Breeding Bulls Research Articles

Meat productivity and biological value of meat in bulls of various breeds

Our study presents the results of a comparative assessment of meat productivity and biological value of meat in bulls of various breeds. The work was carried out at OJSC named after N.E. Tokarlikov of the Almetyevsk region of the Republic of Tatarstan using industrial technology in three groups (18 heads in each group): I - Simmental, II - Black-and-White and III - Hereford. Relatively high rates of meat productivity and qualitative characteristics of the meat were determined in Hereford bulls: meat weight was 1.7 and 4.5% more compared with Simmental and Black-and-White peers. The meat index in animals of the meat direction (4.59) is higher by 7.5 and 5.5% compared to analogues of I and II groups. The specific gravity of the protein did not have significant differences (18.60-19.05%). At the same time, a higher level of fat was noted in meat from beef cattle - by 1.05 and 1.51%. They also favorably differed in essential amino acids content in the proteins of muscle tissue. Their amino acid score was above 100%. A more balanced ratio of essential amino acids was established in individuals of beef cattle when calculating the biological value of the protein. Meat from animals of Hereford breed was differed by relatively high level of non-essential amino acids - 318.8 mg per 1 g of protein, which is 1.3 and 10.4% more than in the peers of the first two groups.

Variability of indicators of milk productivity in cows of different genotypes and with different index of lactation constancy

at present, the livestock industry in Russia is aimed at obtaining highly productive cows, taking into account their individual characteristics. It is known that animals with high genetic potential react to certain environmental changes especially. Hence, phenotypic evaluation will not help select the best cows with high genetic potential. Therefore, the assessment of individual qualities requires a new approach, which can be safely attributed to various kinds of indices, among which the index of lactation constancy occupies a special place. Such an index score fully characterizes the genotype. Any herd is characterized by a large genetic diversity of individuals. The variability of milk productivity traits determines this diversity, therefore, among highly productive cows there are those that are able to maintain the amount of milk yield and other valuable traits and be able to pass them on to their descendants. The main goal of breeding is aimed at identifying cows with such a valuable genotype and further their widespread use within the farm. Cows, daughters of different breeding bulls with a high index of lactation constancy, can serve as a starting point in the selection of producers with further recommendation for their use in different populations with different levels of productivity.

Identification of Pentatrichomonas hominis in preputial washes of bulls in Brazil.

The parabasalid Pentatrichomonas hominis is generally considered to represent a symbiotic component of the gastrointestinal microbiota in a wide variety of vertebrate hosts including humans. Nevertheless, a limited number of studies have raised the possibility that it may act as a pathogen of humans, dogs, and pigs and that some human infections may have a zoonotic origin. Data from North America revealed an association between P. hominis and the bovine urogenital tract, principally in bulls and rarely in cows. The importance of this observation is linked to possible interference in the accurate diagnosis of the economically important venereal pathogen Tritrichomonas foetus. The current study employed culture-based and molecular methods to examine the preputial cavities of four breeding bulls, raised in open pasture in southeastern Brazil, for the presence of trichomonads. Motile protozoa were isolated from three of the bulls and were definitively identified as P. hominis based on nucleotide sequencing of polymerase chain reaction (PCR) amplicons derived from the ribosomal RNA operon (ITS1-5.8S rDNA-ITS2) of the parasite. The potential implications of these findings for bovine and human health are discussed.

Effect of bull-calf management system on meat productivity

Traditional technologies for the production of beef in the conditions of industrial production of livestock products in the middle of the 20th century were schematically transferred from dairy cattle breeding and do not take into account the behavioral characteristics of animals. The traditional approach to the cultivation of young animals involves a stall-and-loose keeping system, mechanized distribution of feed and manure cleaning. Under such conditions the labor costs for the production of 1 kg of beef are within 15-30 man-hours, the total specific weight of feed, electricity, fuel and lubricants, depreciation costs of livestock buildings and technological equipment in the cost structure of this product reaches 50-55%. Beef production remains unprofitable regardless of animal breed – the cost of 1 kg of meat is 1.5-2 times higher than the sales price, which hinders further development of the industry. The paper shows the results of the assessment of meat productivity of bulls of various breeds when raised using traditional and low-cost technologies. Research results are relevant for beef production in steppe regions.

