Allogenic mesenchymal stem cell-conditioned medium does not affect sperm parameters and mitigates early endometrial inflammatory responses in mares

This study aimed to evaluate the effects of mesenchymal stem cell-conditioned medium (MSC-CM) on sperm parameters, intrauterine polymorphonuclear neutrophils (PMN), intrauterine fluid accumulation (IUF), and fertility in mares. In experiment 1, two ejaculates from ten stallions were extended to 50 million sperm/mL using a milk-based extender. Thereafter, 20 mL of extended semen was added of MSC-CM as follows: 0, 5, 10, 15, and 20 mL. Sperm kinetics and plasma membrane integrity were evaluated immediately after dilution (T0) and 2 h post-incubation at 37 °C (T2). In experiment 2, mares characterized as resistant (n = 13) or susceptible (n = 7) to endometritis were inseminated with fresh semen 24 h post-induction of ovulation in two (Control and CM-1) and three (Control, CM-1, and CM-2) cycles in a crossover, as follows: control, no pharmacological interference; CM-1, supplementation of semen insemination dose at 3:4 (v:v, MSC-CM:semen); CM-2, 30 mL of MSC-CM was infused into the uterus 24 h before insemination. Endometrial cytology and uterine fluid were collected 6 and 24 h after insemination to evaluate the number of PMNs and concentrations of interleukins IL6, IL10, and TNFα. IUF was determined by ultrasonography 24 and 48 h after insemination. Pregnancy status was diagnosed 14 days after ovulation. The addition of MSC-CM to semen did not influence sperm parameters at T0 and T2 (P > 0.05) and reduced (CM-1; P < 0.05) the number of PMNs at 6 h post-insemination in resistant mares. In susceptible mares, PMNs at 6 and 24 h post-insemination, as well as IUF were reduced (P < 0.05) in both treated cycles (CM-1 and CM-2). In addition, MSC-CM downregulated IL6 and upregulated IL10 concentrations in the uterus of susceptible mares after insemination. There were no differences in fertility rates among groups both in resistant (Control, 77%, 10/13; CM-1, 62%, 8/13) and susceptible mares (Control, 42.8%, 3/7; CM-1, 57.1%, 4/7; CM-2, 85.7%. 6/7). In conclusion, MSC-CM did not affect sperm parameters when mixed with diluted semen, and reduced post-insemination inflammatory responses in mares.

Clinical safety of intratesticular transplantation of allogeneic bone marrow multipotent stromal cells in stallions

Although stem cell therapy is a promising alternative for treatment of degenerative diseases, there are just few reports on the use of stem cells therapy in horse's reproductive system. This study aims to evaluate the effect of intratesticular injection of bone marrow mesenchymal stromal/stem cells (MSCs) in healthy stallions, and its outcome on seminal parameters and fertility. In Experiment 1, 24 stallions were divided into treatment group (TG) and control group (CG). In the TG, an intratesticular application of MSC was performed, and in the CG, only PBS was used. Measurements of testicular volume, surface temperature and Doppler ultrasonography were performed 24 and 48 hr after treatments. Fifteen days after application, the testicles were removed and submitted to histological analysis. In Experiment 2, 3 fertile stallions received similarly treatment with MSCs. Physical examination and sperm analysis were performed weekly during 60 days after treatment, and at the end, semen from one of them was used for artificial inseminations of 6 healthy mares. In Experiment 1, clinical examinations showed no signals of acute inflammation on both groups according to the analysed variables (p > .05). Also, no signal of chronic inflammation was observed on histological evaluation. In Experiment 2, stallions presented no physical alterations or changes in sperm parameters, and a satisfactory fertility rate (83%; 5/6) was observed after AI. The results support the hypothesis that intratesticular application of bone marrow MSCs is a safe procedure, and this could be a promising alternative to treat testicular degenerative conditions.

