Evaluation of bull spermatozoa during and after cryopreservation: Structural and ultrastructural insights

Effect of interleukin 6 (IL-6) on sperm quality, kinematic parameters, acrosome integrity, apoptosis, ultrastructure, and molecular docking in cryopreserved ram spermatozoa

Sperm cryopreservation can lead to subfertility due to potential damage to sperm DNA, membranes, and overall motility caused by the freeze-thaw process. Interleukin-6 (IL-6) is a versatile cytokine with various roles in reproductive processes. However, the impacts of IL-6 supplementation on cryopreserved ram sperm have not been thoroughly investigated. Therefore, this study aims to assess the influence of IL-6 on the sperm quality of cryopreserved ram sperm. Ram semen was collected, pooled, and extended with tris-citrate soybean lecithin extender supplemented with 0, 50, 100, and 200 ng/mL of IL-6. The samples experienced a standard freezing protocol, and sperm quality, kinematic parameters, ultrastructure, and molecular docking of cryopreserved ram spermatozoa were evaluated. The results showed that sperm kinematics, viability, progressive motility, and membrane integrity were significantly enhanced by the addition of 100 or 200 ng of IL-6/mL (p < 0.05). Semen supplemented with 100 or 200 ng/mL of IL-6 also exhibited higher percentages of sperm kinematics, including DAP, DCL, DSL, VSL, VAP, VCL, and ALH, compared to other groups (p < 0.05). IL-6 supplementation enhanced acrosome integrity, and reduced caspase-3 activity in post-thawed ram spermatozoa (p < 0.05) compared to untreated group. Supplementation with IL-6 (200 ng/mL) significantly decreased oxidative biomarkers (NO, MDA, and H2O2) (p < 0.001) and improved total antioxidant capacity (p < 0.05). The percentage of sperm damage (tail, head, and midpiece) was significantly reduced by IL-6 supplementation (p < 0.05). Electron micrographs showed that supplementation with 100 or 200 ng/mL IL-6 protected acrosome stability, plasma membrane integrity, and sustained the ultrastructure integrity of cryopreserved ram spermatozoa. The docking exploration indicates a higher binding affinity with sperm function biomarkers, including caspase 3, BCL2, and PSMA6, with binding energies of - 52.30 kcal/mol, - 56.04 kcal/mol, and - 57.06 kcal/mol, respectively. In conclusion, the addition of IL-6 to the freezing extender can enhance the post-thaw quality of cryopreserved ram spermatozoa.

Study on the correlation of supplementation with L-citrulline on the gastrointestinal flora and semen antifreeze performance of ram

Introduction

Cryopreservation of semen can give full play to the reproductive advantages of male animals. However, in actual production, due to the poor frost resistance of sheep semen and the low conception rate, the promotion of sheep frozen semen is greatly hindered. Therefore, it is urgent to improve the frost resistance of semen to improve the quality of frozen semen. At present, most studies on improving the quality of frozen semen are based on the improvement of semen dilutions, and few studies on improving the freezing resistance of ram semen by feeding functional amino acids.

Methods

Therefore, 24 Turpan black rams were divided into high antifreeze group (HF) and a low antifreeze group (LF) Each of these groups was further randomly divided into control and experimental subgroups. The control subgroup was fed a basal diet, while the experimental subgroup received an additional 12 g/d of L-Cit supplementation based on the control group for a duration of 90 days.

Results

The results showed that Following L-Cit supplementation, the experimental group demonstrated significantly elevated sperm density and VSL (Velocity of straight line), T-AOC, GSH-Px, and NO levels in fresh semen compared to the control group (P < 0.01). After thawing, the experimental group exhibited significantly higher levels of T-AOC, GSH-Px, and NO compared to the control group (P < 0.01). Additionally, the HFT group, after thawing frozen semen, displayed significantly higher HK1 protein expression compared to the control group. The number of spermatogonia, spermatocytes, and sperm cells in the HFT group was significantly higher than that in the HFC group. Moreover, 16S rRNA sequence analysis showed that Candidatus_Saccharimonas, Staphylococcus, Weissella, succinivbrionaceae_UcG_002, and Quinella were significantly enriched in the rumen of the HFT group, while Ureaplasma was significantly enriched in the HFC group. In the duodenum, Clostridiales_bacterium_Firm_14, Butyrivibrio, and Prevotellaceae_NK3831_group were significantly enriched in the HFT group, whereas Desulfovibrio and Quinella were significantly enriched in the HFC group.

Discussion

Under the conditions employed in this study, L-Cit supplementation was found to enhance the intestinal flora composition in rams, thereby improving semen quality, enhancing the antifreeze performance of semen, and promoting the development of testicular spermatogenic cells.

