M.M. Mekonnen

The green, blue and grey

A.Y. Hoekstra

water footprint of farm

December 2010

animals and animal products

Volume 1: Main Report

Value of Water

Research Report Series No. 48

THE GREEN, BLUE AND GREY WATER FOOTPRINT
OF FARM ANIMALS AND ANIMAL PRODUCTS

VOLUME 1: MAIN REPORT
M.M. MEKONNEN1
A.Y. HOEKSTRA1,2
DECEMBER 2010

VALUE OF WATER RESEARCH REPORT SERIES NO. 48

1

Twente Water Centre, University of Twente, Enschede, The Netherlands
2

Contact author: Arjen Hoekstra, a.y.hoekstra@utwente.nl© 2010 M.M. Mekonnen and A.Y. Hoekstra.

Published by:
UNESCO-IHE Institute for Water Education
P.O. Box 3015
2601 DA Delft
The Netherlands

The Value of Water Research Report Series is published by UNESCO-IHE Institute for Water Education, in
collaboration with University of Twente, Enschede, and Delft University of Technology, Delft.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the priorpermission of the authors. Printing the electronic version for personal use is allowed.

Please cite this publication as follows:
Mekonnen, M.M. and Hoekstra, A.Y. (2010) The green, blue and grey water footprint of farm animals andanimal products, Value of Water Research Report Series No. 48, UNESCO-IHE, Delft, the Netherlands.

Contents
Summary .................................................................................................................................................................. 5
1. Introduction ........................................................................................................................................................ 7
2. Method and data ................................................................................................................................................. 9
2.1 Method ....................................................................................................................................................... 9
2.2 Data .......................................................................................................................................................... 14
3. Results .............................................................................................................................................................. 19
3.1 Quantity and composition of animal feed ................................................................................................ 19
3.2 The water footprint of animal feed ........................................................................................................... 21
3.3 The water footprint of live animals at the end of their lifetime and animal products per ton .................. 21
3.4 Water footprint of animal versus crop products per unit of nutritional value .......................................... 28
3.5 The total water footprint of animal production ........................................................................................ 29
4. Discussion ........................................................................................................................................................ 35
5. Conclusion ........................................................................................................................................................ 39
References .............................................................................................................................................................. 41

Summary
The projected increase in the production and consumption of animal products is likely to put further pressure on
the globe’s freshwater resources. The size and characteristics of the water footprint vary across animal types andproduction systems. The current study provides a comprehensive account of the global green, blue and grey
water footprints of different sorts of farm animals and animal products, distinguishing between different
production systems and considering the conditions in all countries of the world separately. The following animal
categories were considered: beef cattle, dairy cattle, pig, sheep, goat, broiler chicken, layer chicken and horses.
The study shows that the water footprint of meat from beef cattle (15400 m3/ton as a global average) is muchlarger than the footprints of meat from sheep (10400 m3/ton), pig (6000 m3/ton), goat (5500 m3/ton) or chicken(4300 m3/ton). The global average water footprint of chicken egg is 3300 m3/ton, while the water footprint ofcow milk amounts to 1000 m3/ton. Per ton of product, animal products generally have a larger water footprint
than crop products. The same is true when we look at the water footprint per calorie. The average water footprint
per calorie for beef is twenty times larger than for cereals and starchy roots. When we look at the waterrequirements for protein, we find that the water footprint per gram of protein for milk, eggs and chicken meat isabout 1.5 times larger than for pulses. For beef, the water footprint per gram of protein is 6 times larger than forpulses. In the case of fat, we find that butter has a relatively small water footprint per gram of fat, even lower
than for oil crops. All other animal products, however, have larger water footprints per gram of fat whencompared to oil crops. The study shows that from a freshwater resource perspective, it is more efficient to obtaincalories, protein and fat through crop products than animal products.
Global animal production requires about 2422 Gm3 of water per year (87.2% green, 6.2% blue, 6.6% grey
water). One third of this volume is for the beef cattle sector; another 19% for the dairy cattle sector. Most of thetotal volume of water (98%) refers to the water footprint of the feed for the animals. Drinking water for the
animals, service water and feed mixing water account only for 1.1%, 0.8% and 0.03%, respectively.

The water footprints of animal products can be understood from three main factors: feed conversion efficiency of
the animal, feed composition, and origin of the feed. The type of production system (grazing, mixed, industrial)
is important because it influences all three factors. A first explanatory factor in the water footprints of animal
products is the feed conversion efficiency. The more feed is required per unit of animal product, the more wateris necessary (to produce the feed). The unfavourable feed conversion efficiency for beef cattle is largely
responsible for the relatively large water footprint of beef. Sheep and goats have an unfavourable feed
conversion efficiency as well, although better than cattle. A second factor is the feed composition, in particular
the ratio of concentrates versus roughages and the percentage of valuable crop components versus crop residues
in the concentrate. Chicken and pig have relatively large fractions of cereals and oil meal in their feed, which
results in relatively large water footprints of their feed and abolishes the effect of the favourable feed conversion
efficiencies. A third factor that influences the water footprint of an animal product is the origin of the feed. The
water footprint of a specific animal product varies across countries due to differences in climate and agricultural
practice in the regions from where the various feed components are obtained. Since sometimes a relatively large

6 / The water footprint of farm animals and animal products

fraction of the feed is imported while at other times feed is mostly obtained locally, not only the size but also thespatial dimension of the water footprint depends on the sourcing of the feed.

It is relevant to consider from which type of production system an animal product is obtained: from a grazing,
mixed or industrial system. Animal products from industrial production systems generally have a smaller total
water footprint per unit of product than products from grazing systems, with an exception for dairy products(where there is little difference). However, products from industrial systems always have a larger blue and grey
water footprint per ton of product when compared to grazing systems, this time with an exception for chicken
products. It is the lower green water footprint in industrial systems that explains the smaller total footprint. Given
the fact that freshwater problems generally relate to blue water scarcity and water pollution and to a lesser extent
to competition over green water, this means that grazing systems are preferable over industrial production
systems from a water resources point of view. In the case of cattle, pigs, sheep and goats, the total water
footprints per ton of product are larger for grazing systems because of the worse feed conversion efficiencies, but
the fact that these systems depend more strongly on roughages (which are less irrigated and less fertilised than
the feed crops contained in concentrate feed) makes that the blue and grey water footprints of products fromgrazing systems are smaller. This compensation through the feed composition does not occur for the case ofchicken. The reason is that chicken strongly rely on concentrate feed in all production systems. Mixed production
systems generally take a position in between industrial and grazing systems. Not accounted for in this study isthat industrialized animal production often produces large amounts of animal waste that cannot be fully recycled
in the nearby land. Such large amounts of waste produced in a concentrated place are known to pollute
freshwater resources if not handled properly.

By focusing on freshwater appropriation, the study obviously excludes many other relevant issues in farm animal
production, such as micro- and macro-cost of production, livelihood of smallholder farmers, animal welfare,public health and environmental issues other than freshwater.

1. Introduction
In the last few decades the world has seen a significant shift in food consumption patterns towards more animal
products such as meat, milk and egg, mainly due to growing economies and rising individual incomes. In
developing countries, in particular, consumption of meat, milk and dairy products has been growing the last few
decades at 5-6 percent and 3.4-3.8 percent annually respectively (Bruinsma, 2003). The shift in consumption
patterns coupled with high population growth and rapid urbanization in most developing countries is driving thetotal demand for animal products upward.

The global meat production has nearly doubled between 1980 and 2004, with the largest share of growth indeveloping countries (FAO, 2005). Related to the increased production there is a shift away from grazing
systems. Although the traditional pastoral system plays a role, most of the increase in meat and milk productionin the last three decades was achieved through production increase in the mixed and industrial production
systems (Bouwman et al., 2005). The shift to more intensive production systems influences the composition ofanimal feed. Traditionally, animals have relied on locally available feed, such as grass, crop residues and wastes
from human food. The more intensive production systems depend on concentrate feeds that are traded locallyand internationally. In many countries, there is a tendency towards decreasing reliance on grazing and increasing
dependence on concentrate feeds. Intensive animal production systems, in which animals are raised inconfinement, currently account for 74 percent of the world’s total poultry production, 40 percent of pig meat andmore than two-thirds of egg production (Seré and Steinfeld, 1996). If this trend continues in the future, its
implication will be far-reaching for both land and water resources requirements.

Animal production requires large volumes of water for feed production, drinking water and servicing animals.
By far the largest water demand in animal production is the water needed to produce animal feed. Because of
the increasing demand for animal products and the growing sector of industrial farming, the demand forfeedstuffs grows as well, including cereals, starchy roots, fodder crops, oilseeds and oil meals. Such highdemand for feed in turn causes a rising demand for water. Besides, intensification of animal production systems
will lead to surface and ground water pollution, both from the use of fertilizers in feed crops production andimproper storage and application of manures.

The global meat trade is projected to rise by more than 50 percent over the next 25 years (Bruinsma, 2003). Alsointernational trade in feed is growing. As a result of the increasing global trade in feed crops and animal
products and the growth of meat preservation over longer periods, many consumers have no longer any idea
about the natural resource use and environmental impacts associated with the products they consume.
Consumers of animal products are spatially disconnected from the processes necessary to produce the products(Naylor et al., 2005; Hoekstra, 2010). The concept of ‘water footprint’ provides an appropriate framework ofanalysis to find the link between the consumption of animal products and the use of the global water resources.
The water footprint is defined as the total volume of freshwater that is used to produce the goods and services
consumed by an individual or community (Hoekstra and Chapagain, 2008).

8 / The water footprint of farm animals and animal products

There are a few earlier publications on water use in animal production. The first and most comprehensive
assessment of the water footprint of farm animals and animal products was carried out by Chapagain and
Hoekstra (2003) and later updated by the same authors in their water footprint of nation’s publication(Chapagain and Hoekstra, 2004). A study by FAO has quantified the global blue water use for feed production,
animal drinking and servicing (Steinfeld et al., 2006). De Fraiture et al. (2007) have estimated the global water
use for animal feed production, both green and blue but not distinguishing between the two. They consideredwater use for two lumped categories: feed crops and grazing. Zimmer and Renault (2003) made a roughestimation of the global water consumption for producing meat and other animal products, not showing details
per country, animal category or product. Galloway et al. (2007) produced a study on the water consumption forchicken and pig for four countries: the USA, Japan, Brazil and the Netherlands. Peden et al. (2007) made anestimate of the global water consumption for producing the feed for farm animals. In addition to the studies
mentioned there have been a few more specific studies for the Nile River Basin (Van Breugel et al., 2010) andfor the USA (Renault and Wallender, 2000; Pimentel et al., 2004).

With the exception of Chapagain and Hoekstra (2003, 2004), none of the studies have estimated the water
footprint of animal products by product and country at a global level. Although Chapagain and Hoekstra (2003,
2004) were able to estimate the water footprint of farm animals and animal products per country, they havetaken a very crude assumption on the composition and amount of feed consumed by the different animals.
Besides, the water footprints of feed crops were estimated based on national average climatic data. We have
tried to improve the estimation of feed composition and feed amount per animal category and have used better
estimates for the water footprints of feed crops.

The objective of the study is to assess the water footprint of farm animals and the various derived animal
products for the period 1996-2005. We consider eight animal categories: beef and dairy cattle, pig, sheep, goat,broiler and layer chicken and horses. The main differences with Chapagain and Hoekstra (2003, 2004) are:

We have estimated the amount of feed consumed per animal category, per production system and per
country based on estimates of feed conversion efficiencies and statistics on the annual production of animal
products. Chapagain and Hoekstra (2003, 2004) have taken rough assumptions on the quantities of feed
consumed per animal category based on incidental data.