Coconut Water as an Extender Component for Cooled Equine Sperm

The aim of this study was to evaluate the effect of coconut water as a component of extender in different formulations for cooling equine sperm. One ejaculate of fourteen stallions was collected. Sperm was diluted to 50 × 10⁶ sperm/mL using five different extenders: ACP-105: powdered coconut water extender (ACP-105, ACP Biotecnologia, Brazil); ACP-Milk: ACP-105 + 20 g/L of skimmed milk; ACP-EY 2.5%: ACP-105 + 2.5% of egg yolk; ACP-EY 5%: ACP-105 + 5% of egg yolk; and BotuSêmen (Botupharma, Botucatu, Brazil) and cooled in passive cooling device (BotuFlex, Botupharma, Botucatu, Brazil) at 5 and 15°C for 24 hours. Sperm kinetics and plasma membrane integrity (PMI) were evaluated by computer-assisted sperm analysis and fluorescence staining, respectively, at T0 (before cooling) and T24 (24 hours after cooling). Sperm kinetics did not differ at T0 among groups (P > .05); however, at T24, these parameters were significantly lower in ACP-105 (5°C, total motility [TM]: 9.2 ± 3.6%; progressive motility [PM]: 2.7 ± 1.6%; percentage of fast-moving spermatozoa [RAP]: 4.8 ± 3.0%; 15°C, TM: 10.6 ± 3.0%; PM: 1.1 ± 0.5%; RAP: 4.8 ± 1.9%) and ACP-EY 5% (5°C, TM: 28.0 ± 6.3%; PM: 5.7 ± 1.8%; RAP: 15.9 ± 6.0%; 15°C, TM: 30.0 ± 6.0%; PM: 6.9 ± 2.1%; RAP: 17.6 ± 5.3%) compared with BotuSêmen (5°C, TM: 66.2 ± 5.6%; PM: 21.1 ± 2.8%; RAP: 53.9 ± 6.1%; 15°C, TM: 63.4 ± 5.4%; PM: 17.2 ± 2.8%; RAP: 51.4 ± 6.3%) (P < .05). All groups exhibited similar PMI at tested moments and cooling temperatures (5°C: 83%; 15°C: 84%) (P > .05). Further studies are necessary to evaluate powdered coconut water in different compositions of sperm extender; however, coconut-based extender as used in this study was not an alternative to preserve sperm parameters of cooled equine sperm.

Variable Inter-assay Estimation of Sperm DNA Fragmentation In Stallions Classified as Good and Bad Semen Freezers

BACKGROUND

Semen cryopreservation causes DNA damage, thus requiring continuous monitoring.

OBJECTIVE

To compare two assays for sperm DNA fragmentation (SDF) from stallions with contrasting semen freezability.

MATERIALS AND METHODS

Thirteen stallions were classified as good semen freezers (GSF) or bad semen freezers (BSF). Ejaculates were cryopreserved with three diluents. Semen was subject to SDF evaluation using the sperm chromatin structure assay (SCSA) and Halomax after thawing (0 h) and after a 4 h thermoresistance test.

RESULTS

On semen of BSF, analysis by SCSA was similar between evaluations, but Halomax showed increased SDF at 4 h. The GSF group was similar between time points in both assays. Diluents did not affect SDF, irrespective of the assay. Halomax showed differences for BSF between time points, differently from SCSA. Linear regression did not show any correlation between assays.

CONCLUSION

The use of Halomax should be encouraged for sperm DNA fragmentation analysis in horse frozen-thawed semen, particularly under field conditions.

Uterine clinical findings, fertility rate, leucocyte migration, and COX-2 protein levels in the endometrial tissue of susceptible mares treated with platelet-rich plasma before and after AI

Persistent mating-induced endometritis (PMIE) results in decreased fertility in horses, thereby causing a significant impact in the horse market. Platelet-rich plasma (PRP), a modulator of the inflammatory response, has been largely used in veterinary medicine. Here, we investigated the effects of PRP on uterine inflammation, conception rate, endometrial polymorphonuclear neutrophil (PMN) migration, and COX-2 protein levels in the endometrial tissue. Thirteen PMIE-susceptible mares were used for artificial insemination (AI). The mares were inseminated with fresh semen in three consecutive cycles in a cross-over study design. The following cycle classifications were used: control cycle, no pharmacological interference; pre-AI, 20 mL of PRP was infused 24 h before AI; and post-AI, 20 mL of PRP was infused four h after AI. Follicular dynamics were monitored daily by transrectal ultrasound. When a follicle larger than 35 mm was detected, ovulation was induced with deslorelin acetate (1 mg, im). AI was performed 24 h after ovulation induction. Intrauterine fluid (FLU) was evaluated by ultrasonography before and 24 h after AI. PMNs in uterine cytology (CYT) and biopsy (HIS) were also observed before and 24 h after AI. Pregnancy was determined within 14 days after ovulation. Number of COX-2 positive cells was evaluated by immunohistochemistry. Both PRP treatments resulted in a decrease of PMNs in the CYT after breeding when compared to controls. FLU did not differ between cycles; however, the conception rates were significantly higher in the PRP mares. Mares positive for endometritis decreased in both treatment groups, and a more intense positive COX-2 labeling was observed in the control group when compared to the two treatment groups. In conclusion, PRP beneficially reduces inflammatory response in PMIE mares independent of when treatments were administered, thus increasing chances of successful pregnancy.

