Chicks don't appear to like cold hands, so try warming your hands before handling them. In respect of mercy killing if a chicken is ill, sometimes its the best thing to do. I've only ever had to do one mercy killing, when a fox badly injured one of mine. For me, I had undertaken a course on dressing and despatching. Not an easy course to do if you are squeamish but such a useful skill to have. It certainly made it easier for me as I was confident that I was making the quickest and least painful death I could for her.