Many healthy rabbits will turn up their noses at hay because they are offered excessive amounts of pelleted food. This is because most rabbits prefer pellets to hay. Rabbit pellets are predominantly made of carbohydrates, and like most people, rabbits love their carbs and will choose them over fiber (hay). The general rule for healthy adult bunnies is no more than one-quarter cup of timothy hay-based pellets per 5 pounds of body weight each day. Growing and lactating (nursing) rabbits sometimes need more pellets in order to consume adequate calories (ask your veterinarian for feeding advice if you own a rabbit in one of these life stages), but for most bunnies, this is enough.
Adult rabbits can get all the nutrients they need from good quality hay and don’t actually need pellets. Hay should be the main food item a rabbit eats, and you cannot overfeed him. Timothy is usually the hay of choice, but orchard grass, oat hay and meadow grass hay are also suitable for healthy adult bunnies. Most owners purchase bags of loose hay at pet stores, although hay cubes are another acceptable, though less common, option. Both forms of fiber are fine as long as the hay is relatively fresh and hasn’t been sitting on the shelf for months (check the label). Certainly, if a rabbit that normally eats hay abruptly stops doing so, he should be examined by a rabbit-savvy veterinarian as soon as possible to ensure nothing is wrong, such as a dental problem or gastrointestinal upset. Rabbits are prone to both conditions.
While your rabbit should primarily consume hay, pellets contain carbohydrates and can be helpful in aiding thin rabbits to maintain or gain weight. Pellets are fine to feed in limited quantities, but should not be fed to the degree that they discourage your rabbit from eating his hay.