Evaluation of floor cooling on lactating sows under mild and moderate heat stress1

The effectiveness of sow cooling pads during lactation was evaluated under mild and moderate heat stress conditions. The moderate heat stress room was targeted to achieve 32°C from 0800 to 1600 h and 27°C for the rest of the day. The mild heat stress room was targeted to achieve 27 and 22°C for the same periods, respectively. Sows received a constant cool water flow of 0.00 (CON, n = 9), 0.25 (LWF, n = 12), or 0.50 (HWF, n = 10) L/min. Respiration rates, rectal temperatures, and skin temperatures were recorded every day (0700 and 1500 h) from the second day in the farrowing room to weaning. The respiration rates of CON sows were 23, 56, 41, and 89 breaths/min, of LWF sows were 21, 24, 29, and 41 breaths/min, and of HWF sows were 18, 20, 24, and 27 breaths/min, and respiration rate increased (P < 0.001) as heat stress increased from mild at 0700 h (22°C), to moderate at 0700 h (27°C), to mild at 1500 h (27°C), and to moderate at 1500 h (32°C). The skin temperatures of LWF sows were 1.1, 0.6, 0.8, and 0.4°C less and of HWF sows were 1.7, 0.7, 1.1, and 1.0°C less (P < 0.01) than CON sows for the same heat stress conditions. The rectal temperatures of LWF sows were 0.02, 0.20, 0.11, and 0.58°C less and of HWF sows were 0.04, 0.22, 0.02, and 0.57°C less (P < 0.05) for the same 4 treatments. The sow cooling pads reduced the effect of heat stress.