Effect of dietary fat supplementation on the carcass composition of three genetic lines of broilers

Three genetic lines of broilers - a commercial line (Ross X Arbor-Acres), and lines selected for low abdominal fat (lean line), and high abdominal fat (fat line) were fed one of two isocaloric and isonitrogenous purified diets differing in total fat content (2 vs. 9%). Carcass composition (crude protein, ether-extract, ash, and total dry matter content) was determined on four broilers/line/diet at 21 days of age and at 1 kg body weight. Carcass protein and ether-extract were not significantly (P less than .05) affected by diet at 21 days of age or at 1 kg weight. Carcass ash was significantly (P less than .01) affected by diet at 21 days of age but not at 1 kg body weight. Genetic line of broiler significantly (P less than .05) affected carcass protein, ether-extract, and ash at 21 days of age and at 1 kg body weight. Lean line broilers had a significantly (P less than .05) higher percentage of carcass protein and a significantly (P less than .05) lower percentage of carcass ether-extract than the fat line or commercial broilers.