Environmental temperature and choice feeding of the broiler

1. Broilers were kept under environmental temperature regimens of 16, 21, 26 or 31° and given, 22-57 d of age, either a complete diet or free-choice of whole wheat and a higher-protein food containing either 252 or 516 g crude protein (nitrogen × 6.25)/kg.2. Broilers maintained at 16 and 21° consumed food at a significantly higher rate than those kept at 26° and the latter had a significantly higher food intake rate than broilers kept at 31°, for each feeding treatment. Compared with 21° the 57 d body-weight of broilers kept at 26° and 31° was significantly reduced.3. When kept under the 16, 21, 26 and 31° regimens, the amount of whole wheat in the food consumed by the broilers choice-fed with wheat and the 252 g crude protein/kg food was 56, 55, 48 and 46% respectively. The corresponding values for the broilers on the second choice-feeding treatment were 80, 76, 79 and 72%.4. Except for a single instance the choice-fed broilers grew at a significantly slower rate than broilers given the complete diet.