Risk Factor Analysis and Genetic Parameter Estimation for Pre-Weaning Mortality Traits in Boer, Spanish, and Crossbred Goat Kids

The objectives of this study were to evaluate fixed risk factors associated with PWM and to estimate genetic parameters for PWM. A total of 927 birth records from a mixed population of purebred and crossbred Boer and Spanish goats born between 2016 and 2023 at the International Goat Research Center (IGRC) were used for this study. Four binary traits were studied: D0-3 (death within 3 days after birth), D4-60 (death between 4 and 60 days), D61-90 (death between 61 and 90 days), and D0-90 (death within 90 days). Logistic regression models were used to evaluate the risk factors associated with PWM traits. Bayesian threshold models and Gibbs sampling were used to estimate the genetic parameters. Birth weight, season, litter size, sex, dam age, breed, and heterosis were found to be significantly associated with at least one of the PWM traits. Heritability estimates were 0.263, 0.124, 0.080, and 0.207, for D0-3, D4-60, D61-90, and D0-90, respectively. The genetic correlations between the studied traits ranged from 0.892 (D0-3 and D0-90) to 0.999 (D0-3 and D61-90). These results suggest that PWM in goats is influenced by both non-genetic and genetic factors and can be reduced by management, genetic selection, and crossbreeding approaches.

Androgen receptor signaling and pyrethroids: Potential male infertility consequences

Infertility is a global health concern inflicting a considerable burden on the global economy and a severe socio-psychological impact. Approximately 15% of couples suffer from infertility globally, with a male factor contribution of approximately 50%. However, male infertility remains largely unexplored, as the burden of infertility is mostly assigned to female people. Endocrine-disrupting chemicals (EDCs) have been proposed as one of the factors causing male infertility. Pyrethroids represent an important class of EDCs, and numerous studies have associated pyrethroid exposure with impaired male reproductive function and development. Therefore, the present study investigated the potentially toxic effects of two common pyrethroids, cypermethrin and deltamethrin, on androgen receptor (AR) signaling. The structural binding characterization of cypermethrin and deltamethrin against the AR ligand-binding pocket was performed using Schrodinger's induced fit docking (IFD) approach. Various parameters were estimated, such as binding interactions, binding energy, docking score, and IFD score. Furthermore, the AR native ligand, testosterone, was subjected to similar experiments against the AR ligand-binding pocket. The results revealed commonality in the amino acid-binding interactions and overlap in other structural parameters between the AR native ligand, testosterone, and the ligands, cypermethrin and deltamethrin. The estimated binding energy values of cypermethrin and deltamethrin were very high and close to those calculated for AR native ligand, testosterone. Taken together, the results of this study suggested potential disruption of AR signaling by cypermethrin and deltamethrin, which may result in androgen dysfunction and subsequent male infertility.

Contributions of seminal plasma proteins to fertilizing ability of bull sperm: A meta-analytical review

Seminal plasma is a dynamic, intricate combination of fluids from the testicles, epididymides, seminal vesicles, bulbourethral glands, and prostate, containing molecules that modulate sperm functions, post-fertilization events, and the female reproductive tract physiology. Significant variations in sperm parameters and fertility status of bulls relate to differences in the seminal plasma proteome. In this framework, a meta-analytical study was conducted examining 29 studies (published between 1990 and 2021) to ascertain the effects of seminal fluid proteins on parameters associated with bull fertility and the influence of distinct methodologies on such effects. Our results revealed that seminal proteins ameliorate sperm parameters, such as motility, integrity, capacitation, and fertilizing ability, and favours sperm protection. Seminal binder of sperm proteins and beta-defensin 126 highly favoured sperm protection when cells were collected from the epididymis by retrograde flux and analysed under room temperature conditions. Furthermore, seminal proteins improved the motility and quality of Bos taurus sperm collected by artificial vagina, mainly in the presence of heparin-binding proteins. The key limitations faced by this meta-analysis were the paucity of studies evaluating the effects of whole seminal fluid proteins and the limited number of studies conducted in vivo. In conclusion, the present meta-analytical study confirms that seminal proteins improve fertility-related parameters in the bovine species. However, methodological strategies used by authors are diverse, with distinct endpoints and methods. Thus, the translational aspects of seminal plasma research should be taken into consideration to precisely define how seminal proteins can be harnessed to advance reproductive biotechnology.

Harnessing the value of reproductive hormones in cattle production with considerations to animal welfare and human health

The human population is ever increasing while the quality and quantity of natural resources used for livestock production decline. This calls for improved product efficiency and the development of improved and sustainable cattle production methods to produce higher quality products to satisfy the demands of both the modern and transient world. The goal of this review was to summarize the interactions, challenges, and opportunities in cattle production relating to their endocrine system, and how reproductive hormones and others impact economically important traits, animal welfare, and human health. A comprehensive literature search was conducted with a focus on analysis of natural hormones and the use of exogenous hormone administration for reproduction, growth, and development of beef and dairy cattle. Hormones regulate homeostasis and enhance important traits in cattle, including fertility, growth and development, health, and the production of both meat and milk products. Reproductive hormones such as testosterone, estradiol, progesterone, and related synthetics like trenbolone acetate and zeranol can be strategically utilized in both beef and dairy cattle production systems to enhance their most valuable traits, but the impact of these substances must account for the welfare of the animal as well as the health of the consumer. This scientific review provides a comprehensive analysis of the bovine endocrine system's impact on food animals and product quality which is vital for students, researchers, livestock producers, and consumers. Although important advances have been made in animal science and related technological fields, major gaps still exist in the knowledge base regarding the influence of hormones on the production and welfare of food animals as well as in the public perception of hormone use in food-producing animals. Filling these gaps through transformative and translational research will enhance both fundamental and applied animal science to feed a growing population.

Implications of sperm heat shock protein 70-2 in bull fertility

Heat shock protein 70 (HSP70) is one of the most abundant chaperone proteins. Their function is well documented in facilitating the protein synthesis, translocation, de novo folding, and ordering of multiprotein complexes. HSP70 in bovine consists of four genes: HSP70-1, HSP70-2, HSP70-3, and HSP70-4. HSP70-2 was found to be involved in fertility. Current knowledge implicates HSP70-2 in sperm quality, sperm capacitation, sperm–egg recognition, and fertilization essential for bull reproduction. HSP70-2 is also involved in the biological processes of spermatogenesis, as it protects cells from the effects of apoptosis and oxidative stress. Fertilization success is not only determined by the amount of sperm found in the female reproductive tract but also by the functional ability of the sperm. However, subfertility is more likely to be associated with changes in sperm molecular dynamics not detectable using conventional methods. As such, molecular analyses and omics methods have been developed to monitor crucial aspects of sperm molecular morphology that are important for sperm functions, which are the objectives of this review.

