I bought a group of 10 mixed chicks in mid-April (so about 5 months old). All have been healthy but about 3 or 4 weeks ago one of the females just seemed sort of "off". She has been tired, lethargic, and has dropped weight. She looks basically normal. I don't see any physical sign of illness. They just were weened over to layer ration as they have started laying eggs....same brand of feed as their chick feed. They are on sawdust with 3 laying boxes and a roosting pole. Housed at night and released into a fenced in yard during the day. She has recently seemed to have more energy, but is still a little less active than the other chickens. She looks like a "mixed breed" chicken...a bit like a golden wyandotte and white breed cross; basically brown with white feathers around her head and neck area. I don't really have a separate area I could put her in at the moment, but if really necessary, I could probably think of something. Any suggestions or basic aid I could try? If she doesn't pick up some weight, I'm afraid I may have to cull her rather than see her suffer through a cold, northern winter. Thank you for any help.