Uterine activity, sperm transport, and the role of boar stimuli around insemination in sows

Effects of gelatin and oxytocin supplementation in a long-term semen extender on boar semen quality and fertility potential

OBJECTIVE

This study investigated the efficacy of different concentrations of gelatin supplementation in long-term semen extender on boar semen quality during storage for 10 days at 17°C. Additionally, oxytocin was added to stored semen to enhance fertility.

METHODS

In Experiment 1, boar semen was collected, diluted with gelatin at concentrations between 0% and 2.5% (w/v) and mixed with a semen extender. Then, it was kept in a refrigerator at 17°C and stored for 10 days. In Experiment 2, the sperm quality was examined after adding 0, 5, and 10 IU oxytocin per artificial insemination dose to the most effective semen extender from Experiment 1 and placing it in a refrigerator at 17°C for 10 days. In Experiment 3, the fertility potential in terms of non-return rate and litter size was determined using the most effective solid-stored semen supplemented with oxytocin.

RESULTS

The results indicated that sperm quality decreased with increasing storage time (p<0.05). The sperm quality in terms of total motility, progressive motility, and viable sperm with intact acrosomes and high mitochondrial potential was the highest with 1.5% gelatin supplementation (p<0.001) on all days of storage. Treatment with oxytocin did not affect sperm quality (p>0.05). The non-return rate and litter size after insemination with semen supplemented with 1.5% gelatin and 10 IU of oxytocin after 8 to 10 days of storage were comparable to those of the control group (p>0.05).

CONCLUSION

A semen extender as a solid medium supplemented with 1.5% gelatin successfully preserved boar semen for a long storage duration. Treatment with oxytocin did not affect sperm quality. In addition, the fertility capacity using 1.5% gelatin with 10 IU oxytocin and stored for 8 to 10 days was acceptable and comparable to that of short-term storage.

The Suinfort® Semen Supplement Counters Seasonal Infertility in Iberian Sows

Simple Summary

Efficient pork production relies on a predictable supply of market pigs. Seasonal infertility caused by heat stress decreases fertility in sows during the summer months, impacting breeding targets and decreasing the efficiency of pork production. The present study examined the effect of a seminal additive containing caffeine, oxytocin, and lecirelin on the fertility and prolificacy of Iberian sows during two consecutive years. The results confirmed that inclusion of the additive in semen prior to AI decreased the seasonality effect, increasing the percentage of pregnant Iberian sows throughout the year.

Abstract

Suinfort^®, a commercial semen supplement demonstrated to increase fertility and litter size in commercial sows, was tested to improve reproductive performance in Iberian sows. A total of 1430 Iberian sows were artificially inseminated (AI) with semen from Duroc boars and assigned by parity to receive the seminal additive Suinfort^® containing 2 IU oxytocin, 5 µg lecirelin, and 2 mM caffeine (SF; n = 1713 AI), or to serve as non-supplemented controls (CON; n = 2625 AI). CON showed a lower fertility comparing to winter for spring (p = 0.001) and summer (p < 0.001); summer was lower than autumn (p = 0.012). SF removed this seasonal effect (p > 0.05). Fertility was significantly higher for SF sows during summer (p = 0.025) and autumn (p = 0.004). Total born, live-born, stillborn, and mummified piglets did not differ between CON and SF but were impacted by the season, with total and live-born decreasing in summer compared with autumn (p < 0.001) and winter (p = 0.005). In conclusion, seminal supplementation with Suinfort^® improved the fertility of Iberian sows during periods of seasonal infertility.

Effect of Boar Sperm Proteins and Quality Changes on Field Fertility

Simple Summary

Artificial insemination with extended liquid boar semen is widely used in the swine industry. The identification of the relationship between boar sperm characteristics and fertility could be of substantial importance to reproduction management. This study evaluated the relationship between boar sperm characteristics and sperm/seminal plasma proteins with main parameters of field fertility. Immotile spermatozoa and spermatozoa with biochemically active plasma membranes affected the number of live-born piglets and litter size of ≥12 piglets. The proteins osteopontin 70 and glutathione peroxidase 5, both separately and in combination, affected the farrowing rate. The combination of immotile sperm and protein osteopontin 70 explained the variation regarding litter size with ≥12 piglets. In conclusion, the evaluation of semen quality variables combined with the evaluation of specific sperm or seminal plasma proteins could provide useful information on in vivo fertilizing capacity of semen doses.

Abstract

This study aimed to evaluate boar sperm characteristics and proteins, in relation to their importance regarding in vivo fertility. Sixty-five ejaculates were used and 468 sows (parity ≥ 2) were inseminated. Sperm CASA kinetics, morphology, viability, DNA fragmentation, mitochondrial membrane potential, sperm membrane biochemical activity (HOST) and sperm proteins (Heat Shock Protein 90-HSP90, glutathione peroxidase-5-GPX5, Osteopontin 70-OPN70) were assessed and related to field fertility (number of live-born piglets—NLBP, litter size ≥ 12 piglets—LS, farrowing rate—FR). Statistical analysis was conducted with simple and multiple regression models. Simple regression analysis showed that immotile sperm (IM) significantly affected the NLBP and LS, explaining 6.7% and 6.5% of their variation, respectively. The HOST positive spermatozoa significantly affected the NLBP and LS, explaining 24.5% and 7.8% of their variation, respectively. Similarly, sperm with activated mitochondria significantly affected the NLBP, explaining 13.5% of its variation. Moreover, the OPN70 affected LS and FR, explaining 7.5% and 10.8% of their variation, respectively. Sperm GPX5 protein affected FR, explaining 6.7% of its variation. Multiple regression analysis showed that the combination of IM and/OPN70 explains 13.0% of the variation regarding LS, and the combination of GPX5 and OPN70 explains 13.6% of the variation regarding FR. In conclusion, the estimation of parameters IM, membrane biochemical activity, mitochondrial membrane potential, OPN and GPX5 can provide useful information regarding semen doses for field fertility.

