The ability of donkey sperm to induce oocyte activation and mule embryo development after ICSI

Members of the Equus genus exhibit a fascinating capacity for hybridization, giving rise to healthy offspring. Mules, resulting from the mating of a mare with a jack, represent the most prevalent equid hybrid, serving diverse roles in our society. While in vitro embryo production, particularly through Intracytoplasmic Sperm Injection (ICSI), has rapidly gained significance in domestic horses, the in vitro production in other equids remains largely unexplored. Utilizing donkey sperm for fertilizing horse oocytes not only addresses this gap but also provides an opportunity to investigate donkey sperm's fertilization capability in vitro to further improve donkey ICSI. In this work, we initially studied the localization of donkey sperm Phospholipase C zeta (PLCζ) and assessed the sperm's capacity to induce pronuclear formation and maternal SMARCA4 recruitment upon injection into pig oocytes through ICSI. Subsequently, we investigated the injection of donkey sperm into horse oocytes, evaluating in vitro production up to the blastocyst stage using sperm from different jacks, including frozen and refrigerated samples. Distinct patterns of PLCζ localization were observed for donkey sperm cells compared to their horse counterparts. Additionally, donkey sperm exhibits a reduced ability to induce porcine oocyte activation. However, when injected into horse oocytes, donkey sperm demonstrated sufficient capability to induce oocyte activation as no discernible differences in cleavage or blastocyst rates are observed between in vitro produced mules and horse ICSI embryos. Our study not only delineates PLCζ localization in donkey sperm but also suggests potential differences in the ability to induce oocyte activation in pigs compared to horses while observing no distinctions in pronuclear recruitment of SMARCA4. Interestingly, donkey sperm remains sufficiently capable of inducing horse oocyte activation for in vitro mule blastocyst production.

Glass wool column filtration for stallion sperm selection: A comparative analysis with the single-layer colloid centrifugation

Glass wool column filtration (GWCF) selects human, bull, boar, dog and buffalo spermatozoa, but reports in the horse are scarce. Single-layer colloid centrifugation with Androcoll-E™ is currently the standard procedure to select good-quality equine sperm. This study was designed to assess GWCF (50 and 75 mg columns; GWCF-50 and GWCF-75, respectively) efficacy to select good-quality sperm from fresh and frozen-thawed equine semen, and to compare its performance with Androcoll-E™ colloid centrifugation. Percentage total motile (TM), progressively motile (PM), morphologically normal (MN), osmotically competent (HOS+) and acrosome-intact/osmotically competent (AI/HOS+) sperm were determined. In studies done with fresh semen samples (n = 17), suspensions subjected to GWCF-50 showed an improvement (p < .05) in PM and HOS+ sperm after selection. With GWCF-75, an increase (p < .05) in PM, MN and HOS+ sperm was observed. Results with GWCF were comparable or better than with Androcoll-E™ selection. Sperm recovery was similar between procedures for all semen parameters. Total sperm count recovery was lower after GWCF-75 (GWCF-50 = 60.0; GWCF-75 = 51.0; Androcoll-E™ = 76.0 million sperm; median; p = .013), but results on total progressive sperm count were similar (GWCF-50 = 23.0; GWCF-75 = 27.0; Androcoll-E™ = 24.0 million sperm; median; p = .3850). Using frozen-thawed semen samples (n = 16), an improvement (p < .05) in TM, PM, NM, HOS+ and AI/HOS+ sperm was observed in GWCF-75 filtrates. Results were comparable to Androcoll-E™ centrifugation, except HOS+ that increased (p < .05) only after GWCF-75. Recovery was comparable for all parameters in frozen samples. GWCF is a simple and low-cost procedure that selects equine sperm with a quality comparable to colloid centrifugation with Androcoll-E™.

Circulation of coronavirus in bats from northern and central Argentina: preliminary study

Purpose

Bats have proven throughout history to be the reservoir and disseminator of a wide variety of viruses in nature, where they have sometimes been linked to important infections in public health, such is the case of coronaviruses causing SARS-CoV, MERS-CoV and SARS-CoV-2. Considering the importance of these previous events and due to the lack of information on the coronavirus present in the bat population in Argentina, we decided to monitor their circulation in two provinces in which there is continuous contact of these animals with others (domestic and wild) and human beings.

