While the Chinese stock market has recently done poorly, pork demand from China remains strong.

Tyler Fulton of HAMS Marketing Services says because the Chinese market has shrunk their supply, they've been short of pork, needing to import more.

He says the changes in the stock market haven't affected how much pork is eaten in China, but it has affected how much is produced.

"What happened was the Chinese domestic supply actually shrunk significantly in 2014 because prices were so terrible for producers, they shrunk so much that it left them quite short, which led them to have to bring in more pork in order to meet the demand that was still there."

However, Fulton says because the US dollar is strong, Chinese demand has been partly in favor of European suppliers.

Over the past month or so, traders generally thought hog inventories would fall more into line with the USDA's forecast from June, yet populations have stayed strong.

Fulton said the increase comes partly because hog producers were starting to expand operations before PED virus outbreaks last year, and disease losses camouflaged the growth.

"When the disease losses started to trail off and it became apparent that the vaccines were effective, it was only then, I'm really only talking about this summer that it became apparent I think that the US market grew over that time frame even though their numbers had a bit of a delayed effect in showing up to the market."

Weekly US hog slaughter is running 11 per cent higher than last year.