.  On  the  other  hand,  the 
existing  Swedish  regulation  of  maximum  animal  density  in  combination  with  the  flat-rate  P 
norm  is  acknowledged  within  the  research  community  as  a  very  effective  way  to  avoid  high 
phosphorus surpluses. 

770 

Intensive Rearing of Poultry or Pigs 

UK: a P Index is used to express the phosphorus status of soils in relation to crop requirements 
when fertiliser planning [ 500, IRPP TWG 2011 ]. 

Chapter 6 

Reference literature 
[ 619, Baltic Sea 2020 2011 ] 

Intensive Rearing of Poultry or Pigs 

771 

772 

Intensive Rearing of Poultry or Pigs 

7  CONCLUDING REMARKS AND RECOMMENDATIONS FOR 

FUTURE WORK 

Timing of the review process 
The key milestones of the review process are summarised in Table 7.1. 

Chapter 7 

Table 7.1:  Key milestones of the review process of the BREF for the Intensive Rearing of Poultry 

or Pigs 

Key milestone 

Reactivation of the TWG 

Call for wishes 

Kick-off meeting 
Data collection 

First draft of revised IRPP BREF 
End of commenting period on first draft 
(2 000 comments received) 
Second draft of revised IRPP BREF 
End of commenting period on second 
draft (2 737 comments received) 
Final TWG meeting 

Date 
13 March 2008 

8 May 2008 

29 June – 1 July 2008 
February 2010 

14 March 2011 

20 May 2011 

1 August 2013 

21 October 2013 

17–21 November 2014 

During the review process, more than 10 site visits in six EU Member States were carried out, 
comprising farms of various sizes, configurations and levels of complexity. 

Sources of information and information gaps 
During  the  review  of  the  BREF  for  the  Intensive  Rearing  of  Poultry  or  Pigs  (IRPP  BREF), 
around 4 700 comments were made by the TWG. The data collection exercise provided a large 
basis  for  emissions  data  and  techniques  in  use  at  the  farm  level.  All  these  documents  were 
assessed  by  the  EIPPCB.  As  a  result,  more  than  710  documents  are referenced  in  the  revised 
IRPP BREF (see Section 10). 

Degree of consensus reached during the information exchange 
A  high  degree  of  consensus  was  reached  on the  BAT  conclusions.  However,  some  dissenting 
views were raised, as described in the following table. 

Intensive Rearing of Poultry or Pigs 

773 

Chapter 7 

Table 7.2: 

Split views 

BAT 
conclusion 

BAT 30 

BAT 30 

TWG member 

Expression of the split view 

Germany and 
European 
Environmental 
Bureau 
Germany, 
Denmark, the 
Netherlands, 
Sweden, Finland, 
European 
Environmental 
Bureau 

Germany  and  the  European  Environmental  Bureau 
expressed a dissenting view that the applicability of air 
cleaning systems for new fattening pig plants should be 
set as 'generally applicable'. 

A  dissenting  view  was  expressed  by  Germany, 
Denmark,  the  Netherlands,  Sweden,  Finland  and  the 
European Environmental Bureau who consider that the 
upper  end  of  the  BAT-AEL  range  for  ammonia 
emissions to air from an animal house for fattening pigs 
should be 2.2 kg NH3/animal place/year. 

Germany  and  the  Netherlands  expressed  a  dissenting 
view that the applicability of the technique 'Store solid 
manure on field heaps placed away from surface and/or 
underground  watercourses  which  liquid  run-off  might 
enter’ should be changed to read 'Only applicable as a 
direct logistic preparation of landspreading activities for 
a restricted time span (e.g. four weeks without covering 
and  three  months  with  covering)  and  with  a  suitable 
substrate to reduce pollution risks. Field heap locations 
should  be  changed  at  least  every  year.  Sufficient 
storage  capacity  on  the  farm  according  to  BAT  13.d 
must always be provided'. 
Germany, 
the  European 
Environmental  Bureau  expressed  a  dissenting  view  by 
proposing  to  delete  footnote  (2)  in  Table 5.3  related  to 
the  BAT-associated  time  delay  between  landspreading 
of solid manure or slurry and incorporation into the soil. 
The  European  Environmental  Bureau,  supported  by 
Austria,  Finland  and  Denmark,  expressed  a  dissenting 
view  that  housing  systems  with  fully  slatted  floors 
should not be applicable to new plants for fattening pigs 
and  weaners.  The  split  view  is  supported  by  the 
Netherlands only for fattening pigs. 

the  Netherlands 

and 

BAT 15 

Germany, the 
Netherlands 

BAT 22  

BAT 30 

Germany, the 
Netherlands and 
European 
Environmental 
Bureau 

European 
Environmental 
Bureau, Austria, 
Finland, Denmark, 
the Netherlands 

Consultation  of  the  Forum  and  subsequent  formal  adoption  procedure  of  the  BAT 
Conclusions 
In accordance with Article 13(3) of the Directive, the Forum gave its opinion on the draft Best 
Available Techniques (BAT) reference document for the Intensive Rearing of Poultry or Pigs at 
its meeting of 19 October 2015:  

1. The Forum welcomed the draft Best Available Techniques (BAT) reference document for the 
Intensive Rearing of Poultry or Pigs as presented by the Commission.  
2. The Forum acknowledges the discussions held at its meeting of 19 October 2015 and agrees 
that  the  changes  to  the  draft  Best  Available  Techniques  (BAT)  reference  document  for  the 
Intensive Rearing of Poultry or Pigs, as proposed in Annex A, should be included in the final 
document.  
3. The forum reaffirms the comments in Annex B as representing the views of certain members 
of the forum but, on which, no consensus exists within the forum to include them in the final 
document. 

774 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Chapter 7 

Subsequently, the Commission took the opinion of the IED Article 13 Forum into account when 
preparing  the  draft  Commission  Implementing  Decision  establishing  best available techniques 
(BAT) conclusions for the Intensive Rearing of Poultry or Pigs. The IED Article 75 Committee, 
at  its  meeting  of  3  October  2016,  gave  a  positive  opinion  on  this  draft  Commission 
Implementing Decision.  

Subsequently,  the  Commission  Implementing  Decision  (EU)  2017/302  establishing  best 
available  techniques  (BAT)  conclusions  for  the  Intensive  Rearing  of  Poultry  or  Pigs  was 
adopted on 15 February 2017 and published in the Official Journal of the European Union (OJ L 
43, 21.2.2017, p. 231-279). 

Recommendations for future work 
The  information  exchange  revealed  a  number  of  issues  where  further  information  should  be 
collected during the next review of the IRPP BREF. These issues include the need to: 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Collect data on the effect of the sow productivity per year (i.e. number of suckling piglets 
produced per sow per year) on the total nitrogen excreted. 

Collect more contextual information (e.g. management of animals, nutritional measures) 
associated with ammonia emissions during the rearing of mating and gestating sows. 

Review the issue of fully slatted floors in pig housing especially in consideration of  the 
future  evolution  on  the  legal  EU  framework  and  scientific  evidence  regarding  animal 
welfare. 

Carry  out  further  investigation  on  the  effectiveness  of  benzoic  acid  to  reduce  NH3 
emissions. 

Collect  data  on  the  effects  of  slurry  acidification  on  soil  fertility,  according  to  the  soil 
type and climate.  

Collect data on ammonia emissions and the associated housing techniques applied to the 
rearing  of  ducks  and  turkeys  (including  the  distinction  between  male  and  females 
turkeys). 

Collect ammonia emission data from organic livestock production covered by Regulation 
834/2007 and on alternative rearing systems for poultry. 

Review  the  issue  on  the  use  of  biological  and  chemical  additives  and  gather  further 
information (e.g. from EFSA). 

Collect information on monitoring of dust and on the determination of emission factors 
specific to the various housing systems. 

Collect dust and odour emission data with the relevant contextual information in order to 
assess the possibility of setting BAT-AELs for dust and/or odour emissions from animal 
houses during the next review of the IRPP BREF. 

Collect ammonia emission data from manure storage and landspreading. 

Urgently  improve  the  quality  and  comparability  of  the  emission  data  reported  by  using 
monitoring methods based on national or international protocols (e.g. VERA protocol). A 
very  well  designed  and  agreed  questionnaire  to  gather  emission  data  and  contextual 
information will be a key issue for the next review of the IRPP BREF. 

Collect information on the effects of temporary field storage of solid manures on surface 
and underground water quality and soil nutrient status. 

Collect  information  and  data  on  techniques  associated  with  the  rearing  of  game  birds, 
laying hen breeders, quails and geese. 

Study  information  on  the  relationship  between  nutrition  and  odour  emissions  from  pig 
housing. 

Intensive Rearing of Poultry or Pigs 

775 

 
 
 
Chapter 7 







Collect more information on loose-housing systems for sows in the service area and for
farrowing sows.

Collect  more  information  about  the  effectiveness  of  feed  additives  on  nitrogen  and
phosphorus excretion.

Study  the  environmental  performance  of  the  whole  farm  by  collecting  nitrogen  and
phosphorus surplus and nutrient recovery data.

Suggested topics for future R&D work 
The  Commission  is  launching  and  supporting,  through  its  Research  and  Technological 
Development  programmes,  a  series  of  projects  dealing  with  clean  technologies,  emerging 
effluent  treatment  and  recycling  technologies  and  management  strategies.  Potentially,  these 
projects  could  provide  a  useful  contribution  to  future  BREF  reviews.  Readers  are  therefore 
invited to inform the European IPPC Bureau of any  research results which are relevant to the 
scope of this document (see also the fifth section of the Preface of this document). 

776 

Intensive Rearing of Poultry or Pigs 

8  GLOSSARY 

This  glossary  is  meant  to  facilitate  the  understanding  of  the  information  contained  in  this 
document.  The  definitions  of  terms  in  this  glossary  are  not  legal  definitions  (even  if  some  of 
them may coincide with definitions given in  European legislation), they are meant to help the 
reader understand some key terms in the context of their use in the specific sector covered by 
this document. 

Glossary 

This glossary is divided up into the following sections: 

I. 
II.
III.
IV.
V. 
VI.
VII.
VIII.

ISO country codes 
Monetary units
Unit prefixes, number separators and notations
Units and measures
Chemical elements
Chemical formulae commonly used in this document
Acronyms
Technical definitions

I. 

ISO country codes 

ISO code 

Member State (1) 

AT 
BE 
CZ 
DE 
DK 
ES 
FI 
FR 
IE 
IT 
NL 
PL 
PT 
SE 
UK 
(1)  The  protocol  order  of  the  Member  States  is  based  on  the 
alphabetical  order  of  their  geographical  names  in  the 
original language(s).  

Austria 
Belgium 
Czech Republic 
Germany 
Denmark 
Spain 
Finland 
France 
Ireland 
Italy 
Netherlands 
Poland 
Portugal 
Sweden 
United Kingdom 

II. Monetary units

Code(1) 

Country/territory 

Currency 

Member State currencies 
EUR 
DKK 
GBP 
(1) ISO 4217 codes.  
(2)  Includes  Austria,  Belgium,  Cyprus,  Estonia,  Finland,  France,  Germany,  Greece,  Ireland, 

euro (pl. euros) 
Danish krone (pl. kroner) 
pound sterling (inv.) 

Euro area (2) 
Denmark 
United Kingdom 

Italy, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia and Spain. 

Intensive Rearing of Poultry or Pigs 

777 

Glossary 

III.  Unit prefixes, number separators and notations 

Numbers  in  this  document  are  written  using  the  '.'  character  as  the  decimal  separator  and  the 
space as the separator for thousands. 

The symbol ~ (around; approximately) is the notation used to indicate approximation.  

The following table contains the frequently used prefixes: 

Decimal Number 

Symbol  Prefix 
k 
h 
da 
------- 
d 
c 
m 

kilo 
hecto 
deca 
------- 
deci 
centi 
milli 

10n 

103 
102 
101 
1  
10−1 
10−2 
10−3 

Word 
Thousand 
Hundred 
Ten 
One 
Tenth 
Hundredth 
Thousandth 

1 000 
100 
10 
1 
0.1 
0.01 
0.001 

IV.  Units and measures  

Unit symbol 

Unit name 

Measure name 
(Measure symbol) 

Conversion and comment 

A 
atm 
bar 
°C 
° 

cfu  

cm 
CV 
d 
db(A) or dbA 
g 
h 
ha 
HP 
J 
K 
kcal 
kg 
kJ 
kPa 
kWh 
l 

LAeq 

lux 
m 
m2 

778 

ampere 
normal atmosphere  
bar  
degree Celsius, centigrade  Temperature (T) 
degree 

Electric current 
Pressure (P) 
Pressure (P) 

colony-forming unit 

centimetre 
French tax horsepower 
day 
a-weighted decibels 
gram 
hour 
hectare 
horsepower 
joule 
kelvin  
kilocalorie  
kilogram  
kilojoule  
kilopascal 
kilowatt-hour  
litre 
equivalent continuous a-
weighted sound level 
lux 
metre 
square metre 

Slope 
Number of viable bacteria or 
fungal cells 
Length 
Power 
Time 
Sound pressure 
Weight 
Time 
Area 
Power 
Energy 
Temperature (T) 
Energy 
Weight 
Energy 
Pressure 
Energy 
Volume 

Sound exposure level 

Illuminance 
Length 
Area 

1 atm = 101 325 N/m2 
1.013 bar = 100 kPa = 1 atm 

1 ha = 104 m2 
1 HP = 746 watts 

0 °C = 273.15 K 
1 kcal = 4.19 kj 
1 kg = 1 000 g 
1 kj = 0.24 kcal 

1 kWh = 3 600 kJ 

1 lux = 1lumen/m2 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Unit symbol 

Unit name 

m3 
mbar 
mg 
min 
MJ 
mm 
MWh 
Nm3 
ouE 
Pa 
ppm 
rpm  
s 
t 

t/yr 

TEQ or 
I-TEQ 

U 

V 

vol- %  
W 
Wh 
wt-% 
yr 

cubic metre 
millibar 
milligram  
minute 
megajoule  
millimetre  
megawatt hour 
normal cubic metre  
European odour unit 
pascal  
parts per million  
Revolutions per minute 
second 
metric tonne  

tonnes per year 

international toxicity 
equivalents (dioxins and 
furans) 
enzyme unit 

Volt 

percentage by volume 
watt  
watt-hour 
percentage by weight  
year 

V.  Chemical elements  

Measure name 
(Measure symbol) 

Volume 
Pressure 
Weight 
Time 
Energy 
Length 
Energy 
Volume 
Odour concentration 
Pressure 
Composition of mixtures 
Rotational speed, frequency 
Time 
Weight 
Mass flow 
Materials consumption 

Toxicity 

Amount of enzyme 
Voltage (V) 
Electric potential 
Composition of mixtures 
Power 
Energy 
Composition of mixtures 
Time 

Glossary 

Conversion and comment 

1 mg = 10-3 g 

1 MJ = 1 000 KJ 
1 mm = 10-3 m 

at 101.325 kPa, 273.15 K 

1 Pa = 1 N/m2 
1 ppm = 10-6 

1 t = 1 000 kg or 106 g 

1 W = 1 J/s 
1 wh = 3 600 J 

Symbol 
Ca 
Cl 
Cu 
F 
Fe 
I 
K 
N 
Na 
Mg 
Mn 
P 
S 
Se 
Zn 

Name 
Calcium 
Chlorine 
Copper 
Fluorine 
Iron 
Iodine 
Potassium 
Nitrogen 
Sodium 
Magnesium 
Manganese 
Phosphorus 
Sulphur 
Selenium 
Zinc 

Intensive Rearing of Poultry or Pigs 

779 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Glossary 

VI.  Chemical formulae commonly used in this document 

Chemical 
formula 

Name 

CH4 
Ca(OH)2 
CO2 
CO 
H2SO4 
H2S 
HCl 
K2O 
NaOH 
N2 
N2O 
NH3 
NH4 
NH3-N 
NH4-N 
--N 
NO2
- 
NO3
--N 
NO3

NOX 

Methane 
Calcium hydroxide 
Carbon dioxide 
Carbon monoxide 
Sulphuric acid 
Hydrogen sulphide 
Hydrogen chloride 
Potassium oxide 
Sodium hydroxide. Also called caustic soda 
Nitrogen gas 
Nitrous oxide 
Ammonia 
Ammonium 
Ammonia (expressed as N) 
Ammonium (expressed as N) 
Nitrite (expressed as N) 
Nitrate 
Nitrate (expressed as N) 
The sum of nitrogen oxide (NO) and nitrogen dioxide (NO2), 
expressed as NO2 
Oxygen gas 
Phosphate 

O2 
P2O5 
PCDD - PCFF  Polychlorinated dibenzodioxins - Polychlorinated dibenzofurans  
SF6 

Sulphur hexafluoride 
The sum of sulphur dioxide (SO2) and sulphur trioxide (SO3), 
expressed as SO2 

SOX 

780 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
VII.  Acronyms 

List of acronyms commonly used in this document. 

Glossary 

Acronym 
ACNV 
ADEME 
ap 
BAT 
BAT-AEL 
BOD 
BOD5 
BPC  
BPEX 

BREF 

CEN 
CHP 
COD 
CP 
DAFC 
DEFRA 
DIN 
DG 
DM 
EC 
ECM REF 
EFSA 
EIPPCB 
ELV 
EMS 

EMAS 

EN 
EPA 

EPER 

E-PRTR 
ESF 
EU 
EU-15 
EU-25 
EU-27 
EU-28 
FAO 
FCR 
FEFANA 
FSF 
FYM  
GHG 
GRP 
HDPE 

IED 

IFIP 

ILF BREF  

Definition 
Automatically controlled natural ventilation 
Agence de l’Environnement et de la Maîtrise l’Énergie 
Animal place. Also see 'bird place' in Glossary VIII 
Best Available Techniques (as defined in Article 3(10) of the IED) 
Emission levels associated with the BAT (as defined in Article 3 (13) of the IED)  
Biochemical oxygen demand  
Biological oxygen demand measured using a 5-day test 
British Poultry Council 
A division of the Agriculture and Horticulture Development Board (UK) 
Best Available Techniques Reference Document (as defined in Article 3(11) of the 
IED) 
Comité Européen de Normalisation (European Committee for standardisation) 
Combined heat and power (unit) (cogeneration unit) 
Chemical oxygen demand  
Crude protein 
Danish Agriculture & Food Council 
Department for Environment, Food and Rural Affairs (for England and Wales) 
Deutsches Institut für Normung (the German national organisation for standardisation) 
Directorate-General (of the European Commission) 
Dry matter  
European Commission 
Reference document on Economics and Cross-Media Effects 
European Food Security Agency 
European Integrated Pollution Prevention and Control Bureau 
Emission limit value 
Environmental management system 
European Eco-Management and Audit Scheme (Council Regulation (EC) No 
1221/2009) 
European Norming or European Norming Standard adopted by CEN  
Environmental Protection Agency (US) 
European pollutant emission register defined in Council Decision 2000/479/EC, now 
replaced by PRTR 
European Pollutant Release and Transfer Register 
Electronic sow feeder 
European Union 
Member States of the European Union before 1 May 2004 
Member States of the European Union from 1 May 2004 until 31 December 2006 
Member States of the European Union from 1 January 2007 until 30 June 2013 
Member States of the European Union from 1 July 2013 
Food and Agricultural Organisation of the UN 
Feed conversion ratio/rate 
EU Association of Specialty Feed Ingredients and their Mixtures 
Fully slatted floor 
Farmyard manure 
Greenhouse gases 
Glass fibre-reinforced plastic 
High density polyethylene  
Directive 2010/75/EU of the European Parliament and the Council of 24 November 
2010 on industrial emissions (integrated pollution prevention and control (Recast)) 
Institut du porc Recherche et Expertise pour la filière porcine (The French Pork and Pig 
Institute) 
2003 Reference Document on Best Available Techniques for the Intensive Rearing of 
Poultry and Pigs  

Intensive Rearing of Poultry or Pigs 

781 

 
 
 
Glossary 

Acronym 

IMPEL 

INFOMIL 
IPCC 
IPPC 

IPPC 
Directive 

IRPP 
IRPP BREF 

ISO 

ITAVI 
JRC 
KTBL 
LECA 
LU 
LW 
MAFF 
MS 
NFU 
NPA 
NSP 
NVZ 
PE 
PSF 
ROM REF 
RH 
TAN 
TGU 
TSS 

TWG 

TXU 
UBA 
UNECE 
UV 
VDI 
VERA 
VOC 

WID 

Definition 
European Union Network for the Implementation and Enforcement of Environmental 
Law 
The Dutch information centre for environmental licensing 
Intergovernmental Panel on Climate Change 
Integrated Pollution Prevention And Control 
Directive 2008/1/EC of the European Parliament and of the Council of 15 January 2008 
concerning integrated pollution prevention and control (IPPC Directive) that has been 
replaced by Directive 2010/75/EU on industrial emissions (IED) 
Intensive Rearing of Poultry or Pigs 
BAT reference document for the Intensive Rearing of Poultry or Pigs 
International Organisation for Standardization. Also international standard adopted by 
this organisation 
Institut Technique de l'Aviculture (FR) 
Joint Research Centre 
Kuratorium für Technik und Bauwesen in der Landwirtschaft (DE) 
Light expanded clay aggregate 
Livestock unit  
Live weight 
Ministry of Agriculture, Fisheries and Food (UK) 
Member State of the European Union 
National Farmers' Union (UK) 
National Pig Association (UK) 
Non-starch polysaccharides 
Nitrate Vulnerable Zone 
Polyethylene (polythene) 
Partly slatted floor 
Reference Report on Monitoring of emissions from IED installations 
Relative humidity 
Total ammoniacal nitrogen 
Thermostable endo-glycanase unit 
Total suspended solids 
Technical Working Group. Group of experts composed of representatives from 
Member States, the industries concerned, non-governmental organisations promoting 
environmental protection and the Commission for the drawing up and review of BREFs 
Thermostable endo-xylanase unit 
Umweltbundesamt (Federal Environment Agency), i.e. from Germany or Austria 
United Nations Economic Commission for Europe 
Ultraviolet 
Verein Deutscher Ingenieure (the association of German engineers) 
Verification of Environmental Technologies for Agricultural Production 
Volatile organic compound 
Directive 2000/76/EC of the European Parliament and of the Council of 4 December 
2000 on the incineration of waste (Waste Incineration Directive) 

782 

Intensive Rearing of Poultry or Pigs 

 
 
 
VIII. Technical terms 

Terms are mostly in line with the 'RAMIRAN Glossary of terms on manure management 2011' 
[ 636, Ramiran 2011 ]. Other sources used are [ 445, VERA 2011 ] [ 494, EFSA 2007 ] [ 648, 
DEFRA 2011 ]. 

Glossary 

Term 
A 

Acidification 

Ad libitum 

Aerated slurry 

Definition 

The  process  by  which  soil  or  surface  waters  become  increasingly  acidic 
(lower pH), e.g. through deposition of ammonia, NOX or sulphur dioxide.  
The provision of free access to feed or water thereby allowing the animal to 
self-regulate intake according to its biological needs. 
Slurry that has undergone the process of aeration, i.e. supply of oxygen using 
special  equipment,  to  stabilise  or  purify  or  to  reduce  odour  or  nitrogen 
content. 

Aerobic processes  Biological treatment processes that occur in the presence of oxygen. 
Aerosol 

Airborne solid particles or liquid droplets. 
The  proportion  of  a  soil's  volume  that  is  filled  with  air;  a  low  air-filled 
porosity indicates poor aeration and restricted drainage. 

Air-filled porosity 

All in - all out 
system 

Amino acid 

Ammonia 

Ammonium 

Anaerobic 
processes 

Animal category 

Animal house 

Animal place 

Application rate 

Arable land 

B 

Barn 

Batch storage 

Batch system 

Bedding 

Batch system. 

implicated 

The chemical units that link together to form proteins and are of fundamental 
importance to life. 
A gas derived from urea excreted by livestock (and from uric acid excreted by 
in  acidification,  eutrophication  and  nitrogen 
poultry)  and 
enrichment of sensitive ecosystems. 
Positively charged ionic form of mineral nitrogen, present in soils, fertilisers 
and manures. It is not readily leached from soils because it is attracted to soil 
particles, but can be lost in surface run-off and macro-pore flow where there 
is  only  limited  contact  between  the  flowing  water  and  soil  surfaces. 
Ammonium in soils is converted to nitrate by the process of nitrification.  

Biological treatment processes that occur in the absence of oxygen. 

The type of animal according to species (pigs, chickens, ducks, turkeys, etc.), 
sex, age and scope of production (breeding, growing and finishing for meat, 
or egg production). 
A  general  name  for  a  building  in  which  livestock  are  kept.  Also  termed 
livestock house or livestock building. 
Space  provided  per  animal  in  a  housing  system  taking  into  account  the 
maximum capacity of the plant.  
Normally  refers  to  the  mass  (tonnes)  or  volume  (cubic  metres)  of  manure 
applied per unit area (e.g. hectare) of land. 
Land  that  is  cultivated  and  sown  with  temporary  crops  (cereals,  vegetables, 
root  or  oil  crops,  etc.),  temporary  grass  for  cutting  or  grazing,  or  is 
temporarily fallow. 

A  general  name  for  a  farm  building  used  for  housing  livestock,  storing 
machinery or crops, etc. 
Storage  method  for  manures  in  which,  once  a  quantity  of  manure  has  been 
collected, it is stored without further additions of ‘fresh’ manure. 
A  method  of  rearing  livestock  in  which  a  group  of  animals,  e.g.  broilers  or 
pigs,  of  similar  live  weight  are  put  into  a  building  or  pen  and  all  removed 
when they have grown to a specified live weight. The building or pen is then 
cleaned prior to introducing another batch. 
Material  placed  on  the  floor  of  livestock  houses  with  solid  floors  or  partly 
slatted floors to provide some comfort to the animals and to absorb moisture 
and  urine.  Commonly  straw,  chopped  straw,  sawdust,  wood  shavings,  sand, 
or peat. Rubber or plastic mats may also be provided for animals to lie on. 

Intensive Rearing of Poultry or Pigs 

783 

 
 
 
 
 
Glossary 

Term 

Bioaerosol 

Biochemical 
oxygen demand 
(BOD) 

Definition 
Aerosol containing biological organisms such as fungi,  bacteria, viruses and 
mycotoxins. 
The  quantity  of  dissolved  oxygen  required  by  microorganisms  in  order  to 
decompose  organic  matter  to  carbon  dioxide  and  water  in  a  given  liquid 
sample  at  a  certain  temperature  over  a  specific  time  period.  The  unit  of 
measurement  is  mg  O2/l.  In  Europe,  BOD  is  usually  measured  after  three 
(BOD3),  five  (BOD5)  or  seven  (BOD7)  days.  It  is  a  measure  of  the  (water) 
pollution potential of organic materials. 
Synonym of 'animal place' in poultry rearing. 
An uncastrated male pig after puberty, intended for breeding. 

