Infra-red thermography and behavioural observations for non-invasive monitoring of heat stress in Italian Alpine dairy goats

This study investigated the physiological and behavioural responses of seventeen Italian Alpine dairy goats to heat stress (HS) during the peak summer heat of 2023 in Northern Italy. Infra-red thermography (IRT) and behavioural observations were used as non-invasive monitoring tools. The goats were monitored indoors and outdoors for six days. Temperature-Humidity Index (THI) was calculated, and superficial skin temperatures (SSTs) were measured at multiple body regions using IRT. A clinical examination of the goats was performed in the morning, and behavioural observations were extrapolated from video recordings. Correlation, multivariate, and regression analyses assessed the associations between THI, SSTs, clinical parameters, and behaviours. All SSTs positively correlated with goats’ rectal temperature (p < 0.05), suggesting the validity of the IRT. The results showed that SSTs increased significantly with THI measured indoors (all p < 0.001), supporting the hoof, loin, and flank regions as potential thermal windows for detecting HS. Under higher THI, the goats spent more time in sternal recumbency (p < 0.01) and reduced their rumination time (p < 0.001) indoors. Outdoors, as the THI increased, the goats increased their respiratory rate and SST, and exhibited more shade-seeking and inactivity, while reducing their nutritional behaviours (all p < 0.001). These adaptive responses were consistent with established thermoregulatory mechanisms. Overall, this study suggests that combining IRT with physiological and behavioural observations provides a comprehensive and non-invasive approach to assessing heat stress in goats. Integrating these indicators could improve the detection of HS and the development of management strategies to safeguard goat welfare in a Mediterranean climate increasingly affected by global warming.