Age and seasonal-dependent variations in the biochemical composition of boar semen

Nonsynonymous SNPs within C7H15orf39 and NOS2 are associated with boar semen quality

Spermatogenesis is the developmental process that produces spermatozoa. The aim of this study was to investigate the single nucleotide polymorphisms (SNPs) within C7H15orf39 and NOS2 genes and to determine the correlations between two SNPs and semen quality in Duroc boars (n = 604). The polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method was used for genotyping the selected two nonsynonymous SNPs. The significant correlation was observed between two SNPs (rs80969873: g.58385473 G > A within C7H15orf39; rs325865291: g.44175445 G > A within NOS2) and semen traits in Duroc boars. This study indicates the SNPs in C7H15orf39 and NOS2 may be the potential molecular marker for improving the semen quality traits in Duroc boars.

Influence of age and seasonality on boar seminal plasma steroids quantification: A preliminary study

Background and Aim

Seasonal changes, especially temperature and photoperiod, are well-known determining factors of swine reproductive capacity, but the underlying mechanisms remain unknown. This study aimed to investigate the effect of age and seasonal variations on boar seminal plasma steroids (dehydroepiandrosterone [DHEA], cortisol [CORT], and testosterone [TEST]) over 1 year.

Materials and Methods

Four commercial hybrid adult boars (Large White × Duroc), aged between 12 and 44 months, were repeatedly evaluated at the Department of Veterinary Medical Sciences of the University of Bologna. Daily temperature and light hours relating to the collection date were considered for each observation within the four astronomical seasons: Winter, spring, summer, and autumn. Hormones were quantified using radioimmunoassay. The association between seasonal factors and hormone concentrations was evaluated using linear regression models. Univariate models were estimated for each hormone to assess the influence of the independent variables; two multivariate models were assessed to evaluate the effect of temperature and daylight hours, including boar and season factors.

Results

Age significantly affected all analyzed hormones (CORT p < 0.0001; DHEA p < 0.0001; and TEST p < 0.0001). The highest average levels were found for each hormone during summertime, suggesting a positive correlation between steroid concentrations with temperature and light hours.

Conclusion

The results of this study support the hypothesis that the increase in external temperature and light hours is somehow associated with higher levels of steroid concentrations in the seminal plasma of in-housed boars. These findings may help further investigate seasonal fluctuations in reproductive outcomes, which are well-known for porcine species.

Influence of age, breed, and season on the quality of boar semen stored at low-temperature

In the face of antimicrobial resistance, antibiotic-free, low-temperature storage of boar semen has been well-researched in recent years and promising results have been obtained. With the prospect of establishing this new preservation method in practice, it is important to evaluate a range of factors, possibly influencing the general and/or boar individual preservation suitability for 5 °C storage. The present study aimed to evaluate the influence of boar age (<18 months (n = 29) vs. 18-36 months (n = 68) vs. >36 months (n = 56)), breed (Pietrain (n = 104) vs. Duroc (n = 49)), as well as the influence of season (summer (n = 73) vs. winter (n = 80)) on the quality of boar semen preserved in antibiotic-free Androstar® Premium extender. AI doses were stored at 5 °C after cooling according to an established cooling protocol. In total, 153 ejaculates were analyzed throughout two identical experimental runs in summer and in winter, and the boars were divided into the corresponding sub-groups based on their age and breed. The application of a general linear model (GLM) and subsequent Bonferroni-corrected post hoc tests did not reveal any significant differences in the quality of semen stored at 5 °C between the different age groups. Regarding the season, a difference was found in the progressive motility (PM) at two out of seven analysis time points (P ≤ 0.01), however, this difference in PM was also present in fresh semen (P < 0.001). Most significant differences were found when comparing the two breeds. At six out of seven analysis time points, PM of Durocs was significantly lower than PM of Pietrains. Again, this difference in PM was also recognizable in fresh semen (P < 0.001). No differences were found in plasma membrane and acrosome integrity examined by flow cytometry. In conclusion, our study confirms the feasibility of 5 °C storage of boar semen under production conditions regardless of boar age. While season and breed have an influence on boar semen stored at 5 °C, these differences are not primarily caused by storage temperature, as they were already apparent in fresh semen.

