I'm kind of new to butchering chickens. I've done six, and for five of them, the crop was packed full. But the sixth was so empty I couldn't even FIND it until I accidentally ruptured it and only a little liquid was in there. Was that normal? I always thought they stayed full of grit. I haven't been giving my birds grit because they have a large dirt run so I assumed they got enough that way. Do I need to be giving them grit? She was a meat bird of some kind (huge, white, unknown breed) and young enough she didn't have eggs inside her, if that's relevant. The other birds I've butchered have all been roosters.