COMMERCIAL BROILER

PRODUCTION

'h

Agriculture Handbook No. 320

Ü.S.DEPr.OFÄGRfCüLTüRE

NATIONAL AGRICULTURAL LIBRARY

MAR 15 1967

CURRENT SERIAL RECORDS

Agricultural Research Service

UMTED STATES DEPARTMENT OF AGRICULTURE
GOOD MANAGEMENT PRACTICES IN RAISING MEAT BIRDS

(1) Start with quality chicks; get healthy chicks from National Plan hatcheries

or other reliable sources.

(2) 'Have chicks of only one age on farm at any time.

(3) Debeak chicks when necessary.

(4) Clean quarters before housing birds and keep houses and equipment clean.

(5) Keep litter clean, dry, and free from mold.

(6) Brood birds carefully; have good sanitary management in brooder house.

(7) Supply adequate heat and ventilation.

( 8 ) Provide enough floor space.

(9) Give adequate space for feed and water; have feed delivery to bin outside

house.

(10) Use all-night lights.

(11) Adapt vaccination schedule to local needs.

(12) Watch for disease; get prompt diagnosis when disease occurs; remove

diseased birds from flock.

(13) Dispose of dead birds promptly; have satisfactory disposal facilities.

(14) Keep visitors out of houses; lock doors.

Trade names are used in this publication solely to provide specific information. Mention of

a trade name does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not signify that the product is approved to the exclusion of other comparable

products.
COMMERCIAL^KOILER

^PRODUCTIONS /

í<^

^^y^AYMOfiD Tl PARKHVRST^

Agricultural Research Service /

UMTEß^ STATES DEPARTMENT OF AGRICULTURE/^

Washington^.C. Issued February 1967^

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.O., 20402 - Price 40 cents
Contents

Page

Good management practices in raising

meat birds Inside front cover

Current trends in broiler raising 1

Production centers 1

Growth of the broiler industry 1

Integration 2

Financing 3

Contracts 4

Cost of production 6

General guide 6

Baby chick cost 6

Grower payment costs 7

Labor cost 7

Grower fixed or housing costs 7 ^

Litter cost 8

Selection of stock 8

Straight-run versus sexed chicks 8

Breeding methods 8

Growth and feed efficiency 9

Feathering 9

Breast development 10

Shank pigmentation 11

Diseases (general) 11

Leukosis 11

Nutrients L 11

Plumage color 11

Egg size 12

Housing 12

Location 12

Requirements 12

Types of houses 13

Controlled envii;^nment 15

Housing costs 16

Brooding 17

Brooding systems 17

Environmental factors 18

Hot-weather problems 19

Litter 20

Preparation of house and brooder 20

Lights 21

Floor space 21

Size of units 22

Waterers and watering space 22

Chick guards and other management practices 22

Debeaking 23

Feeders and feeder space 23

Management practices 25

Size of operation 25

Labor efficiency . 25

Stress factors 25

Page

Grower supervision 25

General sanitation 26

Security management 26

Disinfection 26

Parasite control 27

Chicken-meat production 27

Cornish game hen 27

Broilers and small roasters 27

Large roasters and capons 28

Breast blisters (sternal bursitis) 28

Marketing 28

Feeds and feeding methods 28

Importance of a good broiler ration 29

Factors to consider in a broiler ration 29

Feeding programs 32

Nutrient requirements 32

Protein 33

Energy 33

Vitamins 33

Vitamin A 34

Vitamin D 34

Vitamin E 34

Vitamin K 34

Riboflavin 35

Pantothenic acid 35

Niacin 35

Choline 35

Biotin 35

Folacin 35

Vitamin B« 35

Vitamin B^ ^. 35

Thiamine ^-. 35

Unidentified growtà factors 35

Minerals **«•. 36

Calcium -.u^/C: « 36

Phosphorus »^«JM^*- - —«^^^ 36

Sodium --*«.- -«-«^ 36

Manganese --.p. - -*ÍÜ

Iodine •* «-«. SéZinc .^ W

Iron and copper '-..^tm^f^^m,^ lit

Molybdenum and selenium ''i^:^,,.^^.

Magnesium ~*^%-' '

Feed and water consumption 37 '

Ration ingredients 37

Grains 37

Millfeeds 37

Fat 38

Fish oil 38

ii
Page

Animal protein products 38

Fishmeal 38

Condensed fish solubles 38

Meat scrap 38

Crabmeal 38

Feathermeal 38

Poultry byproduct meal . 38

Vegetable protein sources 39

Soybean meal ^ 39

Cottonseed meal 39

Corn gluten meal 39

Sources of natural vitamins and unidentified

growth factors 39

Distillers' dried solubles 39

Fermentation products 39

Alfalfa meal 39

Dried whey 39

Antioxidants 39

Coccidiostats 39

Antibiotics 40

Antibiotic potentiation 40

Arsenicals __; 41

Hormones 41

Xanthophyll 41

Miscellaneous additives 41

Ration formulation 41

Factors affecting feathering 44

Linear programing : 44

Concentrates and premixes 45

Broiler feeds 46

Feed preparation and distribution 47

Judging feed value 47

Marketing 47

Marketing cycle 47

Marketing areas and practices 48

Page

Standards and grades 49

Classes 50

Condemnations 50

Diseases 50

PuUorum and fowl typhoid 50

Omphalitis , 50

Epidemic tremor (avian encephalomyelitis) 51

Crazy chick disease (encephalomalacia) 51

Rickets 51

Curled-toe paralysis (riboflavin deficiency) 51

Slipped tendons (perosis) 51

Nutritional roup (vitamin A deficiency) _. 51

Coccidiosis ', 51

Cecal coccidiosis 51

Intestinal coccidiosis 51

Nonspecific enteritis 52

Avian nephrosis (Gumboro disease) 52

Hemorrhagic anemia syndrome 52

Gizzard erosion 52

Moldy-feed toxicosis 52

Aspergillosis 53

Leukosis and Marek's disease , 53

Infectious bronchitis 53

Newcastle disease (pneumoencephalitis) 53

Laryngotracheitis 53

Colibacillosis (E. coli infections) 54

Chronic respiratory disease 54

Synovitis (infectious synovitis) 55

Fowl pox 55

Vaccination 55

Other conditions causing disease and mortality __ 56

Barebacks and cannibalism 56

Mites, lice, and ticks 56

Rats and mice 56

Management guide Inside back cover

Tables

Page

Effect of feed conversion on income 30

Feed cost of prodiii^ing a pound of live broiler 30

T^î?'*c^t ^¿)f'feed conversion on value of feed 31

Approximate feed and water consumption . 37

Analysis of ingredients 43

Typical nutrient specifications 46

Typical ingredient restrictions 46

Broiler starter and finisher rations 46

iÛ

This handbook supersedes Agriculture Handbook 151, Broiler Feeding.
CAUTION

Feed Additives—When a medicated feed is used, follow the manufacturer's directions exactly. Directions on the label or feed tag are based on U.S. Food and Drug

Administration regulations governing the use of a medicated feed, its withdrawal,

and replacement with a nonmedicated feed. (See reference in footnote 1, p. 40.)

Poisons for Controlling Rats and Mice—All poisons are dangerous and can kill

small animals and pets if used carelessly. Anticoagulant rat poisons—warfarin,

pival, fumarin, and Diphacinone—are safe when used according to the manufacturer's instructions. They may be purchased as powdered concentrates for dry

baits or in water-soluble form. Follow all directions and heed all precautions on

the label.

Insecticides—Insecticides are poisonous; use them with care. Follow all directions and heed all precautions on container labels. Do not contaminate feed and

water with insecticides.

•1
COMMERCIAL BROILER PRODUCTION

By RAYMOND T. PARKHURST, Director, South Central Poultry Research Laboratory,

Agricultural Research Service

Commercial broiler production is a highly specialized farm enterprise. In 1952, the annual

production of commercial broilers exceeded that

of farm chickens, including hens that were byproducts of egg production. The total output

has increased from 34 million broilers in 1934 to

over 2,300 million in 1965. Except for small decreases in 1944 and 1946, the annual output of

broilers has increased each year since 1934. The

average price per pound paid to the producer and

the value of broiler production have fluctuated.

Prices have tended to decline, and the total value

of production has inclined to over $1 billion in

1964.

Commercial broilers are produced at a relatively uniform rate the year around. More are

raised to meet the greater demand in the summer

because of more outdoor cooking and fewer during the winter holidays when more turkey is on

the market. The per capita consumption of

broiler meat has increased rapidly since 1947-48,

as shown in figure 1.

The large-scale production of broilers has developed in concentrated areas. The first such

area was probably the Delmarva Peninsula, which

includes all of Delaware and parts of Maryland

and Virginia on the Eastern Shore of Chesapeake

Bay. Virginia also has several sizable producing

areas. Georgia has recently been the largest producing State. Other concentrated areas of output are in Arkansas, Alabama, North Carolina,

Mississippi, Texas, Maine, and California. The

southeastern and south-central regions have had

the greatest increases in recent years, as shown

in figure 2.

CURRENT TRENDS IN BROILER RAISING

Production Centers

The center of broiler production has moved in

recent years from the eastern seaboard—the Delmarva Peninsula, Maine, and Connecticut—to

the Southeastern States of Georgia and North

Carolina and the South Central States of Arkansas, Alabama, Mississippi, and Texas. In 1964,

the 10 leading States in broiler production produced 1,800 million birds, or 84 percent of all the

broilers in the Nation. Area competition is primarily dependent on production and transportation costs of processed broiler«.

^

"^Growth of the Broiler Industry

For several years and especially from 1955 to

1962, the cost of producing and marketing broilers has had a downward trend. Although prices

have also been less nearly every year, producers

have offered increasing supplies. The cost reduction has been due to many factors. Advances

have been made in nutrition, breeding, management, and in the prevention and control of diseases. The improvement in feed efficiency has

been the most important factor in reducing the

total cost per pound of the broiler. Radical

changes have been made in the way the broiler

enterprise has been financed and organized. Live

birds have been more accessible to processing

plants. The availability of high-quality birds in

a convenient form and at reasonable prices for the

consumer has enhanced the demand. Population

and take-home pay have increased. The volume

of output has become more constant throughout

the year.

Competition has been intense in the broiler industry, forcing many firms and their producers

out of business. Firms with more profitable margins have usually taken up the slack caused by the

closing of less efficient firms. Lack of availability

of credit has at times slowed the expansion rate.

On the other hand, the trend has been for more

broilers to be raised per farm. Broiler raisers

have increased the size of their houses and have

installed labor-saving equipment to care for more

birds. Labor cost per bird has been lowered.

Commercial broiler production may be a fulltime enterprise, part-time with some industrial

pursuit, or combined with farming operations,

such as the production of corn, cotton, soybeans,

hay, or beef cattle. Many broiler growers do not

depend entirely on the income from their

chickens.

The ability of the grower can be an important

factor in the growth of an individual enterprise.
AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

CONSUMPTION OF CHICKEN MEAT

1935 1940 1945 1950 1955 1960 1965

4tREADY'TO'CO0K BASIS. A7965 PRELIM^INARY.

^INCLUDES ALLOWANCE FOR BACKYARD CHICKENS THROUGH 1963.

BN-27934

FIGURE 1.—Consumption of commercial broilers and farm chickens, 1935-65. Note rapid and almost complete replacement of farm chickens by broilers.

His decisions as to heat, ventilation, feeding, disease control, and similar matters, even under the

supervision of service personnel, can materially

affect results.

The competition for labor can be a very important factor in the growth of broiler production in an area. If broiler growers have no alternative, they will probably continue to operate

when prices are depressed and income is low.

However, when industries offer an alternative

revenue, the wage offered, the relative "pleasantness" of the jobs, the time of year, the duration

of the job, and the skill and responsibility required all become factors. In the South, historically, there have been fewer agricultural alternatives and less industrial demand for labor.

Integration

Poultry-meat production has passed through

several stages of development. Originally meat

production was a byproduct of egg production,

and much of the poultry meat was from milkfattened roasters from the Middle West and the

South Shore of Massachusetts. There was some

specialization of production close to the eastern

markets, where premium prices were paid for

small broilers and "South Shore" roasters. Most

of the early commercial broiler production was by

independent growers. They paid cash for everything and took all the profit. As margins became

smaller, flocks became larger, and soon the feed

dealer became the source of credit. As the industry grew, the feed dealers began to depend

on the feed manufacturers as a source of funds.

To spread their risk, both feed dealers and feed

manufacturers integrated vertically with hatcheries aiid processors. This was the start of many

forms of integratibnT

Integration may include one df"'inere..i>hases,

such as financing, feed, hatching, breeder ^pck,

production, processing, and retail marketing. îî^.

most cases, the primary production of breeJApJ"

stock and retailing have not been included. IV^^

companies may be involved in a single operatM»,

such as processing, or a single corporation JMiy

encompass all the phases. Some corporationi mn

publicly financed, and their operations oft^^-

clude most of the phases enumerated abo\|k

Several forms of integration apply to t^rilir

production. Horizontal integration is the tm*

bining of firms in the same stage of prodiwgtóaB.

It may result in better control of productiç^ liWÎ

increased efficiency. For example, many lud
COMMERCIAL BROILER PRODUCTION

COMMERCIAL BROILERS PRODUCED, U.S.A.

(In Thousands)

1934 1,600 1,500

^=i=i;;=i=i=;ii=!i!=;i;iii!jii=58^i;!:^ 34,030

1945

4.7% 4.4%

24,944

51,060

14%

'I I I I I I I

::::::=:=:: 149,745 :=::::::::::::::::::::

;^:i:;;iii;i:i:i:;:i41%:;:' 365,572

1955

475,483::::::::::=::::::::::: ,««,,„.

:Í43.5%:i:iiiii:Í:ÍiÍi=:::::Í: ''091,684

1965

m ; 653,695

128%

773,079^

1.i.1.1 i lililí

;::: 603,879 ;:::::

^33.1%^^^:;:;:;:;:;: 25.9%!:;:;:;;^ 2,332,589

DEL., MD.,& VA. ^ N.C., S.C.,& GA. ^ ALA., MISS., 4 ARK. EID ALL OTHER

FIGURE 2.—Commercial broilers produced in selected areas, 1934-65.

BN-27935

companies have merged. Vertical integration is

the control by a single management of two or

more stages of production. It is said to be backward when it undertakes to maintain access to

materials. For example, processors may wish to

assure a supply of birds in order to get as near

full capacity as possible. They may contract with

growers when supplies are limited. Forward integration usually has the maintenance of the market position as its purpose. Feed manufacturers

have integrated to try to hold their volume. They

are strong factors in production and, in some

cases, include all phases of integration except

retailing.

Ownership integration is one brought about by

merger or by expansion of a firm. Contract integration coordinates nominally independent enterprises by a system of contracts. Probably 95 percent of the broilers are grown under some type

of vertical integration or contractual arrangement. This is due primarily to capital and credit

requirements, reduced unit costs, improved quality, better alinement of output with other stages,

especially processing, and reduced operation uncertainties as to capital inputs and market outlets.

Because of the larger volume base, better management and service, more research, and easier

maneuverability of sales are possible. An integrated business can be more effective if it is more

efficient.

Financing

The methods of financing the poultry industry

undoubtedly contribute to its principal problemlow prices and marginal returns.

Few growers are still able to continue as independent operators. Throughout the broiler industry the amount of integration has increased.

One of the principal reasons for this trend has

been the increasing need for more financing. Because operators tend to be more responsible financially, more liberal credit has been extended to

integrated operations or to those persons who

have, in their normal iDusiness activities, used

considerable credit. Feed manufacturers are an

example of this group.

Local banks, their correspondent city banks,

and the Production Credit Association largely

finance the broiler industry through credit extended to feed manufacturers, dressing-plant

processors, hatcherymen, and integrated operations. Much of this money is loaned at the local

level to growers with mortgages as collateral.

Some of the larger cooperatives get their money

through the Bank of Cooperatives, especially for

processing and other marketing purposes. Much
AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

of the money for broiler-house construction has

come through the Federal Land Bank Association, the Production Credit Association, and individuals. The loans are usually payable over a

5- to 20-year period and are secured by mortgages.

The Farmers Home Administration makes loans

for the development and operation of broiler production on farms no larger than family farms.

Established broiler producers may obtain credit

to continue or to make needed adjustments in

their broiler operations. FHA, however, only

finances the establishment of broiler enterprises

on a limited scale. Insurance companies also

make mortgage loans in some areas.

One of the reasons for the rapid expansion of

the poultry industry in the South has been that

financing is easier there. A dollar goes farther,

especially in poultry-house construction. More

capital has been available to invest in poultry

enterprises there.

Contracts

Good contracts state terms concisely and divide

fairly the responsibilities of the grower and management, or the company with whom he has a

contract. Most broiler growers are concerned

with two major risks, which generally make them

either unable or unwilling to finance their own

broiler operations. The first is the risk of unusually high mortality and the second is that of unusually low market prices or sometimes a lack of

a satisfactory market for their birds.

In most contracts the firm supplies the baby

chicks, retains ownership of the broilers, assumes

responsibility for marketing the birds, and

promptly pays the grower. The firm also supplies feed, supervision, medicine, vaccines, and

disinfectants. It assumes most cash losses. The

grower supplies labor, housing, equipment, fuel,

litter, and miscellaneous items.

The out-of-pocket purchases of the grower are

usually low. However, his costs should be taken

into consideration. They include repairs, depreciation, taxes, interest, and insurance. Repairs are a part of the cost of trying to stay in

business. The grower must get back the cost of

depreciation or he is out of business when his

houses and equipment are beyond repair. The

grower is usually taxed on everything he owns,

including land, houses, and equipment. Insurance is a justifiable protection against losses that

might wipe him out. He is responsible for personal injuries. The grower gets the manure

produced.

There are many kinds of production contracts.

Most contracts guarantee the grower at least

something for the use of his houses and equipment and for electricity, water, and minor cash

outlays. When prices are depressed, growers

may receive little or no return for their labor.

In general, growers with inadequate housing and

equipment, poorer-than-average feed conversions,

high mortality, or poor condemnation records find

it increasingly difficult to get contracts when

weather is adverse, output is curtailed, or broiler

prices are depressed. In recent years, this has

been around Thanksgiving and Christmas. To

obtain maximum returns, producers need to make

full and continuous use of their facilities and

labor. Contractual arrangements are very

important.

Production operations are financed in many

ways, such as open account, no loss, share, flat

fee, labor, and feed conversion. With the openaccount plan, the grower buys his feed, chicks,

medicine, vaccines, and other supplies from the

dealer, who takes a chattel mortgage on the birds.

The dealer supervises the operation, does the selling, collects payments, and credits the grower's

account. The dealer does not assume the production or price risks.

The guaranteed no-loss plan is similar to the

open-account plan except that should the income

be less than the credits extended, the dealer absorbs the loss and closes the account. The grower

loses his labor and the; returns on the use of his

house and equipment. He, of course, directly or

indirectly, pays for th0 guarantee against loss.

The share contract was used extensively in the

eastern broiler-growing areas. The feed dealer

usually furnished the feed, chicks, medicine, fuel,

litter, and other produ(îtion items, charging them

to the grower's accounjt. The grower furnished

the broiler house, equipment, and labor necessary

to grow the birds to marketable age. The dealer

retained title to the birds and made the decision

on marketing. After iieducting the charges for

feed, chicks, and other ¡supplies from the net proceeds from the broilers| sold, the dealer retained a

share of the remaining I proceeds and remitted the

rest to the grower. The share varied from 90-10

(90 percent to the grower and 10 percent to the

dealer) to 50-50. If the proceeds were less than

the charges, the dealerj stood the loss, except for

his markup. The gro^j^er received no return for

his labor or for the ^se of his buildings and

equipment. Other types of contracts replaced

the share contract becatise of the unwillingness of

growers to take the risks involved and because

of the growth of the efficiency-type contracts.

Another share-type jcontract was used extensively during the perioji when broiler prices were

depressed and integratibn was spreading. In this

contract, feed was charged at ingredient cost, and

the hatchery received |a minimum agreed price

for its chicks. The grower, hatchery, and feed

mill divided the profiis 38, 25, and 37 percent,

respectively. Operatoi?s of the feed mill and

hatchery assumed lossfes at 60 and 40 percent,
COMMERCIAL BROILER PRODUCTION

respectively. The grower, in case of a loss, received nothing for that lot of broilers. However,

he usually received more per 1,000 broilers when

the selling price was relatively favorable than

under a guaranteed no-loss or the share-the-profit

contract.

Under the flat-fee contract, the dealer furnishes

the chicks, feed, medicine, vaccines, and other

production items and does the selling. The producer furnishes the house, equipment, and labor.

The dealer retains title to the birds and pays the

grower a guaranteed minimum per chick placed

per week or per pound of broiler marketed. The

latter is generally considered preferable because

of a direct reward for low mortality.

Another form of this contract provides that

the minimum payment drops when the price per

pound of broiler sold drops below a certain price.

For example, the contract payment may drop

from 2 to 11/2 cents per pound of broiler sold

when the price per pound of broiler sold goes

below 15 cents per pound.

The labor contract is similar to the flat-fee contract, except that the grower is paid a fixed wage

by the dealer, usually on a weekly basis. The

plan may be used when houses are leased.

There are several types of "efficiency" contracts,

and the trend is toward their use. Basically the

grower gets a percentage of what he saves the

managenient. This type of contract provides the

grower with an incentive to practice good management. The management retains title to the

broilers, supplies all production items, supervises

production, markets the broilers, and assumes the

loss responsibility. The grower furnishes houses,

equipment, fuel, electricity, and water.

One contract pays a fixed price per pound of

broiler sold with an increase or a decrease in the

base rate depending on the feed conversion of

each batch. For example, the grower may have

a guarantee of a cent per pound. Market price

is not a factor. The grower is paid 0.1 cent per

pound for each 0.1 pound below 2.5-pound feed

conversion and the same, 0.1 cent per pound, for

each 0.1 pound above a 3.0-pound average weight

and for each 0.5-percent mortality below 4-percent

mortality.

Modifications are based on "point spread" or

the "production efficiency" index. The point

spread, described in detail on page 29, is the relationship between the feed-conversion ratio and

the live weight of the birds at the time of marketing. An average weight of 3.33 pounds and a

feed conversion of 2.50 gives an 83-point spread.

These relationships may also be expressed as the

production efficiency index by dividing the live

weight by the feed-conversion ratio. For example, the index for the weight and conversion above

would be 1.33 (3.33-^2.50).

Another contract pays an agreed amount per

1,000 chickens started. A payment is made on a

feed-conversion factor, a differential according to

the selling price, or both; point spread; or cost

of production. No perfect contract has been devised to take care of all conditions. Some of the

variations in the contracts concern fuel cost, distribution of profits, floor space allowed per chick

started, allowance for putting insulation or central heating in the houses, penalties for condemnation losses, extra allowance for cost of fuel during colder-than-average periods, cost of disinfectants and of applying them, cost of litter, cost of

cleaning out houses, and cost of catching and

hauling birds to market.

In most broiler areas, the condemnation losses

are charged to the growers. Some operators give

a fuel allowance to the grower when the weather

is more severe than usual. This tendsto increase

feed conversion and reduce mortality and condemnation losses. Growers who have or put in insulation in an approved way are usually given an

allowance to help reimburse them for it, if they

are not paying the fuel bill.

Contracts vary with different dealers and integrators. They may combine features of various

types. Company-owned broiler farms result primarily when it is not possible to get growers with

either adequate houses or managerial ability.

Managers of company-owned farms often are

supplied a house, are assured a minimum income,

and then are paid a bonus for doing a better-thanaverage job. Farms may be owned or leased by

the company. There are several reasons for

control by either ownership or leasing. The principal one is that contractors have the responsibility for production, but insufficient authority over

producers to match their responsibility. Some of

the advantages of expansion by leasing over ownership as far as integrators are concerned are the

lowered fixed costs that are direct business expense, conservation of capital, better utilization

of labor between farm and nonfarm work, and

tax advantages. In some cases, the grower, in

addition to leasing his houses, also works for the

integrator or contractor on a fixed salary or labor

contract.

Cost-of-production contracts are being used to

reward those growers who get good feed efficiency and use enough, but not too much, fuel

and medication. The many different types of

these contracts include a guarantee payment per

1,000 birds and a payment of an added bonus

per pound to the grower for profit over the

break-even point and a reduction of the same

amount for a loss below the break-even point.

Another type predicts an average cost for the

period during which the birds are to be sold,

and payments to the grower vary above or below

the average. The grower and the contractor

split the profits, if any, above basic production
AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

costs and payments made to the grower. In

another type, the contractor averages the cost

during the week, month, or quarter for all

growers and pays a bonus to the best growers.

Less efficient growers get something, but usually

have difficulty renewing their contracts.

By its survival, contracting in one form or

another has demonstrated that it is a more satisfactory system than any alternative that has

been mutually acceptable to participating parties.

Contracting is firmly established in the broiler

industry. Most broiler growers will not finance

their operations independently even when they

can. The extent to which the grower under the

contracting system loses his independence to a

considerable extent depends on his attitude and

that of his family. Servicemen, representing

management on the farm, welcome the opportunity to turn over responsibility to the grower.

When the grower and his family prove themselves capable of making the day-to-day decisions, they will usually have the opportunity to

do so. In contract farming they have a new

variation of the traditional system of family

farming.

The type of contract that exists between the

hatchery and the producer of hatching eggs has

an important bearing on the wide fluctuation in

broiler prices. The industry could adopt a

policy of compensating the producer during those

periods when it is necessary and advisable to

reduce or stop setting eggs. An average-volume

guarantee is sometimes used to assure hatching

eggs when wanted, yet cut off supplies when

not needed.

COST OF PRODUCTION

General Guide

The cost of producing broilers varies with

every batch. As a guide, the percentage of each

item, other than grower payments (labor and

overhead), to be considered in the cost of producing broilers is approximately as follows:

Item Percent

Feed 71.00

Chicks 21.80

Fuel 2.25

Medication 1.8

Vaccination 1.35

Litter .9

MisceUaneous -9

When contract payments are included in the

costs, the percentages are approximately as

follows :

Item Percent

Feed 62.4

Chicks 19.2

Grower payments 12.0

Fuel 2.0

Medication 1-6

Vaccination 1-2

Litter -8

Miscellaneous -^

Feed is the largest cost item. Feed and chick

costs represent 80 to 90 percent of the total cost.

For information on cost of labor and on economical feeding, including cost of production

and how to calculate it, see pages 7 and 29-32.

Some variation in grower costs, even within

a single enterprise, is due to different ways of

doing the same job. When the result is a difference in weights, feed conversion, or mortality,

the cost is materially affected. It is often possible for an individual broiler grower to improve

his efficiency. For information on labor efficiency, see page 7.

The usual objective is to lower production

costs to give greater profits. Production costs

generally are lowered if one combines all the

improvement possibly in the breeding of the

broiler stocks used, nutrition and feeding, prevention and control of disease, and management,

including environmental control. This requires

close cooperation between the operator, the service supervisor, and the grower. If there is

friction or a lack of confidence between the supervisor and the grower, optimum results rarely are

obtained.

Baby Chick Cost

The cost of baby chicks has been reduced

because of improved hatchability. Most of the

reduction has been due to the decreasing costs

in hatching as hatchery size increased and fuller

use has been made of facilities. The trend,

especially since 1955, has been to fewer but

larger hatcheries. The total production has increased enormously. The relatively stable yearround demand for broiler chicks has resulted in

greater use of facilities. With integration, a

much better balance has existed between hatchery

capacity and the needs of production and marketing. As hatchery size increased, reductions

resulted on a per chick basis in in-plant labor,

cost of utilities, and overall cost of the hatchery

building. The labor costs were substantially

reduced. The inefficiently operated hatchery will

probably not survive when its cost of producing

chicks is too high.

