Boar spermatozoa in the oviduct

Fertilization rate and number of embryos on day 2 after intrauterine and deep intrauterine insemination using frozen-thawed boar semen in multiparous sows

The present study determines fertilization rate and number of embryos on Day 2 after intrauterine insemination (IUI) and deep intrauterine insemination (DIUI) using frozen-thawed (FT) boar semen in multiparous sows. Twelve crossbred Landrace × Yorkshire multiparous sows were included. The sows were inseminated at 24 h after oestrus detection and reinseminated every 12 h until ovulation took place. The inseminations were conducted using IUI with 2 × 10⁹ FT sperm per dose (n = 6) and DIUI with 1 × 10⁹ FT sperm per dose (n = 6). The sows were slaughtered at 45.1 ± 7.2 h after ovulation. Embryos and unfertilized oocytes were flushed from the oviducts. IUI yielded a better fertilization rate than DIUI (66.0% versus 31.0%, P < .001). The number of embryos was 13.5 ± 2.7 and 6.6 ± 3.2 embryos/sow in IUI and DIUI groups, respectively (P = .08). The proportion of sows having unilateral fertilization was higher in the DIUI (3/5) than the IUI group (1/6). In conclusion, IUI with at least 2 × 10⁹ total number of FT boar spermatozoa is recommended.

Cytokine expression in the gilt oviduct: effects of seminal plasma, spermatozoa and extender after insemination

Effects of semen components [fresh semen in extender, spermatozoa in extender (Spz), seminal plasma (SP)], or extender alone (Beltsville thawing solution, BTS) on the expression of selected cytokines [interleukin (IL)-1beta, IL-6, IL-10 and transforming growth factor (TGF)-beta1)] as well as the presence of cells positive for CD8 or CD25 were studied in the pig oviduct. In addition, cytokines in SP and oviductal flushings were analyzed. In experiment (Exp) I, groups of gilts were sampled at 5-6h after insemination with SP, Spz, fresh semen in BTS or only BTS (control). In Exp II, gilts were sampled 35-40 h after insemination with SP, Spz, BTS or only catheter insertion (control). Most oviductal flushing samples were positive (> or =detectable limits) for IL-10 and TGF-beta1 but only few for IL-6. The IHC-labelling of IL-6, IL-10 and TGF-beta1 was evident, especially in the epithelial cells of the isthmus and infundibulum as well as in the cells of the regional (mesometrial) lymph node. Cilia of the epithelium were positive for IL-6 (strongest in the infundibulum) and TGF-beta1 (strongest in the isthmus) but negative for IL-10. There were no consistent differences in IHC-labelling of the cytokines in relation to different treatments, except at 35-40 h after insemination (Exp II), when IL-6 was slightly higher in epithelium of the SP group and IL-10 in the infundibular connective tissue was higher in the SP and Spz groups. In the isthmus and infundibulum, there were no differences between animals inseminated with BTS (control) and the semen components for any of the cytokine mRNAs at 5-6h after insemination (Exp I). However, later (35-40 h, Exp II), insemination with SP, Spz and BTS alone appeared to up-regulate TGF-beta1 mRNA expression compared with the control group (without any fluid infused). In all treatment groups, the mRNA level for TGF-beta1 was higher than for IL-1beta, IL-6 and IL-10. Higher mRNA levels of all cytokines were found in the isthmus compared with the infundibulum. Numbers of CD8-positive cells (both in epithelium and connective tissue) appeared higher in the infundibulum compared with the isthmus and were mostly higher shortly (Exp I) after treatment with SP, SPZ and BTS than later (Exp II) in both segments. CD25-positive cells were few and found solely in the sub-epithelial connective tissue. The results indicate that in the porcine oviduct, IL-6, IL-10 and TGF-beta1 are endogenous produced and that TGF-beta1 may have a more important role for immunomodulation than the other cytokines, especially in isthmus. Differences between isthmus and infundibulum in cytokine mRNA expression and in presence of CD8-positive cells indicate different patterns of immune reactivity in the upper and lower parts of the oviduct.

Seminal plasma proteins inhibit in vitro- and cooling-induced capacitation in boar spermatozoa

Dilute boar seminal plasma (SP) has been shown to inhibit in vitro capacitation and cooling-induced capacitation-like changes in boar spermatozoa, as assessed by the ability of the spermatozoa to undergo an ionophore-induced acrosome reaction. We hypothesised that the protein component of SP is responsible for this effect. To test this hypothesis, varying concentrations of total SP protein or SP proteins fractionated by heparin binding were assayed for their ability to inhibit in vitro capacitation, as well as cooling- and cryopreservation-induced capacitation-like changes. In vitro capacitation and cooling-induced capacitation-like changes were prevented by 10% whole SP, as well as by total proteins extracted from SP at concentrations greater than 500 μg mL−1. No amount of SP protein was able to prevent cryopreservation-induced capacitation-like changes. Total SP proteins were fractionated based on their heparin-binding properties and the heparin-binding fraction was shown to possess capacitation inhibitory activity at concentrations as low as 250 µg mL−1. The proteins in the heparin-binding fraction were subjected to mass spectrometry and identified. The predominant proteins were three members of the spermadhesin families, namely AQN-3, AQN-1 and AWN, and SP protein pB1. We conclude that one or more of these heparin-binding SP proteins is able to inhibit in vitro capacitation and cooling-induced capacitation-like changes, but not cryopreservation-induced capacitation-like changes, in boar spermatozoa.

Spermadhesin PSP-I/PSP-II heterodimer induces migration of polymorphonuclear neutrophils into the uterine cavity of the sow

Seminal plasma (SP) is a complex fluid which exerts biological actions in the female reproductive tract. In pigs, SP elicits endometrial inflammation and consequent immune changes after mating. This study tested whether heparin-binding spermadhesins (HBPs) and the heterodimer of porcine sperm adhesions I and II (PSP-I/PSP-II) in SP recruit different lymphocyte subsets (CD2(+), CD4(+) and CD8(+) T cells) or polymorphonuclear leukocytes (PMNs) to the superficial endometrium or luminal epithelium and lumen, respectively, of oestrous sows. In Experiment 1, endometrial biopsies were taken between 2 and 120 min after infusion of uterine horns with HBPs, PSP-I/PSP-II or saline and evaluated by immunohistochemistry or histology. In Experiment 2, the uterus of oestrous sows was infused with PSP-I/PSP-II or saline to assess PMN numbers in the uterine lumen 3h later. PSP-I/PSP-II elicited CD2+ T cell recruitment from 10 min, and CD8(+) T cells from 60 min after infusion, while HBPs increased CD4(+) T cell recruitment by 120 min. PSP-I/PSP-II but not HBPs induced PMN migration to the surface epithelium by 10 min. PMN numbers were elevated 5-fold by 30 min and 7-fold from 60 min, with PMNs detectable in the lumen from 30 min after infusion. Six-fold more PMNs were collected from the uterine lumen of PSP-I/PSP-II-infused sows compared to controls at 3h after infusion. These data show that PSP-I/PSP-II heterodimer in seminal plasma has a predominant role in triggering the recruitment of uterine PMNs and T cells after mating, initiating a cascade of transient and long-lasting immunological events.

