One of my pullets just started laying and the other one is very close behind! I will start them on layer feed as soon as the other starts laying. I have a 50-pound bag left of chick start-grower so is it ok to mix it with the layer pellets?? Also are eggshells ok to feed them as an extra source of calcium, will they promote egg eating? I can't go to the feed store to get oyster shell. Is an extra source of calcium necessary?