Rabbit Fact Sheet - Effect of Diet
The Effects of Diet on Rabbit Gastrointestinal Health
SUMMARY: Rabbits are uniquely adapted to digesting succulent vegetative matter and excluding indigestible fractions. Diet of pet or companion rabbits can be greatly influenced by the type of food provided. Too little fiber or too much starch can slow transit and lead to digestive disturbances. Excess protein and fat should be avoided, and modest supplementation with minerals and vitamins is recommended. Feeding a balanced commercially prepared diet like Genesis Extruded Rabbit Food in addition to clean grass or legume hays is recommended.
INTRODUCTION: The digestive system of the rabbit is well adapted to exploiting the feed stocks available in their wild habitat. However, displacing the pet into our homes as companions transfers the obligation of balancing the rabbit’s diet and nutrition onto the pet owner. In many circumstances the simple stomached digestion of the rabbit is similar to that of humans, dogs and even horses. However, they do have some unique idiosyncrasies which must be considered. If these are overlooked it can lead to harmful nutritional imbalances, sickness and even death. Some of the nutritional similarities and unique requirements will be described to enhance diet selection for the domestic companion rabbit with an emphasis on prevention of digestive disorders, general health, and longevity.
OPTIMAL DIETARY COMPOSITION: Often the most overlooked nutrient is water. While the wild rabbit may in fact be able to acquire all of the water necessary for its survival from selection of succulent plant material and dew, the captive rabbit is not so fortunate. For that reason it is very important to assure that fresh water is available at all times. Water bottles are often recommended as they are less likely to be contaminated or spilled.
Carbohydrate balance is critical to proper feeding of the rabbit. Simply stated fiber should be no less than 13 to 16% (crude fiber) and soluble sugars and starch (NFE) should be no more than 16% of the diet (LeBas, 2004). While fiber is not considered to be an “essential” nutrient per se it is certainly critical to the rabbit for proper gut motility and ingesta transit (Belenguer et al., 2002; Garcia et al., 1993). Low fiber intake has been reported to decrease cecal VFA and elevate cecal pH and NH3 levels (Gidenne et al., 2004). Fiber particle size is also important with the ideal exceeding 2mm. Small particle size fiber (1 mm or less) can negatively increase GI retention time and cecal weight (Gidenne, 1992). Further, inadequate fiber can slow gut motility, lead to impaction, exaggerate problems with tricobezoars (hairballs), increase morbidity and even decrease survivability. On the other side of the carbohydrate fulcrum, starch and soluble sugars coming from ingredients like grain are typically low in rabbit diets. At low levels the starch from the diet is almost completely digested and absorbed in the small intestine. Cooking dietary starch in pro- cesses like extrusion can substantially improve small intestinal digestion (Otutumi et al., 2005). However, feeding high levels of unprocessed grains can lead to undigested starch spilling over into the cecum and may lead to digestive disorders. For example, high cecal starch concentrations can lead to an overgrowth of Clostridium spiriformes and production of enterotoxic iota toxin (Peeters et a., 1993).
For pet or house rabbit dietary protein (adult maintenance) should be in the range of 12 to 16% (Lowe 2003; LeBas 2004). The ingestion of cecotropes has been estimated to provide around 18% of the rabbit’s daily protein requirement (Fraga, 2003). If the dietary protein exceeds 20%, digestive disturbances, soft feces, diarrhea, and (or) scours may be observed. Consumption of fat by rabbits is generally in the form of plant structural or membrane lipids (Xiccato, 2003). Dietary fat composition should be in the 2 to 5% range with no more than 5% as added fat and these should be from vegetable sources.
Minerals and vitamins are also of great importance in rabbit diets; however, for the most part their needs don’t differ too substantially from that of other simple-stomached species. It should be noted though that the rabbit cannot regulate its calcium absorption. This is not a problem except in the case of high calcium containing forages. This lack of control over calcium absorption is often why grass hay rather than alfalfa (Lucerne) is recommended. Imbalances in calcium and phosphorous nutrition (too much P per unit Ca) can lead to dental problems and urinary tract obstructions (urolithiasis). Theoretically supplemental vitamins should not be necessary due to their concentration in cecotropes. However, vitamins are often provided in the diet to offset their potential loss during ingredient harvest, storage and processing. Further, B-vitamin supplementation can support rabbit nutritional needs in the event that normal cecal fermentation or cecotrope ingestion is disrupted.
LITERATURE CITED:
• Belenguer, A., J. Balcells, M. Fondevila, and C. Torre. 2002. Caecotrophes intake in growing rabbits estimated either form urinary excretion of purine derivatives or from direct measurement using animals provided with a neck collar: effect of type and level of dietary carbohydrate. Anim Sci 74:135-144.
• Fraga, M.J. 2003. Protein Digestion. In The Nutrition of the Rabbit. Edd C. de Blas and J. Wiseman. CABI Publishing, Oxon, UK pp 39-54. • Garcia, G., J.F. Galvez, and J.D. de Blas. 1993. Effect of substitution of sugarbeet pulp for barley in diets for finishing rabbits on growth perfor-
mance and on energy and nitrogen efficiency. J. Anim. Sci. 71:1823-1830.
• Gidenne, T. 1992. Effect of fibre level, particle size and adaptation period on digestibility and rate of passage as measured at the ileum and in the faeces in the adult rabbit. Br. J. Nutr 67:133-146.
• Gidenne, T., N. Jehl, A. Lapanouse, and M. Segura. 2004. Inter-relationship of microbial activity, digestion and gut health in the rabbit: effect of substituting fibre by starch in diets having a high proportion of rapidly fermentable polysaccharides. Br. J. Nutr. 92:95-104.
• LeBas, F. 2004. Reflections on rabbit nutrition with a special emphasis on feed ingredients utilization. Proceedings of the 8th World Rabbit Congress, Ciudad de Puebla, Mexico. pp 686-736.
• Lowe, J.A. 2003. Pet Rabbit Feeding and Nutirion. In The Nutrition of the Rabbit. Edd C. de Blas and J. Wiseman. CABI Publishing, Oxon, UK pp 309-332.
• Otutumi, L.K., A.C. Furlan, and C. Scapinello. 2005. Digestibility and intestinal enzymatic activity of growing rabbits fed different sources of starch processed or not by extrusion . R. Bras. Zootec. 34:557-567.
• Peeters, J.E., R. Orsenigo, L. Maertens, D. Gallazzi, and M. Colin. 1993. Influence of two iso-energetic diets (starch vs. oil) on experimental colibacillosis (EPEC) and iota-enterotoxaemia in early weaned rabbits. World Rabbit Science 1:53-66.
• Xiccatto, G. 2003. Fat Digestion. In The Nutrition of the Rabbit. Edd C. de Blas and J. Wiseman. CABI Publishing, Oxon, UK pp 55-68.
