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 Agri- culture 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 Page Good management practices in raising Grower supervision 25 meat birds Inside front cover General sanitation 26 Current trends in broiler raising 1 Security management 26 Production centers 1 Disinfection 26 Growth of the broiler industry 1 Parasite control 27 Integration 2 Chicken-meat production 27 Financing 3 Cornish game hen 27 Contracts 4 Broilers and small roasters 27 Cost of production 6 Large roasters and capons 28 General guide 6 Breast blisters (sternal bursitis) 28 Baby chick cost 6 Marketing 28 Grower payment costs 7 Feeds and feeding methods 28 Labor cost 7 Importance of a good broiler ration 29 Grower fixed or housing costs 7 ^ Factors to consider in a broiler ration 29 Litter cost 8 Feeding programs 32 Selection of stock 8 Nutrient requirements 32 Straight-run versus sexed chicks 8 Protein 33 Breeding methods 8 Energy 33 Growth and feed efficiency 9 Vitamins 33 Feathering 9 Vitamin A 34 Breast development 10 Vitamin D 34 Shank pigmentation 11 Vitamin E 34 Diseases (general) 11 Vitamin K 34 Leukosis 11 Riboflavin 35 Nutrients L 11 Pantothenic acid 35 Plumage color 11 Niacin 35 Egg size 12 Choline 35 Housing 12 Biotin 35 Location 12 Folacin 35 Requirements 12 Vitamin B« 35 Types of houses 13 Vitamin B^ ^. 35 Controlled envii;^nment 15 Thiamine ^-. 35 Housing costs 16 Brooding 17 Unidentified growtà factors 35 Brooding systems 17 Minerals **«•. 36 Environmental factors 18 Calcium -.u^/C: « 36 Hot-weather problems 19 Phosphorus »^«JM^*- - —«^^^ 36 Litter 20 Sodium --*«.- -«-«^ 36 Preparation of house and brooder 20 Manganese --.p. - -*ÍÜ Lights 21 Iodine •* «-«. Sé- Floor space 21 Zinc .^ W Size of units 22 Iron and copper '-..^tm^f^^m,^ lit Waterers and watering space 22 Molybdenum and selenium ''i^:^,,.^^. Chick guards and other management practices 22 Magnesium ~*^%-' ' Debeaking 23 Feed and water consumption 37 ' Feeders and feeder space 23 Ration ingredients 37 Management practices 25 Grains 37 Size of operation 25 Millfeeds 37 Labor efficiency . 25 Fat 38 Stress factors 25 Fish oil 38

ii Page Page Animal protein products 38 Standards and grades 49 Fishmeal 38 Classes 50 Condensed fish solubles 38 Condemnations 50 Meat scrap 38 Diseases 50 Crabmeal 38 PuUorum and fowl typhoid 50 Feathermeal 38 Omphalitis , 50 Poultry byproduct meal . 38 Epidemic tremor (avian encephalomyelitis) 51 Vegetable protein sources 39 Crazy chick disease (encephalomalacia) 51 Soybean meal ^ 39 Rickets 51 Cottonseed meal 39 Curled-toe paralysis (riboflavin deficiency) 51 Corn gluten meal 39 Slipped tendons (perosis) 51 Sources of natural vitamins and unidentified Nutritional roup (vitamin A deficiency) _. 51 growth factors 39 Coccidiosis ', 51 Distillers' dried solubles 39 Cecal coccidiosis 51 Fermentation products 39 Intestinal coccidiosis 51 Alfalfa meal 39 Nonspecific enteritis 52 Dried whey 39 Avian nephrosis (Gumboro disease) 52 Antioxidants 39 Hemorrhagic anemia syndrome 52 Coccidiostats 39 Gizzard erosion 52 Antibiotics 40 Moldy-feed toxicosis 52 Antibiotic potentiation 40 Aspergillosis 53 Arsenicals __; 41 Leukosis and Marek's disease , 53 Hormones 41 Infectious bronchitis 53 Xanthophyll 41 Newcastle disease (pneumoencephalitis) 53 Miscellaneous additives 41 Laryngotracheitis 53 Ration formulation 41 Colibacillosis (E. coli infections) 54 Factors affecting feathering 44 Chronic respiratory disease 54 Linear programing : 44 Synovitis (infectious synovitis) 55 Concentrates and premixes 45 Fowl pox 55 Broiler feeds 46 Vaccination 55 Feed preparation and distribution 47 Other conditions causing disease and mortality __ 56 Judging feed value 47 Barebacks and cannibalism 56 Marketing 47 Mites, lice, and ticks 56 Marketing cycle 47 Rats and mice 56 Marketing areas and practices 48 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 direc- tions 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 manufac- turer'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 direc- tions 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 spe- ing the winter holidays when more turkey is on cialized farm enterprise. In 1952, the annual the market. The per capita consumption of production of commercial broilers exceeded that broiler meat has increased rapidly since 1947-48, of farm chickens, including hens that were by- as shown in figure 1. products of egg production. The total output The large-scale production of broilers has de- has increased from 34 million broilers in 1934 to veloped in concentrated areas. The first such over 2,300 million in 1965. Except for small de- area was probably the Delmarva Peninsula, which creases in 1944 and 1946, the annual output of includes all of Delaware and parts of Maryland broilers has increased each year since 1934. The and Virginia on the Eastern Shore of Chesapeake average price per pound paid to the producer and Bay. Virginia also has several sizable producing the value of broiler production have fluctuated. Prices have tended to decline, and the total value areas. Georgia has recently been the largest pro- of production has inclined to over $1 billion in ducing State. Other concentrated areas of out- 1964. put are in Arkansas, Alabama, North Carolina, Commercial broilers are produced at a rela- Mississippi, Texas, Maine, and California. The tively uniform rate the year around. More are southeastern and south-central regions have had raised to meet the greater demand in the summer the greatest increases in recent years, as shown because of more outdoor cooking and fewer dur- in figure 2. CURRENT TRENDS IN BROILER RAISING Production Centers enterprise has been financed and organized. Live birds have been more accessible to processing The center of broiler production has moved in plants. The availability of high-quality birds in recent years from the eastern seaboard—the Del- a convenient form and at reasonable prices for the marva Peninsula, Maine, and Connecticut—to consumer has enhanced the demand. Population the Southeastern States of Georgia and North and take-home pay have increased. The volume Carolina and the South Central States of Arkan- of output has become more constant throughout sas, Alabama, Mississippi, and Texas. In 1964, the year. the 10 leading States in broiler production pro- Competition has been intense in the broiler in- duced 1,800 million birds, or 84 percent of all the dustry, forcing many firms and their producers broilers in the Nation. Area competition is pri- out of business. Firms with more profitable mar- marily dependent on production and transporta- gins have usually taken up the slack caused by the tion costs of processed broiler«. closing of less efficient firms. Lack of availability of credit has at times slowed the expansion rate. "^Growth of the Broiler Industry On the other hand, the trend has been for more ^ broilers to be raised per farm. Broiler raisers For several years and especially from 1955 to have increased the size of their houses and have 1962, the cost of producing and marketing broil- installed labor-saving equipment to care for more ers has had a downward trend. Although prices birds. Labor cost per bird has been lowered. have also been less nearly every year, producers Commercial broiler production may be a full- have offered increasing supplies. The cost reduc- time enterprise, part-time with some industrial tion has been due to many factors. Advances pursuit, or combined with farming operations, have been made in nutrition, breeding, manage- such as the production of corn, cotton, soybeans, ment, and in the prevention and control of dis- hay, or beef cattle. Many broiler growers do not eases. The improvement in feed efficiency has depend entirely on the income from their been the most important factor in reducing the chickens. total cost per pound of the broiler. Radical The ability of the grower can be an important changes have been made in the way the broiler 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 replace- ment of farm chickens by broilers.

His decisions as to heat, ventilation, feeding, dis- small broilers and "South Shore" roasters. Most ease control, and similar matters, even under the of the early commercial broiler production was by supervision of service personnel, can materially independent growers. They paid cash for every- affect results. thing and took all the profit. As margins became The competition for labor can be a very im- smaller, flocks became larger, and soon the feed portant factor in the growth of broiler produc- dealer became the source of credit. As the in- tion in an area. If broiler growers have no alter- dustry grew, the feed dealers began to depend native, they will probably continue to operate on the feed manufacturers as a source of funds. when prices are depressed and income is low. To spread their risk, both feed dealers and feed However, when industries offer an alternative manufacturers integrated vertically with hatch- revenue, the wage offered, the relative "pleasant- eries aiid processors. This was the start of many ness" of the jobs, the time of year, the duration forms of integratibnT of the job, and the skill and responsibility re- Integration may include one df"'inere..i>hases, quired all become factors. In the South, histori- such as financing, feed, hatching, breeder ^pck, cally, there have been fewer agricultural alterna- production, processing, and retail marketing. îî^. tives and less industrial demand for labor. most cases, the primary production of breeJApJ" stock and retailing have not been included. IV^^ Integration companies may be involved in a single operatM», such as processing, or a single corporation JMiy Poultry-meat production has passed through encompass all the phases. Some corporationi mn several stages of development. Originally meat publicly financed, and their operations oft^^- production was a byproduct of egg production, clude most of the phases enumerated abo\|k and much of the poultry meat was from milk- Several forms of integration apply to t^rilir fattened roasters from the Middle West and the production. Horizontal integration is the tm* South Shore of Massachusetts. There was some bining of firms in the same stage of prodiwgtóaB. specialization of production close to the eastern It may result in better control of productiç^ liWÎ markets, where premium prices were paid for 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 4.7% 4.4% 1945 24,944 'I I I I I I I 51,060 ::::::=:=:: 149,745 :=:::::::::::::::::::: 14% ;^:i:;;iii;i:i:i:;:i41%:;:' 365,572

1955 475,483::::::::::=::::::::::: ,««,,„. :Í43.5%:i:iiiii:Í:ÍiÍi=:::::Í: ''091,684

1965 1.i.1.1 i lililí m ; 653,695 773,079^ ;::: 603,879 ;::::: 2,332,589 128% ^33.1%^^^:;:;:;:;:;: 25.9%!:;:;:;;^

DEL., MD.,& VA. ^ N.C., S.C.,& GA. ^ ALA., MISS., 4 ARK. EID ALL OTHER BN-27935 FIGURE 2.—Commercial broilers produced in selected areas, 1934-65. companies have merged. Vertical integration is grated business can be more effective if it is more the control by a single management of two or efficient. more stages of production. It is said to be back- ward when it undertakes to maintain access to Financing materials. For example, processors may wish to assure a supply of birds in order to get as near The methods of financing the poultry industry full capacity as possible. They may contract with undoubtedly contribute to its principal problem- growers when supplies are limited. Forward in- low prices and marginal returns. tegration usually has the maintenance of the mar- Few growers are still able to continue as inde- ket position as its purpose. Feed manufacturers pendent operators. Throughout the broiler in- have integrated to try to hold their volume. They dustry the amount of integration has increased. are strong factors in production and, in some One of the principal reasons for this trend has cases, include all phases of integration except been the increasing need for more financing. Be- retailing. cause operators tend to be more responsible finan- Ownership integration is one brought about by cially, more liberal credit has been extended to merger or by expansion of a firm. Contract inte- integrated operations or to those persons who gration coordinates nominally independent enter- have, in their normal iDusiness activities, used prises by a system of contracts. Probably 95 per- considerable credit. Feed manufacturers are an cent of the broilers are grown under some type example of this group. of vertical integration or contractual arrange- Local banks, their correspondent city banks, ment. This is due primarily to capital and credit and the Production Credit Association largely requirements, reduced unit costs, improved qual- finance the broiler industry through credit ex- ity, better alinement of output with other stages, tended to feed manufacturers, dressing-plant especially processing, and reduced operation un- processors, hatcherymen, and integrated opera- certainties as to capital inputs and market outlets. tions. Much of this money is loaned at the local level to growers with mortgages as collateral. Because of the larger volume base, better man- Some of the larger cooperatives get their money agement and service, more research, and easier through the Bank of Cooperatives, especially for maneuverability of sales are possible. An inte- processing and other marketing purposes. Much AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE of the money for broiler-house construction has may receive little or no return for their labor. come through the Federal Land Bank Associa- In general, growers with inadequate housing and tion, the Production Credit Association, and in- equipment, poorer-than-average feed conversions, dividuals. The loans are usually payable over a high mortality, or poor condemnation records find 5- to 20-year period and are secured by mortgages. it increasingly difficult to get contracts when The Farmers Home Administration makes loans weather is adverse, output is curtailed, or broiler for the development and operation of broiler pro- prices are depressed. In recent years, this has duction on farms no larger than family farms. been around Thanksgiving and Christmas. To Established broiler producers may obtain credit obtain maximum returns, producers need to make to continue or to make needed adjustments in full and continuous use of their facilities and their broiler operations. FHA, however, only labor. Contractual arrangements are very finances the establishment of broiler enterprises important. on a limited scale. Insurance companies also Production operations are financed in many make mortgage loans in some areas. ways, such as open account, no loss, share, flat One of the reasons for the rapid expansion of fee, labor, and feed conversion. With the open- the poultry industry in the South has been that account plan, the grower buys his feed, chicks, financing is easier there. A dollar goes farther, medicine, vaccines, and other supplies from the especially in poultry-house construction. More dealer, who takes a chattel mortgage on the birds. capital has been available to invest in poultry The dealer supervises the operation, does the sell- enterprises there. ing, collects payments, and credits the grower's account. The dealer does not assume the produc- tion or price risks. Contracts The guaranteed no-loss plan is similar to the Good contracts state terms concisely and divide open-account plan except that should the income fairly the responsibilities of the grower and man- be less than the credits extended, the dealer ab- agement, or the company with whom he has a sorbs the loss and closes the account. The grower contract. Most broiler growers are concerned loses his labor and the; returns on the use of his with two major risks, which generally make them house and equipment. He, of course, directly or either unable or unwilling to finance their own indirectly, pays for th0 guarantee against loss. broiler operations. The first is the risk of unusu- The share contract was used extensively in the ally high mortality and the second is that of un- eastern broiler-growing areas. The feed dealer usually low market prices or sometimes a lack of usually furnished the feed, chicks, medicine, fuel, a satisfactory market for their birds. litter, and other produ(îtion items, charging them In most contracts the firm supplies the baby to the grower's accounjt. The grower furnished chicks, retains ownership of the broilers, assumes the broiler house, equipment, and labor necessary responsibility for marketing the birds, and to grow the birds to marketable age. The dealer promptly pays the grower. The firm also sup- retained title to the birds and made the decision plies feed, supervision, medicine, vaccines, and on marketing. After iieducting the charges for disinfectants. It assumes most cash losses. The feed, chicks, and other ¡supplies from the net pro- grower supplies labor, housing, equipment, fuel, ceeds from the broilers | sold, the dealer retained a litter, and miscellaneous items. share of the remaining I proceeds and remitted the The out-of-pocket purchases of the grower are rest to the grower. The share varied from 90-10 usually low. However, his costs should be taken (90 percent to the grower and 10 percent to the into consideration. They include repairs, de- dealer) to 50-50. If the proceeds were less than preciation, taxes, interest, and insurance. Re- the charges, the dealerj stood the loss, except for pairs are a part of the cost of trying to stay in his markup. The gro^j^er received no return for business. The grower must get back the cost of his labor or for the ^se of his buildings and depreciation or he is out of business when his equipment. Other types of contracts replaced houses and equipment are beyond repair. The the share contract becatise of the unwillingness of grower is usually taxed on everything he owns, growers to take the risks involved and because including land, houses, and equipment. Insur- of the growth of the efficiency-type contracts. ance is a justifiable protection against losses that Another share-type jcontract was used exten- might wipe him out. He is responsible for per- sively during the perioji when broiler prices were sonal injuries. The grower gets the manure depressed and integratibn was spreading. In this produced. contract, feed was charged at ingredient cost, and There are many kinds of production contracts. the hatchery received |a minimum agreed price Most contracts guarantee the grower at least for its chicks. The grower, hatchery, and feed something for the use of his houses and equip- mill divided the profiis 38, 25, and 37 percent, ment and for electricity, water, and minor cash respectively. Operatoi?s of the feed mill and outlays. When prices are depressed, growers hatchery assumed lossfes at 60 and 40 percent, COMMERCIAL BROILER PRODUCTION

respectively. The grower, in case of a loss, re- 1,000 chickens started. A payment is made on a ceived nothing for that lot of broilers. However, feed-conversion factor, a differential according to he usually received more per 1,000 broilers when the selling price, or both; point spread; or cost the selling price was relatively favorable than of production. No perfect contract has been de- under a guaranteed no-loss or the share-the-profit vised to take care of all conditions. Some of the contract. variations in the contracts concern fuel cost, dis- Under the flat-fee contract, the dealer furnishes tribution of profits, floor space allowed per chick the chicks, feed, medicine, vaccines, and other started, allowance for putting insulation or cen- production items and does the selling. The pro- tral heating in the houses, penalties for condem- ducer furnishes the house, equipment, and labor. nation losses, extra allowance for cost of fuel dur- The dealer retains title to the birds and pays the ing colder-than-average periods, cost of disinfec- grower a guaranteed minimum per chick placed tants and of applying them, cost of litter, cost of per week or per pound of broiler marketed. The cleaning out houses, and cost of catching and latter is generally considered preferable because hauling birds to market. of a direct reward for low mortality. Another form of this contract provides that In most broiler areas, the condemnation losses are charged to the growers. Some operators give the minimum payment drops when the price per a fuel allowance to the grower when the weather pound of broiler sold drops below a certain price. For example, the contract payment may drop is more severe than usual. This tends to increase feed conversion and reduce mortality and condem- from 2 to 11/2 cents per pound of broiler sold nation losses. Growers who have or put in insula- when the price per pound of broiler sold goes below 15 cents per pound. tion in an approved way are usually given an allowance to help reimburse them for it, if they The labor contract is similar to the flat-fee con- are not paying the fuel bill. tract, except that the grower is paid a fixed wage by the dealer, usually on a weekly basis. The Contracts vary with different dealers and inte- plan may be used when houses are leased. grators. They may combine features of various There are several types of "efficiency" contracts, types. Company-owned broiler farms result pri- and the trend is toward their use. Basically the marily when it is not possible to get growers with grower gets a percentage of what he saves the either adequate houses or managerial ability. managenient. This type of contract provides the Managers of company-owned farms often are grower with an incentive to practice good man- supplied a house, are assured a minimum income, agement. The management retains title to the and then are paid a bonus for doing a better-than- broilers, supplies all production items, supervises average job. Farms may be owned or leased by production, markets the broilers, and assumes the the company. There are several reasons for loss responsibility. The grower furnishes houses, control by either ownership or leasing. The prin- equipment, fuel, electricity, and water. cipal one is that contractors have the responsibil- One contract pays a fixed price per pound of ity for production, but insufficient authority over broiler sold with an increase or a decrease in the producers to match their responsibility. Some of base rate depending on the feed conversion of the advantages of expansion by leasing over own- each batch. For example, the grower may have ership as far as integrators are concerned are the a guarantee of a cent per pound. Market price lowered fixed costs that are direct business ex- is not a factor. The grower is paid 0.1 cent per pense, conservation of capital, better utilization pound for each 0.1 pound below 2.5-pound feed of labor between farm and nonfarm work, and conversion and the same, 0.1 cent per pound, for tax advantages. In some cases, the grower, in each 0.1 pound above a 3.0-pound average weight addition to leasing his houses, also works for the and for each 0.5-percent mortality below 4-percent integrator or contractor on a fixed salary or labor mortality. contract. Modifications are based on "point spread" or Cost-of-production contracts are being used to the "production efficiency" index. The point reward those growers who get good feed effi- spread, described in detail on page 29, is the re- ciency and use enough, but not too much, fuel lationship between the feed-conversion ratio and and medication. The many different types of the live weight of the birds at the time of market- these contracts include a guarantee payment per ing. An average weight of 3.33 pounds and a 1,000 birds and a payment of an added bonus per pound to the grower for profit over the feed conversion of 2.50 gives an 83-point spread. break-even point and a reduction of the same These relationships may also be expressed as the amount for a loss below the break-even point. production efficiency index by dividing the live Another type predicts an average cost for the weight by the feed-conversion ratio. For exam- period during which the birds are to be sold, ple, the index for the weight and conversion above and payments to the grower vary above or below would be 1.33 (3.33-^2.50). the average. The grower and the contractor Another contract pays an agreed amount per split the profits, if any, above basic production AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE costs and payments made to the grower. In tunity to turn over responsibility to the grower. another type, the contractor averages the cost When the grower and his family prove them- during the week, month, or quarter for all selves capable of making the day-to-day deci- growers and pays a bonus to the best growers. sions, they will usually have the opportunity to Less efficient growers get something, but usually do so. In contract farming they have a new have difficulty renewing their contracts. variation of the traditional system of family By its survival, contracting in one form or farming. another has demonstrated that it is a more sat- The type of contract that exists between the isfactory system than any alternative that has hatchery and the producer of hatching eggs has been mutually acceptable to participating parties. an important bearing on the wide fluctuation in Contracting is firmly established in the broiler broiler prices. The industry could adopt a industry. Most broiler growers will not finance their operations independently even when they policy of compensating the producer during those can. The extent to which the grower under the periods when it is necessary and advisable to contracting system loses his independence to a reduce or stop setting eggs. An average-volume considerable extent depends on his attitude and guarantee is sometimes used to assure hatching that of his family. Servicemen, representing eggs when wanted, yet cut off supplies when management on the farm, welcome the oppor- not needed. COST OF PRODUCTION

General Guide his efficiency. For information on labor effi- ciency, see page 7. The cost of producing broilers varies with The usual objective is to lower production every batch. As a guide, the percentage of each costs to give greater profits. Production costs item, other than grower payments (labor and generally are lowered if one combines all the overhead), to be considered in the cost of pro- improvement possibly in the breeding of the ducing broilers is approximately as follows: broiler stocks used, nutrition and feeding, pre- vention and control of disease, and management, Item Percent including environmental control. This requires Feed 71.00 close cooperation between the operator, the serv- Chicks 21.80 ice supervisor, and the grower. If there is Fuel 2.25 Medication 1.8 friction or a lack of confidence between the super- Vaccination 1.35 visor and the grower, optimum results rarely are Litter .9 obtained. MisceUaneous -9 When contract payments are included in the Baby Chick Cost costs, the percentages are approximately as The cost of baby chicks has been reduced follows : because of improved hatchability. Most of the Item Percent reduction has been due to the decreasing costs in hatching as hatchery size increased and fuller Feed 62.4 Chicks 19.2 use has been made of facilities. The trend, Grower payments 12.0 especially since 1955, has been to fewer but Fuel 2.0 larger hatcheries. The total production has in- Medication 1-6 creased enormously. The relatively stable year- Vaccination 1-2 Litter -8 round demand for broiler chicks has resulted in Miscellaneous -^ greater use of facilities. With integration, a much better balance has existed between hatchery Feed is the largest cost item. Feed and chick capacity and the needs of production and mar- costs represent 80 to 90 percent of the total cost. keting. As hatchery size increased, reductions For information on cost of labor and on eco- resulted on a per chick basis in in-plant labor, nomical feeding, including cost of production cost of utilities, and overall cost of the hatchery and how to calculate it, see pages 7 and 29-32. building. The labor costs were substantially Some variation in grower costs, even within reduced. The inefficiently operated hatchery will a single enterprise, is due to different ways of probably not survive when its cost of producing doing the same job. When the result is a dif- chicks is too high. ference in weights, feed conversion, or mortality, The major factors in baby chick expense are the cost is materially affected. It is often pos- egg cost and hatchability. A 10-cent difference sible for an individual broiler grower to improve 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 equip- up 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 prob- Grower 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 per- purchases. 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 per- Labor 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 build- utes 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 auto- broilers, and some hired help probably would be "^Sf i. 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, labor- saving 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 amount of mortgage, if any. With a diminish- pound and is paid 2 cents per pound as a mini- ing level of income, the expenditures for these mum base, his return for labor is 1.09 cents per items are reduced or postponed. New build- pound. At 3.3 pounds, the labor return is 3.6 ings and equipment will require less maintenance. cents (1.09x3.3) per broiler. For four nocks Miscellaneous expenses include cost of electricity ^ per year, the basic labor income would be $144 and water supply. per 1,000 ((4X3.6X1,000)-^100). The amount Some of the most important factors affecting of labor income a grower receives is affected by grower costs are the number of flocks per year, « the fixed costs per unit (pound or broiler), what the time between batches, and the type of hous- he is guaranteed per unit in his contract, how ing and equipment used. Fixed costs become - many units he produces ( nocks X broilers per higher per broiler when only two or three batches ^ flock), and what he has in his contract as bonuses are raised in a year or the houses are not filled or discounts based on performance, selling price, to capacity. The time between batches will ^ or both. depend, in addition to other factors, on the num- In the example given here, the grower pay- ber of times per year the house is cleaned out ment should be at least $66 per 1,000 broilers and the method used. Inefficient methods of ((120+144)-^4). However, minimum grower cleaning between batches can markedly increase payments may vary from $50 to $75 per 1,000 the cost of production. The broiler house should started or from 1 to 2.25 cents per pound of live be designed for easy cleaning (see p. 13). broilers marketed. Contract payments vary con- siderably, but are usually about 1.7 to 2 cents per pound. Litter Cost Depreciation can vary with the quality of the house and equipment. Some houses are The cleaning out of the house can vary in built to last 20 and others 10 years. If of poor qual- cost. The value of the litter must be determined ity or not given proper care, they will last only 5 on an individual project basis. When the broiler years. The interest charges vary with the risk project is part of a farming enterprise, the involved and the various sections of the country. litter can be valuable. In some cases, old litter The personal property tax varies a great deal is given to whoever will clean out the house and because of differences in assessed valuation and refill it with clean litter. Sometimes nobody local tax levy. Some of the factors affecting wants it. The cost of removal also varies de- repair and insurance expenditures that the pending on the method used, such as shoveling grower will make on buildings and equipment by hand into a wheelbarrow or wagon or scoop are his anticipated earning power (his age), loading into a manure spreader. For further especially how near he is to retirement, and the information, see page 20.

