Comparative assessment of thermoadaptability in Murrah buffalo, crossbred, and Vechur cattle using heat tolerance indices under controlled climate conditions

Abstract

The increasing frequency and intensity of heat stress events due to climate change pose a significant challenge to livestock productivity and welfare, particularly in tropical regions. This study aimed to evaluate the thermoadaptability of Murrah buffalo, crossbred cattle, and Vechur cattle under controlled heat stress conditions using two heat tolerance indices: the Iberia Heat Tolerance Index (IHTI) and the Benezara Coefficient of Adaptability (BCA). Eighteen calves (N=6 per breed) were exposed to 42°C and 50-55% relative humidity for 6 hours daily over 21 days in a climate-controlled chamber. Physiological parameters Rectal Temperature (RT), Respiration Rate (RR), and Heart Rate (HR) were recorded before and after exposure on days 0, 7, 14, and 21. The Iberia Heat Tolerance Index (IHTI) and Benezara Coefficient of Adaptability (BCA) were calculated to quantify thermal tolerance. Results revealed significant differences in RT and RR among breeds post-exposure (p