By Julie Ingwersen

CHICAGO, July 17 (Reuters) - Front-month live cattle futures on the Chicago Mercantile Exchange (CME) declined on Friday for a 15th straight session, pressured by a steep slide in cash cattle markets this month and a summertime lull in beef demand, analysts said.

"We are in that seasonal time-frame where in the heat, usually, our demand softens," said Don Roose, president of Iowa-based U.S. Commodities.

In addition, speculators appeared to be unwinding inter-market spreads by selling cattle futures and buying hogs, Roose said. Managed commodity funds hold a sizable net long position in CME cattle futures, leaving the market vulnerable to periods of long liquidation. Funds hold a net short in hog futures.

CME August live cattle LCQ26 futures settled down 2.650 cents on Friday at 224.425 cents per pound after dipping to 224.200 cents, the contract's lowest since March 9. October futures LCV26 ended down 2.575 cents at 220.700 cents a pound.

CME August feeder cattle futures FCQ26 fell 0.650 cent to finish at 345.950 cents per pound.

Slaughter-ready cattle traded in the southern Plains this week as low as $235 per hundredweight, down $13 from last week, and down about $20 from two weeks ago, traders said.

Meat packers appear to have regained leverage as they buy cattle to process into beef, while cattle feeders have been more eager to sell heavyweight cattle.

Wholesale beef prices continued to retreat. The USDA priced choice cuts of beef on Friday afternoon at $366.81 per cwt, down $1.57 from Thursday and the lowest reading since February 20.

Retailers will eventually start buying meat for school lunch programs and stocking up for the September 7 Labor Day holiday, Roose and other analysts said, but that activity is still a few weeks away.

Hog futures advanced, gaining against cattle on inter-market spreads and rising cash hog prices. Sizzling temperatures this week in the Midwest and Plains were curbing hog weights, Roose said, a supportive factor for futures.

CME August lean hog futures LHQ26 settled up 1.375 cents at 101.650 cents per pound after reaching 102.025 cents, the contract's highest since May 20. October hogs LHV26 ended up 1.025 cents at 87.950 cents per pound.

The CME's Lean Hog Index .IHX, a two-day weighted average of cash hog prices, was last quoted at 95.10 cents, its highest value since October.

The USDA priced the pork carcass cutout late on Friday at $104.41 per cwt, up $1.99 from Thursday.