SELECTION OF STOCK

Straight-Run Versus Sexed Chicks ing stock. Hybrid vigor is obtained by system- atic matings that may involve crossing of differ- Straight-run chicks are generally used for ent breeds, different strains of the same breed, or raising broilers. Growth rate and feed conver- the crossing of inbred lines. In addition to hy- sion do not seem to be materially different if the brid vigor, improvement in economic factors often sexes run together or separately. Cockerels grow results from these crosses, provided the mating more rapidly and convert their feed more effi- includes stocks having superior qualities of ge- ciently than pullets and are more profitable to netic origin. raise. Being heavier at a given age, there is more The end product—our modern white, yellow- weight over which to spread chick and con- shanked broiler—is often obtained by crossing tract fixed costs. Very little convincing data the male lines from specialized breeders with are available that the advantages of separating female lines produced likewise by specialists. the sexes, if any, offset the costs involved. Since Each line may be the result of crossing two the demand has been for only white-feathered or more strains. The male lines usually have broilers, there has been very little interest in dominant white feathers and are selected for sex-linked crosses, which facilitate separating rapid growth; meat characteristics, such as the sexes at hatching time. breast width, body depth, live market grade, and dressing yield; and rapid feathering. The Breeding Methods female line also must have outstanding growth The science of genetics has been and is being rate, high hatchability, and good, but not out- continuously utilized to improve broiler breed- standing, production of eggs of desirable size COMMERCIAL BROILER PRODUCTION

and texture. Considerable attention has been weight at 9 weeks is important. If it is desired given recently to additional factors, such as to iinprove &gg production in otherwise desir- freedom from Mycoflasma gallisepticum, feed able meat-type breeding stock, it seems advisable efficiency, skin texture, skin and shank pigmenta- to make intense selection for growth rate in tion, and, in the case of large broilers, roasters, stock that is slightly inferior in growth but and capons, feathering on the breast or absence much superior in Qgg production. The more of breast blisters. rapidly growing birds are more efficient than If male and female lines are produced by the slower growing birds. different breeders, as they often are, each line It is known that feed efficiency is inherited. must, to remain competitive, cross well with There is some question whether it is practical other lines. Progeny test and family selection for the commercial broiler breeder to select for have been effective in the development of broiler it as a specific factor. It would seem more lines. The buyer must judge the ability of male practical to assume that selection for rapid rate and female lines to cross well, whether the lines of growth at 4 to 6 weeks of age, and possibly are developed by separate breeders or the same including long shanks, is also selection for high breeder. feed efficiency. Sex-linked genes may be of con- The selection of a commercial broiler stock can siderable importance in the expression of both be the determining factor between profit and loss. growth and feed conversion. Since birds selected Extension poultry specialists and county agricul- as early as 4 to 6 weeks do not always grow as tural agents can provide information that will be expected, a further selection is desirable at about helpful in making the selection. The results ob- 20 weeks and just before they go to the breeding tained by other growers in the area from different pens. stocks on such factors as growth, feed conversion, viability, and rate of condemnation should be considered. Feathering In large broiler operations, a common practice Processors demand broilers that are uniformly is to test several stocks on one farm where suitable covered, with feathers. Because the sex-linked facilities are available and careful records are factor for feathering is inherited in such a kept. It is important that the housing, feeding, simple manner, it is highly improbable that any and management be uniform for all stocks in reputable strain does not already contain a order to obtain a valid comparison of the factors large proportion of early-feathering stock. affecting economic returns—rate of growth, The method used is to select chicks for fast pounds of chicken per 100 pounds of feed, mor- feathering at a day old and later to select grow- tality, and quality of broilers produced. The in- ing chicks for rapid growth and for superior formation will provide a more reliable basis for meat production. Selection is applied to both the selection of a stock if the tests are repeated males and females and to the parental stock on a second or third farm. The farm or farms producing crossbred broiler chicks. selected for the test should follow production Selection to obtain breeders that feather rapid- practices typical of the area. ly IS most easily accomplished at the time of In intergrated operations, the comparisons may hatching. Fast feathering is a sex-linked reces- include such factors as egg production, fertility, sive to slow feathering; hence, when mated and hatchability of the parent stock. Other con- together, male and female breeding birds selected siderations are the cost and availability of the stock and the services provided by the supplier.

Growth and Feed Efficiency Growth (final broiler weight) behaves geneti- cally as a simple quantitative character. The demand of the processor for a white bird created a problem for the geneticist, because the domi- nant 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. BN-27933 Growth (9-week weight) has been positively FIGURE .3.—Fast feathering: Left, wing of chick with correlated with other important economic factors, seven primary and seven secondary feather sheaths such as breast width, body depth, and fleshing. all of which are nearly equal in length; right, wing of another chick with similar development of feather The relationship of Qgg production to broiler 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 BN-27942 chicks. FIGURE 5.—Chicks showing contrasting feather growth: Kate of feathering can be determined in day- Left, slow feathering at 10 days of age; right, fast old chicks by the length of the primary and feathering at same age. secondary feather sheaths of the wing and the number of the secondary feather sheaths. The ment should be made when birds are 6 weeks of chick with the highest rate has well-developed age, but may be made when they are from 6 to primaries and secondaries, with six or more 12 weeks old. For these observations each bird secondaries (fig. 3, left). The next best has should be examined individually and held in a six or more secondaries, which are not so well similar position. A good way is to hold the developed but are approximately as long as the chicken by the legs in the left hand, with its head primaries (fig. 3, right). downward, and with the right hand to examine The chick of the slow-feathering type has no the width and length of the breast. By compari- secondaries, or less than six short ones, and no sons, the birds can be divided into at least four primaries, or very short ones. Figure 4 illus- grades, as shown in figure 6. trates 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 BN-27936 may be used to cut the web between the toes. In FIGURE 6.—Breast types and grades of birds to be se- any case, some means should be adopted so that lected as breeding stock for broiler production: A such chicks can be recognized at a later age. and B show desirable fullness of breast ; C and D are poorer types. (Observations made about three-quar- ters of an inch from edge of keel.) Breast Development As the breast meat is the most valued part of At this time observations may be made also on the broiler, this characteristic should be given any imperfections of the breastbone or skin, such considerable attention in any selection and breed- as curved and dented breastbones and breast blis- ing program. Observations of breast develop- ters. Any individual with such imperfections COMMERCIAL BROILER PRODUCTION 11 should not be used as a breeder. With a little breeders is very important. Foundation breeders experience one soon learns to judge accurately the should assume the responsibility for cleaning up relative breast development in birds of the same all their breeder flocks. Both male and female age. Imes must be clean. In order to facilitate the de- The different breast grades represent measure- velopment of "clean" flocks, breeders may, with ments used in poultry meat-production experi- msignificant genetic loss, relax selection for 8- or nients at the Agricultural Kesearch Center, Belts- 9-week body weight for one generation. ville. This method of classification permits four Both broiler breeder replacement and broiler grades—A, B, C, and D. If one wishes further chicks should be from parent stock free of PPLO. divisions, grades A+, A, A—, B + , B, B—, and Therefore, in commercial production of replace- so on can be used. Only males with A or B ment stock, reasonable geographic isolation of breasts and females with A, B, or C breasts serologically tested negative birds is important. should be kept for breeders. Special precautions should be taken to see that One of the best times to select breeding birds management isolation is not disrupted at any for efficient, rapid growth is at 6 weeks of age, time. and it is also an ideal age to observe breast de- velopment. As both of these observations may be made at this time, one handling of the birds is Leukosis eliminated. The amount of leukosis in broiler condemna- tions and total mortality are often masked by con- Shank Pigmentation ditions such as septicemia and airsaculitis. There is no practical test by which the infected hen, egg, Shank pigmentation is inherited. Within the or chick can be detected. A hatchery should yellow-skinned varieties there are distinct differ- not accept eggs from a breeder flock with a high ences ranging from bright yellow and orange incidence of leukosis. yellow to green and sometimes bluish shades. The ability of certain strains of birds to resist This has not been of sufficient value economically to justify much consideration. Nutrition and the virus that causes visceral lymphomatosis, the most prevalent form of leukosis, has been shown freedom from parasites and diseases affect pig- to be due to genetic factors. Culling of flocks is mentation much more than inheritance. most effective if done on a family basis, and entire families with individuals showing indications of Diseases (General) the leukosis complex, such as irregular pupils, marble bone, or other symptoms, should be elimi- Chickens differ genetically in their ability to nated. A highly susceptible strain should not be resist invasion by protozoa, bacteria, fungi, vi- used for crossing purposes. Since the disease can ruses, and parasitic worms. It is feasible to also be transmitted by direct contact between develop strains comparatively resistant to Eime- chickens in the same hatching or rearing units, ria tenella coccidium, fowl typhoid, pullorum dis- isolation procedures are essential. There is no ease, visceral lymphomatosis, Newcastle disease, known treatment for leukosis. "blue comb," and encephalomalacia. However, it has not been determined whether it is economi- cally feasible to do so in any case. Nutrients When severely exposed to respiratory disease, The requirement for certain amino acids— the strain cross progeny of good noninbred argmine, methionine, but not lysine—is inher- strains fared better than their pure parent ited. Genetic differences have also been exhibited strains. for the A, Bi, D3, E, and riboflavin vitamin fac- The S6 strain of avian pleuropneumonialike tors, the unidentified growth factors, manganese, organisms (PPLO) Mycoplasma gallisepticum^ calcium, and zinc. Again, selection for rapid an agent, or one of the agents, in the air-sac growth normally emphasizes the individuals most disease complex or airsaculitis, is present in most capable of efficiently using these nutrients and broiler breeders. The ultimate objective is to leads to the elimination of those having an ab- eliminate the infectious agent from breeder flocks. normally high requirement for them. Basically A blood test can be used to detect noninfected any individual with an abnormal requirement for flocks. It has no value in detecting individual any nutrient should be eliminated as a breeder. 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 Plumage Color routine treatment of eggs for broiler production. Growth rate and other characteristics may be As airsaculitis is the largest single cause of con- affected by the genes that determine plumage demnations, the elimination of PPLO from color of broilers. For example, the gene for silver 12 AGRICULTURE HANDBOOK 3 2 0, U.S. DEPT. OF AGRICULTURE Color sex-linkage for determining sex at hatch- ing 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. BN-27940 When hatching eggs are scarce and more small FIGURE 7.—White birds, with Cornish and White Ply- mouth Rock strains predominating, make up most eggs are set, broiler laisers observe that mortality broiler breeding flocks. tends to increase and growth and feed conversion suffer. In independent operations, broilers from apparently has to be associated with the gene that larger eggs usually bring a greater cash return extends black and with recessive white for maxi- per bird over feed costs. However, in an inte- mum growth. If white birds are desired, the grated operation, broilers from smaller eggs may dominant white gene needs to be combined with give greater total returns over egg and feed the gene causing barring. costs. HOUSING