The vanguard sperm cohort of the boar ejaculate is overrepresented in the tubal sperm reservoir in vivo

In boars, sperm cohorts are sequentially emitted in epididymal cauda fluid and resuspended in different mixtures of accessory sex gland secretions while ejaculated in various fractions. During natural mating, these ejaculate fractions sequentially enter the cervix-uterine lumen, are quickly transported towards the tips of the uterine horns and colonize the oviductal sperm reservoirs (SR). Using a simple experiment, we tested the hypothesis that the first ejaculated sperm subpopulation (fortuitously present in the peak portion of the sperm-rich fraction [SRF], the so-called Portion 1, P1) is, by reaching first the SR, overrepresented there. Spermatozoa from P1- and of P2- (last portion of the SRF and the Post-SRF) were collected from 3 fertile boars. P1-spermatozoa were fluorophore DNA-stained, while P2-spermatozoa were kept unstained. Weaned estrous sows were conventionally inseminated (12 h after onset of estrus) with similar sperm numbers (approx 10 x 10(9) spermatozoa) per portion but in different orders as follows: (i) a mix of P1 and P2 aliquots (control, P1+P2, n=5), or testing (ii) a sequential order (P1-P2, Treatment A, n=5) or (iii) an inverse order (P2-P1, Treatment B, n=5) of cohort AI. Sows were euthanized approx 3 h post-AI, and the SRs were flushed to recover the spermatozoa, which were accounted for as stained or unstained. The total number of spermatozoa flushed did not differ between groups or boars (NS, ranging 0.9 to 2.0 x 10(9)). Sequential, in vivo-like, sperm deposition (P1-P2, Treatment A) yielded the highest proportion of stained P1-spermatozoa in the SRs (59.8 +/- 5.66%, means +/- SEM) compared with when the order was reversed (P2-P1, Treatment B; 15.6 +/- 2.1% P1-spermatozoa, P<0.05) or P1 and P2 sperm suspensions were mixed (control, 36.9 +/- 2.70% P1-spermatozoa, P<0.05). The tested hypothesis proved valid; if inseminated in the same order as ejaculated in vivo, P1-spermatozoa become overrepresented in the SR. The physiological consequences of this skewed SR-colonization are discussed in this paper alongside the advantageous use of P1-spermatozoa for handling, including cryopreservation.

Expression of progesterone receptor in the utero-tubal junction after intra-uterine and deep intra-uterine insemination in sows

The aim of this study was to investigate the expression of progesterone receptor (PR) in the utero-tubal junction (UTJ) of sows at 24 h after intra-uterine insemination (IUI) and deep intra-uterine insemination (DIUI) compared with conventional artificial insemination (AI) in pigs. Fifteen multiparous sows were used: AI (n = 5), IUI (n = 5) and DIUI (n = 5). The sows were inseminated with a single dose of diluted semen during the second oestrus after weaning at 6-8 h prior to ovulation (AI: 3000 × 10(6) spermatozoa, IUI: 1000 × 10(6) spermatozoa and DIUI: 150 × 10(6) spermatozoa). The UTJ was collected and subject to immunohistochemical staining using avidin-biotin immunoperoxidase technique with mouse monoclonal antibody to PR. In the oviductal part of the UTJ, the intensity of PR in the tunica muscularis and the proportion of PR-positive cells in the surface epithelium after DIUI were lower than AI (p < 0.05). The intensity and the proportion of PR-positive cells between AI and IUI in all compartments of the UTJ did not differ significantly (p > 0.05). When comparing between tissue compartments, prominent staining was observed in the muscular layer of the UTJ. It could be concluded that the expression of PR in the UTJ prior to fertilization after DIUI with a reduced number of spermatozoa was lower than that after AI. This might influence sperm transportation and the fertilization process.

Distinct effects of boar seminal plasma fractions exhibiting different protein profiles on the functionality of highly diluted boar spermatozoa

The aim of this study was to evaluate how different protein profiles of seminal plasma (SP) fractions affect sperm functionality in vitro. Ejaculates from three boars were separated into six fractions. The fractions differed from each other in their sperm content, in their total SP protein content, and their spermadhesin PSP-I/PSP-II and heparin-binding protein (HBP) concentrations. Spermatozoa were mainly recovered in fraction 2 (sperm-rich fraction, >1800 x 10(6) spermatozoa/ml), whereas the pre-sperm fraction 1 and the post-sperm fractions 4-6 contained low numbers of spermatozoa (<500 x 10(6)/ml). Except in fraction 2, the total SP protein concentration and the concentration of both, spermadhesin PSP-I/PSP-II and the HBPs increased with fraction order. Distinct time-dependent effects were observed on motility characteristics and membrane integrity of highly diluted boar spermatozoa upon incubation with a 10% dilution of the SP from each fraction. The highest sperm viability was recorded after exposure for 5 h to fraction 2, followed by fractions 1 and 3. The percentages of motile spermatozoa also differed significantly among fractions after 5 h of incubation. Spermatozoa incubated with SP of fractions 1-3 showed the highest percentage motility. We conclude that different SP fractions exert distinct effects on the functionality of highly diluted boar spermatozoa. Fractions 1-3 appear to promote sperm survival, whereas fractions 4-6 seem to be harmful for preserving the physiological functions of highly diluted boar spermatozoa.

Effect of type of semen, time of insemination relative to ovulation and embryo transfer on early equine embryonic vesicle growth as determined by ultrasound

Embryonic vesicle growth in the mare is easily monitored by ultrasound. Apart from pregnancy diagnosis, assessment of the embryonic vesicle in practice is also useful to evaluate its viability. Although subject to individual variation, embryo growth rate follows a constant pattern in the early stages of development in relation to embryonic age. Previous studies have shown a significant effect of some factors routinely used in practice, such as post-ovulation insemination and embryo transfer, on embryonic growth and the time in which the vesicle is first detected. This study attempts to confirm previous results in different settings and characterise the causes for this delay in growth. A total of 159 pregnancies from different mating protocols: (1) pre-ovulation natural mating, (2) pre-ovulation natural mating and transfer into recipient mares, (3) post-ovulation natural mating, and (4) post-ovulation AI with frozen/thaw spermatozoa were evaluated ultrasonographically from day 12 to 19 of pregnancy and vesicle diameters recorded. Regression analysis between embryonic vesicle diameters and embryonic ages was performed for each group and mean vesicle diameter at different age periods among groups were tested for statistical difference with a general linear model of variance. There was no significant difference between groups 1 and 2 (P=0.73) or between groups 3 and 4 (P=0.71). However both pre-ovulation groups (1 and 2) had larger vesicle diameters (P<0.000) at any embryonic age analysed than either of the post-ovulation groups (3 and 4). In conclusion, post-ovulation inseminations produced pregnancies with smaller vesicle diameters equivalent to approximately 1 day's growth.