Bird place 
Boar 
Breeders (poultry)  Parent stock (males and females) kept to lay eggs for hatching. 

Breeding 

Broadcast 

Broilers 
Broiler breeders 

Broiler litter 

Broiler manure 

C 

C : N ratio 

Carbohydrates 

Carcass weight 

Channel 

Chemical oxygen 
demand (COD) 

Chick 
Chicken 
Combined heat 
and power (CHP) 
plant  
Compartment 
Competent 
authority 

Composite sample 

Complete feed 

Compound feed 

Conservation 
tillage 

Crate 

Crude protein 

The production of offspring from livestock. Breeding stock are animals kept 
to produce offspring rather than for slaughter. 
Uniform  scattering  of  manure  over  the  whole  surface  of  an  area  of  land  (as 
opposed to placement in rows). 
Chickens reared for meat production. 
Parent stock (males and females) kept to lay eggs for broiler production. 
Bedding of absorbent material, e.g. sawdust, wood shavings or straw, mixed 
with droppings on the floor of buildings housing broiler chickens. 
Broiler litter 

The amount of total carbon divided by the amount of total nitrogen contained 
in  livestock  manure.  Manures  with  a  high  C : N  ratio  such  as  farmyard 
manure  usually  take  longer  to  break  down,  or  mineralise,  in  the  soil  than 
those such as slurry with a lower C : N ratio. 
Complex  organic  compounds  containing  carbon,  hydrogen  and  oxygen  that 
are  essential  to  all  living  organisms.  The  energy  stored  in  carbohydrates  is 
released to power living processes. 
Deadweight. 
A long watertight compartment often constructed beneath a slatted or gridded 
floor  in  a  building  designed  to  collect  faeces  and  urine  as  slurry  or  liquid 
manure  prior  to  discharging  under  gravity  to  longer-term  storage.  A  gate 
valve  or  sluice  gate  may  be  built  into  the  channel  to  provide  short-term 
storage. Commonly used in housing for fattening pigs. 
Amount of oxygen needed for the total oxidation of organic matter to carbon 
dioxide.  COD  is  an  indicator  for  the  mass  concentration  of  the  chemically 
oxidisable  organic  matter  (normally  referring  to  analysis  with  dichromate 
oxidation) according to ISO 15705:2002. 
A young bird about to be hatched or newly hatched. 
Most important poultry species including laying hens and broilers. 
An internal combustion engine coupled to an electricity generator. Modified 
to run on biogas, a CHP plants yields heat, through recovery from the engine 
cooling system, and electricity. 
Separate part of an animal house that can be individually ventilated. 
The authority or authorities or bodies responsible under the  legal provisions 
of the Member States for carrying out the obligations arising from the IED. 
Sample prepared by an operator or by an automatic device and that has been 
obtained by mixing several spot samples. 
Compound feed which, by reason of its composition, is sufficient for a  daily 
ration. 
A  mixture  of  at  least  two  feed  materials,  whether  or  not  containing  feed 
additives, for animal feeding in the form of complete or complementary feed.  
Any  method  of  soil  cultivation  that  leaves  the  previous  year's  crop  residue 
(such as corn stalks or wheat stubble) on fields before and after planting the 
next crop, to reduce soil erosion and run-off. 
A small pen or container for livestock, allowing very restricted movement. 
Total  protein  of  feed,  derived  by  multiplying  the  amount  of  nitrogen  by  a 
factor of 6.25 since the average nitrogen content of proteins is about 16 %. 

784 

Intensive Rearing of Poultry or Pigs 

 
Term 
D 
Deadweight 

Decommissioning 

Deep litter 

Deep pit 

Denitrification 

Diet 

Digested slurry 

Digestate  

Digestible energy 

Dirty water 

Disposal 

Drake 
Droppings 

Dry matter (DM) 

Dry sow 

Duck 
Duckling 

Dunging 

Dust 

E 
Earth-banked 
lagoon 
Effluent 

Emission 

Emission factor 

Emission limit 
value (ELV) 

End-of-pipe 
technique 

Enzyme 

Essential amino 
acids 

Definition 

Glossary 

installation 

including  decontamination  and/or 

The weight of the dressed or prepared carcass. 
The  shutdown  of  an 
dismantling. 
Faeces  or  droppings  and  urine  mixed  with  large  amounts  of  bedding  (e.g. 
straw, sawdust or wood shavings) and accumulated over a certain amount of 
time on the floor of buildings.  
An  underground  watertight  compartment  for  collecting  and  storing  liquid 
manures or slurry or poultry droppings. 
The transformation,  most commonly by bacteria, of nitrates to nitrous oxide 
and  nitrogen  gas.  An  anaerobic  process  that  occurs  in  soils  and  in  manure 
stores and in some treatment methods, after a nitrification period. 
The food offered to livestock. 
Slurry that has undergone the process of anaerobic digestion using  a special 
plant and equipment, to stabilise, purify, reduce odour and produce biogas. 
The semi-solid or liquid product of anaerobic digestion. 
Digestible  energy  (DE)  is  the  gross  energy  of  a  feed,  minus  the  energy 
content of the faeces attributable to it. 
Waste water. 
Any  operation  which  is  not  recovery  even  where  the  operation  has  as  a 
secondary  consequence  the  reclamation  of  substances  or  energy  (as  defined 
by the EC Waste Framework Directive). 
Male duck. 
Waste voided by poultry. 
The  residue  remaining  following  heating  under  standard  conditions  (usually 
around  105 °C  to  constant  weight)  to  evaporate  water.  Often  expressed  as  a 
percentage of the weight of original material. 
Adult female pig between lactations (between weaning of the piglets and the 
perinatal period). 
Usually denotes a female duck. The male is called a drake. 
A young duck, usually less than 8 weeks old. 
The deposition of faeces by livestock but often used to refer to deposition of 
faeces and urine (e.g. in an animal house or yard) by livestock. 
Small, solid particles that may remain suspended in the air for some time but 
settle out under their own weight. Includes fine particulate matter which may 
be collected by filtration from indoor ambient air or air outlet(s) of an animal 
house. It can be expressed as total dust, PM10 or PM2.5. 

Lagoon 

Liquid stream discharged from a process or a farm. 
The  direct  or  indirect  release  of  substances,  vibrations,  heat  or  noise  from 
individual  or  diffuse  sources  in  the  installation  into  the  air,  water  or  land 
(Article 3(4) of the IED).  
Emission level of a given pollutant (gases or particulates) from a given source 
(e.g. an animal house) to the atmosphere. It can be expressed as the integrated 
mass  emitted  per  time  interval  and  animal  produced  (e.g.  kg/year/animal), 
animal place (e.g. kg/year/ap) or livestock unit (e.g. ouE/s/LU). May also be 
expressed as a percentage, e.g. % total ammoniacal nitrogen or total nitrogen. 
The  mass,  expressed  in  terms  of  certain  specific  parameters,  concentration 
and/or level of an emission, which may not be exceeded during one or more 
periods of time. 
A technique that reduces final emissions or consumption by some additional 
process but does not change the fundamental operation of the core process. 
A  type  of  protein  present  in  living  organisms  that  catalyses  (speeds  up) 
chemical changes without being changed itself. 
Those  amino  acids  that  cannot  be  made  by  a  plant  or  animal  but  must  be 
obtained from the environment or food. 

Intensive Rearing of Poultry or Pigs 

785 

 
 
Glossary 

Term 

Erosion (soil) 

Eutrophication 

European odour 
unit (ouE) 

Evaporation 
Excreta 

Exhaust air 

Existing farm 
Existing plant 

F 

Faecal Indicator 
Organism 

Faeces 

Fallen stock 

Farm 

Farmyard manure  

Farrowing sows 
Fattener 
Fattening 

Fattening pigs 

Feed 

Feed additives  

Feed composition 

Feed conversion 
rate 

Feed conversion 
ratio 

Feed material 

Definition 
Wearing  away  and  loss  of  soil,  principally  topsoil,  by  wind  and  running 
water. 
Process of nutrient enrichment in water or soil, resulting in oxygen depletion 
in aquatic ecosystems, loss of biodiversity, etc. Especially refers to the impact 
of ammonia and NOX emissions on terrestrial ecosystems over large parts of 
Europe. 
The  unit  of  measurement  for  odour  concentration.  1  ouE  corresponds  to  the 
amount of odorant(s) that, when diluted into one cubic metre of neutral gas at 
standard  conditions,  elicits  a  physiological  response  from  a  panel  of  people 
(detection  threshold)  equivalent  to  that  elicited  by  one  European  Reference 
Odour  Mass  (EROM)  evaporated  in  one  cubic  metre  of  neutral  gas  at 
standard conditions. One EROM is equivalent to 123 μg n-butanol. 
Physical process by which a liquid is changed into a gas. 
Waste expelled from the body: faeces plus urine. 
Airstream  discharged  from  an  animal  house  contaminated  with  gaseous  or 
particulate components, normally with low concentrations. 
A farm which is not a new farm. 
A plant which is not a new plant. 

Microorganisms  excreted  by  and  present  in  livestock  excreta  and  manures. 
Their presence in water indicates contamination by excreta manure; E. coli is 
the most commonly used faecal indicator organism. 

Solid waste or undigested material voided by animals. 
Animals  which  have  been  killed  by  euthanasia  with  or  without  a  definite 
diagnosis  or  which  have  died,  including  stillborn  and  unborn  animals,  on  a 
farm  or  on  any  premises  or  during  transport,  but  which  have  not  been 
slaughtered  for  human  consumption  (from  draft  regulation  on  aids  to 
farming). 
An installation as defined in Article 3(3) of Directive 2010/75/EU where pigs 
or poultry are reared. 
Faeces and urine mixed with large amounts of bedding (usually straw) on the 
floor of pig housing.  
Sows between the perinatal period and weaning of the piglets. 
Farm that rears fattening pigs. 
Rearing of livestock for meat production. 
Production  pigs  typically  reared  from  a  live  weight  of  30 kg  to  slaughter  or 
first service. This category includes growers, finishers and gilts that have not 
been serviced. 
Any  substance  or  product,  including  additives,  whether  processed,  partially 
processed or unprocessed, intended to be used for feeding animals. 
Substances,  microorganisms  or  preparations,  other  than  feed  material  and 
premixtures,  which  are  intentionally  added  to  feed  or  water  in  order  to 
perform, in particular, one or more of the functions mentioned in Article 5(3) 
of Regulation (EC) No 1831/2003. 
Descriptions  of  the  individual  ingredients  that  constitute  a  feed  formula  and 
their nutritional value. 

Feed conversion ratio. 

A measure of an animal's efficiency at converting feed mass into increases of 
the desired output, e.g. the amount of feed (kg) needed for 1 kg growth of live 
weight. 
Products  of  vegetable  or  animal  origin,  whose  principal  purpose  is  to  meet 
animals’  nutritional  needs,  in  their  natural  state,  fresh  or  preserved,  and 
products  derived  from  the  industrial  processing  thereof,  and  organic  or 
inorganic  substances,  whether  or  not  containing  feed  additives,  which  are 
intended for use in animal feeding either directly as such, or after processing, 
or in the preparation of compound feed, or as a carrier of premixtures. 

786 

Intensive Rearing of Poultry or Pigs 

 
Glossary 

Term 
Feedstuff 

Fertiliser 

Fertiliser 
requirement 

Fertiliser value 

Field drainage 

Definition 
Feed. 
Any  natural  or  manufactured  material  applied  to  the  soil  in  order  to  supply 
one  or  more  plant  nutrients.  The  term  is  generally  applied  to  inorganic 
materials that are commercially available. 
The amounts of plant nutrients needed, in addition to those already contained 
in the soil, to obtain a desired, optimum crop yield. 
The value or worth of manure (e.g. EUR/m3) based on the cost of providing 
the  same  quantities  of  plant  nutrients  that  it  contains  as  mineral  fertiliser.  It 
should  be  stated  whether  this  is  based  on  plant  available  nutrients  or  plant 
available nutrient content. 
The construction of drains in or under the field to remove surplus water from 
the land to a ditch. 
A heap or stack of solid manure stored in a field prior to spreading. 
Growth stage of pigs, between about 50–60 kg and slaughter. 
Finisher. 
Mixture of combustion products and air generated by an incineration process. 

Field heap 
Finisher (pigs) 
Finishing pig 
Flue-gas 
Forced ventilation  Mechanical ventilation. 

Fogging 

Foraging 

Free-range 

Fresh manure 

Front-end loader 

Water spraying at high pressure to produce fine droplets that absorb heat and 
reduce indoor dust concentration.  
The  behaviour  of  animals  when  they  are  moving  around  in  such  a  way  that 
they  are  likely  to  encounter  and  acquire  food  for  themselves  or  their 
offspring. 
A system for keeping livestock in which the animals are allowed to run free 
over a field or an area of land. For poultry it means the birds have free access 
to an outside area during the daytime but are usually housed at night. 
Manure (solid manure or slurry) immediately after removal from the livestock 
housing.  
A  large  shovel  or  bucket  mounted  on  loading  arms  at  the  front  of  a  tractor 
used for handling solid manure. The bucket may have a few short spikes with 
a back plate or may consist of many long spikes with a back plate.  

Fully slatted floor  A floor where the whole area is slatted. 

Functional areas 

G 
Gestating sows 
Gilt 
Grassland 

Greenhouse gases  

Goose 

Groundwater 

Grower (pigs) 

Areas  of  living  space  that  are  dedicated  to  feeding,  drinking  and  resting  or 
exercising due to the presence of specific equipment. 

Pregnant sows, including gilts. 
A young female pig before she has produced a litter. 
Land covered by herbaceous vegetation that is dominated by grass. 
Gases  that  contribute  to  the  greenhouse  effect  and  global  warming.  They 
include carbon dioxide, methane and nitrous oxide. 
Large  aquatic  bird  sometimes  kept  as  a  domestic  animal  for  meat  and  for 
feathers. 
Part  of  subsurface  water  in  the  zone  of  saturation.  The  upper  surface  of  the 
saturated zone is called the water table. 
Pig from about 28–30 kg live weight fed a diet to achieve high growth rates to 
about 50–60 kg live weight. 

Growers/Finishers  Fattening pigs. 

Guinea fowl 

H 

Heavy metals 

A  pheasant-like  bird  from  Africa  reared  for  ornamental  qualities,  meat, 
feathers for crafts and fly tying, or vermin control. 

A  group  of  metallic  elements  that  include  lead,  cadmium,  zinc,  copper, 
mercury  and  nickel.  Technical  literature  describes  these  as  metals  with  a 
density  greater  than  4.5  g/ml.  They  can  be  found  in  considerable 
concentrations in sewage sludge and several other waste materials as well as 
in smaller concentrations in pig and poultry manure.  

Intensive Rearing of Poultry or Pigs 

787 

 
 
 
Glossary 

Term 

Housing system 

Hygienisation 

I 

Insulation 

Intensive 
production 

Ionisation 

K 

Kennel 

L 
Lactating sow 
Layer 

Layer breeder 

Laying hens 
Leachate 

Leaching 

Liquid fraction 

Liquid manure 
Litter 

Livestock 

Livestock unit 
(LU) 

Live weight 

M 

Definition 
A unit with the primary function of providing housing for a specified animal 
category,  and  with  a  specific  design,  equipment  and  management  that 
determines  its  environmental  performance.  It  includes  the  way  a  certain 
animal  category  is  kept  (e.g.  pen  and  floor  design),  the  manure  storage  and 
management  system,  the  ventilation  system  installed  to  control  the  indoor 
climate  in  the  building  and  the  type  and  regime  used  to  provide  feed  and 
water to the animals. 
Sanitation. 

The  prevention  of  the  passage  of  heat  in  or  out  of,  for  example,  a  livestock 
building  by  incorporating  non-heat-conducting  material  into  the  walls  and 
roof. 
Farming characterised by high inputs of capital and resources, etc. that aims 
to make the best use of the genetic potential of crops and livestock to achieve 
high outputs. 
An  electrostatic  field  is  created  in  the  house  to  produce  negative  ions. 
Circulating airborne dust particles are charged by free negative ions; particles 
are  collected  on  the  floor  and  room  surfaces  by  gravitational  force  and 
electrostatic field attraction. 

A type of pig pen, usually for weaners. It includes a sleeping section  with a 
hinged  roof  that  can  be  raised  or  lowered  to  control  temperature  and 
ventilation. 

A sow having recently given birth and producing milk. 
Laying hen. 
Parent stock (males and females) kept to produce fertile eggs for commercial 
laying hen production. 
Grown female chickens for egg production after 16 to 20 weeks of age. 
Solution obtained by leaching.. 
The  loss  of  soluble  elements  and  compounds  from  a  porous  material  (e.g. 
soil)  in  drainage  water  to  the  aqueous  environment  including  groundwater. 
This applies especially to nitrate leaching. 
Varying  degrees  of  separation  of  solids  and  liquid  may  occur  during  the 
management  of  manures,  giving  rise  to  liquid  and  solid  fractions.  There  are 
no  specific  terms  to  denote  the  different  types  of  liquid  fractions  but  their 
properties vary with the proportions of urine, faeces, bedding and water that 
they contain. They include: i) seepage or drainage from manure in livestock 
houses or on concrete surfaces used by livestock, ii) seepage or drainage from 
solid manure stores, iii) liquid from a strainer box in a slurry lagoon or from a 
weeping  wall  store,  iv)  liquid  derived  from  the  mechanical  separation  of 
slurry,  v)  clarified  liquid  (or  supernatant)  obtained  from  the  upper  layer 
following  the  settlement  of  slurry  in  a  lagoon,  and  vi)  thickened  liquid 
remaining following the settlement of slurry in a lagoon and the removal of 
the upper layer of clarified liquid (supernatant). 
Slurry 
All the piglets born at one birth. 
Domesticated  animals  such  as  cattle,  pigs,  poultry,  sheep,  horses  and  goats. 
Any  creature  kept  for  the  production  of  food,  wool,  skin  or  fur  or  for  the 
purpose of its use in the farming of the land or for amenity purposes. 
A unit used to compare or aggregate numbers of animals of different species 
or  categories.  1  LU  often  equals  500  kg  live  weight  of  an  animal.  Other 
equivalences can be defined on the feed requirements (or sometimes nutrient 
excretion). 
The  weight  of  a  live  animal  (as  opposed  to  the  weight  of  the  carcass  or 
deadweight). 

788 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
Glossary 

Term 

Manure 

Manure belt 

Manure 
management 

Manure pit 

Manure 
processing 

Manure system 

Mating sows 

Meal 

Metabolisable 
energy 

Methane 

Microorganisms 

Mineralisation 

Minerals 

Mineral fertiliser 

Mucking out 

N 
N-balance 

Net energy 

New farm 

New plant  

Nitrate Vulnerable 
Zone 

Nitrification 

Nitrous oxide 

Definition 
A general term to denote any organic material that supplies organic matter to 
soils together with plant nutrients, usually in lower concentrations compared 
to mineral fertilisers. 
Movable  belt,  e.g.  made  of  'non-stick'  polypropylene,  below  the  cages  on 
which  droppings  from  laying  hens  are  collected  and  are  periodically 
transported outside the house to closed storage or direct application.  
The  collection,  storage,  transport  and  landspreading.  It  may  also  include 
treatment. 
An underground store with a watertight floor and walls and a solid or gridded 
lid  commonly  used  for  short-term  storage  of  liquid  manure,  slurry,  dirty 
water, etc. May be inside or outside a livestock building. 
A  controlled  biological,  chemical  and/or  physical  process  that  changes  the 
properties of the manure. 
The manure system includes the collection and removal of slurry or solids out 
of the housing system. 
Sows ready for service and before gestation. 
A feedstuff consisting of one or a mixture of finely ground ingredients such 
as cereals, oilseeds, etc. 
Metabolisable energy (ME) is the gross energy of the  feed consumed  minus 
the  gross  energy  contained  in  the  faeces,  urine,  and  gaseous  products  of 
digestion.  For  poultry  the  gaseous  products  are  usually  negligible,  so  ME 
represents the gross energy of the feed minus the gross energy of the excreta. 
A  correction  for  nitrogen  retained  in  the  body  is  usually  applied  to  yield  a 
nitrogen-corrected ME (men) value.  
A greenhouse gas produced during anaerobic fermentation of organic matter, 
especially  from  enteric  fermentation  in  ruminants  and  storage  of  liquid 
manure. A constituent of biogas. 
Living  organisms  of  microscopic  or  submicroscopic  size.  They  include 
bacteria, algae, fungi and viruses, although the latter are not considered living 
organisms. 
The  transformation  by  microorganisms  of  organic  compounds  to  inorganic 
compounds, e.g. of nitrogen/carbon in soils and stored manures. 
Inorganic  substances,  including  trace  elements,  fed  to  livestock  and  that  are 
required for the normal functioning, growth and health of the animal. 
Fertiliser  manufactured  by  a  chemical  process  or  mined,  as  opposed  to  an 
organic material (manure) that contains carbon. 
A  colloquial  term  for  removing  manure,  usually  solid  manure  such  as 
farmyard manure from a building housing livestock. 

Nitrogen mass balance. 
Net  energy  (NE)  is  metabolisable  energy  minus  the  energy  lost  as  the  heat 
increment.  ‘Heat increment’ is the heat loss of a  nourished animal in excess 
of  that  lost  by  a  fasting  animal.  NE  may  include  the  energy  used  for 
maintenance only (nem) or for maintenance and production (nem+p).  
A  farm  first  permitted  following  the  publication  of  the  BAT  conclusions  as 
defined in Article 1(12) of Directive 2010/75/EU or a complete replacement 
of a farm following the publication of the BAT conclusions. 
A plant first permitted at the site of the farm following the publication of the 
BAT  conclusions  as  defined  in  Article  1(12)  of  Directive  2010/75/EU  or  a 
complete  replacement  of  a  plant  on  the  existing  foundations  following  the 
publication of the BAT conclusions. 
Land  areas  designated  according  to  the  Nitrates  Directive  (91/676/EEC),  in 
which  nitrate  pollution  (from  agricultural  sources)  exceeds,  or  is  likely  to 
exceed, the legal limit of 50 mg NO3/litre. 
The transformation by bacteria of ammonium  nitrogen to nitrite  and  then to 
nitrate.  An  aerobic  process  that  may  occur  in  soils  and  during  aeration  of 
liquid manures. 
A greenhouse gas derived mainly from the denitrification process. 

Intensive Rearing of Poultry or Pigs 

789 

 
Glossary 

Term 

Nutrient balance 

Nutrient surplus 

O 
Odorant 

Odour 

Odour 
concentration 

Open climate 
house 
Organic matter 
(OM) 

Organic Waste 

P 

Partly slatted floor 

Particulate matter 
(PM) 

Passageway 

Pathogens 

Pen 

Perforated floor  

Pesticide 

pH 

Pheasants 

Phytase 

Definition 
A comparison between plant nutrient input and nutrient output or uptake. The 
nutrient balance can be expressed as: 
• a  supply/demand balance comparing  the amount of  nutrients entering crop 
and  grassland  production  in  the  form  of  manure  or  fertilisers  and  nutrients 
removed in products (including products not leaving the farm) or the standard 
nutrient requirement of the crop; 
•  an  import/export  balance  comparing  the  nutrients  imported  on  to  and 
exported from the farm.  
The amount of plant nutrients exceeding the amount required or taken up by 
crops, thus resulting in a positive nutrient balance. 

A chemical or gas that causes odour. 
Organoleptic attribute perceptible by the olfactory organ on detecting certain 
volatile  substances  with  very  different  chemical,  physical  and  biological 
properties. It can be a pleasant or unpleasant smell. 
The  concentration  of  an  odorant  mixture  is  conventionally  defined  as  the 
dilution factor to be applied to an effluent in order to be no longer perceived 
as  an  odorant  by  50  %  of  people  in  a  sample  of  the  population.  The  odour 
concentration  at  the  limit  of  detection  is  by  definition  1 ouE/m3.  It  is 
expressed  in  European  odour  units  per  cubic  metre  of  air  (ouE/m3)  and  it  is 
measured  by  olfactometric  analyses  in  accordance  with  the  European  CEN 
standard (EN 13725). 

An animal house with natural ventilation only. 

Residues derived from plants, animals and microorganisms in various stages 
of decomposition. 
A general term for any wastes of organic rather than inorganic origin and so 
containing carbon (e.g. livestock manure, sewage sludge). 

A  floor  that  is  partly  solid  and  partly  slatted.  Commonly  used  in  pens  for 
housing  pigs  and  designed  so  that  the  animals  defecate  and  urinate  on  the 
slatted part. 
All  airborne  inorganic  and  organic  solid  or  liquid  (droplets  and  aerosols) 
matter  that  may  be  present  in  the  exhaust  air.  This  complex  mixture  varies 
greatly in size, composition and origin. 
Usually an area with a hard surface to provide livestock (and farm staff and 
machinery) access to different parts of the building or between buildings. 
Microorganisms  that  can  cause  disease  in  humans,  animals  and  plants. 
Pathogens  include  bacteria,  viruses  and  parasites  and,  in  agriculture,  can  be 
found in manure, sewage sludge, etc. 
A small enclosure for livestock, within a house or outdoors. 
Like slatted floor, but with holes rather than slats. In poultry housing, it refers 
to a double floor where the perforations of the upper floor let dry air flow up 
through the floor in order to dry manure and litter.  
Biological, physical or chemical agent used to kill pests. The term pesticide is 
often  applied  only  to  chemical  agents.  Various  pesticides  are  known  as 
insecticides, nematicides, fungicides, herbicides and rodenticides. According 
to  the  Stockholm  Convention  on  Persistent  Organic  Pollutants,  10  of  the  12 
most dangerous and persistent organic chemicals are pesticides. 
Negative  logarithm  of  proton  (H+)  activity.  A  measure  of  the  hydrogen  ion 
concentration  of  a  solution  and  an  indication  of  its  acidity  or  alkalinity. 
Expressed on a scale from 0 to 14, 7 is neutral, and the higher values alkaline, 
and the lower values more acidic. 
A  species  of  game  bird  that  comes  in  many  breeds  and  varieties.  They  are 
raised for meat, feathers, and ornamental value or to be released into the wild 
for shooting. 
Type  of  enzyme  that  releases  inorganic  phosphorus  from  organic  forms  of 
phosphorus  (phytate)  in  grain  and  thereby  makes  the  phosphorus  more 
available to animals. 

