11 Year - Digestion

Crawford County 4-H Dairy Skills
11 year old
How a Cow Digests the Feed She Eats
The dairy cow has a unique digestive system. She is a ruminant animal, which means she has a
four-chambered stomach. This compared to animals with a simple single chambered stomach,
gives her the unique ability to digest fiber and make protein from simple nitrogen compounds.
Digestion in ruminants takes place by a process called fermentation which utilizes microbes
found in the stomachs to convert feed into compounds readily digested and easily converted
into milk and meat. This makes the cow’s justification for existence compelling because of her
capacity to produce high quality food from feeds that man cannot normally utilize.
The digestive system starts with the mouth. A cow does not bite her feed, instead she uses her
tongue to sweep feed into her mouth. From the mouth, feed passes through a tube called the
esophagus into the first and largest stomach called the rumen. The rumen is very muscular and
acts as a mixing vat and fermentation tank. Feed particles that are small in size sink to the
bottom of the rumen and pass into the next stomach called the reticulum. Those that are large
are regurgitated back into the mouth where they are chewed into finer pieces and mixed with
saliva. This process is called “cud-chewing”. Through chewing and mixing, all feed eventually
passes into the reticulum. From the reticulum, this now slurry of ground feed and microbes
passes into the omasum, where water absorption takes place. From there the slurry passes
into the abomasum. The abomasum is the equivalent of the true stomach. It is there where
strong acids are produced and mixed with slurry. Digestion is completed in the intestine where
enzymes are produced and absorption takes place. A common digestive disease of cows is the
displaced abomasum or twisted stomach. This condition occurs under certain circumstances
when gas is trapped in the abomasum causing it to “float” out of place. Most displaced
abomasums are repairable with surgery.
1. Name the 4 chambers of the cow’s stomach:
a. _________________________________________________
b. _________________________________________________
c. _________________________________________________
d. _________________________________________________
2. What is the process called when a cow regurgitates feed back into her mouth so it can
be mixed with saliva and be ground into finer particles? _________________________
3. The fermentation process utilizes ____________________________ to digest fiber and
make protein in the ruminant stomach.