A SURVEY OF WHOLE-BLOOD SELENIUM CONCENTRATIONS OF HORSES IN VIRGINIAAND MARYLAND

A survey was conducted in 7 counties in Virginia and 4 counties in Mar yland to determine relationships among blood selenium concentrations a nd management and dietary factors which significantly affect blood sel enium concentrations. Three-hundred-and-forty-six horses were randomly sampled and a questionnaire of management/husbandry practices was obt ained from each farm included in the study. Blood selenium concentrati ons (+/- sd) for the population surveyed ranged from 0.027 mug/ml to 0 .266 mug/ml with a mean of 0.125 +/- 0.043 mug/ml. Factors significant ly affecting blood selenium concentration included feeding supplements , origin of hay and amount of time spent on pasture. There was also ev idence that level of exercise and gender of the horse may contribute t o differences in blood selenium concentrations.