Effect of current intensity and duration on the effectiveness of head-only electrical stunning in pigs under commercial conditions.

After head-only electrical stunning of pigs sequential animal-based measurements were carried out right after stunning as well as before and after bleeding in order to analyse how unconsciousness is achieved and maintained in relation to recorded and calculated technical parameters such as electric current intensity, electric work, duration of stunning, and stun-to-bloodletting period. The measurements were performed at three different slaughterhouses on 9 different days under routine slaughtering conditions. The data of 405 pigs were analysed. The effectiveness of stunning was measured by the number of parameters at two (adequate and acceptable) levels. Current intensity had a predominant effect on the effectiveness of stunning and on the maintenance of unconsciousness. The duration of stunning played a role only as part of the electric work, which manifested itself in the maintenance of unconsciousness. Stunning proved acceptable in 99% of the cases, provided that the minimum current intensity of 1.02 Amp was secured. In 99% of the cases unconsciousness could be maintained at an acceptable level beyond bloodletting when the electric work was at least 8,089.38 Joules. Recovery of consciousness depends on the stun-to-stick period: the best time of bloodletting is less than 32 seconds from the end of stunning.