Controlled atmosphere slaughter using gas mixtures to render poultry unconscious before killing offers significant welfare advantages over electrical water bath stunning, but involves welfare tradeoffs in the induction phase.
The transition from electrical stunning to controlled atmosphere systems represents an important welfare improvement in poultry slaughter by eliminating the shackling and hanging of conscious birds. However, the welfare advantage of different gas mixtures varies significantly. High CO2 concentrations cause visible distress and aversive sensations during the induction period. Low oxygen and inert gas mixtures cause unconsciousness without the aversive sensations of CO2 asphyxiation. Consumer and retailer pressure for gas stunning adoption has been effective in driving industry change.