I had 3 roosters and 5 hens. They are about 5 months old and have seemed very healthy until friday night. Friday night, my son went out to check on them and found 2 of the hens dead and two more very lethargic. The roosters and the other hen were a little slow acting. We brought them in the house on the heated back porch. The two sick acting hens died, but the other 4 perked up. Their poop was runny and yellowish and they smelled terrible so we put them back out in the coop saturday morning. The coop is 4' x 6' by 6' high. It has a box like steeple on top with holes in it for ventilation. The coop walls are insulated and have wall board over the insulation. It is not drafty. We have a 250W red light hanging a few inches from the ceiling. It's cold here ~10 F. and about 22 F in the coop. The combs on the roosters are dark now. We bought some Aureomycin chlortetra-cycline HCl soluble powder and have been giving it to them in their water. I was going to buy a heater tomorrow for the coop, but there are MANY postings on this site that say they don't need heat. Are they freezing to death or are they sick?