Motility Assessment of Porcine Spermatozoa: a Comparison of Methods

Are There Differences between Methods Used for the Objective Estimation of Boar Sperm Concentration and Motility?

Artificial insemination in the swine industry, as in other species, demands adequate semen handling and accurate evaluation for the preparation of seminal doses. Sperm concentration and motility estimates are part of the semen evaluation process and are considered important for maximizing the yield of doses for insemination. In this study, methods were examined for their accuracy in the estimation of boar sperm concentration and motility. Assessments of sperm concentration were carried out using iSperm^®, ISAS^® v1, Open CASA v2, and the Accuread^® photometer. Analyses of sperm motility were performed with iSperm^®, ISAS^® v1, and Open CASA v2 systems. In this study, boar semen samples were collected from 10 healthy males from two genetic lines. There were no relevant differences between sire lines when sperm concentration was assessed. A Bayesian analysis was applied to the four methods used to assess sperm concentration to examine whether there are relevant differences between them. Results suggested differences in the four methods, with a probability of relevance (PR) of 0.86-1.00. The iSperm^® method revealed higher concentration values within the highest posterior density region at 95% confidence interval (HPD_95%) = 167.0, 224.2 M/mL, whereas Open CASA v2 showed the lowest values, with HPD_95% = 99.3, 155.9 M/mL. The iSperm^® demonstrated higher reliability in measuring sperm concentration compared to other methods or devices within the given range of confidence. ANOVAs revealed relevant differences in the three methods of motility estimation. Overall, differences in boar sperm concentration and motility estimates were found using various methods, but further studies are needed for better characterization of these differences.

In vitro effect of zearalenone on sperm parameters, oocyte maturation and embryonic development in buffalo

The negative impact of zearalenone (ZEN; potent estrogenic mycotoxin) exposure on buffalo embryo production has not yet been determined. In the current study, buffalo sperm and oocytes were exposed to ZEN at different concentrations during maturation. Sperms (with and without ZEN exposure) were incubated for 2 h and evaluated for motility, viability, acrosome integrity, normality, and ultrastructure. Matured oocytes exposed to ZEN were stained to determine their nuclear maturation. Further, their developmental ability was evaluated after in vitro fertilization. Our results showed the toxic effects of ZEN at high concentrations (2000 ng/mL) on different buffalo sperm parameters. The number of acrosome-intact sperm was reduced at 0 h after exposure to a concentration of ≥ 100 ng/mL. Furthermore, the maturation rate of buffalo oocytes (telophase I + metaphase II) was significantly decreased in ZEN-treated oocytes with a higher degeneration rate. Oocytes matured in 1000 ng/mL ZEN and subsequently exhibited considerable reduction in cleavage rate and blastocyst formation compared with control oocytes (2.6% vs. 13.1%). Moreover, the morula rate was decreased (p < 0.001) in ZEN-treated oocytes at concentrations of ≥ 10 ng/mL. Overall, the adverse effects of in vitro ZEN exposure on buffalo sperm parameters and oocyte meiotic progression with a notable reduction in cleavage, morula, and blastocyst rates were defined by these results. Altogether, buffaloes should be considered sensitive to ZEN exposure with respect to their reproductive function.

Effect of zinc on boar sperm liquid storage

Storage and transport of liquid boar sperm for artificial insemination (AI) requires the addition of solutions called extenders, which increase the volume of the ejaculate and help preserve its functional characteristics. Yet, the quality of sperm decreases over time primarily due to the increased production of reactive oxygen species (ROS) that damage the plasma membrane. Many commercial extenders are supplemented with additives that mitigate this effect. In semen, zinc is supplied at high concentration on the seminal plasma and helps protect the plasma membrane of sperm. However, zinc in the seminal plasma is diluted and chelated upon addition of extenders for storage, potentially reducing its antioxidant effect. Here we characterize viability, motility, mitochondrial activity, DNA integrity and ROS content of boar sperm diluted with Sus (Medi Nova, Italy) extender supplemented with different concentrations of ZnCl₂, at intervals after dilution during 3 days. The ability of sperm supplemented with 2 mM ZnCl₂ to fertilize oocytes in vivo of was also tested. Sperm viability was over 82% for all treatments. Mitochondrial integrity analysis, measured by Cytochrome c activity, indicated a protector effect of Zn, noted as a reduced number of sperm with extensive loss of mitochondrial activity. Acrosomal integrity was improved by treatment with all concentrations of ZnCl₂ tested. Sperm kinematics were affected by treatment with ZnCl₂, showing higher percentage of progressive and rapid sperm in doses supplemented with 2mM ZnCl₂. ROS levels and chromatin integrity did not show differences between ZnCl₂-supplemented doses and the control. Fertilization rate, total number, live, still born and mummified piglets did not change when sperm were diluted with extender containing 2 mM ZnCl₂. The presented characterization indicates that Zn addition to Sus extender have a protective effect on mitochondrial sheath and acrosomal membranes; and provides the basis for further studies aimed to optimize sperm performance in AI.

