Influence of different levels and sources of copper supplementation on performance, some blood parameters, nutrient digestibility and mineral balance in lambs

Two trials were conducted in a 2×2+1 factorial experiment based on a completely randomized design to evaluate the effects of different sources of copper (Cu) on performance, plasma metabolites, nutrient digestibility and retention of some minerals in male lambs on a barley based diet. The first trial consisted of 25 lambs (6–7 months of age) which were randomly allotted to 5 treatments including, (1) basal diet (containing 8.6 mg Cu/kg DM; control) without supplementary Cu; (2) basal diet+10 mg Cu/kg DM as CuSO 4 (Cu–S 10); (3) basal diet+20 mg Cu/kg DM as CuSO 4 (Cu–S 20); (4) basal diet+10 mg Cu/kg DM as Cu-proteinate (Cu–P 10); and (5) basal diet+20 mg Cu/kg DM as Cu-proteinate (Cu–P 20). The basal diet consisted of 70% barley grain, 27% alfalfa hay and 3% soybean meal. Blood samples were taken via the jugular vein on 0, 7, 14, 28, 57, 65 and 84 d and analyzed for serum ceruloplasmin, total antioxidant capacity, red blood cell superoxide dismutase activity, erythrocyte count, packed cell volume, hemoglobin and plasma mineral concentrations. For the second trial, 4 lambs from each treatment were randomly selected and transferred to metabolic cages to evaluate the effects of different Cu sources on nutrient digestibility and Cu, zinc (Zn), and nitrogen (N) retentions. Copper source had a significant effect on ceruloplasmin concentration ( P P P >0.05). Total antioxidant capacity increased ( P P >0.05). No clinical signs of copper toxicity were observed in this study, although we speculate that the continuance of treatments would have produced copper toxicity and hence hemolytic anemia.