Location year. The house should be kept warm enough, but not too warm. The litter should be kept rea- A minimum of 5 acres of land is usually needed sonably dry. Provision should be made to modify for a specialized broiler enterprise. The broiler the air condition as broilers grow. Fresh air house should be located where water drainage should be circulated, but the house should be free and air movement are good. Low lying, damp from drafts. Results are not so satisfactory when areas and valleys should be avoided. Usually an the broiler house is too cold, too hot, too wet, or open area, free from trees, is better for naturally too dry. ventilated houses. However, for southern areas, The importance of adequate housing to protect a row of tall trees on the south side of the house, broilers from adverse conditions is apparent from with branches above the eave line, may be desir- the seasonal effects on broiler results. Mortality, able for shade. Most houses are oriented in an condemnations, and medication costs are highest east-west direction. and feed efficiency is usually poorest in birds sold The cost of house construction is higher if the during the winter. Growth is best in the fall. land is not reasonably level. Usually it costs more Feed efficiency is best in birds sold in the early to prepare the site for one long house than for summer. Medication costs are also lowest in the two short ones. To avoid dampness, the floor of early summer. Hot weather adversely affects the house should be a minimum of 6 inches above both growth and feed efficiency. the ground level, and higher is desirable. There needs to be a good access road from the houses Ways by which a grower can decide on the kind to the highway because of feed and bird haulage. of broiler house and equipment in which he will The cost of getting utilities, such as water, gas, invest include personal experience and experience and electricity, should be considered. A location of neighbors and friends; advice of the service- should be avoided where the birds may be dis- man, the contractor, and builders; and informa- turbed by automobile lights. Houses should be tion from the county agent, extension service, and convenient to the caretaker's house, and the pre- poultry press. He must decide on how much capi- vailing wind should be away from his house. tal 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 Requirements have some requirements as to the size and type of A broiler house should provide clean, dry, com- the broiler unit. For the importance of fixed fortable surroundings for birds throughout the 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 best broilers come out of relatively narrow houses —24 to 30 feet wide. Wider houses are more Pole-type houses are economical to build, main- economical to construct (see p. 16). Construction tain, and clean. Pressure-treated poles are set is usually either the pole or combined pole-stud into the ground to support the roof and the walls. type. The length varies from 200 to 600 feet, Pole-type houses usually have roofs of metal and with most of them from 300 to 400 feet. For ease walls of poultry netting covered with curtains or in using 4- by 8-foot sheets of insulation, houses with conventional building materials and cur- are often built in multiples of 4-foot lengths. If tains. If panels are to be used, the more conven- houses are too long, the cost of preparing the site, tional construction with a foundation and studs is especially in hilly country, may be too high. The preferable. capacity of new houses usually varies from 7,200 In broiler-producing areas where winters are to 20,000 broilers. All the birds may be in one cold, the better broiler houses will have insulated pen, or pens may have as few as 1,000 birds. The ceilings and walls. Often they have central heat- trend is to pen units of 1,200 to 2,500 birds. ing and may have controlled fan circulation. Sidewall height in houses is usually 6 to 8 feet. In areas with warm winters, houses are usually If there is no ceiling or insulation is placed on the less solidly constructed. As a result, production underside of the rafters, a 6-foot height will nor- costs may be higher in both winter and summer. mally give adequate headroom for cleaning equip- More attention is being given to both insulation ment and sufficient opening for natural ventila- and ventilation in all areas. tion. Roofs are usually of galvanized iron or In the South, extreme heat and occasional aluminum, with insulation or 15-pound asphalt severe cold are both problems. Some wide-open felt under them. houses are being modified to include at least roof If on-the-job constructed ridge ventilators are insulation and adjustable curtains. More atten- used, the north side is usually closed and the south tion is being given to having enough heat when opening can be closed when desired. Many new it is needed, so that adequate ventilation can be houses have one 4-foot long, rectangular, pre- provided. fabricated metal ventilator per 1,000 broilers. Broiler houses in the various areas are of many It can be adjusted by means of a chain or rope types and dimensions and are constructed of many so that it can be wide open, entirely closed, or one kinds of materials. In the North, concrete floors side can be open at any time. are usual, whereas in the South, they are rarely It is usual to have double doors at each end so found. that a manure spreader or truck can be used for Many of the new houses are 24 to 40 feet wide, litter handling and for cleaning the house. The with gable-type roofs. The consensus is that 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 els. Drafts that might chill the birds should be outside wall to aid in loading birds going to avoided. Enough circulation should be main- market. (Fig. 8.) tained to keep the litter dry. Young chickens are The overhang at the eaves is usually 2 feet. often overventilated. For information on envir- Windows or upper openings may have panels onmental control, see page 15. covered with various curtain materials or curtain To get the best broiler performance, the house materials without frames. The upper panels may should be as warm as possible without stressing swing in at the top, with or without hinges (fig. the birds. They should be kept as comfortable as 9). The lower openings of this house may be is economically feasible. There should be no un- closed with curtain material or panels or be win- repaired holes in the walls or roof, no misfitting terized with 15-pound felt. These lower panels, door and panels, nor too much window opening. when used, swing out. The lower panels may be Insulation retards the flow of heat and helps covered with metal, wood, insulation material, or maintain a more desirable temperature in the curtain material, similar to the upper frames. house. It is much easier to control the tempera- Winches and cables are often used to control ture and ventilation in a house if it is insulated. panels from a convenient point in the house (fig. The way the house is managed will, to a consider- 10). All openings to the house should be covered able extent, determine whether the insulation is with 3^-inch mesh wire to keep out wild birds. of value. It may be as important as the "R" val- Although maintaining adequate temperature is ues supplied. Insulation materials vary in effec- of first importance, constant attention is needed tiveness and cost. They should be economical, to ventilate the broiler house properly. In general, efficient in stopping the flow of heat, reasonably narrow houses are easier to ventilate. Attention permanent, easy to apply, able to resist wind and should be given to weather forecasts, especially (ire, and resistant to wetting. They should not of windy weather, so as to anticipate the need warp and should resist rodents and insects. They for quick adjustments of frames, curtains, or pan- 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. birds in hot weather, to give more positive ven- Some materials have reflective properties as well tilation, and to make management easier by re- as built-in vapor barriers. To be effective, re- ducing the time and some of the drudgery re- flective surfaces must be exposed to the air space. quired to care for the birds properly. The final The general rule for ventilation in the space result is an improved market quality of birds and between the roof insulation and the roof is to pro- higher income. vide openings equal to one three-hundredths of A correctly designed and properly adjusted the building floor area. This type of ventilation air-inlet system is important in attaining these could consist of openings along the eaves above objectives. A proven system should be used or an the insulation and some ventilators in the ridge or engineer consulted. The operator usually sets the gable ends of the roof. timeclocks and thermostats once a week accord- ing to the age of the broilers or the desired tem- Controlled Environment perature and more often when there are extreme weather changes. It is essential not to throw The primary objectives of using windowless, away needed heat by excessive use of fans. fan-ventilated, insulated broiler houses are as fol- About 25 percent of the maximum capacity of lows : To provide a more desirable temperature, to the ventilating system is operated continuously furnish an adequate supply of clean fresh air without controls. Mechanical ventilation and without drafts during the winter, to create with insulation will not solve the problem of poor turbulent airflow a comfortable condition for management; they may add to it. 16 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE While the brooders are in operation, the ther- initial housing investment are as follows: Cur- mostats are set in relation to their heat output. rent and probable future costs of construction, The thermostats for the heating and the ventilat- probable differences in growth and feed conver- ing systems must be synchronized so they are not sion, lower mortality and condemnation losses, operating in opposition to each other. Most of interest rates, repair costs, taxes, risk, and the mechanically ventilated houses are being con- prestige. structed so the sides can be opened. Winter re- The housing and equipment costs amount to 5 sults have beeen rather uniformly good, but in to 6 percent of the total cost of production. They "* some cases, sidewall panels have had to be re- range from about 50 cents to $1 per square foot of * moved during the hot periods of summer. Emer- floor area for the open-type house characteristic gency electrical power units seem to be necessary of the southern broiler areas to about $1 to $1.50 ^ because of high or total losses in case of power per square foot of initial investment for houses failure. The use of electricity for the fans can insulated overhead, ventilated with fans, and 4 be estimated at about 250 kilowatt-hours per thermostatically controlled. There has been a 1,000 broilers per batch in the fan-ventilated marked increase in the width of houses and the * houses. Controlled mechanical ventilation is usu- use of insulation, especially under the roofs, in - ally installed in houses that are insulated and in most broiler areas. Wider houses cost less than which the normal bird density has been increased narrow ones per square foot of floor space, be- by 20 to 25 percent. For forced ventilation, fans cause there is less sidewall to enclose and they should be selected and controlled to deliver from have the advantage of having less exposed area 1 to 3 cubic feet of air per minute per broiler through which heat will be lost. In general, the against l^-inch static pressure. more the investment in housing, the lower the The balance between insulation, forced venti- fuel and repair costs. lation, amount of air infiltration, and variable With better equipment, labor costs are usually temperature outside must be maintained. Unde- less. If the watering system is well planned, the sirable air conditions in the house may result if waterers can be easily cleaned. If it is easy to any factors are not stabilized. The higher initial medicate the water, much labor can be saved. operating cost of the windowless house must be However, the cost of production can be high if justified in terms of the claimed advantages. facilities are not fully utilized. Using houses on Consideration also must be given to the need for as nearly a continuous basis as possible and filling more technical skill than is possessed by the grow- them to capacity at all times are the main ways to ers on many broiler farms. This skill can only be keep housing cost per bird low. For the effect of gained through experience. fixed or housing costs on labor income, see page To maintain a balanced environment for broil- 7. ers, prevailing and forecasted atmospheric condi- When estimating the percent cost of materials tions of temperature and Humidity should be con- for a pole-type insulated house with a concrete sidered. Fans are being used in broiler houses to floor, the lumber to frame the structure will be help force the required air through the house in about 25, the covering materials about 40, insula- order to remove polluted air, dust, and the mois- tion 20, and concrete floor 15. If labor is esti- ture evaporated from droppings, from around mated at about 40 percent of the total building waterers, or from rain entering the house. The cost, the materials for the structure will be re- fan and blower assemblies and their controllers duced to about 15 percent and the covering mate- and protective equipment should be selected to rials to 25 percent. Care should be taken in modi- meet the particular airflow requirements of the fying plans to reduce costs. The saving may be situation. It should be possible to provide at least lost because of increased cost of repairs and main- 3 cubic feet of air per minute per broiler. Poul- tenance and decreased life and safety of the build- try-house fan motors must be totally enclosed be- ing. Engineering assistance should be requested cause of the dust, moisture, and ammonia fumes. before too much modification is attempted from In well-insulated houses, filled to capacity with proven plans. birds, more air can be moved to remove moisture It is possible to use table 2 (p. 30) to estimate without seriously lowering the temperature. A the possible advantage of using insulation in the room temperature of 60° to 70° F. is generally broiler house, or otherwise building a house that desirable. 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 Housing Costs $4.50 per hundredweight, the feed cost of the broiler is 3.33 times 10.80 cents (table 2), or 35.96 Research is needed to find out what housing cents. If the feed conversion is 2.3 pounds, the costs are justified. In the meantime, some factors feed cost per broiler is 3.33 times 10.35 cents to consider in choosing between low and high (table 2), or 34.46 cents. The feed-cost saving COMMERCIAL BROILER PRODUCTION 17 fer hroiler for each 10-point saving in feed con- life of a house for depreciation purposes, 74 cents version is 1.5 cents (35.96—34.46). The feed- (7.4X10) per square foot could be expended in cost saving per pound of live hroiler for each 10- housing costs for each 10-point anticipated im- point saving in feed conversion is 0.45 cent provement in feed conversion based on $90 per ton (1.5^3.33). of feed. Allowing 0.8 square foot per broiler and four It would seem that some houses could be broods per year, about 16.5 pounds ((3.3X4) changed with profit when there is a possibility -^0.8) of live broiler are produced per year per that improvement would result in better feed square foot of broiler house. If the saving per conversion. Eesearch is needed to determine the pound is 0.45 cent, the saving on the 16.5 pounds economics of housing in relation to livability and of broiler weight per year would be 7.4 cents condemnations and also on how to manage houses (16.5X0.45). Allowing 10 years as the normal so as to use environmental control effectively. BROODING Brooding Systems ter, or smooth black water pipes, or a few com- binations of alternate sections of "fin" and Adequate temperature is the most important smooth black pipes with equal heat output. Vul- factor in successful brooding, because without it can, or fin, pipes have about five times the radia- adequate ventilation in the wintertime is impos- tion of smooth pipes, but are more difficult to sible. It is possible to raise broilers with many keep clean and lose some of their effectiveness types and makes of brooding equipment. Some when dirty. of the factors to be considered when deciding on A hover is usually formed over the pipes. It the system of brooding to be used are the avail- may consist of reflective-type insulation, ply- ability and cost of the fuel, the size and construc- wood, 15-pound felt, or some other material, tion of the brooder house (fig. 9), especially as to placed on wood or insulated strips spaced along whether or not it is insulated, the convenience of the pipes. It is used while the chicks are small. operating the equipment, and the ease of remov- Litter is sometimes used on top of the hover, ing the hover when cleaning out the house. It is but is not very satisfactory. assumed that only those types of brooders will be A forced hot-water circulation with circulatory considered that will give good broiler perform- pumps is generally used because it responds ance. more quickly to the thermostat than the gravity- The initial investment is greater when central flow hot-water system employed in earlier instal- brooding systems for either hot water or hot air lations. Automatic controls consist of an aqua- are installed than when the canopy hovers are stat to regulate the fuel intake and the thermo- used. The cost of operation is usually less. They stat to control the circulating pumps. are more economical to operate in units of not less In the warm-air system there is a centrally than 3,000 broilers. The hot-water brooding sys- located warm-air heater, from which warm-air tem responds more slowly but holds its heat pipes run each way to a series of hovers. The longer than the hot-air system. This might be warm air is forced through the heating ducts of advantage in case of power failure if auxiliary by a blower. The returned air is wholly or power is not available. Central heating systems partially drawn from the heated pen. The offer less fire hazard than the canopy hovers, ex- system is controlled primarily by thermostats cept those using electricity as the energy source. placed at the far ends of the brooder house. The They are more easily controlled by thermostats principal disadvantage is that, in case of a and other automatic devices because fewer are power failure, there is no heat available when the required. However, inexperienced operators may blowers stop operating. Otherwise, there is no not be able to maintain as uniform temperature reason why equally good results cannot be under the brooding canopy or areas. The usual obtained with either system. fuels for central systems are natural or liquefied When an insulated mechanically controlled petroleum gas, coal, or oil. house is used, the need for a central brooding A central heating system should be designed system may be more difficult to justify. One of by a qualified person for the building in which the principal reasons for the central systems it is to be located. Hot-water systems were is the more favorable room temperatures that used with pipes laid in the floor. They proved can be maintained in both insulated and non- less efficient and otherwise less satisfactory than insulated houses. when pipes were laid above the floor and are For commercial broiler production, the 1,000- rarely used commercially now. The above-the- chick hover should be the choice over the smaller floor hot-water system usually consists of a hori- hover whether heated by gas, oil, or electricity. zontal bank of six pipes of 2-inch inside diame- 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 infra- times sufficient air must be supplied to the burn- red types. It is usual to allow 10 square inches ers to get enough oxygen for complete combus- of canopy hover space per chick. For winter tion. brooding in noninsulated houses, not over 750 At one time coal-stove hovers were very pop- ^ chicks per hover are recommended. In insulated ular in the North and East. They were excellent houses, allow 850 chicks per hover. In mechani- for winter brooding, but were difficult to regulate cally ventilated insulated houses, it may be in mild and hot weather. Oil brooders are sat- possible to start 1,000 chicks under a 1,000-chick isfactory, if the oil is reasonably priced. There canopy hover, allowing only approximately 7.3 are two types, one with and one without vent square inches per bird. pipes. When wood is available and cheap, the Fuel consumption should be considered when wood-burning hover is satisfactory. However, ^ comparing canopy and infrared-type gas hovers. few are used any more because of the labor Gas hovers are usually easy to regulate and involved. Electric hovers are not extensively i relatively inexpensive to operate. They may not used. In areas where either coal or oil is provide enough heat in extremely cold weather. available and cheap, supplementary heaters are Like oil and electrically heated hovers, most gas often used effectively in cold weather to give hovers are cold-room brooders and do not heat extra needed heat when gas and electric hovers the room to the extent that may be desired. This are used. Because they are cold-room brooders, is particularly true in noninsulated houses, gas and electric hovers do not materially heat especially those with considerable air leakage the room. Consideration should be given to the (ridge ventilators with open sides, or poorly relative economy of using supplementary heat, constructed panels and walls, or both). In in- more hovers with fewer chicks per hover, or sulated houses, gas hovers often do not heat the larger canopies with more space per chick. room to the recommended temperature without maintaining too high a temperature under the Environmental Factors hover. A warm-room, gas-burning hanging brooder, often referred to as the "pancake" type, Careful management is necessary to give as is now being used (fig. 10). It helps to raise the good air conditions as possible for temperature, ventilation, and humidity. The action of the room temperature. chicks in itself is not, at all times, an adequate Gas and nonvented oil-burning hovers also guide to temperature. With multiple-unit or have a disadvantage of giving off moisture as large brooders, it is not possible to judge the well as gases into the house. Every pound of temperature of an individual hover by the posi- liquefied petroleum gas (LPG) burned will give tion of the chicks around it. Each hover should off 1.6 pounds of water, 3 pounds of carbon be equipped with a thermometer. The temper- dioxide, and some monoxide gas. Every pound ature should be read once or twice daily, depend- of fuel oil gives off 1.2 pounds of water, 3.1 ing principally on the room temperature and the pounds of carbon dioxide, and some monoxide age of the chicks. The necessary adjustment gas. For each pound of LPG or fuel oil burned, should be made. The brooding equipment should it requires about 300 cubic feet of air at 60° F. be capable of giving enough heat at all times. to remove the water and gases. A gallon of The recommended temperature at chick level LPG weighs about 41/2 pounds and has approxi- at the edge of the hover is 95° F. for the first 2 mately 80,000 usable British thermal units days, with a reduction of 3° daily for 5 days to (B.t.u.) per gallon. A gallon of fuel oil weighs 80° ; second week, 80° ; and from the third week about 7 pounds and has about 100,000 usable on 75°. Avoid any temperature below 60°. For B.t.u. per gallon. The 1,000-chick brooders have the best feed efficiency with good growth, and heat outputs that range from 12,000 to 30,000 especially when there is any sickness present, B.t.u. per hour. a room temperature of 75° is recommended. LPG is extensively used as a fuel for brooders. When chicks circle wide or leave the hover, it Propane and butane are its main constituents it too hot or the room temperature is comfortable. and LPG is usually a mixture of them. During If they tend to crowd under the hover, it is too low-temperature periods, butane might not cool. In either case, the temperature is probably vaporize fast enough to furnish vapor for the extremely high or extremely low and adjustment needs of the brooder, whereas propane might is needed immediately. Avoid especially temper- furnish the required amount. Propane develops atures below 80° the first 2 weeks and over 85° about the same tank pressure at —10° F. as after 6 weeks. Avoid wide daily fluctuations of butane develops at 70°. Therefore, gas suppliers 20° to 30° in the first 6 weeks. Temperature regulate the ratio of butane and propane in the fluctuations should be watched, especially when fuel to provide satisfactory operation at different you are trying to brood without heat in warm atmospheric temperatures. They also add al- weather. cohol to the fuel during cold weather. At all With uninsulated houses, the heat requirements COMMERCIAL BROILER PRODUCTION 19 will be greater than with insulated houses, source of disease outbreaks or breast blisters. provided the advantages of insulation are not Excessive dust may trigger a respiratory trouble. dissipated by excessive air leakage through open Both conditions can be avoided with proper • or leaky walls, uncontrolled ridge ventilators, or ventilation made possible by adequate heat. in similar ways. The outside temperature is a Dust has sometimes been a major problem with considerable factor in heat requirements and is fan ventilation, probably because of lower hu- one of the reasons why winter broods are usually midity and overdrying of the litter. less profitable than those at other times of the If broiler houses are equipped with winches year. and cable (fig. 10) to quickly and effectively If everything else is normal, the chicks will adjust frames and curtains, the houses will often ^ be comfortable when the relative humidity is be better ventilated. It is even better if the 50 to 70 percent. They may show discomfort by grower stays around the houses and spends , huddling at 45 percent or less when the room plenty of time with his birds, so that he can temperature is 60° to 70° F. anticipate the required action. Insulated houses can be ventilated less than For information on the size and type of house, noninsulated houses and still maintain good insulation, mechanized ventilation, and use of conditions. The reason is that more moisture fans, see page 13. is removed per pound of ventilated air at higher temperatures in insulated houses than at in- creased ventilation at low temperatures in non- Hot-Weather Problems insulated houses. The heat given off by a thousand chicks at a In insulated houses, ammonia may be more of day old is only about 3,600 British thermal units a problem because of insufficient ventilation. (B.t.u.) per hour, but at marketing age (3.3 In uninsulated houses, ammonia is partially com- pounds) it is 42,900 B.t.u. per hour. Tempera- bined with condensing moisture. tures from 85° to 95° do not markedly affect An adequate source of heat helps to provide growth and feed efficiency in chickens up to 6 adequate ventilation. Often a broiler house is weeks of age unless the humidity is also 55 per- closed tight with plastic to conserve heat. As a cent or higher. Above 95°, heat prostration result, the air becomes foul and the litter wet. may occur, especially at 75 percent relative hu- With inadequate ventilation, ammonia may build midity or higher. At any humidity, the 6-week- up to the extent that the eyes of the chickens old and older broilers start to suffer at 85° and and the grower are affected. Chickens affected over, and heat stress occurs. by ammonia will jerk their heads as if to clear When drugs are used in the drinking water, them. This production of ammonia depends on the dosage prescribed is based on normal water the amount of fecal matter in the litter, litter consumption. High temperatures will result moisture and temperature, litter aeration, and in high water consumption, which may give an possibly the porosity of the litter. When the overdose of the drug. Conversely, low tempera- air is below 32° F., there is no noticeable am- tures result in low water consumption, which monia. Above 32° and with litter-moisture con- may give an underdose of the drug. tent above 29 percent on a dry basis, ammonia In addition to high temperature and humidity, production is noticeable. the stress can be increased by having deep litter, The chicks may be chilled if there is too much insufficient water, too shallow water in waterers, ventilation. Overventilation that disperses overcrowded birds, weeds outside the house so needed heat is costly. A draft or a wave of high they cut off air circulation, and by doing cold air directly on the birds should be avoided nothing to relieve the condition. Whitewashing at all times. Correct ventilation is an individual or painting the roof aids in heat reflection. problem. Vented central heating systems do not Water sprinklers on the roof will reduce the put additional moisture into the room as do non- roof temperature and therefore the radiation of vented gas and oil-burning hovers and require the heat from the roof. Increasing the turbu- less ventilation to remove the moisture. The lence of the air by increasing air circulation heat output of broilers after they are 6 weeks by natural or artificial means will reduce the of age is many times that of baby chicks. This body temperature and respiration rates. is true of moisture output. Ventilation must Deep, cool, clean drinking water should be be stepped up as broilers increase in age and provided. For water-consumption rates, see weight. Because needs ñuctuate so, the grower page 37. Water consumption at 95° F. is at should be present in order to give attention to least double that at 70°. Be sure the birds do each situation as it arises. Neglect of the flock not run out of water at any time. At least four can mean a stress on the birds, which can result 8-foot waterers per 1,000 broilers should be pro- in colds and chronic respiratory disease complex, vided when the temperature is above 90°. Dur- in spite of previous careful attention. ing hot weather, the use of lights becomes Wet litter is never desirable. It can be the 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 Some of the risks of not cleaning out after the hotter hours of the day. Keeping the litter every brood include more losses, due especially shallow helps to avoid some of the heat of to chronic respiratory disease (CED), leukosis, fermentation, which results with deep litter, and and aspergillosis. There may also be more ^ also the birds can come in contact with cooler roundworms, tapeworms, and coccidiosis. On soil and lose heat from their bodies by con- the other hand, losses from avian nephrosis duction. (Gumboro disease) may be as high or higher if the litter is changed. With thorough disin- fection, security management, and replacing Litter old with new litter, mortality may sometimes be The usual kinds of good-quality litter ap- materially reduced, even when avian nephrosis ^ parently do not affect growth, feed conversion, or is the problem. mortality under general growing conditions. A The cost of removing old litter and adding new i good-quality litter is dry, loose, and absorbent. varies considerably. In commercial practice, It should contain no injurious materials or molds much hand labor is now replaced by use of and be reasonably free of dust. Convenience various kinds of mechanical equipment, includ- and economy are important considerations. ing power loaders, bulldozers, manure spreaders, Shavings are the most popular litter, wñth saw- and front-end loaders. dust second. Sawdust should be covered for Deep litter is especially important on dirt 3 days, as young chicks sometimes eat it. Peanut floors, because if it is dry, it will prevent penetra- hulls, cane" pulp, rice hulls, flax, peat moss, wood tion of the cold from the ground during the chips, and %-inch pine-bark litter can be used. low-temperature periods. In the winter at least Crushed corncobs may cause more breast blisters 6 inches is desirable. Two to four inches is than other litters. Excelsior waste tends to mat usually a good depth for the summer. The and cake. Chopped straw, about 6 inches deep, availability and the cost of litter become factors is preferred for large broilers and roasters to (see p. 8). prevent breast blisters. To prevent disease from being tracked into the house, the house should be locked after Preparation of House and Brooder clean litter is in place. A shallow pan of dis- One of the most important ways to prevent infectant should be placed at any entrance in and reduce losses from disease is a strict security use. The disinfectant should be kept reasonably management program. In addition to the gen- fresh and undiluted. eral sanitation program (p. 26), certain specific Litter can be reused provided a severe disease things should be done in preparation for and outbreak has not occurred. It is usually eco- during the brooding phase. nomical to do so. Growth, feed conversion, and market quality, other than breast blisters, are not The primary objective is to break the cycle of usually affected, provided the litter is in good infection. Every bird should be off the farm condition. The prevailing broiler price, the cost before the cleanup process starts. Remove all of the new litter, the value of the used litter as feed from feeders. All removable equipment, fertilizer, its condition, and the cost of and the such as hovers, feeders, waterers, and stands, time required for removing the old litter are im- should be swept free of dust, washed clean under portant considerations. A cushion of clean, dry pressure, disinfected with an approved disin- litter is the best insurance against breast blisters. fectant, and put outside in the sun while the house If litter is replaced, usually 1 week is allowed is being cleaned. Do not overlook the baby chick between batches for cleaning out and 1 week for equipment, especially fountains. Equipment that the pen to remain idle. is raised while the litter is removed should be Wet or caked litter may be due to starting washed and disinfected before fresh litter is with less than 2 inches of litter. It causes added. Nothing should be overlooked.. For dis- stresses that may lead to poorer results. Usually infectants and insecticides, see pages 26-27. more breast blisters occur with w^et litter. Some A concrete floor is easier to clean than a dirt nonspecific enteritis and mycosis may result floor. When the latter is used, it is preferable from moldy litter. To avoid excessive moisture, to clean out all the old litter after each brood. good management must be practiced. Ventila- Put in 2 inches (4 inches in winter) of neiv, tion must be sufficient and proper. The house clean, dry litter. When this is not considered temperature must be adequate. Waterers must to be necessary or advisable because of relatively be kept adjusted to avoid spillage and in good little trouble from diseases or parasites, high cost working order to avoid leaks. Stirring damp of litter or litter removal, or lack of sufficient litter prevents caking in the winter. Between time between broods, a special effort should be broods, caked and wet litter should be removed made to rake out and remove all damp or lumpy from the house. litter, feathers, and dead chicks from the old COMMERCIAL BROILER PRODUCTION 21 litter before adding a topping of fresh litter. checked and the brooder should be in operation As a compromise, litter is sometimes replaced and adjusted to the desired temperature. The entirely in the hover area, and 1 or 2 inches feeder lids and gallon water fountains should of new litter put on top of the old litter in other be in place, as well as the chick guards if they areas. The litter and dirt that are removed are used. All fountains and feeders should should be disposed of away from the houses so as usually be rinsed after disinfecting. not to blow or be tracked back into them. After the floor has been thoroughly cleaned Lights and disinfected and before the new litter is added, the ceiling and walls should be swept Probably no management practice varies more or blown clean of dust and cobwebs. Hose than the lighting schedules for broilers. Lights them down with water at about 300 pounds- are used to prevent chickens from piling or pressure. Use a good detergent. A steam stampeding when scared. Enough light should jenny is useful because the heat generated may be provided to attract the chicks to the source of be a valuable supplement to pressure and a heat. With most gas-burning hovers, sufficient disinfectant in eliminating certain diseases and light is supplied so that no additional light is parasites. After the house is dry, spray it with needed. When the source of heat does not suffice, malathion for mites and lice (see p. 56). an attraction light, or small light under the To control rats and mice, keep the premises hover, should be provided 24 hours daily for clean, have a rodent-control service use calcium about 2 weeks. Properly spaced 15- or 25-watt cyanide dust in outdoor rodent burrows, or use bulbs are usually adequate. anticoagulants, such as warfarin, pival, fumarin, Lights are used after the chicks are 2 weeks or Diphacinone in suitable baits, or buy a com- of age to prevent piling and to allow more time mercially prepared, ready-to-use bait mixture to eat. In the fall and winter, days are too and follow the manufacturer's recommendations. short. When broilers are uncomfortably hot, A good bait formula includes— they do not eat, especially in the middle of the Cups day. The use of lights at night, when it is cooler, Cornmeal 13 often results in materially increasing feed intake. Oatmeal 4 For general use, it is suggested that natural Corn oil 1 light be supplemented with all-night lights from Confectioners* sugar 1 the third week to the time of m^keting. To Anticoagulant 1 avoid piling in case of power failures, it is In preparing the house for a new brood, check desirable to allow at least 1 hour of darkness all wire screens to be sure wild birds cannot in every 24-hour period. Too intense light may enter. Close all openings with 3^-inch mesh cause stress. An intensity of 1 foot-candle at wire. Remove tall grass and weeds for at least feeder height is recommended for maximum 30 feet from the house to prevent cutting ort* gains. As broilers grow, the light intensity can ventilation and as a ñre precaution. Clean out be reduced to as little as 0.1 foot-candle and still all ditches not only to give good drainage from be satisfactory. In houses 40 feet wide, two the house but to eliminate breeding places for rows of 100-watt bulbs 10 feet from the sides, mosquitoes and other insects. The roads and 10 feet on center, and at an 8-foot height will roofs should be put in good repair, especially prove adequate, if bulbs are kept clean or re- in the fall. Check the curtains or frames for flectors are used. The rule-of-thumb practice is holes and be sure they are in good working order. one-fourth watt per square foot of floor space. Between broods, be sure that each hover is The color or kind (incandescent versus fluores- clean and free from dust and dirt, which could cent) of light does not affect growth. Blue cause a fire or an explosion. Infrared hovers lights may be used w^hen catching birds and red should have been cleaned and covered tightly lights in case of cannibalism. with a plastic bag immediately after being dis- Another program is to allow 2 foot-candles at continued. A portable air compressor to give feeder height from 2 to 4 weeks, 1.5 foot-candles about 100 pounds' pressure has many uses in the from 4 to 6 weeks, and 1 foot-candle from 6 cleaning process and can be purchased for as weeks to market. Light intensity can be altered little as $25. Check all thermostats, fuel lines, by changing the size of the bulbs. and hoisting ropes not only to assure satisfactory operation but to prevent accidents and fire. All Floor Space water valves should be in good working order. All light bulbs should be checked and cleaned. The amount of floor space allowed varies from It is desirable to have the house empty for at 0.8 to 1 square foot per chick. The actual least a week after it is clean and ready for amount will depend on such factors as the occupancy. Before the chicks arrive, all the weight at which the broilers are to be sold, the workable parts of the brooder should have been 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 average bird in the house for optimum water the year. intake and less spill. Keep debris out of the Crowding broilers will usually result in more waterers. More waste feed has been recovered culls, a lower average body weight, poorer feed from V-shaped troughs than from the deeper conversion, more cannibalism and feather pick- types. The valves on the waterers should be JTiqr, decreased market value, and higher mortal- checked daily and between each brood. ity. It is often difficult to maintain a constant For birds to be marketed at about 3 to 3% water supply in cold weather. Electric heat- pounds, usually allow 1 square foot of floor ing cable can be used to protect pipes from space in the summer. The rest of the year and freezing. The cable can also be used in trough- in fan-ventilated insulated houses, the allowance type waterers. The water is usually maintained is 0.8 square foot. For broilers to be marketed at not less than 40° F. The minimum tempera- at 4 pounds and over, allow 1 square foot normal- ture will vary depending on the location of the ly and 114 square feet in hot weather. 