Effects of different extenders on epigenetic patterns and functional parameters of bull sperm during cryopreservation process

The cryopreservation process induces alterations in cellular parameters and epigenetic patterns in bull sperm, which can be prevented by adding cryoprotectants in the freezing extenders. The purpose of this study was to compare the protective effects of two extenders based on soybean lecithin (SLE) and egg yolk (EYE) on epigenetic patterns and quality parameters of sperm such as motility parameters, mitochondrial membrane integrity, DNA fragmentation, viability, and apoptotic-like changes of bull sperm after cryopreservation. Results demonstrated that cryopreservation significantly (p < .05) reduced the level of DNA global methylation, H3K9 histone acetylation, and H3K4 histone methylation in both frozen groups compared to the fresh sperm. Also, the level of H3K9 acetylation was lower in the frozen SLE group (21.2 ± 1.86) compared to EYE group (15.2 ± 1.86). In addition, the SLE frozen group had a higher percentage of viability, progressive motility, and linearity (LIN) in SLE frozen group compared to EYE frozen group. However, no difference was observed in mitochondrial membrane integrity and DNA fragmentation between SLE and EYE frozen groups. While soybean-lecithin-based extender showed some initial positive impacts of epigenetics and semen parameters, further investigations can provide useful information for better freezing.

Evaluation of Kappa-carrageenan supplementation in extender for post-thaw Kajli ram sperm quality

Cryopreservation is one of the reliable techniques for long-term storage of sperm. The success of this technique depends on the choice of cryoprotectant; therefore, a plethora of literature has reported the effects of different cryoprotective agents so far. Kappa-carrageenan (κ-carrageenan) is a hydrocolloid polysaccharide extracted from red marine seaweed. Its unique property makes it a promising option as a non-colligative cryoprotectant. The current study aims to evaluate the cryoprotective effect of k-carrageenan along with glycerol on ram sperm quality both after equilibration and freezing. Nine Kajli rams were utilized in this experiment for semen collection through an artificial vagina maintained at 42°C. Qualified samples were diluted in tris egg yolk glycerol (TEYG) extender containing different concentrations of k-carrageenan as 0 mg/mL (control), 0.2, 0.5, 0.8 and 1 mg/mL. Post-thaw assessment was done at 37°C after 24 h of storage, which showed a significant improvement (p < .05) in sperm viability, motility, membrane and acrosome integrity in an extender containing k-carrageenan at a concentration of 0.5 mg/mL compared to control. It is concluded from the current study that the combination of glycerol and 0.5 mg/mL concentration of k-carrageenan improved the sperm post-thaw quality.

Comparative developmental competence of in vitro embryos recovered from Bali cattle with normal and poor sperm motility

Background and Aim

Fertility is crucial for enhancing the efficiency of livestock production, as it directly impacts the reproductive rates. A comprehensive understanding of the relationship between sperm quality and embryo development is key to optimizing reproductive outcomes and improving the quality of livestock. This study analyzed the developmental competence of in vitro embryos recovered from Bali cattle with normal or poor sperm motility.

Materials and Methods

Nine bulls with normal fresh semen (NFS) or poor fresh semen (PFS) motility were ejaculated for semen. Semen ejaculates, including volume, motility, and sperm concentration, were evaluated immediately after collection to measure the quality of the fresh semen. Frozen semen was evaluated using computer-assisted semen analysis (CASA) for motility, progressive sperm motility, distance curve path, distance curve linear, distance straight line, average path velocity, curvilinear velocity, linear velocity, straightness (STR), linearity of forward progression (LIN), wobble, and average lateral head displacement (ALH). Bull groups were used to determine in vitro embryo cleavage ability after fertilization of Bali cattle. Ovaries of Bali cattle were collected by slicing, and only cytoplasmic oocytes with compact cumulus cells were used in this study. The oocytes were matured, and in vitro fertilization was performed using fertilization media with a final sperm concentration of 1.5 × 106 spermatozoa/mL. After 48 h, the embryo cleavage ability of the cultured oocytes was evaluated.

Results

There were significant differences in motility values between the NFS and PFS groups; however, there were no significant differences in the volume or sperm concentration. There was a significant difference in the LIN value between the groups but no significant differences in other CASA parameters. There were no significant differences in the cleavage rate and morula between the groups, but a positive correlation was observed between the cleavage rate and the morula and between the morula and ALH. A significant negative correlation was observed between the cleavage rate and STR and between the morula and STR; no significant differences were observed for other variables.

Conclusion

Despite variations in sperm characteristics, both normal and poor sperm motility demonstrated comparable in vitro embryonic development competence. These findings provide important insights into the fertility potential of Bali bulls, providing valuable information that can enhance selection strategies to improve the quality of livestock production.

