Los Angeles ? The U.S. Department of Agriculture on Sunday ordered the recall of 143 million pounds of frozen beef from a California slaughterhouse, the subject of an animal-abuse investigation, that provided meat to school lunch programs.

Officials said it was the largest beef recall in the United States, surpassing a 1999 ban of 35 million pounds of ready-to-eat meats. No illnesses have been linked to the newly recalled meat, and officials said the health threat was likely small.

The recall will affect beef products dating to Feb. 1, 2006, that came from Chino-based Westland/Hallmark Meat Co., the federal agency said.

Secretary of Agriculture Ed Schafer said his department has evidence that Westland did not routinely contact its veterinarian when cattle became non-ambulatory after passing inspection, violating health regulations.

“Because the cattle did not receive complete and proper inspection, Food Safety and Inspection Service has determined them to be unfit for human food and the company is conducting a recall,” Schafer said in a statement.

A phone message left for Westland president Steve Mendell was not immediately returned.

Federal officials suspended operations at Westland/Hallmark after an undercover Humane Society video surfaced showing crippled and sick animals being shoved with forklifts.

Two former employees were charged Friday. Five felony counts of animal cruelty and three misdemeanors were filed against a pen manager. Three misdemeanor counts – illegal movement of a nonambulatory animal – were filed against an employee who worked under that manager. Both were fired.

No charges have been filed against Westland, but an investigation by federal authorities continues.

Officials estimate that about 37 million pounds of the recalled beef went to school programs, but they believe most of the meat probably has already been eaten.

“We don’t know how much product is out there right now. We don’t think there is a health hazard, but we do have to take this action,” said Dr. Dick Raymond, USDA Undersecretary for Food Safety.

Most of the beef was sent to distribution centers in bulk packages. The USDA said it will work with distributors to determine how much meat remains.

Federal regulations call for keeping downed cattle out of the food supply. They may pose a higher risk of contamination from E. coli, salmonella or mad cow disease because they typically wallow in feces and their immune systems are often weak.

About 150 school districts around the nation have stopped using ground beef from Hallmark Meat Packing Co., which is associated with Westland. Two fast-food chains, Jack-In-the-Box and In-N-Out, said they would not use beef from Westland/Hallmark. Other chains such as McDonald’s and Burger King said they do not buy beef from Westland.