Boar sperm quality and oxidative status as affected by rosmarinic acid at 17 °C

Peroxidation damage induces sublethal injury to boar sperm during preservation. Rosmarinic acid (RA) has already been verified to efficiently protect cells from oxidant-induced injury and to produce significant effect on cryopreservation of semen. Through our experiments, we aim at investigating whether RA has a positive effect on the preservation of pig semen at room temperature. The semen collected from sexually mature Large White boars were preserved at 17 °C in Beltsville thawing solution (BTS) supplied. The boar sperm were exposed to 0, 25, 50, 75, 100, 125 and 150 μM RA in vitro and the sperm functions were examined. The sperm motility, the acrosome and plasma membrane integrity, the catalase activity (CAT), the total antioxidative capacity (T-AOC) activity and the malondialdehyde content (MDA) were examined at 0, 1, 3 and 5 days. The BTS diluent containing RA improved the sperm quality during the process of liquid preservation compared with the control treatment. After 5 days of liquid preservation, the addition of RA at 100 μM produced an optimal effect on the survival time as well as on the maintenance of motility, acrosome and plasma membrane integrity; T-AOC activity; CAT activity; and the MDA content. Besides, our results in the reproductive experiments showed that the addition of RA at 100 μM to the BTS diluent increased the pregnancy rate. These results suggest that the proper concentration of RA in boar semen extenders possibly improves the artificial insemination efficiency by reducing the sperm damage and the subsequent dysfunction during liquid preservation in swine production systems.

Combined effect of type and capture area of counting chamber and diluent on Holstein bull sperm kinematics

The evaluation of sperm motion is crucial for processing of seminal doses for artificial insemination. Here, the combined effect of the type and capture area of three counting chambers, together with the type of diluent employed, on sperm motility was analysed. Ejaculates from thirteen Holstein bulls were used for sperm kinematic analysis with the ISAS^® v1 CASA-Mot system, using two capillary-loaded counting chambers (Leja^® and Cell-Vu^® ) and one drop displacement chamber (Makler^® ). Nine fixed positions were analysed per chamber type, considering central and lateral and three longitudinal fields. Independent of the diluent used, differences were found between the three chambers. Independent of the extender, no differences in x-axis were observed with Cell-Vu^® , while using Leja^® , some parameters showed lower values in the centre than in lateral areas. In both counting chambers, the lowest values were observed in the distal area. Results obtained with the two diluents were highly different with a very low correlation between them. In conclusion, the capture area inside the chambers leads to significant changes in sperm kinematic parameters and different dilution media introduce considerable differences in the motility patterns. It is necessary to optimise sampling methods and specific set-ups to be used with CASA-Mot technology.

Protective Effects of Quercetin Against Cadmium Chloride-Induced Oxidative Injury in Goat Sperm and Zygotes

Quercetin, a plant-derived flavonoid, is frequently used as an antioxidant for efficient anti-oxidative capacity. However, whether quercetin has protective effects on goat sperm and preimplantation embryos against Cd²⁺-induced oxidative injury is still unclear. So, we researched the influence of quercetin on goat sperm and zygotes respectively under the oxidative stress induced by Cd²⁺. In our study, quercetin decreased the malonaldehyde (MDA) and reactive oxygen species (ROS) levels caused by Cd²⁺ in goat sperm (p < 0.05), which facilitated sperm characteristics including motility, survival rates, membrane integrity, and mitochondria activity during storage in vitro and subsequent embryo development (p < 0.05). Moreover, in goat zygotes, quercetin decreased peroxidation products including ROS, MDA, and carbonyl through preserving or maintaining mitochondrial function, gene expression, and anti-oxidative products such as glutathione peroxidase, superoxide dismutase, and catalase, which ameliorated subsequent embryo development and embryo quality (p < 0.05). Taken together, these results suggest that quercetin protects both goat sperm and preimplantation embryos from Cd²⁺-induced oxidative stress.