Cerium oxide nanoparticles improve the post-thaw quality and in-vivo fertility of Beetal buck spermatozoa

The motility, health quality, and membrane disorders of spermatozoa are adversely affected during the process of semen cryopreservation due to the over-production of reactive oxygen species (ROS). Cerium oxide nanoparticles (CeO2NPs) possess properties to scavenge ROS either by mimicking specific antioxidants or by enhancing the activities of antioxidant enzymes. Therefore, we aimed at evaluating the effects of adding the CeO2NPs in the TRIS-citrate-yolk extender on in-vitro antioxidant enzyme activities, spermatozoa quality attributes, and in-vivo fertility of post-thaw Beetal buck spermatozoa. The CeO2NPs were prepared and characterized (UV-spectrophotometry, FTIR, and XRD). Semen samples, collected from bucks (n = 5), were distributed into five aliquots and diluted in an extender containing increasing concentrations of nanoparticles (0 μg/ml, called the control group, 25 μg/mL, 50 μg/mL, 75 μg/mL, and 100 μg/mL). At post-thaw, spermatozoa were evaluated for the above-mentioned attributes and the pregnancy rate by inseminating Beetal does (n = 252). Results demonstrated that CeO2NPs mitigated the detrimental effects of cryopreservation as ROS production and lipid peroxidation were lower (P < 0.001) in the 25, 50, and 75 μg/mL CeO2NPs-added groups compared to the control and 100 μg/ml CeO2NPs-added group. The addition of 25 μg/mL CeO2NPs improved (P < 0.001) the activities of superoxide dismutase, catalase, and peroxidase and the concentration of reduced glutathione (P < 0.001) compared to the other groups. In terms of sperm kinematics and velocity parameters, the groups added with the 25 and 50 μg/mL CeO2NPs exhibited higher total motility (P < 0.001), sperm progressive motility (P = 0.003), and rapid velocity (P < 0.001). The group added with the 50 μg/mL CeO2NPs had the highest (P = 0.04) average path velocity. The groups added with the 25 and 50 μg/mL CeO2NPs also exhibited higher plasma membrane integrity (P = 0.003), acrosomal integrity, and viability (P < 0.001) compared to the control group. The DNA integrity was also higher (P < 0.001) in all the CeO2NPs-added groups. The pregnancy rate was higher (P = 0.003) in the 25 (51.92 %) and 50 μg/mL CeO2NPs (58.33 %) groups compared to the other groups. Conclusively, our findings suggest that the inclusion of cerium oxide nanoparticles in the TRIS-citrate-yolk freezing extender can reduce the occurrence of cryopreservation-induced damages to Beetal's buck spermatozoa and ultimately enhance the pregnancy rate in does.

Cryoprotective Effect of Pectin Tanacetan from Tanacetum vulgare L

We researched the ability of tanacetan pectin from inflorescences of common tansy Tanacetum vulgare L. to change the osmolarity and freezing point of water in solutions of cryoprotectants: glycerol-3.5%, dimethyl sulfoxide (DMSO)-10%, dimethylacetamide-10% (DMAC), and 1.2-propanediol (1.2-PD)-10%, as well as the effect of solutions of tanacetan (0.2%, 0.4%) on the kinetics of crystallization processes and the nature of crystal formation. We used a combination of protector and pectin that we tested earlier, which provided effective protection for human leukocytes and platelets, as well as bovine spermatozoa, at temperatures below freezing (-20°C and -80°C). It has been established that tanacetan slows down the process of water freezing in glycerol, but not in DMSO, DMAC, and 1.2-PD, promotes deeper supercooling of the medium, and affects the morphological structure of ice. The addition of pectin to the cryosolution increases the activity of the main cryoprotectant glycerol even at its low concentrations. The combination of glycerol and tanacetan can be effective in freezing biological materials, which is confirmed by the preservation of leukocytes at -20°C and -80°C for 7 days, platelets at -80°C for 30 days, and spermatozoa at -80°C within 1 day. A comprehensive analysis of the chemical, physicochemical, and cryoprotective properties of tanacetan indicates the prospect of using pectin in the cryopreservation of biological objects at temperatures of electric freezers.

Coenzyme Q10 improves the quality and in vitro fertility of post-thawed buffalo (Bubalus bubalis) semen via its antioxidative effect

