Cut-off value of body surface temperature and assessing heat stress in dairy cows

Heat stress has a significant impact on the health and productivity of dairy cows, making early and accurate detection essential for effective welfare management. The aim of this study was to determine cut-off values of body surface temperature across different anatomical regions, measured by infrared thermography (IRT), to distinguish cows under heat stress from those in thermoneutral conditions. The research was conducted on a Holstein-Friesian farm in the Vojvodina region, with 200 total measurements collected during spring and summer. The identified cut-off values were as follows: 36.06 °C for the eye, 32.2 °C for the ear, 33.6 °C for the nose, 37.3 °C for the forehead, 35.8 °C for the whole head, 35.1 °C for the abdomen, 36.6 °C for the udder, 32.3 °C for the front limb, 33.5 °C for the hind limb, and 35.95 °C for the whole body. All values demonstrated satisfactory to high discriminative power (AUC = 0.71-0.95) for identifying cows under heat stress. These thresholds enable early identification of thermal load and timely interventions. Although body surface temperature is a sensitive and non-invasive indicator, its application requires contextual interpretation and integration with other physiological parameters. The results support the development of automated systems for continuous monitoring and prevention of heat stress, contributing to more sustainable dairy farming practices under changing climatic conditions.