Мясная продуктивность бычков разных пород

The article presents the results of the evaluation of the slaughter qualities of bulls of different breeds and the directions of productivity. The object of the study were bulls of the red steppe (group I), Simmental (group II) and Kazakh white-headed (group III) breeds. When studying the slaughter qualities of bulls during the control slaughter, the pre–slaughter live weight, the mass and yield of the paired carcass, as well as the internal raw fat, slaughter weight, slaughter yield were established. The obtained experimental material was processed by the method of variation statistics according to N.A. Plokhinsky with the determination of the reliability of the difference using the Student's criterion. It was found that the absolute and relative mass of the paired carcass of Red steppe bulls was 229.6 kg and 53.8%, respectively, young Simmental breed – 269.5 kg and 56.2%, Kazakh white-headed breed animals – 259.2 kg and 57.1%. At the same time, the absolute and relative mass of intracavitary raw fat in group I bulls was 10.6 kg and 2.5%, group II – 13.9 kg and 2.9%, group III – 13.2 kg and 2.9%. As for the slaughter weight and slaughter yield, the value of these indicators was at the level of 240.2 kg and 56.3% for red steppe bulls, 283.4 kg and 59.1% for young Simmental breed, 272.4 kg and 60.0% for Kazakh white–headed breed animals %.

Nutritional and biological value of meat from young bulls of dairy breeds

Nutritional and biological value of meat from young bulls of dairy breeds

Племенная ценность по удою быков- производителей как фактор отбора по молочной продуктивности первотелок

Studies have been conducted to identify the influence of the father's breeding value (BVF) in milk yield on the superiority of his daughters (BVY1l) over their peers on this trait, lactating in 2020 in the herds of the Leningrad region (n=3062). A positive correlation of BVF with the absolute milk yield of daughters and BVY1l was established, but this relationship is not high (+0,127 and +0,128). The sample is divided into three groups BVF by milk yield (from –410 to +1554 kg of milk): I – BVF milk yield of less than –100 kg («degraders») – 18,9 %; II – BVF milk yield of –100 to +99 kg («neutral») – 35,7 %; III – BVF milk yield of +100 kg or more («improvers») – 45,4 %. In terms of breeding value by milk yield, on average, the first heifers of group I lagged by –75±12 kg, group II – by –3±9 kg, and in group III the superiority was +41±9 kg. But at the same time, regardless of the level of BVF in all selection options, the number of daughters of bulls has both positive and negative value. So, in group I, 29,7 % of animals surpass their peers by +100 kg of milk or more, in group II, 32,8 % of such animals, and in group III, on the contrary, 32,5 % of the first heifers were inferior to their peers by –100 kg or more of milk. Thus, it can be stated that with an increase in BVF, an increase in BVY1l is observed. the descendants of the bull, that is, the official evaluation of the breeding bulls can be used as an animal selection tool to improve the breeding qualities of the herd.

Influence of foreign and domestic breeding bulls on indicators of lactation performance and natural resistance of daughters

Influence of foreign and domestic breeding bulls on indicators of lactation performance and natural resistance of daughters

Semen quality variations in successively graded up Sahiwal breeding bulls

Semen quality variations in successively graded up Sahiwal breeding bulls

Effect of Breeding Bulls on Growth Performance and Survivability of Brahman Crossbreds in Rural Areas of Bangladesh

Effect of Breeding Bulls on Growth Performance and Survivability of Brahman Crossbreds in Rural Areas of Bangladesh

The Importance of Reproductive Behavior Tests in Bull Breeding Soundness Evaluation

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Sperm DNA 5-methyl cytosine and RNA N6-methyladenosine methylation are differently affected during periods of body weight losses and body weight gain of young and mature breeding bulls.