Methods & Materials

Samples of pharyngeal swabs and fecal matter were collected from different species of bats from the provinces of Jujuy (northern Argentina) and La Pampa (central Argentina), and from other wild and domestic animals that cohabitated with bats. The samples were stored in RNA Shield® 1X until processing. The viral RNA extraction was performed with Quick-RNA Viral Kit (ZYMO RESEARCH®) and the cDNA with EasyScript First-Strand cDNA Synthesis SuperMix (TRANS®). Each sample was analyzed individually by nested PCR directed to a conserved 440 bp fragment located within the viral polymerase gene (Chu et al., 2006).

Results

Preliminary results from 43 stool samples and 53 pharyngeal swabs from insectivorous and hematophagous bats demonstrated the presence of alfacoronavirus sequences in four fecal samples (3 insectivorous bats and 1 hematophagous bat) and in one pharyngeal swab sample from an insectivorous bat. Through comparison with GenBank sequences, the closest relatives identified were alphacoronaviruses of the species Myotis riparius/ nigricans, Molossus rufus and Desmodus rotundus. Interestingly, we found alphacoronavirus sequences of one species present in another bat species since the colonies were in close contact. Samples from other animal species are in the process of being analyzed.

Conclusion

The identification of new coronaviruses that naturally inhabit bat populations and in animal species that share the biological niche, contributes to the knowledge of viral evolution and the biology behind the jump between animal species.

Effect of hCG administration on Day 7 post-mating on accessory corpus luteum development and progesterone concentration in llamas

A high embryo loss rate has been reported in llamas. As strategies that lead to an increase in plasma progesterone (P4) concentration might improve fertility, the aim of the present study was to evaluate if the administration of hCG on Day 7 post-mating is useful to develop an accessory corpus luteum (CL), increasing plasma P4 concentration. Twenty (n = 20) female llamas, ranging between 5 and 10 years of age and four (n = 4) males of proven fertility, ranging between 8 and 10 years of age were included in the study. Accessory CL developed in all treated llamas after hCG administration and plasma P4 concentration was significantly greater in treated than in control females (P˂0.0001). The diameter and vascularization of the original CL were not affected by treatment in pregnant llamas. However, in treated non-pregnant llamas, corpus luteum diameter was greater than in the control group from Day 14 post-mating until the end of the study (P˂0.001). In treated llamas, the accessory CL was detected throughout the study in pregnant and non-pregnant females, but its vascularization started to decrease around Day 16 post-mating in non-pregnant animals (P˂0.05). In conclusion, hCG treatment on Day 7 post mating was useful to induce an accessory CL and increase plasma P4 concentration in llamas. Thus, this treatment could be considered as a useful strategy to improve pregnancy rates in llama herds.

Detection of lipid peroxidation in dog spermatozoa with the fluorescent dye C11-BODIPY581/591

C11-BODIPY^581/591 is a fluorescent probe that has been successfully used to evaluate lipid peroxidation in different species, but it has not been completely studied in the dog. Thus, the aim of the present study was to assess lipid peroxidation of dog spermatozoa using C11-BODIPY^581/591 and compare different positive controls of the technique. Twenty-four ejaculates were collected from 8 adult male dogs. Routine seminal characteristics were evaluated in raw semen. Lipid peroxidation evaluation was performed as described in other species. Samples were divided in three aliquots, exposed to UV radiation, incubated with hydrogen peroxide or left without treatment (control). Lipid peroxidation was significantly greater only in UV-exposed samples than in the control ones (91 ± 6% vs. 8.3 ± 3.5%, p ˂ .01). In conclusion, C11-BODIPY^581/591 is useful to evaluate lipid peroxidation of dog spermatozoa and UV radiation is a good promoter of membrane oxidation, so irradiated samples can be used as a positive control of this technique.

