Show Birds and Frostbite

[Fanci Feathers Marans]

I honestly haven't done much research on the subject. Any kind of moisturizer should work. It can probably get a little tedious doing it every night, though. Maybe confine the roosters to a different house that is warmer. Maybe a chicken tractor that can be moved close to the house?

 

[I Love Layers]

It can be a pain. I live in ND and show LF Cochins, the females combs and wattles are never damaged, but the males can be.
A few things I have learned
1) Try to invest in smaller waterers, so that there is less of a chance of the bird getting its comb wet. I have wanted to try the automatic cups. However now I use small purple dishes that hang on a skinny piece of flat iron in the conditioning cages.
2) No metal feeders or waterers, especially waterers(unless heated). They will cause the comb to become frozen, I found this out with my layers, especially if the metal is wet.
3) Give the birds plenty of bedding, I like to fill one area of the coop full with straw, for them to nestle in and keep their body heat in better.
4) If a bird does get water on its comb and it is below freezing get the water off. Blow on the comb, and once most of the water is off put your hands over the comb for a short period.

I personally don't like vaseline, my experience with it is that it actually freezes onto the birds combs.
If you can just insulate the roof of the coop or one side. I insulated 2 small spots in the roof and inbetween 3 studs and you can easily tell the difference in the coop