Development and validation of an air recirculated ventilation system, Part 2: Evaluation of pig productivity in spring and summer seasons including examination of cooling methods

An air recirculated ventilation system (ARVS) for a pig house was developed to improve the rearing environment, prevent livestock disease, reduce odour emission, and save energy. The validation experiments for winter were completed in our previous research (Kim et al.., 2023), but additional experiments were carried out in spring and crucially in summer when the cooling of pig house is important. Since directly using cooling devices may use excessive energy, more efficient cooling methods were required. In this study, ARVS, cooling methods that can lower the windchill temperature of piglets were evaluated. When the recirculating water temperature of the wet scrubber module was maintained at about 20 °C, the air temperature can be lowered by about 4 °C. From calculating the calorific value based on the heat production of piglets and ventilation rate, thus the capacity of the cooling device of the recirculating water was expected to be very large. The ventilation rates in the ARVS piglet room during spring and summer therefore remained consistently high. In particular, the humidity inside the ARVS piglet room was maintained appropriately despite the significant rainfall that occurred in the summer. The ammonia concentration was found to be below 5 ppm in ARVS piglet room, but as high as 57 ppm in the conventional piglet room. The odour concentration emitted from the ARVS piglet room was generally <100 OU. As a result, the body mass gain was improved by 2.8 kg and 1.0 kg, respectively, during the spring and summer.