Aiming to characterize the effects of nutritional status on epigenetic markers, such as DNA 5-methyl cytosine (mC) methylation and RNA N6-methyladenosine (m6A) methylation, of bovine sperm, 12 Angus × Hereford crossbred breeding bulls were submitted to nutritional changes for a period of 180 d: no change in body weight (BW) (phase 1 = 12 d), BW loss (phase 2 = 78 d), and BW gain (phase 3 = 90 d) in a repeated measures design. Animals were fed Beardless wheat (Triticum aestivum) hay and mineral mix. Statistical analyses were performed using SAS 9.4 (SAS Inst., Cary, NC). Higher levels of RNA m6A (P = 0.004) and DNA methylation (P = 0.007) of spermatic cells were observed at phase 2 compared with phase 1. In phase 3, sperm RNA m6A methylation levels continued to be higher (P = 0.004), whereas the DNA of sperm cells was similar (P = 0.426) compared with phase 1. Growing bulls had a tendency (P = 0.109) of higher RNA m6A methylation levels than mature bulls. Phase 2 altered scrotal circumference (P < 0.001), sperm volume (P = 0.007), sperm total motility (P = 0.004), sperm progressive motility (P = 0.004), total sperm count (P = 0.049), normal sperm (P < 0.001), abnormal sperm (P < 0.001), primary sperm defects (P = 0.039), and secondary sperm defects (P < 0.001). In phase 3, bulls had scrotal circumference, sperm volume, sperm motility, sperm progressive motility, total sperm count, normal and abnormal spermatozoa, and primary and secondary spermatozoa defects similar to phase 1 (P > 0.05). Serum concentrations of insulin-like growth factor-1 and leptin decreased during phase 2 (P = 0.010), while no differences (P > 0.05) were detected between phases 3 and 1; growing bulls tended (P = 0.102) to present higher leptin levels than mature bulls. Specific for mature bulls, DNA methylation was positively correlated with leptin concentration (0.569, P = 0.021), whereas for young bulls, DNA methylation was positively correlated with abnormal spermatozoa (0.824, P = 0.006), primary spermatozoa defect (0.711, P = 0.032), and secondary spermatozoa defect (0.661, P = 0.052) and negatively correlated with normal spermatozoa (-0.824, P = 0.006), total sperm count (-0.702, P = 0.035), and sperm concentration (-0.846, P = 0.004). There was no significant correlation (P > 0.05) between RNA m6A and hormones and semen traits. In conclusion, the nutritional status of breeding bulls alters epigenetic markers, such as DNA methylation and RNA m6A methylation, in sperm, and the impact of change seems to be age dependent. These markers may serve as biomarkers of sperm quality and fertility of bulls in the future. Detrimental effects on sperm production and seminal quality are observed at periods and places when and where environmental and nutritional limitations are a year-round reality and may carry hidden players that may influence a lifetime of underperformance.

