No feather on belly or rear....

[jschway]

Noticed this when I was doing some yard work... Should I be worried? All the other hens are fully feathered.

 

[Karhog]

Could be that she is laying on the area when sleeping or maybe she is feather plucking. I would up the protein a bit in case as theycan pluck feathers to get extra protein. Meal worms are great for a bit of a boost.
It doesn't look sore to me. Is she eating and drinking ok? If she is otherwise well, i would just up protein and observe...check she isn't being bullied. Though I would have thought the feather loss would have been more around her neck or head if that were the case