The U.S. Department of Agriculture will test ground beef for bird flu particles, though officials said Tuesday they’re confident the nation’s meat supply is safe.

Bird flu has been found in nearly three-dozen dairy herds across nine states. The new testing is the latest effort by the USDA to track and understand how the virus is spreading among livestock.

Two studies will test if particles of the bird flu virus, called Type A H5N1, is found in beef for sale in the states where dairy cows have tested positive or in the muscles of dairy cows sent to slaughter. A third will test how cooking meat at different temperatures affects the virus using a bird flu surrogate.

A week ago, the U.S. Food and Drug Administration confirmed it found non-infectious remnants of the bird flu virus in pasteurized milk. The particles are inactive and pose no threat to consumers, experts said.