SULFUR AMINO-ACID REQUIREMENT OF BROILER CHICKS FROM 14 TO 38 DAYS OFAGE .2. ECONOMIC-EVALUATION

A calculation model was developed that can be used to derive dietary m ethionine and cystine (TSAA) levels for maximum profitability in growi ng broilers. Based on dose-response curves from two broiler experiment s, the model calculates additional income from improved feed conversio n and from increased breast meat yield. From the comparison of additio nal income to the additional cost associated with increasing dietary T SAA levels, the TSAA content giving maximum profit can be estimated. U nder European price conditions, a dietary level of .95% TSAA was found to be most profitable for broilers grown to 1.7 kg (Experiment 1, 14 to 34 d of age), when only the feed conversion response to dietary TSA A was considered. In broilers grown to 2.2 kg (Experiment 2, 14 to 38 d of age), two situations were simulated. If only the feed conversion response was evaluated, the most profitable TSAA level would be .85%. If both feed conversion and breast meat responses were considered, a h igher level of .89% TSAA would be optimum. Changing prices of input an d output variables (broiler feed, breast meat, DL-methionine) affected the respective economic optimum level of dietary TSAA only slightly.