PSII-6 Electronically controlled cooling pads improve litter growth and thermoregulatory measures and increase total heat production in heat stressed lactating sows

Abstract

Heat stress (HS) decreases lactation output in sows due to an attempt to reduce metabolic heat production; however, this negatively affects litter growth performance. Therefore, the study objective was to determine whether electronically controlled cooling pads (ECP) would improve indirect measures of lactation output (e.g., metabolic heat production) and litter growth performance in HS exposed sows. Over two repetitions, 12 multiparous (2.69 ± 0.85) lactating sows (265.4 ± 26.1 kg) and litters were assigned to either an ECP (n = 6) or a non-functional ECP (NECP; n = 6) and placed into farrowing crates within indirect calorimeters from d 3.7 ± 0.5 to d 18.7 ± 0.5 of lactation. Litters were standardized across all sows (11.4 ± 0.7 piglets/litter), and sows were provided ad libitum feed and water. All sows were exposed to cyclical HS (28.27 ± 1.42°C nighttime to 35.14 ± 0.70°C daytime). On d 4, 8, 14, and 18 of lactation, indirect calorimetry was performed on each individual sow and litter to determine total heat production (THP). Body temperature (TB), was measured hourly using vaginal implants, and respiration rate (RR) was measured daily at 0700, 1100, 1300, 1500, and 1900 h. Litter weights were obtained at birth and weaning. An overall decrease (P < 0.01; 25 bpm) in RR and maximum daily TB (P = 0.02; 0.40°C) was observed in ECP versus NECP sows. An increase in THP (P < 0.01; 20.4%) and THP/kg0.75 (P < 0.01; 23.1%) was observed for ECP when compared to NECP sows and litters. Litter growth rate was increased (P < 0.01; 20.8%) in ECP versus NECP sows. In summary, the use of ECP improves litter growth, thermoregulatory measures, and bioenergetic parameters associated with greater milk production in lactating sows exposed to cyclical heat stress.