Photo taken on July 27, 2018 shows the office of U.S. National Pork Board in Des Moines of Iowa state, the United States. U.S. pig farmers are feeling the pinch after the trade disputes initiated by the United States and they are worried about losing their markets, one of the heads of the U.S. National Pork Board told Xinhua in a recent interview. (Xinhua/Wang Ping)