Young Scholar Presentation: Heat Stress Alleviation in Lactating Sows By Dietary Betaine Supplementation and Cooling Pads

The first objective was to evaluate the effect of dietary betaine supplementation on sow lactation and post-weaning performance during summer conditions. Sows were supplemented with either 0.00 or 0.21% dietary betaine (193 and 175 sows, respectively). Betaine supplemented sows had 3.90% greater average daily feed intake (ADFI) during lactation than control sows (P = 0.005). Treatment by parity interactions were significant for ADFI and BW loss (P < 0.008). Parity 2 betaine supplemented sows had 0.72 kg/d greater ADFI and 6.70 kg less BW loss than parity 2 control sows (P < 0.022). Betaine supplemented sows had greater ADFI on 6-11, 12-16 and 17-21 d periods (P < 0.019). Wean to estrus intervals (WEI) were 0.31 d shorter (P = 0.004) and had different distribution (P = 0.029), for betaine supplemented than control sows. Greater percentages, 3.2 and 12.1% of betaine supplemented sows returned to estrus on d 3 and 4 than control sows. In another lactation trial, sows supplemented with 0.21% dietary betaine had 0.51 mm greater follicle diameter (P = 0.043), and 0.23ºC lower rectal temperature (P = 0.048) than control sows. The second objective was to develop a cooling pad that efficiently removes excess of heat from lactating sows. Cooling pads were built with an aluminum plate surface, high-density polyethylene base, and copper pipes. Respiration rates, rectal, vaginal and skin temperatures for 8 replicates of 10 sows were evaluated after 100 min of cooling with different constant cool water flows of 0.00 (4 sows), 0.25 (2 sows), 0.55 (2 sows) or 0.85 (2 sows) L/min. The cooling was initiated 1 h after the room reached 35ºC. Mean room temperature and relative humidity during the trial were 35.1 ± 0.4ºC and 68.4 ± 3.2%, respectively. The 0.55 and 0.85 L/min treatments reduced respiration rates, rectal, vaginal and skin temperatures after 80 min of cooling (P < 0.001). Respiration rates decreased within 20-40 min for sows on the 0.85 L/min treatment (P < 0.001). Overall heat removal during the trial was 193, 321 and 365 watts for the 0.25, 0.55 and 0.85 L/min treatments, respectively (P < 0.001). Betaine supplementation can alleviate some of the heat stress effects in lactating sows. Cooling pads have a greater potential than betaine to reduce heat stress in lactating sows. Initial data indicate that pulsing of cooled water results in more efficient heat transfer per L of water.