PHENOTYPIC VARIABILITY OF SPERM PRODUCTIVITY OF BULL-SIRES OF DIFFERENT DIRECTIONS OF PRODUCTIVITY

Significant breeds and age features of sperm productivity were found in breeding bulls. The volume of ejaculate and the total number of sperm in it increases until the age of 8–9 years, depending on the breed. The ejaculate volume of 2-year-old bulls, depending on the breed, was 58.63–73.0% and 3-year-old bulls – 69.1–87.0% of the ejaculate volume of 6-year-old offspring, and the total number of sperm in the ejaculate – respectively 53.9–75.4 and 59.5–90.4% of this number of sperm in the ejaculate of 6-year-old bulls. These indicators with small fluctuations persist until 10–12 years of age of the offspring. Sperm concentration and motility also increase until 6–8 years of age and remain at this level with small fluctuations until 12 years of age. The resistance of sperm to freezing reaches its maximum values at the age of 5–6 years of bulls. Analysis of the data shows that the degree of influence of age on the volume of ejaculate, depending on the breed is in the range of 24.2–30.1%, on the concentration of sperm – 2.6–15.2, their total number in the ejaculate – 13.8–21.2, sperm motility – 4.3–18.3 and the resistance of sperm to freezing – 8.5–15.8%.&#x0D; According to the results of research, the correlation coefficient between age and ejaculate volume for bulls of the studied breeds was 0.43–0.60, and between age and the total number of sperm in the ejaculate – 0.37–0.48. There is a significant dependence of ejaculate volume and total sperm count on the live weight of the fetuses. The correlation coefficient between ejaculate volume and live weight, depending on the breed, was 0.51–0.75, and for the total amount in ejaculate – 0.45–0.55. The share of live weight on ejaculate volume was 25.0–43.1%, and on the total number of sperm in ejaculate – 20.8–36.9%. This close relationship can be explained by the fact that the weight of the testes has a high relationship with the live weight of the ovary (r = 0.89).&#x0D; The results of research show that the semen of breeding bulls of different breeds has different morphological composition. The largest number of sperm abnormalities occurs in isolated heads (3.5 ± 0.14%), curved bodies (2.7 ± 0.19%), twisted (1.6 ± 0.14%), bent (1.7 ± 0.14%) and folded (3.4 ± 0.40%) tails. The sum of primary anomalies was significantly less than the sum of secondary anomalies.&#x0D; When dividing pathological forms into pathology of the head, neck, body and tail, it was found that the total amount of abnormal forms of sperm was the largest in bulls of limousine breed (16.6 ± 2.19) and the smallest – in the offspring of Aberdeen Angus and Simmental breeds. The largest number of pathological forms of sperm heads were bulls of Hereford breed (7.0 ± 0.55%), and the smallest – the offspring of Aberdeen Angus breed (4.2 ± 0.83%), the difference is statistically significant at P &lt; 0.005. The sum of primary anomalies was highest in bulls of Limousine breed (2.9 ± 1.03) and Dutch breed (2.1 ± 0.42), and secondary anomalies – in bulls of Limousine breed (13.7 ± 1.87) and Piemontese breed (13.7 ± 2.19%).&#x0D; During the correlation-regression analysis, the closest correlation was established between the motility of germ cells after thawing and the number of pathologies of the heads (r = -0.43 at P &lt; 0.05), cervical sperm (r = -0.44 at P &lt; 0,05) and the total amount of pathological forms (r = -0.45 at P &lt; 0.005). Average correlations were observed between the number of pathologies of the heads and necks of sperm and the motility of germ cells in native semen (respectively r = -0.31 and r = -0.30 at P &lt; 0.05), pathologies of the heads – -0.30 at P &lt; 0.005) and the total amount of pathological forms of sperm (r = -0.23 at P &gt; 0.05) and the amount of rejected sperm. The share of the influence of the age of bulls on the number of pathological forms of the heads was 24.0% (P &lt; 0.05), pathologies of the necks – 4.0% (P &gt; 0.05), the body – 26.0% (P &lt; 0.05), tail – 37.0% (P &lt; 0.01) and the total number of pathological forms of sperm – 59.0% (P &lt; 0.001).&#x0D; Conclusions. Age and breed features of quantitative and qualitative indicators of sperm productivity, growth of genitals, morphological composition of spermatozoa and correlations between these indicators in bulls of different breeds have been established.

Prevalence of Bovine Genital Campylobacteriosis, Associated Risk Factors and Spatial Distribution in Spanish Beef Cattle Based on Veterinary Laboratory Database Records.

