Selection Of Bulls Research Articles

Delineating marker genotypes for higher reproduction performance to aid in selection of Murrah bulls

Unraveling the genetic variability of performance traits is the key basis of selection in farm animals. Murrah is a predominant milch breed of India, efforts were being made in the past to select them for higher production, which is negatively related with the fertility. Keeping this fact in mind and to select the animals having optimum production and fertility performance, present study was conducted to validate suitable markers and the association of their allelic variation with the fertility traits in Murrah buffaloes. Study was conducted on 280 Murrah buffaloes to explore SNPs in SPEF2 gene and their association with sire conception rate (SCR), conception rate (CR) and weight at birth of Murrah bulls. Results revealed that SNP C168T of SPEF2 gene with genotype CC was found to have non-significant but higher CR and SCR in comparison to CT and TT genotype. Although no significant association of the identified SNPs could be established with bull fertility traits, a further study with a large number of samples could make the differences due to genotypes a significant effect and can be used as an aid for early selection of high fertile Murrah bulls

PSIII-15 Feeding patterns of yearling Angus bulls based on feed efficiency metrics

Abstract The study objective was to determine how feeding behavior relates to feed efficiency in yearling Angus bulls at the Cal Poly Bull test. Bulls (n = 102) were housed in four pens sorted according to initial body weight (BW; 460 ± 35, 407 ± 15, 374 ± 20, 323 ± 30; mean kg ± SD), resulting in 24 to 28 bulls/pen. Feeding behavior was monitored using an electronic feeding system (SmartFeed, C-Lock, Inc.) during an 85-d feed efficiency test. Four feeders in each pen were filled twice daily at approximately 0630 h and 1700 h. The number of visits to the feed bunk, visit duration, total feeding time, and hourly feed intake were determined from data collected from the feeding system. These data were summarized by hour in a 24-h period, across the 85-d period. Bulls were retrospectively classified into a high feed efficiency group (HIFE) and low feed efficiency group (LOFE) based on an assessment of their summed residual feed intake rank and their feed:gain ratio rank. Within each pen, 5 HIFE and 5 LOFE bulls were selected, resulting in 20 bulls/treatment used for the final analyses. Data were analyzed using the MIXED procedure in SAS 9.4. The model included the fixed effects of feed efficiency group (HIFE vs LOFE), hour (0 to 24), and the feed efficiency group × hour interaction. Bull within pen was considered a random effect and hour a repeated measure. LOFE bulls visited the bunk more frequently throughout the day during the entire testing period (P = 0.04). Differences between feed efficiency groups depended on hour and most differences were observed within 3 h of fresh feed delivery (P ≤ 0.02). A feed efficiency group × hour interaction (P < 0.001) indicated that LOFE bulls had longer feed bunk visit durations predominantly between fresh feed deliveries (P ≤ 0.048). LOFE bulls spent more time feeding throughout the entire day (P = 0.003) when compared with HIFE bulls. Feeding duration per hour was longer for LOFE bulls during the post-morning feeding period (7-h duration) and post-evening feeding period (4-h duration; P ≤ 0.045). More feed was consumed by LOFE bulls throughout the day (P < 0.001), particularly during the post-morning feeding period (P ≤ 0.05). Overall, bulls exhibiting decreased feed efficiency had different feeding behavior patterns in all behavioral categories than their more feed efficient counterparts, especially around feed delivery. Thus, more active bulls at the feed bunk were less feed efficient, and this behavioral pattern may be an important consideration in bull selection.

The Effectiveness of Using Bulls With Increased Immune Response in Terms of Milk Yield, Milk Contents, and Somatic Cell Count in Polish Holstein-Friesian Cows

