No sugar is added to milk, unless some other flavoring (e.g., chocolate) is being added. The milk sugar, lactose, is put there by the cow.
I would not drink raw milk under any conditions. No matter how clean the dairy (and no dairy is ever spotless), cows are prone to any number of illnesses—including rabies—which can end up in the milk.
If no sugar is added why does low fat and 2% have more sugar? I remember Atkins saying they add the sugar to give it some taste once the fat is removed.