Timeless or tainted? The effects of male ageing on seminal fluid

Reproductive ageing can occur due to the deterioration of both the soma and germline. In males, it has mostly been studied with respect to age-related changes in sperm. However, the somatic component of the ejaculate, seminal fluid, is also essential for maintaining reproductive function. Whilst we know that seminal fluid proteins (SFPs) are required for male reproductive success across diverse taxa, age-related changes in SFP quantity and composition are little understood. Additionally, only few studies have explored the reproductive ageing of the tissues that produce SFPs, and the resulting reproductive outcomes. Here we provide a systematic review of studies addressing how advancing male age affects the production and properties of seminal fluid, in particular SFPs and oxidative stress, highlighting many open questions and generating new hypotheses for further research. We additionally discuss how declines in function of different components of seminal fluid, such as SFPs and antioxidants, could contribute to age-related loss of reproductive ability. Overall, we find evidence that ageing results in increased oxidative stress in seminal fluid and a decrease in the abundance of various SFPs. These results suggest that seminal fluid contributes towards important age-related changes influencing male reproduction. Thus, it is essential to study this mostly ignored component of the ejaculate to understand male reproductive ageing, and its consequences for sexual selection and paternal age effects on offspring.

Gut microbial diversity among Yorkshire, Landrace and Duroc boars and its impact on semen quality

The gut microbiota plays an important role in pig health and performance, particularly in host growth and fecundity. In present study, the characteristics and diversity of gut microbiota in fine purebred boars from three-way crossbred "Duroc×Landrace×Yorkshire" pigs were investigated using 16 S rRNA gene sequencing. The results showed that the three breeds of boars shared similar gut microbiota, yet there remain slight differences at the family/genus level. At the family level, Ruminococcaceae, Streptococcaceae and Lactobacillaceae have the highest abundance in Landrace, while Rikenellaceae and f_p_251_o5 have the highest abundance in Duroc. The abundance of Prevotellaceae, Lachnospiraceae and Spirochaetaceae in intestinal of Yorkshire were higher than that of Landrace and Duroc. In addition, ten and six biomarkers were identified in the microbiota across breeds and months of age, respectively. Moreover, we evaluated the effect of gut microbiota on boar semen quality, revealing that Duroc had the strongest sperm vitality, significantly associated with the genus Rikenellaceae_PC9_gut_group. In addition, the spermatogenesis ability and sperm production improved gradually along with increase of age. In conclusion, this study provides a reference for understanding the gut microbiota composition of purebred boars used for three-way crosses and their impact on semen performance.

Candida Genus Maximum Incidence in Boar Semen Even after Preservation, Is It Not a Risk for AI though?

There is little information in the literature about the fungal contamination of boar semen and its persistence during storage. The challenge of this study was to perform a mycological screening to identify the yeast in the raw semen at 12/24 h after dilution. The research was done in pig farms in the N-E area of Romania, with maximum biosecurity and state-of-the-art technology. All the examined ejaculates (101) were considered to be normal for each spermogram parameter, with microbiological determinations in T0 at the time of ejaculate collection, T1 at the time of dilution, and T2 at 24 h of storage. Microbiological determinations (mycological spermogram) were performed for quantitative (LogCFU/mL) and qualitative (typification of fungal genera) identification. Bacterial burden (×103 LogCFU/mL) after dilution (T1) decreased drastically (p < 0.0001) compared to the one in the raw semen (T0). After 24 h of storage at 17 °C, the mean value of the bacteriospermia remained constant at an average value of 0.44. Mycospermia had a constant trend at T0 (raw) and T1 (0.149 vs. 0.140) and was slightly higher at T2 (0.236). The difference between T1 vs. T2 (p = 0.0419) was close to the statistical reference value (p = 0.05). Of the total genera identified (24), the fungi had a proportion of 37.4% (9/15) and a ratio of 1:1.6. Regarding the total species (34), the fungi had a frequency of 29.42% (10/24) with a ratio between the fungi and bacteria of 1:2.4. A fertility rate of 86% was observed in the L1 group (50 AI sows with doses and mycospermia from T1), and an 82% rate was observed in the L2 group (50 AI sows with doses and mycospermia from T2). The litter size of L1 was 9.63 piglets and 9.56 for L2. Regarding the total number of piglets obtained between the two groups, there was a slight decrease of 22 piglets in group L2, without statistical differences (p > 0.05). The predominant genera persisted after dilution during a 12 h storage at 17 °C, where yeasts, such as Candida parapsilosis and C. sake were identified in more than 92% of AI doses.

