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  • Writer's pictureK.L.

The Science Behind: How Cows Produce Milk

Cover page- Ishita Baghel

Q: What do cows do in their free time?

A: They Watch Moo-vies!

Unfortunately, it's true. Cows are a major victim of being in bad jokes. However, they think it's a moo-racle for their kind! (See what I mean?) Anyways, aside from being a part of dad jokes, cows play quite an important part in our lives. They help us produce all sorts of dairy products, the most common being milk. But how exactly do they produce milk? Let's find out!


Like humans, cows have five main food groups. In order to produce milk, cows need to be well fed. Keep this in mind: A healthy cow is a happy cow, which gives us more milk. The five main food groups of a cow are pasture, hay (dried pasture), silage (green cut pasture), grains, and forage crops. Pasture is a land covered in grass and is the main food group for cows. The other food groups revolve around pasture itself. Cows eat 20 kilograms of food per day! Along with the nutrients found in food, cows also need a LOT of water to produce milk. As you see, cows are quite the foodies! In addition to food, cows also need a good amount of rest and sleep to produce milk (14 hours).

How Milk is Produced

A normal cow weighs about 1 ton and its stomach has four parts. The fours parts are:

The Rumen - Largest part of the stomach. It contains the enzymes to trigger the digestive process. The rumen helps break down the food eaten.

The Reticulum -It traps anything that the cow shouldn't have eaten. It serves as a kind of fort or wall to a castle. The reticulum also softens the eaten pasture or grass and turns them into tiny wads of cud. (Cuds are partly digested food sent from the first part of the stomach to the second to be re-chewed.)

The Omasum -This part of the stomach filters the food, squeezes out water and breaks the cud down even further.

The Abomasum -It finishes off the process of digestion and passes the nutrients gained from the food to the bloodstream. When you think about it, a cow's digestive system is somewhat like a relay race.

If you know how a cow is milked, you may notice a body part called the udder. This is where farmers collect milk from the cow. Remember the abomasum? I mentioned that it passes nutrients to the bloodstream. A cow's circulatory system relays the nutrients and water all the way to alveoli (microscopic sacs) in the udder. In each alveolus are some epithelial cells (cells that line the body) capable of producing milk. Each alveolus, with the help of the epithelial cells, can contain up to 0.01 mL of milk. Once the alveoli are full, myoepithelial cells push the milk into the milk ducts and milk chamber. A cow has 5-20 milk ducts that separate into smaller milk ducts. And so, that is how a cow produces milk.

Fun Fact

Cows can only produce milk when they are pregnant or when they have a calf (or calves). Milk production doesn't only involve the stomach and circulatory system, it also involves many hormones that can only be stimulated through pregnancy.

I hope you like this article and continue to enjoy the feeling of discovering something new.

Keep moo-ving on with learning,






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