Effect of higher concentration of dietary vitamin E supplementation on growth, immune competence and antioxidant status in broilers

An experiment was conducted to study the effect of higher levels of vitamin E supplementation on growth, immune competence and antioxidant status in broiler chickens. One hundred and forty four-day old broiler chicks were randomly distributed into 4 dietary groups with 6 replicates of 6 chicks each. They were housed in stainless steel battery brooder cages with raised wire floor under uniform managemental conditions. A basal diet based on maize-soybean meal was formulated. Subsequently, another four test diets were prepared by supplementing vitamin E to contain 10, 30, 150 and 300 IU vitamin E per kg diet. Each diet was fed ad-libitum to 6 replicates of 6 chicks each during the experimental period of 0–6 weeks. The body weight gain was significantly lower in the chicks fed diet containing 10IU vitamin E per kg diet. Increasing the vitamin E supplementation to 30IU per kg diet significantly increased the weight gain; however no further improvement in weight gain could be noticed on higher levels of supplementation (150 or 300 IU per kg diet). The cell mediated immune response as measured by phytohaemaglutinin-P inoculation and humoral immune response against sheep red blood cells injection was significantly higher in the birds fed 150IU vitamin E per kg diet compared to those fed either 10 or 30 IU. The antioxidant parameters such as lipid peroxidase decreased whilst glutathione peroxidase increased linearly with the level of vitamin E supplementation. Lowest and highest concentration of lipid peroxidase and glutathione peroxidase respectively, was observed in the diet containing 300IU vitamin E per kg. From the results of the study, it is concluded that vitamin E requirement for better immunity and antioxidant status is higher than growth.