PREFERENCE AMONG COOLING SYSTEMS BY GILTS UNDER HEAT-STRESS

A preference experiment was conducted to compare and evaluate the use of three cooling systems by mature gilts. Systems evaluated were snout coolers (S), drip coolers (D), and conductive cool pads (P). Preferen ce for cooling system and pen position were continuously monitored and evaluated during daily heat stress conditions (34.2 +/- 2.8 degrees C ), nightly warm conditions (26.6 +/- 2.3 degrees C), and for total tim e. The physiological variables of respiration rate (RR) and rectal tem perature (T-r) were measured at three separate times daily. Gilts naiv e to the cooling systems were individually housed in pens with three f ree stalls, each stall containing a different cooling system. After 1 d of warm temperature 127.6 +/- 2.5 degrees C) acclimation, gilts were exposed to 10 h of the heat stress conditions and 14 h of the warm ni ght conditions each day for six consecutive days. Cooling system use w as higher during the hot period (80.2% than during the warm period (66 .2%). The conductive cool pad was preferred over the drip cooler (P < .02) and the snout cooler (P < .0002). The preference for the conducti ve cool pad persisted in the warm period. Cooling system use had a sig nificant effect on T-r and RR (P < .001). The T-r (P < .005) and RR we re lower (P < .005) with the use of the conductive cool pad, whereas t he drip cooler and snout cooler showed no effect on these variables.