Prognostic value of post thaw semen quality parameters, mitochondrial integrity and cholesterol content of sperm membrane vis-à-vis conception rate in Frieswal bulls

The present study aimed to analyze the quantitative relationship of membrane cholesterol content (Chol content), mitochondrial integrity (Δψm), and quality parameters of spermatozoa (SQP) at post-thaw stage with conception rate (CR) and estimated relative conception rate (ERCR) in Frieswal bulls. For the experiment, frozen semen straws (32) were collected from the SF laboratory and CR (Total insemination 3482) was obtained from Field Progeny Testing units. Based on the CR, bulls were grouped into low, medium or high groups (G I, G II and G III, respectively). SQP, viz. viability (Eosin Nigrosin), post thaw motility, biochemical integrity of the membrane (HOS res), acrosome integrity (Giemsa, and fluorochromes fluorescein isothiocyanate Pisum sativum agglutinin and propidium iodide, respectively), chol-content, and Δψm using fluorescent probe JC-1 (5,5’,6,6’-tetrachloro- 1,1’,3,3’-tetraethylbenzimi-dazolylcarbocyanine iodide) were determined. The values thus obtained were subjected to the stepwise regression analysis using the least squares principles for each group, and the CR and ERCR were regressed on the various SQP. Pearson’s correlation coefficients were estimated between the CR and ERCR values and the various SQPs. The coefficient of determination (R2) moderately higher for all the models and ranged from 63.70–93.40% (high and medium group, respectively). High R2 value of the prediction equation for the herd and bulls with medium CR (75.9 and 93.4%, respectively) reveal their suitability to predict the CR and ERCR potential of the cryopreserved semen. Study results point to inclusion of cholesterol content and Δψm estimation in routine semen analysis before long-term storage or usage for insemination purposes.

A Simple Confocal Microscopy-based Method for Assessing Sperm Movement

In the field of reproductive medicine, assessment of sperm motility is a key factor for achieving successful artificial insemination, in vitro fertilization, or intracellular sperm injection. In this study, the motility of boar sperms was estimated using real-time imaging via confocal microscopy. To confirm this confocal imaging method, flagellar beats and whiplash-like movement angles were compared between fresh and low-temperature-preserved (17℃ for 24 h) porcine sperms. Low-temperature preservation reduced the number of flagellar beats from 11.0±2.3 beats/s (fresh sperm) to 5.7±1.8 beats/s and increased the flagellar bending angle from 19.8°±13.8° (fresh) to 30.6°±15.6°. These data suggest that sperm activity can be assessed using confocal microscopy. The observed motility patterns could be used to develop a sperm evaluation index and automated confocal microscopic sperm motility analysis techniques.

Effect of chamber characteristics, loading and analysis time on motility and kinetic variables analysed with the CASA-mot system in goat sperm

Several factors unrelated to the semen samples could be influencing in the sperm motility analysis. The aim of the present research was to study the effect of four chambers with different characteristics, namely; slide-coverslip, Spermtrack, ISAS D4C10, and ISAS D4C20 on the sperm motility. The filling procedure (drop or capillarity) and analysis time (0, 120 and 240s), depth of chamber (10 or 20μm) and field on motility variables were analysed by use of the CASA-mot system in goat sperm. Use of the drop-filling chambers resulted in greater values than capillarity-filling chambers for all sperm motility and kinetic variables, except for LIN (64.5% compared with 56.3% of motility for drop- and capillarity-filling chambers respectively, P<0.05). There were no significant differences in total sperm motility between different chamber depths, however, use of the 20μm-chambers resulted in greater sperm progressive motility rate, VSL and LIN, and less VCL and VAP than chambers with a lesser depth. There was less sperm motility and lesser values for kinetic variables as time that elapsed increased between sample loading and sperm evaluation. For sperm motility, use of droplet-loaded chambers resulted in similar values of MOT in all microscopic fields, but sperm motility assessed in capillarity-loaded chambers was less in the central fields than in the outermost microscopic fields. For goats, it is recommended that sperm motility be analysed using the CASA-mot system with a drop-loaded chamber within 2min after filling the chamber.

