[CO2 stunning of broilers and turkey hens]

Stunning of poultry is still not solved satisfactorily. This concerns the requirements of animal welfare, meat quality and working conditions in the lairage, stunning and debleeding area. In an investigation of combined CO2-/O2-stunning in a new gas stunning system stress reactions of the animals during the induction phase and stunning effectivity were recorded in 7,000 chicken and 3.825 turkeys. During the induction phase (here: chicken 41 sek./turkeys 25-65 sec.) the animals first staid calm and then showed beak-opening as a consequence of the breathing stimulating effect of CO2. As a further sign of the aversiveness against CO2 the animals showed head shaking and wing flapping. The used settings of gas concentrations and stunning time in the system investigated lead to a very deep stunning resp. Killing of the animals. Therefore the debleeding cut could be performed late (chicken 44-55 sec., turkeys 54-90 sec.) after leaving the system without animals regaining consciousness. The stunning of turkeys with a mixture of CO2 and oxygen is an improvement according to animal welfare requirements because unnecessary pain and suffering, happening very often with electrical stunning, can be avoided. As far as animal welfare in chicken stunning is concerned it must be evaluated if gas stunning means an improvement because stress during the till now relatively long induction phase must be put into relation with comparably lower stress caused by hanging upside down and a fast and safe working electrical stunning unit.