Yes, rabbits can eat oats. Oats should compose a small amount of the diet. The main part of a rabbit's diet should be timothy hay--this should be available at all times. A pelleted rabbit diet should be supplemented. Treats and vegetables should be fed in small amounts comprising no more than 10% of the diet.
Rabbits also like the bark off apple branches which are high in vitamins for them. Most pellets have a high concentration of alfalfa which is too high in calcium. Watch their urine cloudy white build up in it wil be a sure sign of calcium overload. Stay away from iceberg lettuce and potatoes. Leaf lettuce, parsely, cilantro, cucumber peels, carrots, pear peels, berries, bananas, lettuce and, etc are what we suppliment with the Timothy hay. If you have a Fleet Farm or other farming store near you, they tend to have the best price on hay. The book Living with the Urban Rabbit has a very comprehensive list of food does and don't also check out some of the rabbit breeders sites for help.
