Gastrointestinal tracts of herbivores, particularly the ruminant: Anatomy, physiology and microbial digestion of plants

Abstract

The ability of herbivores to utilize forages and plants as their sole energy source is dependent on microorganisms living at various sites within their gastrointestinal tract. Essentially two types of herbivores have evolved, those with a post-gastric (hindgut) fermentation and those with a pre-gastric (foregut) fermentation. Bacteria are present in the gastrointestinal tract of all herbivores, and many are also inhabited by ciliate protozoa and fungi. Ruminants, probably the most abundant of the herbivores, are foregut fermentors with a four-chambered stomach (rumen, reticulum, omasum and abomasum). Only the last chamber, the abomasum, is acidic. The environment within the rumen is anaerobic, 39C, with a pH between 6.0 and 7.0. © GSP, India.