I have five Leghorn hens 9 months old now. We have had below zero temperatures for a couple weeks now. I had a 100 watt lightbulb in their small roosting area (enclosed and door closed at night). I noticed they were getting white tips on thier combs, so I put in a 250 Watt red heat lamp a few nights ago. I leave it on all day now. But now some of them are getting dark purple tips and white seems to be creeping down the tips of their combs. I put Vaseline on them, and if I squeeze (lightly) the healthy red flesh beneath the discolored tissue, the whole tip turns red. Does this mean blood is still getting to the tips and there is still hope? I have never experienced this before. I have pics, but I don't know how to attach pictures to my post.