Abstract The dairy cattle industry has witnessed significant advancements in production traits, including milk yield, reproduction, and health, through decades of breeding efforts. Despite these improvements, cow health and milk hygiene remain essential. High immune response (HIR) technology identifies cattle with optimized immune responses, enabling the selection of bulls with high immune responses for breeding. Studies indicate that HIR-based breeding improves animal health without compromising production traits. This study aimed to assess the effectiveness of bulls with a high immune response in improving milk yield, milk contents, and somatic cell count in the milk of Polish Holstein-Friesian cows. A total of 11,509 cows of the Polish Holstein-Friesian breed were used. Among those, 1,773 animals were the offspring of HIR bulls, including 926 first-generation offspring (called I50 group) and 847 second-generation offspring (I25 group). There were 9,736 animals unrelated to HIR bulls (I0 group). Selected production and functional traits were analyzed. The results show that cows with higher kinship to HIR bulls showed increased milk yield. However, their milk exhibited lower fat, protein, and casein content. A favorable impact of HIR bulls was demonstrated by the decrease in somatic cell count in their offspring’s milk compared to the milk of cows from the I0 group. This research contributes valuable insights into the potential benefits of using HIR bulls in dairy cattle breeding programs, emphasizing the importance of balancing production traits with health considerations.

Evaluation of hormones as candidate early biomarkers of Holstein bull performance around the first semen collection at artificial insemination centres

AbstractArtificial insemination (AI) centres select bulls as calves according to their genetic breeding values and raise them until the first semen collection; yet, a high dropout rate of reared bulls is a problem for AI centres. Potential hormonal indicators of bull sexual maturation (cortisol, dehydroepiandrosterone (DHEA), testosterone, oestradiol, insulin‐like growth factor 1 (IGF‐1)) were observed and evaluated in relation to the performance parameters to perhaps identify candidate biomarkers allowing an early selection of bulls as suitable sires. Blood samples from 102 German Holstein calves at 4 ± 1, 8 ± 1 and 12 ± 2 months of age from six AI centres were analysed using validated immunoassays for cortisol, DHEA, testosterone, oestradiol and IGF‐1. Semen analyses included native and thawed diluted semen. Bulls were classified at the first semen collection into groups with good versus poor performance (GP vs. LP). After 2 years, the subsequent differentiation was done in high (HPP), medium (MPP) and low performance persistency (LPP). Age at first semen collection was an important factor for sperm quality. Cortisol concentrations decreased with age, but the cortisol/DHEA ratio decreased with age only in GP bulls (p < .05). Oestradiol and testosterone concentrations both correlated with libido behaviour (p < .05). Testosterone and IGF‐1 concentrations were higher at the time of first semen collection in GP bulls and increased with age (p < .05). In conclusion, testosterone and IGF‐1 concentrations at first semen collection are associated with performance at first semen collection and future performance persistency, and might be useful early biomarkers for consistent sperm producing bulls on AI centres.

Validation of the Indigenous Technical Knowledge of Cattle Pastoralists of Andhra Pradesh and Telangana, India

Indigenous technical knowledge (ITK) of livestock breeding is often tacit and not necessarily expressed in conventional forms of scientific research and documentation. Indigenous livestock breeding systems rely mostly on qualitative traits than pure quantitative qualities. Qualitative traits are difficult to measure and most of the indigenous knowledge systems are in forms of qualitative traits. The lack of documentation and predominant qualitative nature makes it difficult to validate the ITK related to livestock breeding. In this context a study was conducted to examine the traditional breeding practices associated with two heritage cattle breeds of the Deccan Plateau region of India. The study examines the criteria used for selection of the breeding bulls of the indigenous Poda Thurpu and Nallmala-Pasa/Kamma, cattle breeds native to the study area. Results of the study identifies fourteen traits specific to breeding bulls and four traits that are generic to the breeding stock/cows. These traits/characteristics are ‘deemed desirable’ by the local cattle breeders for the ‘heritage breeds’, believed to have been bred and managed by them for generations. Observations of the present study supports the notion that traditional breeders of heritage breeds lay more emphasis on qualitative traits (ability to warding-off predators, fending off-springs, coat colour and texture, gait of the animal, temperament, and response and obedience to instructions of the master) than quantitative traits. It was found that local breeders give significant importance to the fertility of bovine bulls than cows. Breeding bulls are meticulously chosen with extreme caution and care, following a very long and meticulous selection process that could last for four years. Traditionally local cattle breeders of the study follow open nucleus breeding system for breeding and are strictly against promotion of inbreeding among their cattle herds. Only men are involved in cattle breeding in the study area and women usually stay away.

Community-based breeding programs can realize sustainable genetic gain and economic benefits in tropical dairy cattle systems.

