Singaravadivelan Arunasalam, Prasad Ambazamkandi, Balusami Chinnappan, Harikumar Subramaniakaimal, Beena Vakayil, Gleeja Villan Lonappan, Sejian Veerasamy, Vijayakumar Periyasamy, Sachin Patil Bakkesh
College of Veterinary and Animal Sciences, Kerala Veterinary and Animal Sciences University, Mannuthy, Thrissur, Kerala, 680651, India.
Tamil Nadu Veterinary and Animal Sciences University, Chennai, 600051, Tamil Nadu, India.
Trop Anim Health Prod. 2025 Jun 25;57(6):285. doi: 10.1007/s11250-025-04537-x.
Heat stress is a critical challenge affecting livestock productivity and welfare, particularly in tropical climates. Infrared thermography (IRT) has emerged as a non-invasive tool for assessing physiological responses to heat stress. The study aimed to evaluate the heat stress responses in Murrah buffaloes, crossbred cattle, and Vechur cattle using inner canthus infrared thermography as a non-invasive tool under farm conditions in Kerala, India. The experiment was conducted at the Silent Valley Farm Platform, Kerala state, India during February-May 2023, a period of peak thermal stress for dairy animals. Eighteen calves (6-12 months old) were equally assigned to three groups representing each breed/species. Each group consisted of an equal number of male and female calves (three males and three females). Physiological responses (respiratory rate, heart rate using a polar monitor) were assessed in the morning (8:00 AM) and afternoon (2:00 PM). Surface temperatures of inner canthus were captured using an infrared camera (testo 865). The statistical analysis revealed significant differences in heart and respiratory rates between breeds, with crossbred calves exhibiting the highest respiration rate. Breed significantly impacted inner canthus temperatures, highlighting the varying influence of physiological and environmental factors on different breeds. Crossbred calves consistently exhibited the significantly (p < 0.001) highest inner canthus temperature compared to Murrah buffalo and Vechur cattle, both in the morning and afternoon. Murrah buffaloes showed intermediate temperatures, while Vechur cattle had the lowest inner canthus temperatures. The inner canthus surface temperature showed strong positive correlations with respiratory rate and thermal indices, including afternoon THI (r = 0.725, p < 0.001) and average daily THI, indicating its significant role as an indicator of heat stress in livestock. In conclusion, inner canthus infrared thermography effectively differentiated breed-specific thermal responses, supporting its utility as a reliable and non-invasive tool for assessing heat stress in tropical dairy production systems.
热应激是影响家畜生产力和福利的一项关键挑战，在热带气候地区尤为如此。红外热成像技术（IRT）已成为一种用于评估对热应激生理反应的非侵入性工具。本研究旨在利用内眦红外热成像技术作为非侵入性工具，在印度喀拉拉邦的农场条件下，评估摩拉水牛、杂交牛和维丘尔牛对热应激的反应。实验于2023年2月至5月在印度喀拉拉邦的寂静谷农场平台进行，这是奶牛热应激高峰期。18头犊牛（6至12月龄）被平均分配到代表每个品种/物种的三个组中。每组由数量相等的雄性和雌性犊牛组成（3头雄性和3头雌性）。在上午（上午8:00）和下午（下午2:00）评估生理反应（呼吸频率、使用极地监测仪测量心率）。使用红外热像仪（德图865）采集内眦的表面温度。统计分析显示，不同品种之间的心率和呼吸频率存在显著差异，杂交犊牛的呼吸频率最高。品种对内眦温度有显著影响，突出了生理和环境因素对不同品种的不同影响。与摩拉水牛和维丘尔牛相比，杂交犊牛在上午和下午内眦温度始终显著（p < 0.001）最高。摩拉水牛的温度处于中间水平，而维丘尔牛的内眦温度最低。内眦表面温度与呼吸频率和热指数呈强正相关，包括下午的温湿指数（r = 0.725，p < 0.001）和平均每日温湿指数，表明其作为家畜热应激指标的重要作用。总之，内眦红外热成像技术有效地区分了品种特异性热反应，支持其作为评估热带奶牛生产系统热应激的可靠且非侵入性工具的实用性。
