Editing Cud (section)

== Rumination ==
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[[File:Water buffalo chewing cud - 01.ogv|thumbnail|A [[water buffalo]] chewing cud]]
The [[alimentary canal]] of ruminants, such as [[cattle]], [[giraffe]]s, [[goat]]s, [[Ovis|sheep]], [[alpaca]]s, and [[antelope]], are unable to produce the [[enzymes]] required to break down the [[cellulose]] and [[hemicellulose]] of plant matter.<ref>{{Cite journal |last1=Sansone |first1=Randy A. |last2=Sansone |first2=Lori A. |date=2012 |title=Rumination |journal=Innovations in Clinical Neuroscience |volume=9 |issue=2 |pages=29–34 |issn=2158-8333 |pmc=3312901 |pmid=22468242}}</ref> Accordingly, these animals rely on a [[symbiotic]] relationship with a wide range of [[microbes]], which largely reside in the [[reticulorumen]], and which are able to synthesize the requisite enzymes. The reticulorumen thus hosts a microbial fermentation which yields products (mainly [[volatile fatty acids]] and microbial protein), which the ruminant is able to digest and absorb. This allows the animals to extract nutritional value from cellulose which is usually undigested.

The process of rumination is stimulated by the presence of [[roughage]] in the upper part of the [[reticulorumen]]. The chest cavity is stretched, forming a vacuum in the gullet that sucks the semi-liquid stomach content into the [[esophagus]]. From the esophagus it is taken back to the mouth with retro [[peristalsis|peristaltic]] movements. When the stomach content, or the cud, arrives in the mouth of the ruminant, it is pushed against the palate with the tongue to remove excess liquid, the latter is swallowed and the solid material is chewed thoroughly so the cattle can extract the minerals present in the cud brought to the surface during rumination. The function of rumination is that food is physically refined to expose more surface area for bacteria working in the reticulorumen, as well as stimulation of [[saliva]] secretion to [[Buffer solution|buffer]] the rumen [[pH]].

When food has been degraded sufficiently it passes from the reticulorumen through the reticulomasal orifice to the [[omasum]] followed by the [[abomasum]] to continue the digestion process in the lower parts of the alimentary canal. No enzymes are secreted in the rumen. Enzymes and [[hydrochloric acid]] are only secreted from the [[abomasum]] (fourth stomach) onwards, and ruminants function from that point onwards much like monogastric animals, such as [[pig|pigs]] and humans.