Editing User:Raven/ignore me (section)

=== Digestive system ===

{{Further|Digestive system of ruminants}}
[[File:Kibegwa 2023 rumen microbiome.png|thumb|Bacteria dominate the rumen microbiome; composition can change substantially with diet.<ref name="Kibegwa2023"/>]]

Cattle are [[ruminant]]s, meaning their [[Gastrointestinal tract|digestive system]] is highly specialized for processing plant material such as [[grass]] rich in [[cellulose]], a tough carbohydrate polymer which many animals cannot digest. They do this in symbiosis with micro-organisms – [[bacteria]], [[Fungus|fungi]], and [[protozoa]] – that possess [[cellulase]]s, [[enzyme]]s that split cellulose into its constituent [[sugar]]s. Among the many bacteria that contribute are ''[[Fibrobacter succinogenes]]'', ''[[Ruminococcus|Ruminococcus flavefaciens]]'', and ''Ruminococcus albus''. Cellulolytic fungi include several species of ''[[Neocallimastix]]'', while the protozoa include the [[ciliate]]s ''Eudiplodinium maggie'' and ''Ostracodinium album''.<ref name="Hua Hendriks Xiong Pellikaan 2022">{{cite journal |last1=Hua |first1=Dengke |last2=Hendriks |first2=Wouter H. |last3=Xiong |first3=Benhai |last4=Pellikaan |first4=Wilbert F. |title=Starch and Cellulose Degradation in the Rumen and Applications of Metagenomics on Ruminal Microorganisms |journal=[[Animals (journal)|Animals]] |volume=12 |issue=21 |date=3 November 2022 |pmid=36359144 |pmc=9653558 |doi=10.3390/ani12213020 |doi-access=free |page=3020}}</ref> If the animal's feed changes over time, the composition of this [[microbiome]] changes in response.<ref name="Kibegwa2023"/>

Cattle have one large [[stomach]] with four compartments; the [[rumen]], [[Reticulum (anatomy)|reticulum]], [[omasum]], and [[abomasum]]. The rumen is the largest compartment and it harbours the most important parts of the microbiome.<ref name="Kibegwa2023">{{cite journal |last1=Kibegwa |first1=Felix M. |last2=Bett |first2=Rawlynce C. |last3=Gachuiri |first3=Charles K. |last4=Machuka |first4=Eunice |last5=Stomeo |first5=Francesca |last6=Mujibi |first6=Fidalis D. |date=13 January 2023 |title=Diversity and functional analysis of rumen and fecal microbial communities associated with dietary changes in crossbreed dairy cattle |journal=[[PLOS One|PLOS ONE]] |volume=18 |issue=1 |pages=e0274371 |doi=10.1371/journal.pone.0274371 |doi-access=free |pmid=36638091 |bibcode=2023PLoSO..1874371K |pmc=9838872}}</ref> The reticulum, the smallest compartment, is known as the "honeycomb". The omasum's main function is to absorb water and nutrients from the digestible feed. The abomasum has a similar function to the human stomach.<ref name="Orr 2023">{{cite web |last1=Orr |first1=Adam I. |title=How Cows Eat Grass: Exploring Cow Digestion |url=https://www.fda.gov/animal-veterinary/animal-health-literacy/how-cows-eat-grass |publisher=[[Food and Drug Administration]] |access-date=13 February 2024 |date=28 June 2023}}{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}}</ref>

Cattle [[regurgitation (digestion)|regurgitate]] and re-chew their food in the process of chewing the [[cud]], like most ruminants. While feeding, cows swallow their food without chewing; it goes into the rumen for storage. Later, the food is regurgitated to the mouth, a mouthful at a time, where the cud is chewed by the molars, grinding down the coarse vegetation to small particles. The cud is then swallowed again and further digested by the micro-organisms in the cow's stomach.<ref name="Orr 2023"/>