US agriculture officials mandate testing of milk supply for bird flu

USDA will test raw milk in attempt to stop spread of virus as more than 700 dairy herds infected since March

America's national milk supply must be tested for the bird flu virus under a new federal order by the US Department of Agriculture announced on Friday.

The mandate comes at a time when authorities are seeking to grapple with the rapid spread of bird flu, known as H5N1, among dairy herds. Infections have spread to more than 500 dairy herds in California, the top state for dairy production.