Can't say Im having problems with the Breda's. We've had 0 degrees weather in NJ the last 2 days. They didn't come out of their coop though, where I had a heat lamp hanging. My Barnevelder rooster has a little purple in his comb from frost, but the Breda's seem to have weathered it well. Can there be some other cause? Weird that with 70 chickens all together only the Breda's died.