Semen Quality Traits Research Articles

Effects of Supplementation of Different Antioxidants to Cryopreservation Extender on the Post-Thaw Quality of Rooster Semen-A Meta-Analysis.

The standardization of the semen cryopreservation technique could be an effective tool in poultry for the conservation of genetic resources. During this process, the production of reactive oxygen species increases, leading to oxidative stress that causes damage to the spermatozoa. To reduce this effect, the addition of exogenous antioxidants in the cryopreservation diluent has been reported to be effective. Multiple antioxidants such as catalase, vitamin E, cysteamine, ergothioneine, and serine have been studied in roosters. Therefore, the present investigation aims to perform a meta-analysis to determine if the use of the aforementioned antioxidants added to the cryopreservation extender produces an improvement in semen quality parameters in roosters after thawing. After collecting the data, a discriminant canonical analysis was performed to determine which of the selected semen quality traits provided the most information, with hypo-osmotic swelling test (HOST), viability, and total motility variables showing the highest discriminatory power. However, according to the descriptive statistics, catalase and serine are the antioxidants that improve a greater number of seminal quality parameters, and since catalase gives the most favorable results for most of the discriminating variables, it could be the antioxidant of choice.

MAP3K1, SPEF2 and PLCZ1 genes association with fertility and semen quality traits of AI bulls in Andhra Pradesh

Bull fertility plays an important role in improving the economic value of the herd and is measured in terms of semen quality traits, which is influenced by both genetic and non-genetic factors. Polymorphism of MAP3K1/ CviQI (rs463712269), SPEF2/HpyCH4V (rs722354121) and PLCZ1/AvaII (rs208019489) and their association with scrotal circumference, sperm motility and plasma membrane integrity, respectively were studied on 239 bulls of different breeds reared in different frozen semen bull stations. The MAP3K1/CviQ1 assay revealed that T allele was more frequent in Ongole and Murrah population. RFLP at SPEF2/ HpyCH4V locus indicated fixation of T allele in both the exotic purebred cattle (Holstein Friesian and Jersey) whereas selective advantage of C allele was observed in Murrah buffaloes. Except in Holstein Friesian crossbred, other cattle genetic groups were with CC genotype for PLCZ1/AvaII assay and the Murrah population had low genetic diversity and heterozygosity excess. The PLCZ1/ AvaII genotypes had significant influence on the plasma membrane integrity of sperm in Holstein Friesian, Jersey and Ongole bulls. The plasma membrane integrity of sperm was reported to be high in heterozygotes (CG) of Jersey and Ongole cattle. The present study, concluded the importance of PLCZ1 gene as a marker for semen quality assessment and selection in bulls.

Effect of season, age and period on semen quality traits in buffalo bulls

ABSTRACT This study investigated the effect of season, age and period on semen traits in buffalo bulls. Data collected during the year 2010–2021 for seven semen traits viz. ejaculate volume (VOL), sperm concentration (SPC), mass activity (MA), initial motility (BFM), post-thaw motility (PTM), number of sperms per ejaculate (NSP) and number of motile sperm (NMSP) from Murrah buffalo bulls (n = 45; aged: 24–75 months). A general mixed model was applied to obtain the R2 value which was the proportion of variation in semen variable. With study period, the highest SPC was obtained during 2012; with the season, the highest VOL (ml) in hot humid and the highest SPC during the hot-dry season and with age, higher VOL, SPC, NSP and NMSP was obtained in older bulls. This study showed that factors i.e. period, season and age had a significant effect on semen traits viz. VOL, MA, SPC, BFM, PTM, NSP and NMSP in buffalo bulls.

