To make my life easier with different ages of chickens I just feed grower feed with oyster shell on the side. I have bought chick starter feed, a small bag, and fed it to the babies when they were not in with the others. But once they’re in with the others everybody eats the same food. I basically feed them enough fermented food that they can eat in about 15 or 20 minutes. I have heard about a quarter cup per chicken, but I never get that technical. I put a bunch out there and if there is still some left over by the end of the day that I know I gave them too much and I give less the next day. Some days they eat more than others, depends on the weather. But you will eventually get a feeling for how much they need.