Biological Availability of Selenium in Feedstuffs and Selenium Compounds for Prevention of Exudative Diathesis in Chicks

Abstract

The biological availability of selenium in feedstuffs and selenium compounds for prevention of exudative diathesis (ED) in chicks was studied. Using a casein-soy protein-torula yeast basal diet deficient in both vitamin E and selenium, graded levels of selenium as supplied by sodium selenite, used as a standard, or by the test ingredients were fed for periods of 12–21 days. Selenium in most of the feedstuffs of plant origin was highly available, ranging from 60 to 90%, but was less than 25% available in animal products. High availability values were obtained for sodium selenate and selenocystine, while low values were found for selenoethionine, sodium selenide, selenomethionine and selenopurine. Gray elemental selenium was almost completely unavailable. Protection against ED was highly correlated with plasma glutathione peroxidase activity in chicks fed sodium selenite or selenomethionine, indicating that biological availability was determined by the ability of the chick to utilize the various forms of selenium for enzyme activity.