Hopefully the girls will be out by tuesday, but while they're still inside I've been "salting" their food with grit. They've graduated to chicken grit. How long does grit stay with them before it's ground down or passed? I change their food out twice a day, and they get 1-2 pinches of chicken grit sprinkled on their food with either some steel cut oats or grapenuts cereal for variety. Is that enough?