The effects of various level of vitamin e on the immunity and egg yield of laying hens

This research was carried out in two experiments. In first experiment, four different levels of vitamin E (0. 5, 35 and 70 IU/kg feed) were added the diets based on corn, and the effects of the diets on egg yields, blood vitamin E levels, T-lymphocyte percentage, plasma cell count in spleen and antibody titers against the vaccine of Newcastle disease were investigated for one years. Total of 864 laying hens were used in this experiment. The mean egg yields of the experimental groups were 79.9, 80.6, 77.2 and 79.5% (P>0.05) and feed consumptions for one kg egg were 2.23, 2.23, 2.36 and 2.20 kg (P<0.05). No significant differences among groups found in blood vitamin E levels and histologic and immunologic results. In the second experiment twentyfour chick for each group were supplied by hatching eggs from the hens used in experiment I in order to investigate maternal immunity. Antibody titers were determined at day 2, 7 and 10. At same day, for histologic investigation, blood and some lenfoid tissue samples from spleen, bursa Fabricii, tymus and ileum were taken at same days the effects of different vitamin E levels were not significant on the antibody titers and histologic results.