Fertilization and early embryonic development in the porcine fallopian tube

Fertilization and early embryo development relies on a complex interplay between the Fallopian tube and the gametes before and after fertilization. Thereby the oviduct, as a dynamic reproductive organ, enables reception, transport and maturation of male and female gametes, their fusion, and supports early embryo development. This paper reviews current knowledge regarding physiological processes behind the transport of boar spermatozoa, their storage in and release from the functional sperm reservoir (SR), and of the interactions that newly ovulated oocytes play within the tube during their transport to the site of fertilization. Experimental evidence of an ovarian control on sperm release from the SR is highlighted. Furthermore, the impact of oviductal secretion on sperm capacitation, oocyte maturation, fertilization and early embryo development is stressed.

Effect of oviductal proteins on structural and functional characteristics of cryopreserved sperm in Murrah buffaloes

The present study was undertaken to elucidate the effect of non-luteal oviductal proteins on sperm characteristics in Murrah buffaloes. Oviducts from healthy buffaloes were collected immediately after slaughter and the oestrous cycle phase was determined as either luteal or non-luteal based on ovarian morphology. Non-luteal oviducts (n = 80) were flushed from the isthmic end of the oviduct with PBS, fluid was centrifuged at 10,000 g at 4 degrees C for 20 min and then dialysed and clarified. The supernatant obtained was lyophilized to concentrate the protein and stored at -20 degrees C till use. Sixteen good quality ejaculates from four Murrah buffalo bulls were collected using an artificial vagina. After fresh semen analysis, each ejaculate was split into two parts and extended in Tris-citrate-egg yolk glycerol dilutor. Part I of the split ejaculate was treated with non-luteal oviductal proteins at the dose rate of 1 mg/ml of diluted semen, while part II remained as control. The extended semen was equilibrated for 4 h at 5 degrees C, filled in 0.5 ml French straws, exposed to LN(2) vapour, plunged into LN(2) and then stored at -196 degrees C. The equilibrated and frozen-thawed semen was evaluated for sperm motility, viability, acrosomal integrity, cervical mucus penetration test and hypo-osmotic sperm swelling test (HOST). In frozen-thawed semen, the percentage of sperm motility, viability and acrosomal integrity was significantly (p < 0.05) higher in the treatment group compared to the control group. The incorporation of non-luteal oviductal proteins in the extender increased the ability of sperm to penetrate cervical mucus both after equilibration and the freeze-thaw process. Similarly, the proportion of sperm with intact plasma membrane, as revealed by HOST values, was also significantly (p < 0.05) higher in the treatment group (32.6%) than the control group (27%) in frozen-thawed semen. It was inferred that incorporation of non-luteal whole oviductal fluid proteins improved the sperm quality in frozen-thawed semen in Murrah buffaloes.

Number of spermatozoa in the crypts of the sperm reservoir at about 24 h after a low-dose intrauterine and deep intrauterine insemination in sows

The aim of this study was to investigate the number of spermatozoa in the crypts of the utero-tubal junction (UTJ) and the oviduct of sows approximately 24 h after intrauterine insemination (IUI) and deep intrauterine insemination (DIUI) and compared with that of conventional artificial insemination (AI). Fifteen crossbred Landrace x Yorkshire (LY) multiparous sows were used in the experiment. Transrectal ultrasonography was performed every 4 h to examine the time of ovulation in relation to oestrous behaviour. The sows were inseminated with a single dose of diluted fresh semen by the AI (n = 5), IUI (n = 5) and DIUI (n = 5) at approximately 6-8 h prior to the expected time of ovulation, during the second oestrus after weaning. The sperm dose contained 3000 x 10(6) spermatozoa in 100 ml for AI, 1,000 x 10(6) spermatozoa in 50 ml for IUI and 150 x 10(6) spermatozoa in 5 ml for DIUI. The sows were anaesthetized and ovario-hysterectomized approximately 24 h after insemination. The oviducts and the proximal part of the uterine horns (1 cm) on each side of the reproductive tracts were collected. The section was divided into four parts, i.e. UTJ, caudal isthmus, cranial isthmus and ampulla. The spermatozoa in the lumen in each part were flushed several times with phosphate buffer solution. After flushing, the UTJ and all parts of the oviducts were immersed in a 10% neutral buffered formalin solution. The UTJ and each part of the oviducts were cut into four equal parts and embedded in a paraffin block. The tissue sections were transversely sectioned to a thickness of 5 mum. Every fifth serial section was mounted and stained with haematoxylin and eosin. The total number of spermatozoa from 32 sections in each parts of the tissue (16 sections from the left side and 16 sections from the right side) was determined under light microscope. The results reveal that most of the spermatozoa in the histological section were located in groups in the epithelial crypts. The means of the total number of spermatozoa in the sperm reservoir (UTJ and caudal isthmus) were 2296, 729 and 22 cells in AI, IUI and DIUI groups, respectively (p < 0.01). The spermatozoa were found on both sides of the sperm reservoir in all sows in the AI and the IUI groups. For the DIUI group, spermatozoa were not found on any side of the sperm reservoir in three out of five sows, found in unilateral side of the sperm reservoir in one sow and found in both sides of the sperm reservoir in one sow. No spermatozoa were found in the cranial isthmus, while only one spermatozoon was found in the ampulla part of a sow in the IUI group. In conclusion, DIUI resulted in a significantly lower number of spermatozoa in the sperm reservoir approximately 24 h after insemination compared with AI and IUI. Spermatozoa could be obtained from both sides of the sperm reservoir after AI and IUI but in one out of five sows inseminated by DIUI.

Identifying useable semen

The "predictors of useable semen" used in most commercial AI centers provide a very conservative estimate of the relative fertility of individual boars. Furthermore, the relatively high sperm numbers used in commercial AI practice (usually >3 x10(9) total sperm per dose of extended semen) usually compensate for reduced fertility, as can be demonstrated in some boars when lower numbers of sperm are used for AI. Differences in relative boar fertility are also masked by the widespread use of pooled semen for commercial AI in many countries. However, the need to continually improve the efficiency of pork production, suggests that commercial AI practice should involve increased use of boars with the highest genetic merit for important production traits. Necessarily, this must be linked to the use of fewer sperm per AI dose, fewer inseminations per sow bred, and hence more sows bred by these superior sires. In turn, this requires improved techniques for evaluating semen characteristics directly related to the fertilization process, such as IVM-IVF assays, analysis of seminal plasma protein markers, more discriminatory tests of sperm motility and morphology, with the goal of identifying high-index boars whose fertility is sustained when low numbers of sperm are used for AI. This paper reviews the current status of laboratory-based boar semen evaluation techniques that meet these criteria.

