much thanks! i'll add a bit to their food, I am more concerned about the additional calcium for egg production than the grit....I hope my thinking is right...please advise if otherwise...I live at about 7500' elevation in the valley at the base of pike peak, so under the natural mulch of the run, it is all black dirt and crumbling mountain..mostly granite. I figured they get all the grit they need from their local environment. we have 5 chicken at this time, plan on expanding to 8-10 this next spring and our run is about 33' long by 17' wide by8 to 12' high.(coop is within these boundary). Actually expanding the coop right now - kinda excited i am utilizing a large hydroponic drain table for the roof, to catch rain and snow which will drain into their water buckets then overflow out to the run.