A critical assessment of the effect of serine protease inhibitors on porcine fertilization and quality parameters of porcine spermatozoa in vitro

Proteases play an important role during mammalian fertilization. Their function is frequently investigated using specific inhibitors. We analyzed four serine protease inhibitors [4-(2-aminoethyl) benzene sulfonyl fluoride hydrochloride (AEBSF), soybean trypsin inhibitor from glycine max (STI), Nα-tosyl-L-lysine-chloromethyl ketone hydrochloride (TLCK) and N(p)-tosyl-L-phenylalanine-chloromethyl ketone (TPCK)] for their in vitro effect on fertilization and sperm quality in pigs. Inhibitor concentrations were chosen based on the reduction of fertilization rate during preliminary dose-response experiments with cryopreserved epididymal spermatozoa. The inhibitor effects on in vitro fertilization (IVF) and sperm parameters (membrane and acrosomal integrity, motility and mitochondrial membrane potential - MMP) were evaluated using diluted fresh semen. AEBSF (100 μM), TLCK (100 μM) and TPCK (100 μM) decreased total fertilization and polyspermy rates by at least 50%. STI (5 μM) lowered total fertilization rates but not the level of polyspermy. AEBSF and TPCK reduced fertilization parameters to a similar degree using cryopreserved epididymal spermatozoa (dose-response experiment) or diluted fresh semen. Inhibition by STI was more pronounced using cryopreserved epididymal spermatozoa, whereas TLCK inhibited IVF only with diluted fresh semen. AEBSF and STI had no effect on sperm parameters, and TLCK significantly reduced motility. TPCK diminished MMP and motility and affected membrane and acrosomal integrity in a negative way. In summary, serine protease inhibitors differed in the way they reduce the fertilization rate. These results emphasize the necessity of inhibitor testing before they can be applied in fertilization studies. AEBSF and STI can be used in the future IVF studies without compromising sperm quality.

Ram spermatozoa migrating through artificial mucus in vitro have reduced mitochondrial membrane potential but retain their viability

Sperm motility in vitro is one of the most common predictors of fertility in male screening. We propose that a mucus-penetration assay can isolate a cellular subpopulation critical to reproductive success. To this end, a device was designed with three modules (sample, test and collection) and its conditions of use evaluated (length of mucus, incubation time, mucus medium, sperm concentration and position in relation to the horizontal). The number of spermatozoa migrating and the viability and acrosomal status of the spermatozoa not migrating were calculated. The second objective was to evaluate the qualitative parameters of the spermatozoa migrating in 1.6% polyacrylamide for 30 min. The number of spermatozoa migrating and the sperm motility, viability and the acrosomal and mitochondrial status of three sperm populations (fresh, not migrating and migrating) were determined. A higher number of migrating spermatozoa were observed after 60 min of incubation, but this situation adversely affected sperm quality. The methylcellulose-based test showed a significantly lower number of migrating spermatozoa than the polyacrylamide test. The position at an angle of 45° resulted in a higher number of migrating spermatozoa in the polyacrylamide-based test. The sperm counts for three consecutive assays indicated an acceptable repeatability of the method. The viability and acrosomal status of the migrating spermatozoa showed no significant changes with regard to the control when the device was placed at 45°, whereas these parameters showed lower values at 0°. The percentage of high mitochondrial membrane potential spermatozoa was significantly reduced in the population of migrating spermatozoa.