Plasma IGF1 and 17β-Estradiol Concentrations During the Follicular Wave in Llamas

The aim of this study was to characterize the temporal association between follicular waves and circulating concentrations of 17β-estradiol (E2) and IGF1 in llamas. Follicular waves could be clearly divided in three phases: growth, plateau and regression; with a mean duration of 18.8 ± 0.32 days. All follicular waves showed overlapping, so that as one dominant follicle was regressing, another one was growing. E2 plasma concentration showed a wavelike pattern, similar to that followed by the dominant follicle; reaching its maximum concentration at the end of the growth phase and decreasing at the end of the plateau phase. IGF1 also showed variations during the follicular wave. It tended to increase during the growth phase and decreased toward Days 14 and 16. IGF1 reached its maximum concentration before E2 did (5 ± 0.8 vs. 7.2 ± 0.5 days after wave emergence) and before the maximum follicular diameter was attained (10.2 ± 0.46 days after wave emergence). Both hormones started to rise again in coincidence with the development of a new follicular wave. The observed profiles allow to suggest that IGF1 could have a role on folliculogenesis and ovarian steroideogenesis in llamas, as reported for other species.

Cyclic AMP efflux through MRP4 regulates actin dynamics signalling pathway and sperm motility in bovines

Previously we demonstrated that multidrug resistance-associated protein 4 transporter (MRP4) mediates cAMP efflux in bovine spermatozoa and that extracellular cAMP (ecAMP) triggers events associated to capacitation. Here, we deepen the study of the role of MRP4 in bovine sperm function by using MK571, an MRP4 inhibitor. The incubation of spermatozoa with MK571 during 45 min inhibited capacitation-associated events. MRP4 was localized in post-acrosomal region and mid-piece at 15 min capacitation, while at 45 min it was mainly located in the acrosome. After 15 min, MK571 decreased total sperm motility (TM), progressive motility (PM) and several kinematic parameters. The addition of ecAMP rescued MK571 effect and ecAMP alone increased the percentage of motile sperm and kinematics parameters. Since actin cytoskeleton plays essential roles in the regulation of sperm motility, we investigated if MRP4 activity might affect actin polymerization. After 15 min capacitation, an increase in F-actin was observed, which was inhibited by MK571. This effect was reverted by the addition of ecAMP. Furthermore, ecAMP alone increased F-actin levels while no F-actin was detected with ecAMP in the presence of PKA inhibitors. Our results support the importance of cAMP efflux through MRP4 in sperm capacitation and suggest its involvement in the regulation of actin polymerization and motility.

Corpus luteum vascularization during the maternal recognition of pregnancy in llamas (Lama glama)

The aim of this study was to characterize corpus luteum vascularization and its association with plasma progesterone concentration in early stages of pregnancy, when maternal recognition of pregnancy is expected to occur. In all animals, both plasma progesterone concentration and corpus luteum vascularization increased from Day 6 to Day 8 post-mating and afterwards in non-pregnant llamas they started to decrease to reach basal levels around Days 12 to 14 post-mating, while in pregnant animals, both variables remained elevated until the end of the study. A lineal positive relationship between corpus luteum vascularization and plasma progesterone concentration was observed in pregnant (r²  = .46, p < .0001) and non-pregnant llamas (r²  = .66, p < .0001). Pregnant animals showed higher plasma progesterone concentration and corpus luteum vascularization than the non-pregnant ones from Day 12 post-mating until the end of the study (p ˂ .05 and p ˂ .01, respectively). These results suggest that maternal recognition of pregnancy should occur before Day 12 post-mating in order to expand luteal lifespan, maintaining corpus luteum vascularization and progesterone production. Also, the assessment of CL vascularization area could be a useful and non-invasive method for early pregnancy diagnosis due to its association with plasma progesterone concentration.

Synchronization of time of development of ovarian follicular waves in South American Camelids

South American camelids (SAC) are induced ovulating animals. In unmated females, ovarian follicle development occurs in waves of growth and regression, while mating when there is the presence of a mature follicle leads to ovulation. The capacity to respond to an ovulatory stimulus depends on the stage of the follicular wave development. Treatments to control ovarian follicular development have been performed to synchronize timing of wave emergence and development of the dominant follicle at a predictable time. Thus, synchronization of the time of follicular wave development allows for performing fixed time mating or artificial insemination, and superestimulatory treatments for multiple follicule development. Protocols are based on removal of the suppressive effect of the dominant follicle, that can be achieved by physical ablation or by inducing ovulation (with LH or GnRH) or atresia (with progesterone or progestagens alone or combined with estradiol) of this follicle. Differences between treatments should be taken into consideration when choosing a protocol for fixed time mating or artificial insemination, especially when applying the use these technologies for SAC production by commercial enterprises. Furthermore, the objective of applying synchronization protocols should be considered, because not all of these are effective in inhibiting follicular growth before initiation of a superestimulatory treatment for multiple follicle development.

