Effect of anionic salts on selenium metabolism in nonlactating, pregnant dairy cows.

The objective of this trial was to determine whether anionic salts in the diets of nonlactating, pregnant cows for 14 to 21 d prepartum affected measures of Se status. One of three dietary treatments (control, anionic salts, and anionic salts plus Se) was administered to 34 nonlactating, pregnant cows using a completely randomized design with repeated measures. The anionic salts were delivered via gelatin capsules that were administered orally in two equal amounts per day, and the Se (3 mg/d) was administered via an intraruminal bolus. The incidence of milk fever among cows was not significantly different across dietary treatments. The severity of hypocalcemia as indicated by concentrations of ionized Ca in serum collected < 2 h postpartum was significantly lessened by dietary anionic salts. Supplementation of anionic salts to the diet did not significantly affect serum Ca concentrations at either 7 d prepartum or 7 d postpartum. Anionic salts did not affect concentrations of Se in blood; however, Se supplementation of the diets of cows significantly increased postpartum concentrations of Se in serum. No treatment effects were detected for concentrations of Se in either serum or whole blood of newborn calves. In conclusion, these data indicate that diets supplemented with anionic salts for 14 to 21 d prepartum and the supplementation of diets with Se had independent effects on concentrations of minerals in blood. Thus, anionic salts administered to prevent milk fever without danger of significantly reducing the transfer of Se from the dam to the calf and without compromising the Se status of the cow when the anionic salts are limited to administration for 14 to 21 d before calving.