Pre Slaughter Determination of Animal Stress and Pork Quality

Increased competition for agriculture commodities such as pork products seems to be a reality in today’s international trade arena. Providing high quality pork products into such markets is no longer an option but a fundamental requirement for sustainability. The Canadian Pork Industry depends heavily on export dollars for survival. Thus, international competition based on quality and the realities of our geography and market infrastructure should make us vigilant with respect to finding new ways of continually improving. In order to provide high quality pork products factors such as animal procurement and pre slaughter management are extremely important.

Transport and handling are realities of our pork market. Transport and handling stressors can have a significant negative impact on animal stress and hence pork quality. We know, for example, that the simple act of loading and short transport of say 1.5 hours can increase a pigs salivary cortisol levels by two to four times normal values. We also know that such pre slaughter stressors can have a negative impact on pork quality resulting in altered colour, moisture holding capacity, pH and toughness. Unfortunately, most pork quality attributes are assessed after slaughter or post mortem and by then, of course, there is little one can do about it.

What pork producers and processors need is a crystal ball that would enable them to see, prior to slaughtering the animal, whether a specific pig was likely to produce poor pork quality. A decision could then be made to not process that pig right at that time and instead try to rest and rehabilitate the animal, thus avoiding a PSE problem. This, "pre slaughter predictability of pork quality issue", has been the focus of research at Lacombe Research Centre for a number of years.

From a research perspective, determining whether a live pig is stressed and would likely produce PSE pork if slaughtered is an accomplishable task if one is able to capture that animal and perform a number of biochemical, endocrine and physiological tests. Clearly, the practicality, never mind the expense, of such an undertaking in a major abattoir is not feasible. That is why we have examined the use of live animal non-invasive or remote evaluation procedures. The procedure that is currently showing significant promise is the use of infrared thermography. Infrared thermography is in its simplest form an image devise able to examine the radiated energy from an animal in the infrared range. We know from a number of tests that there is a significant correlation between the stress level an animal is experiencing (cortisol, catecholamines, blood metabolites) and the infrared characteristics displayed by that animal. We also know from numerous studies that there is a significant correlation between pork quality traits such as pH, colour, texture, and drip loss and infrared characteristics. For example, in trials at Lacombe Research Centre, pigs displaying normal drip loss (2.1%) and pH (5.61) 24h post slaughter were also seen to have lower (25.1 C) infrared temperatures. However, pigs displaying reduced pork quality traits (3.1 % drip loss and a lower pH of 5.56) also showed a higher radiated temperature (27.9C).

Studies are currently underway at Lacombe Research Centre to fine tune infrared prediction indexes for identifying live animals in the pre slaughter environment that would likely produce poor quality pork. Again, major advantages of the infrared system are that it is noninvasive (you don’t have to catch the pig and take a blood sample for example) and can be done at line speeds typical in modern swine abattoirs. The use of such technology in the Canadian swine industry may be one way of helping to maintain high pork quality standards.