Localization and expression of spermadhesin PSP-I/PSP-II subunits in the reproductive organs of the boar

The epithelial localization and expression of the spermadhesin PSP-I and PSP-II subunits were determined in the testis, ductus epididymes (caput, corpus and cauda), seminal vesicles and bulbourethral glands of mature boars, using immunohistochemical, western blotting and RT-PCR methods. Immunohistochemistry showed positive labelling for PSP-I and PSP-II antibodies in the epithelium of seminal vesicles in all males tested. Positive immunolabelling, but with variable intensity, was also present in the epididymal epithelium (caput, corpus and cauda), although varying largely among segments and boars. Immunoreactivity was nearly or completely absent in the seminiferous epithelium and the bulbourethral gland, although SDS-PAGE and western blotting revealed the presence of PSP-I and PSP-II immunoreactive bands in all the tissue extracts, including the testis and the bulbourethral gland. mRNA amplification by RT-PCR using primers specific for PSP-I and PSP-II showed a trend similar to that observed for western blotting, i.e. intensity variation between tissues (even between segments of the same epididymis) and among boars. Our results indicate that the seminal vesicles are the main source of PSP-I and PSP-II spermadhesins, although epididymal segments, testis and the bulbourethral gland also participate in the expression of both proteins.

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.

Effects of ultrashort gamete co-incubation time on porcine in vitro fertilization

A reduction in co-incubation time has been suggested as an alternative method to reduce polyspermic fertilization. The aim of this study was to evaluate the effect of short periods of gamete co-incubation during pig in vitro fertilization. A total of 2,833 in vitro matured oocytes were inseminated with thawed spermatozoa and coincubated for 0.25, 1, 2, 3, 7, 10 min and 6h. The oocytes from the 0.25-10 min groups were washed three times in modified Tris-buffered medium (mTBM) medium to remove spermatozoa not bound to the zona and transferred to the same medium (containing no spermatozoa) until 6h of co-incubation time were completed. After 6h, presumptive zygotes from each group were cultured in NCSU-23 medium for 12-15 h to assess fertilization parameters. After each period of co-incubation, 45-50 oocytes from each group were stained with Hoechst-33342 and the number of spermatozoa bound to the zona was counted. Although the number of zona bound spermatozoa increased (p<0.05) with the co-incubation time, no increase was observed in penetration rates among groups from 2 min to 6h of co-incubation time (ranging from 53.5+/-2.8 to 61.3+/-2.6%). Similarly, the efficiency of fertilization reached a maximum for the 2 min of co-incubation group with values ranging between 32.3+/-2.4 and 41.9+/-2.5%. The reduction of co-incubation time did not affect the monospermy rate (range: 71.3+/-3.4-80.2+/-3.8%) and the mean number of spermatozoa/oocyte (range: 1.2+/-0.4-1.4+/-0.5). These results show that, under our in vitro conditions, high penetration rate can be obtained with co-incubation times as short as 2 min, although monospermy could not be improved using this strategy.

PSP-I/PSP-II spermadhesin exert a decapacitation effect on highly extended boar spermatozoa

PSP-I/PSP-II heterodimer is a major protein of boar seminal plasma that is able to preserve, in vitro, the viability, motility and mitochondrial activity of highly-extended boar spermatozoa. However, a relationship between the protective effects of the heterodimer and sperm capacitation is still unclear. The present study investigated the effect of the PSP-I/PSP-II (1.5 mg/mL) on membrane stability, intracellular calcium concentration ([Ca(2+)](I)) and plasma membrane and acrosome integrity of highly extended boar spermatozoa. Boar spermatozoa were diluted to 1 x 10(6) spermatozoa/mL and incubated at 38 degrees C in Phosphate-buffered saline (PBS) for 10, 30, 60, 120 and 300 min or in modified Tris-buffered medium (mTBM) for 10, 20, 30, 60 and 120 min. After each incubation time, the membrane stability (using Merocyanine-540/Yo-Pro-1), elevation of [Ca(2+)](I) (using Fluo-3-AM/PI) and the sperm plasma membrane and acrosome integrity (using SYBR-14/PI/PE-PNA) were evaluated by flow cytometry. As expected, exposure of the spermatozoa to the PSP-I/PSP-II preserved the plasma membrane and acrosome integrity compared to non-exposed spermatozoa in both media PBS and mTBM (p < .01). The evaluation of membrane stability showed no differences in the percentages of viable sperm with instable plasma membrane in the presence of the PSP-I/PSP-II compared to controls irrespective of the dilution media. The evaluation of the [Ca(2+)](I) levels showed that while spermatozoa incubated in mTBM and exposed to PSP-I/PSP-II had lower [Ca(2+)](I) than controls (39.08% vs. 47.97%, respectively; p < .05), no differences were observed in those samples incubated in PBS. However, a temporal evaluation of the samples showed that a similar proportion of live spermatozoa were able to achieve high levels of [Ca(2+)](I) and membrane instability independent of the presence of PSP-I/PSP-II. In conclusion, PSP-I/PSP-II exert a non-permanent decapacitation effect on highly extended boar spermatozoa that is related with a delay in the increase of [Ca(2+)](I) levels.

Sire effect on the pregnancy outcome in beef cows synchronized with progesterone based Ovsynch and CO-Synch protocols

The objective was to determine the sire effect on the pregnancy outcome in beef cows in which stage of estrus was synchronized with progesterone based fixed-time artificial insemination (AI) protocols. Three Angus sires with more than 300 breedings were evaluated for differences in pregnancy outcome from 1868 inseminations. Angus cross beef cows (N=1868) were synchronized with Ovsynch-CIDR or CO-Synch-CIDR protocols for fixed-time AI. Cows in both groups that showed estrus on day 9 before 1500 h were designated to Selectsynch-CIDR group and were inseminated according to AM-PM rule. Results indicated that Sire 2 had lower fixed-time AI pregnancy rate compared to Sire 3 (48.1% versus 58.7%; P=0.01). Significant sirexsynchronization program and sirexlocation interactions were observed for fixed-time AI (P<0.05). Sire 2 had a lesser fixed-time AI pregnancy in both Ovsynch-CIDR and CO-Synch-CIDR groups compared to Sire 3. In two of four locations, Sire 2 had a lesser fixed-time pregnancy rate compared to Sire 3. No sire differences were observed in AI pregnancy for cows in Selectsynch-CIDR group. In conclusion, evidence in this study suggest that there are differences in sire fertility when they were used in fixed-time AI protocols, possibly due to the sire differences in sperm capacitation process. Further studies are needed to investigate association of the sire differences in fixed-time AI protocols with sire differences in the sperm capacitation process.