790 

Intensive Rearing of Poultry or Pigs 

 
 
Glossary 

for  normal  plant  growth.  Usually  divided 

Definition 
An animal of the porcine species of any age, kept for breeding or fattening. 
Pigs from birth to weaning. 
A part of the farm where one of the following processes or activities is carried 
out: animal housing, manure storage, manure processing. A plant consists of a 
single  building  (or  facility)  and/or  the  necessary  equipment  to  carry  out 
processes or activities. 
Elements  needed 
into 
macronutrients  (nitrogen,  phosphorus,  potassium,  magnesium,  calcium, 
sulphur) and micronutrients (e.g. copper, zinc, manganese). 
Visible  or  measurable  discharge  of  a  contaminant  from  a  given  point  of 
origin. 
Airborne  particles  with  an  aerodynamic  diameter  of  10  micrometres  or  less 
corresponding to 50 % sampling efficiency. 
Airborne particles  with an aerodynamic diameter of 2.5  micrometres or less 
corresponding to 50 % sampling efficiency. 
The  direct  or  indirect  introduction,  as  a  result  of  human  activity,  of 
substances, vibrations, heat or noise into the air, water or land which may be 
harmful to human health or the quality of the environment, result in damage 
to material property, or impair or interfere with amenities and other legitimate 
uses of the environment. (Article 3(2) of the IED) 
The rearing phase after weaning and before growing/finishing. 
Fowl  (chickens),  turkeys,  guinea  fowl,  ducks,  geese,  quails,  pigeons, 
pheasants  and  partridges  reared  or  kept  in  captivity  for  breeding,  the 
production  of  meat  or  eggs  for  consumption,  or  for  restocking  supplies  of 
game. 
Feed  ingredient  covering  the  animals'  basic  needs  for  vitamins  and  trace 
elements  and,  possibly,  some  amino  acids  and  nutritional  additives. 
Incorporated into complete feed, e.g. for pigs. 
Complex,  organic  compound  made  up  of  amino  acids  that  contain  carbon, 
oxygen,  nitrogen,  hydrogen  and  sometimes  phosphorus  and  sulphur.  With 
water, they form the basic constituents of living cells and of the structure of 
plants and animals. 
Young  chickens  below  the  age  for  laying  eggs.  When  reared  for  egg 
production, a pullet becomes a laying hen when it begins to lay eggs at 16 to 
20 weeks of age. When reared for breeding, young male and female chickens 
are defined as pullets until 20 weeks of age.  

The allowance of food given to an animal. 

Mineral nitrogen: ammonium, nitrate and uric acid. 

The keeping of growing livestock. 
A pit that is used for short-term storage of liquid manure, slurry, dirty water, 
etc. from a livestock house prior to transfer to a main store. 
A material that is not deliberately produced in a production process and may 
or may not be waste. 
Part of the  precipitation, snowmelt,  irrigation  water, liquid  manure, etc. that 
does not infiltrate but moves as overland flow. Run-off can cause pollution by 
transporting pollutants and pathogens to surface waters. 

Term 
Pig 
Piglets 

Plant 

Plant nutrients 

Plume 

PM10 

PM2.5 

Pollution  

Post-weaning 

Poultry 

Premix 

Protein 

Pullets 

R 
Ration 
Readily available 
nitrogen 
Rearing 

Reception pit 

Residue 

Run-off 

S 

Sanitation 

Sensitive receptor 

Action  by  which  pathogenic  microorganisms  are  killed  by  heating  and/or 
addition of chemicals or irradiation. 
Area which need special protection, such as: 
- residential areas; 
- areas where human activities are carried out (e.g. schools, daycare centres, 
recreational areas, hospitals or nursing homes); 
- sensitive ecosystems/habitats. 
Barn. 

Shed 
Slaughter weight  Weight of a live animal immediately prior to slaughter. 

Intensive Rearing of Poultry or Pigs 

791 

 
 
Glossary 

Term 

Slurry 

Soil moisture 
deficit 

Soil texture 

Solid floor 

Solid fraction 

Solid manure 

Sows 
Space allowance 
Stag 
Stall 

Stocking density 

Straw 

Surface water 

Suspended solids 
(SS) 
T 

Technique 

Total ammoniacal 
nitrogen (TAN) 

Total dust 

Total Kjeldahl 
nitrogen 
Total nitrogen (or 
total N) 
Total nitrogen 
excreted 

Total phosphorus 

Total phosphorus 
excreted 
Total solids (TS) 
Total suspended 
solids (TSS) 

Trace element 

Tramline 

Triangular slats 

Turkey 
U 

792 

Definition 
Faeces  and  urine  mixed  or  not  with  some  litter  material  and  some  water  to 
give  a  liquid  manure  with  a  dry  matter  content  up  to  about  10 %  that  flows 
under gravity and can be pumped. 
The  difference  between  the  amount  of  water  actually  in  the  soil  and  the 
maximum  amount  of  water  that  the  soil  can  hold  without  resulting  in 
drainage. 
Soil  classification  based  on  the  type  and  proportion  of  particles  (sand,  silt, 
clay) that it contains. 
A continuous surface which allows full contact with and support to the lower 
surface of the animal foot. 
See  liquid  fraction  above.  Solids  or  fibrous  material  derived  from  the 
mechanical separation of slurry. The solid fraction is normally stackable.  
Faeces  or  droppings  and  urine  mixed  or  not  with  litter  material  that  do  not 
flow under gravity and cannot be pumped. 
Female pigs during the rearing periods of mating, gestating and farrowing. 
The number or body weight of animals per unit area in their accommodation. 
A male turkey. 
A division or compartment for an animal or animals, usually within a house. 
The live weight of animals which are present in a house at the same time per 
square metre of useable area. 
Dry stems of cereals after the grain has been removed. 
Water that flows in streams and rivers, natural lakes, wetlands and reservoirs 
constructed by humans. 

Suspended matter in liquid. 

+ (assuming that the amount of NH3 is insignificant).

Includes  both  the  technology  used  and  the  way  in  which  the  installation  is 
designed, built, maintained, operated and decommissioned. 
The  total  amount  of  ammonium-N  (NH4-N)  and  its  compounds,  including 
uric  acid,  which  is  readily  broken  down  to  NH4-N.  TAN  is  often  used  as  a 
synonym for NH4
All  particles  emitted  from  a  source  with  an  aerodynamic  diameter  of  500 
micrometres or less. 
Total amount of organic and reduced nitrogen compounds, excluding nitrates 
(NO3-N). 
Total nitrogen, expressed as N, includes free ammonia and ammonium (NH4-
N), nitrites (NO2-N), nitrates (NO3-N) and organic nitrogen compounds. 
Total nitrogen eliminated from animal metabolic processes through urine and 
faeces. 
Total  phosphorus,  expressed  as  P2O5,  includes  all  inorganic  and  organic 
phosphorus compounds, dissolved or bound to particles. 
Total phosphorus eliminated from animal  metabolic processes through urine 
and faeces. 
Dry matter. 
Mass  concentration  of  all  suspended  solids,  measured  via  filtration  through 
glass fibre filters and gravimetry.  
A  chemical  element  that  is  required  in  very  small  quantities  by  plants  or 
animals for normal functioning, growth and health. Include iron, zinc, boron, 
copper, manganese, cobalt and molybdenum. 
Accurately  spaced,  narrow  pathways  left  in  a  cereal  crop  for  example  to 
provide  wheel  guide  marks  for  tractors  and  machinery  used  in  subsequent 
operations, e.g. fertiliser application. 
Components of slatted floors, e.g. in pig pens, usually made of metal, plastic 
or concrete. They are triangular in cross section with the apex of the triangle 
facing down so that the slots between them are wider on the underside of the 
floor.  
Large poultry species kept for the production of meat. 

Intensive Rearing of Poultry or Pigs 

Glossary 

Term 

Urea 

Uric acid 
Urine 
V 

Ventilation rate 

Veranda 

Viscosity 

Vitamin 

Volatile fatty acids 
(VFA) 

Volatile organic 
compound (VOC) 

Volatile solids 

Volatilisation 

W 
Waiting sows 

Waste water 

Water table 

Weaners 

Weaning 
Welfare 

Working width 

Z 
Zeolites 

Zootechnical 
additives 

Definition 
The  main  end  product  of  mammalian  protein  metabolism  and  the  main 
nitrogen compound in the urine of mammals. 
The main end product of the protein metabolism of birds (poultry). 
Wastes removed from the bloodstream via the kidneys and voided as a liquid. 

This  is  usually  expressed  as  the  volume  flow  of  air  (m3/hour)  through  an 
animal house. It can be given for the whole building or per animal (place). 
Covered  area  with  open  side  walls  along  the  side  of  poultry  houses  that 
allows animals access to the outside climate for animal welfare reasons. It is 
sometimes  equipped  with  a  base  plate  covered  with  some  type  of  litter 
(scratching area) or ground covering. 
Resistance  of  a  fluid  to  a  change  in  shape  or  movement  of  neighbouring 
portions relative to one another. Viscosity denotes opposition to flow.  
A  class  of  organic  substances  required  by  animals  in  small  amounts  for 
normal  functioning,  growth  and  health.  Farm  animals  can  synthesise  some, 
e.g. Vitamin C, in their bodies but most must be provided in their diet. 
Short-chain fatty acid containing two to five carbon atoms that are produced 
as end products of microbial fermentation in the digestive tract. 
Any organic compound having at 293.15 K a vapour pressure of 0.01 kPa or 
more, or having a corresponding volatility under the particular conditions of 
use (Article 3(45) of the IED). 
The weight loss after a sample of total solids is ignited in a furnace (heated to 
dryness at 550 °C). 
The process by which ammonia gas is released from a solution. Refers to the 
loss  of  ammonia  from  urine  and  from  manure  during  housing,  storage  and 
landspreading.  

A sow waiting to be on heat before insemination. 
Rainwater  run-off  commonly  mixed  with  manure,  water  derived  from  the 
cleaning of surfaces (e.g. floors) and equipment, and water derived from the 
operation  of  air  cleaning  systems.  This  may  also  be  referred  to  as  soiled 
water. 
The level in soil below which the ground is completely saturated with water. 
Young pigs reared from weaning until fattening, typically reared from a live 
weight of around 8 kg to 30 kg. 
The time when the pigs are reared from a live weight of around 8 kg to 30 kg. 
The state of an individual as regards its attempts to cope with its environment. 
The distance between the centres of two adjacent spreading widths, each one 
achieved by a single pass of the manure spreader.  

Aluminosilicate mineral deposits that have a microporous structure. 
The  following  functional  groups  are  included,  as  per  Regulation  (EC)  No 
1831/2003: 
(a)  digestibility  enhancers:  substances  which,  when  fed  to  animals,  increase 
the digestibility of the diet, through action on target feed materials; 
(b)  gut  flora  stabilisers:  microorganisms  or  other  chemically  defined 
substances,  which,  when  fed  to  animals,  have  a  positive  effect  on  the  gut 
flora; 
(c) substances which favourably affect the environment; 
(d) other zootechnical additives. 

Intensive Rearing of Poultry or Pigs 

793 

794 

Intensive Rearing of Poultry or Pigs 

Annexes 

9  ANNEXES 

9.1  Animal species and livestock units (LU) 

In the evaluation of the environmental impact of intensive livestock farms, the term 'place' may 
lead to confusion. A place can be considered equal to one animal, but there is a difference in the 
extent of environmental effects from keeping different kinds of animals belonging to the  same 
species but of different kinds and at different stages of production. For example, hens, broilers, 
ducks and turkeys all belong to the species 'poultry', but the environmental effects of farms with 
these kinds of animals and the same number of places are considerably different. In addition, it 
makes a difference whether young animals are reared or older animals are fattened.  

To overcome these problems, animal places can be expressed in terms of animal mass (livestock 
units - LU, e.g. 1 LU = 500 kg animal mass), as environmental effects depend strongly on the 
average animal mass during a production period. Animal  masses correspond approximately  to 
manure production and emissions. They may be defined as the time-integrated average animal 
mass  over  a  production  period  or  cycle  on  the  basis  of  the  animal-specific  growth  function, 
which is  available for every  kind  of  animal. This  enables different  types (breeding,  fattening) 
and  stages  (weaning,  growing-finishing)  of  production,  housing  periods  and  changing 
production processes to be taken into consideration. 

Some examples of standard values  for LU as reported by Member States are  presented below 
(Table 9.1, Table 9.2, Table 9.3).  

Table 9.1: 

Standard values for the calculation of live animal mass in LU, used in Germany 

Animal category 

Pigs 

Average live animal 
mass in LU/animal 

Fattening pigs (25–110 kg) 
Fattening pigs (25–115 kg) 
Fattening pigs (25–120 kg) 
Early-pregnant and non-pregnant sows, boars (150 kg) 
Sows with piglets (up to 10 kg) 
Sows with piglets (up to 14 kg) 
Sows with piglets (up to 18 kg) 
Weaners (up to 15 kg) 
Weaners (up to 25 kg) 
Weaners (up to 30 kg) 
Young sows (up to 90 kg) 

Poultry 

Laying hens 
Young hens - rearing (until the 18th week) 
Broilers (up to 35 days) 
Broilers (up to 42 days) 
Broilers (up to 49 days) 
Ducks - rearing (Pekin ducks) 
Ducks - fattening (Pekin ducks) 
Flying ducks - rearing 
Flying ducks - fattening 
Turkeys - rearing 
Turkeys - fattening (hens) 
Turkeys - fattening (cocks) 
Turkeys - fattening (mixed males and females) 
NB: 1 LU corresponds to a standardised live animal mass of 500 kg 

Source: [ 474, VDI 2011 ] 

0.13 
0.14 
0.15 
0.30 
0.40 
0.45 
0.50 
0.02 
0.03 
0.04 
0.12 

0.003 4 
0.001 4 
0.001 5 
0.002 0 
0.002 4 
0.001 3 
0.003 8 
0.001 2 
0.005 0 
0.002 2 
0.012 5 
0.022 2 
0.016 

Intensive Rearing of Poultry or Pigs 

795 

Annexes 

Table 9.2: 

Standard values for the calculation of live animal mass in LU, used in Spain 

Animal category 

Pigs 

Sows in a farrow-to-finish farm (1) 
Sows with piglets until 6 kg 
Sows with piglets until 20 kg 
Weaners 6 to 20 kg 
Fattening pigs (Growers) 20 to 50 kg 
Fattening pigs (Finishers) 50 to 100 kg 
Fattening pigs 20 to 100 kg 

Poultry (2) 

Average live animal mass 
in LU/animal 

2 
0.25  
0.30 
0.02 
0.08 
0.10 
0.09 

0.007 
Broilers 
0.021 
Turkeys 
0.014 
Laying hens 
Partridges, quails and pheasants 
0.003 5 
(1) Includes all offspring of the sow until the end of the fattening period. 
(2) Values used in the region of Andalusia. 
NB: 1 LU corresponds to an adult cow. 
Source: [ 500, IRPP TWG 2011 ] [ 624, IRPP TWG 2013 ] 

Table 9.3: 

Standard values for the calculation of live animal mass in LU, used in the UK 

Animal category  

Average live animal mass 
in LU/animal 

Pigs 

Sows 
Farrowing sows  
Boars 
Fattening pigs > 110 kg 
Fattening pigs 20–110 kg 
Piglets < 20 kg 

0.4 
0.45 
0.5 
0.24 
0.13 
0.06 

Poultry 

Laying hens  
Broilers 
Pullets 
Breeding hens 
NB: Calculated values. 1 LU corresponds to a standardised live animal mass of 

0.004 4 
0.001 8 
0.002 
0.004 

500 kg. 

Source: [ 614, UK 2013 ] 

In order to compare or aggregate numbers of  the various categories of livestock, equivalences 
based on the feed requirements of the animals can also be defined. In this case livestock units 
are defined on the basis of the feed requirements of the individual animal categories (Table 9.4). 

Other equivalences can be defined based on nutrient excretion. 

796 

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Table 9.4:  Livestock unit coefficients used by Eurostat 

Animal category 

Bovine 

Under 1 year old 
1–2 years old 
Male, 2 years old and over 
Heifers, 2 years old and over 
Dairy cows 
Other cows, 2 years old and over 

Pigs 

Piglets with a live weight of under 20 kg 
Breeding sows weighing 50 kg and over 
Other pigs 

Poultry 

Laying hens 
Broilers 
Ostriches 
Other poultry 

Annexes 

Average live animal 
mass in LU/animal 

0.400 
0.700 
1.000 
0.800 
1.000 
0.800 

0.027 
0.5 
0.3 

0.014 
0.007 
0.35 
0.03 

Other 

Sheep and goats 
Equidae 
Rabbits, breeding females 
NB:  1  LU  corresponds  to  the  grazing  equivalent of  one 600  kg  dairy  cow 
producing 3 000 kg of milk annually, without additional concentrated 
foodstuffs. 

0.8 
0.1 
0.02 

Source: [ 12, Eurostat 2015 ] 

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9.2 

Examples of phase feeding programmes  

Applied feeding programmes are reported in the following sections. 

9.2.1 

Multiphase feeding for poultry  

9.2.1.1 

Pullets 

Table 9.5:  Multiphase feeding for pullets in the UK 

Parameter 
Period (weeks) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
NSP enzymes (%) 
Source: [ 298, UK 2010 ] 

Phase 1 
0–6 
20 (19–21) 
1 (0.9–1.1) 
1 (0.9–1.2) 
0.5 (0.5–0.6) 
15 (10–25) 
60 (40–80) 
0.018 (0–0.018) 
0.005 (0–0.01) 

Phase 2 
7–12 
18.5 (18–19) 
0.85 (0.8–0.95) 
0.9 (0.9–1.2) 
0.5 (0.5–0.6) 
15 (10–25) 
60 (40–80) 
0.018 (0–0.018) 
0.005 (0–0.01) 

Phase 3 
13–16 
16 (15–17) 
0.65–0.8 
0.9 (0.9–1.2) 
0.45 (0.4–0.55) 
15 (10–25) 
60 (40–80) 
0.018 (0–0.018) 
0.005 (0–0.01) 

Table 9.6:  Multiphase feeding for pullets (free range) in the UK 

Parameter 
Period (weeks) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
NSP enzymes (U/kg) 
Source: [ 294, UK 2010 ] 

Phase 1 
0–8 
19 
1 
0.95 (0.95–1) 
0.741 
15 
70 
0 
500 

Phase 2 
8–12 
16.5 
0.8 
0.95 (0.95–1) 
0.76 
15 
70 
0 
500 

Phase 3 
12–16 
15.5 
0.7 
0.95 (0.95–1) 
0.76 
15 
70 
0 
500 

Table 9.7:  Multiphase feeding for pullets in Germany 

12 

11.4 

11–11.4 

Phase 2 
4–8  

Phase 4 
16/17  

Phase 1 
1–3  

Phase 3 
9–15/16  

20–21 
0.4–0.48 

Parameter 
Period (weeks) (1) 
Metabolisable energy 
(MJ/kg) 
Crude protein (%) 
Amino acids (%) (2) 
Amino acid profile 
(Met : Lys : Val : Thr : Trp) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
NSP enzymes (%) (3) 
(1) The body weight, rather than simply the age, determines the right time to change the feed. Chicks and pullets are 

0.95–1.05 
0.75–0.75 
6–6.2 
44–60  
500 (250–750) 
0.005–0.01 

0.9–0.92 
0.58 
6–6.2 
39–40 
500 (250–750) 
0 

0.95–1 
0.7–0.7 
6–6.2 
44–60 
500 (250–750) 
0 

2–2.25 
0.65–0.65 
6–6.2 
40–44 
500 (250–750) 
0 

16–17.5 
0.34–0.37 

18–18.5 
0.37–0.42 

14.5–16 
0.31–0.39 

1 : 1.9 : 1.6 : 1.5 : 0.5 

11.2–11.4 

weighed once a week. 

(2) Data refer to methionine (first limiting amino acid). 
(3) The enzyme activity ranges from 280/125 to 560/250 TXU/TGU (xylanase/glucanase) per kg of feed.  
NB: Unrestricted (ad libitum) dry feed/pelleted feed. 

Source: [ 327, Germany 2010 ] 

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Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
9.2.1.2 

Laying hens 

Table 9.8:  Multiphase feeding for laying hens (in cages) in the UK 

Annexes 

Parameter 
Period (weeks) 
Crude protein (%) 

Amino acids (%) 

0.9 (0.7–1) 

0.9 (0.85–1) 

Phase 4 
56–70 
15–17 

Phase 2 
29–40 
16.5–19 

Phase 3 
41–55 
16–18 

Phase 1 
16–28 
17 (16–18) 

Phase 5 
>71  
13–16 
0.65 (0.6–
0.75) 
4 (3.8–4.4) 
3.8 (3.6–4.2) 
0.4 (0.38–0.5) 
0.45 (0.4–0.5) 
15 (10–20) 
15 (10–20) 
60 (40–100) 
60 (40–100) 
0.018 (0–0.18)  0.018 (0–0.18)  0.018 (0–0.18)  0.018 (0–0.18)  0.018 (0–0.18) 
0.005 (0–0.01)  0.005 (0–0.01)  0.005 (0–0.01)  0.005 (0–0.01)  0.005 (0–0.01) 

4 (3.8–4.4) 
0.45 (0.4–0.5) 
15 (10–20) 
60 (40–100) 

3.6 (3.5–4) 
0.45 (0.4–0.5) 
15 (10–25) 
60 (40–100) 

0.72 (0.7–0.8) 

0.8 (0.7–0.9) 

2.5 (2–4) 

Total calcium (%) 
Total phosphorus (%)  0.5 (0.4–0.55) 
Total copper (mg/kg) 
Total zinc (mg/kg)  
Phytase (%) 
NSP enzymes (%) 
Source: [ 297, UK 2010 ] 

15 (10–20) 
60 (40–100) 

Table 9.9:  Multiphase feeding for laying hens (free range) in the UK 

Parameter 
Period (weeks) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
NSP enzymes (U/kg) 
Source: [ 293, UK 2010 ] 

Phase 1 
16–25 
17.5 
0.88 
3.8 (3.8–4) 
0.475 
15 
70 
120 
500 

Phase 2 
25–50 
17 
0.84 
3.9 (3.9–4.1) 
0.451 
15 
70 
120 
500 

Phase 3 
50–72 
15.5 
0.76 
4.05 (4.05–4.3) 
0.403 
15 
70 
120 
500 

Table 9.10:  Multiphase feeding for laying hens (in cages) in Germany 

Phase 1 
11.6–12.1 
18 (15.4–20) 
0.4–0.42 

Phase 2 
11.4 
17 (15.5–19) 
0.35 (0.32–0.38) 

Parameter 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile 
(Met : Lys : Val : Thr : Trp)  
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg)  
NSP enzymes (%)  
(1) Data refer to methionine (first limiting amino acid). 
NB: Unrestricted (ad libitum) dry feed/pelleted feed (middlings or another type of feed). 

0.38  
0.45–0.55 
0.000 5 
0.004 4 
300 (250–750) 
0.005–0.01 

3.8 (3.7–4.4) 
0.42–0.45 
0.000 5 
0.004 4 
300 (250–750) 
0.005–0.01 

1 : 1.9 : 1.6 : 1.5 : 0.5 

Phase 3 
11–11.4 
16.5 (15–17) 
0.35 (0.32–0.38) 

4.1 (4.0–4.5) 
0.36–0.45 
0.000 5 
0.004 4 
300 (250–750) 
0.005–0.01 

Source: [ 327, Germany 2010 ] 

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9.2.1.3 

Broilers 

Table 9.11:  Multiphase feeding for light broilers (40 days) in the UK 

Parameter 
Period (days) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
NSP enzymes (%) 
NB: Final weight 2.35 (2, 25–2, 45) kg for 40 days 
Source: [ 296, UK 2010 ] 

Phase 1 
0–10 
22 (22–23) 
1.45 (1.3–1.5) 
0.9–1 
0.55 (0.5–0.6) 
20 (15–25) 
70 (60–90) 
0.03 
0.015 

Phase 2 
11–20 
21 (20–22) 
1.35 (1.2–1.4) 
0.75–0.9 
0.45–0.55 
20 (15–25) 
70 (60–90) 
0.03 
0.015 

Phase 3 
21–33 
18–19.5 
1.25 (1.15–1.3) 
0.65–0.85 
0.4–0.48 
20 (15–25) 
60 (50–80) 
0.03 (0.015–0.03) 
0.015 

Phase 4 
34–40 
18–19.5 
1.15 (1–1.2) 
0.65–0.85 
0.4–0.48 
20 (15–25) 
60 (50–80) 
 0.03 
0.015 

Table 9.12:  Multiphase feeding for heavy broilers (7 to 8.5 weeks) in the UK 

Phase 1 
1–8 
23.3 
NI 
1 
0.78 
25 
100 

Parameter 
Period (days) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
Inorganic phosphorus (%) 
NSP enzymes (%) 
NB: Final weight 3 kg for 8.5 weeks or 2.1 kg for 7 weeks. NI = no information provided. 
Source: [ 295, UK 2010 ] 

Phase 3 
14–27/37 
19.7 
NI 
0.74 
0.58 
25 
 90  
0.03 
1.02 
0.03 

Phase 4 
28–45/28–55 
17.8 
NI 
0.69 
0.52 
25 
 80  
0.03 
0.82 
0.03 

Phase 2 
9–13 
20.7 
NI 
0.74 
0.58 
25 
90  
0.03 
1.03 
0.03 

2.05 
0.03 

Phase 5 
46–49/56–59 
17.7 
NI 
0.64 
0.46 
25 
80  
0.03 
0.47 
0.03 

Table 9.13:  Multiphase feeding for broilers in Germany 

13.2–13.8 

13.0–13.4 

12.2–12.6 

Phase 1 
1–10 

Phase 2 
11–27/32 

Phase 3 
28/33–35/42 

22 (20–23) 
0.55 (0.45–0.6) 

21 (20–22) 
0.55 (0.45–0.55) 

1 : 1.84 : 2.78 : 1.81 : 
0.43 

Parameter 
Period (days) 
Metabolisable energy 
(MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile 
(Met : Met/Cys : Lys : 
Thr : Trp)  
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
NSP enzymes (%) (2) 
(1) Data refer to methionine (first limiting amino acid). 
(2) The enzyme activity ranges from 280/125 to 560/250 TXU/TGU (xylanase/glucanase) per kg of feed.  
NB:  
- The information is a synthesis of a lot of data recommended by different public and private research institutions 

1 (0.85–1.2) 
0.65 (0.65–0.7) 
6.2 (4–8)  
40 (40–50)  
500 (250–1 000) 
0.005–0.01 

0.9 (0.8–1.2) 
0.55 (0.55–0.7) 
6.2 (4–8)  
40 (40–44)  
500 (250–750) 
0 

0.8 (0.7–1.2) 
0.5 (0.5–0.7) 
6.2 (4–8)  
40 (20–70)  
500 (250–750) 
0 

1 : 2.17 : 2.68 : 1.97 : 
0.44 

19.5 (18–21) 
0.5 (0.45–0.52) 

1 : 2.38 : 2.54 : 2.07 : 
0.42 

and researchers. 

