While it's important to feed some rabbit food daily to help ensure a balanced diet, it's by no means the only thing you need to feed your rabbit. All rabbits should have constant access to quality grass hay or oat hay, as the fiber is important for their digestive system. You should also feed your rabbit a variety of fresh vegetables, particularly leafy greens — but small amounts of root vegetables are good, too. Fruit is nice as a treat but should be limited due to its high sugar content. Adult rabbits generally need no more than 1/4 to 1/2 cup of rabbit food daily per 6 pounds of weight.;