The dairy industry is searching for add-values in milk that will promote the sale of milk. Several minerals and vitamins are important in this aspect. One easy way of improving milk quality is to change dairy cow diet. The concentration of selenium and iodine is greatly influenced by dairy cow diet. Both vitamin A and E concentrations in milk can be altered by dairy cow diet. Preferable diets are pasture and/or high-quality forage. Most important for rumen synthesis of vitamins of the B-complex are a well-functioning rumen, which means feed consisting of high quality forage.