What to Feed Your Pet Rabbit. Just like people, bunnies enjoy a good meal. A nice mix of hay, vegetables, pellets, as well as fresh water will make your rabbit healthy and happy. Read on for more information about what to feed your pet rabbit. Fresh hay should make up the bulk of your rabbit’s diet and needs to be readily available at all times. Adult rabbits can eat timothy, grass, and oat hays, while younger rabbits should be fed alfalfa. Alfalfa should not be given to adult rabbits because of the higher protein and sugar content.