Identification of biomarkers for bull fertility using functional genomics

Prediction of bull fertility is critical for the sustainability of both dairy and beef cattle production. Even though bulls produce ample amounts of sperm with normal parameters, some bulls may still suffer from subpar fertility. This causes major economic losses in the cattle industry because using artificial insemination, semen from one single bull can be used to inseminate hundreds of thousands of cows. Although there are several traditional methods to estimate bull fertility, such methods are not sufficient to explain and accurately predict the subfertility of individual bulls. Since fertility is a complex trait influenced by a number of factors including genetics, epigenetics, and environment, there is an urgent need for a comprehensive methodological approach to clarify uncertainty in male subfertility. The present review focuses on molecular and functional signatures of bull sperm associated with fertility. Potential roles of functional genomics (proteome, small noncoding RNAs, lipidome, metabolome) on determining male fertility and its potential as a fertility biomarker are discussed. This review provides a better understanding of the molecular signatures of viable and fertile sperm cells and their potential to be used as fertility biomarkers. This information will help uncover the underlying reasons for idiopathic subfertility.

Sperm proteins ODF2 and PAWP as markers of fertility in breeding bulls

Low fertility is the single most important factor limiting livestock reproductive performance, adversely affecting the cattle industry and causing millions of dollars of economic loss. In the livestock industry, male fertility is of crucial importance for the reproductive performance of livestock. However, there is a lack of reliable biomarkers to predict bull fertility in artificial insemination service. The objective of this study was to identify sperm proteins as biomarkers for bull fertility. To discover candidate sperm quality biomarkers, sperm proteome profiling was conducted in extreme high- and extreme low-fertile bulls selected from a pool of 1000 AI sires with varied fertility. Thirty-two differentially expressed proteins were identified. Among them, high levels of sperm outer dense fiber of sperm tails 2 (ODF2) and post-acrosomal assembly of sperm head protein (PAWP/WBP2NL) represented the most extreme differences in quantity between high- and low-fertility bulls. Protein immunodetection and flow cytometry used to validate these putative fertility markers in a combined cohort of 154 AI sires. Both ODF2 and PAWP correlated significantly with fertility. In conclusion, ODF2 and PAWP can be used to assess semen quality and predict sire fertility.

PSXV-15 Application of a survey instrument for understanding pain management practices associated with equine assisted activities and therapy horses

Equine assisted activities and therapy (EAAT) is a popular therapy option for physical, psychological, and cognitive disorders. A critical component of this treatment option is the horse, and while research has reported the benefits for human participants, there is a lack of knowledge concerning the therapy horse due to limited research documenting the impact of these activities. Nevertheless, those that manage these animals understand the demanding activities placed on the therapy horse, and thus, can play a vital role in educating those new to the industry. Therefore, the objective of this study was to utilize a survey instrument to document management activities associated with pain for the therapy horse. An 11 forced-choice question survey was developed and sent out to 97 EAAT programs within the U.S. Participation was available online for a total of four months. Response rate was 31% (n = 30). From the respondents, 50% answered +46 yrs old for age, 70% answered +15 yrs equine experience, and 60% answered +11 yrs working in EAAT. The most popular answer for number of horses in the respondents’ EAAT program was >11 horses (53%), and as to the horses in the program, 50% answered they had >7 geriatric horses. The majority of the respondents answered “definitely yes” to having functionally lame horses used regularly in their programs (53%) and having experience with pain management practices associated with orthopedic (50%) and gastrointestinal (67%) conditions. The majority of the programs used vital sign measurements (67%), facial expressions (73%), and behavioral changes (87%) to detect equine pain. In conclusion, EAAT horses appear to commonly need healthcare practices for pain management suggesting further research is needed in precision medicine and animal welfare. In addition, educational programs covering pain management practices for individuals going into the EAAT industry would assist in ensuring the welfare of these animals.

Sperm Functional Genome Associated With Bull Fertility

Bull fertility is an important economic trait in sustainable cattle production, as infertile or subfertile bulls give rise to large economic losses. Current methods to assess bull fertility are tedious and not totally accurate. The massive collection of functional data analyses, including genomics, proteomics, metabolomics, transcriptomics, and epigenomics, helps researchers generate extensive knowledge to better understand the unraveling physiological mechanisms underlying subpar male fertility. This review focuses on the sperm phenomes of the functional genome and epigenome that are associated with bull fertility. Findings from multiple sources were integrated to generate new knowledge that is transferable to applied andrology. Diverse methods encompassing analyses of molecular and cellular dynamics in the fertility-associated molecules and conventional sperm parameters can be considered an effective approach to determine bull fertility for efficient and sustainable cattle production. In addition to gene expression information, we also provide methodological information, which is important for the rigor and reliability of the studies. Fertility is a complex trait influenced by several factors and has low heritability, although heritability of scrotal circumference is high and that it is a known fertility maker. There is a need for new knowledge on the expression levels and functions of sperm RNA, proteins, and metabolites. The new knowledge can shed light on additional fertility markers that can be used in combination with scrotal circumference to predict the fertility of breeding bulls. This review provides a comprehensive review of sperm functional characteristics or phenotypes associated with bull fertility.

Advancing Semen Evaluation Using Lipidomics

Developing a deeper understanding of biological components of sperm is essential to improving cryopreservation techniques and reproductive technologies. To fully ascertain the functional determinants of fertility, lipidomic methods have come to the forefront. Lipidomics is the study of the lipid profile (lipidome) within a cell, tissue, or organism and provides a quantitative analysis of the lipid content in that sample. Sperm cells are composed of various lipids, each with their unique contribution to the overall function of the cell. Lipidomics has already been used to find new and exciting information regarding the fatty acid content of sperm cells from different species. While the applications of lipidomics are rapidly evolving, gaps in the knowledge base remain unresolved. Current limitations of lipidomics studies include the number of available samples to analyze and the total amount of cells within those samples needed to detect changes in the lipid profiles across different subjects. The information obtained through lipidomics research is essential to systems and cellular biology. This review provides a concise analysis of the most recent developments in lipidomic research. This scientific resource is important because these developments can be used to not only combat the reproductive challenges faced when using cryopreserved semen and artificial reproductive technologies in livestock such as cattle, but also other mammals, such as humans or endangered species.

