The effect of stunning methods on stress and meat quality parameters in pigs

A total of 100 commercial market pigs were randomly allocated to two stunning treatments: carbon dioxide (CO2) and electrical stunning, at a commercial abattoir. The effects of the two stunning methods on pig stress and meat quality were measured. Blood lactate and cortisol, and postmortem pH (pH45 min; pH24 h), temperature (T45 min), drip loss and sensory color for the longissimus dorsi, pars lumbalis, were determined. After electrical stunning, pH45 min and pH24 h was lower than after CO2 stunning (P<0.05), and T45 min was higher (P<0.01). There was no effect (P>0.05) of stunning on drip loss 24 h and 48 h post-mortem, or sensory color, or on stress parameters, lactate and cortisol. However, individual animal variations of stress markers within the slaughter batch were very high, and their average concentrations indicated high levels of stress. From the perspective of animal welfare and protection, both stunning methods should be conducted properly, according to the defined procedures to minimize stress and to assure adequate meat quality.