Cluckin’ Good Oyster Shell provides additional calcium to increase egg shell strength for layers. Oyster shell is not a substitute for grit. Calcium is absorbed by chickens to build strong egg shells where grit stays in the gizzard to contribute to digesting whole grains and oyster shell.Begin to offer Cluckin’ Good Oyster Shell to your hens when they are nearly laying, approximately at 18-20 weeks. Oyster Shell provides supplemental calcium to ensure strong egg shells. We suggest offering Cluckin’ Good Oyster Shell in any of the following ways; free choice in a separate dish or tossing on the ground in their coop area to encourage natural scratching behavior. The birds will self-regulate and take what they need.