DES MOINES, Iowa (AP) — Federal government regulators proposed changes Friday in the way most hogs slaughtered for meat in the United States are processed in a series of new rules that officials say improve industry practices but critics say could imperil food safety.

The new rules would allow hog slaughter plants to voluntarily join a new proposed inspection system that would put plant employees in charge of determining which animals are unfit for processing. Government inspectors who currently perform this function would be moved to other areas of the plant focused more on food safety, said...