EFFECT OF SELENIUM AND A-TOCOPHEROL SUPPLEMENTATION ON POSTPARTUM REPRODUCTIVE FUNCTION OF DAIRY HEIFERS AT PASTURE

The objective of this study was to investigate the effects of selenium (Se) and alpha-tocopherol supplementation on uterine involution and o varian function in dairy heifers fed a prepartum diet containing low c oncentrations of Se and alpha-tocopherol. Twenty-four pregnant Friesia n heifers were randomly allocated to one of four experimental groups i n a 2 x 2 design balanced for age and body weight. Prepartum treatment s consisted of supplementation with either 2 intraruminal Se pellets o r 3600 mg of alpha-tocopherol po 4 times per wk, or both. Control anim als received no supplementation. For 8 wk before calving, the heifers were fed exclusively on pasture hay which contained less than 10 mu g/ kg of Se and 19 mg/kg of alpha-tocopherol. After calving, the heifers grazed perennial ryegrass and white clover pasture. Concentrations of Se and alpha-tocopherol in serum for the prepartum heifers of the cont rol group were 10 ng/ml and 1.3 mu g/ml, respectively, indicating defi ciencies of these nutrients. Treatment with Se and alpha-tocopherol in creased prepartum serum concentrations of Se and alpha-tocopherol to 7 4 ng/ml and 5 mu g/ml, respectively (P < 0.001). However, treatment wi th Se, alpha-tocopherol, or both, failed to enhance uterine involution , hasten resumption of postpartum ovarian activity or reduce the incid ence of clinical postpartum abnormalities. These findings suggest that postpartum reproductive dysfunction is not a primary feature of moder ate Se or vitamin E deficiency of cattle at pasture.