Just since the snow has started and I have changed the water feeder to nipples instead of free drinking I have noticed that my two BO roos have started to show black on the tips of their combs.I thought at first it might be frost bite, but none of the other birds seem affected and after reading some of the posts I think they might not be getting enough to drink with the nipples and they could be dehydrated. I have started to put the water back down so they can get a good mouth full, but one is now limping and I'm not sure what to do. Any suggestions please.