Live cells are not affected by dead sperm in liquid boar semen: new insights based on a thermo-resistance test

This study evaluated the effect of different proportions of dead spermatozoa on the quality of liquid boar semen during a thermo-resistance test (TRT). After three days of storage (17°C), 54 conventional AI semen doses (~ 23 × 10⁶ sperm/mL in ~ 88 mL of BTS) were split into three 15 mL-treatments (25%, 50% and 75% dead sperm cells) by mixing two subsamples containing 75% (I) and 0% (II) of live cells. Spermatozoa were evaluated after TRT at 30 (on-test) and 300 min (off-test) incubation at 38°C. At the on-test, treatments 25%, 50% and 75% dead sperm cells showed medians for total sperm motility of 77.6%, 50.2% and 25.6%, respectively. Considering the absolute variation of sperm motility during TRT, doses with 25% dead sperm lost more percentage points (pp) (-9.4 pp) compared to doses containing 50% (-8.2 pp) and 75% dead sperm (-4.5 pp). The lowest loss was observed for doses with 75% dead sperm (P < 0.01). However, data showed that treatments lost similar proportion of motile cells over the TRT: 25% dead sperm = -11.9%, 50% dead sperm = -16.0% and 75% dead sperm = -17.5% (P = 0.31). Regarding the flow cytometry parameters (plasma and acrosomal membrane integrity, mitochondrial activity of cells with intact plasma membrane, high degree of lipid disorder and apoptotic cells), the absolute variations did not surpass values of -1.8 pp, 3.4 pp, -5.4 pp and 4.7 pp, respectively. Moreover, the relative variation suggested that dead sperm did not substantially change their values over the TRT. In conclusion, dead sperm cells did not influence the quality of contemporary live cells during the period and in conditions of a TRT.

Linseed oil in boar's diet during high temperature humidity index (THI) period improves sperm quality characteristics, antioxidant status and fatty acid composition of sperm under hot humid sub-tropical climate

Environmental heat stress in sub-tropical climates negatively impacts boar semen production and its quality. The present study aimed to examine the heat stress alleviating effects of dietary linseed oil on semen quality and antioxidant status of boar, in the summer and winter seasons in sub-tropical climate. Six Hampshire crossbreed boars were fed with 90 mL linseed oil (treatment) whereas six boars of the same breed were fed 90 mL vegetable oil (control) for sixteen weeks during both season. Sperm quality was assessed for motility, viability, abnormality, acrosomal integrity, and Hypo-osmotic swelling test (HOST). Sperm velocity attributes were assessed by computer-assisted semen analysis (CASA). Antioxidants (glutathione peroxidase; GPx, catalase; CAT, total antioxidant capacity; TAC and nitric oxide; NO) and lipid peroxidation (malondialdehyde; MDA) were measured in seminal plasma and serum. Gas chromatography-mass spectrometry (GC-MS) was used for the estimation of fatty acid composition of seminal plasma and spermatozoa. Feeding linseed oil to the boars significantly (p < 0.05) improved sperm quality at the fresh stage and after 72 h of liquid storage in both season. There was a significant (p < 0.01) effect of treatment and season on semen quality parameters. Significant boar (p < 0.05) effect was recorded on reaction time, semen volume, sperm abnormality, acrosomal integrity and HOST reactive sperm. There was a significant (p < 0.01) effect of treatment and season on the velocity attributes viz. VAP, VSL, VCL, ALH, BCF and STR%. Linseed oil supplementation significantly (p < 0.01) enhanced antioxidant and lowered MDA levels in serum as well as seminal plasma. The concentration of alpha-linolenic (ALA), arachidonic and docosahexaenoic (DHA) fatty acids were significantly (p < 0.01) increased in seminal plasma and sperm after linseed oil supplementation. In conclusion, linseed oil supplementation to boar during high THI months improved the semen quality parameters viz. semen volume, sperm concentration, and progressive motile sperm, along with enhanced antioxidant capacity.

