I think that, in using ACV for cocci, it works better as a preventative. Cocci is normally present in every mammal's bowel flora..it only becomes dangerous when it has an overgrowth. This can happen in cases where the animal has had a wide spectrum antibiotic dosage, scours, etc. All these things can create an environment that has diminished the "good" bacteria that are present in the intestines that help with the digestion of our foods. These good bacteria also hold back the growth of the bacteria such as e.coli, coccidia, salmonella, etc.
All vinegar and other fermented foods do is replace and replenish our naturally occurring good flora. Cocci isn't "contagious" as one would imagine, as it is present in every farm animal and in the soils of all farms....it is when the balance of existing microorganisms is upset that problems appear. Thus why a good deep litter system promotes good bacterial growth that holds in check the bad bacteria...it actually inhibits their growth.
When people claim that a chicken they brought home gave their flock cocci, I always shake my head....their flock already had cocci, but the new chicken may have been carrying a heavier load of cocci bacteria than their coop, soil, flock can handle as they don't have enough of the good bacteria in the animal, in the soil, in the coop to combat the bad. Hence the exact reason that the more you bleach and kill off all the good bacteria, the more you have to deal with the bad...they grow quicker, particularly without the good bacteria inhibiting their growth.
The whole premise of raising a flock with good immune systems, with healthy digestive tracts that carry a full load of healthy, good microorganisms, with good exposure to air, light, fresh soil.....all that is preventative. It naturally inhibits the overgrowth of dangerous bacteria, both in their environment and in their bodies.
So...if you are looking for ACV to be the cure all when you find yourself with a cocci overgrowth..sorry, it won't "fix" it. Fixing it should have started before you ever got an overgrowth and expecting the ACV will correct poor management of soil, coop and flocks will be a failed experiment.
What causes that overgrowth?
Overstocking chickens in a coop, run or on range will cause an environment that promotes the conditions for an overgrowth of dangerous microorganisms.
Giving medicated feeds and slopping the antibiotics or anti-protozoal meds to your chickens at the first sign of the sniffles.
Wet, barren runs with concentrated fecal matter in the soils.
Bleaching every surface to rid it of ALL germs..particularly the good ones.
Deworming often(yes, many deworming agents have a mild laxative action so that the dead worm load is expelled and doesn't clog up the works).
.....all these things that I see discussed on this forum on a daily basis and are touted as "good" animal husbandry are the very things that are promoting these types of illnesses. And their solution? To do more of the same...bleach, medicate, isolate birds in small cages/pens, etc. Can no one see the vicious cycle?
All the things I do not do...and I have never had any illnesses in my flocks all these years. I don't think that is chance, luck, anecdotal, an exception or anything else people claim. It's called preventative management and it really, truly works.