Heat and Moisture Production Rates of a Modern U.S. Swine Breeding, Gestation, and Farrowing Facility

Abstract

Abstract. Current recommendations for swine building ventilation system design to maintain an environment conducive to animal productivity and well-being are based on heat and moisture production rates measured in the 1950s and 1970s. Advancements in animal genetics, nutrition, and management practices to increase productivity and pork quality since then have led to considerable changes in heat and moisture production rates of modern swine and their housing systems. This study quantifies the total heat production rate (THP) of the animals, which is partitioned into house-level latent heat or moisture production rate (LHP, MP) and house-level sensible heat production rate (SHP), of a 4300-sow breeding, gestation, and farrowing facility in Iowa for 16 consecutive months. The THP was determined using indirect animal calorimetry, LHP or MP was determined from mass balance, and SHP was calculated as the difference between THP and LHP. A mobile air emission monitoring unit equipped with state-of-the-art gas analyzers and a data acquisition system was used to monitor the deep-pit breeding and early gestation barn [1800 head, 204 ±3.2 kg head -1 (mean ±SE)], the deep-pit late gestation barn (1800 head, 219 ±3.0 kg head -1 ), and two shallow-pit (pull-plug) farrowing rooms (40 sows with litters per room, 223 ±0.4 kg head -1 ). Results from the study show that THP at 20°C averages 1.89 W kg -1 for sows in the breeding and early gestation stage, 1.57 W kg -1 for sows in the late gestation stage, and 3.35 W kg -1 for sows and litters in week 0 of the lactation stage. The corresponding house-level LHP for the three stages averages 0.74 W kg -1 (early gestation), 0.57 W kg -1 (late gestation), and 1.98 W kg -1 (lactation, week 0). Finally, the corresponding house-level SHP for the three stages averages 1.15 W kg -1 (early gestation), 1.00 W kg -1 (late gestation), and 1.37 W kg -1 (lactation, week 0). Compared with the ASABE Standards, the values from the current study for gestation sows in their early and late pregnancy stages showed increases of 35% and 12% in THP, 72% and 34% in LHP, and 19% and 3% in SHP, respectively. Values for lactating sows and litters during the first week after parturition showed changes of 29% in THP, 52% in LHP, and 6% in SHP relative to the ASABE Standards. The reductions of THP from day to night for the three stages were 30% (early gestation), 27% (late gestation), and 6% (lactation). These data will help with updating the standards for ventilation design and operation of modern swine housing.