WASHINGTON — The Agriculture Department released long-awaited poultry-inspection rules on Thursday that will give plant operators the option of conducting their own inspections for bird defects and feces on the processing lines and allow government inspectors to concentrate on other food-safety issues in the plant.

Agriculture Secretary Tom Vilsack said the new rules were the most significant change in food-safety inspections in nearly 60 years. They “will increase the chances of us detecting problems by placing the burden of finding contaminates such as salmonella on the plants,” he said.

The Agriculture Department has run a pilot program since 1998 testing a system that gives plants the responsibility of inspecting the birds. Under existing procedures, inspectors from the department’s Food Safety and Inspection Service are stationed along poultry plant assembly lines to examine the birds for blemishes, feces or visible defects before they are processed. Not all plants may choose to inspect themselves under the new rules, in which case a government inspector would remain on the processing line.

The department also announced that it would limit speeds on poultry plant lines to 140 birds per minute to protect workers from repetitive-stress injuries like carpal tunnel syndrome. The current average is about 130 birds a minute, officials said, but food-safety groups were worried because earlier proposals indicated the limit would be significantly raised.