U.S. pork inventories rose 31 percent at the end of August, to a record 580.8 million pounds, as farmers culled their herds due to high feed costs, according to the U.S. Department of Agriculture. The number is up significantly from the 442.9 million pounds stored at the same time in 2011, and up 5.7 percent from the end of July.

“There’s no doubt the high grain prices did cause higher liquidation,” said Don Roose, the president of U.S. Commodities Inc. “We’ve had bigger supplies, and consumption in general was down a little bit.” U.S. commercial pork output in the first eight months of 2012 totaled 15.1 billion pounds, up 3.3 percent from the same period in 2011, according to the USDA. Pork production in August rose to 2 billion pounds, up 16 percent from July and 5.6 percent higher than August 2011.

Hog futures for December rose 0.7 percent to 74.7 cents a pound at 10:40 a.m. September 21 on the Chicago Mercantile Exchange. Prices were down 12 percent through September 20. Wholesale pork prices dropped 11 percent in August, the biggest monthly slide since October 2010.