An Innovative Ventilation and Cooling Strategy Based on the Thermal Comfort of Growing-Finishing Pigs

Highlights Nine treatments of a ventilation and cooling strategy based on the HS2I index were developed. The treatments were tested with pigs (45-120 kg) exposed to artificial heatwaves in experimental rooms. Zootechnical performance showed no advantage in using larger sprinkling water volumes. The combination of an HS2I of 3.0 and reduced sprinkling water volumes may not avoid heat stress for heavier pigs. Abstract. During the growing-finishing phase of pig production, mitigating heat stress is essential to maximize growth performance, improve feed efficiency, and minimize risks of deteriorating animal welfare and farm profitability. Housed Swine Heat Stress Index (HS2I) assesses pigs’ thermal comfort into a dimensionless metric scored from 0 (no heat stress) to 10 (severe heat stress), where 3 marks the beginning of heat stress along the range. Focusing on thermal comfort, a ventilation and cooling strategy based on the HS2I was implemented through precise control of air velocity and cooling using water sprinklers. The objective of this study was to optimize this strategy by adjusting two main parameters: the HS2I setpoints (2.0, 2.5, or 3.0) and the water sprinkling volumes (partial, gradual, or complete). Experiments were conducted in laboratory rooms housing 14 pigs under simulated summer-like conditions to test nine functional treatments of the strategy. The results showed that reduced water use through partial sprinkling was generally adequate to maintain pig performance, regardless of the selected HS2I setpoint. However, the combination of an HS2I setpoint of 3.0 with a reduced sprinkling strategy may expose heavier pigs (>100 kg) to heat stress. These findings offer practical insights for optimizing cooling strategies in pig production systems that face heat stress challenges. Keywords: Animal index, Direct cooling, Heat stress mitigation, Recirculation fans, Sprinkling systems, Swine production, Zootechnical performance.