A dog that is that large is going to cost a lot to feed, whether it be real or commercial food. (Check the prices on the premium foods that are prescribed for allergies next time you are at a pet superstore.) You do not need to feed your dog chicken breasts and ground beef though. Look into some alternatives discussed in this article (chicken feet, chicken necks, chicken wings, beef trachea, etc.), feed him vegetable peelings, and put together a diet that is less expensive.