CO 2 is not an acceptable method for killing waterfowl. It is especially important to confirm death when birds are euthanized using gas, since they can appear dead but then regain consciousness. Containers in which birds are euthanized should be clear or have a window through which the birds can be observed. When large numbers of poultry are to be killed, as during the depopulation of spent hen flocks, it is important that CO 2 be injected frequently into the chamber to maintain these levels. The MAK container holds about 200 hens when full.
Carbon monoxide is a relatively rapid and effective method of euthanasia for birds.
Carbon monoxide combines with the hemoglobin in the red blood cells in preference to oxygen, causing hypoxia. Only a pure, commercially compressed source of CO should be used. Vehicle exhaust is not an acceptable source of CO for euthanasia because it is hot and contains contaminants. High levels of CO are deadly to humans, and chronic exposure of pregnant women to even low levels of CO can cause birth defects. Only well-trained personnel should therefore use carbon monoxide and then only under properly controlled circumstances.