Evaluation of Genetic and Non-genetic Factors Influencing Semen Production Potential in Sahiwal Bulls

Background: Understanding genetic and non-genetic factors that influence the quality and quantity of semen production plays a crucial role in determining the reproductive efficiency and genetic progress within the Sahiwal breed. The objective of this study was to assess the impact of genetic and non-genetic factors on the semen production potential of Sahiwal bulls. Methods: Semen ejaculate data, including volume (VOL), sperm concentration per milliliter (CONC), total sperm count per ejaculate (TS), initial motility (INIT) and post-thaw motility (PT), as well as semen quality traits such as hypo-osmotic swelling test (HOST) and acrosome integrity of frozen semen (AIFS), were obtained from 52 Sahiwal bulls. The data spanned from January 2011 to December 2018 and were collected at BAIF’s frozen semen station in Jind, Haryana, India. To ensure data reliability, observations beyond the mean±4 standard deviations (S.D.) were identified as outliers and subsequently excluded from the study. Two key factors, namely the season of semen collection (winter, summer and monsoon) and the age of bulls at collection (categorized into 12-month intervals ranging from less than 36 months to 156 months), were considered influential factors affecting semen characteristics. To investigate the correlation between bulls (genetic + permanent environmental correlation) and semen parameters, a repeatability animal model was employed, treating the bull as a random effect. The statistical analysis was conducted using WOMBAT software. Result: The findings revealed that the season of semen collection had a highly significant effect (P less than 0.01) on VOL, CONC, TS and PT. However, INIT, HOST and AIFS were not influenced (P greater than 0.05) by the season of collection. Furthermore, age at semen collection significantly affected all semen characteristics. VOL and TS exhibited an increasing trend until 72 to 84 months, followed by a decline until 96 to 108 months.

Genetic parameters for bull effects on in vitro embryo production (IVP) and relationship between semen quality traits and IVP performance

In vitro production of embryos (IVP) is increasingly applied in dairy cattle breeding and promises widespread use of females of superior genetic merits. One of the current challenges with implementation of IVP is the variability in blastocyst rates. Several factors contribute to these variabilities, among which is known to be the bull used for oocytes fertilization. The extent of genetic control of bulls’ effect on IVP performances is yet to be investigated. This study estimates genetic parameters for bull effects on IVP performance traits including blastocyst rate, hatching rate and an index trait combining Blastocyst rate, Kinetic Score, and Morphology score (BL_M_K). The IVP experiments were performed using oocytes aspirated from slaughterhouse ovaries from Holstein cows, fertilized with semen from 123 Holstein bulls. A total of 77 in vitro fertilization (IVF) experiments with 163 records (different IVF groups) were available for the analysis. The results indicate low to moderate heritability and moderate to high repeatability estimates for bull effects on IVP performance traits. Our study also showed that some semen quality traits had significant effects on IVP performance. This included strong genetic correlations between pre-cryopreservation sperm viability and blastocyst rate as well as BL_M_K score at days 7 and 8. Despite the generally weak bull effect correlations and the high standard errors of the estimates, our results provide initial evidence of a measurable genetic component in the bull's impact on IVP performance traits. However, the high standard errors underscore the need for further studies with a larger sample size.

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.

Determinant genetic markers of semen quality in livestock.

The reproductive efficiency of livestock is crucial for agricultural productivity and economic sustainability. One critical factor in successful fertilization and the viability of offspring is the quality of semen. Poor semen quality, especially in frozen-thawed semen used in artificial insemination (AI) have been shown to influence conception outcomes, resulting a negative impact on livestock production. Recent advancements in genetic research have identified specific markers linked to semen quality traits in various livestock species, such as cattle, sheep, goats, pigs, buffalo, and equines. These genetic markers are essential in screening males for breeding suitability, which in turn enhances selective breeding programs. Understanding these markers is crucial for improving reproductive performance and increasing productivity in livestock populations. This review offers a comprehensive overview of the genetic markers associated with semen quality in key livestock. It explores the underlying genetic mechanisms and their practical implications in animal breeding and management. The review underscores the importance of integrating genetic insights into breeding strategies to optimize reproductive efficiency and ensure the sustainable development of livestock industries.