Effects of individual versus group housing system during the weaning-to-estrus interval on reproductive performance of sows

Selection of appropriate housing conditions for sows is critical for their physical health and long-term reproductive success. The present objective was to evaluate the influences of housing system postweaning (i.e., individual stalls (IS) or group pens (GP)), season and parity on piglet productivity of sows in a commercial setting. This study utilized 3 053 Polish Large White×Polish Landrace sows that were weaned at a rate of 20-30 animals per week at the median age of 4 weeks; 1 474 sows were moved into GP of seven to eight animals each, while 1 579 were placed in IS after weaning. Starting 2 days postweaning all animals were checked for estrus with a teaser boar and then artificially inseminated using 3×10⁹ spermatozoa per dose of an inseminate at the onset of heat and 24 h later. The proportion of sows showing the signs of standing heat at or before 6 days postweaning was greater (P < 0.05) for sows moved to GP compared with IS; this difference manifested mainly in second parity sows weaned in the summer and fall. Conception and farrowing rates were significantly higher (P < 0.01) and the weaning-to-estrus interval shorter in GP compared with IS sows in every season but autumn. Mean litter size was lower (P < 0.05) in IS groups in summer, autumn, and winter, and the number of live-born piglets/sow was lower (P < 0.05) for IS sows in the summer and fall. Beneficial effects of group housing on piglet productivity manifested up until the seventh consecutive farrowing and then began to wane. In summary, there was a significantly greater proportion of sows going estrus "on time" (i.e., <7 days) in group housing compared to single stalls but this effect was confined to the second parity sows during the summer and fall months; these results suggest the existence of a seasonal and age-related aspect to sow fertility worthy of further investigation. While both housing systems have their pros and cons, our present results indicate that, in commercial settings, group housing postweaning improved nearly all reproductive parameters of sows.

Sperm interactions with the female reproductive tract: A key for successful fertilization in mammals

Sperm migration through the female genital tract is not a quiet journey. Uterine contractions quickly operate a drastic selection, leading to a very restrictive number of sperm reaching the top of uterine horns and finally, provided the presence of key molecules on sperm, the oviduct, where fertilization takes place. During hours and sometimes days before fertilization, subpopulations of spermatozoa interact with dynamic and region-specific maternal components, including soluble proteins, extracellular vesicles and epithelial cells lining the lumen of the female tract. Interactions with uterine and oviductal cells play important roles for sperm survival as they modulate the maternal immune response and allow a transient storage before ovulation. The body of work reported here highlights the importance of sperm interactions with proteins originated from both the uterine and oviductal fluids, as well as hormonal signals around the time of ovulation for sperm acquisition of fertilizing competence.

The role of semen and seminal plasma in inducing large-scale genomic changes in the female porcine peri-ovulatory tract

Semen modifies the expression of genes related to immune function along the porcine female internal genital tract. Whether other pathways are induced by the deposition of spermatozoa and/or seminal plasma (SP), is yet undocumented. Here, to determine their relative impact on the uterine and tubal transcriptomes, microarray analyses were performed on the endocervix, endometrium and endosalpinx collected from pre-ovulatory sows 24 h after either mating or artificial insemination (AI) with specific ejaculate fractions containing spermatozoa or sperm-free SP. After enrichment analysis, we found an overrepresentation of genes and pathways associated with sperm transport and binding, oxidative stress and cell-to-cell recognition, such as PI3K-Akt, FoxO signaling, glycosaminoglycan biosynthesis and cAMP-related transcripts, among others. Although semen (either after mating or AI) seemed to have the highest impact along the entire genital tract, our results demonstrate that the SP itself also modifies the transcriptome. The detected modifications of the molecular profiles of the pre/peri-ovulatory endometrium and endosalpinx suggest an interplay for the survival, transport and binding of spermatozoa through, for instance the up-regulation of the Estrogen signaling pathway associated with attachment and release from the oviductal reservoir.

The Transcriptome of Pig Spermatozoa, and Its Role in Fertility

In the study presented here we identified transcriptomic markers for fertility in the cargo of pig ejaculated spermatozoa using porcine-specific micro-arrays (GeneChip^® miRNA 4.0 and GeneChip^® Porcine Gene 1.0 ST). We report (i) the relative abundance of the ssc-miR-1285, miR-16, miR-4332, miR-92a, miR-671-5p, miR-4334-5p, miR-425-5p, miR-191, miR-92b-5p and miR-15b miRNAs, and (ii) the presence of 347 up-regulated and 174 down-regulated RNA transcripts in high-fertility breeding boars, based on differences of farrowing rate (FS) and litter size (LS), relative to low-fertility boars in the (Artificial Insemination) AI program. An overrepresentation analysis of the protein class (PANTHER) identified significant fold-increases for C-C chemokine binding (GO:0019957): CCR7, which activates B- and T-lymphocytes, 8-fold increase), XCR1 and CXCR4 (with ubiquitin as a natural ligand, 1.24-fold increase), cytokine receptor activity (GO:0005126): IL23R receptor of the IL23 protein, associated to JAK2 and STAT3, 3.4-fold increase), the TGF-receptor (PC00035) genes ACVR1C and ACVR2B (12-fold increase). Moreover, two micro-RNAs (miR-221 and mir-621) were down- and up-regulated, respectively, in high-fertility males. In conclusion, boars with different fertility performance possess a wide variety of differentially expressed RNA present in spermatozoa that would be attractive targets as non-invasive molecular markers for predicting fertility.

Effect of Oxytocin, Cloprostenol or Buserelin in Semen Doses on Sow Fertility

Simple Summary

Efficient pork production relies on a consistent supply of market pigs. However, many sows experience a seasonal infertility during the hotter months, resulting in fewer pigs produced and a seasonally constrained pork supply. The present study examined the impact of supplementing boar semen with different hormones in order to combat sow seasonal infertility. The results confirmed a seasonal infertility, in that litter sizes were reduced for sows bred during May to August, but that this adverse effect could be reversed by adding hormones to the semen doses used to inseminate sows.

Abstract

During the periods January to April, May to August, and September to December in two consecutive years, sows were assigned at breeding to receive semen doses supplemented with 87 µg cloprostenol (PG; n = 158), 5 IU oxytocin (OT; n = 154), 2 µg buserelin (GN; n = 93), or served as non-supplemented controls (CON; n = 605). Sows were inseminated at the detection of estrus, and again 24 h later, but only the first inseminations were supplemented. Compared to CON, only buserelin increased pregnancy and farrowing rates (p ≤ 0.05); there was no effect of a period or a treatment × period interaction. Litter size was larger (p ≤ 0.001) for all seminal additive groups during the first two periods and tended to increase in GN compared to CON (p ≤ 0.1) during the third period, resulting in a tendency (p < 0.1) for a period × treatment interaction. The addition of cloprostenol, oxytocin or buserelin to semen doses at first insemination increases litter size in multiparous sows.