Functional attributes of seminal proteins in bull fertility: a systematic review

Proteomic approaches have been widely used in reproductive studies to uncover protein biomarkers of bull fertility. Seminal plasma is one of the most relevant sources of these proteins that may influence sperm physiology. Nonetheless, there are still gaps in existing knowledge in the functional attributes of seminal proteins. Thus, we reviewed the relationships between seminal plasma proteins and bull fertility by conducting a systematic review with data obtained from 71 studies. This review showed that the associations related to fertility improvement with the use of total seminal plasma proteins are still controversial. None of the studies explored the sperm fertilizing ability following these interactions. By contrast, the exposure to a single protein, such as osteopontin, binder of sperm proteins, and heparin binding proteins, can increment sperm motility, capacitation, and fertilizing ability by modulating intracellular calcium concentrations, removing lipids from sperm membranes, and regulating the acrosome reaction. Variations in protein analyses and the protein contents and their abundances between animals contributed to the difficulty of establishing protein biomarkers of fertilizing potential of the bull sperm. Indeed, the heterogenicity of methodologies was a limitation of this review. Standardized methods of seminal protein analyses, as well as sperm endpoints, may minimize such discrepancies. In conclusion, potential biomarkers of sperm parameters are still to be established. Future studies should evaluate protein isoforms and how they interact with sperm to ascertain their biological functions.

Comparative analysis of various step-dilution techniques on the quality of frozen Limousin bull semen

Background and Aim:

Indonesia has two National Artificial Insemination centers and 17 Regional Artificial Insemination Centers. The frozen semen production techniques differed between the centers, including the type of diluent and semen dilution technique. The aim of the research was to compare the quality of frozen Limousin bull semen diluted using different techniques.

Materials and Methods:

Semen was collected from three sexually mature Limousin bulls using an artificial vagina. Immediately after collection, the semen was evaluated macroscopically and microscopically. Semen that had >70% motile sperm and <20% sperm abnormality was divided into three tubes and diluted with skim milk-egg yolk (SMEY) using three different dilution techniques: One-step dilution (100% SMEY with 8% glycerol) at room temperature ([RT] 20°C until 25°C) two-step dilution (50% SMEY without glycerol at RT, stored at 5°C; and 50% SMEY with 16% glycerol after 1 h stored at 5°C); and three-step dilution (50% SMEY without glycerol at RT, stored at 5°C; and 50% SMEY with 16% glycerol added twice at 1 h and 1.5 h after being stored at 5°C). The diluted semen was loaded into 0.25 mL mini straws, equilibrated, and frozen using a freezing machine. Sperm motility, viability, membranes, DNA integrity, and concentrations of malondialdehyde (MDA) and aspartate aminotransferase (AST) enzymes were evaluated after thawing.

Results:

The results showed that there were no significant differences in sperm motility and DNA integrity between dilutions (p>0.05). However, sperm viability and membrane intactness of one-step dilutions were higher than those of three-step dilutions. The concentrations of MDA and AST enzymes of sperm in one-step dilutions were lower than those of three-step dilutions (p<0.05).

Conclusion:

It was concluded that the one-step-dilution technique was better than three-step dilution for cryopreservation of Limousin bull semen.

Cellular and Functional Physiopathology of Bull Sperm With Altered Sperm Freezability

The objective of this study was to ascertain the cellular and functional parameters as well as ROS related changes in sperm from bulls with varied sperm freezability phenotypes. Using principal component analysis (PCA), the variables were reduced to two principal components, of which PC1 explained 48% of the variance, and PC2 explained 24% of the variance, and clustered animals into two distinct groups of good freezability (GF) and poor freezability (PF). In ROS associated pathophysiology, there were more dead superoxide anion positive (Dead SO+) sperm in GF bulls than those in PF (15.72 and 12.00%; P = 0.024), and that Dead SO+ and live hydrogen positive cells (live H₂O₂+) were positively correlated with freezability, respectively (R² = 0.55, P < 0.0130) and (r_s = 0.63, P = 0.0498). Related to sperm functional integrity, sperm from PF bulls had greater dead intact acrosome (DIAC) than those from GF bulls (26.29 and 16.10%; P = 0.028) whereas sperm from GF bulls tended to have greater live intact acrosome (LIAC) than those from PF bulls (64.47 and 50.05%; P = 0.084). Sperm with dead reacted acrosome (DRAC) in PF bulls were greater compared to those in GF (19.27 and 11.48%; P = 0.007). While DIAC (R² = 0.56, P = 0.0124) and DRAC (R² = 0.57, P < 0.0111) were negatively correlated with freezability phenotype, LIAC (R² = 0.36, P = 0.0628) was positively correlated. Protamine deficiency (PRM) was similar between sperm from GF and PF bulls (7.20 and 0.64%; P = 0.206) and (r_s = 0.70, P = 0.0251) was correlated with freezability. Sperm characteristics associated with cryotolerance are important for advancing both fundamental andrology and assisted reproductive technologies across mammals.

Protein signatures of seminal plasma from bulls with contrasting frozen-thawed sperm viability

The present study investigated the seminal plasma proteome of Holstein bulls with low (LF; n = 6) and high (HF; n = 8) sperm freezability. The percentage of viable frozen-thawed sperm (%ViableSperm) determined by flow cytometry varied from -2.2 in LF to + 7.8 in HF bulls, as compared to the average %ViableSperm (54.7%) measured in an 860-sire population. Seminal proteins were analyzed by label free mass spectrometry, with the support of statistical and bioinformatics analyses. This approach identified 1,445 proteins, associated with protein folding, cell-cell adhesion, NADH dehydrogenase activity, ATP-binding, proteasome complex, among other processes. There were 338 seminal proteins differentially expressed (p < 0.05) in LF and HF bulls. Based on multivariate analysis, BSP5 and seminal ribonuclease defined the HF phenotype, while spermadhesin-1, gelsolin, tubulins, glyceraldehyde-3-phosphate dehydrogenase, calmodulin, ATP synthase, sperm equatorial segment protein 1, peroxiredoxin-5, secretoglobin family 1D and glucose-6-phosphate isomerase characterized the LF phenotype. Regression models indicated that %ViableSperm of bulls was related to seminal plasma peroxiredoxin-5, spermadhesin-1 and the spermadhesin-1 × BSP5 interaction (R2 = 0.84 and 0.79; p < 0.05). This report is the largest dataset of bovine seminal plasma proteins. Specific proteins of the non-cellular microenvironment of semen are potential markers of sperm cryotolerance.

