The method of slaughter is one of the most significant welfare moments in farm animal lives, with stunning technology able to prevent conscious suffering but inconsistently applied globally.
Pre-slaughter stunning aims to render animals insensible before killing, preventing conscious suffering. When correctly applied, captive bolt stunning of cattle and electrical stunning of pigs and poultry produces rapid unconsciousness. However, slaughter line speed and operator fatigue lead to missed stuns and inadequately stunned animals. Approximately 1-5% of cattle and higher percentages of poultry may be inadequately stunned based on inspection data. High-concentration CO2 used for pig stunning causes a burning sensation in mucous membranes before loss of consciousness. Inert gas mixtures are more humane but less widely adopted. Non-stunned religious slaughter is permitted in many countries, with debate about whether properly performed non-stunned slaughter is less humane than poorly applied stunning. CCTV in slaughterhouses has improved compliance.