Hog futures fell, heading for the longest decline since October 2011, on signs of weakening overseas demand for U.S. pork. Cattle dropped.

China, the third-biggest buyer of American pork, has asked the U.S. for further documentation that shipments are free of ractopamine, a feed additive used to add lean muscle in livestock, according to the U.S. Meat Export Federation. Russia, the sixth-biggest buyer of U.S. pork and beef in 2012, has banned imports of American meat because the products may contain ractopamine.

“The demand challenge is there in the export market right now,” Lawrence Kane, a market adviser at Stewart-Peterson Group in Yates City, Illinois, said in a telephone interview. “We ship an awful lot of pork. Internationally right now, we have a question on demand.”

Hog futures for April settlement declined 0.8 percent to 82.275 cents a pound at 10:06 a.m. on the Chicago Mercantile Exchange, after touching 81.7 cents, the lowest since Nov. 12. Prices are headed for the seventh straight drop, the longest slump since Oct. 27, 2011.

Cattle futures for April delivery slid 0.1 percent to $1.2805 a pound. The commodity was down 3.1 percent this year through yesterday.

Feeder-cattle futures for March settlement were unchanged at $1.40725 a pound on the CME.

To contact the reporter on this story: Elizabeth Campbell in Chicago at ecampbell14@bloomberg.net

To contact the editor responsible for this story: Steve Stroth at sstroth@bloomberg.net