U.S. beef and dairy exports surged 14 percent and 57 percent, respectively, in September compared with a year earlier, extending a year-long foreign demand boom that’s fueled an income upswing for American farmers following a 2009 slump.

Canada, Japan and South Korean were among the biggest buyers of U.S. beef and veal during September, helping lift total exports to 185.6 million pounds up from 162.4 million pounds in September 2009, according to Agriculture Department data released Nov. 12. Shipments of cheese, butterfat and other dairy products totaled 131,395 tons in September, the USDA said.

While beef, pork and dairy exports for the first nine months of 2010 are up compared with 2009 levels, the recent numbers indicate high prices are starting to curb demand, analysts said. September’s beef exports were down from summer highs, while pork exports fell for the third consecutive month after wholesale prices soared to records in August.

“I would list high prices as the number one reason for lower shipments,” said Steve Meyer, a livestock economist who runs Adel, Ia.-based Paragon Economics, Inc. Pork cutout values “were record high in August and close to record high for most of September. Even with the dollar falling, U.S. pork was more expensive for foreign buyers and it appears that they backed off a bit.”

Additionally, shipments to Mexico, the second-biggest foreign customer for U.S. pork next to Japan, were inflated a year ago in the aftermath of the H1N1 virus outbreak, Meyer said.

“Shipments to Mexico were rebounding by September last year and were probably larger than they otherwise would have been as Mexican meat processors tried to backfill for what we think was a significant reduction in Mexico’s domestic herd,” Meyer said.

Pork shipments totaled 322.2 million pounds in September, down 7.8 percent from 349.4 million pounds a year earlier, according to the USDA. For the year through September, pork exports totaled 3.08 billion pounds, up 3.4 percent from the same period in 2009.

Overall, U.S. farmers and livestock producers are still poised for a strong year financially amid high animal and crop prices and climbing exports. Meat consumption is growing as economies in China and other countries continue rapid growth, while drought that slashed Russia’s wheat harvest has led to stronger demand for U.S. grains.

Net farm income for 2010 is expected to increase 24 percent, to $77.1 billion, from recession-weakened levels in 2009, the USDA said in an August forecast. For the year that began Oct. 1, U.S. agricultural exports were expected to rise 5.1 percent to $113 billion, the second-highest total on record, according to the USDA.

For the year through September, U.S. beef exports totaled 1.65 billion pounds, up 16 percent from the same period in 2009, according to the data released Nov. 12. If that pace continues through the rest of the year, exports may top the record 1.996 billion pounds shipped in 2008.

For dairy products, U.S. exports through September were valued at $2.72 billion, up 69 percent from the same period in 2009.