PSVII-4 Genetic Parameters for Various Semen Quality and Reproductive Performance Traits in Nellore Cattle Including X Chromosome Markers

Abstract Estimating genetic parameters of male and female fertility and reproduction traits is essential for optimizing beef cattle breeding programs. In general, only markers located on autosomal chromosomes are used for genetic evaluations. Sex chromosomes tend to be excluded due to the compensation mechanism of dosage of genes linked to the X chromosome, which is the second largest chromosome in the cattle genome and harbors many genes potentially influencing these traits. Therefore, we estimated genomic-based variance components, including the X chromosome in the variance components analysis for female precocity, fertility, and andrological traits based on the single-step GBLUP procedure and Bayesian inference. The dataset consisted of ~120,000 records for the probability of pregnancy at 14 months (PP14), early rebreeding (REBA), and stability (STAY). From the breeding soundness exam (BSE) of bulls, 20,000 records were obtained for semen quality, andrological biometry, semen defects, and bull fitness (BULL_FIT). The pedigree contained 660,608 animals, where 11,012 animals were genotyped for 770,111 SNPs. All traits have reasonable additive genetic variation and are heritable, with a substantial contribution from the X chromosome, indicating that genetic progress for these traits is feasible. The heritability estimates (h2) explained by autosomal and X chromosome SNPs was low and low-to-moderate, respectively, for female reproductive performance traits, such as REBA [0.17 (auto); 0.07 (sex chr)], PP14 (0.42;0.05), and STAY (0.32;0.01). For male traits, the heritability estimates based on the autosomes and X chromosome, respectively, ranged from 0.02 to 0.04 and from 0.01 to 0.03 for semen quality traits; from 0.10 to 0.68 and from 0.02 to 0.07 for morphological traits; from 0.10 to 0.12 and from 0.01 to 0.02 for semen defects traits; for bull evaluation (BULL_FIT) were observed h2 for autosomes 0.18 and 0.10 for sexual chromosome X. The results observed in this study indicate a substantial contribution of the X chromosome on fertility and reproductive performance traits. These findings will serve as background information for designing breeding programs for genetically improving semen production and quality and reproductive performance in Nellore cattle.

Effect of age, season and sire on semen quality traits in Frieswal breeding bulls

The present study was undertaken to assess the effect of season of semen collection, age and sire on semen quality of Frieswal breeding bulls. The data on 8113 semen ejaculates of 155 bulls born to 34 Frieswal sires were utilized for the study. The effect of age of bulls on semen volume, sperm concentration (million) per ml and sperm motility (%) in fresh semen (directly after collection) was highly significant. Additionally, it was discovered that the sire effect of bulls on different semen quality parameters and the influence of season on sperm concentration and motility both were statistically significant. Heritability estimates of different semen quality traits studied were moderately high and exceptionally significant. For semen volume, the estimate was found to be 0.336±0.078 while for concentration and pre freezing sperm motility values were 0.296±0.068 and 0.407±0.089, respectively. From the results, it may be concluded that the age and sire of bulls significantly affected the semen volume, sperm concentration and sperm motility in Frieswal bulls. The season of semen collection caused significant variations in sperm concentration and motility but not the semen volume. The semen volume and concentration were superior in ejaculates collected during winter season while the summer season was conducive for increased sperm initial motility. The Frieswal bulls up to 4-5 years are able to produce semen of better quality. The moderately high heritability estimates of semen quality traits provide indication for genetic improvement of the traits through selection.

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.

Effect of Genetic and Non-genetic Factors on Semen Quality Traits in Bovine Breeding Bulls

Background: A breeding bull is used to serve many females; therefore, for overall herd fertility, the bull's fertility is more important than female fertility. Methods: The present study was carried out to compare the effects of species, season, period, and interaction between species and season on the semen quality traits of Murrah buffalo and crossbred cattle bulls. For the 25-year study period, a total of 26205 ejaculation records of 389 bovine breeding bulls, including Murrah buffalo and crossbred cattle bulls, were analysed that were maintained at an organised farm. Result: Species and period of semen collection had a highly significant effect on all the traits (P less than 0.01). Season of semen collection and interaction between season and species had a highly significant effect (P less than 0.01) on semen volume (SV), consistency, mass activity (MA), total sperm count (TSC), initial motility (IM) and post-thaw motility (PTM), a significant effect (P less than 0.05) on age at first semen collection (AFSC) and non-significant effect on the semen colour and age at first semen freezing (AFSF). Overall, semen quality was good at the organised farm during all seasons. In bovine breeding bulls, PTM during the rainy and summer seasons was comparatively low. An overall increase in semen quality in the later periods showed progressive improvement in management at the organised farm over the period.

