Observations of market pigs following transport to a packing plant.

A field study was conducted to record observations of 41,744 market-weight pigs upon arrival at a commercial abattoir to evaluate the relationships between various independent factors and open-mouth breathing, skin discoloration, lameness, unloading time, and mortality during transport. Observations were recorded from 242 trailer loads on 46 separate days over a period of 14 mo. Travel time (<2.5 h or >or=2.5 h), wait time before unloading (<20 min or >or=20 min), loading pressure (<260 kg of BW/m(2) trailer floor space or >or=260 kg of BW/m(2) trailer floor space), ambient temperature while unloading (<17 degrees C or >or=17 degrees C), and trailer type [potbelly (PB); straight-deck with conventional unloading doors (SDC); or straight-deck with wide unloading doors (SDW)] were recorded for each load. Open-mouth breathing was more prevalent in pigs when transported on PB trailers compared with that of SDC or SDW trailers (P < 0.01), and at warmer temperatures (>or=17 degrees C, P < 0.001). Skin discoloration was more prevalent (P < 0.001) among pigs unloaded at temperatures >or=17 degrees C. Lameness was more prevalent (P < 0.05) after shorter travel times at greater loading pressure compared with shorter travel times at decreased loading pressure. Unloading time for PB trailers was longer (P < 0.001) than for SDC and SDW. Mortality rates during transport were minimal (0.06%) in the deliveries that we observed, and there were no significant (P > 0.10) relationships between mortality and any independent variable tested. Wait time before unloading was not associated (P > 0.10) with any of the dependent variables included in the statistical model. In conclusion, warmer ambient temperatures (>or=17 degrees C) and the use of PB trailers are associated with an increased incidence of open-mouth breathing and skin discoloration, and longer unloading times after the transport of market pigs.