- Unrestricted (ad libitum) dry feed/pelleted feed. With regard to the structure of the pellet, it is recommended that 

during the first phase it is between crumbled and 2 mm. For the next phases it is 3 mm. 

Source: [ 327, Germany 2010 ] 

800 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
9.2.1.4 

Turkeys 

Annexes 

Table 9.14:  Multiphase feeding for turkeys in the UK 

Parameter 
Period (weeks) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg) 
Total zinc (mg/kg)  
Phytase (%) 
NSP enzymes (%) 
Source: [ 299, UK 2010 ] 

Phase 1 
0–2 
26 (25–28) 
1.7 (1.6–1.8) 
1.25 (1.2–1.4) 
0.75 (0.7–0.9) 
15 (15–25) 
70 (60–100) 
0.03 (0–0.03) 

Phase 2 
3–6 
24 (23–26) 
1.5 (1.4–1.7) 
1.1 (1–1.4) 
0.7 (0.65–0.85) 
15 (15–25) 
70 (60–100) 
0.03 (0–0.03) 

Phase 3 
7–12 
20 (20–23) 
1.4 (1.3–1.5) 
0.9 (0.9–1.2) 
0.65 (0.6–0.7) 
15 (15–25) 
70 (60–100) 
0.03 (0–0.03) 

Phase 4 
13–20 
18 (17–21) 
1.2 (1–1.3) 
0.8 (0.75–1) 
0.6 (0.55–0.65) 
15 (15–25) 
70 (60–100) 
0.03 (0–0.03) 

0.015 (0.015–0.03)  0.015 (0.015–0.03)  0.015 (0.015–0.03)  0.015 (0.015–0.03) 

Table 9.15:  Multiphase feeding for turkeys (starter) in Germany 

1 : 1.05 : 0.64 : 0.6 : 0.37 : 0.17  1 : 1.05 : 0.66 : 0.61 : 0.37 : 0.17 

Phase 1 
1–2 
11.2–11.8 
27.5–29.5 
0.17–0.171 

Phase 2 
3–5 
11.5–12.1 
26–27.5 
0.152–0.162 

Parameter 
Period (weeks) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile  
(Lys: Arg : Me/Cys : Thr : Met : Trp) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
NSP enzymes (%) (2) 
(1) Data refer to lysine (first limiting amino acid). 
(2) The enzyme activity is 560/250 TXU/TGU (xylanase/glucanase) per kg of feed. 
NB:  
- Unrestricted (ad libitum) dry feed/pelleted feed. 
- Regardless of sex, turkeys are raised together for the first and second phases of growth, which extend over the first 4–

1.1–1.5 
0.8–1 
0.000 8–0.001 
0.004–0.005 
500 (250–1 000) 
0.01–0.015 

1.3–1.4 
0.8–1 
0.000 8–0.001 
0.005–0.006 5 
500 (250–1 000) 
0 

5 weeks until full feathering of the young turkey. 

Source: [ 327, Germany 2010 ] 

Table 9.16:  Multiphase feeding for turkeys (male) in Germany 

Parameter 
Period (weeks) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile  
(Lys : Met/Cys : Thr : Met : Trp) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  

Phytase (FTU/kg) 

Phase 1 
5–8 
11.8–12.3 
24–24.5 
1.35–1.45 
1 : 0.54 : 0.56 
: 0.35 : 0.17 
0.8–1.4 
0.6–0.82 

Phase 2 
9–12 
12.3–12.8 
20–21 
1.25–1.28 
1 : 0.56 : 0.56 : 
0.35 : 0.16 
0.75–1.2 
0.55–0.55 

0.000 5–0.001  0.000 6–0.001 
0.003–0.004 
0.004–0.006 
500 (250–
500 (250–
1 000) 
1 000) 
0.01–0.015 
0.01–0.015 

Phase 3 
13–16 
12.8–13.2 
18–18 
1–1 
1 : 0.56 : 0.56 : 
0.34 : 0.16 
0.7–1.1 
0.5–0.7 
6–10 
30–40 

Phase 4 
> 17 
13.2–13.6 
14–16 
0.8–0.85 
1 : 0.55 : 0.56 : 
0.33 : 0.16 
0.65–1 
0.45–0.65 
0.000 6–0.001 
0.003–0.004 

500 (250–1 000)  500 (250–1 000) 

0.01–0.015 

NSP enzymes (%) (2) 
(1) Data refer to lysine (first limiting amino acid). 
(2) The enzyme activity is 560/250 TXU/TGU (xylanase/glucanase) per kg of feed. 
NB:  
- Unrestricted (ad libitum) dry feed/pelleted feed. 
- The feeding programme for male turkeys is a continuation of the programme for turkey starters.  
Source: [ 327, Germany 2010 ] 

0.01–0.015 

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801 

 
 
 
 
 
 
 
 
 
 
Annexes 

Table 9.17:  Multiphase feeding for turkeys (female) in Germany 

1 : 1.05 : 0.66 : 0.61 : 0.37 : 0.17 

Phase 1 
5–6/8–9 
12.3–13.8 
23–24.4 
1.4–1.45 

Phase 2 
9–10/12–13 
12.8–13.2 
20–21 
1.22–1.25 

Parameter 
Period (weeks) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile  
(Lys : Arg : Met/Cys : Thr : Met : Trp)  
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
NSP enzymes (%) (2) 
(1) Data refer to lysine (first limiting amino acid). 
(2) The enzyme activity is 560/250 TXU/TGU (xylanase/glucanase) per kg of feed. 
NB:  
- Unrestricted (ad libitum) dry feed/pelleted feed.  
- The feeding programme for female turkeys is a continuation of the programme for turkey starters. 
Source: [ 327, Germany 2010 ] 

0.75–1.2 
0.55–0.55 
0.000 8–0.001 
0.004–0.005 
500 (250–1 000) 
0.01–0.015 

0.8–1.2 
0.55–0.8 
0.000 8–0.001 
0.005–0.006 5 
500 (250–1 000) 
0.01–0.015 

Phase 3 
13–14/16–17 
13.2–13.6 
18–18.5 
1–1.1 

0.7–1.1 
0.5–0.75 
0.000 8–0.001 
0.004–0.005 
500 (250–1 000) 
0.01–0.015 

9.2.1.5 

Ducks 

Table 9.18:  Multiphase feeding for ducks in Germany 

Phase 1 
1–3  
11.40–12.34 
20–23.75 
0.4–0.48 

Phase 2 
4–7  
12.20–12.97 
18–18 
0.4–0.45 

Parameter 
Period (weeks) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile  
(Met : Lys : Met/Cys: : Thr : Trp)  
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
NSP enzymes (%) (2) 
(1) Data refer to methionine (first limiting amino acid). 
(2) The enzyme activity ranges from 280/125 to 560/250 TXU/TGU (xylanase/glucanase) per kg of feed.  
NB: Unrestricted (ad libitum) dry feed/pelleted feed. During the first phase the feed could be crumbled. For the next 

0.8–1.2 
0.65–0.85 
4.5 
40–50 
500 (250–1 000) 
0.005–0.01 

0.7–0.8 
0.6–0.7 
4.5–6.2 
40–55 
500 (250–1 000) 
0.005–0.01 

1 : 2 : 1.70 : 1.5 : 1.46 

1 : 2 : 1.75 : 1.5 : 0.4 

phases it is between 3 mm and 4 mm. 

Source: [ 327, Germany 2010 ] 

802 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
Annexes 

9.2.2 

Multiphase feeding for pigs 

9.2.2.1 

Gestating sows 

Table 9.19:  Multiphase feeding for gestating sows in the UK 

Parameter 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
Inorganic phosphorus (%) 
NSP enzymes (%) 
NB: NI = no information provided. 

Source: [ 309, UK 2010 ] 

Phase 1 (lactation) 
15–20 
0.8–1.1 
0.55–0.75 
0.55–0.75 
25 
100–150 
0–0.1 
0–0.7 
NI 

Phase 2 (gestation) 
12–15 
0.5–0.6 
0.75–0.9 
0.55–0.75 
25 
100–150 
0–0.1 
0–0.7 
NI 

Table 9.20:  Multiphase feeding for gestating sows in Germany 

Parameter 
Period (days of pregnancy) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile (Lys : Met/Cys : Thr : Trp)  
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg of feed)  
Inorganic phosphorus (%) 
NSP enzymes (%)  
(1) Data refer to lysine (first limiting amino acid). 
NB: NI = no information provided. 

Source: [ 326, Germany 2010 ] 

9.2.2.2 

Farrowing sows 

Phase 1 
1–84 
11, 8–12, 2 
13 (12–14) 
0.6 (0.5–0.7) 

Phase 2 
85–115 
11, 8–12, 2 
14 (12–16) 
0.7 (0.6–0.8) 

1 : 0.6 : 0.65 : 0.19 

0.55–0.65 
0.4–0.55 
8–10 
50–80 
500 (300–700)  
0.15 (0.1–0.2) 
NI 

0.56–0.75 
0.45–0.55 
8–10 
50–80 
500 (300–700)  
0.15 (0.1–0.2) 
NI 

Table 9.21:  Multiphase feeding for farrowing sows in Germany 

Parameter 
Days of lactation 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
Inorganic phosphorus (%) 
NSP enzymes (%) 
NB: NI = no information provided. 

Source: [ 326, Germany 2010 ] 

One phase 
25 
13 (12.8–13.4) 
17 (16–17.5) 
0.95 (0.9–1) 
0.85 (0.75–0.95) 
0.6 (0.5–0.7) 
1 
50  
500 (300–700) 
0.15 (0.1–0.2) 
NI 

Intensive Rearing of Poultry or Pigs 

803 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

9.2.2.3 

Weaners 

Table 9.22:  Multiphase feeding for weaners and growers in the UK 

Parameter 
Period (weight in kg) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
Inorganic phosphorus (%) 
NSP enzymes (%) 
Source: [ 308, UK 2010 ]  

Phase 1 
7.5–20 
20–24 
1.6–1.7 
0.55–0.75 
0.55–0.75 
170 
150  
0–0.1  
0–0.7 
0–0.1 

Phase 2 
20–25 
19–23 
1.4–1.6 
0.6–0.75 
0.55–0.75 
170 
150  
0–0.1 
0–0.7 
0–0.1 

Phase 3 
25–50 
18–21 
1.2–1.4 
0.6–0.75 
0.55–0.75 
17 
150 
0–0.1 
0–0.7 
0–0.1 

Table 9.23:  Multiphase feeding for weaners in Germany 

Parameter 
Period (weight in kg) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg) 
Inorganic phosphorus (%) 
Benzoic acid (%) 
NSP enzymes (%) (1) 
(1) The enzyme activity is 10 TXU (xylanase) per kg of feed. 
Source: [ 326, Germany 2010 ] 

Phase 1 
8–20  
13.4 
18 (17–18.5) 
1.25 (1.2–1.4) 
0.75 (0.7–0.8) 
0.55 (0.46–0.6) 
20(6–170) 
80 (35–100) 
500–1 500 
0.15 (0.1–0.2) 
0.5 
0.01 

9.2.2.4 

Fattening pigs 

Table 9.24:  Multiphase feeding for finishers in the UK (two phases) 

Phase 2 
21–30  
13.8–13.0 
17.5 (17–18) 
1.15 (1.1–1.2) 
0.7 (0.65–0.8) 
0.5 (0.42–0.55) 
20 (6–170)  
80 (70–100)  
500–1 500 
0.15 (0.1–0.2) 
0.5 
0.01 

Parameter 
Period (weight in kg) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (%)  
Inorganic phosphorus (%) 
NSP enzymes (%) 
Source: [ 311, UK 2010 ] 

Phase 1 
50–70 
17–20 
1–1.2 
0.6–0.75 
0.55–0.75 
25 
150 
0–0.1 
0–0.7 
0–0.1 

Phase 2 
70–100 
16–19 
0.9–1.2 
0.6–0.75 
0.55–0.75 
25 
150 
0–0.1 
0–0.7 
0–0.1 

804 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
Table 9.25:  Multiphase feeding for fattening pigs in Germany (two phases) 

Annexes 

Parameter 
Period (weight in kg) 
Metabolisable energy (MJ/kg) 
Crude protein (%) 
Amino acids (%) (1) 
Amino acid profile (Lys : Met/Cys : Thr 
: Trp)  
Total calcium (%) 
Total phosphorus (%) 
Total copper (mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg of feed) 
Inorganic phosphorus (%) 
NSP enzymes (%) 
(1) Data refer to lysine (first limiting amino acid). 
NB: NI = no information provided. 
Source: [ 326, Germany 2010 ] 

Phase 1 
25–60  

Phase 2 
60–110  

13.0–13.4 at the beginning and 12.8 at the end of the period 

17 
1.05 (0.95–1.15) 

14 
0.95 (0.9–1.05) 

1 : 0.55 : 0.65 : 0.18 

0.7 (0.65–0.75) 
0.58 (0.42–0.6) 
10 (5–15) 
 50 
280–500 
0.15 (0.1–0.2) 
NI 

0.65 (0.6–0.75) 
0.45 (0.4–0.45) 
10 (5–15) (5) 
60 
280–500 
0.15 (0.1–0.2) 
NI 

Table 9.26:  Multiphase feeding for weaners and fattening pigs in the UK (5 phases) 

Phase 2 

20–25 

Phase 3 

Phase 4 

25–50 

50–70 

Phase 5 

70–100 

21 (19–22) 
1.45 (1.3–1.5) 
0.7 (0.6–1) 

19 (18–22) 

18 (17–20) 

1.35 (1.2–1.45)  1.15 (1–1.25) 
0.75 (0.7–0.9) 

0.7 (0.7–1) 

17 (16–19) 
1(0.8–1.1) 
0.65 (0.65–1) 

0.65 (0.6–0.8)  0.65 (0.6–0.75) 

0.6 (0.6–0.7) 

0.6 (0.6–0.7)  0.55 (0.55–0.65) 

170 

150 
NI 
NI 

170 

150 
0.01 
NI 

25 

150 
0.01 
NI 

25 

150 
NI 
NI 

Table 9.27:  Multiphase feeding for fattening pigs in Germany (5 phases) 

Phase 2 

40–60  

Phase 3 

60–80  

Phase 4 

Phase 5 

80–100  

100–110  

NI 

NI 

NI 

12.8 

16.5–18 

16.5–17.5 
1.05 (0.95–1.15)  0.95 (0.9–1.05)  0.9 (0.85–1.05) 
0.6–0.75 

0.65–0.75 

15.5–17 

0.7 

14–16 
0.85 (< 1) 
0.6 

12.9–15 
0.75 (< 0.85) 
0.6 

22 (21–23) 
1.5 (1.4–1.7) 
0.7 (0.6–1) 

Phase 1 

7.5–20 

Parameter 
Period (weight in 
kg) 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus 
(%) 
Total copper 
(mg/kg)  
Total zinc (mg/kg)  
Phytase (%) 
NSP enzymes (%) 
NB: NI = no information provided. 
Source: [ 310, UK 2010 ] 

150 
NI 
NI 

170 

13.0–13.4 

Phase 1 

30–40  

Parameter 
Period (weight in 
kg) 
Metabolisable 
energy MJ/kg 
Crude protein (%) 
Amino acids (%) 
Total calcium (%) 
Total phosphorus 
(%) 
Total copper 
(mg/kg)  
Total zinc (mg/kg)  
Phytase (FTU/kg of 
feed) 
Inorganic 
phosphorus (%) 
NSP enzymes (%) 
NI 
NB: NI = no information provided. 

60 

5–15 

280–500 

0.1–0.2 

0.42–0.6 

0.45–0.55 

0.4–0.5 

0.4–0.5 

5–15 

60 

4–15 

60 

4–15 

60 

0.45 

4–15 

60 

280–500 

280–500 

280–500 

280–500 

0.15 

NI 

0.1–0.2 

0.1–0.2 

0.1–0.2 

NI 

NI 

NI 

Source: [ 326, Germany 2010 ] 

Intensive Rearing of Poultry or Pigs 

805 

 
 
 
 
 
 
 
 
Annexes 

9.2.2.5 

Multiphase feeding in France 

Examples  of  feeding  programmes  recommended  for  pig  nutrition  in  France  are  given  in  the 
table below. 

Table 9.28:  Multiphase feeding for pigs in France  

Sows 

Weaners 

Fattening 
pigs (1)  

Stage 

Gestation 
Lactation 
1st age 
(Pre-starter) 
2nd age 
(Starter) 
Growing 
(30–65 kg) 
Finishing 
(65–112 kg)  

Crude protein level in feed (%) 

Phosphorus (%) 

Standard 
(One-phase) 
17 
17.5 

21 

19 

17.5 

17.5 

Two-phase 

14 
16.5 

20 

18 

16.5 

15 (2)  

Standard 
(One-phase) 
0.65 
0.65 

0.75 

0.75 

0.58 

0.58 

Two-phase 

0.5 
0.6 

0.68 

0.58 

0.48 

0.44  

(1) Feed conversion = 2.86 kg/kg. For over 112 kg, +0.006 kg per extra kg.  
(2) The finishing feed represents at least 60 % of the whole quantity of feed. 
Source: [ 329, CORPEN 2003 ] 

806 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Annexes 

9.3 

Example of calculation of costs associated with the 
application of emission reduction techniques 

The scope of this annex is to describe an approach that can be used for calculating the cost of 
individual techniques proposed under the framework of the IED. The approach described relates 
to the ‘unit’ cost of techniques; it has also been adopted by UNECE for part of the process of 
calculating  the  compliance  costs  of  reducing  ammonia  emissions  from  livestock  production  
[ 508, TFRN 2014 ].  

This annex further implies that, for this approach to be adopted, all techniques to be considered 
in the determination of BAT should be presented with the required technical and financial data 
as listed in the tables.  

This annex is largely based on work done by DEFRA, UK, in turn based on work by an expert 
group  within  the  TWG  on  cost  assessment  and  BAT  [  557,  MAFF  2000  ].  Cost  calculation 
examples  have  been  also  drawn  up  by  an  expert  group  in  Spain  within  the  TWG  
[ 338, Piñeiro et al. 2009 ].  

9.3.1 

Methodology 

This section comprises the following topic areas: 

 

 

 

overview; 

type of measure; 

calculation of 'unit' costs. 

Overview 

The calculation of unit costs requires a clear understanding of: 

 

 

 

the proposed technique to be introduced to reduce emissions; 

the  whole  range  of  systems  of  production  and  management  that  are  found  on  relevant 
farms; 

the  impact  that  the  introduction  of  the  technique  will  have  on  farm  production  and 
management systems in both physical and financial terms as well as in terms of costs and 
benefits. 

The  calculation  will  result  in  an  annual  cost,  which  may  comprise  an  allowance  for  capital 
expenditure amortised over the life of the investment. Once calculated, these costs can be used 
in: 

 

 

 

 

the calculation of the cost of individual, or a combination of, techniques per kilogram of 
pollutant abated; 

the determination of general BAT; 

the relationship between the costs of BAT implementation and the economic viability or 
profitability of the intensive poultry or pig rearing industry; 

the cost to the industry of compliance. 

Intensive Rearing of Poultry or Pigs 

807 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

Categories of technique 

Techniques  applicable  to  the  intensive  poultry  or  pig  rearing  sector  may  be  categorised  as 
follows: 

 

 

 

 

 

feeding; 

housing; 

solid manure or slurry storage; 

treatment of manure, if applicable; 

application of solid manure or slurry to land. 

A technique should be identified under one of the above categories and according to livestock 
category  affected, for example,  laying  hens  or  breeding  pigs.  The  categories  are  subsequently 
used to identify how 'unit' costs should be calculated. 

Calculation of unit costs 

Unit  costs  are  the  annual  increase  in  costs  that  a  typical  farmer  will  bear  as  a  result  of 
introducing a technique. The general approach to the calculation of unit costs is as follows: 

 

 

 

 

 

define  the  physical  and  husbandry  changes  resulting  from  implementation  of  the 
abatement technique based on a thorough understanding of farming systems;  

for  each  technique,  identify  those  areas  where  cost  or  performance  changes  will  be 
associated with the introduction of that technique; 

in all cases, only those costs directly associated with the technique should be considered; 

additional costs associated with any technical enhancements should be ignored; 

as the assessment of costs is carried out at farm level, any grants that are available should 
be deducted from expenditure. 

The category that techniques fall into will determine the physical units that are used to define 
the  population  or  quantities  of  manure,  and  form  the  basis  of  subsequent  calculations.  The 
relationship can be seen in the following table. 

Table 9.29:  Units used for assessing costs 

Category 

Units/year 

Details 

Feeding and housing 

Manure storage, 
treatment and 
landspreading 

per head 
per animal place 
per kg NH3 abated 
per kg produced 
per m3 or tonne 
per kg NH3 abated 
per kg produced 

Building capacity 

Slurry (including dilution) and solid 
manure (including bedding) 

Unit costs should be calculated according to the general approach described below: 

 

 

808 

current costs should be used for all calculations; 

capital expenditure, after deducting any grants, should be annualised over the economic 
life of the investment; 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

annual operating costs should be added to the annualised cost of capital; 

changes in performance have a cost and should be taken into account as part of the annual 
costs; 

this total sum is divided by the annual throughput to determine the 'unit cost'; annual cost 
is expressed by the 'units' shown in Table 9.31. 

Annexes 

The approach is detailed in the following paragraphs. 

Capital costs 

Capital expenditure needs to be assessed under the headings shown in Table 9.30. 

Table 9.30:  Capital expenditure considerations 

Primary consideration 
Capital for fixed equipment (1) 
or machinery (2) 

Labour cost of installation 

Notes 

Use national costs. If these are unavailable, use international 
costs including delivery cost and convert the cost to national 
currency at the appropriate rate. 
Use contract charges if these are normal.  
If farm staff are normally used to install the conversion, 
employed staff should be rated at typical hourly rates. Farmers’ 
input should be charged at the opportunity cost. 
Subtract the value of capital grants available to farmers. 

Grants 
(1) Fixed equipment includes buildings, conversions of buildings, feed storage bins, or manure storage. 
(2)  Machinery includes feed distribution augers, field equipment for manure application or equipment for 

manure processing. 

Capital  expenditure  should  clearly  indicate  the  investment  costs  in  new-build  situations,  in 
contrast with rebuilding or renovation of buildings.  

Annual costs 

The  annual  cost  associated  with  the  introduction  of  a  technique  needs  to  be  assessed  in  the 
following steps. 

Table 9.31:  Annual cost considerations 

Step 

Consideration 

A 

B 

C 

D 

Annualised cost of capital should be 
calculated over the life of the investment 

Repairs associated with the investment 
should be calculated 
Changes in labour costs 

Fuel and energy costs 

E 

Changes in livestock performance 

F 

Cost savings and production benefits 

Notes 
Use standard formula. The term will depend on 
the economic life. Conversions need to take 
account of the remaining life of the original 
facility. See Appendix 1 to this section. 
A certain percentage of the capital costs. See 
Appendix 2 to this section. 
Additional hours multiplied by cost per hour.  
Additional power requirements may need to be 
taken into account. See Appendix 2 to this 
section. 
Changes in diets or housing can affect 
performance, with cost implications. See 
Appendix 3 to this section. 
In certain cases, the introduction of techniques 
will result in the saving of costs for the farmer. 
These should be quantified as far as possible.  
Care should be taken for the avoidance of fines 
for pollution. 

Intensive Rearing of Poultry or Pigs 

809 

 
 
 
 
 
 
 
 
 
 
 
Annexes 

9.3.2 

Examples in the UK  

Liquid manure application by soil injection 

Basis for the costs: 

1. 

The  costs  are  based  on  the  purchase  of  an  injector  attachment  for  fitting  to  either  the 
slurry tanker or the tractor. The capital cost of such equipment is EUR 10 000. 
2. 
Additional tractor power of about 35 kW is needed compared to surface application. 
3.  Work rates of about 14 m3 per hour may be achieved compared to 17 m3 (2.5 loads per 
hour of 7 m3) per hour using a tanker and splash plate system. This is based on a 6-minute 
discharge for a splash plate operation being extended to 12 minutes when injecting. 
Annual throughput 2 000 m3. 
Capital cost amortised over 5 years at 8.5 %. 
Emission reduction, e.g. reduction of ammonia emission expressed in mg NH3/Nm3. 

4. 
5. 
6. 

Table 9.32:  Additional costs incurred with liquid manure application by soil injection in the UK 

Step 

Consideration 

Calculation 

Total 
(EUR/yr) 

A 

B 

C 

Annual cost of 
capital 

Repairs 
Changes in labour 
costs 

D 

Fuel and energy costs 

Use formula given in Appendix 1 and shown below. 
C = (r(1+r)n)/((1+r)n – 1) 

C = EUR 10 000 
r = 8.5 % inserted into formula as 0.085 
n = 5 years 
EUR 10 000 = (0.085(1+0.085)5)/((1+0.085)5 – 1) 
At 5 % of capital cost of injector (EUR 10 000) 
Slower  application  rates  (2 000m3    14  m3/hr  less 
2 000m3  17 m3/hr) = 25 hours times EUR 12 per hour 
Additional tractor costs: 35 kW for 2 000m3  14 m3/hr 
= 143 hrs at 10 litres per hour at EUR 0.35 per litre 

E 

F 

Not applicable 

Changes in livestock 
performance 
Cost savings and 
production benefits 
Total extra annual costs 
Total extra cost per m3 based on an annual throughput of 2 000 m3

Not  included,  although  there  may  be  better  use  of 
manure nitrogen 

2 540 

500 

300 

500 

0 

0 

3 840 
1.92 

Solid manure incorporation by ploughing (example calculation without capital expenditure) 

Basis for the costs: 

1. 

2. 
3. 

Contractors  will  need  to  be  used  to  incorporate  solid  manure  in  many  situations,  as 
employed labour and machinery will be fully utilised on other tasks. 
The method of incorporation will normally be by ploughing. 
There  will  be  a  marginal  cost  saving,  as  this  operation  (ploughing)  will  not  need  to  be 
carried out by farm staff at a later time. 

