The effects of vitamin E on the antioxidant system, egg production, and egg quality in heat stressed laying hens.

摘要

150 Leghorn laying hens were divided to two groups and subjected to similar environmental conditions. Diets were based on standard layer rations with 30, 80, or 105 mg vitamin E/kg. All birds were kept in 45% relative humidity (RH) and at room temperature (21 degrees C) for 3 weeks adaptation period. In the fourth week, the temperature and RH were increased to 35 degrees C and 65%, respectively, in the experimental group. Blood samples were collected from both groups before, during and after exposure to heat stress. Vitamin E analyses were determined by HPLC and biochemical parameters were analysed using spectrophotometry. Results revealed that the levels of plasma malondialdehyde (MDA), erythrocyte MDA, glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD), and egg yolk MDA concentration significantly increased (P<=0.05), while the plasma vitamin E decreased in the experimental group during heat stress. Egg quality also decreased in the experimental group during heat stress. Dietary supplementation with higher levels of vitamin E alleviated some of the metabolic consequences of heat stress. It is suggested that vitamin E supplementation has no beneficial effect on egg production during heat stress.