A Comparative Study for Semen Quality Traits between Murrah and Nili Ravi Buffalo Breeding Bulls Maintained at an Organized Farm

Background: The aim of the study was to compare the effect of season on the semen quality traits of Murrah and Nili Ravi buffalo breeding bulls. Methods: For a period of 5 years, a total of 855 ejaculation records of 17 buffalo breeding bulls, including Murrah (11) and Nili Ravi (6) buffalo bulls maintained at an organised farm, were analysed for various semen traits using least squares analysis. Result: Breed had a significant effect (p less than 0.01) on semen volume, consistency, mass activity (MA), total sperm count (TSC) and post thaw motility (PTM) and a non-significant effect on colour and initial motility (IM). In Murrah bulls, except for semen volume, the other parameters viz. consistency, MA, TSC and PTM were found to be significantly higher than Nili Ravi bulls. Season of semen collection had a significant effect on consistency, TSC and PTM whereas a non-significant effect on semen volume, colour, MA and IM was observed. During the summer season, overall consistency and TSC were higher, but PTM was found to be comparatively lower. Season and breed interaction had a significant effect (p less than 0.01) on consistency, TSC and IM while a non-significant effect on semen volume, colour, MA and PTM was observed. In Murrah buffalo bulls, a non-significant effect of season on consistency was observed whereas, in Nili Ravi bulls, a significantly higher consistency during summer and spring and; a significantly lower consistency during the rainy season was observed. In Murrah bulls, the highest TSC were observed during the rainy and summer seasons; whereas, in Nili Ravi bulls only during the summer season. In Murrah bulls, semen consistency, MA and IM were lower during the spring season; semen volume was lower during the prewinter season; total sperm count was lower during the winter season. In Nili Ravi bulls, semen volume was lower during summer; consistency, MA and TSC were lower during the rainy season; and IM was lower during the spring season. The PTM was lower during the summer season in both the breeds.

Micrococcal nuclease sequencing of porcine sperm suggests enriched co-location between retained histones and genomic regions related to semen quality and early embryo development.

The mammalian spermatozoon has a unique chromatin structure in which the majority of histones are replaced by protamines during spermatogenesis and a small fraction of nucleosomes are retained at specific locations of the genome. The sperm's chromatin structure remains unresolved in most animal species, including the pig. However, mapping the genomic locations of retained nucleosomes in sperm could help understanding the molecular basis of both sperm development and function as well as embryo development. This information could then be useful to identify molecular markers for sperm quality and fertility traits. Here, micrococcal nuclease digestion coupled with high throughput sequencing was performed on pig sperm to map the genomic location of mono- and sub-nucleosomal chromatin fractions in relation to a set of diverse functional elements of the genome, some of which were related to semen quality and early embryogenesis. In particular, the investigated elements were promoters, the different sections of the gene body, coding and non-coding RNAs present in the pig sperm, potential transcription factor binding sites, genomic regions associated to semen quality traits and repeat elements. The analysis yielded 25,293 and 4,239 peaks in the mono- and sub-nucleosomal fractions, covering 0.3% and 0.02% of the porcine genome, respectively. A cross-species comparison revealed positional conservation of the nucleosome retention in sperm between the pig data and a human dataset that found nucleosome enrichment in genomic regions of importance in development. Both gene ontology analysis of the genes mapping nearby the mono-nucleosomal peaks and the identification of putative transcription factor binding motifs within the mono- and the sub- nucleosomal peaks showed enrichment for processes related to sperm function and embryo development. There was significant motif enrichment for Znf263, which in humans was suggested to be a key regulator of genes with paternal preferential expression during early embryogenesis. Moreover, enriched positional intersection was found in the genome between the mono-nucleosomal peaks and both the RNAs present in pig sperm and the RNAs related to sperm quality. There was no co-location between GWAS hits for semen quality in swine and the nucleosomal sites. Finally, the data evidenced depletion of mono-nucleosomes in long interspersed nuclear elements and enrichment of sub-nucleosomes in short interspersed repeat elements.These results suggest that retained nucleosomes in sperm could both mark regulatory elements or genes expressed during spermatogenesis linked to semen quality and fertility and act as transcriptional guides during early embryogenesis. The results of this study support the undertaking of ambitious research using a larger number of samples to robustly assess the positional relationship between histone retention in sperm and the reproductive ability of boars.

