Cows and other farm animals need a lot of food:
More than three-quarters of global agricultural land is used for livestock, despite meat and dairy making up a much smaller share of the world's protein and calories. [...] However, only half of the world’s croplands are used to grow crops that are consumed by humans directly. We use a lot of land to grow crops for biofuels and other industrial products, and an even bigger share is used to feed livestock.
That wasn't me, but I found out about it relatively recently and I'm happy to share it.