Retrospective analysis of commercial heterospermic and homospermic cooled boar semen: effect of the season, sample type and shipping temperature on sperm quality

We retrospectively analyzed data from heterospermic and homospermic boar semen for motility and morphology during a 2-year period. Homospermic doses were also evaluated for viability, acrosome integrity, DNA fragmentation, osmolality and pH. Additionally, we investigated the effect of temperature upon arrival and the agreement between viability and motility as evaluating tool. We observed lower (p < 0.05) total motility (TM) and normal sperm morphology within summer and fall. Conversely, lower (p < 0.05) progressive motility (PM) was found at the beginning and end of each year. Viability and acrosome integrity were reduced (p < 0.05) in summer months but not exclusively, suggesting that samples could be compromised by transport temperature. Sperm DNA fragmentation was <6% with a small variation. Medium osmolality and pH slightly changed (p < 0.05). Sperm count was not source of variation on sperm parameters. Sample temperature upon arrival correlated to PM and VSL (p < 0.05). While motility was reduced <12°C (p < 0.05). Homospermic doses were less affected by season and arrival temperature, having better parameters (p < 0.05) than contemporaneous heterospermic samples but influenced by genetic line (p < 0.05). We found a high agreement between viable acrosome-intact sperm and TM, especially when TM was ≥80%. Our data verify the improvement of sperm quality during time as sperm count/dose does not affected quality, but season effect persists regardless of ejaculate selection at the stud. Homospermic exhibited better parameters than heterospermic doses, seemingly being more resilient to temperature variations, suggesting that selection for sperm quality within boars selected by growth traits can improve product quality.

Impact of Seminal Plasma Composition on Sperm Freezability in Wild Mammals: A Review

This review was designed to summarize the most important information around seminal plasma composition and discuss its impact on the freezability of wild mammal semen samples. Seminal plasma is made up of various biochemical constituents, including ions, lipids, proteins, enzymes, and sugars, which vary between species in response to the presence and size of any relevant accessory glands. The biochemical constituents of seminal plasma may change as a result of age, individual variability, and seasonality. These constituents are responsible for supporting different functions in sperm cells, contributing to motility, acrosomal reaction, and fertilization events. A detailed understanding of seminal plasma biochemistry may help to optimize semen freezing protocols, enabling the dynamic alteration in diluents to allow for increased sperm viability rates after thawing.

Precocious puberty in male wild boars: a possible explanation for the dramatic population increase in Germany and Europe

Background

The wild boar population in Europe is steadily growing, one of the reasons for this increase probably being the high reproductive potential of this large mammal. Population management is important to stabilise wild boar numbers and a great deal of attention is focusing on the reasons, which might contribute to the high reproductive rates. Understanding the timing of puberty attainment provides information required for proper management practices. Knowledge of the earliest expected time of sexual maturation in male wild boars is limited, research being mostly focused on females. Previous hunting references indicate that sexual maturity in males occurs in the second year after birth. In contrast, male domestic pigs become sexually mature from about seven months of age. Thus, aims of this study were to investigate (1) whether there is a physiological ability for reproduction also in male wild boars of a younger age and (2) whether the body weight of wild boar males has a more important role than age in driving the maturation of the testis.

Methods

Male wild boar individuals were sampled during hunting drives in the eastern part of Lower Saxony in Germany. Testes with epididymides from 74 males were collected and prepared for histological examination and immunohistochemistry. The reproductive status could be ascertained based on development/occurrence of different germ cell populations using histology and based on the immunohistochemical detection of the anti-Müllerian hormone and androgen receptor.

