How Do They Eat That?

The other day I was asked about cattle having 4 stomachs and how their digestive system works. This is a subject we cover a lot in many of my classes but just to be sure I pulled out one of my favourite text books (yes I’m a big enough nerd to have a favourite textbook) and double checked my information. Here is what I have learned:   A cow does not have 4 stomachs like ours; but one big stomach with 4 digestive compartments.

inside of rumen

After food is swallowed it first enters the rumen. The rumen is the largest compartment and is full of bacteria that allow cattle to be able to digest fibrous material such as grass and hay. The food that enters the rumen is not fully chewed; it is softened into round balls of ‘cud’ that is later regurgitated for the cow to chew later when she is resting. A cow does this so as to give the food as much surface area as possible for the digestive process to work on it.

inside of reticulum

Next comes the reticulum,  also known as the ‘hardware stomach’ because it has a honeycomb structure that is designed to catch any foreign objects that the cow may have eaten (for example wire, nails etc) and keep them from going through, and causing damage to, the digestive system. This is also the first step where bacteria is able to start to break down the fibrous components of a cows diet.

inside of  omasum

After that comes the omasum, this one looks just like piles of fabric folded over on itself. The job of the omasum is to take out nutrient and water from the food.

At the very end is the abomasums. This is the compartment that is most like our stomach. It is full of acid and secrets enzymes that allow the cow to properly digest her food.

So there you have it, all four digestive compartments of a cow stomach. I find this system very fascinating because it allows cattle (and other ruminants) to digest material that we as humans can not!



pictures from: http://courses.washington.edu
text book: A Veterinary Book for Dairy Farmers by RW Blowey

from: http://www.omafra.gov.on.ca/english/livestock/beef/facts/91-066f2.gif