Implementing an appropriate breeding program is crucial to control fluctuation in performance, enhance adaptation, and further improve the crossbred population of dairy cattle. Five alternative breeding programs (BPs) were modeled considering available breeding units in the study area, the existing crossbreeding practices, and the future prospects of dairy research and development in Ethiopia. The study targeted 143,576 crossbred cows of 54,822 smallholder households in the Arsi, West Shewa, and North Shewa zones of the Oromia Region, as well as the North Shewa zone of the Amhara Region. The alternative BPs include conventional on-station progeny testing (SPT), conventional on-farm progeny testing (FPT), conventional on-station and on-farm progeny testing (SFPT), genomic selection (GS), and genomic progeny testing (GPT). Input parameters for modeling the BPs were taken from the analysis of long-term data obtained from the Holetta Agricultural Research Center and a survey conducted in the study area. ZPLAN+ software was used to predict estimates of genetic gain (GG) and discounted profit for goal traits. The predicted genetic gains (GGs) for milk yield (MY) per year were 34.52 kg, 49.63 kg, 29.35 kg, 76.16 kg, and 77.51kg for SPT, FPT, SFPT, GS, and GPT, respectively. The GGs of the other goal traits range from 0.69 to 1.19 days per year for age at first calving, from 1.20 to 2.35 days per year for calving interval, and from 0.06 to 0.12 days per year for herd life. Compared to conventional BPs, genomic systems (GPT and GS) enhanced the GG of MY by 53%-164%, reduced generation interval by up to 21%, and improved the accuracy of test bull selection from 0.33 to 0.43. The discounted profit of the BPs varied from 249.58 Ethiopian Birr (ETB, 1 USD = 39.55696 ETB) per year in SPT to 689.79 ETB per year in GS. Genomic selection outperforms SPT, SFPT, and FPT by 266, 227%, and 138% of discounted profit, respectively. Community-based crossbreeding accompanied by GS and gradual support with progeny testing (GPT) is recommended as the main way forward to attain better genetic progress in dairy farms in Ethiopia and similar scenarios in other tropical countries.

92 Factors influencing bull selection in Illinois beef producers: Analysis of retained and non-retained ownership producers

Abstract The objective was to understand decision-making factors for bull selection of producers participating in the Illinois Performance Tested (IPT) bull sale. The IPT bull sale has served Illinois beef producers for the last 54 yr offering around 50 bulls annually. A comprehensive survey targeted a diverse group of beef producers that had previously attended the IPT bull sale. The survey was developed through Qualtrics and provided to producers via email. The survey consisted of 40 questions based on four categories: farm location, herd demographics, bull selection criteria, and feedback from previous experiences at the IPT bull sale. There were a variety of question types including multiple choice, select all that apply, open-ended, ranking of importance, and select on a scale from one to ten. Specific responses on bull selection criteria focused on expected progeny differences and functional traits. Survey results were grouped based on whether producers retained ownership of feedlot cattle; regularly retained ownership (RET; n = 12) and never retained ownership (NRET; n = 15). Data were analyzed with the MIXED and GLIMMIX procedures of SAS 9.4. For RET and NRET producers, there were no observed differences in mature cow body weight and herd size (P ≥ 0.42). Most producers responded that they calved in March and April. Producer groups did not differ (P = 0.99) in the percentage of respondents retaining replacement heifers, as 66% of RET and NRET producers retained replacements. However, RET producers tended to be more likely (P = 0.07) to regularly sell freezer beef. Specifically, 75% of RET producers regularly sell freezer beef compared with 13% of NRET producers. Additionally, RET producers tended to prioritize (P = 0.1) carcass trait expected progeny differences in bull selection more than NRET producers (66 vs 33%, respectively). There was no difference (P = 0.2) in the percentage of respondents that selected the weaning weight expected progeny difference in their top three traits. However, NRET producers were much more likely (P < 0.01) to prioritize yearling weight expected progeny difference in their bull selection decisions. Specifically, 66% of RET producers used yearling weight expected progeny difference in their bull selection compared with 0% of NRET producers. Lastly, there was no difference (P = 0.61) in the percentage of respondents who included docility in their top three functional traits. In conclusion, bull buyers at the IPT bull sale that regularly retain ownership of feedlot cattle were more likely to prioritize expected progeny differences for yearling weight and carcass traits while functional traits priorities were similar to producers that did not retain ownership of feedlot cattle.

