Body composition of the broiler-breeder pullet

Broiler breeder pullets were reared on a standard breeder-grower diet in accordance with breeder recommendations to 10 wk of age, with samples of the birds being selected for carcass analysis at 2, 3, 4, 5, 6, 7, 8 and 10 wk of age. At 10 wk of age, 264 pullets were assigned to one of three diets formulated to contain 15% CP and to provide 2,550, 2,800 or 3,080 kcal of ME per kg. The birds on the 2,800-kcal diet were fed to attain the body weight recommended by the breeder; the birds on the other diets received the same feed allotment. At 14, 16, 18, 20, 22, and 24 wk of age, 12 birds per treatment were slaughtered for carcass analysis. All of the birds were light-stimulated at 20 wk of age. From 2 to 10 wk of age, carcass analysis of the feed-restricted pullets revealed a relatively constant protein content, 20 to 21%, accompanied by a declining proportion of fat. Feeding a high-energy diet from 10 to 24 wk of age increased body weight and the absolute and proportional content of fat. The percentage of body protein was largely unaffected by the diet, but there was a consistent effect on fat content (P less than .05). The body fat and protein contents were highly correlated with body weight.