Survey of the effectiveness of stunning procedures used in Spanish pig abattoirs

Two pig abattoirs (A and B) equipped with an automated head-only and head-t o-chest electrical stunning system, and two (C and D) equipped with a manua l carbon dioxide stunning system, were evaluated to compare the effectivene ss of stunning in a total of 10,454 pigs slaughtered under commercial condi tions. In the abattoirs with the electrical stunning system, the percentage of animals that responded to a nose prick was significantly lower (P<0.05) in abattoir B, where a higher current intensity was used (P<0.05). than in abattoir A. No righting reflex was observed in the electrically stunned pi gs. In the abattoirs with the carbon dioxide stunning system, the percentag e of animals that responded to a nose prick and showed a righting reflex wa s significantly lower (P<0.05) in abattoir C,where the duration of the carb on dioxide cycle was longer and the interval between discharge from the sys tem to sticking was shorter (P<0.05). than in D. Comparing the electrical a nd carbon dioxide stunning systems, the pigs stunned with carbon dioxide we re significantly more responsive to a nose prick (P<0.05) and 25 per cent o f them showed a righting reflex. Under the conditions of the study the full y automated head-only stunning with additional chest electrodes appeared to be more effective and less susceptible to incorrect handling than the manu al carbon dioxide stunning system.