The first shipment of British feed wheat to the United States in 2-1/2 years was purchased by hog producer Murphy Brown, a subsidiary of Smithfield Foods, possibly as part of an effort to produce a specific grade of meat, an official at Prestage Farms Inc, a partner of Murphy Brown, said.

"There is some wheat coming in, feed wheat for hog feed, but we are not participating. That is Murphy Brown," John Prestage, senior vice president of Prestage Farms, told Reuters.

Prestage Farms is a partner with Murphy Brown and Nash Johnson & Sons Farms in Wilmington Bulk Ltd, a U.S. feed-buying consortium.

Wilmington Bulk is listed as the operator of a handy-sized vessel, the Nin, that is scheduled to arrive in Wilmington, North Carolina, on Nov. 12, carrying wheat, the port's website said. The ship left the British port of Harwich on Tuesday, Reuters shipping data showed.

The Nin's cargo, around 25,000 tonnes of British feed wheat, marks Britain's return to being a net exporter after a two-season hiatus.

"To my knowledge, nobody is feeding it to their hogs but Murphy Brown," Prestage said. "We don't intend to participate in the near future, with the current price premium they are paying for this wheat," he added.

"They are doing it for other reasons, for meat quality for certain customers," Prestage said.

Hog producers in the U.S. Southeast sometimes add wheat to their feed rations, cash grain traders said. Slow U.S. rail service and a shortage of locally available feed-grade wheat may have made the British wheat attractive, the traders said. (Reporting by Julie Ingwersen; Editing by Peter Galloway)