We reckon with the relative occurrence of the three production systems (grazing, mixed and industrial) in
each country, using the studies of Seré and Steinfeld (1996) and Wint and Robinson (2007). In Chapagain
and Hoekstra (2003, 2004), for each country the dominant animal production system was selected, after
which further calculations for this country were based on data for that specific production system.



We have estimated the green, blue and grey water footprints of the feed crops using a spatially explicit cropwater use model able to estimate actual crop water use (Mekonnen and Hoekstra, 2010a, 2010b). In theprevious studies the potential rather than the actual crop water use was used. In addition, the estimate wasbased on country average climatic data which could lead to errors in large countries. Furthermore the earlier
studies did not explicitly distinguish between the green and blue water footprint components and did notinclude the grey water footprint component at all.

2. Method and data
2.1

MethodWe follow the water footprint definitions and methodology as set out in Hoekstra et al. (2009). The blue water
footprint refers to consumption of blue water resources (surface and groundwater) along the supply chain of a
product. ‘Consumption’ refers to loss of water from the available ground-surface water body in a catchment area.
Losses occur when water evaporates, returns to another catchment area or the sea or is incorporated into a
product. The green water footprint refers to consumption of green water resources (rainwater in so far as it does
not become run-off). The grey water footprint refers to pollution and is defined as the volume of freshwater thatis required to assimilate the load of pollutants given natural background concentrations and existing ambient
water quality standards.

We consider eight farm animal categories: beef and dairy cattle, pig, sheep, goat, broiler and layer chicken andhorses. When estimating total feed amounts and total water footprints per category, we include ‘buffaloes’ in the
category of ‘beef cattle’ and ‘asses and mules’ in the category of ‘horses’.

The water footprint of a live animal consists of different components: the indirect water footprint of the feed andthe direct water footprint related to the drinking water and service water consumed (Chapagain and Hoekstra,
2003, 2004). The water footprint of an animal is expressed as:WF [a, c, s ]  WF feed [a, c, s ]  WFdrink [a, c, s ]  WFserv [a, c, s ](1)where WFfeed[a,c,s], WFdrink[a,c,s] and WFserv[a,c,s] represent the water footprint of an animal for animal
category a in country c in production systems s related to feed, drinking water and service water consumption,
respectively. Service water refers to the water used to clean the farmyard, wash the animal and carry out otherservices necessary to maintain the environment. The water footprint of an animal and its three components canbe expressed in terms of m3/yr/animal, or, when summed over the lifetime of the animal, in terms of m3/animal.
For beef cattle, pig, sheep, goat and broiler chicken – animals that provide their products after they have beenslaughtered – it is most useful to look at the water footprint of the animal at the end of its lifetime, because it is
this total that will be allocated to the various products (e.g. meat, leather). For dairy cattle and layer chicken, it ismost straightforward to look at the water footprint of the animal per year (averaged over its lifetime), because
one can easily relate this annual animal water footprint to its average annual production (milk, eggs).

The water footprint of an animal related to the feed consumed consists of two parts: the water footprint of thevarious feed ingredients and the water that is used to mix the feed: Feed[a, c, s, p]  WFn

WF feed [a, c, s ] prod [ p ]  WFmixing [ a, c, s ]p 1

Pop [a, c, s ](2)

10 / The water footprint of farm animals and animal products

Feed[a,c,s,p] represents the annual amount of feed ingredient p consumed by animal category a in country c and
production system s (ton/yr), WFprod[ p ] the water footprint of feed ingredient p (m3/ton), WFmixing[a,c,s] thevolume of water consumed for mixing the feed for animal category a in country c and production system s(m3/yr/animal) and Pop*[a,c,s] the number of slaughtered animals per year or the number of milk or egg
producing animals in a year for animal category a in country c and production system s.

The water footprint of feed ingredients
The water footprints of the different crops, roughages and crop by-products ( WFprod[ p] , m3/ton) that are eatenby the various farm animals have been calculated following the methodology developed by Hoekstra andChapagain (2008) and Hoekstra et al. (2009). The water footprints of feed crops were estimated using a cropwater use model that estimates crop water footprints at a 5 by 5 arc minute spatial resolution globally (Mekonnen
and Hoekstra, 2010a, 2010b). Grey water footprints were estimated by looking at leaching and runoff of nitrogen
fertilisers only, following Mekonnen and Hoekstra (2010a,b). Since animal feed in a country originates fromdomestic production and imported products, for the calculation of the water footprint of animal feed in a country,
we have taken a weighted average water footprint according to the relative volumes of domestic production andimport: T [n ,p]  WF
P[ p ]   T [n ,p]P[ p]  WFprod [ p] WFprod[ p] 

ie

prod [ ne ,p ]

ne

i

(3)

e

ne

in which P[p] is the production quantity of feed product p in a country (ton/yr), Ti[ne,p] the imported quantity of
feed product p from exporting nation ne (ton/yr), WFprod[p] the water footprint of feed product p when producedin the nation considered (m3/ton) and WFprod[ne,p] the water footprint of feed product p as in the exporting nationne (m3/ton). The water footprint of crop residues such as bran, straw, chaff and leaves and tops from sugar beet
have already been accounted for in the main product, therefore their water footprint was set equal to zero.

Volume and composition of feed
The volume and composition of the feed consumed vary depending on the type of animal, the production systemand the country. The amount of feed consumed is estimated following the approach of Hendy et al. (1995), in
which the total annual feed consumption (including both concentrates and roughages) is calculated based on
annual production of animal products and feed conversion efficiencies. Only for horses we have used theapproach as in Chapagain and Hoekstra (2003), which means that we multiplied the estimated feed consumption
per animal by the number of animals, thus arriving at an estimate of the total feed consumed by horses.

The steps followed to calculate the volumes and composition of feed are schematically shown in Figure 1. The
total feed per production system for both ruminants and non-ruminants animals is calculated as follows:
Feed [a, c, s ]  FCE[a, c, s ]  P[a, c, s ](4)The water footprint of farm animals and animal products / 11

where Feed[a,c,s] is the total amount of feed consumed by animal category a (ton/yr) in country c andproduction system s, FCE[a,c,s] the feed conversion efficiency (kg dry mass of feed / kg of product) for animal
category a in country c and production system s, and P[a,c,s] the total amount of product (meat, milk, or egg)
produced by animal category a (ton/yr) in country c and production system s.

For ruminants

Animal live weight
LW[a,c,s]

Daily feed intake
rate
FIR[a,c,s]

Per capita annual
feed intake FI[a,c,s]

Annual animal
products output
P[a,c,s]Total animal
population
Pop[a,c,s]

Per capita products
output PO[a,c,s]

Directly available for
non-ruminants

Average feed
conversion efficiency
FCE[a,c,s]

Annual animal
products output
P[a,c,s]Total feed
Feed[a,c,s]

Roughage feed
Roughage[a,c,s]

Concentrate feed
Concentrate[a,c,s]

Share ofconcentrate out of
total feed fc[a,c,s]

Concentrate feed
per crop
Concentrate[a,c,s,p]Concentrate composition in termsof major categories per animal
according to Wheeler et al. (1981)

FAOSTAT Concentrate
feed per crop per country
Concentrate[p,c]Figure 1. Steps in the calculation of feed amount per animal. For ruminants (beef cattle, dairy cattle, sheep andgoat), feed conversion efficiencies are derived as indicated in the upper part of the scheme. For non-ruminants(pig, broiler and layer chicken), the feed conversion efficiencies are directly taken from the literature.

Estimating feed conversion efficiencies
Feed conversion efficiency is defined as the amount of feed consumed per unit of produced animal product (e.g.
meat, milk, egg). Feed conversion efficiencies were estimated separately for each animal category (beef cattle,
dairy cattle, sheep, goat, pig, broiler chicken and egg layer chicken), for each animal production system and per
country. Although the term used may suggest precisely the opposite, animals that have a low ‘feed conversion
efficiency’ are efficient users of feed. We use the term here as generally used in livestock studies. The feed
conversion efficiencies (FCE, kg dry mass/kg product) for non-ruminants (pig and chicken) were adopted from
Hendy et al. (1995). For ruminants (cattle, goat, sheep), feed conversion efficiencies were estimated throughdividing feed intake per capita by annual production (of beef, milk, sheep and goat meat) per capita:

12 / The water footprint of farm animals and animal products

FCE[a, c, s ] FI [a, c, s ]PO[a, c, s ](5)where FI[a,c,s] is the feed intake per head by ruminant animal category a in country c and production system s(kg dry mass/yr/animal), and PO[a,c,s] the product output per head for ruminant animal category a in country cand production system s (kg product/yr/animal). The product output (beef, milk, sheep and goat meat) per animal
for ruminants is calculated as:

PO[a, c, s ] 

P[a, c, s ]Pop[a, c, s ](6)in which P[a,c,s] is the total annual production of beef, milk, sheep meat or goat meat in country c in production
system s (kg/yr) and Pop[a,c,s] the total population of beef cattle, dairy cattle, sheep or goat in that country andproduction system.

Estimating the total annual production of animal products
The annual production of animal products has been estimated as shown in Figure 2. The meat production (Pmeat,
ton/yr) per animal category a (beef cattle, pig, sheep and goat) in country c and production system s is estimatedby multiplying the carcass yield per slaughtered animal by the annual number of animals slaughtered:Pmeat [a, c, s ]  CY [a, c, s ]  SA[a, c, s ](7)

The carcass yield (CY, kg/animal) for each animal category per production system was estimated by combining
country average carcass yield data from FAO (2009) with data on animal live weight per production system pereconomic region (Hendy et al. 1995) and data on carcass weight as percentage of live weight (FAO, 2003). The
obtained carcass yields were scaled such that the total meat production per animal category equals the value
provided by FAO (2009). The number of slaughtered animals per production system (SA, number of animal/yr)
was calculated by multiplying the total animal number by the animal off-take rate per production system:
SA[a, c, s ]  Pop[a, c, s ]  OR[a, c, s ](8)where Pop[a,c,s] is the population of animal category a in country c for production system s and OR[a,c,s] theoff-take rate, which is the fraction of the animal population that is taken out in a given year for slaughter(dimensionless).

Milk and egg production per production system and country were calculated as:
Pmilk [a, c, s ]  MY [a, c, s ]  DC[a, c, s ](9)Pegg [a, c, s ]  f egg [a, c, s ]  Pegg [a, c](10)The water footprint of farm animals and animal products / 13

where Pmilk[a,c,s] and Pegg[a,c,s] represent production of milk and egg in country c and production system s
respectively (ton/yr), MY[a,c,s] milk yield per dairy cow in country c and production system s (ton/dairy cow),
DC[a,c,s] the number of dairy cows in country c and production system s, fegg[a,c,s] the fraction of egg producedin country c and production system s and Pegg[a,c] the total amount of egg produced in country c (ton/yr).
Fraction of animal per
country per production
systemfa[a,c,s]

Carcass weight aspercent of live weight per
country fcw[a,c]Animal per country
Pop[a,c]Animal per country per
production system
Pop[a,c,s]

Animal off-take rate
per country
OR[a,c]Animal off-take rate percountry per production
system
OR[a,c,s]

Carcass yield per
country per production
system CY[a,c,s]

Carcass yield per country
CY[a,c]Number ofslaughtered animal
per country SA[a,c]Number of slaughteredanimals per country per
production system
SA[a,c,s]Meat production per
production system per
country Pmeat[a,c,s]National average meatproduction per country
Pmeat[a,c]Animal live weight per
country per production
system LW[a,c,s](a) Meat production per production system and per country
Milk yield per
production
system MY[a,s]Fraction of milk
produced per
production
system fmilk[a,s]Milk yield per
country MY[a,c]Dairy cow number
per country
Popdiary[a,c]Milk yield per
country per
production system
MY[a,c,s]

Dairy cow number
per country persystemPopdiary[a,c,s]

Milk production
per country
Pmilk[a,c]Milk production per
country per
production system
Pmilk[a,c,s](b) Milk production and yield per country per production system

Egg production
per country
Pegg[a,c]

Fraction of egg
produced persystem fegg[a,s]Egg production
per country persystemPegg[a,c,s](c) Egg production per country and per production system

Figure 2. Steps in the calculation of: (a) annual meat production (beef cattle, pig, sheep, goat, broiler chicken); (b)annual milk production (dairy cattle); and (c) annual egg production (layer chicken). Broken arrows indicate
iteration and adjustment to fit to values of FAO (2009).

