A former aide to Sen. Herman E. Talmadge (D-Ga.) has told investigators that Talmadge maneuvered in 1974 to protect an old friend and campaign contributor from critical questioning by the Senate Watergate Committee.

Two days before the hearing Talmadge's friend, Florida supermarket executive A. D. Davis, and Davis' brother, each gave $3,250 contributions to Talmadge's Senate campaign, according to federal election records.

Daniel Minchew, who was Talmadge's senior aide until 1974, told investigators for the Senate Select Committee on Ethics last week that he arranged to have Talmadge available to chair the Watergate committee when Davis's turn came up to testify before the group.

Minchew has also told committee investigators that Davis made a $1,000 contribution to Talmadge's fellow Georgian Sen. Sam Nunn (D-Ga.) in 1972 through Talmadge's office. No such political contribution is listed by Nunn in his federal election records.

A spokesman for Talmadge yesterday denied there was anything improper in Talmadge's handling of the Watergate questioning of Davis. He also denied any connection between the contributions by the two Davises and Talmadge's chairing of the hearing. The Talmadge spokesman and a spokesman for Nunn denied the existence of the alleged $1,000 contribution. A.D. Davis also denied the allegations.

Both Talmadge and Minchew are under investigation by the Senate committee and federal grand jury here. Each man has accused the other of responsibility for a secret and illegal bank account that was set up here in Talmadge's name and operated by Minchew. Talmadge is also under investigation by the Internal Revenue Service over allegations concerning his financial affairs.

According to a transcript of the Watergate hearing, Talmadge was the only Senate member of the committee present when Davis did testify on April 11, 1974, and chaired the closed session.

Watergate committee investigators sought to question Davis about campaign contributions he made in 1968 to the Nixon campaign allegedly through Nixon's friend, Charles G. (Bebe) Rebozo. According to testimony by the committee's assistant chief counsel, Terry Lenzner, the investigators believed the money ended up in the hands of Watergate operatives Anthony Ulasewicz and John J. Caulfield.

Despite objections from Lenzner and other staff members of the committee, Talmadge ruled that the questions were not allowed under the Senate's mandate and cut off further questions about the contributions. At the end of the session Talmadge complied with a request by Davis and ordered the transcript of the hearing sealed.

A former member of the Watergate committee staff, who was present at the session, said yesterday that committee staffers were dismayed to hear Talmadge after the session making plans to fly back to Georgia on Davis' plane.

Davis, who was vice chairman of the board of the Winn-Dixie supermarket chain at the time of the hearing, was a close friend of Talmadge. The two men ran an annual hunt for senators and others at Davis' D-Dot Ranch in Florida, and Davis helped make Talmadge's family ham business a success by pushing Talmadge hams in his markets.

It was unclear yesterday where the contributions by the two Davis brothers did end up. Federal election records filed by Talmadge say the contributions were earmarked for "public information research" to be conducted by Atlanta political consultant Gerald Rafshoon. Talmadge's spokesman said yesterday his office passed the contributions directly over to Rafshoon who used them to pay for a poll conducted by William Hamilton Associates, a political polling firm here.

Officials of Rafshoon's firm said yesterday they had a notation in their books of the contributions. The money, they said, was paid to the Hamilton firm.

Hamilton said yesterday that he did conduct "a small telephone poll" for Talmadge in 1974. But he said it was "highly unlikely" the poll cost $6,500 and that he did not believe payment for the poll came from either Rafshoon or the Davis checks.

The allegation that Talmadge interfered with Senate Watergate investigations of political contributors to his campaigns is the second of its kind in recent days.

Last week The Atlanta Constitution reported that Talmadge got $10,000 in two political contributions from the dairy industry while he was allegedly pressuring the Watergate investigators to quickly concluded their probe into illegal political payments by dairymen.

Talmadge has publicly denied knowing about the dairy contributions while the Watergate committee was meeting. But sources yesterday confirmed that Talmadge met with the treasurer of a dairy cooperative's political fund and others just a day before the fund made a $5,000 contribution to the Georgian's campaign. Officials of the dairymen's group have said the meeting was to discuss legislation.

A spokesman for Talmadge yesterday denied that Talmadge ever get the contribution. "It sounds like someone trying to mislead the Ethics Committee with a totally fabricated and misleading story about a contribution that simply did not exist," said Gordon Roberts, Talmadge's spokesman.