Application of Proteomics to Identify Fertility Markers in Angus Bull Sperm

The goal of the study was to ascertain sperm proteins as fertility markers by identifying sperm proteins in Angus bull sperm using proteomics and validate the markers through comparative sperm biology between Angus and Holstein bulls for which there is reliable fertility data available. We aimed to determine proteins differentially expressed in sperm from Angus bulls with different fertility phenotypes. Two-dimensional differential gel electrophoresis with mass-spectrometry, functional gene clusters, canonical pathways and protein networks, using integrated discovery bioinformatics software and ingenuity pathway analysis were used to identify and analyze sperm proteome. We identified 80 proteins that were differentially expressed in sperm of our experimental population. Using computational biology approaches we demonstrated involvement of structural proteins such as outer dense fiber of sperm tails 2 and enzymes including kinases, and phosphatases having functions in essential pathways in glycolysis/gluconeogenesis and free scavenging. The results are significant because analyzed proteins in Angus sperm are determinants of fertility, gene-environment interactions, as well as potential biomarkers for animal breeding.

Amino Acids of Seminal Plasma Associated With Freezability of Bull Sperm

Sperm cryopreservation is an important technique for fertility management, but post-thaw viability of sperm differs among breeding bulls. With metabolites being the end products of various metabolic pathways, the contributions of seminal plasma metabolites to sperm cryopreservation are still unknown. These gaps in the knowledge base are concerning because they prevent advances in the fundamental science of cryobiology and improvement of bull fertility. The objective of this study was to test the hypothesis that seminal plasma amino acids are associated with freezability of bull sperm. To accomplish this objective, amino acid concentrations in seminal plasma from seven bulls of good freezability (GF) and six bulls of poor freezability (PF) were quantified using gas chromatography–mass spectrometry (GC–MS). Multivariate and univariate analyses were performed to identify potential freezability biomarkers. Pathways and networks analyses of identified amino acids were performed using bioinformatic tools. By analyzing and interpreting the results we demonstrated that glutamic acid was the most abundant amino acid in bull seminal plasma with average concentration of 3,366 ± 547.3 nM, which accounts for about 53% of total amino acids. The other most predominant amino acids were alanine, glycine, and aspartic acid with the mean concentrations of 1,053 ± 187.9, 429.8 ± 57.94, and 427 ± 101.3 nM. Pearson’s correlation analysis suggested that phenylalanine concentration was significantly associated with post-thaw viability (r = 0.57, P-value = 0.043). Significant correlations were also found among other amino acids. In addition, partial least squares-discriminant analysis (PLS-DA) bi-plot indicated a distinct separation between GF and PF groups. Phenylalanine had the highest VIP score and was more abundant in the GF groups than in the PF groups. Moreover, pathway and network analysis indicated that phenylalanine contributes to oxidoreductase and antioxidant reactions. Although univariate analysis did not yield significant differences in amino acid concentration between the two groups, these findings are significant that they indicate the potentially important roles of amino acids in seminal plasma, thereby building a foundation for the fundamental science of cryobiology and reproductive biotechnology.

Sperm cellular and nuclear dynamics associated with bull fertility

The objective of this study was to ascertain cellular characteristics and the dynamics of the sperm chromatin proteins protamine 1 (PRM1) and protamine 2 (PRM2) in the sperm of Holstein bulls having a different fertility status. Important sperm variables were analyzed using computer-assisted sperm analysis (CASA). Sperm membrane, acrosome status, DNA integrity were also assessed using propidium iodide (PI), fluorescein isothiocyanate conjugated to Arachis hypogaea (FITC-PNA), and acridine orange (AO) followed by flow cytometry. In addition, abundances of PRM1 and PRM2 were analyzed using flow cytometry experiments. Differences in sperm decondensation capacity were assessed in bulls of varying fertility using a decondensation assay. As determined using CASA, average pathway velocity, amplitude of lateral head displacement and straightness were different (P < 0.05) for sperm from high and low fertility bulls. There, however, were no differences between the high and low fertility bulls for characteristics of sperm plasma membrane, acrosome, and DNA integrity (P >  0.05). Relative abundances of PRM1 and PRM2 in sperm from the high and low fertility bulls were inversely related (P <  0.0001). Percentages of decondensed sperm were different between high and low fertility bulls (P < 0.0001) and total numbers of decondensed sperm were greater in low fertility bulls than high fertility bulls (R² = 0.72). Results of the present study are significant because molecular and morphological phenotypes of sperm that were detected affect fertility in livestock species.

Uncovering sperm metabolome to discover biomarkers for bull fertility

Background

Subfertility decreases the efficiency of the cattle industry because artificial insemination employs spermatozoa from a single bull to inseminate thousands of cows. Variation in bull fertility has been demonstrated even among those animals exhibiting normal sperm numbers, motility, and morphology. Despite advances in research, molecular and cellular mechanisms underlying the causes of low fertility in some bulls have not been fully elucidated. In this study, we investigated the metabolic profile of bull spermatozoa using non-targeted metabolomics. Statistical analysis and bioinformatic tools were employed to evaluate the metabolic profiles high and low fertility groups. Metabolic pathways associated with the sperm metabolome were also reported.

Results

A total of 22 distinct metabolites were detected in spermatozoa from bulls with high fertility (HF) or low fertility (LF) phenotype. The major metabolite classes of bovine sperm were organic acids/derivatives and fatty acids/conjugates. We demonstrated that the abundance ratios of five sperm metabolites were statistically different between HF and LF groups including gamma-aminobutyric acid (GABA), carbamate, benzoic acid, lactic acid, and palmitic acid. Metabolites with different abundances in HF and LF bulls had also VIP scores of greater than 1.5 and AUC- ROC curves of more than 80%. In addition, four metabolic pathways associated with differential metabolites namely alanine, aspartate and glutamate metabolism, β-alanine metabolism, glycolysis or gluconeogenesis, and pyruvate metabolism were also explored.

Conclusions

This is the first study aimed at ascertaining the metabolome of spermatozoa from bulls with different fertility phenotype using gas chromatography-mass spectrometry. We identified five metabolites in the two groups of sires and such molecules can be used, in the future, as key indicators of bull fertility.

