The problem with using CO2 for culling is because the chemoreceptors that detect levels of carbon dioxide. The body knows when it is suddenly experiencing hypercapnic hypoxia (high CO2, low O2), and triggers a panic response that includes hyperventilation in an attempt to correct the situation. The animal will lose consciousness eventually, but such a death isn't pain free, if you can imagine the sensation of not being able to breathe.
And freezing? For euthanasia, that is about as barbaric as they come. They don't fall asleep. They live as the water in their cells begin to freeze and crystallize, which is horribly painful. Have you ever gotten frostbite on your fingers? It is incredibly painful.
And freezing? For euthanasia, that is about as barbaric as they come. They don't fall asleep. They live as the water in their cells begin to freeze and crystallize, which is horribly painful. Have you ever gotten frostbite on your fingers? It is incredibly painful.