Eww! Cow's digestion not for the queasy
Elise Diaz's fifth-grade students at O'Plaine School in Gurnee asked: "Why do cows have four stomachs?"
If you get a little queasy at the thought of throw-up, you may need some fresh air before you read about cows and their stomachs.
It seems like most dogs and cats regurgitate after eating grass. Cows and other ruminants do that too - but then they reswallow the regurgitated food. It's the way their digestive systems work - and a way they can eat foods other animals can't.
Ruminants are mammals with four stomach chambers, the first one being the rumen.
"The rumen holds about 50 gallons of partially digested food," said Cliff Shipley, DVM, DACT, at the University of Illinois College of Veterinary Medicine in Urbana. Shipley oversees the care of large animal patients and farm animals owned by the university.
"Cows have four digestive compartments in their stomach before it connects to the small intestine," Shipley said. "The compartments allow the use of forages, like grass. The compartments contain protozoa and bacteria and other organisms that can digest cellulose."
Cows, water buffalo, deer, camels, goats, sheep, horses, reindeer and other ruminants eat hay, grass and stalks. They swallow the plant matter; it travels down the esophagus and into the first stomach chamber. The rumen can't fully digest the plant material, so it shoots a wad of hay and grass back up to the cow's mouth in the form of cud.
Lots and lots of chews later, the cud can be more easily swallowed and passed from the rumen to the reticulum. Then it is sent to the omasum and finally the abomasum. The remaining nutrients are moved into the small intestine.
Filling up a 1,000-pound animal means it has to chew about 40 pounds of forage each day. Compare that to an average 150-pound person who consumes only 3 pounds of food in a day.
Learn more about cows and other animals at the University of Illinois College of Veterinary Medicine free open house on Sunday, April 11, 10 a.m. to 4 p.m. Animal lovers of all ages and students interested in veterinary careers are invited to milk cows, "examine" dummy animal patients, hold reptiles and use microscopes to view samples.
For more information, check out the U of I College of Veterinary Medicine Web site at vetmed.illinois.edu/openhouse.
<p class="factboxheadblack">Check these out</p>
<p class="News">The Grayslake Area Public Library District suggests these titles on ruminants:</p>
<p class="News">• "Farm Animals," by Melvin and Gilda Berger</p>
<p class="News">•"Fun Facts About Farm Animals," by Carol Benanti</p>
<p class="News">• "Giraffes: Long Necked Ruminants," by Andreu Llamas</p>
<p class="News">• "On The Land," by the Diagram Group</p>
<p class="News">• "Some Porcupines Wrestle: And Other Freaky Facts about Animal Antics and Families," by Barbara Seuling</p>