I have 8 year old hens that are currently eating Nutrena Layer 16% and I am about to integrate 10 twelve week old chicks into the flock. What is the best way to feed them so that the hens will get enough calcium and the little ones won't get too much. I have been feeding the younger ones Nutrena Chick Feed. The feed stores around here carry Country Acres, Purina, Nutrena, and Dumor. What is the best way or feed to feed a multi age flock?