Selenium Content in Single Cell Proteins and Selenium Deficiency in Chicks fed them as a Sole Protein Source

Abstract

Selenium content in 21 single cell proteins of various species grown on various carbon sources with and without supplemental selenium in the culture media was determined and compared with that in two kinds of brewer's yeast.Single cell proteins with selenium content less than 0.03ppm resulted in exudative diathesis of chicks in 5 weeks, when fed as a sole protein source in semi-purified diet. Supplementation of selenium as sodium selenite to the diets at the level of 0.5ppm prevented exudative diathesis completely. Two kinds of brewer's yeast and an yeast grown on methanol with supplemental selenium contained 0.18, 0.17 and 0.30ppm of selenium, respectively, which produced no exudative diathesis of chicks. A yeast grown on methanol, of which selenium level was below sensitivity limit of selenium determination, i.e., 0.01ppm, produced neither exudative diathesis nor encephalomalacia of chicks, when fed as a protein source of natural-type diet composed mainly of yellow corn and defatted rice bran.Biologically active selenium content in yeast grown on methanol increased with supplementation of selenium in the culture media, although clear-cut linear relationship between selenium contents in the media and in the yeast was not observed.It is concluded that selenium content in single cell protein is related to the selenium level in the culture media, and that selenium deficiency symptoms of chicks are only observed when selenium-deficient single cell protein is given to chicks as sole protein and selenium sources in semi-purified diet.