Antioxidant and selenium status of laying hens fed with diets supplemented with selenite or Se-yeast

The experiment was designed to investigate the effects of feed supplementation with selenite or selenized yeast on parameters of antioxidant and selenium status of laying hens. Hens of laying breed Shaver Starcross 288 were randomly divided at the day of hatching into 4 groups and fed for 9 months on diets which differed only in amounts or forms of selenium supplemented. Group 1 was fed the basal diet (BD) with native Se content 0.1 mg·kg^-1 DM. Groups 2 and 3 were fed the BD diets supplemented with equivalent Se dose 0.4 mg·kg^-1 DM of either sodium selenite or Se-yeast, respectively. The diet for group 4 was supplemented with Se-yeast at Se dose 0.9 mg·kg^-1 DM. The activities of glutathione peroxidase (GPx) in blood and tissues of liver, kidney and duodenal mucosa were significantly increased by Se supplementation, but no differences due to form or dose of Se were observed. Both Se sources resulted in significant reduction of superoxide dismutase (SOD) activity in erythrocytes. Malondialdehyde (MDA) content in kidney tissue was reduced by both Se sources, but its production in liver tissue was inhibited by Se-yeast only. Selenium supplementation did not influence the levels of MDA and -SH groups in plasma. Although both Se significantly raised Se concentrations in blood and tissues of liver, kidney, spleen, hearth and duodenal mucosa, significant Se deposition into muscles appeared in hens given Se-yeast only. The presented results suggest that Se-yeast is more effective in maintenance of antioxidant and selenium status of laying hens than selenite.