Estimation Genetic Parameters of Semen Quality Traits in Iranian Holstein Bulls

For the design of any successful breeding program, knowledge about semen quality traits is greatly important and per-required. Reproductive performance is of paramount economic importance in the livestock industry, including dairy cattle production. Despite the importance of the quality of semen used in artificial insemination to the reproductive success of dairy herds, few studies have estimated the extent of genetic variability in semen quality traits. In this study, records collected by Jahed (station 1) and Sheykh Hasan (station 2) breeder centers from 1991 to 2013, were used to estimate variance components, heritability, and repeatability for sperm quality traits. Records information was analyzed by wombat software. Data were analyzed by using the repeatability model in three models, first by year-season-station, secondary by station, and third by year. In the first model, maximum heritability and repeatability (0.9755) estimated the total number of sperm in milt ejaculation trait. In the second model, maximum heritability (0.96), that was in Jahed center, estimated for total number sperm in milt ejaculation, maximum repeatability (1), that was in Jahed center, too, estimated for sperm volume and maximum repeatability (1), that was in both breeding centers, estimated for motility to post-thaw motile ratio trait. In the third model, maximum heritability and repeatability (0.54), estimated for (liveafmil) trait. Maximum heritability and repeatability estimates for the total number of post-thaw motile sperm per milt ejaculation trait were 0.19 and 0.32, respectively. The objectives of this study were to estimate genetic parameters of semen quality traits using data from routine semen collection in the Iranian Holstein.

SPAG6 c.900 T>C affects boar semen quality and blood-testis barrier function by creating a new splice acceptor site.

Sperm associated antigen 6 (SPAG6) acts as a scaffolding protein in the center of the flagellar axoneme and has an impact on the maturation of the motility of mammalian sperm flagella and the maintenance of sperm structure. In our previous research, SPAG6 c.900 T>C in exon 7 and exon 7 skipped transcript was identified by analyzing RNA-seq data of testicular tissues from 60 day (sexually immature) and 180 day (sexually mature) Large White boars. Herein, we found porcine SPAG6 c.900 T>C to be associated with semen quality traits in Duroc, Large White and Landrace pigs. SPAG6 c.900 C can generate a new splice acceptor site, inhibit the occurrence of SPAG6 exon 7 skipping to a certain extent, thereby promote the growth of Sertoli cells and maintain the normal blood-testis barrier function. This study provides new insights into the molecular regulation of spermatogenesis and a new genetic marker for the improvement of semen quality in pigs.

