I think the high humidity, cold and big combs makes it difficult to prevent. So moving to warmer climate, smaller combs or climate controlled coops. I'm going with smaller combs. The previous roosters have lost most of their combs. The part dark Cornish have some frostbite but nowhere as bad as the straight combsNot much I could have or would have done differently. Just one of the leghorn gals is damaged so maybe I should watch where she is roosting to see if there's an issue there.