The effect of stocking density in transit on the carcass quality and welfare of slaughter pigs: 2. Results from the analysis of blood and meat samples.

In a trial involving 2496 pigs, the influences on blood profile and pork quality of stocking densities ranging from 201 to 321kg m(-2) were examined. The pigs came from four different farms and were killed in 16 weekly batches. They were transported for on average 3hr and held in lairage for 1hr. Higher stocking densities resulted in more physical stress to the pigs based on the activity of the enzyme CPK in the blood. Stocking density did not apparently affect psychological stress and high densities did not result in dehydration. The colour, water holding capacity and instrumentally-determined texture of the pork from the carcasses of the pigs were not affected by stocking density. The experimental design and precision of the measurements were sufficient to detect numerous differences in blood profile and pork quality between pigs from the four source farms. These differences probably related to different degrees of stress-susceptibility. The results suggest that the highest stocking density examined (321kg m(-2)) is unacceptable for the transport of pigs. The second highest density (281kg m(-2)) produced relatively little evidence of an adverse effect on the welfare of pigs. It may be scientifically acceptable for short journeys (≤3hr) but not for longer ones where pigs need more space to lie down.