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How Do Cows Digest Food?

Last Updated: 22.04.24



It is believed that cattle creep feeders can help you add 80 to 100 pounds to the weaning weights of calves. Also, creep feeding is very economical and will help calves suffer less setback at weaning and adapt to feedlot rations quicker than those calves that aren’t fed a grain-based creep feed.

According to some studies, cows are generally quite intelligent animals that are able to remember things for a long time. And what is even more interesting about these gentle giants is the fact that they have four-compartment stomachs. Hence, they have this amazing quality to break down all those tough and coarse foods that many animals don’t.

But, they need to undergo a special digestive process in order to be able to do that. If we made you a little curious, you should read further, as you will find some really interesting facts about a  cow’s digestive system.



Cows have their own special way of digesting food, and it all starts from the very moment they take their first bite. You know how we chew our food very well before we swallow it, and there are many animals who do the same as us. But with cows, it is different! They only chew their food for a little before it is swallowed.

They do this because they have the option to voluntarily re-chew that food and this will improve their digestion. This is an important characteristic of the digestion in cows and this process of re-chewing and re-swallowing is called rumination. You must have heard people referring to cows as ruminants, and now you know why.

Also, as we have already mentioned that cows have a four-compartment stomach (rumen, reticulum, omasum, abomasum) and it is important to know that the largest one is the rumen. In order to be able to understand how large this compartment is, you should imagine a 55-gallon trash can.

Pretty big, right? Well, thanks to this, cows are able to consume large amounts of grass. The next step, after filling up on grass, is to take a break from standing but not from eating. So, they lie down and chew their food more thoroughly, and now is when the rumination takes place.


Now that we know what the rumen is, let’s see how it actually works. In order to be able to break down complex foods and release nutrients that the cow can digest, the rumen contains many microorganisms that help cows do just that. These tiny organisms are extremely important because without them the cow would starve.

It is believed that there are more organisms in the rumen of a single cow than there are people on Earth! The most common organisms inside the rumen are bacteria – there are many different types but only 20 of them have been studied and analyzed.

Studies show that half of the tiny organisms are bacteria and the other half consists of protozoa and fungi. All of them coexist and cross-feed, and they all have specific functions. Some bacteria, for example, are responsible for carrying out the digestion of starch, sugars, protein, and fiber.

While some are in charge of keeping the rumen clean so that it doesn’t become toxic. Protozoa are known to convert sugars to starch or to consume starch and cellulose. And, fungi can digest cellulose and break open the starch fibers in grass and plants.


Rumination and saliva

Cows chew their feed for a little and then after saliva is added and the feed takes the shape of a bolus, they just swallow it. A cow has the ability to ruminate, which means that the feed will come back into her mouth and she will chew it again.

This stage is extremely important because this is when most of the reduction of feed particles occurs. A cow can produce between 40 and 150 liters of saliva per day, depending on the cow’s diet.

If more rumination is involved, it is easy to imagine that the cow will produce more saliva. Saliva is important because it helps cows to counteract the acidity that can be produced by certain foods like cereals, molasses, potatoes, and fodder beets.

Also, saliva has the role to reduce the risk of bloat as it has a suppressing effect inside the rumen.  Sometimes, if the cow eats too many grains, the rumen can become too acidic and it can lead to serious health issues. That is why it is recommended that a cow’s diet should consist of mainly silage and haylage.

Reticulum, Omasum, and Abomasum

We know how the rumen works, so now let’s have a look at the other three compartments from the cow’s stomach. Reticulum works closely with the rumen – it is actually attached to it. The rumen contracts every minute, and as a result, feed particles of the correct size and density are segregated into the fluid in the reticulum.

And, since the contractions don’t stop, they will force these particles and some of the fluid contents into the omasum. In other words, the reticulum acts as a storage area before passing feed to the omasum or for regurgitation. The cow can chew the feed over and over again and then re-enters the rumen for more digesting.

And, because the reticulum has a “honeycomb” surface anytime the cow eats screws or nails, they will end up at its bottom. You must have heard about the “hardware disease”, and this happens when the hardware (nails or screws) perforate the reticulum wall. The omasum is the third compartment of the cow’s stomach where the water from feed particles is absorbed.

It has many “leaves” of tissue which provide a wide absorption surface (about 4-5 m2). Also, this surface not only absorbs water but it also absorbs nutrients such as potassium and sodium. The final digestion happens in the abomasum which is very similar to a human stomach – the feed is further broken down before it passes into the small intestine.




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Diana Murphy

July 7, 2020 at 3:29 pm

Thanks for this article. Easy to understand.


July 8, 2020 at 7:31 am

Thank you for your appreciation, Diana!

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