4.  Manure spread up to the equivalent of 250 kg total N per hectare per year.  

810 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
Table 9.33:  Additional costs incurred with solid manure incorporation by ploughing in the UK 

Annexes 

Step 

Consideration 

Calculation 

A 
B 
C 
D 
E 

F 

Not applicable 
Not applicable 

Annual cost of capital 
Repairs 
Changes in labour costs  Employment of a contractor to carry out ploughing 
Fuel and energy costs 
Changes in livestock 
performance 
Cost 
production benefits 
Total extra annual costs 

Savings in farmer’s own marginal machinery costs 

Not applicable (included in contractor charge) 

Not applicable 

savings 

and 

Total 
(EUR/ha) 

0 
0 
65 
0 
0 

10 

55 

Extra cost per tonne of manure: 

EUR/tonne 

Pig manure applied at 36 tonnes/ha 
Laying hen litter applied at 16.5 tonnes/ha 
Broiler litter applied at 8.5 tonnes/ha 

1.53 
3.33 
6.47 

Calculations with changes to a building: 1. Air ducts in deep pit poultry housing 

Basis for the costs: 

1. 

2. 

3. 

Simple  polythene  pipe  air  ducts  are  installed  in  the  pit  under  the  manure  and  fan 
ventilated. The capital cost is EUR 0.32 per bird place. 
Such  systems  have  additional  operating  costs  of  EUR 0.16  per  bird  place  per  year 
(electricity and repairs). 
The capital costs of the system are amortised over 10 years at 8.5 %. 

Table 9.34:  Additional costs incurred with air duct installation in the UK 

Step 

Consideration 

Calculation 

Total  
(EUR/bird place) 

A 
B 
C 
D 

E 

F 

Cost of pipes and fan 
Additional repair costs  
Not applicable 
Additional electricity costs 

Annual cost of capital 
Repairs 
Changes in labour costs 
Fuel and energy costs 
Changes in livestock 
performance 
Cost savings and production 
benefits 
Total extra annual costs per bird place 

Not applicable 

Not applicable 

0.05 
0.08 
0 
0.08 

0 

0 

0.21 

Calculations for changes to a building: 2. Metal grid replacement floors in pig buildings 

Basis for the costs: 

1. 
2. 
3. 

4. 

5. 

Capital cost of replacement slats: EUR 78 per m2 (Tri-bar) plus EUR 16 of installation. 
Installation is uncomplicated. 
The cost of capital is amortised over 10 years at 8.5 %. This allows for fitting the slats in 
existing accommodation, which is partway through its life. 
Cost per pig place is based on a total allowance of 0.63 m2 per pig place, see below. Of 
this  area,  normally  25 %  or  0.156  m2  per  pig  place  is  slatted  in  partly  slatted 
accommodation. 
Repair costs are considered to be similar to other types of floor. 

Intensive Rearing of Poultry or Pigs 

811 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

Table 9.35:  Additional costs incurred with metal grid floor replacement in the UK 

Consideration 

Calculation 

Step 

A 

Annual cost of capital 

Capital cost of EUR 94/m2 for 0.156 m2 
amortised over 10 years at 8.5 % 
No extra costs 
Not applicable 
Not applicable 

B 
C 
D 
E 

Repairs 
Changes in labour costs 
Fuel and energy costs 
Changes in livestock 
performance 
Cost savings and production 
benefits 
Total extra annual costs per pig place 
NB: Data provided by Kirncroft Engineering (UK). 

F 

Not applicable 

Not applicable 

Total  
(EUR/pig place) 

2.23 

0 
0 
0 

0 

0 

2.23 

9.3.3 

Examples in Spain 

Multiphase feeding of fattening pigs (excluding feed cost) 

Basis for the costs: 

1. 
2. 

3. 

Baseline: Growing and finishing pigs are housed together and fed one ration. 
Costs  are  calculated  for  the  fitting  of  an  additional  feed  storage  bin  and  distribution 
system  to  each  house  to  allow  pigs  to  be  fed  a  ration  containing  a  protein  level  more 
precisely matched to their requirements.  
The building capacity is 720 places, the building occupation is 85 % and the cleaning and 
disinfection  lasts  10  days. The feed  storage  bin  capacity  is  12 tonnes,  the  length  of  the 
distribution auger is 140 metres and the power requirements 1 kWh.  

4.  Multiphase feeding may provide cost and feed conversion ratio improvements.  

Table 9.36:  Additional  costs  incurred  for  the  installation  of  multiphase  feeding  in  fattening  pig 

houses in Spain 

Step 

Consideration 

Calculation 

A 

Annual cost of capital  Storage bin: Investment cost of EUR 1 554 

B 
C 

D 

E 

F 

amortised over 10 years at 5.0 % 
Auger: Investment cost of EUR 3 500 
amortised over 5 years at 5.0 % 
2 % of investment cost 
Not applicable 

Repairs 
Changes in labour 
costs 
Fuel and energy costs  Additional power requirements at 

Changes in livestock 
performance 

Cost savings and 
production benefits 

feed 

EUR 0.12/kWh and 3 hours per day 
operation of motor  
Not  available,  although  multiphase  feeding 
may 
ratio 
provide 
improvements 
Price difference between feeds: EUR 2/tonne 
Phase duration 20–60 kg: 55 days 
Phase duration 60–100 kg: 45 days 
Feed consume 20–60 kg: 1.4 kg/pig and day 
Feed consume 60–100 kg: 2.2 kg/pig and day 

conversion 

Total extra annual costs per animal place 

Total  
(EUR/animal 
place) 
0.25 

1.12 

0.14 

0.23 

-0.25 

1.52  

812 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
The  total  costs  can  also  be  expressed  as  EUR  0.005 2  per  kg  of  pig  produced  under  the 
assumption that one animal place for fattening pigs produces 294 kg of marketed pig per year. 

Retrofitting an animal house for gestating sows with a partly slatted floor and reduced pit  

Annexes 

Basis for the costs: 

1. 

2. 
3. 

Baseline:  Gestating  sows  are  reared  on  a  fully  slatted  floor  with  a  deep  pit  (more  than 
60 cm).  
Costs are calculated for reducing the existing pit width by 50 %.  
The  building  capacity  is  230  places,  the  building  surface  is  460  m2,  the  floor  is  50 % 
slatted with concrete slats and the pit has a rectangular section with an average depth of 
60 cm. 

Table 9.37:  Additional  costs  to  install  a  partly  slatted  floor  with  a  reduced  pit  in  gestating  sow 

houses in Spain 

Step 

Consideration 

Calculation 

A 

Annual cost of 
capital 

Repairs 

B 
C-F 

EUR 3 770, 

Investment  costs  of  EUR  9 976  are  amortised 
over  10  years  (disassembly  and  assembly 
reformation: 
facilities: 
EUR 1 386, concrete for the pits: EUR 4 820) at 
a 5 % interest rate 
2 % of investment cost 
Not applicable 

pit 

Total extra annual costs per animal place 

Total extra costs 
 (EUR/animal 
place) 

5.27 

0.41 

5.68  

The  total  costs  can  also  be  expressed  as  EUR  0.002 1  per  kg  of  pig  produced  under  the 
assumption  that  one  animal  place  for  gestating  sows produces 26.6 pigs  marketed  per  year  or 
2 660 kg of marketed pig per year (with the assumption that one pig marketed at 100 kg). 

For  existing  buildings,  it  is  advisable  to  consider  an  economic  security  margin  of  20 %  (the 
existing conditions can be less favourable than in the example).  

Installing a manure pan in a new animal house for farrowing sows  

Basis for the costs: 

1. 
2. 

Baseline: Farrowing sows are reared on a fully slatted floor with a deep pit.  
The building capacity is 120 places, the total building surface is 684 m2 and the floor 
remains 100 % slatted. 

Table 9.38:  Additional costs to install a manure pan with a smooth surface under the slatted floor 

in a new house for farrowing sows in Spain 

Step 

Consideration 

Calculation 

Total extra costs 
 (EUR/animal 
place) 

Annual cost of 
capital 

Repairs 

A 

B 
C-F 

Extra investment costs of EUR 14 070 are 
amortised  over  10  years  at  a  5 %  interest 
rate (cost of concrete + PVC sheet for the 
pit: EUR 1 407 per 12 places) 
2 % of investment cost 
Not applicable 

Total extra annual costs per animal place 

15.18 

2.34 

17.52  

Intensive Rearing of Poultry or Pigs 

813 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

The  total  costs  can  also  be  expressed  as  EUR  0.002 2  per  kg  of  pig  produced  under  the 
assumption  that  one  animal  place  for  farrowing  sows  produces  80  pigs  marketed  per  year  or 
8 000 kg of marketed pig per year (with the assumption that one pig is marketed at 100 kg). 

Retrofitting an animal house for farrowing sows with a manure pan  

Basis for the costs: 

1. 
2. 

Baseline: Farrowing sows are reared on a fully slatted floor with a deep pit.  
The building capacity is 120 places, the total building surface is 684 m2 and the floor 
remains 100 % slatted. 

Table 9.39:  Additional costs to install a manure pan with a smooth surface under the slatted floor 

in an existing house for farrowing sows in Spain 

Step 

Consideration 

Calculation 

A 

Annual cost of 
capital 

Repairs 

B 
C-F 

Investment  costs  of  EUR 24 869  are 
amortised  over  10  years  (disassembly  and 
assembly  facilities  EUR 1 080  per  12 
places,  brick  partition  EUR 20/m2,  cost  of 
concrete  +  PVC  sheet 
the  pit: 
EUR 1 407 per 12 places) at a 5 % interest 
rate 
2 % of investment cost 
Not applicable 

for 

Total extra annual costs per animal place 

Total extra costs 
(EUR/animal 
place) 

26.84 

4.14 

30.98  

The  total  costs  can  also  be  expressed  as  EUR  0.004 6  per  kg  of  pig  produced  under  the 
assumption  that  one  animal  place  for  farrowing  sows  produces  80  pigs  marketed  per  year  or 
8000 kg of marketed pig per year (with the assumption that one pig is marketed at 100 kg). 

For  existing  buildings,  it  is  advisable  to  consider  an  economic  security  margin  of  20 %  (the 
existing conditions can be less favourable than in the example).  

Installing slanted walls to separate faeces and urine in a new animal house for weaners  

Basis for the costs: 

1. 
2. 

Baseline: Weaners are reared on a fully slatted floor with a deep pit.  
The building capacity is 1 320 places, the total building surface is 500 m2 and the floor 
remains 100 % slatted. 

Table 9.40:  Additional costs to install slanted walls in the manure pit  of a new house for weaners 

in Spain 

Step 

Consideration 

Calculation 

Total extra costs 
(EUR/animal 
place) 

Annual cost of 
capital 

Repairs 

A 

B 
C-F 

Extra investment costs of up to EUR 2 088 
are  amortised  over  10  years  at  a  5 % 
interest rate (EUR 0 to +30 % in relation to 
a deep pit) 
2 % of investment cost 
Not applicable 

Total extra annual costs per animal place 

0–0.20 

0–0.03 

0–0.23  

814 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The total  costs can also  be expressed as up to EUR 0.000 4 per kg of pig produced under the 
assumption that one animal place for weaners corresponds to 5.79 rotations per year or 579 kg 
of marketed pig per year (with the assumption that one pig marketed at 100 kg). 

Retrofitting an animal house for fattening pigs with a partly slatted floor  

Annexes 

Basis for the costs: 

1. 

2. 

Baseline:  Fattening  pigs  are  reared  on  a  fully  slatted  floor  with  a  deep  pit  (more  than 
70 cm).  
Costs are calculated for the installation of a partly slatted floor (one-third solid and two-
thirds slatted). The building capacity is 1 440 animal places, the building surface is 1 450 
m2 and the average depth of the pit is 70 cm.  

Table 9.41:  Additional costs to install a partly slatted floor and reduced pit in an existing gestating 

pig house in Spain 

Step 

Consideration 

Calculation 

A 

Annual cost of 
capital 

Repairs 

B 
C-F 

Investment costs of EUR 34 820 are amortised 
over  10  years  (disassembly  and  assembly 
facilities:  EUR  2 540/room  of  120  places, 
brick  partition:  EUR 20/m2,  solid  concrete 
floor: EUR 15/m2) at a 5 % interest rate 
2 % of investment cost 
Not applicable 

Total extra annual costs per animal place 

Total extra costs 
(EUR/animal place) 

3.13 

0.48 

3.61  

The  total  costs  can  also  be  expressed  as  EUR  0.012 3  per  kg  of  pig  produced  under  the 
assumption that one animal place for fattening pigs produces 294 kg of marketed pig per year. 

For  existing  buildings,  it  is  advisable  to  consider  an  economic  security  margin  of  20 %  (the 
existing conditions can be less favourable than in the example).  

Slurry application by trailing hose machines 

Basis for the costs: 

1. 

2. 

3. 

The costs are based on the purchase of a trailing hose attachment for fitting to the slurry 
tanker using a splash plate for application of slurry to land. 
The tanker capacity is 15 000 litres, the working width 12 metres, and the required tractor 
power 150 CV with a working rate of 19 m3/h. 
The quantity of slurry to be spread annually is 5 375 m3 and it is generated by a fattening 
pig house with 2 500 animal places.  

Intensive Rearing of Poultry or Pigs 

815 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

Table 9.42:  Additional  costs  incurred  for  the  fitting  of  a  mounted  trailing  hose  system  to  an 

existing slurry tanker 

Step 

Consideration 

Calculation 

Total extra costs 
(EUR/animal place) 

A  Annual cost of capital 

Investment  costs  of  EUR  18 000  are 
amortised over 6 years at a 5 % interest 
rate 
12.82 % of investment cost 

B  Repairs 
C  Changes in labour costs  A same working rate is assumed 
D 

No additional tractor power is needed  

E 

F 

Fuel and energy costs 
Changes in livestock 
performance 
Cost savings and 
production benefits 
Total extra annual costs per animal place 

Not applicable 

Not  included,  although  there  may  be 
better utilisation of nitrogen in manure 

0.66 

0.42 
NA 
NA 

NA 

NA 

1.08  

NB: NA = not applicable. 

The  total  costs  can  also  be  expressed  as  EUR  0.013 5  per  kg  of  pig  produced  under  the 
assumption that one produced pig produces 0.8 m3 of slurry and that a pig is marketed at 100 kg. 

Useful reporting of cost data 
A  number  of  issues  and  presentational  factors  make  assimilation  of  cost  data  easier  for  the 
reader and could support future assessment. 

Any  report  on  costs  should  contain  sufficient  information  to  enable  the  uninformed  reader  to 
follow the logic and calculations. A combination of explanatory narrative and tables allows the 
reader to follow the thought processes of the author(s). 

In all cases, the sources of the data should be identified. Where professional judgement has been 
used to derive certain figures or assumptions, this should be acknowledged.  

It is suggested that a report should contain the following sections and format: 

 
 

 

Introduction 
Summary: 

Cost of technique: 

Text and tables showing the unit cost of techniques 

Text and tabular presentation for each technique showing 
the basis and calculation of the unit cost, drawing on 
supplementary data contained in appendices 

9.3.4 

Appendices 

Appendix 1: Calculation of annual charge for capital 

Capital expenditure on abatement techniques should be converted to an annual charge. Capital 
may  be  for  buildings,  fixed  equipment  or  machinery.  It  is  important  to  include  only  the 
additional or marginal capital associated with the abatement techniques. 

Amortisation should be used to calculate the annual cost of capital. When using this method, an 
additional  allowance  for  depreciation  of  the  asset  should  not  be  included  in  the  calculation. 
Factors  derived  from  appropriate  tables  can  be  applied  to  the  capital  invested  or  the  standard 
formula, shown below, can be used. 

816 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Formula 

The formula for calculating the annual cost of capital items is: 

Equation 9.1: 

C = 

r(1+r)n 
 (1+r)n - 1 

Annexes 

where:   C = capital investment; 

r = rate of interest expressed as a decimal of 1, e.g. an interest rate of 6 % is entered in 
the equation as 0.06; 
n = write-off period in years. 

Rate of interest 

The rate of interest that is applied should reflect that commonly paid by farmers and will vary 
by country and by investment term. For guidance, 5 % is the rate of interest commonly incurred 
by farmers seeking medium-term loans in Spain.  

Write-off period 

The write-off period will depend on the type of investment and whether it is a new facility or a 
conversion. 

In  the  case  of  new  facilities,  the  following  economic  lives  are  given  as  a  guide.  In  particular 
circumstances it may be necessary to vary these figures. 

Table 9.43:  Economic life of new facilities 

Type of investment 

Buildings 
Fixed equipment installed in buildings 
Machinery (depending on type) 

Economic life in years 
20 
10 
7 or 5 

In the case of conversions, it is necessary to annualise the capital cost over the remaining life of 
the original facility. 

These figures reflect the economic life over which the investment should be considered rather 
than the operational life. In many cases, the facility may have an operational life in excess of the 
economic life, though it is the economic life that must be used in these calculations. 

Appendix 2: Repair and fuel costs 

Repairs 

Repair costs associated with any investment will vary greatly. The type of investment, original 
build quality, operating conditions, age in relation to design life and amount of use all play their 
part in influencing costs. 

The following figures can be used for guidance. 

Intensive Rearing of Poultry or Pigs 

817 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

Table 9.44:  Repair costs as a percentage of new costs 

Type of investment 

Buildings 

Fixed equipment  

Tractors 

Manure and slurry spreaders 

Annual repair cost as a 
percentage of new cost 
0.5–2 

1–3 

5–8 

3–6 

Fuel 

The following general formulae can be used to calculate fuel costs: 

Electricity: 

Equation 9.2: 

Fuel cost  = 

kWh 

x  Hours of use 

x 

Fuel price 

Tractor fuel: 

Equation 9.3: 

Fuel 
cost 

=  kWh 

x 

Fuel consumption 
per kWh 

x 

Hours 
of use 

x 

Fuel 
price 

Appendix 3: Unit costs - Some detailed considerations 

The following detailed factors should be considered in relation to each technique. 

Feed 

Changes to diets can be applied to many classes of livestock to reduce ammonia emissions. The 
following implications need consideration in each case. 

Table 9.45:  Annual costs to consider in capital costs of feeding systems 

Capital costs 

Additional feeding systems 

Annual costs to consider 

Annual charges, repairs and power inputs 
Changes to carcass value 
Relative costs of diets 
Changes to livestock performance and feed consumption 
Changes in excreta output 
Changes in labour requirements 

818 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Housing 

For  those  techniques  requiring  capital  expenditure  by  farmers,  it  is  necessary  to  consider  the 
elements in the following table. 

Annexes 

Table 9.46:  Annual costs to consider in capital costs of housing systems 

Capital costs 

Changes to housing systems 

Annual costs to consider 

Annual charges, repairs and power inputs 
Changes in house capacity 
Changes in labour requirements 
Changes in bedding requirements 
Changes to livestock performance and feed consumption 
Changes in excreta storage capacity in the building 

NB:  Capital  costs  may  refer  to  either  the  modification  of  existing  facilities  or  the  additional  costs  of 
replacement  facilities.  The  choice  will  depend  on  building  condition  and  suitability  for  conversion, 
normally  related  to  age  and  remaining  economic  life.  Only  the  additional  costs  of  providing  those 
facilities that relate to the pollution abatement should be included. 

Manure storage 

For  those  techniques  requiring  capital  expenditure  by  farmers,  it  is  necessary  to  consider  the 
elements in the following table. 

Table 9.47:  Annual costs to consider in capital costs of manure storage systems 

Capital costs 

Additional storage  

Permanent covers 

All covers 

Annual costs to consider 

Annual charge, repair costs 
Annual charge, repair costs 
Cost of temporary covers on an annual basis 
Changes in labour requirements 
Reductions in rainwater dilution 

Manure landspreading 

Table 9.48:  Annual costs to consider in capital costs of manure storage systems 

Capital costs 
Low emission spreaders (compared to 
splash plate spreaders) 

Annual costs to consider 

Annual charge, repair costs 
Changes in tractor power requirements 
Changes in work rates 
Changes in labour requirements 

Intensive Rearing of Poultry or Pigs 

819 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annexes 

9.4  Reference techniques 

The  reference  (or  'baseline')  situation,  against  which  emission  reduction  percentages  can  be 
calculated, is in most cases the practice or design that is the most commonly applied technique 
presently found on commercial farms and is used to construct baseline inventories.  

Housing 

Animal category 

Reference housing system 

Laying hens in enriched cages  Non-aerated belts, two removals a week 
Laying hens in non-cage 
housing 
Broilers 

Deep litter (or deep pit) with a partially littered floor 

Turkeys 

Ducks 

Farrowing sows 

Mating and gestating sows 

Fattening pigs 

Weaners 

Fan-ventilated house with a solid, fully littered floor 
Solid, fully littered floor in closed, thermally insulated buildings with 
forced ventilation or in naturally ventilated houses with open side 
walls 
Fan-ventilated house with a solid, fully littered floor 
Crates with metal or plastic slatted floors and a deep manure pit 
underneath, forced ventilation 
Fully slatted floor (concrete slats) with a deep pit, forced ventilation 
Fully slatted floor with a deep manure pit underneath, forced 
ventilation 
Fully slatted floor (in pens or flatdecks) with metal or plastic slats and 
with a deep pit, forced ventilation 

Nutrition 
The baseline feeding strategy for each animal category is one-phase feeding without nutritional 
measures to reduce nutrient excretion.  

Manure storage 
The  baseline  for  estimating  the  efficiency  of  an  abatement  measure  is  the  emission  from  the 
same type of store, without any cover on the surface. 

Manure application 
The baseline for manure application is untreated slurry or solid manure spread over the whole 
soil surface ('broadcast') and not followed by incorporation, and not targeting application timing 
conditions that minimise NH3 loss. For slurry, this would typically consist of a tanker equipped 
with  a  discharge  nozzle  and  splash  plate.  For  solid  manures,  the  reference  case  would  be  to 
leave the manure on the soil surface without incorporation. 

Reference literature 
[ 43, COM 2003 ] [ 508, TFRN 2014 ] 

820 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
 
 
9.5  Data compilation for excretion 

9.5.1 

Total nitrogen excreted from pig rearing 

Annexes 

Figure 9.1:  Total nitrogen excreted by weaners 

Figure 9.2:  Total nitrogen excreted by fattening pigs (1 of 2) 

Intensive Rearing of Poultry or Pigs 

821 

 
 
 
 
 
 
 
 
 
Annexes 

Figure 9.3:  Total nitrogen excreted by fattening pigs (2 of 2) 

Figure 9.4:  Total nitrogen excreted by sows 

822 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
9.5.2 

Total phosphorus excreted from pig rearing 

Annexes 

Figure 9.5:  Total phosphorus excreted by weaners 

Figure 9.6:  Total phosphorus excreted by fattening pigs 

Intensive Rearing of Poultry or Pigs 

823 

 
 
 
 
 
 
 
 
Annexes 

Figure 9.7:  Total phosphorus excreted by sows 

9.5.3 

Total nitrogen excreted from poultry rearing 

Figure 9.8:  Total nitrogen excreted by laying hens 

824 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Annexes 

Figure 9.9:  Total nitrogen excreted by broilers 

Figure 9.10:  Total nitrogen excreted by ducks 

Intensive Rearing of Poultry or Pigs 

825 

 
 
 
 
 
 
Annexes 

Figure 9.11:  Total nitrogen excreted by turkeys 

9.5.4 

Total phosphorus excreted from poultry rearing 

Figure 9.12:  Total phosphorus excreted by laying hens 

826 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
Annexes 

Figure 9.13:  Total phosphorus excreted by broilers 

Figure 9.14:  Total phosphorus excreted by turkeys 

Intensive Rearing of Poultry or Pigs 

827 

 
 
 
 
 
 
 
Annexes 

9.6  Data compilation for ammonia emissions 

9.6.1 

Ammonia emissions to air from an animal house for pigs 

Figure 9.15:  Ammonia emissions to air from an animal house for mating and gestating sows (1 of 2) 

Figure 9.16:  Ammonia emissions to air from an animal house for mating and gestating sows (2 of 2) 

828 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
 
 
 
Annexes 

Figure 9.17:  Ammonia emissions to air from an animal house for farrowing sows 

Figure 9.18:  Ammonia emissions to air from an animal house for weaners (1 of 2) 

Intensive Rearing of Poultry or Pigs 

829 

 
 
 
 
 
 
Annexes 

Figure 9.19:  Ammonia emissions to air from an animal house for weaners (2 of 2) 

Figure 9.20:  Ammonia emissions to air from an animal house for fattening pigs (1 of 2) 

830 

Intensive Rearing of Poultry or Pigs 

 
 
 
 
 
 
Annexes 

Figure 9.21:  Ammonia emissions to air from an animal house for fattening pigs (2 of 2) 

9.6.2 

Ammonia emissions to air from an animal house for poultry 

Figure 9.22:  Ammonia emissions to air from an animal house for laying hens (1 of 2) 

Intensive Rearing of Poultry or Pigs 

831 

 
 
 
 
 
 
 
 
Annexes 

Figure 9.23:  Ammonia emissions to air from an animal house for laying hens (2 of 2) 

Figure 9.24:  Ammonia emissions to air from an animal house for broilers (1 of 2) 

832 

Intensive Rearing of Poultry or Pigs 

Annexes 

Figure 9.25:  Ammonia emissions to air from an animal house for broilers (2 of 2) 

Intensive Rearing of Poultry or Pigs 

833 

834 

Intensive Rearing of Poultry or Pigs 

References 

10  REFERENCES 

[1]  Eurostat, Food: from farm to fork statistics, Eurostat, 2011. 

[2]  Eurostat, Agri-environmental indicator - livestock patterns. 

http://ec.europa.eu/eurostat/statistics-explained/index.php/Agri-
environmental_indicator_-_livestock_patterns, 2017. 

[3]  Eurostat, Pig population - annual data 2005-2013, 2014. 

[4]  Eurostat, Pig farming sector - statistical portrait, 2014. 

[5]  The  Poultry  Site,  Upgrading  Hen  Housing:  Latest  Developments 

in  Europe. 
http://www.thepoultrysite.com/articles/1533/upgrading-hen-housing-latest-developments-
in-europe, 2017. 

[6]  Eurostat, Livestock density index, 2017. 

[7]  DG  AGRI,  Agriculture  in  the  European  Union.  Statistical  and  Economic  Information, 

2013. 

[8] 

[9] 

Portugal, Overview of intensive livestock farming in Portugal, 1999. 

Italy, IT Annexes, 2013. 

[10]  CIRCA, AGRI C4 Balance sheet for eggs, Balance sheet for poultrymeat, 2012. 

[11]  ADAS,  ILF  142  ADAS  The  practicability  of  fitting  various  types  of  emission  control 

cover to above, 2000. 

[12]  Eurostat, Livestock unit (LSU), 2015. 

[13]  Melse,  Air  treatment  techniques  for  abatement  of  emissions  from  intensive  livestock 

production, Wageningen University, Wageningen, NL, 2009. 

[14]  Spain, Pig CHAMP Pro Europa S.L. - PODZ, 2014. 

[15]  Eurostat, Agriculture statistics at regional level, 2014. 

[16]  Eurostat,  Agricultural  production 

-  animals.  http://ec.europa.eu/eurostat/statistics-

explained/index.php/Agricultural_production_-_animals, 2017. 