Estimating the feed composition
Animal feeds are generally divided into ‘concentrates’ and ‘roughages’ (Box 2.1). The volume of concentrate
feed has been estimated per animal category and per production system as:
Concentrate[a, c, s ]  Feed[a, c, s ]  f c [a, c, s ](11)where Concentrate[a,c,s] is the volume of concentrate feed consumed by animal category a in country c andproduction system s (ton/yr) and fc[a,c,s] the fraction of concentrate in the total feed for animal category a incountry c and production system s. For the latter variable, data have been obtained from Hendy et al. (1995) andBouwman et al. (2005).

14 / The water footprint of farm animals and animal products

The composition of concentrate feeds varies across animal species and regions of the world. To our knowledge,
there are no datasets with global coverage on the composition of feed for the different animals per country.
Therefore, we have made a number of assumptions concerning the concentrate feed composition of the different
animal species. According to Hendy et al. (1995), the diets of pig and poultry include, on average, 50-60%
cereals, 10-20% oil meals and 15-25% ‘other concentrates’ (grain substitutes, milling by-products, nonconventional concentrates). Wheeler et al. (1981) provide the feed composition in terms of major crop categories
for the different animal categories (Figure 3 and Figure 4). We have used these and other sources in combination
with FAOSTAT country average concentrate feed values for the period 1996-2003 (FAO, 2009) to estimate thediet composition of the different animal species. In order to estimate the feed in terms of specific crops per
animal, we first estimated the feed in terms of major crop categories following Wheeler et al. (1981). The feed interms of major crop categories is further distributed to each crop proportional to the crop’s share in its crops
category as obtained from FAOSTAT (FAO, 2009). The roughage feed is divided into fodder, grass and crop
residues using the data obtained from Bouwman et al. (2005).
Box 2.1 Definition of feed components. Source: Hendy et al. (1995) and FAO(1983).
Feeds are generally divided into ‘concentrates’ and ‘roughages’.
Concentrates are feeds which contain a high level of nutrients for a given weight of feed usually low in crude fibre content (less than
18% of dry matter content) and high in total digestible nutrients. Thus concentrates may be high in energy, as in the case of cereals
and milling by-products or they may be high in protein, as are protein meals of either vegetable or animal origin. The concentrates
considered in this study include all the feed material found in FAO (2009) and which are derived from crops. The concentrate feeds
considered include cereals, roots and tubers, oil crops, oil meals, bran, molasses, pulses, sugar crops, fruits and vegetables.

Roughages are feeds with low density of nutrients, with a crude fibre content over 18% of dry matter, include most fresh and dried
forages and fodders. The main roughages are:o pastures: includes temporary and permanent pastures.
o harvested roughages: include those which are sown and harvested annually for forage, fodder or silage. The principal types of
harvest roughages include forage (green) cereals such as maize, oats and sweet sorghum; sugarcane, lucerne (alfalfa) and berseem(Egyptian clover); special high yielding grasses cultivated chiefly for silage (such as Thimoth grass); roots and tubers such as
potatoes, beets, swedes, turnips; oilseeds such as winter rape; pulses such as field peas, beans, sweet lupins and vetches;
vegetables such as pumpkins and cabbages. These feeds are sometimes processed for lower fibre content and bulk and are thenusually classified as concentrate feeds (e.g. cassava chips and pellets, processed alfalfa, pea and bean meals).
o other roughages: include a large variety of crop by-products such as straw and chaff from cereals and pulses; leaves and tops fromsugar beet; fodder beets and vegetables; and other miscellaneous roughages such as acacia and ipil ipil (leucaena) leaves.

2.2

Data

A large amount of data has been collected from different sources. A major data source for animal stocks,
numbers of animals slaughtered each year, annual production of animal products, and concentrate feed per
country is FAOSTAT (FAO, 2009). Other important sources that have been used are: Seré and Steinfeld (1996),
Hendy et al. (1995), Bouwman et al. (2005), Wint and Robinson (2007), Wheeler et al. (1981) and FAO (2003).
Box 2.2 summarizes how specific data have been obtained from these different sources.

The water footprint of farm animals and animal products / 15

Box 2.2. Overview of data sources.


Animal production systems: Seré and Steinfeld (1996) have developed a classification of animal production systems based on agroecology, the distinction between pastoral, mixed and landless systems and on the presence of irrigation or not. They distinguisheleven animal production systems grouped under three headings: grazing (extensive), mixed and industrial (intensive). In this study
we use the schematization into these three production systems.



Feed conversion efficiencies: For ruminants, the feed conversion efficiencies were estimated as explained in Section 2.1. For nonruminants (pig, broiler and egg laying chicken), feed conversion efficiencies per animal category, per production system and per
economic region were obtained from Hendy et al. (1995). For both ruminants and non-ruminants, the feed conversion efficiency data
were scaled such that at the level of world regions they match the efficiencies as reported in Bouwman et al. (2005).

Annual production of animal products: Data on the annual production of animal products (beef, pig meat, sheep meat, goat meat,chicken meat, milk and egg) per production system for different economic regions were obtained from Seré and Steinfeld (1996).
Production data per product and country for the period 1996-2005 were obtained from FAOSTAT (FAO, 2009). The two data
sources have been combined to derive production data per animal category, production system and per country for the period 19962005. We scaled the production data per production system such that at national level, the production aggregated over the different
production systems equals the production as reported in FAO (2009) for the period 1996-2005.



Number of animals: Seré and Steinfeld (1996) provide the total animal population for the different production systems for the year
1995 for a number of geographic regions in the world. Wint and Robinson (2007) provide the total animal population for the year
2005 for the different production systems for developing countries. We have combined the two sources to obtain number of animals
per animal category, per production system and per country. We scaled the numbers such that at national level, the number of animals
aggregated over the different production systems equal the numbers as reported in FAO (2009) for the period 1996-2005.



Number of slaughtered animals and animal off-take rates: The annual number of slaughtered animals for beef cattle, pig, sheep,goat and broiler chicken per country have been taken from FAO (2009). The animal off-take rates at national level have been derived
from the same source by dividing the annual number of slaughtered animals by the total population. The off-take rate for the grazing
system was assumed to be 90% of the national average off-take rate for the animal category considered (Bouwman, et al., 2005). Per
country, the off-take rate for the mixed and industrial production systems were scaled until the total number of slaughtered animals
per animal category equalled the value provided by FAO (2009).



Animal live weight: Hendy et al. (1995) provide live weight of ruminant animals (beef cattle, dairy cattle, sheep and goat) byproduction system and economic region. FAO (2003) give animal live weight for cattle, pig, sheep, goat and chicken. We combined
these two sources, taking advantage of the fact that Hendy et al. (1995) specify data per production system (but not per country) andFAO (2003) provides data per country (but not per system).

Carcass weight as percentage of live weight: FAO (2003) provides carcass weight as percentage of live weight for the different
animal categories per country.

Ruminant animals daily feed intake rate: Daily feed intake rate for ruminant animals (beef cattle, dairy cattle, sheep and goat) was
obtained from Hendy et al. (1995).



Share of concentrate feed in total animal feed: The contribution of concentrate feeds such as cereals, oil-meals, roots and othercrop products in the total feed composition was obtained from Hendy et al. (1995) and Bouwman et al. (2005).

Composition of the concentrate feed: The composition of concentrate feed per animal category was estimated following mainly
Wheeler et al. (1981) (Figure 3-4). In addition, we used Steinfeld et al. (2006) for data on the relative composition of poultry and pig
feed for major countries (Figure 5-6). The data available in Wheeler et al. (1981) and Steinfeld et al. (2006) are not sufficient tospecify the feed composition at the level of specific crops or crop products. In order to come to that level of detail we use the Supply
and Utilization Accounts of FAOSTAT (FAO, 2009), which provide the total concentrate feed utilization per country per crop andcrop product.

Composition of the roughage feed: We used Bouwman et al. (2005) to estimate the composition of the roughage feed (grass, fodder
crops, crop residues).

Water use for drinking and animal servicing: Data were obtained from Chapagain and Hoekstra (2003). See Appendix IV.

Water use for mixing feed: Following Chapagain and Hoekstra (2003), the water use for feed mixing is assumed to be 50% of total
concentrate feed intake (or 0.5 litre per kg of concentrate feed intake).

16 / The water footprint of farm animals and animal products

Average feed utilization (%)

80

60

40

20

0
Cereals

Oilmeals

Cattle and buffaloes

Other concentrates
Sheep and goats

Pigs

Roughages
Poultry

Total feed
Other

Figure 3. World average utilization of feeds by different animal species in metabolisable energy equivalents
Source: Wheeler et al. (1981).

Composition of diet (%)

100

80

60

40

20

0
Cattle andbuffaloes

Sheep and goats

Cereals

Oilmeals

Pigs

Poultry

Other concentrates

Roughages

OthersFigure 4. Aggregate world composition of diets for different species of animal in metabolisable energy equivalents
Source: Wheeler et al. (1981).

The water footprint of farm animals and animal products / 17100
90

Feed composition (%)

80
70
60
50
40
30
20
10
0

BarleyMaize

Sorghum

Wheat

Peas

Soybean Cake

Other oilmeals

Fish meal

OthersFigure 5. Relative composition of poultry feed basket in selected countries (by weight). Source: Steinfeld et al.
(2006).

100
90

Feed composition (%)

80
70
60
50
40
30
20
10
0

Barley

Maize

Rice

Rye

Sorghum

Wheat

Peas

Soybean Cake

Rapeseed Cake

Fish meal

OthersFigure 6. Relative composition of pig feed basket in selected countries (by weight). Source: Steinfeld et al. (2006).