A novel semen supplement (SuinFort) improves sow fertility after artificial insemination

The objective of this study was to determine effects of a novel seminal supplement, SuinFort, on fertility of multiparous sows. For 2 years, a total of 1159 sows were assigned to be artificial inseminated (AI) either with semen supplemented with the additive (2 IU oxytocin, 5 μg lecirelin, 2 mM caffeine, n = 830 AI) or with no supplementation (Control, n = 2422 AI). The supplement was included 15 min before insemination. Supplementation with SuinFort resulted in greater fertility both by increasing farrowing rate 87.2% ± 0.7 to 90.7% ± 1.0 (P <  0.001) and litter size from 13.8 ± 0.1 to 14.4 ± 0.1 (P <  0.001). To test if there was a direct effect of SuinFort on spermatozoa, an in vitro experiment was conducted using semen doses from 10 boars. Semen was stored at 15 °C and on days 1, 2 and 3 were aliquoted to a control and SuinFort-supplemented group, incubated at 37 °C and analyzed for sperm quality at 15 min and 2 h. For aliquots with SuinFort, there was a small decrease in semen quality. In conclusion, the administration of a combination of oxytocin, lecirelin and caffeine to boar semen 15 min prior to AI, positively affects sow fertility. Considering that in vitro effects on sperm quality were small, it is likely that SuinFort affects fertility by modulating uterine function. Supplementation of semen with SuinFort, therefore, has potential for increasing pork production efficiency as a result of increased reproductive efficiency after AI of sows.

Implications of boar sperm kinematics and rheotaxis for fertility after preservation

Artificial insemination (AI) is the single most important assisted reproductive technique devised to facilitate the genetic improvement of livestock. In the swine industry, it has broadly replaced natural service over the last number of decades which has been made possible by the high pregnancy rates and litter sizes obtainable with semen extended, up to, and sometimes beyond 5 d. Central to achieving good reproductive performance is the ability of boar studs to monitor semen quality, the basis of which has long been the assessment of sperm motility by subjective and, more recently, by more objective computerised systems. In this review, the literature on the relationship between sperm motility and kinematic parameters and field fertility is summarised. We discuss how this relationship is dependent on factors such as the viscosity of the media and the use of standard operating procedures. Emerging evidence is discussed regarding the importance of sperm rheotaxis and thigmotaxis as long-distance sperm guidance mechanisms, which enable motile functional spermatozoa to avoid the backflow of fluid, mucus and semen from the sow's uterus in the hours post AI, facilitating the establishment of sperm reservoirs in the oviducts. The literature on the use of microfluidics in studying sperm rheotaxis in vitro is also summarised, and we discuss how these systems, when combined with techniques such as lensless microscopy, have the potential to offer more physiological assessments of the swimming patterns of boar spermatozoa. Finally, possible future avenues of further investigation are proposed.

Morphological changes in the porcine cervix: A comparison between nulliparous and multiparous sows with regard to post-cervical artificial insemination

In recent decades, new artificial insemination (AI) methods, such as post-cervical AI (PCAI), have been developed in pig. PCAI involves crossing the cervix to deposit the sperm in the uterine body. Although PCAI application in sows is frequent, its application in nulliparous (gilts) females it is still limited due to the difficulty of passing through the cranial part of the cervical lumen. We hypothesized that ageing and parity would modify the cervical canal, facilitating the introduction of AI devices through the cervix. The aim was to compare the morphology of the uterus at different levels between multiparous and nulliparous females. Morphological analysis of the uterus pointed to a longer cervix (25.9 ± 4.6 vs. 21.6 ± 3.3 cm, p < 0.001) and greater length of the part of the reproductive tract involved in PCAI (from rima vulvae to the last cervical cushion) (56.2 ± 6.0 vs. 50.3 ± 5.2 cm, p < 0.001) in multiparous sows compared with nulliparous animals. As regards the structure of the vaginal and uterine parts of the cervix (the part in contact with the vagina and uterine body, respectively), the cross-sectional area, perimeter and total thickness were greater in the uterine part of multiparous than of nulliparous animals (area: 4.07 ± 1.46 vs. 2.46 ± 0.56 cm², p < 0.01; perimeter: 8.50 ± 1.44 cm vs. 6.28 ± 0.92 cm, p < 0.001; thickness: 10.79 ± 0.96 vs. 8.35 ± 0.62 mm, p < 0.05), but not in the vaginal part. The tissue content analysed in histological cross-sections also showed differences between female groups, a greater content of connective tissue (58.86 ± 10.78 vs. 67.60 ± 13.38%, p < 0.001) and a lower amount of muscle fibres (39.79 ± 10.24 vs. 30.66 ± 13.69%, p < 0.001) being observed in multiparous sows. Finally, silicone casts of the cervical lumen revealed differences between the two groups in the size and shape of the ridges in the lumen trajectory. Parity, which is also influenced by ageing, determines important changes in the size, structure and tissue content of the cervix wall, as well as in the morphology of the cervical canal, which may be responsible for the different levels of performance of PCAI in the female populations. Therefore, the future design of AI strategies and catheters should take into consideration the morphological variations of the cervix lumen, which will depend on age and parity of the females.

Computational multivariate modelling of electrical activity of the porcine uterus during spontaneous and hormone-induced oestrus

NEW FINDINGS

What is the central question of this study? Does oestrous cycle synchronization influence myoelectrical activity of porcine myometrium? What is the main finding and its importance? Exogenous hormones used to synchronize oestrus in pigs altered myoelectrical activity, which was effectively modelled. Higher-order multivariate statistic modelling provided evidence of similar activity in both types of oestrus, but a larger order of EMG signals during induced oestrus. Higher-order statistical analysis of the probabilistic model suggests the beginning of the early follicular phase and the mid-luteal phase to be most important in evaluation of the natural patterns of myoelectrical activity. Higher-order multivariate cumulants are more informative than classical statistics in characterization of myoelectrical activity changes in porcine myometrium.

