China has announced that beginning on March 1, 2013 all U.S. pork products will be tested for ractopamine, a feed additive used to promote lean muscle growth by a third-party testing firm, according to the U.S. Meat Export Federation. The feed additive has been found to be safe and certain levels are deemed acceptable by the United Nations. 

China is the world's biggest producer and consumer of pig meat and the third-largest market for U.S. pork. The announcement is odd considering that no pork products from the US have tested positive for the feed additive, recently. U.S. pork exports to China and Hong Kong, totaled $886 million in 2012. 

Some industry insiders see the move as a way to protect its domestic pig production, and earlier in February, Russia barred any U.S. meat products that contain ractopamine. If China were to ban pork imports from the United States, it would boost pig production in Canada, Brazil and the European Union.