I started my coop in early spring with 6 Red Comets and a Barred Rock rooster. This winter when the weather got cold the hens stopped laying eggs and shortly there after my rooster died. I received two more Barred Rock roosters just before the new year. The first one died about a week ago and the other today. In all they don't look like they were bit, pecked at or hurt. All feather seem to be intact. It looks like they just fell over and died. My Red Comets don't seem to be effected by what is going on other than no more egg laying. I use straw in my coop when I first started and had the idea that shredded paper would be a good supplement in the coop also. After the second rooster died I thought that the paper my be having effect on the coop so I removed all paper and straw and added fresh straw alone. A week later my last rooster died (today). The chickens have a 6'x6'x6' coop with 4 nesting boxes access to outside and a fenced area of about 64'x 36' area to be outside. Any ideas on what might be going on? They are being fed hen and chick feed from Southern States.