Results

In this study, male wild boars aged nine to ten months already passed puberty and were able to reproduce if they had reached the appropriate body condition of about 29 kg dressed weight. Immunopositivity to the anti-Müllerian hormone in Sertoli cells was evident only in prepubertal animals and decreased with the onset of puberty. No immunoreaction was evident at postpuberty. The androgen receptor was detected in Sertoli cells, peritubular cells and Leydig cells, surprisingly already in Sertoli cells of prepubertal wild boars as well depending on body weight. Moreover, two-thirds of young males aged about ten months were precociously reproductively mature, showing histologically the presence of spermatozoa in testes and epididymides.

Conclusions

As piglets are mostly born in spring, also these young male individuals could target the heat of female wild boars in the winter months, resulting in the observed population increase. Therefore, a reduction in wild boar numbers should also focus on piglets of both sexes.

Assessment of the Morphometry of Heads of Normal Sperm and Sperm with the Dag Defect in the Semen of Duroc Boars

Introduction

The Dag defect is one of the primary morphological defects in sperm correlating with reduced fertility. This defect is found in the spermatozoa of many livestock species. The aim of the study was to assess the morphometry of the heads of normal sperm and sperm with the Dag defect in the semen of Duroc breeding boars.

Material and Methods

Sperm morphology was examined in ten ejaculates each from 12 Duroc boars. In total, 3,600 morphologically normal sperm and 838 sperm with the Dag defect were evaluated. The area, perimeter, length and width of the sperm head were measured and these basic morphometric parameters were used to calculate four additional shape indices characterising the sperm head, i.e. ellipticity, elongation, roughness and regularity.

Results

Sperm with this defect had markedly smaller heads, 0.32 μm shorter and 0.19 μm narrower than the heads of sperm with normal morphological structure. The heads of sperm with the Dag defect also had a 1.1μm smaller perimeter and a 2.5 μm² smaller surface area than the heads of morphologically normal sperm.

Conclusions

The Dag defect is found in boar sperm irrespective of the age of the individual. It affects the morphology of the sperm head.

Evolutionary consequences of environmental effects on gamete performance

Variation in pre- and post-release gamete environments can influence evolutionary processes by altering fertilization outcomes and offspring traits. It is now widely accepted that offspring inherit epigenetic information from both their mothers and fathers. Genetic and epigenetic alterations to eggs and sperm-acquired post-release may also persist post-fertilization with consequences for offspring developmental success and later-life fitness. In externally fertilizing species, gametes are directly exposed to anthropogenically induced environmental impacts including pollution, ocean acidification and climate change. When fertilization occurs within the female reproductive tract, although gametes are at least partially protected from external environmental variation, the selective environment is likely to vary among females. In both scenarios, gamete traits and selection on gametes can be influenced by environmental conditions such as temperature and pollution as well as intrinsic factors such as male and female reproductive fluids, which may be altered by changes in male and female health and physiology. Here, we highlight some of the pathways through which changes in gamete environments can affect fertilization dynamics, gamete interactions and ultimately offspring fitness. We hope that by drawing attention to this important yet often overlooked source of variation, we will inspire future research into the evolutionary implications of anthropogenic interference of gamete environments including the use of assisted reproductive technologies. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'

Dietary flaxseed oil improve boar semen quality, antioxidant status and in-vivo fertility in humid sub-tropical region of North East India