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 Size of Units broiler houses has a heating capacity of 5 watts per foot. The length of the cable required Houses currently being built in the major depends on the total length of piping and the broiler-producing areas will have a minimum number of watts per foot of pipe required. capacity of 7,200 (24 by 300 feet) and will Anyone not familiar with electrical installations usually approximate 12,000 (40 by 300 feet) of this kind should consult a competent elec- birds. The house may not be divided into pens trician or power-company representative. 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 Chick Guards and convenience of managing the birds, the cost of Other Management Practices the partitions, and the value of partitions in restricting disease. In cold weather the use of a 12-inch corru- gated paper circle 2 feet outside the edge of the gas, oil, or electric hover will help prevent drafts Waterers and Watering Space on young chicks. In hot-water brooding, guards are usually placed 3 feet from the outside edge of Clean water at about 55° F. should be avail- the hover. Sometimes removable 1-foot boards able. Thoroughly cleaned, disinfected, and can be used in place of cardboard. For infrared rinsed gallon fountains with wide-based, spill- brooding, these are sometimes inserted in cleats proof plastic bases should be provided at the rate on the posts along one side of the house. When of 10 per 1,000 chicks. Some hanging waterers room temperatures are 70° F. or higher, either (fig. 11) can be lowered so that the chicks have the guards are not used at all, or corrugated board early access to them. When all the chickens are is replaced by %- or 1-inch mesh wire and the drinking from the automatic waterers, the gal- guards are removed at the end of 4 days. Guards lon fountains should be removed, cleaned, and normally can be removed at the end of a week. preferably stored in a special dustproof place. Although the first 10 days are extremely im- Fountains should not be used after 3 weeks, and portant in the life of the chick, the first 2 days usually they are discontinued after about 10 are critical. Fill the fountains the night before days. Some automatic waterers can be used to remove the chill from the water. Carefully successfully from the start. place the fountains and feeders around the hover It is a good investment to have automatic so that they are easily accessible to the chicks. waterers. If the 8-foot automatic hanging Know the temperature under the hover and waterer is used, at least one-half linear inch per adjust it to outside weather. For the correct bird is usually allowed or three waterers per temperatures, see page 18. Normally the tem- 1,000 birds. One additional waterer per 1,000 perature should be 95° F. at chick level the first should be added when the temperature is 90° F. 2 days. Do not run some hovers at 85° and or above. The birds should not have to go more others at 110°. Except in a single-unit operation, than 10 feet to get water at any time. the action of the chicks is not a sufficiently reli- Waterers should be washed daily. The use of able guide to temperature. A desirable room a 5-gallon bucket with a 4-inch V cut in the top temperature is 70°. Try to maintain at least of one side is suggested. One end of the trough 60°, then chicks that wander from the hover are can be set in it as the trough is brushed or less likely to be chilled. Ventilate the house to mopped clean. The lip of the waterers, too, keep the air fresh, but avoid drafts. Discourage should be adjusted weekly to the back level of 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 area. They may be removed as soon as the chicks are eating from the regular feeders in from 5 to Careful debeaking of birds fed crumbles and 10 days. When hanging feeders are used, the pellets will materially improve the percentage of bottom pans (fig. 10) are often utilized in addi- grade A birds marketed. There are many differ- tion to some lids. ent methods of debeaking, all of which seem to be Several factors should be considered when effective, including notching so that the end of equipping a house with feeders. The two most the beak drops off. Usually one-third of the up- important are the amount of labor required and per beak between the tip and the nostril of the the cost of the equipment. However, in individ- day-old chick is removed. If debeaking is too ual situations such factors as managerial, physi- severe, growth is retarded and some mortality cal, and mechanical ability may be equally im- may result. Mash feed wastage is usually less portant. Much depends on the capabilities of the with debeaked chicks. person taking care of the birds. The cost of the trough feeders per 1,000 birds is usually the low- Feeders and Feeder Space est, but the labor cost is generally much higher in commercial houses of over 6,000 birds. New, cut-down chick boxes or box lids are gen- erally used at first for feeding the chicks, allow- It has been shown that with all types of feed- ing one feeder lid per 100 chicks. These feeders ers less wastage occurs with pellets than with allow the chicks to find the feed easily. The mash. feeders should be placed in the immediate hover The mechanical poultry feeder is probably the 24 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE most important labor-saving device the poultry- The hanging tube-type feeders (fig. 9) are man has. Without a mechanical feeder, but with sometimes preferred to the mechanical feeder, be- automatic waterers, one man will spend full time cause they require the grower to spend more time looking after a flock of 6,000 broilers. With with the birds, they are easier to adjust, and may < automatic w^aterers and a mechanical feeder, the cause less downgrading. When these hanging same man can look after 15,000 to 20,000 birds. feeders are used, fifteen 15-inch diameter tube If extra help is available during the first week, a feeders, holding about 30 pounds of feed, are sug- good grower can attend to 50,000 broilers. gested per 1,000 broilers. Probably fewer feeders A bulk feed bin holding several tons of feed, will be needed for a high- than a low-energy which can be serviced outside the house, is usually ration, because the feed intake normally is less. located in the center of the house. The mechani- With some low-energy rations, twice as many may % cal feeder has a hopper that is fed from the stor- be needed. Usually more downgrading occurs age bin. The feed is distributed in a continuous when more feeders are in the pen. t trough through the house by a motor-driven drag With labor at $1 per hour, 10 flocks will often chain or shaker, by a closed conveyor system, or pay the cost of replacing trough feeders with by hanging feeders that move to a hopper for fill- hanging feeders in flocks of 10,000 or more. ing. When sacked feed is used, it is stored near Hanging feeders are preferred to trough feeders the hopper and put in by hand. Most mechanical because they do the entire job, are easier to ad- feeders are controlled by a time switch, but a just, if properly adjusted cannot be overfilled, feed-consumption controlling device is sometimes need not be filled so often, and cause less injury to used to actuate the motor drive. the birds. One of the principal disadvantages is The original cost of mechanical feeders is usu- the tendency in most feeders for high-fat feeds ally higher than for hanging or trough feeders. to stick to the sides and hang up. The many In modern broiler production, mechanical feeders ropes or wires supporting tube feeders are some- often are economically justified. The recommen- what objectionable. dation of the manufacturer should be followed as to feeding space. It will usually approximate 10 The use of trough feeders is usually limited to to 12 broilers per linear foot of feeding space. flocks of 5,000 birds or fewer, to situations where As a rule of thumb, installation of a mechan- they are already installed, and where labor cost cal feeder or feeders is worthwhile if the invest- is not important. Usually more feed is wasted ment is no more than five times the labor saved with trough feeders, and they take up more floor in a year. If the use of mechanical feeders will space. Their principal advantages are absence of save an hour a day at a dollar an hour, the grower hanging ropes, no hang up of feed, and the grow- will save $365 annually; he can afford $1,825 for er's spending more time with the birds. When equipment. With labor at $1 per hour, 13 flocks these feeders are used, a 4-foot chick trough will often pay the replacement cost of mechani- feeder is generally preferred, allowing 10 per cal feeders in flocks of 10,000 or more. The cost 1,000 chicks started. At 3 weeks, a change is of the mechanical feeder should be depreciated made to the 5-foot broiler feeder, and 25 of annually at 10 percent, interest should be charged these feeders provide 3 linear inches of space at 6 percent, and 3 percent should be allowed for per bird. repairs. The bulk storage should be depreciated Much feed wastage is avoided by not filling at 5 percent, interest charged at 6 percent, and 1 feeders more than half full and feeding three or 2 percent allowed for repairs, depending on its construction. times per day. The labor of feeding at this rate Operating the mechanical feeder.will require can be justified in improved conversion. The 15 kilowatt-hours per 1,000 broilers. The labor space allowance is undoubtedly affected in all requirement per 1,000 broilers is reduced more by types of feeders by the energy content of the feed mechanical feeders as compared to trough or tube as well as the form in which it is fed. Less hop- feeders when a larger number of birds are in- per space is needed with high- than low-energy volved. rations and with pellets or crumbles as compared With mechanical feeders, the grower can ob- with mash. Feeders should have a lip to prevent serve the birds more frequently. It is usually "billing" and wasting of the feed. Usually the difficult to justify a mechanical feeder for fewer lip of the feeders of all types is adjusted weekly than 6,000 birds unless the age or physical condi- tion of the caretaker will enable him to benefit by to the back height of the average bird in the pen it or unless suitable labor is difficult to get when or house. All feed troughs should be kept level needed. Some of the disadvantages of mechanical to assure optimum feed intake with minimum feeders may be greater waste of feed, greater feed wastage. Some growers hang their feed difficulty in adjusting to proper height, more ten- troughs. When either tube or trough feeders are dency for growers to neglect birds, and inability used, bulk storage bins are usually placed to of growers to maintain the equipment properly. serve two pens. COMMERCIAL BROILER PRODUCTION 25 MANAGEMENT PRACTICES Good management practices are summarized on avoided by good management and nutrition. En- the inside front cover and a management guide is vironmental stresses include too high, too low, or given on the inside back cover of this handbook. sudden changes in temperature; too high humid- ity at high temperatures; too many chicks per Size of Operation brooder; too little floor space; faulty ventilation; insufficient feeding or watering space; improper In general, a person will not undertake a debeaking; disease outbreaks; loud noises or broiler enterprise unless it will provide at least other things that frighten birds; and sudden a quarter of his income. Most growers have at changes in personnel and in management prac- least 5,000 broilers per lot. So many other fac- tices. tors are involved that apparently little or no Common nutritional stresses include all nutri- relationship in general exists between the size of tional deficiencies, mineral imbalances, certain the enterprise and the rate of growth or feed effi- hormones, most drugs, and certain ingredients at ciency obtained. A small broiler raiser may be higher than optimal levels. Chickens may react able to do as well on a per bird basis as a large to mild stresses in such a way that no eifect is producer. However, as the number of birds in- observable. However, chickens subjected to both creases per grower or per building, the standard environmental stress and nutritional deficiencies of housing, equipment, and general management are more liable to succumb to disease. Under needs to be higher for economical results. stress, requirements are probably increased for The number of birds cared for by a family unit certain amino acids, vitamin A, and unidentified tends to increase on either a full- or a part-time growth factors. Nutritional requirements for basis. The amount of time given to the enter- practical broiler formulas allow for these in- prise is an important consideration. The amount creased needs. of available finances may be a limiting factor. The number of broilers a family unit can handle satisfactorily will depend principally on the abil- Grower Supervision ity of the individuals, the size and arrangement Growers may be supervised by the feed dealer of the house or houses, and the labor-saving or by a serviceman. The duties of the service- equipment, especially in the feeding and watering man vary with almost every situation. Manage- operations. For further information, see page 7. ment policies differ in the amount of discretion allowed the serviceman and that allowed the Labor Efficiency grower. A grower who has proven his ability is often given much greater leeway than one who The two best assurances of good management has not done so. The best growers are not neces- are a congenial working relationship between the sarily with the company offering the greatest growers and the servicemen and the selection of money return, although there is usually no better growers who either stay home when they have incentive than the financial return. If a com- chickens or have efficient assistance. Considerable pany and the serviceman are consistently fair to variation exists between farms in the amount of their growers, maintain good relationships with capital, in other resources, and especially in the them, and have prestige in the industry, they may managerial capabilities of the grower. There can get some of the best growers, with what a grower be no best plan covering labor, housing, and may consider a less satisfactory contract. equipment for all farms. In general, the serviceman provides the per- When considering any plan, it is necessary to sonal contact between the company and the know the least cost of doing a particular job. The grower and in so doing gives a measure of pro- cost of labor on a particular farm and the avail- tection to the financial risk the company has in ability of money are extremely important. If the contract. He should provide the grower with labor is excessive on the enterprise, it is doubtful detailed information on approved practices of whether much capital outlay in labor-saving management and disease prevention and control. equipment can be justified. On the other hand, He should be specific and clear in his instruc- managerial problems can often be minimized by tions. He should give priority to grower com- reducing drudgery. munications, listen to their complaints, exchange ideas with them, and weigh their suggestions. Stress Factors When justified, the growers should be com- mended. Probably nothing is more important in Stresses cause physiological and biochemical re- obtaining good results than to have good rela- actions, which often depress growth rate or feed tionships between the serviceman and the grower. conversion. Combined or severe stresses may re- A management program must be simple, definite, sult in culls or deaths. Most stresses can be and consistent. 26 AGRICULTURE HANDBOOK 3 2 0, U.S. DEFT. OF AGRICULTURE The principal responsibility of the serviceman birds are to be handled, clean coveralls should is usually to visit the broiler growers. He gener- be worn. The poultryman should himself not be ally visits each grower once a week. Fewer a visitor to other flocks. (Servicemen should routine calls are made on the best growers, and start out with clean outer clothes each morning. he makes special visits when called. The broil- They should first visit flocks under 4 weeks of ers and the broiler house are checked and orders age with no apparent disease.) for feed taken. When the broilers are about (4) When birds are sold, remove the entire ready, their marketing is discussed. group from the farm. Birds of more than one If a serviceman does not have enough growers age should not be on the same farm at the same to occupy all his time, and sometimes when he time. No stray or yard bird should be on the does have, he often is called on to assist the premises. grower in vaccinating his chickens, to deliver (5) Normally the brooder house should be chicks and feed, to help load and haul broilers to thoroughly cleaned and disinfected between market, or to assist with office records. broods. It should remain empty and clean for at Most servicemen are paid a straight salary. As least a week. The brooder house should be well an additional incentive, a bonus system may be ventilated. It is desirable that it be insulated desirable. For example, a monthly check could be and, when economically feasible, have a concrete given to the serviceman of the group of growers floor. having the lowest cost of production. Alterna- (6) Houses and equipment should be thor- tively, a serviceman could be given increased re- oughly cleaned. Blow out or brush down the muneration when his growers exceed an agreed dust, spray the house, and disinfect it at 300 average point spread or "production efficiency" pounds' pressure. Einse equipment with clean index. water after disinfection. When practical to do so, expose equipment to the sun. After the equipment is returned to the house and clean General Sanitation litter added, lock all doors. Place a pan of dis- infectant at each door to be used by the attend- Security Management ant. Anyone who must enter should be required Security management is a method of disease to dip his shoes in the pan. control. The objective of a preventive program is (7) The litter should be free from mold, have to stop the mechanical spread of disease organ- a minimum of fine material, and be kept dry but isms. Most diseases cannot occur without such not dusty. disease-producing organisms as bacteria, viruses, (8) The feed should not be delivered mto the and parasites. Their spread between and within broiler house. The feed man should never have farms must be prevented. A security manage- to enter the house. ment program is necessary because disease agents (9) In a disease outbreak, obtain a prompt, can enter a flock from so many sources. Disease- accurate diagnosis from a professional source, producing organisms can survive away from the and start the proper treatment at once. bird for at least a few hours, possibly for days or (10) Have and use a properly constructed, weeks. conveniently located disposal pit or incinerator (1) Sanitation should start with clean eggs. of adequate size. Do not store clean eggs in dirty flats nor in used If properly followed, the security management nondisinfected cases. Chicks should be delivered program should considerably reduce disease from a clean hatchery, which is free of puUorum losses as well as reduce the drug bill. and fowl typhoid, by attendants wearing clean outer clothing and plastic boots. Do not ship Disinfection chicks by common carrier, such as train or bus. Use new or clean disinfected boxes to transport The producer should know what proper clean- them. ing is, why it is necessary, and how to do it. (2) Isolate chicks from older birds and visi- Most disease germs can be killed only by dis- tors, especially during the first 4 weeks. A sep- infection after thorough cleaning. The virus arate caretaker is desirable. Keep houses locked diseases are best controlled by strict cleanliness. at all times, even when the caretaker is inside. Effective cleaning begins with the removal of Exclude children, dogs, cats, and wild birds from litter and manure. The cleaning process includes poultry houses and follow a fly-control program. scrubbing with brushes until surfaces are visibly (3) Do not allow visitors in the same room clean, using a good detergent, flushing with clean with the birds. If observers are necessary, they water, and then applying an approved disin- should wear clean rubber boots, which have been fectant. One advantage of a cement floor is that disinfected with quaternary ammonium com- lye (caustic soda) can be used effectively. Since pound, when entering and leaving the premises. it corrodes metals, lye cannot be used as a Plastic boots in addition are desirable. If the general cleaner. A 2-percent lye solution should COMMERCIAL BROILER PRODUCTION 27 be used only Jwhen the temperature is above manure) in the disinfecting solution or on the 32° F. Because it irritates the skin, one needs surfaces to be disinfected may prevent the solu- to be cautious in it^ use. Lye can be used on tion from destroying disease organisms so that a dirt floor after it has been swept clean. no disinfection results. Quaternary ammonium compounds should be used in concentrations of 200 p.p.m. (1:5,000) Parasite Contrai and applied only to properly cleaned surfaces. After the house has been disinfected, malathion Hard waters slow their effectiveness. These can be used to control lice, mites, flies, and other compounds can be used for flushing floors and external parasites (see p. 56). walls and for disinfecting equipment. They are To control tapeworms, attack them at the effective against most disease-producing bacteria developing stage in the intermediate host. This and viruses. ik^, ; is best done by removing manure or litter, which The cresylic compounds are good disinfectants serves as a breeding place for beetles, ants, flies, for general use. If a preparation has a phenol earthworms, slugs, or snails—the intermediate coefficient of 5, it is five times more germicidal hosts of the tapeworms. When a tapeworm than phenol. It would be used in a 1-percent problem exists, the change of litter after each concentration, because the recommended dilution brood is usually essential. of phenol is 5 percent. The cresylic compounds The large intestinal roundworm, Ascaridia can be used for disinfections for nearly all gallic has no intermediate hosts. The eggs are bacterial and virus diseases. hard to kill. Preventive measures include gen- The presence of organic matter (dirt and eral sanitation. CHICKEN-MEAT PRODUCTION Cornish Game Hen giblets 5.5, and viscera 11 to 12. The total edible meat will be about 46 percent with males Cornish game hens, otherwise known as Eock and 47.5 with females of eviscerated weight. Cornish game hens, or baby broilers, are yomig immature chickens usually produced in about The killing and processing methods are 5 to 7 weeks. They range from li^ pounds to 2 similar to those for heavier chickens. A semi- pounds live weight when marketed. They weigh scald at 126° to 129° F. is usual. The birds are about 16 to 28 ounces oven-ready. Although then iced if to be sold fresh. Because of the their production is a specialized phase of the variable demand for this specialty product, poultry industry, it is similar to regular broiler quick freezing is customary, using transparent production in many ways. With few exceptions, plastic bags. It must be kept in mind that owing the usual methods of brooding and management to the weight at which these baby broilers are are followed. Only one-half square foot of sold, the cost per pound is much higher for floor space is provided per bird. Most of the the baby chick and for processing. Overhead is baby broilers are raised under contracts similar less because more batches can be raised per year. to those used for heavier broilers. The ration used is high in protein (24-25 Broilers and Small Roasters percent) and in energy (1,450 to 1,500 metaboliz- able calories). A high calorie broiler starter The average housewife prefers a dressed or ration should serve the purpose. It should give cut-up broiler or fryer that weighs 2 to 21/2 the desired weight and feed conversion of 2. The pounds, rather than a heavier one. Some of vaccination and disease-prevention program will the eastern broiler areas market a bird that has depend on local conditions and needs. a live weight of 4 pounds at between 9 and 10 Most processors want birds to average 11/2 weeks of age. If carried to 11 weeks, the males pounds live weight and 16 to 17 ounces when will weigh 5 pounds and the females about 4 ready for the oven. Other processors pay a pounds. The feed conversion is about one-fourth bonus for birds weighing 2 pounds and want pound better for a 3^2- than for a 4i/^-pound an eviscerated weight up to 24 ounces. The age broiler. The extra feed cost to 11 weeks is offset, for marketing cockerels is 4I/2 to 5 weeks. The at least in part, by the lower cost per pound for last of the pullets go at 6 weeks. Overweight the chick and for brooding. As one less lot can birds are grown out as broilers. The dressing be raised per year with the larger broiler, the percent (New York dressed) will be about 88 overhead cost is greater for it. for 2-pound live-weight Cornish hens. The With large broilers or small roasters, in addi- eviscerated weight will be about 68 percent of tion to the general problem of consumer demand, the live weight. As a percentage of live w^eight the increase in breast blisters (p. 28) and in the following can be expected: Breast meat mortality has to be considered. The greater 14 or 15, head 2 to 3.5, feet and shanks 4 to 4.5, mortality can be minimized by good manage- 28 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE ment practices. For information on feather the heavier birds. The cost of producing male picking and cannibalism, see page 56. broilers is less than for female broilers, capons, The heavy broiler is ideal for roasting. Roast and roasters, including those few produced by chicken is tender, tasty, and an ideal size for feeding dienestrol diacetate. the small family. It would give a greater return If capons are kept beyond 6 months, their rate to the producer if grown in quantity for a pre- of growth is superior to non treated males of the arranged market. same age, because they then put on weight much more readily than do roasters. As birds ^et Large Roasters and Capons older, their feed efficiency is poorer and mortality can be higher. This must be considered in figur- Large roasters and capons may be raised either ing cost of production. As caponizing males sets in confinement or on range. The tendency is to back their growth rate slightly, there is no great ^ raise them in confinement; pole-type houses are difference in the comparative growth rates of extensively used. Provide one-half square foot of capons and roasters to 6 months of age. Roasters space per bird until birds are 6 weeks old, 1 fed with dienestrol diacetate are usually mar- square foot to 10 weeks, 2 square feet to 16 weeks, keted when 14 weeks of age. Time of marketing and 3 square feet to market. Roasters and capons will be conditioned by price and consumer pref- are brooded, fed, and managed as broilers to 6 erence for roasters and capons. weeks of age. A capon is a castrated male chicken. After this surgical operation, the bird fattens more Breast Blisters (Sternal Bursitis) readily and produces more tender meat. Capons With roasters and capons, special attention sell for a higher price per pound than broilers needs to be paid to the prevention of breast blis- or roasters, because they require more labor and ters. Many carcasses are downgraded because of cost more to produce. They do not use feed as them. Some strains of birds seem more suscep- efficiently as lightweight birds. tible to this condition, possibly because of the Most poultrymen caponize cockerels that are breast angle or the feather coverage of the breast. 3 to 5 weeks old. The operation is of little value For information on a causative agent, see page after chickens are 2 months old. After the oper- 54. ation, put capons in clean quarters, separated Breast blisters occur more in males than in fe- from other chickens for 2 or 3 days. Capons do males and more in large than in small birds. not need special care after they recover from the Rate of growth seems to be involved. The most initial shock of the operation. For directions on important preventive measure is to have ample how to caponize, see the U.S. Department of floor space and deep, dry, clean litter. Condi- Agriculture Leañet 490, Caponizing Chickens, or tions that seem to irritate the keel bone and con- consult your county agent or a poultry specialist. tribute to the trouble are wet or caked litter and A compound, dienestrol diacetate, sometimes is roosting places with sharp edges, such as water- added to special feeds to produce a feminizing ers or feeders. effect on male chickens. This may result in fat- tening and tenderizing of rapidly growing birds. If you use this compound, follow the directions Marketing of the manufacturer. In general, roasters and capons are marketed Give roasters and capons the kind and amount in a similar way to broilers. As they are spe- of feed recommended for broilers during the first cialty products, like baby broilers, care must be 6 weeks. After changing to finishing mash, sup- taken to have an assured market. Losses can ply cracked corn to roasters and capons in the mount rapidly with a glutted market. Birds afternoon. Gradually increase the grain until treated with dienestrol diacetate and similar ma- birds are getting equal amounts of corn, mash, terials are usually sent to market live weight at 5 and pellets at 12 weeks of age. For roasters, in- to 6 pounds. Their market quality is usually su- crease the corn in the diet to 50 percent after the perior to that of untreated males of the same age, 15th week. Continue to supply grit as long as but is not equal to that of capons. The principal birds are fed whole grain. demand for capons is for large birds, 5 to 9 The fixed or overhead costs of producing roast- pounds, ready-to-cook weight. Roasters usually ers and capons are higher than for broilers, as average 31/2 to 6 pounds. The superior market more lots of broilers can be produced within a quality of capons warrants a higher price for year. The chick cost per pound will be less for them. FEEDS AND FEEDING METHODS Most broiler feeds are produced by a feed- an integrated operation, or a large independent manufacturing company, the feed-mixing unit of producer. The processed feeds are usually mixed COMMERCIAL BROILER PRODUCTION 29 in a centrally located mill and are delivered in 100 pounds to $4.75, the feed cost per pound goes bulk by truck to the broiler farms. It is not gen- down to 10.45 cents. erally economical for the individual grower with Note that at 2.4 pounds' feed conversion, the 10,000 to 50,000 broilers to do his own mixing on the farm.^ 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 Importance of a Good Broiler Ration pound. As is to be expected, the improvement in feed conversion is of increasing importance as Any poultry meat-production enterprise must use a feeding program that will give economical feed prices increase. A feed costing $4.50 would results if the operation is to survive. Usually have to have a feed conversion of 2.2 to give about the same feed cost per pound (9.9 cents) the best broiler feeding program gives the high- as a $4 per hundredweight feed giving a 2.5 est net return. With it, the broilers grow fast, pounds' feed conversion (10 cents) (see table 2). use their feed efficiently, have the desired finish However, higher cost feeds should give a greater and a high livability, and the feed cost per pound average body weight as well as improved feed is low. The finish may include plumpness, conversion at market age. bright-yellow pigmentation, and good feathering. It is not always possible to get more money per Feed cost is approximately 71 percent of the pound for exceptional quality in broilers. Yet total cost of producing broilers without contract a reduction in cost that gives poor broiler quality payrmnts. The cost of producing a pound of usually is not justified. As feed costs constitute broiler can be roughly calculated by multiplying about 62 percent of the total cost of producing the feed cost per pound in table 2 by factor 1.41. broilers, including contract payments, it is im- As an example, if the feed cost per pound is 8.4 portant to know what constitutes a good eco- cents, the total cost is 11.84 cents. If contract nomical ration. payments are made, the factor becomes 1.60 (feed cost estimated at 62.4 percent of total cost includ- ing contract payments). The total cost, includ- Factors To Consider in a Broiler Ration ing contract payments, becomes 13.6 cents per pound. Rapid growth in broilers is important, because Point spread usually is a more satisfactory cri- with increased age and weight more feed is re- terion of the worth of a feed than feed cost per quired to produce a pound of meat. By market- pound. The reason is that it takes rate of growth ing as soon as the desired weight is reached, feed into consideration. Point spread is the weight in and labor are saved and mortality risk is re- duced. However, when the processor will accept pounds times 100 minus the feed conversion times 100. For example, if the average weight is 3.33 larger broilers, when prices are good, and when pounds, the weight factor is 333. If the feed con- feed is cheap, larger birds may be more profit- version is 2.40, the feed conversion factor is 240 able because there are more pounds over which to and the point spread is 333 minus 240, or 93. Its spread the chick and the overhead costs. usefulness is limited because it becomes relatively Efficient feed conversion is an important con- greater as the broiler gets older. sideration. It may be expressed as the pounds of Income over feed cost per broiler is affected feed required to produce a pound of live broiler by quality of bird, growth, and feed conversion. or the pounds of live broiler per 100 pounds of The income is obtained by multiplying the feed (see table 1). If a broiler consumes 8 weight, 3.33 pounds, by the selling price. If it pounds of feed and weighs 3.33 pounds when is assumed that the average weight is 3.33 pounds marketed, the feed conversion is 2.4 (8-^-3.33), and the feed cost is $4.50 per hundred pounds, and the pounds of meat per 100 pounds of feed the feed cost per broiler is obtained by multiply- are 41.67 (table 1). With a feed conversion of 2.4 ing the weight, 3.33, by the feed conversion by pounds, assuming a feed cost of $4.50 per hun- the assumed feed cost of $4.50. The difference dredweight, the feed cost per pound of broiler is the income over feed cost. For example, at 13 will be 10.8 cents (table 2). If the feed conver- cents per pound, the 3.33-pound broiler gives an sion goes up to 2.5, the feed cost per pound goes income of 43.29 cents (3.33X13). If there is a up 0.45 cent to 11.25 cents, as shown in table 50-point spread, the feed conversion is 2.83, and 2. On the other hand, if the feed conversion goes 3.33 times 2.83 equals 9.42 pounds of feed per down to 2.2 and the price goes up 25 cents per broiler. At $4.50 per hundredweight, the feed cost per bird is 42.39 cents (9.42X4.50). The in- iFor more detailed information, refer to the publica- come over feed cost per broiler is 0.90 cent tion Drugs; Current Good Manufacturing Practice in Manufacture, Processing, Packing, or Holding, obtain- (43.29—42.39). As would be expected, the in- able from the Office of Public Information, Food and come increases with the selling price—3.33 cents Drug Administration, 200 C St. SW., Washington, D.C. per bird for each cent increase in selling price. 20204. Without contract payments, feed approximates 30 AGRICULTURE HANDBOOK 3 20, U.S. DEFT. OF AGRICULTURE TABLE 1.—Efect of feed conversion on income

