The problem of mineral elements distribution in grain raw material with high fiber content was investigated. Deep pro- cessing of grain, in the first place, assumes fine grinding of grain substrate. In the experiment wheat, barley, oats and grain wastes were milled in a mill and divided into 200-400- 600-800 μm and over 800 μm fineness fractions. Fine fod- der, called "activated", was used: AHF - activated highly en- zymatic grain wastes fodder; AHB - activated highly enzymat- ic barley fodder; AHBF - activated highly enzymatic bran fodder and AHO - activated highly enzymatic oats fodder. The content of the following macroelements was determined in obtained fractions: calcium, phosphorus, magnesium and iron. It was established that, depending on the size of feed particles, the content of the macroelements in them was dif- ferent. The distribution of calcium, phosphorus, magnesium and iron in the fractions of wheat, oats and barley obeys the following regulation: being at the minimum in fine fraction, their content increased with increasing particle size in the range from 400 to 800 microns. The exception was the waste of grain, where the maximum content of calcium and iron was noted in fine fraction, with further decrease in the fractions of 400-800 microns, which was probably due to the multicom- ponent composition of grain matter. The maximum content of calcium was found in fine fraction of grain wastes equal to 1810 micrograms per gram and in the fraction 401-600 mi- crons of oats - 1320 micrograms per gram. In all types of raw materials, the content of phosphorus increased with increas- ing particle size. The best ratio of calcium and phosphorus was 1: 1.9; 1-2.1 noted for the waste in the fractions of 200and 400 microns.