Student Competition: Metabolism and Nutrition, Amino Acids

A study was conducted to evaluate the interaction of dietary amino acids (AA) concentrations and modern commercial broiler strains . The objective was to determine if broiler strains respond differently to AA supply when raised in similar conditions. Body weight (BW), average daily gain (ADG), feed conversion ratio (FCR), processing yields and protein turnover were evaluated. A total of 4,050 male broilers were hatched and placed in 90 pens (n = 45 birds/pen). Two thousand twenty-five Cobb MX × Cobb 500 and Ross YP × Ross 308 were used in the present study. Commercial crumble starter and grower feed were fed from d 1–11 and d 11–22, respectively. Five experimental finisher diets were fed from d 22–42 in pellet form (9 replicates per strain/diet). Isoenergetic finisher diets (3125 kcal/kg) were formulated to 80, 90, 100, 110, and 120% of the ideal amino acid recommendation of AMINOChick2: 0.80, 0.90, 1.00, 1.10, and 1.20% dLys, respectively. Other first limiting amino acids were held at a constant ratio to dLys level: Met+Cys, 0.76; Thr: 0.65; Val: 0.80; Ile: 0.71; Arg: 1.05, and Trp: 0.16. Birds were weighed and FCR determined at 10, 21, 35, and 42 d . At 42 d, 900 birds (90 per strain/diet) were processed and yield data was collected. At 42 d, there were significant differences in BW due to strain (P = 0 .0022) and diet (P = 0.001). FCR was not affected by strain. Broilers fed increasing levels of AA had better FCR at 42 d (P < 0.0001). There were no strain × dietary AA level interactions for the d 22 to 42 period for any performance perimeters. Wings, breast, tenders, leg quarters and fat pad weights were all significantly (P < 0 .0001) affected by dietary AA levels . On a percentage of live weight basis, breast (P < 0 .0001), tenders (P = 0.0102), and leg quarters (P < 0.0001) showed a significant difference between strains. There were no strain × dietary AA level interactions for processing yield weights. This trial suggests that modern strains of commercial broilers respond identically increasing dietary AA levels .