EFFECT OF VARIOUS DIETARY SELENIUM (SE) INTAKES ON TISSUE SE LEVELS AND GLUTATHIONE-PEROXIDASE ACTIVITIES IN LAMBS

Experiments were conducted to examine selenium (Se) metabolism in tissues of lambs following Se supplementation at varying doses. For three months four groups of lambs were fed either a basal diet (group A) containing 0.082 mg Se per kg dry matter (ppm) or the same diet plus mineral mixture with Se (as selenite) so that the total diet contained 0.25, 0.41 and 0.58 ppm Se (groups B, C and D, respectively). After three months six lambs of each group were slaughtered and tissues were removed for Se level and GSH-Px activity determinations. Among the tissues of lambs fed the basal diet the highest Se concentration was found in the kidney (1.32 mug/g wet weight), and the lowest in the skeletal muscle (0.030 mug/g wet weight). In the liver, heart, lung and spleen Se concentrations were almost at the same level and varied in the range of 0.14 to 0.18 mug/g wet weight tissue. No increase in Se concentration was found in the kidneys of Se-supplemented animals. Se concentration in the liver and lung increased linearly with the Se level in the diet. In the spleen, heart and skeletal muscle the highest Se concentrations were found in lambs fed 0.41 ppm Se. Tissue GSH-Px activities (calculated on the per g protein basis) increased significantly in Se-treated animals. In the tissues of lambs fed 0.25 ppm Se the enzyme activities were higher in a range of 1.8 to 3.5 as compared to the group fed the basal diet. Higher doses of dietary Se had much smaller effect on the tissues GSH-Px activity. Basing on the results obtained it can be ascertained that a plateau level of GSH-Px activity was reached at a dietary Se level of 0.25 ppm for the kidney, liver, spleen and skeletal muscle, and at 0.41 ppm for the lung and heart. In unsupplemented and Se-supplemented lambs tissue GSH-Px activities were in the order: spleen > heart > lung > kidney > liver > muscle.