Lethargic hen with feather loss
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She may be sick, and being pecked by others. I would try to get her droppings checked for coccidia and worms by a local vet. You should be able to see whether or not she has lice or mites on her skin, especially around the vent. That would require something like permethrin or Sevin dust to treat both chickens and coop. At her age she could be suffering from a reproductive infection or egg yolk peritonitis. Those and other conditions are common in hens 2 and older. Check her crop to make sure that it is not impacted, and is emptying by morning.