Striking Teamsters and the trucking industry returned to the bargaining table yesterday as the auto industry, crippled by parts shortages, laid off thousands more workers and planned new production cutbacks.

The talks, called by federal mediators, were the first since negotiations for a new three-year master freight contract collapsed when the old pact expired Saturday night - triggering selective strikes by the union and a retaliatory lockout by the industry.

The two sides recessed after about five hours of talks and were planning to resume this morning. "It's tough. Once they're out on strike, it's tough," said chief federal mediator Wayne L. Horvitz. Sources close to the talks said before they began that a settlement before next week was considered unlikely.

Aside from the hard-hit auto industry, where more than 140,000 workers, nearly one in five, were laid off or put on short shift as of yesterday, critical shortages are not expected before a week or more, according to government officials.But the government is reportedly ready to seek an injunction to end the shutdown when such shortages develop.

The shutdown covers about 500 of the nation's largest firms and their 235,000 Teamster employes who normally carry a big share of the nation's general freight. Because the only previous interstate shutdown lasted three days in 1976, this is the longest and biggest trucking interruption in history.

The key point of dispute when the talks broke off was a union demand for semiannual, rather than annual, payment of cost-of-living increases. Teamster President Frank Fitzsimmons told reporters Wednesday he is "not ready to change" the demand. The industry was also reportedly "holding firm," according to one source.

Government officials, who view the Teamster negotiations as a critical test of the Carter administration's voluntary anti-inflation program, contend that the Teamster proposal would breach the guidelines.

They say the industry's final offer was within the guidelines of 7 percent a year for wage and benefit increases, although the industry calculates the total cost at more than 30 percent over three years, including costs exempted from the guidelines and assuming an 8.5 percent inflation rate.

Although the guidelines have been relaxed to accommodate the Teamsters, trucking executives fear the Interstate Commerce Commission will not allow rate increases pegged to any costs in excess of the guidelines. Unionized firms also fear high rates will make it harder to compete with non-Teamster operators.

As General Motors and the Fort Motoc Co. continued production and workforce cutbacks, Chrysler, the third largest automaker, said it will stop "virtually all" of its operations on Monday. Chrysler has 41 plants with 85,000 workers in six states. GM and Ford officials said they anticipate further cutbacks, rather than shutdowns, next week.