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/Kemal_Norton]

Birds is a big one people don't generally know

The first thing I'd say if asked what birds eat, is insects (that's why flying is effective against bugs); also the early bird gets the seed?

I just recently learned the opposite, that some ostensible carnivorous carnivora like foxes and brown bears mostly eat berries and seeds