Comparative evaluation of cooling systems for farrowing sows

The field studies reported here compare the performance of three cooling sq stems for relieving farrowing/lactating sows of heat stress under the warm and humid production climate in southern China. The comparative systems in cluded (1) tunnel ventilation (TV) with vertical head-zone ventilation (HZV ) vs. TV with HZV and drip cooling (DC), (2) TV only vs. TV with DC, and (3 ) horizontal air mixing (HAM) only vs. HAM and DC. For the HZV, a perforate d overhead air duct was used to create an air velocity of 0.6 to 0.8 m/s (1 18 to 157 ft/min) in the head zone of the sow. The paired tests were conduc ted successively in an experimental commercial farrowing barn housing 42 so ws. Body temperature (T-b) and respiration rate (RR) of the sows were used to evaluate the efficacy of the systems. The results indicate that sows und er TV + DC or TV + HZV + DC had significantly lower T-b than those under TV only or TV + HZV(P < 0.01 and P < 0.001, respectively). DC under HAM was l ess effective for T-b reduction (P > 0.05). DC reduced RR in all cases, 42% under TV (P < 0.01), 41% under TV + HZV(P < 0.01), and 22% under HAM (P > 0.05). It was concluded that TV with DC provides rite most cost-effective c ooling scheme.