Seminal plasma arising from the whole boar sperm-rich fraction increases the stability of sperm membrane after thawing

Boar spermatozoa arising from the sperm-rich ejaculate fraction are reported to have a more stable plasma membrane and are more resistant to cold shock and premature acrosome reaction than spermatozoa from the whole ejaculate. Furthermore, seminal plasma (SP) can increase the cryotolerance of boar spermatozoa, and in other domestic species, it has the ability to reverse cryopreservation damage. This study aimed to evaluate the effects of boar SP arising from the whole sperm-rich ejaculate fraction (SP-SRF) on the integrity, stability, and peroxidation of sperm membranes after thawing. Each ejaculate ( = 24) was divided among 4 treatments: control (CT), centrifuged and suspended in autologous SP-SRF (CS), centrifuged with withdrawn SP-SRF (CW), and post-thawed SP arising from the whole sperm-rich fraction addition to CW (CWSP). After thawing, all treatments were incubated for 5, 60, and 120 min and were analyzed for membrane integrity, fluidity, and peroxidation by flow cytometer. The absence of SP-SRF increased the lipid disorder ( < 0.05) but had no effect on lipid peroxidation ( > 0.05) or membrane integrity ( > 0.05). However, the increase in lipid disorder by withdrawal of SP-SRF was reversed by SP-SRF addition ( < 0.05) to the post-thawing medium, whereas plasma and acrosomal membrane integrity ( > 0.05) and lipid peroxidation ( > 0.05) were unchanged. In conclusion, despite the centrifugation effects, the addition of SP arising from the whole sperm-rich fraction to post-thawed boar semen decreased sperm lipid disorder without an influence of the sperm membrane integrity and peroxidation.

Comparison of cushioned centrifugation and SpermFilter filtration on longevity and morphology of cooled-stored equine semen

This study compares two methods for seminal plasma removal by evaluating sperm recovery rates, and motility and morphology of cooled-stored semen. Ejaculates were divided into three groups: control, filtration and cushioned centrifugation. Semen was extended to 25 million sperm/ml using a skim-milk-based extender and stored at 5°C for all groups. Sperm motility (total motility (%TM) and progressive motility (%PM)) was determined at 0, 24, 48 and 72 hours by a computer-assisted sperm analyser. Sperm morphology was assessed using differential interference microscopy. Overall, %TM of the centrifugation group was significantly higher than the filter group, but not significantly different than the control. No significant difference in %TM or %PM was detected for the control group and filter. Cushioned centrifugation was a superior method to obtain progressively motile sperm compared with control (P=0.03) and filter groups (P<0.001). No significant difference was found for the per cent of normal sperm cells and detached heads between the groups. This study demonstrated that cushioned centrifugation was a superior method to remove seminal plasma while preserving %TM and enhancing %PM for stallions under cooled storage over three days. However, as the differences appear to be negligible, the SpermFilter may represent an alternative for farms lacking a centrifuge.

Does Clinical Treatment with Phenylbutazone and Meloxicam in the Pre-ovulatory Period Influence the Ovulation Rate in Mares?