This study aimed to determine the effects of Coenzyme Q10 (CoQ10) in the freezing medium on functional and oxidative stress parameters and in vitro fertilization (IVF) rate of buffalo sperm. Collected samples were relocated to the laboratory for initial evaluation, gentle dilution in extenders, cooling (4°C, 2 h), equilibration (4°C, 4 h), packaging (straws, 0.5 mL), programmable freezing, and thawing (37°C, 30 s). Statistical analysis depicted that adding CoQ10 (100 μM) in a freezing medium caused a significant augmentation in total motility (%), average path, and straight-line velocities (μm/sec) of buffalo sperm than control. Adding CoQ10 (100 μM) improved sperm progressive motility, rapid velocity, and functional parameters (%) compared to the control and 10 μM of CoQ10. Moreover, CoQ10 in a freezing medium caused a significant augmentation in seminal plasma catalase (U/mL) and glutathione reductase (GSH; nmol/109 ) at 100 μM than control and other treatments. CoQ10 inclusion (100 μM) ameliorates seminal plasma superoxide dismutase (U/mL), glutathione-S-transferase (GST; nmol/mL/min) fructose (μg/mL), and ATP (nmol/million) than control. Furthermore, CoQ10 at 100 μM improved seminal plasma glutathione peroxidase (μM) levels than control, 10 μM, and 20 μM. Lastly, hydrogen peroxide (H2 O2; nM) production was significantly lower at 100 μM than at control and 10 μM. CoQ10 (100 μM) caused a significant augmentation in the un-capacitated pattern followed by a reduction in the capacitated pattern, and apoptosis-like changes (%) than control, and other treatments, whereas viability was increased than control and other treatments. CoQ10 (100 μM) significantly improved the IVF rate in comparison with control, CoQ10 at 10 μM, and 20 μM groups. In conclusion, the addition of CoQ10 (100 μM) in the freezing medium can improve the quality and in vitro fertility of post-thawed buffalo semen via its antioxidative effect. Further studies are needed to evaluate the effect of CoQ10 on the in vivo fertility of buffalo bull semen.

The effects of green synthesized anionic cupric oxide nanoparticles on Zaraibi goat spermatozoa during cryopreservation with and without removal of seminal plasma

Sperm motility, normal morphology, viability, spermatozoa DNA damage, and lipid peroxidation are all affected by semen cryopreservation. The goal of this study was to see how effective cupric oxide nanoparticles (CuONPs) are as a cryo-extender additive on post-thawed sperm parameters. An artificial vagina was used to collect semen samples from five mature Zaraibi bucks (2-3 years). Ejaculates were pooled and separated into two fractions (A&B), a fraction (A) was left without being centrifuged and a fraction (B) was centrifuged to remove seminal plasma. Both fractions were diluted with tris egg yolk citrate extender (TECE) and then divided into five equal aliquots, each supplemented with (0, 10, 20, 40, and 60 ppm/ml) CuONPs. The findings revealed that removing seminal plasma before cryopreservation harms sperm parameters. Sperm motility, viability index, membrane integrity, biochemical antioxidant marker, DNA integrity, and MDA level improved after supplementation with CuONPs up to 60 ppm/ml, the most prominent significant positive effect was obtained with the highest dose (60 ppm/ml) without removal of the seminal plasm compared to control group. In conclusion: The presence of seminal plasma with a high concentration of CuONPs (up to 60 ppm/ml) may help to mitigate the negative effects of cryo-preservation.

A soy lecithin nanoparticles-based extender effectively cryopreserves Holstein bull sperm

Plant-based semen extenders, typically derived from soybean lecithin, are easier to modulate more and consistent in their composition than animal-based extenders. As large lecithin particles can, however, reduce effectiveness and solubility in bull semen extenders, sonication was used to create nano-lecithin (NL) particles of soybean lecithin. The objective was to determine the effects of lecithin type and concentration on the quality of frozen-thawed bovine sperm. We hypothesized that reducing the size of lecithin improves its interactions with the sperm and enhances the parameters that favor its motility, viability and fertility. Semen was collected from six mature Holstein bulls and ejaculates meeting minimum standards were pooled. Eight Tris-based extenders that contained 1, 2, 3, or 4 % of either conventional lecithin (L1-L4) or NL (NL1-NL4), plus two control extenders (one animal-based extender containing 20 % egg yolk [EY] and a commercial lecithin-based extender [BioXcell®]) were compared. Among soybean lecithin-based extenders, NL3 had the highest total and progressive sperm motility, and average path, straight-line and curvilinear sperm velocity, and was comparable to EY. Additionally, sperm mitochondrial activity was the highest in NL3, whereas sperm viability was highest in EY, NL3, and L4. Following in vitro fertilization of in vitro-matured bovine oocyes, NL3 had cleavage and hatching rates comparable to BioXcell®, but a lower blastocyst rate than EY. Overall, NL3 performed better than the other extenders for most end points, with efficiency comparable to EY. We, therefore, concluded that reducing lecithin particle size to a nano level improves sperm cryopreservation with optimal performance with 3 % NL.

