The more home grown feeds are used for dairy cows, the greater the risk for mineral and vitamin deficiencies, if it is not supplemented from other sources. Most roughage form sandy and peat soils lack essential elements like copper and selenium. As long as concentrates are incorporated in the diet the requirements are met. When concentrates are replaced by home grown grain or by-products, deficiencies occur. By combining the available feedstuffs in the most efficient way in the diet, an overview will make it clear whether there is an existing problem on the farm