title: Changes in the digestible lysine and sulfur amino acid needs of broiler chicks during the first three weeks posthatching.
abstract: Four experiments were conducted to study the changes in the digestible lysine (DLYS) and sulfur amino acid (DSAA) requirements of broilers during the first 21 d posthatching. Cobb 500 by-product male broilers were fed corn-corn gluten meal-soybean meal diets formulated to be isocaloric and isonitrogenous. Five graded levels of either Lys or SAA were used, varying from 0.78 to 1.28% DLYS (experiments 1 and 2) and from 0.61 to 1.08% DSAA (experiments 3 and 4). Body weight gain (BWG) and gain:feed ratio (GF) were calculated at 4, 7, and 21 d. The DLYS requirements based on BWG varied from 0.98 at 4 d of age to 1.01% at 21 d in experiment 1 and from 0.95 at 4 d of age to 0.99% at 21 d, in experiment 2. Based on GF, the DLYS requirement varied from 1.08 to 1.10% in experiment 1, and from 0.98 to 0.94% in experiment 2 at 4 and 21 d, respectively. The estimated DSAA requirements for BWG varied from 0.83 to 0.88% or from 0.71 to 0.75% for 4 and 21 d in experiments 3 and 4, respectively. For GF, the DSAA decreased slightly from 0.88% at 4 d to 0.83% at 21 d in experiment 3, but did not change in experiment 4 (0.81%). Minimal changes in the DLYS or DSAA estimated requirements occurred during the first 21 d of age, which suggests that the recommended DLYS and DSAA levels determined at 21 d of age appear to be adequate to meet chick needs for the first week of age.
authors.affiliation: Department of Poultry Science, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: A
authors.initials: A
authors.lastname: Garcia
authors.forename: A B
authors.initials: AB
authors.lastname: Batal
mesh_terms: D000603:Amino Acids, Sulfur / Q000008:administration & dosage*; D000818:Animals; D002645:Chickens / Q000254:growth & development*; D004032:Diet; D004063:Digestion; D005983:Glutens; D008239:Lysine / Q000008:administration & dosage*; D008297:Male; D009751:Nutritional Requirements; D013025:Glycine max; D013997:Time Factors; D015430:Weight Gain; D003313:Zea mays
chemical_list: D000603:Amino Acids, Sulfur; D005983:Glutens; D008239:Lysine