Relevance. In ensuring food security in Russia, the intensification of livestock industries, including dairy farming, which has been actively developing in recent years, is of particular importance. A special role is given to the modernization of milk production at highly industrial dairy farms and complexes [3, 4, 6].

In the Penza Region, same as in other Russian regions, along with the reconstruction of old dairy farms, large dairy complexes equipped with modern technological equipment are being built, and the breeder’s stock is formed at the expense of highly productive imported and domestic Holstein cattle. It is quite obvious that the realization of the genetic potential of such livestock is possible only under the proper conditions of feeding and management [9].

The limiting factor in the development of dairy cattle breeding is the realization of the reproductive potential of cows [1, 2, 11, 12]. Reproduction is the main component that has a direct impact on the efficiency of the enterprise. It determines not only the high milk productivity of the herd but also allows reducing the costs of insemination and conducting a more intensive culling of low-productivity and “problem” livestock by introducing young animals with a higher genetic potential into the herd [13–15].

The efficiency of reproduction of a dairy herd consists in reducing the duration of the service period for the herd as a whole, as well as for each animal, increasing the efficiency of insemination and reducing the number of sperm doses spent on fruitful insemination, as well as minimizing abortions throughout the entire period of gestation. To get one calf per year from a cow, the duration of the service period should not exceed 80–90 days, and the optimal time for fertilization of animals is considered to be the 2nd month after calving. A shortened to 30 days and an increased service period of more than 90 days negatively affects the productivity and reproductive functions of cows.