The lysine requirement and ratio of total sulfur amino acids to lysine for chicks fed adequate or inadequate lysine

• Published in: Poultry science 1998-04, Vol.77 (4), p.564-569
• Main Authors: Knowles, T.A. (Louisiana State University Agricultural Center, Baton Rouge, LA.), Southern, L.L
• Format: Article
• Language: English
• Subjects: ACIDE AMINE SOUFRE; ACIDE GLUTAMIQUE; ACIDO GLUTAMICO; Amino Acids, Sulfur - analysis; AMINOACIDOS SULFURADOS; Animals; BESOIN NUTRITIONNEL; CHEMICAL COMPOSITION; Chickens - physiology; CHICKS; Cohort Studies; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Diet - veterinary; Dietary Supplements - standards; Eating; EFFICACITE ALIMENTAIRE; EFICIENCIA DE CONVERSION DEL PIENSO; FEED CONVERSION EFFICIENCY; FEED INTAKE; GAIN DE POIDS; GANANCIA DE PESO; GLUTAMIC ACID; Glycine max - chemistry; INGESTION DE PIENSOS; LISINA; LIVEWEIGHT GAIN; LYSINE; Lysine - administration & dosage; Lysine - standards; Male; METHIONINE; METIONINA; NECESIDADES DE NUTRIENTES; NUTRITIONAL REQUIREMENTS; POLLITO; POUSSIN; PRISE ALIMENTAIRE (ANIMAUX); SULPHUR AMINO ACIDS; WEIGHT GAIN
• ISSN: 0032-5791; 1525-3171
• DOI: 10.1093/ps/77.4.564

Experiments (Exp.) were conducted with Cornish Rock males (4 to 14 or 15 d of age) to determine the Lys requirement (Exp. 1) and the optimum ratio of TSAA:Lys for chicks fed adequate or inadequate Lys (Exp. 2). In Exp. 1, 180 chicks were allotted on the basis of BW to six treatments with six replications of five chicks each in a completely randomized design (CRD). Average initial and final BW were 73.5 and 415.5 g. The Lys levels fed were: 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3% digestible Lys. In Exp. 2, 240 chicks were allotted on the basis of BW to 12 treatments with four replications of five chicks each in a CRD. Average initial and final BW were 68.5 and 336.3 g. Chicks were fed either 0.82 or 1.0% digestible Lys and within each Lys level, a ratio of TSAA:Lys of: 0.55, 0.63, 0.72, 0.80, 0.88, and 0.96, resulting in a 2 X 6 factorial arrangement of treatments. At the end of each trial, all chicks were weighed and pen feed consumption was measured. In Exp. 1, average daily gain (ADC) and gain:feed (CF) increased (linear, P 0.01; quadratic, P 0.02) as dietary Lys increased. A cubic (P 0.04) effect of Lys for average daily feed intake (ADFI) was observed. One-slope, broken-line regression models estimated Lys requirements of 1.0, 0.9, and 1.1% for ADG, ADFI, and GF, respectively. In Exp. 2, chicks fed 1.0% Lys had higher (P 0.01) ADG, ADFI, and GF than chicks fed 0.82% Lys. Daily gain, ADFI, and GF increased (linear, P 0.01; quadratic, P 0.01) as TSAA:Lys increased. For ADG, ADFI, and GF, one-slope, broken-line regression models estimated required ratios of TSAA:Lys of 0.66, 0.71, and 0.63 for chicks fed 1.0% Lys and 0.66, 0.67, and 0.63 for chicks fed 0.82% Lys There were no differences (P 0.05) in the estimated ratios of TSAA:Lys required to maximize ADG, ADFI, and GF for chicks fed 0.82 and 1.0% Lys. Thus, similar ratios of an indispensable amino acid to Lys can be obtained when chicks are fed at or slightly below their Lys requirement