267 EFFECT OF SEMINAL PLASMA IN LAMA GLAMA SPERM

In South American camelids, raw semen only presents sperm with oscillatory movements. Therefore, it is necessary to treat these cells to enable them to acquire progressive motility. The effects of raw seminal plasma (SP) on sperm movement patterns (oscillatory, progressive, and hyperactive) have apparently not yet been reported. The objective of this study was to determine effects of raw seminal plasma on sperm motility, viability, and acrosomal status in fresh llama semen. A total of 15 ejaculates were collected (electroejaculation) from 5 llamas (n = 5, r = 3). Each ejaculate was diluted 4 : 1 in 0.1% collagenase in HEPES-TALP (HT) medium and incubated 4 min at 37°C, with the objective of separating spermatozoa from SP. Immediately after incubation, each ejaculate was divided into 2 and centrifuged for 8 min at 800 × g. Pellets were resuspended in either HT or raw SP and maintained at 37°C until evaluation (at 0, 1.5, and 3 h). Sperm motility was evaluated using a phase contrast microscope and a warm stage. Propidium iodide and carboxyfluorescein diacetate were used for assessing membrane integrity (viability). Acrosomal status was evaluated with the Coomassie blue stain. A split-plot design was used with treatment as a factor, with 2 levels (HT and SP) and time as the other factor, with 3 levels (0, 1.5, and 3 h), and blocked by males. There was no significant interaction between treatments (HT and SP) and times (0, 1.5, and 3 h) for each of the seminal characteristics evaluated. Progressive sperm motility was observed after collagenase treatment in all samples. Progressive motility disappeared immediately after the addition of raw SP and showed only oscillatory movements. In contrast, samples incubated in HT maintained progressive motility and became hyperactive. There were no differences (P > 0.05) in total motility of sperm incubated in HT among incubation times (0 h: 30.8 ± 18.9%; 1.5 h: 26.5 ± 11.5%; and 3 h: 21.5 ± 13.5%). However, in samples incubated with SP, a decrease (P < 0.05) in total sperm motility was detected after 3 h of incubation (0 h: 16.5 ± 12.6%, 3 h: 2.3 ± 3.2%). Sperm viability was not different (P > 0.05) between treatments (HT and SP); samples incubated in HT retained 78.4% of the initial viability (32.8/41.8, 3 h/0 h), and samples incubated in SP retained 69.7% of their initial viability (24.4/35.0, 3 h/0 h). The percentage of spermatozoa with intact acrosomes was not different (P > 0.05) between treatments (HT and SP); however, the percentage of sperm with intact acrosomes decreased after 3 h of incubation in both samples (HT and SP). Due to the presence of a high percentage of progressive and hyperactive motile sperm in samples incubated in HT and their absence in samples incubated in SP, we concluded that raw seminal plasma preserved oscillatory sperm motility. Further studies are needed to understand the effects of SP on South American camelid spermatozoa.

In vitro equine embryo production using air-dried spermatozoa, with different activation protocols and culture systems

The aim of this work was to evaluate the use of air-dried spermatozoa for in vitro production of equine embryos and verify if sperm extract activation and in vivo culture improve in vitro embryo production. Cooled spermatozoa (control) and air-dried spermatozoa stored for 2, 14 or 28 days were used for ICSI sperm extract, or ionomycin was used for oocyte activation, and embryos were in vitro or in vivo (in mare's oviduct) cultured for 7 days. With in vitro culture, cleavage rate was higher when activating with sperm extract (P < 0.05). No differences in embryo development were seen between the two activation treatments nor between storage periods (P > 0.05). Blastocysts were obtained with cooled spermatozoa, and morulae were achieved using in vivo culture with 28-day storage spermatozoa and ionomycin-activated oocytes. When in vivo culture was performed, sperm DNA fragmentation was assessed using the sperm chromatin dispersion test and did not show statistical correlation with cleavage nor embryo recovery rates. In conclusion, equine embryos can be produced using air-dried spermatozoa stored for several weeks. Sperm extract activation increased cleavage rates but did not improve embryo development. In vivo culture allowed intrauterine stage embryos to be achieved.

