The pig metabolome modifications under heat-stress conditions: towards the description of physiological mechanisms in pig genetic resources

Heat-stress significantly impairs pig production by reducing performance and reproduction efficiencies. Therefore, it is crucial to understand the physiological mechanisms that contribute to resilience in order to enhance the ability of pig industry to adapt to the increasing frequency of these challenging conditions in the context of climate change. Different pig breeds may respond differently to heat stress based on their genetic background. In this study, we investigated the modifications in the blood metabolome profiles of pigs from various breeds in response to the circadian rhythm in high summertime temperatures. We utilized an untargeted metabolomic platform to measure approximately 700 metabolites in 12 animals per breed from four different breeds (two cosmopolitan breeds: Italian Large White and Italian Duroc; and two local breeds: Cinta Senese and Mora Romagnola). Samples were taken in the late afternoon (the hottest part of the day) and in the morning (the coolest part of the day). Metabolomic profiles were compared using a machine learning approach based on random forest. We identified 30-50 heat-stress-related metabolites from each breed and their discriminative power was confirmed with unsupervised analyses. However, each breed exhibited unique modifications in their metabolomic profiles, with only a few metabolites shared between breeds. This study revealed distinct physiological mechanisms among breeds that may help them cope with heat stress. The findings offer new insights into the molecular mechanisms involved in circadian rhythm physiological processes in these pig breeds. Acknowledgments: This study has received funding from the European Union's Horizon Europe research and innovation programme under grant agreement No. 01059609 (Re-Livestock project).