The U.S. Department of Agriculture has initiated mandatory testing of the national milk supply due to concerns over bird flu, which has affected over 710 dairy herds in 15 states since March. Testing will occur at dairy farms and during milk transportation or processing, with private labs required to report any positive cases. The program starts in six states, including California and Pennsylvania, aiming to detect the disease, monitor trends, and assist states in managing affected herds to control the virus's spread. California health officials have already recalled products from Raw Farm due to potential contamination. While infected milk poses risks, pasteurized milk remains safe. This order follows an April mandate for testing lactating dairy cows before interstate transport.