After a two-year battle with civil rights and food safety groups, Agriculture Department officials said Thursday that they have dropped a proposal that would have allowed poultry plants to dramatically increase the speed of processing lines as part of a new inspection system.

The regulations originally proposed by the USDA gave plants the ability to accelerate line speeds from 140 birds per minute to 175 birds per minute.

The groups and dozens of members of Congress argued that faster lines would make it impossible for inspectors to spot fecal matter, would exacerbate crippling carpal tunnel among workers and would increase animal abuse. The NAACP and other civil rights groups fought the measure because most of the plant workers are African American or Latino.

The regulation that was finalized Thursday leaves the maximum speed in most plants at 140 birds per minute.

“We listened,” Agriculture Secretary Tom Vilsack said at a news briefing. “No triggers. No tricks. There are no hidden ways that folks can get around this.”

The new rule, however, provides a waiver to 20 plants that are already in a pilot program, letting them operate at 175 birds per minute. Vilsack said their lines now average 131 birds per minute.

The regulation still includes another highly contentious proposal that would allow a dramatic reduction in the number of USDA inspectors at processing plants. The plan is for workers to take on some roles previously filled by federal inspectors. Unions, food safety groups and lawmakers have warned that the change will reduce government oversight and compromise public safety.

Rep. Rosa L. DeLauro (D-Conn.) said that because the regulation substantially changed from the version proposed, the USDA should have reopened it for public comment. She said she remains concerned about the reduction of USDA inspectors, calling it a “recipe for more food-borne illness and more people in the hospital.”

Vilsack defended the plan Thursday, saying that it will increase pathogen testing — to be required in all plants — and that “thousands” of people will avoid illness because of the change.