THE INFLUENCE OF DIFFERENCES IN DIETARY AMINO-ACIDS DURING THE EARLY GROWING PERIOD ON GROWTH AND DEVELOPMENT OF NICHOLAS AND BRITISH UNITED TURKEY TOMS

From 0 to 4, 4 to 8, and 8 to 12 wk of age, Nicholas (NIC) and British United Turkeys (BUT) toms were fed one of two series of experimental diets. All toms were fed the same diet, appropriately adjusted for age period, from 12 to 16 and 16 to 24 wk. The first series was formulate d to 1984 NRC specifications whereas the second series contained highe r,concentrations of lysine and total sulfur amino acids (NRC+). The NI C toms were heavier (P less-than-or-equal-to .05) at 4, 8, 12, and 16 wk, but there were no strain differences at 20 wk. The NRC+ diets sign ificantly increased BW in both strains at 12 wk, but there were no die t effects at 16 or 20 wk. At 12 wk, BUT toms had significantly more ca rcass protein and less carcass lipid compared with NIC toms, but there were no significant dietary effects on these variables. In both strai ns, the NRC+ diets significantly increased the relative weight of the eviscerated carcass and both the absolute and relative weights of the Pectoralis major muscles at 12 wk. At 20 wk, the absolute and relative weight of the Pectoralis minor muscles was significantly heavier in B UT toms and in toms fed the NRC+ diets. The tibia and femur were longe r in BUT toms compared with NIC toms. From 1 to 24 wk, weekly BW from 50 toms per strain and treatment combination were used to calculate gr owth curve parameters according to the Gompertz equation. The slope of the growth curve was significantly less in BUT toms, but the BW and a ge at the point of inflection were increased compared with NIC toms. T here were no significant diet effects on any growth curve parameters.