According to sources as part of a trade deal

According to sources, China is looking to lift a trade ban on poultry and may buy more pork to meet a growing supply deficit. This is part of a trade deal with the US. However, it is not willing to allow a prohibited growth drug used in roughly half of the US hog herd. The China hog population has been hurt by an African swine fever. According to sources 200 million pigs could be culled or die as a result of the fever (about 30% of the pork output).

You can read more about the ins and outs of the pork and chicken trade issues HERE.