CHICAGO, Dec 13 (Reuters) - Chicago Mercantile Exchange lean hog futures extended a slump, as live cattle futures came under renewed pressure with broad selling hitting agricultural markets on Wednesday.

Livestock markets settled lower with grain and soy futures, as volatility persisted.

"Everything was feeling a little bit more pressure in the ag sphere," said Austin Schroeder, commodity analyst at Brugler Marketing & Management.

CME February lean hog futures closed down 1.525 cents at 66.725 cents per pound and touched their lowest price since setting a contract low of 65.8 cents on Nov. 28.

The contract has dropped 24% so far this year as large U.S. hog supplies, weak cash prices and lackluster demand for pork have loomed over the market.

"I think we're still trying to hunt for a bottom," Schroeder said. "We just haven't found it yet."

Hog slaughtering improved after dropping below last week's levels on Monday and Tuesday. Meatpackers processed an estimated 489,000 hogs on Wednesday, up from 487,000 hogs a week earlier, the U.S. Department of Agriculture said.

The USDA said separately that average hog weights in the week ended Dec. 9 were steady from a week earlier at 290.6 pounds, but up from 285.5 pounds a year ago.

Cattle slaughtering also exceeded last week's levels, with packers processing an estimated 127,000 head compared to 125,000 cattle a week earlier.

CME February live cattle finished 1.375 cents weaker at 167.225 cents per pound. January feed cattle reached the highest level since Dec. 1, before ending down 1.875 cents at 217.375 cents per pound.

Technical selling weighed on futures as cash markets remained mostly quiet, traders said.

Live cattle last week set a 14-month low after soaring earlier this year as U.S. producers slashed herds in the face of a drought that reduced the availability of land for grazing.

The USDA priced choice cuts of boxed beef at $291.64 per hundredweight, down $1.14 from Tuesday. Prices had jumped on Monday and Tuesday after reaching an April low last Friday.

(Reporting by Tom Polansek in Chicago; Editing by Shinjini Ganguli)