Studies with the intraruminal selenium pellet. 1. Some factors influencing the effectiveness of the pellet for selenium supplementation of sheep

Abstract

A number of experiments were conducted to determine whether surface coatings on pellets, season of treatment, or age of sheep affected the efficacy of intraruminal selenium pellets, as measured by selenium status of the recipient sheep. Also, comparisons were made between pellets and oral drenches of sodium selenate, and between three brands of commercially available pellets. Plasma selenium concentration reached a maximum within 2 weeks of administration of either pellets or oral drenches. Thereafter concentrations declined rapidly, but with all three brands of commercial pellet examined, sheep would have been protected from white muscle disease for at least one year. There were, however, differences between brands; one brand of pellet maintained the sheep at a higher selenium status than the other two. Surface coating, season of treatment, and age of sheep had only minor effects on pellet efficacy.