Undiluted or extended storage of ram epididymal spermatozoa as alternatives to refrigerating the whole epididymes

The Influence of Three Commercial Soy Lecithin-Based Semen Extenders and Two Spermatozoa Concentrations on the Quality of Pre-Freeze and Post-Thaw Ram Epididymal Spermatozoa

There are limited studies on the factors affecting the success of ram epididymal spermatozoa (REPS) cryopreservation. On this note, the current study assessed the influence of three commercial soy lecithin-based semen extenders, AndroMed® (AND), BioXcell® (BIO), and OviXcell® (OVI), and two concentrations (400 × 106 vs. 200 × 106 spermatozoa/mL) on the pre-freeze and post-thaw quality of REPS. The REPS were retrieved from nine adult rams' testes and diluted with each of the three extenders to both concentrations. Straws were frozen manually. Standard motility (SMP) and kinematic parameters (KPs) were assessed via a CASA, while spermatozoa viability, morphology, and acrosomal integrity were assessed via the Kovács-Foote staining technique. The concentration did not significantly affect the pre-freeze and post-thaw SMP and KPs of REPS. BIO and OVI had significantly higher pre-freeze and post-thaw BCFs, post-thaw VAP, and the percentage of all intact heads than AND. In contrast, AND had a significantly lower percentage of REPS with tail defects than BIO and OVI. The 400 × 106 spermatozoa/mL concentration resulted in a significantly higher percentage of all intact heads than the 200 × 106 spermatozoa/mL concentration. Freezing significantly increased tail defects and decreased the percentage of REPS with distal cytoplasmic droplets. The cryopreservation of REPS at the 400 × 106 spermatozoa/mL concentration is recommended. All three extenders must be optimized to preserve the viability, membrane integrity, and better normal morphology of REPS; the reason for increased tail abnormality after the freezing/thawing process needs to be studied.

Postmortem Collection of Gametes for the Conservation of Endangered Mammals: A Review of the Current State-of-the-Art

The collection of gametes from recently deceased domestic and wildlife mammals has been well documented in the literature. Through the utilization of gametes recovered postmortem, scientists have successfully produced embryos in 10 different wildlife species, while in 2 of those, offspring have also been born. Thus, the collection of gametes from recently deceased animals represents a valuable opportunity to increase genetic resource banks, obviating the requirement for invasive procedures. Despite the development of several protocols for gamete collection, the refinement of these techniques and the establishment of species-specific protocols are still required, taking into account both the limitations and the opportunities. In the case of wildlife, the optimization of such protocols is impeded by the scarcity of available animals, many of which have a high genetic value that must be protected rather than utilized for research purposes. Therefore, optimizing protocols for wildlife species by using domestic species as a model is crucial. In this review, we focused on the current advancements in the collection, preservation, and utilization of gametes, postmortem, in selected species belonging to Equidae, Bovidae, and Felidae, both domestic and wildlife.

Freezing Protocol Optimization for Iberian Red Deer (Cervus elaphus hispanicus) Epididymal Sperm under Field Conditions

Creating germplasm banks of wild species, such as the Iberian red Deer (Cervus elaphus hispanicus) can be challenging. One of the main difficulties is the obtention and cryopreservation of good-quality reproductive cells when the spermatozoa are obtained from epididymides after death. To avoid a loss of seminal quality during transport, developing alternative methods for cooling and freezing sperm samples under field conditions is necessary. The objective of this study was to evaluate the effects of different durations of equilibrium and different techniques of cooling and freezing on Iberian red deer epididymal sperm quality after thawing to optimize the processing conditions in this species. Three experiments were carried out: (I) evaluation of refrigeration in straws or tubes of 15 mL; (II) study of equilibration period (0, 30, 60, or 120 min); and (III) comparison of four freezing techniques (liquid nitrogen vapor in a tank (C), liquid nitrogen vapor in a polystyrene box (B), dry ice (DY), and placing straws on a solid metallic plate floating on the surface of liquid nitrogen (MP)). For all experiments, sperm motility and kinematic parameters, acrosomal integrity, sperm viability, mitochondrial membrane potential, and DNA integrity were evaluated after thawing. All statistical analyses were performed by GLM-ANOVA analysis. Samples refrigerated in straws showed higher values (p ≤ 0.05) for mitochondrial activity and lower values (p ≤ 0.05) for apoptotic cells. Moreover, the acrosome integrity showed significant differences (p ≤ 0.05) between 0 and 120 min, but not between 30 and 60 min, of equilibration. Finally, no significant differences were found between freezing in liquid nitrogen vapors in a tank or in a box, although there was a low quality after thawing when the samples were cryopreserved in dry ice or by placing straws on a solid metallic plate floating on the surface of liquid nitrogen. In conclusion, under field conditions, it would be possible to refrigerate the sperm samples by storing them in straws with a 120 min equilibration period and freezing them in liquid nitrogen vapors in a tank or box.

