In the Sverdlovsk region, in herds of Holstein black-and-white cattle of the Ural type, up to 98% of cows are descended from bull producers of foreign selection. Assessment of the influence of a bull producer on the productive qualities of daughters is relevant and of practical importance, especially in conditions of increased blood in the Holstein breed. The daughters of the breeding bull Gavano had the highest indicators in terms of milk production, the daughters of the breeding bull Das were in second place. It should be noted that the milk yield for 305 days of lactation in all studied animals was within the range of 6583 (daughter of bull Cassio) - 8106 (daughter of bull Gavano) kg, which indicates a high potential for productivity in the cows of this herd. The superiority of the daughters of bull Gavano in milk yield ranged from 445 to 1523 kg or 5.5 - 18.8% and was reliable in favor of the former (P≤0.05 - P≤0.01). The highest rates for fat mass fraction in milk were found in the daughters of bull De-Su. 4,0 and 4,01% of fat was in milk of cows-daughters of the Sayan, Mers and Cassio bulls. In terms of protein mass fraction in milk, cows differed from bull De-Su for the worse. In the milk of cows-daughters of other bull producers the protein mass fraction was in the range of 3.13-3.17%. The yield of milk fat and milk protein was more influenced by milk yield in 305 days of lactation. Most of the nutrients were obtained from the milk of the cows-daughters of bull Gavano. The daughters of bull Sayan were in second place, only slightly inferior to them were the daughters of bulls Das and De-Su. Less nutrients were obtained with milk from the daughters of bull Cassio. All cows had a dairy production direction, as evidenced by a high milk yield ratio from 1186 to 1432 kg of milk per 100 kg of live weight of a cow. The farm uses daughter cows from Holstein bull producers with a high genetic potential for productivity.

For insemination of cattle’s broodstock, the bulls’ seed is used, both domestic and foreign selection, that is, the increase in blood count of received heifers for the Holstein breed continues. The growth of animals, despite general growth patterns, is influenced by many factors, including their origin. The research aim is to assess weight growth characteristics of replacement heifers, depending on their origin, namely the father – the servicing bull. It was found that the difference in live weight at birth between heifers of different seed bulls was insignificant and amounted to 1.4 kg or 4.7%. The highest live weight at 18 months of age had heifers from the Sayan bull – 425.3 kg, slightly 3.6-5.3 kg inferior to them were the heifers from the Cassio and Mers bulls. Heifers grew unevenly over the periods. The uneven growth of heifers of different seed bulls, although it has a general pattern, but differs in groups. If in the period from 6 to 12 months of age there is a decrease in absolute growth in all groups, then already in the next period we can note the peculiarities in absolute growth change. So, the absolute growth of the heifers from the Das bull remained at the same level; the absolute growth of the heifers from the Sayan, De-Su, Tuareg, Cassio bulls continued to decline, and the absolute growth of the heifers from the seed bulls Havano, Mers and Bentley increased. On average, for the entire growing period, it ranged from 21.0 to 22.0 kg per month. Thus, the culture system of replacement heifers on the farm allows to get good results. The age of the first heifers’ insemination, depending on belonging to the seed bull, ranges from 14.3 to 16.9 months, which allows us to speak about using early terms of the first heifers’ insemination. The live weight at the time of the first insemination meets the requirements.

For insemination of the breeding stock of dairy cattle the semen of sires of both domestic and foreign breeding is used. Due to the fact that the issues of herd reproduction have become one of the most important factors of progress in dairy cattle breeding, the rearing of replacement young animals is given great importance. The purpose of the research was to study the age dynamics of the growth of replacement heifers depending on origin from sire. It was found that the diff erence in live weight at calving between heifers from diff erent sires was insignifi cant and amounted to 1,4 kg or 4,7 %. The heifers from the sire Sayan had the highest live weight at the age of 18 months – 425,3 kg, the heifers from the sires Cassio and Mers were slightly inferior to them by 3,6 and 5,3 kg. According to the rearing periods the heifers grew unevenly. The uneven growth of heifers from diff erent sires, although it had a common pattern, but diff ered by groups. So, from 6 to 12 months of age, there was a decrease in absolute gain in all groups, but in the next period (12–15 months), there were features in the change in absolute gains. So, in heifers from the sire Das, the absolute gain remained at the same level, and in heifers from the sires Sayan, De-Su, Touareg, Cassio, it continued to decline, while in heifers from the sires Gavano, Marrs and Bentley it is increased. On average, over the entire rearing period, it ranged from 21,0 to 22,0 kg per month. Thus, the system of rearing of replacement heifers on the farm allows us to get good results. The age of the fi rst insemination of heifers, depending on the origin of the sires ranges from 14,0 to 15,9 months with eff ective insemination at the age of 14,8–16,9 months, which suggests the use of early terms of the fi rst insemination of heifers. The live weight of heifers at the fi rst insemination meets the requirements for cattle of Black-and-White breed, regardless of their origin from sire.