Effects of changes in nutritional copper on erythrocyte superoxide dismutase activity in sheep

In copper-deficient lambs with serum copper less than 0.30 microgram/ml there was a linear relationship between erythrocyte superoxide dismutase (SOD) activity and serum copper concentration. When these lambs were fed adequate copper (10-14 mg/kg of feed), SOD increased by 68 per cent over 90 days. The time course of this increase corresponded to the erthrocyte lifespan of lambs. In sheep given excess copper (0.25 g/kg body weight over seven weeks) erythrocyte SOD activity did not differ significantly from that of control sheep. A 40 per cent decrease in erythrocyte SOD activity occurred in sheep fed diets supplemented with molybdenum and sulphate for 90 days. Compared with controls, these sheep stored less copper in their livers and had similar caeruloplasmin activities but higher serum copper concentrations.