[MAK]

We give well baked ground up shell for no particular reason other than we read we can - but I have no intention of weighing feed to calculate a % of any of their food intake - even if they can absorb Ca from ground up shell
I agree that if they range about they will pick up grit as needed The 3 cows we ate had quite big bits of rock in their gizzard and their bones were as hard as "the hobs of hell" - there is a saying for Robert's thread!