I had a hard time with this as well since killing animals is not in my nature. Out of all the ways my imagination could come up with to youthenize rodents........as sedistic as it may sound...I find it the quickest and most effective to give the rats head a good swing into a strong corner wall and while I have a few seconds before it comes to (the wack doesnt always kill the big ones), I just hold the tail with my left hand and put my other hands fingers behind the head on the neck and proceed to stretch the animal out with the purpose of dislocating its spine as much as possible. Rats are stiffer than mice so you kind of have to do it slow and sturdy while moving the tail end from side to side to realy get those vertebre to let go. The more vertebre separated the less likely it will move and it will die quicker. Dont be fooled by big rats. Theyre fairly hardy.
Dislocation may not be necessary if you hit it against the wall hard enough. But for a larger rat that amount of force usualy draws a quirt of blood or two out the nose so dont do it in a nice area of the home unless you want to wipe blood off the white walls. All joking aside...your chances of making a mess arent likely. Just stun it with a wack and pull its spine apart. It takes some getting used to but its quick and relatively not messy.
I know it sounds gross but the cycle of life is what it is and Im to the point where I feed so many snakes now I dont have time to waste thinking about it.
If you prefer spending more time suffocating it thats completely up to you. What ever floats your boat realy!!
-----
Without INTEGRITY and HONESTY what else have you!
Brendan Saffron