Why Does A Cow Eat Grass? Beginner Basics

Cows eating grass, notice the sheep in the background.

Why does a cow eat grass? A cow has a pretty big body to support and grass doesn’t look too filling.

How can cow and a bunch of other large animals wild or domestic survive and actually thrive on grass?

Cows are biologically designed to eat and thrive on grass. Cows have a specially adapted stomach that has four compartments, which allows her to combine cud chewing and digestive microbes in order to digest fibrous plants.

Maybe you’ve thought to yourself how can an animal that big live and grow on grass.

Eating vegetable matter only does not provide many calories. We all know this-think dieters and salads.

We’ll be looking into the basics of cows eating grass-getting into some things you probably knew or were pretty sure of and some things that just may be totally new.

How To Select A Family Cow goes over the basics of what you need to look for if you are thinking about getting your own milk cow!

Maybe you are looking for a starter herd of beef cattle? Read Getting Your Starter Herd to show you the things you should be looking for and looking to avoid when buying cattle.

Cows are biologically designed to eat grass

Cows eat grass because grass and other forages (plants the cow can eat) are the food source cattle are biologically designed to eat.

Grass grows all over the world. Cows can eat the grass fresh from the plant or can eat it dried and stored in a barn to be feed later in the year. This dried and stored grass is called hay.

Grass has the ability to remain nutritious through the winter. Even when the grass is dormant (not growing) cows can eat any of the plant that is still standing from the previous growing season.

Many farmers keep their cows out of some of the pastures leaving the grass to grow then be eaten by the cows in the winter.

This is also why wild herds of grass eaters move around-they are looking to find an area of grass to eat in the non growing season.

Jersey cow grazing
This is our family cow, Aleene. She is a Jersey.

Eating grass is called grazing

Eating grass is called grazing. When a cow gets her lunch from the grass out in the field she is grazing.

Grazing is the term also used to describe any wild animal eating grass for a meal.

Here’s a short video of Aleene, our family cow, grabbing grass with her tounge. This is how all cattle eat, since cattle only have bottom row teeth!

A cow grabs grass with her tounge

This is one of those things that might surprise you-cows do not have upper teeth!

She eats by wrapping her tounge around a hunk of grass to hold it then kind of sawing off the blades of grass with a sideways motion of her lower teeth against the top ridge of her jaw.

Every bite, over and over until she’s full.

Grass is perfect food for a cow

Cows can survive on grass because of a special digestive system that makes a cow and other grass eaters like her able to digest things that animals like us cannot digest.

A cow has a four compartment stomach that allows her and other animals with the same special stomach to get nutrition from plants.

Animals like us with a more simple stomach cannot get nutrients from the plants the cow is eating.

Here is an article from Big Picture Beef on why grass is such a great food source for cattle.

Cattle are ruminants, they can live on grass

The ability to digest these plants is what makes the cow a ruminant. A ruminant is an animal capable of digesting plants that we cannot because of her digestive system-specifically the four compartment stomach.

Her stomach has millions of organisms mostly bacteria that allow her to get nutrition from grass.

She will eat grass or other forages until she feels full then she will chew her cud.

Chewing her cud means she makes little bundles of grass and brings it back up to her mouth in order to more completely chew the forage fibers.

Her single celled workforce (all the organisms in her stomach) need well chewed food so they can utilize all of the energy and nutrients the forage has to offer.

Cows are not always eating

Cows like to take in all of their grass as quickly as they can so they can get to chewing their cud.

A cow is actually only eating if you are seeing the grass or hay go into her mouth and be swallowed.

Cows spend lots of time chewing cud

After she swallows she finds a comfortable place to sit so she can thoroughly chew her cud.

She will spend hours a day chewing her cud to grind up the grass as much as possible.

Grinding up the grass gives her micro organisms in her specialized stomach complete access to all of the nutrients in the blades of grass.

If you are looking for other interesting cow behavior explanations consider clicking here for another of my articles on cattle and why they do what they do.

Cows can eat other forages

Cows can eat a number of things besides grass.

Many herbs, broad leaf plants and even weeds that will naturally grow in a mixed pasture are high on the list of good stuff to eat as far as a cow is concerned.

Some people choose to feed grain like corn to their cows. Feeding grain is very common on farms.

Grain has a lot of energy in the form of carbohydrates that is easy for the cow to get. It does not take long at all for a cow to eat a scoop of grain.

Cows use the carbs in grass for energy

Actually with plentiful high carbohydrate grasses she can get fat just by eating grass.

For the health of the cow staying in good shape-not too fat not too thin-will give her the best life. This is the same for any animal including other livestock, pets and people

Cows can eat many types of grass

A cow can eat nearly any type of grass that other livestock like sheep or wild grass eaters like deer would eat.

The grasses grown for hay, like orchard grass and timothy, are easy choices but also common yard grass like bluegrass will fill her up.

Cows stop eating when they are full

She will stop eating when she has eaten enough forage to be full so now it is time to start chewing her cud.

If a cow totally stopped eating, for instance she did not eat anything today, something is up. You need to investigate.

Your cow is counting on you to look after her.

Not eating is a huge red flag health wise that something is wrong. This is true for any animal and people too.

Related Questions

What do cows eat in the summer?

Most cows eat grass in the summer and hay in the winter.

Why does a cow have four stomachs?

Actually, a cow only has one stomach.

Her stomach has four compartments kind of like you have one house with multiple rooms. The four compartments allow her to digest plants that people can not digest.

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