Author: Kerrin Grant, M.S.; Rehabilitation Supervisor/Nutritionist, The Wildlife Center Espanola, New Mexico Herbivore nutrition separates animals into two main categories, depending on where food particles are broken down and fermented prior to absorption. The categories are foregut and hindgut fermenters, with the hindgut group being broken down into colonic and cecal fermenters. The second group of herbivore digestion is the hindgut fermenter. This adaptation is found in monogastric herbivores or herbivores with a one-chambered stomach. This adaptation is further categorized into two groups: colonic fermentation, which is typical of larger species such as horses and rhinos, and cecal fermenters, such as rabbits and rodents. Colonic fermenters typically have a proportionally longer large intestine than small intestine. For instance, the large intestine comprises 62% of a horse’s digestive tract, whereas cecal fermenters have a considerably enlarged cecum compared to the rest of the digestive tract. In cecal fermenters most digestion of plant matter occurs after it leaves the stomach and enters the cecum. Food particles move through the stomach, down the long small intestine and enter the proximal colon. From here, digestible matter enters the cecum and indigestible matter passes down to the distal colon and is excreted. Food matter that enters the enlarged cecum then forms into cecotrophs that are re-consumed by the animal so they can absorb important nutrients, like the B vitamins. This action of re-ingesting cecotrophs is the monogastric herbivore’s version of a cow chewing its cud, but their food is re-ingested after it has left the stomach instead of beforehand. Cecotrophs are swallowed whole and digestive enzymes are released that allow for absorption. Additionally, microbes that were breaking down food particles in the cecum now provide important amino acids and B vitamins for the animal to absorb. Chinchillas have a seasonally varied diet, but fiber comprises approximately 66% of the diet annually, most of which is highly lignified (bark, wood stems, shrubs, and bromeliads), whereas seeds form very little of the natural diet. The highly lignified diet suggests chinchillas have adaptations to absorb proteins from other means than directly from the diet. So how does all this affect the diet of exotic pets? Since many of the small mammals in the exotic pet trade are herbivores, and cecal fermenters, it is important to remember how these species have evolved to digest food and absorb nutrients. Many species require a diet high in fiber to maintain a healthy cecum. Diets high in starches and refined sugars (as is commonly given as treats) may be fine in limited supply. When starches, are given on a regular basis or in large quantities this may lead to a disruption of cecal pH, loss of microbes for digestion, and diarrhea. Fiber is an important dietary component for most, if not all, cecal-fermenting pets. Gastric disease commonly results from a lack of adequate fiber in the diet. Additionally, lagomorphs and some rodents have evolved to consume diets that are either low in protein, or contain secondary plant compounds that interfere with protein absorption; therefore, providing excess levels of protein in a captive diet can be problematic. Feeding clover (high in protein) is associated with bloat in chinchillas. Some types of respiratory disease have been attributed to increased ammonia from excess dietary protein in rabbits (Jenkins, 1997).
Posted on: Fri, 26 Sep 2014 23:06:56 +0000
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