In a backyard setting, they are entirely unnecessary and there are other ways that prove more effective, and with less long term ramifications than using a coccidiostat, to keep chickens healthy. I've never fed such a thing to a chicken and chickens were raised for thousands of years just fine without the use of them...it's just the commercial use of them, where animals are crowded into unhealthy living conditions that has necessitated the need for such things in the first place.
I say good riddance. People will have to just start stepping up their game on flock management.
I say good riddance. People will have to just start stepping up their game on flock management.