Federal food safety inspectors have begun testing ground beef from grocery stores for the presence of bird flu in states where dairy cows have tested positive for the virus, according to the U.S. Department of Agriculture (USDA).

A USDA spokesperson told The Epoch Times in an emailed statement that the agency's Food Safety and Inspection Service (FSIS) is carrying out three separate beef safety studies, including one that involves sampling ground beef from grocery stores in the nine states where dairy cattle have tested positive for the H5N1 bird flu.

"Samples are being collected at retail outlets in the states in which dairy cow herds have tested positive for H5N1 influenza virus," the spokesperson said, adding that the ground beef samples will be analyzed using polymerase chain reaction (PCR), which can detect whether any viral particles are present.

The second study involves testing beef muscle from dairy cows that were condemned at selected slaughterhouses for the presence of bird flu.

"For the second sampling effort, FSIS is currently collecting muscle samples at FSIS-inspected slaughter facilities of cull dairy cattle that have been condemned for systemic pathologies," the spokesperson clarified.

The third study is a ground beef cooking study, which involves using a "virus surrogate" in ground beef and cooking it at different temperatures to "determine log-reduction" of the H5N1 virus, the spokesperson said.

Earlier, the U.S. Food and Drug Administration said that the application of heat in a process known as pasteurization killed the bird flu virus in milk. That came after regulators found that roughly 20 percent of retail milk samples tested positive for bird flu.

So far, no beef cattle have tested positive for the H5N1 virus. Last week, the USDA said it found bird flu in a lung tissue sample from an asymptomatic dairy cow that was sent to slaughter from an infected herd. The agency said that the animal did not enter the food supply.