I have always wanted to prove that slitting the throat of an animal is not as painful as it seems. (I am not a Halal man, still I could defend it and probably it is more kinder method than ramming bulls against a huge saw blade where some of these animals are still half alive despite stunning them, and they are hung upside down from just one leg! )
The pain any animal suffers during the slitting process is no more intense than say accidentally cutting your finger or part of your arm or you leg with a sharp knife.
Sometimes we do not even feel anything when we have cut ourselves, we only realise when we see blood oozing out! and most of the time we do not scream when we cut ourself, we shout a curse! we normaly say Oh ****e! I have just cut myself!
So now, if you take any animal, even if you were not going to slaughter it, you try to constrain it, and lead him away, it will protest and cry out, unless that animal knows you and trust you and it knows that you are the owner and you feed him daily.
so, any animal if you then force it to lie down, you push it, you grab his head and pull it down, it will strongly protest and cry out loud, it will know something is up!
So when a group of men surround a poor animal and they are all trying to push and pull him, with or without ropes tied awkwardly around its neck, and may be around its legs and push it over on its side to be slaughtered, the animal starts crying there and then, it is not crying because of any pain yet, but the animal's natural instinct tells it that something is wrong, he starts fearing something is coming up!
and when his throat is finally slit open, he simply bleeds to death with very little pain, his brain dies pretty much quickly due to lack of blood and even if his eyes are wide open, he sees nothing but darkness,
In humans when they have blood circulation problem, and their blood pressure suddenly goes low, on getting up they often feel dizzy and they loose their vision for a split second, a dark shadow appears in front of their vision, until the blood pressure climbs up again.
So the animal being slaughter simply feels a very slight pain, though it is distressed already for being confined and tied up, it struggles to escape but cannot, it start to cry out loud,
eventually that animal dies through loss of blood and not through torturous pain but some light pain, the sharper the knife the less drag on flesh, and lesser the pain.
If you took the same animal and took it to an operating theater, and under general anesthesia had two radio controlled valves implanted in his jugular veins or arteries, each of which leads up to his brain, and then after implanting this radio controlled valve, the animal recovers from his operation and is then left to graze normally in his choice of field for a few days, like nothing happened to him.
While implanting radio controlled valves, the animal is also implanted with other sensor that monitors his brain activity and his stress levels, his heart beat. etc etc.
Some weeks later, observers secretly monitoring the animal send a command to close off those two main valves, the observers may then notice the animal did not undergo any distress, it simply laid down when it felt unwell due to lack of oxygenated blood reaching his brain, and it may either simply lay down, or fall off to its one side, his vision becomes darker, he may become confused and so might let out one or two cries, and simply goes quiet and dies a painless death, his stress levels may have gone up.
If as a man, you suffer a sudden loss of vision, for no apparent reason
(unless you knew that you got punched!) then your stress levels would shoot up! You would start wondering what is suddenly wrong with me!
same way the animal may still get stressed out, but not through pain!
so eventually as the valves are commanded to shut off the blood supply, the animal retires to ground, his brain sends signals that something is wrong, his heart rate goes up trying to compensate for loss of blood pressure. That is provided his nerves are still intact,
But in the end the animal does not suffer a horrific death, but people like me will feel always feel they were under intense pain, when the fact is they cannot be, so in my view, independent, not biased towards Halal either way, is the same as killing animals through stunning method, where animals are equally distressed and as they are prevented from escaping and pushed towards their final destiny, stunned and chopped off with big circular saw blades!
No difference really!