I need advice for frostbite on my Roo

[Chickens R Us]

I think its not only the extra light but the extra time its left on.

 

[Jakoda]

my chickies seem to have also gotten some frostbite Here it's been above zero the last couple of days,but low temps, I have good ventilation, no drafts, not windy, I loaded them up with vaseline (tho they like to get it messy

Their combs and wattles aren't "frozen" feeling, am wondering whats up