CHANGES IN PLASMA ALPHA-TOCOPHEROL AND SELENIUM OF GESTATING COWS FEDHAY OR SILAGE

The effects of dietary hay or silage on plasma alpha-tocopherol and Se concentrations during late gestation and early lactation were studied using 40 crossbred pregnant cows and their calves. Cows received sole ly either timothy hay or grass silage forage from midgestation to earl y lactation and 21 d prior to estimated calving were or were not injec ted with Se (30 mg) and alpha-tocopherol (3000 IU). Five blood samples were collected for determination of concentrations of alpha-tocophero l and Se twice during late gestation and three times after calving. Bl ood samples from calves were collected at birth and at 10 and 30 d of age. Serum concentrations of alpha-tocopherol were low at birth for bo th groups of calves and ranged from .83 to 1.08 mug/ml of plasma. Hay had less alpha-tocopherol than silage (15 vs. 35 ppm in the DM). Cows fed silage had significantly higher plasma alpha-tocopherol concentrat ions (3.41 mug/ml) than cows fed hay (2.25 mug/ml). Cows given one sub cutaneous injection of Se plus alpha-tocopherol preparation had signif icantly higher Se concentration in plasma (30 ng/ml) than did cows in the control group (17 ng/ml). The Se concentration in the placenta of cows that were injected with the Se preparation was significantly high er (64 ppm) than that in the control (47 ppm). Plasma Se concentration of calves at birth was correlated significantly with that of dams soo n after parturition.