Population structure and identification of genomic regions associated with productive traits in five Italian beef cattle breeds

Italy has a long history in beef production, with local breeds such as Marchigiana, Chianina, Romagnola, Maremmana, and Podolica which produce high-quality meat. Selection has improved meat production, precocity, growth ability and muscle development, but the genetic determinism of such traits is mostly unknown. Using 33K SNPs-data from young bulls (N = 4064) belonging to these five Italian breeds, we demonstrated that the Maremmana and Podolica rustic breeds are closely related, while the specialised Marchigiana, Chianina, and Romagnola breeds are more differentiated. A genome-wide association study for growth and muscle development traits (average daily gain during the performance test, weight at 1 year old, muscularity) was conducted in the five Italian breeds. Results indicated a region on chromosome 2, containing the myostatin gene (MSTN), which displayed significant genome-wide associations with muscularity in Marchigiana cattle, a breed in which the muscle hypertrophy phenotype is segregating. Moreover, a significant SNP on chromosome 14 was associated, in the Chianina breed, to muscularity. The identification of diverse genomic regions associated with conformation traits might increase our knowledge about the genomic basis of such traits in Italian beef cattle and, eventually, such information could be used to implement marker-assisted selection of young bulls tested in the performance test.

Effects of Various Non-genetic Factors on Fertility Traits in Murrah Bulls in an Organized Herd

Background: In a herd going through improvement by selective breeding, bulls contribute more than half of the genetic gain due to higher selection intensity and wider coverage through AI. On the other side, meritorious sires might have a lower fertility due to various reasons which would render them less fit in their contribution to genetic improvement. Thus dairy buffalo breeders must find a delicate balance between production and reproduction superiority for selection of sires, for which an accurate assessment of genetic and non-genetic component of conception is essential. Methods: Present study was conducted on thirty five years data comprising of 5349 AI records on 1302 Murrah buffaloes using 86 bulls maintained and semen analysis of cryopreserved semen samples of 130 Murrah maintained at ICAR-National Dairy Research Institute Karnal were analyzed to study bull conception rate and sperm quality traits. Data were classified into four periods; four seasons of AI viz., Summer (April-June), rainy (July-September), autumn (October-November), winter (December-March); five parity (first, second, third, fourth, fifth and above) and five female AI number (1,2,3,4 and ³ 5 AI) to study the conception rate. Age at freezing (Years), period of freezing and season of freezing were analysed to observe their effects on semen quality traits. Mixed model analysis (SAS 9.3) and the analysis of variance were used to see the effects of various factors on conception rate as well as on semen quality parameters. Result: The analysis of variance revealed that period of AI and season of AI had significant (P less than 0.05) effect on conception rate while parity and female AI number were not found to affect the conception rate of bulls. For seminal parameters, acrosome integrity and HOST were significantly affected by age at freezing. Season affected all the semen quality traits while the effect of period of freezing was found to be non-significant for all the traits. Over all autumn season was found to be most suitable with respect to better seminal parameters. Considering season of AI, rainy season (July-September) had the lowest conception rate. The overall conception rate (%) in the study was 38.43±0.99; where Sires showed a wide variation for conception rate ranging from 20.00% to 60.46%. Concluding with the fact that there exists variation among bull fertility that can be utilized for not only herd conception rates but also be used as a criteria for bull selection and evaluation.

Bull Breeding Soundness Assessment Using Artificial Neural Network-Based Predictive Models

For years, efforts have been devoted to establishing an effective bull breeding soundness evaluation procedure; usual research on this subject is based on bull breeding soundness examination (BBSE) methodologies, which have significant limitations in terms of their evaluation procedure, such as their high cost, time consumption, and administrative difficulty, as well as a lack of diagnostic laboratories equipped to handle the more difficult cases. This research focused on the creation of a prediction model to supplement and/or improve the BBSE approach through the study of two algorithms, namely, clustering and artificial neural networks (ANNs), to find the optimum machine learning (ML) approach for our application, with an emphasis on data categorization accuracy. This tool was designed to assist veterinary medicine and farmers in identifying key factors and increasing certainty in their decision-making during the selection of bulls for breeding purposes, providing data from a limited number of factors generated from a deep pairing study of bulls. Zebu, European, and crossbred bulls were the general groupings. The data utilized in the model’s creation (N = 359) considered five variables that influence improvement decisions. This approach enhanced decision-making by 12% compared to traditional breeding bull management. ANN obtained an accuracy of 90%, with precision rates of 97% for satisfactory, 92% for unsatisfactory, and 85% for bad. These results indicate that the proposed method can be considered an effective alternative for innovative decision-making in traditional BBSE.