The major factors in baby chick expense are

egg cost and hatchability. A 10-cent difference

in the cost of a dozen hatching eggs will change
COMMERCIAL BROILER PRODUCTION 7

the chick cost about 1 and 1.25 cents at 84- and Grower Fixed or Housins Costs

70-percent hatchability, respectively. At 50 cents

per dozen eggs, a drop from 84 to 70 percent in The amount of fixed costs per unit (square

hatchability will increase the chick cost 1 cent. foot or broiler) will depend on the amount of

At 70 cents per dozen, the cost per chick goes money invested in land, buildings, and equipup about 1.33 cents. In integrated operations ment; the assumed rate of depreciation; and the

especially, these factors become very important. expenditures for taxes, interest due on borrowed

capital, repairs, and insurance on buildings and

r^^w*.». Pa^tnr^i^int T^et« cquipmcut. The only other direct costs are probGrower Fayment Costs ^bly hired labor and cash outlays for electricity,

It is estimated that about 12 percent of the ^^^^^' and possibly land rental,

total cost of producing a broiler is the payment ^ l^epreciation on buildmgs is usually figured at

to the grower for his labor, the use of his house ^ percent, or 20 years, and on equipment at 10

and equipment, electricity, water, and minor cash Percent, or 10 years. Interest is charged at 6 perpurchases. In an efficient operation, about 5 to 9^^^ t^"^ buildings and equipment at the level of

6 percent will be housing and equipment charges investment. Kepairs amount to II/2 percent on

and 6 to 7 percent will be labor. i '^^'''^^ and 2 percent on equipment. Taxes on

land and building and insurance on buildings

and equipment are charged at three-fourths perLabor Cost cent of the level of investment. The level of

T 1 ^1. I. 4.^ ^i, 1 • j • investment will depend on the age of the build- in general, the better the housing ings or equipment. When not known, it is

?^n!^'u\^''^^ï ^}^J^^'''',Î''^\ The labor per assumed to be one-half percent. For example,

1,000 broilers started should not exceed 31 mm- annual interest is figured at 3 percent for buildutes per day, and with automatic equipment, i^gs and equipment and is equivalent to 6 percent

should not exceed 18 minutes per day. The ^^ ^Q^^^J investment

hours per 1,000 per brood should not exceed 17 Assuming investment cost in the house of $1

without or 9 with automatic equipment. This per square foot, the cost per broiler capacity at

IS based on a 66-day growing period and, of 0.8 square foot allotted per bird is 80 cents,

course, would vary for different length periods. The annual fixed costs in cents per square foot,

A family unit on a full-time basis should based on $1 per square foot, are as follows:

care for at least 36,000 broilers, preferably 45,000.

It would be necessary to have mechanical feeders Cents per

and waterers. Eight hours would be required ^^^^^ square foot

daily during the brooding period^feeding and fSst 3 m

watering approximately 3 hours each, brooding Repairs I__I I__I__ __ "_I~""III"II 150

1/2 hour, and flock inspection, regulating ventila- Taxes Z__II__I__I I__ .75

tion, management of litter, and other miscellane- Insurance .75

ous chores li/^ hours. After the brooding period, "^^^^^ H-OO

about 6l^ hours daily would be required—feed- /T?^^ i.^,,«;« ^ • x i. ^/. #

ing 4, watering 1, and miscellaneous tasks U/o ilZ}'''^!'^ ^""î equipment costs, see p 16; of

hours. If mechanical feeders were not used and ^^"^^' ^^^f. "^f ^^^.^e half or double the

round hanging feeders were utilized, almost If'^Z ^^<^f^î^ ^^^^-^ Assuming 25 cents

twice as long would be required to feed 36,000 P^f.-'^tl^ *°°^ *7 equipment including autobroilers, and some hired help probably would be "^Sfi. f '''' waterers the annual fixed

needed. Usually hired help would be required '^^«^^ ^^ ^«"^^ P^^ ^1"^^« i«<>t are as follows:

only to clean out and to repair houses and Cents per

equipment. item square foot

Contract farming is normally a family affair. Depreciation 2.50

The wife and children help, especially during R^pafrs ""III *50

the first 2 weeks. The trend is to large-scale, Insurance "II"I"rmiI"I"I"mZIIZZmm .25

full-time operations and away from part-time Total ¿00

production. When there is surplus labor, laborsaving equipment must be considered only in ^^.^^ ^^^ ^P^^l annual fixed cost for housing and

terms of reducing fatigue and drudgery in cer- ^quipment is 15 cents per square foot, the annual

. • • 1 j X ü 5 • X p j ^- nxed cost per 1,000 broilers at 0.8-SQuare foot

tam jobs and not of reducing cost of production. ^^^^. is f 120 ' (0.8X0.15x1,000). With four

A grower can calculate his labor income fairly flecks per year, the cost is $30 per 1,000-bird

accurately if he knows his ownership costs and flock, or 3 cents per bird. At 3.3 pounds per

subtracts his fixed costs from his minimum con- broiler, the total fixed cost per pound is 0.91 cent

tract guarantee. (3.0-Í-3.3).
8 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

If a grower has a fixed cost of 0.91 cent per

pound and is paid 2 cents per pound as a minimum base, his return for labor is 1.09 cents per

pound. At 3.3 pounds, the labor return is 3.6

cents (1.09x3.3) per broiler. For four nocks

per year, the basic labor income would be $144

per 1,000 ((4X3.6X1,000)-^100). The amount

of labor income a grower receives is affected by

the fixed costs per unit (pound or broiler), what

he is guaranteed per unit in his contract, how

many units he produces ( nocks X broilers per

flock), and what he has in his contract as bonuses

or discounts based on performance, selling price,

or both.

In the example given here, the grower payment should be at least $66 per 1,000 broilers

((120+144)-^4). However, minimum grower

payments may vary from $50 to $75 per 1,000

started or from 1 to 2.25 cents per pound of live

broilers marketed. Contract payments vary considerably, but are usually about 1.7 to 2 cents

per pound.

Depreciation can vary with the quality of

the house and equipment. Some houses are

built to last 20 and others 10 years. If of poor quality or not given proper care, they will last only 5

years. The interest charges vary with the risk

involved and the various sections of the country.

The personal property tax varies a great deal

because of differences in assessed valuation and

local tax levy. Some of the factors affecting

repair and insurance expenditures that the

grower will make on buildings and equipment

are his anticipated earning power (his age),

especially how near he is to retirement, and the

amount of mortgage, if any. With a diminishing level of income, the expenditures for these

items are reduced or postponed. New buildings and equipment will require less maintenance.

Miscellaneous expenses include cost of electricity ^

and water supply.

Some of the most important factors affecting

grower costs are the number of flocks per year, «

the time between batches, and the type of housing and equipment used. Fixed costs become - higher per broiler when only two or three batches ^

are raised in a year or the houses are not filled

to capacity. The time between batches will ^

depend, in addition to other factors, on the number of times per year the house is cleaned out

and the method used. Inefficient methods of

cleaning between batches can markedly increase

the cost of production. The broiler house should

be designed for easy cleaning (see p. 13).

Litter Cost

The cleaning out of the house can vary in

cost. The value of the litter must be determined

on an individual project basis. When the broiler

project is part of a farming enterprise, the

litter can be valuable. In some cases, old litter

is given to whoever will clean out the house and

refill it with clean litter. Sometimes nobody

wants it. The cost of removal also varies depending on the method used, such as shoveling

by hand into a wheelbarrow or wagon or scoop

loading into a manure spreader. For further

information, see page 20.

SELECTION OF STOCK

Straight-Run Versus Sexed Chicks

Straight-run chicks are generally used for

raising broilers. Growth rate and feed conversion do not seem to be materially different if the

sexes run together or separately. Cockerels grow

more rapidly and convert their feed more efficiently than pullets and are more profitable to

raise. Being heavier at a given age, there is more

weight over which to spread chick and contract fixed costs. Very little convincing data

are available that the advantages of separating

the sexes, if any, offset the costs involved. Since

the demand has been for only white-feathered

broilers, there has been very little interest in

sex-linked crosses, which facilitate separating

the sexes at hatching time.

Breeding Methods

The science of genetics has been and is being

continuously utilized to improve broiler breeding stock. Hybrid vigor is obtained by systematic matings that may involve crossing of different breeds, different strains of the same breed, or

the crossing of inbred lines. In addition to hybrid vigor, improvement in economic factors often

results from these crosses, provided the mating

includes stocks having superior qualities of genetic origin.

The end product—our modern white, yellowshanked broiler—is often obtained by crossing

the male lines from specialized breeders with

female lines produced likewise by specialists.

Each line may be the result of crossing two

or more strains. The male lines usually have

dominant white feathers and are selected for

rapid growth; meat characteristics, such as

breast width, body depth, live market grade,

and dressing yield; and rapid feathering. The

female line also must have outstanding growth

rate, high hatchability, and good, but not outstanding, production of eggs of desirable size
COMMERCIAL BROILER PRODUCTION

and texture. Considerable attention has been

given recently to additional factors, such as

freedom from Mycoflasma gallisepticum, feed

efficiency, skin texture, skin and shank pigmentation, and, in the case of large broilers, roasters,

and capons, feathering on the breast or absence

of breast blisters.

If male and female lines are produced by

different breeders, as they often are, each line

must, to remain competitive, cross well with

other lines. Progeny test and family selection

have been effective in the development of broiler

lines. The buyer must judge the ability of male

and female lines to cross well, whether the lines

are developed by separate breeders or the same

breeder.

The selection of a commercial broiler stock can

be the determining factor between profit and loss.

Extension poultry specialists and county agricultural agents can provide information that will be

helpful in making the selection. The results obtained by other growers in the area from different

stocks on such factors as growth, feed conversion,

viability, and rate of condemnation should be

considered.

In large broiler operations, a common practice

is to test several stocks on one farm where suitable

facilities are available and careful records are

kept. It is important that the housing, feeding,

and management be uniform for all stocks in

order to obtain a valid comparison of the factors

affecting economic returns—rate of growth,

pounds of chicken per 100 pounds of feed, mortality, and quality of broilers produced. The information will provide a more reliable basis for

the selection of a stock if the tests are repeated

on a second or third farm. The farm or farms

selected for the test should follow production

practices typical of the area.

In intergrated operations, the comparisons may

include such factors as egg production, fertility,

and hatchability of the parent stock. Other considerations are the cost and availability of the

stock and the services provided by the supplier.

Growth and Feed Efficiency

Growth (final broiler weight) behaves genetically as a simple quantitative character. The

demand of the processor for a white bird created

a problem for the geneticist, because the dominant white gene seemed to be linked with some

growth-depressing factor.

There seems to be no advantage in using any

linear measurement over body weight alone.

Growth (9-week weight) has been positively

correlated with other important economic factors,

such as breast width, body depth, and fleshing.

The relationship of Qgg production to broiler

weight at 9 weeks is important. If it is desired

to iinprove &gg production in otherwise desirable meat-type breeding stock, it seems advisable

to make intense selection for growth rate in

stock that is slightly inferior in growth but

much superior in Qgg production. The more

rapidly growing birds are more efficient than

the slower growing birds.

It is known that feed efficiency is inherited.

There is some question whether it is practical

for the commercial broiler breeder to select for

it as a specific factor. It would seem more

practical to assume that selection for rapid rate

of growth at 4 to 6 weeks of age, and possibly

including long shanks, is also selection for high

feed efficiency. Sex-linked genes may be of considerable importance in the expression of both

growth and feed conversion. Since birds selected

as early as 4 to 6 weeks do not always grow as

expected, a further selection is desirable at about

20 weeks and just before they go to the breeding

pens.

Feathering

Processors demand broilers that are uniformly

covered, with feathers. Because the sex-linked

factor for feathering is inherited in such a

simple manner, it is highly improbable that any

reputable strain does not already contain a

large proportion of early-feathering stock.

The method used is to select chicks for fast

feathering at a day old and later to select growing chicks for rapid growth and for superior

meat production. Selection is applied to both

males and females and to the parental stock

producing crossbred broiler chicks.

Selection to obtain breeders that feather rapidly IS most easily accomplished at the time of

hatching. Fast feathering is a sex-linked recessive to slow feathering; hence, when mated

together, male and female breeding birds selected

BN-27933

FIGURE .3.—Fast feathering: Left, wing of chick with

seven primary and seven secondary feather sheaths

all of which are nearly equal in length; right, wing

of another chick with similar development of feather

sheaths.
10 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

BN-27943

FIGURE 4.—Slow feathering: Left, wing of chick with

few primary and secondary feather sheaths; right,

wing of another chick with short primary and no

secondary feather sheaths showing through down.

for fast feathering will produce fast-feathering

chicks.

Kate of feathering can be determined in dayold chicks by the length of the primary and

secondary feather sheaths of the wing and the

number of the secondary feather sheaths. The

chick with the highest rate has well-developed

primaries and secondaries, with six or more

secondaries (fig. 3, left). The next best has

six or more secondaries, which are not so well

developed but are approximately as long as the

primaries (fig. 3, right).

The chick of the slow-feathering type has no

secondaries, or less than six short ones, and no

primaries, or very short ones. Figure 4 illustrates slow-feathering chicks. About 90 percent

of such chicks feather slowly, have no tail-feather

development at 10 days, and small primary and

secondary wing-feather development (fig. 5, left).

Some of them will develop into "barebacks" at

12 weeks of age, and many of them will have a

considerable number of pin-feathers. These are

not good breeders with respect to feathering. In

this group the males, in particular, should not be

used as breeders.

When selection is made of fast-feathering

chicks (fig. 5, right), they should be raised by

themselves, or if this is not feasible, they should

be identified by some means. Wing banding is

considered the best and most permanent means of

identification. If this is not practicable, then the

chicks may be toe-punched, or a pair of scissors

may be used to cut the web between the toes. In

any case, some means should be adopted so that

such chicks can be recognized at a later age.

Breast Development

As the breast meat is the most valued part of

the broiler, this characteristic should be given

considerable attention in any selection and breeding program. Observations of breast developBN-27942

FIGURE 5.—Chicks showing contrasting feather growth:

Left, slow feathering at 10 days of age; right, fast

feathering at same age.

ment should be made when birds are 6 weeks of

age, but may be made when they are from 6 to

12 weeks old. For these observations each bird

should be examined individually and held in a

similar position. A good way is to hold the

chicken by the legs in the left hand, with its head

downward, and with the right hand to examine

the width and length of the breast. By comparisons, the birds can be divided into at least four

grades, as shown in figure 6.

BN-27936

FIGURE 6.—Breast types and grades of birds to be selected as breeding stock for broiler production: A

and B show desirable fullness of breast ; C and D are

poorer types. (Observations made about three-quarters of an inch from edge of keel.)

At this time observations may be made also on

any imperfections of the breastbone or skin, such

as curved and dented breastbones and breast blisters. Any individual with such imperfections
COMMERCIAL BROILER PRODUCTION

should not be used as a breeder. With a little

experience one soon learns to judge accurately the

relative breast development in birds of the same

age.

The different breast grades represent measurements used in poultry meat-production experinients at the Agricultural Kesearch Center, Beltsville. This method of classification permits four

grades—A, B, C, and D. If one wishes further

divisions, grades A+, A, A—, B + , B, B—, and

so on can be used. Only males with A or B

breasts and females with A, B, or C breasts

should be kept for breeders.

One of the best times to select breeding birds

for efficient, rapid growth is at 6 weeks of age,

and it is also an ideal age to observe breast development. As both of these observations may be

made at this time, one handling of the birds is

eliminated.

Shank Pigmentation

Shank pigmentation is inherited. Within the

yellow-skinned varieties there are distinct differences ranging from bright yellow and orange

yellow to green and sometimes bluish shades.

This has not been of sufficient value economically

to justify much consideration. Nutrition and

freedom from parasites and diseases affect pigmentation much more than inheritance.

Diseases (General)

Chickens differ genetically in their ability to

resist invasion by protozoa, bacteria, fungi, viruses, and parasitic worms. It is feasible to

develop strains comparatively resistant to Eimeria tenella coccidium, fowl typhoid, pullorum disease, visceral lymphomatosis, Newcastle disease,

"blue comb," and encephalomalacia. However, it

has not been determined whether it is economically feasible to do so in any case.

When severely exposed to respiratory disease,

the strain cross progeny of good noninbred

strains fared better than their pure parent

strains.

The S6 strain of avian pleuropneumonialike

organisms (PPLO) Mycoplasma gallisepticum^

an agent, or one of the agents, in the air-sac

disease complex or airsaculitis, is present in most

broiler breeders. The ultimate objective is to

eliminate the infectious agent from breeder flocks.

A blood test can be used to detect noninfected

flocks. It has no value in detecting individual

birds, as in the pullorum test. Dipping eggs in

antibiotic solution can help in reducing PPLO

in breeders, but is of questionable value in the

routine treatment of eggs for broiler production.

As airsaculitis is the largest single cause of condemnations, the elimination of PPLO from

11

breeders is very important. Foundation breeders

should assume the responsibility for cleaning up

all their breeder flocks. Both male and female

Imes must be clean. In order to facilitate the development of "clean" flocks, breeders may, with

msignificant genetic loss, relax selection for 8- or

9-week body weight for one generation.

Both broiler breeder replacement and broiler

chicks should be from parent stock free of PPLO.

Therefore, in commercial production of replacement stock, reasonable geographic isolation of

serologically tested negative birds is important.

Special precautions should be taken to see that

management isolation is not disrupted at any

time.

Leukosis

The amount of leukosis in broiler condemnations and total mortality are often masked by conditions such as septicemia and airsaculitis. There

is no practical test by which the infected hen, egg,

or chick can be detected. A hatchery should

not accept eggs from a breeder flock with a high

incidence of leukosis.

The ability of certain strains of birds to resist

the virus that causes visceral lymphomatosis, the

most prevalent form of leukosis, has been shown

to be due to genetic factors. Culling of flocks is

most effective if done on a family basis, and entire

families with individuals showing indications of

the leukosis complex, such as irregular pupils,

marble bone, or other symptoms, should be eliminated. A highly susceptible strain should not be

used for crossing purposes. Since the disease can

also be transmitted by direct contact between

chickens in the same hatching or rearing units,

isolation procedures are essential. There is no

known treatment for leukosis.

Nutrients

The requirement for certain amino acids—

argmine, methionine, but not lysine—is inherited. Genetic differences have also been exhibited

for the A, Bi, D3, E, and riboflavin vitamin factors, the unidentified growth factors, manganese,

calcium, and zinc. Again, selection for rapid

growth normally emphasizes the individuals most

capable of efficiently using these nutrients and

leads to the elimination of those having an abnormally high requirement for them. Basically

any individual with an abnormal requirement for

any nutrient should be eliminated as a breeder.

Plumage Color

Growth rate and other characteristics may be

affected by the genes that determine plumage

color of broilers. For example, the gene for silver
12 AGRICULTURE HANDBOOK 3 2 0, U.S. DEPT. OF AGRICULTURE

'/-:-''^'¿'^€''

BN-27940

FIGURE 7.—White birds, with Cornish and White Plymouth Rock strains predominating, make up most

broiler breeding flocks.

apparently has to be associated with the gene that

extends black and with recessive white for maximum growth. If white birds are desired, the

dominant white gene needs to be combined with

the gene causing barring.

Color sex-linkage for determining sex at hatching has not made progress because the females

are not white. Processors want all birds to be

white (fig. 7).

Egg Size

Broiler chicks from large eggs (24 to 28 ounces

per dozen) are definitely larger at hatching than

those from small eggs (18 to 22 ounces). As

broilers grow, the effect of this relationship is

less, but it is still definite at 8 and 12 weeks for

body weight and possibly for feed conversion.

The trend in early chick mortality is high in 18-

to 21-ounce eggs.

When hatching eggs are scarce and more small

eggs are set, broiler laisers observe that mortality

tends to increase and growth and feed conversion

suffer. In independent operations, broilers from

larger eggs usually bring a greater cash return

per bird over feed costs. However, in an integrated operation, broilers from smaller eggs may

give greater total returns over egg and feed

costs.

HOUSING

Location

A minimum of 5 acres of land is usually needed

for a specialized broiler enterprise. The broiler

house should be located where water drainage

and air movement are good. Low lying, damp

areas and valleys should be avoided. Usually an

open area, free from trees, is better for naturally

ventilated houses. However, for southern areas,

a row of tall trees on the south side of the house,

with branches above the eave line, may be desirable for shade. Most houses are oriented in an

east-west direction.

The cost of house construction is higher if the

land is not reasonably level. Usually it costs more

to prepare the site for one long house than for

two short ones. To avoid dampness, the floor of

the house should be a minimum of 6 inches above

the ground level, and higher is desirable. There

needs to be a good access road from the houses

to the highway because of feed and bird haulage.

The cost of getting utilities, such as water, gas,

and electricity, should be considered. A location

should be avoided where the birds may be disturbed by automobile lights. Houses should be

convenient to the caretaker's house, and the prevailing wind should be away from his house.

Requirements

A broiler house should provide clean, dry, comfortable surroundings for birds throughout the

year. The house should be kept warm enough,

but not too warm. The litter should be kept reasonably dry. Provision should be made to modify

the air condition as broilers grow. Fresh air

should be circulated, but the house should be free

from drafts. Results are not so satisfactory when

the broiler house is too cold, too hot, too wet, or

too dry.

The importance of adequate housing to protect

broilers from adverse conditions is apparent from

the seasonal effects on broiler results. Mortality,

condemnations, and medication costs are highest

and feed efficiency is usually poorest in birds sold

during the winter. Growth is best in the fall.

Feed efficiency is best in birds sold in the early

summer. Medication costs are also lowest in the

early summer. Hot weather adversely affects

both growth and feed efficiency.

Ways by which a grower can decide on the kind

of broiler house and equipment in which he will

invest include personal experience and experience

of neighbors and friends; advice of the serviceman, the contractor, and builders; and information from the county agent, extension service, and

poultry press. He must decide on how much capital he can invest, the size of broiler unit he needs

or can build, and the most economical facilities in

terms of expected results. The integrator may

have some requirements as to the size and type of

the broiler unit. For the importance of fixed

costs in relation to labor income, see pages 7-8.
COMMERCIAL BROILER PRODUCTION 13

BN-27939

FIGURE 8.—Typical broiler house in Delmarva area. Note outside door for each pen, large double end doors, outside

centered feed stoi'age, and white roof.

Types of Houses

Pole-type houses are economical to build, maintain, and clean. Pressure-treated poles are set

into the ground to support the roof and the walls.

Pole-type houses usually have roofs of metal and

walls of poultry netting covered with curtains or

with conventional building materials and curtains. If panels are to be used, the more conventional construction with a foundation and studs is

preferable.

In broiler-producing areas where winters are

cold, the better broiler houses will have insulated

ceilings and walls. Often they have central heating and may have controlled fan circulation.

In areas with warm winters, houses are usually

less solidly constructed. As a result, production

costs may be higher in both winter and summer.

More attention is being given to both insulation

and ventilation in all areas.

In the South, extreme heat and occasional

severe cold are both problems. Some wide-open

houses are being modified to include at least roof

insulation and adjustable curtains. More attention is being given to having enough heat when

it is needed, so that adequate ventilation can be

provided.

Broiler houses in the various areas are of many

types and dimensions and are constructed of many

kinds of materials. In the North, concrete floors

are usual, whereas in the South, they are rarely

found.

Many of the new houses are 24 to 40 feet wide,

with gable-type roofs. The consensus is that the

best broilers come out of relatively narrow houses

—24 to 30 feet wide. Wider houses are more

economical to construct (see p. 16). Construction

is usually either the pole or combined pole-stud

type. The length varies from 200 to 600 feet,

with most of them from 300 to 400 feet. For ease

in using 4- by 8-foot sheets of insulation, houses

are often built in multiples of 4-foot lengths. If

houses are too long, the cost of preparing the site,

especially in hilly country, may be too high. The

capacity of new houses usually varies from 7,200

to 20,000 broilers. All the birds may be in one

pen, or pens may have as few as 1,000 birds. The

trend is to pen units of 1,200 to 2,500 birds.

Sidewall height in houses is usually 6 to 8 feet.

If there is no ceiling or insulation is placed on the

underside of the rafters, a 6-foot height will normally give adequate headroom for cleaning equipment and sufficient opening for natural ventilation. Roofs are usually of galvanized iron or

aluminum, with insulation or 15-pound asphalt

felt under them.

If on-the-job constructed ridge ventilators are

used, the north side is usually closed and the south

opening can be closed when desired. Many new

houses have one 4-foot long, rectangular, prefabricated metal ventilator per 1,000 broilers.

It can be adjusted by means of a chain or rope

so that it can be wide open, entirely closed, or one

side can be open at any time.

It is usual to have double doors at each end so

that a manure spreader or truck can be used for

litter handling and for cleaning the house. The

doors can also be used for added ventilation in
14 AGRICULTURE HANDBOOK 32 0, U.S. DEPT. OF AGRICULTURE

BN-27941

FIGURE 9.—Brooder house. Note removable adjustable window panels, canopy hover, hanging feeders,

and floor-type waterer.

hot weather. Each pen has a wide door on the

outside wall to aid in loading birds going to

market. (Fig. 8.)

The overhang at the eaves is usually 2 feet.

Windows or upper openings may have panels

covered with various curtain materials or curtain

materials without frames. The upper panels may

swing in at the top, with or without hinges (fig.

9). The lower openings of this house may be

closed with curtain material or panels or be winterized with 15-pound felt. These lower panels,

when used, swing out. The lower panels may be

covered with metal, wood, insulation material, or

curtain material, similar to the upper frames.

Winches and cables are often used to control

panels from a convenient point in the house (fig.

10). All openings to the house should be covered

with 3^-inch mesh wire to keep out wild birds.

Although maintaining adequate temperature is

of first importance, constant attention is needed

to ventilate the broiler house properly. In general,

narrow houses are easier to ventilate. Attention

should be given to weather forecasts, especially

of windy weather, so as to anticipate the need

for quick adjustments of frames, curtains, or panels. Drafts that might chill the birds should be

avoided. Enough circulation should be maintained to keep the litter dry. Young chickens are

often overventilated. For information on environmental control, see page 15.

To get the best broiler performance, the house

should be as warm as possible without stressing

the birds. They should be kept as comfortable as

is economically feasible. There should be no unrepaired holes in the walls or roof, no misfitting

door and panels, nor too much window opening.

Insulation retards the flow of heat and helps

maintain a more desirable temperature in the

house. It is much easier to control the temperature and ventilation in a house if it is insulated.

The way the house is managed will, to a considerable extent, determine whether the insulation is

of value. It may be as important as the "R" values supplied. Insulation materials vary in effectiveness and cost. They should be economical,

efficient in stopping the flow of heat, reasonably

permanent, easy to apply, able to resist wind and

(ire, and resistant to wetting. They should not

warp and should resist rodents and insects. They

should not be used in the lower part of the house
COKMEKOIAL BROILER PRODUCTION 15

BIÎ-2T988

FIGURE 10.—Broiler raiser adjusting height of "pancake" brooder. Winches can be used to regulate height of curtains.

Note hanging waterers and feeders and feeder pan still in use.

without protection, unless they are peckproof.

Some materials have reflective properties as well

as built-in vapor barriers. To be effective, reflective surfaces must be exposed to the air space.

The general rule for ventilation in the space

between the roof insulation and the roof is to provide openings equal to one three-hundredths of

the building floor area. This type of ventilation

could consist of openings along the eaves above

the insulation and some ventilators in the ridge or

gable ends of the roof.

Controlled Environment

The primary objectives of using windowless,

fan-ventilated, insulated broiler houses are as follows : To provide a more desirable temperature, to

furnish an adequate supply of clean fresh air

without drafts during the winter, to create with

turbulent airflow a comfortable condition for

birds in hot weather, to give more positive ventilation, and to make management easier by reducing the time and some of the drudgery required to care for the birds properly. The final

result is an improved market quality of birds and

higher income.

A correctly designed and properly adjusted

air-inlet system is important in attaining these

objectives. A proven system should be used or an

engineer consulted. The operator usually sets the

timeclocks and thermostats once a week according to the age of the broilers or the desired temperature and more often when there are extreme

weather changes. It is essential not to throw

away needed heat by excessive use of fans.

