Evaluation of a long-acting selenium and copper preparation for intraruminal administration to cattle.

An intraruminal, soluble glass bolus containing selenium (Se) and copper (Cu) was evaluated for improving the Se and Cu status of pregnant cows and their calves. In the cows, there was a marked increase in the Se status following treatment with the soluble glass bolus. In the untreated cows, Se concentration in the blood (27-31 ng/g) as well as milk (5.1-6.8 ng/ml) remained low which was indicative of Se-deficiency. In the treated cows, the soluble glass bolus administration produced higher blood and milk Se concentrations, which were increased during the whole experimental period (10 months). In calves born from soluble glass treated cows, blood Se (11-28 ng/ml) and Cu (0.43-0.82 microgram/ml) concentrations were higher (except at birth for Cu) than in those from the untreated cows. Despite these differences, the status of the calves born from the treated cows was still low in both Se and Cu.