Which gas is the only approved gas for stunning livestock?

• A. Nitrous Oxide
• B. Oxygen
• C. CO2
• D. Argon

Answer: (C)

Gas stunning aims to render livestock unconscious quickly and safely before slaughter. Carbon dioxide is the only gas here that has regulatory approval for routine stunning of livestock, because high concentrations reliably induce unconsciousness through rapid physiological effects and it integrates well with standard slaughter-line practices and welfare controls. Nitrous oxide, while it has anesthetic properties, raises welfare and practical concerns that prevent it from being approved for stunning. Oxygen on its own does not stun, so it cannot be used to achieve unconsciousness. Inert gases like argon can be used in some research settings, but they are not universally approved for commercial stunning due to variability in effects and welfare considerations.