Effect of Dietary Vitamin E on the Performance, Plasma and Egg Yolk Vitamin E Levels and Lipid Oxidation of Egg in Heat Stressed Layers

Abstract

This study was conducted to investigate the effects of dietary vitamin E levels on the concentration of vitamin E of egg yolk and plasma, TBARS (thiobarbituric acid reactive substance) of egg yolk during refrigerated storage of 1 or 42 days and productive performance of laying hens exposed to heat stress (30 oC). Twenty four week old, 128 Lohman LSL hybrids layers divided into 8 groups. Half of the groups were kept at normal poultry-house conditions (20 oC) and the other half were exposed to heat stress (30 oC). In both poultry-houses, former groups were fed on basal diets and 2nd, 3rd, and 4th groups were fed on the vitamin added rations which were 45, 65, 85 IU/kg vitamin E respectively. Supplementation of vitamin E caused a very significant increase in the egg yields. Egg production was significantly greater (P<0.01) with 85 IU /kg vitamin E (81%) as compared to control hens. On the other hand the average egg yields were significantly decreased (approximately 14%) by the heat stress. A higher concentration of vitamin E reduced TBARS values in eggs. Concentration of vitamin E in the yolk and plasma linearly increased as the dietary vitamin E increased