Electrical water bath stunning is the dominant poultry slaughter method but has significant welfare problems; controlled atmosphere systems offer a more welfare-positive alternative.
Electrical water bath stunning is associated with welfare problems at every stage. Shackling inverted conscious birds causes acute pain and stress from the inversion posture, wing spread, and restraint. Pre-stun shocks cause pain without insensibility in a proportion of birds. Recovery from stun before killing is possible if the current is insufficient. Controlled atmosphere killing systems address these problems by rendering birds unconscious in their transport crates before they are removed for processing, eliminating shackling and inversion stress. The welfare improvement is substantial and the technology is commercially available; the barrier to widespread adoption is infrastructure cost and the time needed for facilities to retrofit.