1678 - Further Studies on the Influence of Genotype and...

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1678 Received for publication January 30, 1998. Accepted for publication June 1, 1998. 1 Supported by state and Hatch funds allocated to the Georgia Agricultural Stations of The University of Georgia. 2 To whom correspondence should be addressed: gpesti@uga. cc.uga.edu 3 Present address: Dept. Zootecnia, Univ. Sao Paulo, 13418-900 Piracicaba SP, Brazil. Abbreviation Key: FCR = feed conversion ratio. Further Studies on the Influence of Genotype and Dietary Protein on the Performance of Broilers 1 E. R. SMITH,* G. M. PESTI,* ,2 R. I. BAKALLI,* G. O. WARE, ² and J.F.M. MENTEN 3 *Department of Poultry Science and ² School of Forest Resources, The University of Georgia, Athens, Georgia 30602 ABSTRACT An experiment was conducted to quan- tify genetic differences in response to dietary protein level of male vs female broilers. Broilers (1 d old) from a “high-yield” strain cross (Ross × Ross 208) and a “fast- growing” strain cross (Peterson × Arbor Acres) were placed on fresh pine shavings in floor pens. From Day 0 to 18, all birds were fed a 23% CP starter diet. During Days 18 to 53 male birds were fed either a 16, 18, 20, 22, 24, or 26% CP diet (3,200 kcal ME/kg) and female birds were fed the 16, 20, or 24% CP diet. Significant differences ( P < 0.05) were noted in the performance of the different strains. Ross × Ross 208 male birds had a higher body weight (3.37 vs 3.16 kg), higher feed intake (7.08 vs 6.78 kg), higher breast yield (31.76 vs 29.25%), higher carcass yield (73.90 vs 71.85%), and a lower adjusted feed conversion ratio (FCR; 2.10 vs 2.16 g:g) than Peterson × Arbor Acres males at 53 d of age. As compared to Peterson × Arbor Acres females, Ross × Ross 208 female broilers also had a higher body weight (2.68 vs 2.55 kg), higher breast meat yield (33.61 vs 30.80%), higher carcass yield (75.31 vs 73.91%), and lower adjusted FCR (1.97 vs 2.04 g:g). Qualitative differences in the response of these strains were confirmed and better qualitative data is presented that can be used to predict the important output parameters from the import inputs in broiler production. ( Key words : broiler, strain, sex, carcass yield, dietary protein, abdominal fat pad) 1998 Poultry Science 77:1678–1687 INTRODUCTION Improvements in the genetic composition of broilers is a compelling reason for producers to reevaluate their feeding regimens. Geneticists have selected for im- proved body weight on the assumption that it will increase the salable product (carcass weight) with the same or reduced inputs (mainly feed). Different growth potentials for different strains have been found (Proud- foot and Hulan, 1978; Malone et al ., 1979; Boa- Amponsem et al ., 1991; Holsheimer and Veerkamp, 1992). A genetic influence on feed conversion ratios (FCR; grams feed consumed per gram body weight change) was found by Hulan et al . (1980). Jackson et al . (1982), Leclercq (1983), Marks and Pesti (1984), and
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This note was uploaded on 07/28/2011 for the course VET 4335 taught by Professor Sakomura during the Spring '11 term at University of South Pacific.

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1678 - Further Studies on the Influence of Genotype and...

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