You could easily look it up.
And I'm sure some of them don't feel as much pain as others, depending on the person doing it and I know that there are some horrible stories from slaughter houses in America, but they slit the throat, making sure not to touch the spinal cord. That alone has to be pretty damn painful. Think about getting your throat slit.
They have to let the animal bleed out which means it may or may not be dead or not suffering on the initial swipe. If they didn't cut it correctly, they may have to cut it a second or third time causing more pain.
So how long they're lying they're suffering you don't know. Just because the animal is quiet doesn't mean it's not suffering.
Complete drainage is required because blood is prohibited in Islamic law, and its removal is believed to improve meat hygiene.
The head must not be cut off completely, and the carcass cannot be skinned or butchered until the animal is completely dead. (thankfully)
Prohibited Areas: The sciatic nerve and specific blood vessels, particularly in the hindquarters, are not consumed.
But seriously, look it up. I knew about some of it, but not that last part. It's not hard just type it into your search engine.
But in all honesty, if we're going to complain about killing any animals for meat we must be consistent. But I would really rather them be stunned, which apparently they can do in halal but don't have to.
I don’t get enough credit for the things I manage not to say.