The presence of anovulatory haemorrhagic follicles during the oestrous cycle of mares causes financial impacts, slowing conception and increasing the number of services per pregnancy. Non-steroidal anti-inflammatory drugs (NSAIDs) such as meloxicam and phenylbutazone are used in the treatment of several disorders in mares, and these drugs can impair the formation of prostaglandins (PGs) and consequently interfere with reproductive activity. This study aimed to evaluate the effects of treatment with NSAIDs on the development of pre-ovulatory follicles in mares. In total, 11 mares were studied over three consecutive oestrous cycles, and gynaecological and ultrasound examinations were performed every 12 h. When 32-mm-diameter follicles were detected, 1 mg of deslorelin was administered to induce ovulation. The first cycle was used as a control, and the mares received only a dose of deslorelin. In the subsequent cycles, in addition to receiving the same dose of deslorelin, each mare was treated with NSAIDs. In the second cycle, 4.4 mg/kg of phenylbutazone was administered, and in the third cycle, 0.6 mg/kg of meloxicam was administered once a day until ovulation or the beginning of follicular haemorrhage. All of the mares ovulated between 36 and 48 h after the induction in the control cycle. In the meloxicam cycle, 10 mares (92%) did not ovulate, while in the phenylbutazone cycle, nine mares (83%) did not ovulate. In both treatments, intrafollicular hyperechoic spots indicative of haemorrhagic follicles were observed on ultrasound. Thus, our results suggested that treatment with meloxicam and phenylbutazone at therapeutic doses induced intrafollicular haemorrhage and luteinization of anovulatory follicles.

Induction of double ovulation in mares using deslorelin acetate

This study aimed to determine whether deslorelin acetate could induce double ovulation in mares. In Experiment 1, eight mares were treated with prostaglandin on Day 8 (D8) after ovulation, then treated with saline or with 100 μg of a controlled-release formulation of deslorelin acetate vehicle intramuscularly (IM) every 12h from D8 after ovulation until at least two follicles reached 33 mm. At this time, ovulation was induced with 2500 IU of hCG. Artificial insemination was performed 24h after induction, and embryos were collected on the eighth day after ovulation was first detected. In Experiment 2, 112 estrous cycles in 56 mares were studied. In this experiment, the deslorelin acetate protocol was initiated only in mares that achieved a follicle with a diameter of at least 25 mm and at least one second follicle with a diameter≥20mm was detected, at which time 100 μg deslorelin acetate or saline was administered IM every 12h. The other procedures were similar to those described in Experiment 1. The variables studied were analyzed using Student's t-test and Fisher's exact test. In Experiment 1, only two mares in deslorelin group having second follicles of 20-25 mm on responded with double ovulation. In the second experiment, 82% of treated mares responded with double ovulation, and the embryo recovery per estrous cycle was 1.12 and 0.57 in the group treated with deslorelin acetate and the control group, respectively (P<0.05). Deslorelin acetate is effective in inducing double ovulation in mares using the protocol proposed. On average, it allows for the recovery of one embryo by uterine flushing.

Replacing egg yolk with soybean lecithin in the cryopreservation of stallion semen

The objective of this study was to determine whether replacing the egg yolk with soybean lecithin in the Botu-Crio® cryodiluent would maintain the fertility of cryopreserved stallion sperm. Two experiments were performed to evaluate cell freezability. In experiment 1, sperm from 15 stallions were frozen in Botu-Crio® (BC) or Botu-Crio® which contained 45g/L soybean lecithin (BCLS45) in place of the egg yolk. In experiment 2, we compared different concentrations of soybean lecithin: 0, 10.0, 12.5, 15.0, 17.5 and 20.0g/L (BC, BCLS10, BCLS12.5, BCLS17.5 and BCLS20, respectively). In experiment 1, sperm frozen in BC and BCLS45 exhibited similar (P>0.05) percentages of total motile sperm (61% and 61%, respectively); progressively motile sperm (27% and 27%, respectively) and sperm with intact plasma membranes (IMP; 53% and 57%, respectively). Similarly, sperm frozen in BC or BC containing any concentration of soybean lecithin maintained similar (P>0.05) percentages of total motile sperm (61-68%) and progressively motile sperm (27-31%). In the first fertility trial, we used cryopreserved semen from a single stallion was inseminated into mares. The semen from the sperm that were frozen in BC diluent resulted in a higher fertility rate (66%, 16/24) compared to the sperm that were frozen in BCLS45 diluent (17%, 5/29; P<0.01). Similarly, in a second fertility trial, the mares that were inseminated with the sperm that were frozen in BC diluent exhibited a higher fertility rate (66%, 16/24) compared to the mares that were inseminated with the sperm that were frozen in BCLS20 (40%, 10/25; P<0.05). Finally, in a third trial, the sperm that were frozen in BC resulted in a higher fertility rate in mares (75%, 18/24) compared to the sperm that were frozen in BCLS10 (41%, 10/24; P<0.05). Although replacing the egg yolk in the BC cryodiluent with soybean lecithin provided similar laboratory results for stallion sperm, after cryopreservation, the sperm that was frozen with soybean lecithin in the diluent correlated with lower fertility rates. Based on these results, we concluded that the use of BCLS can be used as an alternative diluent for cryopreserving stallion sperm. However, the resulting reduced fertility rate is a matter of concern. Further studies are necessary to clarify the reasons for this decrease in fertility and to determine the optimal lecithin concentration for diluents to freeze stallion sperm.

