>>970241The grass/grain crop is to feed livestock. It doesn't have to be wheat.
Cows are not exactly as easy to raise as you think they are. Unless you have a dozen
acres for grazing land (and no even then in most cases) you will need to supplement their food source.
The same crop can help feed the pigs/goat (better because you can milk and eat them) along with all waist from the garden and orchard.
My source is that I grew up on a 42 acre ranch.