Pigs hauled in the bottom nose compartment of a pot-belly trailer have much greater risk for higher levels of stress and poorer meat quality, according to a study at the Prairie Swine Centre in Saskatoon, Saskatchewan.
A total of 1,170 market pigs were hauled in summer and winter during six-week periods in a pot-belly trailer for eight hours from Saskatoon to Brandon, Saskatchewan.
Compartments were categorized. Pigs in the middle deck did not have to use an internal ramp. Pigs in the belly compartment had to descend a ramp during loading and ascend during unloading. Pigs in the upper deck ascended a ramp during loading and descended it at the packing plant. Pigs in the bottom nose compartment had to ascend and then descend ramps during both loading and unloading.
Focal pigs located throughout the truck were equipped with heart monitors and then sampled for lactate levels at slaughter and evaluated.
All pigs were fasted 8-9 hours before loading (21 hours before slaughter) and kept in holding pens at the packing plant for 1.5 hours prior to slaughter.
Various muscle pH readings, light reflectance and drip loss were taken to assess pork quality.
Pigs loaded in summer in the bottom nose presented higher heart rate readings at loading compared to those located in the bottom deck, with pigs in the middle deck and upper deck being intermediate. During transport, pigs loaded in the upper deck and middle deck had higher heart rates than pigs in the bottom deck and bottom nose compartments.
At slaughter, blood lactate levels were higher in pigs transported in the bottom nose section. The higher heart rate and lactate levels may reflect the greater physical effort required of pigs to climb the very steep ramp giving access to the bottom nose compartment.
Meat quality was somewhat affected by this physical effort as those pigs in the bottom nose compartment displayed higher pH values and lower drip loss.
In winter trips, pigs loaded in the bottom nose showed a higher heart rate at loading and higher blood lactate levels.
Meat quality was also affected by animal location during winter transport of pigs, with those in the bottom nose compartment showing higher pH values and lower drip loss.
Higher pH values and low drip loss indicate that these pigs are prone to poor meat quality referred to as dark, firm and dry as the result of an extended period of stress.
Researchers: J.A. Correa and J.P. Laforest, Laval University; H.W. Gonyou, Prairie Swine Centre; T.M. Widowski, C. Dewey and R. Bergeron, University of Guelph; S. Torrey and L. Faucitano, Agriculture and Agri-Food Canada; N. Lewis, University of Manitoba; and T. Crowe, University of Saskatchewan. For more information, contact Gonyou by phone (306) 667-7443, fax (306) 955-2510 or e-mail harold.gonyou@usask.ca.