Extreme subcutaneous, intramuscular and inhaled insulin resistance treated by pancreas transplantation alone

Diabetes mellitus with resistance to insulin administered subcutaneously or intramuscularly (DRIASM) is a rare syndrome and is usually treated with continuous intravenous insulin infusion. We present here two cases of DRIASM in 16 and 18 years female patients that were submitted to pancreas transplantation alone (PTA). Both were diagnosed with type 1 diabetes as young children and had labile glycemic control with recurrent episodes of diabetic ketoacidosis. They had prolonged periods of hospitalization and complications related to their central venous access. Exocrine and endocrine drainages were in the bladder and systemic, respectively. Both presented immediate graft function. In patient 1, enteric conversion was necessary due to reflux pancreatitis. Patient 2 developed mild postoperative hyperglycemia in spite of having normal pancreas allograft biopsy and that was attributed to her immunosuppressive regimen. Patient 1 died 9 months after PTA from septic shock related to pneumonia. In 8 months of follow-up, Patient 2 presented optimal glycemic control without the use of antidiabetic agents. In conclusion, PTA may be an alternative treatment for DRIASM patients.

Viability and cell cycle analysis of equine fibroblasts cultured in vitro

This experiment aimed to study equine fibroblasts in culture analyzing and the cell cycle and viability of cells pre- and post-freezing. Skin fragments were obtained from 6 horses and cultured in DMEM high glucose + 10% FCS in 5% CO(2) until the beginning of confluence. Two passages were performed before freezing. Cells subjected to serum starvation (0.5% FCS) were analyzed for viability and cell cycle at 24, 48, 72, 96, 120, 144 and 168 h of culture. For the confluent groups, cells were analyzed at the moment they achieved confluence. Cellular viability was assisted with Hoescht 33342 and propidium iodide. The analysis of apoptosis/necrosis and cell cycle was performed using a flow cytometer (FACS Calibur BD((R))) after staining the cells with annexin V and propidium iodide. Both optical microscopy and flow cytometry confirmed that cellular viability was similar for serum starvation and confluent groups (average 84%). Similarly, both methods were efficient to synchronize the cell cycle before freezing. However, after thawing, serum starvation, for more than 24 h, was superior to culture for synchronizing cells in G0/G1 (69% x 90%). The results of this experiment indicate that equine fibroblasts can be efficiently cultured after thawing.

Microencapsulation of antibiotic rifampicin in poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The aim of this study was the preparation of microparticles containing rifampicin using a biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) for oral administration produced by a bacteria. The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microparticles with and without rifampicin were prepared by the emulsification and solvent evaporation method, in which chloroform and polyvinyl alcohol are used as the solvent and emulsifier, respectively. Microparticles were obtained within a size range of 20-60 microm by changing the initial poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polyvinyl alcohol and rifampicin concentrations. An encapsulation efficiency value of 14% was obtained. The optimized total yield of 60% of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/ rifampicin was obtained. A load of 0.035 mg/1 mg of PHBV was reached. Almost 90% of the drug loaded in the microparticles was released after 24 h. The size, encapsulation efficiency and ribampicin release of the microparticles varied as a function of the initial poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polyvinyl alcohol and rifampicin concentrations. It was demonstrated that the microencapsulated rifampicin, although was not totally available in the medium, exhibited a similar inhibition value as free rifampicin at 24 h of incubation with S. aureus. Cytotoxicity assays demonstrated a reduction of the toxicity when rifampicin was microencapsulated in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) while maintaining its antibacterial activity.

