we found that homemade chicken tractors allowed us to protect our birds from predators while allowing them fresh grass and bugs daily. they don't need as much layer pellets as my birds in the coop and runs. you can also use them to isolate a broody or a breeding pair or trio. i call them scratch pens and they give the chickens more exercise. since we have a garden, the chickens get all the scraps all summer long and we feed them turnips and greens all fall usually until real hard frosts in december. since this winter is mild, we still have green grass in the yard for them. you can also buy cheap scratch feed and mix it with layer pellets to stretch it. only feed oyster shells when their egg shells get thin and soft.