The first case of bird flu in a cow has been reported in California, the largest dairy producing state in the United States

poultry flu has spread to the nation’s largest milk-producing state, posing a challenge for government officials who are facing resistance from farmers to expand testing efforts to contain the outbreak. California, which accounts for one-fifth of the U.S. milk supply, has reported cases of the virus at eight dairy farms in the past two weeks, according to the California Department of Food and Agriculture. All affected dairy farms have been quarantined and biosecurity measures have been stepped up to prevent the spread of the virus.