CASE STUDY: Tissue and Blood Selenium Concentrations and Performance of Beef Calves from Dams Receiving Different Forms of Selenium Supplementation12

The objective of this experiment was to evaluate effects of different sources and forms of supplemental Se for beef cows on Se concentrations in their calves. Forty-three Angus cows, 115 to 130 d of gestation, were randomly assigned to receive no Se supplementation (control), one 9-mL injection of barium selenate, a 5-mL injection of sodium selenite every 4 mo, or free-choice minerals containing 26 mg of Se/kg as sodium selenite or Se yeast in addition to pasture. Blood Se was determined at 0 (birth), 30, 90, and 205 d of age. Liver biopsy was performed on all calves at d 205. At birth, blood Se was adequate (>100 μg of Se/L) for all treatments. At d 30 and 90, control, both injectable products, and free-choice selenite treatments produced blood Se in or near adequacy (mean = 82 μg of Se/L), and Se yeast increased blood Se well above adequate at 166 and 182 μg of Se/L for d 30 and d 90, respectively. At 180 d, blood Se concentrations for calves of dams subject to control and injectable treatments were deficient (<50 μg of Se/L), calves from dams on the free-choice selenite treatment were marginal (<75 μg of Se/L), and calves from dams on Se yeast had blood Se above adequate at 188 μg of Se/L. Most calves had inadequate (<1200 μg of Se/kg of DM) liver Se at weaning (range = 297 to 1321 μg of Se/kg of DM), and calves from dams on both free-choice treatments had liver Se concentrations greater (P<0.05) than those of calves from dams treated with injectables or the control dams. Supplementation of Se yeast to cows produced adequate calf blood Se throughout this experiment, whereas control and other treatments produced calf blood Se concentrations that were mostly marginal or deficient after d 30.