Protein levels can be reduced once the major growth in the birds is completed. Toss a couple of handfuls onto their litter or on their range and they will love scratching for it. In the process they will do a nice job of turning over their bedding, keeping it dry and loose. The protein requirement, however, increases again during the annual molt when the birds are growing new feathers, even though egg production is lower. Poultry also need starchy food for energy.
Corn is a commonly used energy source.
As the birds mature they need less protein and more starch as is reflected in the layer rations. Make any change in ration slowly, to avoid stomach problems and diarrhea. Each bird will drink 2 or 3 cups of water a day and more in summer. Give them clean fresh water each day. No water for just a few hours can lead to dehydration, which can suppress egg production for weeks.