Freezing of stallion epididymal sperm

Inseminations with frozen-thawed epididymal sperm have resulted in low-pregnancy rates of mares. If fertility of epididymal sperm could be improved, it would help to preserve genetic material from stallions that have suffered severe injuries, been castrated or have died. The aim of the present study was to investigate the effect of different extenders and pre-freezing addition of capacitation media on freezability of epididymal sperm and on storage at 5 degrees C for 24h. In experiment 1, epididymal sperm samples were diluted and subsequently frozen with three different extenders: Botu-Crio, EDTA-Lactose and INRA-82. Motility analysis using computer assisted sperm analyzer (CASA) demonstrated better motility for sperm in Botu-Crio than in the other extenders; EDTA-Lactose yielded better motility than INRA-82 on most evaluated parameters. There was no difference in membrane integrity among the studied extenders. From 18 inseminated mares, 12 (66%) were pregnant 15 days after AI with frozen-thawed epididymal sperm showing that Botu-Crio was able to maintain the fertility potential. In experiment 2, the effect of incubation of epididymal sperm before freezing in three capacitation media (Fert Talp, Sperm Talp, Talp+Progesterone), seminal plasma, or control was tested. Based on post-thaw motility evaluation by CASA, samples incubated in Sperm Talp showed better motility values. There were no differences in plasma or acrosomal membranes or in mitochondrial potential among groups. We concluded that Botu-Crio was better than the other extenders in the ability to preserve epididymal sperm and that pre-freeze addition of Sperm Talp was also beneficial.

Utilização do primeiro ciclo ovulatório da estação reprodutiva para produção de embriões em éguas sob condições tropicais

A eficiência da primeira ovulação da estação reprodutiva para a produção de embriões foi determinada através da taxa de recuperação embrionária, da viabilidade dos embriões recuperados, da concentração sérica de progesterona, da resposta do primeiro folículo pré-ovulatório da estação reprodutiva ao hCG e da resposta do primeiro CL a PGF2±. Treze éguas que estavam no período de anestro ou inicial da transição de primavera foram acompanhadas por ultra-sonografia até a detecção do primeiro folículo pré-ovulatório. Neste momento a ovulação foi induzida com 2500 UI de hCG (IV) e elas foram inseminadas em dias alternados até a ovulação. Sete dias após a detecção da ovulação foi realizada coleta de embrião e a concentração de P4 foi determinada. A partir da detecção do primeiro folículo >; 25mm da estação, as éguas demoraram em média 14,92 ± 10,80 dias para alcançarem o primeiro folículo pré-ovulatório e 18,00 ± 11,08 dias para ovularem, sendo que 11/13 éguas ovularam em até 48 horas após a administração do hCG. Estes folículos cresceram em média 2,19 ± 0,86 mm/dia. Nove das 13 éguas (69,2%) produziram embriões e todos foram considerados viáveis após avaliação visual e pelo exame de fluorescência. Os corpos lúteos formados mostraram-se funcionalmente competentes produzindo em média 7,39 ± 2,11 ng/ml de P4, além de serem responsivos à PGF2±. Deste modo, o primeiro ciclo ovulatório do ano pode ser utilizado com sucesso para a produção de embriões viáveis.

Amides as cryoprotectants for freezing stallion semen: A review

Stallion semen cryopreservation, despite its impact on the horse industry, is not an established technology. During the last years, a number of modifications have been proposed to the freezing process, however, a large population of stallions still have poor semen quality and fertility after frozen-thawed. Glycerol toxicity could be a reason for the variation on stallion sperm freezability. There are limited publications concerning the use of alternative cryoprotectants for equine sperm. Glycerol is contraceptive for some species and other cryoprotectors, such as amides, have been show to be a good option for freezing semen of these species. Recent reports have shown encouraging data respecting the use of amides as cryoprotectants for stallions, with more remarkable improvements for semen from stallions that freeze poorly when glycerol is used.

Penetration of zona-free hamster, bovine and equine oocytes by stallion and bull spermatozoa pretreated with equine follicular fluid, dilauroylphosphatidylcholine or calcium ionophore A23187

