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Unformatted text preview: 2001 Poultry Science Association, Inc. R ESPONSE OF E ARLY- AND L ATE- D EVELOPING B ROILERS TO N UTRITIONALLY A DEQUATE AND R ESTRICTIVE F EEDING R EGIMENS D URING THE S UMMER W. A. DOZIER, III 1,2 and E. T. MORAN, Jr. Poultry Science Department and Alabama Agricultural Research Station, Auburn University, AL 36849-5416 e-mail: [email protected] Primary Audience: Complex Managers, Nutritionists, Processing Plant Personnel S UMMARY Male broilers, characterized as either early- or late-developing based on their growth characteristics, were compared under summer conditions in their response to an adequate feeding regimen designed to optimize growth and a restrictive one intended to minimize late mortality. Accordingly, the early-developing strain grew faster initially, whereas the late-developing strain had the advantage prior to marketing. Ultimately, both strains had similar body weights at 49 d of age. Both broiler sources also responded similarly to each of the feeding regimens. Under summer conditions, adequate nutrition enabled reasonable growth rate throughout production, but restriction of effective protein relative to energy severely limited performance without an advantage to mortality. Differences in chilled carcass weights after processing paralleled differences in live body weight. Fillet yields and their physical dimensions were similar between strain-crosses, but they were both reduced as a consequence of using the restrictive regimen. Key words: Broiler, environment, nutritional restriction 2001 J. Appl. Poultry Res. 10:92–98 D ESCRIPTION OF P ROBLEM Broilers progress from hatching to marketing through several stages of development. Com- mercial genetic sources can differ in both growth rate and body composition depending on selec- tion strategy. In turn, nutrient needs are also likely to be altered to accommodate growth of each source [1, 2]. In practice, the broiler indus- 1 To whom correspondence should be addressed 2 Present address: University of Georgia, Department of Poultry Science, Rural Development Center, P.O. Box 1209 Tifton, GA 31793. Phone: (229) 386-3442. Fax: (229) 386-3448 try employs various feeding regimens. Nutri- tionally adequate feeding regimens enable opti- mum live performance and meat yield, but they are usually expensive and a high incidence of late mortality often results with today’s high performance bird. Conversely, feeds that pro- vide low protein relative to energy not only de- crease the rate of development and have reduced costs but often relieve mortality associated with rapid development. DOZIER, III AND MORAN, JR.: BROILER GROWTH AND NUTRITION 93 High environmental temperatures adversely affect broiler growth rate, feed consumption [3, 4, 5], and carcass yield [6, 7]. Increasing dietary protein level has been one approach to correcting for decreased protein intake. Temim et al.  used 4- to 6-wk-old broilers and reported that the reduction in live performance and breast meat yield associated with high environmental...
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- NS, Broiler, E. T. MORAN, W. A. DOZIER