i cut a piece of sod, flip it over and put it directly in the brooder. I've read that the chick's antibodies are highest in the first 2 weeks of life. In a natural broody situation, Mama broody would have those babies scratching around in the barnyard within several days of hatching. They'd also ingest some of her feces, which would also help with their immunity. There have been studies done which show that chicks brooded on litter which has had previous broods on it, or litter from the coop have healthier immune systems, much higher survival rates. And, yes, Meep Beep, I can assure you that my chicks do have cocci in their guts, as most likely all birds do, as well as a lot of animals. But a healthy immune system keeps the flora in the gut balanced so the bad guys don't outnumber the good guys. There is no one right or wrong way to raise chicks, the important thing is to make informed decisions.