Our 4 chickens live in an enclosed run with chippings on the floor - they had grass for the first 2 days and then they mullered it so we put chippings down to help reduce the mud bath.
But each time I open the door to fill their food or whatever they desperately try to peck at the bits of grass in the doorway, yet when I throw cabbage leaves or similar leftovers for them they don't get so excited - do they need green or is it just novelty?
I can't free range them even for a few hours as our garden isn't secure enough, and the neighbour doesn't like them :(