Global stocks hit as China cancels U.S. farm visits, yields slip

NEW YORK (Reuters) - An index of global stock markets gave up early gains after Chinese agriculture officials who were to visit U.S. farm states next week cancelled their trip, dampening optimism on U.S.-China trade talks.Revived worries about the state of the ongoing trade tensions between Washington and Beijing drove Treasury yields lower and pushed the U.S. dollar down against the safe-haven Japanese yen.Stocks had started the day stronger as stimulus measures by major central banks eased..