ABSTRACT

In pig production units, control of the oestrous cycle and synchronization of ovulation have become routine herd management procedures. During the oestrous cycle, in both induced and spontaneous conditions, the ovaries and the uterus undergo hormone-dominated physiological changes, which are consistent with the hypothesis that there is a functional role of uterine contractions in promoting fertilization. We have used electromyography to determine whether the use of exogenous hormones, such as equine chorionic gonadotrophin and human chorionic gonadotrophin, which have the potential to control the timing of ovulation in female pigs, changes the multivariate relationships between parameters of electrical bursts and modulates the patterns of myoelectrical activity. We used the mathematical approach of higher-order multivariate cumulants in complex modelling of the myometrial electrical activity. The experiment was conducted on 12 mature Polish Landrace sows, and uterine activity was recorded during both spontaneous and induced oestrous cycles. The burst parameters were determined using six features in the time domain and, after Fast Fourier transformation, in the frequency domain. Evaluation of myoelectrical activity patterns was conducted based on classical univariate statistical methods and multivariate probabilistic modelling. The classical statistical approach indicated weaker myoelectrical activity after hormonal stimulation, whereas the higher-order multivariate statistical model showed evidence of similar status of activity and a larger order of signals during induced oestrus. Routine oestrous cycle synchronization affects the multivariate probabilistic model of myometrial electrical activity.

Uterine EMG activity in the non-pregnant sow during estrous cycle

BACKGROUND

Uterine myoactivity is crucial for successful reproductive performance of the sow. Spontaneous contractions of the uterus are strictly controlled and coordinated. Uterine electromyographic (EMG) activity undergoes hormonal regulation with rapid and long-term effects. What is more, interstitial Cajal-like Cells (ICLC) appear essential for smooth muscle contractility in the reproductive tract where they are suspected to be playing a major role in generating, coordinating, modulating and synchronizing slow triggering waves. The aim of this study was to investigate the myoelectrical activity of sow's uterus during estrus cycle.

RESULTS

Study was conducted on 10 Polish Landrace sows. Propagation mechanisms and their connection with the uterine EMG activity were considered in correlation with expression of c-kit, progesterone and oxytocin receptors of the non-pregnant sow. ICLC were labeled with antibody directed against c-kit receptor and visualized by confocal microscopy and scanning cytometer for positive cells percentage assessment. EMG signal was recorded directly from the myometrium with telemetry transmitters and electrodes located in different topographic regions of reproductive tracts. The stages of estrus cycle were determined by monitoring levels of luteinizing hormone, progesterone and estrogen with radioimmunoassays. Significant differences of the EMG signal parameters between diestrus and estrus and the correlations with density of labelled receptors were demonstrated. Moreover, the electrophysiological studies indicated that ICLC in the myometrium in the tip of uterine horn may participate in the regulation of slow waves duration and frequency.

CONCLUSIONS

The pattern of EMG signal propagation in the wall of the non-pregnant porcine uterus occurs in an orderly, bidirectional fashion and at distinctive speed, with no differences between diestrus and estrus.

The effect of farrowing duration and parity on preovulatory follicular size and oxytocin release of sows at subsequent oestrus

This study examined the extent to which prolonged farrowing and parity are associated with plasma oxytocin concentrations and follicular development of oestrous sows during subsequent insemination. A total of 30 sows were allocated to two groups based on farrowing duration: (i) SHORT (n = 14): 159 ± 29 min, (ii) LONG (n = 16): 533 ± 190 min. The sows were also divided into two parity classes: (i) YOUNG (n = 14): parity 2.5 ± 0.8, (ii) OLD (n = 16): parity 6.4 ± 2.3. After weaning, the ovaries were examined daily with transrectal ultrasound. On the second day of oestrus, blood samples were collected for oxytocin (OT) assay at -15, -10, -5, 0, +1, +2, +3, +4, +6, +8, +10, +15, +20, +25, +30, +40, +50 and +60 min with a boar contact between 0 and +10 min. Boar presence stimulated an increase in OT concentrations (p < .05). During boar presence, OT in the LONG group was higher than in the SHORT group (p < .01). The sows in the OLD group had a longer farrowing duration than in the YOUNG group (p < .05). OT levels and diameters of follicles were more relevant for parity than was the duration of farrowing. We therefore conclude that the OT levels and follicular development of oestrous sows are associated due to parity but difficult to be predicted from the duration of previous farrowing.

The genetics of egg retention and fertilization success in Drosophila: One step closer to understanding the transition from facultative to obligate viviparity

Oviparous, facultative egg retention enables Drosophila females to withhold fertilized eggs in their reproductive tracts until circumstances favor oviposition. The propensity to retain fertilized eggs varies greatly between species, and is correlated with other reproductive traits, such as egg size and ovariole number. While previous studies have described the phenomenon, no study to date has characterized within-species variation or the genetic basis of the trait. Here, we develop a novel microscope-based method for measuring egg retention in Drosophila females and determine the range of phenotypic variation in mated female egg retention in a subset of 91 Drosophila Genetic Reference Panel (DGRP) lines. We inferred the genetic basis of egg retention using a genome-wide association study (GWAS). Further, the scoring of more than 95,000 stained, staged eggs enabled estimates of fertilization success for each line. We found evidence that ovary- and spermathecae-related genes as well as genes affecting olfactory behavior, male mating behavior, male-female attraction and sperm motility may play a crucial role in post-mating physiology. Based on our findings we also propose potential evolutionary routes toward obligate viviparity. In particular, we propose that the loss of fecundity incurred by viviparity could be offset by benefits arising from enhanced mate discrimination, resource specialization, or modified egg morphology.

The addition of reduced glutathione to cryopreservation media induces changes in the structure of motile subpopulations of frozen-thawed boar sperm

Adding cryopreservation media with reduced glutathione (GSH) has previously been shown to maintain the motility, membrane integrity and fertilizing ability of frozen-thawed boar sperm, although the effects of GSH on good (GFE) and poor freezability (PFE) ejaculates rely upon the intrinsic ejaculate freezability. The resilience to withstand freeze-thawing procedures has previously been related to the existence of a specific distribution of motile sperm subpopulations, which differs between GFE and PFE. Thus, the main aim of this study was to determine whether the addition of GSH to freezing media has any impact on the distribution of motile sperm subpopulations in GFE and PFE. With this purpose, 18 GFE and 13 PFE were cryopreserved with or without 2 mM GSH. Sperm quality and motile subpopulations were evaluated at 30 min and 4 h post-thawing. Three subpopulations were identified and the percentages of spermatozoa belonging to the fastest and most linear subpopulation, which was referred as 'SP1', decreased over post-thawing time. Good freezability ejaculates that were cryopreserved in the presence of 2 mM exhibited a significantly higher percentage of spermatozoa belonging to SP1 than the other combinations of treatment and freezability both at 30 min (mean ± SEM: GFE-C: 16.6 ± 0.4; GFE-GSH 27.7 ± 0.6) and 4 h post-thawing (GFE-C: 7.8 ± 0.2 vs.

