I am very very much a probiotics-pusher but I would not chance it right now. Nothing but crumbles and Corid water for the duration of the treatment and when everyone is better (when treatment is done) then I would put ACV in their water....starting with one teaspoon per gallon and working it up over time to a tablespoon per gallon. And (my preference) I would keep them on starter crumbles with Amprolium. It's not antibiotics and they may really need it down the road. But for now I would let the Corid do it's thing and not risk interference. I do believe there are vitamins also in ACV.
Here we go. I just googled this. So you don't want to
Substances in apple cider vinegar
Scientists have measured ninety different substances in apple cider vinegar such as thirteen types of carbolic acids, four aldehydes, twenty ketones, eighteen types of alcohols, eight ethyl acetates etc.
It also contains important minerals, trace elements and vitamins (as listed underneath) as well acetic acid, propionic acid, lactic acid, enzymes, amino acids as well as roughage in the form of potash and apple pectin.
Vitamins
Vitamin C, Vitamin E, Vitamin A, Vitamin B1, Vitamin B2, Vitamin B6, Provitamin beta-carotene, Vitamin P.
So that's a nix. Thiamin is Vitamin B1.