>Another 14% come from grains and other food that could have been eaten by people. But altogether this less than a quarter of the calories livestock consume. A

>Another 14% come from grains and other food that could have been eaten by people. But altogether this less than a quarter of the calories livestock consume. Are you wholly unfamiliar with feedlots? 50% + of the bodyweight of the bulk of cattle in the world comes when they live on a feedlot, where they get 5.5 to 6.5 pounds of feed, via trough, to raise them from 600-900 pounds up to the slaughter weight of 1250-1350 pounds. Corn (dent, which is still usable for human foodstuffs but is mostly just grown for animal feed) is widely used on the feed lot because you don't need 5.5-6.5 pounds per pound of beef, you only need 2.07-2.24 pounds per pound of slaughter weight. Each pound of dent corn yields about 1,566 kcals so you're trading 3241+ kcal of (fertilized) corn crop for 800-1250 kcals of beef. So for 1 acre of corn you need 40 to 50 pounds of nitrogen, 1 acre of corn. For the 2020 crop year, USDA estimates U.S. corn yield to be 181.8 bushels per acre. 1 bushel is 56 pounds. So to finish 1 cow to slaughter weight, assuming it's pasture fed to 600 pounds, you're looking at roughly 2.9 pounds of nitrogen fertilizer. So roughly 2.9 pounds of nitrogen, 1345 pounds of corn, and then factor in the water which is 1-2 gallons per 100 pounds of of bodyweight per day times 12-36 months depending on what fat content is desired in the meat. Again, we can use less fertilizer, reduce water usage, and better use some current cropland (75+ million acres in the United States alone) for crops intended for human consumption, drastically reduce the risk of new diseases by eliminating hundreds of millions of chronically stressed animal hosts, and to simply restore of them to native species in an area and reduce all of the negative environmental impacts of farming in those areas (runoff, soil depletion, loss of native habitats).