Estimation of the relative bioavailability of inorganic selenium sources for poultry. 1. Effect of time and high dietary selenium on tissue selenium uptake

An experiment was conducted with male broiler-type chicks to study the effect of time and high dietary Se concentration on tissue Se uptake. A basal corn-soybean meal diet (.2 mg/kg Se, DM basis) was supplemented with 0, 3, 6, or 9 mg/kg Se (as-fed basis) as Na2SeO3 and fed ad libitum for 1, 2, or 3 wk. No toxic effect of Se was observed as expressed by mortality; however, there was a reduction in daily feed intake (P less than .01) at 6 and 9 mg/kg added Se, particularly at 3 wk, suggesting developing toxicosis. Selenium concentration in all tissues studied increased linearly (P less than .001) as dietary Se increased, especially in kidney and liver. Coefficients of determination and lambda criterion values were greatest in plasma, followed by liver, muscle, and kidney. It appeared that 1 wk would be an adequate length of time for further Se bioavailability studies based on tissue Se uptake from diets containing 3 to 9 mg/kg added Se.