GFE-GSH

16.7 ± 0.4). In conclusion, the positive effect of GSH on the motility of frozen-thawed sperm is related to a specific sperm subpopulation (SP1), which could coincide with the fertile sperm one.

Reproductive tract modifications of the boar sperm surface

The sperm cell has a unique, polarized, and segregated surface that is modified extensively by the changing environments in both the male and the female reproductive tracts. The sperm cannot refresh its surface, as protein translation and membrane recycling by intracellular vesicular transport have ceased upon its maturation. So, how is the sperm surface modified in the reproductive tracts and how do these processes affect fertilization? This review traces these modifications as boar sperm travels from their liberation from the Sertoli cell into the lumen of seminiferous tubules of the testis to the site of fertilization in the ampulla of the oviduct in the sow, via an artificial insemination route. The effect of sperm dilution for artificial insemination, as well as more extensive sperm processing for in vitro fertilization, cryopreservation, or sex sorting, are also discussed with respect to how these procedures affect sperm surface organization and fertilization capacity.

Effects of natural environment on reproductive histo-morphometric dynamics of female dromedary camel

Camel shows a seasonal breeding pattern with enhanced reproductive activity during the period of low climatic temperature, high rainfall and better food conditions. Therefore, the study was conducted to explore the underlying seasonal effects on histological dimensions of reproductive tract in adult female one-humped camel (Camelus dromedarius) kept in the natural environment of Pakistan. A total 25 reproductive tracts were collected during spring, summer, autumn and winter seasons and were analysed for histo-morphometric parameters during different environmental conditions. A significant increase in number (p<0.05) and size (p<0.05) of surface with secondary and tertiary ovarian follicles was observed in winter season. The epithelial height (p<0.05) and luminal diameter (p<0.05) of infundibulum, ampulla and isthmus of uterine tubes were also significantly increased during winter season. Moreover, significantly increased length (p<0.05) and circumference (p<0.05) of uterine cornua, increased number (p<0.001) and diameter (p<0.001) of endometrial glands with enlarged surface and glandular epithelia (p<0.001) were found in winter compared to summer season. Therefore, we concluded that quiescent ovarian follicular and uterine glandular activities are the main reason of camel low breeding during summer season.

Biomathematical pattern of EMG signal propagation in smooth muscle of the non-pregnant porcine uterus

Uterine contractions are generated by myometrial smooth muscle cells (SMCs) that comprise most of the myometrial layer of the uterine wall. Aberrant uterine motility (i.e., hypo- or hyper-contractility or asynchronous contractions) has been implicated in the pathogenesis of infertility due to the failure of implantation, endometriosis and abnormal estrous cycles. The mechanism whereby the non-pregnant uterus initiates spontaneous contractions remains poorly understood. The aim of the present study was to employ linear synchronization measures for analyzing the pattern of EMG signal propagation (direction and speed) in smooth muscles of the non-pregnant porcine uterus in vivo using telemetry recording system. It has been revealed that the EMG signal conduction in the uterine wall of the non-pregnant sow does not occur at random but it rather exhibits specific directions and speed. All detectable EMG signals moved along the uterine horn in both cervico-tubal and tubo-cervical directions. The signal migration speed could be divided into the three main types or categories: i. slow basic migration rhythm (SBMR); ii. rapid basic migration rhythm (RBMR); and iii. rapid accessory migration rhythm (RAMR). In conclusion, the EMG signal propagation in smooth muscles of the porcine uterus in vivo can be assessed using a linear synchronization model. Physiological pattern of the uterine contractile activity determined in this study provides a basis for future investigations of normal and pathologicall myogenic function of the uterus.

Comparison of the porcine uterine smooth muscle contractility on days 12-14 of the estrous cycle and pregnancy

Background

Uterine contractile activity is very important for many reproductive functions including embryo transport, implantation, gestation and parturition. Abnormal contractility leads to implantation failure, spontaneous miscarriage, preterm birth and many other disorders. The objective of the present study was to assess the effects of acetylcholine (ACh), noradrenaline (NA), oxytocin (OT) and prostaglandins F_2α (PGF_2α) and E₂ (PGE₂) on the contraction of uterine strips collected from the horns of cyclic gilts (12–14 days of the estrous cycle—group I) and from pregnant (12–14 days after first insemination gilts in which one of the uterine horn was gravid (group IIa) and the second one was non-gravid (group IIb). Uterine strips consisting of the endometrium with the myometrium and myometrium alone were examined.

Results

ACh increased the tension in all groups as compared to the pretreatment period, and the increase was the highest in group IIb; the amplitude decreased in all groups, and the frequency increased mainly in groups I and IIa. NA did not affect the tension in any group, but decreased the amplitude and frequency in group IIb as compared to groups I and IIa. OT caused the highest increase in the tension in group IIb, a decrease in the amplitude and an increase in the frequency of contractions as compared to the pretreatment period. PGF_2α induced the highest increase in the tension and amplitude in group IIb, with a decline in the frequency in this group. PGE₂ increased the tension and frequency only in group IIb, and caused the greatest eduction in the amplitude in this group.

Conclusions

These results indicate that contractility of the porcine smooth muscle collected from uterine horns with embryos was different from those obtained from the uterine horns without embryos and the horns of cyclic gilts.

A comparative study of boar semen extenders with different proposed preservation times and their effect on semen quality and fertility

The present study compared the quality characteristics of boar semen diluted with three extenders of different proposed preservation times (short-term, medium-term and long-term). A part of extended semen was used for artificial insemination on the farm (30 sows/extender), while the remaining part was stored for three days (16–18 °C). Stored and used semen was also laboratory assessed at insemination time, on days 1 and 2 after the collection (day 0). The long-term extender was used for a short time, within 2 days from semen collection, with the aim to investigate a possible advantage over the others regarding laboratory or farm fertility indicators at the beginning of the preservation time. Viability, motility, kinetic indicators, morphology and DNA fragmentation were estimated. The results showed reduced viability, higher values for most of the kinetics, and higher immotile spermatozoa from day 1 to day 2 in all extenders; however, the long-term extender was superior compared to the other two on both days. With regard to morphology and chromatin integrity, the percentage of abnormal and fragmented spermatozoa increased on day 2 compared to day 1 for all of the extenders. However, based on the farrowing rate and the number of piglets born alive after the application of conventional artificial insemination within 2 days from semen collection/dilution, it was found that the medium-term diluents were more effective. In conclusion, it seems that the in vivo fertilization process involves more factors than simply the quality of laboratory evaluated sperm indicators, warranting further research.

