Final answer:
The part of the rabbit's digestive system where bacterial fermentation occurs is the large cecum, which plays a vital role in their ability to digest and recycle nutrients.
Step-by-step explanation:
Fiber is important in a rabbit's diet, and the part of the digestive system where bacterial fermentation occurs is the large cecum. Rabbits have a unique digestive system in which they digest their food twice, utilizing their enlarged cecum for this process. The cecum is responsible for the fermentation of plant material that cannot be completely broken down by enzymes in the small intestine. This fermentation by bacteria within the cecum leads to the production of vital nutrients, like vitamins, which the rabbit then recycles by eating the cecotrophy's - a special kind of feces - to reabsorb these nutrients in the small intestine.