Environmental stress in the form of high temperature humidity index (THI) in tropical and sub-tropical region negatively affects semen quality and fertility of boar. Therefore, the present study was done to evaluate the effect of supplementing flaxseed oil (FLO) to boar's diet on its semen quality, antioxidant status, fatty acid composition of seminal plasma and fertility under sub-tropical climate. For this purpose, six Hampshire crossbreed (50% Hampshire and 50% Gunghroo) boars were divided into two groups i.e control (CON) and treatment (FLO). In FLO and CON group, flaxseed and vegetable oil, respectively, was top dressed at the rate of 3% in basal diets for each boar on daily basis for 16 weeks during monsoon season. A total of 60 ejaculates, comprising 30 ejaculates from each group (ten ejaculates from each boar) were collected. Semen samples were evaluated for sperm quality parameters (SQPs: motility, viability, abnormality, acrosomal integrity and Hypo-osmotic swelling test) and velocity attributes by computer assisted semen analysis (CASA) at fresh and after 72 h of preservation at 17 °C. Antioxidant (glutathione peroxidase; GPx, catalase; CAT, total antioxidant capacity; TAC and malondialdehyde; MDA) were analyzed in seminal plasma and serum. Fatty acid compositions of seminal plasma were analyzed by gas chromatography-mass spectrometry (GC-MS). In-vivo fertility study was also conducted. Reaction time and false mounts were significantly (p < 0.05) reduced in FLO group as compared to CON group. Semen quality parameters were significantly (p < 0.05) improved at fresh stage and after 72 h of liquid storage in FLO group as compared to CON group. Velocity attributes (VAP, VSL, VCL, ALH, BCF and LIN) were significantly (p < 0.05) higher in FLO group. Flaxseed oil supplementation significantly (p < 0.01) enhanced serum GPx and CAT concentration. Serum and seminal plasma MDA concentration decreased significantly (p < 0.01) in FLO group. Similarly, GPx, TAC and CAT were significantly (p < 0.01) elevated in seminal plasma of FLO group. The study revealed that feeding of flaxseed oil altered the fatty acid composition of seminal plasma and significantly (p < 0.05) improved the farrowing rate. In summary, flaxseed oil supplementation improved the semen quality parameters and fertility of boars in sub-tropical climate by improving the antioxidant capacity and altering the fatty acid composition of seminal plasma.

Genomic Sequencing Reveals the Diversity of Seminal Bacteria and Relationships to Reproductive Potential in Boar Sperm

A number of emerging studies suggest that pathogenic microorganisms in semen may cause a decline in the reproductive potential of spermatozoa, and the bacterial diversity and profile of ejaculated boar semen in different seasons are currently unknown. To explore the bacterial composition and changes in ejaculated boar semen from winter and summer, and the underlying mechanism of decline in sperm quality and fertility capacity in summer, 120 ejaculated semen samples were examined for bacterial communities using genomic sequencing technology, and the associations between microbial composition and sperm reproductive potential were investigated. The results showed that Proteobacteria (57.53%), Firmicutes (31.17%), Bacteroidetes (4.24%), and Actinobacteria (3.41%) are the dominant phyla in the ejaculated semen, and the dominant genera were Pseudomonas (34.41%) and Lactobacillus (19.93%), which belong to the phyla of Proteobacteria and Firmicutes, respectively. Interestingly, the higher diversity of bacteria in ejaculated semen of winter differs from that of summer semen, potentially due to seasonal changes related to changes in semen quality and sperm fertilizing capacity. Furthermore, the highly abundant Lactobacillus in winter samples were positively associated with sperm quality and reproductive performance obtained from sows inseminated with such semen samples, while in contrast, the highly abundant Pseudomonas in summer samples was negatively associated with sperm quality and reproductive potential. Additionally, our results strongly indicated that Lactobacillus is not only a potential probiotic for semen quality and fertility potential but also beneficial for restraining the negative influence of Pseudomonas. Overall, our findings significantly contribute to the current understanding of the phenotypes and etiology of male "summer infertility," and may represent a frontier in male reproductive disorders and possible early prevention against pathogenic bacteria.

Period of Boar Ejaculate Collection Contributes to the Yearly Intra-Male Variability of Seminal Plasma Cytokines

The concentrations of cytokines in seminal plasma (SP) fluctuate over time in healthy males, weakening their practical usefulness as diagnostic tools. This study evaluated the relevance of intra-male variability in SP cytokines and to what extent the period of the year when ejaculate is collected contributes to such variability. Thirteen cytokines (GM-CSF, IFNγ, IL-1α, IL-1β, IL-1ra, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, and TNFα) were measured using the Luminex xMAP^® technology for 180 SP samples of ejaculate collected over a year from nine healthy and fertile boars. The SP samples were grouped into two annual periods according to decreasing or increasing daylight and ambient temperature. Intra-male variability was higher than inter-male variability for all cytokines. All SP cytokines showed concentration differences between the two periods of the year, showing the highest concentration during the increasing daylength/temperature period, irrespective of the male. Similarly, some cytokines showed differences between daylength/temperature periods when focusing on their total amount in the ejaculate. No strong relationship (explaining more than 50% of the total variance) was found between annual fluctuations in SP-cytokine levels and semen parameters. In conclusion, the period of the year during which ejaculates were collected helps explain the intra-male variability of SP-cytokine levels in breeding boars.

