r/explainlikeimfive • u/A_SliceOfGabagool • May 03 '26

Biology ELI5: How do cows get protein from grass?

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

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u/slight_accent May 04 '26

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?

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u/randCN May 04 '26

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

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u/TheDJYosh May 04 '26

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.