Undated (AP) _ With a congressional investigation of the cattle futures industry in the works, the Chicago Mercantile Exchange has released a study it hopes will shield it from a dispute over the effects of futures trading on cash cattle prices.

The Merc, where livestock and meat futures are traded on live and feeder cattle, live hogs and pork bellies, absolves itself from having had any part in driving cattle prices to their lowest inflation-adjusted level in three decades.

Complaints from the cattle industry intensified this past spring when prices collapsed following the government's announcement of its whole-herd dairy buyout program aimed at reducing milk production.

The program, and the slaughter schedule for cattle, dumped a huge amount of beef on the market and cattle prices plunged sharply.

Don Butler, president of the National Cattlemen's Association, said at the time that the buyout program had a ''devastating paychological impact'' on the market and cost the beef industry millions of dollars.

With prices collapsing, suspicions resurfaced that the futures market exaggerates price swings and provides an avenue for price manipulation.

In June, the National Cattlemen's Association asked Congress to investigate the cattle futures markets to determine whether they met an economic need and whether there was existing or potential cash market manipulation through futures trading.

The House Agriculture Committee has begun such an investigation. And this past week, leaders of the Senate Agriculture Committee asked the General Accounting Office to investigate the effect of cattle futures on cash cattle prices.

The Merc, in its own study, said cattle prices are low now mainly because of changing attitudes toward beef and ''cutthroat competition'' from chicken growers.

''There is no statistical evidence that the futures market depresses cash prices,'' the Merc concluded in its analysis.

Richard Farr, chairman of the cattlemen's group futures subcommittee, said the Merc's study provided some useful data ''but some of the conclusions we may or may not agree with.''

His group had studied the document only briefly, Farr said, and agreed the study would help dispel some of the concerns among cattlemen. Nonetheless, he said, a congressional investigation still was needed.

According to the Merc's analysis, the volatility of the cash cattle market became more subdued after the inception of cattle futures.

The annual variability in the percent change in weekly steer prices averaged 2.87 percent during the 11 years before futures and 2.39 percent after cattle futures trading started 22 years ago, the study said.

Also, the Merc said, ''there is no evidence that the futures market made the cash market reaction to the dairy buyout announcement any more volatile that it otherwise would have been.''

As to allegations that speculators can muscle the market, the Merc said a recent analysis by the Commodity Futures Trading Commission found large speculators holding only 5 to 6 percent of the buy side or the sell side of the market.