Analysis of testicular variables, semen motility and kinematics-derived indexes in boar using a CASA-Mot system

The present study aimed to evaluate differences in area, volume and testicular weight among groups related to breed and age of boar and establish associations between testicular parameters and seminal characteristics. Seminal quality has been studied using computer-assisted semen analysis (CASA) systems that reduce the subjectivity of kinematic parameters. Based on the data obtained through this system, sperm quality indexes and their derived parameters have been assessed to identify a better estimator for determining movement and velocity parameters. We also established indexes of velocity and sperm movement for boar semen. To this end, we evaluated 191 ejaculate samples from 63 boars. Differences related to the effects of season and age on quality boar semen were found (p ≤ .05) in the animal groups. Indexes were established for velocity and sperm movement based on CASA-Mot, and we proposed a sperm movement index (SMI) and sperm velocity index (SVI) with the CASA-Mot variables. Correlations were found (p < .05) among sperm indexes and CASA-Mot variables. Boar characteristics were found to be associated with some CASA-Mot variables, and the estimated SMI and SVI indexes predicted a greater variation in kinematic characteristics compared to the parameters evaluated separately using the CASA-Mot system.

Influence of the age of the individual on the stability of boar sperm genetic material

Routine evaluation of the sperm of livestock animals involves detection of morphological abnormalities. However, most sperm defects that reduce fertilizing capacity are a result of anomalies in spermatogenesis. The aim of the study was to evaluate the effect of a boar's age on the stability of the genetic material of its sperm. The age of the boar was found to have a significant effect on sperm DNA stability and chromatin structure. The highest percentage of spermatozoa with DNA fragmentation was found in the oldest group of boars (0,61%), while the highest proportion of spermatozoa with abnormal histone retention (8,01%) and protamination (9,78%) was found in the youngest group of boars. Aniline blue (AB), chromomycin A3 (CMA3) and acridine orange (AO) staining should be routinely used in individuals used for artificial insemination especially young animals at the start of their exploitation for breeding, as well as older individuals with an age-related decrease in the stability of genetic material. Earlier diagnosis based on additional tests would allow for stricter selection and elimination of males with fertility disorders from breeding, to be replaced by breeders of full value. It was also demonstrated that all three staining methods mentioned above can be used in classical morphological analysis, because they clearly distinguish the sperm head from the background of the slide. Chromomycin staining clearly reveals the midpiece and thus can be used as a specific staining method for its evaluation. Staining with aniline blue is a fast and simple test whose result can be analysed under a light microscope. This staining technique can be recommended for use at insemination stations.

Does advanced age affect reproductive variables, semen composition, and liquid semen storage during different seasons in Boujaâd rams?

The present research was conducted to evaluate the effects of season and age on scrotal circumference (SC), semen characteristics, semen composition, and sperm motility during liquid storage in Boujaâd rams. Semen was collected throughout 1 year from April 2014 to March 2015. Two ram groups, namely older rams including animals aged 5.5 to 6 years of age, and younger rams including animals aged 2.5 to 3 years of age were used. Scrotal circumferences, semen characteristics, and some biochemical variables from semen were measured. After collection and evaluation, the semen was extended in skim milk (SM) at 15 °C to a concentration of 0.8 × 10⁹ spermatozoa/ml. Thereafter, samples were evaluated at different storage times (0, 8, and 24 h). The results indicate that older rams had greater values of SC, lesser semen quality, protein, lipid, and cholesterol concentrations than younger rams. Nevertheless, for both groups there were the least values for semen quality and semen composition in winter. The semen collected from younger rams had greater motility after liquid storage compared with that of the older rams. The least semen quality after liquid storage was recorded in the winter compared with the other seasons of the year for both age groups. In conclusion, results of the present study indicate that older Boujaâd sheep have lesser semen quality, different semen composition than younger rams after liquid storage and during different seasons of the year. Furthermore, there was a strong correlation between semen composition and motility of stored ram semen.

