WOW! -40 F!
What are you feeding them to keep warm - turbo jet fuel?
Sorry, I'm gonna catch R2elk's wrath for this, but I cut heat lamps on when it gets to +20F around here, and when the temps flucutate by more than 50 F for a day or so, with the more and more erratic weather we are getting. So if it goes from 80 F to 30 F in two days, I will cut the lamps on at 30 for a day - the temp usually bounces back to a more gradual seasonal decline after a hick-up.
Oh, your bids just sent me a text saying I should post that all this is essential for their survival but, I dunno, their are not contributing enough to my campaign...