The results of the evaluation of genomic inbreeding of stud bulls of Black-and-White and Holstein breeds of the Central region of Russia are presented. The studies were carried out by detecting long homozygous fragments in the animal genome – runs of homozygosity (ROH), compared to the traditional approach of determining inbreeding by pedigree. ROH analysis was performed using the Illumina Bovine SNP50K v2 BeadChip biochip with the density of 54609 SNP in the population of stud bulls of Black-and-White and Holstein breeds (n = 100) in Moscow and Leningrad regions. The largest number and total length of ROH in the studied population were found on chromosomes 3, 6, 9, 10, 20, and 24, with an average length of 10.34; 9.15; 10.33; 12.37, and 9.05 Mb, respectively. The number of ROH segments varied from 5 to 34, with an average of 19.1. The average ROH size was 8539 ± 161 kb with the total number of nucleotide mutations of 136.2 ± 2.5 SNP and coverage density of 62.2 kb. It was found that the larger the inbreeding value by pedigree, the higher the frequency of occurrence of homozygous segments (on average from 15.5 to 25.7, respectively, with the inbreeding value from 0 to 8.5%). The total length of the fragments and the average value of ROH tend to increase depending on the inbreeding level (271.3 Mb and 10862 kb at the inbreeding value of 5.0% and higher). The highest repeatability with the inbreeding coeffi cient was obtained for the sum of homozygous genome patterns and diallelic markers, 0.517 and 0.475, respectively. Monitoring the level of homozygosity on the basis of genomic information most accurately refl ects the true level of inbreeding, and allows more effi cient monitoring of the breeding process in animal populations.

На примере популяции голштинизированного чернопестрого и голштинского скота, а именно быковпроизводителей, используемых на территории Московской области, было проведено ретроспективное исследование, направленное на определение уровня гомозиготности по STRмаркерам, с последующей оценкой влияния на основные хозяйственнополезные качества и племенную ценность животных. Произведен расчет генетических дистанций и индекса фиксации с учетом страны происхождения, породной и линейной принадлежности в исследуемой популяции. При анализе использовали 12 пар микросателлитных локусов, с последующим сокращением до 9 пар для расчета уровня гомозиготности:TGLA227, BM2113, ETH10, SPS115, TGLA122, INRA23, BM1818, ETH225, BM1824. Коэффициенты наследуемости основных показателей продуктивности и воспроизводства были следующими: удой за 305 дней лактации (h20,146), массовая доля жира в молоке (h20,170), выход молочного жира (h20,139), массовая доля белка в молоке (h20,142), выход молочного белка (h20,124), количество дойных дней (h20,030), продолжительность сервиспериода (h20,033) и живая масса животного (h20,102).Построен генетический тренд по удою за 305 дней лактации в разрезе лет 19832011гг., отражающий селекционную работу в регионе, выраженную в повышении удоя на 104 кг в среднем за период в 4 года. Отмечен низкий индекс фиксации и значения генетических дистанций между животными с учетом страны их происхождения относительно РФ: Германия (Fst0,004 Nei0,021), Голландия (Fst0,005 Nei0,025), Дания (Fst0,007 Nei0,038), Канада (Fst0,011 Nei0,061). Генетические дистанции по Нею и индекс фиксации между породами относительно чернопестрой голштинской: краснопестрая голштинская (Fst0,01 Nei0,054), чернопестрая (Fst0,023 Nei0,118), холмогорская (Fst0,125 Nei0,438). Отмечено отсутствие дивергенции с незначительной дифференциацией линии Силинг Трайджун Рокит 252803 при попарном сравнении между линиями относительно Рефлекшн Соверинг 198998: Вис БэкАйдиал 1013415 (Fst0,002 Nei0,011), Монтвик Чифтейн 95679 (Fst0,01 Nei0,049), ПабстГовернер882933 (Fst0,019 Nei0,105), Силинг Трайджун Рокит 252803 (Fst0,05 Nei0,248). Наблюдается увеличение однородности в динамике между группами по годам рождения (19832014) от Fst0,015,Nei0,081 до Fst0,05,Nei0,024.On the example of the population of Holsteinized blackandwhite and Holstein cattle, namely: sire used in the territory of the Moscow region, a retrospective study was conducted aimed at determining the level of homozygosity by STR markers, followed by an assessment of the impact on the main economically useful qualities and breeding value of animals.The calculation of genetic distances and fixation index was made taking into account the country of birth sires, breed and linear affiliation in the studied population. In the analysis, 12 pairs of microsatellite loci were used, followed by reduction to 9 pairsfor calculating homozygosity level: TGLA227, BM2113, ETH10, SPS115, TGLA122, INRA23, BM1818, ETH225, BM1824. The heritability coefficients of the main indicators of productivity and reproduction were: milk yield for 305 days of lactation (h2 0.146), fat percent in milk (h2 0.170), milk fat (h2 0.139), protein percent (h2 0.142), milk protein (h2 0.124), days in milk (h2 0.030), days out (h2 0.033) and live body weight (h2 0.102). A genetic trend for milk yield for 305 days of lactation in the context of the years 19832011 was built, reflecting the breeding work in the region, expressed in an increase in milk yield by 104,1 kg. on average for a period of 4 years. A low fixation index and values of genetic distances between animals with regard to their country of birth relative to the Russian Federation were noted: Germany (Fst 0.004 Nei 0.021), Holland (Fst 0.005 Nei 0.025), Denmark (Fst 0.007 Nei 0.038) , Canada (Fst 0.011 Nei 0.061). Genetic distances according to Nei and the fixation index between the breeds relative to the blackandwhite Holstein: redandwhite Holstein (Fst 0.01 Nei 0.054), blackandwhite (Fst 0.023 Nei 0.118), Kholmogory (Fst 0.125 Nei 0.438). No divergence was noted with a slight differentiation of the Sealing TrijunRokit 252803 line with a pairwise comparison between the lines relative to Reflection Sovering 198998: Vis Back Aidial 1013415 (Fst 0.002 Nei 0.011), MontvikChiftain 5679 (Fst 0.01 Nei 0,049) Pabst Governor 882933 (Fst 0.019 Nei 0.105) Sealing Tridegin Rocket 252803 (Fst 0.05 Nei 0.248). There is an increase in homogeneity in the dynamics between groups by year of birth (19832014) from Fst 0.015, Nei 0.081 to Fst 0.05, Nei 0.024.