Distribution of spermatozoa and embryos in the female reproductive tract after unilateral deep intra uterine insemination in the pig

The present study was performed to investigate the number of either the spermatozoa or the embryos in the reproductive tracts of sows after unilateral, deep, intra uterine insemination (DIUI). Two experiments were conducted, 10 sows were used in experiment I and eight sows were used in experiment II. Transrectal ultrasonography was used to examine the time when ovulation took place in relation to oestrus behaviour. The sows were inseminated with a single dose of diluted fresh semen 6-8 h prior to expected ovulation, during the second oestrus after weaning. In experimental I, five sows were inseminated by a conventional artificial insemination (AI) technique using 100 ml of diluted fresh semen, containing 3000 x 10(6) motile spermatozoa and five sows were inseminated by the DIUI technique with 5 ml of diluted fresh semen, containing 150 x 10(6) motile spermatozoa. The sows were anesthetized and ovario-hysterectomized approximately 24 h after insemination. The oviducts and the uterine horns on each side of the reproductive tracts were divided into seven segments, namely ampulla, cranial isthmus, caudal isthmus, utero-tubal junction (UTJ), cranial uterine horn, middle uterine horn and caudal uterine horn. Each segment of the reproductive tracts was flushed with Beltsville thawing solution (BTS) through the lumen. The total number of spermatozoa in the flushing from each segment were determined. In experimental II, eight sows were inseminated by the DIUI technique using 5.0 ml diluted fresh semen containing 150 x 10(6) motile spermatozoa. The sows were anesthetized 61.1 +/- 12 h after insemination (48-72 h) and the embryos were flushed from the oviduct through the proximal part of the uterine horn. It was revealed that, in experimental I, the spermatozoa were recovered from both sides of the reproductive tract in the AI-group, and from unilateral side of the reproductive tract in the DIUI-group (three sows from the left and two sows from the right sides). The number of spermatozoa recovered from the reproductive tracts was higher in the AI- than the DIUI-group (p < 0.001). In experiment II, fertilization occurred in five of eight sows (62.5%) after DIUI. The number of ova that ovulated were 16.4 +/- 2.6 per sow and the embryos numbering 11.4 +/- 2.3 per sow were recovered from both sides of the reproductive tract. In conclusion, the spermatozoa given by DIUI could be recovered from only one side of the reproductive tract of sows at approximately 24 h after DIUI via the flushing technique. However, embryos were found in both sides of the oviducts and the proximal part of the uterine horns 48-72 h after insemination, indicating that the fertilization occurred in both sides of the oviducts.

Plasma concentrations of cortisol and PGF2alpha metabolite in Danish sows during mating, and intrauterine and conventional insemination

Background

The aims of the present work was to study whether there are any relationships between cortisol and PG-metabolite in mated sows or inseminated with the intrauterine technique and compare these to changes occurring in conventionally inseminated sow.

Methods

Thirty three crossbred sows (Danish Landrace × Danish Large White) were fitted with jugular vein catheters through vena auricularis from one of the ears. The sows were randomly divided into three groups (Boar-, IUI- and AI-group) and blood samples were collected before, during and after service. In a final evaluation only 25 sows that became pregnant and farrowed piglets at full term were used.

Results

Cortisol concentrations increased in all groups but Boar-group (n = 8) had a significantly higher cortisol during 10 to 20 min after service than sows in AI-group (n = 8). In mated sows cortisol concentrations peaked at 15 minutes after service. The Boar-group (n = 8) showed no ascending PG-metabolite levels during the whole experiment, while both IUI- and AI-groups (n = 9 and n = 8, respectively) had a 2.5-fold increase in PG-metabolite 15 minutes after service.

Conclusion

In conclusion, mating of sows by a boar results in a greater increase of cortisol than AI and without an elevation of PG-metabolite levels, which was seen in both the inseminated groups. It was also demonstrated that IUI-group had an earlier significant increase of PG-metabolite levels than sows inseminated conventionally. Further investigation using different semen extenders or even different type of insemination catheters might be helpful in understanding the reason for an immediate increase of PG-metabolite after insemination but not after mating.

Controlled cooling during semen cryopreservation does not induce capacitation of spermatozoa from two portions of the boar ejaculate

Cryopreservation imposes dramatic changes in boar sperm survivability but it is as yet unclear which part of the process affects the spermatozoa the most. The present study monitored, along the entire process of cryopreservation, the stability (PMS) of the architecture of the lipid plasma membrane and its integrity (PMI), as well as the kinetics of the processed spermatozoa using two portions from the boar ejaculate (P1 = the first 10 mL of the sperm-rich fraction, SRF; P2 = the rest of the ejaculate), frozen in a recently developed package, the MiniFlatPack (MFPs, 0.5 x 10(9) sperm/dose). Evaluation was made at four specific stages, viz. S1 = after collection (suspended in Beltsville thawing solution, BTS); S2 = at 15 degrees C (suspended in lactose-egg yolk, LEY); S3 = at 5 degrees C (suspended in LEY plus glycerol); and S4 = post-thaw. Both sperm kinetics (using computer-assisted sperm analysis, CASA) and PMS [i.e. the degree of lipid disorder and of the exteriorization of phosphatidylserine (PS) in the plasma membrane, measured by flow cytometry using Merocyanine-540 (M-540), and Annexin-V (AV) respectively], as well as plasma membrane integrity [PMI, i.e. the degree of membrane damage, measured using Yo-Pro-1 or propidium iodide (PI)] were assessed after incubation in BTS at 38 degrees C. Moreover, spermatozoa were challenged by incubation in modified Brackett-Oliphant medium (mBO+) with 37 mm of bicarbonate at 38 degrees C for 30 min, and their PMS and PMI further explored. Total sperm motility was significantly higher in P1 than in P2 along the entire process (S1-S4; p < 0.01), decreasing significantly at S4 for both fractions (p < 0.0001). The proportion of spermatozoa showing linear motility (LinM) was similar between ejaculate portions (P1 and P2), with a significant increase post-thaw (S4; p < 0.0001). During cooling (S1-S3) but not post-thaw (S4), lateral head displacement (LHD) differed between portions and changed along the stages (p < 0.01). Sperm velocity differed between portions in S1 (p < 0.01), but remained similar, independently of the portion, thereafter (S2-S4). Both PMS and the total number of live spermatozoa remained similar between S1 and S3 while incubated in BTS for both ejaculate portions. Sperm mortality increased post-thaw (S4) in both portions but the degree of lipid disorder remained low in the live cells (1.28% for P1; 1.55% for P2). Exposure to mBO+, on the other hand, significantly increased membrane lipid disorder along cooling (S1-S3; p < 0.0001), increasing the percentages of dead spermatozoa, especially post-thaw (around 70%, both portions). PS-exteriorization (AV) was not evident along the cryopreservation process in control (BTS) samples and exposure to mBO+ only induced minor variations. The data showed that kinetics, PMS and PMI of boar spermatozoa suspended in BTS (S1), LEY (S2) or LEY plus glycerol (S3) were maintained during controlled cooling but were altered by thawing, showing more characteristics of cell injury than of sperm capacitation. The spermatozoa were able to capacitate but the bicarbonate challenge destabilized the plasma membrane during initial cooling and accelerated membrane changes post-thaw. We conclude that capacitation of boar spermatozoa does not occur during controlled cooling.

