Seasonal variation in physiological responses, stress and metabolic-related hormones, and oxidative status of Murrah buffaloes

Abstract

Harsh environmental conditions adversely affect the health and productivity of buffaloes. The present study was conducted to investigate the effect of seasonal thermal stress on the physiological responses, oxidative stress and some related hormones in Murrah buffaloes. A significant (p < 0.05) rise was observed in the rectal temperature, respiration rate, pulse rate and superoxide dismutase (SOD) during hot-humid (HH) and hot-dry (HD) seasons compared to thermoneutral (TN) season. Plasma cortisol and malondialdehyde (MDA) levels were low during TN season, intermediate in HD and highest during HH season. Although the levels of plasma triiodothyronine and thyroxine were high during TN season, their levels declined notably during HD and HH seasons. The temperature humidity index had a positive correlation (p < 0.01) with physiological responses, SOD, MDA and plasma cortisol levels. However, it was negatively correlated (p < 0.01) with the concentration of plasma thyroid hormones. The results reveal that buffaloes could cope efficiently with heat stress by reducing the levels of metabolic heat production-related hormones and releasing more antioxidant (SOD). However, they were still showing signs of stress which were reflected by higher levels of cortisol, lipid peroxidation (MDA) and physiological responses. Therefore, promoting health and productivity of buffaloes requires suitable management strategies to alleviate heat stress and provide comfort to them during extreme seasons.