Considering that the average cow weighs anywhere from 900 to 1,600 pounds, you might be wondering how cows are able to get all the protein they need. Surely, grass doesn’t contain enough protein to encourage maximum growth and ensure that all of the functions in a cow’s body work optimally?

While cows might primarily consume grass, they also eat foods other than grass that provide them with enough protein, including soybeans, alfalfa hay, and protein supplementation.

4 Best Sources of Protein for Cows


Wait a minute. Didn’t we just say that grass doesn’t provide enough protein for a cow’s needs? Yes, but you might be surprised to learn that grass actually acts as a great source of protein for cows, but this is only because cows are ruminants.

So it isn’t so much the grass that is the source of protein, but more the bacteria that grows on the grass that a cow is able to then ferment in its stomach. This bacteria breaks down the cellulose in grass and converts it into amino acids, which in turn provide protein for cows.

So that is how cows get protein from grass that is able to help them grow into the very large animals that they are.


Soybeans are approximately 40% crude protein and 20% fat. The protein in soybeans is approximately 70% rumen degradable and 30% rumen undegradable while having a total digestible nutrient value of 91%. What this all means is that soybeans are a great option for cows to get the protein they need.

However, as the high-fat levels found in raw soybeans can negatively impact fiber digestion, it’s important that cattle do not overconsume soybeans, especially growing calves, whose diet should consist of no more than 7% of soybeans.

Alfalfa Hay

What makes alfalfa hay such a great source of protein for cows is that its highly digestible and rapidly cleared from the rumen, which increases intake and therefore makes it an efficient way of obtaining protein.

Early cut alfalfa contains 16 to 20 percent crude protein, while even late cut alfalfa still typically contains a high amount of crude protein at 12 to 15 percent.

Often, especially during winter and during a poor hay production season, or with hay produced under low levels of management, additional protein is required.

Protein Supplementation

Protein supplementation can be a great way for cows to get their protein needs met, but it isn’t without its downsides – mainly to the farmer/rancher. Protein supplementation requires feed, labor, fuel, and equipment that all quickly add up in cost.

Protein supplementation is available in many forms and includes protein blocks, liquid supplements, and range cubes.

How Much Protein Do Cows Need?

The amount of protein that cows need varies depending on the size of the animal, the stage of production, and expected performance. Young, growing cattle and lactating cows are most likely to require protein supplementation.

During lactation, for example, larger cattle typically require a higher amount of crude protein per day than smaller cattle, though smaller cattle will require higher quality feeds and forages.

The reason that younger cattle that are still growing require high levels of crude protein in their diets is to support muscle growth.

As a general rule, just remember that cattle require more crude protein with increasing lactation and rate of gain.

Why Do Cows Need Protein in Their Diet?

Protein plays a very important role in a cow’s diet because it makes sure that many of the functions in a cow’s body are working correctly.

Adequate protein intake ensures that a cow’s vital organs and systems operate as they should, including mammary gland activity, reproductive and immune functions. Adequate protein intake also ensures that a cow will reach its maximal growth.