Bovine genital campylobacteriosis (BGC) is a sexually transmitted disease that causes early reproductive failure in natural breeding cattle that are managed extensively. The aim of this study was to assess the BGC prevalence in Spain from 2011 to 2019 using data collected cross-sectionally from the diagnostic reports issued by the SALUVET veterinary diagnostic laboratory from a total of 5,182 breeding bulls from 1,950 herds managed under “dehesa” systems (large herds within fenced pastures and all-year breeding season) or mountain systems (smaller herds with seasonal breeding management and grazing in communal mountain pastures). Infection was detected by PCR in 7.7 and 12.2% of the bulls and herds tested, respectively. The “dehesa” herd management system (OR = 2.078, P = < 0.001, 95% CI = 1.55–1.77), bovine trichomonosis status of the herd (OR = 1.606, P = 0.004, 95% CI = 1.15–2.22), and bulls ≥3 years old (OR = 1.392, P = 0.04, 95% CI = 1.01–1.92) were identified as risk factors associated with Campylobacter fetus venerealis infection. We also studied the high-risk areas for circulation of the infection in extensive beef cattle herds in Spain, showing four significant clusters in “dehesa” areas in the south-western provinces of the country and a fifth cluster located in a mountain area in northern Spain. The results obtained in the present study indicate that BGC is endemic and widely distributed in Spanish beef herds. Specifically, “dehesa” herds are at greater risk for introduction of Cfv based on relatively high local prevalence of the infection and the use of specific management practices.

KOVALENKO GRIGORY SAMIYLOVYCH – A LEADING SCIENTIST IN ANIMAL SELECTION

Kovalenko Hryhoriy Samiylovych was born on October 5, 1946 in the village of Fedorivka, Ivankiv district, Kyiv region, in a peasant family. From 1961 he studied at the Kozelets Zooveterinary College of the Chernihiv region, graduating in 1965 with a degree in zootechnics. In 1973 he graduated from the Ukrainian Order of the Red Banner of Labor Agricultural Academy with a degree in zootechnics.&#x0D; He began his career on January 19, 1966 at the Central Research Station for Artificial Insemination of Farm Animals (Brovary city). He worked as a technician for artificial insemination of cows and heifers, a technician for collecting semen of bulls, a brigadier of the dairy farm, a senior zootechnician for testing breeding bulls, a senior zootechnician of the breeding department.&#x0D; From January 1976 he worked at the Ukrainian Research Institute of Breeding and Artificial Insemination of Cattle as a junior researcher, researcher, senior researcher, head of the sector of bulls assessment.&#x0D; In 1999 he defended his dissertation "Comparative assessment of animals of the Ukrainian Black-and-White Dairy breed with analogues of foreign breeds" in the specialty 06.02.01 – breeding and selection of animals. He received the degree of Candidate of Agricultural Sciences, as well as the academic title of Senior Researcher. Works at the Institute of Animal Breeding and Genetics named M.V.Zubets of the National Academy of Agrarian Sciences of Ukraine as a leading researcher in the Department of Cattle Breeding.&#x0D; The main direction of the scientist's research is the theory and practice of the breed-forming process, the formation of structural units of dairy breeds (intra-breed and factory types, lines, families, herds). Works on the improvement of Ukrainian Black-and-White, Red-and-White Dairy and Simmental breeds and the creation of highly productive herds.&#x0D; He has published 106 scientific papers, including 10 guidelines. G. S. Kovalenko is a co-author of nine structural units of the Ukrainian Black-and-White Dairy breed, in particular the Central-Eastern intra-breed and Kyiv factory types, factory lines of M. Montfrech, S. S. Suddin, Astronaut and Elbrus (order № 127 of the Ministry of Agriculture of Ukraine from 26.04.96), as well as the Southern intra-breed, Pre-Dnistrian and Pre-Dnieper factory types (order № 519/89 of the Ministry of Agrarian Policy of Ukraine from 29.09.2005). The scientist is a co-author of 22 selection programs and plans in Lviv and Kyiv regions, Boryspil and Berdychiv districts and farms of different regions of Ukraine and others. Actively implements nationwide breed improvement programs, in particular, "Breeding programs for Ukrainian Black-and-White Dairy breed for 2003–2012", "Ukrainian Black-and-White breed breeding programs for cattle for 2013–2020". Actively promotes scientific knowledge among dairy professionals.&#x0D; The staff of the department sincerely congratulates the jubilee, wishes him good health and creative longevity.

