Dr. Don Llewellyn
Livestock Extension Specialist
Director, WSU Lincoln County Extension, Davenport, WA
I’m kind of in a story telling mood, so let’s take a rather lighthearted look at a myth that has been around for a long time—I’ve heard it and addressed it repeatedly in my 50+ years of working with cattle.
Myth: Cattle have four stomachs.
Here’s Scene 1 of our play: Enter our cave-dwelling ancestor (who has recently acquired fire and related technologies) and has just slayed some unsuspecting cud-chewing ungulate and is looking forward to a feast of BBQ and utilization of the byproducts of his labors (there was a good market for skins, bones, and what have you in those days). In preparation for events to come, our hero’s first step is to field dress his catch. Upon closer inspection, does he find four stomachs? No. However, there is a caveat, the stomach appears more complex than those of the wild pigs, canines, and saber-toothed cats and such that he has previously brought back to his dwelling. I will discuss the structures he sees later.
Leap forward several thousand years. I have my formal training as a ruminant nutritionist and it isn’t a very glamorous job, but it has many rewards, in the forefront are my interactions with livestock producers and scientists from a lot of disciplines. I tell my students at WSU that as a ruminant nutritionist “feces are my life”—they think that’s funny.
A good while ago in our daughter Donna’s elementary school career, she was going on a field trip to learn about farms, agriculture, and the like. In the interest of being involved in our kids’ education, we tagged along with the group and found ourselves at, if I recall correctly, a small farm. They had “stations” set up so the busloads of kids could rotate through the educational activities. When we arrived at one of the animal stations, a somewhat uninformed adult who was talking about the small ruminants in the pen stated to his pint-sized clientele that these animals had four stomachs. I don’t remember his whole narrative, but the four-stomach comment was cringeworthy enough. However, I was considerate and took into account that these folks were volunteers and doing their best to portray a positive public perception of agriculture, so I did not make a spectacle of myself or embarrass our daughter by correcting our well-meaning citizen. Important safety tip: When you give a talk you better know your topic because you never know who might be in the audience.
Now back to our play, Scene 2: Upon closer examination of the gastrointestinal tract (GIT) our pre-historic man of the hour sees several structures (I guess you could say he is the forefather of the modern-day animal physiologist). As he peruses the GIT, you can follow along with the following diagram of the flow of digesta and the function of the parts of the rumen:
The four chambers of the ruminant stomach
Reticulum—feed and saliva travel down the esophagus and enter this pouch-like structure that is situated low and near the front of the rumen. On the inside, the reticulum has the appearance of a honeycomb. Dense feed enters this compartment. It is also the site where ingested objects like wire and nails can perforate the wall of the reticulum resulting in “hardware disease” which ultimately can lead to infection and death. A fold of tissue divides the reticulum from the rumen, but they aren’t separate per se.
Rumen—is the large storage compartment for ingested feed and the major site of microbial digestive activity. Fermentation of feed takes place here with the production of volatile fatty acids (VFA) and other digestive products. Microbe-produced enzymes allow for digestion of cellulose from fibrous feeds. The wall of the rumen makes it possible for absorption of digestive products such as VFAs. It is also the site of rumen degradation of protein and the resulting production of microbial protein.
Omasum—sometimes called the “butchers bible” because the folds of inner tissue resemble the pages of a book. Water and other products are absorbed here with little microbial activity. It also acts as a pump to move material on to the abomasum.
Abomasum—the compartment that is most like the monogastric stomach found in humans, pigs, dogs, etc. The tissue is very glandular for production of hydrochloric acid and digestive enzymes that help digest feeds. From here it’s on to the small intestine for further digestion and absorption.
The four chambers of the ruminant stomach are what allow cattle to utilize highly fibrous feeds and turn them into useful products and in the big picture to make good use of lands unsuitable for cultivation. Four chambers working together to provide nutrition to the cow and making high-quality food. Our pre-historic friend figured that out long ago—at least the part about making good stuff to eat. As a ruminant nutritionist, I’m continually amazed at the ruminants’ capabilities and their ability to produce high-quality protein products to feed a growing human population.
Well, there you have it, the myth is busted! For now, I think it’s time for that BBQ. I hope you have enjoyed my stories, my musings, and as they used to say in the early years of TV, ‘I hope you have enjoyed them as much as I have bringing them to you’. I will be back next time for a more serious approach to the myth of the month. Until then, so long, give us a call or e-mail if we can help with your cattle and operations. That’s what WSU Lincoln County Extension is here for! Don Llewellyn, 509-725-4171, firstname.lastname@example.org