Microenvironment of the male and female reproductive tracts regulate sperm fertility: Impact of viscosity, pH, and osmolality

BACKGROUND

Terminally differentiated mammalian sperm are exposed to gradients of viscosity, pH, and osmolality both in the male and female reproductive tract during their perilous journey to quest the ovum. The complex physicochemical factors play an integral role in preparing sperm for the fertilization process.

OBJECTIVES

To elucidate the influence of the reproductive tract microenvironment especially viscosity, pH, and osmolality in regulating sperm functional and fertilization competence.

MATERIALS AND METHODS

The data used in this review were collected from the research papers and online databases focusing on the influence of viscosity, pH, and osmolality on sperm function.

DISCUSSION

The gradients of viscosity, pH, and osmolality exist across various segments of the male and female reproductive tract. The changes in the viscosity create a physical barrier, pH aid in capacitation and hyperactivation, and the osmotic stress selects a progressive sperm subpopulation for accomplishing fertilization. The sperm function tests are developed based on the concept that the male genotype is the major contributor to the reproductive outcome. However, recent studies demonstrate the significance of sperm genotype-environment interactions that are essentially contributing to reproductive success. Hence, it is imperative to assess the impact of physicochemical stresses and the adaptive ability of the terminally differentiated sperm, which in turn would improve the outcome of the assisted reproductive technologies and male fertility assessment.

CONCLUSION

Elucidating the influence of the reproductive tract microenvironment on sperm function provides newer insights into the procedures that need to be adopted for selecting fertile males for breeding, and ejaculates for the assisted reproductive technologies.

Effect of Bovine Serum Albumin Supplementation in Tris-Soybean Lecithin-Based Extender on Quality of Chilled Ram Epididymal Spermatozoa

Objective: This study was designed to assess the effects of using tris-soybean lecithin (TSL)-based extender supplemented with bovine serum albumin (BSA) on the quality of ram epididymal spermatozoa during refrigerated storage. Method: Epididymal sperm were collected from 22 Zandi rams, diluted in TSL-based extender at different concentrations (0%, 2.5%, 5%, 7.5%, and 10%) of BSA, and stored for 5 days at 4°C. Sperm parameters including motility, viability, plasma membrane integrity, chromatin protamination, and malondialdehyde (MDA) content were evaluated at 0, 24, 72, and 120 hours of refrigeration. Results: The addition of 10% BSA to the extender significantly improved sperm viability at 24 and 120 hours of refrigerated liquid storage (p < 0.05). An enhancement in plasma membrane integrity was observed along with a decrease in MDA level by increasing the concentration of BSA from 0% to 10% (p > 0.05). Sperm motion characteristics were higher in the BSA-free group at 120 hours of preservation (p < 0.05). No statistical difference was found for nuclear protamination between experimental groups (p > 0.05). Conclusion: BSA supplementation in TSL-based extender can preserve the viability of epididymal ram spermatozoa during liquid storage at 4°C.

Supplementation of cauda epididymal plasma improves sperm characteristics following liquid preservation of ram semen at 3-5°C