3. Results
3.1

Quantity and composition of animal feed

Table 1 provides global average feed conversion efficiencies for different animal categories and production
systems. Region-specific feed conversion efficiencies are presented in Appendix I. Ruminants (cattle, sheep,goat) are less efficient in converting feed into meat than non-ruminants (pig, chicken), amongst other due to thelower quality of feed they consume. Particularly meat production from cattle costs a lot of feed per unit ofproduct obtained. Although ruminants need more feed, their feed largely consists of forage and other materials
that humans cannot eat, while non-ruminants consume large amounts of concentrate feed that could be used forhuman consumption. Non-ruminants thus most obviously compete with humans for food, but in an indirect way
ruminants also compete for food with humans. In some cases the roughages eaten by ruminants are producedwith land and water resources that cannot alternatively be allocated to crop production for human consumption(e.g. in the case of grazing in dry or wetlands), but often the land and water resources used for roughages supply
can alternatively be used for crop growth for human consumption, so that ruminants compete with humans forfood also through consumption of roughages.
Table 1. Global average feed conversion efficiency per animal category and production system.
Feed conversion efficiency (kg dry mass feed/kg output)
Animal category
Grazing

Mixed

Industrial

Overall

Beef cattle

70.1

51.8

19.2

46.9

Dairy cattle

3.5

1.6

1.1

1.9

Broiler chicken

9.0

4.9

2.8

4.2

Layer chicken

9.3

4.4

2.3

3.1

Pig

11.3

6.5

3.9

5.8

Sheep and goat

49.6

25.8

13.3

30.2

Non-ruminants are responsible for 60% of the global consumption of concentrate feeds; ruminants account for
40%. Figure 7 shows the consumption of different concentrates by different animal categories. Chickens take thelargest share in total concentrate feed consumption (30%). Three fifth of the concentrate feed consumption bychicken in the world is for broiler chicken and two fifth for layer chicken. Pig meat production takes nearly thesame share (29%) in global concentrate feed consumption, while dairy cattle are responsible for 25% and beef
cattle 14%. Our estimated shares of different animal categories in the total concentrate feed consumption is very
close to the estimates made by Hendy et al. (1995).

Annual concentrate feed consumption averaged over the period 1996-2005 expressed in commodity fresh weightamounted to 1195 million tons per year. This value is very close to the feed data provided by FAO (2009) for theperiod 1996-2003 (1229 million ton/yr). The feed data analysed and presented here focus on commodities
derived from crop production. Figure 8 presents a summary of the global total feed utilization of cereals, oilmeals and cakes, roots and tubers, bran and others. Cereals make up the largest percentage of the total
concentrate feed use (57%), followed by oil meals (15%), roots (11%) and brans (10%).

20 / The water footprint of farm animals and animal products

Consumption of different concentrates(Million ton/yr)

400
Others300

Oilmeals
Molases
Brans

200

Sugar crops
Roots

100

PulsesOil crops
Cereals0
Sheep &
goat

Layer
chickenBeef cattle

Broilerchicken

Dairy

Pig

Figure 7. Consumption of different concentrates per animal category.

Oil crops
1%
Cereals
57%

Pulses
1%

Roots
11%
Sugar crops
2%

Brans
10%

Molases
1%
Others2%

Oilmeals
15%

Figure 8. Contribution of different crops (on fresh weight basis) toward global total concentrate feed utilization.
Period 1996-2005.

The estimated global amount of feed consumption per animal category and world region is presented inAppendix II. Feed consumption per production system is shown in Appendix III. The total feed consumption
over the period 1996-2005 was 4996 million ton feed in dry matter per year, on average. Roughages account for
the largest share out of this total, accounting for 80%, and feeds derived from crop production account for theremaining 20%. Considering only plant-based feed materials, our global estimate of total feed in dry matter

The water footprint of farm animals and animal products / 21(4996 Mton dry mass/yr) is about 6% lower than the estimate of Wirsenius (2000) (5300 Mton dry mass/yr) and
8% more than the estimate of Bouwman et al. (2005) for 1995 (4637 Mton dry mass/yr). Our estimate of global
utilization of roughages (4010 Mton dry mass/yr), which includes pasture, forages, straws, sugar crops tops andleaves, oil crops stalks and husks is 15% lower than the estimate of Wirsenius (2000) (4740 Mton dry mass/yr)
and 5% larger than the estimate of Bouwman et al. (2005) for 1995 (3832 Mton dry mass/yr).

3.2

The water footprint of animal feed

The water footprint per ton of feed differs among crops and across countries. Since the most significant part of
the animal water footprint comes from the feed they consume, the water footprint per unit of feed is an importantfactor in the determination of the water footprint of animals and their associated derived products. Table 2 shows
the average water footprint of selected feed ingredients for selected countries. Crop residues and by-products
such as bran, straw, chaff and leaves and tops from sugar beet have a water footprint of about zero, because thewater footprint of crop growing is mainly attributed to the main crop products, not the low-value residues or byproducts. As a result they provide an opportunity to reduce the water footprint of animal production. Huge
reduction in the water footprint of animals can also be obtained by using crops with a relatively low water
footprint per ton such as sugar beet. Therefore, careful selection of feeds that meet the nutrient requirement of theanimals and at the same time have a smaller water footprint per ton could significantly reduce the indirect use of
freshwater resources associated with animal production.

3.3

The water footprint of live animals at the end of their lifetime and animal products per ton

Table 3 shows, for each animal category, the average water footprint of an animal at the end of its life time andthe annual water footprint of an animal. Dairy cows have the largest annual water footprint (2056 m3/yr/animal),which is more than the average human being. Broiler chicken have the smallest footprint (26 m3/yr/animal).

Table 4 presents the green, blue and grey water footprints of some selected animal products per production
system for selected countries. Appendix V presents the full result of our analysis: green, blue and grey water
footprints of all farm animals and animal products considered, per production system and per country. The water
footprints of animals and animal products vary greatly across countries and production systems. When we look at
global averages, however, we see that the water footprint of meat increases from chicken meat (4300 m3/ton),goat meat (5500 m3/ton), pig meat (6000 m3/ton), sheep meat (10400 m3/ton) to beef (15400 m3/ton). The
differences can be partly explained from the different feed conversion efficiencies of the animals. Beef
production, for example, requires eight times more feed (in dry matter) per kilogram of meat compared to
producing pig meat, and eleven times if compared to the case of chicken meat. This is not the only factor,
however, that can explain the differences. Another important factor is the feed composition. Particularly thefraction of concentrate feed in the total feed is important, because concentrate feed generally has a larger water
footprint than roughages. Chicken, which are efficient from a total feed point of view, are no longer that efficientwhen we look at the fraction of concentrates in their feed. This fraction is 73% for broiler chicken (global
average), while it is only 5% for beef cattle.

22 / The water footprint of farm animals and animal products

1850

839

784

Blue

17

9

455

590

Grey

102

129

308

316

Green

1638

1411

847

666

7

20

1591

Barley

Blue

Maize

MilletSoybeans

Rapeseed

Cottonseed Cake

Fodder crops

Pasture

1021

1842

1277

1162

318

88

342

178

294

203

227

207

499

1247

941

908

1213

780

376

204

79

139

145

861

194

96

120

145

131

Green

718

1619

791

311

440

2225

1490

523

947

Blue

521

1

74

713

20

103

62

63

81

Grey

135

124

295

364

118

195

308

176

194

Green

2954

3344

1600

11982

2509

3719

2953

2990

4306

164

40

26

84

76

59

61

57

Grey

228

141

222

79

128

233

302

309

115

Green

444

433

357

422

394

258

529

471

550

1

Grey

32

17

56

31

29

24

22

22

13

Green

116

39

147

14

60

63

49

67

82

Blue

3

59

164

3

26

37

26

Grey

63

12

82

50

21

29

14

20

25

Green

1714

2186

2231

1869

1533

3322

1629

1562

2037

Blue

65

1

129

122

23

18

98

92

70

Grey

10

15

106

43

11

92

10

10

37

Green

2095

2771

1483

1556

1155

1646

2567

2743

1703

2

7

1213

1

1467

4

3

231

Blue

Sesame seed
Cake

643

155

Blue

Sugar beet

608

Grey

Blue

Cassava

World
Average

Egypt

1994

USA

China

Green

MexicoBrazil

Wheat

India

Water
footprint
component

Germany

Feed

Australia

Table 2. Average water footprint of selected feed components for selected countries (m3/ton) (1996-2005).

Grey

420

98

466

197

259

235

341

360

336

Green

1422

1813

1851

1550

1272

2756

1352

1296

1690

Blue

54

1

107

101

19

15

81

76

58

Grey

8

12

88

35

9

76

8

8

31

Green

254

648

328

154

245

1170

425

388

471

Blue

276

52

111

670

178

341

195

169

270

Grey

53

81

114

103

53

172

48

68

91

Green

254

158

2461

232

131

412

117

244

207

Blue

204

148

33

44

27

Grey

15

7

105

285

30

31

11

35

20

Green

762

307

225

225

131

407

174

372

315

Blue
Grey
Source: data for feed crops based on Mekonnen and Hoekstra (2010b); data for pasture from this study. The
water footprints shown in this table refer the weighted average of domestically produced and imported feeds.

The water footprint of farm animals and animal products / 23

Table 3. Average annual water footprint of one animal, per animal category (1996-2005).

Animalcategory

Water footprintof live animal atend of life time
(m3/ton)Average animal
weight at end oflife time (kg)Dairy cattle

Average water
footprint at end of
3
life time (m /animal)

Average annual
Average life
water footprint of one
time (yr)animal (m3/yr/animal)

20558

10

2056

Horse

40612

473

19189

12

1599

Beef cattle

7477

253

1889

3.0

630

Pig

3831

102

390

0.75

520

Sheep

4519

31.3

141

2.1

68

47

1.4

33

Layer chicken
Goat

3079

24.6

76

2.3

32

Broiler chicken

3364

1.90

6

0.25

26

Total water footprint per ton of productFor all farm animal products, except dairy products, the total water footprint per unit of product declines from thegrazing to the mixed production system and then again from the mixed to the industrial production system. The
reason is that, when moving from grazing to industrial production systems, feed conversion efficiencies become
better. Per unit of product, about three to four times more feed is required for grazing systems when compared toindustrial systems (see Table 1). More feed implies that more water is needed to produce the feed. However, thefact that feed conversion efficiencies in grazing and industrial production systems differ by a factor 3 to 4 does
not mean that the water footprints of animal products are 3 to 4 times larger when derived from a grazing insteadof an industrial system. This is because the feed composition of animals raised in grazing systems is generally
more favourable from a water resources point of view. For all animal categories, the fraction of concentrate feedin the total feed is larger for industrial systems if compared to mixed production systems and larger for mixed
systems if compared to grazing systems. The water footprint per kg of concentrate feed is generally larger thanfor roughages, so that this works to the disadvantage of the total water footprint of animals raised in industrial
systems and to the advantage of the total water footprint of animals raised in grazing systems. This effect,
however, does not fully compensate for the unfavourable feed conversion efficiencies in grazing systems. An
exception is in dairy farming, where the total water footprint per unit of product is comparable in all three
production systems. For dairy products, the water footprint happens to be smallest when they are derived from amixed system and a bit larger but comparable when obtained from a grazing or industrial system.

Blue and grey water footprints per ton of productAll the above is about comparing the total water footprints of animal products. The picture changes when we
focus on the blue and grey water footprint components. With the exception of chicken products, blue and grey
water footprints always increase from grazing to industrial production systems. Figure 9 illustrates this byshowing the blue water footprint of a number of animal products across the three productions systems. For thegrey water footprint similar pictures can be obtained. The larger blue and grey water footprints for products
obtained from industrial production systems are caused by the fact that concentrate feed takes a larger share in
the total feed in industrial systems when compared to grazing systems. For beef cattle in grazing systems, the24 / The water footprint of farm animals and animal products

global average share of concentrate feed in total feed is 2%, while in industrial systems it is 21%. Mixed systems
are generally somewhere in between. Although the feed crops that are contained in the concentrate feed are often
to a great extent based on green water, there is a blue water footprint component as well, and the larger the
consumption of feed crops compared to roughages, the larger the total amount of blue water consumed. This
explains the larger blue water footprint per ton of product in industrial production systems for beef, milk, cheese,and pig, sheep and goat meat. The application and leaching of fertilizers and other agro-chemicals in feed crop
production results in the fact that the grey water footprint of animal products from industrial systems, where thedependence on feed crops is greatest, is larger than for grazing systems. Given the fact that freshwater problems
generally relate to blue water scarcity and water pollution and to a lesser extent to competition over green water,
this means that – from a water resources point of view – grazing systems are preferable over industrial
production systems for cattle, pig, sheep and goat.

