Dietary effects on selenite toxicity in the chick.

The toxicity of Na2SeO3 in diets containing torula (TY) or brewers' yeast (BY) compared to a corn-soy (CS) diet was investigated. Chick mortality caused by feeding 50 or 75 ppm Se as Na2SeO3 was significantly less with TY diets than with either BY or CS diets. The TY diet was also effective in reducing the depressing effect of Se on feed consumption and weight gain. Chicks fed 50 ppm Se in the TY diet accumulated the least amounts of Se in their livers and had only moderate hepatocellular fatty metamorphosis, whereas, those fed the same level of Se in BY diet accumulated the greater levels of Se and showed severe fatty metamorphosis. Partial or total replacement of TY (11%) with BY in the diet significantly increased mortality due to Se toxicity. Some protection against Se toxicity was associated with the ash fraction of TY. This may indicate that the protective effect of TY against Na2SeO3 toxicity is due at least in part to its mineral content.