This is our first year keeping chickens in the winter. We have enclosed their coop so no drafts can get in, but left openings in the top for ventilation. They have a dry layer of sawdust and hay in the bottom and also have a wooden roost. I've read that in cold weather you can put vaseline on your chickens combs and wattles to help prevent frostbite. My question is how often if at all should I do this? We live in Northeast Pa and we are reaching the coldest temps we've had so far. Our nights are averaging around 20 degrees. I just want to make sure that my chickens are going to be okay and would hate to see them get frostbite. Thank you!