We can supply one kind of selenium: sodium selenite
Selenium has a special place among the feed-derived natural antioxidants, being an integral part of selenoproteins participating in the regulation of various physiological processes in the body. A deficiency of selenium in growing chickens causes exudative diathesis. Early signs of usually occur at 3–6 wk of age, depending on the degree of deficiency. Selenium and vitamin E deficiency causes white muscle disease in ruminants and in poultry it causes retarded muscale growth.