The method of slaughter is one of the most critical welfare moments in any farmed animal's life — and for the billions of chickens slaughtered annually, electrical water bath stunning and controlled atmosphere killing are the primary methods with very different welfare profiles.
Slaughter welfare for poultry is one of the most tractable areas for welfare improvement at scale: relatively modest changes in technique affect the final experience of billions of animals annually. The shift from electrical water bath to controlled atmosphere killing eliminates the shackling distress that is one of the most acute welfare harms in the system. The capital cost is real but amortised across the enormous number of animals processed. Consumer and retailer pressure for higher welfare slaughter methods has driven adoption in some markets. The welfare case for regulatory mandates requiring controlled atmosphere or equivalent stunning is strong and backed by decades of welfare science.