Since I got chickens last autumn I knew I wanted to raise my chicks without Amprolium. I decided I would just have to jump in head first and do it! So when I had my first hatch, I was obsessed with making sure those chicks had all sorts of natural preventatives every day. I was careful that they weren't exposed to coccidia until they had been on preventatives for a while. I made sure the brooder was as close to germ free as I could possibly get it. All went great! Until I moved them to the coop... They were about 31/2 weeks old. One day I walked out to feed them, and one was dead. There was bloody poop all over the place! I had a cow.
Fortunately I had medicated feed and Corid (Amprolium, the same thing in medicated feed) on hand. I immediately put them on both and started praying the rest would live! They did, but I thought I was forever ruined on natural chick raising. Of course when my second hatch was born, I was determined to do better than the first time. I think I did. They are now free-ranging 7 week olds that have never been on medicated feed. (I should add that there was one time when 3 of them suffocated and I thought they had coccidia. They had access to medicated feed for about 5 minutes before I figured out what had really happened.) It's too early to tell if the method I'm using is really as effective as I hope it is, or if I just got lucky, but I wanted to put it out there so that it could hopefully benefit someone. It's very simple. If you have time to brood chicks, you have time to do this. It is a combination of things I found on the internet, things that simply made sense to me, and things I learned from people here on BYC.

1) Do not sterilize your brooder. I don't mean leave it nasty and never clean it, just don't bleach it or anything. A good wipe down should do the trick.

2) Feed the chicks kefir every day. If you aren't familiar with kefir you can learn about it here. Plain yogurt (no flavors) and spoiled milk accomplish the same thing. They contain probiotics which help maintain good intestinal flora. Seeing as coccidia is an intestinal parasite, you can see how this would be helpful.

3) Add dirt to their brooder. I get mine from underneath the roost in the chicken coop. The goal is to get the dirt from somewhere your chickens frequent. Older chickens naturally carry some coccidia in them, they have just built a resistance to it. That's why you almost never see a hen infected with coccidiosis. If you don't have older birds, dirt from your yard will be fine. It will probably have cocci in it as well.

That's it! It's as simple as that. If anyone tries this I would love to know about it and how it goes. If not, then I hope someone at least got some inspiration. :)