I have never had to put a chicken down yet. I just let them live out their days and die naturally when their time comes. Many methods of killing chickens seem inhumane and painful to me.
It is great when you can just let them live out there days, and die at peace.
But the problem is, it doesn't always go like that.
I had a goat that was 12 years old, and she was one of my best friends. She had a very good life, but on her last day the thing I wanted most for her was just for it to be over.
If I could have, I would have put her down with my own hands, but I didn't have any way of doing it.
She died later that day; taking her the hours drive on bumpy roads to a vet would have been even worse. I now have a captive bolt pistol for it, if it ever happens again.
It is the same with chickens, I put a BO down last week because it seemed she had a brain problem, and wasn't 'all there' and not coming out of the coop any more.
I had to leave for a few days, and couldn't physically take her out every morning.
Instead of letting her starve by herself in the coop, I chose to give her any easy way out.
So do think about it, would you prefer to die in a dark coop all by yourself, of thirst and hunger, or in a sunny paddock with full tummy and a breeze on your cheek?
I know what I would prefer.