Effects of evaporative cooling systems on the performance of lactating sows in a tropical climate.

This study evaluated litter performance, behavioral and physiological parameters, and milk characteristics of sows submitted to different thermal environments. Fifty sows were distributed in a completely randomized design with two treatments: an evaporative cooling system (ECS) and a conventional system (CS). Sow and its litter were characterized as an experimental unit. The animals were weighed at equalization and weaning. Feed intake, milk production, and bromatological characteristics of milk were measured; the sows respiratory rate, rectal, and surface temperature were monitored. Litter uniformity was determined at equalization and weaning. Behaviors of the sows and litters were monitored for 24 h on the 7th and 15th day of lactation. Temperature and relative humidity inside the maternity was 25.00 to 28.00 °C and 26.00 to 32.55 °C and 30.00 to 70.00% and 70.00 to 88.00%, respectively, considering ECS and CS. Nutritional quality of the milk remained stable during lactation in both systems evaluated. ECS improved the average weight of the piglets, weaning weight, and daily milk production by 0.038, 0.699, and 2.31 kg/day, respectively. Sows housed in the ECS had a reduction in physiological parameters and, increase in inactive alert behavior (1.79 percentage points) and breastfeeding behavior. Piglets showed a decrease of 2.43% in the range of feedings at night and 0.15% during the day. ECS provided better comfort to the sows at the expense of the CS and, consequently, better litter performance.