Hmmm... I have wondered about whether slitting the arteries with a sharp knife or decapitation is more humane... The latter isn't necessarily as instant as you'd think. Chickens in particular seem to have a lot of functionality controlled by their brain stem. There's one chicken that lives for 18 months without a head . He just never died, so they started feeding him by putting grain in the exposed esophagus. Ironically, he died from choking. My point is, in most cases what they are dying from is blood loss, not actually being decapitated, so slitting the throat with a very sharp knife (the sharper the knife, the less you feel it) might actually be much less traumatic... Especially since being hung upside down seems do kind of make them zone out, like flipping a sheep on its butt or putting a lip twitch on a horse. If you leave the windpipe intact, they can keep breathing and just go to sleep from blood loss...
As far as steers, goats, etc... I think it is much better to stun them first or shoot them in the head. It's obviously a lot faster and less stressful, especially since I think they pretty much always slit the windpipe so the animal chokes and suffocates, as well as bleeds out. I would certainly never slit the throat of a conscious steer. It would probably be better to stun the chickens first too, honestly, but seeing as their heads are so tiny I imagine this would be much more difficult, so people usually don't bother.
Disclaimer: I'm just conjecturing from what I have read - I have yet to gain any first-hand knowledge here.
As far as steers, goats, etc... I think it is much better to stun them first or shoot them in the head. It's obviously a lot faster and less stressful, especially since I think they pretty much always slit the windpipe so the animal chokes and suffocates, as well as bleeds out. I would certainly never slit the throat of a conscious steer. It would probably be better to stun the chickens first too, honestly, but seeing as their heads are so tiny I imagine this would be much more difficult, so people usually don't bother.
Disclaimer: I'm just conjecturing from what I have read - I have yet to gain any first-hand knowledge here.