LUBBOCK — The smallest cattle herd since the 1950s likely will mean higher beef prices at the supermarket for the next two years.

Experts said beef prices could climb as much as 10 percent a year in 2012 and 2013, and the increase could be even greater if demand from other countries increases.

Those higher prices would follow steady increases that have seen the average retail cost of a pound of hamburger rise 23 percent, from $2.38 in December 2010 to $2.92 last December, according to the U.S. Department of Agriculture.

Last month the USDA reported the U.S. herd had declined to 90.8 million cattle, 2 percent less than the previous year and the lowest inventory since 1952, when there were 88.1 million.

“We’re producing less beef so prices are going to go up,” Texas AgriLife Extension Service livestock economist David Anderson said.

Ranchers have sold more of their cattle in recent years to meet increased costs for feed, fuel and other expenses. The soaring feed costs come amid heightened demand for corn to produce ethanol and to meet a growing export market.

The situation has been worst in Texas, the nation’s leading cattle producer, and other parts of the southern plains and southwest, where a record drought caused pastures to wither, leaving ranchers with few options but to sell their cattle or pay top-dollar for feed.

There are 1.4 million fewer cattle — a record 660,000 of those cows — in Texas this year compared with the previous year, accounting for about 74 percent of the drop in numbers nationally. The animals were either moved to another state or were slaughtered.