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Science on the Farm for Kids
Science on the FarmScience on the Farm for Kids

Science on the Farm for Kids

Dairy cows

A cow chews her cud for 40 to 60 times, for almost one minute, before the cud is returned to the rumen.

Question: Why do cows chew their cuds?

Answer: A cow has one stomach with four distinct compartments. It’s very different from a human stomach.

Cows graze on grass and swallow it half-chewed. They then store it in the first compartment, called the rumen, where the grass or hay is softened by fluids. It’s formed into small wads or “cuds” before it’s recalled to the mouth – where the cow chews for 40 to 60 times, for almost one minute, before the cud is returned to the rumen.

The food then moves into the second compartment, or reticulum. From the reticulum the cud progresses to the omasum, where it’s pressed and broken down further.

It then moves to the fourth compartment, called the abomasum, where it’s digested. And finally the forage goes into the intestine, where the cow takes out the nutrients she needs to produce milk – and keep her healthy and contented. It takes 70 hours to turn grass into milk.

When cows chew their cud they secrete saliva. Saliva contains a natural antacid, which helps to buffer the rumen or first compartment of the stomach. Proper buffering of the rumen allows a cow to digest forages better, and to eat more feed to help her produce more milk.

If the cow eats corn, which is more-easily digested, it’s a straight shot from rumen to reticulum to omasum and finally to the abomasum. That’s not good. She needs forages of sufficient length for the production of saliva, so about 15 percent to 20 percent of her feed needs to be longer than 1.5 to 2 inches in length for optimal production of saliva. Feed that is all chopped or pulverized will not allow for sufficient cud chewing. Oh yes – there is a science to cud chewing.

Animals usually fall into “flight or fight” mode when encountering a potential enemy. Cows don’t fight; they flee. From an evolutionary standpoint cows developed four compartments, so they could graze quickly and then go hide from their enemies. Bossy could take plenty of time to digest the greens. Cows are called ruminants; they evolved to utilize forages, not grain, as their primary feed source.

Cud-chewing is a sign of a healthy and happy cow. A non-cud-chewing cow may have reduced milk-fat tests, may be lame, or have digestive upsets such as a twisted stomach or displaced abomasum. Cows spend about eight hours per day chewing their cud, which is about 30,000 chews per day.

Wisconsin is home to 1.3 million cows living on 7,000 farms. The average herd size is 183 cows; each cow produces about 7 gallons of milk. Like most Wisconsinites our cows immigrated to the United States. Holsteins came from Holland, Jerseys from the Island of Jersey in the English Channel, Ayrshire from Scotland, Brown Swiss from Switzerland and Guernsey from the Channel Islands. The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. There is another breed of Wisconsin cow we don’t hear too much about, the Milking Shorthorn. The breed was established in the 1700s in northeastern England.

Larry Scheckel is the author of “Seneca Seasons: A Farm Boy Remembers.” He grew up on a family farm in the hill country of southwestern Wisconsin, one of nine children. His teaching career stretched to more than 38 years teaching physics and aerospace science to more than 4,000 high school students at Tomah, Wisconsin. 

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