Effect of dietary protein and fat levels on fattening of corticosterone-injected broiler chicks

The effect of dietary composition on fattening of cotricosterone-injected broilers was studied with Hubbard male chicks. Corticosterone was injected daily from 26 days of age during 9 days at a concentration of 600 micrograms/bird/day. Dietary energy to protein (E:P) ratio or fat level did not significantly affect body weight gain, abdominal fat pad size, skin dry matter, or liver parameters in corticosterone-injected chicks. However, corticosterone-injected birds fed the diet containing the narrower E:P ratio had smaller livers which also contained less fat than chicks fed the diet with a wide E:P ratio. This effect, although consistant in three experiments, was significant (P < .01) only in one. It is concluded that dietary fat level and E:P ratio do not affect carcass fat content of corticosterone-injected chicks, but diets containing wide E:P ratios may increase fattening of the liver considerably.