Added weight Value of extra broiler weight per 100 pounds of feed Feed conversion Weight of at indicated live-weight selling price per pound (pounds of feed broiler per of broiler per per pound of 100 pounds 100 pounds live broiler) of feed of feed $0.16 $0.15 }.14 $0.13 3.12 ).ll $0.10

Pounds Pounds Cents Cents Cents Cents Cents Cents Cents 2.8- 35.71 13.30 37.04 1.33 21.28 19.95 18.62 17.29 15.96 14.63 2.1- 15.62 14.20 38.46 1.42 22.72 21.30 19.88 18.46 17.04 2.6- 16.94 15.40 40.00 1.54 24.64 23.10 21.56 20.02 18.48 2.5_ 23.38 20.04 18.37 16.70 2.4_ 41.67 1.67 26.72 25.05 21.71 28.96 27.15 25.34 23.53 21.72 19.91 18.10 2.3_ 43.48 1.81 19.70^^ 1.97 31.52 29.55 27.58 25.61 23.64 21.67 2.2- 45.45 21.70 47.62 2.17 34.72 32.55 30.38 28.21 26.04 23.87 2.1- 33.32 30.94 28.56 26.18 23.80 2.0- 50.00 2.38 38.08 35.70

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

Feed conversion Cost of feed per pound of live broiler (c) at indicated cost of feed per 100 pounds (&) (pounds of feed per pound of live broiler) $4.25 $4.00 $3.75 $3.50 $3.25 $3.00 (a) $5.50 $5.25 $5.00 $4.75 $4.50

Cents Cents Cents Cents Cents Gents Gents Gents Cents Cents Cents 9.10 8.40 14.70 14.00 13.30 12.60 11.90 11.20 10.50 9.80 2.8- 15.40 8.78 8.10 14.18 13.50 12.83 12.15 11.48 10.80 10.13 9.45 2.7_ 14.85 9.10 8.45 7.80 14.30 13.65 13.00 12.35 11.70 11.05 10.40 a75 2.6_ 10.63 10.00 9.38 8.75 8.13 7.50 2.5_ 13.75 13.13 12.50 11.88 11.25 12.00 11.40 10.80 10.20 9.60 9.00 8.40 7.80 7.20 2.4_ 13.20 12.60 6.90 11.50 10.93 10.35 9.78 9.20 8.63 8.05 7.48 2.3- 12.65 12.08 7.15 6.60 11.55 11.00 10.45 9.90 9.35 8.80 8.25 7.70 2.2- 12.10 7.35 6.83 6.30 11.55 11.03 10.50 9.98 9.45 8.93 8.40 7.88 2.1_ 8.50 8.00 7.50 7.00 6.50 6.00 2.0- 11.00 10.50 10.00 9.50 9.00

Ma) X (&) = (^)- 71 percent of the total cost of the broiler. A fac- of feed equal in value to a pound of live broiler. tor of 1.41 is used to convert feed cost to total For example, if the price of feed is $4.67 per hun- cost without contract payments (see table 2). At dred pounds and the price of broilers is 14 cents, $4.50 per hundredweight and a feed conversion the ratio is 3 (14^4.67). If the price of feed is of 2.2, the feed cost per pound is 9.9 cents $5 per hundred pounds and the price of broilers (2.2X4.50). The total cost, without contract is 15 cents, the ratio is still 3. The ratio fluctu- payments, would be 13.95 cents per pound and the ates widely. It may be as favorable as 5 (aver- nonfeed costs (chicks, fuel, lights, litter, medi- age, 1955) or as unfavorable as 2.7 (December cine, and vaccination) would be 29 percent, or 1963). 4.05 cents (13.95—9.9) per pound. In table 1, the effect of feed conversion on in- With contract payments, the total cost per come can be observed. Of course, the higher the pound is approximately 1.6 (100-^-62.4) times the selling price, the greater the value of the extra feed cost per pound, and the nonfeed percent of weight. If feed conversion improves from 2.5 to the total cost is about 37.6. With a feed cost of 2.4, the added weight per 100 pounds of feed is 9.9 cents per pound, the total cost becomes 15.84 1.67 pounds. The value at 13 cents per poimd cents and the nonfeed costs 5.95 cents (37.6 per- is 21.71 cents. If the improvement in feed con- cent of 15.84) per pound. The importance of re- version is from 2.5 to 2.3, the added value, due to lating average body weight sold and feed conver- the 20 points, is 45.24 cents (21.71 + 23.53). The sion with the price paid for the feed is obvious. feed giving such an improvement in feed conver- To consider mortality as a factor, income over sion would be worth $9.05 (45.24X20; also, feed cost should be figured on the basis of the 4.33 + 4.72 in table 3) per ton more. Table 3 can number of birds sold. be used as a guide to the comparative value of The broiler-feed ratio is sometimes used as an feeds when their relative feed conversions are index of the broiler situation. It is the pounds known. COMMERCIAL BROILER PRODUCTION 31 irt^icoococoioeoco iCDOOOCOCDOiCOt- O ^* 1 (M (M* CO CÔ CÓ CÔ Th TjH ■H

ITHCOÄCDO'^CO'* ^. iprHOOCOOOOt-

^ 1

(M ^- |rH^t-OC0C0(Ml>: O CO CO cô Tfí Tjí Tjí id id Ö m-

IC0rHOC0

d o ¡COCÓThTjildldCDCD

per pound (not cumulative)i (d) |Ç0b-(NOrtHC005rtH ^. ICDíNCDOTííOSTJHTH rH O 1 có Ttí TjH id id id c¿ t^ CO improves at indicated live-weight selling price Increase in value of feed per ton as conversion ^ 1 C^ lO o CO 00 CO 05 CO S O ¡TtÍTíÍTííldldcDCDb-: È Q 1 I 71.43 83.33 74.07 76.92 80.00 86.96 90.91 95.24 Dol. 100.00

b-OOrHOCOCOOCOO •a rH ^- iq Tt^ p p p p p t> p

Cil>00 00 000505OOr-l 5^ 1 É ^ rH rH rH

•H 85.72 88.88 92.30 96.00 Dol. 100.00 104.35 109.02 120.00 •s. g 114.29 ''B g

!l OOiQOCOlOOOrHO CO ^OOíMOOCOOrHOOO rH Ö

IIo Pi p* ^ OQC0b-^(N*CDrHI>*CÓO g qOOOrHrH

1 g ^rHrHrHrHrHrHrHrH^ >ai

CO rH Dol. 114.29 118.51 123.07 128.00 133.33 139.14 145.46 152.38 g 160.00

ta sion Feed of live of feed conver- (pounds broiler) 00l>ÇDlOTtHC0C

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 tempera- feeds, the feed formulator should evaluate his ture used and the length of time a meal is ex- own 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. Incom- plete 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 pro- average 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 in- should 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 con- of 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 metabo- certam 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 addi- Phenyialanine 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 At one time rickets was a common disease in emaciation. Vitamins are nutritional factors broilers. It is caused by the nutritional defi- considered necessary for growth and mainten- ciency due to insufficient vitamin D, calcium, or ance of health. For the symj)toms and lesions phosphorus, although rarely is a deficiency of of important nutritional deficiency diseases in the minerals acute enough to bring on the broilers, see page 51. symptoms. The chicks with rickets sit down The requirements for the needed vitamins are on their hocks or walk with a stiff-legged gait. sometimes met by the natural feedstuffs. In They are retarded in growth and appear un- some cases, the need for a vitamin requires the thrifty, or without vigor. The breastbone be- addition of a concentrated source or vitamin comes crooked, the rib ends are beaded, and the supplement to the ration, because the natural back and legs are soft and rubbery. content is too low or there ha^ been or might be The vitamin D3 concentrate is usually pre- loss due to oxidation. mixed with yellow cornmeal before it is in- Most practical broiler formulas do not benefit corporated in the rest of the ration. by adding folacin, biotin, ascorbic acid, vitamin Be (pyridoxine), or thiamine. Vitamin E Vitamin E occurs widely in grains, grain by- Vitamin A products, and alfalfa meal. It is involved m Vitamin A is required for the normal function- most of the tissue functions of the chick's body ing of the epithelial tissues of the membranes and in the prevention especially of encephal- of all the principal functional tracts of the omalacia (crazy chick disease), muscular dys- body. Normal functions, such as growth, develop- trophy, and exudative diathesis. Most rations ment of bones, and resistance to infectious dis- have enough vitamin E from natural ingredients, ease, are totally or partially dependent on this but the content can be materially reduced by vitamin. oxidative destruction during storage, especially The requirements for vitamin A are expressed after grinding, and from pelleting. in U.S.P. units of vitamin A activity per pound Vitamin E is not a single chemical entity. of feed. Normally 0.6 /xg. of beta-carotene ap- It consists of various tocopherols, which vary pears to be equivalent to 1 U.S.P. unit of vita- widely in biological activity. The most active min A. The principal sources of the carotene, is alpha-tocopherol. One international unit or provitamin A, in broiler rations are alfalfa (LU.) is the biological potency of 1 mg. of meal, yellow corn, and corn gluten meal. To dl-alpha-tocopheryl acetate. Another form, also meet the full requirements, a vitamin A concen- available for feed mixing, is a d-alpha-tocopheryl trate is often added and especially to rations in acetate. One mg. of it is equivalent to 1.36 which milo or wheat replaces yellow corn and LU. of vitamin E. in high fat diets. There seem to be important interrelationships When losses may be due to the action of between vitamin E, antioxidants, sulfur amino certain minerals, heat during storage, or pellet- acids, and selenium in the prevention of vitamin ing, a stabilized product is used or a margin E deficiency diseases (see p. 51). As a margin of safety allowed. It is not unusual to include of safety, 5,000 LU. of vitamin E per ton are enough vitamin A in the ration to build up and sometimes added to broiler feeds as a supple- maintain a reserve of vitamin A in the liver. To ment. do this, more vitamin A may be advisable with certain diseases, such as coccidiosis and chronic Vitamin K respiratory disease (CRD), and when birds go off feed. Any deficiency retards growth. An Chicks may be hatched with a very low reserve extreme deficiency affects the health of the bird. of vitamin K. If fed a deficient ration, they may For symptoms, see page 51. 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 Vitamin D of the blood. Mortality and morbidity of chicks The requirements for vitamin D are expressed from cecal coccidiosis have been decreased by in international chick units per pound of feed. adding a source of vitamin K to the feed. There Chicks effectively use vitamin D3 from irradiated is a direct antagonism between sulfa drugs, such animal sterol and fish oils, but do not use vitamin as sulfaquinoxaline, and vitamin K. Vitamin D2 from irradiated ergosterol as efficiently as K has been beneficial in treating some cases of do mammals. When the minerals in the ration hemorrhagic disease. For information on hemor- are adequate and balanced, vitamin D is no rhagic anemia syndrome, see page 52. different in efficiency from fish oils and from Vitamin Ki occurs naturally in alfalfa meal, irradiated animal sterols. dried cereal grasses, soybean meal, and soy oil. COMMERCIAL BROILER PRODUCTION 35 Vitamin K2 has been isolated from putrefied acid deficiency. In pantothenic acid deficiency fishmeal. Vitamin K3, the synthetic vitamin K, the first symptoms are around the mouth and is menadione. Menadione sodium bisulfite, which eyes, and rarely are the feet severely affected. is extensively used in feeds and water, is an additional compound of menadione. It contains Folacin 33 percent of menadione. Added vitamin K sources are used only to meet stress conditions, Folacin, or folie acid, is essential for the primarily due to drugs and diseases. normal functioning of virtually all body cells. In broilers a deficiency results in retarded growth, poor feathering, perosis, anemia, lowered Riboflavin resistance to round worms, and an increased Curled-toe paralysis is the characteristic methionine requirement. Most rations are ade- symptom of riboflavin deficiency. Other symp- quate in folacin. Some questionable rations will toms are retarded growth and diarrhea. In benefit by the addition of 0.25 mg. per pound nutritional paralysis, the chicks suddenly start, of the synthetic compound. walking on their hocks with the toes curled inward. As they are otherwise healthy, they Vitamin BQ respond rapidly to added riboflavin in the ration. Good sources are a synthetic compound, fermen- Chicks on a vitamin Be-deficient ration grow tation byproducts, dried milk products, and very slowly and often show considerable excita- dried brewer's yeast. bility and jerky convulsive movements. They run about aimlessly, fall on their sides, and paddle their feet in the air. Complete exhaustion Pantothenic Acid follows and is often fatal. The deficiency is A deficiency in pantothenic acid results in rarely seen in the field. dermatitis of the feet, and crusty scabs appear around the mouth and vent. The eyelids may Vitamin B12 stick together and growth and feather develop- ment are poor. Molasses and fermentation by- Vitamin B12 is essential for chick growth. products are good sources of this vitamin. The There are no specific symptoms of deficiency. synthetic compound commonly used as a source Vitamin B12 is associated with animal protein is d-calcium pantothenate. Less costly to manu- sources. Most rations in which the principal facture than this compound is dl-calcium source of protein is of vegetable origin require pantothenate, but 50 percent of it is inactive. vitamin B12 supplementation. Some sources of Use should be based on d-pantothenate activity. B12 and the approximate value in milligrams per pound in natural feedstuffs are as follows: Poultry byproduct meal 0.16, feathermeal 0.44, Niacin fish solubles 0.20, fishmeal 0.1, and meat scraps In niacin deficiency, the tongue and mouth 0.05. Generally a commercial vitamin B12 cavity become inflamed. Other symptoms in- supplement is used. clude retarded growth, loss of appetite, poor feathering, and scaly dermatitis of the feet and Thiam^ine skin. The principal common sources of niacin are the synthetic compound, grains, and the Polyneuritis results if baby chicks are fed a fermentation, ^rain, and fish byproducts. The thiamine-low ration for about 10 days. The niacin in corn is not available to poultry. head of an affected chick is drawn over the back. Other symptoms of deficiency are general weak- ness, loss of appetite, emaciation, and convul- Choline sions. Thiamine deficiency is uncommon. Choline is a factor in the prevention of perosis, or slipped tendons. When the ration is Unidentified Growth Factors deficient in choline, growth is retarded. The principal source of supplementary choline is The unidentified growth factors (UGF) are choline chloride. Each pound or 25 percent probably synthesized by the intestinal micro- choline chloride supplies 98,518 mg. of choline. flora. At least three distinct organic factors and two or more trace minerals are apparently Biotin involved in the UGF. Organic growth factors have been isolated from fish solubles and corn A dermatitis results from biotin deficiency. distillers' dried solubles. Other good sources of The feet become rough and hemorrhagic cracks UGF, trace minerals, or both are alfalfa meal, appear. Some scabs appear about the beak. dried whey, penicillin mycelium residues, strep- Symptoms are similar to those for pantothenic tomyces meal, butyl fermentation solubles, dried 36 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE and condensed fermented corn extractives, much phosphorus in the diet. The rate of brewer's dried yeast, fishmeal, liver preparations, growth may be depressed. On the other hand, other animal byproducts, feathermeal, and dis- the effect of excess fluorine is greater when phos- tillers' grains and solubles. Soybean meal appar- phorus is deficient in the diet. ently has both water- and fat-soluble factors, Most practical broiler diets will contain ap- which stimulate growth. Liver and com dis- proximately 0.65 percent total and 0.4 percent tillers' solubles contain certain natural chelates, available phosphorus. Only 30 percent of the which aid in the utilization of zinc. Feather- phosphorus from plant sources is available. Con- meal contains an inorganic unidentified growth siderable differences occur in the availability of factor. phosphorus from various inorganic sources. Care should be taken in the use of phosphate supple- Minerals ments of low phosphorus availability and which The quantity and quality of minerals in the contain high levels of fluorine, especially in high- f^ ration are important. Perhaps more important energy rations containing added fat. The is the relationship of one mineral to another or broiler starter and finisher diets should have to some other nutrient. Certain minerals are about 0.4 percent of nonphytin phosphorus from needed for bone structure and tissues, whereas good animal or inorganic phosphorus sources, others are essential for the production of en- such as feed-grade dicalcium phosphate,defluor- zymes and hormones. When present in inade- inated phosphate, or low-fluorine rock phosphate. quate amounts, nutritional deficiencies may result. If in excess, growth may be depressed, Sodium the effectiveness of antibiotics may be adversely Sodium is usually added to broiler rations in affected, and vitamins may be destroyed. the form of salt (sodium chloride). In certain Consideration must be given to the content areas the water contains relatively large amounts in the diet of such minerals as calcium, phos- of salt. Normally a broiler feed has about 0.25 phorus, iodine, sodium, manganese, magnesium, percent of salt added. potassium, sulfur, and the trace minerals, which include copper, iron, zinc, molybdenum, and Manganese selenium. Special consideration is given, in formulating the broiler ration, to calcium, phos- A lack of this mineral is one of the causes of phorus, salt, manganese, zinc, copper, iron, and perosis, or slipped tendons, in broilers. It is iodine. Interrelationships between calcium and present to a certain extent in nearly all ingredi- manganese, copper and zinc, and zinc and iron ents of broiler rations. The requirement for affect requirements. The requirements for min- manganese is increased by an excess of calcium erals are given on pages 32-33. and phosphorus in combination. To insure an adequate supply of manganese, it is usual to add feeding-grade manganese sulfate to supply Calcium 22.7 mg. of manganese per pound of ration. Except possibly for the first week or two, the calcium content of the ration should not exceed Iodine 1 percent and the optimum results are probably As the broiler rations should contain 0.5 mg. obtained at about 0.8 percent. To potentiate the per pound of iodine, iodized salt is usually broad-spectrum antibiotics, such as chlortetra- specified. An iodine deficiency leads to an en- cycline and oxytetracycline, the calcium content largement of the thyroid gland. Iodine is not of the feed may be lowered to about 0.4 percent. usually deficient in broiler feeds. Such a feed is usually given only for 3 days and not during the first 3 weeks. If given too long Zinc or when chicks are too young, rickets (leg weak- ness) may result. (See also p. 51.) A deficiency of zinc in the ration may cause The principal source of calcium in broiler depressed grow^th, unsteady gait, shortening and feed is high-calcium ground limestone. Oyster- thickening of long bones, frizzled feathers, and shell flour, most sources of phosphorus, and parakeratosis of the skin. A high calcium level most animal protein feeds also supply liberal increases the severity of zinc deficiency symp- amounts of calcium for the ration. toms. Natural chelates in certain ingredients aid in the utilization of zinc. Zinc may be of Phosphorus importance because it can activate certain enzyme systems or aid in the absorption of other trace The amount and the source of phosphorus minerals. Common sources of added zinc are in the diet are important as well as the relation zinc carbonate, zinc oxide, and zinc chloride. of the calcium to phosphorus. The vitamin D It is usual to add 50 ç.p.m. or 22.7 mg. of zinc requirement may be adversely affected by too per pound to broiler rations. COMMERCIAL BROILER PRODUCTION 37 Iron and Copper probably added amounts are not needed in prac- Although the requirements listed by the tical formulation. As a margin of safety, 0.0454 National Eesearch Council (p. 32) may be too mg. of each per pound may be added. low, practical broiler rations normally contain adequate amounts of iron and copper without Magnesium the use of additives. Zinc causes a strong an- tagonism to iron and copper, especially copper. Magnesium is an essential element and must A deficiency of iron especially can cause anemia, be provided from a dietary source. It is required rough feathering, and lighter colored feathers as an activator for many enzymes. Deficiency in red varieties. A deficiency of copper may symptoms are poor growth, tremors, gasping, result in poor growth and a high mortality, and convulsions. The requirement is less in the largely due to spontaneous aortic rupture. As a margin of safety, 1.816 mg. of copper per presence of antibiotics and is greater with con- pound may be included in the finisher ration. tamination, as with chicken feces, or with in- creased calcium or phosphorus in the ration. Molybdenum and Selenium Magnesium does not need to be added to a Chicks require molybdenum and selenium, but practical broiler ration.

FEED AND WATER CONSUMPTION Table 4 gives the approximate feed and water TABLE 4 Approximate feed and water consump- consumption per 1,000 mixed-sex commercial tion per IfiOO iroilers ^ broilers. The feed consumption will vary with the strain, the texture, energy, and protein con- Feed pei* Feed per Accumu- V^eek lative Water tent of the ration, environment (such as tempera- day week per day ture) , management, and disease problems. Water feed intake varies with the temperature, diet, and feed intake. When the temperature is about Pounds Pounds Pounds Gallons 1 33 231 231 7 70° F., the water consumption varies from 1% 2 60 420 651 13 to 2 pounds of water for every pound of feed 3 90 630 1,281 19 consumed. Nearly 21/^ times more water is con- 4 117 819 2,100 25 5 145 1,015 3,115 31 sumed per pound of feed at 90° than at 60°. 6 200 1,400 4,515 4ß Extra salt in the diet will increase the water 7 262 1,834 6,349 55 8 291 2,037 8,386 61 consumption. Adequate quantities of water 9 301 2,107 10,493 63 should be available for broilers to fulfill their individual needs. i Assume a room temperature of 70° F.

