Lesson Of The Week: Chewing The Cud

Cows are interesting. They eat grass and hay, but they grow huge. Have any of you ever seen a skinny cow? There is a perception about vegetarians being skinny, but I guess they blow that theory out of the water.

Hay is very difficult to digest, so a cow's digestive system is pretty tough! Cows belong to the ruminant class of animals, which have four stomachs and chew their cud. The average cow chews 40,000 to 60,000 times a day because of the amount of food it eats and chewing its cud.

After grinding its initial food, the cow swallows the food into its first stomach, the rumen. The rumen is the largest compartment and has billions of microorganisms inside. These organisms help the cow by digesting the plant fiber and producing fatty acids for the cow. This symbiotic relationship helps cows digest a variety of materials that are hard to digest for other animal classes. Any food that is too heavy or hard to be digested is stored in the reticulum, the second stomach compartment.

Once this is done, the cow regurgitates the unprocessed food to allow it to grind the food into smaller pieces, called chewing its cud. Once it is done chewing, the cow swallows the food into a third compartment called omasum. The omasum absorbs the fatty acids that were not absorbed by the rumen.

Finally, the food that is left gets passed to the final compartment called the abomasum. The abomasum works like a human stomach. It secretes acids to break down the remaining food.

This is the back story behind chewing the cud.