Stunning is the primary welfare intervention at poultry slaughter. When correctly implemented it ensures unconsciousness before killing; when it fails, birds may be conscious during slaughter.
Poultry stunning welfare represents one of the highest-volume welfare intervention points in the food system — billions of birds pass through stunning systems each year. When water bath stunning is correctly calibrated (appropriate current, frequency, and exposure duration for species and size), it produces immediate unconsciousness. However, practical implementation faces consistent challenges: birds that raise their heads avoid full immersion; incorrect parameters may paralyse without rendering unconscious; pre-stun shocks cause pain before the full stun current; and recovering consciousness before neck cutting — while rare in well-managed plants — causes suffering if it occurs. Controlled Atmosphere Killing, by contrast, avoids the pain of conscious inversion and shackling, and newer low-O2 systems using nitrogen or argon mixtures produce unconsciousness more humanely than high-CO2 systems (which cause aversive breathlessness before unconsciousness). The welfare case for transitioning from water bath to CAK systems is strong and growing. EU and UK welfare regulations require regular stunning effectiveness checks, but audit quality and frequency vary significantly across plants.