Life Skill Development and Financial Impact Associated With a Youth Livestock Sales Program

The Sale of Junior Champions is a premier livestock auction and youth scholarship program held at Dixie Nationals as a part of Mississippi’s junior livestock program. The sale is open to 4-H and FFA members who qualified their livestock at the annual Dixie National Junior Round-Up. While youth livestock sales programs are commonly found at state and county fairs throughout the United States, demographic information and information concerning financial and life skill impacts of the program on participants is limited. Therefore, a survey instrument for the 2018 sale was designed to determine how the event has impacted the financial burden of continued education and life skill development of youth participants. Paper and electronic surveys were distributed during and after the event. Responses (n = 176) reflected a diverse group of participants including 4-H/FFA members (22%), parents of youth (22%), volunteers (21%), Extension employees/FFA advisors (22%), sale buyers/sponsors (12%), and others (2%). Most participants (45%) were older (40-60 years old). Almost half of the respondents (43%) had attended the sale 6 or more times, while 10% were first-time attendees. A driving force for attendance appeared to be the scholarships as 33% received or had a youth receiving a scholarship. Program participation promoted improvement in all life skills measured. Future educational goals in youths were reported to be positively impacted by sale participation (p < 0.001). Understanding of sale participant demographics and financial and life skill impacts will assist in program justification, future program growth, and identifying groups where participation can be strengthened.

Advances in Cryopreservation of Bull Sperm

Cryopreservation of semen and artificial insemination have an important, positive impact on cattle production, and product quality. Through the use of cryopreserved semen and artificial insemination, sperm from the best breeding bulls can be used to inseminate thousands of cows around the world. Although cryopreservation of bull sperm has advanced beyond that of other species, there are still major gaps in the knowledge and technology bases. Post-thaw viability of sperm is still low and differs significantly among the breeding bulls. These weaknesses are important because they are preventing advances both in fundamental science of mammalian gametes and reproductive biotechnology. Various extenders have been developed and supplemented with chemicals to reduce cryodamage or oxidative stress with varying levels of success. More detailed insights on sperm morphology and function have been uncovered through application of advanced tools in modern molecular and cell biology. This article provides a concise review of progress in the cryopreservation of bull sperm, advances in extender development, and frontiers using diverse techniques of the study of sperm viability. This scientific resource is important in animal biotechnology because with the advances in discovery of sperm fertility markers, there is an urgent need to improve post-thaw viability and fertility of sperm through enhanced cryopreservation for precision agriculture to produce food animals to ensure food security on the global scale.

Retained Acetylated Histone Four in Bull Sperm Associated With Fertility

Bull fertility, ability of the sperm to fertilize and activate the egg and support embryo development, is vital for cattle reproduction and production. Even though majority of histones are replaced by protamines, some histones are retained in sperm. It is known that chromatin remodeling during spermatogenesis results in dynamic changes in sperm chromatin structure through post-translational modifications (PTM) of sperm histones, which are important for regulation of gene expression. However, amounts of sperm Histone 4 (H4), its acetylated form (H4 acetyl), and to what extent these molecular attributes influence sperm chromatin structure and bull fertility are unknown. These gaps in the knowledge base are important because they are preventing advances in the fundamental science of bovine male gamete and improvement of bull fertility. The objective of this study was to test the hypothesis that expression dynamics as well as PTM of sperm H4 are associated with bull fertility. Flow cytometry was utilized to quantify H4 and H4 acetylated form in sperm from seven high and seven low fertility Holstein bulls. The results indicated that the average number of cells with H4 or H4 acetyl expression in high and low fertility bull sperm were 34.6 ± 20.4, 1.88 ± 1.8, 15.2 ± 20.8, and 1.4 ± 1.2, respectively. However, the sperm enriched in both H4 and H4 acetyl were different between high and low fertility groups (3.5 ± 0.6; 1.8 ± 0.8; P = 0.043). The localization and detection of H4 and H4 acetylation were measured by immunocytochemistry which revealed that H4 and H4 acetylation were equally distributed in the sperm head of high and low fertility sires. Western blotting results confirmed the presence of the H4 and its acetylated form in the sperm. Bioinformatics studies demonstrated that H4 is highly conserved among mammalians, and have significant gene ontology on spermatogenesis, early embryo implantation, and sperm capacitation. The results are significant because it demonstrates the replacement of canonical histone H4 into modified H4 acetylation in sperm and regulate its dynamics which is crucial for bull fertility and reproductive biotechnology. These findings advance fundamental science of mammalian early development and reproductive biotechnology.

Expression dynamics of Integrin Subunit Beta 5 in bovine gametes and embryos imply functions in male fertility and early embryonic development

Integrins have been shown to act as signalling receptors, and they primarily recognise extracellular matrix ligands on the oocyte surface. However, their possible roles in oocyte activation and embryo development are not clearly understood. The objectives of this study were to evaluate expression of Integrin Subunit Beta 5 (ITGβ5) in bovine sperm, oocytes, and early embryos and to ascertain the evolutionary conservation of ITGβ5. To accomplish these objectives, we used western blotting to study expression levels of ITGβ5 protein in sperm and RT-qPCR to determine expression levels of ITGβ5 transcripts in oocytes and embryos. We have also used bioinformatic analysis to determine the evolutionary conservation of the ITGβ5 protein among various species. Western blotting showed that ITGβ5 protein was detectable in bull sperm. Moreover, results of RT-qPCR showed that levels of ITGβ5 were significantly higher in the two-cell embryos, followed by the 8-16-cell embryos. However, no significant difference in expression levels were noted for the morula and blastocyst stages as compared to MII oocytes. Bioinformatic analysis revealed that ITGβ5 is conserved among various species. We conclude that expression of ITGβ5 in bovine gametes and embryos implies an important role in fertilisation and embryogenesis.

Relationship Between Gait Mechanics and the Speed of the Trot in the Weimaraner Dog Breed

While the size of the Weimaraner may assist in the breed performing the tasks of a sporting dog, the large size coupled with these tasks may also make the breed more susceptible to orthopedic issues. The understanding of the normal gait mechanics of the Weimaraner can be a useful tool in examining for gait abnormalities associated with these orthopedic issues, and yet, research concerning breed-specific gaits in the canine is limited. Therefore, study objectives were to define the normal Weimaraner trotting kinematics and determine the influence of speed on these parameters. Markers were attached to palpation points on the limbs and head of American Kennel Club registered Weimaraners. Dogs were tracked while performing a slow (1.2-1.7 m/s) and fast (1.9-2.3 m/s) trotting speed. Frame-by-frame analysis was performed. Paw ground contact and lift-off was documented and marker displacement was tracked. At both speeds, the trot had a diagonal footfall sequence with diagonal limb pairing alternating between diagonal bipedal support and suspension. The faster speed was achieved with significant increases in stride length and displacements of the head, withers, and fore and hind paws (P < .05). Range of motion of the elbow and hip significantly increased as the dog transitioned from a slow to fast speed (P < .05). Through gait analysis, the Weimaraner trot was defined as a 2-beat diagonal rhythm gait with suspension. Speed did not change these characteristics, but did influence stride length and linear and angular displacements, and thus, should be a consideration in clinical examination.

