Alternatives to CO2 stunning successfully tested

The stunning of slaughter pigs using CO2 is controversial. Therefore, the FLI has tested alternative stunning gases for practicality and animal welfare. How can pigs be stunned more animal-friendly for slaughter? This question concerns the meat industry. Animal welfare activists have been criticizing the conventional stunning of slaughter pigs with CO2 for some time. Alternative gases such as argon and nitrogen are considered less burdensome alternatives. However, there are concerns about their efficiency in stunning and possible effects on meat quality. The research project TIGER of the Friedrich-Loeffler-Institut (FLI) has examined this in detail and now provides important results. CO2 stunning Advantages: deep and long-lasting loss of perception and sensation, driving of animals to the stunning facility in groups possible, good meat quality Disadvantages: hyperventilation and breathlessness before loss of perception and sensation, aversive reactions (e.g. escape attempts, hyperventilation, vocalization) before loss of perception and sensation, irritations in nose and lungs due to the formation of carbonic acid Animals show fewer and shorter defense reactions. For the approved animal experiments, the researchers used a new, patented fumigation technique in the dip-lift system. Cameras recorded animal behavior before and during stunning. The loss of ability to stand occurred after about 20 to 24 seconds. Until then, pigs showed less frequent and shorter aversive reactions when using nitrogen and argon compared to conventional CO2 stunning. Less hyperventilation or escape behavior was observed. However, the stunning time with nitrogen and argon was about 40% longer at around four minutes compared to CO2. Although differences in meat pH were noticeable, they were deemed marginal. Gas mixtures therefore did not cause any relevant differences in meat quality. Alternative gases are slightly more expensive. Further investigations are necessary to apply the technique in high numbers of slaughters in conventional slaughterhouses, as they use a different technique to introduce slaughter pigs into the gas atmosphere. This usually involves continuously running lifts for groups of animals. However, initial technical tests were promising. The tested gases are slightly more expensive than CO2, but the longer stunning time must be considered. This could increase overall costs by up to 1 cent per kilogram of meat. The research project showed that nitrogen and argon can be used for stunning under commercial conditions. The reduced defense reactions improve animal welfare, but the longer stunning time leads to slightly higher costs.