According to the Council Regulation (EC) No. 1099/2009 and the German law on the protection of animals during slaughter and killing, animals shall only be slaughtered after stunning so that they do not experience avoidable pain and suffering. Gas stunning with carbon dioxide is one of the most commonly used stunning methods for slaughtering pigs. In recent years, there have been several studies referring to an insufficient depth of anesthesia and to aversive behavior as conscious reactions due to exposure to gas. Ways to reduce this aversive behavior by varying the concentration of carbon dioxide and by using alternative gases as well as the question concerning the time to loss of consciousness and sensibility during gas stunning are currently discussed.
For assessing welfare aspects during stunning of slaughter pigs with carbon dioxide and alternative gases (argon, helium) different physiological parameters are investigated. Under the effect of different stunning gases and by use of a whole-body plethysmograph pulmonary function which is crucial for the effectiveness of anaesthesia is examined. In this context, respiration can give indications of different severities of aversive behavior. In addition, brain functions are monitored in order to determine the time of loss of consciousness and sensibility. From the point of view of animal welfare, the determination of the onset of unconsciousness and sensibility is absolutely essential for assessing defense reactions and excitations.
This study is funded by the B. & C. Tönnies Forschung and is carried out in cooperation with the Max-Rubner-Institut in Kulmbach.