THE INFLUENCE OF REPRODUCTIVE STAGE ON THE SELENIUM STATUS OF SHEEP IN A LOW-SELENIUM REGION

The selenium status of sheep was evaluated during the reproductive sta ge in a region of low selenium level. Serum selenium concentration, wh ole blood glutathione peroxidase activity (GSH-Px), which is a good in dicator of protection against oxidative damage, as well as the activit ies of creatine kinase (CK) and aspartate aminotransferase (AST), the plasma indicators of muscle damage, were evaluated in a group of ewes during gestation and lactation and in their lambs. The selenium requir ements of ewes were found to increase during lactation. There were no differences in GSH-Px activity between the experimental and the contro l groups throughout the reproductive stage. In the second half of preg nancy GSH-Px activity was subnormal. In spite of this, no evidence of existing pathologic conditions associated with selenium deficiency was found, since the muscle markers CK and AST were within the normal ran ge. In the same way, no distinct symptoms of nutritional myopathy were observed in the lambs, suggesting that the low selenium level found i n the ewes did not cause alterations in their development.