[17]  FAO, FOASTAT Livestock Primary, 2009. 

[18]  FAO, Tackling climate change through livestock. A global assessment of emissions and 

mitigation opportunities, FAO, 2013. 

[19]  Environment  Agency  (England  and  Wales),  Additional  guidance  for  H4  odour 
management  -  How  to  comply  with  your  environmental  permit,  Environment  Agency 
(England and Wales), 2011. 

[20]  COM, Communication from the Commission to the European Parliament and the Council 
on  the  various  systems  of  rearing  laying  hens  in  particular  those  covered  by  Directive 
1999/74/EC, 2008. 

[21]  EFSA,  Welfare  aspects  of  various  systems  for  keeping  laying  hens,  Scientific  report, 

EFSA-Q-2003-92, 2005. 

[22]  Bodemkundige Dienst, ILF 037 Bodemkundige Dienst, 1999. 

[23]  EPA (UK), ILF 060 EPA Groundwater Protection schemes, 1999. 

[24]  LNV, Handboek voor de pluimveehouderij, 1994. 

[25]  BPEX, http://www.bpex.org.uk, 2015. 

[26]  Finland, BAT report. Methods and techniques for reducing the environmental load due to 

intensive rearing of pigs and poultry, 2001. 

Intensive Rearing of Poultry or Pigs 

835 

References 

[27]  UR Wageningen, NH3  and dust emissions from broiler houses: Problems and solutions, 

2012. 

[28]  FORUM, Comments Forum to first draft, 2001. 

[29]  Pahl,  Environmental  factors  on  pig  production  -  Description  of  potential  emissions, 

causes, abatement and legislation, 1999. 

[30]  Spain, Comments on draft 2 ILF BREF, 2001. 

[31]  MAFF, Making better use of livestock manure on grassland, 1999. 

[32]  SCOPE, 'Agricultural phosphorus', SCOPE Newsletter, Vol. 21, 1997. 

[33]  Calvet et al., 'Measuring gas emissions from livestock buildings: A review on uncertainty 

analysis and error sources', Biosystems engineering, 116(3), pp.221-231, 2013. 

[34]  Ajinomoto,  Prevention  of  nitrogen  pollution  from  pig  husbandry  through  feeding 

measures, 2000. 

[35]  Netherlands, Text for discussion on IRPP BREF Landspreading, 2010. 

[36]  R&R, ILF 113 R&R Kombideksysteem, 2000. 

[37]  BOE  España,  Real  Decreto  949/2009  de  5  de  junio,  por  el  que  se  establecen  las  bases 
reguladoras  de  las  subvenciones  estatales  para  fomentar  la  aplicacion  de  los  procesos 
tecnicos del Plan de biodigestion de purines, 2009. 

[38]  ASG  Lelystad,  LAYWEL,  Welfare  implications  of  changes  in  production  systems  for 
laying hens. Description of housing systems for laying hens (deliverable23), 2006. 

[39]  Germany, Comments Germany to first draft (2003 ILF BREF formerly 124), 2001. 

[40]  NFU/NPA, Comments on the 2nd draft of the ILF BREF (2003 ILF BREF formerly 183), 

2001. 

[41]  Netherlands, Comments Netherlands to first draft (2003 ILF BREF formerly 122), 2001. 

[42]  Netherlands, Dutch notes on BAT for pig and poultry ILF (2003 ILF BREF formerly 10, 

1999. 

[43]  COM, Best Available Techniques (BAT) Reference Document for the Intensive Rearing 

of Poultry and Pigs (ILF BREF), 2003. 

[44]  IKC, ILF 128 NL technical description of systems for housing poultry species, 2000. 

[45]  E-PRTR, European Pollutant Release and Transfer Register (E-PRTR), 2017. 

[46]  Netherlands, RAV_E1.5.5_BWL2009.10_illustration, 2010. 

[47]  Netherlands, RAV_E2.12.1_BWL2004.11_illustration, 2010. 

[48]  Netherlands, RAV_E1.7_BWL2001.06_A, 2010. 

[49]  Germany, DE_housing_ pullets_litter, 2010. 

[50]  Austria, AT_pullet_Austria T rearing pullet, 2010. 

[51]  BE Flanders, BelgiumFlanders_input e-o-p treatment 
techniques_scrubbers_concerns_annex9, 2010. 

[52]  BE Flanders, BelgiumFlanders_e-o-p air treatment techniques_biobed_annex 10, 2010. 

[53]  Denmark, DK_aircleaning_biofilter, 2010. 

[54]  Denmark, DK_aircleaning_chemical, 2010. 

[55]  Denmark, DK_aircleaner_chemical_appendix, 2010. 

[56]  Denmark, DK_housing_poultry_manurebelt, 2010. 

[57]  Denmark, DK_appendix_housing_Poultry_manurebelt, 2010. 

836 

Intensive Rearing of Poultry or Pigs 

References 

[58]  Denmark, DK_housing_poultry_manuredry, 2010. 

[59]  Denmark, DK_appendix_housing_Poultry_manuredry, 2010. 

[60]  Germany, DE_housing_layers_aviaries, 2010. 

[61]  Germany, DE_housing_layers_aviaries, veranda, 2010. 

[62]  Germany, DE_housing_layers_aviaries,veranda,outdoor, 2010. 

[63]  Germany, DE_housing_layers_enriched cages, 2010. 

[64]  Germany, DE_housing_layers_litter, 2010. 

[65]  Germany, DE_housing_layers_litter,veranda, 2010. 

[66]  Germany, DE_housing_layers_litter,veranda,outdoor, 2010. 

[67]  Netherlands, RAV_E2.5.6_BWL2009.10_A, 2010. 

[68]  Spain, ES_poultry_laying_hen_1-1, 2010. 

[69]  Spain, ES_poultry_laying_hen_1-2, 2010. 

[70]  Netherlands, RAV_E2.12.1_BWL2004.11_A, 2010. 

[71]  Netherlands, RAV_E2.11.3_BWL2005.04_A, 2010. 

[72]  Netherlands, RAV_E2.11.4_BWL2005.05_A, 2010. 

[73]  Netherlands, RAV_E2.11.2_BWL2004.10_A, 2010. 

[74]  Netherlands, RAV_E1.8.2_BWL2005.03_A, 2010. 

[75]  Netherlands, RAV_E1.8.3_BWL2006.10_A, 2010. 

[76]  Netherlands, RAV_E1.8.4_BWL2006.11_A, 2010. 

[77]  Netherlands, RAV_E1.8.5_BWL2006.12_A, 2010. 

[78]  Netherlands, RAV_E1.8_BWL2005.0y_illustration, 2010. 

[79]  Netherlands, RAV_E1.8.1_BWL2005.02-A, 2010. 

[80]  Netherlands, RAV_E1.5.5_BWL2009.10_A, 2010. 

[81]  Germany, DE_housing_pullets_aviaries, 2010. 

[82]  Austria, AT_laying hens_Austria D laying hens in aviaries, 2010. 

[83]  Italy, IT 02 Laying hens-enriched cages, 2010. 

[84]  UK, UK_housing Laying hen enriched cages_4, 2010. 

[85]  UK, UK_laying hens_barn_1, 2010. 

[86]  UK, UK_laying hens_free range_2, 2010. 

[87]  Germany, DE_housing_broiler_litter, 2010. 

[88]  Italy, IT 03 Broiler cross V, 2010. 

[89]  Italy, IT 04 Broiler tunnel V, 2010. 

[90]  Italy, IT-broiler1, 2010. 

[91]  Italy, IT-broiler2, 2010. 

[92]  Italy, IT-broiler3, 2010. 

[93]  Netherlands, RAV_E5.9.1.2V1, 2010. 

[94]  Netherlands, RAV_E5.9.1.1V1, 2010. 

[95]  UK, Energy efficiency for broilers, 2010. 

[96]  UK, UK_broiler standard_1, 2010. 

Intensive Rearing of Poultry or Pigs 

837 

References 

[97]  UK, UK_broiler select_2, 2010. 

[98]  UK, UK_broiler_cross_B2, 2010. 

[99]  UK, UK_broiler_tunnel_B1, 2010. 

[100]  UK, UK_broiler_side_B3, 2010. 

[101]  UK, UK_broiler_ridge_B4, 2010. 

[102]  UK, UK_ housing turkey_1, 2010. 

[103]  UK, UK_ housing turkey_2, 2010. 

[104]  UK, UK_ducks_natural_1, 2010. 

[105]  UK, UK_ducks_forced_2, 2010. 

[106]  UK, UK_ducks_shed_3, 2010. 

[107]  UK, UK_ducks_FR_4, 2010. 

[108]  BE Flanders, BelgiumFlanders_input poultry_annex4_update 100302, 2010. 

[109]  Netherlands, RAV_E4.4.2_BWL2004.14_A, 2010. 

[110]  Netherlands, RAV_E4.8_BWL2007.10_A, 2010. 

[111]  Netherlands, RAV_E4.5_BB98.10.066_A, 2010. 

[112]  Netherlands, RAV_E4.4.1_BWL2004.13_A, 2010. 

[113]  Netherlands, RAV_E4.2_BB97.01.050_A99.02.067_A, 2010. 

[114]  Netherlands, RAV_E3.3_BWL2005.10.V2_A, 2010. 

[115]  Netherlands, RAV_G2.1 poultry, 2010. 

[116]  Germany, DE_housing_ducks_litter, 2010. 

[117]  Germany, DE_housing_young ducks_litter, 2010. 

[118]  Germany, DE_housing_young turkeys_litter, 2010. 

[119]  Germany, DE_housing_turkeys_litter, 2010. 

[120]  Germany, DE_biofilter, 2010. 

[121]  Germany, DE_biotricklingfilter, 2010. 

[122]  Germany, DE_2_stage_air_cleaner, 2010. 

[123]  Germany, DE_3_stage_air_cleaner, 2010. 

[124]  Netherlands, RAV_E7.3_BWL2009.19_A, 2010. 

[125]  Netherlands, NL_Combined_Scrubber_85_Uniqfill_A, 2010. 

[126]  Netherlands, NL_Combined_Scrubber_85_Inno+_A, 2010. 

[127]  Netherlands, NL_Combined_Scrubber_85_Dorset_A, 2010. 

[128]  Netherlands, NL_Combined_Scrubber_70_Big_Dutchman_A, 2010. 

[129]  Netherlands, NL_Combined_Scrubber_85_Devrie_A, 2010. 

[130]  Netherlands, NL_Chemical_Scrubber_95_Uniqfill_A, 2010. 

[131]  Netherlands, NL_Chemical_Scrubber_90_Inno+_A, 2010. 

[132]  Netherlands, NL_Chemical_Scrubber_70_Bovema_A, 2010. 

[133]  Netherlands, NL_Chemical_Scrubber_95_Bovema_A, 2010. 

[134]  Netherlands, NL_Chemical_Scrubber_70_Uniqfill_A, 2010. 

[135]  Netherlands, NL_Biological_scrubber_70_Dorset_A, 2010. 

838 

Intensive Rearing of Poultry or Pigs 

References 

[136]  UK, sid5: Poultry dust emissions, 2009. 

[137]  Netherlands, RAV_E7.2_F6.2_BWL2009.18_A, 2010. 

[138]  Netherlands, RAV_E7.1_F6.1_BWL2009.17_A, 2010. 

[139]  Netherlands, NL_Combined_Scrubber_70_Big_Dutchman_A_Illustration, 2010. 

[140]  Netherlands, RAV_E.7.1_BWL2009.17_illustration, 2010. 

[141]  Italy, IT_Drying_tunnel_Ramiran08, 2010. 

[142]  UK, Valeron: heat reflecting membranes/ radiant barriers 1 of 2, 2010. 

[144]  Finland, FI Housing Broilers_1, 2010. 

[145]  Finland, FI Housing Broilers_2, 2010. 

[146]  DEFRA,  Ammonia  Fluxes  Within  Broiler  Litter  And  Layer  Manure  Management 

Systems, 2002. 

[147]  Cabaraux et al., 'Gaseous emissions from weaned pigs raised on different floor systems. 

Agric. Ecosyst. Environ., 2009,130, 86-92.', 2009. 

[148]  BPC, Revision of Emission Factor for Broilers, 2009. 

[149]  Robertson  et  al.,  'Commercial-scale  Studies  of  the  Effect  of  Broiler-protein  Intake  on 
Aerial Pollutant Emissions', Biosystems Engineering, Vol. 82, 2002, pp. 217-225. 

[150]  CRPA,  'Il  tunnel  di  essiccazione  esterno  per  pollina:  benefici  ambientali  e  costi 

energetici', Professione Avicunicoltore, Vol. 9, No 10, 2008, pp. 2-7. 

[151]  Link CR, UK Poultry Industry IPPC Compliance, 2005. 

[152]  Link CR, UK Poultry Industry IPPC Compliance. Emissions to air from Highfield farm 

Commercial Duck rearing Houses, 2006. 

[153]  Netherlands, Background information on determination of emission levels, 2010. 

[154]  Czech Republic, Ionisation in pig stables, 2010. 

[155]  Germany, DE_housing waiting sow_kennel housing, 2010. 

[156]  Germany, DE_housing waiting sow_slatted floor with drained area, 2010. 

[157]  Germany, DE_housing waiting sow_plane floor and yard, 2010. 

[158]  EC,  'Council  Directive  2008/120/EC  of  18  December  2008  laying  down  minimum 
standards for the protection of pigs ', Official Journal of the European Union, Vol. L 47, 
18.2.2009, 2008, pp. 5-13. 

[159]  Austria, AT_sows_Austria P farrowing sow_mating gestating sow_waiting sow, 2010. 

[160]  Denmark, DK_housing_manure_cooling_waiting_sow, 2010. 

[161]  Germany, DE_housing mating_deep litter, 2010. 

[162]  Germany, DE_housing waiting sow_fully slatted with lying pen, 2010. 

[163]  Germany, DE_housing mating_group, 2010. 

[164]  Spain, ES_housing_gestating_sows_1, 2010. 

[165]  Netherlands, D1392 - BWL 2006.09_A, 2010. 

[166]  Netherlands, D1391 - BB0006085_A, 2010. 

[167]  Netherlands, Illustration D 1392 - BWL 2006.09, 2010. 

[168]  Netherlands, D_1.3.8.1__115%_-A- -cooling fins, 2010. 

[169]  Netherlands, D_1.3.8.2_135%_A - cooling fins, 2010. 

[170]  Spain, ES_housing_farrowing_sows_1, 2007. 

Intensive Rearing of Poultry or Pigs 

839 

References 

[171]  Germany, DE_housing farrowing_individual_1, 2010. 

[172]  Germany, DE_housing farrowing_individual_2, 2010. 

[173]  UK, UK_housing_fixed farrower_1, 2010. 

[174]  UK, UK_housing_fixed farrower_2, 2010. 

[175]  Ecodyn, Scottish pig industry - response to BREF, 2010. 

[176]  Netherlands, D_1.1.12.3___BB_99.06.072-A, 2010. 

[177]  Netherlands, D1131 - BWL 200606_A, 2010. 

[178]  Netherlands, Illustration D 1131 - BWL 2006.06, 2010. 

[179]  Spain, ES_housing_weaner_1, 2010. 

[180]  Spain, ES_housing_weaner_2, 2010. 

[181]  Germany, DE_housing weaner_deep litter, 2010. 

[182]  Germany, DE_housing weaner_fully slatted, 2010. 

[183]  Germany, DE_housing weaner_kennel housing, 2010. 

[184]  Germany, DE_housing weaner_partly_slatted, 2010. 

[185]  Germany, DE_housing weaner_plane floor and yard, 2010. 

[186]  BE Flanders, BelgiumFlanders_input pigs_annex6_update 100302, 2010. 

[187]  Spain, ES_housing_fattening_pigs_2, 2010. 

[188]  Spain, ES_housing_fattening_pigs_3, 2010. 

[189]  Germany, DE_housing fattening pig_fully slatted, 2010. 

[190]  Germany, DE_housing fattening pig_kennel_housing_partly slatted, 2010. 

[191]  Germany, DE_housing fattening pig_plane floor_yard, 2010. 

[192]  Germany, DE_housing fattening pig_partly slatted, 2010. 

[193]  Germany, DE_housing fattening pig_deep_litter, 2010. 

[194]  Netherlands, D32711 - BWL 200403_A, 2010. 

[195]  Netherlands, D32712 - BWL 200404_A, 2010. 

[196]  Spain, ES_housing_fattening_pigs_1, 2010. 

[197]  Denmark, DK_housing_manure_cooling_waiting_sow_appendix, 2010. 

[198]  Netherlands, D32161 - BWL 200810_A, 2010. 

[199]  Netherlands, Illustration D32161- BWL 2008.10, 2010. 

[200]  Netherlands, D32162 - BWL 200811_A, 2010. 

[201]  Mul M. et al, EU-Welfare legislation on pigs (Report 273), Wageningen UR, 2010. 

[202]  EAAP, 'Pig Housing system in Europe: current trends', 1998. 

[203]  ADAS, ES0138 Review of livestock manure management options in Europe, 2005. 

[204]  IMPEL, Final report IMPEL IPPC Pig farms - main, 2009. 

[205]  ADAS, Management techniques to minimise ammonia emissions during storage and land 

spreading of poultry manures, 2000. 

[206]  Silsoe, Fugitive emissions of methane from anaerobic digestion, 2000. 

[207]  ADAS,  Management  techniques  to  minimise  ammonia  emissions  from  solid  manures, 

2004. 

[208]  Spain, ES_slurry_storage_1, 2010. 

840 

Intensive Rearing of Poultry or Pigs 

References 

[209]  Denmark, DK_storage_natural floating layer, 2010. 

[210]  Denmark, DK_storage_Tent covering, 2010. 

[211]  Germany, DE_slurry storage_lagoon, 2010. 

[212]  Germany, DE_solid manure storage, 2010. 

[213]  Netherlands, Floating balls_A, 2010. 

[214]  Germany, DE_slurry storage_above-ground silo-water protection area, 2010. 

[215]  Germany, DE_slurry storage_below-ground silo, 2010. 

[216]  Denmark, DK_storage_Floating bricks, 2010. 

[217]  Denmark, DK_storage_Light tiles, 2010. 

[218]  Baltic  Sea  2020,  Best  Available  Technologies  for  Manure  Treatment,  Baltic  Sea  2020, 

2010. 

[219]  Netherlands, On farm manure treatment technology in the Netherlands, 2010. 

[220]  Germany, DE_Manure separator, 2010. 

[221]  Denmark, DK_treatment_slurry_seperation_screwpress, 2010. 

[222]  Denmark, DK_treatment_slurry_seperation_decanter_centrifuge, 2010. 

[223]  Denmark, DK_treatment_slurry_seperation_flocculation_appendix, 2010. 

[224]  Finland, FI Pellon Manure Treatment.pdf, 2010. 

[225]  Finland, Manure phosphorus fractionation by gypsum-based precipitate, 2010. 

[226]  Germany, DE_Manure belt-dryer, 2010. 

[227]  Denmark, DK_storage_fibre fraction covering, 2010. 

[228]  Denmark, DK_treatment_manureacid, 2010. 

[229]  Finland, FI Housing sows with anaerobic digester, 2010. 

[230]  Philippe et al., 'Gaseous emissions from group-housed gestating sows offered a high-fibre 

diet ad libitum. Agric. Ecosyst. Environ., 2009, 132, 66-73.', 2009. 

[231]  Italy, IT 06 Manure treatment dryer, 2010. 

[232]  Huijsmans  et  al.,  'Ammonia  and  nitrous  oxide  emissions  following  field-application  of 

manure: state of the art measurements in the Netherlands', 2009. 

[233]  Denmark, DK_application_trailing_hoses, 2010. 

[234]  Spain, ES_trailing_shoe_1, 2010. 

[235]  Spain, ES_bands_1 (trailing hose), 2010. 

[236]  Denmark, DK_application_injection_bare soil, 2010. 

[237]  Denmark, DK_application_injection_winter crop, 2010. 

[238]  Denmark, DK_application_injection_grassland, 2010. 

[239]  Spain, ES_incorporation_1, 2010. 

[240]  Italy, IT 05 Manure application dripline, 2010. 

[241]  Italy, IT-driplines-Ramiran116, 2010. 

[242]  CRPA, IT_driplines, 2009. 

[243]  Webb J. et al, 'Validating the MAVIS model for optimizing incorporation of litter-based 
manure  to  reduce  ammonia  emissions',  ASABE  Technical  Library  49(6):  1905-1913, 
2006. 

Intensive Rearing of Poultry or Pigs 

841 

References 

[244]  ADAS, Optimising slurry application timings to minimise nitrogen losses, 2006. 

[245]  ADAS, N2O and denitrification measurements on nutrient demo farms, 2002. 

[246]  Basford, NC Pulse Jet Irrigator. Evaluation of spread pattern and C of V % calculation, 

2010. 

[247]  IGER, Ammonia emissions from irrigation of dilute pig slurry, 2003. 

[248]  ADAS, Optimising the performance of low trajectory slurry application techniques, 2001. 

[249]  Webb  et  al.,  'Manure  applications  to  reduce  nitrate  and  ammonia  pollution:  scenario 

analysis using the MANNER model', Soil Use and Management, 2001. 

[250]  IGER, Field storage of manure and nitrous oxide emissions, 2004. 

[251]  KTBL, Ventilation in pig housing, 2009. 

[252]  IGER, Straw use in reducing NH3 emissions, 2005. 

[253]  ADAS, Environmental impacts of solid and liquid manure systems, 2002. 

[254]  Webb J.M. et al., Review of the efficiency of methods to reduce emissions of ammonia 
following the application of manures to land, their costs, potential agronomic benefits and 
impacts on emissions of nitrous oxide, 2009. 

[255]  BE Flanders, BelgiumFlanders Manure storage times in Flanders, 2010. 

[256]  VITO, Beste Beschikbare Technieken voor mestverwerking, 2006. 

[257]  France, French proposition concerning manure - chapter 2, 2010. 

[258]  France, French proposition concerning manure - chapter 3, 2010. 

[259]  France, French proposition concerning manure - chapter 4, 2010. 

[260]  IGER,  Predicting  ammonia  loss  following  the  application  of  organic  manures  to  land, 

2001. 

[261]  France, French proposition concerning pig housing - chapter 4, 2010. 

[262]  France, French proposition concerning pig housing - chapter 2, 2010. 

[263]  France, French proposition concerning pig housing- chapter 3, 2010. 

[264]  Loyon et al., 'Intensive livestock farming systems across Europe – A review of the current 
impact from the  IPPC directive based on data gathered by questionnaire', 14th Ramiran 
Conference, Lisboa 12-15 September 2010, 2010. 

[265]  BE Flanders, Extra costs for new to build housing systems in BelgiumFlanders, 2005. 

[266]  Austria, AT_fattening pigs_Austria U fattening pigs, 2010. 

[267]  UK, UK_housing_pig_finisher_1, 2010. 

[268]  Denmark, DK_housing_manure_cooling_fattening_pigs/gilts, 2010. 

[269]  France, Template for fully slatted floor for fattening pigs, 2010. 

[270]  France, Templates_FR_fullyslatted2, 2010. 

[271]  France, Templates_FR_partiallyslatted1, 2010. 

[272]  France, Templates_FR_partiallyslatted2, 2010. 

[273]  BE Flanders, BelgiumFlanders_annex12_Kostrpijs verbouwingen, 2010. 

[274]  BE  Flanders,  BeligumFlanders_annex11_summary  cost  prices  rebuilding  pig  housing 

systems, 2010. 

[275]  DIN,  DIN  18910-1:2004  Principles  for  planning  and  design  for  closed  ventilated 

livestock buildings, 2004. 

[276]  Finland, FI Housing FatteningPigs_1, 2010. 

842 

Intensive Rearing of Poultry or Pigs 

[277]  Ji-Qin  et  al.,  'Ammonia  emissions  from  a  large  mechanically-ventilated  swine  building 

during warm weather', Journal of Environmental Quality, Vol. 29, 2000. 

References 

[278]  Fefana, FEF-IPPC_Brumisation_ 10-04-06, 2010. 

[279]  Fefana, FEF Brumisation Dossier technique élevage, 2010. 

[280]  France, French proposition concerning feed- chapter 3, 2010. 

[281]  France, French proposition concerning feed- chapter 4, 2010. 

[282]  Netherlands, 1% Benzoic acid_A, 2010. 

[283]  Guingand  et  al.,  Effects  of  adding  0.5%  of  benzoic  acid  (VevoVitall®)  to  the  feed  of 

growing-finishing pigs on urinary pH, ammonia and performance (Trial Romillé), 2005. 

[284]  Guingand et al., Effects of adding 0.5% and 1% of benzoic acid (VevoVitall®) to the feed 
of growing-finishing pigs on urinary pH, ammonia and performance (Trial Villefranche 
de Rouergue), 2005. 

[285]  Fefana, FEF-Nutrition-Benzoic_Acid-KU_Leuven-2004, 2004. 

[286]  Guarino  et  al.,  Photocatalytic  TiO2  coating—to  reduce  ammonia  and  greenhouse  gases 

concentration and emission from animal husbandries, 2008. 

[287]  Jelínek et al., 'Research of the utilization of biotechnological agents for the reduction of 
ammonia and greenhouse gases emissions in livestock breeding in the Czech Republic', 
Research in Agricultural Engineering, Vol. 53, 2007, pp. 126-133. 

[288]  Wageningen, FEF_Nutrition_Benzoic_Acid-Wageningen, 2008. 

[289]  MLC, LS3601 Finishing Pigs - Systems Research, 2005. 

[290]  Univ. of Newcastle, WA0321 A review and workshop to agree advice on reduced nutrient 

pig diets, 2002. 

[291]  IRPP TWG, ILF 184 TWG ILF 2002, 2002. 

[292]  Italy, ILF 185 Italy, comments, n. 2, 2001. 

[293]  UK, UK_nutrition_layers free range_1, 2010. 

[294]  UK, UK_nutrition_layers rearers_1, 2010. 

[295]  UK, UK_nutrition_broilers_2, 2010. 

[296]  UK, UK_nutrition_broilers_3, 2010. 

[297]  UK, UK_nutrition_cage layers_1, 2010. 

[298]  UK, UK_nutrition_replacement layers_1, 2010. 

[299]  UK, UK_nutrition_turkeys_3, 2010. 

[300]  BE Flanders, Belgium Flanders_input pigs_update 100302, 2010. 

[301]  Fefana, FEF_Nutrition_Probiotics_Pigs_Davis, 2010. 

[302]  Fefana, FEF_Nutrition_Probiotics_Pigs-Maaroufi, 2010. 

[303]  Fefana, FEF_Nutrition_Probiotics_Broilers_Angel-Lactob-Exp1, 2010. 