Experiments evaluated the ability of follicular fluid (FF), dilauroylphosphatidylcholine (PC12) and the calcium ionophore A23187 (A23187) to induce capacitation in stallion and bull spermatozoa, determined by the ability of the spermatozoa to penetrate zona-free hamster, bovine and equine oocytes. Spermatozoa suspensions were incubated at 37 degrees C in one of the following treatments: 1) a modified Tyrode's medium (BGM3) alone; 2) BGM3 + FF; 3) BGM3 + PC12; 4) BGM3 + FF + PC12; 5) BGM3 + A23187; and 6) BGM3 + FF + A23187. Treated spermatozoa were incubated with zona-free hamster, bovine and equine oocytes for 3 h, after which oocytes were stained to assess spermatozoa penetration. The number of hamster oocytes penetrated by spermatozoa incubated in BGM3 alone (1/30) or in presence of FF (2/31) was significantly lower (P < 0.05) than by spermatozoa treated with PC12 or A23187 (16/30 and 17/30, respectively). Processing stallion spermatozoa either by a swim-up procedure or by centrifugation through a Percoll gradient increased the percentages of motile spermatozoa in the final sample, and spermatozoa collected by both processes penetrated similar numbers of zona-free hamster oocytes (P > 0.05). Although treating spermatozoa with PC12 or A23187 enabled both stallion and bull spermatozoa to penetrate oocytes, higher numbers of bovine oocytes were penetrated by bull spermatozoa (25/30) than by stallion spermatozoa (4/30) regardless of spermatozoal treatment. However, the number of zona-free hamster and equine oocytes penetrated by bull spermatozoa (25/30 and 12/18 respectively) and stallion spermatozoa (17/30 and 15/21 respectively) were similar (P > 0.05). We conclude that both PC12 and A23187 capacitate stallion and bull spermatozoa sufficiently to permit the acrosome reaction to occur, enabling spermatozoa to penetrate homologous and heterologous zona-free oocytes.

Ovarian superstimulatory response and embryo production in mares treated with equine pituitary extract twice daily

Equine pituitary extract (EPE), has been reported to induce multiple ovulation in mares, however ovulation rates are poor in comparison to those obtained in other species. Attempts to improve the effectiveness of EPE for induction of superovulation in cyclic mares has focused on daily frequency of EPE treatment. Two experiments were performed to compare the ovarian response of cyclic mares given EPE once or twice-daily. Mares were assigned to one of two treatment groups 6 to 8 days after ovulation: prostaglandin was given once and EPE (25 mg) was given once daily (Group 1) or twice daily (Group 2). In Experiment 1, more (P < 0.05) follicles > or = 35 mm were detected in mares treated with EPE twice daily (6.1 +/- 3.1) than in mares treated once a daily (2.0 +/- 0.6). In a second experiment, the embryo recovery rates of mares given the two EPE protocols used in Experiment 1 were compared. The number of ovulations per mare was higher (P < 0.05) for mares treated twice-daily (7.1 +/- 5.1, range 3 to 18) than for mares treated once daily (2.4 +/- 1.8, range 1 to 6). The number of embryos produced per mare was higher (P < 0.05) in mares in Group 2 (3.5) than in Group 1 (1.6). Although it is not clear whether the increased ovulation rate is due specifically to dose or frequency, twice-daily administration of a high dose of EPE significantly improved follicular development, ovulation and embryo recovery over the standard treatment of once-daily injection.

Use of oocyte transfer in a commercial breeding program for mares with reproductive abnormalities

In some mares with lesions of the reproductive tract, embryo collection and survival rates are low, or collection of embryos is not feasible. For these mares, oocyte transfer has been proposed as a method to induce pregnancies. In this report, a method for oocyte transfer in mares and results of oocyte transfer performed over 2 breeding seasons, using mares with long histories of subfertility and various reproductive lesions, are described. Human chorionic gonadotropin or an implant containing a gonadotropin-releasing hormone analog was used to initiate follicular and oocyte maturation. Oocytes were collected by means of transvaginal ultrasound-guided follicular aspiration. Following follicular aspiration, cumulus oocyte complexes were evaluated for cumulus expansion and signs of atresia; immature oocytes were cultured in vitro to allow maturation. The recipient's ovary and uterine tube (oviduct) were exposed through a flank laparotomy with the horse standing, and the oocyte was slowly deposited within the oviduct. Oocyte transfer was attempted in 38 mares between 9 and 30 years old during 2 successive breeding seasons. All mares had a history of reproductive failure while in breeding and embryo transfer programs. Twenty pregnancies were induced. Fourteen of the pregnant mares delivered live foals. Results suggest that oocyte transfer can be a successful method for inducing pregnancy in subfertile mares in a commercial setting.