Dependence of physical characteristics of ejaculate of Polish Landrace boars on the time interval between successive ejaculate collections

The aim of the research was to determine the dependence of physical properties of boar ejaculates on the time interval between successive ejaculate collections. The material for the study comprised 1954 ejaculates collected manually from boars used for artificial insemination. For all ejaculates, the ejaculate volume, sperm concentration, percentage of motile spermatozoa, and number of spermatozoa in the ejaculate were determined, and the number of insemination doses per ejaculate was calculated. The boars’ suitability for artificial insemination was evaluated taking into account the effect of the time passed between ejaculate collections. The ejaculate volume and the concentration and number of sperm in the ejaculate were shown to increase with the time elapsed since the previous ejaculate. The number of insemination doses obtained per ejaculate increased as well. Ejaculates with a high sperm count were obtained when the ejaculation frequency was no more than every 4 days. The percentage of spermatozoa with progressive motility increased with the time elapsed since the collection of the previous ejaculate, but only up to 4 days. Further decreases in ejaculation frequency no longer resulted in increased sperm motility.

Linear growth model analysis of factors affecting boar semen characteristics in Southern China

This study investigated the factors affecting the semen traits of boars in Southern China. A total of 172,408 ejaculates of boars from 9 AI centers were collected from January 2013 to May 2016. A linear growth model was used to analyze the effects of leve1 1 (boar breed, age, season, and boar age at herd entry) and level 2 (housing type) factors on semen quality. The intraclass correlation coefficients of semen volume, total sperm number, functional sperm number, sperm concentration, motility, and abnormal sperm were 0.62, 0.62, 0.61, 0.60, 0.54, and 0.70, respectively. Boars reared in ordinary houses had lower total and functional sperm numbers than those reared in air filtration houses ( < 0.05). The functional sperm number of Duroc boars was lower than that of Landrace and Yorkshire boars ( < 0.05). The total and functional sperm numbers were lowest from May to September and peaked at the age of 34.1 and 37.7 mo, respectively. Furthermore, boars aged 8 and 9 mo at herd entry had greater functional sperm numbers than those aged 5, 6, 7, and 12 mo at herd entry ( < 0.05), whereas no significant difference was observed between boars aged 8 mo and boars aged 9 mo at herd entry ( > 0.05). In conclusion, the linear growth model is suitable for longitudinal data analysis. To improve boar breeding, sunstroke prevention in the early spring should be given greater attention. Importantly, 8 mo appears to be the most suitable age for boar introduction, especially for Duroc boars.

Effects of season on boar semen parameters and antioxidant enzymes in the south subtropical region in Brazil

Although boar semen productivity is affected by seasonality, its effects are not equal among different regions which raise concerns regarding the profitability of boar stud farms. Therefore, the goals of this study were (i) to evaluate the seasonal effect on semen production in a commercial boar stud farm located in a subtropical climate region and (ii) to verify whether the activities of superoxide dismutase and glutathione peroxidase in spermatozoa and seminal plasma were associated with seminal traits of fresh and cooled semen. Nine boars were collected twice per season, and routine seminal parameter analyses were performed together with superoxide dismutase and glutathione peroxidase activities in seminal plasma and spermatozoa. Despite a reduction in sperm concentration in spring and summer, most seminal parameters were constant year-round. Temperature-humidity index was higher in the summer compared to spring, autumn and winter (p < .05). Superoxide dismutase activity in spermatozoa was increased in summer compared to autumn and winter (p < .05). The activities of both enzymes in seminal plasma and spermatozoa glutathione peroxidase remained unaltered throughout the seasons. In conclusion, seasonality showed little influence in overall boar seminal parameters despite microclimatic differences among seasons, and spermatozoa collected during summer increased superoxide dismutase activity.