The response of cage‐reared broiler cockerels to dietary supplements of nitrovin, zinc bacitracin or penicillin used singly or in paired combinations

The effect of feeding diets supplemented with procaine penicillin (50 mg/kg), zinc bacitracin (25 mg/kg) or nitrovin (20 mg/kg) singly or in combinations on the performance of broiler cockerels from 1 to 56 d was assessed. 2. The growth of treated birds was significantly better than that of controls fed on a basal diet, but no combination of additives was significantly superior to the additives given singly. 3. Performance up to 56 d of birds fed continuously on a diet supplemented with zinc bacitracin (25 mg/kg) from 1 d old was better than that obtained when the supplement was either introduced or withdrawn at different ages.