I live in North Central Texas. On Thursday it was 72 degrees, today it's 25 degrees in my non insulated well vented coop. I have a brooding silkie sitting on a clutch of eggs, 4, 8 week old easter Eggers and 6 adult chickens in my coop. It's going to be below freezing at night for the next 3 or 4 days. My question is should I add a heat lamp at night? I can put it on a timer.