Just an update on the new abattoir at Leicester Quality Meats. I visited the abattoir a couple of weeks ago to see the operation.
This is one of the modern and welfare friendly abattoirs in the country. I am a consultant for one of the largest free range producers in the country and ex officer with the MLC. I would not hesitate to recommend the facility to Smallholders. The issue about CO2 is this. The gas stuns the pigs only, it is prefered to electrical stunning as the pigs enter in small groups which keeps them calm, they dont have to be chased around by a guy with stunning tongs, or get forced single file up a race with electric goads.There is no squealing shouting and yelling and the staff are respectful of welfare issues. I have visited most of the abattoirs in the UK and this is one of the best.
The owners are farmers themselves.
Carbon dioxide stunning is a contentious issue.
The problem is that pigs, like humans, can sense high levels of carbon dioxide. Subject humans to a significant increase in atmospheric carbon dioxide concentration and they will experience respiratory distress and some will even suffer from panic attacks. The evidence suggests that pigs suffer in the same way before losing consciousness. Sure in a 30% carbon dioxide stunning environment the effect is pretty brief, perhaps 30-60 seconds, but you do not get the same welfare issues when you use argon or nitrogen gas, or a proper electrical stun.
Sure electrical or mechanical (in other species) stunning does not look or sound pretty but done properly loss of consciousness is instantaneous. A lot of the stigma involved with these methods stem from people being drawn to poor examples of stunning (eg; the cow that is incorrectly captive bolted several times before a good stun is achieved) or simply misunderstanding what they are seeing (eg; to an outsider an unconscious pig exhibiting tonic-clonic behaviour may be perceived to be conscious and in significant pain).
As for good pig handling it is dependent upon staff expertise and pig temperament, not the type of stunning equipment used.
/tangent
Thank you to everybody who compiled the list of good abattoirs, there is a long list of current and prospective vet students that are looking for placements where it will be a lot of help.