Acute heat stress compromises the physiology of growing pigs

Twenty-four castrated male pigs were used to determine the effect of ambient temperature on thermoregulatory responses during an acute heat stress test conducted for 48 hours. The animals were housed in two climatic chambers with controlled temperature, humidity and ventilation. The animals were maintained in thermal comfort for the category (22ºC) in one of the chambers, and in the other, under heat stress (34ºC). Twelve pigs were housed in each chamber, with the experimental unit composed of two animals in the stall, totaling six replicates. The environmental conditions of the climatic chambers and physiological parameters of respiratory rate and rectal and surface temperature were monitored at the beginning of the experiment and every 12 hours during the experimental period. Growing pigs presented effective thermoregulatory responses beginning at 12 hours under acute heat stress (34°C).