LACK OF INTERRELATIONSHIP BETWEEN THE EFFECTS OF DIETARY FACTORS AND FOOD WITHDRAWAL ON CARCASS QUALITY OF BROILER-CHICKENS

1. Four factorial experiments were carried out to determine whether th ere is any interrelationship between dietary energy-to-protein (E:P) r atio (experiments 1, 2 and 3) or pelleting the diet (experiment 4) and the duration of food withdrawal (FW), in their effect on carcase qual ity of broiler male chickens. The quality was evaluated by yields of c arcase and breast meat, abdominal fat pad size, and the content and co mposition of the fat in the meat. The effect of sex on the response to FW was also determined in experiment 3 and that of age in experiment 4. 2. The diet with an E:P ratio higher than recommended decreased the weights of carcase and breast meat significantly (P< 0.05) in 2 of th e 3 experiments, and consistently increased the size of the abdominal fat pad and the fat content in thigh, but not in breast meat. Abdomina l fat pad and the fat in meat of birds fed on this diet contained a si gnificantly higher amount of oleic acid and a lower amount of linoleic acid, than the fat of birds fed on the diets with the recommended and the low E:P ratios. The pellets increased significantly the weights o f carcase and breast meat and the relative size of abdominal fat pad. 3. FW for 24-h decreased significantly the weight at slaughter in all 4 experiments, carcase weight in 3 experiments, and breast weight in 1 experiment. However, it did not affect the relative size of the abdom inal fat pad, the fat content in thigh and breast meat, and the compos ition of fatty acids in these tissues and in abdominal fat. None of th e variables mentioned was affected significantly by the interaction be tween the dietary factors evaluated, sex or age of the birds on the on e hand, and (FW) on the ether hand. 4. It is concluded that the effect of 24 h of EMI on weight at slaughter, carcase and breast meat weight s and on fattening, is not affected by dietary E:P ratio, pelleting th e diet, or sex and age of the broilers.