About 25 percent of the maximum capacity of

the ventilating system is operated continuously

without controls. Mechanical ventilation and

insulation will not solve the problem of poor

management; they may add to it.
16 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

While the brooders are in operation, the thermostats are set in relation to their heat output.

The thermostats for the heating and the ventilating systems must be synchronized so they are not

operating in opposition to each other. Most of

the mechanically ventilated houses are being constructed so the sides can be opened. Winter results have beeen rather uniformly good, but in

some cases, sidewall panels have had to be removed during the hot periods of summer. Emergency electrical power units seem to be necessary

because of high or total losses in case of power

failure. The use of electricity for the fans can

be estimated at about 250 kilowatt-hours per

1,000 broilers per batch in the fan-ventilated

houses. Controlled mechanical ventilation is usually installed in houses that are insulated and in

which the normal bird density has been increased

by 20 to 25 percent. For forced ventilation, fans

should be selected and controlled to deliver from

1 to 3 cubic feet of air per minute per broiler

against l^-inch static pressure.

The balance between insulation, forced ventilation, amount of air infiltration, and variable

temperature outside must be maintained. Undesirable air conditions in the house may result if

any factors are not stabilized. The higher initial

operating cost of the windowless house must be

justified in terms of the claimed advantages.

Consideration also must be given to the need for

more technical skill than is possessed by the growers on many broiler farms. This skill can only be

gained through experience.

To maintain a balanced environment for broilers, prevailing and forecasted atmospheric conditions of temperature and Humidity should be considered. Fans are being used in broiler houses to

help force the required air through the house in

order to remove polluted air, dust, and the moisture evaporated from droppings, from around

waterers, or from rain entering the house. The

fan and blower assemblies and their controllers

and protective equipment should be selected to

meet the particular airflow requirements of the

situation. It should be possible to provide at least

3 cubic feet of air per minute per broiler. Poultry-house fan motors must be totally enclosed because of the dust, moisture, and ammonia fumes.

In well-insulated houses, filled to capacity with

birds, more air can be moved to remove moisture

without seriously lowering the temperature. A

room temperature of 60° to 70° F. is generally

desirable.

Housing Costs

Research is needed to find out what housing

costs are justified. In the meantime, some factors

to consider in choosing between low and high

initial housing investment are as follows: Current and probable future costs of construction,

probable differences in growth and feed conversion, lower mortality and condemnation losses,

interest rates, repair costs, taxes, risk, and

prestige.

The housing and equipment costs amount to 5

to 6 percent of the total cost of production. They "*

range from about 50 cents to $1 per square foot of *

floor area for the open-type house characteristic

of the southern broiler areas to about $1 to $1.50 ^

per square foot of initial investment for houses

insulated overhead, ventilated with fans, and 4

thermostatically controlled. There has been a

marked increase in the width of houses and the *

use of insulation, especially under the roofs, in -

most broiler areas. Wider houses cost less than

narrow ones per square foot of floor space, because there is less sidewall to enclose and they

have the advantage of having less exposed area

through which heat will be lost. In general, the

more the investment in housing, the lower the

fuel and repair costs.

With better equipment, labor costs are usually

less. If the watering system is well planned, the

waterers can be easily cleaned. If it is easy to

medicate the water, much labor can be saved.

However, the cost of production can be high if

facilities are not fully utilized. Using houses on

as nearly a continuous basis as possible and filling

them to capacity at all times are the main ways to

keep housing cost per bird low. For the effect of

fixed or housing costs on labor income, see page

7.

When estimating the percent cost of materials

for a pole-type insulated house with a concrete

floor, the lumber to frame the structure will be

about 25, the covering materials about 40, insulation 20, and concrete floor 15. If labor is estimated at about 40 percent of the total building

cost, the materials for the structure will be reduced to about 15 percent and the covering materials to 25 percent. Care should be taken in modifying plans to reduce costs. The saving may be

lost because of increased cost of repairs and maintenance and decreased life and safety of the building. Engineering assistance should be requested

before too much modification is attempted from

proven plans.

It is possible to use table 2 (p. 30) to estimate

the possible advantage of using insulation in the

broiler house, or otherwise building a house that

will result in an improved feed conversion. If we

assume a broiler at market age weighs 3.33 pounds

and has a conversion of 2.4 pounds and feed is

$4.50 per hundredweight, the feed cost of the

broiler is 3.33 times 10.80 cents (table 2), or 35.96

cents. If the feed conversion is 2.3 pounds, the

feed cost per broiler is 3.33 times 10.35 cents

(table 2), or 34.46 cents. The feed-cost saving
COMMERCIAL BROILER PRODUCTION

fer hroiler for each 10-point saving in feed conversion is 1.5 cents (35.96—34.46). The feedcost saving per pound of live hroiler for each 10-

point saving in feed conversion is 0.45 cent

(1.5^3.33).

Allowing 0.8 square foot per broiler and four

broods per year, about 16.5 pounds ((3.3X4)

-^0.8) of live broiler are produced per year per

square foot of broiler house. If the saving per

pound is 0.45 cent, the saving on the 16.5 pounds

of broiler weight per year would be 7.4 cents

(16.5X0.45). Allowing 10 years as the normal

17

life of a house for depreciation purposes, 74 cents

(7.4X10) per square foot could be expended in

housing costs for each 10-point anticipated improvement in feed conversion based on $90 per ton

of feed.

It would seem that some houses could be

changed with profit when there is a possibility

that improvement would result in better feed

conversion. Eesearch is needed to determine the

economics of housing in relation to livability and

condemnations and also on how to manage houses

so as to use environmental control effectively.

BROODING

Brooding Systems

Adequate temperature is the most important

factor in successful brooding, because without it

adequate ventilation in the wintertime is impossible. It is possible to raise broilers with many

types and makes of brooding equipment. Some

of the factors to be considered when deciding on

the system of brooding to be used are the availability and cost of the fuel, the size and construction of the brooder house (fig. 9), especially as to

whether or not it is insulated, the convenience of

operating the equipment, and the ease of removing the hover when cleaning out the house. It is

assumed that only those types of brooders will be

considered that will give good broiler performance.

The initial investment is greater when central

brooding systems for either hot water or hot air

are installed than when the canopy hovers are

used. The cost of operation is usually less. They

are more economical to operate in units of not less

than 3,000 broilers. The hot-water brooding system responds more slowly but holds its heat

longer than the hot-air system. This might be

of advantage in case of power failure if auxiliary

power is not available. Central heating systems

offer less fire hazard than the canopy hovers, except those using electricity as the energy source.

They are more easily controlled by thermostats

and other automatic devices because fewer are

required. However, inexperienced operators may

not be able to maintain as uniform temperature

under the brooding canopy or areas. The usual

fuels for central systems are natural or liquefied

petroleum gas, coal, or oil.

A central heating system should be designed

by a qualified person for the building in which

it is to be located. Hot-water systems were

used with pipes laid in the floor. They proved

less efficient and otherwise less satisfactory than

when pipes were laid above the floor and are

rarely used commercially now. The above-thefloor hot-water system usually consists of a horizontal bank of six pipes of 2-inch inside diameter, or smooth black water pipes, or a few combinations of alternate sections of "fin" and

smooth black pipes with equal heat output. Vulcan, or fin, pipes have about five times the radiation of smooth pipes, but are more difficult to

keep clean and lose some of their effectiveness

when dirty.

A hover is usually formed over the pipes. It

may consist of reflective-type insulation, plywood, 15-pound felt, or some other material,

placed on wood or insulated strips spaced along

the pipes. It is used while the chicks are small.

Litter is sometimes used on top of the hover,

but is not very satisfactory.

A forced hot-water circulation with circulatory

pumps is generally used because it responds

more quickly to the thermostat than the gravityflow hot-water system employed in earlier installations. Automatic controls consist of an aquastat to regulate the fuel intake and the thermostat to control the circulating pumps.

In the warm-air system there is a centrally

located warm-air heater, from which warm-air

pipes run each way to a series of hovers. The

warm air is forced through the heating ducts

by a blower. The returned air is wholly or

partially drawn from the heated pen. The

system is controlled primarily by thermostats

placed at the far ends of the brooder house. The

principal disadvantage is that, in case of a

power failure, there is no heat available when the

blowers stop operating. Otherwise, there is no

reason why equally good results cannot be

obtained with either system.

When an insulated mechanically controlled

house is used, the need for a central brooding

system may be more difficult to justify. One of

the principal reasons for the central systems

is the more favorable room temperatures that

can be maintained in both insulated and noninsulated houses.

For commercial broiler production, the 1,000-

chick hover should be the choice over the smaller

hover whether heated by gas, oil, or electricity.

The gas used may be natural or liquid petroleum
18 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

(LP). The gas hovers come in canopy or infrared types. It is usual to allow 10 square inches

of canopy hover space per chick. For winter

brooding in noninsulated houses, not over 750

chicks per hover are recommended. In insulated

houses, allow 850 chicks per hover. In mechanically ventilated insulated houses, it may be

possible to start 1,000 chicks under a 1,000-chick

canopy hover, allowing only approximately 7.3

square inches per bird.

Fuel consumption should be considered when

comparing canopy and infrared-type gas hovers.

Gas hovers are usually easy to regulate and

relatively inexpensive to operate. They may not

provide enough heat in extremely cold weather.

Like oil and electrically heated hovers, most gas

hovers are cold-room brooders and do not heat

the room to the extent that may be desired. This

is particularly true in noninsulated houses,

especially those with considerable air leakage

(ridge ventilators with open sides, or poorly

constructed panels and walls, or both). In insulated houses, gas hovers often do not heat the

room to the recommended temperature without

maintaining too high a temperature under the

hover. A warm-room, gas-burning hanging

brooder, often referred to as the "pancake" type,

is now being used (fig. 10). It helps to raise the

room temperature.

Gas and nonvented oil-burning hovers also

have a disadvantage of giving off moisture as

well as gases into the house. Every pound of

liquefied petroleum gas (LPG) burned will give

off 1.6 pounds of water, 3 pounds of carbon

dioxide, and some monoxide gas. Every pound

of fuel oil gives off 1.2 pounds of water, 3.1

pounds of carbon dioxide, and some monoxide

gas. For each pound of LPG or fuel oil burned,

it requires about 300 cubic feet of air at 60° F.

to remove the water and gases. A gallon of

LPG weighs about 41/2 pounds and has approximately 80,000 usable British thermal units

(B.t.u.) per gallon. A gallon of fuel oil weighs

about 7 pounds and has about 100,000 usable

B.t.u. per gallon. The 1,000-chick brooders have

heat outputs that range from 12,000 to 30,000

B.t.u. per hour.

LPG is extensively used as a fuel for brooders.

Propane and butane are its main constituents

and LPG is usually a mixture of them. During

low-temperature periods, butane might not

vaporize fast enough to furnish vapor for the

needs of the brooder, whereas propane might

furnish the required amount. Propane develops

about the same tank pressure at —10° F. as

butane develops at 70°. Therefore, gas suppliers

regulate the ratio of butane and propane in the

fuel to provide satisfactory operation at different

atmospheric temperatures. They also add alcohol to the fuel during cold weather. At all

times sufficient air must be supplied to the burners to get enough oxygen for complete combustion.

At one time coal-stove hovers were very pop- ^

ular in the North and East. They were excellent

for winter brooding, but were difficult to regulate

in mild and hot weather. Oil brooders are satisfactory, if the oil is reasonably priced. There

are two types, one with and one without vent

pipes. When wood is available and cheap, the

wood-burning hover is satisfactory. However, ^

few are used any more because of the labor

involved. Electric hovers are not extensively i

used. In areas where either coal or oil is

available and cheap, supplementary heaters are

often used effectively in cold weather to give

extra needed heat when gas and electric hovers

are used. Because they are cold-room brooders,

gas and electric hovers do not materially heat

the room. Consideration should be given to the

relative economy of using supplementary heat,

more hovers with fewer chicks per hover, or

larger canopies with more space per chick.

Environmental Factors

Careful management is necessary to give as

good air conditions as possible for temperature,

ventilation, and humidity. The action of the

chicks in itself is not, at all times, an adequate

guide to temperature. With multiple-unit or

large brooders, it is not possible to judge the

temperature of an individual hover by the position of the chicks around it. Each hover should

be equipped with a thermometer. The temperature should be read once or twice daily, depending principally on the room temperature and the

age of the chicks. The necessary adjustment

should be made. The brooding equipment should

be capable of giving enough heat at all times.

The recommended temperature at chick level

at the edge of the hover is 95° F. for the first 2

days, with a reduction of 3° daily for 5 days to

80° ; second week, 80° ; and from the third week

on 75°. Avoid any temperature below 60°. For

the best feed efficiency with good growth, and

especially when there is any sickness present,

a room temperature of 75° is recommended.

When chicks circle wide or leave the hover, it

it too hot or the room temperature is comfortable.

If they tend to crowd under the hover, it is too

cool. In either case, the temperature is probably

extremely high or extremely low and adjustment

is needed immediately. Avoid especially temperatures below 80° the first 2 weeks and over 85°

after 6 weeks. Avoid wide daily fluctuations of

20° to 30° in the first 6 weeks. Temperature

fluctuations should be watched, especially when

you are trying to brood without heat in warm

weather.

With uninsulated houses, the heat requirements
COMMERCIAL BROILER PRODUCTION

will be greater than with insulated houses,

provided the advantages of insulation are not

dissipated by excessive air leakage through open

• or leaky walls, uncontrolled ridge ventilators, or

in similar ways. The outside temperature is a

considerable factor in heat requirements and is

one of the reasons why winter broods are usually

less profitable than those at other times of the

year.

If everything else is normal, the chicks will

^ be comfortable when the relative humidity is

50 to 70 percent. They may show discomfort by

, huddling at 45 percent or less when the room

temperature is 60° to 70° F.

Insulated houses can be ventilated less than

noninsulated houses and still maintain good

conditions. The reason is that more moisture

is removed per pound of ventilated air at higher

temperatures in insulated houses than at increased ventilation at low temperatures in noninsulated houses.

In insulated houses, ammonia may be more of

a problem because of insufficient ventilation.

In uninsulated houses, ammonia is partially combined with condensing moisture.

An adequate source of heat helps to provide

adequate ventilation. Often a broiler house is

closed tight with plastic to conserve heat. As a

result, the air becomes foul and the litter wet.

With inadequate ventilation, ammonia may build

up to the extent that the eyes of the chickens

and the grower are affected. Chickens affected

by ammonia will jerk their heads as if to clear

them. This production of ammonia depends on

the amount of fecal matter in the litter, litter

moisture and temperature, litter aeration, and

possibly the porosity of the litter. When the

air is below 32° F., there is no noticeable ammonia. Above 32° and with litter-moisture content above 29 percent on a dry basis, ammonia

production is noticeable.

The chicks may be chilled if there is too much

ventilation. Overventilation that disperses

needed heat is costly. A draft or a wave of

cold air directly on the birds should be avoided

at all times. Correct ventilation is an individual

problem. Vented central heating systems do not

put additional moisture into the room as do nonvented gas and oil-burning hovers and require

less ventilation to remove the moisture. The

heat output of broilers after they are 6 weeks

of age is many times that of baby chicks. This

is true of moisture output. Ventilation must

be stepped up as broilers increase in age and

weight. Because needs ñuctuate so, the grower

should be present in order to give attention to

each situation as it arises. Neglect of the flock

can mean a stress on the birds, which can result

in colds and chronic respiratory disease complex,

in spite of previous careful attention.

Wet litter is never desirable. It can be the

19

source of disease outbreaks or breast blisters.

Excessive dust may trigger a respiratory trouble.

Both conditions can be avoided with proper

ventilation made possible by adequate heat.

Dust has sometimes been a major problem with

fan ventilation, probably because of lower humidity and overdrying of the litter.

If broiler houses are equipped with winches

and cable (fig. 10) to quickly and effectively

adjust frames and curtains, the houses will often

be better ventilated. It is even better if the

grower stays around the houses and spends

plenty of time with his birds, so that he can

anticipate the required action.

For information on the size and type of house,

insulation, mechanized ventilation, and use of

fans, see page 13.

Hot-Weather Problems

The heat given off by a thousand chicks at a

day old is only about 3,600 British thermal units

(B.t.u.) per hour, but at marketing age (3.3

pounds) it is 42,900 B.t.u. per hour. Temperatures from 85° to 95° do not markedly affect

growth and feed efficiency in chickens up to 6

weeks of age unless the humidity is also 55 percent or higher. Above 95°, heat prostration

may occur, especially at 75 percent relative humidity or higher. At any humidity, the 6-weekold and older broilers start to suffer at 85° and

over, and heat stress occurs.

When drugs are used in the drinking water,

the dosage prescribed is based on normal water

consumption. High temperatures will result

in high water consumption, which may give an

overdose of the drug. Conversely, low temperatures result in low water consumption, which

may give an underdose of the drug.

In addition to high temperature and humidity,

the stress can be increased by having deep litter,

insufficient water, too shallow water in waterers,

overcrowded birds, weeds outside the house so

high they cut off air circulation, and by doing

nothing to relieve the condition. Whitewashing

or painting the roof aids in heat reflection.

Water sprinklers on the roof will reduce the

roof temperature and therefore the radiation of

the heat from the roof. Increasing the turbulence of the air by increasing air circulation

by natural or artificial means will reduce the

body temperature and respiration rates.

Deep, cool, clean drinking water should be

provided. For water-consumption rates, see

page 37. Water consumption at 95° F. is at

least double that at 70°. Be sure the birds do

not run out of water at any time. At least four

8-foot waterers per 1,000 broilers should be provided when the temperature is above 90°. During hot weather, the use of lights becomes

especially important, as birds will eat better dur-
20 AGRICULTURE HANDBOOK 32 0, U.S. DEPT. OF AGRICULTURE

ing the cooler hours of the night than during

the hotter hours of the day. Keeping the litter

shallow helps to avoid some of the heat of

fermentation, which results with deep litter, and

also the birds can come in contact with cooler

soil and lose heat from their bodies by conduction.

Litter

The usual kinds of good-quality litter apparently do not affect growth, feed conversion, or

mortality under general growing conditions. A

good-quality litter is dry, loose, and absorbent.

It should contain no injurious materials or molds

and be reasonably free of dust. Convenience

and economy are important considerations.

Shavings are the most popular litter, wñth sawdust second. Sawdust should be covered for

3 days, as young chicks sometimes eat it. Peanut

hulls, cane" pulp, rice hulls, flax, peat moss, wood

chips, and %-inch pine-bark litter can be used.

Crushed corncobs may cause more breast blisters

than other litters. Excelsior waste tends to mat

and cake. Chopped straw, about 6 inches deep,

is preferred for large broilers and roasters to

prevent breast blisters.

To prevent disease from being tracked into

the house, the house should be locked after

clean litter is in place. A shallow pan of disinfectant should be placed at any entrance in

use. The disinfectant should be kept reasonably

fresh and undiluted.

Litter can be reused provided a severe disease

outbreak has not occurred. It is usually economical to do so. Growth, feed conversion, and

market quality, other than breast blisters, are not

usually affected, provided the litter is in good

condition. The prevailing broiler price, the cost

of the new litter, the value of the used litter as

fertilizer, its condition, and the cost of and the

time required for removing the old litter are important considerations. A cushion of clean, dry

litter is the best insurance against breast blisters.

If litter is replaced, usually 1 week is allowed

between batches for cleaning out and 1 week for

the pen to remain idle.

Wet or caked litter may be due to starting

with less than 2 inches of litter. It causes

stresses that may lead to poorer results. Usually

more breast blisters occur with w^et litter. Some

nonspecific enteritis and mycosis may result

from moldy litter. To avoid excessive moisture,

good management must be practiced. Ventilation must be sufficient and proper. The house

temperature must be adequate. Waterers must

be kept adjusted to avoid spillage and in good

working order to avoid leaks. Stirring damp

litter prevents caking in the winter. Between

broods, caked and wet litter should be removed

from the house.

Some of the risks of not cleaning out after

every brood include more losses, due especially

to chronic respiratory disease (CED), leukosis,

and aspergillosis. There may also be more ^

roundworms, tapeworms, and coccidiosis. On

the other hand, losses from avian nephrosis

(Gumboro disease) may be as high or higher

if the litter is changed. With thorough disinfection, security management, and replacing

old with new litter, mortality may sometimes be

materially reduced, even when avian nephrosis ^

is the problem.

The cost of removing old litter and adding new i

varies considerably. In commercial practice,

much hand labor is now replaced by use of

various kinds of mechanical equipment, including power loaders, bulldozers, manure spreaders,

and front-end loaders.

Deep litter is especially important on dirt

floors, because if it is dry, it will prevent penetration of the cold from the ground during the

low-temperature periods. In the winter at least

6 inches is desirable. Two to four inches is

usually a good depth for the summer. The

availability and the cost of litter become factors

(see p. 8).

Preparation of House and Brooder

One of the most important ways to prevent

and reduce losses from disease is a strict security

management program. In addition to the general sanitation program (p. 26), certain specific

things should be done in preparation for and

during the brooding phase.

The primary objective is to break the cycle of

infection. Every bird should be off the farm

before the cleanup process starts. Remove all

feed from feeders. All removable equipment,

such as hovers, feeders, waterers, and stands,

should be swept free of dust, washed clean under

pressure, disinfected with an approved disinfectant, and put outside in the sun while the house

is being cleaned. Do not overlook the baby chick

equipment, especially fountains. Equipment that

is raised while the litter is removed should be

washed and disinfected before fresh litter is

added. Nothing should be overlooked.. For disinfectants and insecticides, see pages 26-27.

A concrete floor is easier to clean than a dirt

floor. When the latter is used, it is preferable

to clean out all the old litter after each brood.

Put in 2 inches (4 inches in winter) of neiv,

clean, dry litter. When this is not considered

to be necessary or advisable because of relatively

little trouble from diseases or parasites, high cost

of litter or litter removal, or lack of sufficient

time between broods, a special effort should be

made to rake out and remove all damp or lumpy

litter, feathers, and dead chicks from the old
COMMERCIAL BROILER PRODUCTION 21

litter before adding a topping of fresh litter.

As a compromise, litter is sometimes replaced

entirely in the hover area, and 1 or 2 inches

of new litter put on top of the old litter in other

areas. The litter and dirt that are removed

should be disposed of away from the houses so as

not to blow or be tracked back into them.

After the floor has been thoroughly cleaned

and disinfected and before the new litter is

added, the ceiling and walls should be swept

or blown clean of dust and cobwebs. Hose

them down with water at about 300 poundspressure. Use a good detergent. A steam

jenny is useful because the heat generated may

be a valuable supplement to pressure and a

disinfectant in eliminating certain diseases and

parasites. After the house is dry, spray it with

malathion for mites and lice (see p. 56).

To control rats and mice, keep the premises

clean, have a rodent-control service use calcium

cyanide dust in outdoor rodent burrows, or use

anticoagulants, such as warfarin, pival, fumarin,

or Diphacinone in suitable baits, or buy a commercially prepared, ready-to-use bait mixture

and follow the manufacturer's recommendations.

A good bait formula includes—

Cups

Cornmeal 13

Oatmeal 4

Corn oil 1

Confectioners* sugar 1

Anticoagulant 1

In preparing the house for a new brood, check

all wire screens to be sure wild birds cannot

enter. Close all openings with 3^-inch mesh

wire. Remove tall grass and weeds for at least

30 feet from the house to prevent cutting ort*

ventilation and as a ñre precaution. Clean out

all ditches not only to give good drainage from

the house but to eliminate breeding places for

mosquitoes and other insects. The roads and

roofs should be put in good repair, especially

in the fall. Check the curtains or frames for

holes and be sure they are in good working order.

Between broods, be sure that each hover is

clean and free from dust and dirt, which could

cause a fire or an explosion. Infrared hovers

should have been cleaned and covered tightly

with a plastic bag immediately after being discontinued. A portable air compressor to give

about 100 pounds' pressure has many uses in the

cleaning process and can be purchased for as

little as $25. Check all thermostats, fuel lines,

and hoisting ropes not only to assure satisfactory

operation but to prevent accidents and fire. All

water valves should be in good working order.

All light bulbs should be checked and cleaned.

It is desirable to have the house empty for at

least a week after it is clean and ready for

occupancy. Before the chicks arrive, all the

workable parts of the brooder should have been

checked and the brooder should be in operation

and adjusted to the desired temperature. The

feeder lids and gallon water fountains should

be in place, as well as the chick guards if they

are used. All fountains and feeders should

usually be rinsed after disinfecting.

Lights

Probably no management practice varies more

than the lighting schedules for broilers. Lights

are used to prevent chickens from piling or

stampeding when scared. Enough light should

be provided to attract the chicks to the source of

heat. With most gas-burning hovers, sufficient

light is supplied so that no additional light is

needed. When the source of heat does not suffice,

an attraction light, or small light under the

hover, should be provided 24 hours daily for

about 2 weeks. Properly spaced 15- or 25-watt

bulbs are usually adequate.

Lights are used after the chicks are 2 weeks

of age to prevent piling and to allow more time

to eat. In the fall and winter, days are too

short. When broilers are uncomfortably hot,

they do not eat, especially in the middle of the

day. The use of lights at night, when it is cooler,

often results in materially increasing feed intake.

For general use, it is suggested that natural

light be supplemented with all-night lights from

the third week to the time of m^keting. To

avoid piling in case of power failures, it is

desirable to allow at least 1 hour of darkness

in every 24-hour period. Too intense light may

cause stress. An intensity of 1 foot-candle at

feeder height is recommended for maximum

gains. As broilers grow, the light intensity can

be reduced to as little as 0.1 foot-candle and still

be satisfactory. In houses 40 feet wide, two

rows of 100-watt bulbs 10 feet from the sides,

10 feet on center, and at an 8-foot height will

prove adequate, if bulbs are kept clean or reflectors are used. The rule-of-thumb practice is

one-fourth watt per square foot of floor space.

The color or kind (incandescent versus fluorescent) of light does not affect growth. Blue

lights may be used w^hen catching birds and red

lights in case of cannibalism.

Another program is to allow 2 foot-candles at

feeder height from 2 to 4 weeks, 1.5 foot-candles

from 4 to 6 weeks, and 1 foot-candle from 6

weeks to market. Light intensity can be altered

by changing the size of the bulbs.

Floor Space

The amount of floor space allowed varies from

0.8 to 1 square foot per chick. The actual

amount will depend on such factors as the

weight at which the broilers are to be sold, the

prevailing price of broilers, the extent to which
22 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

the environment is controlled, and the season of

the year.

Crowding broilers will usually result in more

culls, a lower average body weight, poorer feed

conversion, more cannibalism and feather pickJTiqr, decreased market value, and higher mortality.

For birds to be marketed at about 3 to 3%

pounds, usually allow 1 square foot of floor

space in the summer. The rest of the year and

in fan-ventilated insulated houses, the allowance

is 0.8 square foot. For broilers to be marketed

at 4 pounds and over, allow 1 square foot normally and 114 square feet in hot weather.

Size of Units

Houses currently being built in the major

broiler-producing areas will have a minimum

capacity of 7,200 (24 by 300 feet) and will

usually approximate 12,000 (40 by 300 feet)

birds. The house may not be divided into pens

or have as few as 1,200 birds per pen. Generally

the smaller the pen, the better the results one

can expect. Factors to consider are the relative

convenience of managing the birds, the cost of

the partitions, and the value of partitions in

restricting disease.

Waterers and Watering Space

Clean water at about 55° F. should be available. Thoroughly cleaned, disinfected, and

rinsed gallon fountains with wide-based, spillproof plastic bases should be provided at the rate

of 10 per 1,000 chicks. Some hanging waterers

(fig. 11) can be lowered so that the chicks have

early access to them. When all the chickens are

drinking from the automatic waterers, the gallon fountains should be removed, cleaned, and

preferably stored in a special dustproof place.

