Effects of season, truck type, and location within truck on gastrointestinal tract temperature of market-weight pigs during transport

Two experiments were done to assess the effects of season, truck type, and location in the truck on the gastrointestinal tract temperature (GTT) of market-weight pigs during transport. In Exp. 1, a total of 504 sentinel pigs were selected from a total load of 3,756 pigs over 12 wk in summer or winter and transported in either a double-decked (DD) hydraulic truck or a pot-belly (PB) trailer for 2 h. In Exp. 2, a total of 330 sentinel pigs were selected from a total load of 2,145 pigs over 11 wk in summer or winter and transported in a PB trailer for 8 h. In both experiments, sentinel pigs were equipped with a temperature data logger for the real-time GTT recording from the farm to slaughter. Transport was divided into 8 periods in Exp. 1 (rest, pretravel, initial travel, prearrival 1, prearrival 2, unloading, lairage 1, and lairage 2]) and in Exp. 2 (rest, pretravel 1, pretravel 2, travel, prearrival 1, prearrival 2, lairage 1, and lairage 2). A delta GTT (Delta GTT) was calculated as the difference between the measured GTT at any determined event and the GTT measured at rest. In Exp. 1, the Delta GTT of pigs was greater (P < 0.001) in summer than in winter and only during the pretravel and initial travel periods. No difference was observed in the Delta GTT between the 2 truck types (P > 0.10). In summer, pigs located in the front top and rear top compartments of the PB trailer presented greater (P < 0.05) Delta GTT values than those transported in the middle top and front belly compartments during initial travel. In summer, during prearrival 1 and 2, a greater (P < 0.05) loss of GTT was found in pigs located in the rear top compartment of the DD truck compared with the rear lower compartment and in the front middle compartment compared with the rear middle compartment of the PB trailer. In Exp. 2, the Delta GTT of pigs was greater (P = 0.03) in summer than in winter during pretravel 2. Pigs in the front top compartment had a greater (P < 0.05) Delta GTT compared with pigs in the middle top, lower deck, and front belly compartments during the pretravel periods. Based on the results of the 2 experiments, modifications of the PB trailer model are recommended to limit body temperature increase due to physical stress at loading and unloading, and during transport due to inconsistent ventilation rate across vehicle locations.