Role of the oviduct in sperm capacitation

Following insemination of spermatozoa pre-ovulation, the mammalian oviduct ensures, by the formation of a functional sperm reservoir (SR), that suitable (low) numbers of viable and potentially fertile spermatozoa are available for fertilization at the ampullary isthmic junction (AIJ). As ovulation approaches, a proportion of the SR-stored spermatozoa is continuously distributed towards the AIJ and individually activated leading to step-wise capacitation and the attainment of hyperactivated motility. This paper reviews in vivo changes in the intra-luminal milieu of the oviduct of pigs and cows, in particular the SR and the AIJ which relate to the modulation of sperm capacitation around spontaneous ovulation. In vivo, most viable spermatozoa in the pre-ovulatory SR are uncapacitated. Capacitation rates significantly increase after ovulation, apparently not massively but concurrent with the individual, continuous sperm dislocation from the SR. Bicarbonate, whose levels differ between the SR and the AIJ, appears as the common primary effector of the membrane destabilizing changes that encompasses the first stages of capacitation. Sperm activation can be delayed or even reversed by co-incubation with membrane proteins of the tubal lining, isthmic fluid or specific tubal glycosaminoglycans, such as hyaluronan. Although the pattern of response to in vitro induction of sperm activation - capacitation in particular - is similar for all spermatozoa, the capacity and speed of the response is very individual. Such diversity in responsiveness among spermatozoa insures full sperm viability before ovulation and the presence of spermatozoa at different stages of capacitation at the AIJ, thus maximizing the chances of normal fertilization.

Sperm release from oviduct epithelial binding is controlled hormonally by peri-ovulatory graafian follicles

To avoid inappropriate conclusions being drawn from the extensive use of in vitro preparations of sperm-oviduct epithelial binding, it is recalled that events in the genital tract of mammals are regulated by the gonads, primarily by their changing secretion of steroid hormones. Key observations from in vivo models are used to emphasise the dynamic interactions between viable sperm cells and the caudal (distal) portion of the oviduct isthmus, the site of the functional sperm reservoir. These include (1) pre-ovulatory arrest and epithelial binding of intact sperm cells and thereby suppression of completion of capacitation, (2) peri-ovulatory activation and release from binding of discrete sub-populations of competent spermatozoa, and (3) post-ovulatory liberation of large numbers of spermatozoa. These observations underline the influence of endocrine regulation of sperm binding and release by peri-ovulatory Graafian follicles, a point brought out by the enhanced sperm release prompted by diverse treatments with solutions of progesterone. In the light of this evidence, the suitability of in vitro preparations for clarifying physiological events should be questioned, especially if myosalpingeal catecholamines diffusing out of the autonomic nervous system contribute to sperm activation and/or release. None of this is to infer that sperm cells themselves are without influence on their epithelial binding reaction(s). Nor is it to suggest that in vitro models of sperm-oviduct binding are without relevance to the development of sperm evaluation technologies. However, pre-ovulatory sperm-epithelial binding and a regulated peri-ovulatory release should be seen as vital tactics in the overall strategy of achieving successful monospermic fertilisation.

Effect of different procedures of ejaculate collection, extenders and packages on DNA integrity of boar spermatozoa following freezing–thawing

Whole ejaculate or sperm-rich fraction, collected from four sexually mature boars, was frozen in an extender containing lactose-hen egg yolk with glycerol (lactose-HEY-G) or extender containing lactose, lyophilized lipoprotein fractions isolated from ostrich egg yolk and glycerol (lactose-LPFo-G), and Orvus Es Paste, respectively. The sperm samples were also frozen in a standard boar semen extender (Kortowo-3), without the addition of cryoprotective substances. Sperm DNA integrity was assessed using a modified neutral comet assay. Sperm characteristics such as motility, plasma membrane integrity (SYBR-14/PI), mitochondrial function (rhodamine 123) and acrosome integrity were monitored. Freezing-thawing caused a significant increase (P<0.05) in sperm DNA fragmentation, irrespective of the procedures of ejaculate collection and extender type. Sperm DNA fragmentation was significantly lower (P<0.05) in the whole ejaculate compared with the sperm-rich fraction, indicating that spermatozoa maintained in the whole seminal plasma prior to its removal for freezing-thawing procedure were less vulnerable to cryo-induced DNA fragmentation. Furthermore, spermatozoa frozen in lactose-HEY-G or lactose-LPFo-G extender exhibited lower (P<0.05) DNA fragmentation than those frozen in the absence of cryoprotective substances. The levels of sperm DNA damage, as expressed by comet tail length and tail moment values, were significantly higher (P<0.05) in sperm samples frozen in the absence of cryoprotective substances. The deterioration in post-thaw sperm DNA integrity was concurrent with reduced sperm characteristics. It can be suggested that evaluation of DNA integrity, coupled with different sperm characteristics such as motility, plasma membrane integrity and mitochondrial function, may aid in determining the quality of frozen-thawed boar semen.