Fountains should not be used after 3 weeks, and

usually they are discontinued after about 10

days. Some automatic waterers can be used

successfully from the start.

It is a good investment to have automatic

waterers. If the 8-foot automatic hanging

waterer is used, at least one-half linear inch per

bird is usually allowed or three waterers per

1,000 birds. One additional waterer per 1,000

should be added when the temperature is 90° F.

or above. The birds should not have to go more

than 10 feet to get water at any time.

Waterers should be washed daily. The use of

a 5-gallon bucket with a 4-inch V cut in the top

of one side is suggested. One end of the trough

can be set in it as the trough is brushed or

mopped clean. The lip of the waterers, too,

should be adjusted weekly to the back level of

the average bird in the house for optimum water

intake and less spill. Keep debris out of the

waterers. More waste feed has been recovered

from V-shaped troughs than from the deeper

types. The valves on the waterers should be

checked daily and between each brood.

It is often difficult to maintain a constant

water supply in cold weather. Electric heating cable can be used to protect pipes from

freezing. The cable can also be used in troughtype waterers. The water is usually maintained

at not less than 40° F. The minimum temperature will vary depending on the location of the

piping, the construction of the house, and the

supply of heat from the birds and other sources.

The type of electric cable used for pipes in

broiler houses has a heating capacity of 5 watts

per foot. The length of the cable required

depends on the total length of piping and the

number of watts per foot of pipe required.

Anyone not familiar with electrical installations

of this kind should consult a competent electrician or power-company representative.

Chick Guards and

Other Management Practices

In cold weather the use of a 12-inch corrugated paper circle 2 feet outside the edge of the

gas, oil, or electric hover will help prevent drafts

on young chicks. In hot-water brooding, guards

are usually placed 3 feet from the outside edge of

the hover. Sometimes removable 1-foot boards

can be used in place of cardboard. For infrared

brooding, these are sometimes inserted in cleats

on the posts along one side of the house. When

room temperatures are 70° F. or higher, either

the guards are not used at all, or corrugated board

is replaced by %- or 1-inch mesh wire and the

guards are removed at the end of 4 days. Guards

normally can be removed at the end of a week.

Although the first 10 days are extremely important in the life of the chick, the first 2 days

are critical. Fill the fountains the night before

to remove the chill from the water. Carefully

place the fountains and feeders around the hover

so that they are easily accessible to the chicks.

Know the temperature under the hover and

adjust it to outside weather. For the correct

temperatures, see page 18. Normally the temperature should be 95° F. at chick level the first

2 days. Do not run some hovers at 85° and

others at 110°. Except in a single-unit operation,

the action of the chicks is not a sufficiently reliable guide to temperature. A desirable room

temperature is 70°. Try to maintain at least

60°, then chicks that wander from the hover are

less likely to be chilled. Ventilate the house to

keep the air fresh, but avoid drafts. Discourage

visitors to the house, especially at this time.
COMMERCIAL BROILER PRODUCTION 23

FIGURE 11.—Hanging waterers lowered so chicks have early access to them.

Debeaking

Careful debeaking of birds fed crumbles and

pellets will materially improve the percentage of

grade A birds marketed. There are many different methods of debeaking, all of which seem to be

effective, including notching so that the end of

the beak drops off. Usually one-third of the upper beak between the tip and the nostril of the

day-old chick is removed. If debeaking is too

severe, growth is retarded and some mortality

may result. Mash feed wastage is usually less

with debeaked chicks.

Feeders and Feeder Space

New, cut-down chick boxes or box lids are generally used at first for feeding the chicks, allowing one feeder lid per 100 chicks. These feeders

allow the chicks to find the feed easily. The

feeders should be placed in the immediate hover

area. They may be removed as soon as the chicks

are eating from the regular feeders in from 5 to

10 days. When hanging feeders are used, the

bottom pans (fig. 10) are often utilized in addition to some lids.

Several factors should be considered when

equipping a house with feeders. The two most

important are the amount of labor required and

the cost of the equipment. However, in individual situations such factors as managerial, physical, and mechanical ability may be equally important. Much depends on the capabilities of the

person taking care of the birds. The cost of the

trough feeders per 1,000 birds is usually the lowest, but the labor cost is generally much higher in

commercial houses of over 6,000 birds.

It has been shown that with all types of feeders less wastage occurs with pellets than with

mash.

The mechanical poultry feeder is probably the
24 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

most important labor-saving device the poultryman has. Without a mechanical feeder, but with

automatic waterers, one man will spend full time

looking after a flock of 6,000 broilers. With

automatic w^aterers and a mechanical feeder, the

same man can look after 15,000 to 20,000 birds.

If extra help is available during the first week, a

good grower can attend to 50,000 broilers.

A bulk feed bin holding several tons of feed,

which can be serviced outside the house, is usually

located in the center of the house. The mechanical feeder has a hopper that is fed from the storage bin. The feed is distributed in a continuous

trough through the house by a motor-driven drag

chain or shaker, by a closed conveyor system, or

by hanging feeders that move to a hopper for filling. When sacked feed is used, it is stored near

the hopper and put in by hand. Most mechanical

feeders are controlled by a time switch, but a

feed-consumption controlling device is sometimes

used to actuate the motor drive.

The original cost of mechanical feeders is usually higher than for hanging or trough feeders.

In modern broiler production, mechanical feeders

often are economically justified. The recommendation of the manufacturer should be followed as

to feeding space. It will usually approximate 10

to 12 broilers per linear foot of feeding space.

As a rule of thumb, installation of a mechancal feeder or feeders is worthwhile if the investment is no more than five times the labor saved

in a year. If the use of mechanical feeders will

save an hour a day at a dollar an hour, the grower

will save $365 annually; he can afford $1,825 for

equipment. With labor at $1 per hour, 13 flocks

will often pay the replacement cost of mechanical feeders in flocks of 10,000 or more. The cost

of the mechanical feeder should be depreciated

annually at 10 percent, interest should be charged

at 6 percent, and 3 percent should be allowed for

repairs. The bulk storage should be depreciated

at 5 percent, interest charged at 6 percent, and 1

or 2 percent allowed for repairs, depending on its

construction.

Operating the mechanical feeder.will require

15 kilowatt-hours per 1,000 broilers. The labor

requirement per 1,000 broilers is reduced more by

mechanical feeders as compared to trough or tube

feeders when a larger number of birds are involved.

With mechanical feeders, the grower can observe the birds more frequently. It is usually

difficult to justify a mechanical feeder for fewer

than 6,000 birds unless the age or physical condition of the caretaker will enable him to benefit by

it or unless suitable labor is difficult to get when

needed. Some of the disadvantages of mechanical

feeders may be greater waste of feed, greater

difficulty in adjusting to proper height, more tendency for growers to neglect birds, and inability

of growers to maintain the equipment properly.

The hanging tube-type feeders (fig. 9) are

sometimes preferred to the mechanical feeder, because they require the grower to spend more time

with the birds, they are easier to adjust, and may <

cause less downgrading. When these hanging

feeders are used, fifteen 15-inch diameter tube

feeders, holding about 30 pounds of feed, are suggested per 1,000 broilers. Probably fewer feeders

will be needed for a high- than a low-energy

ration, because the feed intake normally is less.

With some low-energy rations, twice as many may %

be needed. Usually more downgrading occurs

when more feeders are in the pen. t

With labor at $1 per hour, 10 flocks will often

pay the cost of replacing trough feeders with

hanging feeders in flocks of 10,000 or more.

Hanging feeders are preferred to trough feeders

because they do the entire job, are easier to adjust, if properly adjusted cannot be overfilled,

need not be filled so often, and cause less injury to

the birds. One of the principal disadvantages is

the tendency in most feeders for high-fat feeds

to stick to the sides and hang up. The many

ropes or wires supporting tube feeders are somewhat objectionable.

The use of trough feeders is usually limited to

flocks of 5,000 birds or fewer, to situations where

they are already installed, and where labor cost

is not important. Usually more feed is wasted

with trough feeders, and they take up more floor

space. Their principal advantages are absence of

hanging ropes, no hang up of feed, and the grower's spending more time with the birds. When

these feeders are used, a 4-foot chick trough

feeder is generally preferred, allowing 10 per

1,000 chicks started. At 3 weeks, a change is

made to the 5-foot broiler feeder, and 25 of

these feeders provide 3 linear inches of space

per bird.

Much feed wastage is avoided by not filling

feeders more than half full and feeding three

times per day. The labor of feeding at this rate

can be justified in improved conversion. The

space allowance is undoubtedly affected in all

types of feeders by the energy content of the feed

as well as the form in which it is fed. Less hopper space is needed with high- than low-energy

rations and with pellets or crumbles as compared

with mash. Feeders should have a lip to prevent

"billing" and wasting of the feed. Usually the

lip of the feeders of all types is adjusted weekly

to the back height of the average bird in the pen

or house. All feed troughs should be kept level

to assure optimum feed intake with minimum

feed wastage. Some growers hang their feed

troughs. When either tube or trough feeders are

used, bulk storage bins are usually placed to

serve two pens.
COMMERCIAL BROILER PRODUCTION 25

MANAGEMENT PRACTICES

Good management practices are summarized on

the inside front cover and a management guide is

given on the inside back cover of this handbook.

Size of Operation

In general, a person will not undertake a

broiler enterprise unless it will provide at least

a quarter of his income. Most growers have at

least 5,000 broilers per lot. So many other factors are involved that apparently little or no

relationship in general exists between the size of

the enterprise and the rate of growth or feed efficiency obtained. A small broiler raiser may be

able to do as well on a per bird basis as a large

producer. However, as the number of birds increases per grower or per building, the standard

of housing, equipment, and general management

needs to be higher for economical results.

The number of birds cared for by a family unit

tends to increase on either a full- or a part-time

basis. The amount of time given to the enterprise is an important consideration. The amount

of available finances may be a limiting factor.

The number of broilers a family unit can handle

satisfactorily will depend principally on the ability of the individuals, the size and arrangement

of the house or houses, and the labor-saving

equipment, especially in the feeding and watering

operations. For further information, see page 7.

Labor Efficiency

The two best assurances of good management

are a congenial working relationship between the

growers and the servicemen and the selection of

growers who either stay home when they have

chickens or have efficient assistance. Considerable

variation exists between farms in the amount of

capital, in other resources, and especially in the

managerial capabilities of the grower. There can

be no best plan covering labor, housing, and

equipment for all farms.

When considering any plan, it is necessary to

know the least cost of doing a particular job. The

cost of labor on a particular farm and the availability of money are extremely important. If

labor is excessive on the enterprise, it is doubtful

whether much capital outlay in labor-saving

equipment can be justified. On the other hand,

managerial problems can often be minimized by

reducing drudgery.

Stress Factors

Stresses cause physiological and biochemical reactions, which often depress growth rate or feed

conversion. Combined or severe stresses may result in culls or deaths. Most stresses can be

avoided by good management and nutrition. Environmental stresses include too high, too low, or

sudden changes in temperature; too high humidity at high temperatures; too many chicks per

brooder; too little floor space; faulty ventilation;

insufficient feeding or watering space; improper

debeaking; disease outbreaks; loud noises or

other things that frighten birds; and sudden

changes in personnel and in management practices.

Common nutritional stresses include all nutritional deficiencies, mineral imbalances, certain

hormones, most drugs, and certain ingredients at

higher than optimal levels. Chickens may react

to mild stresses in such a way that no eifect is

observable. However, chickens subjected to both

environmental stress and nutritional deficiencies

are more liable to succumb to disease. Under

stress, requirements are probably increased for

certain amino acids, vitamin A, and unidentified

growth factors. Nutritional requirements for

practical broiler formulas allow for these increased needs.

Grower Supervision

Growers may be supervised by the feed dealer

or by a serviceman. The duties of the serviceman vary with almost every situation. Management policies differ in the amount of discretion

allowed the serviceman and that allowed the

grower. A grower who has proven his ability is

often given much greater leeway than one who

has not done so. The best growers are not necessarily with the company offering the greatest

money return, although there is usually no better

incentive than the financial return. If a company and the serviceman are consistently fair to

their growers, maintain good relationships with

them, and have prestige in the industry, they may

get some of the best growers, with what a grower

may consider a less satisfactory contract.

In general, the serviceman provides the personal contact between the company and the

grower and in so doing gives a measure of protection to the financial risk the company has in

the contract. He should provide the grower with

detailed information on approved practices of

management and disease prevention and control.

He should be specific and clear in his instructions. He should give priority to grower communications, listen to their complaints, exchange

ideas with them, and weigh their suggestions.

When justified, the growers should be commended. Probably nothing is more important in

obtaining good results than to have good relationships between the serviceman and the grower.

A management program must be simple, definite,

and consistent.
26 AGRICULTURE HANDBOOK 3 2 0, U.S. DEFT. OF AGRICULTURE

The principal responsibility of the serviceman

is usually to visit the broiler growers. He generally visits each grower once a week. Fewer

routine calls are made on the best growers, and

he makes special visits when called. The broilers and the broiler house are checked and orders

for feed taken. When the broilers are about

ready, their marketing is discussed.

If a serviceman does not have enough growers

to occupy all his time, and sometimes when he

does have, he often is called on to assist the

grower in vaccinating his chickens, to deliver

chicks and feed, to help load and haul broilers to

market, or to assist with office records.

Most servicemen are paid a straight salary. As

an additional incentive, a bonus system may be

desirable. For example, a monthly check could be

given to the serviceman of the group of growers

having the lowest cost of production. Alternatively, a serviceman could be given increased remuneration when his growers exceed an agreed

average point spread or "production efficiency"

index.

General Sanitation

Security Management

Security management is a method of disease

control. The objective of a preventive program is

to stop the mechanical spread of disease organisms. Most diseases cannot occur without such

disease-producing organisms as bacteria, viruses,

and parasites. Their spread between and within

farms must be prevented. A security management program is necessary because disease agents

can enter a flock from so many sources. Diseaseproducing organisms can survive away from the

bird for at least a few hours, possibly for days or

weeks.

(1) Sanitation should start with clean eggs.

Do not store clean eggs in dirty flats nor in used

nondisinfected cases. Chicks should be delivered

from a clean hatchery, which is free of puUorum

and fowl typhoid, by attendants wearing clean

outer clothing and plastic boots. Do not ship

chicks by common carrier, such as train or bus.

Use new or clean disinfected boxes to transport

them.

(2) Isolate chicks from older birds and visitors, especially during the first 4 weeks. A separate caretaker is desirable. Keep houses locked

at all times, even when the caretaker is inside.

Exclude children, dogs, cats, and wild birds from

poultry houses and follow a fly-control program.

(3) Do not allow visitors in the same room

with the birds. If observers are necessary, they

should wear clean rubber boots, which have been

disinfected with quaternary ammonium compound, when entering and leaving the premises.

Plastic boots in addition are desirable. If the

birds are to be handled, clean coveralls should

be worn. The poultryman should himself not be

a visitor to other flocks. (Servicemen should

start out with clean outer clothes each morning.

They should first visit flocks under 4 weeks of

age with no apparent disease.)

(4) When birds are sold, remove the entire

group from the farm. Birds of more than one

age should not be on the same farm at the same

time. No stray or yard bird should be on the

premises.

(5) Normally the brooder house should be

thoroughly cleaned and disinfected between

broods. It should remain empty and clean for at

least a week. The brooder house should be well

ventilated. It is desirable that it be insulated

and, when economically feasible, have a concrete

floor.

(6) Houses and equipment should be thoroughly cleaned. Blow out or brush down the

dust, spray the house, and disinfect it at 300

pounds' pressure. Einse equipment with clean

water after disinfection. When practical to do

so, expose equipment to the sun. After the

equipment is returned to the house and clean

litter added, lock all doors. Place a pan of disinfectant at each door to be used by the attendant. Anyone who must enter should be required

to dip his shoes in the pan.

(7) The litter should be free from mold, have

a minimum of fine material, and be kept dry but

not dusty.

(8) The feed should not be delivered mto the

broiler house. The feed man should never have

to enter the house.

(9) In a disease outbreak, obtain a prompt,

accurate diagnosis from a professional source,

and start the proper treatment at once.

(10) Have and use a properly constructed,

conveniently located disposal pit or incinerator

of adequate size.

If properly followed, the security management

program should considerably reduce disease

losses as well as reduce the drug bill.

Disinfection

The producer should know what proper cleaning is, why it is necessary, and how to do it.

Most disease germs can be killed only by disinfection after thorough cleaning. The virus

diseases are best controlled by strict cleanliness.

Effective cleaning begins with the removal of

litter and manure. The cleaning process includes

scrubbing with brushes until surfaces are visibly

clean, using a good detergent, flushing with clean

water, and then applying an approved disinfectant. One advantage of a cement floor is that

lye (caustic soda) can be used effectively. Since

it corrodes metals, lye cannot be used as a

general cleaner. A 2-percent lye solution should
COMMERCIAL BROILER PRODUCTION 27

be used only Jwhen the temperature is above

32° F. Because it irritates the skin, one needs

to be cautious in it^ use. Lye can be used on

a dirt floor after it has been swept clean.

Quaternary ammonium compounds should be

used in concentrations of 200 p.p.m. (1:5,000)

and applied only to properly cleaned surfaces.

Hard waters slow their effectiveness. These

compounds can be used for flushing floors and

walls and for disinfecting equipment. They are

effective against most disease-producing bacteria

and viruses. ik^, ;

The cresylic compounds are good disinfectants

for general use. If a preparation has a phenol

coefficient of 5, it is five times more germicidal

than phenol. It would be used in a 1-percent

concentration, because the recommended dilution

of phenol is 5 percent. The cresylic compounds

can be used for disinfections for nearly all

bacterial and virus diseases.

The presence of organic matter (dirt and

manure) in the disinfecting solution or on the

surfaces to be disinfected may prevent the solution from destroying disease organisms so that

no disinfection results.

Parasite Contrai

After the house has been disinfected, malathion

can be used to control lice, mites, flies, and other

external parasites (see p. 56).

To control tapeworms, attack them at the

developing stage in the intermediate host. This

is best done by removing manure or litter, which

serves as a breeding place for beetles, ants, flies,

earthworms, slugs, or snails—the intermediate

hosts of the tapeworms. When a tapeworm

problem exists, the change of litter after each

brood is usually essential.

The large intestinal roundworm, Ascaridia

gallic has no intermediate hosts. The eggs are

hard to kill. Preventive measures include general sanitation.

CHICKEN-MEAT PRODUCTION

Cornish Game Hen

Cornish game hens, otherwise known as Eock

Cornish game hens, or baby broilers, are yomig

immature chickens usually produced in about

5 to 7 weeks. They range from li^ pounds to 2

pounds live weight when marketed. They weigh

about 16 to 28 ounces oven-ready. Although

their production is a specialized phase of the

poultry industry, it is similar to regular broiler

production in many ways. With few exceptions,

the usual methods of brooding and management

are followed. Only one-half square foot of

floor space is provided per bird. Most of the

baby broilers are raised under contracts similar

to those used for heavier broilers.

The ration used is high in protein (24-25

percent) and in energy (1,450 to 1,500 metabolizable calories). A high calorie broiler starter

ration should serve the purpose. It should give

the desired weight and feed conversion of 2. The

vaccination and disease-prevention program will

depend on local conditions and needs.

Most processors want birds to average 11/2

pounds live weight and 16 to 17 ounces when

ready for the oven. Other processors pay a

bonus for birds weighing 2 pounds and want

an eviscerated weight up to 24 ounces. The age

for marketing cockerels is 4I/2 to 5 weeks. The

last of the pullets go at 6 weeks. Overweight

birds are grown out as broilers. The dressing

percent (New York dressed) will be about 88

for 2-pound live-weight Cornish hens. The

eviscerated weight will be about 68 percent of

the live weight. As a percentage of live w^eight

the following can be expected: Breast meat

14 or 15, head 2 to 3.5, feet and shanks 4 to 4.5,

giblets 5.5, and viscera 11 to 12. The total

edible meat will be about 46 percent with males

and 47.5 with females of eviscerated weight.

The killing and processing methods are

similar to those for heavier chickens. A semiscald at 126° to 129° F. is usual. The birds are

then iced if to be sold fresh. Because of the

variable demand for this specialty product,

quick freezing is customary, using transparent

plastic bags. It must be kept in mind that owing

to the weight at which these baby broilers are

sold, the cost per pound is much higher for

the baby chick and for processing. Overhead is

less because more batches can be raised per year.

Broilers and Small Roasters

The average housewife prefers a dressed or

cut-up broiler or fryer that weighs 2 to 21/2

pounds, rather than a heavier one. Some of

the eastern broiler areas market a bird that has

a live weight of 4 pounds at between 9 and 10

weeks of age. If carried to 11 weeks, the males

will weigh 5 pounds and the females about 4

pounds. The feed conversion is about one-fourth

pound better for a 3^2- than for a 4i/^-pound

broiler. The extra feed cost to 11 weeks is offset,

at least in part, by the lower cost per pound for

the chick and for brooding. As one less lot can

be raised per year with the larger broiler, the

overhead cost is greater for it.

With large broilers or small roasters, in addition to the general problem of consumer demand,

the increase in breast blisters (p. 28) and in

mortality has to be considered. The greater

mortality can be minimized by good manage-
28 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

ment practices. For information on feather

picking and cannibalism, see page 56.

The heavy broiler is ideal for roasting. Roast

chicken is tender, tasty, and an ideal size for

the small family. It would give a greater return

to the producer if grown in quantity for a prearranged market.

Large Roasters and Capons

Large roasters and capons may be raised either

in confinement or on range. The tendency is to

raise them in confinement; pole-type houses are

extensively used. Provide one-half square foot of

space per bird until birds are 6 weeks old, 1

square foot to 10 weeks, 2 square feet to 16 weeks,

and 3 square feet to market. Roasters and capons

are brooded, fed, and managed as broilers to 6

weeks of age.

A capon is a castrated male chicken. After

this surgical operation, the bird fattens more

readily and produces more tender meat. Capons

sell for a higher price per pound than broilers

or roasters, because they require more labor and

cost more to produce. They do not use feed as

efficiently as lightweight birds.

Most poultrymen caponize cockerels that are

3 to 5 weeks old. The operation is of little value

after chickens are 2 months old. After the operation, put capons in clean quarters, separated

from other chickens for 2 or 3 days. Capons do

not need special care after they recover from the

initial shock of the operation. For directions on

how to caponize, see the U.S. Department of

Agriculture Leañet 490, Caponizing Chickens, or

consult your county agent or a poultry specialist.

A compound, dienestrol diacetate, sometimes is

added to special feeds to produce a feminizing

effect on male chickens. This may result in fattening and tenderizing of rapidly growing birds.

If you use this compound, follow the directions

of the manufacturer.

Give roasters and capons the kind and amount

of feed recommended for broilers during the first

6 weeks. After changing to finishing mash, supply cracked corn to roasters and capons in the

afternoon. Gradually increase the grain until

birds are getting equal amounts of corn, mash,

and pellets at 12 weeks of age. For roasters, increase the corn in the diet to 50 percent after the

15th week. Continue to supply grit as long as

birds are fed whole grain.

The fixed or overhead costs of producing roasters and capons are higher than for broilers, as

more lots of broilers can be produced within a

year. The chick cost per pound will be less for

the heavier birds. The cost of producing male

broilers is less than for female broilers, capons,

and roasters, including those few produced by

feeding dienestrol diacetate.

If capons are kept beyond 6 months, their rate

of growth is superior to nontreated males of the

same age, because they then put on weight much

more readily than do roasters. As birds ^et

older, their feed efficiency is poorer and mortality

can be higher. This must be considered in figuring cost of production. As caponizing males sets

back their growth rate slightly, there is no great ^

difference in the comparative growth rates of

capons and roasters to 6 months of age. Roasters

fed with dienestrol diacetate are usually marketed when 14 weeks of age. Time of marketing

will be conditioned by price and consumer preference for roasters and capons.

Breast Blisters (Sternal Bursitis)

With roasters and capons, special attention

needs to be paid to the prevention of breast blisters. Many carcasses are downgraded because of

them. Some strains of birds seem more susceptible to this condition, possibly because of the

breast angle or the feather coverage of the breast.

For information on a causative agent, see page

54.

Breast blisters occur more in males than in females and more in large than in small birds.

Rate of growth seems to be involved. The most

important preventive measure is to have ample

floor space and deep, dry, clean litter. Conditions that seem to irritate the keel bone and contribute to the trouble are wet or caked litter and

roosting places with sharp edges, such as waterers or feeders.

Marketing

In general, roasters and capons are marketed

in a similar way to broilers. As they are specialty products, like baby broilers, care must be

taken to have an assured market. Losses can

mount rapidly with a glutted market. Birds

treated with dienestrol diacetate and similar materials are usually sent to market live weight at 5

to 6 pounds. Their market quality is usually superior to that of untreated males of the same age,

but is not equal to that of capons. The principal

demand for capons is for large birds, 5 to 9

pounds, ready-to-cook weight. Roasters usually

average 31/2 to 6 pounds. The superior market

quality of capons warrants a higher price for

them.

FEEDS AND FEEDING METHODS

Most broiler feeds are produced by a feedmanufacturing company, the feed-mixing unit of

an integrated operation, or a large independent

producer. The processed feeds are usually mixed
COMMERCIAL BROILER PRODUCTION

in a centrally located mill and are delivered in

bulk by truck to the broiler farms. It is not generally economical for the individual grower with

10,000 to 50,000 broilers to do his own mixing

on the farm.^

Importance of a Good Broiler Ration

Any poultry meat-production enterprise must

use a feeding program that will give economical

results if the operation is to survive. Usually

the best broiler feeding program gives the highest net return. With it, the broilers grow fast,

use their feed efficiently, have the desired finish

and a high livability, and the feed cost per pound

is low. The finish may include plumpness,

bright-yellow pigmentation, and good feathering.

It is not always possible to get more money per

pound for exceptional quality in broilers. Yet

a reduction in cost that gives poor broiler quality

usually is not justified. As feed costs constitute

about 62 percent of the total cost of producing

broilers, including contract payments, it is important to know what constitutes a good economical ration.

Factors To Consider in a Broiler Ration

Rapid growth in broilers is important, because

with increased age and weight more feed is required to produce a pound of meat. By marketing as soon as the desired weight is reached, feed

and labor are saved and mortality risk is reduced. However, when the processor will accept

larger broilers, when prices are good, and when

feed is cheap, larger birds may be more profitable because there are more pounds over which to

spread the chick and the overhead costs.

Efficient feed conversion is an important consideration. It may be expressed as the pounds of

feed required to produce a pound of live broiler

or the pounds of live broiler per 100 pounds of

feed (see table 1). If a broiler consumes 8

pounds of feed and weighs 3.33 pounds when

marketed, the feed conversion is 2.4 (8-^-3.33),

and the pounds of meat per 100 pounds of feed

are 41.67 (table 1). With a feed conversion of 2.4

pounds, assuming a feed cost of $4.50 per hundredweight, the feed cost per pound of broiler

will be 10.8 cents (table 2). If the feed conversion goes up to 2.5, the feed cost per pound goes

up 0.45 cent to 11.25 cents, as shown in table

2. On the other hand, if the feed conversion goes

down to 2.2 and the price goes up 25 cents per

iFor more detailed information, refer to the publication Drugs; Current Good Manufacturing Practice in

Manufacture, Processing, Packing, or Holding, obtainable from the Office of Public Information, Food and

Drug Administration, 200 C St. SW., Washington, D.C.

20204.

29

100 pounds to $4.75, the feed cost per pound goes

down to 10.45 cents.

Note that at 2.4 pounds' feed conversion, the

change in the cost of 25 cents per hundredweight

of ration makes a difference of 0.6 cent in feed

cost per pound—a little more than a half cent per

pound. As is to be expected, the improvement

in feed conversion is of increasing importance as

feed prices increase. A feed costing $4.50 would

have to have a feed conversion of 2.2 to give

about the same feed cost per pound (9.9 cents)

as a $4 per hundredweight feed giving a 2.5

pounds' feed conversion (10 cents) (see table 2).

