A possible explanation for this difference is that the pigs can recover from previous stresses prior to arrival at the slaughterhouse, which is not the case for lairage times < 2 h. The higher prevalence (not significant) of PSE for lairage times > 4 h, could be caused by a higher preslaughter stress. The pigs were sleeping and needed to stand up to be driven to the stunner.
As the prevalence of DFD meat is very low, no effect of lairage time was found (data not shown). More DFD cases are needed to investigate the impact of different lairage times on the DFD prevalence in Summer.