Microbial digestion: rumen versus large intestine

Microbial digestion and synthesis in the ruminant forestomach requires retention of ingesta and micro-organisms for a relatively prolonged period of time, an anaerobic environment, a suitable range of pH, and removal of inhibitory end-products. Many of the end-products provide a major source of the nutrients required by the host. The forestomach also aids in the conservation of endogenous sodium, chlorine and nitrogen. The following discussion will attempt to demonstrate analogies between the forestomach of ruminants and the large intestine of these and other mammals. Because of the background of readers, and the large amount of information available, the characteristics of the ruminant forestomach will be only briefly outlined, with reference to recent reviews. The reader is also referred to the recent review of Ulyatt et al.71 for a more detailed discussion of the structure and function of the ruminant large intestine.