50 FIRST EQUINE CLONE BORN IN ARGENTINA BY SOMATIC CELL NUCLEAR TRANSFER FROM A POLO ARGENTINO MARE

Births of the first cloned equids were reported in 2003 (Woods et al. 2003 Science 301(5636), 1063; Galli et al. 2003 Nature 424 (6949), 635) but no equine clones have been reported in Latin America. The aim of this work was to inform the birth of the first equine clone in Argentina as a result of interdisciplinary teamwork. Equine oocytes were obtained from slaughterhouse ovaries and were transported at 38°C for 15 h in TCM-199 buffered with 20 mM HEPES and supplemented with 1 mM glutamine, 0.19 mM sodium pyruvate, 2 μg mL–1 LH, 5 μg mL–1 FSH, 100 ng mL–1 EGF, 100 ng mL–1 IGF-I, and 10% FCS. After 16 to 18 h of maturation, oocytes were denuded and enucleated. Frozen–thawed somatic cells from 1 of 2 aged (23 and 20 years old) Polo Argentino breed donor mares were inserted into the perivitelline space of each enucleated oocyte and fusion was induced. Activation was performed by exposure to Ionomycin (5 μM) for 4 min, followed by 4 h culture in a combination of 6-DMAP and cycloheximide in SOFaas culture media (Choi et al. 2001 Reproduction 122, 177–183). Embryos were cultured in 50 μL SOFm droplets for 7 to 8 days and then were transferred non-surgically to anovulatory recipient mares treated with 1.5 mg oestrogen, followed by long acting progesterone (BioRelease P4 300 LA, BET Pharm, KY). The production rates of the first cell line were: fusion 301/553 (54.4%), cleavage 163/218 (53.4%), blastocysts produced 20/163 (12.2%), blastocysts transferred 18/20 (90%), pregnancies 1/18 (5.5%) and no foal born. The production rates of the second cell line were: fusion 252/553 (45.6%), cleavage 55/252 (21.8%), blastocysts produced 8/55 (14.5%), blastocysts transferred 7/8 (87.5%), pregnancies 4/7 (57%) and 1 filly was born. DNA microsatellite analysis confirmed that the filly was a clone from the original donor cell line. The filly, born naturally on Day 329 of gestation, suffered premature placental separation and weighed 12 kg. Despite the intensive care provided, the filly’s respiratory, nervous, and cardiovascular functions deteriorated rapidly and she died 14 h postpartum. Fetal membranes weighed 5.7 kg (47.5% of the filly’s weight) and showed marked oedema of the chorioalantois and umbilical cord (which also showed a torsion of 9 twists). Histopathologically, the chorioalantois showed scant and poorly developed villi and also connective tissue oedema. Death could have been due to marked immaturity, as a consequence of placental insufficiency and umbilical cord torsion.

