Presently modem nutrition of high-yielding dairycows requires knowledge needs animals for given to efficiency and resulting corresponding quality and quantity fodder for given to commercial trend and performance animals. Starch is organic nutrient, which of principle in a way works economy milk production (FOX et al. 2009). Continual by increasing the performance milks near dairycows and increase share starch in TMR happens not only to health problems inductive acidosis dairycows, but also to increasing content starch in excrement, which indicates losses received organic nutriments (OBA and ALLEN et al. 2003, REMERD et al. 2004) Starch at different feeds has different quality in light on the part of degradability in rumen (CORREA et al. 2002). Application undegradabilty of starch cut in production TMK in rumen and more starch will add to the illeum, energy metabolism is well -balanced and dairycow can increase production of milk (LOPES et al. 2009). Goal of experiments is evaluation qualities of different types maize grains (resp. starch) and degree mechanical disruption (size at milling 1 mm or 5 mm) depending on his degradability in rumen of dairycows.