Cows and almost all cattle are ruminants. So, what are ruminants? Ruminants are cud-chewing hoofed mammals with a four compartment stomach and occasionally three. Cow being one among them and you may be wondering you have always seen one stomach for it and how can the numbers climb up. Yes, you are technically right. The cow has only one stomach strictly speaking. But, in actual terms it is been divided into four chambers to form four stomachs. Now you know how many stomachs does a cow have? Read further to get into the each type of stomach and reason for a four-chambered structure.

How Many Stomachs Does A Cow Have?

How Many Stomachs Does A Cow Have

Unlike humans, the structure of cow stomach varies and that is the reason why it is counted to be four. Initially, let us see the parts of the cow’s stomach:

Rumen– It is the first part of the cattle’s stomach. The process of breaking down of complex foods grass or sophisticated plants is done here.

Reticulum– The cud gets produced here when the cow’s saliva is combined with the food. Further, the cud burps up into the mouth and the cattle chew it down to break it into fine particles. You might have noticed cow continuously chewing on something similar to bubble gum then she is processing her cud.

Omasum– All the water content in the food is absorbed here.

Abomasum– The destination of the food and it is completely digested here and the process is similar to that take place in the human stomach.

Cow’s Diet


The platter of the cow consists of hay silage, distillers grains, corn silage, grain (corn), soya bean meal, hay, and wheat.

Rumen And Reticulum

After the food consumption, it is chewed slightly and combined with saliva and once swallowed moved to rumen through the esophagus.

The rumen appears similar to a vat as it aids storing of food and mixing. It provides constant temperature, pH and an anaerobic environment. The region receives well grind substrates from the oesophagus on a regular basis. Fermented products here are absorbed either in the same region or allowed to pass down through the system.

One of the primary functions of the rumen is to subsist on roughage. Shrub and grasses that are rich in cellulose. Rumen is designed for fiber digestion. This forms the largest part of the mammal’s stomach. Sometimes it is referred to as “fermentation vat.” To facilitate better nutrient absorption and the surface area the inner layer of rumen has papillae and tiny projections.

A ridge of tissue separates the reticulum from the rumen. The lining of the tissue appears honey-comb like due to the small papillae present here. Both reticulum and rumen can hold up to 50 to 120 L of fluid and food. The temperature inside the rumen remains around 39 degree Celsius (or varies in the range of 38 to 42 degree Celsius). It is most suitable for a range of microbes to thrive.

Under the normal circumstances, the pH value of rumen and reticulum contents lies between 6 and 7. A stable pH value is maintained by continuous removal of the acidic products resulting from the microbial fermentation. And simultaneously, adding bicarbonate from the saliva.

Rumination Followed By Chewing

The mechanical action of chewing breaks down the food into small particles before reaching rumen. Further, the chemical breakdown in rumen takes place with the help of enzymes secreted by the microbes present in the rumen. By combining rumen microbes and fluid, the food components are continuously churned to further simplify the food. The rumen and reticulum wall has contractions and that helps the movement of fine food particles into the next part omasum.

Rumination is the process where the newly consumed food is brought back to the mouth for advanced chewing. The advanced chewing broke down the food into further fine particles resulting in increased surface area of food particles. Consequently, food becomes easily accessible to rumen’s chemicals. Hence, the rate of microbial digestion is increased.

Depending on the fibre content in the food, the process of rumination or chewing cud takes time. If the food is rich in fibre, then it takes more time for rumination and if it is minimal, the rumination session remain smaller. When the feed is less then, milk produced is less.

While food stays in the rumen most of the nutrients, get absorbed across the wall. Further, absorption aids the movement of food components through the wall to get into the blood stream from the digestive tract. From the bloodstream, it is transferred into the liver.

The process of food flow through the rumen is continuous. Remember food when longer than 1 mm cannot move through the rumen until its length is reduced. Therefore, the rumen is the primary regulator of feed consumed.

Food Traverse Through Rumen

Digestion to some extent depends on the passage of food material in the rumen. Generally, the rate of food passage and digestion depends on particle size, density, the level of feeding, and ease of digestion process. Few foods make their way through the digestive system quickly and easily while some hard foods take a long period to get excreted.


Omasum occupies the space between reticulum and abomasums. The output of reticulum that enters omasum have water as a primary component. Say, about 90% to 95%. The functionality of the omasum is to remove the water content from the infeed and further digest it into the fine particles. Omasum has folds that appear large and are called laminae.


It is the connective between small intestine and omasum. This is the place for acid digestion and it is similar to the human stomach. The walls of abomasum are folded to form ridges that secrete gastric juices containing some enzymes and hydrochloric acid. The pH of the region remains between 1 and 1.3 this makes the area acidic with a pH of 2. Rumen microbes are killed by the acidity of the place. Enzymes likely pepsins carry out the digestion of dietary protein in the same part.


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