Responses of Thyroid Hormones of Market-Size Broilers to Thermoneutral Constant and Warm Cyclic Temperatures

• DOI: 10.1093/ps/85.9.1520
• Publication Date: 2014-02-18T19:23:38Z
• Authors: X. Tao; Z.Y. Zhang; H. Dong; H. Zhang; H. Xin
• Keywords: Constant (computer programming)

This study characterizes the responses, particularly diurnal variations, of thyroid hormones (TH) [3,5,3′-triiodothyronine (T3), thyroxine (T4), and T3:T4 ratio (T3/T4)] Arbor Acres broilers to constant thermoneutral (TN) or warm cyclic (WC) temperatures. There existed distinct circadian variations—2 peaks in TH under TN WC conditions. The 2 T3, T4, T3/T4 occurred, respectively, at 0 16 h, 8 12 h condition; but 4 During a 5-d heat exposure (HE) regimens, T3 T4 showed continual decrease. daily mean declined significantly (P < 0.05) on first day HE, whereas significant decrease occurred second HE. was no change during same HE period. Hence, results indicate that provides better stress indicator than T4. nature variations makes it necessary collect blood samples more once day, e.g., 6 times 0, 4, 8, 12, 16, 20 ensure full evaluation hormonal responses market-size undergoing thermal challenges.