Purina Organic Layer Crumbles are made with the Oyster Strong System to provide a balanced and complete diet with 16% protein for feeding organic laying hens. The Oyster Strong System, is an exclusive blend of oyster shell and key vitamins and minerals, like vitamin D and manganese, which ensures the optimal supply of calcium will be available at night when your hens are forming eggs. | Purina Organic Layer Crumble Poultry Feed | Size 35 lbs