However, higher cost feeds should give a greater

average body weight as well as improved feed

conversion at market age.

Feed cost is approximately 71 percent of the

total cost of producing broilers without contract

payrmnts. The cost of producing a pound of

broiler can be roughly calculated by multiplying

the feed cost per pound in table 2 by factor 1.41.

As an example, if the feed cost per pound is 8.4

cents, the total cost is 11.84 cents. If contract

payments are made, the factor becomes 1.60 (feed

cost estimated at 62.4 percent of total cost including contract payments). The total cost, including contract payments, becomes 13.6 cents per

pound.

Point spread usually is a more satisfactory criterion of the worth of a feed than feed cost per

pound. The reason is that it takes rate of growth

into consideration. Point spread is the weight in

pounds times 100 minus the feed conversion times

100. For example, if the average weight is 3.33

pounds, the weight factor is 333. If the feed conversion is 2.40, the feed conversion factor is 240

and the point spread is 333 minus 240, or 93. Its

usefulness is limited because it becomes relatively

greater as the broiler gets older.

Income over feed cost per broiler is affected

by quality of bird, growth, and feed conversion.

The income is obtained by multiplying the

weight, 3.33 pounds, by the selling price. If it

is assumed that the average weight is 3.33 pounds

and the feed cost is $4.50 per hundred pounds,

the feed cost per broiler is obtained by multiplying the weight, 3.33, by the feed conversion by

the assumed feed cost of $4.50. The difference

is the income over feed cost. For example, at 13

cents per pound, the 3.33-pound broiler gives an

income of 43.29 cents (3.33X13). If there is a

50-point spread, the feed conversion is 2.83, and

3.33 times 2.83 equals 9.42 pounds of feed per

broiler. At $4.50 per hundredweight, the feed

cost per bird is 42.39 cents (9.42X4.50). The income over feed cost per broiler is 0.90 cent

(43.29—42.39). As would be expected, the income increases with the selling price—3.33 cents

per bird for each cent increase in selling price.

Without contract payments, feed approximates
30 AGRICULTURE HANDBOOK 3 20, U.S. DEFT. OF AGRICULTURE

TABLE 1.—Efect of feed conversion on income

Feed conversion

(pounds of feed

per pound of

live broiler)

2.8-

2.1-

2.6-

2.5_

2.4_

2.3_

2.2-

2.1-

2.0-

Weight of

broiler per

100 pounds

of feed

Pounds

35.71

37.04

38.46

40.00

41.67

43.48

45.45

47.62

50.00

Added weight

of broiler per

100 pounds

of feed

Pounds

1.33

1.42

1.54

1.67

1.81

1.97

2.17

2.38

Value of extra broiler weight per 100 pounds of feed

at indicated live-weight selling price per pound

$0.16

Cents

21.28

22.72

24.64

26.72

28.96

31.52

34.72

38.08

$0.15

Cents

19.95

21.30

23.10

25.05

27.15

29.55

32.55

35.70

}.14

Cents

18.62

19.88

21.56

23.38

25.34

27.58

30.38

33.32

$0.13

Cents

17.29

18.46

20.02

21.71

23.53

25.61

28.21

30.94

3.12

Cents

15.96

17.04

18.48

20.04

21.72

23.64

26.04

28.56

).ll

Cents

14.63

15.62

16.94

18.37

19.91

21.67

23.87

26.18

$0.10

Cents

13.30

14.20

15.40

16.70

18.10

19.70^^

21.70

23.80

TABLE 2.—Feed cost of producing a pound of live hroiler ^

Feed

conversion

(pounds of

feed per

pound of

live broiler)

(a)

2.8-

2.7_

2.6_

2.5_

2.4_

2.3-

2.2-

2.1_

2.0-

Cost of feed per pound of live broiler (c) at indicated cost of feed per 100 pounds (&)

$5.50

Cents

15.40

14.85

14.30

13.75

13.20

12.65

12.10

11.55

11.00

$5.25

Cents

14.70

14.18

13.65

13.13

12.60

12.08

11.55

11.03

10.50

$5.00

Cents

14.00

13.50

13.00

12.50

12.00

11.50

11.00

10.50

10.00

$4.75

Cents

13.30

12.83

12.35

11.88

11.40

10.93

10.45

9.98

9.50

$4.50

Cents

12.60

12.15

11.70

11.25

10.80

10.35

9.90

9.45

9.00

$4.25

Cents

11.90

11.48

11.05

10.63

10.20

9.78

9.35

8.93

8.50

$4.00

Cents

11.20

10.80

10.40

10.00

9.60

9.20

8.80

8.40

8.00

$3.75

Gents

10.50

10.13

a75

9.38

9.00

8.63

8.25

7.88

7.50

$3.50

Gents

9.80

9.45

9.10

8.75

8.40

8.05

7.70

7.35

7.00

$3.25

Gents

9.10

8.78

8.45

8.13

7.80

7.48

7.15

6.83

6.50

$3.00

Cents

8.40

8.10

7.80

7.50

7.20

6.90

6.60

6.30

6.00

Ma) X (&) = (^)-

71 percent of the total cost of the broiler. A factor of 1.41 is used to convert feed cost to total

cost without contract payments (see table 2). At

$4.50 per hundredweight and a feed conversion

of 2.2, the feed cost per pound is 9.9 cents

(2.2X4.50). The total cost, without contract

payments, would be 13.95 cents per pound and the

nonfeed costs (chicks, fuel, lights, litter, medicine, and vaccination) would be 29 percent, or

4.05 cents (13.95—9.9) per pound.

With contract payments, the total cost per

pound is approximately 1.6 (100-^-62.4) times the

feed cost per pound, and the nonfeed percent of

the total cost is about 37.6. With a feed cost of

9.9 cents per pound, the total cost becomes 15.84

cents and the nonfeed costs 5.95 cents (37.6 percent of 15.84) per pound. The importance of relating average body weight sold and feed conversion with the price paid for the feed is obvious.

To consider mortality as a factor, income over

feed cost should be figured on the basis of the

number of birds sold.

The broiler-feed ratio is sometimes used as an

index of the broiler situation. It is the pounds

of feed equal in value to a pound of live broiler.

For example, if the price of feed is $4.67 per hundred pounds and the price of broilers is 14 cents,

the ratio is 3 (14^4.67). If the price of feed is

$5 per hundred pounds and the price of broilers

is 15 cents, the ratio is still 3. The ratio fluctuates widely. It may be as favorable as 5 (average, 1955) or as unfavorable as 2.7 (December

1963).

In table 1, the effect of feed conversion on income can be observed. Of course, the higher the

selling price, the greater the value of the extra

weight. If feed conversion improves from 2.5 to

2.4, the added weight per 100 pounds of feed is

1.67 pounds. The value at 13 cents per poimd

is 21.71 cents. If the improvement in feed conversion is from 2.5 to 2.3, the added value, due to

the 20 points, is 45.24 cents (21.71 +23.53). The

feed giving such an improvement in feed conversion would be worth $9.05 (45.24X20; also,

4.33 +4.72 in table 3) per ton more. Table 3 can

be used as a guide to the comparative value of

feeds when their relative feed conversions are

known.
COMMERCIAL BROILER PRODUCTION 31

CO I

5^

•s. <

Increase in value of feed per ton as feed conversion

improves at indicated live-weight selling price

per pound (not cumulative)i (d)

OH

irt^icoococoioeoco

iCDOOOCOCDOiCOt-

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ITHCOÄCDO'^CO'*

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(MÖm-

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71.43

74.07

76.9280.00

83.33

86.96

90.9195.24

100.00

rHÉ

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85.72

88.8892.30

96.00

100.00

104.35109.02

114.29

120.00

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Dol.

114.29

118.51123.07

128.00

133.33

139.14

145.46152.38

160.00

Weight

of

broiler

per

ton of

feed

(Ö)

<j^ CO t-. (TIp CqP rH T}^p

Feed

conversion

(pounds

of feed

per pound

of live

broiler)

00l>ÇDlOTtHC0C<lrHO

(M* (N (M* C4 (N* Oi ci (M* ci

ta
32 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

Feed conversion is given in table 1 as both

pounds of feed per pound of broiler and pounds

of broiler per 100 pounds of feed. It is often advantageous to convert from one to the other. The

effect of feed conversion on the value of the feed

is given in table 3. The pounds of broiler (live

weight) produced per ton of feed are obtained

by dividing 2,000 by the feed conversion. For

example, 2,000 divided by 2.8 (a) equals 714.3

pounds (6). The value of this live weight of

broiler at various prices is given in the third

column (c). For example, 714.3 times 16 cents

equals $114.29 (c). The increases in the value of

the feed due to the improvement in feed conversion are shown in the last column (d).

For example, when feed conversion improves

from 2.8 to 2.7, the pounds of broiler produced

increase from 714.3 to 740.7 and the value at 16

cents per pound increases from $114.29 to $118.51,

an increase of $4.22. For the 0.1 pound in feed

conversion, the value per ton of feed went up

$4.22. Per bag it would be 21.1 cents.

Data in the last column (d) are not cumulative.

To get the cumulative or aggregate value between

efficiencies, add all the increases between them.

For example, an improvement in feed conversion

from 2.5 to 2.2 at 16 cents would mean an increase

in value of feed of $17.46 (5.33 + 5.81 + 6.32) per

ton without considering the probable increase in

average live weight.

Feeding Programs

No feeding program is best for all situations.

Sometimes a single complete ration because of its

simplicity has proven advantageous, especially in

small operations. Broilers should be full fed continuously. Feeding from three-fourths to 1 pound

of a prestarter diet usually gets chicks off to a

good start. This prestarter is used for 10 to 14

days. It may be the same feed as the starter diet

with 100 grams of antibiotic added or it may differ from it in many ways, such as a higher percent of protein, different sources of proteins, and

various amounts and kinds of vitamins. The

starter is used from the time the prestarter is discontinued to the end of the fifth or sixth week.

It usually has a slightly lower protein content

than the prestarter and a low level of antibiotics.

The use of a finisher feed at 5 or 6 weeks allows an increase in energy in relation to the protein content of the ration. When desired, increased pigmentation can be obtained by the use

of selected ingredients in the finisher. To meet

the requirements of laws regarding the withdrawal of some additives just before marketing,

a nonmedicated "withdrawal" feed may be fed

for a specified period. However, some medicated

finishers can be fed to marketing. It is highly

undesirable to start chicks on the finisher left

over from the previous batch of broilers. The

practice is nutritionally unsound. Also, the feed

is often moldy.

A prestarter or starter may be fed in mash or

crumble form for 2 or 3 weeks. "Starve-outs" are

fewer with mash. After 2 or 3 weeks, the starter

can be fed in mash, crumble, or pellet form. The

earlier the change is made to pellets, the greater

the advantage from their use. The finisher feed

also can be continued in the same form the starter

feed was fed. It is not desirable to change from

pellets to mash. Grit can be fed, but it is usually

not needed with all mash feeds. When fed, it is

generally equal to about 10 percent of the total

feed consumed, and the size is varied with the

size of the bird.

NUTRIENT REQUIREMENTS

The nutrient requirements of broilers vary with

such factors as breed or strain, sex, age, rate of

growth, environmental stresses, and disease.

The minimum nutrient requirements ^ per

pound of feed for starting chickens from 0 to 8

weeks of age are as follows :

Total protein percent—

Vitamins :

Vitamin A activity U.S.P. unitsi—

Vitamin D I.C.U.2—

Vitamin E

Vitamin Ki mg__.

Thiamine mg—

Riboflavin mg—

Pantothenic acid mg—

- 20

_ 910

_ 90

_ See text.

.24

.8

1.6

4.5

2 NATIONAL RESEAKCH COUNCIL. NUTKIENT REQUIREMENTS OF POULTRY. Nati. Res. Council Pub. 1345, 28 pp.

Washington, D.C. 1966. The values expressed as amount

per kilogram of feed, obtained from this publication,

were converted into amount per pound of feed for this

handbook.

Niacin mg 12

Pyridoxine mg 1.3

Biotin mg .04

Choline mg.3 590

Folacin mg .54

Vitamin B12 ^S -004

Minerals :

Calcium - percent 1.0

Phosphorus do.* .7

1 May be vitamin A or provitamin A.

2 See p. 34.

3 See p. 35.

4 At least 0.5 percent of total feed of starting chickens should be inorganic phosphorus. All phosphorus of

nonplant feed ingredients is considered inorganic. Approximately 30 percent of phosphorus of plant products

is nonphytin phosphorus and may be considered as part

of inorganic phosphorus required. Part of phosphorus

requirement of growing chickens must also be supplied

in inorganic form. For birds in these categories, requirement for inorganic phosphorus is lower and not so well

defined as for starting chickens.
COMMERCIAL BROILER PRODUCTION QQ

Potas^um~"3""~"I"IIII~"I^d^^ 2^ ^^ ^^ ^^^ advisable to allow any amino acids

Manganese mg 25* ^^ exceed very much their actual requirements.

Iodine mg .16 To do so may increase the cost of the ration

Magnesium mg 227 unnecessarily and also may depress growth, due

Copper : Zml"": ^18 pi^obably to imbalance. Most efficient growth

Zinc I mg 16* results when the essential amino acids are present

5 Equivalent to 0.37 percent of sodium chloride. in adequate and balanced quantities.

These requirements are adequate for optimum re- 7]^^. availability and the amount of amino

suits as well as normal health. When consider- ^^^^^ ^^ ^^J protein material are affected by the

ing the values to be used for practical broiler processing conditions, especially the temperafeeds, the feed formulator should evaluate his ture used and the length of time a meal is exown situation and determine margins best suited P^^^^ ^^ ^^- Vegetable protein meals that have

y to it. A guide to nutrient specifications is given ^^^ ^^\ heated excessively during processing

on page 46. ^^^ usually the most desirable. However, some

Broiler feeds should provide proteins, carbo- ^^^^^ ^^^ underprocessed to the extent that the

hydrates, fats, minerals, vitamins, and unidenti- ^^^^^ ^^^^^ ^^^ ^^^J partially available,

fied growth factors in proper balance. Incomplete or unbalanced rations may result in poor Energy

growth, inefficient utilization, and nutritional Energy and the relation of energy to protein

iseases. . iî-r>ix^ix ^^^ to amino acids are important considerations

In Nutrient R^equirements of Poultry,« data j^ broiler feeding. Both productive energy

are given on the daily nutrient requirements and ^nd metabolizable energy determinations are used

the feed and time required to obtam certam by feed formulators. Variable values for proaverage live weights with heavy breed chickens. a^etive energy are obtained unless a controlled

Protein environment and genetically uniform chickens

rr.! , -1 -, -, . , j. ' n arc cmployed in test procedures. Tables for

The broiler depends mainly on protem for productive energy values have been used, because

building tissue Prestarter and starter diets ^^^^ ^^l^es were available for the various inshould contam 20 to 24 percent of protein. The g^edients and for finished feeds. Metabolizable

source of the protein and the energy content energy values vary with the diy-matter conof the diet are important considerations m deter- ^ent of the ingredient or ration. As more values

mmmg the exact percentage. The quantity of ^re available, greater use is made of the metabocertam of the ammo acids found m the protein jj^able energy values in feed formulation,

is more important than the total pro^^^^^ Carbohydrate and fat serve primarily as

m the diet. The various plant and animal pro- ^^urces of energy although protein may also

terns differ basically because of these ammo be used for this purpose. Amounts of energy

aci^s they contain. . ^ ,,_ in excess of needs are stored as body fat.

The essential ammo acid requirements for the Carbohydrate includes nitrogen-free extract and

ration of starting chicks based on a protemle^^^ crude fiber. Nitrogen-free extract includes

of 20 percent and a metabolizable energy level of starches and sugars that are readily utilized.

1,250 calories per pound are as follows: ^ Crude fiber is not utilized by the chickens. If

ArgSiSr''''^ ^^^^^^*^^^^*^^^' good feed efficiency is desired, the fiber content

Lysine^- I I_III_IIZIIIIIII 1.1 ^^ ^^^ ration should be kept low. The grains

Histidine A and their byproducts are the principal sources

Methionine .75 of carbohydrate.

^^. . Fat is present in most feedstuffs. The fat

|cystine^^^^_IIIIIIIIIIIIIIIIII"IiriIIIII 35 content of the ration can be raised by adding

Tryptophan Z .2 various commercially produced stabilized fats

Glycine 2 1 from animal and vegetable sources. The addiPhenyialanine 1.3 tion of some fats to certain diets increases the

fPhenvlalanine 7 ^^^^ ^^ growth. Dietary deficiencies of certain

/Tyrosine mZIZIIIIIIZZIZIZZIZZZZZZI .6 unsaturated fatty acids can be overcome by

Leucine 1.4 linoleic, but not linolenic, acid. Feed efficiency

Isoleucine .75 normally improves as the fat content of a ration

Threonine .7 is increased.

Valine — .85

1 These are estimates of requirements and include no VîtaiMÎne margins of safety. ^ iidiiiiiis

2 Chick can synthesize glycine, but synthesis does not rp. svmDtoms often seen in phronic proceed at rate sufficient for maximum growth. -, ¿ • gross symptoms oiten seen m enrome

denciencies oi any oi several nutritional factors

3 See footnote 2, p. 32. may be similar, such as retarded growth, ruffled
34 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

plumage, general weakness, loss of appetite, and

emaciation. Vitamins are nutritional factors

considered necessary for growth and maintenance of health. For the symj)toms and lesions

of important nutritional deficiency diseases in

broilers, see page 51.

The requirements for the needed vitamins are

sometimes met by the natural feedstuffs. In

some cases, the need for a vitamin requires the

addition of a concentrated source or vitamin

supplement to the ration, because the natural

content is too low or there ha^ been or might be

loss due to oxidation.

Most practical broiler formulas do not benefit

by adding folacin, biotin, ascorbic acid, vitamin

Be (pyridoxine), or thiamine.

Vitamin A

Vitamin A is required for the normal functioning of the epithelial tissues of the membranes

of all the principal functional tracts of the

body. Normal functions, such as growth, development of bones, and resistance to infectious disease, are totally or partially dependent on this

vitamin.

The requirements for vitamin A are expressed

in U.S.P. units of vitamin A activity per pound

of feed. Normally 0.6 /xg. of beta-carotene appears to be equivalent to 1 U.S.P. unit of vitamin A. The principal sources of the carotene,

or provitamin A, in broiler rations are alfalfa

meal, yellow corn, and corn gluten meal. To

meet the full requirements, a vitamin A concentrate is often added and especially to rations in

which milo or wheat replaces yellow corn and

in high fat diets.

When losses may be due to the action of

certain minerals, heat during storage, or pelleting, a stabilized product is used or a margin

of safety allowed. It is not unusual to include

enough vitamin A in the ration to build up and

maintain a reserve of vitamin A in the liver. To

do this, more vitamin A may be advisable with

certain diseases, such as coccidiosis and chronic

respiratory disease (CRD), and when birds go

off feed. Any deficiency retards growth. An

extreme deficiency affects the health of the bird.

For symptoms, see page 51.

Vitamin D

The requirements for vitamin D are expressed

in international chick units per pound of feed.

Chicks effectively use vitamin D3 from irradiated

animal sterol and fish oils, but do not use vitamin

D2 from irradiated ergosterol as efficiently as

do mammals. When the minerals in the ration

are adequate and balanced, vitamin D is no

different in efficiency from fish oils and from

irradiated animal sterols.

At one time rickets was a common disease in

broilers. It is caused by the nutritional deficiency due to insufficient vitamin D, calcium, or

phosphorus, although rarely is a deficiency of

the minerals acute enough to bring on the

symptoms. The chicks with rickets sit down

on their hocks or walk with a stiff-legged gait.

They are retarded in growth and appear unthrifty, or without vigor. The breastbone becomes crooked, the rib ends are beaded, and the

back and legs are soft and rubbery.

The vitamin D3 concentrate is usually premixed with yellow cornmeal before it is incorporated in the rest of the ration.

Vitamin E

Vitamin E occurs widely in grains, grain byproducts, and alfalfa meal. It is involved m

most of the tissue functions of the chick's body

and in the prevention especially of encephalomalacia (crazy chick disease), muscular dystrophy, and exudative diathesis. Most rations

have enough vitamin E from natural ingredients,

but the content can be materially reduced by

oxidative destruction during storage, especially

after grinding, and from pelleting.

Vitamin E is not a single chemical entity.

It consists of various tocopherols, which vary

widely in biological activity. The most active

is alpha-tocopherol. One international unit

(LU.) is the biological potency of 1 mg. of

dl-alpha-tocopheryl acetate. Another form, also

available for feed mixing, is a d-alpha-tocopheryl

acetate. One mg. of it is equivalent to 1.36

LU. of vitamin E.

There seem to be important interrelationships

between vitamin E, antioxidants, sulfur amino

acids, and selenium in the prevention of vitamin

E deficiency diseases (see p. 51). As a margin

of safety, 5,000 LU. of vitamin E per ton are

sometimes added to broiler feeds as a supplement.

Vitamin K

Chicks may be hatched with a very low reserve

of vitamin K. If fed a deficient ration, they may

bleed to death from an injury. Hemorrhages

may occur in any part of the chick's body. A

lack of vitamin K also delays the clotting time

of the blood. Mortality and morbidity of chicks

from cecal coccidiosis have been decreased by

adding a source of vitamin K to the feed. There

is a direct antagonism between sulfa drugs, such

as sulfaquinoxaline, and vitamin K. Vitamin

K has been beneficial in treating some cases of

hemorrhagic disease. For information on hemorrhagic anemia syndrome, see page 52.

Vitamin Ki occurs naturally in alfalfa meal,

dried cereal grasses, soybean meal, and soy oil.
COMMERCIAL BROILER PRODUCTION 35

Vitamin K2 has been isolated from putrefied

fishmeal. Vitamin K3, the synthetic vitamin K,

is menadione. Menadione sodium bisulfite, which

is extensively used in feeds and water, is an

additional compound of menadione. It contains

33 percent of menadione. Added vitamin K

sources are used only to meet stress conditions,

primarily due to drugs and diseases.

Riboflavin

Curled-toe paralysis is the characteristic

symptom of riboflavin deficiency. Other symptoms are retarded growth and diarrhea. In

nutritional paralysis, the chicks suddenly start,

walking on their hocks with the toes curled

inward. As they are otherwise healthy, they

respond rapidly to added riboflavin in the ration.

Good sources are a synthetic compound, fermentation byproducts, dried milk products, and

dried brewer's yeast.

Pantothenic Acid

A deficiency in pantothenic acid results in

dermatitis of the feet, and crusty scabs appear

around the mouth and vent. The eyelids may

stick together and growth and feather development are poor. Molasses and fermentation byproducts are good sources of this vitamin. The

synthetic compound commonly used as a source

is d-calcium pantothenate. Less costly to manufacture than this compound is dl-calcium

pantothenate, but 50 percent of it is inactive.

Use should be based on d-pantothenate activity.

Niacin

In niacin deficiency, the tongue and mouth

cavity become inflamed. Other symptoms include retarded growth, loss of appetite, poor

feathering, and scaly dermatitis of the feet and

skin. The principal common sources of niacin

are the synthetic compound, grains, and the

fermentation, ^rain, and fish byproducts. The

niacin in corn is not available to poultry.

Choline

Choline is a factor in the prevention of

perosis, or slipped tendons. When the ration is

deficient in choline, growth is retarded. The

principal source of supplementary choline is

choline chloride. Each pound or 25 percent

choline chloride supplies 98,518 mg. of choline.

Biotin

A dermatitis results from biotin deficiency.

The feet become rough and hemorrhagic cracks

appear. Some scabs appear about the beak.

Symptoms are similar to those for pantothenic

acid deficiency. In pantothenic acid deficiency

the first symptoms are around the mouth and

eyes, and rarely are the feet severely affected.

Folacin

Folacin, or folie acid, is essential for the

normal functioning of virtually all body cells.

In broilers a deficiency results in retarded

growth, poor feathering, perosis, anemia, lowered

resistance to roundworms, and an increased

methionine requirement. Most rations are adequate in folacin. Some questionable rations will

benefit by the addition of 0.25 mg. per pound

of the synthetic compound.

Vitamin BQ

Chicks on a vitamin Be-deficient ration grow

very slowly and often show considerable excitability and jerky convulsive movements. They run

about aimlessly, fall on their sides, and paddle

their feet in the air. Complete exhaustion

follows and is often fatal. The deficiency is

rarely seen in the field.

Vitamin B12

Vitamin B12 is essential for chick growth.

There are no specific symptoms of deficiency.

Vitamin B12 is associated with animal protein

sources. Most rations in which the principal

source of protein is of vegetable origin require

vitamin B12 supplementation. Some sources of

B12 and the approximate value in milligrams per

pound in natural feedstuffs are as follows:

Poultry byproduct meal 0.16, feathermeal 0.44,

fish solubles 0.20, fishmeal 0.1, and meat scraps

0.05. Generally a commercial vitamin B12

supplement is used.

Thiam^ine

Polyneuritis results if baby chicks are fed a

thiamine-low ration for about 10 days. The

head of an affected chick is drawn over the back.

Other symptoms of deficiency are general weakness, loss of appetite, emaciation, and convulsions. Thiamine deficiency is uncommon.

Unidentified Growth Factors

The unidentified growth factors (UGF) are

probably synthesized by the intestinal microflora. At least three distinct organic factors

and two or more trace minerals are apparently

involved in the UGF. Organic growth factors

have been isolated from fish solubles and corn

distillers' dried solubles. Other good sources of

UGF, trace minerals, or both are alfalfa meal,

dried whey, penicillin mycelium residues, streptomyces meal, butyl fermentation solubles, dried
36 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

and condensed fermented corn extractives,

brewer's dried yeast, fishmeal, liver preparations,

other animal byproducts, feathermeal, and distillers' grains and solubles. Soybean meal apparently has both water- and fat-soluble factors,

which stimulate growth. Liver and com distillers' solubles contain certain natural chelates,

which aid in the utilization of zinc. Feathermeal contains an inorganic unidentified growth

factor.

Minerals

The quantity and quality of minerals in the

ration are important. Perhaps more important

is the relationship of one mineral to another or

to some other nutrient. Certain minerals are

needed for bone structure and tissues, whereas

others are essential for the production of enzymes and hormones. When present in inadequate amounts, nutritional deficiencies may

result. If in excess, growth may be depressed,

the effectiveness of antibiotics may be adversely

affected, and vitamins may be destroyed.

Consideration must be given to the content

in the diet of such minerals as calcium, phosphorus, iodine, sodium, manganese, magnesium,

potassium, sulfur, and the trace minerals, which

include copper, iron, zinc, molybdenum, and

selenium. Special consideration is given, in

formulating the broiler ration, to calcium, phosphorus, salt, manganese, zinc, copper, iron, and

iodine. Interrelationships between calcium and

manganese, copper and zinc, and zinc and iron

affect requirements. The requirements for minerals are given on pages 32-33.

Calcium

Except possibly for the first week or two, the

calcium content of the ration should not exceed

1 percent and the optimum results are probably

obtained at about 0.8 percent. To potentiate the

broad-spectrum antibiotics, such as chlortetracycline and oxytetracycline, the calcium content

of the feed may be lowered to about 0.4 percent.

Such a feed is usually given only for 3 days and

not during the first 3 weeks. If given too long

or when chicks are too young, rickets (leg weakness) may result. (See also p. 51.)

The principal source of calcium in broiler

feed is high-calcium ground limestone. Oystershell flour, most sources of phosphorus, and

most animal protein feeds also supply liberal

amounts of calcium for the ration.

Phosphorus

The amount and the source of phosphorus

in the diet are important as well as the relation

of the calcium to phosphorus. The vitamin D

requirement may be adversely affected by too

much phosphorus in the diet. The rate of

growth may be depressed. On the other hand,

the effect of excess fluorine is greater when phosphorus is deficient in the diet.

