Correct. The vast majority of US cattle are grain fed/finished.
"If all the grain currently fed to livestock in the United States were consumed directly by people, the number of people who could be fed would be nearly 800 million," David Pimentel, professor of ecology in Cornell University's College of Agriculture and Life Sciences, reported at the July 24-26 meeting of the Canadian Society of Animal Science in Montreal. Or, if those grains were exported, it would boost the U.S. trade balance by $80 billion a year, Pimentel estimated.
With only grass-fed livestock, individual Americans would still get more than the recommended daily allowance (RDA) of meat and dairy protein, according to Pimentel's report, "Livestock Production: Energy Inputs and the Environment."
"If all the grain currently fed to livestock in the United States were consumed directly by people, the number of people who could be fed would be nearly 800 million," David Pimentel, professor of ecology in Cornell University's College of Agriculture and Life Sciences, reported at the July 24-26 meeting of the Canadian Society of Animal Science in Montreal. Or, if those grains were exported, it would boost the U.S. trade balance by $80 billion a year, Pimentel estimated.
With only grass-fed livestock, individual Americans would still get more than the recommended daily allowance (RDA) of meat and dairy protein, according to Pimentel's report, "Livestock Production: Energy Inputs and the Environment."
To add to that, the argument that animal pastures cannot be used for anything else has been proven demonstrably false time and time again. They are not usable for modern day agricultural monoculture cropland, which is the metric that the studies use and I'm sure the commenter is referring to. That does not mean by any stretch of the imagination that they cannot be rewilded or even transformed into usable farm land again through long term soil regeneration methods such as permaculture farming or effective through growing climate appropriate polycultures.
Frankly, yes, they do fix themselves. You'd be utterly shocked at what landscapes look like if we leave them. Having been part of forest regeneration efforts across the UK for the past 8 years - from southern heathlands to rocky Welsh and Scottish outcrops, good for "nothing but sheep" - I can say with all certainty that every part of the country except the most extreme alpine regions is suitable for reforestation or some form of plantation dense rewilding, mooring, wild flower meadow, etcetera. The same can be said of much of Canada and America, with my peers over there having the same results when grazing stops. Hell, the Mongolian steppes are turning to results of goat herding, and the Gobi desert is though to have been cause by the same.
In the UK for example, people are completely ignorant to how the place looked before we levelled it for grazing, viewing the 70% ecologically barren agricultural land (of which 80% of that is used for grazing or agriculture to feed cattle) as the norm and the 2.5% old growth forest as a more novelty, and something strangely "unique to that area". The country was 60-80% temperate rainforest before human habitation, depending on what research you go by.