Reduction of hepatic lipid deposition in laying hens by dietary selenium-yeast interaction

Experiments were conducted to study the effect of chromiun and selenium on liver lipid deposition and incidence of liver hemorrhage in caged layers. Commercial strains of layers were fed ad libitum equicaloric and isonitrogenous diets. Corn-torula dried yeast diets containing added selenium (.1 microgram/g) with or without supplementary chromium (10 microgram/g) significantly reduced total liver lipid and liver hemorrhage. The effects of protein source (soybean meal vs. yeast) and selenium were separated in a factorial experiment which showed that the hepatic lipid response to selenium results from an interaction of selenium with an unidentified factor in torula yeast. The addition of selenium to diets with each protein source significantly elevated glutathione peroxidase (GSHPx) activity. Inclusion of 5% brewers yeast in the corn-soy diet or vitamin E (50 IU/kg) to the corn-torula dried yeast reduced liver lipid similar to that seen in birds fed the torula-yeast diet containing .1 microgram Se/g. Comparison of oral glucose tolerance of birds fed corn-soy and corn-soy brewers yeast diets showed no significant difference. None of the dietary treatments significantly altered body weight, egg production, egg weight, or feed consumption. The results indicate that the metabolic role of selenium in relation to its role in hepatic lipid metabolism is mediated through an interaction with a dietary factor(s) present in yeast.