142 Genotype-By-Environment Interactions in Dairy Cattle Raised in California and New England

Abstract Genotype-by-environmental interactions (G x E) have been reported to cause sire reranking in dairy populations. However, the effects of such interactions are not included in the current US national dairy genetic evaluation. Phenotypes collected from animals across the country are considered the same trait, disregarding interactions between genetic effects and region or other environmental factors. Variations in production systems may interact with the genotypes of the animals, leading to distinct phenotypes. Separating data into regions could change decision-making on bull selection, which is the most important step of a breeding program. The goal of this study is to evaluate the extent of genotype-by-environment interaction between the state of California and the region of New England in the US Holstein Population. Data from Holstein cows in the aforementioned regions collected from 2010 to 2020 were provided by the Council on Dairy Cattle Breeding. The genetic evaluation models used for the national evaluation were modified to account for New England and California phenotypes as separated yet correlated traits. The mixed model accounted for additive genetic, sire-by-herd interaction, and permanent environmental effects as random, and for the management group, age of parity, birth year, and parity as fixed effects. In some scenarios, sire-by-herd interaction and permanent environment were removed due to convergence problems. Variance components were estimated using AIREML under the Method R procedure. Such a method allows computing variance components for large databases by splitting the data into several random groups. Ten random samples of data containing 100,000 records were used for each analysis. The scenarios included single trait for each state, single trait with both states, and two-trait with separated states. Breeding values from the top 100 bulls in each region were compared with evaluate potential sire reranking. Heritabilities varied across regions for all three traits (Table 1). California presented lower heritability than New England across methods. The genetic correlations on the two-trait analysis averaged at 0.96, 0.92, and 0.95 for yield, fat, and protein, respectively. The Spearman correlation coefficient between breeding values of the bulls with more than 200 daughters was 0.87 for milk yield, suggesting that the reranking is unimportant. The genetic correlations suggested that GxE between the two regions is small and that the traits should not be split in the current genetic evaluation. In conclusion, no critical effect of genotype-by-environment interaction was observed, even though top bulls may differ across regions. The next step of this project is to evaluate GxE for somatic cell score and to include genomic information in the evaluations. Finally, a genome-wide association study across the two regions will be performed to investigate changes in genomic regions associated with the phenotypes.

Production systems and breeding practices of Begaria cattle breed as input for a community-based breeding program

This study aimed to describe the production systems and breeding practices of Begaria cattle breeds as a resource for community-based conservation and breeding program. A semi-structured questionnaire and focus group discussions were employed to identify and describe the breeding practice of the farmer. Three kebeles: Almahal, Fanguso, and Mankush were considered for the study. The data were analyzed using R software. Cattle were kept for a variety of reasons, including milk, breeding, meat, cash, and saving. It was typical throughout the study area to see herd mixing and keeping together (4.7 ± 0.33 herds on average), herd movement during the dry season, and breeding bull sharing (1.9 ± 1.55 shared bulls). During the summer season, cattle rearing in the areas was hindered by feed and water shortages. The breed's major reproduction constraints were abortion (24 %), repeat breeding (19), and calf mortality (14). The primary reason for keeping Begaria cattle was for milk (29 %), cash (26), meat (22), and breeding (0.22). The average age at first calving (AFC), calving interval (CI) and milk yield per day of the breed were 41.5 ± 1.63, 16.0 ± 0.43 months, and 3.2 ± 0.12 L respectively. The average age of breeding bull selection was 3 ± 0.1 years, and it was based on several criteria, including their phenotype, growth, and white coat colour. Based on the current findings, it is recommended that a multi-trait selection program be designed with full stakeholder participation.

Genetic analysis for semen quality traits in buffalo bulls.

