Feed conversion for beef is around 6:1, so you have 6 pounds of plants for every pound of beef. Lots of those plants are grass and other stuff humans don't really want to feed on though. Still, the large number of calories cattle need to make gains leave some room to adjust the crop mix.
Of course grazing animal migration patterns and grassland effects (desertification/deforestation) not withstanding. I would love to see an increase in variety and number of grassland mammals in general in order to preserve/expand grasslands.