Supplementation of Thymoquinone Nanoparticles to Semen Extender Boosts Cryotolerance and Fertilizing Ability of Buffalo Bull Spermatozoa

Thymoquinone nanoparticles (TQNPs) are broadly utilized in numerous pharmaceutical applications. In the present study, we tested the effects of TQNP supplementation on sperm quality and kinematics, acrosome exocytosis, oxidative biomarkers, apoptosis-like and morphological changes of frozen-thawed buffalo sperm, as well as the fertilizing capacity. Semen was collected from buffalo bulls, diluted (1:10; semen/extender), and divided into five aliquots comprising various concentrations of TQNP 0 (CON), 12.5 (TQNP12.5), 25 (TQNP25), 37.5 (TQNP37.5), and 50 (TQNP50) µg/mL, and then cryopreserved and stored in liquid nitrogen (-196 °C). The results revealed that TQNPs (25 to 50 µg/mL) provided the most optimal results in terms of membrane integrity (p < 0.001) and progressive motility (p < 0.01). In contrast, TQNP50 resulted in a greater post-thawed sperm viability (p = 0.02) compared with other groups. The addition of TQNPs to the extender had no discernible effects on sperm morphology measures. Sperm kinematic motion was significantly improved in the TQNP50 group compared to the control group (p < 0.01). TQNPs effectively reduced the content of H2O2 and MDA levels and improved the total antioxidant capacity of post-thawed extended semen (p < 0.01). The addition of TQNP significantly increased the number of intact acrosomes (p < 0.0001) and decreased the number of exocytosed acrosomes (p < 0.0001). A significant reduction in apoptosis-like changes was observed in TQNP groups. The non-return rates of buffalo cows inseminated with TQNP50-treated spermatozoa were higher than those in the control group (p < 0.05; 88% vs. 72%). These findings suggested that the freezing extender supplemented with TQNPs could effectively enhance the cryotolerance and fertility of buffalo sperm.

Treatment with cholesterol just after thawing maintains the fertility of bull sperm

Freezing and thawing diminish sperm motility and fertility by disrupting the cholesterol balance in sperm plasma and organelle membranes. The aim of this study was to elucidate the mechanisms through which exogeneous cholesterol treatment enhances the quality of frozen-thawed bull sperm. The incorporation of cholesterol was investigated using boron-dipyrromethene (BODIPY)-cholesterol, and BODIPY signals were detected not only in the plasma membrane but also in the midpiece region immediately after thawing. The positive signal of cholesterol in the midpiece region was inhibited by a scavenger receptor class B Type I (SR-BI) inhibitor, block lipid transport 1 (BLT-1). To comprehend the role of exogenous cholesterol in the functions of the plasma membrane, propidium iodide (PI)/Annexin V and peanut agglutinin lectin (PNA) staining were performed. The results showed that treatment with exogenous cholesterol increased the number of acrosome-intact sperm and decreased the number of sperm with damage to the plasma membrane. Moreover, since BODIPY signals were also observed in the midpiece region, mitochondrial function was evaluated using a flux analyzer and a flow cytometer with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl carbocyanine iodide (JC-1) staining, revealing an increase in the number of sperm with high-mitochondrial activity and oxygen consumption. Finally, to assess sperm fertility, computer-assisted sperm analysis (CASA) and IVF were carried out. Sperm velocities and fertilization rates in IVF were significantly enhanced by the addition of cholesterol just after thawing. Thus, the treatment with cholesterol after thawing protected the plasma membrane from the stress of thawing and maintained mitochondrial function, thereby preserving the fertilization ability of frozen-thawed bull sperm for conventional IVF and artificial insemination (AI). Therefore, the application of cholesterol just after thawing is a promising option for improving the fertility of frozen-thawed sperm.

Improvement of post-thaw quality and fertilizing ability of bull spermatozoa using Rho kinase inhibitor in freezing extender

In this study, it was hypothesized that the addition of an appropriate concentration of Y-27632 (a ROCK inhibitor) to the freezing extender prevents cryopreservation-induced apoptosis and improves embryonic development after in vitro fertilization (IVF). Semen samples were collected from five fertile Simmental bulls using an artificial vagina twice a week for 4 weeks. Selected samples were pooled and diluted with Tris-egg-yolk-glycerol (TEYG) extender containing different concentrations of Y-27632 (0, 10, 20, 30, and 40 μM) and then frozen in liquid nitrogen. After thawing, computer-assisted semen analysis (CASA), plasma membrane integrity, and acrosome intactness were evaluated in terms of morphological abnormalities, intracellular generation of reactive oxygen species (ROS), DNA fragmentation, phosphatidylserine (PS) externalization, and apoptotic-related gene expression. Finally, groups of frozen and thawed spermatozoa were used for bovine oocyte IVF. The results show that the semen extender at a concentration of 20 μM Y-27632 effectively improved total motility (TM), curvilinear velocity (VCL), as well as the plasma membrane and acrosome integrity compared to the control group (p < 0.05). Intracellular ROS levels were significantly (p < 0.05) lower in samples treated with 30 μM Y-27632 compared to the control specimen. Furthermore, supplementation of the semen extender with 20 μM Y-27632 resulted in more viable spermatozoa compared with the control group (p < 0.05). According to qRT-PCR results, the expression levels of BAX and CASPASE-9 genes in samples treated with 30 μM Y-27632 were significantly downregulated, while the expression of BCL2 was increased compared to the control (p < 0.05). The results of IVF demonstrated that the treatment of frozen-thawed spermatozoa with 20 μM Y-27632 increased blastocyst rates compared to the control group (p < 0.05). In conclusion, the addition of 20 μM Y-27632 into the freezing extender can improve the functionality and the fertilizing capacity of frozen spermatozoa due to its antioxidative and anti-apoptotic properties.

