The best thing for a rabbit to chew on is hay. Contrary to what the people at the pet store sell you or you read in different places....chew toys, blocks of wood, etc. are not beneficial (except to the people that sell them). Hay is the primary way to keep the teeth down (incisors, pre-molars and molars)and what they should be chewing on. It's not how hard something is...it's how chewy it is. The teeth wear by tooth to tooth contact. Wood is far too soft to have any effect whatsoever on the teeth. If you notice your rabbit eat, they chew from side to side...not up and down. They use their 6 incisors (4 upper and 2 lower) to pull hay in or tear greens. The pre-molars and molars are used to fold the hay into something that looks like an accordian. The side to side chewing motion is due to the curvature of the pre-molars and molars. It is advisable to offer a buffet of different hays since each type of hay has a different texture and requires a different chewing mechanism. A rabbit that eats lots of hay will not be obese and will have a very healthy GI. While we do offer toys....hay is our primary chewing component.
Randy