Do Deer Chew Cud – Digestive System Facts

Written By John VanDerLaan 

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Have you ever heard the expression, “You chew like a cow!”?

I have, thanks to my chewing habits, but that saying comes from a place of truth.

Deer, as well as cattle, sheep, and giraffes belong to a class of herbivorous animals called ruminants and ruminants chew cud.

In the video below, you will not only see a deer chewing cud, but you can actually see the deer swallowing the cud and bringing it back up to chew again.

What is Cud?

Deer and other ruminants regurgitate partially digested food, and chew it to break it down further, and then the deer re swallows the cud.

Cud is the partially digested food that the deer bring back up to chew a second time. It is usually about the size of a lemon.

This is known as ruminating, and is also called chewing cud.

A whitetail deer chews its cud around 40 times while a mule deer chews its cud around 60 times other deer species will vary according to diet.

While it may sound absolutely disgusting to humans with a regular digestive system, there’s a reason for the madness behind a deer chewing cud, and it’s all thanks to the deer digestive system.

Deer's Digestive System

Deer digestive system

Image credit: Wikipedia

Remember the word ruminants? 

An animal that belongs to this category is herbivorous, and they tend to have to go through a few extra steps to extract all of the necessary nutrients and break down the food that they consume.

Deer eat a ton of cellulose, but deer and other ruminants cannot digest cellulose, which is why they have four stomachs and why deer chew cud.

That’s why Mother Nature gifted ruminants, like the white tailed deer and other deer species, with special stomachs to digest their food. Where humans have to make do with a monogastric stomach, ruminants come equipped with four-stomach chambers.

Having a four-chambered stomach allows them to be extra thorough when digesting occurs, and with good reason. When deer feed, they don’t get to have the luxury of eating food and laying down after a nice meal. 

The name of the game for a deer when it comes to food is the following:

Eat as much plant matter as they possibly can in one sitting, especially when competition is nearby.

Make sure that the food that they eat is also good for the micro organisms that live in their guts.

The deer fills its paunch, or rumen and heads to their bedding area.

The deer bring the cud back up and chew on it to make digestion easier.

Then pass it through the four chambers in their stomach after they chew the cud enough for digestion to occur.

Here is a cool video of a whitetail deer buck bedded down and chewing its cud.

How Many Stomachs Does a Deer Have?

Deer have four stomachs, commonly referred to as four chambered stomachs and each stomach chamber serves a very important process in the deer digestive system.

Deer chew cud to maximize their digestive process.

Having a full stomach sounds great, especially if you have four chambers in the stomach, but when that belly is full of plant life that isn’t exactly the easiest to digest, you’d want to find a way to take some pressure off of things.

First Chamber: Rumen

When deer go to forage on grass and other browse, contrary to popular belief, they don’t chew their food all the way through. deer chew enough so that the food is safe to swallow.

When they first swallow food, the food passes into the first section of the stomach called the rumen. The rumen could basically be considered a waiting room, being the chamber that holds the food when the deer loads up. The rumen portion can hold about two gallons of food for a deer.

After they get to their bedding area, they will lie down and begin to bring the cud back up and start chewing on it before swallowing it and sending it back to pass through the second chamber.

Second Chamber: Reticulum

Since deer eat plant life that contains cellulose, which is basically the part of plants that isn’t digestible, their stomachs are going to need a way to separate the good stuff from the bad stuff.

And that’s where the second portion, known as the reticulum, comes in.

The reticulum portion of the stomach could basically be considered the strainer of the stomach.

After the food has been through the first cycle, the cud comes through the reticulum, where the reticulum puts a filter on the incoming cud.

The good bits that are digestible go through the fermentation process, which makes it easier for the third portion to step up and pull its weight.

The cellulose?

It's still a stomach, so the cud that can’t be broken down with digestion is going in the waste bin.

Fun fact, deer are known to defecate and urinate almost twelve times a day.

The digestion that takes place within the reticulum can take around sixteen hours by itself.

Third Chamber: Omasum 

There’s still more to chew, and another chamber that the re-regurgitated cud has to pass through.

After the cud has been processed via the second chamber, brought up and chewed on again, it gets swallowed and passes into the third section, the omasum.

The omasum is the water absorber, taking all of the water out of the foods where it is absorbed into the body for the deer's energy.

After this stage, the deer brings it back up one last time into the deer mouth to be ground up even further before reaching the fourth, final stage in the deer digestive system.

Fourth Chamber: Abomasum

The abomasum is the true stomach and last chamber, full of the gastric juices required to fully digest the food.

This is where the chewed food is sent last, where deer digestion occurs, very much like human digestion.

When the food enters the abomasum, the gastric juices, like hydrochloric acid and enzymes in the deer’s stomach come together to strip the cud of all of its nutrients, leaving the rest of the food to go into the intestines, where it is turned into waste droppings.


Yes, deer chew cud and now you know why!

You have learned that deer belong to a family of herbivores called ruminants, although they will occasionally eat meat.

You also now know that the process of bringing food back up to chew again is known as ruminating and is commonly called chewing cud.

Cud chewing makes the deer digestion process smooth sailing, breaking down the food into something easy to digest.

Exactly what deer eat will depend on the habitat in which they live and the time of year. Deer and other mammals will have a different diet in the winter as compared to the summer and as a result may have more or less cud to chew.

Deer are primarily crepuscular and will lie down and chew their cud in between their daily feeding cycles.

Now we know what deer eat and why deer are always chewing!

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John VanDerLaan

John VanDerLaan is the managing editor here at He oversees a team of editors, writers and pro staff that are subject matter experts in hunting and hunting gear. John's expertise includes thoroughly testing all types of hunting gear, as well as hunting all over the U.S. and Canada. While his hunting expertise includes game birds, small game and large game, his favorite game animal is the whitetail deer and he loves to share the knowledge that he has gained over 40 years of chasing the wily whitetail with both archery gear and firearms. John is an active member of the Outdoor Writers Association of America.

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