In the case of chicken products (chicken meat and egg), the industrial production system has, on average, asmaller blue and grey water footprint per ton of product compared to the other two production systems. The
reason is that chicken strongly rely on concentrate feed in all production systems, intensive or extensive. Broiler
chicken in extensive systems have a share of concentrate feed in total feed of 63%, while this is 81% in intensive
industrial systems. There is still a difference, but the differences in feed composition for both broiler and layer
chicken is less outspoken if compared to the other animal categories. As a result, the relatively unfavourable feed
conversion efficiency in extensive systems is not compensated by a more favourable composition of the feed asis the case in the other animal categories.

Country differences
In general terms, one can say that the type of production system is highly relevant for the size, composition andgeographic spread of the water footprint of an animal product, because the type of production system determines
feed conversion efficiency, feed composition and origin of feed. Similarly we observe that the country of
production influences the water footprint of animal products in general terms as well. The Netherlands, forexample, shows lower total water footprints for most animal products if compared to the USA. The USA, in turn,generally shows lower total water footprints for animal products than India. These crude general differences
between countries are related to existing country differences in feed conversion efficiencies, but also to the factthat water footprints of feed crops vary across countries as a function of differences in climate and agricultural
practice.

Water footprint components - example for beef
For all animal products, the water footprint related to the animal feed takes by far the largest share in the total
water footprint. Further one can say that the green water footprint is always much larger than the blue and grey
water footprints. As an example, Table 5 shows in detail the components of the water footprint of producing akilogram of beef. The water footprint is dominantly green water (94%) and the largest share comes from the feed
the cattle consume (99%). Drinking and service water contribute only 1% toward the total water footprint, but
30% to the blue water footprint. The major fraction (83%) of the water footprint of a beef cow is attributed to thederived beef, but smaller fractions go to the other products: offal, leather and semen.

Table 4. The green, blue and grey water footprint of selected animal products for selected countries (m3/ton).
Animalproducts
Beef

Australia

Brazil

China

India

Netherlands

RussiaUSA

Global average

Farming system

Grazing
Mixed
Industrial
Weighted average
Sheep meat Grazing
Mixed
Industrial
Weighted average
Goat meat
Grazing
Mixed
Industrial
Weighted average
Pig meat
Grazing
Mixed
Industrial
Weighted average
ChickenGrazingmeat
Mixed
Industrial
Weighted average
Egg
Grazing
Mixed
Industrial
Weighted average
Milk
Grazing
Mixed
Industrial
Weighted average
ButterGrazing
Mixed
Industrial
Weighted average
Milk powder Grazing
Mixed
Industrial
Weighted average
CheeseGrazing
Mixed
Industrial
Weighted average
Grazing
LeatherMixed(bovine)Industrial
Weighted average

Green

Blue

Grey

Green

Blue

Grey

Green

Blue

Grey

Green

Blue

Grey

18056
14455
4730
14507
13236
6554

745
623
304
613
438
427

55
61
96
62
9
22

10151
4809
2435

434
245
233

15
0
0

3733
4299
2056
7908
5284
4862
2893
2968
2962
2243
1435
1570
1555
780
700
517
704
4246
3808
2814
3829
3628
3253
2405
3271
3857
3459
2556
3478
17601
14090
4610
14150

240
3721
1909
651
1226
276
173
176
176
146
99
107
106
74
64
48
63
400
347
261
344
342
296
223
294
380
331
253
328
801
682
407
673

23729
20604
8421
19228
19440
10649
4747
11772
15860
8745
3754
8144
5482
5109
8184
6080
6363
4073
3723
4204
432
257
3625
2737
1046
1254

0
247
118
656
414
336
200
205
205
173
111
121
120
20
35
43
33 1149
107 5691
192 6822231
0
178 6254
91 4862
164 5829198
0
152 5344
97 5169
174 6197
210
162 5681
54 22821
59 19815
93 8099
60 18445

150
187
147
178
372
421
445
421
328
349
406
372
1689
828
215
749
35
32
24
30
24
24
28
27
22
42

16
61
244
82
1
9
12
7
0
0
0
0
318
316
525
379
364
233
213
240
25
15
213
161
7
36

16140
13227
10922
12795
9606
5337
2366
5347
5073
2765
1187
2958
11134
5401
3477
5050
4695
3005
1940
2836
3952
2351
2086
2211
1580
897

0
339
933
495
0
454
451
452
0
283
437
312
205
356
538
405
448
297
195
281
375
230
206
217
106
147

0
103
1234
398
0
14
22
14
0
0
0
0
738
542
925
648
1414
905
584
854
1189
708
628
666
128
213

25913
16192
12412
15537
11441
7528
4523
7416
8081
4544
2046
4194
3732
4068
9236
5415
11993
7676
3787
6726
10604
6309
3611
4888
1185
863

0
533
1471
722
0
582
593
582
0
381
436
393
391
893
2014
1191
1536
995
496
873
1360
815
472
635
105
132

33
122
230
0
179
104
197
0
153
126
225

22
39
196
0
117
34
167
0
100
36
178

927
8600
4880
0
5044
7348
4169
0
4309
7812
4432

145
577
799
0
789
493
683
0
674
540
742

210
696
1161
0
1141
595
992
0
975
633
1055

885
6448
4697
0
4819
5510
4013
0
4117
5857
4267

130
572
716
0
706
489
612
0
603
535
666

178
219
255
217
246

107 4581
15 14300
59 11719
235 9677
79 11323

732
0
377
904
515

1036
0
91
1093
352

4377
25195
15743
12068
15103

657
0
593
1505
777

0
144 10319
866 3934
288 56840
316 8248484
314 8248
0
9 244330
13 2443
325 4048
390 3653
1021 3776
554 3723
1369 2535
876 1509
432 1548
768 1545
1176 1695
699 1085
400 1187
542 1175
34
572
65
431
500
63
462
188 3111
352 2345
0 2720341 2513
160 2658
301 2003
0 2324291 2147
171 2826
320 21302471
310 22830
140 11883
842 4530
280 6067

Green

Blue

Grey

Green

Blue

Grey

Green

Blue

Grey

Green

Blue

Grey

15182
11615
23591
16264
14236
7176
3044
9284
7086
3615
1546
4432
7176
7212
5165
6937
8854
5259
2976
6036

411
451
1002
585
351
379
469
395
219
247
322
266
357
472
397
429
334
210
124
235

200
204
871
372
3
7
9
5
0
0
1
0
282
289
207
276
321
190
108
219

19102
12726
2949
12933
11910
9842
0
10948

525
546
356
525
312
318
0
315

590
768
551
733
18
74
0
44

4617
4455
4511
0
1143
1488
1273

170
164
166
0
60
76
65

168
162
164
0
39
56
45

6221
8098
6927
0
5315
6920
5919

324
415
355
0
277
355
303

213
302
247
0
182
258
211

5651
7356
6292
16922
765 12946
259 26295
369 18093

310
393
338
529
574
1189
723

194
275
224
223
228
971
414

5118
4953
3404
4102
2836
1688
1731
1728
1740
1113
1218
1206
1106
582
444
647
6022
3169
2417
3519
5145
2708
2065
3007
5470
2878
2196
3196
21290
14185
3287
14450

870
743
563
645
294
183
187
187
183
121
132
130
69
59
61
60
373
321
330
324
319
274
282
277
355
307
315
310
657
681
497
658

890
916
634
761
497
296
303
303
331
212
232
230
89
88
100
89
482
478
543
483
412
409
464
413
438
435
493
439
658
856
614
819

21121
14803
8849
14414
15870
7784
4607
9813
9277
4691
2431
5185
7660
5210
4050
4907
7919
4065
2337
3545
6781
3006
2298
2592
1087
790
1027
863
5913
4297
5591
4695
5052
3671
4777
4011
5371
3903
5078
4264
20905
16701
9487
15916

465
508
683
550
421
484
800
522
285
313
413
330
431
435
487
459
734
348
210
313
418
312
205
244
56
90
98
86
305
492
532
465
261
421
455
398
293
463
500
439
535
644
805
679

243
401
712
451
20
67
216
76
0
4
18
6
632
582
687
622
718
574
325
467
446
545
369
429
49
76
82
72
265
415
448
393
227
354
382
336
241
377
406
357
240
453
763
498

761
349
484

664
225
345

422

35

422

35

453

4

454
479
306
236
268
113
76
77
77
76
51
55
55
50
40
43
41
272
218
233
224
232
186
199
191
263
214
227
219

4
587
451
427
438
271
161
165
165
161
103
113
111
32
23
25
25
176
123
136
134
151
105
116
114
160
111
124
121

947
513
589

26 / The water footprint of farm animals and animal products

Beef

Pork
600

Blue water footprint (m 3/ton)Blue water footprint (m 3/ton)

750
600
450
300
150
0

500
400
300
200
100
0

Grazing

Mixed

Industrial

Weighted
average

Grazing

Animal production systems

Milk

CheeseBlue water footprint (m 3/ton)Blue water footprint (m 3/ton)

Weighted
average

600

90

60

30

0

500
400
300
200
100
0

Grazing

Mixed

Industrial

Grazing

Weighted
average

Animal production systems

Mixed

Industrial

Weighted
average

Animal production systems

Egg

Chicken meat
600

Blue water footprint (m 3/ton)800

Blue water footprint (m 3/ton)Industrial

Animal production systems

120

600

400

200

400

200

0

0
Grazing

Mixed

Industrial

Grazing

Weighted
average

Mixed

Industrial

Animal production systems

Animal production systems

Sheep meat

Goat meat

1000

Weighted
average

500

Blue water footprint (m 3/ton)Blue water footprint (m 3/ton)

Mixed

800
600
400
200
0

400
300
200
100
0

Grazing

Mixed

Industrial

Animal production systems

Weighted
average

Grazing

Mixed

Industrial

Weighted
average

Animal production systems

Figure 9. Global average blue water footprint per production system for selected animal products (1996-2005).

