I had a hen that was fine one day, the next she just sat and slept. Then, the next day she died. When I checked her, she had good color, size and she had laid this week. The only thing I noticed was she had lost some feathers on her belly and underside. Kinda patchy. The weather is cold here, and they are let out at least once a day to range, but are mostly in our coop. The are a mixed New Hampshire. All the other hens are fine, I have a Rooster I keep with them. They are under a year old.