The evaluation of selenium status of sheep from the major production areas of Morocco.

In order to evaluate the selenium status of sheep in the major raising areas of Morocco, blood selenium concentration, erythrocyte glutathione peroxidase activity and feed selenium levels were determined. A total of 843 blood samples from sheep and 118 feed samples were analyzed. Results showed that 73% of sheep sampled had blood selenium concentrations below 100 ng/ml, and were deficient or marginal. Erythrocyte glutathione peroxidase activity was below 19 IU/g hemoglobin and feed selenium levels below 0.1 mg/kg on a dry matter basis. The erythrocyte glutathione peroxidase activity was highly correlated with blood selenium concentration over a wide range of selenium levels (r = 0.88, P less than 0.001, N = 622), indicating that the enzyme can be used as an indicator of the selenium status of grazing sheep.