Differential proteomics highlights specific testicular proteins associated with chicken sperm motility and fertility potential

Sperm motility, the percentage of sperm with forward progressions, is one of the semen quality traits that is highly related with male fertility potential in farm animals. The proportion of roosters with low sperm motility impedes the reproduction efficiency. This study aimed to determine crucial testicular proteins linked to sperm motility defects as causes of subfertility in roosters. iTRAQ was performed with the testis from five low sperm motility roosters and three high ones. A total of 2345 proteins were identified, of which, 86 were differentially expressed (DEPs), including 5 up-regulated and 88 down-regulated proteins in the low group. These DEPs were mainly enriched in cytoskeleton and cilium cell component, and biological processes related to sperm motility, and protein transport, and cellular protein localization. A cluster of 13 down-regulated proteins such as IFT88, TEKT1, ACTN2, DNAH5, RSPH9, and SPAG6, were associated with axoneme assembly. Further western blot and immunohistochemical analysis confirmed the down-regulated SPAG6 expression in low group, and indicated its expression in other cell types in testis beyond round spermatids, and that its pattern was in accordance with testis development and recession pace. Silencing transcription factor SOX5 down-regulated SPAG6 transcripts and impaired the cell proliferation and migration. In summary, this study highlights that down-regulated sperm flagellar structure associated proteins were the potential cause of low sperm motility. More specifically, the highly conserved SPAG6 protein across species is a positive regulator for testis development, spermatogenesis, and sperm motility regulation in chickens.

Genome-wide association study reveals candidate markers related to field fertility and semen quality traits in Holstein-Friesian bulls

In vitro assessment of bull semen quality is routinely used in bull semen processing centres in order to ensure that semen destined to be used in the field has passed minimum standards. Despite these stringent quality control checks, individual bulls that pass the quality control checks can still vary in field fertility by up to 25%. A genome-wide association study was undertaken to determine genetic markers associated with prefreeze and post-thaw bull sperm quality traits as well as field fertility. Genome-wide association analysis was performed using a single nucleotide polymorphism (SNP) regression mixed linear model in WOMBAT. Genes within a 250 Kb span of a suggestive (P ≤ 1 × 10−5) SNP were considered as candidate genes. One SNP was associated with adjusted pregnancy rate, and 21 SNPs were associated across the seven semen quality traits (P ≤ 1 × 10−5). Functional candidate genes include SIPA1L2 which was associated with adjusted pregnancy rate. This encodes a Rap GTPase-activating protein involved in Rap1 signalling pathway and was previously found to play a role in the process of sperm differentiation. Gene ontology (GO) analysis also identified significantly enriched biological processes involved protein tyrosine kinase activity including genes such as DYRK1A, TEC and TXK that were associated with sperm motility prior to freezing. Another candidate gene associated with post-thaw sperm motility was FHDC1 which coordinates actin filament and microtubule dynamics. The induced 11 GO terms in the ejaculates rejected after freezing trait were related to ATPase, phosphatase and hydrolase activity. These results reveal novel specific genomic regions and candidate genes associated with economically important phenotypes such as field fertility and semen quality traits.

Genetic parameters for various semen production and quality traits and indicators of male and female reproductive performance in Nellore cattle

BackgroundGiven the economic relevance of fertility and reproductive traits for the beef cattle industry, investigating their genetic background and developing effective breeding strategies are paramount. Considering their late and sex-dependent phenotypic expression, genomic information can contribute to speed up the rates of genetic progress per year. In this context, the main objectives of this study were to estimate variance components and genetic parameters, including heritability and genetic correlations, for fertility, female precocity, and semen production and quality (andrological attributes) traits in Nellore cattle incorporating genomic information.ResultsThe heritability estimates of semen quality traits were low-to-moderate, while moderate-to-high estimates were observed for semen morphological traits. The heritability of semen defects ranged from low (0.04 for minor semen defects) to moderate (0.30 for total semen defects). For seminal aspect (SMN_ASPC) and bull reproductive fitness (BULL_FIT), low (0.19) and high (0.69) heritabilities were observed, respectively. The heritability estimates for female reproductive traits ranged from 0.16 to 0.39 for rebreeding of precocious females (REBA) and probability of pregnancy at 14 months (PP14), respectively. Semen quality traits were highly genetically correlated among themselves. Moderate-to-high genetic correlations were observed between the ability to remain productive in the herd until four years of age (stayability; STAY) and the other reproductive traits, indicating that selection for female reproductive performance will indirectly contribute to increasing fertility rates. High genetic correlations between BULL_FIT and female reproductive traits related to precocity (REBA and PP14) and STAY were observed. The genetic correlations between semen quality and spermatic morphology with female reproductive traits ranged from -0.22 (REBA and scrotal circumference) to 0.48 (REBA and sperm vigor). In addition, the genetic correlations between REBA with semen quality traits ranged from -0.23 to 0.48, and with the spermatic morphology traits it ranged from -0.22 to 0.19.ConclusionsAll male and female fertility and reproduction traits evaluated are heritable and can be improved through direct genetic or genomic selection. Selection for better sperm quality will positively influence the fertility and precocity of Nellore females. The findings of this study will serve as background information for designing breeding programs for genetically improving semen production and quality and reproductive performance in Nellore cattle.