Artificial insemination in pigs today

Use of artificial insemination (AI) for breeding pigs has been instrumental for facilitating global improvements in fertility, genetics, labor, and herd health. The establishment of AI centers for management of boars and production of semen has allowed for selection of boars for fertility and sperm production using in vitro and in vivo measures. Today, boars can be managed for production of 20 to 40 traditional AI doses containing 2.5 to 3.0 billion motile sperm in 75 to 100 mL of extender or 40 to 60 doses with 1.5 to 2.0 billion sperm in similar or reduced volumes for use in cervical or intrauterine AI. Regardless of the sperm dose, in liquid form, extenders are designed to sustain sperm fertility for 3 to 7 days. On farm, AI is the predominant form for commercial sow breeding and relies on manual detection of estrus with sows receiving two cervical or two intrauterine inseminations of the traditional or low sperm doses on each day detected in standing estrus. New approaches for increasing rates of genetic improvement through use of AI are aimed at methods to continue to lower the number of sperm in an AI dose and reducing the number of inseminations through use of a single, fixed-time AI after ovulation induction. Both approaches allow greater selection pressure for economically important swine traits in the sires and help extend the genetic advantages through AI on to more production farms.

Morphometry of boar sperm head and flagellum in semen backflow after insemination

Once deposited in the female reproductive system, sperm begin their competition and undergo a selection to reach the site of fertilization. Little is known about the special characteristics of sperm that reach the oviduct and are able to fertilize, with even less information on the role of sperm dimension and shape in transport and fertilization. Here, we examine whether sperm morphometry could be involved in their journey within the uterus. For this purpose, sperm head dimension (length, width, area, and perimeter) and shape (shape factor, ellipticity, elongation, and regularity), and flagellum length were analyzed in the backflow at different times after insemination (0-15, 16-30, and 31-60 minutes). Sperm morphometry in the backflow was also analyzed taking into account the site of semen deposition (cervical vs. intrauterine). Finally, flagellum length was measured at the uterotubal junction. Sperm analyzed in the backflow were small (head and flagellum) with different head shapes compared with sperm observed in the dose before insemination. The site of deposition influenced head morphometry and tail size both being smaller in the backflow after cervical insemination compared with intrauterine insemination. Mean tail length of sperm collected in the backflow was smaller than that in the insemination dose and at the uterotubal junction. Overall, our results suggest that sperm size may be involved in sperm transport either because of environment or through sperm selection and competence on their way to encounter the female gamete.

Boar sperm with defective motility are discriminated in the backflow moments after insemination

During insemination, a large number of spermatozoa are deposited in the female genital tract, but a very low percentage is able to colonize the site of fertilization. The influx of neutrophils into the uterine lumen and semen reflux (backflow) are known mechanisms that decrease the number of spermatozoa within the uterus. No report has attempted to ascertain whether the backflow is a random or selective process of the spermatozoa. In this work, sows were inseminated using two populations of spermatozoa in the same proportion: (1) unstained spermatozoa with high motility and (2) stained spermatozoa with low, medium, or high motility. Volume, number, and percentage of stained spermatozoa were evaluated in the backflow (collected at 0-15, 16-30, and 31-60 minutes after insemination). This article provides evidence that (1) the motility characteristics of the spermatozoa do not influence the percentage of sows with backflow, the volume and number of spermatozoa in the backflow; (2) the discarding of spermatozoa in the backflow is not specific during the first moments after insemination (0-15 minutes), whereas later (16-60 minutes), spermatozoa with defective motility (low and medium groups) are discarded in a higher proportion than high group in the backflow ([16-30 minutes: low, 85.13 ± 4.32%; medium, 72.99 ± 5.05%; and high, 54.91 ± 2.38%; P < 0.0001; 31-60 minutes: low, 87.16 ± 6.01%; medium, 87.02 ± 4.01%; and high, 59.35 ± 2.86%; P = 0.001]). Spermatozoa with poor motility are discarded in the backflow probably as a selective process, on the part of the female genital tract or as a result of the intrinsic low spermatozoa motility.

The use of oxytocin in liquid semen doses to reduce seasonal fluctuations in the reproductive performance of sows and improve litter parameters--a 2-year study

The objective of the present research was to eliminate seasonal fluctuations in year-round reproductive performance of sows and to improve litter parameters by administration of oxytocin into liquid semen insemination doses. A 2-year experiment was performed on crossbreed sows, Polish Large White × Polish Landrace, which were partitioned into two groups: control, insemination without any modification with 100 mL semen doses and oxytocin, insemination with 100 mL semen doses to which 5 IU of oxytocin was added just before insemination. A total of 10,486 inseminations were made. The farrowing rate and obtained litter parameters, including the effect of season, were analyzed. For each litter, the following factors were defined: average litter size, percentage of fetal death and mummified piglets, average piglet birth weight, percentage of piglet mortality, fecundity index, average number of piglets weaned, weaned piglet weight, and daily gain. Sows presented a positive reaction to the experimental factor. A statistically higher farrowing rate for oxytocin group in summer and autumn seasons was confirmed (P ≤ 0.01). Regardless of the season, a higher average litter size was observed in the oxytocin group with the most evident differences for winter, spring (P ≤ 0.01), and summer (P ≤ 0.05). The effect of oxytocin on the percentage of fetal death and mummified piglets born was not confirmed statistically except for winter. Analyzing the fecundity index, higher values were obtained for the oxytocin group in all seasons (P ≤ 0.01), including the lowest difference between groups for winter (51.43) and the highest for summer (100.61). A higher average birth piglet weight and weaned piglet weight were recorded for the oxytocin group in all seasons. The highest differences in birth piglet weight between groups were noted for spring (0.22 kg; P ≤ 0.01) and winter (0.17 kg; P ≤ 0.05) and in weaned piglet weight for winter and spring (0.58 kg and 0.52 kg; for both, P ≤ 0.01). The greatest daily gains were observed in the winter season (P ≤ 0.05) in favor of oxytocin. On the basis of the presented results, it should be noted that the use of oxytocin into insemination doses improves the farrowing rate and other parameters of the reproductive performance of sows. In the absence of negative effects, year-round insemination with oxytocin addition into seminal doses is recommended, which effectively improves the production performance and reduces the problem of seasonality in reproduction.

