Cow Digestive System?

Cow Digestive System?

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Most animals have only one stomach, and so do humans. The digestive system matches the food that the animal eats, and that’s why it shouldn’t come as a surprise that cows have 4 stomachs. Just think about it, when dogs eat grass they throw it up, because they are unable to process it. Cows need a more complex digestive system so that they can digest the grass. How does the digestive system of a cow work?

A cow’s digestive system consists of 6 components: mouth, esophagus, 4 compartment stomach, small intestine, cecum, and large intestine. The 4 compartments of the stomach are the rumen, reticulum, omasum, and abomasum.

A cow is a ruminant, which means that it is set apart from other animals because of its complex digestive systems. They process food, absorb nutrients, and gain energy differently than other herbivores. This kind of stomach is typical for cattle, elk, sheep, goats, deer, giraffes, water buffalos, and camels.

What kind of digestive system does a cow have?

The cow is a ruminant, which means that it belongs to a group of animals that are set apart from other mammals because of their complex digestive system. They process food, absorb nutrients, and gain energy differently than other herbivores. 

The cow has a digestive tract that consists of six parts which are the mouth, esophagus, a complex four-compartment stomach, small intestine, cecum, and large intestine. Its stomach includes the rumen or paunch, reticulum, the omasum, and the abomasum.


The whole process starts in a cow’s mouth. The cow grazes by wrapping its tongue around plants and tearing, pulling them into its mouth for chewing. It starts by chewing with the lower jaw incisors, then with the molars, which serve to grind plant material down further. 

Before the cow swallows, plants will be mixed with the saliva. Saliva contains enzymes that are capable of breaking down fats and starches and help buffer the pH levels in the reticulum and rumen segments of the stomach. An adult cow will eat from 50 to 80 quarts daily to aid in digestion, but the amount will vary based on how much time it spends chewing.


Once the plants and the saliva mix and the cow swallows, the mixture will travel down the esophagus to the rumen. The esophagus can move feed from the mouth to the stomach or from the stomach to the mouth. Cows need to move their feed from the stomach to the mouth so they can regurgitate feed that wasn’t chewed well enough and chew it again. When the cow is done chewing again it will swallow once again.


The stomach will then further break down the feed. It consists of 4 compartments, and each one has a special function. Once the feed is dissolved and all the proteins and minerals are absorbed, it is time for it to move to the next section.

Small intestine

The small intestine consists of three sections, duodenum, jejunum, and ileum. They work together to complete the digestive process. Duodenum is a section that is connected to the stomach, and it is where secretions from the gallbladder and pancreas mix with the partially digested matter.

This process will balance the pH in the cow’s intestine, and ensure that the digestive enzymes work correctly. The next section is the jejunum. It is lined with small, finger-like projections known as villi. They increase the intestinal surface area and absorb nutrients.

The last section is the ileum. It serves for absorbing vitamin B12, salts, and any nutrients that passed through the jejunum. At the end of the ileum is a valve, which prevents any backward flow of materials. In an adult cow, the entire organ can be up to 150 feet long and has a 20-gallon capacity.


The cecum is located between the small and large intestines. It is a three-foot-long pouch. Its only function is to provide storage and a transition between the two intestines. It has about a two-gallon holding capacity.

Large intestine

A large intestine is smaller in length but larger in diameter than the small intestine. It is the last step of the digestive process. Its job is to absorb the remaining water, and it has bacteria microbes that finish digestion and produce vitamins that the animal needs to grow and remain healthy. It also helps eliminate any undigested and unabsorbed food from the system in the form of waste. 

The entire digestion process takes between 1 and 3 days. 

What are the 4 stomachs of a cow?

The most important part of a cow’s digestive system is its stomach. It has 4 distinct compartments, each with its specific function. The 4 parts of a cow’s stomach are the rumen, reticulum, omasum, and abomasum.


The rumen, which is also known as the “paunch” is the first area of the cow’s stomach and is connected to the cattle’s esophagus. Rumen acts as a storage unit for eaten vegetation and forms balls of cud. Cud is big, non-digestible pieces of plant material that have to be regurgitated, chewed a second time and swallowed before continuing through the process. The rumen can absorb nutrients through the papillae of its wall and promotes fermentation, creating the rumen bacteria and rumen microbes which are necessary to break down and digest the proteins in feed.

There are microorganisms in the rumen that serve for digesting cellulose and complex starches, as well as synthesizing protein, B vitamins, and vitamin K. Rumen can hold up to 40 gallons of material as a storage unit. Combined with the reticulum, the rumen makes up about 85% of the volume of the entire stomach. 

Health issues that can occur with the rumen are bloating, which happens when a cow can’t eradicate a buildup of gas, acidosis, and rumenitis, which happen when there is a high acid production due to low pH balance. You can prevent these by managing and paying attention to cattle’s food and water intake.


The reticulum is also known as the “honeycomb” because the inner lining and its structure appear similar to a honeycomb. It has some independent functionality, and it is attached to the rumen with only a thin tissue divider. This divider holds heavy and dense objects, for example, rocks and metals, and traps large feed particles that are not small enough to be digested. 

