Broiler response to energy or energy and protein dilution in the finisher diet

Two experiments were carried out with male broiler chickens in which diets from 35 to 49 d of age were diluted by oat hulls and sand. In one experiment only energy was diluted; in the second experiment, both energy and protein (amino acid) levels were affected. Each diet was tested with four replicate floor pens each containing 25 1-d-old birds. All birds received a standard starter diet to 16 d and then grower diet to 35 d. In Experiment 1, dilution of only energy resulted in a significant linear (P < 0.01) reduction in body weight at 42 d, although there was growth compensation after this time such that all birds weighed the same at 49 d. Diet energy dilution resulted in increased feed intake, although energy intake was not maintained (P < 0.01). Diet energy dilution generally had little effect on carcass weight or yield of breast meat, although there was less abdominal fat (P < 0.01). In Experiment 2, dilution of both energy and protein had a comparable effect on growth rate as described in Experiment 1; however, in this study there was a linear decrease in carcass weight and breast meat yield as the diet was diluted. These results suggest that the male broiler chicken can grow quite well on very low energy diets but that a period of at least 7 d is required for adjustment to feed intake. Even with compensatory increase in feed intake, however, the bird is unable to maintain its energy intake when fed such diluted diets.