Slaughter Results, Meat Chemical Composition and pH of Aberdinangus, Hereford and Limousin bulls

Abstract Beef production must combine the interests of both producers and consumers, taking into account the sustainable use of environmental resources. The aim of the study was to analyze and compare the slaughter results, meet chemical composition and pH value of three beef breeds – Aberdinangus (AA), Hereford (HF) and Limousin (LI) bulls. The bulls were fattened on Latvian and Lithuanian farms, mainly using grass forage. The breed and age of bulls before slaughter significantly affected all slaughter results, except for fat class. From the meat chemical composition traits, the bull breed and age before slaughter had a significant effect only on the protein content. LI bulls showed the highest carcass weight 301.1±6.8 kg (p&lt;0.05), dressing percentage 58.2±1.1% (p&lt;0.05) and conformation score 3.56±0.18 points. The best fattened carcasses were obtained from AA bulls - 2.43±0.20 points. Muscle samples of musculus longissimus (M. longissimus) bulls of LI breed showed higher content of moisture (72.0±1.0%), protein (23.0±0.2%), ash (1.1±0.0%) and cholesterol (56.7±6.6 mg 100 g−1). AA breed bulls showed higher total fat (6.6±1.2%) and iron content (13.1±0.6 mg). The highest pH was observed in the meat obtained from AA bulls – 6.0±0.1, LI and HF breed bulls showed pH 5.8±0.0 and 5.8±0.1 respectively. Correlation analysis showed a significant, strong positive correlation between cold carcass weight and dressing percentage for AA and LI bulls, r=0.90 and r=0.88, respectively. For LI breed bulls, a strong positive correlation was also found between the cold carcass weight and the conformation score (r=0.98, p&lt;0.01).

Use of Holstein bulls in improvement of black pied cattle

Sires play an important role in improvement of productive qualities of bred livestock. Most researchers and breeders estimate their impact to be at least 90%. In order to evaluate the results of using different Holstein breeding bulls, we compared the productivity of their offspring with the average values for all bulls. The following methods of variation statistics were used: observation, data grouping, and correlation analysis. It was found that the best are the descendants of the bull Estuary 2186 of the Montwick Chieftain line. Besides, Liman 2186 bull’s daughters excelled in high milk fat content - 4.46%. Daughters of Punch 2748 bull of Pabst Governor line were the best in protein content of milk (3.27%). Daughters of Liman 2186 bull had the highest fat and protein yield during 305 days of lactation. It was established that the direction and value of correlation between the main features of milk yield of cows of different lineages have a rather high degree of variation. Presence of positive genetic correlation between milk yield and protein content in milk in some lines of animals enables breeding cows by two traits simultaneously (milk yield and protein content in milk).

Potential Risk Factors Associated with Infection with Bovine Leukaemia Virus in Dairy and Beef Cattle in Taiwan.

Bovine leukaemia virus (BLV), which is classified as a Deltaretrovirus, is the aetiologic agent of enzootic bovine leukosis (EBL), a chronic lymphoproliferative disorder with a worldwide distribution. EBL is widespread in dairy herds and causes a direct economic impact due to reduced milk production and the early culling of BLV-infected cattle. The BLV infection status in Taiwan remains largely unknown; a high prevalence of BLV in dairy cows was recently revealed. The present study further investigated BLV infections in beef cattle. Surprisingly, the prevalence of BLV proviral DNA was as low as 11.8% (23/195), which is significantly lower than that noted in dairy cows, which was 42.5% (102/240) (p < 0.001). Factors associated with BLV infections were subsequently investigated. Due to the differences in herd management, an analysis of risk factors for a BLV infection was independently conducted in these two sectors. Several factors associated with a BLV infection were identified. Age was significantly associated with BLV infection status in dairy cows (p < 0.001) but not in beef cattle. A high prevalence of BLV was observed in cattle >15.5 months old (57.8%) compared with those ≤15.5 months old (11.4%). Moreover, after stratification analysis, based on the critical age of 15.5 months, as determined by the receiver operating characteristic (ROC) curve, a significantly higher BLV prevalence was demonstrated in lactating dairy cows, cattle undergoing bull breeding, heifers at older ages, and those undergoing routine rectal palpation. Due to the high prevalence of BLV in Taiwan, the development of an effective control program, based on the identified risk factors, is important for interrupting the routes of BLV transmission within herds.