Correlation between Post-Thaw Spermatozoa Quality of the Endangered Javan Banteng with OPN Gene Expression

The role of ex situ conservation facilities or captivity through captive breeding programs is essential in the conservation of the endangered Javan banteng. The development of semen cryopreservation may assist on one side of the conservation plan. However, the male Javan banteng reproductive capability must be considered as it influences the targeted outputs. Studying the potential biomarker for fertility such as osteopontin gene expression is also expected to help predict male fertility. Therefore, this study aimed to analyze the quality of spermatozoa after thawing to help predict the male reproductive capability of Javan banteng. Furthermore, this study investigated the potential role of osteopontin gene expression in male Javan banteng fertility. A positive reinforcement approach was used to accustom the male and female animals as we focused on establishing a collection procedure using neither sedation nor anaesthesia. Semen samples were collected at Taman Safari Indonesia, Bogor, in accordance with the female banteng receptivity. Semen samples were then evaluated and then cryopreserved under field conditions. Our study showed the different predicted reproductive capability of the Javan banteng based on the post-thaw spermatozoa quality, which showed significant differences. The OPN gene showed positive correlations with the progressive motility (r = 0.711, p = 0.048), viability (r = 0.822, p = 0.012), and acrosomal integrity (r = 0.665, p = 0.072) of Javan banteng spermatozoa after thawing. Our study demonstrated the predicted Javan banteng reproductive capability based on various post-thaw spermatozoa variables. This finding is also the first report on the OPN gene potential to be developed as the assessment tool of post-thaw spermatozoa quality of the male Javan banteng. The findings in our study may help give recommendations for future breeding programs, especially in the ex situ conservation sites.

Effects of propolis-loaded nanoliposomes fortification in extender on buffalo semen cryopreservation

Buffalo sperm is sensitive to cryoinjuries, thus improving sperm cryoresistance is a critical approach for wide spreading the assisted reproductive technologies in buffalo. The intention of this work was to assess the effect of propolis-loaded in nanoliposomes (PRNL) supplementation of semen extender on semen quality, antioxidant status and some apoptotic genes of cryopreserved buffalo semen. PRNL were prepared using cholesterol (Chol) as well as soybean lecithin and their physicochemical properties were characterized. Egyptian buffalo bulls (4-6 years) were involved, and the semen samples were collected using the artificial vagina method. Buffalo semen was pooled (n = 25 ejaculates) and cryopreserved in tris extender containing PRNL at 0 (PRNL0), 2 (PRNL2), 4 (PRNL4) and 6 µg/mL (PRNL6), respectively. The PRNL had a size of 113.13 nm and a negative zeta potential (- 56.83 mV). Sperm progressive motility, viability, membrane integrity, abnormalities, chromatin damage, redox status, apoptosis status, and apoptotic genes were investigated after post-thawed buffalo semen. Using 2 or 4 µg/mL PRNL significantly increased sperm progressive motility, viability, and membrane integrity, while sperm abnormalities and the percentage of chromatin damages were the lowest in PRNL2 group. Moreover, the PRNL2 group exhibited the best results for all antioxidative activities (TAC, SOD, GPx and CAT) with significantly higher levels than the other groups (P < 0.05). The levels of ROS and MDA were significantly lower in the PRLN2 compared with other groups. The sperm caspase 3 enzyme activities showed the lowest values in PRNL2 groups followed by PRNL4 and PRNL6 groups with significant differences compared with the control. Adding 2 µg/mL PRNL to freezing media significantly reduced apoptotic genes such as Bax and Caspase 3 in sperm, while significantly increase in Bcl2 expression compared with the control (P < 0.001). The expression of Bcl2, Caspase 3 and Bax genes in sperm were not affected by the 6 µg/mL PRNL addition (P > 0.05). The electron micrography descriptions exemplified that the fortification of 2 or 4 µg/mL PRNL maintained the acrosomal and plasma membrane integrities as well as sustained the ultrastructure integrity of the cryopreserved buffalo spermatozoa when compared with control group, whereas the 6 µg/mL of PRNL demonstrated highest injury to the acrosome and plasma membranes. Results show supplementation of the buffalo freezing extender with 2 or 4 µg/mL of PRNL enhanced post-thawed sperm quality via boosting the antioxidant indices, diminishing the oxidative stress and apoptosis as well as maintained the ultrastructure integrity of frozen-thawed buffalo sperm.

