The efficacy of vitamin E (DL-alpha-tocopheryl acetate) supplementation inhen diets to alleviate egg quality deterioration associated with high temperature exposure

Supplementation of hen diets with vitamin E was investigated as a means to alleviate egg quality deterioration associated with high temperature exposu re. One hundred eighty layers (60 birds/diet) were randomly placed on diets supplemented with vitamin E at 20, 60, and 120 IU/kg feed. After 2 wk on f eed, one-half of the birds were maintained at environmental temperatures of 21 C, whereas the other half were acclimated over 3 d to increasing enviro nmental temperatures reaching 34 C. Birds were exposed to 21 or 34 C for 2 wk (five hens per cage x six replications). Egg production, feed intake, an d egg weights were determined daily. Twenty eggs were collected from each t reatment group and analyzed for vitamin E content in yolk, percentage egg s olids, yolk color, yolk pH, albumen pH, foaming ability of albumen proteins , emulsification capacity of yolk, yolk viscosity, yolk color, and vitellin e membrane strength (VMS). Results suggested that high temperature exposure (HTE) caused a reduction in feed intake, egg production, Haugh units, egg weights, VMS, yolk and albumen solids, foam stability, angel cake volume, y olk color, and emulsification capacity. Supplementation of HTE lion diets w ith 60 IU vitamin E/kg feed improved feed intake, egg production, VMS, yolk and albumen solids, foam stability, and angel cake volume. However, egg we ight, emulsification capacity, yolk color, yolk index, and yolk viscosity w ere not improved by vitamin E supplementation of HTE hens. Vitamin E levels in the yolk were lower from HTE hens compared with controls at all levels of vitamin E supplementation.