This study was attempted to estimate the genetic parameters of semen quality traits in buffalo bulls. The study data consisted of 10975 ejaculates from 45 Murrah buffalo bulls (aged 24-72months) used for breeding program during year 2010 to 2020. Semen quality traits (ejaculate volume, concentration of sperm, mass activity, initial and post-thaw motility, number of sperms per ejaculate, motile sperm number and discard rates) were studied. It was observed that average ejaculate volume was 2.82 ± 1.45mL with mean concentration of 1040.12 ± 523.26 million/mL. Higher heritability was observed for number of sperms per ejaculate, number of motile sperm and sperm concentration. Significant phenotypic correlation was obtained between volume and number of sperms per ejaculate as well as volume and number of motile sperms. Likewise, significant phenotypic correlation was evident between sperm concentration with sperm number per ejaculate. Highest phenotypic correlation was obtained between sperm count per ejaculate and motile sperm count. Estimated genetic trends showed significant change in volume and motile sperm number. In conclusion, this study ascertains that genetic parameters of semen traits can be considered during the selection of buffalo bulls in breeding program.

Practical applications of genomics

Genomic testing serves multiple functions for beef cattle popu­lations. Since their inception in the late 2000s, genomic tests have been critical tools for detecting mutations that cause genetic defects, parentage testing, and improving the quality of genetic predictions. Sire selection is one of the most conse­quential decisions that commercial operations make. This chal­lenge is compounded by the relatively low levels of information available on the unproven herd sires that commercial herds purchase. Selection tools in the form of Expected Progeny Dif­ferences (EPDs) allow commercial operations to reduce the risk involved in sire selection. EPDs isolate the genetic component of economically-relevant traits and increase selection accuracy. While parent average EPDs are more reliable than phenotypic selection, unproven sires can still experience significant EPD shifts as more information becomes available. Genomic testing enhances the EPDs for unproven and low-accuracy sires. These increases in accuracy are equivalent to approximately a calf crop’s worth of records in a genomic evaluation (from 10 to 30 phenotypes depending on the trait). Nearly all breed associa­tions calculate genomically-enhanced EPDs, making their use imperative for commercial operations. Beyond bull selection, opportunities exist for commercial producers to utilize genom­ics for heifer selection and marketing terminal animals.

Seroepidemiological study of bovine alphaherpesvirus 1 in the dairy cattle herds of Addis Ababa, Ethiopia.

Bovine alphaherpesvirus 1(BoHV-1) causes respiratory disease, abortions, and genital disorders in cattle. Although BoHV-1 has been known to cause severe economic damage to the dairy industries, little is known about its epidemiology in dairy cattle of Addis Ababa, Ethiopia. The present study aimed to determine the seroprevalence and the risk factors associated with the occurrence of BoHV-1. A total of 369 blood samples from 115 dairy herds were collected using a proportional stratified random sampling method and examined antibodies against BoHV-1 using ELISA test. A questionnaire survey was done to gather information related to farm demographics and reproductive disorders. Univariate and multivariate mixed-effect logistic regression analyses were used. The overall seroprevalence of BoHV-1 was detected in 21 % (95%CI: 17-25%) and 32 % (95%CI: 24-42 %) at animal and herd levels, respectively. A multivariable mixed effect logistic regression model revealed that adult cattle had 14 times (OR = 14.32; 95 % CI: 2.53-81.5; P=0.003) more likely to increase the risk of being BoHV-1 seropositive than young cattle. Purchased cattle had 4 times (OR = 4.15; 95 % CI: 1.36-12.66, P=0.012) more likely to increase the risk of being BoHV-1 seropositive than homebred cattle. The risk of being BoHV-1 seropositive was 195 times higher in herds using bulls (OR = 195.51; 95 % CI: 3.62-1056.51; P=0.010) than in herds using artificial insemination only for breeding. BoHV-1 seropositivity was significantly associated with cows that had a history of abortion (OR = 6.89; 95 % CI: 1.97-22.76; P=0.002), retained placenta (OR = 3.26; 95 % CI: 1.32-8.07; P=0.010), and repeat breeding (OR = 3.64; 95 % CI: 1.08-12.18; P=0.036). This study demonstrated the gaps in the selection of BoHV-1 free bulls for breeding as well as limited farm biosecurity practices. Thus, awareness creation for dairy farmers on good farm biosecurity practices including vaccination should be initiated.

