Abstract: A method and apparatus for producing and maintaining a gas mixture in one or more phases, in which the phases are generated in zones of, for example, a stunning tunnel or a stunning shaft. The gas mixture includes carbon dioxide gas and oxygen gas, and the concentration of air is maintained at a level equivalent to a concentration level in air. Carbon dioxide is added based on the measured level of carbon dioxide in each zone.

Abstract: A method and apparatus for the treatment, such as anaesthetization or killing, of poultry by using gas. The gas comprises oxygen and carbon dioxide, among other components. During the treatment, the oxygen concentration is kept constant at a normal level (18-22 vol. %). This is important as it allows the poultry to breathe normally while the natural body functions can be maintained in their normal state until anaesthetization takes place. The concentration of carbon dioxide is increased either continuously or discontinuously. Accordingly, it is possible to anaesthetize poultry before slaughter in a way which produces low levels of stress and discomfort in the poultry while, at the same time, the quality of the meat is better than with the use of traditional methods. In the apparatus, the poultry are exposed to the gas in a chamber (1). The apparatus may include a belt conveyor (5) and can be separated into three treatment zones (2, 3 and 4).