The use of a high pressure waterjet combined with electroimmobilization for the stunning of slaughter pigs: Some aspects of meat quality.

It is considered that waterjet stunning may be a humane stunning method to apply in slaughter facilities. An experiment was conducted in a slaughterhouse to examine the effects of waterjet stunning combined with electroimmobilization during exsanguination on the occurrence of haemorrhages in the muscles and on meat quality. Slaughter pigs (n = 31) were stunned by waterjet (3900 bar) in a V-type restrainer and immobilized electrically (40 V) during exsanguination. Control animals (n = 39) were stunned automatically and electrically (600 V) using the same restraint device. At 45 min post mortem the pH in the semimembranosus (SM) and longissimus dorsi (LD) muscles was significantly lower (p < 0·01), while rigor mortis and temperature in the SM and LD were significantly higher (p < 0·05 and p < 0·01, respectively) in the carcasses of pigs stunned with the waterjet as compared to control pigs. At 18 h post mortem the ultimate pH of the LD was lower (p < 0·05), while scatter (fibre optic probe) and filter paper test values of the LD were higher (p < 0·01) in carcasses of pigs stunned with the waterjet. Fewer haemorrhages were observed in the shoulders of pigs stunned with the waterjet. The results of this experiment suggest that waterjet stunning, when combined with electroimmobilization, may be a suitable method to stun pigs in a slaughterhouse. However, further studies are required to improve the meat quality.