I would think that'd make it easy for the chickens to slip and hurt themselves. If you have mites I'd use permethin instead, that'll kill them outright
I use organic cold pressed neem oil on my roosting bars (tree branches) and reapply once every week or two or three It actually kills mites, and it isn't slick, I'm not sure if coconut oil would work for your intended purpose. This is what I use