Fodder grain plays a priority role in ensuring high productivity of farm animals and poultry, revealing their genetic potential. Therefore, it is necessary to use the most advanced methods of grain preservation for the most complete preservation of the original feeding power. Such methods in recent years include the technology of sealed storage of raw fodder grain harvested before the complete maturation phase. Various biological and chemical additives are used to improve the preservation results. The use of such additives (due to the specific features of preserved raw materials) is obligatory. The authors conducted comparative tests of certain types of additives for processing raw fodder grains in the whole and flattened forms to determine the effect of different degree of compaction on the effectiveness of their preserving action. They made an experiment, and the quality of fermentation was determined using generally accepted methods. The raw grain isolated from air access is protected from spoilage due to acidification, so the effectiveness of using preservative additives was primarily determined by the effect on this indicator. The whole grain was put into storage with a higher moisture content (35%) than the flattened one (about 25%), which ensured its significantly better acidification regardless of the degree of compaction. A denser grain storage pattern provided better grain acidification regardless of grain moisture. From tested preparations, the flattened grain was better acidified by powdered sulphur at the medium degree of compaction for storage; the whole grain was better acidified by Biosil NN at the maximum degree of compaction. On average the preparations used in the experiment were arranged in the following sequence (as their influence on the degree of grain acidification weakened): powdered sulphur → biopreparations Biosil NN → chemical preservative Promir.