One of the problems with raising turkey poults on the ground is cocci. That's why I always tell people to be prepared to loose some along the way. Not just from that but they can get stepped on, get seperated etc.
Medicated feed doesn't prevent cocci. It's a low dosage of amprolium and that allows them to get a very mild case and build up an immunity and it does work. Medicated feed is all we feed our little ones. When I have hen raised I confine them to a smaller maturnity pen. It keeps the poults closer to the hen and for each batch I add a layer of fresh sand to cover the ground a couple inches deep. It's still possible they can catch it but the chance is reduced from the new sand.
Steve