With his age and Size 2 cups a day is plenty. I feed my 73lb Bully 1 cup twice a day. If you think you're not feeding him enough you can add some snacks, apple slices, Blue berries, baby carrots. If you are concerned about protein you can always add a little boiled chicken, beef, fish, or venison. Just dont add alot. You may think its not enough but Bullies will eat until die....its just the breed.