Boar seminal plasma components and their relation with semen quality

Select boar seminal plasma (SP) components and their relation to semen quality were investigated. Thirty nine boars from three artificial insemination (AI) centers were divided into group A (GA: > 80% normal sperm and >70% motility) and group B (GB: < 80% normal sperm and < 70% motility). Each ejaculate was collected and semen volume, concentration, sperm motility (computer aided semen analysis; CASA), morphology, and vitality (both eosin nigrosin staining) were investigated. The SP was separated and analyzed for aspartate-amino-transferase (AST), γ-glutamyl-transferase (GGT), alkaline phosphatase (ALP) activity, and the concentrations of sodium (Na), potassium (K), chloride (Cl), calcium (Ca), phosphate (PO(4)(3-)), magnesium (Mg), selenium (Se) and zinc (Zn) were assessed. Repeated measures (2 months interval) were conducted in eight boars of GA from one AI center. The activity of GGT (r = -0.482) and ALP (r = -0.459) was moderately associated (p < 0.05) with ejaculate volume and strongly associated with concentration (r = 0.580 and r = 0.618, respectively; p = 0.000). Moderate associations (p < 0.05) were found between ALP (r = 0.439), GGT (r = 0.387), Na (r = -0.428), K (r = 0.354), and Se (r = 0.354) with progressive motility. The SP concentration of Na (r = -0.401), Cl (r = -0.521), and K (r = 0.350) was associated (p < 0.05) with normal morphology. Only Mg was associated (p < 0.05) with membrane damage (r = -0.335). The concentration of Na, Cl, and Zn (1681.0 vs. 1701.0 µg/dL) was different between groups (p < 0.05). Repeated measures showed significant differences in time but only for Na, Mg, and Zn (p < 0.05). In conclusion, several biochemical components of SP were related to semen quality. The analysis of biochemical parameters could provide extra information about reproductive health of AI boars.

Effect of active immunization against GnRH on testosterone concentration, libido and sperm quality in mature AI boars

Background

The aim of the present study was to investigate the efficacy of the Improvac on testosterone concentration in blood serum, sexual behavior and sperm quality in matured AI boars. A total of nine Danish Landrace AI boars were included in the analysis.

Methods

The trial period lasted for 15 weeks and was divided into four periods: Control period: three weeks before vaccination; Period I – four weeks after first vaccination; Period II – four weeks after second vaccination, Period III – four weeks after third vaccination. Blood and sperm samples were collected at weekly intervals. Freshly collected sperm samples were analyzed.

Results

Testosterone concentration correlated with libido (r = 0.531; p < 0.001), volume of ejaculate (r = 0.324; p < 0.001) and the percentage of morphologically normal spermatozoa (r = 0.207; p < 0.05). Testosterone concentration rised significantly (p < 0.05) in 5–6 week of trial, e. i. after the first dose of Improvac and after this peak the level of testosterone further progressively decreased (p < 0.05).

Conclusions

Results from this study indicate that active immunization of sexually matured boars against GnRH has negative impact on testosterone concentration, sexual behavior, volume of ejaculate and total number of normal spermatozoa in ejaculate.

Normal reproductive development of offspring derived by intracytoplasmic injection of porcine sperm grown in host mice

For establishment of gonadal xenografting, it is essential to clarify whether offspring derived from gametes grown in host mice harboring xenografts have normal reproductive development. This study examined the secretory profiles of gonadal hormones in relation to sexual maturation or ovarian cyclicity in pigs generated by intracytoplasmic sperm injection using xenogeneic sperm (Xeno-ICSI pigs, four males and one female). We also assessed the developmental activity of gametes obtained from these pigs using in vitro culture systems, or by mating with conventionally produced (conventional) pigs. During the growth of male Xeno-ICSI pigs, serum inhibin and testosterone concentrations were generally within ranges for those hormones in conventional pigs. Histologically, there were no differences in the growth and differentiation of seminiferous tubules between Xeno-ICSI and conventional pigs. Parameters of semen quality, including volume, pH, sperm concentration, and the percentage of motile sperm were not different from those in conventional pigs. Among the Xeno-ICSI pigs, individual differences were noted in the ability of sperm to penetrate oocytes and to produce blastocysts. However, oocytes after in vitro fertilization using these sperm developed into blastocysts containing more than 31 cells. One conventional sow delivered 12 piglets after being mated with a male Xeno-ICSI pig. During growth of the female Xeno-ICSI pig, serum progesterone concentrations had a sudden increase at 41 wk of age, suggesting CL formation. After puberty, this animal showed cyclic changes in the serum concentrations of progesterone and inhibin, and delivered 10 piglets after AI using fresh sperm obtained from a conventional boar. In conclusion, these findings demonstrated that both male and female Xeno-ICSI pigs had normal reproductive abilities.

