EFFECT OF DIETARY PHYTATE ON GROWTH AND SELENIUM STATUS OF CHICKS FEDSELENITE OR SELENOMETHIONINE

1. An experiment was conducted to study the effect of dietary phytate on the selenium status of chicks fed on a semi-purified diet with or w ithout supplements of sodium selenite or selenomethionine (200 mu g Se lenium/kg). 2. Assessment included measurement of growth and activity of glutathione peroxidase (GSHPx) (EC.1.11.1.9), an enzyme that limits damage by free radical species arising from oxygen metabolism by cata lysing the reduction of hydrogen peroxide and lipid hydroperoxides. In addition, information was obtained on forms of selenium in blood, liv er, kidney, heart and muscle, distinguishing between selenide-Se, redu cible-Se and non-reducible-Se. 3. Phytate caused significant reduction s in growth, food consumption and food conversion efficiency. Suppleme ntary selenium was without effect on growth but significantly increase d GSHPx activity in all tissues. Phytate also increased GSHPx activity in blood and heart, and in muscle in the absence of supplementary sel enium, but decreased the activity in kidney. 4. Concentrations of all forms of tissue selenium were significantly increased by supplementary selenium. In general, there was greater deposition from selenomethion ine than from selenite and most was in non-reducible form. 5. Phytate increased selenium in all tissues except muscle; it is not clear if th is resulted from increased absorption or increased retention. It incre ased reducible-Se in blood, liver and heart and non-reducible-Se in bl ood and kidney. Tissue concentrations of selenide-Se were highly varia ble: presence or absence of or absence of phytate contributed to some significant interactions. 6. The results suggest that there is a posit ive relationship between phytate and selenium status in chicks, in con trast to its negative effect on growth.