Impact of swine reproductive technologies on pig and global food production

Reproductive technologies have dramatically changed the way pigs are raised for pork production in developed and developing countries. This has involved such areas as pigs produced/sow, more consistent pig flow to market, pig growth rate and feed efficiency, carcass yield and quality, labor efficiency, and pig health. Some reproductive technologies are in widespread use for commercial pork operations [Riesenbeck, Reprod Domest Anim 46:1-3, 2011] while others are in limited use in specific segments of the industry [Knox, Reprod Domest Anim 46:4-6, 2011]. Significant changes in the efficiency of pork production have occurred as a direct result of the use of reproductive technologies that were intended to improve the transfer of genes important for food production [Gerrits et al., Theriogenology 63:283-299, 2005]. While some technologies focused on the efficiency of gene transfer, others addressed fertility and labor issues. Among livestock species, pig reproductive efficiency appears to have achieved exceptionally high rates of performance (PigCHAMP 2011) [Benchmark 2011, Ames, IA, 12-16]. From the maternal side, this includes pigs born per litter, farrowing rate, as well as litters per sow per year. On the male side, boar fertility, sperm production, and sows served per sire have improved as well [Knox et al., Theriogenology, 70:1202-1208, 2008]. These shifts in the efficiency of swine fertility have resulted in the modern pig as one of the most efficient livestock species for global food production. These reproductive changes have predominantly occurred in developed countries, but data suggests transfer and adoption of these in developing countries as well (FAO STAT 2009; FAS 2006) [World pig meat production: food and agriculture organization of the United Nations, 2009; FAS, 2006) Worldwide Pork Production, 2006]. Technological advancements in swine reproduction have had profound effects on industry structure, production, efficiency, quality, and profitability. In all cases, the adoption of these technologies has aided in the creation of a sustainable supply of safe and affordable pork for consumers around the world [den Hartog, Adv Pork Prod 15:17-24, 2004].

Prolonged duration of farrowing is associated with subsequent decreased fertility in sows

In modern swine production failure of sows to become pregnant within the expected time after weaning results in major economic loss and culling of sows. The objective of this study was to determine the effects of duration of farrowing on subsequent repeat breeding rate. The study was performed in a commercial sow-pool piggery system in Finland comprising 148 sows (Yorkshire × Landrace). A multivariate analysis was undertaken on data for parity, weaning to estrus interval, boar, number of inseminations, season, sow back-fat thickness, gestation length, duration of farrowing, number of live-born piglets, number of stillborn piglets, lactation length, and number of piglets weaned. Furthermore, two farrowing systems (crate vs. pen) were investigated. A binary logistic regression was used to analyze the effect of these factors on the repeat breeding rate (pregnant vs. not pregnant at first insemination after weaning). The total duration of previous farrowing was longer in rebred sows (357 ± 207 minutes, average ± SD) than in pregnant sows (255 ± 126 minutes; P < 0.01). The other parameters were not statistically significant to the outcome of first insemination after weaning. In conclusion, we established that sows with long duration of farrowing have higher repeat breeding rate at the first insemination after weaning and could be used as an indicator for subsequent fertility.

Participation of analogues of lysophosphatidic acid (LPA): oleoyl-sn-glycero-3-phosphate (L-α-LPA) and 1-oleoyl-2-O-methyl-rac-glycerophosphothionate (OMPT) in uterine smooth muscle contractility of the pregnant pigs

Recent studies show that a representative of phospholipids, namely lysophosphatidic acid (LPA) and its receptors (LPA1-3) play a significant role in the reproductive processes, i. a, in the modulation of the uterine contractility. The participation of LPA3 in the reproductive processes has been revealed in mice and has not been studied in gilts. Therefore, in the present study we investigated the role/action of LPA and its receptors LPA1, LPA2 and LPA3 on the contraction activity in the porcine uterus. The study was conducted on an experimental model in which the pig uterus consisted of the one whole uterine horn and a part of the second horn, both connected with the uterine corpus. Uterine strips consisting of the endometrium with the myometrium (ENDO/MYO) and myometrium (MYO) alone were collected on days 12-14 of the estrous cycle (control group; n = 5) or pregnancy (experimental group; n = 5). Two analogues of LPA at increasing doses were used: oleoyl-sn-glycero- 3-phosphate (L-α-LPA, a selective agonist of LPA1 and LPA2 receptors; 10-7 M; 10-6 M and 10-5 M) and 1-oleoyl-2-O-methyl-rac-glycerophosphothionate (OMPT, a selective agonist of LPA3 receptor; 68 nM; 136 nM and 680 nM). L-α-LPA caused an increase in the contraction tension, amplitude and frequency of ENDO/MYO from the uterine horn with the developing embryos. This effect was not observed in MYO in both groups examined. In the ENDO/MYO strips of the uterine horn with developing embryos, OMPT significantly increased the contraction tension at the highest dose (680 nM) and amplitude at all doses examined, while frequency of contractions was decreased at doses of 136 nM and 680 nM. In the MYO strips of the uterine horn with embryos a significant increase in the contraction tension and amplitude after the highest dose of OMPT was observed. The results obtained imply the important role of receptors LPA1 , LPA2 and LPA3 in the contraction activity of the porcine uterus during early pregnancy.

Reproductive performance and backflow study in cervical and post-cervical artificial insemination in sows

The present study was developed to evaluate multiparous sow reproductive performance and backflow in post-cervical artificial insemination (post-CAI) using a reduced number of sperm than in cervical artificial insemination (CAI). The experimental groups were divided into sows inseminated by: 1) cervical artificial insemination (CAI): 3×10(9) spermatozoa/80 ml; 2) post-CAI: 1.5×10(9) spermatozoa/40 ml (post-CAI 1); 3) post-CAI using 1×10(9) spermatozoa/26 ml (post-CAI 2). Post-CAI 1 reproductive parameters were similar to those of post-CAI 2 (except for live born litter size which was greater in post-CAI 1) and better than for the CAI group (p<0.01). In a second experiment the backflow volume, number of sperm, and sperm quality in the backflow were studied in the 3 experimental groups. The % of volume and spermatozoa in the backflow was higher in the CAI group (p<0.05) than post-CAI groups (statistically similar between them). Moreover, the quality parameters (motility, progressive motility, viability, chromatin decondensation and morphology) in backflow semen were identical in all three experimental groups, but differed as regards the original insemination dose incubated inside a colostomy bag (sperm quality control group). The present study shows that the use of post-CAI (either post-CAI 1 or 2) in field conditions can be recommended because the efficiency is similar (in the case of post-CAI 2) or higher (post-CAI 1) than when using the traditional method (CAI), representing a reduction cost.

