Selenium (Se) is an essential element in the nutrition of poultry, sheep, swine, dairy cattle and beef cattle. It is essential to the antioxidant function of the glutathione peroxidase (GSH-Px) enzyme and is related to complex enzymatic and metabolic functions. The GSH-Px enzyme is essential to cell and tissue protection from damage caused by oxygen resulting from leukocytes during the phagocytosis.
The selenium cycle in the food chain of land animals and humans starts from the soil and includes plant and animal sources ultimately dependent on its absorption from the soil. Soils are the major source of selenium for plants and therefore for animals eating those plants and humans consuming plant and animal-derived foods. Selenium levels vary greatly in different foods as well as in the same foods grown in different areas. Agricultural practises have taken their toll on our lands. Usage of inorganic fertilizers containing sulphur, soil acidification and decreased soil aeration substantially decrease selenium’s availability. There is also inconsistency in the common practice of selenium supplementation of animal diets. On the one hand, naturally occurring organic selenium is represented by a mixture of selenoamino acids with selenomethionine (SeMet) comprising more than 50% of the total selenium in many feed ingredients, including grains and forages. In fact SeMet fulfills the criteria of an essential amino acid. On the other hand, until recently the supplemental form of selenium for farm animals and poultry has been inorganic, either selenite or selenate. Changes in the feed formulation for poultry, sheep, swine, dairy cattle and beef cattle, relating to usage of the most effective organic selenium in diets could be a solution for the global selenium deficiency. Recent approval by the US Food and Drug Administration of organic selenium in the form of selenium-enriched yeast would resolve the discrepancy between natural and supplemental selenium sources.
Lyons et al. (2007) Asian-Aust. J. Anim. Sci. 20(7):1135-1155
Plants absorb inorganic forms of mineral from soil through root hairs. These inorganic minerals are the ideal natural food for plants, but they are not bioavailable to humans in this form.
The mineral combines with water and both are pushed through the plant’s cells in the stems and leaves.
This process transforms the inorganic minerals into ionic forms, which creates a highly bioavailable nutritious form of organic minerals for humans and animals. When animals and humans consume plants the body knows exactly how to use the minerals within these plants for vital bodily processes.