Three moos for the U.S. Department of Agriculture, which is aiming to close a loophole in organic standards for livestock. Under the proposed rule, organic cows must be let out to graze in a pasture at least 120 days per year, and must get 30 percent of their feed from such grazing. The old rules merely said cows must have “access to pasture” — which, undefined, allowed some “organic” operators to cut corners.