The water footprint of farm animals and animal products / 27

Table 5. The components of the water footprint of a beef cow and its derived products.
Weighted average water
footprint of feed (litre/kg)

Feedamount(kg/kgcarcass)

Green

Maize

1.0102

695

111

181

702

112

182

996

Wheat

0.2441

1322

77

140

323

18.8

34.0

375

Barley0.2657

1143

59

126

304

15.6

33.4

353

Soya bean cake

0.1858

1451

72

19

270

13.4

3.6

286

Sorghum

0.1028

1228

130

92

126

13.4

9.5

149

Oats

0.0603

1457

212

125

87.8

12.8

7.6

108

Rice, paddy

0.0754

997

259

165

75.1

19.6

12.4

107

Cassava

0.1451

498

0

12

72.3

0.0

1.8

74.1

Oilseed cakes, other0.0275

2158

37

50

59.4

1.0

1.4

61.7

Rape and mustard cake

0.0479

977

132

151

46.8

6.3

7.2

60.4

Rye

0.0233

1573

38

109

36.7

0.9

2.5

40.1

Millet0.0107

2718

130

172

29.0

1.4

1.8

32.2

Cereals, not specified

0.0308

874

66

41

26.9

2.0

1.3

30.2

Sunflower seed cake0.0249

968

63

98

24.1

1.6

2.4

28.1

Pulses, not specified

0.0132

1133

307

618

15.0

4.1

8.2

27.2

Molasses

0.0597

311

110

29

18.6

6.6

1.7

26.9

Groundnut cake

0.0171

1265

121

106

21.7

2.1

1.8

25.6

Soybeans

0.0140

1744

41

24

24.5

0.6

0.3

25.4

Potatoes

0.0796

254

10

48

20.2

0.8

3.8

24.9

Cottonseed cake

0.0280

481

259

86

13.5

7.3

2.4

23.1

Cottonseed

0.0181

618

353

124

11.2

6.4

2.2

19.8

Peas, dry

0.0126

1149

21

336

14.4

0.3

4.2

18.9

Sunflower seed

0.0054

2744

144

234

14.8

0.8

1.3

16.9

Sugar cane

0.0698

171

35

16

11.9

2.5

1.1

15.5

Plantains

0.0091

1392

27

3

12.7

0.2

0.0

13.0

Beans, dry

0.0029

3270

48

575

9.4

0.1

1.6

11.1

Rapeseed

0.0049

1877

3

305

9.3

0.0

1.5

10.8

Vegetables fresh not specified

0.0369

152

49

69

5.6

1.8

2.5

10.0

Copra cake

0.0046

1567

2

10

7.2

0.0

0.0

7.2

Sweet potatoes

0.0170

285

7

57

4.8

0.1

1.0

5.9

Yams

0.0166

326

0

1

5.4

0.0

0.0

5.5

Palm kernel cake

0.0075

659

0

27

4.9

0.0

0.2

5.2

Dates

0.0009

2397

2074

97

2.1

1.8

0.1

4.0

Sesame seed cake

0.0015

2111

53

53

3.1

0.1

0.1

3.3

Sugar beet

0.0165

154

16

30

2.5

0.3

0.5

3.3

Oilseeds, not specified

0.0024

802

94

35

2.0

0.2

0.1

2.3

Other minor feed crops

0.0122

325

66

40

3.9

0.8

0.5

5.2

Feed crop*

Blue

Water footprint (litre/kg carcass)

Grey

Green

Blue

Grey

Total

continued on next page

28 / The water footprint of farm animals and animal products

Weighted average water
footprint of feed (litre/kg)

Feedamount(kg/kgcarcass)

Green

Crop residues

21.943

0

0

0

0.0

0.0

0.0

0.0

Fodder crops

2.4632

168

29

21

415

71.8

50.7

537

Pasture (grass)31.525

303

0

0

9556

0.0

0.0

9556

Feed crop*

Blue

Water footprint (litre/kg carcass)

Grey

Green

Blue

Water for feed mixing
Water footprint related to feed

Grey

1.5
12391

314

Total

1.5
388

13107

Drinking water

110

110

Service water29

29

Total water footprint of beef cattle (litre/kg carcass)

12391

453

388

13246

Total water footprint of a 253 kg beef cow (in litre)(assuming a total carcass weight of 143 kg)1769000

64600

55300

1889000… of which 83% is attributed to the 101 kg of resultant beef, so thatthe water footprint of beef** (litre/kg beef) amounts to:

14400

550

450

15400

… of which 10% is attributed to the 18 kg of resultant offal, so thatthe water footprint of offal** (litre/kg offal) amounts to:

10400

400

330

11200

… of which 5% is attributed to the 6.1 kg of resultant leather, so thatthe water footprint of leather** (litre/kg leather) amounts to:

15900

680

500

17100

… of which 2% is attributed to the 0.03 kg of resultant semen, so thatthe water footprint of semen** (litre/kg semen) amounts to: 1069000

40600

33400

1143000* The feed amounts included here represent the global average feed intake of beef cattle. Obviously, the feed
composition of individual cows will deviate based on the production system and composition of the concentrate
feed applied.
** The percentage of the total water footprint of a beef cow attributed to each product refers to the ‘value fraction’for that product (Appendix V). The amount of a certain product (in kg) coming from the total animal is based onthe ‘product fraction’ for that product (Appendix V). In the blue water footprint, we added the water footprint ofprocessing the slaughtered cow into the derived products.

3.4

Water footprint of animal versus crop products per unit of nutritional value

As a general picture we find that animal products have a larger water footprint per ton of product than crop
products. As we see from Table 6, the global average water footprint per ton of crop increases from sugar crops(roughly 200 m3/ton) and vegetables (~300 m3/ton) to pulses (~4000 m3/ton) and nuts (~9000 m3/ton). For
animal products, the water footprint increases from milk (~1000 m3/ton) and egg (~3300 m3/ton) to beef (~15400
m3/ton). Also when viewed from a caloric standpoint, the water footprint of animal products is larger than forcrop products. The average water footprint per calorie for beef is twenty times larger than for cereals and starchy
roots. When we look at the water requirements for protein, we find that the water footprint per gram of protein
for milk, eggs and chicken meat is about 1.5 times larger than for pulses. For beef, the water footprint per gramof protein is 6 times larger than for pulses. In the case of fat, we find that butter has a relatively small water
footprint per gram of fat, even lower than for oil crops. All other animal products, however, have larger water
footprints per gram of fat when compared to oil crops. The general conclusion is that from a freshwater resource
perspective, it is more efficient to obtain calories, protein and fat through crop products than animal products. A
note should be made here, however, that types of proteins and fats differ across the different products.

The water footprint of farm animals and animal products / 29

Table 6. The water footprint of some selected food products from vegetable and animal origin.
Water footprint per ton (m3/ton)
Food item

Nutritional content

Water footprint per unit ofnutritional value
ProteinFat
Calorie(litre/g (litre/g(litre/kcal)
protein)
fat)

Green

Blue

Grey

Total

Calorie(kcal/kg)

Protein(g/kg)

Fat(g/kg)

Sugar crops

130

52

15

197

285

0.0

0.0

0.69

0.0

0.0

Vegetables

194

43

85

322

240

12

2.1

1.34

26

154

Starchy roots

327

16

43

387

827

13

1.7

0.47

31

226

Fruits

726

147

89

962

460

5.3

2.8

2.09

180

348

Cereals

1232

228

184

1644

3208

80

15

0.51

21

112

Oil crops

2023

220

121

2364

2908

146

209

0.81

16

11

Pulses

3180

141

734

4055

3412

215

23

1.19

19

180

Nuts

7016

1367

680

9063

2500

65

193

3.63

139

47

Milk

863

86

72

1020

560

33

31

1.82

31

33

Eggs

2592

244

429

3265

1425

111

100

2.29

29

33

Chicken meat

3545

313

467

4325

1440

127

100

3.00

34

43

Butter

4695

465

393

5553

7692

0.0

872

0.72

0.0

6.4

Pig meat

4907

459

622

5988

2786

105

259

2.15

57

23

Sheep/goat meat

8253

457

53

8763

2059

139

163

4.25

63

54

Bovine meat

14414

550

451

15415

1513

138

101

10.19

112

153

In order to reduce the pressure on the world’s water resource associated with their consumption pattern,
individuals have the option of shifting from a meat-rich to a vegetarian diet. The water footprint of an individual
consumer depends to a large extent on the type of diet of the individual. Meat-based diets have a larger water
footprint compared to a vegetarian diet. The average USA citizen consumes almost four times the amount ofprotein compared to the global average (FAO, 2009). About 63% of the daily protein intake comes from animal
based products. This high level of consumption of animal-based products is directly reflected in the relative large
water footprint of the average American citizen (Hoekstra and Chapagain, 2007). Replacing 50% of all animal
products by an equivalent amount of high nutritious crop products such as pulses, groundnuts and potatoes will
result a 30% reduction of the food-related water footprint. A vegetarian diet compared with the average current
per capita food intake in the USA can reduce the water footprint of an individual by as much as 58%.

3.5

The total water footprint of animal production

During the period 1996-2005, the total water footprint for global animal production was 2422 Gm3/yr (87.2%
green, 6.2% blue and 6.6% grey water). The different components of the global water footprint of animal
production are shown in Table 7. The largest water footprint for the animal production comes from the feed they
consume, which accounts for 98% of the total water footprint. Drinking water, service water and feed mixing
water further account only for 1.1%, 0.8% and 0.03% of the total water footprint, respectively. The estimate ofdrinking and service water is in line with Peden et al. (2007). Grazing accounts for the largest share (38%),
followed by maize (17%) and fodder crops (8%).

30 / The water footprint of farm animals and animal products
The global water footprint of feed production is 2376 Gm3/yr, of which 1463 Gm3/yr refers to crops and theremainder to grazing (Table 8). The total water footprint of feed crops amounts to 20% of the water footprint of
total crop production in the world, which is 7404 Gm3/yr (Mekonnen and Hoekstra, 2010b). The globally
aggregated blue water footprint of feed crop production is 105 Gm3/yr, which is 12% of the blue water footprintof total crop production in the world (Mekonnen and Hoekstra, 2010b). This means that an estimated 12% of the
global consumption of groundwater and surface water for irrigation is for feed, not for food, fibres or other crop
products. Globally, the total water footprint of animal production (2422 Gm3/yr) constitutes 29% of the water
footprint of total agricultural production.

When we consider the total water footprint per animal category (Table 9), we find that beef cattle have thelargest contribution (33%) to the global water footprint of farm animal production, followed by dairy cattle(19%), pig (19%) and broiler chicken (11%). The green, blue and grey water footprints per animal category andproduction system are shown in Table 10. Altogether, mixed production systems account for the largest share(57.4%) in the total water footprint of animal production. Grazing and industrial production systems account for
20.3% and 22.3%, respectively. In the grazing system, over 97% of the water footprint related to feed comesfrom grazing and fodder crops and the water footprint is dominantly (94%) green. In the mixed and industrial
production systems, the green water footprint forms 87% and 82% of the total footprint, respectively. The blue
water footprint in the grazing system accounts for 3.6% of the total water footprint and about 33% of this comesfrom the drinking and service water use. In the industrial system, the blue water footprint accounts for 8% of thetotal water footprint.
Table 7. Global water footprint of animal production by component.
3

Total water footprint (Mm /yr)Feed crop
Green

Blue

Grey

Total

Share (%)

Grazing

9128160.0

0.0

912816

37.7

Maize

302595

33581

74960

41113617.0

Fodder crops

167896

9900

10903

188699

7.79

Soybean cake1682216559

3178

177958

7.35

Wheat

122934

8345

16214

147493

6.09

Barley116844

6778

14410

138031

5.70

Oats

48508

10370

4753

63631

2.63

Sorghum

40781

3376

2798

46954

1.94

Rice, paddy

24699

7497

4863

37059

1.53

Oilseed cakes, other

22159

409

525

23093

0.95

Rape and mustard cake

16841

2457

3134

22432

0.93

Cassava

17630

8.6

849

18488

0.76

Cereals, not else specified

15683

881

979

17543

0.72

Sweet potatoes

12927

210

2781

15918

0.66

Rye

13628

249

1057

14934

0.62

Pulses, not else specified

7829

1242

4300

13371

0.55

continued on next page

The water footprint of farm animals and animal products / 31

Total water footprint (Mm3/yr)
Feed crop
Green

Blue

Grey

Total

Share (%)

