Photo by Sue Weaver
Jacy isn’t laughing—she’s chewing cud!
Last week, a lady brought her children to our farm to meet us. The little boy looked at me and said, “What’s he chewing?”
“His cud,” his mama told him. “He chews up his food and swallows it, then horks it up again and chews it some more. And you know what? He has four stomachs!”
Uzzi and I looked at each other. That’s not quite true. We don’t have four stomachs; we have one stomach with four chambers. Here’s how it works:
True ruminants—like us goats, sheep, cows, deer, elk, antelope, bison, water buffalo and yaks—have a rumen, a reticulum, an omasum and an abomasum. Combined, they make up our stomach.
The first and largest of the chambers is our rumen. It’s located on our left sides, where it acts as a fermentation vat. A rumen contains billions of bacteria, protozoa, fungi, molds, yeasts and other wee beasties that feed on carbohydrates in the stuff we eat. They convert carbohydrates into volatile fatty acids. Volatile fatty acids represent our primary source of energy.
As feed mixed with saliva enters our rumen, it separates into layers of solid and liquid material. Later, when we’re resting, we burp up some gas (that’s why you think our breath smells bad) and a bolus of food (our cud) and re-chew it more slowly. Then we swallow it again. Yum!
Chewed-up feed flows back and forth between the rumen and the next chamber, the reticulum, by way of an overflow flap. Particles remain in this area for 20 to 48 hours because fiber fermentation is a slow process. Eventually they pass from the reticulum through a short tunnel into our omasum.
The omasum is divided by long folds of tissue like pages in a book. It’s also lined with little finger-like things called papillae to increase its working surface. The omasum decreases the size of feed particles, removes excess fluid from digestive slurry, and absorbs volatile fatty acids that weren’t absorbed in our rumen.
The fourth chamber, our abomasum, is considered our “true stomach” because it’s the most like a human’s stomach. The walls of the abomasum secrete digestive enzymes and hydrochloric acid. Protein is partially broken down in the abomasum before material enters the small intestine.
Because our stomachs are so different from yours, there are tricks to feeding us ruminants. You know all those bacteria and other wee beasties in our rumens? Because they provide our energy needs, if all of them die, we die, too. And they’re sensitive because they get used to one type of diet at a time. So if you switch, say, from a high-hay and low-grain diet to one containing lots of grain, our rumen beasties die off. Then we’re in big trouble! So make changes in our feed very gradually to give our rumen beasties time to adjust.