A new federal rule proposed Monday would require extensive salmonella testing in raw poultry in an effort to keep the foodborne pathogen from reaching grocery stores and reduce illnesses. The rule, three years in the making, could cost turkey growers and processors in Minnesota, which produces more turkeys than any other state. “The potential impact on Minnesota’s turkey industry is to be determined, but any time you add additional requirements that could add to supply chain delays, there’s always an added cost,” said Ashley Kohls, executive director of the Minnesota Turkey Growers Association.