Most practical broiler diets will contain approximately 0.65 percent total and 0.4 percent

available phosphorus. Only 30 percent of the

phosphorus from plant sources is available. Considerable differences occur in the availability of

phosphorus from various inorganic sources. Care

should be taken in the use of phosphate supplements of low phosphorus availability and which

contain high levels of fluorine, especially in high- f^

energy rations containing added fat. The

broiler starter and finisher diets should have

about 0.4 percent of nonphytin phosphorus from

good animal or inorganic phosphorus sources,

such as feed-grade dicalcium phosphate,defluorinated phosphate, or low-fluorine rock phosphate.

Sodium

Sodium is usually added to broiler rations in

the form of salt (sodium chloride). In certain

areas the water contains relatively large amounts

of salt. Normally a broiler feed has about 0.25

percent of salt added.

Manganese

A lack of this mineral is one of the causes of

perosis, or slipped tendons, in broilers. It is

present to a certain extent in nearly all ingredients of broiler rations. The requirement for

manganese is increased by an excess of calcium

and phosphorus in combination. To insure an

adequate supply of manganese, it is usual to

add feeding-grade manganese sulfate to supply

22.7 mg. of manganese per pound of ration.

Iodine

As the broiler rations should contain 0.5 mg.

per pound of iodine, iodized salt is usually

specified. An iodine deficiency leads to an enlargement of the thyroid gland. Iodine is not

usually deficient in broiler feeds.

Zinc

A deficiency of zinc in the ration may cause

depressed grow^th, unsteady gait, shortening and

thickening of long bones, frizzled feathers, and

parakeratosis of the skin. A high calcium level

increases the severity of zinc deficiency symptoms. Natural chelates in certain ingredients

aid in the utilization of zinc. Zinc may be of

importance because it can activate certain enzyme

systems or aid in the absorption of other trace

minerals. Common sources of added zinc are

zinc carbonate, zinc oxide, and zinc chloride.

It is usual to add 50 ç.p.m. or 22.7 mg. of zinc

per pound to broiler rations.
COMMERCIAL BROILER PRODUCTION

Iron and Copper

Although the requirements listed by the

National Eesearch Council (p. 32) may be too

low, practical broiler rations normally contain

adequate amounts of iron and copper without

the use of additives. Zinc causes a strong antagonism to iron and copper, especially copper.

A deficiency of iron especially can cause anemia,

rough feathering, and lighter colored feathers

in red varieties. A deficiency of copper may

result in poor growth and a high mortality,

largely due to spontaneous aortic rupture. As

a margin of safety, 1.816 mg. of copper per

pound may be included in the finisher ration.

Molybdenum and Selenium

Chicks require molybdenum and selenium, but

37

probably added amounts are not needed in practical formulation. As a margin of safety, 0.0454

mg. of each per pound may be added.

Magnesium

Magnesium is an essential element and must

be provided from a dietary source. It is required

as an activator for many enzymes. Deficiency

symptoms are poor growth, tremors, gasping,

and convulsions. The requirement is less in the

presence of antibiotics and is greater with contamination, as with chicken feces, or with increased calcium or phosphorus in the ration.

Magnesium does not need to be added to a

practical broiler ration.

FEED AND WATER CONSUMPTION

Approximate feed and water consumption per IfiOO iroilers ^

Table 4 gives the approximate feed and water TABLE 4

consumption per 1,000 mixed-sex commercial

broilers. The feed consumption will vary with

the strain, the texture, energy, and protein content of the ration, environment (such as temperature) , management, and disease problems. Water

intake varies with the temperature, diet, and

feed intake. When the temperature is about

70° F., the water consumption varies from 1%

to 2 pounds of water for every pound of feed

consumed. Nearly 21/^ times more water is consumed per pound of feed at 90° than at 60°.

Extra salt in the diet will increase the water

consumption. Adequate quantities of water

should be available for broilers to fulfill their

individual needs. i Assume a room temperature of 70° F.

V^eek Feed pei*

day

Feed per

week

Accumulative

feed

Water

per day

1

Pounds

33

60

90

117

145

200

262

291

301

Pounds

231

420

630

819

1,015

1,400

1,834

2,037

2,107

Pounds

231

651

1,281

2,100

3,115

4,515

6,349

8,386

10,493

Gallons

7

13

19

25

31

4ß

2

3

4

5

6

7 55

8 61

9 63

RATION INGREDIENTS

Grains

Grains are included in the ration primarily as

a source of energy and secondly for their protein

and amino acid content. The low-energy grains,

barley and oats, contribute more of the B-complex vitamins and minerals than the highenergy grains. All grains are thought to carry

some unidentified growth factors. For broilers,

com is the best grain. As a source of energy, if

corn is given a value of 100, the comparative

values for the other grains would be about 88 for

wheat, 87 for barley, and 84 for oats. If used,

wheat should be coarsely ground. The feeding

value of some barleys has been improved by soaking them in water, adding certain enzyme preparations, or adding fat to the diet. Eeplacing corn

with oats usually results in slower growth and

poorer feed conversion. Oat groats, or dehuUed

oats, compare favorably with corn or wheat.

Com is a source of the carotenoid pigments,

which provide provitamin A and pigmentation

factors. In rations containing 2.5 percent or

more of alfalfa meal or 2.5 percent or more of

corn gluten meal, milo can replace half of the

yellow com when the price is right. In general,

cereals are deficient in riboflavm, vitamin B12,

choline, and phosphorus. Molasses is sometimes

used at low levels to replace com or milo.

MiUfeeds

Wheat bran improves the palatability of a

feed, but it has a low content of digestible

nutrients and is not used in high-energy rations.

Wheat middlings and shorts can be economical

sources of energy. They are a better source

of the B-G complex factors than the cereal

grains.
38 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

Fat

The amount of fat added to a commercial

broiler feed varies considerably. It may range

from about 1 to 10 percent. The relative cost

and availability of fats of acceptable quality

are important considerations. In general, the

amount to add is what is required to produce

a pound of chicken at the least possible cost.

Most broiler rations will include 2 to 4 percent

of added fat, which brings the total fat content

to 6 to 8 percent. The use of levels of fat above

2 to 3 percent in pelleted feeds must be justified

entirely on the relative cost of energy. Pelleting a low-fat ration improves both growth and

feed conversion, but pelleting a high-fat ration

does not. Mash feeds may te improved in feed

efficiency and sometimes in growth by adding

10 percent of fat. The principal reason for

improved results from both pelleting and high

fat levels is an increase in nutrient intake. Efficient feed conversion depends to a considerable

extent on the total energy content of the diet,

which is the sum of the energy derived from fat,

carbohydrate, and protein.

Fats may make mash feeds less dusty and enhance their texture and palatability. They may

also cause feed to "hold up" in bins and feeders

and may cause poor-quality pellets, which break

down to fines. Equipment has been developed

for incorporating fats in mashes and pellets.

Antioxidants are blended with fats to reduce

the rancidity and the destruction of nutritive

factors such as vitamins A and E.

For general calculations, 2,900 calories of productive energy and 3,500 calories of metabolizable energy are used for fats when exact values

are not known.

Fish Oil

The addition of fish oil may improve growth

and feed efficiency. Care must be taken to avoid

fishy flavor. The amount used will depend on

the amount and kind of fishmeal in the ration.

The maximum fish oil, without fishmeal in the

ration, is 21^ percent.

Animal Protein Products

The animal protein products—fishmeal, meat

scrap, and crabmeal—contain relatively high

quantities of the essential amino acids, vitamin

Bi2, riboflavin, and choline. Combining several

animal and vegetable protein sources is usually

advantageous. Synthetic methionine and lysine

are commercially available and their use is sometimes indicated.

Fishmeal

Most starter rations, without other sources of

animal protein or unidentified growth factoid

of the "fish" type, are improved by adding 2.5

to 10 percent of high-quality fishmeal. It is

probably not advantageous to exceed 7.5 percent

of fishmeal in the finisher rations. The level

to use will depend primarily on the kind and

cost of the fishmeal in relation to other protein

sources. Fishmeal is a good source of the B-G

complex vitamins.

Condensed Fish Solubles

Made from fish waste, condensed fish solubles

are a source of the "fish" factor and of the B-G

complex factors, especially vitamin B12. This

product is usually shipped m tank cars.

Meat Scrap

Meat scrap and meat and bone scrap are byproducts of the rendering industry. They average 50 percent in crude protein. The lower the

protein content, the higher the bone content.

The use of meat scrap in broiler rations will

depend on its relative cost as compared to fishmeal, soybean meal, feathermeal, and poultry

byproduct meal.

Crabmeal

Commercial crabmeal has the following percent constituents : Protein 32, crude fat 1, crude

fiber 13, ash 42, calcium 16, phosphorus 1.6, and

salt 3. Crabmeal can replace fishmeal and meat

and bone scrap if adjustment is made for calcium, phosphorus, and riboflavin. Crabmeal

has about the same content of unidentified

growth factors as fishmeal.

Feathermeal

The hydrolyzed feathermeals vary greatly in

protein quality. Feathermeal has a relatively

poor quality of protein compared to fishmeal,

poultry byproduct meal, or soybean meal. It

contains about 80 percent of crude protein and

800 calories of productive energy. It is relatively

high in amino acids, glycine, cystine, and arginine, but low in methionine and lysine. It contains an unidentified inorganic growth factor.

Its use is limited to 5 percent or less of the

poultr^^ ration. Results are not improved by

supplementing feathermeal with massive doses

of amino acids or extra vitamins and minerals.

Poultry Byproduct Meal

Poultry byproduct meal is usually guaranteed to

have 55 percent of crude protein and 12 percent
COMMERCIAL BROILER PRODUCTION 39

of fat. It has a productive energy content of

about 900 calories per pound, about equal to fishmeal and higher than meat and bone scrap or soybean meal. If correction is made for calcium and

phosphorus, this product can substitute for all the

meat scrap and half the fishmeal, provided at

least 2.5 percent of fishmeal remains in the ration. It is low in methionine, lysine, and cystine

and needs animal protein supplementation.

Vegetable Protein Sources

Soybean Meal

The 50 percent dehulled and 44 percent solventextracted soybean meals have largely replaced

other types in this most widely used source of

vegetable protein in broiler rations. Soybean

meal, either 50 percent dehulled or 44 percent extracted, and ground yellow corn are the principal

ingredients in most least cost broiler rations.

Soybean meals may be deficient in certain amino

acids, especially methionine, vitamin B12, and unidentified growth factors.

Cottonseed Meal

A commercial prepress solvent cottonseed meal

will contain about 600 calories of productive energy per pound (air dry basis) if it contains 44

to 47 percent of protein and has a protein solubility of 74 percent or more. It can be of equivalent nutritive value to soybean meal if fed on an

equal energy basis and is supplemented with lysine and if the soybean meal is supplemented with

methionine. Fifty percent protein dehulled soybean meal will have about 640 calories per pound.

Cottonseed meal will have a higher crude fiber

content than soybean meal. It is best used as partial replacement of other vegetable protein

sources.

Corn Gluten Meal

Corn gluten meal is used up to 5 percent of the

ration as a protein source to replace part of the

soybean meal, and it is used at about 2 percent

of the ration to improve pigmentation, especially

the finisher diet and when yellow cornmeal is replaced by nonpigmented grains. It is low in lysine, arginine, and tryptophan.

Sources of Natural Vitamins and

Unidentified Growth Factors

Distillers^ Dried Solubles

Corn and milo distillers' dried solubles are used

primarily as a source of "fermentation" unidentified growth factors at levels of 2.5 or 5.0 percent, replacing soybean meal and ground corn.

They are a good source of energy and the B-G

complex vitamins.

Fermentation Products

Various products, both primary and byproduct,

are excellent sources of the unidentified growth

factors. They are often high in vitamins and

may contam residual amounts of antibiotics.

Alfalfa Meal

Although alfalfa meal is included in the broiler

ration primarily for its provitamin A, betacarotene activity, and its xanthophyll content, it

also contains substantial amounts of vitamins, including vitamins E and K. Most commercial

alfalfa meals have an antioxidant, such as ethoxyqum and fat added, are blended, stored under

gas, and ground before use. With the advent of

high-energy rations, there has been less 17 percent protein meal used and a trend toward 20

percent meals in broiler feeds. When nonpigmented grains replace yellow corn, 2 percent of

alfalfa meal is often included in the ration.

Dried Whey

Some rations are improved by the addition of

the "whey" unidentified growth factor. Because

of its laxative effect and sometimes its cost, the

use of dried whey is generally restricted to a

maximum of 21/2 percent of the ration.

Antioxidants

Antioxidants are used in broiler rations to protect against rancidity and the oxidative destruction of vitamins A and E in storage, mixing, and

pelleting and to increase the utilization of provitamin A from alfalfa meal. Butylated hydroxytoluene (BHT) and 1,2-dihydro 6-ethoxy2,2,4-trimethylquinoline (Santoquin and Dethoxyquin) are common antioxidants for broiler

feeds. They are used at a level of 0.0125 percent

to prevent encephalomalacia and the destruction

of the fat-soluble vitamins A and E. They do not

improve pigmentation or the dietary utilization

of xanthophyll in broilers unless oxidizing agents,

such as lineoleic acid, are present. Antioxidants

do not appear to have a specific function in preventing selenium and vitamin E-induced deficiencies.

Coccidiostats

A coccidiostat is used in most broiler rations to

prevent coccidiosis. The suggested level is that

recommended by the manufacturer. Care should

be taken to limit the percentage used to the requirements of the situation and to be sure the

drug is removed from the ration at marketing

time according to regulations. When a coccidiostat is used, special consideration should be given

to the vitamin A and K content of the ration.
40 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

Some of the coccidiostats commonly used in

broiler rations are as follows:

Amprolium, Amprol 25 percent (l-(4-amino-2-n-propyl-5-

pyrimidinylmethyl)-2-picolinium chloride hydrochloride)

Arzene (arsenosobenzene)

Glycarbylamide, Glycamide (4,5-imidazole-dicarboxamide) . ^ ^ ^ Nicarbazin, Nicarb (4,4'-dinitrocarbanilide-2-nydroxy-4,

6-dimethylpyrimidine )

Nitrofurazone, NFZ ( 5-nitro-2-furaldehyde semicarbazone) /^ ... o

Nitrofurazone and furazolidone, Bifuran (5-nitro-^-

furaldehyde semicarbazone and n-(5-nitro-2-furfurylidene ) -3-amino-2-oxazolidone )

Nitrophenide, Megasul (m,m-dinitrodiphenyldisulfide)

Polystat ( acetyl- ( para-nitrophenyl ) -sulfanilamide, dibutyltin dilaurate, dinitrodiphenylsulfonylethylenediamine, 3-nitro-4-hydroxyphenylarsonic acid)

Sulfaquinoxaline, SQ (2-sulfanilamidoquinoxaline)

Trithiadol (bithionol and methiotriazamine )

Unistat ( acetyl- ( para-nitrophenyl ) -sulfanilamide, 3,5-

dinitrobenzamide, 3-nitro-4-hydroxyphenylarsonic acid)

Whitsyn (2,4-diamino-5-(para-chlorophenyl) 6-ethyl pyrimidine and 2-sulfanilamidoquinoxaline)

Zoalene, Zoamix (3,5-dinitro-o-toluamide)

Antibiotics

Most broiler rations contain antibiotics at the

relatively low levels of 4 to 10 grams per ton to

stimulate growth. Some of those commonly used

are penicillin, bacitracin, zinc bacitracin, erythromycin, chlortetracycline, and oxytetracycline.

Improved results are sometimes obtained by combining antibiotics or by changing antibiotics

periodically.

Chicks in contaminated quarters may show depressed growth from the fourth to the seventh

day. This symptom was not observed when an

antibiotic was included in the diet. The feed is

apparently poorly utilized from the 4th to the

12th days by the chicks not getting the antibiotic. Fecal excretion is greater when an antibiotic is not given. Antibiotics seemingly improve

growth and feed utilization by affecting the

micro-organisms, which reduce absorption of nutrients. Eesults from antibiotics are highly variable. Sometimes males respond when females do

not. The age and extent to which different breeds

and strains respond may vary with different antibiotics. Reasons for the complexity of antibiotic

action are not know^n.

Levels of 100 grams per ton or more are used

in some prestarter rations to be fed for the first

14 to 21 days. High levels of antibiotics are also

used for disease control.

The broad-spectrum antibiotics—chlortetracycline and oxytetracycline—are often potentiated

when used to control certain diseases. The

amount and the sources of certain minerals in the

ration affect the concentration of the antibiotics

in the blood of the bird. The manufacturer's

recommendations should be followed in the use

of antibiotics.

Antibiotics commonly used in broiler rations

and their principal functions are as follows:

Antibiotic

Aureomycin, aurofac

chlortetracycline _.

Function i

Growth promotion ; aid in

prevention and control of

chronic respiratory disease (CRD) and synovitis.

Bacitracin Growth promotion; aid in

prevention and control of

CRD and blue comb ; meet

stress conditions.

Bacitracin, manganese — Growth promotion.

Bacitracin méthylène

disalicylate See Bacitracin.

Bacitracin, zinc Do.

Erythromycin, .Gallimycin,

erythromycin thiocyanate Growth promotion; aid in

prevention and control of

CRD.

Oleandomycin Growth stimulation.

Oxytetracycline, oxytetracycline hydrochloride,

terramycin Growth promotion; aid in

reduction of CRD mortality; aid in prevention and

control of synovitis.

Penicillin, procaine

penicillin ___ Growth promotion; aid in

prevention and treatment

of CRD, blue comb, and

synovitis.

Penicillin (from procaine

penicillin), streptomycin Growth promotion; treatment of CRD and blue

comb.

iThe function of the antibiotic is dependent on the

level of the drug in the feed. For more detailed information, refer to Food and Drug Administration Antibiotic Regulations, obtainable from the Office of Information, Food and Drug Administration, 200 C St. SW.,

Washington, D.C. 20204.

Antibiotic Potentiation

When broad-spectrum antibiotics, such as

chlortetracycline and oxytetracycline, are used to

control diseases, it is economical and feasible to

potentiate them.

Calcium is the principal inhibitor of antibiotics

in poultry feeds. On the other hand, the calcium

salt, calcium sulfate, is less inhibitory and can be

used to advantage. Sodium sulfate also can be

used as a substitute for calcium carbonate or dicalcium phosphate to increase concentration of

the antibiotics in the blood. Due to its tendency

to increase water consumption when used in excessive amounts, it is advisable to restrict the percent of sodium sulfate to 1.5 in potentiating formulas. When using formulas to potentiate antibiotics, the directions of the manufacturer of the

antibiotic should be followed. If it is approved

for use, terephthalic acid (T.P.A.) will also enhance the therapeutic efficiency of Aureomycin.
COMMERCIAL BROILER PRODUCTION 41

Arsenicals

Low levels of certain arsenicals have a growth

effect similar to that of antibiotics. Arsenicals

and antibiotics usually give a greater growth response when combined than if used separately.

For example, the addition of arsanilic acid or "3-

nitro" to bacitracin méthylène disalicylate will

give a better gain and feed conversion than the

antibiotic alone. The pigmentation of the birds

fed on arsenicals is often improved. Arsanilic

acid (p-aminobenzenarsonic acid) or sodium arsanilate and 3-nitro-4-hydroxyphenylarsonic acid

are the commonly accepted arsenical sources.

Arsanilic acid or sodium arsanilate is used at 45

to 90 grams per ton and "3-nitro" at 22.5 to 45

grams per ton of ration. The directions of the

manufacturer should be followed for the other

compounds.

Hormones

Dienestrol diacetate, a synthetic compound with

hormonelike activity, has been mixed with feed to

increase fat deposition and to give improved carcass quality. When any product of this kind is

used, the manufacturer's directions and the Food

and Drug Administration's regulations should be

followed.

The Consumer and Marketing Service's poultry

inspection program includes laboratory testing

procedures for determining chemical residues in

poultry products. Failure to heed directions for

use and withdrawal periods may result in poultry products being condemned as unwholesome.

Xanthophyll

In most areas, customers prefer highly pigmented birds. The variation in skin color is due

primarily to breed, method of scald, and the xanthophylls in the feed ingredients of the rations.

Xanthophylls are a group of carotenoid pigments.

Good pigmentation usually results when at least

6.4 mg. of xanthophyll from natural sources are

present in each pound of feed. If low carotenoid

ingredients, such as milo or white corn, are used

in a starter ration, good pigmentation can still be

obtained by using about 8 mg. of xanthophyll

per pound in a finisher ration. Most finishers

have at least this level. Approximate available

xanthophyll values for ingredients mostly responsible for pigmentation in broilers are given

on page 43.

Miscellaneous Additives

Some of the miscellaneous additives used in

broiler rations and their functions are as follows :

Additive Function

Aterrimin Growth stimulant.

Dynafac Growth promotion and feed

conversion.

FurazoHdone, nf-180 Chemotherapeutic agent for

growth promotion and

prevention and treatment

of fowl typhoid, paratyphoid, pullorum disease,

and CRD.

Neomycin, neomycin

sulfate

Nystatin, Mycostatin

Reserpine

Sulfathiazole sodium

Used for bacterial enteritis.

For prevention and treatment of crop mycosis and

mycotic diarrhea.

To combat stress conditions.

To control spread of infectious coryza.

RATION FORMULATION

The formulation of a practical broiler feed is

the combining of selected ingredients to meet

specific nutritive requirements and often processing and pricing limitations. Ingredients are classified on the basis of the nutrient in which they

are rich ; for example, carbohydrates, vegetable

proteins, animal proteins, vitamins, stabilized

fats, minerals, and miscellaneous additives.

The choice of ingredients within a class de-.

pends largely on composition, availability, and

price. The feed formulator chooses the ingredients that, when combined, provide the required

nutritive value at the lowest possible cost. The

value of ingredients and formulated feeds should,

whenever possible, be based on actual feeding results. When a product of doubtful value is used

in an effort to provide plenty of a nutrient, the

result can be a dangerous imbalance ; for example,

the use of feathermeal to supply all the protein

in a ration if it happened to be the cheapest

source of protein.

The approximate composition of complete

broiler rations by ingredient classes can be used

as a guide and is as follows:

Percent of

Ingredient class ration

Carbohydrates 1 55-60

Vegetable proteins ^ 20-30

Animal proteins ^ 2.5-20

Vitamins ^ 2-8

Stabilized fats s Ù-8

1 Grains and grain byproducts : Corn, wheat, barley,

oats, millet, shorts, middlings, red dog, hominy feed, etc.

2 Soybean, corn gluten, cottonseed, peanut meals.

3 Fishmeal, fish solubles, meat scrap, liver meal, dried

milk, feathermeal, poultry byproduct meal, etc.

4 Commercial vitamin supplements, alfalfa, dried whey,

dried yeast, distillers' solubles, fermentation solubles, etc.

5 Grease, tallow, poultry oil, etc.
42 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

Mineral carriers« 1-3

Miscellaneous "^

«Limestone flour, oystershell flour, dicalcium phosphate, steamed bonemeal, defluorinated superphosphate,

defluorinated rock phosphate, iodized salt, manganese

sulfate, etc.

''^ Trace amounts of these ingredients may be added.

Many are present in commercial rations, but some may

not be necessary under all conditions. The group includes antibiotics, coccidiostats, arsenicals, hormones, antioxidants, and xanthophyll.

The specifications or allowances for practical

broiler rations are constantly changing. For a

tentative set for starter and finisher rations used

as a basis for linear programing, see tables 6

and 7 (p.46).

For the composition of ingredients commonly

used in poultry feeding, see Joint United StatesCanadian Tables of Composition.* These values

will prove a reliable guide in choosing and using

ingredients. Suppliers of ingredients will usually furnish the analysis of their products as well

as guarantees. Table 5 gives the composition

of selected ingredients to illustrate an example in

linear programing.

Wlienever possible the formulator should utilize the actual chemical analyses of the ingredients to be used. In addition, digestibility, palatability, and the effect on the appearance of the

bird should be considered. Actual feeding tests,

when available, are of greatest importance.

Attention must be paid to the interrelation of

nutritional factors, some of which have been indicated (see pp. 36-37). Examples are the proteinamino acid and the calcium-phosphorus ratios.

Proper nutrition balance is especially important

when environmental heat is excessively high.

The productive energy of practical broiler

feeds probably varies from 900 to 1,100 calories

per pound and the metabolizable energy from

1,350 to 1,500 calories per pound. The optimum

ratio of calories to protein content may be different depending primarily on the quality of the

protein. As a guide, the optimum ratio for starting diets is" usuallj^ considered to be 42 to 45

calories of productive energy and 60 to 65 calories of metabolizable energy to each percent of

crude protein in the ration. The corresponding

figures for finishing diets are 48 to 53 and 69 to

75 and for withdrawal diets, 60 to 85. The ratios

vary with the quality of the protein. The better

the balance of the amino acids, the wider the

ratio that can be used. When the ratio is low, less

fat is deposited. The protein requirement of 20

percent (p. 32) will meet the approximate mini4 NATIONAL ACADEMY OF SCIENCES, NATIONAL RESEARCH

COUNCIL, JOINT UNITED STATES-CANADIAN TABLES OF COMPOSITION. Pub. 659, 80 pp. Washington, D.C. 1959.

mum requirement for growth in rations containing 900 calories of productive energy per pound.

Since the food intake of the growing broiler is

proportionate to its energy requirements, the protein, amino acid, vitamin, and mineral levels

needed in the ration are related to the energy

content of the ration. As the energy content of

the ration increases to 1,450 calories of productive energy, as by the addition of high levels of

dietary fat, the needed level of all required nutrients, especially vitamins and minerals, is substantially increased. This is also true when feed

intake is reduced for other reasons.

As the energy content of the ration increases,

the percent protein required also increases if the

best growth and feed conversion are desired.

Some feed formulators maintain a constant ratio

of calories to protein content for their starter,

finisher, and withdrawal feeds. In practical formulation, where energy and protein levels do not

change much, consideration should be given to

expressing amino acid requirements on an energy

basis. The ratios of amino acids to energy would

appear to be a more direct means of insuring

amino acid adequacy and thus avoid the necessity of considering the ratio of calories to protein as such.

Requirements for the amino acids are all interrelated, and they are related to the levels of total

protein and energy. In general, the levels required of the amino acids, expressed as a percent

of the ration, are higher as the protein content

increases. As an example, if the protein content

is 24 percent, the percent of the ration for each

amino acid can be obtained by multiplying the

percentages given on page 33 for a ration having

a 20 percent protein level by 24/20 or factor 1.2.

Since protein quality may vary markedly, recent

guides for use in the formulation of poultry feeds

have expressed amino acid levels as a direct function of the energy level. Up to the optimum

energy utilization by the bird, the requirement

for methionine, lysine, glycine, and arginine goes

up as the energy content of the ration increases.

In most broiler rations the sulfur amino acids

(methionine and cystine) and lysine have to be

considered most critically. The indications are

that the minimum levels to be used should be on

an energy basis. For example, for best growth

and feed efficiency, the ratio of minimum sulfur

amino acids (methionine and cystine) to metabolizable energy should be about 0.53 percent for

starters and 0.48 percent for finishers. The corresponding values on the basis of productive

energy would be obtained by multiplying by 1.43.

Because of the varying response of amino acid

supplementation with different diets, other factors also may have to be considered. Whenever

feed intake is decreased, for example in hot

weather, all nutrients should be increased in rela-
COMMERCIAL BROILER PRODUCTION" 43

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44 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

tion to energy by about 7.5 percent or in proportion to the drop in feed consumption when it is

known. To meet the sulfur amino acid levels

needed by broilers, it may be necessary to add to

high corn rations from 0.5 to 1.5 pounds per ton

of methionine and to high milo diets as much as

2 pounds.

