부산대학교 도서관

The first objective was to evaluate the effect of dietary betaine supplementation on sow lactation and postweaning 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 ADFI during lactation than control sows (P= 0.005). Treatment × 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 in the 6- to 11-d, 12- to 16-d, and 17- to 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 sows than for control sows. Greater percentages, 3.2 and 12.1% of betaine-supplemented sows, returned to estrus on d 3 and 4, respectively, 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 0.23°C 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 and 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 L/min (2 sows). The cooling was initiated 1 h after the room reached 35°C. Mean room temperature and relative humidity during the trial were 35.1 ± 0.4°C and 68.4 ± 3.2%, respectively. The 0.55 and 0.85 L/min treatments reduced respiration rates and rectal, vaginal, and skin temperatures after 80 min of cooling (P< 0.001). Respiration rates decreased within 20 to 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 W 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 liter of water.