Effect of sperm cryopreservation and supplementing semen doses with seminal plasma on the establishment of a sperm reservoir in gilts

Frozen-thawed (FT) boar sperm have a reduced fertile life, due in part to a capacitation-like status induced by cooling. Reversal of this cryocapacitation in vitro by exposure to boar seminal plasma (SP) has been demonstrated. The objective of these studies was to determine the effect of SP on the ability of FT sperm to create an oviductal sperm reservoir following artificial insemination (AI). In Experiment one, 35 pre-pubertal gilts were injected (IM) with 400 IU eCG plus 200 IU hCG to induce oestrus. At detection of oestrus, gilts were inseminated with 3 x 10(9) live sperm, either fresh (FS; n = 13), FT (n = 10), or FT supplemented with 10% v/v SP (n = 12). Gilts were killed 8 h later, their reproductive tracts recovered and the uterotubal junctions (UTJs) flushed to recover sperm. Fewer (p < 0.01) sperm were recovered following FT, compared to FS, inseminations, and there was no evident effect of SP. In Experiment two, 30 pre-pubertal gilts received IM injections of 1000 IU eCG followed by 5 mg pLH 80 h later to control time of ovulation. Gilts were inseminated with 3 x 10(9) live FS sperm (n = 6), FT sperm (n = 15) or FT sperm plus 10% SP (n = 9) at 12 h before ovulation and then sacrificed 8 h later. The UTJs were dissected and flushed for sperm recovery. Fewest (p < 0.001) sperm were recovered following FT insemination and there was no evident effect of SP. These data demonstrate that the size of the sperm reservoir is markedly reduced in gilts inseminated with FT sperm. However, the lack of effect of SP suggested that either it did not reverse cryocapacitation or that such a reversal does not impact the in vivo ability to create a sperm reservoir.

State of the art in farm animal sperm evaluation

Our ability to screen the structural and functional integrity of the spermatozoon in vitro has increased markedly over the past decades, but our capacity to estimate the fertility of a semen sample or of the sire from which it has been collected, especially in selected farm animal breeders, has not. The estimation of fertility is constrained by several factors (e.g. type of cell, analysis strength, sperm deposition strategies, recordings of fertility), including the fact that the ejaculate is composed of a diverse sperm population. Such cell heterogeneity is reflected not only in differences in the intactness of attributes needed for fertilisation, such as motility or morphology, but also in the relative ability of the spermatozoa to remain fertile over time, to sustain selection steps and responses to exogenous stimuli similar to those during sperm transport in the female genital tract, all of which account for innate variations in the fertilising ability among doses, ejaculates and sires. Determination of how large such a sperm population with competence for fertilisation and in-built ability to display these attributes under physiological signalling is would allow for a better estimation o f fertility, provided that th e particular s ire produces this sub-population in a repeatable manner. The value of these analyses is discussed in the present paper.

Dialysis of boar semen prior to freezing-thawing: its effects on post-thaw sperm characteristics

Low-molecular weight components of the seminal plasma have a detrimental effect on sperm function. The present study was undertaken to evaluate the effect of the removal of low-molecular weight components by dialysis on sperm characteristics prior to and after freezing. Semen, collected from 5 boars, was extended in Kortowo-3 extender (K-3, Poland) and cooled for 3h (control non-dialysis) or dialyzed for 5h in semi-permeable dialysis bags of 12-14kDa molecular weight cut-off prior to freezing. The semen samples were diluted in lactose-hen egg yolk-glycerol extender (lactose-HEY-G) or lactose-lyophilized lipoprotein fractions-glycerol extender (lactose-LPFo-G), packaged into aluminum tubes and frozen in a controlled programmable freezer. Pre-frozen and frozen-thawed spermatozoa were evaluated for motility, plasma membrane (SYBR-14 and propidium iodide) and acrosome integrity, mitochondrial function (Rhodamine 123) and ATP content. The results of the study showed that dialysis significantly improved the sperm characteristics prior to freezing. Dialysis enhanced (P<0.05) post-thaw sperm motility, plasma membrane integrity and mitochondrial function, but had no significant effect (P>0.05) on recovery of spermatozoa with intact acrosomes. Furthermore, dialyzed spermatozoa exhibited higher (P<0.05) ATP content compared with the control after freezing-thawing. Consistent inter-boar variability was detected mainly in dialyzed semen following freezing-thawing. These results indicated that the improvement in sperm quality characteristics prior to freezing and the post-thaw sperm recovery were due to the removal of low-molecular weight components from the seminal plasma. It can be suggested that dialysis is effective in improving the post-thaw quality of boar spermatozoa and has also great practical importance in improving the protocols for cryopreservation of semen. Dialysis may also contribute to a better understanding of different mechanisms underlying cryo-induced damage to boar spermatozoa.

The Role of Oestradiol in the Uterine Peristalsis in the Perfused Swine Uterus

This study was designed to examine the effects of oestradiol (E2) on sperm transport in the swine uterus. The bicornuate swine uterus is optimal for the study of the uterine transport and peristalsis because the influence of various factors can be examined on each uterine horn independently. Forty swine uteri (with or without ovarectomy) were perfused for a period of up to 7 h. Two different E2 concentrations (3 or 30 pg/ml) in the perfusion medium were administered for 30 min unilaterally. Through an intracervical catheter 1 ml of a high concentrated dextran blue solution was administered directly in the upper part of the cervix. After bilateral perfusion of the swine uterus with a bolus of 0.3 IU oxytocin the distribution of coloured particles was assessed macroscopically before and after incision of the uterine horns. Coloration was evaluated by two observers blinded to the site-specific administration of E2. In the 10 ovarectomized uteri with the 3 pg/ml E2 concentration a unilateral distribution towards the side of oestradiol administration was observed in six uteri, in four it was a bilateral distribution. In the 10 non-ovarectomized uteri with the 3 pg/ml E2 concentration a uni- and ipsilateral coloration was observed in five uteri, in five it was a bilateral distribution. In the 20 uteri with 30 pg/ml E2, a unilateral coloration of the uterus horns was observed in all uteri. Oestradiol is one of the main factors, which influences the direction of the sperm transport in a dose-dependent manner, in the perfused swine uterus.

Separation, characterization and identification of boar seminal plasma proteins

Methods used for the isolation, separation and characterization of boar seminal plasma proteins are discussed, as well as techniques applied to study their binding properties. Attention is paid to interactions of these proteins with different types of saccharides and glycoconjugates, with membrane phospholipids, and to interactions between proteins. Boar seminal plasma contains different types of proteins: spermadhesins of the AQN and AWN families; DQH and PSP proteins belong to the most abundant. Some of these proteins are bound to the sperm surface during ejaculation and thus protein-coating layers of sperm are formed. Sperms coated with proteins participate in different types of interactions occurring in the course of the reproduction process, e.g. formation of the oviductal sperm reservoir, sperm capacitation, oocyte recognition and sperm binding to the oocyte.

