A little rest and relaxation can reduce stress in your pigs, just like it can with you. Allowing hogs to rest and adjust to their surroundings before slaughter may avoid aggravating stresses that reduce pork quality, according to University of Missouri research.
“High pre-slaughter stress is the single biggest factor responsible for pork quality reductions,” says David Newman, a University of Missouri meat science graduate student. “However, it appears that suboptimal transportation and resting periods at the plant that are too short can worsen the negative effects of high stress.”
When pigs become stressed “their fight or flight mechanisms kick in,” says Eric Berg, University of Missouri meat scientist. “The pig’s body temperature, blood pressure and hormone levels all increase. Then when the pig is slaughtered, all that heat and energy is trapped in the muscle. The result is pale, soft and exudative pork, which tends to be tough, dry and less appetizing to the consumer.”
In the study, hogs were divided into different treatment groups and subjected to varying transport conditions, lengths of time spent in holding pens prior to slaughter and pre-slaughter stress levels. After slaughter, the researchers measured lean-meat quality attributes including fresh pork color, the meat’s pH and electrical conductivity. Stress hormones were evaluated from blood samples.
A long, rough transport period by itself or one that followed with a short holding period at the plant had little overall impact on pork quality, Newman notes. But, hogs that were subjected to those treatments as well as high pre-slaughter stress ended up with lower pork quality than hogs subjected to high pre-slaughter stress alone.
The take-home message is to do everything you can to ensure a low-stress production system, right down to choosing a truck driver certified in quality assurance, says Newman. His message for packers is that whenever feasible, give hogs a chance to rest when they come off the trucks and ensure that employees observe all handling procedures to reduce stress before pigs move to slaughter.