153 Sperm metabolomic landscape associated with bull fertility

Sub-fertility fertility in bulls decreases the efficiency and profitability of cattle production because AI allows a single bull to inseminate thousands of cows. In recent decades, there has been a general decline in fertility of bulls, even among those exhibiting normal sperm motility and morphology. Despite advances in technology and knowledge, molecular, cellular and physiological mechanisms underlying the causes of low fertility in bulls are currently unclear. Therefore, the objective of this study was to identify sperm metabolites associated with fertility in Holstein bulls. The metabolome of sperm from 10 mature bulls with high fertility (HF, n=5) and low fertility (LF, n=5) was identified by gas chromatography coupled to mass spectrometry. Bull fertility was based on the sire conception rates deviating from the average. Statistical analysis was performed by using MetaboAnalyst 3.0 (http://www.metaboanalyst.ca/). A total of 22 metabolites were detected and categorized according to their major chemical classes, including amino acids, peptides/analogues, carbohydrates/carbohydrate conjugates, fatty acids, steroids/steroid derivatives, keto acids and derivatives, carboxylic acids, and other organic and inorganic compounds. Organic acids and derivatives as well as fatty acids were the major compounds in bull spermatozoa. Seven organic acids and derivatives were detected, including benzoic acid, carbonate, carbamate dimethyl, carbamate trimethyl, lactic acid, oxalic acid, and urea. Five fatty acids were identified including oleic acid, oleanitrile, nonanoic acid, and palmitic acid. Oleic acid, phosphoric acid, phosphine, carbamate trimethyl, and glycerol were the most abundant metabolites in bull sperm, whereas benzoic acid, acetic acid, l-serine, carbamate, and 2-ketobutyric acid were the least predominant metabolites present in bull sperm. Multivariate analysis (partial least squares-discriminant analysis) of the sperm metabolome showed a clear separation between HF and LF bulls. Variable importance in projection (VIP) score demonstrated that metabolites with VIP &gt;1.5 were gamma-aminobutyric acid (VIP=2.01), carbamate trimethyl (VIP=1.88), benzoic acid (VIP=1.86), and lactic acid (VIP=1.81). Abundance ratios of gamma-aminobutyric acid, carbamate trimethyl, benzoic acid, and lactic acid was greater in HF bulls compared with LF animals. According to univariate analysis, abundance ratios of gamma-aminobutyric acid (P=0.03) and carbamate trimethyl (P=0.047) were greater in HF than in LF bulls. Gamma-aminobutyric acid was positively correlated with carbamate trimethyl (r=0.94; P&lt;0.0001) and benzoic acid (r=0.74; P=0.0139). Benzoic acid was positively correlated with carbamate trimethyl (r=0.75; P=0.0107) and carbamate dimethyl (r=0.68; P=0.0274). The identified metabolites can serve as potential markers to evaluate semen quality and predict bull fertility.

Metabolomic markers of fertility in bull seminal plasma

Metabolites play essential roles in biological systems, but detailed identities and significance of the seminal plasma metabolome related to bull fertility are still unknown. The objectives of this study were to determine the comprehensive metabolome of seminal plasma from Holstein bulls and to ascertain the potential of metabolites as biomarkers of bull fertility. The seminal plasma metabolome from 16 Holstein bulls with two fertility rates were determined by gas chromatography-mass spectrometry (GC-MS). Multivariate and univariate analyses of the data were performed, and the pathways associated with the seminal plasma metabolome were identified using bioinformatics approaches. Sixty-three metabolites were identified in the seminal plasma of all bulls. Fructose was the most abundant metabolite in the seminal fluid, followed for citric acid, lactic acid, urea and phosphoric acid. Androstenedione, 4-ketoglucose, D-xylofuranose, 2-oxoglutaric acid and erythronic acid represented the least predominant metabolites. Partial-Least Squares Discriminant Analysis (PLSDA) revealed a distinct separation between high and low fertility bulls. The metabolites with the greatest Variable Importance in Projection score (VIP > 2) were 2-oxoglutaric acid and fructose. Heat-map analysis, based on VIP score, and univariate analysis indicated that 2-oxoglutaric acid was less (P = 0.02); whereas fructose was greater (P = 0.02) in high fertility than in low fertility bulls. The current study is the first to describe the metabolome of bull seminal plasma using GC-MS and presented metabolites such as 2-oxoglutaric acid and fructose as potential biomarkers of bull fertility.

Seminal plasma proteins and metabolites: effects on sperm function and potential as fertility markers

Molecular components of sperm and in the media surrounding them influence male fertility. In this regard, seminal plasma proteins and metabolites modulate various reproductive events, including sperm motility and capacitation, cell protection, acrosome reaction, fertilization and embryonic development. Empirical associations between seminal proteins and metabolites and fertility indicate that these molecules are potential molecular markers of male reproductive status in cattle and other species.

Testis specific histone 2B is associated with sperm chromatin dynamics and bull fertility-a pilot study

BACKGROUND

Bull fertility is the degree of sperm's ability to fertilize and activate the egg and support embryo development, and this is critical for herd reproductive performance. We used the bull as a unique model organism for the study of male fertility because cattle genetics and physiology is similar to those of other mammals including humans. Moreover, reliable fertility data along with well-established in vitro systems are available for bovine. The objective of this original study was to ascertain evolutionary diversification and expression dynamics of Testis Specific Histone 2B (TH2B) in sperm from Holstein bulls with different fertility scores.

METHODS

The intensity of TH2B was determined by using flow cytometry in sperm from 13 high and 13 low fertility bulls. Expression levels of TH2B were measured using immunofluorescence and Western blotting in sperm from five high and five low fertility bulls. Sequence identity, evolutionary distance and interactome of TH2B were evaluated by dotmatcher, STRING and Cytoscape. Data were analyzed using linear mixed effects model and regression plots were drawn.

RESULTS

The intensity of TH2B as measured by flow cytometry was significantly affected by an interaction between fertility group and fertility score (P = 0.0182). The intensity of TH2B in sperm from the high fertility group decreased (P = 0.0055) as fertility increased. TH2B was constantly detectable in sperm and expression levels of TH2B decreased in relation to fertility in sperm from the high fertility group (P = 0.018). TH2B biological functions include male gamete generation, chromosome organization, DNA packaging, DNA conformation change, chromatin organization, nucleosome organization, chromatin disassembly, spermatid nucleus elongation, spermatid nucleus differentiation, sperm motility, chromatin organization, chromatin condensation, chromatin silencing, nucleus organization, and chromatin remodeling (P < 0.05).

