P1 sows are more sensitive to heat stress as indicated by their body temperatures and respiration rate they also had higher rectal temperature during lactation than older sows. These trials showed that the thermal response of first-parity sows is different from multiparous sows during heat stress. P1 sows also had a greater increase in respiration rate from the morning to afternoon (55 to 73 breaths/minute) compared with multiparous sows (58 to 66 breaths/minute). Sows in both rooms had similar respiration rates two days before farrowing (Figure 2 69 and 75 breaths/minute, respectively), but sows in FA rooms had a greater respiration rate by late lactation than EC sows (74 vs. In multiparous sows, however, ear temperature only rose from 95.5° F in the morning to 97.2° F in the afternoon. The ear temperature of P1 sows increased from 95° F in the morning to 97.5° F in the afternoon. P1 sows had a greater increase in shoulder temperature from the morning to the afternoon (93.7 to 96.4° F) compared to multiparous sows (94.1 to 96.1° F).įor all sows, ear temperature increased from 95.5° F before farrowing to 97.7° F after farrowing. Interestingly, rectal temperatures of sows housed in both rooms were similar, indicating that although the ambient temperature in the FA room was greater than the EC room, the sows in the FA room apparently coped with the higher temperature by increasing vasodilation and respiration rate to keep their body temperature stable.įor all sows, shoulder temperature increased after farrowing and remained elevated throughout lactation. However, the average rectal temperature after farrowing was greater in P1 sows (102.2° F) vs.
For both trials, average ambient temperature was lower in the EC room compared with the FA room.įarrowing was associated with an increase in rectal temperature for all parities (Figure 1). Outside and room ambient temperatures were measured by temperature sensors. Measurements included rectal temperature (thermistor thermometer with a probe), ear and shoulder temperature (infrared thermometer), and respiration rate (breaths/minute). on Monday, Wednesday and Friday from the day they entered the farrowing rooms until a few days after weaning. Thermal temperature measurements were taken at 9 a.m. Sows were split between the two rooms, with similar numbers of same parity sows housed in each room. Thirty-five sows were studied in 2010, 28 sows in the 2011 trial. In both trials, sows were moved from the breeding barn to farrowing rooms about one week before expected farrowing dates. The EC and FA rooms were located within the same farrowing building on the University of Missouri Swine Research Complex. Landrace or Landrace x Large White Parity 1 (P1) or multiparous (up to Parity 7) sows were used. Two trials were performed - one in June-July 2010, the other in June-July 2011 - to study the thermal response of different parity lactating sows housed in EC and FA farrowing rooms. Field observations suggest evaporative cooling can reduce ambient temperatures by 10° F. Fans pull the air through the pads, cooling the air by evaporation as it travels through the room and across the pigs. In EC facilities, water drips between ridged pads mounted on the side or end of the building. Fans pull air across the pigs at a rapid rate to allow for cooling. In FA facilities, outside air is pulled into the barn through inlets at the top and side of the room by fans located on the opposite wall. Two types of farrowing room ventilation systems are forced air (FA) and evaporative cooled (EC). Heat-stressed sows may also produce less milk, resulting in smaller piglets at weaning.Īttempts to modify farrowing room environment to reduce heat stress commonly center on reducing the internal body temperature of the sow during periods of high ambient temperatures. Heat stress can decrease farrowing rates and depress litter size for sows and gilts.