newhere. yes, the milk has a hechsher, but as charliehall pointed out it covers vitamins and other supplements they put into the milk, not the milk itself. they are relying on the governmental controls that all milk being sold as cows milk is in fact cows milk.
not sure when the ou published this
http://www.oukosher.org/index.php/common/article/cholov_stam_an_update_from_the_farm_and_lab/