Cows are sometimes fed human-consumable calories (eg corn).

Other crops that humans can digest can be produced on land currently used for grass.

Other animal species that eat grass require fewer feed cal per calorie produced.

Most pasture is land that cannot support human-edible crops. Cows eat low quality grass that needs no fertilizer or pesticides. Stuff that lives in very alkaline soils, etc. Cows and us, we do not compete for farmland.