WRAPUP 2-Russia set to halt imports of U.S. beef, pork

* Russia requires testing for ractopamine * USMEF says pork, beef exports to Russia could stop * USDA asks Russia to suspend requirement * Russia move comes after US Senate passes trade bill * Cattle, hog futures down By Theopolis Waters and K.T. Arasu CHICAGO, Dec 7 (Reuters) - U.S. pork and beef exports to Russia could halt on Saturday following Moscow's requirement that the meat be tested and certified free of the feed additive ractopamine, a move analysts said smack