Mammalian spermatozoa remain immotile and metabolically inactive in the cauda epididymidis, thus maintaining fertility for several weeks. The aim of this study was to functionally characterise and evaluate the effect of cauda epididymal plasma (CEP) on liquid preservation of ram spermatozoa. Four experiments were conducted to investigate the effects of: (1) CEP and its fractions on sperm motility; (2) CEP (10%, 15%, 20% v/v) on liquid preservation of ram spermatozoa; (3) seminal plasma (SP; 20%, 30%, 50% v/v) on liquid-preserved spermatozoa; and (4) both CEP and post-storage SP treatment on sperm characteristics. Biochemical characterisation of ram CEP revealed high protein (30.9mgmL-1), catalase (68.9IUmL-1), alkaline phosphatase (17.5IUmL-1) activities and total antioxidant capacity (1112µM Trolox equivalent). Progressive motility of prewashed cauda spermatozoa was reduced (P<0.05) by CEP or its protein-rich fraction compared with protein-free plasma or phosphate-buffered saline. After 48h storage, total motility, rapid motility (average path velocity >75µms-1; 53.9%, 73.5% and 71.8% with 0, 15% and 20% CEP respectively) and straight line velocity (86.3, 102.1 and 102.4µms-1 with 0, 15% and 20% CEP respectively) were significantly (P<0.05) higher in the CEP-treated groups than the control. Viability and acrosomal integrity were similar between groups; however, functional membrane integrity was higher (P<0.05) in the 15% CEP-treated group. Treatment of liquid-preserved spermatozoa with either 20%, 30% or 50% SP improved (P<0.05) rapid motility and kinematics at each time point of storage compared with control. In conclusion, liquid preservation of ram spermatozoa in the presence of 15% or 20% CEP and post-storage treatment with SP significantly improve sperm characteristics.

Mimicking the cauda epididymal plasma-like osmolality in extender improves liquid preservation of ram semen at 3-5°C

Cauda epididymis in mammals is known to store mature sperm largely in quiescent state for several weeks without significantly affecting fertility. Hence, the aim of this study was to evaluate the effects of mimicking cauda epididymal plasma (CEP)-like conditions in extender on liquid preservation of ram semen at 3-5°C. Four experiments were conducted in this study: (1) evaluation of physicochemical properties of ram CEP, (2) effect of hyperosmotic solution on sperm motility and functional membrane integrity (FMI), and the effects of (3) CEP-like hyperosmolality (390 vs. 360 mOsmol/kg) and (4) pH in extender (pH 6.5 vs. 6.8) on liquid preservation of ram semen. Sperm treatment with hyperosmotic solution (450 mOsmol/kg) resulted in a decline (P < 0.05) in mass motility (3.5 ± 0.2 vs. 4.3 ± 0.2) and FMI (30.4 ± 3.2 vs. 52.1 ± 2.1%) compared to that with isoosmotic solution (360 mOsmol/kg). Overall, sperm viability, acrosomal integrity, and progressive motility were similar (P > 0.05) while straight-line velocity (77.8 ± 3.1 vs. 71.3 ± 2.7µm/s), linearity (47.4 ± 0.4 vs. 39.5 ± 0.9%), straightness (79.7 ± 0.5 vs. 74.0 ± 0.5%) and beat cross frequency (28.6 ± 0.8 vs. 26.0 ± 0.5 Hz) were higher (P < 0.05) and FMI (65.7 ± 1.5 vs. 75.4 ± 1.1%) was lower (P < 0.05) following liquid-preservation in hyperosmotic extender compared to that in isoosmotic extender. Both total motility (83.3 ± 1.8 vs. 75.4 ± 1.5%) and progressive motility (51.7 ± 2.3 vs. 39.5 ± 1.9%) were higher (P < 0.05) at 48 h of storage in hyperosmotic extender compared to the control. Overall, the seminal attributes were similar (P > 0.05) between the two pH's of the extender. In conclusion, semen extender having CEP-like osmolality but not the pH was superior to extenders having conventional osmolality and pH for liquid preservation of ram semen.Abbreviations: AI: artificial insemination; ALH: amplitude of lateral head displacement; BCF: beat cross frequency; CASA: computer-assisted semen analyzer; CEP: cauda epididymal plasma; ELON: elongation; EYTF: egg yolk-Tris-citrate-fructose; FMI: functional membrane integrity; GLM: general linear model; GPC: glycerophosphatidylcholine; HOS: hypoosmotic swelling; LIN: linearity; pHe: external pH; PROG: progressive motility; S.E.M.: standard error of the mean; SLTF: soya lecithin-Tris-fructose extender; SP: seminal plasma; STR: straightness; VAP: average path velocity; VCL: curvilinear velocity; VSL: straight-line velocity; TM: total motility.

