Variations in electrical stunning tong placements and relative consequences in slaughter pigs

Variations in the manual application of electrical stunning tongs that are commonly observed in stunning pens in abattoirs were tested under laboratory conditions on 145 pigs. Five different placements, previously identified during a survey, using either 150 or 250 V were studied, and the welfare consequences and effects on the intensity of carcass convulsions were assessed. Quantitative relationships between tong applications, average current strength, prevalence of induction failure, indicators of insensibility and signs of recovery were evaluated. Those placements not spanning the brain were found to be inadequate on welfare grounds when used at 150 or 250 V. The variation in convulsion intensity, subjectively scored, was small and therefore it is unlikely that tong position using a 50 Hz alternating current (AC) is an important factor influencing carcass handling. The need to develop methods for reliably measuring currents going through the brain is emphasized.