My rooster, Dolittle, got frostbite when the temperature dropped to minus 20 here in Vermont. The hen house was about 17 degrees. I have a heat bulb in there for weather like this but it just wasn't enough. Most of his comb was black.
Dolittle and I are very close - he's 9 - and all he wants from any person is a hug. Most of you will chuckle, but I brought him into the laundry room and set him up in a dog crate. I let him out to walk around as well.
In addition to his regular food, I fed him protein - plain shredded steak, waffles soaked with egg yolk, oatmeal, and fruit - blueberries,apples. I also ground up a 1/4 of a baby aspirin twice a day - thought this would help with circulation and pain - and squirted fish oil for omega 3 on his food. (You can chuckle now). I put triple antibacterial ointment on his comb twice a day. It did start to blister, but I let them break on their own. The danger of frostbite is infection.
Miraculously, in a week the color was coming back underneath the dead skin and scabs - quite ugly but not infected.
I brought him back with his girls when he was healed and they gradually picked off the dead skin.
With the exception of one tiny tip, he's back to his handsome self ! We were very lucky.
I should add that at the first sign of infection, don't wait - see the vet.