CHICAGO, May 31 (Reuters) - Chicago Mercantile Exchange (CME) cattle futures turned lower for a third session on Friday, as technical trading at one point sent the most-active August live cattle contract dipping to a two-week low.

Growing concern over future beef demand weighed on prices, analysts said.

The slump in prices also reflected some shifts by hedge funds - which have been long in the cattle market - to book profits at month's end and adjust their positions going into the summer months, traders said.

Live cattle weights also have pressured futures in recent weeks, as slaughter-ready animals have been tipping the scales at 40 pounds heavier or more compared to last year, said independent livestock trader Dan Norcini.

And as boxed beef cutout prices turned lower Friday afternoon, market participants are wondering about what the summer demand for U.S. beef will look like, Norcini said.

The choice boxed beef cutout value eased down 84-cents to $313.20 per hundredweight (cwt), the U.S. Department of Agriculture reported. Select cuts also dropped 81-cents to $301.71 per cwt.

"The question everyone is asking is, have prices peaked?" Norcini said.

Meanwhile, lean hogs turned higher as a jump in weekly U.S. pork exports gave futures a bullish boost at the end of the week, traders said.

"There's been talk in the market that the hogs were oversold, that the funds pressed the prices of hog futures down too hard, as we've some stability lately in the pork cutout prices," Norcini said.

Most-active CME July hog futures ended up 0.175 cent at 97.125 cents per pound.

CME August live cattle closed 1.325 cents lower at 178.450 cents per pound, while June live cattle settled down 1 cent at 181.550 cents per pound.

CME August feeder cattle settled down 2.675 cents at 256.400 cents per pound. (Reporting by P.J. Huffstutter; Editing by Alan Barona)