How Do Cows Digest Cellulose?

Human enzymes can digest various types of food. However, we lack the enzyme needed to digest cellulose – an organic compound that can be found in hay or grass. In contrast, cows can eat almost anything plant-based, including grass. If you are curious about “how can cows digest cellulose?”, find the answer in this article.

Why can cows digest cellulose but humans?

Cellulose is a complex carbohydrate compound found in plant cell walls, including grasses, kale, lettuce, and other vegetables. Humans can only digest vegetables but grasses.

The reason is that vegetables, including spinach and kale, contain certain ingredients that the human stomach can break down and absorb. Meanwhile, grass contains a large amount of cellulose, which forms a strong bond that no human enzymes can crash.

Cows are part of the ruminant class, along with sheep, buffalo, and goats. These animals have symbiotic bacteria in the intestinal tract. These symbiotic bacteria obtain enzymes that can digest cellulose in the digestive tract.

cow ruminant

In addition, the cow’s stomach consists of four separate compartments, each of which is necessary for a certain digestive process. In this way, the cow can easily break down cellulose and digest them.

How do cows digest cellulose?

The process of how cows break down cellulose is quite interesting. When the cow begins to eat grass, it goes down the esophagus, which is a tube that connects the throat to the stomach.

After the grass is partially digested by small microbes in the first chamber of the stomach, it goes down to the second compartment called the reticulum. In this chamber, the grass is turned into cuds of grass.

In the next step, the animal will start its regurgitation process. The cuds of grass which previously formed in the second stomach cavity are pushed back to the mouth so that the cow can chew a little more and break it into pieces. The cow then swallows the grass pieces again then sends them back to the stomach.

This cellulose breakdown process can take hours. The cow will repeat the above process until the whole cellulose in the grass is converted to nutrients. That is also the reason why people usually see cows as slow eater creatures.

Anaerobic bacteria in cows’ digestive system

cows’ digestive system

Hundreds of small species such as bacteria, protozoa, and fungi live in different parts of the ruminant gut. The anaerobic bacteria usually locate in the first compartment of the cow’s stomach. It is also known as rumen and is responsible for the actual digestion of the grass.

At the rumen, the anaerobic bacteria decompose the cellulose in the grass and digests it without oxygen. These bacteria will release various enzymes that help digest cellulose. These enzymes are also known as catalysts that help break down cellulose into smaller parts such as glucose.

Those compounds then enter the third chamber of the stomach, which is called the omasum. In this area, they are fermented into essential nutrients.

Finally, the digested grass eventually enters the last chamber – the abomasum. It contains acids that are similar to the human stomach. In this chamber, the leftover grass will be digested a little more, then reaches the small and large intestines.

How do other animals digest cellulose?

Over millions of years of evolution, different animals adapted to different climates and conditions to survive. As a result, their digestive system will also vary depending on the type of nutrient consumption and environmental conditions.

For some animals, such as pigs or horses, their digestive systems contain the bacteria needed to break down cellulose, but fermentation takes place mainly in the intestines, not the stomach.

Some monkeys are known for the miraculous evolution of nature. After a long period of adaptation and survival, they created a way to absorb cellulose in the leaves of the plant, known as a leaf-oriented diet. These mammals developed an enzyme lysozyme that has properties similar to that found in ruminants. Hence, they are able to break down cellulose and benefit from the nutrients obtained.

Final Words

The cow’s digestive system is considered to be one of nature’s amazing achievements. Thereby, the cow is able to separate indigestible substances like cellulose and turn them into nutrients. It has also shown us that nature still has a lot of new things to explore, especially the mysterious truths of other creatures living on this earth.

We hope that this article not only helps you answer the question “How do cows digest cellulose?” but it also gives you new knowledge about the amazing animal world.

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