Sunflower seed cake

11279

626

905

12809

0.53

Potatoes

9602

369

2500

12471

0.51

Millet

9617

607

458

10682

0.44

Soybeans

9786

374

212

10372

0.43

Groundnut cake

8874

658

575

10107

0.42

Peas, dry

6666

144

1736

8546

0.35

Cottonseed cake

4851

2889

775

8514

0.35

Molasses

4214

1808

410

6432

0.27

Cottonseed

3252

2480

618

6350

0.26

Vegetables fresh not else specified

3665

703

1977

6345

0.26

Beans, dry

4003

54

922

4979

0.21

Sunflower seed

4045

200

314

4560

0.19

Rapeseed

3338

11

763

4111

0.17

Copra cake

3581

3.5

23

3608

0.15

Sugar cane

2148

590

217

2955

0.12

Palm kernel Cake

2519

0.7

93

2612

0.11

Sesame seed cake

2111

53

46

2210

0.09

Plantains

2078

52

4

2134

0.09

Sugar beet

1070

70

285

1425

0.06

Oilseeds, not else specified

990

150

50

1191

0.05

Bananas

761

53

41

855

0.04

Yams

767

0.5

3.3

771

0.03

Dates

244

279

15

538

0.02

Apples

326

118

38

483

0.02

Tomatoes

102

93

39

234

0.01

Roots and tubers, not else specified

177

4.1

27

208

0.01

Fruits, other

116

25

9

150

0.01

Groundnuts

70

8

5

83

0.00

Coconuts

38

0.0

0.1

38

0.00

Cocoa beans

16

0.0

0.2

16

0.00

Onions

0.7

1.6

0.2

2.5

0.00

Sesame seed

1.8

0.3

0.2

2.2

0.00

Palm-kernels

0.8

0.0

0.0

0.8

0.00

Mixing water for feed preparation

0.0

610

0.0

610

0.03

Drinking water

27099

27099

1.12

Service water

18213

18213

0.75

2421722100.00Total water footprint

2112301

150660158762

32 / The water footprint of farm animals and animal products

Table 8. The global water footprint of animal production compared to the global water footprint of total agricultural
3
production for the period 1996-2005 (Gm /yr).
Green

Blue

Grey

Total

Water footprint of crop production*

5771

899

733

7404

Water footprint of grazing

913

-

-

913

-

46

-

46

6684

899

733

8317

Water footprint of feed crop production

1199

105

159

1463

Water footprint of grazing

913

-

-

913

-

46

-

46

Total

2112

151

159

2422

Water footprint of animal production as a percentage ofthe total water footprint in agricultural production

32%

17%

22%

29%

Water footprint of total agricultural production

Direct water footprint of livestock**
Total
Water footprint of animal production

Direct water footprint of livestock*** Source: Mekonnen and Hoekstra (2010b).
** Water footprint of drinking, servicing and feed mixing.

A substantial part of the water footprint of an animal product produced in one country often resides outside thatcountry. This is most in particular the case for products originating from industrial production systems, because
those systems use the largest fraction of concentrate feed. Feed crops are often imported rather than produced
domestically. Soybean cake, for example, which is an important feed ingredient in industrial livestock raising, isoften imported. In the period 1996-2005, 49% of global soybean production was exported, either in the form ofsoybean or in the form of soybean cake (FAO, 2009).
Table 9. The total water footprint per animal category (1996-2005).
Global total numberof animals* (millions)Average annual water footprint3
per animal** (m /yr per animal)

Annual water footprint ofanimal category (Gm3/yr)%

Beef cattle

1267

630

798

33

Dairy cattle

228

2056

469

19

Pig

880

520

458

19

Broiler chicken

9923

26

255

11

Horse

112

1599

180

7

Layer Chicken

5046

33

167

7

Sheep

1052

68

71

3

Goat

750

32

24

1

Total

19258

2422

100

Animal category* Source: FAO (2009).
** See Table 3.

The water footprint of farm animals and animal products / 33
Table 10. The green, blue and grey water footprints per animal category and production system (Gm3/yr) for theperiod 1996-2005.

Animal category

Grazing production
systemMixed production
systemGrey GreenBlue

Industrial production
systemGrey GreenBlue

World total

Green

Blue

Grey GreenBlue Grey

Beef cattle

185

4.5

2.1

443

20

12

112

10

9.0

740

35

23

Dairy cattle

83

3.6

3.7

269

27

26

48

4.1

3.8

400

35

34

Pig

27

1.5

2.2

237

19

27

111

14

19

376

34

48

Broiler chicken

37

3.4

3.3

100

8.3

14

73

6.3

10

210

18

28

Horse

82

3.0

1.4

69

7.1

2.4

13

0.8

0.6

164

11

4

Layer chicken

4.5

0.3

0.3

52

5.4

9.4

77

6.5

12

133

12

22

Sheep

34

1.2

0.0

28

2.0

0.2

5.0

1.0

0.2

66.5

4.3

0.5

Goat

8.2

0.3

0.0

13

0.9

0.0

2.0

0.4

0.0

22.7

1.5

0.0

Total

461

17.8

13.2

1210

90

90

442

43

55

2112

151

159

4. Discussion
The result of the current study can be compared with results from earlier studies. However, only a few otherstudies on the water footprint per unit of animal product and the total water footprint of animal production areavailable. We will first compare our estimates of the water footprints per ton of animal product with two earlier
studies and subsequently we will compare the total water footprint related to animal feed production with fiveearlier studies.

The rough estimates made by Pimentel et al. (2004) for the water footprints of beef and meat from sheep, pig andchicken are partly very close to our global estimates but partly also quite different. They report a water footprintof chicken meat of 3500 m3/ton, which is only a bit lower than our global average estimate of 4300 m3/ton, andeven closer if we subtract the grey water footprint component from our estimate (which is not included in
Pimentel’s studies). They report a water footprint of pig meat of 6000 m3/ton, which happens to coincide with
our global average estimate (but our estimate includes the grey water footprint component). For sheep meat, theyreport a water footprint of 51000 m3/ton and for beef 43000 m3/ton, values that are very high when compared toour estimates (10,400 m3/ton for sheep meat and 15400 m3/ton for beef). We consider the values reported by
Pimentel as crude first estimates, for which the underlying assumptions have not been spelled out, so that it isdifficult to explain differences with our estimates.

The study of Chapagain and Hoekstra (2004) is the only publication with global estimates of the water footprintof animal products with specifications by country. At a global level, the estimated water footprints per ton ofanimal and animal product compare very well with the estimates from Chapagain and Hoekstra (2004), with an r2of 0.88 (Figure 10a). The good agreement at the global level between the two studies is probably that the global
average water footprints for various feed ingredients are very close in the two studies. The trend line in Figure
10a is slightly above 1, which is caused by our higher estimates for the water footprints of sheep and goat meat.
For most other animal products, the current study gives a bit lower estimates than the earlier study.

When we compare our estimates with Chapagain and Hoekstra (2004) at a country level, more differences arefound (Figure 10b-f). The two studies show a relatively good agreement for pig meat, chicken meat and egg –although for egg the earlier study systematically gives higher numbers – but little agreement for beef and dairy
products. In general we find that Chapagain and Hoekstra (2004) underestimated the water footprints for Africancountries and overestimated the water footprints for OECD countries. As already pointed out in the introductory
chapter, there are three main reasons why the estimates from the current study can differ from the 2004-study
and are considered more accurate. First, the current study is based on better data for the estimation of thequantity and composition of animal feed. Second, the current study reckons with the relative presence of thethree production systems per country and accounts for the differences between those systems. Third, we haveestimated the water footprints of the various feed ingredients more accurately by using a high-resolution gridbased crop water use model, including the effect of water deficits where they occur, making explicit distinction
between the green and blue water footprint components and including the grey water footprint component.

36 / The water footprint of farm animals and animal products

trend line
1:1 liney = 1.0246x
R² = 0.8773

15000
beef
10000

sheep meat
beef cattle

goat meat
5000

pig meat
milk

0
0

5000

10000

15000

20000

100000Beef WF estimate from current study [m 3/ton]

Animals and animal products WF estimate
from current study [m 3/ton]

20000

1:1 line
75000

Cyprus

Syria
Mongolia

25000

MoroccoMostlyOECD
countries

Mexico
Spain

0
0

25000

50000

75000

100000Beef WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]

Portk WF estimate from current study [m 3/ton]

Milk WF estimate from current study [m 3/ton]Tunisia

Ertrea
Benin

(b)

10000

y = 0.835x
R² = 0.4798

trend line
1:1 line
7500

5000

Mauritania

SenegalNiger
Hungary

2500

Georgia

Mongolia

0
0

2500

5000

7500

20000
trend line
1:1 liney = 0.891x
R² = 0.7929

15000

10000

Tajikstan

5000

0
0

10000

5000

10000

15000

20000

Pork WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]

Milk WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]

(c)

(d)

20000
trend line
1:1 line

Egg WF estimate from current study [m 3/ton]

Chicken meat WF estimate from current study[m 3/ton]

Bolivia

MostlyAfricancountries

50000

Animals and animal products WF estimate from Chapagain and Hoekstra (2004)[m 3/ton](a)y = 0.8917x
R² = 0.2649

trend line

y = 0.9369x
R² = 0.8717

15000

10000

5000

0

20000
trend line
1:1 liney = 0.6422x
R² = 0.6972

15000

10000

5000

0

0

5000

10000

15000

20000

0

Chicken meat WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]

(e)

5000

10000

15000

20000

Egg WF estimate from Chapagain and Hoekstra (2004) [m 3/ton](f)Figure 10. Comparison of average water footprint of (a) animals and animal products at global level, and (b) beef(c) milk, (d) pig meat, (e) chicken meat and (f) egg at the country level as estimated in the current study andChapagain and Hoekstra (2004). From the current study we show here the sum of green and blue water
footprints, excluding the grey water footprint, because that component was excluded in the 2004-study.

As one can see in the overview presented in Table 11, our estimate of the total evaporative water use (green plus
blue water footprint) for producing animal feed (2217 Gm3/yr) is 3% larger than the estimate by De Fraiture et al.
(2007) and 5% smaller than the estimate by Zimmer and Renault (2003). Our estimate of the global consumptive
water use for producing feed crops (1312 Gm3/yr) does not significantly differ from the estimate by De Fraiture
et al. (2007). Our estimate of global consumptive water use for grazing (913 Gm3/yr) is 9% larger than theestimate by De Fraiture et al. (2007). The differences with three other studies that reported on the consumptive
water use related to grazing are much larger, which is cause by another definition applied. Postel et al. (1996)
estimated the water evaporated from grazing land to be 5800 Gm3/yr. In more recent studies, Rost et al. (2008)
and Hanasaki et al. (2010) estimate the total evapotranspiration from grazing land to be 8258 Gm3/yr and 12960
Gm3/yr, respectively. However, unlike the current study, the estimates in these three studies refer to the total
evapotranspiration from grazing lands rather than to the evaporation related to the grass actually consumed.

The water footprint of farm animals and animal products / 37

According to De Fraiture et al. (2007), reported ‘grazing lands’ are only partly actually grazed. Besides, theharvest efficiency – the fraction of grass actually consumed by the animal compared to the standing biomass – isquite small. In a recent study in the USA, Smart et al. (2010) showed that, depending on the animal stocking
density, harvest efficiencies reach between 14-38%.
Table 11. Comparison of the results of the current study with the results from previous studies.
Period3

Global water footprint* related to animal feed production (Gm /yr)StudyGrazing

Crops

Total

Postel et al. (1996)

1995

5800

-

-

Zimmer and Renault (2003)

2000

-

-

2340

De Fraiture et al. (2007)

2000

840

1312

2152

Rost et al. (2008)

1971-2002

8258

-

-

Hanasaki et al. (2010)

1985-1999

12960

-

-

Current study*

1996-2005

913

1304

2217

* The numbers in the table, also the ones from the current study, refer to the green plus blue water footprint. Noneof the previous studies included the grey water footprint component.