Effect of length of time post-mortem on quality and freezing capacity of Cantabric chamois (Rupicapra pyrenaica parva) epididymal spermatozoa

Genome Resource Banks are keystones in the ex-situ conservation of wild species. Post-mortem (PM) collection of epididymal spermatozoa is an opportunistic and valuable source of germplasm, the time from the death of the animal limits its use. Seeking to improve germplasm preservation strategies for the chamois (Rupicapra sp.), the effect of PM time on epididymal sperm quality and freezability was studied using the Cantabrian chamois. Samples were classified according to PM collection time, up to 216 h (refrigerated), and cryopreserved (Tris-citric acid-fructose, 430 mOsm/kg, 15% egg yolk, 8% glycerol; freezing at -20 °C/min). Sperm quality was assessed after recovery and post-thawing (motility by CASA, HOS test, abnormal forms, cytoplasmic droplets, and viability and acrosomal damage by flow cytometry). The sperm mass pH and osmolality showed a positive correlation with time. Total sperm motility dropped after 2 days PM, with progressivity and sperm velocities remained similar up to 3 days PM. Sperm freezability was acceptable, with the post-thawing HOST, motility, progressivity, VAP, VCL, VSL and BCF negatively correlating with PM time. Overall, chamois epidydimal samples were not adequate for preservation after 6 days PM. Freezability capacity could make these spermatozoa suitable for specific ART even if kept refrigerated for several days PM.

Viability of ovine spermatozoa collected from epididymides stored at 18°-25°C for 48 hours post mortem

ABSTRACT The objectives of this study were to verify the time during which viable ovine spermatozoa could be recovered from the cauda epididymis kept at ambient temperature (18-25°C). Sperm collected in an artificial vagina (AV) were used as control. Spermatozoa samples were collected with an AV and from epididymis at 0 (G0), 6 (G6), 12 (G12), 24 (G24), and 48 (G48) hours post mortem. Total motility (TM), progressive motility (PM), hypo-osmotic membrane integrity test (HOST) and morphological changes were assessed. TM decreased (P<0.05) from 24 hours post mortem (70.0±1.9%) compared to AV (86.4±1.0%). PM decreased (P<0.05) from 12 hours after death (31.3±4.0%) compared to AV group (73.2±1.4%). The percentage of viable cells in HOST decreased (P<0.05) in the G48 (60.0±8.9%). Spermatozoa recovery was lower (P<0.05) 48 hours after death (2064.2±230.7 x 106 spermatozoa) compared to G0(2623.6±288.4 x 106 spermatozoa). In conclusion, under the conditions of this study, it would be possible to use epididymal spermatozoa recovered up to 24 hours after death for artificial insemination or in vitro fertilization; however, fertility trials are necessary to prove this hypothesis.

Beneficial and harmful effects of cyclodextrin-vitamin E complex on cryopreserved ram sperm

Vitamin E is a potent molecule, especially when loaded in cyclodextrin, in modulating oxidative stress during the freeze-thawing process. The present study aimed to investigate the effect of different concentrations of cyclodextrin-vitamin E complex (CD-Vit E) on cryopreserved ram sperm. Ejaculates collected from five adult rams were pooled and divided into four aliquots. All aliquots were treated in Tris-extender (Tris-glucose-citric acid) containing 2 mg cholesterol-loaded methyl-β- cyclodextrin/120 × 10⁶ spermatozoa and either 0 (Control), 2, 4 or 6 mg CD-Vit E/120 × 10⁶ spermatozoa, corresponding to 0, 0.5, 1 or 1.5 of pure vitamin E, respectively. After incubation at 22 °C for 15 min and the addition of Tris-extender containing glycerol and egg yolk (v/v), all aliquots were frozen in liquid nitrogen. After thawing, motility (computer aided sperm analysis), viability (eosin staining), membrane integrity (HOST), acrosome integrity (Coomassie G-250 staining) and lipid peroxidation (Thiobarbituric acid assay) were evaluated. Compared to control, 2 mg CD-Vit E had a significant positive effect on total motility, progressive motility, movement linearity (LIN%), viability and lipid peroxidation. At 4 mg, however, CD-Vit E had a significant negative effect on total motility, progressive motility, membrane functionality and acrosome integrity. At a greater concentration (6 mg), the negative effects were greater as compared with inclusion of 4 mg in the cryoprotectant and the percentage of rapidly and moderately motile gametes and viability were also altered. In conclusion, the effect of CD-Vit E on cryopreserved ram sperm was concentration-dependent with the 2 mg amount having a beneficial effect while greater concentrations (4 and 6 mg) had a harmful effect on sperm motility and gamete integrity but without affecting oxidative stress status.