CONCLUSIONS

We elucidated the cellular localization and molecular physiology of TH2B using both computational and cell biology approaches. In addition to advancing the fundamental science of mammalian male gamete, the present findings can be potentially used to evaluate semen quality and predict male fertility in the future.

TRIAL REGISTRATION

This study did not involve any live animals. We did not perform any anesthesia, euthanasia, or any kind of animal sacrifice. The cryopreserved semen samples were obtained from Alta Genetics, Inc., Watertown, WI, USA. All samples were preserved in liquid nitrogen.

Proteomic analysis of seminal plasma from locally-adapted "Curraleiro Pé-Duro bulls" (Bos taurus): identifying biomarkers involved in sperm physiology in endangered animals for conservation of biodiversity

The present study was aimed at evaluating the seminal plasma proteins and sperm parameters of Curraleiro Pé-Duro bulls. Semen was collected from 10 bulls by electroejaculation, and sperm parameters were evaluated in fresh and frozen-thawed semen. Seminal plasma proteins were analyzed by 2-D SDS-PAGE and mass spectrophotometry. Tools in computational biology were used to generate bioinformatic knowledge and evaluate gene ontology, protein-protein interactions, phylogenetic trees and multiple sequence alignments. Sperm motility in fresh and frozen-thawed semen was 78.8±1.8% and 21.2±1.6%, respectively. Pearson's correlations were evaluated (p<0.05). Sperm motility and vigor in fresh semen were correlated with clusterin, TIMP2 and cathepsin S (r=0.64-0.71) and sperm defects were related to inhibitor of carbonic anhydrase and BSP 5 (r=0.78-0.80). Clusterin, BSP 5, alpha-enolase, creatine kinase M-type, glyceraldehyde-3-phosphate dehydrogenase, BSP 3, albumin, and 5'-nucleotidase and legumain were correlated with acrosome intact live sperm (r=0.80-0.64). Associations were detected between sperm vigor and spermadhesin 1 (r=-0.89), and between sperm defects in fresh semen and spermadhesin 1 and clusterin (r=-0.81). Sperm motility in frozen-thawed semen was associated with BSP 1, spermadhesin 1, clusterin and spermadhesin Z13 (r=0.64-0.85). The percent of motile sperm after freeze-thawing was negatively correlated (r=-0.64) with the amount of spermadhesin 1 in the seminal plasma. Based on in silico analysis, TIMP2 interacted with BSP1, BSP3, BSP5 and metalloproteinases. Molecular functions of proteins associated with sperm parameters were binding, catalytic activity and enzymatic regulation. Amino acid sequences of spermadhesin 1 and BSP 1 from Bos taurus, and other domestic species were similar. Phylogenetic tree analysis demonstrated that clusterin from Bos taurus was related to Ovis aries and domains of clusterin, spermadhesin 1, BSP 1 and inhibitor of carbonic anhydrase were conserved as well. In summary, specific seminal proteins are associated with sperm parameters of locally-adapted bulls. Use of the endangered mammalian as a model may assist in understanding aspects of evolutionary adaptations and could improve assisted reproductive biotechnologies.

Molecular physiognomies and applications of adipose-derived stem cells

Adipose-derived stromal/stem cells (ASC) are multipotent with abilities to differentiate into multiple lineages including connective tissue and neural cells. Despite unlimited opportunity and needs for human and veterinary regenerative medicine, applications of adipose-derived stromal/stem cells are at present very limited. Furthermore, the fundamental biological factors regulating stemness in ASC and their stable differentiation into other tissue cells are not fully understood. The objective of this review was to provide an update on the current knowledge of the nature and isolation, molecular and epigenetic determinants of the potency, and applications of adipose-derived stromal/stem cells, as well as challenges and future directions. The first quarter of the review focuses on the nature of ASC, namely their definition, origin, isolation and sorting methods and multilineage differentiation potential, often with a comparison to mesenchymal stem cells of bone marrow. Due to the indisputable role of epigenetic regulation on cell identities, epigenetic modifications (DNA methylation, chromatin remodeling and microRNAs) are described broadly in stem cells but with a focus on ASC. The final sections provide insights into the current and potential applications of ASC in human and veterinary regenerative medicine.

254 SYSTEMS BIOLOGY OF SPERM AND BULL FERTILITY

Bull fertility, the ability of the spermatozoon to fertilize and activate the egg as well as support early embryonic development, is crucial for efficient production of cattle. With the major advances in fundamental science of reproduction, such as genomics, and in biotechnology, such as assisted reproductive technologies, bull influence on herd production has been accentuated. In addition to providing half of the genome for the zygote, sperm also contribute proteins, transcripts, and epigenetic traits that play important roles in sperm physiology, fertilization, and early embryonic development. Recently, using sperm from Holstein bulls with different in vivo fertility data, we have demonstrated that sperm Protamine 1 protein and a panel of microRNA are associated with bull fertility. In addition, molecular and cellular biology experiments on the analyses of sperm nuclear proteins showed that bull sperm have significant levels of histones that are also associated with bull fertility. This presentation will convey the results of most relevant research on discovery of sperm biomolecular markers associated with semen quality and bull fertility. Because of the available field data in bull fertility and the physiological similarities between bovine and other mammals, research results stemming from the systems biology of bull fertility are applicable to other species as well.

Sperm superoxide dismutase is associated with bull fertility

Decreasing mammalian fertility and sperm quality have created an urgent need to find effective methods to distinguish non-viable from viable fertilising spermatozoa. The aims of the present study were to evaluate expression levels of ?-tubulin 2C (TUBB2C), heat shock protein 10 (HSP10), hexokinase 1 (HXK1) and superoxide dismutase 1 (SOD1) in spermatozoa from Holstein bulls with varying fertility using western blotting and to analyse the biological networks of these key sperm proteins using a bioinformatics software (Metacore; Thomson-Reuters, Philadelphia, PA, USA). The rationales behind this study were that the sperm proteins play crucial roles in fertilisation and early embryonic development in mammals and ascertaining the biological networks of the proteins helps us better understand sperm physiology and early mammalian development. The results showed that expression of SOD1 was higher in spermatozoa from high fertility bulls (PPin vivo bull fertility. The findings are important because they illuminate molecular and cellular determinants of sperm viability and the identified protein markers can be used to determine bull fertility.

