We eat the seeds, not the blade. I would assume by "eating grass" op meant eating the grass blades. Maybe in the future vegans will genetically engineer themselves to chew their cud. That actually sounds like a cool scifi backstory.

Cow (field) corn is nasty shit, but CAFOs still feed it to cows and use antibiotics to keep them from dying from it. Google Image Search "muddy feedlot".

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

That has nothing to do with what I said.

It's also used to make corn chips, corn-meal, and the sweetener in everything Americans consume.

Yeap. And HFCS and ethanol for mandated use in gasoline.

We don't eat or are able to digest the majority of even those crops. Cows can eat alfalfa which is nearly free to grow and provides free fertilizer for the soil for future rotated crops. Not growing alfalfa would mean relying more on fossil fuel derived fertilizer and increase carbon emmissions from farming.