The article discusses the results of scientific and economic experiment carried out on black-motley breed cows on the use of mineral and energy supplement, ‘Reactor’, which includes energy components, calcium propionate, betaine and natural sorbent. The complex action of the investigated product had a positive impact on animal productivity. It was established experimentally that using during the transitional period of 250-350 gr. of ‘Reactor’ per head daily allows to increase daily milk yield of cows in the first hundred days of lactation by 9.8 and 14.5% (to 30.3 and 31.6 kg vs. 27.6 kg in control), to improve milk production profitability level by optimizing feed consumption, and to reduce the service period.