Field data analysis of boar semen quality

This contribution provides an overview of approaches to correlate sow fertility data with boar semen quality characteristics. Large data sets of fertility data and ejaculate data are more suitable to analyse effects of semen quality characteristics on field fertility. Variation in fertility in sows is large. The effect of semen factors is relatively small and therefore impossible to find in smaller data sets. Large data sets allow for statistical corrections on both sow- and boar-related parameters. Remaining sow fertility variation can then be assigned to semen quality parameters, which is of huge interest to AI (artificial insemination) companies. Previous studies of Varkens KI Nederland to find the contribution to field fertility of (i) the number of sperm cells in an insemination dose, (ii) the sperm motility and morphological defects and (iii) the age of semen at the moment of insemination are discussed in context of the possibility to apply such knowledge to select boars on the basis of their sperm parameters for AI purposes.

Effects of dietary supplementation with an organic source of selenium on characteristics of semen quality and in vitro fertility in boars

Semen characteristics in boars fed organic or inorganic sources of Se were assessed in 3 experiments. Crossbred boars were randomly assigned at weaning to 1 of 3 dietary treatments: I) basal diets with no supplemental Se (control), II) basal diets with 0.3 mg/kg of supplemental Se from an organic source (Sel-Plex, Alltech Inc., Nicholasville, KY), and III) basal diets supplemented with 0.3 mg/kg of supplemental Se from sodium selenite (Premium Selenium 270, North American Nutrition Co. Inc., Lewisburg, OH). For Exp. 1, semen was collected from boars (n = 10/dietary treatment) on 5 consecutive days at 15 mo of age. Effects of treatment × day were detected for the proportions of progressively motile (P = 0.02) and rapidly moving (P = 0.03) spermatozoa, and measures of sperm velocity, including path velocity of the smoothed cell path (P = 0.05) and average velocity measured in a straight line from the beginning to the end of the track (P = 0.05). Negative effects of day of semen collection on sperm motility were least pronounced in boars fed Sel-Plex. Experiment 2 was conducted when boars were 17 mo of age, and semen was collected (n = 10 boars/dietary treatment), diluted in commercially available extenders, and stored at 18°C for 9 d. Effects of treatment × day were detected for percentages of motile (P = 0.01) and static (P = 0.01) spermatozoa, amplitude of lateral head displacement (P = 0.02), frequency with which the sperm track crossed the sperm path (P = 0.04), straightness (P = 0.01), and average size of all sperm heads (P = 0.03). In general, sperm cells from boars fed Sel-Plex were better able to maintain motility during liquid storage compared with boars fed sodium selenite. For Exp. 3, semen was collected from boars (n = 6/dietary treatment) at 23 mo of age, and spermatozoa were evaluated at d 1 and 8 after semen collection using in vitro fertilization procedures. There was a tendency for an effect (P = 0.11) of dietary treatment on fertilization rate with Sel-Plex-fed boars having the greatest value (70.7%). The results of this study suggest that there are positive effects of dietary supplementation with Sel-Plex on boar semen characteristics and that organic Se supplementation may help ameliorate the negative effects of semen storage on characteristics of sperm motility.