77 PREGNANCY RATES AFTER VITRIFICATION OF FRESH AND COOLED EQUINE EMBRYOS USING THE CRYOTOP METHOD

Cryopreservation of equine embryos is still not a routine procedure. Pregnancies have been obtained after transfer of vitrified embryos of less than 300 μm (Eldridge-Panuska et al. 2005). The aim of this study was to use the cryotop method (Kuwayama, 2007) to obtain pregnancies after transfer of vitrified thawed cooled and fresh embryos collected in our clinical embryo transfer programme. Embryos were assigned either to be vitrified within 3 h of collection or to be cooled for 18–24 h before vitrification. All embryos were vitrified and thawed by Cryotop Vitrification Kit® (Cryo Tech Laboratory®). Briefly, they were equilibrated in a solution containing ethylene glycol (EG), dimethylsulphoxide (DMSO) in TCM-199 for 10 to 25 min. Then they were moved to vitrification solution containing EG, DMSO, and sucrose in TCM-199 and loaded with a glass capillary onto the top of the film strip. After loading, almost all the solution was removed to leave only a thin layer covering the embryo, and the sample was quickly immersed into liquid nitrogen and covered with a protective cap. The time between entry to vitrification solution and nitrogen was from 1 to 3 min. At warming, the strip was immersed directly for 1 min into a 37°C medium containing sucrose in TCM-199. The embryo was incubated 3 min in a diluent solution, washed twice 5 min each in washing solution, and further cultured in DMEM F-12 with 10% FBS at 38.5°C 5% CO2 between 2 to 5 h. For transfer, the embryo was loaded in 0.5-mL straws. All recipient mares had ovulated 4 to 7 days before nonsurgical transfer. Pregnancies were detected 6 to 8 days later. A total of 15 embryos, grades 1 to 2, were obtained. Fresh embryos (n = 7) ranged between 250 and 800 μm, and refrigerated embryo (n = 8) diameter was between 130 and 550 μm. Pregnancy rates were 37.5% (3/8) for embryos cooled before vitrification and 28.6% (2/7) for embryos vitrified within 3 h. The overall pregnancy rate was 33.3% (5/15). Shipping cooled embryos allows maintaining a large number of recipients far away from donors, without decreasing pregnancy rate. It also makes it possible to send embryos to a specialised laboratory in order to be vitrified and preserved until recipients are available. Equine embryos collected 6 days after ovulation are generally smaller than 300 μm and have shown the highest survival rate after cryopreservation. However, the embryo recovery rate is higher when flushing is performed at Day 7 or 8. This cryopreservation protocol could provide a way to vitrify fresh and cooled embryos up to 550 μm, which would prevent the loss of valuable embryos collected in more advanced stages of development. In summary, pregnancies can be obtained after cooling for 18 to 24 h and vitrification of embryos collected 7 or 7.5 days after.

308 GUANACO SPERM CHROMATIN EVALUATION USING TOLUIDINE BLUE

Guanacos, a wild species of South American camelids, have a high-quality fiber with great economic potential. To evaluate reproductive aptitude in guanacos, our laboratory has developed a reliable semen collection technique using electroejaculation and has applied various methods for evaluating semen characteristics. Studies for evaluating the state of sperm chromatin have also been initiated. Toluidine blue (TB) is a cationic stain that unites with the phosphate groups in the DNA, thus permitting differentiation between sperm heads according to the degree of chromatin decondensation. The objectives of this study were to determine the TB staining patterns of guanaco sperm chromatin, establish a positive control for the stain, and evaluate the effect of collagenase on sperm chromatin condensation. Semen was collected from 4 guanacos, between 6 and 9 years old, using electroejaculation. In Experiment 1, to establish a positive control for the stain, equal quantities of 1% dithiothreitol (DTT) and raw semen were incubated at room temperature for 30 s, 1.5 min, and 3 min. After incubation, smears were made and then dried, to avoid continuing the reaction, and finally were stained with 0.02% TB. A split-plot design was used with time as the splitting factor and considering the males as a block. In Experiment 2, raw semen was divided into 2 aliquots, one diluted 4 : 1 in 0.1% collagenase in HEPES-TALP-BSA medium and the other left without enzyme. Both aliquots were incubated 4 min at 37°C and, after centrifugation to remove the enzyme, smears were made and stained with TB. Spermatozoa were classified according to the degree of chromatin decondensation. Analysis of variance was performed using the males as a blocking factor and the treatment as a fixed factor. According to the degree of chromatin decondensation, three patterns of staining with TB were observed: light blue (negative, without alteration of chromatin condensation), light violet (intermediate, some degree of decondensation), and dark violet (positive, high degree of decondensation). A significant increase (P < 0.05) of sperm with highly decondensed chromatin was observed in semen incubated for 3 min with DTT when compared to 30 s of incubation. Therefore, 3 min of incubation with DTT was chosen as the positive control for Experiment 2. No significant differences in any of the 3 patterns of TB staining were observed between semen incubated with or without 0.1% collagenase. In conclusion, it is possible to use TB to evaluate the degree of chromatin decondensation in guanaco spermatozoa and to use DTT as a positive control for the stain. Treatment of guanaco semen with 0.1% collagenase did not affect sperm chromatin condensation; therefore, this enzyme can be used to decrease semen viscosity and aid handling in the laboratory.

