The behavioural response of finisher pigs and sows to electrode attachment: An evaluation of pig welfare and ease of application as a precursor to on-farm euthanasia by one-step electrocution

An alternative stun-kill electrocution technique may be more user-friendly to euthanize large pigs (68-300kg), over the captive bolt or gunshot. High voltage (>250 Volts) equipment for applying head-chest electrocution through tongs exists, but is costly. Attaching two electrodes (copper clamps) to blood-rich areas, then connecting them to an accessible 120 Volt power source, could theoretically, deliver sufficient amperage simultaneously to the brain and heart, killing the pig. This study investigated the behavioural response of sows (n=138) and finisher (n=40) pigs to electrode attachment, and ease of application. Each pig was restrained in a pen and received four treatments in varied sequence: bridle-belt (BB), clamps on tail and ear (CTE), or flank and lip (CFL), and handling without electrodes (CON). Per treatment, electrodes were left attached for 10s then removed. The behavioural response was scored (0: accepting to 3: highly aversive) and behaviours expressed (frequency) were recorded. Three attempts to attach electrodes were allowed, and the duration of time for attachment was measured. Attaching CTE was quickest (P<0.001) and >1 attempt was most probable with BB (P<0.001). Aversion was more probable with CTE and CFL compared to BB or CON (P<0.001). Clamp combinations were easier to attach, while BB minimized aversion.