The article presents the results of a comprehensive study of the effect of humic substances added to the diet of dairy cows on productivity, the chemical composition of milk and key parameters of rumen digestion. It was found that the 84-day use of humic acids in the diet of cows in the experimental group led to a significant increase in milk yield by 4.5 liters (p<0.05), which is a 1.2-fold increase> <0.05), which is a 1.2-fold increase compared to the beginning of the experiment. In addition to the increase in milk yield, a significant improvement in milk quality was observed, in par ticular, an increase in fat content by 1.3 times and protein by 1.1 times. The study found that humic acids stimulate the activity of rumen ciliates, which, in turn, leads to a significant increase in the concentration of short chain fatty acids (p<0.05) and improve the absorption of nutrients from the diet. This, in turn, provides a greater amount of amino acids necessary for the synthesis of milk protein, which is confirmed by a statistically significant increase in the protein content of the cows in the experimental group (p<0.05). An important aspect of the effect of humic acids is their ability to stabilize the pH value of the rumen content within the physiological norm, which is probably achieved by increasing the buffering capacity of the rumen fluid after their administration. In addition, humic acids increased the reductase activity of the rumen microflora, which reflects the enhancement of fermentation and metabolic processes, and therefore, improved digestion efficiency. The results obtained indicate a complex positive effect of humic substances on milk productivity and rumen digestion of cows, which makes them a promising feed additive for increasing productivity and improving milk quality in modern dairy farming.

Key words: humic acids, productivity, mass fraction of fat, mass fraction of protein, dry matter, short-chain fatty acids, reductase activity, rumen con tent, pH value.