Variations of motility and survival with storage time at 4°C of epididymal spermatozoa Ouled-Djellal breed rams in Eastern Algeria

Aim:

The aim of this study was to evaluate some reproduction performances in Ouled-Djellal rams.

Materials and Methods:

This study involved genital organs removed after slaughter from 54 rams at the municipal slaughterhouse of Batna (East Algeria).

Results:

The measurements of survival and mobility of epididymal sperm followed at 0, 24, 48 and 72 h after collection, revealed significant (p<0.05) to highly significant differences (p>0.001) according to time. Thus, concerning the sperm motility the values were 91.00±2.40%, 89.20±2.40%, 77.00±6.20% and 62.60±1.20% at 0, 24, 48 and 72 h, respectively. Indeed, in live sperm, the viability rates were 82.15±1.48%, 77.67±1.74%, 66.56±1.95% and 52.30±1.46% at 0, 24, 48 and 72 h, respectively.

Conclusion:

This study revealed that epididymal spermatozoa stored at 04°C for 72 h kept their mobility and vitality at nearly a half of their the original parameters.

Fertility of undiluted ram epididymal spermatozoa stored for several days at 4°C

In vitro preservation of the male gamete is a challenge in the development of artificial insemination techniques for domestic animals. Specific strategies and diluents have been developed for the preservation of the fertilizing ability of the semen for each species. However, the epididymal medium has been demonstrated to be the best sperm environment to maintain sperm viability over several days and weeks for mammals. The aims of this study were to evaluate the motility and in vivo fertility of ram epididymal spermatozoa when the semen was stored for up to 4 days at 4°C undiluted in epididymal plasma. The study was undertaken with two ovine breeds (Ile de France and Corriedale). The motility of epididymal spermatozoa was better preserved in the undiluted epididymal fluid than when epididymal spermatozoa were diluted in classic ovine extender such as skim milk. During storage, the decrease in the percentage of motile sperm was lower if the epididymal spermatozoa were collected immediately after epididymal sampling than 24 h after castration or animal death. The fertility obtained after cryopreservation of the stored sperm and subsequent intrauterine insemination ranged from 55% to 24% following 24 to 96-h sperm storage. There was a linear regression relationship between fertility and the number of motile sperm inseminated for both breeds. These results show that it is possible to keep epididymal sperm motile and fertile for several days without dilution. Such a method of sperm preservation could be a final possibility for animals of high genetic value or for endangered species when the collection of semen before death of the animal is not possible.

Alternative procedures for the cryopreservation of brown bear ejaculates depending on the flexibility of the "in cooling" period (5°C)

The adaptability of cryopreservation protocols for brown bear spermatozoa collected under field conditions and frozen in a nearby laboratory (transported for a few hours) or shipped to a reference laboratory for sex sorting (transported for a few days) was evaluated. Forty-nine electroejaculates from 15 mature brown bears were extended to 100×10(6) sperm/mL in a TES-Tris-Fructose based extender and cryopreserved (-20°C/min to -100°C and stored at -196°C). After thawing, the quality of the seminal samples was assessed for total (TM), progressive (PM) motility and kinetic parameters - by CASA -, and viability (VIAB), viable and non-apoptotic status (YOPRO-), high membrane mitochondrial potential (MIT) and intact acrosomes (iACR) - by flow cytometry -. In Experiment 1, we assessed different storage times (0, 0.5, 1 - control -, 4-5, 7-8 and 11-12 h) at 5°C from final dilution to freezing. After thawing, non-equilibrated samples (0 h) showed lower values of iACR, TM and PM. No significant differences were found for the different periods of equilibration tested. In Experiment 2, we evaluated three long-term storage times (24, 48 and 72 h) at 5°C before freezing using storage for 1h as control. The post-thawing quality of brown bear spermatozoa declined markedly after 48-72 h of pre-freezing. In conclusion, our findings suggest the possibility of extending the pre-freezing cooling period up to 24h post-collection without freezing. This knowledge should enable the adaptation of the freezing protocols for when a special handling conditions are required such as the shipment of seminal samples to technological centers for the pre-freezing application of enhancer spermatic biotechnologies.

