Should I be giving my hens grit and oyster shell, or is oyster shell enough? I've heard conflicting advice on whether oyster shell is a substitute for grit. We just started putting our chickens and a small chicken tractor for a few hours a day, and the grass is pretty rough (early spring in Massachusetts). I'm getting a lot of cecal poops, and it makes me think that maybe the oyster shell is not enough and I need to add some grit. Thanks!