Kinetic vitrification: concepts and perspectives in animal sperm cryopreservation

Sperm cryopreservation is an important tool for genetic diversity management programs and the conservation of endangered breeds and species. The most widely used method of sperm conservation is slow freezing, however, during the process, sperm cells suffer from cryoinjury, which reduces their viability and fertility rates. One of the alternatives to slow freezing is vitrification, that consist on rapid freezing, in which viable cells undergo glass-like solidification. This technology requires large concentrations of permeable cryoprotectants (P- CPA's) which increase the viscosity of the medium to prevent intracellular ice formation during cooling and warming, obtaining successful results in vitrification of oocytes and embryos. Unfortunately, this technology failed when applied to vitrification of sperm due to its higher sensitivity to increasing concentrations of P-CPAs. Alternatively, a technique termed 'kinetic sperm vitrification' has been used and consists in a technique of permeant cryoprotectant-free cryopreservation by direct plunging of a sperm suspension into liquid nitrogen. Some of the advantages of kinetic vitrification are the speed of execution and no rate-controlled equipment required. This technique has been used successfully and with better results for motility in human (50-70% motility recovery), dog (42%), fish (82%) and donkey (21.7%). However, more studies are required to improve sperm viability after devitrification, especially when it comes to motility recovery. The objective of this review is to present the principles of kinetic vitrification, the main findings in the literature, and the perspectives for the utilization of this technique as a cryopreservation method.

Effects of Melatonin and Silymarin on Reactive Oxygen Species, Nitric Oxide Production, and Sperm Viability and Motility during Sperm Freezing in Pigs

Sperm during the freezing and thawing process is damaged by oxidative stress. Thus, its antioxidant scavenger is essential for sperm survival and death in frozen-thawed semen. We used melatonin and silymarin in experiments after the dose-dependent experiment. Our study aimed to identify the effect of melatonin and silymarin on the motility and viability of sperm, reactive oxygen species (ROS), and nitric oxide (NO) production in frozen-thawed boar semen. Melatonin and silymarin were treated alone and cotreated in the fresh boar semen. Boar semen was collected using the gloved-hand method from ten crossbred pigs, and samples were used in the experiments. We evaluated sperm viability using SYBR-14 and PI kit, and ROS and NO production were detected by DCF-DA and DAF-2, respectively. The sperm motility was not significantly different between non-treatment and treatment. ROS and NO production in frozen-thawed sperm were decreased by melatonin and silymarin. Moreover, silymarin significantly reduced NO production more than melatonin. Melatonin and silymarin enhanced the viability of sperm. We suggest that melatonin and silymarin are essential antioxidants in semen cryopreservation for protecting sperm damage and maintaining sperm viability. Melatonin and silymarin may be useful antioxidants in freezing boar sperm.

Germplasm cryopreservation in bulls: Effects of gonadal tissue type, cryoprotectant agent, and freezing-thawing rates on sperm quality parameters

Germplasm preservation is crucial for reproductive programs involving farm and endangered species. This study describes the effects of slow-uncontrolled cryopreservation protocols on bovine sperm associated with testicular or epididymal tissues. Samples from the testis or epididymis (cauda) were cut into ∼0.5 or 1 cm³ fragments and cryopreserved using Me2SO (Dimethyl Sulfoxide) or glycerol-based cryoprotectants. Sperm were collected from testicular or epididymal tissue before and after freezing-thawing (38 °C or 40 °C) and kept at room temperature (RT) or 4 °C during handling. The parameters studied were viability, membrane integrity (HOS), motility, acrosome integrity, chromatin, and morphology. Pre-freezing parameters were lower in testicular sperm than epididymal: HOS+ and DNA integrity (P < 0.05). Normal-% pre-freezing testicular sperm morphology was lower than epididymal (43.3 ± 1.8% vs. 65.3 ± 14.8%). All testicular RT-kept sperm parameters decreased post-freezing, except for acrosome integrity, which remained constant (P > 0.05). There were no differences in Me2SO-frozen tissue sizes (P > 0.05). All epididymal RT-kept sperm parameters dropped post-freezing except for the constant DNA integrity (P > 0.05). 4^oC-kept sperm were fitter than those at RT (P < 0.05). 4^oC-kept testicular sperm viability, DNA, and membrane integrities declined after 38 °C or 40 °C thawing (P < 0.05). Acrosome integrity and motility remained unchanged after freezing (P > 0.05). 4^oC-kept epididymal sperm acrosome integrity, motility, and HOS+% severely dropped post-thawing (P < 0.05). Viability and DNA integrity were unchanged (38 °C vs. 40 °C; P > 0.05). Overall, post-freezing sperm morphology was unaffected (P > 0.05), but Dag defect was significantly lower in testicular samples (P < 0.05). Whole-epididymis parameters were maintained up to 24h at 4 °C (P > 0.05). In conclusion, testis-epididymis freezing protocols should use small tissue pieces, Me2SO-based cryoprotectants, and 4°C-kept samples to reduce sperm damage.

