EFFECTS OF DIETARY SULFUR-CONTAINING AMINO-ACIDS ON PERFORMANCE AND BREAST MEAT DEPOSITION OF BROILER CHICKS DURING THE GROWING AND FINISHING PHASES

1. Two growth trials were performed to measure the effects of dietary methionine and cystine (SAA) on growth rate, food conversion efficienc y and breast meat deposition in male broilers. 2. In experiment 1, bro ilers were grown on 6 experimental diets covering a range from 6.9 to 9.6 g SAA/kg. The diets were fed from 15 to 33 d of age. Similarly, in experiment 2, 6 diets containing 6.0 to 8.5 g SAA/kg were fed to fini shing broilers 33 to 43 d of age. In each experiment 60 birds per trea tment were processed, and carcase yield and breast meat percentage wer e determined. 3. Significant responses in weight gain, efficiency of f ood conversion and breast meat percentage were detected, which could b e described well by exponential regression curves. Dietary SAA require ments to obtain maximum efficiency of food utilisation and maximum bre ast meat deposition were estimated to be about 9.0 g/kg from 15 to 33 d of age, and about 8.0 g/kg from 33 to 43 d of age. 4. Economic aspec ts were considered to calculate optimum SAA specifications from the re sults. In both trials, the dietary optimum of SAA was found to be high er for birds to be further processed than for birds to be marketed as whole carcases.