Distribution in the sheep of selenium derived from 75Se-labelled ruminal pellets

Abstract

Dense pellets consisting of elemental iron and selenium (9:1 by weight) labelled with 75Se were introduced into the rumen of two groups of sheep for 1 month prior to slaughter. One group was considered to be in normal selenium status, the other had grazed low selenium pastures for 2 years prior to the experiment and were shown, by analysis of blood selenium levels, to be in low selenium status. During the experimental period the pellets released 0.5-1.3 mg selenium each day; of this, about 30% was excreted in the urine and about 1 % in the expired air. Blood selenium levels rose rapidly during the first week, then more slowly, and finally leveled out at 0.18-0.34 �g/ml. Concentrations of selenium derived from the pellets were determined in various body tissues and organs at slaughter. In the course of the experiments no toxic effects were observed, and the examination of a wide variety of tissues at autopsy indicated that in no case was there excessive accumulation of selenium. The results of these experiments are discussed in relation to the use of these pellets commercially.