Well I do have other birds. I collected the soil and sand from an area in my yard but I let my chickens free range sometimes so they do have access to it. The pine straw has definitely been exposed to other birds. My chickens like to go to that area and turn it up when I let them out. I didn't know if this would hurt them by introducing cocchi to them or if it would help by possibly introducing it to them early. My understanding is thats what the feed does and helps them build a resistance up. Im doing more research now.
Yes it will help them build up a resistance. But it's a long time debate if this is good or not. Some say feed medicated to keep them safe and others say to let nature take it's course. Personally I don't do medicated and never have had a loss. Many think that is a risk though. So it falls into personal beliefs/preferences. I also don't vaccinate my chicks born here as want to breed healthier strains even if that means losing birds.