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Unformatted text preview: Variations in the Digestible Sulfur Amino Acid Requirement of Broiler Chickens Due to Sex, Growth Criteria, Rearing Environment, and Processing Yield Characteristics B. S. Lumpkins,* A. B. Batal,* 1 and D. H. Baker† *Poultry Science, University of Georgia, 208 Poultry Science Building, Athens 30602; and †Department of Animal Science, University of Illinois, Urbana 61801 ABSTRACT Four experiments (Exp.) were conducted with Cobb 500 chicks to evaluate variations in the esti- mated digestible sulfur amino acid (DSAA) requirement of broilers due to rearing environment, sex, or growth performance during the starter period (7 to 19 d), and live performance response and carcass yield characteristics during the grower period (21 to 42 d). In the first 3 experi- ments conducted during the starter period, chicks were allocated to battery or floor pens, and in the fourth experi- ment birds were reared in floor pens. For Exp. 1, 2, and 3 a sulfur amino acid deficient corn-soybean meal-corn gluten meal basal diet and for the grower experiment a corn-soybean meal-peanut meal basal diet was formu- lated to be isocaloric and isonitrogenous within experi- ment. Graded levels of DSAA ranged from 0.54 to 0.94% in Exp. 1, 0.53 to 1.03% in Exp. 2, 0.49 to 0.89% in Exp. 3, and 0.43 to 0.83% in Exp. 4. True digestibility of the diets was determined using the precision-fed rooster assay. The DSAA requirements were estimated using 1-slope broken-line methodology. During the starter period, the average DSAA requirement of males and females was Key words : digestible sulfur amino acid requirement, broiler, rearing environment, growth performance, carcass yield 2007 Poultry Science 86:325–330 INTRODUCTION Sulfur amino acids ( SAA ) are essential for growth, meth- ylation reactions, and feather synthesis and are important precursors for synthesis of glutathione, taurine, coenzyme A, selenoenyzmes, and polyamines. Because of the im- portant role SAA play in the body, determining a proper requirement is of the utmost concern. The development of synthetic sources of Met has made it easier for nutrition- ists to adjust the levels of TSAA for experimental purposes in addition to making it easier for proper feed formulation through supplementation of DL-Met or DL-OH-Met. Re- 2007 Poultry Science Association Inc. Received June 26, 2006. Accepted November 9, 2006. 1 Corresponding author: email@example.com 325 similar when based on the gain to feed ratio (G:F; 0.71 and 0.71%, respectively) and BW gain (BWG; 0.67 and 0.67%, respectively). In Exp. 3 involving battery and floor pens, males and females had similar DSAA requirement estimates, but the DSAA requirement based on maximal G:F (0.68%) was higher than the maximal BWG require- ment (0.61%). In the grower period, the estimated DSAA requirement for males based on G:F was higher than that based on BWG, but the BWG and G:F requirements were similar for females. The DSAA requirement estimates were similar for males and females based on BWG...
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