There are several uncertainties in this study in the quantification of the water footprint of animals and animal
products. Due to a lack of data, many assumptions have to be made. There are a number of uncertainties in the
study, but particularly two types of uncertainty may have a major effect on the final output of the study. First,
data on animal distribution per production system per country for OECD countries is not available. Wint andRobinson (2007) provide livestock distributions per production system per country for developing countries but
not for OECD countries. For these countries we are forced to use the data from Seré and Steinfeld (1996), whoprovide livestock distribution per economic region. These data have the limitation that they are not countryspecific and may lead to wrong distribution of animals into the different production system for some countries.
The second major uncertainty is related to the precise composition of feed per animal category per country. Suchdata are not directly available so that we had to infer these data by combining different data sources and anumber of assumptions.

Although the scope of this study is very comprehensive, there are many issues that have been left out. One issue
is that we neglected the indirect water footprints of materials used in feed production and animal raising. We
expect that this may add at most a few per cents to the water footprint estimates found in this study (based on
Hoekstra et al., 2009). In the grey water footprint estimations we have looked at the water pollution by nitrogenfertilisers only, excluding the potential pollution by other fertiliser components or by pesticides or other agrochemicals. Besides, we have not quantified the grey water footprint coming from animal wastes, which isparticularly relevant for industrial production systems. Intensive animal production often generates an amount ofwaste that cannot be fully recycled on the nearby land. The large amount of waste generated in a concentrated
place can seriously affect freshwater systems (FAO, 2005; Steinfeld et al., 2006; Galloway et al., 2007). Finally,
by focusing on freshwater appropriation, the study obviously excludes many other relevant issues in farm animal
production, such as micro- and macro-cost of production, livelihood of smallholder farmers, animal welfare,public health and environmental issues other than freshwater.

5. Conclusion
The present study estimates the water footprint of farm animals and animal products per production system andper country. The results show that:

Although beef cattle, sheep and goat require much more feed per unit of meat produced than pig and broiler
chicken, the fraction of concentrate feed in the total feed is much larger for the latter (Section 3.1). Since
concentrate feed has a larger water footprint per unit of weight than roughages (Section 3.2), the water
footprints of the different sorts of meat are closer than one would expect on the basis of feed conversion
efficiencies alone (Section 3.3).

The total water footprint of an animal product is generally larger when obtained from a grazing system thanwhen produced from an industrial system, because of a larger green water footprint component. The blue andgrey water footprints of animal products are largest for industrial systems (with an exception for chicken
products). From a freshwater perspective, animal products from grazing systems are therefore to be preferredabove products from industrial systems (Section 3.3).

The water footprint of any animal product is larger than the water footprint of a wisely chosen crop productwith equivalent nutritional value (Section 3.4).



29% of the total water footprint of the agricultural sector in the world is related to the production of animal
products. One third of the global water footprint of animal production is related to beef cattle (Section 3.5).

The global meat production has almost doubled in the period 1980-2004 (FAO, 2005) and this trend is likely tocontinue given the projected doubling of meat production in the period 2000-2050 (Steinfeld et al., 2006). To
meet this rising demand for animal products, the on-going shift from traditional extensive and mixed farming toindustrial farming systems is likely to continue. Because of the larger dependence on concentrate feed inindustrial systems, this intensification of animal production systems will result in increasing blue and grey water
footprints per unit of animal product. The pressure on the global freshwater resources will thus increase bothbecause of the increasing meat consumption and the increasing blue and grey water footprint per unit of meat
consumed.

Managing the demand for animal products by promoting a dietary shift away from a meat-rich diet will be an
inevitable component in the environmental policy of governments. In countries where the consumption of animal
products is still quickly rising, one should critically look how this growing demand can be moderated. On the
production side, it would be wise to include freshwater implications in the development of animal farming
policies, which means that particularly feed composition, feed water requirements and feed origin need to receive
attention. Animal farming puts the lowest pressure on freshwater systems when dominantly based on crop
residues, waste and roughages. Policies aimed to influence either the consumption or production side of farmanimal products will generally entail various sorts of socio-economic and environmental trade-offs (Herrero etal., 2009; Pelletier and Tyedmers, 2010). Therefore, policies aimed at reducing the negative impacts of animal
production and consumption should be able to address these potential tradeoffs. Policies should not affect the40 / The water footprint of farm animals and animal products

required increase in food security in less developed countries neither the livelihood of the rural poor should be
put in danger through intensification of animal farming.

This study provides a rich data source for further studies on the factors that determine how animal products put
pressure on the global water resources. The reported incidents of groundwater depletion, rivers running dry andincreasing levels of pollution form an indication of the growing water scarcity (UNESCO, 2009; Postel, 2000;
Gleick, 1993). Since animal production and consumption play an important role in depleting and polluting theworld’s scarce freshwater resources, information on the water footprint of animal products will help us
understand how we can sustain the scarce freshwater resources.

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Value of Water Research Report Series

Editorial board:
Arjen Y. Hoekstra – University of Twente, a.y.hoekstra@utwente.nl
Hubert H.G. Savenije – Delft University of Technology, h.h.g.savenije@tudelft.nl
Pieter van der Zaag – UNESCO-IHE Institute for Water Education, p.vanderzaag@unesco-ihe.org
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
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16.
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24.
25.

Exploring methods to assess the value of water: A case study on the Zambezi basin.
A.K. Chapagain  February 2000
Water value flows: A case study on the Zambezi basin.
A.Y. Hoekstra, H.H.G. Savenije and A.K. Chapagain  March 2000
The water value-flow concept.
I.M. Seyam and A.Y. Hoekstra  December 2000
The value of irrigation water in Nyanyadzi smallholder irrigation scheme, Zimbabwe.
G.T. Pazvakawambwa and P. van der Zaag – January 2001
The economic valuation of water: Principles and methods
J.I. Agudelo – August 2001
The economic valuation of water for agriculture: A simple method applied to the eight Zambezi basin countries
J.I. Agudelo and A.Y. Hoekstra – August 2001
The value of freshwater wetlands in the Zambezi basin
I.M. Seyam, A.Y. Hoekstra, G.S. Ngabirano and H.H.G. Savenije – August 2001
‘Demand management’ and ‘Water as an economic good’: Paradigms with pitfalls
H.H.G. Savenije and P. van der Zaag – October 2001
Why water is not an ordinary economic good
H.H.G. Savenije – October 2001
Calculation methods to assess the value of upstream water flows and storage as a function of downstream benefits
I.M. Seyam, A.Y. Hoekstra and H.H.G. Savenije – October 2001
Virtual water trade: A quantification of virtual water flows between nations in relation to international crop trade
A.Y. Hoekstra and P.Q. Hung – September 2002
Virtual water trade: Proceedings of the international expert meeting on virtual water trade
A.Y. Hoekstra (ed.) – February 2003
Virtual water flows between nations in relation to trade in livestock and livestock products
A.K. Chapagain and A.Y. Hoekstra – July 2003
The water needed to have the Dutch drink coffee
A.K. Chapagain and A.Y. Hoekstra – August 2003
The water needed to have the Dutch drink tea
A.K. Chapagain and A.Y. Hoekstra – August 2003
Water footprints of nations, Volume 1: Main Report, Volume 2: AppendicesA.K. Chapagain and A.Y. Hoekstra – November 2004
Saving water through global trade
A.K. Chapagain, A.Y. Hoekstra and H.H.G. Savenije – September 2005
The water footprint of cotton consumption
A.K. Chapagain, A.Y. Hoekstra, H.H.G. Savenije and R. Gautam – September 2005
Water as an economic good: the value of pricing and the failure of markets
P. van der Zaag and H.H.G. Savenije – July 2006
The global dimension of water governance: Nine reasons for global arrangements in order to cope with local water problems
A.Y. Hoekstra – July 2006
The water footprints of Morocco and the Netherlands
A.Y. Hoekstra and A.K. Chapagain – July 2006
Water’s vulnerable value in Africa
P. van der Zaag – July 2006
Human appropriation of natural capital: Comparing ecological footprint and water footprint analysis
A.Y. Hoekstra – July 2007
A river basin as a common-pool resource: A case study for the Jaguaribe basin in Brazil
P.R. van Oel, M.S. Krol and A.Y. Hoekstra – July 2007
Strategic importance of green water in international crop trade
M.M. Aldaya, A.Y. Hoekstra and J.A. Allan – March 2008

26. Global water governance: Conceptual design of global institutional arrangements
M.P. Verkerk, A.Y. Hoekstra and P.W. Gerbens-Leenes – March 2008
27. Business water footprint accounting: A tool to assess how production of goods and services impact on freshwater
resources worldwide
P.W. Gerbens-Leenes and A.Y. Hoekstra – March 2008
28. Water neutral: reducing and offsetting the impacts of water footprints
A.Y. Hoekstra – March 2008
29. Water footprint of bio-energy and other primary energy carriers
P.W. Gerbens-Leenes, A.Y. Hoekstra and Th.H. van der Meer – March 2008
30. Food consumption patterns and their effect on water requirement in China
J. Liu and H.H.G. Savenije – March 2008
31. Going against the flow: A critical analysis of virtual water trade in the context of India’s National River Linking
Programme
S. Verma, D.A. Kampman, P. van der Zaag and A.Y. Hoekstra – March 2008
32. The water footprint of India
D.A. Kampman, A.Y. Hoekstra and M.S. Krol – May 2008
33. The external water footprint of the Netherlands: Quantification and impact assessment
P.R. van Oel, M.M. Mekonnen and A.Y. Hoekstra – May 2008
34. The water footprint of bio-energy: Global water use for bio-ethanol, bio-diesel, heat and electricity
P.W. Gerbens-Leenes, A.Y. Hoekstra and Th.H. van der Meer – August 2008
35. Water footprint analysis for the Guadiana river basin
M.M. Aldaya and M.R. Llamas – November 2008
36. The water needed to have Italians eat pasta and pizza
M.M. Aldaya and A.Y. Hoekstra – May 2009
37. The water footprint of Indonesian provinces related to the consumption of crop products
F. Bulsink, A.Y. Hoekstra and M.J. Booij – May 2009
38. The water footprint of sweeteners and bio-ethanol from sugar cane, sugar beet and maize
P.W. Gerbens-Leenes and A.Y. Hoekstra – November 2009
39. A pilot in corporate water footprint accounting and impact assessment: The water footprint of a sugar-containing
carbonated beverage
A.E. Ercin, M.M. Aldaya and A.Y. Hoekstra – November 2009
40. The blue, green and grey water footprint of rice from both a production and consumption perspective
A.K. Chapagain and A.Y. Hoekstra – March 2010
41. Water footprint of cotton, wheat and rice production in Central Asia
M.M. Aldaya, G. Muñoz and A.Y. Hoekstra – March 2010
42. A global and high-resolution assessment of the green, blue and grey water footprint of wheat
M.M. Mekonnen and A.Y. Hoekstra – April 2010
43. Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030
A.R. van Lienden, P.W. Gerbens-Leenes, A.Y. Hoekstra and Th.H. van der Meer – April 2010
44. Burning water: The water footprint of biofuel-based transport
P.W. Gerbens-Leenes and A.Y. Hoekstra – June 2010
45. Mitigating the water footprint of export cut flowers from the Lake Naivasha Basin, Kenya
M.M. Mekonnen and A.Y. Hoekstra – June 2010
46. The green and blue water footprint of paper products: methodological considerations and quantification
P.R. van Oel and A.Y. Hoekstra – July 2010
47. The green, blue and grey water footprint of crops and derived crop products
M.M. Mekonnen and A.Y. Hoekstra – December 2010
48. The green, blue and grey water footprint of farm animals and animal products
M.M. Mekonnen and A.Y. Hoekstra – December 2010

Reports can be downloaded from:www.waterfootprint.org
www.unesco-ihe.org/value-of-water-research-report-series

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