Validation of an experimental strategy for studying surface-exposed proteins involved in porcine sperm-oviduct contact interactions

Previous experiments have shown that boar sperm survival in vitro is enhanced when co-incubated with a solubilised protein extract of porcine oviducal apical plasma membrane proteins. Here, we examine the hypothesis that the effects are mediated by direct oviduct-sperm contact and use in situ biotinylation of the oviducal epithelial surface to trace the surface-exposed biotinylated proteins through purification and solubilisation steps. We have also examined the effectiveness of mechanical scraping as a method of recovering oviducal epithelial proteins. We show that a subset of proteins originally exposed at the oviducal surface eventually bind to spermatozoa during incubation in vitro, but also show that a different protein subset is implicated if the sperm incubation is performed with proteins that had been biotinylated after (ex situ) extraction from the oviduct. Apical plasma membrane fractions biotinylated after purification contained many more biotinylated protein bands than preparations labelled before purification and multiple protein bands were eventually found to associate with spermatozoa. Although the evidence presented here supports the hypothesis that protein(s) anchored to the oviducal epithelium bind populations of spermatozoa directly and may have a role in the enhancement of sperm viability, it also shows that the choice of investigative technique exerts a major influence on experimental outcomes.

Effect of storage in short- and long-term commercial semen extenders on the motility, plasma membrane and chromatin integrity of boar spermatozoa

For artificial insemination (AI) in pigs, preservation of liquid boar semen at 16-20 degrees C is still common practice as sperm cryopreservation remains suboptimal in this species. To meet the different needs of the swine industry, several extenders have been developed to preserve semen in liquid form for short--and long-term storage. In the present study, three different commercial extenders devised for short-term (BTS+) or long-term preservation (MR-A and X-Cell), were used to test whether storage of semen from four mature, fertile boars at 17 degrees C for 96 h would affect sperm characteristics relevant for fertility, such as motility, membrane integrity and chromatin stability. Computer-assisted sperm analysis, and stainings with the acylated membrane dye SYBR-14/propidium iodide, and acridine orange in connection with flow cytometry were used to evaluate these variables. Percentages of total motile spermatozoa decreased slightly, but significantly, after 72-96 h. While membrane integrity values varied during the period of study, no significant changes in either membrane integrity or chromatin stability were, however, registered. This suggests a customary 96-day storage at 17 degrees C in these extenders was too short an interval to cause losses of integrity in nuclear DNA in the boar population studied.

Challenges in Pig Artificial Insemination

Semen extended in a liquid state, together with conventional artificial insemination (AI), is the sole sperm technology used by the pig industry. Sperm technologies known for many years, such as cryopreservation, and others developed during recent years, such as sperm sexing, have not yet been integrated into commercial use. Moreover, there has recently been an explosion of new technologies, such as sperm mediated gene transfer or encapsulated spermatozoa which need additional supportive techniques before they can be economically applied to pig breeding. The speed with which the aforementioned sperm technologies are accepted and utilized by the pig industry depends on the availability of efficient insemination procedures. Therefore, AI is entering a new dimension where it will be converted into a tool for the efficient application of current and new sperm technologies. Some new insemination procedures have been recently developed. This review examines the suitability of available insemination procedures for the efficient application of current, emergent and future sperm technology to the pig industry.

Can we increase the estimated value of semen assessment?

Estimating the fertility of a semen sample or of the male from where it has been collected by simple assessment of in vitro sperm characteristics is still difficult, owing to the variable correlations that laboratory results achieve with in vivo fertility. A major reason behind these variations is the fact that the ejaculate and the artificial insemination (AI)-doses it generates are composed of a diverse sperm population. Such heterogeneity is reflected both in differences of intactness of attributes needed for fertilization, such as motility or morphology, but also in the relative ability of spermatozoa to prevail fertile over time, handling and exposure to different stimuli, all of which account for innate variations in fertilizing ability among doses, ejaculates and sires. However, methods are already available to select sub-populations of intact spermatozoa which can be tested for their degree of competence for fertilization and whose estimated power is promising, allowing the elimination of cases of sub-fertility, particularly in bovine. Examples of these methods are the separation of viable spermatozoa by swim-up or discontinuous gradient centrifugation, followed by testing the ability of the selected spermatozoa to dose-response/time sustain capacitation and acrosome reaction induction. Finding how large a sperm population with non-compensated attributes for fertilization and ability to display and sustain stimuli is, perhaps by a quick screening of membrane integrity and stability by multi-parametric methods, would allow, provided the particular male produces this sub-population in a repeatable manner, for a better estimation of fertility.

The predictive value of routine semen evaluation and IVF technology for determining relative boar fertility

Practical techniques for assessing semen quality in order to predict male fertility are still needed. The principal objective of this experiment was to evaluate routine laboratory evaluation and in vitro fertilization (IVF) techniques as predictors of relative boar fertility using a low-dose AI protocol. Nine boars were evaluated during a 6.5+/-1 mo period, beginning at 29-32 wk of age. Ejaculates were evaluated for motility, morphology and concentration, diluted to 1.5 billion sperm in 50 mL extender, and used to breed 50+/-5 gilts over the same period. On nine occasions, a specific aliquot of the ejaculate's first sperm-rich fraction was evaluated using IVF procedures. Boars differed (P<0.001) consistently for pregnancy rate (from 73 to 98%), farrowing rate (71-98%) and total born (8.8-12.0). Routine semen evaluation and IVF parameters that presented significant differences between boars, but no differences in time and no boar by time interaction, were used to correlate in vivo fertility. A multiple regression model based on routine semen evaluation parameters accounted for up to 27 and 22% of the variation of fertility index and total piglets born, respectively, whereas male pronuclear formation rate was the IVF variable that accounted for 17 and 12% of the variation in farrowing rate and fertility index, respectively. Collectively, we inferred that the use of low sperm numbers for AI, determination of pregnancy rate at Day 30, motility of extended semen after 7 and 10d, and specific IVF parameters may be useful for identifying relatively infertile boars that are not currently excluded from use in existing commercial boar studs.

Sperm binding glycoprotein is differentially present surrounding the lumen of isthmus and ampulla of the pig’s oviduct

In several mammals a sperm reservoir is formed at the isthmus of the Fallopian tube, providing viable, potentially fertile sperm for an extensive period. In pig (Sus scrofa) the spermadhesin AQN-1 seems to be involved in the establishment of the sperm reservoir. The pig oviductal protein, sperm binding glycoprotein (SBG), binds to sperm and exposes carbohydrate groups that can be recognized by AQN-1. In this study we obtain anti-SBG polyclonal antibodies and use them to localize SBG in the oviduct. Immunohistochemical analysis shows that SBG is present at the apical surface of isthmic and ampullar epithelial cells. The presence of SBG is limited to the upper two-thirds of the crypts of the isthmus and to cells located near the oviductal lumen in the ampulla. The ratio of the amount of SBG detected by western blot is 1:3 (ampulla:isthmus). Sperm entering the Fallopian tube probably contact the epithelial cells at the lumen before they reach the cells at the bottom of the folds. In vitro sperm can bind to isthmus and, at less extent, to ampulla. Thus, the localization and the relative amount of SBG in the isthmus and ampulla of pig's oviduct are compatible with its possible function in sperm binding to oviductal epithelial cells.