Getting back to Rabbits, see www.rabbit.org and go to the link for nutrition.

Alfalfa-based pellets are not good for adults, especially as the rabbit gets older. Alfalfa pellets are high in calcium, which for babies is good (for their bones), but as an adult they not longer need that calcium for bone growth. The excess calcium sits in their bladder, forms into crystals and eventually becomes bladder stones. The tell-tale sign for excess calcium is called sludge, a whitish deposit in the bunny's urine.....that is a danger sign that you need to stop ALL alfalfa based products immediately.

There are timmothy hay based pellets, as Zippy indicated, made by the Oxbow company. Rabbit specialist vets usually sell them as well as oxbow online. americanpetdinner.org (or maybe .com)
also sells timmy-based pellets.

I urge people who say they've always feed their rabbits pellets and have never had a problem....I'd like to know how old did your bunny get to be before it died and do you know what it died of?
I'm not being a smart alec.... I'm sure that some bunnies can live on nothing but pellets but as my vet says, do wild bunnies eat pellets? Of course the answer is no. It is not a natural food. Bunnies need unlimited amounts of timmy hay and greens to keep their gut moving. If the gut gets heavy with pellets, or the bladder heavy with calcium crystals you could, not would but could, lose your bunny. A bunny's gut has to move 24 hrs a day and if it stops they die within hours, so please don't take the chance.