some ruminants are good because they can turn inedible biomass into calories. However the scale at which we farm them is orders of magnitude beyond those levels.
replyI'm fairly sure there weren't 1.5 billion cows in the world before humans.
replyThere were many other large mammals, but we've destroyed a lot of biodiversity already.
replyYes, but there weren't that many large grazing animals because most of the world was covered in woods, not pastures. Trees are the most successful large creatures and we've probably reduced their habitat by 50%.
replyThat's the actual tragedy. Forests contain a lot more like per cubic km than pastures do.