Abstract
Although to date no occurrences of white muscle disease have been reported, instances of herd infertility in cattle and in sheep are fairly common. Samples of pasture were collected from most parts of Uganda and examined for selenium. Of these Samples, 20 per cent contained less than 0·05 p.p.m. selenium and about half contained less than 0·l p.p.m. Samples from sites on soils derived from the few sedimentary rocks found in Uganda all contained well above the critical level of selenium. On one farm, closely examined, variations in pasture selenium content were found both with respect to position on a slope and to seasonal rainfall. The two legumes, Centrosema pubescens and Stylosantltes gracilis, contained less selenium than the grasses, especially when the level of selenium was much above average.
