Most brands provide multiple options for different stages of a rabbits life. So check the labeling. Most brands recommend .5 ounces per pound of rabbit per day(about 2/3 of a cup for 9 pounds). Non breeding senior rabbits can eat a 12-13% protein pellet. Young Rabbits and Breeding rabbits need a 16-18% protein pellet. So you’ll need to always read your feed labeling because not all pellets are created equal. Check the protein(16%) and fiber levels(20%) on the labeling. A good pellet is a balanced diet. In addition to pellets you can provide hay daily which is additional fiber and supplemental fats and minerals. A rabbit will benefit from a high fiber diet. Eating hay regularly will help their stomach bacteria stay healthy. Small amounts of fruits & vegetables are also acceptable for rabbits older than 12 weeks. No more than a 1/4 cup at a time.