The effect of diet and copper supplementation on chick growth

Two experiments are described in which various diets were fed to broiler chicks, with or without a supplement of 0.1 per cent CuSO 4.5 H₂O supplying 250 mg/kg added Cu. When the basal diet was composed mainly of wheat and fish meal with added tallow, growth responses to copper measured at 6 weeks of age were 7.6 per cent in the first experiment (highly significant) and 2.8 per cent in the second experiment (0.1 > P > 0.05). When the basal diet was composed mainly of maize and soya‐bean meal there was no response to added copper in the first experiment and a significant depression in growth in the second experiment. A basal diet containing 25 per cent of dried whey gave very poor growth (about 60 per cent of normal) but showed a large response to the addition of Cu. Responses to added Cu in all diets were generally larger in the faster growing males than in the female chicks.

Where positive growth responses to copper were obtained, food consumption was usually higher, but efficiency of food utilisation was better in the chicks given the copper‐supplemented diets.

The average concentrations of Cu found in the livers of birds with or without copper supplements were 4.41 and 4.10 mg/kg of fresh liver respectively in the first experiment and 6.88 and 4.56 mg/kg of fresh liver in the second experiment. The difference in the second experiment was highly significant.