The Washington Dairy Products Commission explained in their article "What Is Milk?," published on their website (accessed Mar. 15, 2007):

“‘Organic milk’ refers to the process by which it was produced, not to the product itself. Organically-produced and conventionally-produced milks are identical in their composition, nutritive characteristics, taste, purity and safety attributes. Organic production methods aim at recycling resources and promoting biodiversity, and these aims are valued by some consumers. However, all milk – regardless of how it was produced – must meet the same strict standards for content, wholesomeness and product safety. Marketing claims that organic milk is different from, and better than, conventionally produced milk have not been scientifically substantiated.”

Mar. 15, 2007