Copper in diets for growing pigs

Twenty-eight centres participated in two co-ordinated trials to obtain further evidence on responses of growing pigs (20–86 kg) to different levels of copper sulphate (CuSO 4 . 5H 2 O) supplementation, and on effect of lowering the amount of copper in the ‘finishing’ diet. The levels of copper supplied were 141, 232 and 276 mg Cu/kg diet in the ‘starting’ diet in trial 1 and 125, 200 and 250 in the ‘starting’ diets continuing or reducing to 125 mg Cu/kg diet in the ‘finishing’ diets in trial 2. The results varied to such an extent that no definite conclusion could be drawn, but there was a tendency to support rather than dispute the accumulated evidence in world literature that the most effective levels of copper supplementation are from 200 to 250 mg/kg diet throughout the growing period.