Of course you need to know what the medicine is in medicated feed to properly answer that. Check the label to see what it says the active ingredients are. The odds are really high it is Amprolium, but I don’t like putting my family’s health at risk on a probably.
If it is Amprolium and Amprolium is the only active ingredient, the USDA and Purina says there is no withdrawal period for eating the eggs. I’ve pointedly asked Purina twice if that means that you can continue feeding the Amprolium-medicated feed to laying hens and they just use that “no withdrawal period” quote without answering the question. My guess is that their lawyers won’t let them vary from that USDA language. I’m not a medical person so I won’t offer an opinion on how safe it is to continue feeding Amprolium medicated feed to laying hens.
Amprolium is not an antibiotic. It will not mess up any probiotics in the chick’s system like an antibiotic would. Its sole purpose is to restrict the Coccidiosis bug’s reproduction in the chick’s system so the number of Coccidiosis bugs don’t get out of control. The problems with Coccidiosis come when the number of bugs get out of hand.
After two to three weeks of continuous exposure to that bug, the chick will develop immunity to that strain of Coccidiosis. So if your chicks have had contact with the ground for three weeks they just about have to have that immunity and don’t need the medicated feed any longer. I purposely feed dirt from the run to my chicks a day or so after I put them in the brooder and feed them more as I go along so by the time they hit the ground they have developed immunity.