A survey was conducted in Southwestern, Punjab, Pakistan during two different seasons to assess the status of selenium of three different classes of grazing sheep. Blood plasma from lactating, non-lactating and male sheep were collected four times monthly in winter and summer seasons and analyzed for selenium concentration. Seasonal variations were found for plasma selenium concentration. Selenium concentration of plasma was higher in male sheep than those lactating and non lactating ewes during both the seasons as well as it were higher compared to the established critical value for blood plasma selenium for these ruminants. High incidence of deficiencies was found particularly for lactating ewes. These deficiencies in plasma selenium based on critical level were 35 to 15 % for lactating, 28 to 12% for non lactating ewes and 15 to 5 % for male animals during winter and summer seasons, respectively. Although some differences among the three classes of sheep were found for selenium concentrations of blood plasma, but dramatic class differences could not be concluded based on this study. It was suggested based on the results obtained, pellets, glass bolus or mixture that contain selenium, should be used for supplementation for grazing sheep in the study area to maintain the plasma Se at optimum required level for the prevention of complication in livestock caused due to deficiency of this element.
Selenium, Grazing sheep, Soil, Forage, Plasma