Why is cellulose difficult for rabbits to digest?

Cellulose is difficult for rabbits to digest because it is a complex carbohydrate that forms the structural component of plant cell walls, and the digestive enzymes of higher animals are generally unable to break it down.12

To overcome this, rabbits utilize a specialized digestive strategy known as hindgut fermentation. After plant material passes through the small intestine, it enters the cecum—a large, secondary chamber containing symbiotic bacteria. These microorganisms ferment the cellulose, converting it into absorbable nutrients.12

Because this process occurs after the primary site of nutrient absorption, rabbits practice coprophagy, the act of consuming their own soft, nutrient-rich feces. By redigesting this material, they ensure that the nutrients released by the bacteria are successfully absorbed, allowing them to derive maximum nutrition from their high-fiber diet.13