Effect of acute bull exposure around the time of artificial insemination on serum oxytocin and progesterone concentrations and pregnancy rates in dairy cows

This study examined the effect of acute bull exposure around the time of artificial insemination (AI) on oxytocin and progesterone concentrations, and pregnancy rates in dairy cows. Ninety six dairy cows, stratified according to parity into primiparous and pluriparous, were divided into three groups; short bull exposure (SBE; 10 min, n = 32), long bull exposure (LBE; 4 h, n = 32) or no bull exposure (NBE; n = 32). On day 45 post-partum, all cows were treated with PGF2α on three occasions 11-14 days apart to synchronize oestrus. They were submitted to fixed time AI 80 h after the third PGF2α injection. Cows in the SBE and LBE groups were artificially inseminated 5 min after the introduction of the bull. From a subset of cows (n = 6 per group; three primiparous and three pluriparous), blood samples were collected once every 5 min starting 15 min before AI until 15 min after AI and analysed for oxytocin concentrations. Additional blood samples were collected for measurements of progesterone (P4) concentrations once daily for 4 days starting on the day of AI and once every 3 days thereafter until day 22. The effects of bull exposure, time, parity, difficulty of AI, and pregnancy on oxytocin and P4 concentrations were analysed using the mixed linear model procedure. Mean oxytocin concentrations or change in oxytocin concentrations after bull exposure or AI were not different among groups. Pregnancy rates for the NBE, SBE and LBE groups were 55.5%, 33.3% and 44.4%, respectively, and were not different among groups. In conclusion, acute bull exposure around the time of AI did not affect oxytocin and progesterone concentrations and did not improve pregnancy rates in dairy cattle under these farms conditions.

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.

Progestagen supplementation during early pregnancy does not improve embryo survival in pigs

Progesterone supplementation during early pregnancy may increase embryo survival in pigs. The current study evaluated whether oral supplementation with an analogue of progesterone, altrenogest (ALT), affects embryo survival. A first experiment evaluated the effect of a daily 20-mg dosage of ALT during days 1-4 or 2-4 after onset of oestrus on embryo survival at day 42 of pregnancy. A control group (CTR1) was not treated. The time of ovulation was estimated by transrectal ultrasound at 12-h intervals. Altrenogest treatment significantly reduced pregnancy rate when start of treatment was before or at ovulation: 25% (5/20) compared to later start of treatment [85% (28/33)] and non-treated CTR1 [100% (23/23)]. Altrenogest treatment also reduced (p < 0.05) number of foetuses, from 14.6 ± 2.6 in CTR1 to 12.5 ± 2.5 when ALT started 1-1.5 days from ovulation and 10.7 ± 2.9 when ALT started 0-0.5 days from ovulation. In a second experiment, sows with a weaning-to-oestrous interval (WOI) of 6, 7 or 8-14 days were given ALT [either 20 mg (ALT20; n = 49) or 10 mg (ALT10; n = 48)] at day 4 and day 6 after onset of oestrus or were not treated (CTR2; n = 49), and farrowing rate and litter size were evaluated. Weaning-to-oestrous interval did not affect farrowing rate or litter size. ALT did not affect farrowing rate (86% vs 90% in CTR2), but ALT20 tended to have a lower litter size compared with CTR2 (11.7 ± 4.1 vs 13.3 ± 3.1; p = 0.07) and ALT10 was intermediate (12.3 ± 2.9). In conclusion, altrenogest supplementation too soon after ovulation reduces fertilization rate and embryo survival rate and altrenogest supplementation at 4-6 days of pregnancy reduces litter size. As a consequence, altrenogest supplementation during early pregnancy may reduce both farrowing rate and litter size and cannot be applied at this stage in practice as a remedy against low litter size.

Use of a novel double uterine deposition artificial insemination technique using low concentrations of sperm in pigs

Currently, the three most important non-surgical artificial insemination systems used in pigs are the conventional, the post-cervical (IUI), and the deep-intrauterine (DIUI) methods. In this study, a new system, termed double uterine deposition insemination (DUDI), which combines aspects of both IUI and DIUI, was evaluated. This method used a thinner, shorter and more flexible catheter than those normally used for DIUI and resulted in the deposition of semen post-cervically, approximately half-way along the uterine horn, thus potentially by-passing the threat of 'unilateral' insemination or pregnancy when using sperm of low concentration. The experiment was carried out over 8 weeks on a group of 166 sows, which were divided into seven groups, inseminated with semen of varying concentration, using the conventional system (control group) or by DUDI. There were no significant differences in fertility at day 35 post-insemination between the controls and the various DUDI sub-groups. Only sows inseminated with 500 million viable spermatozoa in a total of 30 mL of fluid using the DUDI system demonstrated decreased total litter sizes when compared to conventional insemination (P<0.001). While conventional insemination normally uses 2.5-3.5 billion sperm, the findings of this study suggest that DUDI can be used under 'field' conditions with sperm concentrations as low as 750 million spermatozoa in 50-30 mL without any detrimental effect on fertility or litter size. DUDI may provide a viable, robust alternative to IUI and DIUI, and has the potential to become incorporated into on-farm insemination systems.

Battle and ballet: molecular interactions between the sexes in Drosophila

Varied and fascinating interactions occur between males and females to lead to the production of progeny. Interactions between the sexes continue even after the act of mating-but at the molecular and cellular level instead of between individual animals. Molecules transferred from males to females during mating (via the seminal fluid) exert potent effects on females' physiology and (at least in some animals) on behavior. Taking advantage of genetic, genomic, and biochemical tools for Drosophila, we investigate molecular interactions that underlie this form of chemical communication. Recent data show that molecules and cells from both sexes participate in this "ballet," facilitating the mutually beneficial outcome of increased progeny production. Examples to be presented include the storage and utilization of sperm in the mated female, and a proteolytic pathway that begins in the male but ends in the female and involves both male and female contributions. Despite the joint benefit of increased progeny production, the "interests" of the mating male can differ from those of his mate. Over evolutionary time this disconnect can, in theory, precipitate a "battle" between the sexes, potentially leading to the rapid sequence changes that have been observed for some seminal proteins across species.