On analysis sheets the protein, fat, fiber, calcium, phosphorus, salt, and amino acids are usually listed as percentages, vitamin A as U.S.P.

units per pound, and vitamin D3 as international

chick units (I.C.U.) per pound. The rest of the

vitamins, except vitamin B12, and the minerals

are listed as milligrams per pound. The vitamin

B12 content is sometimes given in micrograms

(1/1,000 mg.) per pound. Sometimes minerals,

coccidiostats, and other additives are given in

percentages or parts per million (p.p.m.). The

conversion formula is 0.01 percent equals 100

p.p.m. equals 90.8 grams per ton. To shift percentages to parts per million, the decimal point

is shifted to the right four places. There are

454 grams in a pound. To convert milligrams

per pound to grams per ton, multiply by 2. To

convert parts per million to grams per ton, multiply by 0.908.

When formulating rations, the source of phosphorus must be considered. The phosphorus from

sources other than supplements is only about 30

percent available and that from various supplements varies greatly. Both the total and the

available phosphorus content of the ration must

be considered. If an 18 percent dicalcium phosphorus product (18 percent of phosphorus, 26

percent of calcium) is listed, steam bonemeal or

defluorinated rock phosphate may replace it on a

phosphorus content basis. If a 14 percent product with equal availability is used, calcium must

be adjusted.

Thirty percent of milo, 20 percent of wheat,

both coarsely ground, or 10 percent of hominy

feed can replace yellow cornmeal. If milo or

wheat is used, the birds will be less pigmented. If

milo replaces corn, the methionine content of the

ration will probably have to be increased. For

each 100 pounds of com replaced by wheat or

milo, 200,000 U.S.P. units of vitamin A should

be added to the ration. If stored ingredients are

used, the vitamin A content should be increased

1,000 U.S.P. units per pound. To meet stress

conditions, 0.5 mg. of menadione sodium sulfite

(vitamin K3), or its equivalent in vitamin Ki,

per pound of ration is added.

It is usual to specify technical grade or 70

percent feeding-grade manganese sulfate, 95

percent calcium carbonate limestone, and 100

percent choline chloride, or their equivalents.

Choline chloride (100 percent) contains 86.79

percent of choline. One pound of 100 percent

choline chloride contains 394,027 mg. of choline.

If calcium pantothenate is used, the amount

should depend on the guarantee of d-pantothenic

acid activity for the product. The "1" form is

inactive. A half pound of manganese sulfate

(70 percent) per ton of ration will provide 50

grams of manganese. To supply the usual 22.7

mg. per pound of zinc, 45.4 grams of zinc must

be added per ton of ration. To supply this will

require either 104 grams of zinc chloride or 62

grams of zinc oxide per ton of ration. An

equivalent amount of zinc may be used from

other acceptable sources.

Factors Affecting Feathering

The factors affecting feathering most include

protein, folie acid, biotin, pantothenic acid, and

vitamin B12. Diets low in protein or with

poor amino acid balance will give poor feathering. In general, factors that promote rapid

growth rate also induce good feathering.

Linear Programing

More economical production of broilers has

resulted from linear programing in feed formulation. Linear programing is the formulation

of rations to meet specified nutritional requirements and yet cost less; hence the name least

cost diets. To be practical, the solution must

result in least cost manufacturing. It is necessary for the nutritionist programer to have a

list of representative delivered prices of all the

ingredients to be considered, their nutrient content, nutrient specifications for the feed, and

nutritional restrictions, including fixed maximum

and minimum amounts.

Linear programing sometimes includes nonnutritive restraints. These may be determined

by the lack of availability of ingredients and

their physical properties, whether bag or bulk.

Machine formulation is of value in planning

nutritional research, better utilization of the

time of the nutritionist, more rapid application

of research results, greater savings, better evaluation of the value of ingredients, more precise

nutrient content and balance of rations, and

better production management in the mill.

It is not necessary and probably is inadvisable

for most firms to have a computer. The size

needed is so large that such a computer could

not generally be utilized enough hours to be

effectively employed. The use of a computing

service is usually the only feasible way to get

the job done. When the prices of ingredients,

such as corn or soybean meal, fluctuate widely,

it may be feasible to reformulate feeds as often

as weekly for maximum benefits from programing.

Linear programing has its limitations. More

research is needed on the composition of many
COMMERCIAL BROILER PRODUCTION 45

ingredients and especially on rapid methods of only as good as the assumptions put into the

determining their biological value. For ex- program. Future benefits of linear programing

ample, the protein of corn and milo and the will depend on the improved skill of the nutriamino acid content of fishmeal vary considerably. tionist-buyer-programer team and the better

Data are insufficient on the nutrient content and nutrient description of ingredients. Actual feedfeeding value of ingredients, such as feather- ing results are, in the meantime, the best assurmeal, poultry byproduct meal, blood meal, corn anee of correct formulation and should supplegluten feed, hominy feed, and molasses. The ment the rapid precise calculations of the comvalue of ingredients differs depending on the puter.

level used and how they are combined with other Table 6 gives an example of the restrictions

ingredients. The level of fat is an example. In placed on nutrients and table 7 the ingredient

addition, there are nonnutritive restraints. Ex- limitations in linear programing for least cost

amples are the availability of ingredients, mill broiler formulas. Table 8 gives examples of

storage facilities, size of the mixer, fire danger typical broiler starter and finisher formulas

during storage, unit size, tag registrations, and resulting from the model chosen. Least cost

such physical characters of ingredients as flow- rations may give as good results as manually

ability, color, odor, palatability, and pelletability. computed rations at several dollars less per ton.

These restraints vary with every feed-manu- The formulas given are good, but are not recomfacturing plant. mended as meeting any but the conditions of this

Considerable experience is needed in knowing particular program at the prices used. When

how to adjust for seasonable effects, to price these formulas were used for 43,693 broilers at

ingredients, to arrive at safety factors, to place the South Central Poultry Eesearch Laboratory,

restriction and restraints, and to determine what State College, Miss., the average weight of the

cost differences justify the usual high cost of birds at 9 weeks of age was 3.96 pounds, the

reformulation. Linear programing is helping feed conversion 2.2 pounds, and the mortality

ingredient purchasing by "shadow pricing." only 2.1 percent.

This is the process by which ingredients, through • / i i >TX

restrictions, are rejected at certain prices and 1 he constant premix (table 7) was as follows:

used in larger amounts at lower prices. The ^*^^ Amount

machine determines the "slack" and the "excess" Vitamin A palmitate (stability

values below and above the maximum and the viiZfr^ ^ ' ^^•^' ?nlj onn'ííín

minimum restrictions, respectively. Riboflavin mg 800

Care must be used in establishing a restric- Niacin mg 5,000

tion, since the use of a maximum restriction on a d-Pantothenic acid ^___mg 1,600

nutrient that could be present in excess with no ^^^^'""-^ chloride mg____ 80,000

«? . A -v,, . ,T x ü xi Vitamm Bio mg 1.200

enect on periormance will increase the cost oi the Ethoxyquin grams 12

formula without improving its nutritive value. Menadione sodium bisulfite mg 200

This is particularly true with amino acids that Iodine percent ^ .050

are not first limiters. If the amino acids are Manganese — do 3.000

restricted, it may not be necessary or advisable Copper IZIZIiriZIZIIIIZZZIZIIIIIZZdoIIIIIZ .080

to restrict the protein content. A similar situa- zinc do_ Í881

tion may exist with fat and energy. However,

the amino acid-energy ratios should not be over- Concentrates and Premixes

looked.

The ratio of percent of methionine and cystine Feed mixers often find it advantageous to use

to megacalories (1,000 calories) of metaboliz- one or more manufactured concentrates for

able energy per pound should be about 0.56 for blending with ground yellow corn or other

the starter and 0.51 for the finisher ration, and grains. It is possible to buy broiler starter and

for lysine the ratio should be 0.87 for the broiler finisher concentrates or a single concenstarter and 0.71 for the finisher ration. These trate for producing both feeds. A single convalues may be converted to actual percentages centrate for several feeds is usually less econeeded in the feed by multiplying them directly nomical and less satisfactory than separate

by the therms (1,000 calories) of metabolizable concentrates for each feed. Generally 800

energy per pound. For example, for a feed with pounds of ground yellow corn are used to pro1,400 calories, multiply by 1.4 (1.4X0.56=0.78) duce a ton of broiler starter feed. To make

to obtain the requirement for the total sulfur finishers, 700 and sometimes only 600 pounds

amino acids (methionine and cystine) for the of broiler finisher concentrate are mixed with

starter of 0.78. 1,300 or 1,400 pounds of com.

The manipulations involved in determining the A multipurpose concentrate must be formbest formula will depend on the specific program ulated to meet its most critical use. Special conand the computer used. A computer solution is centrâtes, superconcentrates, or premixes are
46 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

TABLE 6.—Typical nutrient specifiGations for

least cost iroiler rations ^

Item

Maximum pounds

Metabolizable calories

per pound, exactly number

Protein percent

Fat do

Fiber, maximum pounds

Calcium, exact do

Inorganic phosphorus

available, exactly do

Arginine ^ do

Lysine 3 do

Methionine ^ do

Methionine^ and cystine do

Tryptophan ^ do

Xanthophyll ^ mg

Broiler

starter

1,000

1,400

(^)

(2)

35

4.5

12

12

4.1

7.8

2.1

6,000

Broiler

finisher

1,000

1,450

(2)

(2)

35

7

3.5

10.8

10.8

3.7

7,0

1.9

8,000

1 All minimum unless otherwise indicated.

2 Unrestricted.

3 Per 1,400 calories.

•* Per 1,000 calories.

TABLE 7.—Typical ingredient restrictions for

broiler formulas in linear programing

Item

Pounds, maximum

Soybean meal, 50 percent

Fishmeal, 60 percent :

Minimum

Maximum

Poultry byproduct meal, 55 percent :

Minimum

Maximum

Corn gluten meal, maximum

Prostrep, exact -.

"3-nitro," 45 grams, exact

or

Progen arsanilic acid, 90 grams,

exact

Alfalfa meal, 20 percent :

Minimum

Maximum

Alfalfa meal, 17 percent :

Minimum

Maximum

Dried whey (MNC), exact

Molasses, cane :

Minimum

Maximum

Poultry oil, maximum

Salt, plain, exact

Amprol plus coccidiostat __

Constant premix, exact —

Broiler

starter

Pounds

1,000

50

150

50

400

200

.375

.5

20

40

20

40

25

50

60

120

5

.5

2.5

Broiler

finisher

Pounds

1,000

(1)

50

150

50

400

200

.25

.5

.5

20

40

20

40

50

60

120

5

.5

2.5

1 Unrestricted.

also available for blending with bulk ingredients,

such as soybean meal, corn gluten meal, poultry

byproduct meal, feathermeal, meat and bone

TABLE 8.—Examples of iroiler starter and finisher

rations resulting from linear programing model

used

Item

Alfalfa meal, 17 percent

Fishmeal, 60 percent

Poultry byproduct meal, 55 percent

Corn, ground yellow. No. 2

Corn gluten meal

Soybean meal, 50 percent

Poultry oil

Dried whey (MNC)

dl-Methionine

Limestone, ground

Salt, plain

Amprol plus coccidiostat

Prostrep

Progen arsanilic acid, 90 grams—

Constant premix (see table 7)

Total -,

Starter Finisher

''E" "F"

Pounds Pounds

40 40

100 160

200

1,050 1,200

100 100

300 340

130 130

50

.25

11 12.5

11 10

1 1

.75 .5

1 1

5 5

2,000.00 2,000.0

scrap, and com, to make complete feeds. The

directions of the manufacturer of the concentrate, superconcentrate, or premix should be

followed.

Because premixing is costly and the number

of available bins and their capacity are usually

limited, the number and unit size of ingredients

often must be considered.

Broiler Feeds

Prestarter feeds often are the same as starter

feeds, except for one or more additives—generally an antibiotic used at a high level. When some

antibiotics are used at a high level in the prestarter, a coccidiostat is not needed. Prestarters

are usually fed in mash form.

Starter feeds may be fed as mash, crumbles,

or pellets. Birds prefer a medium-coarse feed

to a fine-textured one. The grind of the com

in the mash is especially important. The use

of crumbles and pellets generally results in

enough better growth and feed efficiency and in

lower waste to more than offset their cost of

production. The breaking down of pellets to

crumbles or fines is a major problem with pellets,

especially when they are handled in bulk and

when the formula is high in fat. The effect of

pelleting on the value of the feed is less as the

level of the energy, and especially the fat content, of the feed increases.

Broiler finisher feeds are generally lower in

protein and higher in fat content than are

starters.
COMMERCIAL BROILER PRODUCTION

Feed Preparation and Distribution

In feed preparation, thorough mixing is important. Technical assistance is often worthwhile in laying out the production unit and in

the selection of the equipment for it. Accuracy

in measuring and thoroughness in blending are

two major considerations.

Broiler feeds are mixed and delivered to the

farm in many different ways. A complete feed

may be manufactured. This is usually done in

a rather large mill, often strategically located as

to incoming and outgoing shipments. Many

9 integrated broiler operations manufacture complete feeds. Feeds may be shipped in bulk cars

to depots in producing areas, where facilities

are available for loading bulk trucks. Another

method is to manufacture concentrates in mills

and ship them in sacks or bulk to mixing facilities in producing areas, where feeds are mixed to

go to the farms in sacks or bulk. The bulk feed is

angered or blown into storage bins at the poultry

house. Most broiler growers generally use one

of these two methods.

A grower may take his grain to a mill to be

ground and custom mixed. A concentrate is

generally used. It is possible to get on-the-farm

mixing units. These usually grind home-grown

grain and combine it with a concentrate in one

operation. Mobile mills eliminate the costly

investment in mixing equipment. They go to

the farm, grind and mix feed, and put it into

a bin or sacks. The service is sometimes used

by the grower who produces and stores his own

grain.

The size of the operation and its location,

especially in relation to the principal ingredients.

47

and the availability and cost of reliable labor

are important in deciding whether complete

rations are to be manufactured, concentrates or

premixes used in a stationary or mobile mill, or

the practice of mixing on the farm is followed.

No method is best for all conditions. Most feeds

are delivered in bulk from a centrally located

mill. The use of bulk trucks has increased with

the expansion in the size of broiler enterprises.

Judging Feed Value

When feeds are tagged, a limited amount of

information can be obtained from the guaranteed

analysis. When feeds are formulated, it is possible to show on paper how close the calculated

analysis of the feed compares with the nutritional requirements. A laboratory examination

of the feed gives valuable information as to the

accuracy of formulation and preparation. No

method of calculation or analysis will predetermine the actual nutritional value of a feed.

Properly run feeding tests are the best way to

arrive at the comparative value of feeds.

If the feeds being compared are fed to one

or more separate flocks of broilers, care should

be taken to have the flocks of similar breeding

and with equal numbers of chickens of each sex.

Accurate records should be kept of the mortality,

the feed consumed, its cost, the pounds of meat

sold, and the total income. With these figures,

it is possible to calculate and compare the

pounds of feed required to produce a pound

of meat, the feed cost of producing a pound of

meat, and the income over feed cost. The calculations will assist the feeder in deciding which

feed or feed formula is best suited to his purpose.

MARKETING

The price received for the product largely

determines whether an operation is successful or

not. Supply greatly affects price. To try to

anticipate the price, you will need to consider

such factors as number of broiler breeders tested,

number of breeder pullet replacements (day-old

basis), number of eggs set, number of chicks

placed, extent of Government buying, and competition of turkeys and other meat products.

The number of breeders tested is an indication of

what may happen in 12 months; the pullet replacements, 6 or 7 months ahead; eggs set, 8

months; and chicks placed, 9 to 10 weeks. The

effect of the first two factors may be influenced

if lots of pullets are brought in earlier than

usual, the breeder hens are kept longer than

usual, and less floor space is allowed per breeder

in houses.

The farm price used for settling the grower

contract may be based on the quoted price for

broilers from the Federal-State Market News

Service for the particular area. In the case of

the integrated operation, it may depend on what

the processor gets when he sells. Price may not

be considered in a contract. The trend is away

from farm base calculations to ready-to-cook

prices.

Marketing Cycle

Normally the demand is a third greater for

broilers in June and July than in the fall. The

least demand is usually around Thanksgiving

and Christmas, when turkeys, roasters, and

capons are often preferred. The consumption

tends toward smaller broilers in the summer and

larger ones in the fall and winter. Most broiler

operators recognize the seasonality of demand

and plan accordingly. Consideration is being

given to freezing some birds in the August-toDecember period for sale during the January-toJune period, when the price has been as much as
48 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE

7 percent higher. Two factors retard this trend

—^the higher cost of preparing frozen birds and

consumer resistance to them. A consumer may

buy a chilled bird, take it home, and freeze it,

but he resists buying the frozen broilers when

chilled icepacked ones are available. Eoasters

weighing 4 to 8 pounds are shipped in frozen,

ready-to-cook condition. The principal markets

are New York and Chicago.

Processing, including evisceration, is done now

in the areas where the broilers are produced.

The ready-to-cook broiler-fryers are icepacked

or dry chilled and shipped in fresh form in

wholesale quantities by refrigerated trucks to

market. The broiler cutting is being shifted

from the retailer to the processor, where packs

are sized to the specifications of the buyer,

marked as to weight, and, if desired, prepriced.

Marketing Areas and Practices

Broilers from Maine are sent to Boston and

local New England markets. The rest of the

Northeast (Baltimore, Philadelphia, Washington, D.C., New York) is served principally by

Delmarva. The midwestern markets used to be

supplied from the Delmarva Peninsula. Some

of the broilers from the Southeast go to the

Northeast, but principally they are trucked to

Florida, Atlanta, New Orleans, Dallas, Chicago,

Detroit, Cleveland, and Columbus markets. The

South Central States, especially Arkansas, Alabama, and Mississippi, ship to Jacksonville,

Miami, New Orleans, Dallas, Chicago, St. Louis,

Omaha, Salt Lake City, Los Angeles, San Francisco, and Seattle. Broiler production will mcrease in California, especially if growers there

can produce the birds at a low enough cost to

compete with the south-central operations and if

the returns are at least comparable with other

ventures. Most of the Texas production is consumed in Texas.

Frozen export packs have become an important

outlet for American-produced broilers. Exporting broilers has the effect of raising prices domestically. Indirectly it increases the demand

for materials and services involved in the production of broilers.

It is usual to market broilers at 10 to 11 weeks

in the Maine and Delmarva areas and 9 to 91/2

weeks in the Southeast. There is no best time.

When fixed and chick costs are high and feed

costs are low, it usually is more profitable to carry

birds longer because there are more pounds over

which to spread the fixed costs and the lower feed

conversion is not so costly. The processing cost

per pound is also less with a heavier bird. The

risk, mortality, and increase of breast blisters are

factors to consider when birds are kept to heavier

weights. When the price is poor, it is often better to market birds as small as the processor will

take without cutting the price. In general, broilers should be sold when they reach the normal

weight for the processor.

The quality of an individual carcass depends on

such factors as the shape or conformation, how

well it is fleshed, the amount and distribution of

fat, and its freedom from such defects as breast

blisters, pinfeathers, disjointed and broken bones,

missing parts, discolored skin and flesh, freezer

burn, and cuts, tears, and missing skin. Poultry

is downgraded if bruising occurs to any extent.

Much of the bruising is caused by the way the

birds are handled between the farm and the proc- ^^

essing plant (see p. 50).

Several management practices will reduce

downgrading. A fasting period of 4 hours prior

to slaughter is sufficient for the intestinal contents to be reduced to a satisfactory point so that

contamination is at a minimum. Give plenty of

water as long as possible up to the time of slaughter. Have hanging waterers. Many tears and

cuts result from birds flying against inflexible

floor waterers. Watch for and eliminate places

where birds can roost. Be careful not to scare

birds at any time. Use portable wire screens and

blue light for catching birds. Have an outside

door in each pen. In wide houses, have doors on

each side. Remove all feeders, waterers, and

other obstructions during loading, as they may

cause cuts and bruises.

Flesh bruises are responsible for more than half

of the undergrades in most processing plants.

Breast bruises are the most common and costly of

the injuries. Rough handling by catching crews

is the main cause of bruising, including birds hitting partitions and slamming birds into coops.

These crews should catch and carry birds by

their shanks, not the drumsticks. They should

make small drives of about 200 birds and use

care in catching and handling the birds.

The assembly operation at the processing plant

should be carefully supervised. Coops should not

be dropped. Birds should be handled by their

shanks. Care should be taken to see that the

birds do not hit the wall or any object while on

the assembly line. Several investigators have suggested that it might be better to load all birds as

needed for processing and run a double shift at

the processing plant rather than to load most of

the birds at night and process most of them during the day.

The cost of catching and hauling poultry is

substantial. It can be reduced by increasing the

efficiency of individual farms. An important consideration is the location and size of the farms

supplying live birds. An outside door for each

pen or several outside doors for each house increase efficiency. Assembly costs per pound decline as the density of the supply area increases.

It is advantageous to have larger producing units
COMMERCIAL BROILER PRODUCTION 49

close to the processing plant. High total volume

allows the use of trucks of larger capacity, higher

output per man-hour, less overhead, and greater

ability to handle larger flocks in a short time.

Substantial economies occur in large-scale assembling and processing. However, these are not so

important in reducing costs of operation as area

density. The expense of a catching crew averages

about $3 per 1,000 birds. The transportation cost

depends on the distance from the farm to the

processing plant. It ranges from one-half to 1

cent per pound of live poultry assembled.

With contract growing and integration, the

processing costs have been lowered because plants

have been better able to operate at capacity. Less

variation has occurred with seasonality of demand and prices.

The method of marketing chickens has improved about as much as production methods.

Large processing plants, contract haulers, and

contractors have practically replaced the older

operation, which included pickups by live-poultry

buyers, live-poultry cars, terminal market livepoultry receivers, live-poultry stores, small fattening and dressing plants, and city dressing plants.

It is anticipated that a substantial reduction will

continue in the number of processing plants and

that more combinations of assembling and processing will develop to improve distribution.

More long-term buying contracts by large buyers, such as chain stores, are anticipated. There

will also be, to the extent the laws allow, consolidated selling by processors in an area. This may

be done by having one selling agency represent

several processors. Fluctuating markets could

possibly be minimized by contracts based on cost

of production plus a reasonable profit. Costs

could be minimized if operations could be planned

to maximize efficiency with such a program.

Prior to 1927 practically all processed poultry

was sold with only the blood and feathers removed. A few plants producing canned poultry

and poultry soups had facilities for evisceration.

The U.S. Department of Agriculture developed a

voluntary inspection program in 1927 as a result

of a Canadian regulation, which prohibited the

importation of canned poultry products unless

accompanied by a certification from the Federal

Government attesting that the product had been

officially inspected and had been found to be

wholesome. New York City enacted a similar

regulation in 1928.

The trend toward the sale of ready-to-cook

poultry was well underway by 1945. By 1955 the

military began purchasing only ready-to-cook

poultry, and civilian supplies were almost entirely

in this form. Slaughtering and eviscerating

operations were generally done in the same plant.

Many plants were using the Department's voluntary inspection service. The Poultry Products

Inspection Act of 1957, which became fully effective on January 1,1959, required all poultry moving in interstate or foreign commerce to be inspected. Approximately 90 percent of the poultry sold off farms, including commercial broilers,

is federally inspected. The balance of the poultry processed and sold within States may be subject to State inspection.

Poultry is processed and sold within some

States on a noninspected basis. The pi^cessing

plant, and possibly the grading, may be' subject

to State inspection. It is not unusual for poidtry

that has not passed or may not pass Federal

inspection to be marketed through noninspected

channels. Some States now require all processed

poultry sold to be federally inspected.

The processors are primarily interested in getting a high percent of eviscerated yield. Condemnations, which are due primarily to air-sac

disease and chronic respiratory disease, are the

most important factor in reducing yield. Yields

are increased by better body conformation and

more white meat due to broad breasts. Good yellow skin and flesh and some fat are desired by

most processors. Breast blisters and barebacks

cause downgrading. Yields are higher in larger

birds.

When broilers are processed, there is a strain

and a sex difference in the dressing percentage.

Cornish broilers and broiler crosses, or strains

containing Cornish, give the greatest breast and

total edible meat yields. Breast width seems to

be the important factor. At the same age, live

male broilers are heavier than females, but females give greater eviscerated weights as a percentage of live weight and greater edible meat

yields as a percentage of eviscerated weights. The

approximate percent of live weight for 3^^- to

5-pound birds will be about 87 for New York

dressed weight and 73 for eviscerated weight.

The edible meat yield as a percent of eviscerated

Aveight will be about 55 for males and 58 for

females.

Standards and Grades

The U.S. standards of quality and grades for

poultry are used extensively for trading purposes.

Many retail distributors require that all ready-tocook poultry delivered be identified with an official grade mark. Ready-to-cook poultry must

have been inspected for wholesomeness to be eligible for grading. Processors applying for resident grading service agree to pay the cost of the

service. Graders may be either State or Federal

employees. The service is made available at reasonable cost in all parts of the country by means

of cooperative agreements with the States. Grade

A, B, or C may not be used in connection with

labels bearing the official inspection mark unless

the poultry has been graded by a licensed grader.
50 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

Classes

The official classes of young chickens are as

follows :

(1) Cornish game hen,—A Cornish, or Eock

Cornish, game hen is an immature chicken about

6 weeks old, of not more than 2 pounds ready-tocook weight. Broiler chickens usually containing some Cornish breeding in the cross are used.

(2) Broiler or fryer,—A broiler or fryer is a

chicken 8 to 11 weeks old, of either sex, with tender meat and flexible breastbone cartilage.

(3) Roaster.—A roaster is a chicken usually

3 to 5 months old, of either sex, with tender meat

and breastbone cartilage that is less flexible than

that of a broiler or fryer.

(4) Capon.—^A capon is a surgically unsexed

male chicken usually under 8 months old with

tender meat.

For details of grading live poultry and more

data on the classes and grades of poultry, see U.S.

Department of Agriculture Handbook 31, Poultry Grading Manual.

Condemnations

Inspectors in processing plants condemn for

disease and other conditions. Of the disease conditions, the respiratory ailments and the leukosis

complex are the most important. Condemnations

due to respiratory ailments come under the headings of septicemia and toxemia, airsacculitis, and

inflammatory processes. For information on the

important respiratory diseases—air-sac disease

(CED complex), Newcastle disease, infectious

bronchitis, laryngotracheitis, and leukosis—see

pages 53-54.

Other conditions resulting in condemnations

include bruises due to mishandling during the

catching, loading, and transportation of live

birds. Also, there are plant-caused condemnations, due primarily to faulty operations, which

include cadavers and bruised, contaminated, overscalded, or decomposed birds. Cadavers are

largely due to improper bleeding.

The reduction of condemnations is very important to the broiler industry. In 1964, the percent

condemned was 2.4, or 193,091,000 pounds (total

pounds condemned ^ (90 percent of pounds inspected — antemortem pounds condemned) ). At

the average price estimated for 1964 of 14.2 cents

per pound, the direct loss was $27,418,922 for the

year, not including the loss of efficiency during

processing. Condemnations usually cause discounts in grower payments.

The official inspection mark is the consumer's

assurance of wholesomeness. One of the primary

objectives of this handbook is the production of

better birds at lower costs. Eeducing condemnations helps materially to do this. For specific

suggestions, see page 26.

DISEASES

When a disease outbreak occurs, determine the

cause as soon as possible. If you do not recognize the disease or parasite, take or send four

or five live chickens to a poultry diagnostic

laboratory. Be sure to give the symptoms,

number of affected birds, number of deaths,

source of stock, size of flock, feeding program,

vaccines used, your name, address, and other

pertinent information.

It is exceptional to observe tuberculosis, cholera, coryza, blue comb disease, vibrionic hepatitis, botulism, or chiggers and ticks in broilers.

Until recently, it was exceptional to find blackhead in broilers.

