Effects of Form of Parenteral or Dietary Selenium Supplementation on Body Weight and Blood, Liver, and Milk Concentrations in Beef Cows

Abstract

In a 365-d study, the effects of form and method of Se supplementation on blood, milk, and tissue Se in grazing beef cows were evaluated. Forty-three Angus cows (115 to 130 d gestation) were randomly assigned to 1 of 5 treatments and received either no Se supplementation (control), one 9-mL barium selenate injection at the initiation of the study, one 5-mL sodium selenite injection + 68IU vitamin E at the initiation of the study and every 4 mo thereafter, or free-choice minerals containing 26 mg/kg Se as sodium selenite or Se yeast. Cows grazed bahiagrass pastures and most calved during early January 2003. Body weight and plasma and liver Se were measured at d 0 and 365. Whole blood and milk samples were taken at calvingand 30, 90, and 205 d postpartum. Cows receiving Se in free-choice minerals were heavier and had a greater increase (P < 0.05) in BW at d 365 than cows receiving all other treatments. Concentrations of Se in plasma and liver were not initially different. At d 365, plasma Se in cows receiving Se yeast was greater (P < 0.05) at 90 μg/L compared with all other treatments. Injectable selenate produced greater plasma Se than control and both the injectable and dietary form of selenite. Liver Se at d 365 was adequate (> 1200 μg/kg) and greater (P < 0.05) in Se yeast-treated cows than in all other treatments. Cows receivinginjectable selenate also had adequate liver Se concentrations that were greater (P < 0.05) than the inadequate levels from control, free-choice selenite, and injectable selenite. Whole blood Se was adequate (> 100 μg/L) for all treatment groups at calving and at 30 and 90 d postpartum. At 205 d post-partum, cows receiving injectable selenate and both free-choice treatments were adequate in whole blood Se, whereas controls and cows receivingin-jectable selenite had inadequate whole blood Se. Cows receiving Se yeast produced greater (P < 0.05) colostrum Se than all others. No differences were observed in milk Se at 30 and 90 d postpartum among treatment groups. At weaning (205 d postpartum), cows receiving Se yeast had at least 2-fold greater (P < 0.05) milk Se than cows on other treatments. Selenium supplementation with organic or inorganic Se via free-choice minerals or injectable selenate maintained adequate Se concentrations in whole blood, plasma, and liver. Inorganic Se was limited in its ability to increase milk Se, whereas Se yeast increased milk Se at parturition and at weaning.