RATION INGREDIENTS Grains Com is a source of the carotenoid pigments, which provide provitamin A and pigmentation Grains are included in the ration primarily as factors. In rations containing 2.5 percent or a source of energy and secondly for their protein more of alfalfa meal or 2.5 percent or more of and amino acid content. The low-energy grains, corn gluten meal, milo can replace half of the barley and oats, contribute more of the B-com- yellow com when the price is right. In general, plex vitamins and minerals than the high- cereals are deficient in riboflavm, vitamin B12, energy grains. All grains are thought to carry choline, and phosphorus. Molasses is sometimes some unidentified growth factors. For broilers, used at low levels to replace com or milo. 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 MiUfeeds wheat, 87 for barley, and 84 for oats. If used, wheat should be coarsely ground. The feeding Wheat bran improves the palatability of a value of some barleys has been improved by soak- feed, but it has a low content of digestible ing them in water, adding certain enzyme prepa- nutrients and is not used in high-energy rations. rations, or adding fat to the diet. Eeplacing corn Wheat middlings and shorts can be economical with oats usually results in slower growth and sources of energy. They are a better source poorer feed conversion. Oat groats, or dehuUed of the B-G complex factors than the cereal oats, compare favorably with corn or wheat. grains. 38 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE Fat Fishmeal The amount of fat added to a commercial Most starter rations, without other sources of broiler feed varies considerably. It may range animal protein or unidentified growth factoid from about 1 to 10 percent. The relative cost of the "fish" type, are improved by adding 2.5 and availability of fats of acceptable quality to 10 percent of high-quality fishmeal. It is are important considerations. In general, the probably not advantageous to exceed 7.5 percent amount to add is what is required to produce of fishmeal in the finisher rations. The level a pound of chicken at the least possible cost. to use will depend primarily on the kind and Most broiler rations will include 2 to 4 percent cost of the fishmeal in relation to other protein of added fat, which brings the total fat content sources. Fishmeal is a good source of the B-G to 6 to 8 percent. The use of levels of fat above complex vitamins. 2 to 3 percent in pelleted feeds must be justified entirely on the relative cost of energy. Pellet- Condensed Fish Solubles ing a low-fat ration improves both growth and Made from fish waste, condensed fish solubles feed conversion, but pelleting a high-fat ration are a source of the "fish" factor and of the B-G does not. Mash feeds may te improved in feed complex factors, especially vitamin B12. This efficiency and sometimes in growth by adding product is usually shipped m tank cars. 10 percent of fat. The principal reason for improved results from both pelleting and high fat levels is an increase in nutrient intake. Effi- Meat Scrap cient feed conversion depends to a considerable Meat scrap and meat and bone scrap are by- extent on the total energy content of the diet, products of the rendering industry. They aver- which is the sum of the energy derived from fat, age 50 percent in crude protein. The lower the carbohydrate, and protein. protein content, the higher the bone content. Fats may make mash feeds less dusty and en- The use of meat scrap in broiler rations will hance their texture and palatability. They may depend on its relative cost as compared to fish- also cause feed to "hold up" in bins and feeders meal, soybean meal, feathermeal, and poultry and may cause poor-quality pellets, which break byproduct meal. down to fines. Equipment has been developed for incorporating fats in mashes and pellets. Crabmeal Antioxidants are blended with fats to reduce the rancidity and the destruction of nutritive Commercial crabmeal has the following per- factors such as vitamins A and E. cent constituents : Protein 32, crude fat 1, crude For general calculations, 2,900 calories of pro- fiber 13, ash 42, calcium 16, phosphorus 1.6, and ductive energy and 3,500 calories of metaboliz- salt 3. Crabmeal can replace fishmeal and meat able energy are used for fats when exact values and bone scrap if adjustment is made for cal- are not known. cium, phosphorus, and riboflavin. Crabmeal has about the same content of unidentified growth factors as fishmeal. Fish Oil Feathermeal The addition of fish oil may improve growth The hydrolyzed feathermeals vary greatly in and feed efficiency. Care must be taken to avoid protein quality. Feathermeal has a relatively fishy flavor. The amount used will depend on poor quality of protein compared to fishmeal, the amount and kind of fishmeal in the ration. poultry byproduct meal, or soybean meal. It The maximum fish oil, without fishmeal in the contains about 80 percent of crude protein and ration, is 21^ percent. 800 calories of productive energy. It is relatively high in amino acids, glycine, cystine, and argin- ine, but low in methionine and lysine. It con- Animal Protein Products tains an unidentified inorganic growth factor. Its use is limited to 5 percent or less of the The animal protein products—fishmeal, meat poultr^^ ration. Results are not improved by scrap, and crabmeal—contain relatively high supplementing feathermeal with massive doses quantities of the essential amino acids, vitamin of amino acids or extra vitamins and minerals. Bi2, riboflavin, and choline. Combining several animal and vegetable protein sources is usually Poultry Byproduct Meal advantageous. Synthetic methionine and lysine are commercially available and their use is some- Poultry byproduct meal is usually guaranteed to times indicated. have 55 percent of crude protein and 12 percent COMMERCIAL BROILER PRODUCTION 39 of fat. It has a productive energy content of Fermentation Products about 900 calories per pound, about equal to fish- meal and higher than meat and bone scrap or soy- Various products, both primary and byproduct, bean meal. If correction is made for calcium and are excellent sources of the unidentified growth phosphorus, this product can substitute for all the factors. They are often high in vitamins and meat scrap and half the fishmeal, provided at may contam residual amounts of antibiotics. least 2.5 percent of fishmeal remains in the ra- tion. It is low in methionine, lysine, and cystine Alfalfa Meal and needs animal protein supplementation. Although alfalfa meal is included in the broiler Vegetable Protein Sources ration primarily for its provitamin A, beta- carotene activity, and its xanthophyll content, it Soybean Meal also contains substantial amounts of vitamins, in- cluding vitamins E and K. Most commercial The 50 percent dehulled and 44 percent solvent- alfalfa meals have an antioxidant, such as ethoxy- extracted soybean meals have largely replaced qum and fat added, are blended, stored under other types in this most widely used source of gas, and ground before use. With the advent of vegetable protein in broiler rations. Soybean high-energy rations, there has been less 17 per- meal, either 50 percent dehulled or 44 percent ex- cent protein meal used and a trend toward 20 tracted, and ground yellow corn are the principal percent meals in broiler feeds. When nonpig- ingredients in most least cost broiler rations. mented grains replace yellow corn, 2 percent of Soybean meals may be deficient in certain amino alfalfa meal is often included in the ration. acids, especially methionine, vitamin B12, and un- identified growth factors. Dried Whey Cottonseed Meal Some rations are improved by the addition of A commercial prepress solvent cottonseed meal the "whey" unidentified growth factor. Because will contain about 600 calories of productive en- of its laxative effect and sometimes its cost, the ergy per pound (air dry basis) if it contains 44 use of dried whey is generally restricted to a to 47 percent of protein and has a protein solu- maximum of 21/2 percent of the ration. bility of 74 percent or more. It can be of equiva- lent nutritive value to soybean meal if fed on an Antioxidants equal energy basis and is supplemented with ly- sine and if the soybean meal is supplemented with Antioxidants are used in broiler rations to pro- methionine. Fifty percent protein dehulled soy- tect against rancidity and the oxidative destruc- bean meal will have about 640 calories per pound. tion of vitamins A and E in storage, mixing, and Cottonseed meal will have a higher crude fiber pelleting and to increase the utilization of pro- content than soybean meal. It is best used as par- vitamin A from alfalfa meal. Butylated hy- tial replacement of other vegetable protein droxytoluene (BHT) and 1,2-dihydro 6-ethoxy- sources. 2,2,4-trimethylquinoline (Santoquin and Dethox- yquin) are common antioxidants for broiler Corn Gluten Meal feeds. They are used at a level of 0.0125 percent to prevent encephalomalacia and the destruction Corn gluten meal is used up to 5 percent of the of the fat-soluble vitamins A and E. They do not ration as a protein source to replace part of the improve pigmentation or the dietary utilization soybean meal, and it is used at about 2 percent of xanthophyll in broilers unless oxidizing agents, of the ration to improve pigmentation, especially such as lineoleic acid, are present. Antioxidants the finisher diet and when yellow cornmeal is re- do not appear to have a specific function in pre- placed by nonpigmented grains. It is low in ly- venting selenium and vitamin E-induced defi- sine, arginine, and tryptophan. ciencies.

Sources of Natural Vitamins and Coccidiostats Unidentified Growth Factors A coccidiostat is used in most broiler rations to Distillers^ Dried Solubles prevent coccidiosis. The suggested level is that recommended by the manufacturer. Care should Corn and milo distillers' dried solubles are used be taken to limit the percentage used to the re- primarily as a source of "fermentation" uniden- quirements of the situation and to be sure the tified growth factors at levels of 2.5 or 5.0 per- drug is removed from the ration at marketing cent, replacing soybean meal and ground corn. time according to regulations. When a coccidio- They are a good source of energy and the B-G stat is used, special consideration should be given complex vitamins. 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 Antibiotics commonly used in broiler rations broiler rations are as follows: and their principal functions are as follows: Function i Amprolium, Amprol 25 percent (l-(4-amino-2-n-propyl-5- Antibiotic pyrimidinylmethyl)-2-picolinium chloride hydrochloride) Aureomycin, aurofac Growth promotion ; aid in Arzene (arsenosobenzene) chlortetracycline _. prevention and control of Glycarbylamide, Glycamide (4,5-imidazole-dicarboxa- chronic respiratory dis- mide) . ^ ^ ^ ease (CRD) and synovitis. Nicarbazin, Nicarb (4,4'-dinitrocarbanilide-2-nydroxy-4, Bacitracin Growth promotion; aid in 6-dimethylpyrimidine ) prevention and control of Nitrofurazone, NFZ ( 5-nitro-2-furaldehyde semicarba- CRD and blue comb ; meet zone) /^ ... o stress conditions. Nitrofurazone and furazolidone, Bifuran (5-nitro-^- Bacitracin, manganese — Growth promotion. f uraldehyde semicarbazone and n-(5-nitro-2-furfuryli- dene ) -3-amino-2-oxazolidone ) Bacitracin méthylène Nitrophenide, Megasul (m,m-dinitrodiphenyldisulfide) disalicylate See Bacitracin. Polystat ( acetyl- ( para-nitrophenyl ) -sulfanilamide, di- Bacitracin, zinc Do. butyltin dilaurate, dinitrodiphenylsulfonylethylenedia- Erythromycin, .Gallimycin, mine, 3-nitro-4-hydroxyphenylarsonic acid) erythromycin thio- Sulfaquinoxaline, SQ (2-sulfanilamidoquinoxaline) cyanate Growth promotion; aid in Trithiadol (bithionol and methiotriazamine ) prevention and control of Unistat ( acetyl- ( para-nitrophenyl ) -sulfanilamide, 3,5- CRD. dinitrobenzamide, 3-nitro-4-hydroxyphenylarsonic acid) Oleandomycin Growth stimulation. Whitsyn (2,4-diamino-5-(para-chlorophenyl) 6-ethyl py- rimidine and 2-sulfanilamidoquinoxaline) Oxytetracycline, oxytetra- Zoalene, Zoamix (3,5-dinitro-o-toluamide) cycline hydrochloride, terramycin Growth promotion; aid in reduction of CRD mortal- Antibiotics ity; aid in prevention and control of synovitis. Most broiler rations contain antibiotics at the Penicillin, procaine relatively low levels of 4 to 10 grams per ton to penicillin ___ Growth promotion; aid in prevention and treatment stimulate growth. Some of those commonly used of CRD, blue comb, and are penicillin, bacitracin, zinc bacitracin, erythro- synovitis. mycin, chlortetracycline, and oxytetracycline. Penicillin (from procaine Improved results are sometimes obtained by com- penicillin), strepto- bining antibiotics or by changing antibiotics mycin Growth promotion; treat- ment of CRD and blue periodically. comb. Chicks in contaminated quarters may show de- iThe function of the antibiotic is dependent on the pressed growth from the fourth to the seventh level of the drug in the feed. For more detailed infor- day. This symptom was not observed when an mation, refer to Food and Drug Administration Anti- antibiotic was included in the diet. The feed is biotic Regulations, obtainable from the Office of Infor- apparently poorly utilized from the 4th to the mation, Food and Drug Administration, 200 C St. SW., 12th days by the chicks not getting the anti- Washington, D.C. 20204. biotic. Fecal excretion is greater when an anti- biotic is not given. Antibiotics seemingly improve Antibiotic Potentiation growth and feed utilization by affecting the micro-organisms, which reduce absorption of nu- When broad-spectrum antibiotics, such as trients. Eesults from antibiotics are highly vari- chlortetracycline and oxytetracycline, are used to able. Sometimes males respond when females do control diseases, it is economical and feasible to not. The age and extent to which different breeds potentiate them. and strains respond may vary with different anti- Calcium is the principal inhibitor of antibiotics biotics. Reasons for the complexity of antibiotic in poultry feeds. On the other hand, the calcium action are not know^n. salt, calcium sulfate, is less inhibitory and can be Levels of 100 grams per ton or more are used used to advantage. Sodium sulfate also can be in some prestarter rations to be fed for the first used as a substitute for calcium carbonate or di- 14 to 21 days. High levels of antibiotics are also calcium phosphate to increase concentration of used for disease control. the antibiotics in the blood. Due to its tendency The broad-spectrum antibiotics—chlortetracy- to increase water consumption when used in ex- cline and oxytetracycline—are often potentiated cessive amounts, it is advisable to restrict the per- when used to control certain diseases. The cent of sodium sulfate to 1.5 in potentiating for- amount and the sources of certain minerals in the mulas. When using formulas to potentiate anti- ration affect the concentration of the antibiotics biotics, the directions of the manufacturer of the in the blood of the bird. The manufacturer's antibiotic should be followed. If it is approved recommendations should be followed in the use for use, terephthalic acid (T.P.A.) will also en- of antibiotics. hance the therapeutic efficiency of Aureomycin. COMMERCIAL BROILER PRODUCTION 41 Arsenicals mented birds. The variation in skin color is due primarily to breed, method of scald, and the xan- Low levels of certain arsenicals have a growth thophylls in the feed ingredients of the rations. effect similar to that of antibiotics. Arsenicals Xanthophylls are a group of carotenoid pigments. and antibiotics usually give a greater growth re- Good pigmentation usually results when at least sponse when combined than if used separately. 6.4 mg. of xanthophyll from natural sources are For example, the addition of arsanilic acid or "3- present in each pound of feed. If low carotenoid nitro" to bacitracin méthylène disalicylate will ingredients, such as milo or white corn, are used give a better gain and feed conversion than the in a starter ration, good pigmentation can still be antibiotic alone. The pigmentation of the birds obtained by using about 8 mg. of xanthophyll fed on arsenicals is often improved. Arsanilic per pound in a finisher ration. Most finishers acid (p-aminobenzenarsonic acid) or sodium ar- have at least this level. Approximate available sanilate and 3-nitro-4-hydroxyphenylarsonic acid xanthophyll values for ingredients mostly re- are the commonly accepted arsenical sources. sponsible for pigmentation in broilers are given Arsanilic acid or sodium arsanilate is used at 45 on page 43. 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 Miscellaneous Additives compounds. Some of the miscellaneous additives used in Hormones broiler rations and their functions are as follows : Dienestrol diacetate, a synthetic compound with hormonelike activity, has been mixed with feed to Additive Function increase fat deposition and to give improved car- Aterrimin Growth stimulant. Dynafac Growth promotion and feed cass quality. When any product of this kind is conversion. used, the manufacturer's directions and the Food FurazoHdone, nf-180 Chemotherapeutic agent for and Drug Administration's regulations should be growth promotion and followed. prevention and treatment The Consumer and Marketing Service's poultry of fowl typhoid, paraty- inspection program includes laboratory testing phoid, pullorum disease, procedures for determining chemical residues in and CRD. poultry products. Failure to heed directions for Neomycin, neomycin use and withdrawal periods may result in poul- sulfate Used for bacterial enteritis. Nystatin, Mycostatin For prevention and treat- try products being condemned as unwholesome. ment of crop mycosis and mycotic diarrhea. Xanthophyll Reserpine To combat stress conditions. Sulfathiazole sodium To control spread of infec- In most areas, customers prefer highly pig- tious coryza. RATION FORMULATION The formulation of a practical broiler feed is in a ration if it happened to be the cheapest the combining of selected ingredients to meet source of protein. specific nutritive requirements and often process- The approximate composition of complete ing and pricing limitations. Ingredients are clas- broiler rations by ingredient classes can be used sified on the basis of the nutrient in which they as a guide and is as follows: are rich ; for example, carbohydrates, vegetable proteins, animal proteins, vitamins, stabilized Percent of fats, minerals, and miscellaneous additives. Ingredient class ration The choice of ingredients within a class de-. Carbohydrates 1 55-60 Vegetable proteins ^ 20-30 pends largely on composition, availability, and Animal proteins ^ 2.5-20 price. The feed formulator chooses the ingredi- Vitamins ^ 2-8 ents that, when combined, provide the required Stabilized fats s Ù-8 nutritive value at the lowest possible cost. The 1 Grains and grain byproducts : Corn, wheat, barley, value of ingredients and formulated feeds should, oats, millet, shorts, middlings, red dog, hominy feed, etc. whenever possible, be based on actual feeding re- 2 Soybean, corn gluten, cottonseed, peanut meals. sults. When a product of doubtful value is used 3 Fishmeal, fish solubles, meat scrap, liver meal, dried milk, feathermeal, poultry byproduct meal, etc. in an effort to provide plenty of a nutrient, the 4 Commercial vitamin supplements, alfalfa, dried whey, result can be a dangerous imbalance ; for example, dried yeast, distillers' solubles, fermentation solubles, etc. the use of feathermeal to supply all the protein 5 Grease, tallow, poultry oil, etc. 42 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE mum requirement for growth in rations contain- ing 900 calories of productive energy per pound. Mineral carriers« 1-3 Since the food intake of the growing broiler is Miscellaneous "^ proportionate to its energy requirements, the pro- «Limestone flour, oystershell flour, dicalcium phos- tein, amino acid, vitamin, and mineral levels phate, steamed bonemeal, defluorinated superphosphate, defluorinated rock phosphate, iodized salt, manganese needed in the ration are related to the energy sulfate, etc. content of the ration. As the energy content of ''^ Trace amounts of these ingredients may be added. the ration increases to 1,450 calories of produc- Many are present in commercial rations, but some may tive energy, as by the addition of high levels of not be necessary under all conditions. The group in- dietary fat, the needed level of all required nu- cludes antibiotics, coccidiostats, arsenicals, hormones, an- tioxidants, and xanthophyll. trients, especially vitamins and minerals, is sub- stantially increased. This is also true when feed The specifications or allowances for practical intake is reduced for other reasons. broiler rations are constantly changing. For a As the energy content of the ration increases, tentative set for starter and finisher rations used the percent protein required also increases if the as a basis for linear programing, see tables 6 best growth and feed conversion are desired. and 7 (p.46). Some feed formulators maintain a constant ratio For the composition of ingredients commonly of calories to protein content for their starter, used in poultry feeding, see Joint United States- finisher, and withdrawal feeds. In practical for- Canadian Tables of Composition.* These values mulation, where energy and protein levels do not will prove a reliable guide in choosing and using change much, consideration should be given to ingredients. Suppliers of ingredients will usu- expressing amino acid requirements on an energy ally furnish the analysis of their products as well basis. The ratios of amino acids to energy would as guarantees. Table 5 gives the composition appear to be a more direct means of insuring of selected ingredients to illustrate an example in amino acid adequacy and thus avoid the neces- linear programing. sity of considering the ratio of calories to pro- Wlienever possible the formulator should uti- tein as such. lize the actual chemical analyses of the ingredi- Requirements for the amino acids are all inter- ents to be used. In addition, digestibility, palat- related, and they are related to the levels of total ability, and the effect on the appearance of the protein and energy. In general, the levels re- bird should be considered. Actual feeding tests, quired of the amino acids, expressed as a percent when available, are of greatest importance. of the ration, are higher as the protein content Attention must be paid to the interrelation of increases. As an example, if the protein content nutritional factors, some of which have been indi- is 24 percent, the percent of the ration for each cated (see pp. 36-37). Examples are the protein- amino acid can be obtained by multiplying the amino acid and the calcium-phosphorus ratios. percentages given on page 33 for a ration having Proper nutrition balance is especially important a 20 percent protein level by 24/20 or factor 1.2. when environmental heat is excessively high. Since protein quality may vary markedly, recent guides for use in the formulation of poultry feeds The productive energy of practical broiler have expressed amino acid levels as a direct func- feeds probably varies from 900 to 1,100 calories tion of the energy level. Up to the optimum per pound and the metabolizable energy from energy utilization by the bird, the requirement 1,350 to 1,500 calories per pound. The optimum for methionine, lysine, glycine, and arginine goes ratio of calories to protein content may be differ- up as the energy content of the ration increases. ent depending primarily on the quality of the protein. As a guide, the optimum ratio for start- In most broiler rations the sulfur amino acids ing diets is" usuallj^ considered to be 42 to 45 (methionine and cystine) and lysine have to be calories of productive energy and 60 to 65 calo- considered most critically. The indications are ries of metabolizable energy to each percent of that the minimum levels to be used should be on crude protein in the ration. The corresponding an energy basis. For example, for best growth figures for finishing diets are 48 to 53 and 69 to and feed efficiency, the ratio of minimum sulfur 75 and for withdrawal diets, 60 to 85. The ratios amino acids (methionine and cystine) to metab- vary with the quality of the protein. The better olizable energy should be about 0.53 percent for the balance of the amino acids, the wider the starters and 0.48 percent for finishers. The cor- ratio that can be used. When the ratio is low, less responding values on the basis of productive fat is deposited. The protein requirement of 20 energy would be obtained by multiplying by 1.43. percent (p. 32) will meet the approximate mini- Because of the varying response of amino acid supplementation with different diets, other fac- 4 NATIONAL ACADEMY OF SCIENCES, NATIONAL RESEARCH tors also may have to be considered. Whenever COUNCIL, JOINT UNITED STATES-CANADIAN TABLES OF COM- feed intake is decreased, for example in hot POSITION. Pub. 659, 80 pp. Washington, D.C. 1959. weather, all nutrients should be increased in rela- COMMERCIAL BROILER PRODUCTION" 43 h II :* o o ê '-H eq c<« «o c^

