MouthA cow has no upper front teeth. Its lower incisors bite against a hard dental pad, and its tongue wraps round the grass and tears it off.
EsophagusThe tube from the mouth to the stomach. In a ruminant it works both ways: it also carries the cud back up to be chewed again.
RumenThe largest compartment, also called the paunch. It fills most of the left side and works as a fermentation vat, where microbes break down the plant fiber.
ReticulumThe small front pouch, called the honeycomb for its lining. It lies against the diaphragm, and heavy objects a cow swallows settle in it.
OmasumA round compartment packed with leaves of tissue like a book's pages. It takes up water from the feed. It is also called the manyplies.
AbomasumThe true stomach, most like that of a pig or a person. It is the only compartment lined with glands, which make acid and digestive enzymes.
Small intestineA long tube in three parts: duodenum, jejunum and ileum. Most of the nutrients are absorbed here.
CecumA large blind pouch where the small intestine meets the large. It does little in a ruminant, unlike in a horse.
Large intestineThe last part of the tract. Its main job is to take water back from what passes through. Most of it is the colon.
RectumThe end of the large intestine. What is left of the feed leaves the body from here.
How this list was compiled: Every name checked on 2026-09-30 in two sources. Mississippi State University Extension, Understanding the Ruminant Animal Digestive System: the whole tract, the four compartments and their linings, the sacs and pillars of the rumen, the reticular groove, https://extension.msstate.edu/publications/understanding-the-ruminant-animal-digestive-system. University of Minnesota Extension, The ruminant digestive system: the four compartments and their everyday names, papillae, leaves, the esophageal groove, https://extension.umn.edu/dairy-nutrition/ruminant-digestive-system. Wikipedia, Ruminant, Rumen, Reticulum, Omasum and Abomasum, https://en.wikipedia.org/wiki/Ruminant. S. Sisson, The Anatomy of the Domestic Animals (1914, public domain), the ox, for where each compartment lies, https://archive.org/details/anatomyofdomesti00siss. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work
How it works
To label the cattle digestive system, write a name on the line for each number. Ten numbers follow the tract inside a cow seen from its left side, from the mouth through the four-part stomach to the rectum.
Read the full guide
Cattle digestive system word bank
Ten names, in alphabetical order: abomasum, cecum, esophagus, large intestine, mouth, omasum, rectum, reticulum, rumen, small intestine.
The four compartments that get swapped
Number 3 sits on the very large sac. Number 4 ends on the pouch at its front, low down; 5 on the small round ball beside that; 6 on the long sac along the floor of the belly. Feed meets them in that order. At the rear, 7 ends on the low mass of coils and 9 on the coil above it; 8 is the short pouch between the two, and 10 the short tube that runs back to the tail.
When marking, oral cavity is right on line 1, gullet on line 2 and colon on line 9.
The inside of the stomach, with its sacs, pillars and linings, is drawn on the labeled cattle page.
Questions and answers
Which stomach compartment is largest in a newborn calf?
The abomasum, number 6. At birth it makes up more than half of the stomach. As the calf grows, the rumen and reticulum grow fast, and in a grown cow they are by far the largest part.
How long does a cow chew its cud each day?
About a third of the day. One extension service says cattle spend one-third of their time ruminating; another gives 35 to 40 percent of each day, with more on long hay than on grain.
Why do cows belch?
Fermentation in the rumen, number 3, makes gas, mostly carbon dioxide and methane. The gas rises to the top of the rumen, and the cow belches to let it out.
What is the reticulorumen?
The rumen and the reticulum counted as one organ, numbers 3 and 4. Only a small fold of tissue lies between them, and feed flows freely from one to the other. One extension service writes rumino-reticulum.