Pet Care Tips provides the following about feeding healthy snacks for your pet rabbit:
"As a responsible and caring rabbit owner you no doubt know that the bulk of your rabbit's diet should be fresh grass hay, such as timothy, meadow, prairie, brome or oat hay.
Alfalfa hay is too high in calories, protein and calcium to be healthy as a major food source for adult rabbits, but you can give your adult rabbits small amounts of alfalfa hay
occasionally as a treat. Young rabbits do need some alfalfa hay as a regular part of their diets because they need more calories and protein since they are growing and are probably
also more active than their parents.
Rabbit pellets such as are sold at feed and pet stores are not suitable as the bulk of your rabbit's diet, but you should offer a handful or so of pellets every day.
Leafy greens are great for your rabbits, and you should offer them several types of leafy greens every day. Be sure to introduce new vegetables slowly and one at a time so that
you can watch for any bad reactions such as soft stools."