CO C^ CO CO

OCOOOQQOkOOOO

T-í CO eo eo CO "5 ■^' <-H c<í

5 S

§ g ^ §

:^^

«o Cí o o -^ o t^ -^ »o CO

a

00 »o 1-H o ^■1 ,-1 T-Î cs¡ US rt<ö it .3 • fe «

I § g § s g § •i 3í

^ a> "-* 8 § § § b« 00

00 o o o o o o 1;» U5 »5 ào eo eo 00 o CO OO «o CO 00 »o

«o ■«<* o> »o o lO » Cí lO CÀ CO t^ c<¡ «o ^ s s

o CO o >* 0> 00 »o T-H 1-1 ,-( o «¿ J 00 o CO CO W T^

S § § g 13 Q, o U SJ V ^ Ö Ö p. a I 1 5 '* ft o, o -K» -§ fl 1 o ^ I -i S ^ '^- I -^ S TS S a -3 -a § 2 ■ a s ^ o 1 a ff Ö fl Ö fl v^ c 9 § i I I e8 I -3. i 2 :f ê ^ 1 & 3 a a a ^ 1 1 1 ^ I I ^ ^ a I :^ a cg á S fS ¿ s •»3 Q ^ 44 AGRICULTURE HANDBOOK 3 20, U.S. DEPT. OF AGRICULTURE tion to energy by about 7.5 percent or in propor- If calcium pantothenate is used, the amount tion to the drop in feed consumption when it is should depend on the guarantee of d-pantothenic known. To meet the sulfur amino acid levels acid activity for the product. The "1" form is needed by broilers, it may be necessary to add to inactive. A half pound of manganese sulfate high corn rations from 0.5 to 1.5 pounds per ton (70 percent) per ton of ration will provide 50 of methionine and to high milo diets as much as grams of manganese. To supply the usual 22.7 2 pounds. mg. per pound of zinc, 45.4 grams of zinc must On analysis sheets the protein, fat, fiber, cal- be added per ton of ration. To supply this will cium, phosphorus, salt, and amino acids are usu- require either 104 grams of zinc chloride or 62 ally listed as percentages, vitamin A as U.S.P. grams of zinc oxide per ton of ration. An units per pound, and vitamin D3 as international equivalent amount of zinc may be used from chick units (I.C.U.) per pound. The rest of the other acceptable sources. vitamins, except vitamin B12, and the minerals are listed as milligrams per pound. The vitamin Factors Affecting Feathering B12 content is sometimes given in micrograms (1/1,000 mg.) per pound. Sometimes minerals, The factors affecting feathering most include coccidiostats, and other additives are given in protein, folie acid, biotin, pantothenic acid, and percentages or parts per million (p.p.m.). The vitamin B12. Diets low in protein or with conversion formula is 0.01 percent equals 100 poor amino acid balance will give poor feather- p.p.m. equals 90.8 grams per ton. To shift per- ing. In general, factors that promote rapid centages to parts per million, the decimal point growth rate also induce good feathering. is shifted to the right four places. There are 454 grams in a pound. To convert milligrams Linear Programing per pound to grams per ton, multiply by 2. To More economical production of broilers has convert parts per million to grams per ton, mul- resulted from linear programing in feed form- tiply by 0.908. ulation. Linear programing is the formulation When formulating rations, the source of phos- of rations to meet specified nutritional require- phorus must be considered. The phosphorus from ments and yet cost less; hence the name least sources other than supplements is only about 30 cost diets. To be practical, the solution must percent available and that from various supple- result in least cost manufacturing. It is neces- ments varies greatly. Both the total and the sary for the nutritionist programer to have a available phosphorus content of the ration must list of representative delivered prices of all the be considered. If an 18 percent dicalcium phos- ingredients to be considered, their nutrient con- phorus product (18 percent of phosphorus, 26 tent, nutrient specifications for the feed, and percent of calcium) is listed, steam bonemeal or nutritional restrictions, including fixed maximum defluorinated rock phosphate may replace it on a and minimum amounts. phosphorus content basis. If a 14 percent prod- Linear programing sometimes includes non- uct with equal availability is used, calcium must nutritive restraints. These may be determined be adjusted. by the lack of availability of ingredients and Thirty percent of milo, 20 percent of wheat, their physical properties, whether bag or bulk. both coarsely ground, or 10 percent of hominy Machine formulation is of value in planning feed can replace yellow cornmeal. If milo or nutritional research, better utilization of the wheat is used, the birds will be less pigmented. If time of the nutritionist, more rapid application milo replaces corn, the methionine content of the of research results, greater savings, better evalua- ration will probably have to be increased. For tion of the value of ingredients, more precise each 100 pounds of com replaced by wheat or nutrient content and balance of rations, and milo, 200,000 U.S.P. units of vitamin A should better production management in the mill. be added to the ration. If stored ingredients are It is not necessary and probably is inadvisable used, the vitamin A content should be increased for most firms to have a computer. The size 1,000 U.S.P. units per pound. To meet stress needed is so large that such a computer could conditions, 0.5 mg. of menadione sodium sulfite not generally be utilized enough hours to be (vitamin K3), or its equivalent in vitamin Ki, effectively employed. The use of a computing per pound of ration is added. service is usually the only feasible way to get It is usual to specify technical grade or 70 the job done. When the prices of ingredients, percent feeding-grade manganese sulfate, 95 such as corn or soybean meal, fluctuate widely, percent calcium carbonate limestone, and 100 it may be feasible to reformulate feeds as often percent choline chloride, or their equivalents. as weekly for maximum benefits from pro- Choline chloride (100 percent) contains 86.79 graming. percent of choline. One pound of 100 percent Linear programing has its limitations. More choline chloride contains 394,027 mg. of choline. 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 nutri- amino 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 feed- feeding value of ingredients, such as feather- ing results are, in the meantime, the best assur- meal, poultry byproduct meal, blood meal, corn anee of correct formulation and should supple- gluten feed, hominy feed, and molasses. The ment the rapid precise calculations of the com- value 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 pellet ability. computed rations at several dollars less per ton. These restraints vary with every feed-manu- The formulas given are good, but are not recom- f acturing 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 concen- starter and 0.71 for the finisher ration. These trate for producing both feeds. A single con- values may be converted to actual percentages centrate for several feeds is usually less eco- needed 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 pro- 1,400 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 form- best formula will depend on the specific program ulated to meet its most critical use. Special con- and 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 TABLE 8.—Examples of iroiler starter and finisher least cost iroiler rations ^ rations resulting from linear programing model used Broiler Broiler Item starter finisher Starter Finisher Item ''E" "F" Maximum pounds 1,000 1,000 Metabolizable calories per pound, exactly number 1,400 1,450 Pounds Pounds Protein percent (^) (2) Alfalfa meal, 17 percent 40 40 Fat do (2) (2) Fishmeal, 60 percent 100 160 Fiber, maximum pounds 35 35 Poultry byproduct meal, 55 percent 200 Calcium, exact do 7 Corn, ground yellow. No. 2 1,050 1,200 Inorganic phosphorus Corn gluten meal 100 100 available, exactly do 4.5 3.5 Soybean meal, 50 percent 300 340 Arginine ^ do 12 10.8 Poultry oil 130 130 Lysine 3 do 12 10.8 Dried whey (MNC) 50 Methionine ^ do 4.1 3.7 dl-Methionine .25 Methionine^ and cystine do 7.8 7,0 Limestone, ground 11 12.5 Tryptophan ^ do 2.1 1.9 Salt, plain 11 10 Xanthophyll ^ mg 6,000 8,000 Amprol plus coccidiostat 1 1 Prostrep .75 .5 Progen arsanilic acid, 90 grams— 1 1 1 All minimum unless otherwise indicated. Constant premix (see table 7) 5 5 2 Unrestricted. 3 Per 1,400 calories. Total -, 2,000.00 2,000.0 •* Per 1,000 calories.

TABLE 7.—Typical ingredient restrictions for scrap, and com, to make complete feeds. The broiler formulas in linear programing directions of the manufacturer of the concen- trate, superconcentrate, or premix should be Broiler Broiler followed. Item starter finisher Because premixing is costly and the number of available bins and their capacity are usually Pounds Pounds limited, the number and unit size of ingredients Pounds, maximum 1,000 1,000 Soybean meal, 50 percent (1) often must be considered. Fishmeal, 60 percent : Minimum 50 50 Maximum 150 150 Broiler Feeds Poultry byproduct meal, 55 percent : Minimum 50 50 Prestarter feeds often are the same as starter Maximum 400 400 feeds, except for one or more additives—general- Corn gluten meal, maximum 200 200 Prostrep, exact -. .375 .25 ly an antibiotic used at a high level. When some "3-nitro," 45 grams, exact .5 .5 antibiotics are used at a high level in the pre- or Progen arsanilic acid, 90 grams, starter, a coccidiostat is not needed. Prestarters exact .5 are usually fed in mash form. Alfalfa meal, 20 percent : Starter feeds may be fed as mash, crumbles, Minimum 20 20 Maximum 40 40 or pellets. Birds prefer a medium-coarse feed to a fine-textured one. The grind of the com Alfalfa meal, 17 percent : in the mash is especially important. The use Minimum 20 20 Maximum 40 40 of crumbles and pellets generally results in Dried whey (MNC), exact 25 enough better growth and feed efficiency and in Molasses, cane : lower waste to more than offset their cost of Minimum 50 50 Maximum 60 60 production. The breaking down of pellets to Poultry oil, maximum 120 120 crumbles or fines is a major problem with pellets, Salt, plain, exact 5 5 especially when they are handled in bulk and Amprol plus coccidiostat __ .5 .5 Constant premix, exact — 2.5 2.5 when the formula is high in fat. The effect of pelleting on the value of the feed is less as the 1 Unrestricted. level of the energy, and especially the fat con- tent, of the feed increases. also available for blending with bulk ingredients, Broiler finisher feeds are generally lower in such as soybean meal, corn gluten meal, poultry protein and higher in fat content than are byproduct meal, feathermeal, meat and bone starters. COMMERCIAL BROILER PRODUCTION 47 Feed Preparation and Distribution and the availability and cost of reliable labor are important in deciding whether complete In feed preparation, thorough mixing is im- rations are to be manufactured, concentrates or portant. Technical assistance is often worth- premixes used in a stationary or mobile mill, or while in laying out the production unit and in the practice of mixing on the farm is followed. the selection of the equipment for it. Accuracy No method is best for all conditions. Most feeds in measuring and thoroughness in blending are are delivered in bulk from a centrally located two major considerations. mill. The use of bulk trucks has increased with Broiler feeds are mixed and delivered to the the expansion in the size of broiler enterprises. farm in many different ways. A complete feed may be manufactured. This is usually done in a rather large mill, often strategically located as Judging Feed Value to incoming and outgoing shipments. Many When feeds are tagged, a limited amount of 9 integrated broiler operations manufacture com- information can be obtained from the guaranteed plete feeds. Feeds may be shipped in bulk cars analysis. When feeds are formulated, it is pos- to depots in producing areas, where facilities sible to show on paper how close the calculated are available for loading bulk trucks. Another analysis of the feed compares with the nutri- method is to manufacture concentrates in mills tional requirements. A laboratory examination and ship them in sacks or bulk to mixing facil- of the feed gives valuable information as to the ities in producing areas, where feeds are mixed to accuracy of formulation and preparation. No go to the farms in sacks or bulk. The bulk feed is method of calculation or analysis will predeter- angered or blown into storage bins at the poultry mine the actual nutritional value of a feed. house. Most broiler growers generally use one Properly run feeding tests are the best way to of these two methods. arrive at the comparative value of feeds. A grower may take his grain to a mill to be If the feeds being compared are fed to one ground and custom mixed. A concentrate is or more separate flocks of broilers, care should generally used. It is possible to get on-the-farm be taken to have the flocks of similar breeding mixing units. These usually grind home-grown and with equal numbers of chickens of each sex. grain and combine it with a concentrate in one Accurate records should be kept of the mortality, operation. Mobile mills eliminate the costly the feed consumed, its cost, the pounds of meat investment in mixing equipment. They go to sold, and the total income. With these figures, the farm, grind and mix feed, and put it into it is possible to calculate and compare the a bin or sacks. The service is sometimes used pounds of feed required to produce a pound by the grower who produces and stores his own of meat, the feed cost of producing a pound of grain. meat, and the income over feed cost. The cal- The size of the operation and its location, culations will assist the feeder in deciding which especially in relation to the principal ingredients. feed or feed formula is best suited to his purpose. MARKETING The price received for the product largely Service for the particular area. In the case of determines whether an operation is successful or the integrated operation, it may depend on what not. Supply greatly affects price. To try to the processor gets when he sells. Price may not anticipate the price, you will need to consider be considered in a contract. The trend is away such factors as number of broiler breeders tested, from farm base calculations to ready-to-cook number of breeder pullet replacements (day-old prices. basis), number of eggs set, number of chicks placed, extent of Government buying, and com- Marketing Cycle petition of turkeys and other meat products. The number of breeders tested is an indication of Normally the demand is a third greater for what may happen in 12 months; the pullet re- broilers in June and July than in the fall. The placements, 6 or 7 months ahead; eggs set, 8 least demand is usually around Thanksgiving months; and chicks placed, 9 to 10 weeks. The and Christmas, when turkeys, roasters, and effect of the first two factors may be influenced capons are often preferred. The consumption if lots of pullets are brought in earlier than tends toward smaller broilers in the summer and usual, the breeder hens are kept longer than larger ones in the fall and winter. Most broiler usual, and less floor space is allowed per breeder operators recognize the seasonality of demand in houses. and plan accordingly. Consideration is being The farm price used for settling the grower given to freezing some birds in the August-to- contract may be based on the quoted price for December period for sale during the January-to- broilers from the Federal-State Market News June 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 take without cutting the price. In general, broil- —^the higher cost of preparing frozen birds and ers should be sold when they reach the normal consumer resistance to them. A consumer may weight for the processor. buy a chilled bird, take it home, and freeze it, The quality of an individual carcass depends on but he resists buying the frozen broilers when such factors as the shape or conformation, how chilled icepacked ones are available. Eoasters well it is fleshed, the amount and distribution of weighing 4 to 8 pounds are shipped in frozen, fat, and its freedom from such defects as breast ready-to-cook condition. The principal markets blisters, pinfeathers, disjointed and broken bones, are New York and Chicago. missing parts, discolored skin and flesh, freezer Processing, including evisceration, is done now burn, and cuts, tears, and missing skin. Poultry in the areas where the broilers are produced. is downgraded if bruising occurs to any extent. The ready-to-cook broiler-fryers are icepacked Much of the bruising is caused by the way the or dry chilled and shipped in fresh form in birds are handled between the farm and the proc- ^^ wholesale quantities by refrigerated trucks to essing plant (see p. 50). market. The broiler cutting is being shifted Several management practices will reduce from the retailer to the processor, where packs downgrading. A fasting period of 4 hours prior are sized to the specifications of the buyer, to slaughter is sufficient for the intestinal con- marked as to weight, and, if desired, prepriced. tents to be reduced to a satisfactory point so that contamination is at a minimum. Give plenty of Marketing Areas and Practices water as long as possible up to the time of slaugh- ter. Have hanging waterers. Many tears and Broilers from Maine are sent to Boston and cuts result from birds flying against inflexible local New England markets. The rest of the floor waterers. Watch for and eliminate places Northeast (Baltimore, Philadelphia, Washing- where birds can roost. Be careful not to scare ton, D.C., New York) is served principally by birds at any time. Use portable wire screens and Delmarva. The midwestern markets used to be blue light for catching birds. Have an outside supplied from the Delmarva Peninsula. Some door in each pen. In wide houses, have doors on of the broilers from the Southeast go to the each side. Remove all feeders, waterers, and Northeast, but principally they are trucked to other obstructions during loading, as they may Florida, Atlanta, New Orleans, Dallas, Chicago, cause cuts and bruises. Detroit, Cleveland, and Columbus markets. The Flesh bruises are responsible for more than half South Central States, especially Arkansas, Ala- of the undergrades in most processing plants. bama, and Mississippi, ship to Jacksonville, Breast bruises are the most common and costly of Miami, New Orleans, Dallas, Chicago, St. Louis, the injuries. Rough handling by catching crews Omaha, Salt Lake City, Los Angeles, San Fran- is the main cause of bruising, including birds hit- cisco, and Seattle. Broiler production will m- ting partitions and slamming birds into coops. crease in California, especially if growers there These crews should catch and carry birds by can produce the birds at a low enough cost to their shanks, not the drumsticks. They should compete with the south-central operations and if make small drives of about 200 birds and use the returns are at least comparable with other care in catching and handling the birds. ventures. Most of the Texas production is con- The assembly operation at the processing plant sumed in Texas. Frozen export packs have become an important should be carefully supervised. Coops should not outlet for American-produced broilers. Export- be dropped. Birds should be handled by their ing broilers has the effect of raising prices do- shanks. Care should be taken to see that the mestically. Indirectly it increases the demand birds do not hit the wall or any object while on for materials and services involved in the pro- the assembly line. Several investigators have sug- duction of broilers. gested that it might be better to load all birds as It is usual to market broilers at 10 to 11 weeks needed for processing and run a double shift at in the Maine and Delmarva areas and 9 to 91/2 the processing plant rather than to load most of weeks in the Southeast. There is no best time. the birds at night and process most of them dur- When fixed and chick costs are high and feed ing the day. costs are low, it usually is more profitable to carry The cost of catching and hauling poultry is birds longer because there are more pounds over substantial. It can be reduced by increasing the which to spread the fixed costs and the lower feed efficiency of individual farms. An important con- conversion is not so costly. The processing cost sideration is the location and size of the farms per pound is also less with a heavier bird. The supplying live birds. An outside door for each risk, mortality, and increase of breast blisters are pen or several outside doors for each house in- factors to consider when birds are kept to heavier crease efficiency. Assembly costs per pound de- weights. When the price is poor, it is often bet- cline as the density of the supply area increases. ter to market birds as small as the processor will It is advantageous to have larger producing units COMMERCIAL BROILER PRODUCTION 49 close to the processing plant. High total volume Inspection Act of 1957, which became fully effec- allows the use of trucks of larger capacity, higher tive on January 1,1959, required all poultry mov- output per man-hour, less overhead, and greater ing in interstate or foreign commerce to be in- ability to handle larger flocks in a short time. spected. Approximately 90 percent of the poul- Substantial economies occur in large-scale assem- try sold off farms, including commercial broilers, bling and processing. However, these are not so is federally inspected. The balance of the poul- important in reducing costs of operation as area try processed and sold within States may be sub- density. The expense of a catching crew averages ject to State inspection. about $3 per 1,000 birds. The transportation cost Poultry is processed and sold within some depends on the distance from the farm to the States on a noninspected basis. The pi^cessing processing plant. It ranges from one-half to 1 plant, and possibly the grading, may be' subject cent per pound of live poultry assembled. to State inspection. It is not unusual for poidtry With contract growing and integration, the that has not passed or may not pass Federal processing costs have been lowered because plants inspection to be marketed through noninspected have been better able to operate at capacity. Less channels. Some States now require all processed variation has occurred with seasonality of de- poultry sold to be federally inspected. mand and prices. The processors are primarily interested in get- The method of marketing chickens has im- ting a high percent of eviscerated yield. Con- proved about as much as production methods. demnations, which are due primarily to air-sac Large processing plants, contract haulers, and disease and chronic respiratory disease, are the contractors have practically replaced the older most important factor in reducing yield. Yields operation, which included pickups by live-poultry are increased by better body conformation and buyers, live-poultry cars, terminal market live- more white meat due to broad breasts. Good yel- poultry receivers, live-poultry stores, small fatten- low skin and flesh and some fat are desired by ing and dressing plants, and city dressing plants. most processors. Breast blisters and barebacks It is anticipated that a substantial reduction will cause downgrading. Yields are higher in larger continue in the number of processing plants and birds. that more combinations of assembling and proc- When broilers are processed, there is a strain essing will develop to improve distribution. and a sex difference in the dressing percentage. More long-term buying contracts by large buy- Cornish broilers and broiler crosses, or strains ers, such as chain stores, are anticipated. There containing Cornish, give the greatest breast and will also be, to the extent the laws allow, consoli- total edible meat yields. Breast width seems to dated selling by processors in an area. This may be the important factor. At the same age, live be done by having one selling agency represent male broilers are heavier than females, but fe- several processors. Fluctuating markets could males give greater eviscerated weights as a per- possibly be minimized by contracts based on cost centage of live weight and greater edible meat of production plus a reasonable profit. Costs yields as a percentage of eviscerated weights. The could be minimized if operations could be planned approximate percent of live weight for 3^^- to to maximize efficiency with such a program. 5-pound birds will be about 87 for New York Prior to 1927 practically all processed poultry dressed weight and 73 for eviscerated weight. was sold with only the blood and feathers re- The edible meat yield as a percent of eviscerated moved. A few plants producing canned poultry Aveight will be about 55 for males and 58 for and poultry soups had facilities for evisceration. females. The U.S. Department of Agriculture developed a Standards and Grades voluntary inspection program in 1927 as a result of a Canadian regulation, which prohibited the The U.S. standards of quality and grades for importation of canned poultry products unless poultry are used extensively for trading purposes. accompanied by a certification from the Federal Many retail distributors require that all ready-to- Government attesting that the product had been cook poultry delivered be identified with an offi- officially inspected and had been found to be cial grade mark. Ready-to-cook poultry must wholesome. New York City enacted a similar have been inspected for wholesomeness to be eli- regulation in 1928. gible for grading. Processors applying for resi- The trend toward the sale of ready-to-cook dent grading service agree to pay the cost of the poultry was well underway by 1945. By 1955 the service. Graders may be either State or Federal military began purchasing only ready-to-cook employees. The service is made available at rea- poultry, and civilian supplies were almost entirely sonable cost in all parts of the country by means in this form. Slaughtering and eviscerating of cooperative agreements with the States. Grade operations were generally done in the same plant. A, B, or C may not be used in connection with Many plants were using the Department's volun- labels bearing the official inspection mark unless tary inspection service. The Poultry Products the poultry has been graded by a licensed grader. 50 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE Classes ings of septicemia and toxemia, airsacculitis, and inflammatory processes. For information on the The official classes of young chickens are as important respiratory diseases—air-sac disease follows : (CED complex), Newcastle disease, infectious (1) Cornish game hen,—A Cornish, or Eock bronchitis, laryngotracheitis, and leukosis—see Cornish, game hen is an immature chicken about pages 53-54. 6 weeks old, of not more than 2 pounds ready-to- Other conditions resulting in condemnations cook weight. Broiler chickens usually contain- include bruises due to mishandling during the ing some Cornish breeding in the cross are used. catching, loading, and transportation of live (2) Broiler or fryer,—A broiler or fryer is a birds. Also, there are plant-caused condemna- chicken 8 to 11 weeks old, of either sex, with ten- tions, due primarily to faulty operations, which der meat and flexible breastbone cartilage. include cadavers and bruised, contaminated, over- (3) Roaster.—A roaster is a chicken usually scalded, or decomposed birds. Cadavers are 3 to 5 months old, of either sex, with tender meat largely due to improper bleeding. and breastbone cartilage that is less flexible than that of a broiler or fryer. The reduction of condemnations is very impor- (4) Capon.—^A capon is a surgically unsexed tant to the broiler industry. In 1964, the percent male chicken usually under 8 months old with condemned was 2.4, or 193,091,000 pounds (total tender meat. pounds condemned ^ (90 percent of pounds in- For details of grading live poultry and more spected — antemortem pounds condemned) ). At data on the classes and grades of poultry, see U.S. the average price estimated for 1964 of 14.2 cents Department of Agriculture Handbook 31, Poul- per pound, the direct loss was $27,418,922 for the try Grading Manual. year, not including the loss of efficiency during processing. Condemnations usually cause dis- counts in grower payments. Condemnations The official inspection mark is the consumer's Inspectors in processing plants condemn for assurance of wholesomeness. One of the primary disease and other conditions. Of the disease con- objectives of this handbook is the production of ditions, the respiratory ailments and the leukosis better birds at lower costs. Eeducing condemna- complex are the most important. Condemnations tions helps materially to do this. For specific due to respiratory ailments come under the head- suggestions, see page 26. DISEASES When a disease outbreak occurs, determine the PuUorum and Fowl Typhoid cause as soon as possible. If you do not recog- nize the disease or parasite, take or send four Most breeder flocks are tested annually for or five live chickens to a poultry diagnostic puUorum and typhoid, and eggs are not set from laboratory. Be sure to give the symptoms, them until all the birds test negative. Bird number of affected birds, number of deaths, carriers of fowl typhoid will react to the pul- source of stock, size of flock, feeding program, lorum antigen. The blood test will not detect vaccines used, your name, address, and other birds carrying the infection in the blood stream, pertinent information. only those carrying antibodies. Repeated blood It is exceptional to observe tuberculosis, chol- testing is necessary. era, coryza, blue comb disease, vibrionic hepatit- In most operations if there should be a break- is, botulism, or chiggers and ticks in broilers. through with either disease, it is possible to trace Until recently, it was exceptional to find black- the ailment to the flock or flocks involved so they head in broilers. can be eliminated immediately as a source of In broiler production the emphasis is on the hatching eggs and baby chicks. Furazolidone is prevention of diseases and then, if necessary, the drug most often used in outbreaks. on their treatment. Average total mortality to 9I/2 weeks is considered to be 4 percent. A Omphalitis practical goal is to have only 1 to 2 percent mortality up to 8 weeks. Preparation of the This disease is usually caused by contamina- broiler house is discussed on page 20. Other tion of the navel at the time of hatch. To pre- procedures in disease prevention are given on vent it, only clean eggs should be set and the page 26. For detailed information on diseases, hatchery, incubators, and hatchers should be refer to Diseases of Poultry.^ kept clean. Fumigation of eggs and incubators with formaldehyde gas is one of the best ways 5 BIESTER, H. E., and SCHWARTE, L. H. DISEASES OF POULTRY. 1382 pp. The Iowa State Univ. Press, Ames. to control this disease. For detailed recom- 1965. mendations on fumigation, see U.S. Depart- COMMERCIAL BROILER PRODUCTION 51 ment of Agriculture Miscellaneous Publication back of the hock slips to one side. This disorder 739, The National Poultry and Turkey Improve- may be due to an improper balance of calcium ment Plans and Auxiliary Provisions. and phosphorus or a deficiency of manganese, niacin, choline, or biotin. The dietary deficiency Epidemic Tremor should be corrected. There is no cure jPor the (Avian Eneephalomyelitis) affected birds.

