All milk in the United States has been fortified with added vitamins A and D for many years. Fortification with vitamin D has been one of the most worthwhile benefits to promote human well-being. Whole milk has 3.2% milk fat, and two percent has 2% milk fat; both have been fortified with vitamins A and D. The fat in milk and dairy products is synthesized by the cow. Milk fat contains no added lard or other supplemental fat sources.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
