Hey guys! I currently feed my two month old flock - two pullets and two cockerels, I think - a home made mixed grain diet.When the hens start laying, should I mix some limestone flour into the feed for calcium, and let the cockerels eat it too, or should I offer it seperately? And also, should I be using limestone flour, or oyster shell as most people seem to do? And how quickly will they get through either source? Thanks!