Core Microbiome of Slovak Holstein Friesian Breeding Bulls’ Semen

Simple SummaryThe aim of this study was to characterize the bacterial profile of semen collected from Holstein Friesian breeding bulls via a high-throughput sequencing approach for a 16S rRNA gene variability analysis. A total of 55 fresh semen samples of sexually mature breeding bulls were used in the study. They were gathered from Holstein Friesian breeding bulls at Slovak Biological Services in Nitra, Slovak Republic. To amplify the V4 region of the 16S rRNA bacterial gene, universal primers 515F and 806R enhanced by a 6 bp barcode identification sequence were used. The 16S rRNA high-throughput sequencing strategy was used. Two microbial clusters were identified among the analyzed samples—the first cluster was based on Actinobacteria and Firmicutes, while the second cluster contained a high prevalence of Fusobacteria.Bacterial contamination of semen is an important factor connected to the health status of bulls that may significantly affect semen quality for artificial insemination. Moreover, some important bovine diseases may be transmitted through semen. Up to now, only a very limited number of complex studies describing the semen microbiome of bulls have been published, as many bacteria are hard to cultivate using traditional techniques. The 16S rRNA high-throughput sequencing strategy allows for the reliable identification of bacterial profiles of bovine semen together with the detection of noncultivable bacterial species. Fresh samples from Holstein Friesian breeding bulls (n = 55) were examined for the natural variability in the present bacteria. Semen doses were selected randomly from Slovak Biological Services in Nitra, Slovak Republic. The most predominant phyla within the whole dataset were Firmicutes (31%), Proteobacteria (22%), Fusobacteria (18%), Actinobacteria (13%) and Bacteroidetes (12%). Samples of semen were divided into two separate clusters according to their microbiome compositions using a cording partition around a medoids analysis. Microbiomes of the first cluster (CL1) of samples (n = 20) were based on Actinobacteria (CL1 average = 25%; CL = 28%) and Firmicutes (CL1 = 38%; CL2 = 27%), while the second cluster (CL2; n = 35) contained samples characterized by a high prevalence of Fusobacteria (CL1 = 4%; CL2 = 26%). Some important indicator microbial groups were differentially distributed between the clusters.

Evaluation of breeding bulls based on quality of offspring considering crossing options

Breeding takes the main place in the complex of measures for intensification of dairy cattle breeding. A characteristic feature of breeding work is identification of the most valuable genotypes and their further use in cattle population. The Holstein breed is considered one of the most highly productive breeds, in many countries of the world it is used for the genetic improvement of local breeds. In this regard, a comparative assessment of methods for determining the breeding value of bulls of different genotypes obtained by interbreeding is relevant. The results of assessment of genetic superiority of the used breeding bulls in terms of milk productivity of daughters for the first lactation through interannual deviations of the homogeneous peers are presented, the best producers in all the studied herds are identified, it is established which breeds the best and worst breeding bulls belong to. The research revealed that 18% of bulls had genetic superiority at controlled farms (9% - Holstein breed, 6% - Yaroslavl crossbreeding bulls, 3% - Mikhailovsky type’s bulls), a negative value - 24% including 9% - Yaroslavl crossbreeding bulls, 9% - Mikhailovsky type’s bulls and 6% - Holstein bulls. A comparative evaluation of the two methods showed a high reliable positive correlation between results of Mikhailovsky type bulls and Yaroslavl crossbreeding bulls equal to 0.82 and 0.56, respectively, which indicates a high reliability of the method of genetic superiority index, which can be used to evaluate bulls during crossbreeding. It is possible to increase the genetic potential of herds by excluding producers with a negative genetic index. The obtained results are recommended to be used when mating bulls and for development of breeding programs for individual herds or entire population