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The rabbit's digestive system is monogastric (one stomached), and falls int the classification of 'hindgut fermenter'. This means that they obtain more nutrition from their food via microbial digestion in the cecum, part of the lower intestine, and then re-ingest the resulting cecotropes.

Cecotropes are mucous-coated soft feces which are high in volatile fatty acids and various vitamins. The microbes produce these nutrients in the cecum and the rabbit consumes them directly from the anus. These grape-like bundles of 'night feces' are rarely found under the cages.

Normal fecal pellets, which are found under the cage routinely, contain very high levels of coarse fiber, upon which the rabbit gut relies for normal function. This is why the crude fiber level of your feed is so important, especially when feeding pellets. When feeding a non-pelleted diet, hay is used to fulfill this requirement.

Water is also a nutrient that is absolutely vital to proper digestion in the rabbit. Water keeps the gut contents fluid and moving along; since the gut sequentially squeezes the contents to mix, move, and digest the ingesta, it's very important that the material is soft and wet. In combination with the crude fiber, which 'scratches' the gut lining to stimulate further movement, these two factors can be called the most important of them all in regard to rabbit digestion.

The third important factor in actual digestion is the microbial flora found in the cecum. What the rabbit is fed can affect what types of bacteria are dominant, as can many antibiotics. This is why the domestic rabbit should never be given any penicillin-based antibiotic orally, and why sudden diet changes are generally a bad idea.

Foods high in starch, like corn, have a greater potential to upset the gut flora to favor bacteria which produce toxins which can be deadly. This problem is called enterotoxemia.

When the rabbit eats, the lips and tongue work together to get food into the mouth, where the sharp incisors chop it into manageable lengths and the molars grind and cut it into swallow-able sizes. Saliva starts the digestive process by breaking down simple sugars and lubricating the ingesta.

Once swallowed, the stomach mixes and kneads the food into something called 'chyme'. Gastric acid begins breaking down various parts of the material so that the small intestine, aided by the pancreas, can absorb the basic amino acids, fats, vitamins and other nutrients. The pancreas in the rabbit secretes enzymes which break these nutrients down into sizes and types which can easily pass the intestinal wall into the bloodstream. This is where most of the actual nutrient absorption occurs.

After this process, the ingesta passes into the cecum, where the larger fiber particles are separated from the finer material, which stays in the cecum for the bacterial flora to process. The coarser fiber is formed into the familiar 'bunny berries' by the large intestine, where water is removed and reabsorbed, then excreted.

The cecal content is fermented and formed into the cecotropes, which are excreted in bunches separately from the normal hard feces.

Rabbits digest fibrous materials and plant proteins more efficiently than any other monogastric species.

'Woolblock' is most often due not only to hair, but to dehydration of the stomach and gut contents.

Mucoid enteropathy is sometimes said to be due to cecal impaction, which is aggravated by dehydration.

Rabbits can be raised and kept on good quality pellets and hay alone, or a combination diet, as long as it is complete and reasonably balanced.

copyright 2007 by Pamela Alley
used by permission

Pamela Alley is the director of the Rabbit Industry Council