[304]  Fefana, FEF_Nutrition_Enzymes_Pigs_Nielsen, 2010. 

[305]  Fefana, FEF_Nutrition_Enzymes_Pigs_Nielsen, 2010. 

[306]  Fefana, FEF_Nutrition_Probiotics_Broilers_Tarun, 2010. 

[307]  Fefana, FEF_Nutrition_Probiotics_Turkeys_Grimes, 2010. 

[308]  UK, UK_nutrition_weaners_1, 2010. 

[309]  UK, UK_nutrition_sows_1, 2010. 

Intensive Rearing of Poultry or Pigs 

843 

References 

[310]  UK, UK_nutrition_pigs_1, 2010. 

[311]  UK, UK_nutrition_pigs_2, 2010. 

[312]  Fefana, FEF_Nutrition_AminoAcids_Reduction CP_Broiler_Ferguson, 2010. 

[313]  Fefana, FEF_Nutirion_AminoAcids_ReductionCP_Turkey_Applegate, 2010. 

[314]  Fefana, FEF_Nutrition_AminoAcids_ReductionCP_Pigs_FullySlattedFloor, 2010. 

[315]  Fefana, FEF_Nutrition_AminoAcids_ReductionCP_Pigs_LatimierDourmad, 2010. 

[316]  Fefana, FEF_Nutrition_AminoAcids_ReductionCP_Layers_Hsu, 2010. 

[317]  Fefana, FEF_Nutrition_AminoAcids_BiphaseFeeding_Pigs_FullySlattedFloor, 2010. 

[318]  Fefana, FEF_Nutrition_AminoAcids_BiphaseFeeding_Pigs_Straw, 2010. 

[319]  Fefana, FEF_Nutrition_AminoAcids_BiphaseFeeding_Pigs_LatimierDourmad, 2010. 

[320]  Fefana, FEF_Nutrition_AminoAcids_PhasesFeeding_Pigs_BEthesis1, 2010. 

[321]  Fefana, FEF_Nutrition_AminoAcids_PhasesFeeding_Pigs_BEthesis2, 2010. 

[322]  Fefana, FEF_Nutrition_AminoAcids_PhasesFeeding_Pigs_BEthesis3, 2010. 

[323]  Finland, FI N and P excretion values per animal per yr, 2010. 

[324]  Netherlands, Protein effect_A, 2010. 

[325]  CRPA, N-low-feed-pigs, 2009. 

[326]  Germany, 5 templates on nutrition pigs, 2010. 

[327]  Germany, 7 templates on nutrition poultry, 2010. 

[328]  CORPEN, Estimation des rejets d'azote,phosphore, potassium, calcium, cuivre et zinc par 

les elevages avicole, 2006, p. 55. 

[329]  CORPEN, Estimation des rejets d’azote - phosphore -potassium - cuivre et zinc des porcs. 
Influence de la conduite alimentaire et du mode de logement des animaux sur la nature et 
la gestion des déjections produites, 2003. 

[330]  Denmark, DK_nutrition_Pig_protein, 2010. 

[331]  Raumberg, Effects of phytogenic feed additives used during pig fattening periods on the 
additives_Endbericht 

(AT_feed 

carrier 

gases 

reduction 
Aromex_710303_English (2).), 2010. 

noxious 

and 

of 

[332]  Delacon, DELACON_nutrition_broiler_1, 2010. 

[333]  Delacon, DELACON_nutrition_broiler_2, 2010. 

[334]  Lipinsky K., Efficiency of Biostrong 510 in broiler chicken nutrition, 2008. 

[335]  Spain, ES_nutrition_fatteningpigs_1, 2010. 

[336]  UK, Tried & Tested Nutrient Management Plan, 2010. 

[337]  Webb  et  al.,  'Webb,  menzi  et  al,  Managing  ammonia  from  livestock  production', 

Environmental Pollution, Vol. 135 (2005) 399-406, 2005. 

[338]  Piñeiro  et  al.,  Calculation  of  unit  cost  for  techniques  for  the  reduction  of  ammonia 
emissions from livestock production, Spanish Ministry of the Environment and Rural and 
Marine Affairs, 2009. 

[339]  ITAVI, 'ITAVI_CNEVA_1997_Maitrise de l'ambiance dans le batiments avicoles', 1997. 

[340]  ADEME, Utilisation rationnelle de l’énergie dans les batiments d’elevage, 2007. 

[341]  Amand et al., 'Evaluation des consommations d’énergies en élevage de volailles de chair', 

2007. 

[342]  ADEME, Les consommations d’énergie dans les bâtiments avicoles, 2008. 

844 

Intensive Rearing of Poultry or Pigs 

[343]  ADEME, 'Les consommations énergétiques dans les bâtiments porcins', 2008. 

[344]  ADEME, 'Consommations d’énergie des bâtiments porcins: comment les réduire ?', 2008. 

[345]  France, French proposition concerning energy- chapter 2, 2010. 

[346]  CA Bretagne, CA Bretagne 2009 Utilisation d'une chaudiere biommasse, 2009. 

References 

[347]  Bartolomeu, 'Echangeurs thermiques', 2007. 

[348]  Bartolomeu, 'Pompes à chaleur', 2008. 

[349]  ITAVI, 'La gestion technique des bâtiments avicoles', 1998. 

[350]  France, French proposition concerning energy- chapter 4, 2010. 

[351]  Marcon  M.,  'Maîtrise  de  l’énergie  dans  la  ventilation  et  le  chauffage  des  bâtiments 

porcins', TechniPorc, 2009. 

[352]  Bartolomeu, 'Echangeur thermique air-sol', 2005. 

[353]  CA  Pays  Loire,  'CRA  Pays  de  la  Loire_2009_Recupération  de  chaleur  en  aviculture  ', 

2009. 

[354]  ITAVI, 'La prévention coup de chaleur en aviculture', 2004. 

[355]  Warwick,  Energy  saving  by  the  application  of improved  ventilation technology  (Report 

AC0401), 2007. 

[356]  Carbon Trust, Energy Use in Pig Farming (ECG089), 2005. 

[357]  France, French proposition concerning water- chapter 2, 2010. 

[358]  France, French proposition concerning water- chapter 3, 2010. 

[359]  Massabie P, 'L'abreuvement des porcs ', 2001. 

[360]  Boulestreau, 'Effet de la brumisation en engraissement en periode estivale', 2006. 

[361]  France, French proposition concerning water- chapter 4, 2010. 

[362]  UK, Thornton Poultry Sheds Glenrothes, site plan, 2010. 

[363]  EHS, Guidance for Treating Lightly Contaminated Surface Run-off from Pig and Poultry 

Units, 2006. 

[364]  Portugal, Discharge of treated slurry to watercourses, 2010. 

[365]  France, French proposition concerning poultry housing - chapter 2, 2010. 

[366]  Renault et al, 'Etude de la qualité de l'air en élevages avicoles', 1997. 

[367]  Michel et al., 'Bien-etre de poules pondeuses logees en cage ou en voliere', 2005. 

[368]  France, French proposition concerning poultry housing - chapter 4, 2010. 

[369]  Harter-Dennis,  Summary  of  Research  UMES/AviHome  Flooring  System,  University  of 

Maryland Eastern Shore, 2010. 

[370]  Franck et al., 'Evaluation d'un dispositif de deodorisation du lisier de canard. Incidence du 

mode de la alimentation de la cuve de traitement', 2003. 

[371]  Penaud et al., 'Compostage sans retorunement d'un melange litieres de poulettes repro en 
presence de l'inoculum bacterien Bactivor', Septieme Journees de la Recherche Avicole, 
2007. 

[372]  Spain, Schematic representation of feed, water and heat distribution by a biomass burner 

in a broiler house, 2013. 

[373]  UBA  Austria,  Cross-media  environmental  control  in  selected  regions.  Hirnsdorf, 

Umweltbundesamt, 2009. 

[374]  Denmark, Appendix_DK_aircleaning_broilers_chemical, 2010. 

Intensive Rearing of Poultry or Pigs 

845 

References 

[375]  Philippe  et  al.,  'Emissions  d’ammoniac  lors  de  l’engraissement  de  porcs  sur  caillebotis, 
litière de paille accumulée et litière à pente paillée. Journées de la Recherche porcine en 
France, 2007, 6 – 8 février 2007, 39, 61-62.', 2007. 

[376]  Ferreira  et  al.,  The  importance  of  having  an  integrated  vision  of  livestock  housing  and 
water  management  -  new  challenges  for  environmental  management  in  the  pig  sector, 
2010. 

[377]  Netherlands, Internal side of poultry shed roof without and with use of ionisation, 2010. 

[378]  Robin  et  al.,  'Emissions  d’ammoniac  et  de  protoxyde  d’azote  des  porcs  engraissés  sur 

litière de paille', Journées Recherche Porcine, 2004. 

[379]  Spain, Implantación de la Directiva IPPC en España. Evaluación Técnica y Económica de 

MTDs en granjas, 2009. 

[380]  Delacon, Cost calculation_Delacon, 2011. 

[381]  Delacon, Report on BSG in EU 2010, 2011. 

[382]  BPEX, 2014 Pig cost of production in selected countries, 2016. 

[383]  France, French proposition on BREF Chapter 1, 2010. 

[384]  Fefana, Brumisation, 2011. 

[386]  DEFRA, Code of Good Agricultural Practice: Protecting our water, soil and air, 2009. 

[388]  BPEX, Bedding options for the English pig industry, 2011. 

[389]  ADAS, Managing Livestock Manures. Booklet 1. Making better use of livestock manures 

on arable land, 2001. 

[390]  ADAS,  Managing  Livestock  Manures.  Booklet  3.  Spreading  systems  for  slurries  and 

solid manures, 2001. 

[391]  Italy, Italian contribution to 2003 IRPP BREF, 1999. 

[392]  LEI Wageningen, Competitiveness of the EU egg industry.pdf, 2012, p. 47. 

[393]  ADAS, ADAS guidance of control of noise in poultry units, 1999. 

[394]  Smith  et  al.,  'Nitrogen  excretion  by  farm  livestock  with  respect  to  land  spreading 
requirements  and  controlling  nitrogen  losses  to  ground  and  surface  waters.  Part  2:  pigs 
and poultry', Bioresource Technology, Vol. 71 (2000) 183±194, 2000. 

[395]  ADAS, Guidance on energy control in pig units, 1999. 

[396]  LEI, Managing nitrogen pollution from intensive livestock production in the EU, 1999. 

[397]  Denmark, Danish BAT notes on pig farming for 2003 BREF, 2000. 

[398]  Finland, Biological treatment in a series of continuously aerated tank reactor, 2013. 

[399]  ID Lelystad, De forfataire excretie van stikstof door landbouwhuisdieren, 2000. 

[400]  Silsoe  Inst.,  'Concentrations  and  emission  rates  of  aerial  ammonia,  nitrous  oxide, 
methane,  carbon  dioxide,  dust  and  endotoxin  in  UK  broiler  and  layer  houses',  British 
Poultry Science, Vol. 38(1):14-28, 1997. 

[401]  Finland, Enhanced solid separation, efficient biological aeration  treatment and ammonia 

stripping, 2013. 

[402]  ADAS, Guidance on farm waste structures, 2000. 

[403]  EA, Towards sustainable agricultural waste management, EA, 2001. 

[404]  Tank manufacturer, Soluciones mundiales para depósitos, 2000. 

[405]  Tengman C.L. et al., Odor solution initiative testing, 2001. 

[406]  Netherlands, Dutch remarks on landspreading, 2002. 

846 

Intensive Rearing of Poultry or Pigs 

[407]  Netherlands, ILF 206 Netherlands Drinker systems, 2002. 

[408]  UK, ILF 220 UK Slurry spreading, 2002. 

[409]  VITO, Beste beschikbare technieken voor het be- en verwerken van dierlijke mest, 1997. 

References 

[410]  Greece, ILF 145 Comments Greece to first draft, 2001. 

[411]  Ireland, ILF 137 Comments Ireland to first draft, 2001. 

[412]  Italy, ILF 127 Comments Italy to first draft, 2001. 

[413]  Portugal, ILF 130 Comments Portugal to first draft, 2001. 

[414]  Fefana,  ILF  108  FEFANA  Amino  Acid  Working  Party  Input  to  the  BREF  Document 

(Comment to 1st Draft of BREF document), 2001. 

[415]  BPEX, 2009 Pig cost of production in selected countries, BPEX, 2010. 

[416]  COM,  Evaluation  of  the  livestock  sector's  contribution  to  the  EU  greenhouse  gas 

emission (GGELS), 2010. 

[417]  ITAVI, Document de synthese: Resultats 2011 des enquêtes poulettes et pondeuses, 2012. 

[418]  ITAVI, Performances techniques et couts de production en volailles de chair, poulettes et 

poules pondeuses, ITAVI, 2010. 

[419]  Red Tractor, Pig Standards, 2011. 

[420]  Ramonet,  'L’élevage  des  porcs  sur  litière.  Une  diversité  de  systèmes  en  engraissement', 

Journées Recherche Porcine, Vol. 35, 2003, pp. 1-6. 

[421]  Netherlands, Ventilation rates in pig housing (Klimaatplatform varkenshouderij), 2011. 

[422]  Taylor N., LIghting for Pig Units, BPEX, 2010. 

[423]  Gill  P.,  Comparison  of  water  use  from  different  drinker  types  by  weaned,  growing  and 

finishing pigs, 1989. 

[424]  VERA,  Test  Protocol  for  Air  Cleaning  Technologies,  VERA  (Verification  of 

Environmental Technologies for Agricultural Production), 2010. 

[425]  DEFRA, Fertiliser Manual (RB209) 8th Edition, TSO, 2010. 

[427]  COM,  Report  from  the  Commission  to  the  Council  and  the  European  Parliament  on 
implementation  of  Council  Directive  91/676/EEC.  Reports  for  the  period  2004-2007 
(COM(2010)47 ), European Commission, 2010. 

[428]  GEC, Assessment on Peatlands, Biodiversity and Climate change, 2008. 

[429]  Texier  et  al.,  'Production  et  composition  des  fumiers  de  porcs  engraissés  sur  sciure, 

copeaux ou écorce', TechniPorc, Vol. 27, 2004, pp. 29-37. 

[430]  Paulicks  et  al.,  'Studies  on  the  tryptophan  requirement  of  lactating  sows.  Part  1: 
Estimation of the tryptophan requirement by performance', Journal of Animal Physiology 
and Animal Nutrition, Vol. 90, 2006, pp. 474-481. 

[431]  MARM, Guía de Mejores Técnicas Disponibles del sector porcino, 2010. 

[432]  BPEX, Commercial Pig Unit Electricity Monitoring Project loc, 2010. 

[433]  CORPEN,  Les  emissions  d'ammoniac  et  de  gaz  azotés  à  effet  de  serre  en  agriculture, 

CORPEN, 2006. 

[434]  ITAVI, 'Aviculture et respect de l’environnement', Sciences et Techniques Avicoles, hors 

série, 2001. 

[435]  Van Gansbeke et al., Groepshuisvesting van zeugen, 2011. 

[436]  Guingand  N.,  'Emission  d’ammoniac  liée  au  stockage  de  lisier  de  porcs:  résultats  de 

laboratoire et de terrain', Journées de la Recherche Porcine, Vol. 34, 2002, pp. 161-166. 

Intensive Rearing of Poultry or Pigs 

847 

References 

[437]  Agrsci, Normtal baggrundstal, 2008. 

[438]  Lacey et al., 'A Review of Literature Concerning Odors, Ammonia, and Dust from Broiler 
Production  Facilities:  1.  Odor  Concentrations  and  Emissions',  The  Journal  of  Applied 
Poultry Research, Vol. 13, 2004, pp. 500-508. 

[439]  Sommer  et  al.,  Algorithms  Determining  Ammonia  Emission  From  Buildings  Housing 

Cattle And Pigs And From Manure Stores, Advances in Agronomy, 2006, pp. 261-335. 

[440]  Webb  et  al.,  The  impacts  of  manure  application  methods  on  emissions  of  ammonia, 
nitrous  oxide  and  on  crop  response—A  review,  Agriculture,  Ecosystems  and 
Environment, 2010, pp. 39-46. 

[441]  Webb et al., Gaseous emissions during the management of solid manures. A review, in 

press, 2012. 

[442]  Hansen  et  al.,  Emissionsfaktorer til  beregning  af  ammoniakfordampning  ved  lagring  og 
udbringning af husdyrgødning, AgroTech, Institut for Jordbrugs- og Fødevareinnovation, 
2008. 

[443]  Chadwick  et  al.,  'Manure  management:  implications  for  greenhouse  gas  emissions', 

publication in progress, Vol. publication in progress, 2011. 

[444]  Haeussermann  et  al.,  'Influence  of  season,  ventilation  strategy,  and  slurry  removal  on 
methane  emissions  from  pig  houses',  Agriculture,  Ecosystems  and  Environment,  Vol. 
112, 2006, pp. 115-121. 

[445]  VERA, Test Protocol for Livestock Housing and Management Systems - version 2-2011-

29-08, 2011. 

[446]  Bouvarel  et  al.,  'Alimentation  sequentielle  et  maitrise  de  l’ingestion  chez  le  poulet  de 
chair effets des teneurs energetiques et proteiques des aliments', Septièmes Journées de la 
Recherche Avicole, Tours, 28 et 29 mars 2007. 

[447]  Finland, Mechanical separation enhanced by chemical flocculation, 2013. 

[448]  Aarnink et al., 'Nutrition, key factor to reduce environmental load from pig production', 

Livestock Science, Vol. 109, 2007, pp. 194-203. 

[449]  Edwards et al., PigSafe project UK, 2012. 

[450]  IFIP, 

'Note  de  conjoncture  Aliment',  Note  de  conjoncture  Aliment,  Mensuel 

d'information, 2011. 

[451]  Portejoie et al., 'Effet de la réduction du taux protéique de l’aliment sur la volatilisation 
ammoniacale des effluents porcins', Journées de la Recherche Porcine, Vol. 34, 2002, pp. 
167-174. 

[452]  Fefana,  FEFANA  WP  Enzymes  proposal  for  the  part  Phytase  (Chapter  4  of  BREF 

document draft 2, on the intensive farming of poultry and pigs), 2002. 

[453]  DEFRA, LK0973 project page, 2011. 

[454]  Eriksen et al., 'Emissions of sulfur-containing odorants, ammonia, and methane from pig 
slurry: effects of dietary methionine and benzoic acid.', Journal of Environmental Quality, 
Vol. 39, 2010, pp. 97-107. 

[455]  Männer, Efficacy of Fresta F and Fresta F Plus on performance in sows from day 90 of 
gestation  to  day  25  day  postpartum,  Institut  of  Animal  Nutrition,  Faculty  of  Veterinary 
Medicine, Free University Berlin, 2011. 

[456]  Delacon, Cost calculation for Fresta® F Plus, 2011. 

[457]  Delacon, Market report in selected markets 2010, 2011. 

[458]  Veit  et  al.,  Effects  of  phytogenic  feed  additives  containing  Quillaja  saponaria  on 
ammonia  in  fattening  pigs,  Delacon,  Agricultural  Research  and  Education  Centre 
Raumberg-Gumpenstein, 2011. 

848 

Intensive Rearing of Poultry or Pigs 

References 

[459]  Overults et al., How much attic insulation?, 2008. 

[460]  COM,  Report  from  the  Commission  to  the  Council  and  the  European  Parliament  on 
implementation  of  Council  Directive  91/676/EEC.  Reports  for  the  period  2008-2011 
(COM(2013) 683 final), 2013. 

[461]  Glo, A new Energy Efficient Era for Global Farming, 2010. 

[462]  VITO, Beste Beschikbare Technieken (BBT) voor de veeteeltsector, 2005. 

[463]  Wageningen UR, Aanpakken bij de bron! Netwerk ‘stof tot nadenken’, 2010. 

[464]  Netherlands, RAV E5.11 / BWL2010.13.V1. Heat exchanger with ventilators, 2010. 

[465]  Netherlands, Picture E5.11 heat exchanger with ventilators, 2011. 

[466]  Bonnouvrier et al., 'Alternative energy on poultry farms: study of a heat recovery system', 
EUROPEAN FORUM, Livestock housing for the future, Vol. 978-2-84148-772-1, 2009, 
Lille. 

[467]  BE Flanders, Belgium Flanders_input poultry_update 100302, 2010. 

[468]  CBS,  Huisvesting  van  landbouwhuisdieren  2008,  Centraal  Bureau  voor  de  Statistiek, 

2011. 

[469]  Netherlands, Stal met mixluchtventilatie, 2011. 

[470]  Netherlands, RAV E5.10 / BWL 2009.14, 2011. 

[471]  Netherlands,  BWL  2009.14.V2,  Stal  met  verwarmingssysteem  met  (indirect  gestookte) 

warmteheaters en ventilatoren, 2011. 

[472]  Fefana, 'Probiotic Market data', Personal Communication, 2011. 

[473]  Infomil, Sample of the list of housing descriptions leaflet for category E 5, 2011. 

[474]  VDI,  VDI  3894  B1/Part  1  September  2011  Emissionen  und  Immissionen  aus 
Tierhaltungsanlagen.  Emissions  and  immissions  from  animal  husbandries  Housing 
systems and emissions: Pigs, cattle, poultry, horses, 2011. 

[475]  Merlet  et  al.,  'Evaluation  de  l’Impact  Carbone  en  production  de  canards  à  rôtir:  une 
approche de terrain des systèmes d’élevage sur caillebotis et sur litière', TeMA, Vol. 13, 
2010, pp. 31-38. 

[476]  AEAT, Atmospheric Emissions From Small Carcass Incinerators, 2002. 

[477]  O'Dea et al., 'Investigating the Effects of Commercial Probiotics on Broiler Chick Quality 

and Production Efficiency', Poultry Science, Vol. 85, 2006, p. 1855:1863. 

[478]  Sieo  et  al.,  'Influence  of  β-Glucanase-Producing  Lactobacillus  Strains  on  Intestinal 
Characteristics  and  Feed  Passage  Rate  of  Broiler  Chickens',  Poultry  Science,  Vol.  84, 
2005, p. 734:741. 

[479]  Bedford et al., Enzyme in Farm Animal Nutrition, 2nd edition, CABI, 2011. 

[480]  Yu et al., 'Effects of enzyme inclusion in a maize–soybean diet on broiler performance', 

Animal Feed Science and Technology, Vol. 134, 2007, p. 283–294. 

[481]  Thacker,  'Fed  Wheat  or  Corn  Based  Diets  Supplemented  With  Xylanase  or  Protease 
Alone or in Combination', Journal of Animal and Veterinary Advances, Vol. 4, 2, 2005, 
pp. 276-281. 

[482]  Cowieson  et  al.,  'Carbohydrases,  Protease,  and  Phytase  Have  an  Additive  Beneficial 
Effect in Nutritionally Marginal Diets for Broiler Chicks', Poultry Science, Vol. 84, 2005, 
p. 1860–1867. 

[483]  Cowieson et al., Interactions between xylanase and glucanase in maizesoy-based diets for 

broilers, British Poultry Science, 2010, pp. 246-257. 

Intensive Rearing of Poultry or Pigs 

849 

References 

[484]  Windisch  et  al.,  Use  of  phytogenic  products  as  feed  additives  for  swine  and  poultry, 

Journal of Animal Science, 2008, pp. E140-E148. 

[485]  Gutierrez  del  Alamo  et  al.,  'Effect  of  Wheat  Cultivar  and  Enzyme  Addition  to  Broiler 
Chicken  Diets  on  Nutrient  Digestibility,  Performance,  and  Apparent  Metabolizable 
Energy Content', Poultry Science, Vol. 87, 2008, pp. 759-767. 

[486]  Pelletier et al., Gas and odor emissions from swine building materials, Transactions of the 

ASABE, 2005, pp. 721-728. 

[487]  Aarnink et al., 'Effect of Type of Slatted Floor and Degree of Fouling of Solid Floor on 
Ammonia Emission Rates from Fattening Piggeries', J. agric. Engng Res, Vol. 66, 1997, 
p. 93 – 102. 

[488]  Pedersen  et  al.,  Characteristics  of  Floors  for  Pig  Pens:  Friction,  shock  absorption, 
ammonia emission and heat conduction, Agricultural Engineering International, 2008. 

[489]  Pedersen  et  al.,  'A  New  Design  For  Highly  Efficient  Partial  Pit  Ventilation',  XVIIth 
World  Congress  of  the  International  Commission  of  Agricultural  Engineering  (CIGR), 
2010, Québec City, Canada. 

[490]  Pedersen  et  al.,  Perstrup  Pig  House  With  Partial  Under-Floor  Air  Evacuation  And  In-

House Separation Of Faeces And Urine, 2011. 

[491]  Guingand  N.,  'Influence  de  la  vidange  des  préfosses  sur  l’émission  d’ammoniac  et 
d’odeurs  par  les  porcheries  d’engraissement.  Résultats  préliminaires',  Journées  Rech. 
Porcine en France, Vol. 32, 2000, pp. 83-88. 

[492]  COM, Report on animal by-products, European Commission Directorate General Health 

& Consumer Protection, 2005. 

[493]  Guingand  et  al.,  'Emissions  comparées  d’ammoniac  et  de  gaz  à  effet  de  serre  par  des 
porcs  charcutiers  élevés  au  froid  sur  caillebotis  partiel  ou  à  la  thermoneutralité  sur 
caillebotis intégral', Journées Recherche Porcine, Vol. 42, 2010, pp. 277-283. 

[494]  EFSA, Animal health and welfare aspects of different housing and husbandry systems for 
adult  breeding  boars,  pregnant,  farrowing  sows  and  unweaned  piglets,  European  Food 
Safety Authority (EFSA), 2007. 

[495]  EFSA, The risks associated with tail biting in pigs and possible means to reduce the need 
for tail docking considering the different housing and husbandry systems, European Food 
Safety Authority, 2007. 

[496]  Sharpe  et  al.,  'Methane  emissions  from  an  anaerobic  swine  lagoon',  Atmospheric 

Environment, Vol. 33, 1999, pp. 3627-3633. 

[497]  BE Flanders, Flemish list of housing systems, 2010. 

[498]  Ćernåk, Overflow Slurry Channels, 1977. 

[499]  AgroTech,  Forarbejde  til  Teknologiudvalget  -  Preliminary  work  for  the  Technology 

Committee. Miljøprojekt Nr. 1246 2008, 2008. 

[500]  IRPP TWG, Comments to Draft 1 revised BREF, 2011. 

[501]  Aubert et al., 'Utilisation d’un complexe de microorganismes pour reduire les emissions 
d’ammoniac en elevage de poulets', Neuvièmes Journées de la Recherche Avicole, 2011, 
Tours. 

