Due to the current legal situation and the problems in availability of organic concentrates, organic dairy cows need for concentrates and the animals nutrient supply was investigated. Rations were calculated for 5 different performance levels (5,000 to 9,000 kg lactation performance) using the program “Super-Ration”. The 3 forage ration types forage high quality, forage low quality and forage + maize silage differed in quality and composition. Energy was supplemented through a mixture of grains and a mixture of five protein sources (field beans, peas, pumpkin seed cake, sunflower cake and dried brewers grains). The results of the model calculations showed that a supplementation of energy-rich concentrates was already necessary at a lactation performance of 5,000 kg, while protein-rich concentrates weren`t required until production levels reached 6,000 (forage low quality), 6,500 (forage + maize silage) and 7,000 (forage high quality) kg of milk. The ration forage + maize silage required the smallest total amount of concentrates, but the highest level of protein-rich concentrates. With regard to the type of protein-rich concentrate, the intake of pumpkin seed cake was the lowest. When taking mobilisation of body reserves into account, performances of 6,500 (forage low quality) and 8,500 kg milk (forage high quality and forage + maize silage) could be reached. The model calculations showed that the nutrient deficiencies at a lactation performance of 9,000 kg were too serious to be reduced to a normal physiological level by feeding these rations, taking into account the restrictions on feeding concentrates. In practice, such top performances can only be achieved with best forage quality, optimal feeding management, high mobilisation of body reserves and consequently a proper genetic makeup of the animals.