I always feed non medicated feed. Keep them clean and dry in the brooder. After they are a week or two old I go out with a shovel and dig up clumps of sod, around 4-6 inches in diameter, about 4 inches deep, pick a clean spot with some good vegetation attached, dandelions come in handy, and put these in the corner of the brooder for them to pick and dig at, replace as necessary.
As soon as your weather allows I than take my outside for the day if it's warm enough in a temporary pen, with food, water and shade. By the time mine are 8 weeks I either move them out to the shed if they are large fowl or they begin to spend the day in the bantam run if they are bantam, in their confinement pen for a week or so than I start letting them out. Usually by this time the ground has dried out and the risk of them getting cocidiosis is zero. They have been exposed in small doses to what's in my soil when the stress on them is low. I personally have never had cocidiosis in my chicks.