Dynamics of sperm subpopulations based on motility and plasma membrane status in thawed ram spermatozoa incubated under conditions that support in vitro capacitation and fertilisation

The present study evaluated modifications occurring in thawed ram spermatozoa during incubation in different media that supported in vitro capacitation and fertilisation, and examines how these changes relate to IVF. Thawed sperm samples were incubated under capacitating (Cap) and non-capacitating (non-Cap) conditions for 0, 1 and 2 h and used in an IVF test. During incubation, changes related to membrane status and the motility pattern of spermatozoa were assessed, the latter being used to characterise sperm subpopulations. A significantly greater increase (P ≤ 0.05) in the percentage of spermatozoa with higher membrane fluidity was observed in samples incubated with Cap medium from the beginning of incubation. In addition, changes over time in the distribution of the motile subpopulation were particularly evident when spermatozoa were incubated with Cap medium, with a noted increase in spermatozoa classified as ‘hyperactivated like’, with major changes occurring after 1 h incubation. Both characteristics (i.e. membrane fluidity and the percentage of the hyperactivated-like subpopulation) were significantly related with in vitro fertility, and only sperm samples incubated with the Cap medium were capable of fertilising oocytes. These results support the idea that changes in sperm membrane fluidity and motility pattern (i.e. an increase in hyperactivated spermatozoa) are needed for fertilisation to take place.

Refrigeração do epidídimo canino a 4ºC e recuperação dos espermatozoides epididimários utilizando ACP-106c

Objetivou-se avaliar a qualidade dos espermatozoides recuperados da cauda do epidídimo após a refrigeração do complexo testículo-epidídimo (CTE) de cães usando o diluidor ACP-106c. Foram utilizados 60 cães machos adultos, com peso de 10-20 kg. Após a eutanásia, removeu-se o CTE que foi imerso em solução fisiológica 0,9% e transportado em caixa térmica ao laboratório a 30ºC. Para a refrigeração e recuperação dos espermatozoides epididimários, os 60 pares do CTE foram divididos em 4 grupos, de acordo com o tempo de refrigeração do CTE e posterior recuperação espermática: G0h, G6h, G12h e G18h, em que cada par do CTE permaneceu por zero, seis, doze ou dezoito horas a 4ºC, respectivamente. A recuperação dos espermatozoides da cauda do epidídimo foi realizada pela técnica de flutuação utilizando-se o diluidor ACP-106c ou Tris. Para cada epidídimo foi adicionado 1,0 mL de um dos dois diluidores, pré-aquecidos a 37ºC por 5 minutos. Em seguida foram centrifugados a 800g/5 minutos para remoção dos resíduos celulares. Avaliou-se a morfologia, funcionalidade e motilidade espermática total e progressiva, além de parâmetros obtidos pelo CASA. Os dados foram submetidos à ANOVA seguido do teste de Turkey (P < 0,05). Em todos os parâmetros avaliados, não houve diferença entre os diluidores testados (P>0,05). Os valores de motilidade total nos grupos G0h, G6h, G12h, e G18h para o ACP-106c foram 84,4±7,7; 81,6±11,6; 88,3±6,5 e 69,5±16,9, respectivamente, e para o Tris 85,2±8,7; 77,4±14,3; 79,0±17,8 e 65,4±17,9, respectivamente. Um decréscimo na qualidade espermática foi observado após 18 horas de refrigeração em ambos os diluidores. Dessa forma pode-se concluir que o ACP-106c pode ser utilizado para recuperar os espermatozoides epididimários refrigerados e podem ser viáveis por até 12h de refrigeração.

Seminal plasma applied post-thawing affects boar sperm physiology: a flow cytometry study

