That's not correct. We (in the US anyway) feed a massive quantity of unspent (not brewery mash for example) grains when finishing cattle in feedlots. Corn, bar

That's not correct. We (in the US anyway) feed a massive quantity of unspent (not brewery mash for example) grains when finishing cattle in feedlots. Corn, barley, milo, soybeans etc along with harvested forages like alfalfa and sorghum (which is often fed as silage). People do feed brewery mash and other byproducts but that isn't most of what goes into feedlot rations nationwide.