I have 4 Guinneas and 36 chickens 2 Roosters and 2 baby roosters...this is the only bird that looks like this! I have removed her from the flick.... the white stuff is Diatomaceous earth mixed with wood ash.... I have sprayed all coops with Permethrin spray.... any other ideas?
She's being plucked, mated (probably overmated) and may also be molting, it's hard to tell about molt in the photo.
I does look like there may be Lice Nits on the feathers in one photo, hard to see. I'd get a can of Permethrin based poultry dust, put it in a sock and use it like a powder puff to dust her all over, work the dust through the feathers down to the skin. Repeat in 7day intervals. While DE and Wood Ash are commonly used in dust bathing areas and may help with deterring an infestation, these are not that effective once a bird has a lot of Lice (or mites), once that happens, using a dust or other treatment is needed.
Any feathers that are broken, damaged, ragged, torn and those with the feather shaft still intact will not be replaced until she molts, so if she's not molting, she may be bare and ragged for a while.
You separated her out, is she sick? Being bullied or kept from food?
Being separated may be need to protect her from the roosters and cockerels and perhaps from the others if they are beating up on her, but separation also means difficulty with reintegration when/if the time comes. It may be better to leave her with her flock and move 2 cockerels (or all the males) for a while and give the hens a break.
