From New York Times:

Each year, federal inspectors find illegal levels of antibiotics in hundreds of older dairy cows bound for the slaughterhouse. Concerned that those antibiotics might also be contaminating the milk Americans drink, the Food and Drug Administration intended to begin tests this month on the milk from farms that had repeatedly sold cows tainted by drug residue.

But the testing plan met with fierce protest from the dairy industry, which said that it could force farmers to needlessly dump millions of gallons of milk while they waited for test results. Industry officials and state regulators said the testing program was poorly conceived and could lead to costly recalls that could be avoided with a better plan for testing.

F.D.A and Dairy Industry Spar Over Testing of Milk