Unravelling bio-climatic thermal stress driven behavioral pattern shifts in crossbred pigs

Pigs are highly susceptible to heat stress and their performance affects sustainability of the pig farming sector. It is therefore, essential to understand their behavior in different climatic conditions. In this work, 24 Landlly crossbred pigs in grower stage with uniform body weight were selected and randomly divided into two groups (heat stress [HS] and heat stress alleviated [HSA]). The HSA group was supplemented with a sensor-based cooling system to minimize heat stress. Major micro-climatic variables viz., ambient temperature (AT), relative humidity (RH %) and temperature humidity index (THI) were recorded twice daily in both pens. Mean AT, RH and THI around the micro-climate were 29.6 ± 0.15 °C, 72.4 ± 0.19 % and 80 ± 0.24, respectively. The lying, sitting, standing, feeding, drinking, and agonistic behavior were recorded daily for 90 days (June, July, August 2023) using 2 fixed Axis M1065 IP cameras. Ethogram was prepared for each behavior individually after segregating the recording from 0900 to 1700 h where maximum AT, RH and THI variations were experienced. Significant increase in the duration of lateral lying, water trough access, walking and standing posture (p < 0.01) were observed in heat stressed pigs. Average feed intake time per animal increased by ∼15 % than normal. During extreme periods of heat, time spend for sternal lying and sitting was significantly lower by 55 % and 25 %, respectively (p < 0.01). Additionally, high incidence of tail biting and agonistic behaviors (p < 0.01) were observed in the HS group. Variation within groups revealed that harsh effects of heat stress in pigs were more evident during the hot-dry period.