Fermentation in the Hindgut of Mammals

Abstract

Terminology in the hindgut is sometimes confusing. The term ``hindgut'' is used in the physiological sense to denote the large intestine (cecum, colon, rectum and anal canal; Lacy 1991). The cecum is a diverticulum located at the junction of the small intestine and colon. The colon varies enormously in length and complexity among mammals, mainly in relation to the natural diet of the animal. In many carnivores the colon is short, straight, and undifferentiated along its length (Hume 1982). In the human, the colon is only 1.0 to 1.5 m in length (Christensen 1989), but can be divided into ascending colon, transverse colon, descending colon, and sigmoid colon; the position or form of each section is described accurately by these terms. In more herbivorous mammals, the colon is much longer, and consequently is often arranged in a spiraling coil (Stevens and Hume 1995). The terms ``ascending,'' ``transverse,'' and ``descending'' colon are not as applicable in these animals; the terms ``proximal colon'' and ``distal colon'' are widely used instead.