Responding to budgetary pressures from Congress, the District of Columbia slashed the number of disability retirements by police and firefighters last year to 44 percent of the total, Mayor Marion Barry told a congressional hearing yesterday.

It was the first time in memory that fewer than half the retirees in a year left on disability. In 1969, disability retirements accounted for 99 percent of the total.

Barry delivered his report on pensions to the House D.C. Appropriations Subcommittee as part of his first appearance presenting a city budget to Congress. The city is seeking $1.4 billion in operating funds for the 1980 fiscal year, which begins next Oct. 1.

The same subcommittee tightened the financial screws last year on the administration of then-mayor Walter E. Washington, cutting $10 million from the pension funds and telling the city to reform the administration of the program.

In 1977, the city had reported that 96 of the 175 retirees left on disability, a total of nearly 55 percent. Early in 1978, the disability retirements of several high-ranking police and fire officials drew attention to the situation, bringing sharp criticism from the public and the press.

Last year, the total number of retirees dropped only slightly, to 168 but those who left on disability declined to 64.

"We made more stringent administrative regulations," D.C. personnel director George R. Harrod told a reporter yesterday, "and we just had to tell the doctors and the [Police and Firemen's Retirement and Relief] board that... we just couldn't be so lax on those things... so the city cannot be ripped off."

Barry asked the lawmakers to restore the money that was eliminated from the budget last year.

"Despite this significant progress, the District has little flexibility in reducing our pension costs," he said. "The number of optional retirements [based upon 20 years of service] is increasing, offsetting gains made from reduced disability retirements. The cost-of-living index to calculate survivors' payments increased more than anticipated...."

Barry's report drew no direct response from the subcommittee. The mayor told the lawmakers that the city hopes for enactment again this year of legislation granting a large, long-term federal subsidy to the pension programs for police, firefighters, city judges and school employes.

A bill that would have granted $1.6 billion over a 25-year period was vetoed last year by President Carter, who said the measure overstated the federal responsibility. His veto message also cited abuses in the disability retirement provisions.

Yesterday's hearing was laden with symbolism both for the mayor and the subcommittee.

It was the first time sine 1967 that Walter Washington was not in the witness chair to present a city budget. And it was the first time since 1962 that Rep. William H. Natcher (D-Ky.) was not presiding as subcommittee chairman.

Barry, starting his third month as mayor, sat across the long, oval table from Rep. Charles Wilson (D-Texas), who succeeded Natcher.

The veteran Kentuckian, who moved to another chairmanship, remains on the D.C. subcommittee, which he first joined in 1955. Yesterday Barry gave him an ornate, handcrafted key to the city. "It is something we do only for people we really love," Barry said, adding with a grin: "It is a key to unlock some of that money."

Barry's testimony, supported by City Council Chairman Arrington L. Dixon, was a broad-brush overview of the budget. Prepared by the former city administration, Barry said "it does not contain all of the priorities I would necessarily choose to be emphasized."

The mayor called on Congress to approve the entire $317 million federal payment proposed by Carter. The city deserves the full sum, he said, and it should not be cut by Congress if local tax collections run higher than expected.

Wilson questioned Barry about the effects of rent control, suggesting that it may be responsible for many apartment owners converting buildings to condominiums and going out of the rental business.

Wilson said the subcommittee, being "a bit insulated" from local policis, "might conduct an in-depth study" of the effects of rent control.

Barry said he would like to speed up the administration of applications by landlords for higher rents or by tenants to hold them down. "I suspect we are going to have some form of (rent contro) for some time," he said, calling it "not the answer" to the city's housing problems.

He said the answer is expansion of the city's housing supply, for which he will soon announce plans.

Answering a question, Barry said the city expects to ask the federal government to reimburse it for about $2 million in the costs of policing and otherwise dealing with the farmers' demonstration on the Mall.