Sen. Howard W. Cannon (D-Nev.) swore in federal court today he had never been offered a bribe by Teamsters union President Roy Lee Williams and did not know Williams from "a bale of hay" when the alleged offer was made.

A lame duck who was defeated earlier this month in his bid for fifth term, Cannon was the first witness to be called by the defense in the trial of Williams and four other men accused of conspiring to bribe the senator in 1979.

The crucial event in the government's case was a meeting in Cannon's office in Las Vegas on Jan. 10, 1979, when Williams and Chicago insurance executive Allen Dorfman allegedly assured Cannon of a valuable piece of Las Vegas real estate in return for his help in blocking legislation to deregulate the trucking industry.

Cannon denied that any deal was struck or even suggested.

Spending most of the day on the witness stand, the 70-year-old senator said the meeting in his office had been set up earlier on a phone call from Dorfman who told Cannon's secretary that he wanted to discuss some "Nevada Teamsters problems."

Dorfman, a longtime Teamster Union associate, turned up with Williams, then a Teamsters union vice president; Edward Wheeler, a Teamsters union lawyer dispatched from Washington, and William Webbe, who works in Dorfman's insurance offices at the Teamsters Central States Pension Fund building in Chicago.

Up to that point, Cannon, who was then chairman of the Senate Commerce Committee, said he had never met Williams, whose home base was in Kansas City, Mo., and had never heard of him.

"Apparently I was introduced to him Williams by his title, but I didn't know Roy Williams from a bale of hay when he came in," Cannon said under day-long questioning by Williams' chief defense attorney, Thomas Wadden.

FBI tape recordings introduced earlier in the trial have depicted Williams praising Cannon on April 26, 1979, for "what he done with deregulations . . . . He put 'em on the back burner . . . . He got that bill out of Sen. Edward M. Kennedy's hands." They have shown Dorfman recalling on May 21, 1979, that at the meeting in Cannon's office, "Roy Williams just unequivocally came right out and says, 'You got the property, senator. Don't worry about it.' "

The tapes also showed Webbe responding to Dorfman by saying, "I was there . . . . Roy said you take care of your end and we'll take care of our end for you."

Cannon denied that any such conversations took place.

Q. "Did you hear anyone say to you words to the effect, 'Don't worry about the property, senator, it's yours'?"

Cannon: "No sir."

Q. "Did you hear anyone say, 'You take care of your end and we'll take care of ours'?"

A. "No sir."

Q. "Did any one of these men, either singularly or together, offer you a bribe?"

A. "No sir. Not on that date or any other date."

Cannon acknowledged that he did mention to Dorfman at some point, probably as the Teamsters group was either entering or exiting, that he and some Las Vegas neighbors were putting a bid in on a piece of Pension Fund real estate that the homeowners wanted to protect them from high-rise development.

The senator said the homeowners agreed around late December, 1978, at a meeting he attended to try to buy the parcel for $1.3 million. He said they asked him if he knew anyone to whom the bid could be submitted.

"At the time, I knew I had a call pending from Mr. Dorfman concerning Nevada Teamsters matters so I said, 'Yes, I think I do know someone,' " Cannon testified.

Today's session began with U. S. District Court Judge Prentice H. Marshall's denial of a round of defense motions for a directed verdict of not guilty, on grounds that the government had not established its case.

Wadden then delivered an opening statement on Williams' behalf. He said Williams went to the meeting with Cannon only reluctantly, at the request of then Teamsters president Frank Fitzsimmons. According to Wadden, Williams was hesitant because he did not know Cannon and was not familiar with deregulation issues, but Fitzsimmons, now dead, told him, "Dorfman set this up . . . . I want you to go."