This disease appears during the second or Nutritional Roup third week of life. Chicks have an unsteady walk and then a tremor of the neck and head. (Vitamin A Deficiency) There is no treatment for affected chicks. The breeding flock should be immunized by vaccinat- Young chicks suffering from vitamin A defi- ing at 6 to 8 weeks of age before they pick up ciency usually show a watery discharge from the natural infection. Many cases of epidemic their eyes. Eventually cheesy material collects tremor are complicated with crazy chick disease. beneath the lids. Growth is poor, feathers are The treatment for the latter should be tried. roughened, and the gait is staggery. The-treat- Survivors of epidemic tremor outbreaks are ment is to provide an adequate vitamin A intake. actively immune. Coccidiosis Crazy Chick Disease ( Encephalomalacia ) Coccidiosis is universally present in the chicken. It may affect chickens of any age and This disease is usually observed between the is caused by microscopic parasites that infect and third and the eighth week and is characterized damage the cecal pouches, the small intestine, by involvement of the nervous system. The onset and the rectum. Sick birds are droopy, chill is sudden. The birds may have convulsions, a easily, have ruffled feathers, have little or no retraction of the head, rhythmic spasms of the appetite, and may pass watery or bloody legs, paralysis, or forced backward movement. droppings. On autopsy, pinpoint hemorrhages are found in A preventive level of drug is the usual method the cerebellum. Losses can be stopped or reduced of trying to prevent the disease. In spite of by supplying adequate vitamin E m the form of all that has been done, coccidiosis is still a wheat germ oil or tocopherols. A favorable serious problem, due primarily to allowing con- response can also frequently be obtained by tamination to build up so the drug cannot handle suddenly changing the feed, using molasses, or it at the usual level given. adding alfalfa meal or wheat bran to the feed. The sporulation of the cyst stage takes place best at 65° to 85° F. and in the presence of Rickets moisture. Transmission is direct as no inter- Leg weakness and loss of vigor are the early mediate host is needed. symptoms of rickets. Later the breast becomes Chickens 4 to 6 weeks old are most susceptible crooked and joints become enlarged. The con- to infection, and loss of growth is greatest at dition is due to an insufficient amount of vitamin this age. A single chicken often has more than D, calcium, or phosphorus or an imbalance of one parasite species present. calcium and phosphorus. The ration may be adequate for normal conditions, but not for Cecal Coccidiosis added stress. Correction of the ration is usually all that is needed. Bloody droppings is the first symptom of a very acute outbreak of "cecal" coccidiosis. In less acute cases, the birds are dull and droopy, Curled-Toe Paralysis act sleepy, and huddle with ruffled feathers and (Riboflavin Deficiency) drooped wings. On postmortem examination, the cecum is greatly distended, filled with blood, Chicks with this condition usually assume a and may contain yellowish cheesy cores. The squatting position. The toes curl inward. disease is caused by a specific protozoan parasite, Eecovery is rapid if the ration is supplemented Eimeria tenella^ which lives and causes damage with riboflavin. primarily in the cecal pouches.

Slipped Tendons Intestinal Coccidiosis (Perosis) Intestinal coccidiosis causes broilers to become The joints enlarge and then the bones become weak and thin. The combs are pale. The post- distorted in perosis. The main tendon over the mortem lesions are found mostly in the intestines. 52 AGRICULTURE HANDBOOK 320, U.S. DEPT. OF AGRICULTURE Hemorrhages in the intestine are seen in acute Avian Nephrosis cases. When Eimeria necatrix is the cause of the trouble, both the ceca and the intestines may (Cumboro Disease) be affected. The primary damage is in the small Usually avian nephrosis attacks chicks between intestine. In severe cases the intestine swells 21 and 28 days of age. They are depressed and and there is bloody diarrhea. sometimes tremble. They show little interest Another cause of intestinal coccidiosis with in feed and water. They stagger, fall down, and symptoms similar to those caused by E, necatrix^^ die. The active period of mortality is 7 to 8 but often less severe, is E, maxima, E, hrunetti days, but it varies. It peaks halfway through causes damage in both the upper and lower this period. On postmortem, the kidneys are intestines and in the rectum and ceca. Other pale or gray, the bursa is enlarged, and usually intestinal species usually of less importance are hemorrhages are in the muscles of the legs, E, acervuUna^ E, praecox, E, mitis^ and E, thighs, and breast. There is no way to prevent hagani. Immunity to one species does not pro- or cure this disease. Once it is on a farm, it duce immunity to another species. Chicken coc- usually persists. Eemoving the litter, treating cidian parasites do not infect turkeys and vice the floor with lye, and spraying the house with versa. a synthetic phenolic disinfectant may help. The prevention of coccidiosis is usually by means of an anticoccidial drug given in the feed Hemorrhagic Anemia Syndrome when the chick is a day old until as near mar- keting as possible. Activity of a drug against Affected flocks do not eat, become weak, squat E, tenella and E. necatrix is essential. It is^ de- on their hocks, and show the typically pale or sirable also to prevent E, acervulma, E. maximxi, dark combs. On postmortem, irregular, scattered and E. irunetti. hemorrhages are found in the muscles of the To prevent coccidiosis, it is suggested that the breast, the outer part of the thigh, and the following drugs be used in the feed as recom- internal organs. The blood is usually pale and mended by the manufacturers: Amprolium, slow to clot. The bone marrow may be yellow Zoalene, Polystat, or Unistat. To control out- or gray instead of normal red. The kidneys are breaks of coccidiosis, it is suggested that one pale and swollen. Broilers 3 weeks old to market of the sulfonamides—sulfaquinoxaline, sulfa- age may be affected. methazine (Sulmet), or sulfathiazole—Zoalene, There is no known causative agent. Several or Amprolium be used at the levels recommended of the aspergilli may be implicated. Vitamin by the manufacturers. E and K deficiencies and moldy-feed toxicosis will produce similar signs. Other possible pre- disposing factors are excessive medication and Nonspecific Enteritis the stress of diseases, particularly avian nephro- sis (Gumboro disease). Sulfonamides (sulfa- quinoxaline, sulfamethazine, or sulfathiazole) This condition is common in young birds and seem to aggravate the condition. This syndrome is often confused with intestinal coccidiosis. may be associated with nonspecific enteritis and It is possibly related to the hemorrhagic anemia gizzard erosion. It may help to increase the syndrome and gizzard erosion. To differentiate vitamin K intake and give codfish liver solubles, it from coccidiosis, oöcysts will not be present, condensed fish solubles, and trace minerals. An it does not respond as well to sulfonamides as effort is being made to find and eliminate the does coccidiosis, and nonspecific enteritis usually cause. persists much longer—many days or weeks. Signs include listlessness, loss of appetite, and Gizzard Erosion diarrhea. Lesions consist of the inflammatory condition of the intestinal tract. This disease Gizzard erosion is characterized by small can be the result of wet litter, overheating, chill- hemorrhages under the homy layer of the giz- ing, faulty feeding, and dirty waterers. zard, causing it to darken and erode. It is often "Eed spot" disease (red spots often seen in the associated with nonspecific enteritis and the intestine) may be nonspecific or it may be due hemorrhagic anemia syndrome. The condition is to one or more species of coccidia {Eimeria found in less vigorous birds and it does not mitis^ E, mxixima^ or E, necatrix),^ If coccidia respond to treatment. are not found, the directions for using the feed- grade antibiotic, or a nitrofuran compound if Moldy-Feed Toxicosis tried, should be followed. Nonspecific enteritis does not respond well to any treatment. Good Many strains of fungi have been isolated from management seems to be a good preventive and broiler mash and from substances toxic to control measure. poultry. Chickens become depressed, develop COMMERCIAL BROILER PRODUCTION 53 diarrhea, have pale comb and wattles, and on An Outline of the Diseases of the Avian Leukosis postmortem show a hemorrhagic condition, giz- Complex. zard erosion, and a necrotic condition of the liver. Infectious Bronchitis When litter becomes damp, especially around the waterers, the molding process starts and The disease comes on suddenly and spreads grows within 10 days. It spreads to other damp rapidly with a high proportion of the chicks areas in the litter. Any feed scattered in the becoming ill. The mortality is usually less than litter serves as a means for the fungi to increase 10 percent, but may reach 70 percent in chicks and toxins to be produced. Chickens that ingest under 4 to 5 weeks and less in older chickens. infected feed or litter invariably develop a toxi- In broilers the major damage of infectious cosis. How serious it is depends on the type of bronchitis is the stress effect in bringing on air- fungi, the potency and amount of toxin, and the sac disease. The symptoms include nasal dis- period of ingestion. Toxicosis usually reaches charge, watery eyes, depression, coughing, and its peak when chickens are 4 to 6 weeks of age. gasping. Bronchitis is often followed within 7 It is not known why molds gain or lose toxicity. to 10 days by an attack of chronic respiratory disease (CRD), which is usually far more serious. A laboratorjr diagnosis is necessary, as bronchitis Aspergillosis cannot be differentiated from other respiratory Infection is usually caused by rearing chicks diseases on the basis of lesions alone. A pre- on moldy litter or on litter that has been moldy ventive and control program will depend on prior to use. Feed occasionally is at fault. The local conditions. It may include vaccination. birds usually have some difficulty breathing. There are nodules and abscesses in the lungs and Newcastle Disease yellow exúdate is in the air sacs. There is no ( Pneumoencephalitis ) treatment for affected birds. The litter should be changed. This will prevent additional birds The respiratory symptoms of Newcastle disease from becoming infected. are similar to those described for bronchitis, but are usually more severe. Mortality can be negli- Leukosis and Marek^s Disease gible or near 100 percent in 10 to 14 days, but mostly in 2 or 3 days. Following recovery, Avian leukosis and Marek's disease are char- nervous manifestations may or may not occur, acterized primarily by an independent rapid such as walking in circles, paralysis, twisted succession of divisions of essential blood-forming neck, and somersaulting. They do not occur cells. Marek's disease has commonly been with bronchitis. CRD may follow Newcastle referred to as neural and ocular lymphomatosis. disease in 5 to 7 days. As in bronchitis, lesions The neural form includes fowl and range para- are not diagnostic. There is danger of spread- lysis and the ocular form, blindness and gray, ing the disease by crates, trucks, litter, and glassy eyes. The disease does not react to the tracking. Security management is recommended. tests currently used for leukosis detection. Leu- In congested broiler areas preventive vaccina- kosis includes visceral lymphomatosis, osteo- tion is practiced extensively. petrosis, erythroblastosis, myeloblastosis, my- elocytomatosis, and nephroblastoma. Visceral Laryngotracheitis lymphomatosis is characterized by an enlarged liver. It may parallel the neural and ocular In acute laryngotracheitis, the respiratory forms. In the visceral form, any organ may be symptoms are severe—gasping and coughing. affected. The skin may have small tumors in The intake of air is accompanied by loud wheez- the feather follicles or large skin tumors. ing. In less severe attacks, the symptoms may be Osteopetrosis, the thick-leg disease, occurs more those of a cold. The incidence of the disease in male than in female broilers. The condition is much less than that of either infectious bron- often escapes detection until the birds are dressed chitis or Newcastle disease, and its spread is and may be sporadic in nature. The other forms slower. It rarely is observed in broilers less of leukosis do not usually occur in broilers. than 4 weeks old. It is highly contagious. It is The indicated preventive and control measures airborne over short distances and is transmitted are breeding for resistance, hatchery sanitation, by persons, trucks, dogs, crows, or other agents. thorough cleansing and disinfection of brooder It is a carrier disease. Some of the recovered houses and equipment, a reasonable break be- birds continue to carry the virus and to be in- tween broods, and isolation of young from adult fectious to susceptible birds. An accurate diag- stock. Parasites should be kept under control. nosis can only be done on the basis of laboratory For further information, see U.S. Department procedures. of Agriculture Production Research Report 94, 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 combined with PPLO and E, coli^ causes a severe diagnosed in the flock, all groups not affected form of CED. Good management helps reduce should be vaccinated. Mortality varies from the effects of E, coli especialTjr. below 10 to as high as 50 percent. Adverse environmental conditions will intensify the severity of the disease. The chicks may be weak, may be handled roughly, or be overheated Colibacillosis or chilled at the hatchery or on the way to the (E. coli Infections) brooder house. In the brooder house, they may be EscJienchia coli infections in broilers may take overheated, chilled, overcrowded, have insufficient the form of an enteritis or an air-sac infection. feed or water space, inadequate ventilation, too Trouble may start with infected hatching eggs. high humidity, and damp or wet litter. The most Apparently clean eggs packed in used dirty cases important stress is probably outbreaks of dis- may be contaminated by this contact. Coliform eases, such as coccidiosis, Newcastle disease, infec- bacteria are often associated with a pleuropneu- tious bronchitis, laryngotracheitis, or the reaction monialike organism (PPLO) in air-sac disease. to vaccination for Newcastle disease and infec- Pathogenic E, coli infections may be triggered at tious bronchitis. 5 to 8 weeks by stress, live-virus vaccinations, CED is an egg-transmitted disease. The rate respiratory viruses, coccidiosis, roundworms, and of transmission from breeder flock to baby chicks poor environmental sanitation and management is thought to be about 10 percent, but varies practices; for example, overcrowding, poor ven- greatly. PPLO stock negative to Se-type Myco- tilation, excessive humidity, too much dust, and plasma antigen is being produced. This stock is temperature extremes. The birds may have ruf- negative only to Se-type antigen, not necessarily fled feathers, may be droopy, and have diarrhea. to others, such as pathogenic Iowa strains 0 and If the air sacs are infected, severe depression, 695. coughing, and other symptoms similar to CKD The incidence of CED complex has been mate- are evident. A laboratory examination is needed rially reduced where PPLO-free chicks have been to diagnose this disease. used to produce broilers. By using antibiotics it To prevent and control coliform enteritis, fura- is possible to medicate the chicks and destroy the zolidone and the antibiotics—Aureomycin, Terra- Alycoplasma originating from embryonic sources. mycin, streptomycin, erythromycin (Gallimycin), The breeder replacement chicks are injected and neomycin, and tylosin (Tylan)—are used. E. coli fed a potentiated high-level antibiotic feed. They infections may readily develop resistance to cer- are then raised under a management-sanitation- tain antibiotics. security program to keep them free of CED. They must be protected from reinfection. Strict attention to isolation and sanitation is essential. Chronic Respiratory Disease The breeders so produced may be used to pro- Chronic respiratory disease (CED), avian my- duce PPLO-free chicks. These chicks should not coplasmosis, or air-sac disease is the leading cause be mixed with other chicks or exposed to PPLO of condemnations at the dressing plant. It also infection. In experiments being conducted to causes a great loss in weight and mortalitj^. In develop mycoplasma-free progeny, primary the field it is a disease from which many infec- breeder and replacement flocks are exposed to a tious agents may be isolated. The primary cause pathogenic strain of Mycoplasma at 5 to 9 weeks of the infection is a pleuropneumonialike organ- of age. ism (PPLO). CED in an uncomplicated respira- The control of CED complex, other than elimi- tory infection is caused by a PPLO identified as nating PPLO from the breeder flock, in the field a Mycoplasma, When a secondary infection is also consists of attempting to suppress the E, coli added, the disease becomes complicated and le- and other bacterial contaminants with chemo- sions may be moderate to severe m form. ^ If the therapeutic agents. Furazolidone has been ex- secondary infection is bacterium E. coli^ more tensively used. The antibiotics commonly used than one bacterium, or fungi, the symptoms are are Aureomycin, Terramycin, streptomycin, ery- usually severe. thromycin (Gallimycin), neomycin, and ty losin The combination of PPLO nnd the viruses of (Tylan). The first objective is to suppress or infectious bronchitis and Newcastle disease, eliminate PPLO. This has been done with poten- either naturally or by vaccination, causes respira- tiated Aureomycin and other antibiotic agents. tory symptoms and air-sac lesions. This mul- Locally it is sometimes practical to eliminate tiple infection found in the field is the CED com- Newcastle disease and infectious bronchitis vac- plex often called air-sac disease. The symptoms cinations, but often impractical and unattainable. and lesions are most severe when produced by Careful vaccination and antibiotic therapy help combining PPLO, E, coli^ and the viruses of in- to keep broilers growing while the birds still fectious bronchitis and Newcastle disease. Either carry PPLO. The security management program infectious bronchitis or Newcastle disease, when (p. 26) should be followed. COMMERCIAL BROILER PRODUCTION 55 Synovitis Vaccination (Infectious Synovitis) The program for vaccination should depend on local conditions. In most concentrated broiler Synovitis also causes heavy losses. Consider- areas, it is cheap insurance against heavy losses. able economic loss is due to birds getting thin and Vaccines should be used according to the in- downgrading at market time. Infectious syno- structions of the manufacturer regarding time vitis is caused by Mycoplasma synoviae^ M, gal- and method. They should be kept cool before liseptieum^ and an unnamed arthritic-producing being opened and used immediately after they are agent. opened. Sometimes broilers are vaccinated and The birds first become droopy and listless. yet an outbreak of disease occurs. In most cases, Their legs are weak. Lameness is observed. the cause is not following the directions enclosed When handled, the hocks show enlargement. The with the vaccine. swollen joints and footpads are painful and dis- Vaccination, especially for Newcastle disease, courage the birds from eating; consequently, they has often been done when the chick is a day old. soon lose weight. They huddle, as if cold. Mor- Superior results can be obtained if Newcastle dis- tality does not usually exceed 5 percent. Birds ease vaccine is given when chicks are 7 to 10 days are generally 5 to 7 weeks old when first affected. old. Except in isolated areas, a booster, or sec- In later stages of the disease the comb dries up, ond vaccination, is given in the water at 4i/^ to 5 the feathers become ruffled, and the droppings weeks. Infectious bronchitis vaccination, if used, are green with an excess of white material, or should be given 7 to 10 days after the Newcastle urates. On postmortem examination, a yellowish vaccination. fluid is found in the bursae and joints. As the Live-virus vaccines are used against fowl pox, disease becomes more severe, a cheeselike sub- infectious bronchitis, laryngotracheitis, and New- stance is present in the bursae and tendon castle disease. For Newcastle disease, killed-virus sheaths. The joints of the wings and shoulders vaccines are also available. A killed-virus vaccine and also the sternal bursa may be affected. cannot cause the disease and is therefore safer to The most effective treatment is to cull affected use and is most useful for broilers, because there birds and treat the rest with 200 grams of Aureo- is less stress for CED and it does not spread live- mycin or 100 grams each of Aureomycin and virus infection. However, it may have the dis- nf-180 (furazolidone) per ton in the feed con- advantages of increased labor cost due to having tinuously until 3 days before marketing. When to be injected, the danger of vaccination crews the disease is expected, 50 grams of antibiotic per spreading disease, the higher cost of the vaccine, ton of feed can be given to the birds continuously and the short duration of immunity. from 1 day old. This is not adequate if other in- The methods of vaccination include the wing- fections, such as CED, are a stress. There is no web^ which is used for administering one type of cheap way of preventing synovitis or of handling Newcastle vaccine; the intraocular^ in which the an outbreak of this disease. vaccine is applied with a dropper in the eye or nostril of the bird, and is used by some poultry- Fowl Pox men for Newcastle vaccination at 5 to 10 days of age; and mass immunization methods. Vaccine Fowl pox is caused by a virus and is sometimes is applied with a garden duster in the dust found in broilers in certain areas of the South, method for Newcastle vaccination. A hand or especially during the mosquito season in the late machine sprayer is used to apply the vaccine as summer and fall. The typical lesions occur on a fine mist in the spray method. The easiest way the unfeathered parts of the body. The head is with the least reaction is the water method.^ also principally affected. The infection may involve used for administering Newcastle vaccine, espe- cially boosters. It is used sometimes for bron- the mouth, nasal chambers, and eyes. Dry pox is chitis vaccination. Fowl pox vaccine is usually usually easily identified by the typical wartlike applied when the chick is 7 to 10 days old, using growth on the comb, wattles, or face. In broil- one prong in the web of the wing. ers, eye infection is most common. When pox No vaccination program is entirely successful infects the mouth and nasal passages, respiratory without strict management practices to limit pos- symptoms may be exhibited and birds may suffo- sible spread of infection. Growers should not cate. This form is called wet pox. visit other flocks. The first 4 weeks of a chick's Routine vaccination of broilers may be advis- life should be in isolation. Servicemen should able where fowl pox occurs regularly. Fowl pox visit flocks less than 4 weeks old the first thing in the morning, and they should not enter the house vaccine is preferred, using the wing-web method unless absolutely necessary. They should start and only one needle, when the birds have been in out each day with clean outer clothing. The use the broiler house for 7 to 10 days. 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 Mites—How To Control Them ; and Leaflet 474, should be made after visiting any farm where Chicken Lice—How To Control Them. there is an outbreak of respiratory ailment. Rats and Mice When outbreaks of respiratory disease occur, the disease usually has been introduced by a human Rats and mice kill young chickens, destroy carrier. eggs, eat or contaminate poultry feed, and dam- age buildings by gnawing wooden walls, foimda- tions, and equipment. They also spread many Other Conditions Causing diseases and parasites. Disease and Mortality Losses from rats and mice in a commercial broiler flock may total several hundred dollars a Barebacks and Cannibalism year, including chickens, feed, and other destruc- tion. The damage often goes unnoticed, because Feather pulling and picking can cause consid- losses are gradual and because rats and mice sel- erable loss from downgrading to mortality. Any- dom appear when anyone is in the poultry house. thing that makes the chicken uncomfortable will To make new buildings rodentproof, use con- lead to feather pulling. If feather pulling is not crete foundations and floors. Metal shields around controlled, picking may cause barebacks and lead doors and hardware cloth over openings are effec- to cannibalism and deaths. Breeding may be a tive in keeping rodents out of buildings. factor. Slowness of feathering combined with Shelter is second only to food in the rodents' poor management encourages the vice. Some requirement for survival. Control rats and mice strains are less cannibalistic than others. with poison before you attempt to destroy their Check faulty management practices. These in- breeding and hiding places. Once the rodent clude too high a temperature or humidity, lack of population is under control, dispose of trash fresh air, drafts, overcrowding, infestations of dumps, piles of old lumber or manure, and gar- worms, lice, or mites, lack of feed or water, insuf- bage. Find and block runs or burrows. ficient feed or watering space, and excessive light Mix poison in baits with cereal, ground meat, including sun spots. More feather picking occurs or fish, or sprinkle poison baits on fruits and with pellet and crumble feeding than with mash vegetables. Place bait along well-traveled runs feeding because the birds have more time to de- and near centers of activity. When using any velop vices. To avoid feather picking, debeak the poison, protect poultry and domestic animals birds properly and do everything possible to make from accidental poisoning by carefully placing them comfortable. Debeaking and providing ade- baits m protected stations. After the existing in- quate ñoor, feed, and watering space are discussed festation has been eliminated, maintain poison under Brooding (pp. 21-23). When feasible, re- stations at all buildings and trouble spots. Check move injured birds and treat with an antipick stations regularly, and keep a supply of fresh bait preparation. Other control measures include exposed to eliminate new invaders. cooling the house (p. 19), scattering whole oats Anticoagulant poisons are slow acting and re- in the litter, or adding 2 pounds per ton of fine quire 5 to 14 days to exterminate rats and 10 to salt to the mash for 2 days. 30 days for mice. For information on fast acting poisons or other control methods, consult your county agricultural agent. Mites, Lice, and Ticks Caution: All poisons are dangerous and can Mites, lice, and ticks are common external para- kill small animals and pets if used carelessly. sites of chickens. They cause stress, lack of vigor, Anticpagulant rat poisons—warfarin, pival, fu- and mortality. For information on the control of mar in, and Diphacinone-^are safe when used ac- these pests, see the following U.S. Department of cording to the manufacturer's instructions. They Agriculture publications: Leaflet 382, The Fowl may be purchased as powdered concentrates for Tick—How To Control It; Leaflet 383, Poultry 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 econom- ically feasible. (See inside front cover and Security Management, p. 26.)