[otis pony]

One of my girls has been picking feathers from the others, leaving one girl with a bare neck.  When or will her feathers grow back? 
I've started giving the occassional pouch of cat food, improved the fresh greens intake and have even tried them with Happy Hoof horse feed that contains biotin in an effort to stop her, fingers crossed!

[Casey76]

Her feathers will grow back... but it might not be until her next moult.

Having said that, I think traumatic feather removal is quite quickly replaced. four weeks after having nearly all her neck feathers removed by a marten, one of my hens is now shoing a lot of new quill growth