Impact of Alpinia galanga and zinc on semen quality and some reproductive hormone constituents in California rabbit bucks.

The objective of the current study was to investigate the influence of synergism of the dry powder of Alpinia galanga rhizomes (AGR) and/or zinc sulfate in the diet on semen quality and reproductive traits of California rabbit bucks. The study was conducted in two stages. First stage: appreciation of semen characteristics, 36 California rabbit bucks (aged 5 months) with average body weights of 2980 g were divided randomly into six treatments (six individuals each). The treatment groups were: first group, control fed basal diet (C); second group, fed basal diet plus 1 g AGR/kg dry matter (DM) (AGR1); third group, fed basal diet plus 2 g AGR/kg DM (AGR2); fourth group, fed basal diet plus 200 mg Zn/litre drinking water (Zn); fifth group, fed basal diet plus 1 g AGR/kg DM and 200 mg Zn/litre drinking water (AGR1 + Zn); sixth group, fed basal diet plus 2 g AGR/kg DM and 200 mg Zn/litre drinking water (AGR2 + Zn). Second stage: the previous bucks were used to determine the efficiency of semen on reproductive fertility traits, 48 mature does (aged 6 months, nulliparous) with an average body weight of 3050 ± 20.7 g were divided randomly into six treatments and inseminated with previous groups of treated bucks. The results of the first stage, recorded high activity on gonadotropins hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH), free testosterone (FT), progesterone (P4) and oestrogen (E217β) concentrations for AGR1 + Zn and AGR2 + Zn compared with the control group. Groups AGR1, AGR2, AGR1 + Zn and AGR2 + Zn had significantly lowered concentrations of triglycerides, total cholesterol, low-density lipoprotein, and malondialdehyde (MDA), whereas high-density lipoprotein and total antioxidant capacity (TAC) were increased significantly compared with the control group. The group supplemented with AGR with or without Zn had significantly improved ejaculate volume, advanced motility, sperm concentration, and cell integrity. Fertility rate and litter size were improved in all groups compared with the control. It was concluded that supplementing diets with Alpinia galanga and Zn significantly increased sperm percentage, motility and reproductive hormones (testosterone, FSH, LH, E217β, P4). This suggested that this plant when used may be favourable for improved sperm quality and fertility parameters.

Age-dependent genetic and environmental variance of semen quality in Nordic Holstein bulls

The aim of this study was to estimate genetic and environmental parameters, across bull's age, for semen quality traits including pre- and postcryopreservation semen concentration, sperm motility, and sperm viability as well as ejaculate volume and number of doses per ejaculate. A data set on 96,595 ejaculates from 2,831 Nordic Holstein bulls collected between 2006 and 2019 was used. Genetic and environmental parameters were estimated using a random regression model and applying the average-information REML approach. Spline functions were chosen to fit the additive genetic and permanent environmental effects across bull's age, and the optimal number of knots was chosen using cross validation. Residual variance heterogeneity was assumed in different bull age classes. The estimated repeatabilities of semen quality traits ranged from 0.16 to 0.85 across different ages of bulls. The estimated heritabilities of semen quality traits ranged from 0.02 to 0.56 across different ages of bulls. The results indicate possibilities for genetic improvement of semen quality traits through selective breeding.