The reticulum makes regurgitation easier. The rumen and reticulum both contain digestive bacteria, so no acid is included in the regurgitation of materials. Unlike the rumen, the reticulum holds only about 5 gallons of material. A health issue that appears commonly and involves the reticulum is hardware disease. This disease occurs when cattle ingest heavy or sharp objects, for example, nails, screws, or wire. They are swept into the reticulum and there is a risk of them puncturing the stomach wall. You can prevent this disease by putting magnets on feeding equipment to catch any metal, or you can cure it by placing an intraluminal magnet that traps already swallowed objects.


Omasum is a globe-shaped part of the stomach and it is also known as “manyplies” thanks to its internal structure. Omasum is lined with big leaves and folds of tissue that resemble the pages of a book. These folds are there to absorbs the water and nutrients from the feed that passes through after its second round of chewing. When it comes to its size, the omasum is smaller than the rumen and reticulum, which makes up about 12% of the stomach’s total volume. It can hold up to about 15 gallons of material.


The abomasum, also known as the “true stomach”, is the last component of a cow’s stomach. It is called “true stomach” because it operates the most similar to a non-ruminant stomach. It is the only part of the stomach that is lined with glands. The glands are there to release hydrochloric acid and digestive enzymes to help the abomasum break down feed and plant material even more. When you compare it to the other parts, the abomasum is smaller and it takes up about 4% of the total stomach volume and only holds about 7 gallons of material.

Why do cows need 4 stomachs?

Cows technically don’t have 4 stomachs, they have only one, but it has 4 compartments. This kind of stomach is essential for eating grass. Each of these compartments has a vital role when it comes to digesting cow feed.

When a cow is eating grass, it tries to eat as much as possible, so that it is not exposed to predators for a long time. It only swallows grass without much chewing. This grass then sits in the rumen and reticulum, which serve as storing units. 

Once the cow finishes grazing and feels safe, it will regurgitate the grass from the rumen and chew it all over again. This is called chewing cud.

The rumen also ferments food, providing the perfect environment for bacteria to break down grass and feed off all the resulting sugar. The cow is then left with fat produced by the bacteria, which provides most of the cow’s energy.

The reticulum sorts out which food needs to be chewed and broken down again, and which can go on to be processed.

When the fermentation is done, the food goes on to omasum. This compartment sucks out water, minerals, and salt and returns them to the rumen. Recycling materials in this way helps maintain the proper environment for the bacteria to live in.

The remaining food goes to the abomasum. The grass is mashed in this compartment. What’s left of food can then go to the intestines. 

When this process is finished, the cow gets rich packets of energy housed in protein, sugar, and fat. 

Problems with cattle’s digestive system

Because there are so many stages in a cow’s digestive system, it is easy for many things to go wrong. Here are some of the most common problems that can occur.

Rumen impaction

The contents of a cow’s rumen should flow and move freely with decent hydration. If the cow doesn’t have sufficient water intake indigestible materials will likely pile up and compress within the rumen. This will stop the movement throughout the rest of the digestive system and keep it from functioning as it should. To prevent rumen impaction, make sure your cow has access to clean water and pay attention to see if it’s drinking an average daily amount.

Hemorrhagic Bowel Syndrome (HBS)

Diagnosing a reason for hemorrhagic bowel syndrome is hard because scientists have been unable to reproduce circumstances that cause HBS in cattle successfully. There are a few things that could cause it, like mold and mycotoxins, Clostridium perfringens type A or other bacteria like E. coli, improper management while trying to achieve higher milk production in dairy cows, or excessive dirt, soil, gravel, sand, or rocks mixed in with the feed. 

HBS will happen when there is a blood clot obstruction or blockage within the small intestine, which becomes distended. If this syndrome is not cured, the cow will most likely die. There are no certain cures or prevention methods, but maintaining rumen health may decrease the chances of HBS from developing.


Acidosis occurs in the rumen and it is a metabolic disease. A lot of things can cause it, including another illness, excessive or incorrect handling that causes animal stress and too much concentrate, and not enough forage. Once a catalyst causes the ruminal pH to change to 5.5 or lower the rumen stops moving, which makes the afflicted cow decrease its food and water intake.

The combination of the pH imbalance and decreased intake results in acid collecting in the rumen, which then further discourages the cattle from eating and drinking. This will cause good bacteria to die off, toxins will be released, and the amount of collecting acid will continue to increase.

That is why the animal will continue to avoid any kind of intake. If you don’t do anything about it, this cycle can compromise the intestine linings, which can lead to the leaky gut syndrome. This syndrome weakens the animal’s immune system and can potentially result in death. You can only break this cycle by successfully encouraging eating and drinking.

Fatty liver

Fatty liver is caused by excessive accumulation of fat in the cow’s liver. The risk of fatty liver is greater during calving time. It is caused by a negative energy balance, which occurs due to the growth of a calf, the beginning of colostrum production, and a decrease in dry matter intake.

All of this causes the cow to break down too much fat for the liver to handle. It can occur as fast as 24 hours after going off feed and will not decrease on its own until the cow can retain a positive energy balance. Some symptoms include a decrease in appetite, lower quantity milk yields, milk fever, ketosis, mastitis, retention of fetal membranes, and a reduction in fertility.

The best way to prevent fatty liver is to keep cows at an ideal body condition and encourage a low-stress environment, which includes avoiding sudden changes in their overall environment or feeding regimen.

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