SULFUR AMINO-ACID REQUIREMENT OF BROILER CHICKS FROM 14 TO 38 DAYS OFAGE .1. PERFORMANCE AND CARCASS YIELD

Two experiments were conducted to evaluate increasing dietary levels o f methionine and TSAA on broiler performance and carcass yield, In Exp eriment 1, the corn-soybean basal diet contained .75% TSAA, to which i ncreasing dose levels of DL-methionine were added, providing at the hi ghest supplemental level .95% TSAA. The experimental diets were fed fo r 20 d, covering the age period of 14 to 34 d. In Experiment 2, a corn -soybean basal diet containing .70% TSAA was used along with DL-methio nine supplements to determine TSAA requirement during the age period o f 14 to 38 d. The highest supplemental level of DL-methionine in this experiment provided .94% TSAA. The TSAA requirement was found to be hi gher for maximum efficiency of feed utilization and breast meat yield than for obtaining maximum weight gain. Based on feed conversion effic iency and breast meat yield, the requirement for TSAA was estimated to be at least .88% for the age period of 14 to 34 or 38 d. It was calcu lated that the estimated TSAA requirement was equivalent to approximat ely .75% apparent digestible SAA or .78% true digestible SAA.