In a dramatic move to protect America’s cattle industry, Agriculture Secretary Brooke Rollins has warned Mexico that the U.S. will halt imports of live animals — including cattle and bison — if Mexico doesn’t step up efforts to combat a dangerous pest creeping northward. In a letter sent Saturday and obtained by Fox News, Secretary Rollins put the Mexican government on notice to act immediately to fight the spread of the New World screwworm or face serious economic consequences on the border. The USDA has set a firm deadline of April 30 for Mexico to address the growing crisis, or...