Incorporation of Selenium into Egg Proteins After Feeding Selenomethionine or Sodium Selenite

Abstract

An experiment was conducted to determine if selenium incorporation into egg proteins could be predicted on the basis of methionine or cystine content. Chickens in egg production were fed a basal diet or the basal diet supplemented with .2 or .4 ppm selenium from selenite or .2 or .4 ppm selenium from selenomethionine. Eggs were collected from each group after feeding the diet 18 days. All of the egg white proteins and yolk fractions prepared contained selenium, and all of them increased in selenium when more was fed. The increase in selenium in egg white proteins after feeding selenite did not appear to be related to the cystine content of the proteins. However, the increase in selenium in egg white proteins after feeding selenomethionine appeared to parallel the methionine content of the proteins. The selenium level of yolk fractions was more closely related to the cystine content. Livetin fractions had the highest selenium level, and low density fractions had the lowest. The data suggest that proteins synthesized in a tissue will have predictable amounts of selenium but that proteins from different tissues will have different patterns of selenium incorporation.