While that first sentence is unnecessarily aggressive, the point of your post is correct for non-industrial scale farming, at least in my experience in the US.

In 'standard' farming practice, a vast majority of the feed for cattle is grass, hay, or other sorts of grass things. The last month or so before slaughter they are fed heavy grain to bulk up a little and be more marketable. (source; my farm).

In Industrial scale farming (which one could argue is the actual standard now because people demand cheap meat), cattle are kept in feed lots for their lives and pushed heavy grain.

Pigs don't eat grass. Chickens don't eat grass.