Selenium in livestock production: a review.

A review of the literature concerning the role of selenium in livestock is presented. Selenium was originally known for its toxicity but in 1957 it was discovered that supplementation of this element prevented liver necrosis in rats. The occurrence of selenium in soils and uptake by plants is discussed, as well as the biochemistry, metabolism, interactions with other elements and nutrients, known functions, requirements of livestock and its toxicity.