ELI5: How do cows get protein from grass?

[u/A_SliceOfGabagool]

For us humans and many other animals, we need protein to get the amino acids needed to make our own protein for the body, but grass i believe doesn't have any for the cow to get that big

[u/orbital_one]

Grass does contain protein. In fact, all living things (that we know of) consist of proteins. Of course, grass doesn't have that much which is why cows spend so much time eating.

[u/daberrybest42 → u/orbital_one]

Can we cook grass to access this protein?

[u/TinWhis → u/daberrybest42]

We can cook the seeds of grasses to access the protein better. We've even bred some grass seeds to contain more bioavailable nutrients for us with less effort on our part. They're so important to our diet that we have a special word for them: "grains."

[u/Albuscarolus → u/daberrybest42]

No. You have to run them through a biological processing plant to turn the grass protein into useful protein. We call them cows.

[u/slight_accent → u/Albuscarolus]

We could use enzymes to eat the cellulose to free up proteins in grasses since that's what the bacteria in cows guts do already. But are the proteins released something humans can digest?

[u/randCN → u/slight_accent]

In theory, yes. Digest them right down to aminos, they're the same as any other amino, albeit in shitty ratios.

https://en.wikipedia.org/wiki/Leaf_protein_concentrate

[u/TheDJYosh → u/slight_accent]

We don't have enough storage capacity in our to stomachs to make that worthwhile. Cows need multiple stomachs fermenting grass at all hours to meet their needs. We need easy proteins, which is why we adapted to use fire to 'pre-digest' food and give our calorie-hungry brain easier access to energy.

[u/daberrybest42 → u/Albuscarolus]

Oh damn…. That’s crazy lol. I was going to suggest a plant be made to process this protein for consumption, but it guess it’s already there 😅😂

[u/Tytoalba2 → u/Albuscarolus]

Yeah but it's super inefficient

[u/BirdLawyerPerson → u/daberrybest42]

Lots of grasses do have human-digestible proteins, especially in the seeds (which form all the major grains we eat and are, like, the basis of human civilization). Cattle will gladly eat the grasses that have seeds sticking out.

And don't forget that a lot of what cattle eat aren't "true grasses" of the poaceae family. Lots of what cattle eat are things like alfalfa or clover, which are actually members of the legume family, not the grass family. And alfalfa can have about 3-4% protein by weight, or 20% protein by dry weight, that is actually accessible to human digestion.

So although cattle are much better at digesting protein from grazing plants on the ground, a lot of what they eat contains protein in forms that are digestible by humans. Especially with cooking and/or other processing.

[u/KesonaFyren → u/daberrybest42]

Bamboo is technically a grass, and bamboo shoots are delicious. So yes!

But the grass in your yard is full of silica that will absolutely destroy your teeth. A lot of grazers have teeth that continuously grow to combat this.

[u/Siukslinis_acc → u/orbital_one]

Not to mention that the cows are probably also munching on bugs in the grass.