SELENIUM BALANCE IN LAYER CHICKENS FED DIETS SUPPLEMENTED WITH SELENIUM FROM INORGANIC OR ORGANIC SOURCES

Abstract

The aim of this study was to compare the effects of feed supplementation with comparable Se doses from sodium selenite (SS) and selenised yeast (Se-yeast) on Se retention, balance and tissue deposition in layer chickens by the balance technique. One-day-old female chickens of the laying strain Isa Brown were randomly allocated to four dietary treatments consisting of basal diet (BD) containing only background Se (0.12 mg/kg dry matter (DM)) and two treatments based on identical BD supplemented with 0.2 mg Se/kg DM either from SS or from Se-yeast. The fourth group of layers fed BD enriched with 0.7 mg Se/kg DM from Se-yeast. After 4 weeks of experiment, no differences in blood Se levels were observed between chickens fed diets supplemented with equivalent doses of SS or Se-yeast, while the 8-week intake of Se-yeast resulted in significantly higher blood Se levels of layers than from SS (0.17 vs. 0.21 mg/L, PË‚0.01). The layers given BD showed significantly the lowest Se level. The daily Se balance was positive in all birds with the highest values in chickens fed larger amount of Se-yeast. The balance measurements carried out in week 4 and 8 showed no differences between groups supplemented with equivalent Se amounts in the selenium balance and Se retention (% of Se ingested), both differing from the control group in week 8 only. The 8-week intake of Se-yeast resulted in significantly higher Se deposition in muscles, heart, gizzard, pancreas, lungs, kidney, Bursa Fabricii and feathers of chickens than that from SS. The highest tissue Se concentrations in all layers were found in the kidney. The layers given diet with larger amount of Se-yeast showed the highest values in the majority tissues. The results demonstrate the better bioavailability of Se-yeast in young layers due to the greater body retention of this essential microelement than from sodium selenite, however the higher Se absorption from digestive tract of birds was as effective as inorganic Se source.