Selenium supplementation and concentrations of selenium in cattle tissues and fluids

Abstract

An experiment was conducted for 22 months to determine Se status of grazing Brahman cows and their calves as affected by Se supplementation and season of the year. The three treatments administered to grazing cows for 120 days (November to March), either orally in a concentrate mixture or yearly injection intramusculary, were: 1) control (no Se), 2) control + .25 ppm Se + Intramuscular injection of 5 mg Se plus 1,500 mg vitamin E, and 3) control + .25 ppm Se. Soils, forages and animal tissues were collected six times during the 22-month experiment. Two collections were in the winter season, and four were in the grazing (spring-fall) season. Animal tissues collected were liver, hair, serum colostrum and milk from 36 cows and serum from their calves. The most consistent finding was low Se concentration of soils and pastures which were reflected in low Se concentrations in serum, liver, hair and feces. Both supplemental dietary Se and dietary plus injectable Se-vitamin-E resulted in higher Se tissue levels. Cows fed supplemental dietary and dietary plus injected Se and vitamin E had more Se in both colostrum and milk than that from cows fed no supplemental Se. Likewise, blood Se concentration of calves from Se supplemented cows was higher than controls. Low tissue and dietary Se concentrations found in this study plus the persistent reports of white-muscle disease in the state of Florida, emphasize the need for increasing intake of Se.