CHICAGO, Aug 30 (Reuters) - Chicago Mercantile Exchange live cattle futures sagged on Monday as beef prices fell and brokers worried that U.S. demand for steaks and hamburgers will decline after the upcoming Labor Day holiday weekend.

Beef prices have softened after reaching their highest price since May 2020 last week as retailers stocked up for end-of-summer sales. Beef prices normally top out just ahead of Labor Day, which is next Monday.

Choice cuts of boxed beef fell by $2.63 to $342.74 per cwt, while select cuts dropped by $2.39 to $313.13 per cwt, according to the U.S. Department of Agriculture.

"Typically the end of the grilling season is the weekend," said Brian Hoops, president of U.S. broker Midwest Market Solutions. "Then demand starts to soften a little bit."

CME October live cattle ended down 0.800 cent at 128.325 cents per pound. December live cattle slipped 0.650 cent to 134.675 cents per pound.

Feeder cattle futures ended mostly firmer, as grain prices stumbled. October feeders settled up 0.525 cent at 168.950 cents per pound.

In the pork market, CME October hogs ended 0.575 cents lower at 90.150 cents per pound.

U.S. wholesale pork cutout values also stumbled. The USDA reported that pork carcass value fell $6.87 to $109.72 per cwt.

China's state planner said it will continue to buy pork for state reserves to support weak prices in the world's top pork-consuming market.

China has been rebuilding its hog herd after the fatal pig disease African swine fever decimated its hog herd and forced the country to increase imports.

In other livestock news, U.S. chicken producer Sanderson Farms said Hurricane Ida closed plants in Mississippi and Louisiana, though none of its facilities suffered significant structural damage. The company plans to operate during the holiday weekend, including on Monday, to catch up on lost production, according to a statement.

(Reporting by Tom Polansek in Chicago; editing by Richard Pullin)