Introduction. Trace elements are elements necessary for the body in negligible amounts, in particular for ruminants from 0.10 to 50.0 mg per kg of dry matter in the diet. All these trace elements are necessary for the biochemical processes of the body, which maintain the normal state of metabolism in the body, contribute to maintaining health and increasing productivity. Ensuring sufficient minerals is a particularly difficult task, since the needs for most minerals are not constant, but depend on physiological factors, including genetics, age, gender, type of production and level of production, and also depends on the composition and quality of the diet. The aim – this article examines the effect of organic forms of mineral additives on metabolism and the degree of digestibility of the dry matter of the feed substrate in the rumen. Material and methods. To implement the tasks set, 4 samples were formed – a control and 3 experimental (I, II, III). All samples were presented with wheat bran, however, before incubation, mineral complexes were introduced into the working tanks where the experimental samples were located: I – Co + Fe; II – Se+Zn; III – Cu. As mineral preparations, the following were used: copper bioplex – 10 mg/kg CB (manufacturer: Alltech, Serbia), zinc bioplex – 140 mg/kg CB (manufacturer: Alltech, 54 Ltd, Ireland); selenium-plex – 0.1 mg/kg CB (manufacturer: Alltech flanders BVBA, Belgium); cobalt chloride – 0.1 mg/kg CB (manufacturer: NPK Ascont+ LLC, Moscow region, Russia); iron chelate – 50 mg/kg SV (manufacturer GLS PHARMACEUTICALS, Moscow, Russia). Studies of the digestibility of the studied feed substrate were carried out by the in vitro method according to a specialized technique. The level of volatile fatty acids (VFA) in the contents of the scar was determined by gas chromatography on a gas chromatograph "Crystallux-4000M", determination of nitrogen forms according to GOST 26180-84. Results. The use of Cu, Co+Fe, Se+Zn contributes to an increase in the digestibility of the CB feed substrate by 1.0–2.4% (p < 0.05), an increase in the concentration of nitrogen in the scar fluid and maintenance of pH at the level of 6.7–6.8. Conclusion. The use of various mineral complexes in the feeding of ruminants contributes to a change in the course of metabolic processes in the rumen.
