Effects of vitamin E and selenium on thyroid status, adrenocorticotropin hormone, and blood serum metabolite and mineral concentrations of Japanese quails reared under heat stress (34°C)

This study was conducted to determine the effects of vitamin E and selenium (Se) on triiodothyronine (T3), thyroxine (T4), thyroid stimulating hormone (TSH), adrenocorticotropin hormone (ACTH), and serum glucose, urea, triglyceride, cholesterol, Ca, P, Na, and K concentrations of Japanese quails reared under heat stress (34°C). One-hundred twenty 10-day-old Japanese quails were randomly assigned to four treatment groups with three replicates of 10 birds each. The birds with a 2 × 2 factorial design received either two levels of vitamin E (125 and 250 mg/kg of diet) or two levels of selenium (0.1 and 0.2 mg/kg of diet). Greater dietary vitamin E and selenium inclusions resulted in a greater (P = 0.001) serum T3, T4, and TSH, but lower (P = 0.001) ACTH concentrations. No interactions between vitamin E and selenium were detected (P ≥ 0.11) for serum concentrations of T3, T4, TSH, and ACTH. Serum glucose, urea, triglyceride, and cholesterol concentrations decreased (P = 0.001), whereas protein concentrations increased (P = 0.001) when both dietary vitamin E and selenium increased. Serum albumin concentrations increased (P = 0.001) with greater dietary vitamin E but did not change with dietary selenium (P = 0.16). No interactions on any blood metabolites were detected (P ≥ 0.11). Serum activities of serum glutamic oxalate transaminase and serum glutamic pyruvate transaminase were not influenced by dietary vitamin E or selenium (P ≥ 0.42). However, serum activity of alkaline phosphatase increased (P = 0.001) with both increasing dietary vitamin E and selenium. There were no interactions detected for the serum enzyme activities (P ≥ 0.09). Increasing both dietary vitamin E and selenium caused an increase in serum concentrations of Ca, P, and K (P = 0.001), but a decrease in serum concentrations of Na (P = 0.001). No interactions were detected for serum mineral concentrations (P ≥ 0.07) except for P (P = 0.001). Results of the present study showed that dietary vitamin E and selenium have synergistic effects, and that supplementing a combination of dietary vitamin E (250 mg) and selenium (0.2 mg) positively influences some blood parameters that may positively influence the performance of Japanese quails under heat stress. J. Trace Elem. Exp. Med. 16:95–104, 2003. © 2003 Wiley-Liss, Inc.