Published online by Cambridge University Press: 30 September 2005
Diets for broiler chickens (n=90) were supplemented with chromium (CrCl3, 6H2O), either alone (0·2 mg/kg diet) or in a combination with ascorbic acid (0·2 mg Cr and 50 mg ascorbic acid/kg diet). The objectives of the study were to ascertain if ascorbic acid had any additive effect on the actions of chromium and whether chromium supplementation could alleviate the nutritional stress in the birds imposed by a reduced energy intake. The birds were fed at the recommended (Bureau of Indian Standards 1992) and at a lower plane of energy. Live-weight gain and diet utilization were higher (P<0·01) when the normal energy diet supplemented with chromium was fed. Food intake (35 days) was higher (P<0·001) in the birds fed with the low energy diet. There was an increase (P<0·01) in metabolizability due to the supplementation of chromium. The metabolizability of crude protein and total carbohydrate increased (P<0·05) when chromium and ascorbic acid were supplemented together. Chromium intake was higher (P<0·001) in the supplemented birds, especially in those fed with the low energy diet (P<0·05), though its retention was higher (P<0·05) when the normal energy diet was given. Chromium in combination with ascorbic acid also enhanced (P<0·01) chromium retention. Blood glucose (P<0·001) and plasma cholesterol (P<0·05) were lower in the supplemented birds and blood glucose was reduced further when ascorbic acid was supplemented together with chromium (P<0·01). Plasma protein increased (P<0·05) in the supplemented chickens. However, variation in the dietary energy concentration did not exert any significant effect on these blood parameters. Plasma chromium was higher (P<0·05) in the supplemented birds, though chromium had little effect in this regard with ascorbic acid. Plasma copper increased (P<0·05) when chromium was supplemented alone and increased further (P<0·05) when chromium and ascorbic acid were supplemented together. Deposition of chromium in the breast and thighs increased (P<0·05) due to supplementation. Protein content and total accretion of protein in the carcass were higher (P<0·05) when chromium was supplemented alone and with ascorbic acid. The supplemented birds had less (P<0·01) fat per 100 g of carcass irrespective of the dietary energy concentration. Weight of the hot carcass increased (P<0·05) due to chromium supplementation although dietary energy concentration did not affect this particular parameter. It was concluded that inorganic chromium supplementation (0·2 mg chromium/kg diet) might effectively enhance the growth performance, diet utilization and carcass characteristics in broiler chickens. Addition of ascorbic acid might also be beneficial in this regard. However, dietary energy concentration was more critical and to yield the maximum benefit of Cr supplementation in broiler chickens, an optimum level was essential.