Selenium – The critical performance component
By J.A. Davidson, P.Ag., PAS
The importance of selenium in the nutrition of livestock and poultry has been recognized since 1957 when it was first identified as an essential micronutrient. It was in the early 1970s that supplementation of animal diets with either sodium selenite or selenate became an accepted practice worldwide.
Selenium is a metalloid with chemical properties similar to sulphur and was first discovered in 1818 by J.J. Berzelius, in Sweden. It is estimated that worldwide, selenium has an average concentration of only 0.05 mg/kg in the soil. The amount of selenium present in soil for absorption by plants is directly related to the amount of selenium in the rock that weathered to form the soil.