Those that say how quick and humane killing livestock is have never been to a slaughterhouse. I have, and you can see the fear in their eyes. Then they (cows) are put into the stalls with their heads secured and hit with the pneumatic bolt in the head. This doesn't kill them it just disorients them. Then the blade comes and ends it all.

Smaller livestock don't get the stall, they get chained up and hung before they get the bolt.

If I had my choice I'd take an arrow to the boiler room that I didn't know was coming and by the time I realized what happened I was just about gone over being prodded through a maze and into a stall where my head was stabilized (like in a guillatine) or hung by my feet so I can take a bolt to the head before having my throat cut. That's just me though.