Genomic diversity and population structure of the Czech Holstein cattle

Holstein-Friesian (HF) is a cosmopolitan breed distributed in more than 150 countries. It represents a large metapopulation with intensive gene flow, realised mainly through artificial insemination and the intensive use of the popular "star" bulls. The breed is known for its superiority in milk yield, production efficiency and black and white coat color. In contrast to the enormous size of the census population, which exceeds nine million animals in the U.S. alone, the genetic diversity of this highly commercialised breed is surprisingly low, necessitating genetic monitoring, especially of subpopulations in individual countries. Our main objective in this study was to analyze genomic diversity (estimated by genomic inbreeding and effective population size) and population structure (relationship to other subpopulations) of the subpopulation from the Czech Republic and, based on high-throughput SNP array genotypes. We analysed 2178 animal samples (32,865 autosomal SNP) from 12 subpopulations and the Simental cattle breed (98 animals), which represents an outlier population. Czech bulls showed high genomic inbreeding (FROH>2Mb=0.133), well above the inbreeding level of Czech cows (FROH>2Mb=0.091), with particularly high recent inbreeding (ROH>8Mb). Unexpectedly, the estimated effective population size (NeLD) was relatively high, ranging from 202 (GONE) to 283 (NeEstimator v2), depending on the estimation algorithm. Our phylogenetic analyses showed that the Czech HF belonged to the "core metapopulation HF ", together with Belgian, British, Canadian, Dutch, French, German, and USA subpopulations, which was separated from the Swiss, Irish, and Croatian subpopulations. We also showed that Czech AI bulls differed slightly from cows, especially in genes affecting meat and carcass. Our results have defined the population structure of the Czech HF and indicate the potential problems of increased inbreeding due to selection of AI bulls.

Establishment of a repertoire of fertility associated sperm proteins and their differential abundance in buffalo bulls (Bubalus bubalis) with contrasting fertility

Sperm harbours a wide range of proteins regulating their functions and fertility. In the present study, we made an effort to characterize and quantify the proteome of buffalo bull spermatozoa, and to identify fertility associated sperm proteins through comparative proteomics. Using high-throughput mass spectrometry platform, we identified 1305 proteins from buffalo spermatozoa and found that these proteins were mostly enriched in glycolytic process, mitochondrial respiratory chain, tricarboxylic acid cycle, protein folding, spermatogenesis, sperm motility and sperm binding to zona pellucida (p < 7.74E−08) besides metabolic (p = 4.42E−31) and reactive oxygen species (p = 1.81E−30) pathways. Differential proteomic analysis revealed that 844 proteins were commonly expressed in spermatozoa from both the groups while 77 and 52 proteins were exclusively expressed in high- and low-fertile bulls, respectively. In low-fertile bulls, 75 proteins were significantly (p < 0.05) upregulated and 176 proteins were significantly (p < 0.05) downregulated; these proteins were highly enriched in mitochondrial respiratory chain complex I assembly (p = 2.63E−07) and flagellated sperm motility (p = 7.02E−05) processes besides oxidative phosphorylation pathway (p = 6.61E−15). The down regulated proteins in low-fertile bulls were involved in sperm motility, metabolism, sperm-egg recognition and fertilization. These variations in the sperm proteome could be used as potential markers for the selection of buffalo bulls for fertility.

MAEL gene contributes to bovine testicular development through the m5C-mediated splicing

Knowledge of RNA molecules regulating testicular development and spermatogenesis in bulls is essential for elite bull selection and an ideal breeding program. Herein, we performed direct RNA sequencing (DRS) to explore the functional characterization of RNA molecules produced in the testicles of 9 healthy Simmental bulls at three testicular development stages (prepuberty, puberty, and postpuberty). We identified 5,043 differentially expressed genes associated with testicular weight. These genes exhibited more alternative splicing at sexual maturity, particularly alternative 3' (A3) and 5' (A5) splice sites usage and exon skipping (SE). The expression of hub genes in testicular developmental stages was also affected by both m6A and m5C RNA modifications. We found m5C-mediated splicing events significantly (p<0.05) increased MAEL gene expression at the isoform level, likely promoting spermatogenesis. Our findings highlight the complexity of RNA processing and expression as well as the regulation of transcripts involved in testicular development and spermatogenesis.