The object of the study was sires of the Black-and-White and Holstein breeds, which had STR profiles and passed the genotyping procedure for SNP markers. The subject of the study was the level of genomic inbreeding and homozygosity, as well as population-genetic characteristics based on them. With an increase in Fx based on pedigree data, an increase in the level of genomic inbreeding (FROH) calculated from SNP markers was also noted. The results for 9 STR markers record a wavelike increase in homozygosity from group I to group IV with a subsequent increase from group V to group VII inclusive. During the study of the average FROH values in accordance with the years of birth of sires, a significant difference was found between the last two groups (2009-2011; 2012-2014) from all the others in a pairwise comparison. The results of calculating the FROHand Ca9 of bulls from different countries of origin indicate a statistically significant differentiation of the group of animals from Russia (RF) from animals, born in German and Canadian. A significant difference was noted for the highest FROH level in the samples in the Holstein Black-and-White breed from the Red-and-White Holstein and Black-and-White breeds. The Fst values between the SNP and STR species of the animals had insignificant differentiation (0.008-0.027). Differences in STR calculation between the Black-and-White Holstein and Red-and-White Holstein breeds were insignificant, less than 20%, while the rest of the values differed many times. Fst between RF and Germany, RF and the Netherlands according to STR data is 0.006 and 0.008, according to SNP data 0.005 and 0.006, respectively. A mutual increase in the value of Fst and the year of birth of the sires was noted, emphasizing the greatest remoteness of the population of 1983-1997 from the populations of recent years, when new genotypes of bulls were obtained. The similarity of Fst values between genealogical lines is replaced by a significant scatter in the indicators when they are compared in pairs.

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