I have 2 flocks of 5 with a roo in each. One flock is coturnix and the other are jumbos. Their eggs are starting to look a little rough so they definitely need more calcium. Do I need to give grit and oyster shell or would oyster shell take the place of grit? Is there a way to grind down oyster shell so it’s small enough for them or do I need to buy something special? We only have chicken supplies available locally. It’s even hard to find feed for them consistently but I’m working on trying to find a recipe and just have it mixed. Thank you!