Aim of this study is to evaluate the structure of the correct selection of feed used to feed dairy cows, by analyzing the composition of cow milk - protein and fat, in particular, the level of urea in milk. It was evaluated the organic dairy farm, implementing the biodynamic milk production technology. The investigation is used for evaluating farm feeding system; grazing - during the summer and feeding cows in barns - during the winter. Studies include identification and evaluation of the efficiency of milk production and milk composition. The milk composition is a basis to evaluate a proper feeding of the cows. The research focused on the period of three years: 2007-2009. Variation of the average monthly level of urea in milk of cow herds is ranging from 70 to 413 mg l-1 of milk.