Behavioural Reactions and Physiological Responses of IPB-D1 Chickens under Acute Heat Stress

This study examined the heat stress tolerance of IPB-D1 chickens through physiological responses, behaviour during heat stress tests, body surface temperature, rectal temperature, and changes in corticosterone and triiodothyronine hormone levels.The chickens were raised under two different rearing systems: the intensive system (P0) and the free-range system (P1).A total of 90 chickens were reared in each system for 12 weeks.Heat stress tests were conducted using random sampling, with 15 chickens representing each rearing system, intensive (P0) and free-range (P1).Data were analyzed using an independent T-test.The results showed that behavioural parameters, including the time to start panting, time to start rapid panting, and wing spreading, were significantly higher (P<0.05) in chickens raised in the free-range system.Furthermore, based on delta tests conducted before and after heat stress for each rearing system, body surface temperature in the comb, shank, and spur was significantly lower (P<0.05) in free-range chickens (P1) compared to intensive chickens (P0).Meanwhile, for rectal temperature and changes in corticosterone and triiodothyronine hormone concentrations, both free-range (P1) and intensive (P0) chickens showed similar results.