In broiler production the emphasis is on the

prevention of diseases and then, if necessary,

on their treatment. Average total mortality to

9I/2 weeks is considered to be 4 percent. A

practical goal is to have only 1 to 2 percent

mortality up to 8 weeks. Preparation of the

broiler house is discussed on page 20. Other

procedures in disease prevention are given on

page 26. For detailed information on diseases,

refer to Diseases of Poultry.^

5 BIESTER, H. E., and SCHWARTE, L. H. DISEASES OF

POULTRY. 1382 pp. The Iowa State Univ. Press, Ames.

1965.

PuUorum and Fowl Typhoid

Most breeder flocks are tested annually for

puUorum and typhoid, and eggs are not set from

them until all the birds test negative. Bird

carriers of fowl typhoid will react to the pullorum antigen. The blood test will not detect

birds carrying the infection in the blood stream,

only those carrying antibodies. Repeated blood

testing is necessary.

In most operations if there should be a breakthrough with either disease, it is possible to trace

the ailment to the flock or flocks involved so they

can be eliminated immediately as a source of

hatching eggs and baby chicks. Furazolidone is

the drug most often used in outbreaks.

Omphalitis

This disease is usually caused by contamination of the navel at the time of hatch. To prevent it, only clean eggs should be set and the

hatchery, incubators, and hatchers should be

kept clean. Fumigation of eggs and incubators

with formaldehyde gas is one of the best ways

to control this disease. For detailed recommendations on fumigation, see U.S. Depart-
COMMERCIAL BROILER PRODUCTION 51

ment of Agriculture Miscellaneous Publication

739, The National Poultry and Turkey Improvement Plans and Auxiliary Provisions.

Epidemic Tremor

(Avian Eneephalomyelitis)

This disease appears during the second or

third week of life. Chicks have an unsteady

walk and then a tremor of the neck and head.

There is no treatment for affected chicks. The

breeding flock should be immunized by vaccinating at 6 to 8 weeks of age before they pick up

the natural infection. Many cases of epidemic

tremor are complicated with crazy chick disease.

The treatment for the latter should be tried.

Survivors of epidemic tremor outbreaks are

actively immune.

Crazy Chick Disease

(Encephalomalacia)

This disease is usually observed between the

third and the eighth week and is characterized

by involvement of the nervous system. The onset

is sudden. The birds may have convulsions, a

retraction of the head, rhythmic spasms of the

legs, paralysis, or forced backward movement.

On autopsy, pinpoint hemorrhages are found in

the cerebellum. Losses can be stopped or reduced

by supplying adequate vitamin E m the form of

wheat germ oil or tocopherols. A favorable

response can also frequently be obtained by

suddenly changing the feed, using molasses, or

adding alfalfa meal or wheat bran to the feed.

Rickets

Leg weakness and loss of vigor are the early

symptoms of rickets. Later the breast becomes

crooked and joints become enlarged. The condition is due to an insufficient amount of vitamin

D, calcium, or phosphorus or an imbalance of

calcium and phosphorus. The ration may be

adequate for normal conditions, but not for

added stress. Correction of the ration is usually

all that is needed.

Curled-Toe Paralysis

(Riboflavin Deficiency)

Chicks with this condition usually assume a

squatting position. The toes curl inward.

Eecovery is rapid if the ration is supplemented

with riboflavin.

Slipped Tendons

(Perosis)

The joints enlarge and then the bones become

distorted in perosis. The main tendon over the

back of the hock slips to one side. This disorder

may be due to an improper balance of calcium

and phosphorus or a deficiency of manganese,

niacin, choline, or biotin. The dietary deficiency

should be corrected. There is no cure jPor the

affected birds.

Nutritional Roup

(Vitamin A Deficiency)

Young chicks suffering from vitamin A deficiency usually show a watery discharge from

their eyes. Eventually cheesy material collects

beneath the lids. Growth is poor, feathers are

roughened, and the gait is staggery. The-treatment is to provide an adequate vitamin A intake.

Coccidiosis

Coccidiosis is universally present in the

chicken. It may affect chickens of any age and

is caused by microscopic parasites that infect and

damage the cecal pouches, the small intestine,

and the rectum. Sick birds are droopy, chill

easily, have ruffled feathers, have little or no

appetite, and may pass watery or bloody

droppings.

A preventive level of drug is the usual method

of trying to prevent the disease. In spite of

all that has been done, coccidiosis is still a

serious problem, due primarily to allowing contamination to build up so the drug cannot handle

it at the usual level given.

The sporulation of the cyst stage takes place

best at 65° to 85° F. and in the presence of

moisture. Transmission is direct as no intermediate host is needed.

Chickens 4 to 6 weeks old are most susceptible

to infection, and loss of growth is greatest at

this age. A single chicken often has more than

one parasite species present.

Cecal Coccidiosis

Bloody droppings is the first symptom of a

very acute outbreak of "cecal" coccidiosis. In

less acute cases, the birds are dull and droopy,

act sleepy, and huddle with ruffled feathers and

drooped wings. On postmortem examination,

the cecum is greatly distended, filled with blood,

and may contain yellowish cheesy cores. The

disease is caused by a specific protozoan parasite,

Eimeria tenella^ which lives and causes damage

primarily in the cecal pouches.

Intestinal Coccidiosis

Intestinal coccidiosis causes broilers to become

weak and thin. The combs are pale. The postmortem lesions are found mostly in the intestines.
52 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

Hemorrhages in the intestine are seen in acute

cases. When Eimeria necatrix is the cause of

the trouble, both the ceca and the intestines may

be affected. The primary damage is in the small

intestine. In severe cases the intestine swells

and there is bloody diarrhea.

Another cause of intestinal coccidiosis with

symptoms similar to those caused by E, necatrix^^

but often less severe, is E, maxima, E, hrunetti

causes damage in both the upper and lower

intestines and in the rectum and ceca. Other

intestinal species usually of less importance are

E, acervuUna^ E, praecox, E, mitis^ and E,

hagani. Immunity to one species does not produce immunity to another species. Chicken coccidian parasites do not infect turkeys and vice

versa.

The prevention of coccidiosis is usually by

means of an anticoccidial drug given in the feed

when the chick is a day old until as near marketing as possible. Activity of a drug against

E, tenella and E. necatrix is essential. It is^ desirable also to prevent E, acervulma, E. maximxi,

and E. irunetti.

To prevent coccidiosis, it is suggested that the

following drugs be used in the feed as recommended by the manufacturers: Amprolium,

Zoalene, Polystat, or Unistat. To control outbreaks of coccidiosis, it is suggested that one

of the sulfonamides—sulfaquinoxaline, sulfamethazine (Sulmet), or sulfathiazole—Zoalene,

or Amprolium be used at the levels recommended

by the manufacturers.

Nonspecific Enteritis

This condition is common in young birds and

is often confused with intestinal coccidiosis.

It is possibly related to the hemorrhagic anemia

syndrome and gizzard erosion. To differentiate

it from coccidiosis, oöcysts will not be present,

it does not respond as well to sulfonamides as

does coccidiosis, and nonspecific enteritis usually

persists much longer—many days or weeks.

Signs include listlessness, loss of appetite, and

diarrhea. Lesions consist of the inflammatory

condition of the intestinal tract. This disease

can be the result of wet litter, overheating, chilling, faulty feeding, and dirty waterers.

"Eed spot" disease (red spots often seen in the

intestine) may be nonspecific or it may be due

to one or more species of coccidia {Eimeria

mitis^ E, mxixima^ or E, necatrix),^ If coccidia

are not found, the directions for using the feedgrade antibiotic, or a nitrofuran compound if

tried, should be followed. Nonspecific enteritis

does not respond well to any treatment. Good

management seems to be a good preventive and

control measure.

Avian Nephrosis

(Cumboro Disease)

Usually avian nephrosis attacks chicks between

21 and 28 days of age. They are depressed and

sometimes tremble. They show little interest

in feed and water. They stagger, fall down, and

die. The active period of mortality is 7 to 8

days, but it varies. It peaks halfway through

this period. On postmortem, the kidneys are

pale or gray, the bursa is enlarged, and usually

hemorrhages are in the muscles of the legs,

thighs, and breast. There is no way to prevent

or cure this disease. Once it is on a farm, it

usually persists. Eemoving the litter, treating

the floor with lye, and spraying the house with

a synthetic phenolic disinfectant may help.

Hemorrhagic Anemia Syndrome

Affected flocks do not eat, become weak, squat

on their hocks, and show the typically pale or

dark combs. On postmortem, irregular, scattered

hemorrhages are found in the muscles of the

breast, the outer part of the thigh, and the

internal organs. The blood is usually pale and

slow to clot. The bone marrow may be yellow

or gray instead of normal red. The kidneys are

pale and swollen. Broilers 3 weeks old to market

age may be affected.

There is no known causative agent. Several

of the aspergilli may be implicated. Vitamin

E and K deficiencies and moldy-feed toxicosis

will produce similar signs. Other possible predisposing factors are excessive medication and

the stress of diseases, particularly avian nephrosis (Gumboro disease). Sulfonamides (sulfaquinoxaline, sulfamethazine, or sulfathiazole)

seem to aggravate the condition. This syndrome

may be associated with nonspecific enteritis and

gizzard erosion. It may help to increase the

vitamin K intake and give codfish liver solubles,

condensed fish solubles, and trace minerals. An

effort is being made to find and eliminate the

cause.

Gizzard Erosion

Gizzard erosion is characterized by small

hemorrhages under the homy layer of the gizzard, causing it to darken and erode. It is often

associated with nonspecific enteritis and the

hemorrhagic anemia syndrome. The condition is

found in less vigorous birds and it does not

respond to treatment.

Moldy-Feed Toxicosis

Many strains of fungi have been isolated from

broiler mash and from substances toxic to

poultry. Chickens become depressed, develop
COMMERCIAL BROILER PRODUCTION

diarrhea, have pale comb and wattles, and on

postmortem show a hemorrhagic condition, gizzard erosion, and a necrotic condition of the

liver.

When litter becomes damp, especially around

the waterers, the molding process starts and

grows within 10 days. It spreads to other damp

areas in the litter. Any feed scattered in the

litter serves as a means for the fungi to increase

and toxins to be produced. Chickens that ingest

infected feed or litter invariably develop a toxicosis. How serious it is depends on the type of

fungi, the potency and amount of toxin, and the

period of ingestion. Toxicosis usually reaches

its peak when chickens are 4 to 6 weeks of age.

It is not known why molds gain or lose toxicity.

Aspergillosis

Infection is usually caused by rearing chicks

on moldy litter or on litter that has been moldy

prior to use. Feed occasionally is at fault. The

birds usually have some difficulty breathing.

There are nodules and abscesses in the lungs and

yellow exúdate is in the air sacs. There is no

treatment for affected birds. The litter should

be changed. This will prevent additional birds

from becoming infected.

Leukosis and Marek^s Disease

Avian leukosis and Marek's disease are characterized primarily by an independent rapid

succession of divisions of essential blood-forming

cells. Marek's disease has commonly been

referred to as neural and ocular lymphomatosis.

The neural form includes fowl and range paralysis and the ocular form, blindness and gray,

glassy eyes. The disease does not react to the

tests currently used for leukosis detection. Leukosis includes visceral lymphomatosis, osteopetrosis, erythroblastosis, myeloblastosis, myelocytomatosis, and nephroblastoma. Visceral

lymphomatosis is characterized by an enlarged

liver. It may parallel the neural and ocular

forms. In the visceral form, any organ may be

affected. The skin may have small tumors in

the feather follicles or large skin tumors.

Osteopetrosis, the thick-leg disease, occurs more

in male than in female broilers. The condition

often escapes detection until the birds are dressed

and may be sporadic in nature. The other forms

of leukosis do not usually occur in broilers.

The indicated preventive and control measures

are breeding for resistance, hatchery sanitation,

thorough cleansing and disinfection of brooder

houses and equipment, a reasonable break between broods, and isolation of young from adult

stock. Parasites should be kept under control.

For further information, see U.S. Department

of Agriculture Production Research Report 94,

53

An Outline of the Diseases of the Avian Leukosis

Complex.

Infectious Bronchitis

The disease comes on suddenly and spreads

rapidly with a high proportion of the chicks

becoming ill. The mortality is usually less than

10 percent, but may reach 70 percent in chicks

under 4 to 5 weeks and less in older chickens.

In broilers the major damage of infectious

bronchitis is the stress effect in bringing on airsac disease. The symptoms include nasal discharge, watery eyes, depression, coughing, and

gasping. Bronchitis is often followed within 7

to 10 days by an attack of chronic respiratory

disease (CRD), which is usually far more serious.

A laboratorjr diagnosis is necessary, as bronchitis

cannot be differentiated from other respiratory

diseases on the basis of lesions alone. A preventive and control program will depend on

local conditions. It may include vaccination.

Newcastle Disease

(Pneumoencephalitis)

The respiratory symptoms of Newcastle disease

are similar to those described for bronchitis, but

are usually more severe. Mortality can be negligible or near 100 percent in 10 to 14 days, but

mostly in 2 or 3 days. Following recovery,

nervous manifestations may or may not occur,

such as walking in circles, paralysis, twisted

neck, and somersaulting. They do not occur

with bronchitis. CRD may follow Newcastle

disease in 5 to 7 days. As in bronchitis, lesions

are not diagnostic. There is danger of spreading the disease by crates, trucks, litter, and

tracking. Security management is recommended.

In congested broiler areas preventive vaccination is practiced extensively.

Laryngotracheitis

In acute laryngotracheitis, the respiratory

symptoms are severe—gasping and coughing.

The intake of air is accompanied by loud wheezing. In less severe attacks, the symptoms may be

those of a cold. The incidence of the disease

is much less than that of either infectious bronchitis or Newcastle disease, and its spread is

slower. It rarely is observed in broilers less

than 4 weeks old. It is highly contagious. It is

airborne over short distances and is transmitted

by persons, trucks, dogs, crows, or other agents.

It is a carrier disease. Some of the recovered

birds continue to carry the virus and to be infectious to susceptible birds. An accurate diagnosis can only be done on the basis of laboratory

procedures.

Birds should not be vaccinated unless the dis-
54 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

ease is known to be in the area. If it is

diagnosed in the flock, all groups not affected

should be vaccinated. Mortality varies from

below 10 to as high as 50 percent.

Colibacillosis

(E. coli Infections)

EscJienchia coli infections in broilers may take

the form of an enteritis or an air-sac infection.

Trouble may start with infected hatching eggs.

Apparently clean eggs packed in used dirty cases

may be contaminated by this contact. Coliform

bacteria are often associated with a pleuropneumonialike organism (PPLO) in air-sac disease.

Pathogenic E, coli infections may be triggered at

5 to 8 weeks by stress, live-virus vaccinations,

respiratory viruses, coccidiosis, roundworms, and

poor environmental sanitation and management

practices; for example, overcrowding, poor ventilation, excessive humidity, too much dust, and

temperature extremes. The birds may have ruffled feathers, may be droopy, and have diarrhea.

If the air sacs are infected, severe depression,

coughing, and other symptoms similar to CKD

are evident. A laboratory examination is needed

to diagnose this disease.

To prevent and control coliform enteritis, furazolidone and the antibiotics—Aureomycin, Terramycin, streptomycin, erythromycin (Gallimycin),

neomycin, and tylosin (Tylan)—are used. E. coli

infections may readily develop resistance to certain antibiotics.

Chronic Respiratory Disease

Chronic respiratory disease (CED), avian mycoplasmosis, or air-sac disease is the leading cause

of condemnations at the dressing plant. It also

causes a great loss in weight and mortalitj^. In

the field it is a disease from which many infectious agents may be isolated. The primary cause

of the infection is a pleuropneumonialike organism (PPLO). CED in an uncomplicated respiratory infection is caused by a PPLO identified as

a Mycoplasma, When a secondary infection is

added, the disease becomes complicated and lesions may be moderate to severe m form. ^ If the

secondary infection is bacterium E. coli^ more

than one bacterium, or fungi, the symptoms are

usually severe.

The combination of PPLO nnd the viruses of

infectious bronchitis and Newcastle disease,

either naturally or by vaccination, causes respiratory symptoms and air-sac lesions. This multiple infection found in the field is the CED complex often called air-sac disease. The symptoms

and lesions are most severe when produced by

combining PPLO, E, coli^ and the viruses of infectious bronchitis and Newcastle disease. Either

infectious bronchitis or Newcastle disease, when

combined with PPLO and E, coli^ causes a severe

form of CED. Good management helps reduce

the effects of E, coli especialTjr.

Adverse environmental conditions will intensify

the severity of the disease. The chicks may be

weak, may be handled roughly, or be overheated

or chilled at the hatchery or on the way to the

brooder house. In the brooder house, they may be

overheated, chilled, overcrowded, have insufficient

feed or water space, inadequate ventilation, too

high humidity, and damp or wet litter. The most

important stress is probably outbreaks of diseases, such as coccidiosis, Newcastle disease, infectious bronchitis, laryngotracheitis, or the reaction

to vaccination for Newcastle disease and infectious bronchitis.

CED is an egg-transmitted disease. The rate

of transmission from breeder flock to baby chicks

is thought to be about 10 percent, but varies

greatly. PPLO stock negative to Se-type Mycoplasma antigen is being produced. This stock is

negative only to Se-type antigen, not necessarily

to others, such as pathogenic Iowa strains 0 and

695.

The incidence of CED complex has been materially reduced where PPLO-free chicks have been

used to produce broilers. By using antibiotics it

is possible to medicate the chicks and destroy the

Alycoplasma originating from embryonic sources.

The breeder replacement chicks are injected and

fed a potentiated high-level antibiotic feed. They

are then raised under a management-sanitationsecurity program to keep them free of CED.

They must be protected from reinfection. Strict

attention to isolation and sanitation is essential.

The breeders so produced may be used to produce PPLO-free chicks. These chicks should not

be mixed with other chicks or exposed to PPLO

infection. In experiments being conducted to

develop mycoplasma-free progeny, primary

breeder and replacement flocks are exposed to a

pathogenic strain of Mycoplasma at 5 to 9 weeks

of age.

The control of CED complex, other than eliminating PPLO from the breeder flock, in the field

also consists of attempting to suppress the E, coli

and other bacterial contaminants with chemotherapeutic agents. Furazolidone has been extensively used. The antibiotics commonly used

are Aureomycin, Terramycin, streptomycin, erythromycin (Gallimycin), neomycin, and tylosin

(Tylan). The first objective is to suppress or

eliminate PPLO. This has been done with potentiated Aureomycin and other antibiotic agents.

Locally it is sometimes practical to eliminate

Newcastle disease and infectious bronchitis vaccinations, but often impractical and unattainable.

Careful vaccination and antibiotic therapy help

to keep broilers growing while the birds still

carry PPLO. The security management program

(p. 26) should be followed.
COMMERCIAL BROILER PRODUCTION 55

Synovitis

(Infectious Synovitis)

Synovitis also causes heavy losses. Considerable economic loss is due to birds getting thin and

downgrading at market time. Infectious synovitis is caused by Mycoplasma synoviae^ M, galliseptieum^ and an unnamed arthritic-producing

agent.

The birds first become droopy and listless.

Their legs are weak. Lameness is observed.

When handled, the hocks show enlargement. The

swollen joints and footpads are painful and discourage the birds from eating; consequently, they

soon lose weight. They huddle, as if cold. Mortality does not usually exceed 5 percent. Birds

are generally 5 to 7 weeks old when first affected.

In later stages of the disease the comb dries up,

the feathers become ruffled, and the droppings

are green with an excess of white material, or

urates. On postmortem examination, a yellowish

fluid is found in the bursae and joints. As the

disease becomes more severe, a cheeselike substance is present in the bursae and tendon

sheaths. The joints of the wings and shoulders

and also the sternal bursa may be affected.

The most effective treatment is to cull affected

birds and treat the rest with 200 grams of Aureomycin or 100 grams each of Aureomycin and

nf-180 (furazolidone) per ton in the feed continuously until 3 days before marketing. When

the disease is expected, 50 grams of antibiotic per

ton of feed can be given to the birds continuously

from 1 day old. This is not adequate if other infections, such as CED, are a stress. There is no

cheap way of preventing synovitis or of handling

an outbreak of this disease.

Fowl Pox

Fowl pox is caused by a virus and is sometimes

found in broilers in certain areas of the South,

especially during the mosquito season in the late

summer and fall. The typical lesions occur on

the unfeathered parts of the body. The head is

principally affected. The infection may involve

the mouth, nasal chambers, and eyes. Dry pox is

usually easily identified by the typical wartlike

growth on the comb, wattles, or face. In broilers, eye infection is most common. When pox

infects the mouth and nasal passages, respiratory

symptoms may be exhibited and birds may suffocate. This form is called wet pox.

Routine vaccination of broilers may be advisable where fowl pox occurs regularly. Fowl pox

vaccine is preferred, using the wing-web method

and only one needle, when the birds have been in

the broiler house for 7 to 10 days.

Vaccination

The program for vaccination should depend on

local conditions. In most concentrated broiler

areas, it is cheap insurance against heavy losses.

Vaccines should be used according to the instructions of the manufacturer regarding time

and method. They should be kept cool before

being opened and used immediately after they are

opened. Sometimes broilers are vaccinated and

yet an outbreak of disease occurs. In most cases,

the cause is not following the directions enclosed

with the vaccine.

Vaccination, especially for Newcastle disease,

has often been done when the chick is a day old.

Superior results can be obtained if Newcastle disease vaccine is given when chicks are 7 to 10 days

old. Except in isolated areas, a booster, or second vaccination, is given in the water at 4i/^ to 5

weeks. Infectious bronchitis vaccination, if used,

should be given 7 to 10 days after the Newcastle

vaccination.

Live-virus vaccines are used against fowl pox,

infectious bronchitis, laryngotracheitis, and Newcastle disease. For Newcastle disease, killed-virus

vaccines are also available. A killed-virus vaccine

cannot cause the disease and is therefore safer to

use and is most useful for broilers, because there

is less stress for CED and it does not spread livevirus infection. However, it may have the disadvantages of increased labor cost due to having

to be injected, the danger of vaccination crews

spreading disease, the higher cost of the vaccine,

and the short duration of immunity.

The methods of vaccination include the wingweb^ which is used for administering one type of

Newcastle vaccine; the intraocular^ in which the

vaccine is applied with a dropper in the eye or

nostril of the bird, and is used by some poultrymen for Newcastle vaccination at 5 to 10 days of

age; and mass immunization methods. Vaccine

is applied with a garden duster in the dust

method for Newcastle vaccination. A hand or

machine sprayer is used to apply the vaccine as

a fine mist in the spray method. The easiest way

with the least reaction is the water method.^ also

used for administering Newcastle vaccine, especially boosters. It is used sometimes for bronchitis vaccination. Fowl pox vaccine is usually

applied when the chick is 7 to 10 days old, using

one prong in the web of the wing.

No vaccination program is entirely successful

without strict management practices to limit possible spread of infection. Growers should not

visit other flocks. The first 4 weeks of a chick's

life should be in isolation. Servicemen should

visit flocks less than 4 weeks old the first thing in

the morning, and they should not enter the house

unless absolutely necessary. They should start

out each day with clean outer clothing. The use

of disinfected boots or clean plastic shoe covers in
56 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE

broiler houses is essential. A change in clothing

should be made after visiting any farm where

there is an outbreak of respiratory ailment.

When outbreaks of respiratory disease occur, the

disease usually has been introduced by a human

carrier.

Other Conditions Causing

Disease and Mortality

Barebacks and Cannibalism

Feather pulling and picking can cause considerable loss from downgrading to mortality. Anything that makes the chicken uncomfortable will

lead to feather pulling. If feather pulling is not

controlled, picking may cause barebacks and lead

to cannibalism and deaths. Breeding may be a

factor. Slowness of feathering combined with

poor management encourages the vice. Some

strains are less cannibalistic than others.

Check faulty management practices. These include too high a temperature or humidity, lack of

fresh air, drafts, overcrowding, infestations of

worms, lice, or mites, lack of feed or water, insufficient feed or watering space, and excessive light

including sun spots. More feather picking occurs

with pellet and crumble feeding than with mash

feeding because the birds have more time to develop vices. To avoid feather picking, debeak the

birds properly and do everything possible to make

them comfortable. Debeaking and providing adequate ñoor, feed, and watering space are discussed

under Brooding (pp. 21-23). When feasible, remove injured birds and treat with an antipick

preparation. Other control measures include

cooling the house (p. 19), scattering whole oats

in the litter, or adding 2 pounds per ton of fine

salt to the mash for 2 days.

Mites, Lice, and Ticks

Mites, lice, and ticks are common external parasites of chickens. They cause stress, lack of vigor,

and mortality. For information on the control of

these pests, see the following U.S. Department of

Agriculture publications: Leaflet 382, The Fowl

Tick—How To Control It; Leaflet 383, Poultry

Mites—How To Control Them ; and Leaflet 474,

Chicken Lice—How To Control Them.

Rats and Mice

Rats and mice kill young chickens, destroy

eggs, eat or contaminate poultry feed, and damage buildings by gnawing wooden walls, foimdations, and equipment. They also spread many

diseases and parasites.

Losses from rats and mice in a commercial

broiler flock may total several hundred dollars a

year, including chickens, feed, and other destruction. The damage often goes unnoticed, because

losses are gradual and because rats and mice seldom appear when anyone is in the poultry house.

To make new buildings rodentproof, use concrete foundations and floors. Metal shields around

doors and hardware cloth over openings are effective in keeping rodents out of buildings.

Shelter is second only to food in the rodents'

requirement for survival. Control rats and mice

with poison before you attempt to destroy their

breeding and hiding places. Once the rodent

population is under control, dispose of trash

dumps, piles of old lumber or manure, and garbage. Find and block runs or burrows.

Mix poison in baits with cereal, ground meat,

or fish, or sprinkle poison baits on fruits and

vegetables. Place bait along well-traveled runs

and near centers of activity. When using any

poison, protect poultry and domestic animals

from accidental poisoning by carefully placing

baits m protected stations. After the existing infestation has been eliminated, maintain poison

stations at all buildings and trouble spots. Check

stations regularly, and keep a supply of fresh bait

exposed to eliminate new invaders.

Anticoagulant poisons are slow acting and require 5 to 14 days to exterminate rats and 10 to

30 days for mice. For information on fast acting

poisons or other control methods, consult your

county agricultural agent.

Caution: All poisons are dangerous and can

kill small animals and pets if used carelessly.

Anticpagulant rat poisons—warfarin, pival, fumarin, and Diphacinone-^are safe when used according to the manufacturer's instructions. They

may be purchased as powdered concentrates for

dry baits or in water-soluble form.

'i^ U.S. GOVERNMENT PRINTING OFFICE: 1967 O 223-122
J7

MANAGEMENT GUIDE

Family Unit Size,—45,000 broilers.

Labor,—With automatic feeders, not over 18 minutes per 1,000 per day ; without

automatic equipment, not to exceed 31 minutes.

House-Unit Size,—7,200 to 20,000 per house; desirable size is 15,000 in 40- by

300-foot house.

Pen Size.—1^200 to 2,500 per pen.

Floor Spa^e.—0.8 square foot per 3- to 3.75-pound broiler; 1 square foot for

summer-reared and per 4-pound bird and over.

Brooder Space,—750 to 1,000 chicks per 1,000-chick size hover; varies with season,

insulation, and mechanical ventilation.

Litter,—2 to 4 inches—less in hot weather.

Fountains.—1-gallon fountain per 100 chicks to 2 weeks old.

Water Space.—Three 8-foot automatic waterers per 1,000; add one more per

1,000 birds when temperature is 90° F. or higher.

Feeder Lids,—One feeder lid per 100 chicks.

Feeder Space,—^Allow fifteen 15-inch diameter 30-pound capacity hanging feeders

per 1,000; allow 1 linear foot per 12 broilers for mechanical feeders.

Feedings,—Follow directions of feed manufacturer or formulator.

Lights,—After 2 weeks, use all-night lights; one 25-watt bulb per 100-square foot

floor space.

Security Management,—Follow good management practices as far as is economically feasible. (See inside front cover and Security Management, p. 26.)