My chickens are just about old enough to begin laying eggs. They are between 16 and 18 weeks old ( Jersey Giant, Morans and Wyandot). I thought I would begin adding lay mash/crumble to their starter/grower. Would this be advisable? Also, the rooster eats the same food as the chickens and is healthy and beautiful. So.. I assume this is ok? Not sure how I would feed him separately.