Influence of different dietary vitamin E supplementation on some plasma components and egg production of laying Japanese quails during heat stress

The experiment was conducted to evaluate the effects of vitamin E (dl-a-tocopherol acetate) supplementation at various concentrations (0-control-, 250, 500, 750 mg/kg of diet) on the feed intake, egg production, plasma enzymes, electrolytes and metabolites of laying quails (Coturnix coturnix japonica) exposed to chronic heat stress at a mean temperature of 31°C from 13 to 17 weeks of age. The quails were randomly assigned to 4 treatment groups, 3 replicates of 15 birds each. Body weight, feed intake and egg production were not affected by vitamin E supplementation. Plasma total cholesterol, total protein, alkaline phosphatase (ALP), blood urea nitrogen (BUN), inorganic P and Mg concentrations did not differ among the groups. Plasma creatinine was higher in the 750 mg/kg vitamin E supplemented group than in other vitamin E supplemented groups. Plasma glucose concentrations decreased as dietary vitamin E increased up to 500 mg/kg of the diet. A higher glucose concentration and activity of glutamic-oxaloacetic transaminase (GOT) were stated in the control group. Triglyceride concentration was the highest whereas albumin and Ca concentrations were higher in the control group than for the 250 and 750 mg/kg vitamin E supplemented groups. Plasma glutamic pyruvic transaminase (GPT) activity was the lowest in control group. These results indicate that the supplementation of 500 mg vitamin E/kg to the diet may offer a potential protective management practice for preventing heat stress-related damages in laying quails.