In Sverdlovsk region Holsteinized black-and-white cattle of Ural type are bred. This livestock is represented by highly productive animals with a high genetic potential for productivity. The aim of the research is to study the productive qualities of the Holsteinized black-and-white cattle with a high proportion of blood relationship to Holstein breed. Milk yield increases with age of cows. The difference between the first and second lactation amounts to 1.084 kg or 11.4%, and between the second and third lactation it is 326 kg (3.0%). In general, the milk yield of mature (full-aged) cows was higher by 1.410 kg or 14.9% than the milk yield of first-calves It is known that mature full-aged cows have a productivity 30% higher than the first-calves. I. e. the genetic potential of the farm broodstock of full-aged cows is within 12.595 kg, and this potential is not fully used. The farm uses cows that are quite different in terms of milk yield. The fluctuations in milk yield from lactation to lactation are 7.060 kg (1st lactation), 10.210 kg (2nd lactation) and 6.785 kg (3rd lactation). In terms of the milk quality indicators – MFF (mass fraction of fat) and MFP (mass fraction of protein) no significant differences in lactation were established, although a certain positive tendency was observed for increase of MFF with age gaining in reference to the first-calves.
In Sverdlovsk region Holsteinized black-and-white cattle of the Ural type are bred. The herd is represented by large bodied, highly productive animals with a high genetic potential for milk productivity. The aim of the research was to study the productive qualities of Holsteinized black-and-white cattle with a high blood relationship to Holstein breed depending on the line, and correlation between milk yield and live weight of cows. The average milk yield for 305 days of lactation in cows of both lines was almost the same, and the difference between them was insignificant. However, when considering the change in milk yield within the groups, it was found that the group of Reflection Sovering cows featured higher performance indicators – from 8.376 to 14.706 kg of milk. The difference between low productive and high productive cows yield amounted to 6.333 kg or 43.1%. In Vis Back Ideal group of cows the difference was less expressed, and amounted to 5.367 kg or 40.4%. The coefficient of variability in the groups was within the range of 26-28%, which indicates significant fluctuations in milk yield. The yield of nutrients in milk (the amount of milk fat + milk protein) was at the equal level - 783 and 730 kg.
In Sverdlovsk region Holstein black-and-white cattle of the Ural type are bred, which are represented by highly productive animals with a high genetic potential for productivity. The aim of the work was to study the effect of genotypes of the kappa-casein gene on milk productivity and quality indicators of milk from Holstein black-and-white cattle of the Ural type. Most of the cows had the AA kappa-casein genotype, and they had the worst indicators of technological properties in terms of cheese suitability. The best technological properties of milk are possessed by cows with the BB kappa-casein genotype. There were only 4.2% of such animals among those examined. The highest milk yield in 305 days of lactation was observed in cows with the genotype for BB kappa casein (9595 ± 314.3 kg), which is 373 kg and 537 kg more, or 3.9 and 5.6% more than in animals with AA and AB genotypes, respectively. The indicators for the mass fraction of fat and mass fraction of protein in the milk of cows of different genotypes for kappa-casein were the same. There was a tendency to an increase in the protein content in the milk of cows with the BB genotype and a decrease in the mass fraction of fat in the milk of cows with the AB genotype. Thus, more nutrients, namely milk fat with the same content in milk, were obtained in the group of first-calf heifers with the BB genotype (380 ± 13.19 kg). They also had a higher yield of milk protein (311 kg), which is more than in other groups by 13 and 19 kg.
Currently first place in the number is a domestic black-motley breed, second place – Holstein. In the Sverdlovsk region, the Ural type of black-and-white cattle was created and officially registered in 2002 by crossing the breeding stock of the black-and-white breed of the Ural offspring with the Holstein bulls. In recent years, there has been a stable significant increase in milk productivity, as a result of which in five years the milk yield for the herd increased by 1388 kg of milk, and for full-aged cows by 1655 kg and reached 10257 kg. A significant increase in productivity was accompanied by a significant increase in the fat content in milk by 0.26% on average for the herd, and by 0.47% for first heifers. protein-Milk content has not changed much, but it is still not high enough. Over the past five years, there has been an increase in the variability of the main selectible trait – milk yield for both the first and third lactation. The selection boundaries for such an important quality indicator of milk as protein content have been slightly expanded. Coefficient of variability in protein content. The negative impact of milk yield on the level of fat content of the herd over the past more than 15 years has naturally changed from an average negative to an average positive in first-heifers, and in full-aged cows it has decreased from -0.17 to -0.08. The dependence of milk yield after the third calving on the results of the first lactation has decreased, but it is still quite significant, as evidenced by the corresponding correlation coefficient of 0.28. The increase in the correlation coefficient between the milk yield of mothers and daughters has almost doubled in ten years.
The improvement of dairy cattle in the Russian Federation is currently being carried out through the use of the gene pool of the world’s best dairy breed as Holstein. This had a positive effect on the dairy productivity of cows, but led to a decrease in productive longevity. Therefore, the reasons for culling the breeding stock of dairy cattle depending on the part of blood of Holstein breed are of considerable interest. At the same time, it is relevant to study the duration of use of cows in herds with industrial exploitation technology. The purpose of the research was to analyze the reasons for culling holsteinized cows of Black-and-White cattle, depending on age. The data on the reasons for culling cows, taking into account the age of cows in lactations have been presented in the article. It has been established that the most common causes of culling are pathology of metabolism, reproductive system, digestive system, selection criteria (mainly barrenness) and pathology of the mammary gland. The age of cows has a certain influence on the level of culling, which increases in full-aged cows. Young cows drop out of the herd due to the pathology of the reproductive system, breast, metabolism, barrenness and injuries. Thus, it was found that the dynamics of metabolic disorders diff ered rhythmically, then increasing, then decreasing from lactation to lactation. This is especially clearly seen from 1 to 5 lactations, and then this dynamics tended to decrease, slightly increasing by 8 lactation. In general, for culled animals the largest culling from the herd was observed for full-aged cows 65,0 % of the total number of culled, including for 3 and 4 lactations 41,0 %. Culling of young cows for 1 and 2 lactations was 35,0 %.
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