Effects of lairage time and stunning onstress and the meat quality of pigs

Much research has been done on pre-slaughter factors, both at home and abroad. In summary, no conclusion has been formed about lairage time. Regarding the high cost of production or other factors, the application and study of carbon dioxide stunning is poor in our country. There has been little research comparing different ways of stunning. In this paper, changes in blood parameters and meat quality in Duroc ×Large White ×Landrace pigs stunned by electricity or carbon dioxide after different lairage times (3 h, 6 h and 12 h), were studied. The results showed that the blood parameters of pigs with 3 h lairage time were significantly lower than for the other two methods, while lactate, creatine kinase, cortisol and lactate dehydrogenase in carbon dioxide stunning were significantly lower than in non-stunning and electric stunning. Different lairage times had no significant effect on the longissimus muscle values of pH, temperature, cook loss, lightness, a * and b * color coordinate values at 24 hours post-slaughter (P>0.05), but pigs with 3 h resting time had significantly lower pH values and temperature at 45 min post-slaughter. Drip loss and shear force values at 24 hours post-mortem were also significantly lower than at the lairage time of 6 h and 12 h. Compared with non-stunning and electric stunning, stunning with carbon dioxide produces lower pH values and temperature at 45 min post-slaughter, higher drip loss and lightness values, and lower a*and b* color coordinate values. The research identified that pigs which had the minimum stress response and the minimal effect on the meat quality were stunned by carbon dioxide after 3 h lairage time. In conclusion, more attention should be paid to lairage time and the way of stunning, as well as to the influence of the synergy of various processing methods for meat quality in order to realize the maximum degree of improvement in pork quality.