AN EVALUATION OF A CONTROLLED-RELEASE SYSTEM FOR SELENIUM IN LAMBS

The efficacy of 100-day controlled release anthelmintic capsules conta ining Se for increasing and maintaining the Se status of lambs was eva luated. Capsules containing either 7.7 or 13.9 mg of Se increased the mean blood Se concentrations from 150 +/- 8.4 nmol/l in the unsuppleme nted lambs to 440 +/- 29.8 and 990 +/- 83.4 nmol/l respectively 100 da ys after their administration. Blood Se concentrations then declined t o 250 +/- 21.5 and 380 +/- 50.1 nmol/l respectively by day 210. The ad dition of 13.9 mg of Se to a 100-day controlled release anthelmintic c apsule is an effective method of protecting lambs from Se deficiency f or at least 180 days.