Cryopreservation induces extensive biophysical and biochemical changes in the sperm. In the present study, we used flow cytometry to assess the capacitation-like status of frozen-thawed boar spermatozoa and its relationship with intracellular calcium, assessment of membrane fluidity, modification of thiol groups in plasma membrane proteins, reactive oxygen species (ROS) levels, viability, acrosomal status, and mitochondrial activity. This experiment was performed to verify the effect of adding seminal plasma on post-thaw sperm functions. To determine these effects after cryopreservation, frozen-thawed semen from seven boars was examined after supplementation with different concentrations of pooled seminal plasma (0%, 10%, and 50%) at various times of incubation from 0 to 4 hours. Incubation caused a decrease in membrane integrity and an increase in acrosomal damage, with small changes in other parameters (P > 0.05). Although 10% seminal plasma showed few differences with 0% (ROS increase at 4 hours, P < 0.05), 50% seminal plasma caused important changes. Membrane fluidity increased considerably from the beginning of the experiment, and ROS and free thiols in the cell surface increased by 2 hours of incubation. By the end of the experiment, viability decreased and acrosomal damage increased in the 50% seminal plasma samples. The addition of 50% of seminal plasma seems to modify the physiology of thawed boar spermatozoa, possibly through membrane changes and ROS increase. Although some effects were detrimental, the stimulatory effect of 50% seminal plasma could favor the performance of post-thawed boar semen, as showed in the field (García JC, Domínguez JC, Peña FJ, Alegre B, Gonzalez R, Castro MJ, Habing GG, Kirkwood RN. Thawing boar semen in the presence of seminal plasma: effects on sperm quality and fertility. Anim Reprod Sci 2010;119:160-5).

Trehalose and glycerol have a dose-dependent synergistic effect on the post-thawing quality of ram semen cryopreserved in a soybean lecithin-based extender

The objective of this study was to examine the interaction of different concentrations of trehalose [0 (T0), 50 (T50) or 100 (T100) mM] and glycerol [5% (G5) or 7% (G7)] on post-thawed quality of ram semen, cryopreserved in a soybean lecithin (SL)-based extender. Twenty-eight ejaculates were collected from four rams and diluted with six trehalose/glycerol combinations: T0G5, T50G5, T100G5, T0G7, T50G7, and T100G7. Sperm motility (CASA), membrane integrity (eosin/nigrosin) and functionality (HOST), abnormal forms, capacitation status (CTC), mitochondrial activity (rhodamine 123), apoptotic features (Annexin V/propidium iodide) and lipoperoxidation (malondialdehyde production) were evaluated after thawing. Extender T100G5 yielded the highest results for total and progressive motility, sperm velocity, normal morphology, functional membranes, active mitochondria and membrane integrity, with P<0.05 in general, except for T50G7 (P>0.05). The combinations T0G5, T0G7 and T100G7 yielded the lowest post-thaw quality. We could not detect significant changes in other kinematic parameters, capacitation status or lipoperoxidation. We conclude that, in our SL-based extender, a combination of 100 mM trehalose and 5% glycerol was the most adequate combination to achieving post-thawing quality in our soybean lecithin-based extender, and our results support that a synergistic effect among trehalose and glycerol exists. We suggest that other combinations could improve these results.

Sperm concentration at freezing affects post-thaw quality and fertility of ram semen

We have investigated the effect of sperm concentration in the freezing doses 200, 400, 800, and 1600 × 10(6) mL(-1) on the post-thaw quality and fertility of ram semen. Semen was collected from seven adult Churra rams by artificial vagina during the breeding season. The semen was diluted in an extender (TES-Tris-fructose, 20% egg yolk, and 4% glycerol), to a final concentration of 200, 400, 800, or 1600 × 10(6) mL(-1) and frozen. Doses were analyzed post-thawing for motility (computer-assisted sperm analysis system [CASA]), viability, and acrosomal status (fluorescence probes propidium iodide [PI]/peanut agglutinin conjugated with fluorescein thiocyanate (PNA-FITC), SYBR-14/PI [Invitrogen; Barcelona, Spain] and YO-PRO-1/PI [Invitrogen; Barcelona, Spain]). Total motility and velocity were lower for 1600 × 10(6) mL(-1) doses, while progressive motility and viability were lower both for 800 and 1600 × 10(6) mL(-1). The proportion of viable spermatozoa showing increased membrane permeability (YO-PRO-1+) rose in 800 and 1200 × 10(6) mL(-1). Intrauterine inseminations were performed with the 200, 400, and 800 × 10(6) mL(-1) doses at a fixed sperm number (25 × 10(6) per uterine horn) in synchronized ewes. Fertility (lambing rate) was similar for semen frozen at 200 (57.5%) or 400 × 10(6) mL(-1) (54.4%), whereas it was significantly lower for 800 × 10(6) mL(-1) (45.5%). In conclusion, increasing sperm concentration in cryopreserved semen, at least at 800 × 10(6) mL(-1) and more, adversely affects the postthawing quality and fertility of ram semen.