After treating with corid
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I can only get medicated feed so they eat that while on Corid if I have to treat anyone, which I really haven't had to do in awhile. You can do either way and it won't matter. You'll still have to watch for signs of cocci relapse, on medicated or non-medicated.
Basically, until they are around 12-13 weeks old or so. After that, you rarely see cocci because by that age, most have developed a good immunity to whatever oocysts are in your soil.