Season, transport duration and trailer compartment effects on blood stress indicators in pigs: Relationship to environmental, behavioral and other physiological factors, and pork quality traits

Transport factors, such as ambient conditions, travel duration and trailer design and compartment location have an impact on the welfare of pigs during transport, carcass bruises and meat quality. However, these results arise from studies where the effects of season, travel duration and compartment location were assessed separately. To our knowledge, the combined effects of these factors on exsanguination blood parameters have not been studied in pigs. Furthermore, correlations between blood parameters evaluated at slaughter, ambient and truck microclimate measures, and other physiological and behavioral response indicators to transport stress have not been calculated in one single study to validate their efficiency as a transport stress monitoring tool. The results of this study suggest that pigs transported at elevated truck temperatures are likely to experience higher stress, especially when they are transported in poorly designed vehicles. Based on the weak to moderate correlations with environmental, other physiological and behavior indicators and meat quality traits, the stress parameters measured in blood collected at exsanguination in this study cannot be considered other than as a complementary measurement in the assessment of the physiological response to transport stress. Overall, the outputs of this study should stimulate the Canadian trucking industry to improve the design of vehicles used for swine transportation to ensure more consistent comfort for all animals and reduce animal and economic losses.