Purina Organic Layer Crumbles with the Oyster Strong System provide a balanced and complete diet with 16% protein for feeding organic laying hens. This product has been certified organic by the USDA. It is made with non-GMO ingredients that have been grown without the use of pesticides and fertilizers. Our layer feeds include the Oyster Strong System, which is an exclusive blend of oyster shell and key vitamins and minerals, like vitamin D and manganese, ensuring a supply of calcium will be available at night when your hens are forming eggs.