Purpose: to determine the potential of the Russian subpopulation of the Holstein breed in relation to selection by loci of beta-and kappa-casein.Materials and methods. For loci CSN2 and CSN3, 1,539 Holstein cattle were genotyped, including 1,242 cows and heifers and 297 sires, and information on CSN2 and CSN3 genotypes of 297 US bulls was analyzed (World Wide Sires, Ltd).Results. It has been established that in the last two years there has been an increase in the percentage of sires in WWS with CSN2 genotypes A2A2 and CSN3 genotypes BB. Thus, sires allele frequency in the 2019 catalog was 0.51 and 0.29, respectively; and in the 2021 catalog was 0.68 and 0.31, respectively.Genotyped sires of domestic breeding organizations, which are mostly foreign origin, were characterized by predominance of the A2 allele CSN2; in this group the frequency of the allele was 0.63. However, the CSN3 B allele in the group of sires belonging to domestic organizations was found with a frequency of 0.34, which is 1.6 times lower than that of sires of American origin.In the genotyped group of Holstein cows and heifers (n = 1242) belonging to 3 large farms in the Krasnodar Krai, the gene frequency CSN2 allele A2 was minimal (0.57), and the CSN3 allele B (0.40) was higher than the allele frequency in the sires group of domestic breeding enterprises.Conclusion. At present, Russian breeding enterprises and farms are lagging behind in these indicators, however, by conducting targeted selection in accordance with the indicated trend, by selecting the appropriate breeding bulls, it is possible in the next generation to increase the proportion of animals carrying valuable genotypes.
Проведены исследования, направленные на сравнение эффективности оценки быков по отдельным признакам молочной продуктивности их дочерей на базе построения и решения уравнения смешанной модели, оптимизированного для популяции симментальского скота на разных уровнях управления породой. В анализе были использованы региональные базы данных «СЕЛЭКС» 5 регионов. Доказано, что точность оценки генотипов на популяционном уровне управления была существенно выше (на 9,6% в среднем), чем на региональных. При этом методология BLUP-оценки значительно более эффективна по сравнению с использованием официальной инструкции [5, 6] оценки быков, основанной на прямом сравнении продуктивности дочерей со сверстницами. Рассчитанные величины генетических и фенотипических корреляций между отдельными признаками молочной продуктивности в породе существенно различались как по значениям, так и по направлению взаимосвязей. Эти результаты определили существенную вариабельность значений ранговой корреляции между быками, oцененными на породном и региональных уровнях управления. В результате организация оценки быков-производителей на породном уровне управления имеет существенные преимущества в сравнении с ее проведением на региональных уровнях. From theoretical and practical points of view the breeding value evaluation is a base for all other breeding activities with animals in the population. In this regard studies on comparative effectiveness of sire’s breeding value estimation on different levels of Simmental breed management have been conducted. The analysis was used the data base of breeding records of five regions. The assessment procedure was carried out at regional subpopulation management levels and at the breed level. It was proved that the accuracy of evaluating genotypes at the population management level is significantly higher (by 9,6 percent) than it’s at regional levels. At the same time, the BLUP methodology turn out to be more effective in comparison with a direct comparison of the productivity of daughters and their herd mates. The calculated phenotypical and genetic correlations between single traits of dairy production significantly differed both in magnitude and in their direction. These results determined a significant variability in the values of rank correlations between sires assessed at the breed and regional levels of management. As a result, organization of sire’s breeding value evaluation at breed level of management with Simmental breed has much more advantages with its conduct at the regional levels.
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