One of essential organ meats. Liver has a vast range of important nutrition it has the most concentrated source of vitamin A as well as vitamins D, E, and K in substantial quantities. Liver is an excellent source of the minerals zinc, manganese, selenium and iron. It also contains all the B vitamins and is a good source of vitamin C. Liver provides a source of good quality protein and the essential fatty acids, both the omega-3 and omega-6 type. It is a fantastic food for your dogs and cats but should not make up more than 5% of the meal.