Innovative approaches to the development of dairy cattle breeding in the Kaluga region

The use of innovative approaches to the development of breeding cattle in the region has significantly increased and improved the productivity of animals. So, over the past 5 years, gross milk production has increased by 192 thousand tons or 171%, milk yield per cow by 2705 kg and amounted to 8745 kg in 2021. The breed composition of cows has changed, the Holstein breed with a specific gravity of about 80% has become the predominant breed of dairy cattle in the Kaluga region. The selection of bulls is aimed only at the bulls-leaders of the Holstein breed and their sons. IT technologies are actively used in the management of regional dairy cattle breeding in the region.

CORRELATED VARIABILITY OF DOMESTIC AND FOREIGN ASSESSMENT OF THE BREEDING VALUE OF BULLS

The purpose of the research was to determine the repeatability of estimates of the breeding value of bulls by offspring in foreign countries and in controlled herds in Ukraine. The study was conducted based on the results of native (by the method of calculated breeding value – CBV, n = 1093) and foreign (the best linear unbiased prediction – BLUP, n = 161) assessment of the breeding value of sires with a repeatability of more than 60% of ten dairy and double breeds, given in the catalogues of bulls for the reproduction of breeding cattle in 2003–2013. By breed affiliation, these 713 bulls are classified as Holstein, 92 – Ukrainian Black-and-White Dairy, 85 – Ukrainian Red- and-White Dairy, 59 – Ukrainian Red Dairy, 47 – Simmental, 40 – Angler, 36 – Swiss, 11 – Red Steppe, 7 – Red Danish, 3 – Lebedyn breeds. By country of birth (selection), the largest representation (439 bulls) had sires of native breeding, 235 bulls used in the specified period (or their sperm products) were imported from Canada, 154 – from Germany, 117 – from the USA, 37 – from Austria, 36 – from the Russian Federation, 20 – from Denmark, 19 – from Hungary, 17 – from the Netherlands, 7 – from Great Britain, 4 – from the Czech Republic, by 2 – from France, Latvia and Estonia and by one from Bulgaria and Lithuania. On each sire the information about the year and the method of evaluation by offspring, the number of daughters, herds and repeatability, average milk yield, the content and yield of milk fat and protein in daughter’s milk, the breeding value of bulls on these traits was taken into account. Prior to receiving an estimate for offspring in Ukraine, 161 sires were evaluated abroad.&#x0D; Correlation analysis established a statistically significant (P &lt; 0.001), but relatively low (27.8–51.7%) level of correlated variability of the breeding value of bulls and the average productivity of their daughters. On the yield, the correlation coefficient was 44.5 ± 2.71%, on the fat content – 51.7 ± 2.59%, protein content – 27.8 ± 3.30% and milk fat yield – 42.8 ± 2.74%. Consequently, the average milk production of daughters cannot be considered as a reliable criterion for assessing the genetic value of sires.&#x0D; The breeding value of sires by the milk yield of daughters closely correlates with that of milk fat and protein (97.3...97.9%) and reveals a low connection (-2.7...-7.8%) with their content, which confirms the natural antagonism of quantitative and qualitative traits of milk production. Consequently, selection on the basis of milk production should be carried out at independent levels with a low probability of obtaining bulls, which simultaneously improve quantitative and qualitative traits.&#x0D; Correlation analysis revealed a low and in most cases not reliable level of correlated variability of native and foreign estimates of the breeding value of bulls. On the yield, the repeatability of foreign and native assessment of the breeding value of sires was 33.6 ± 7.29% (P ˂ 0.001), by fat content – 13.0 ± 7.67% (P = 0.093), by milk fat yield – 8.6 ± 7.71%, by protein content – -0.1 ± 7.83% (P = 0.991), milk protein yield – 23.7 ± 7.61% (P = 0.002) and by the complex breeding index – 13.8 ± 7.66% (P = 0.074). Thus, the level of breeding value of sires determined abroad can be considered only as a preliminary one for their selection into native herds, which does not guarantee the corresponding breeding effect due to the different reaction rate in the interaction "genotype – environment". Quite reasonable so is the requirement of the native instruction on the selection of bulls concerning the mandatory reevaluation of imported bulls as well as sires, whose sperm products were purchased by import into Ukraine.