Collection method, season and individual variation on seminal characteristics in the llama (Lama glama)

The objective of the present study was to evaluate the effect of semen collection method (electroejaculation "EE" as compared with the artificial vagina "AV"), the season (summer versus winter) and the male used on macroscopic and microscopic characteristics of ejaculates in llamas. A total of 110 ejaculates were collected from six males and 92 of them were analyzed. Ejaculate volume, concentration, total sperm and the following sperm characteristics were studied: motility, membrane function (HOS test), membrane integrity (CFDA/PI fluorochromes) and morphology. A mixed linear model, that considered season and collection method as the fixed variables and the male as the random variable, was used for the statistical analysis. Variability was found between males (p<or=0.05) when comparing the seminal characteristics. When considering the number of collections performed and the number of ejaculates discarded with each method, significant differences (p<0.01) were found between collection methods (EE and AV), with EE having a greater proportion of successful semen collections. There were significant differences (p<or=0.05) between collection methods for volume, sperm motility and membrane function. Ejaculates obtained by EE have a greater volume, sperm motility, live spermatozoa and sperm with functional membranes. Comparison of semen variables between the two seasons indicated that sperm concentration and sperm abnormalities were different (p<0.01). Ejaculates obtained during winter have greater sperm concentration and less sperm tail abnormalities than in summer. We conclude that semen variables have individual variation in llamas and are affected both by method of collection and season. The most desirable semen quality was obtained during winter using EE as the semen collection method.

371 INTRACYTOPLASMIC SPERM INJECTION OF EQUINE OOCYTES USING AIR-DRIED SPERM OR SPERM STORED IN A HIGH OSMOLARITY MEDIUM

The generally accepted method of long-term sperm preservation is freezing in liquid nitrogen. However, it is not always available. Other techniques have shown to preserve sperm for a short period of time that can be used for intracytoplasmic sperm injection (ICSI). Mouse offspring have been produced after ICSI with sperm stored in a high osmolarity medium. Also, human embryos were obtained by ICSI with air-dried sperm. Recently, equine blastocysts have been obtained by ICSI with lyophilized sperm. In our study, cleavage rate was evaluated after ICSI of equine oocytes using air-dried sperm or sperm stored in a high osmolarity medium. Oocytes were obtained from slaughterhouse ovaries by scraping individual follicles and transported in a portable incubator at 38�C for 15 h in TCM-199 buffered with HEPES and supplemented with glutamine, sodium pyruvate, LH (Bioniche Animal Health, Inc., Beltville, Ontario, Canada), FSH (Bioniche Animal Health, Inc.), epidermal growth factor (EGF), insulin-like growth factor 1 (IGF-1), and 10% FBS (GIBCO, Grand Island, NY, USA). On arrival, they were cultured for 6 more hours in 5% CO2 in air at 38�C in microdroplets of the same medium, without HEPES. Sperm was collected from 2 stallions of proven fertility. The ejaculate was diluted in Kenney extender, centrifuged, and the pellet was resuspended in HEPES-TALP (H-TALP). Three sperm treatments were used: (C) Control: ejaculated motile sperm processed as described above; (1) Air-dried sperm: obtained from spreading sperm on a sterile slide and drying it for 10 min in a laminar flow chamber; (2) Sperm in a high osmolarity medium: ejaculated motile sperm resuspended in H-TALP with high osmolarity (800 mOsmol). Samples from groups 1 and 2 were stored at 5�C for 2 to 3 days before being used for sperm injection. Only oocytes with an intact cytoplasm and a visible polar body were selected for injection and randomly assigned to each experimental group. Each MII oocyte was injected with 1 sperm cell and activated in Ionomicin for 10 min and DMAP for 3 h. Injected oocytes were cultured in DMEM : F10 1 : 1 with 10% FBS at 38�C in 7% O2 and 5% CO2 for 48 h. The number of cleaved embryos was recorded. Data was analyzed by chi-square test. A total of 135 MII oocytes were injected. The cleavage rate in group 1 was significantly lower than in the control group (31/71, 43.66% vs. 28/38, 73.68%) (P &lt; 0.05). No differences were observed between group (2) and control (19/29, 73.07% vs. 28/38, 73.68%) (P &gt; 0.05). This is the first report of equine oocytes fertilized by ICSI with air-dried sperm or with sperm kept in high osmolarity medium. These simple sperm preservation techniques might be an alternative option when liquid nitrogen is not available. Further studies will determine if it is possible to obtain pregnancies or even healthy offspring.