Molecular morphology and function of bull spermatozoa linked to histones and associated with fertility

Sub-par fertility in bulls is influenced by alterations in sperm chromatin, and it might not be solved with increased sperm concentration in artificial insemination. Appropriate histone retention during sperm chromatin condensation plays critical roles in male fertility. The objective of this study was to determine failures of sperm chromatin condensation associated with abnormal persistence or accessibility of histones by aniline blue (ANBL) test, expression levels, and cellular localizations of one variant and two core histones (H3.3, H2B, and H4 respectively) in the spermatozoa of low-fertility (LF) vs high-fertility (HF) bulls. The expression levels and cellular localizations of histones in spermatozoa were studied using immunoblotting, immunocytochemistry, and staining methods. The bioinformatics focused on the sequence identity and evolutionary distance of these proteins among three mammalian species: bovine, mouse, and human. We demonstrated that ANBL staining was different within the LF (1.73 (0.55, 0.19)) and HF (0.67 (0.17, 0.06)) groups (P<0.0001), which was also negatively correlated within vivobull fertility (r=−0.90,P<0.0001). Although these histones were consistently detectable and specifically localized in bull sperm cells, they were not different between the two groups. Except H2B variants, H3.3 and H4 showed 100% identity and were evolutionarily conserved in bulls, mice and humans. The H2B variants were more conserved between bulls and humans, than in mice. In conclusion, we showed that H2B, H3.3, and H4 were detectable in bull spermatozoa and that sperm chromatin condensation status, changed by histone retention, is related to bull fertility.

Interrelationships between apoptosis and fertility in bull sperm

Male fertility, the ability of sperm to fertilize and activate the egg and support early embryogenesis, is vital for mammalian reproduction. Despite producing adequate numbers of sperm with normal motility and morphology, some males suffer from low fertility whose molecular mechanisms are not known. The objective was to determine apoptosis in sperm from high and low fertility bulls and its relationship with male fertility. DNA damage, phosphatidylserine (PS) translocation, and expression of pro- and anti-apoptotic proteins (BAX and BCL-2) in the sperm were determined using TUNEL, Annexin V, and immunoblotting approaches, respectively. Amounts of apoptotic spermatozoa were 2.86 (± 1.31) and 3.00 (± 0.96) in high and low fertility bulls, respectively (P=0.548), and were not correlated with fertility. There was a negative correlation between early necrotic spermatozoa and viable spermatozoa (r = -0.99, P<0.0001). Fertility scores were correlated with live spermatozoa detected by eosin-nigrosin test and necrotic spermatozoa determined via flow cytometry (r = -0.49, P<0.006 and r = -0.266, P<0.0113, respectively). BAX level was higher in low fertile group than high fertile group; however, this difference was not statistically significant due to the variations of bull samples (Bull 1-3 vs. Bull 4-5) in low fertile group (P<0.283). BCL-2 was not detectable in any of the sperm samples. The results shed light onto molecular and cellular underpinnings of male fertility.

Dynamics of microRNAs in bull spermatozoa

BACKGROUND

MicroRNAs are small non-coding RNAs that regulate gene expression and thus play important roles in mammalian development. However, the comprehensive lists of microRNAs, as well as, molecular mechanisms by which microRNAs regulate gene expression during gamete and embryo development are poorly defined. The objectives of this study were to determine microRNAs in bull sperm and predict their functions.

METHODS

To accomplish our objectives we isolated miRNAs from sperm of high and low fertility bulls, conducted microRNA microarray experiments and validated expression of a panel of microRNAs using real time RT-PCR. Bioinformatic approaches were carried out to identify regulated targets.

RESULTS

We demonstrated that an abundance of microRNAs were present in bovine spermatozoa, however, only seven were differentially expressed; hsa-aga-3155, -8197, -6727, -11796, -14189, -6125, -13659. The abundance of miRNAs in the spermatozoa and the differential expression in sperm from high vs. low fertility bulls suggests that the miRNAs possibly play important functions in the regulating mechanisms of bovine spermatozoa.

CONCLUSION

Identification of specific microRNAs expressed in spermatozoa of bulls with different fertility phenotypes will help better understand mammalian gametogenesis and early development.

Reprogramming mammalian somatic cells

Somatic cell nuclear transfer (SCNT), the technique commonly known as cloning, permits transformation of a somatic cell into an undifferentiated zygote with the potential to develop into a newborn animal (i.e., a clone). In somatic cells, chromatin is programmed to repress most genes and express some, depending on the tissue. It is evident that the enucleated oocyte provides the environment in which embryonic genes in a somatic cell can be expressed. This process is controlled by a series of epigenetic modifications, generally referred to as "nuclear reprogramming," which are thought to involve the removal of reversible epigenetic changes acquired during cell differentiation. A similar process is thought to occur by overexpression of key transcription factors to generate induced pluripotent stem cells (iPSCs), bypassing the need for SCNT. Despite its obvious scientific and medical importance, and the great number of studies addressing the subject, the molecular basis of reprogramming in both reprogramming strategies is largely unknown. The present review focuses on the cellular and molecular events that occur during nuclear reprogramming in the context of SCNT and the various approaches currently being used to improve nuclear reprogramming. A better understanding of the reprogramming mechanism will have a direct impact on the efficiency of current SCNT procedures, as well as iPSC derivation.

195 SPERMATOZOAL PROTEIN MARKERS FOR ANGUS BULL FERTILITY

Fertility is one of the most economically important traits controlling animal reproduction. Despite its significant economic impact, there are no reliable markers to predict semen quality. The objective of this study was to identify spermatozoal proteins associated with bull fertility, the ability of the sperm to fertilize the oocyte and support embryonic development. To accomplish our objectives, we isolated total spermatozoal proteins from 4 Angus bulls with different fertility phenotypes. Next, differentially expressed proteins were determined using two-dimensional differential in-gel electrophoresis (2D-DIGE), followed by sequencing of the most differentially expressed proteins. Immunoblotting experiments were conducted to confirm expression of key proteins detected by 2D-DIGE. Our results from 2D-DIGE experiments showed approximately 2000 detectable spermatozoal proteins. Of these comprehensive lists of proteins, we identified 80 of the proteins with the highest differential expression in spermatozoa from high- and low-fertility bulls. Diverse sets of differentially expressed proteins known to play roles in sperm motility, metabolism, and cell morphology were identified. These proteins included outer dense fibre of sperm tails 2 and manganous superoxide, heat shock protein, tubulins, α-enolase, and acrosomal vesicle protein-1. Expression profiles of outer dense fibre of sperm tails 2 and manganous superoxide dismutase were confirmed using immunoblotting. The findings are significant because they help us understand the fundamental biology of the male gamete and early development. In addition, the identified proteins can be used as molecular markers to predict bull fertility, an economically important trait. Funded in part by the Mississippi Agricultural and Forestry Experiment Station, American Angus Association, and Alta Genetics, Inc.