Heat stress matters: Insights from United States swine producers

Abstract Heat stress (HS) is widely recognized by researchers and veterinarians as a major issue impacting swine health, productivity, and welfare, but there is limited understanding of how HS is perceived and managed at the farm level. Therefore, the study objective was to assess U.S. swine farm managers' perceptions of HS impacts, thresholds, and management for multiple pig categories including pre-weaned pigs, nursery pigs, grow-finish pigs, market pigs, non-pregnant and gestating sows, lactating sows, and mature boars. Sixty-two swine farm managers completed an electronic Qualtrics survey, presented in both English and Spanish, which included questions on perceived HS thresholds, ventilation setpoints, mitigation practices, and environmental management support tools. Respondents rated their agreement with HS impacts on productivity, health, and welfare using a Likert scale, and Pearson’s correlations were used to establish relationships between responses. A majority of respondents agreed or strongly agreed that HS negatively affects pig productivity (87.1%), health (83.9%), and welfare (85.5%). However, perceived HS thresholds were variable across pig categories including pre-weaning pigs (31.22 ± 3.59°C), nursery pigs (31.46 ± 3.79°C), grow-finish pigs (28.16 ± 4.27°C), market pigs (26.22 ± 5.56°C), non-pregnant sows (27.77 ± 3.81°C), gestating sows (26.99 ± 3.34°C), lactating sows (26.71 ± 3.08°C) and mature boars (26.61 ± 3.99°C). The standard deviations for reported thresholds ranged from ±3.08°C to ±5.56°C, underscoring the variability in perceptions among respondents. This variability extended to ventilation temperature setpoints with high ventilation temperature setpoints of 24.34 ± 3.75°C and 25.41 ± 2.80°C, and low ventilation temperature setpoints of 17.32 ± 3.10°C and 18.86 ± 2.96°C for gestation barns and farrowing barns, respectively. Finally, a majority of producers (64.5%) agreed or strongly agreed that a decision support tool for improved HS management would be beneficial to their operation. Producer responses emphasize the need for clearer guidelines and more consistent application of HS management practices to optimize swine health, productivity, and welfare across different production stages.