Hi, Im new here and have some quesitons. We just got chickens in June, they are 4 years old, what they call Dommanecks. We are getting eggs, about 5 dozen so far. We are feeding laying mash only. We have no experience with chickens. We have a chicken tractor we keep them in. Im sure they need some grit...right. Can I just feed them crushed sandstone, its plentifull here. If I can just how much do they need and how often. We have 4 Dommer Hens and one Bantan Hen. Any help will be appreciated.