This is my first year with chickens and we have 9 (4 Barred Rock, 3 Isa Brown, 2 Buff Orp) who are about 8 months old. My question is whether or not to keep their coop door closed today. Their coop is a converted shed about 10'x10', insulated, with deep pine shavings on the wood floor. My husband made a hardware cloth screen door under the big door, and we have always opened the heavy door and kept the screen door closed for light and ventilation. Today it will struggle to get to 0 degrees F, with 20-30 below wind chills here in northern MI. Do I leave the big door closed all day? They have a pop out door which is closed because too much snow in their run, and a vent near the ceiling. There is not much light if the big door is closed. Worried about them today 