Acrosomal ultrastructure of stallion spermatozoa cryopreserved with ethylene glycol using two packaging systems

The present experiments aimed to examine the substitution of glycerol (G) by ethylene glycol (E) as a cryoprotective agent for stallion spermatozoa. Two different ethylene glycol concentrations (5% and 10%) and also the association of glycerol (2%) and ethylene glycol (3%) (E/G) were studied (Experiment 1). In Experiment 2, two packing systems (0.5 x 4.0 ml) were evaluated using both cryoprotectors. In both experiments, the sperm membrane integrity after freezing was evaluated using transmission electron microscopy. The mean post-thaw motility was 34.25, 36.5, 29.25 and 34.75% for G5%, E5%, E10% and E/G, respectively. It was observed that the percentage of motile spermatozoa was significantly smaller (P<0.05) when semen was processed with E10%. A decrease in the acrosome integrity was observed in frozen thawed spermatozoa from all treated groups. It was observed that 28.0, 22.5, 25.5 and 22.5% of the sperm cells had a normal acrosome following freezing with G5%, E5%, E10% and E/G, respectively. Undulation of the outer acrosomal membrane, acrosomal swelling and loss of acrosomal content density and homogeneity were the most evident ultrastructural alterations observed. In Experiment 2, the post-thaw motility was higher (P<0.05) for sperm frozen in 0.5 ml straws than in 4.0 ml straws, regardless of the cryoprotector used. The ultrastructural evaluation showed 26.7 and 16.0% of intact acrosomes for sperm frozen in 0.5 ml and 4.0 ml straws, respectively. We concluded that ethylene glycol has similar cryoprotective properties to glycerol and that utilisation of 0.5 ml straws improved the ability of horse sperm cells to withstand damage after the cryopreservation process.

Factors affecting pregnancy rates and early embryonic death after equine embryo transfer

In the present study, 638 embryo transfers conducted over 3 yr were retrospectively examined to determine which factors (recipient, embryo and transfer) significantly influenced pregnancy and embryo loss rates and to determine how rates could be improved. On Day 7 or 8 after ovulation, embryos (fresh or cooled/transported) were transferred by surgical or nonsurgical techniques into recipients ovulating from 5 to 9 d before transfer. At 12 and 50 d of gestation (Day 0 = day of ovulation), pregnancy rates were 65.7% (419 of 638) and 55.5% (354 of 638). Pregnancy rates on Day 50 were significantly higher for recipients that had excellent to good uterine tone or were graded as "acceptable" during a pretransfer examination, usually performed 5 d after ovulation, versus recipients that had fair to poor uterine tone or were graded "marginally acceptable." Embryonic factors that significantly affected pregnancy rates were morphology grade, diameter and stage of development. The incidence of early embryonic death was 15.5% (65 of 419) from Days 12 to 50. Embryo loss rates were significantly higher in recipients used 7 or 9 d vs 5 or 6 d after ovulation. Embryos with minor morphological changes (Grade 2) resulted in more (P<0.05) embryo death than embryos with no morphological abnormalities (Grade 1). Between Days 12 and 50, the highest incidence of embryo death occurred during the interval from Days 17 to 25 of gestation. Embryonic vesicles that were imaged with ultrasound during the first pregnancy exam (5 d after transfer) resulted in significantly fewer embryonic deaths than vesicles not imaged until subsequent exams. In the present study, embryo morphology was predictive of the potential for an embryo to result in a viable pregnancy. Delayed development of the embryo upon collection from the donor or delayed development of the embryonic vesicle within the recipient's uterus was associated with a higher incidence of pregnancy failure. Recipient selection (age, day after ovulation, quality on Day 5) significantly affected pregnancy and embryo loss rates.

Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol

Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were removed by successive dilutions in PBS + 15% v:v fetal calf serum (FCS) containing decreasing concentrations of the cryoprotectants. Pregnancy was diagnosed ultrasonographically in 53.3%, 13.3% and 0% of the mares in Groups 1, 2 and 3 respectively. Ultrastructural analysis showed differences between frozen/thawed and fresh embryos. In the former, embryonic cells were deformed and showed dilation of the intercellular and perivitelline spaces, a decrease of desmosome number in the junctional complexes, few microvilli on the apical surface of the trophectoderm and an almost total absence of pinocytotic vesicles. Most of the mitochondria showed regions containing dilation and irregularities on the cristae, which appeared electron-dense. The results obtained with Groups 2 and 3 embryos showed that the cryoprotectants employed were not effective in protecting the embryos against damage during freezing and thawing. Indeed, the ultrastructural changes observed in the Group 3 embryos explained the absence of any established pregnancies in this group of mares.