Space requirements of weaned pigs during a sixty-minute transport in summer.

Currently, there are no trucking quality assurance recommendations for space allowance of weaned pigs during transport in the United States. The objective of this research was to establish a first estimate of the space requirements of weaned pigs during transport in summer based on measures of animal well-being. A commercial semi-trailer was fitted with compartments that provided 0.05, 0.06, and 0.07 m(2)/pig, which were replicated on the upper and lower deck, with a constant 100 pigs per compartment. Cameras were placed in each experimental compartment to record behaviors and postures of pigs during transport. The frequencies of standing, lying, sitting, standing/rearing on another pig, and lying/huddling on top of another pig were recorded using 1-min scan samples during the entire duration of transport. Blood samples were collected and BW and lesion scores recorded from 32 pigs per space allowance for physiological and immune measures before and after transport (n = 32 pigs/treatment). Pigs were transported for 60 +/- 5 min to the wean-to-finishing site using the same route for each replicate during summer (temperature: 28.4 +/- 1.2 degrees C and relative humidity: 59.8 +/- 4.4% within the trailer). Data were analyzed using the MIXED procedure (SAS Institute Inc., Cary, NC). Cortisol, hematocrit, blood urea nitrogen, total protein, albumin, aspartate aminotransferase, creatine kinase, and gamma-glutamyl transferase increased (P < 0.05) after transport regardless of space allowance. Plasma glucose and BW decreased (P < 0.05) after transport regardless of space allowance. Lesion scores increased (P < 0.001) after transport and were greater (P < 0.05) for barrows compared with gilts. The neutrophil to lymphocyte ratio was greater (P < 0.005) for pigs transported at 0.05 m(2)/pig compared with pigs transported at 0.06 and 0.07 m(2)/pig. Pigs transported at 0.05 m(2)/pig lay down less (P < 0.05) than pigs transported at 0.06 and 0.07 m(2)/pig between 30 and 60 min of transport. Greater neutrophil to lymphocyte ratio and less lying behavior performed by pigs transported at 0.05 m(2)/pig suggest that a minimum space allowance of 0.06 m(2)/pig was preferable when transporting weaned pigs for 60 min during summer in this study.