Then can human process grass?

Most cows don't eat grass like a wandering herd. Most cows eat stuff we grow on farms that could grow stuff we can eat instead.

https://www.ers.usda.gov/amber-waves/2024/december/ers-data-...

and

https://www.ers.usda.gov/topics/crops/corn-and-other-feed-gr...

Let me surface a more direct article: https://insideanimalag.org/land-use-for-animal-ag/#:~:text=1...

Of the total land area of the contiguous 48 states, ~45% is used for animal ag. This includes: Land for grazing livestock at ~35%. Land for crops going specifically to animal feed at ~9%. Animal ag farmsteads at <1%.[1-3]

The first link you posted says that 29% of the land is used for pasture and 15% is used for crops (which will include both human and animal).

So yes, most cows are eating grass like a wandering herd.

The data doesn't prove either point. For all we know, a very low number of cattle are being grazed on those 29%. Or a lot of them. We don't know.

That doesn't follow. The chart is counting the number of acres of land which are used for specific purposes, not the number of cattle being raised on that land. And the category you're counting as "pasture" encompasses rangeland as well, which is used at an extremely low density (often as low as 1 head of cattle per 10 acres).

> Most cows don't eat grass like a wandering herd. Most cows eat stuff we grow on farms that could grow stuff we can eat instead.

Most cows do eat grass and other stuff we can't eat.

"Hard feed" is made from crops grown as part of a rotation cycle, or from things like soya where 80% of it is only suitable for cattle feed.

Cattle feed is more than grass

depends on the phase of development. Most beef is pasture fed for a significant period, maybe supplemented with extra feed in the winter, but still grass, etc. It's only near the relatively short end they are consolidated & finished at the feed lot.

> Most beef is pasture fed for a significant period

Citations please.

When i looked into internet [1] it says "approximately 95% of the cattle in the United States continue to be finished, or fattened, on grain"

[1] https://extension.psu.edu/grass-fed-beef-production

Correct, but many lands like parts of Alberta and Texas are not very good for growing foods humans can eat. So you may as well get marginal additional calories out of the non-productive land via cellulose digesters.