A preliminary study on using autologous and heterologous boar sperm supernatant from freezing processes as post-thawing solution: its effect on sperm motility

The aim of this study was to evaluate the effect of post-thawing dilution with autologous and heterologous sperm supernatant on motility of frozen-thawed boar spermatozoa. During the cryopreservation, sperm supernatant (a combination of seminal plasma and semen extender, 50% v/v) or seminal plasma from nine boars (Duroc, Large White, and Landrace; three in each) was collected by centrifugation and stored frozen until use as post-thawing solution. Sperm pellets were further processed and cryopreserved using control-rate freezer and was thawed at 50°C for 12 s. After thawing, frozen thawed semen samples were diluted with seminal plasma (group A), supernatant from Landrace (group B), supernatant from Large White (group C), supernatant from Duroc (group D), and Modena™ semen extender (group E). Post-thawing motility was evaluated using a phase-contrast microscope after thawing at 1, 10, 20, and 30 min. The present results show that at 1 min, a significantly higher percentage (P ≤ 0.001) of progressive motility was found in groups B (53.3%) and C (53.9%) than the other groups. At 10 min, the highest (P ≤ 0.001) progressive motility was found in groups B (65%) and C (61%). At 20 and 30 min, a significantly higher percentage (P ≤ 0.001) of progressive motility was found in groups B (58.9%), C (53.5%), and D (45.6%) than groups A (3.9%) and E (20.6%). It can be stated that supernatant from the freezing processes (consisting of seminal plasma and Modena™, 50% v/v) had a beneficial effect on post-thawing progressive motility of frozen boar semen.

How to evaluate and quantify the influence of coincidence on fertility and herd health parameters? A practical overview of frequently used and abused statistical techniques in research and practice

In this article, frequently encountered statistical questions and methods used both in research and in daily practice are described and explained. First, the concepts of variability and uncertainty are explained and illustrated. From this, it is explained how variation can be quantified and how the limits of what can be expected as a result of normal variation are determined both for continuous and binary data. Based on the basic concepts of probability theory, an introduction to risk assessment was given. Finally it is explained how to test whether individual observations lie outside the normal range or the test whether populations are different from each other. All these are carried out avoiding theory and formulas as much as possible and illustrated with real examples from reproduction and herd health.

Influence of seminal plasma on the kinematics of boar spermatozoa during freezing

Sperm motility is, for its relation to cell viability and fertility, a central component of the spermiogram, where consideration of motion patterns allows discrimination of sub-populations among boar spermatozoa. Extension and cryo-preservation imposes changes in these patterns in connection to handling, additives, temperature changes and the removal of boar seminal plasma (BSP) which apparently makes spermatozoa susceptible to oxidative stress, thus affecting survival and motility post-thaw. Detailed kinematic analyses during sperm cooling are sparse, particularly when considering the instrumentation and settings used for analyses, the effect of extenders, and of the BSP the processed spermatozoa are exposed to. Spermatozoa present in the first collectable 10mL of the sperm-rich fraction of the ejaculate (portion 1, P1-BSP), have shown an increased ability to sustain motility during and after cryo-preservation than spermatozoa immersed in the rest of the ejaculate (portion 2, P2). When P2-spermatozoa were cleansed from their BSP and exposed for 60min to pooled P1-BSP, their motility post-thaw increased to similar levels as P1-spermatozoa. This BSP-influence is sire-dependent, presumably related to the protein concentration in the different ejaculate portions, and apparently unrelated to changes in membrane integrity or membrane stability through conventional, controlled cooling.

Determination of high mitochondrial membrane potential in spermatozoa loaded with the mitochondrial probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1) by using fluorescence-activated flow cytometry

A flow cytometric method was developed to identify viable, energized sperm cells with high mitochondrial inner transmembrane potential (Deltapsi(m)), >80-100 mV using the mitochondrial probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) and the impermeant nuclear stain propidium iodine (PI). This flow cytometric method is described in detail here. When in contact with membranes possessing a high Deltapsi(m), JC-1 forms aggregates (J(agg)) that are fluorescent at 590 nm in response to 488 nm excitation. We found that the reactive oxygen species generator, menadione reduced sperm motility and reduced Deltapsi(m) in a dose responsive fashion that was closely correlated with the loss of motility.

