I feel bad I didn't use vit/min sooner, but they free range almost all spring, summer, and fall. Oh well, can't hurt. How often? I'm a minimalist, I really prefer them nibble what they need from gardens, bushes, trees, and all that natural unmanicured green goodness the Earth has provided me with. And what eats it, in the case of the ducks and turkeys. None of my chickens will ever get to be free again. I've lost too many to human preditors. I'm gonna put a lock on my new chicken coop. They can still eggs, but the birds stay **** it.