> The principle of gas stunning or Controlled Atmosphere Stunning (CAS) is that animals are exposed to a high concentration of CO2, CO2 mixed with inert gases, or inert gases only
> Carbon dioxide especially at high concentrations (above 40%) is pungent and painful to inhale and leads to a highly aversive response involving very loud and high-pitched vocalisations and vigorous attempts to escape from the gondola and the exposure to the gas, including scratching other pigs vigorously with the claws of the front legs and trampling of pigs that have become recumbent. Furthermore, during the induction phase animals will show increased breathing and gasping associated with signs of breathlessness (“air hunger”). Induction of unconsciousness with CO2 stunning does not immediately induce unconsciousness and the process is associated with fear, pain and respiratory distress (Verhoeven et al., 2016; Beausoleil and Mellor, 2015), lasting from the start of exposure to CO2 until loss of consciousness
> Ventilator shutdown involves locking a flock or herd of animals in a building and turning off the ventilation systems. As the temperature rises and gases inside the building accumulate, the animals suffocate to death, usually over a period of many hours.
Rising "gases" is CO2. Suffocation by co2 is one of the worse death because that’s how the body knows he needs to inhale. Most of the other gases will kill you without you noticing. but forcing a subject to breath co2 is absolute torture.
Images talk by themselfs I guess, here’s 4 hour of the process which is legal in most of the world beware, not a fun video : https://www.farmtransparency.org/videos?id=2d2a5ec62b
UK replaced CO2 with other gaz[0] and the pigs dies as a sleep. The price difference is a needle.
0: butane or nitrogen IIRC but someone more knowledgeable may correct me.