Use of fluorescence-activated flow cytometry to determine membrane lipid peroxidation during hypothermic liquid storage and freeze-thawing of viable boar sperm loaded with 4, 4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid1

Part of the reduction in boar sperm motility and fertility associated with hypothermic liquid storage and cryopreservation may be due to membrane lipid peroxidation. Lipid peroxidation was monitored by the shift from red to green fluorescence emission of the lipophilic probe 4, 4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid, C(11)BODIPY(581/591) (BODIPY), as measured by fluorescence-activated flow cytometry in live sperm (negative for propidium iodide). Experiments were conducted with Percoll-washed sperm to determine the specificity of BODIPY oxidation in the presence of different reactive oxygen species generators and metal chelators. Compared with no FeSO(4) and Na ascorbate, the combination of FeSO(4) and Na ascorbate (FeAc) increased (P < 0.01) the percentage of sperm containing oxidized BODIPY from <or=1 to >70% and increased (P < 0.05) BOD-IPY fluorescence intensity/cell by 5- to 10-fold after a 30-min incubation. Motility was depressed (P < 0.05) after exposure to FeAc, but viability was not affected. Of the reactive oxygen species generators tested, BODIPY oxidation was specific for FeAc, because menadione and H(2)O(2) had little or no effect. The oxidization of hydroethidine to ethidium was specific for menadione and H(2)O(2); FeAc had no effect. The presence of the metal chelators EDTA or deferoxamine mesylate at 3 and 9 muM inhibited FeAc-induced BODIPY oxidation and maintained motility. Experiments were conducted to determine the effect of liquid storage at 17 degrees C for 1 and 5 d and the effect of freeze-thawing on basal and FeAc-induced BODIPY oxidation. Basal BODIPY oxidation (no FeAc) was low in liquid stored and thawed viable sperm (1.3 and 3.4%, respectively). Although the incidence of basal or spontaneous membrane lipid peroxidation was low during liquid storage and after freeze-thawing, viable boar sperm were susceptible to FeAc-induced lipid peroxidation.

Measuring mouse sperm parameters using a particle counter and sperm quality analyzer: A simple and inexpensive method

This study examined a method for analyzing the count, motility, and morphology of mouse epididymal sperm, optimizing the diluent, incubation time, sample concentration, and temperature, using a particle counter (CDA-500) to count and size sperm and a sperm quality analyzer (SQA-IIC) to measure sperm motility, quantified as the sperm motility index (SMI). The optimal conditions consisted of a 30-min incubation in D-MEM (Dulbecco's modified Eagle's medium; considering cost and availability) at 37 degrees C, with 5 x 10(6)cells mL(-1) in the original solution. Furthermore, the influence of formalin fixation, and the correlation between the automated counter and a manual method were investigated. The sample fixation had no marked effect on the sperm count or morphology assessment. A linear correlation was observed between the manual and automated methods (y=0.920x +0.276; r(2)=0.571; p<0.001; range: (3-6) x 10(6)). The suitability of the proposed method was confirmed using spermatozoa prepared from mice treated with the reproductive toxin diethylstilbestrol (DES). Using sperm from the cauda epididymidis on one side per mouse, we confirmed that measurement of these sperm parameters using the two devices was simple, rapid, inexpensive, and reproducible.

Development of a protocol for multiple staining with fluorochromes to assess the functional status of boar spermatozoa

The aim of this study was to design a simple and reliable method for the simultaneous evaluation of the nucleus, the acrosome, and the mitochondrial sheath of boar spermatozoa. Sperm samples coming from healthy and sexually mature Pietrain boars were incubated with two nuclear fluorochromes--bis-benzamide specific for viable cells, and propidium iodide specific for nonviable cells--the fluorochrome Mitotracker Green FM specific for functional mitochondria, and the lectin Trypsin inhibitor from Soybean (SBTI) conjugated with the fluorochrome Alexa Fluor 488 specific for proacrosin. The results obtained from assessing the functional status of the spermatozoa using fluorochromes were compared with the conventional sperm parameters of sperm vitality using the eosin exclusion test (EE test), and sperm motility and morphology using the computer-assisted semen analyzer SCA 2002Producció. Applying the multiple staining test, it was found that the frequency of viable spermatozoa with intact acrosome and intact mitochondria was not different from the frequency of viable spermatozoa obtained with the EE test, and also correlated positively with the frequency of motile spermatozoa and the frequency of mature spermatozoa. Therefore, this technique is useful to characterize the status of boar spermatozoa by assessing the nuclear, acrosomal, and mitochondrial integrity. Moreover, it provides reliable diagnostic information about the fertility potential of boars.