CHICAGO, Sept 23 (Reuters) - Chicago Mercantile Exchange (CME) lean hog futures firmed on Thursday, after China lowered its sow herd targets in an effort to ensure supply and stabilize prices.

China's Ministry of Agriculture and Rural Affairs said the target for its sow herd was now around 41 million head for 2021-2025 and should be no lower than 37 million head.

"China is encouraging its producers to restrict their sow herd numbers," said Rich Nelson, chief strategist at Allendale Inc. "That is certainly supportive of deferred contracts."

October lean hogs firmed 0.900 cent to 84.750 cents per pound, while the December contract added 3.125 cents to 76.500 cents per pound.

Pork export sales firmed, with 32,600 tonnes sold for the week ended September 16, up 29% from the week prior and 12% higher than the previous four-week average.

Cash pork softened, with the CME's lean hog index, a two-day weighted average of cash prices slipping 91 cents to $92.65 per cwt.

CME's live cattle was mixed-to-lower ahead of the U.S. Department of Agriculture's monthly cattle on feed report, due Friday afternoon, pressured as market-ready cattle add weight on slaughter delays.

"We've had a few plants off and on over the past two to three weeks, due to labor problems or mechanical issues," Nelson said.

For the week, packers have slaughtered 477,000 head of cattle, down 1.24% from a year ago.

Friday's monthly cattle-on-feed report is expected to show tighter on-feed supplies from a year ago, translating to diminished market-ready cattle in the first part of 2022.

"These placement numbers impact February through June processing numbers," said Nelson. "Q1 is going to be a tight supply picture."

Supplies should improve heading into the summer, he added.

Wholesale beef prices dipped, with choice cuts falling $2.23 to 305.60 per cwt. and select cuts eased 51 cents to $274.99 per cwt. according to the USDA.

CME October live cattle futures ended 0.050 cent lower at 123.225 cents per lb, while December futures rose 0.075 cent to 128.625 cents per lb.

Feeder cattle futures eased, with benchmark November feeders falling 0.125 cent to 158.100 cents per lb. (Reporting by Christopher Walljasper; Editing by Anil D'Silva)