Selenium, Copper, Zinc, Manganese and Their Relevant Antioxidant Enzymes in Plasma of Grazing Pregnant Ewes during Dry Season

The plasma levels of copper (Cu), zinc (Zn), manganese (Mn) and selenium (Se) were measured in pregnant fat tailed ewes in relation to the activities of the relevant antioxidant enzymes as well as the oxidative status of the animals. Whole blood samples of 47 ewes were taken at the first day of a 51-day breeding period (before pregnancy) and 120 days later (70-120 days of pregnancy). Pregnancy was confirmed in 43 ewes by measuring plasma progesterone in the samples of day 120. For the whole period of the study, the ewes were grazing on medium-to-low quality pastures and cereal stubble and were offered about 1 kg/head/day of a mixture of alfalfa hay (40%) and wheat straw (60%) plus at least 100g barley grain/head/day. A trace mineralized supplement was available free choice. The level of malondialdehyde (MDA; an index of lipid peroxidation) and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) were measured in erythrocytes as well as the concentrations of Cu, Zn, Mn and Se in plasma. In the ewes with confirmed pregnancies the results were compared between days 1 and 120. MDA level increased (P≤0.05) at day 120, revealing the presence of oxidative stress. The activities of SOD and GPX and the concentrations of Cu and Zn decreased (P≤0.05), revealing antioxidant depletion in peripheral blood. Increased metabolic functions of reproductive tissues during pregnancy along with some nutritional insufficiencies could be the underlying reasons of these findings. Fat tailed ewes may experience oxidative stress during pregnancy when they are mainly fed medium to low quality forages. Further investigations are suggested to assess if the correction of such conditions is effective in reducing the proportion of barren ewes and improving the performance of the born lambs.