Dogs are carnivorous animals. That makes their major diet meat-based. You must feed your Blue German Shepherd high-quality dog food that has all the nutrients your dog needs. Table scrap can cause them digestive upset. Give them little food at a time so that they can digest without any issue. Small pieces of biscuits or a dog's Kimble might be a good option while training your dog. If you are feeding your high-quality dog food, mineral supplements are not necessary. However, adding some yogurt and cooked vegetables can be beneficial.