[502]  Guinebert  et  al.,  'Interet  d’un  traitement  biologique  des  litieres  de  volailles  par  apport 
d’un  additif  microbien  en  presence  des  animaux',  Sixièmes  journées  de  la  Recherche 
Avicole, 2005, Saint Malo. 

[503]  Vermeij, Costs available measures to reduce fine dust (Informatiebijeenkomst fijn stof), 

2011. 

[504]  KTBL, Abluftreinigung in der Schweinehaltung - Verfahren, Einsatzbereiche, Leistungen 

und Kosten, 2010. 

850 

Intensive Rearing of Poultry or Pigs 

References 

[505]  Hahne  J.,  'Development  of  exhaust  air  treatment  in  animal  husbandry  in  Germany', 

Landtechnik, Vol. 66, 2011, pp. 289-292. 

[506]  TWG  ILF  BREF,  Complete  Comments  to  2003  ILF  BREF  Draft  2  (Excel  spreadsheet 

with all comments on draft 2), 2001. 

[507]  COM, Best Available Techniques (BAT) Reference Document for Common Waste Water 
and Waste Gas Treatment/Management Systems in the Chemical Sector (CWW BREF), 
European Commission - JRC IPTS EIPPCB, 2016. 

[508]  TFRN,  Options  for  Ammonia  Mitigation  -  Guidance  from  the  UNECE  Task  Force  on 

Reactive Nitrogen, 2014. 

[509]  Province Antwerpen, Invloed va klimaat op de groei van vleeskuikens. Studienamiddagen 

Pluimveehouderij, 1999. 

[510]  EFSA, Animal health and welfare in fattening pigs in relation to housing and husbandry, 

2007. 

[511]  Le et al., 'Effects of dietary crude protein level on odour from pig manure', Animal, Vol. 

2007, No 1, 2007, pp. 734-744. 

[512]  Andree  et  al.,  'The  Effect  of  Protein  Supply  on  Odour  Emission  from  Fattening  Pigs', 

Landtechnik, Vol. 58, 2003, pp. 38-39. 

[513]  Mol and Ogink, Geuremissies uit de veehouderij II, Wageningen UR, 2002. 

[514]  KTBL,  Exhaust  air  treatment  systems  for  animal  housing  facilities,  KTBL,  2008,  p. 

KTBL publication 464. 

[515]  UR  Wageningen,  Maatregelen 
indicatieve 

ter  vermindering  van 
evaluatie 

van 

pluimveehouderij: 
biofiltratie 
fijnstofreductietechniek, Wageningen UR Livestock Research, 2010. 

fijnstofemissie  uit  de 
potentiële 

als 

[516]  TÜV, Bericht Über Die Zertifizierung der Biofilteranlage der Firma Hartmann Biofilter 
für  den  Anwendungsfall  der  ma  Hartmann  Biofilter  für  Den  Anwendungsfall  der 
Schweinehaltung  hinsichtlich  der  Abscheidewirkung  ge-  Schweinehaltung  hinsichtlich 
der Abscheidewirkung gegenüber Staub, Geruch, Ammoniak und Keime genüber Staub, 
Geruch, Ammoniak und Keime, TÜV RHEINLAND, 2009. 

[517]  Petersen et al., 'Ammonia and nitrous oxide interactions: Roles of manure organic matter 

management', Animal Feed Science and Technology, Vol. 166-167, 2011, pp. 503-513. 

[518]  Sommer  et  al.,  'Greenhouse  Gas  Emission  from  Stored  Livestock  Slurry',  Journal  of 

Environmental Quality, Vol. 29, 1999, pp. 744-751. 

[519]  Amon et al., 'Amon Kryvorutchko fulltext', Vol. 112, 2007, pp. 199-207. 

[520]  Fleming R., Liquid Manure Storage Covers, 2006. 

[521]  Portejoie et al., 'Effect of covering pig slurry stores on the ammonia emission processes', 

Vol. 87, 2003, pp. 199-207. 

[522]  Loyon et al., 'Réduction des émissions d’ammoniac au cours du stockage du lisier porcin: 
Evaluation grandeur réelle d’une couverture de balles en polystyrène', Vol. 39, 2007, pp. 
49-54. 

[523]  Leip et al., 'Impacts of European livestock production: nitrogen, sulphur, phosphorus and 
greenhouse gas emissions, land-use, water eutrophication and biodiversity', 2015. 

[524]  UK EA, How to comply with your environmental permit for intensive farming. Appendix 

9-Producing a proposal for covering slurry stores, 2012. 

[525]  BPEX, Covering slurry stores. Benefits, Practicalities and Available Options, 2011. 

[526]  Hansen  et  al.,  'Observations  of  production  and  emission  of  greenhouse  gases  and 
ammonia during storage of solids separated from pig slurry: Effects of covering', Vol. 40, 
2006, p. 4172–4181. 

Intensive Rearing of Poultry or Pigs 

851 

References 

[527]  Hamelin et al., Life Cycle Assessment of Biogas from Separated slurry, 2010. 

[528]  ITAVI,  'Sciences  Et  Techniques  Avicoles,  Hors  série:  Aviculture  et  respect  de 
l'environnement', Vol. Hors série: Aviculture et respect de l'environnement, 2001, pp. 53-
59. 

[529]  Veneto  Agricoltura,  Nitrati  da  problema  a  risorsa.  Stato  dell'arte  e  opportunità  dalle 

esperienze di progetto, 2012. 

[530]  Nicks  et  al.,  'Emissions  d’ammoniac,  de  protoxyde  d’azote,  de  méthane,  de  gaz 
carbonique  et  de  vapeur  d’eau  lors  de  l’élevage  de  porcs  charcutiers  sur  litière 
accumulées de paille et de sciure. Journées de la Recherche Porcine en France, 2003, 35, 
4 – 6 février 2003, 7 – 14.', Vol. 35, 2003, pp. 7-14. 

[531]  Ramonet et al., 'L’engraissement de porcs sur litière de particules de bois ou de sciure en 

couche fine', Vol. 34, 2002, pp. 143-148. 

[532]  Nicks  et  al.,  'Emissions  d’ammoniac,  de  protoxyde  d’azote,  de  méthane,  de  gaz 
carbonique et de vapeur d’eau lors de l’élevage de porcelets sevrés sur litière accumulée 
de paille et de sciure. Journées de la Recherche Porcine en France, 2002, 34, 5 – 7 février 
2002, 149 – 154.', Vol. 34, 2002, pp. 149-154. 

[533]  Baltic Sea 2020, Best Available Technologies for Pig Manure Biogas Plants in the Baltic 

Sea Region, 2011. 

[534]  AFBI, AFBI Magowan PPDC-report-the-effect-of-drinker-design, 2007. 

[535]  UK, Weaner on straw template, 2011. 

[536]  Sagoo et al., 'Integrated management practices to minimise losses and maximise the crop 

nitrogen value of broiler litter', Vol. 97, 2007, pp. 512-519. 

[537]  COM, ILF 191 EC. Storage vessels for manure storage (5), 1999. 

[538]  Netherlands, ILF 138 Netherlands. Nitrogen and phosphorus consumption utilisation and 

losses in pig production, 1999. 

[539]  MAFF, ILF 110 MAFF. Phase feeding pigs to reduce nutrient pollution - N in pig slurry., 

Scientific, 1999. 

[540]  MAFF,  "Phase  feeding  pigs  to  reduce  nutrient  pollution  -  ammonium-N  emission  from 

application", WA0317, 1999. 

[542]  CEFIC, ILF 198. Highly digestible inorganic feed phosphates, 2002. 

[543]  Fefana,  ILF  199.  Addition  of  specific  feed  additives.  CEFIC,  (2002).  Highly  digestible 

inorganic feed phosphates, 2002. 

[544]  Netherlands, ILF 178. Additional information about Combideck system in broiler houses, 

2002. 

[545]  Netherlands, ILF 181. (additional) Comments on the 2nd draft ILF BREF, 2002. 

[546]  TWG  ILF,  ILF  186  DK-NL.  Manure  surface  cooling  channel  in  combination  with  a 

closed heat exchanger, 2002. 

[547]  IMAG-DLO, ILF 187. Nürtinger system, 2001. 

[548]  TWG ILF, ILF 189 Italy-UK. Pens with straw bedded floor; natural ventilation, 2002. 

[549]  IMAG-DLO,  ILF  175.  Environmental  aspect  of  a  group  housing  system  for  sows  with 

feeding stations and straw, 1999. 

[550]  IPCC, N2O Emissions From Managed Soils, And CO2 Emissions From Lime And Urea 

Application, 2006. 

[551]  Oenema et al., 'Onema et al 2005, trends in global nitrous oxide emissions from animal 
production systems', Nutrient Cycling in Agroecosystems, Vol. 72, 2005, pp. 51-65. 

[552]  IDELE, L'eclairage artificiel des batiments d' élevage de ruminants, 2012. 

852 

Intensive Rearing of Poultry or Pigs 

References 

[553]  bhsl, Report to Board for Wimpstone Batch 4, 2011. 

[554]  EPA (IE), ILF 001 and ILF 002 Batneec Guidance Note for the Pig Production Sector and 

for the Poultry production Sector, 1998. 

[555]  MAFF, ILF 040 Guidelines for Farmers guide in NVZs, 1998. 

[556]  ADAS,  ILF 143 Silsoe, Low-cost covers to abate gaseous emissions from slurry stores, 

2000. 

[557]  MAFF,  "Calculating  the  cost  of  best  available  techniques  for  the  intensive  rearing  of 

poultry and pigs (draft)", 2000. 

[558]  COM, ILF 195 Livestock manure Brochure, 1999. 

[559]  ADAS, ILF 069 ADAS guidance of control of noise in pigs units, 1999. 

[560]  IGER, ILF 202 IGER Treatment of livestock wastes through the use of additives, CSG 15 

(rev. 1299), 2000. 

[561]  Flotats  et  al.,  Guia  de  los  tratamientos  de  las  deyecciones  ganaderas,  Generalitat  de 

Catalunya, 2004. 

[562]  MARM, IMG_0974 band spreader, 2011. 

[563]  MARM, IMG_0929.JPG, 2011. 

[564]  bhsl, 12 07 10, Example Large UK Farm CL2E system (bhsl), 2012. 

[565]  NFU,  '12  07  13  to  NFU  fm  bhsl  re  input  for  IPPC  brief  from  BREF  doc  _5',  Personal 

Communication, 2012. 

[566]  EFSA, Scientific Opinion concerning a Multifactorial approach on the use of animal and 

non-animal-based measures to assess the welfare of pigs, 2014. 

[567]  Nicks B., 'Caractéristiques techniques et aspects environnementaux de l’élevage de porcs 
charcutiers et de porcelets sevrés sur litières accumulées. Ann. Méd. Vét., 2004, 148, 31-
38.', 2004. 

[568]  Melse  et  al.,  'Multi-pollutant  scrubbers  for  removal  of  ammonia,  odour  and  particulate 

matter from animal house exhaust air', 2010. 

[569]  UR Wageningen, Report 215 Wageningen. Measures to reduce fine dust emission from 

poultry houses: reduction from broiler houses by ionization, 2009. 

[570]  ALTERRA, Calculated losses of gaseous nitrogen compounds from livestock manure in 

stables and manure storage systems. Alterra Report 107, 2000. 

[571]  Eurich-Menden  et  al.,  'Ammonia  emission  factors  within  the  agricultural  emission 

inventory - Part 2: Poultry and fattening pigs', 2011. 

[572]  Fefana, Questionnaire on Nutrition-Amino acids, 2010. 

[573]  DSM  et  al.,  'Economic  and  environmental  benefits  of  Ronozyme  ProAct',  Personal 

Communication, 2012. 

[574]  UBA Germany, Matrix parameters and storage conditions of manure, 2011. 

[575]  UBA  Germany,  Systematic  cost-benefit  analysis  of  reduction  measures  for  ammonia 

emissions in agriculture for national cost estimates, 2011. 

[576]  COM,  JRC  Reference  Report  on  Monitoring  of  Emissions  to  Air  and  Water  from  IED 

installations (ROM REF), European Commission, JRC IPTS EIPPCB, 2017. 

[577]  IAF, International Accreditation Forum website, 2010. 

[578]  DG Environment, What is Emas?, 2010. 

[579]  EC, 'Regulation (EC) No 1221/2009 of the European Parliament and of the Council of 25 
November  2009  on  the  voluntary  participation  by  organisations  in  a  Community  eco-
management  and  audit  scheme  (EMAS),  repealing  Regulation  (EC)  No  761/2001  and 

Intensive Rearing of Poultry or Pigs 

853 

References 

Commission Decisions 2001/681/EC and 2006/193/EC', Official Journal of the European 
Union, Vol. L 342, 22.12.2009, pp. 1-45. 

[580]  CEN,  EN  ISO  14001:2015  Environmental  management  systems  –  Requirements  with 

guidance for use, 2015. 

[581]  COM,  Best  Available  Techniques  (BAT)  Reference  Document  in  the  Slaughterhouses 

and Animal By-products Industries (SA BREF), 2005. 

[582]  Wageningen NL, Measures to reduce fine dust emission from poultry: optimisation of an 

oil spraying system for broilers, 2009. 

[583]  Netherlands, 'Illustration of floating balls', Personal Communication, 2010. 

[584]  Netherlands, Floating balls and benzoic acid, 2010. 

[585]  Netherlands, Broilers in multifloor system on tiers with manure belt, 2010. 

[586]  Netherlands, Broilers housing with litter and forced ventilation, 2010. 

[587]  Netherlands, Multifloor system on tiers for broilers, 2010. 

[588]  LEI Wageningen, Competitiveness of the EU poultry meat sector, 2013. 

[589]  Netherlands, Quantitative information on livestock in the Netherlands, 2010. 

[590]  Batfarm,  'Reconciling  livestock  management  to  the  environment  -European  workshop, 

proceeding and minutes of the meeting', 2013. 

[591]  Denmark, DK Storage Natural Floating layer, 2009. 

[592]  R.Burns, L.Moody, 'A review of permeable cover options for manure storage', 2007. 

[593]  UBA  Germany, 

'Reduction  of  emissions  from  the  storage  of  slurry',  Personal 

Communication, 2013. 

[594]  Agro Business Park, Manure processing technologies, 2011. 

[595]  Agro Business Park, Inventory of manure processing activities in Europe, 2011. 

[596]  Denmark, Separation of slurry with decanter centrifuge, 2009. 

[597]  Loyon  et  al.,  'Gaseous  emissions  (NH3,  N2O,  CH4  and  CO2)  from  aerobic  treatment  of 

piggery slurry - Comparison with conventional storage system', 2007. 

[598]  Denmark, Slurry acidification during field spreading, 2012. 

[599]  Denmark, Slurry acidification in storage tank, 2012. 

[600]  P.Kai et al., 'A whole farm assessment of the efficacy of slurry acidification in reducing 

ammonia emissions', 2008. 

[601]  ALTERRA-IIASA, Emissions from agriculture and their control potentials, 2012. 

[602]  Denmark, Application with trailing hoses, 2010. 

[603]  Denmark, Application of slurry with injection system - winter crop, 2009. 

[604]  Denmark, Application of slurry with injection system - bare soil, 2009. 

[605]  E.Magowan, AFBI, Review of peer reviewed publications comparing ammonia emissions 

from deep and shallow pits under fully slatted floors in pig housing, 2010. 

[606]  Z.Ye et al., 'Key factors driving ammonia emissions from a pig house', 2011. 

[607]  COM, Assessment and Summary of the Member States' Implementation Reports for the 

IED, IPPC Directive, SED and WID, 2016. 

[608]  Netherlands, Manure collection in water, 2010. 

[609]  UR  Wageningen,  Kempfarm  housing  system  for  growing-finishing  pigs:  environmental 

emissions and investment costs, 2007. 

854 

Intensive Rearing of Poultry or Pigs 

References 

[610]  Fefana, 'Calculator excretion ex animal', Personal Communication, 2012. 

[611]  C.Rigolot  et  al.,  'Modelling  of  manure  production  by  pigs  and  NH3,  N2O  and  CH4 
emissions. Part I: animal excretion and enteric CH4, effect of feeding and performance', 
2010. 

[612]  TWG  comments,  Comment  received  by  TWG  members  on  the  proposals  for  reference 

systems, 2012. 

[613]  UR  Wageningen,  Standardised  calculation  methods  for  animal  manure  and  nutrients, 

2012. 

[614]  UK, Inventory of ammonia emissions from UK Agriculture. 2012, 2013. 

[615]  IE EPA, 'Emission factors used in national inventories', Personal Communication, 2012. 

[616]  Spain, 'Comment on the proposal for reference systems', Personal Communication, 2012. 

[617]  ITAVI, 'Calculation files for poultry', Personal Communication, 2012. 

[618]  DAFC, DK, 'Reference emission factors', Personal Communication, 2013. 

[619]  Baltic Sea 2020, Proposal for revision of Chapter 6 of the BREF, 2011. 

[620]  Germany,  Combined  above  floor_underfloor  ventilation  system  with  partial  airflow 

treatment, 2013. 

[621]  Alitalo et al, 'A new system exploiting soil microbes for aerobic biological treatment of 

swine manure: Theory and preliminary experiment', 2011. 

[622]  Alitalo  et  al,  'Combined  microbiological  processing  and  ammonia  stripping  of  liquid 

manure', 2011. 

[623]  Germany, Near_Zero_Emission_Stall pig housing system, 2013. 

[624]  IRPP  TWG,  Comments  submitted  for  the  Draft  2  of  the  revised  Intensive  Rearing  of 
Poultry and Pigs (IRPP) Best Available Techniques (BAT) Reference Document (BREF), 
2013. 

[625]  BE  Flanders,  BelgiumFlanders_update  regressions  used  in  Flanders  (Belgium)  to 

calculate level of excretion, 2013. 

[626]  Denmark, DK_aircleaner_biological_appendix, 2010. 

[627]  EEA,  EMEP/EEA  air  pollutant  emission  inventory  guidebook  2013.  Document  3.B 

Manure management, 2013. 

[628]  Veltholf,  'A  model  for  inventory  of  ammonia  emissions  from  agriculture  in  the 
Netherlands.  Atmospheric  Environment  46  (2012).  -  ISSN  1352-2310  -  p.  248  -  255', 
2012. 

[629]  Denmark, Whole farm environmental assessment - Tool from Denmark, 2013. 

[630]  VDI,  VDI  4285  Part  2:2011  Determination  of  diffusive  emissions  by  measurements  - 

Industrial halls and livestock farming, 2011. 

[631]  BE Flanders, Belgium Flanders_storage animal waste_Dutch version, 2013. 

[632]  DAFC, Effect of Fresta® F Plus on ammonia emissions from finisher facilities, 2010. 

[633]  ITAVI, Estimation des rejets d'azote - phosphore - potassium - calcium - cuivre - et zinc 

par les élevages avicoles. Mise à jour des références CORPEN-Volailles de 2006, 2013. 

[634]  BE Flanders, Belgium Flanders_odour emissions pig housing systems, 2013. 

[635]  Le Bouquin et al., 'Qualite de l’air et emissions gazeuses en fonction du type de logement 

des poules pondeuses', 2013. 

[636]  Ramiran,  Ramiran  Glossary:  Glossary  of  terms  on  livestock  and  manure  management. 

Second edition, 2011. 

Intensive Rearing of Poultry or Pigs 

855 

References 

[637]  BE  Flanders,  Ventilation  rates  (m³/h  per  animal)  recommended  in  Belgium  (Flanders), 

2012. 

[638]  BE Flanders, Updated Emission Factors from Belgium (Flanders ), 2014. 

[639]  IE EPA, Air pollutant emissions in Ireland 1990–2011 reported to the Secretariat of the 

UNECE Convention, 2014. 

[640]  Netherlands, Dutch national emission factors for ammonia in pigs and poultry, 2013. 

[641]  IRPP IWG, BREF Conclusions D2 Review January BE (Flanders), DE, ES, UK, NL and 

FR, 2014. 

[642]  BE Flanders, Belgium Flanders_emission levels housing fattening pigs, 2013. 

[643]  Van  Ransbeeck  et  al.,  'Indoor  concentrations  and  emission  factors  for  pig  fattening 

facilities', 2013. 

[644]  Netherlands, Emission factors for PM10 in the Netherlands, 2014. 

[645]  Denmark, 'New Standards for Odour Emissions from Pig Facilities in Denmark', 2005. 

[646]  COM,  Mission  report  for  the  visit  to  different  farms  performing  intensive  rearing  of 

poultry and pigs, European Commission, JRC IPTS EIPPCB, 2013. 

[647]  Rousset et al., 'Seeding of selected complexes of microorganisms on litters during rearing 

to reduce ammonia emissions in broiler house', 2012. 

[648]  DEFRA,  An  Inventory  of  Mitigation  Methods  and  Guide  to  their  Effects  on  Diffuse 
Water Pollution, Greenhouse Gas Emissions and Ammonia Emissions from Agriculture, 
2011. 

[649]  DAFC, Low-pressure oil ejecting system in a farrowing unit and a finisher unit, 1999. 

[650]  Denmark, DK_nutrition_Pig_phos, 2010. 

[651]  DAFC, Effect of benzoic acid addition in pig feed, 2010. 

[652]  DAFC, Effect of benzoic acid addition in pig feed_2, 2012. 

[653]  Denmark, Quantification of nitrogen and phosphorus in manure in the Danish normative 

system, 2014. 

[654]  BPEX,  Evaluation  of  phase  feeding  in  two  contrasting  finishing  systems  (fully  slatted 

versus straw based housing), 2004. 

[655]  Takai  et  al.,  'Concentrations  and  Emissions  of  Airborne  Dust  in  Livestock  Buildings  in 

Northern Europe', 1998. 

[656]  Ponchant et al., 'Estimation of levels of nitrogen volatilization in poultry barns from field 

measurements', 2012. 

[657]  Bailey T., Deep injection paper UK, 2012. 

[658]  Baltic  Manure,  Baltic  Manure.  Energy  Potential  of  Manure  in  the  Baltic  Sea  Region., 

2013. 

[659]  IPCC, 

'IPCC  Guidelines.  Chapter  10:  Emissions  from  Livestock  and  Manure 

Management', 2006. 

[660]  France, French proposition concerning poultry housing- chapter 3, 2010. 

[661]  Denmark, Economic assessment of techniques for the whole-farm - Tool from Denmark, 

2013. 

[662]  Philippe et al., 'Gaseous emissions during the fattening of pigs kept either on fully slatted 

floor or on straw flow. Animal, 2007, 1, 1515 - 1523', 2007. 

[663]  Simongiovanni  et  al.,  'Estimation  of  the  tryptophan  requirement  in  piglets  by  meta-

analysis', 2012. 

856 

Intensive Rearing of Poultry or Pigs 

References 

[664]  EFSA, Opinion of the Scientific Panel on Additives and Products or Substances used in 
Animal  Feed  on the  safety  and efficacy  of VevoVitall® (benzoic  acid) as feed additive 
for pigs for fattening, 2007. 

[665]  Riis,  Test  Farm  Airclean.  3-filter  bioscrubber  tested  with  VERA  protokol.  Danish  Pig 

Research Centre, 2012. 

[666]  BE  Flanders,  Excretion levels  from  the  Action  programme  nitrates  directive  2011-2014 

Flanders (region of Belgium), 2011. 

[667]  Spain, Ammonia emission factors from Spanish PRTR, 2011. 

[668]  IE EPA, Odour Impacts and Odour Emission Control Measures for Intensive Agriculture, 

2001. 

[669]  Italy, Proposal for modifying the Table 3.26 (Average annual consumption per type of pig 

farm and by type of energy source and operation), 2013. 

[670]  Kiwan  et  al.,  'Tracer  gas  technique,  air  velocity  measurement  and  natural  ventilation 

method for estimating ventilation rates through naturally ventilated barns', 2012. 

[671]  Krause et al., 'How to describe animal welfare in stable design? In: Briese A, Clauß M, 
Hartung  J,  Springorum  A  C  (eds)  Proceedings  of  the  14th  ISAH  Congress;  Vechta, 
Germany; Vol. 1. Brno: Tribun EU, pp 529-532', 2009. 

[672]  Faz A., Pig slurry treatment using constructed wetlands, 2015. 

[673]  DG AGRI, Agriculture in the European Union. Markets statistical information, 2014. 

[678]  NSW  DPI,  'Basic  husbandry  -  the  boar.  Primefact  69,  ISSN  1832-6668,  Job  number 

6154', 2006. 

[697]  EEA,  European  Union  emission  inventory  report  1990–2014  under  the  UNECE 

Convention on Long-range Transboundary Air Pollution (LRTAP), 2016. 

[698]  DG AGRI, EU Market Situation for Eggs, 2014. 

[699]  Eurostat, Pig population - annual data, 2017. 

[700]  EC,  'DIRECTIVE  (EU)  2016/2284  OF  THE  EUROPEAN  PARLIAMENT  AND  OF 
THE COUNCIL of 14 December 2016 on the reduction of national emissions of certain 
atmospheric  pollutants,  amending  Directive  2003/35/EC  and  repealing  Directive 
2001/81/EC', 2016. 

[701]  COM, A policy framework for climate and energy in the period from 2020 to 2030, 2014. 

[702]  Whalen  et  al.,  'Soil  food  web  controls  on  nitrogen  mineralization  are  influenced  by 

agricultural practices in humid temperate climates', 2013. 

[703]  COM,  Best  Available  Techniques  (BAT)  Reference  Document  for  Energy  Efficiency 

(ENE BREF), European Commission, JRC IPTS EIPPCB, 2009. 

[704]  MAFF, Code of Good Agricultural Practice for the Protection of Water, 1998. 

[705]  COM,  First  Draft  of  Best Available Techniques (BAT)  Reference  Document for  Waste 

Incineration (WI BREF), 2017. 

[706]  EEA, 

Ammonia 

(NH3) 

emissions. 

http://www.eea.europa.eu/data-and-

maps/indicators/eea-32-ammonia-nh3-emissions-1/assessment-4, 2017. 

[707]  Alterra, Integrated measures in agriculture to reduce ammonia emissions; final summary 

report, 2007. 

[708]  EC,  'REGULATION  (EU)  2016/429  OF  THE  EUROPEAN  PARLIAMENT  AND  OF 
THE  COUNCIL  of  9  March  2016  on  transmissible  animal  diseases  and  amending  and 
repealing certain acts in the area of animal health (‘Animal Health Law’)', 2016. 

[709]  The 

Poultry 

Site, 

Lighting 

for 

poultry 

housing. 

http://www.thepoultrysite.com/articles/452/lighting-for-poultry-housing/, 2017. 

Intensive Rearing of Poultry or Pigs 

857 

858

Intensive Rearing of Poultry or Pigs 

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