Molecular Markers: A New Paradigm in the Prediction of Sperm Freezability

For decades now, sperm cryopreservation has been a pillar of assisted reproduction in animals as well as humans. Nevertheless, the success of cryopreservation varies across species, seasons, and latitudes and even within the same individual. With the dawn of progressive analytical techniques in the field of genomics, proteomics, and metabolomics, new options for a more accurate semen quality assessment have become available. This review summarizes currently available information on specific molecular characteristics of spermatozoa that could predict their cryotolerance before the freezing process. Understanding the changes in sperm biology as a result of their exposure to low temperatures may contribute to the development and implementation of appropriate measures to assure high post-thaw sperm quality. Furthermore, an early prediction of cryotolerance or cryosensitivity may lead to the establishment of customized protocols interconnecting adequate sperm processing procedures, freezing techniques, and cryosupplements that are most feasible for the individual needs of the ejaculate.

Lipid alterations by oxidative stress increase detached acrosomes after cryopreservation of semen in Holstein bulls

The nearly exclusive use of cryopreserved semen in cattle breeding enables long shipping distances, higher storage times, quarantine to avoid germ transmission and easy dispersal of high genetic value bulls. Spermatozoa from bulls are well freezable and improvement of cryopreservation protocols over decades has led to high semen quality. However, there is still some loss of spermatozoa in each semen dose due to detached acrosomes after thawing. There are even individual bulls with extremely high numbers of detached acrosomes after cryopreservation, called "bad freezers". This study screened 1092 ejaculates from 59 Holstein bulls for the difference in detached acrosomes before and after cryopreservation (ΔAC). The individual bull influenced ΔAC (P < 0.001) and allowed selection for individuals with repeatedly low ΔAC (good freezers) or high ΔAC (bad freezers). Good freezers were superior to bad freezers in a thermo-resistance test (78.2% vs. 33.6% total motility, respectively, P = 0.047) and had higher non-return rates (NRR: 46.8% vs. 40.8%, respectively, P = 0.016). Since oxidative stress is one possible explanation for premature acrosome reaction, the radical reduction capacity of the seminal fluid was measured, finding that this parameter was reduced in bad freezer bulls during cryopreservation (P = 0.043). Analysis of lipid species in sperm cells by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) showed a reduction of ether lipids and plasmalogens as well as an increase in formyl-lysophosphatidylcholines only within the bad freezers during cryopreservation (P = 0.043). In conclusion these findings show, that lipid alteration caused by oxidative stress is one essential reason for highly augmented acrosome reacted spermatozoa in bad freezer bulls. Therefore, increased use of antioxidants in the extender could be a possible starting point for developing individualized extenders for bad freezer bulls of high genetic value, in order to raise sperm quality after cryopreservation even in those bulls.

Epicatechin Prevents Cryocapacitation of Bovine Spermatozoa through Antioxidant Activity and Stabilization of Transmembrane Ion Channels

Epicatechin (EPC) is a flavonoid belonging to the family of catechins; it has been described as a powerful scavenger of a wide spectrum of reactive oxygen species (ROS) and a modulator of ex vivo sperm vitality. In this study, we assessed the potential protective abilities of EPC on cryopreserved bovine spermatozoa. We focused on conventional quality parameters, as well as the oxidative profile of spermatozoa alongside capacitation patterns, and expression profiles of proteins involved in the process of capacitation. Semen samples were cryopreserved in the presence of 25, 50 or 100 μmol/L EPC and compared to native semen (negative control) as well as ejaculates frozen in the absence of EPC (positive control). A dose-dependent improvement of conventional sperm quality parameters was observed following EPC administration, particularly in case of the sperm motility, membrane, acrosome and DNA integrity in comparison to the positive control. Experimental groups exposed to all EPC doses presented with a significantly lower proportion of capacitated spermatozoa as opposed to the positive control. While no significant effects of EPC were observed in cases of superoxide production, a significant decrease in the levels of hydrogen peroxide and hydroxyl radical were recorded particularly in the experimental groups supplemented with 50 and 100 μmol/L EPC. Western blot analysis revealed that supplementation of particularly 100 μmol/L EPC to the semen extender prevented the loss of the cation channel of sperm (CatSper) isoforms 1 and 2, sodium bicarbonate cotransporter (NBC) and protein kinase A (PKA), which play important roles in the process of sperm capacitation. In summary, we may hypothesize that EPC is particularly effective in the stabilization of the sperm membrane during the freeze-thaw process through its ability to quench ROS involved in damage to the membrane lipids and to prevent the loss of membrane channels crucial to initiate the process of sperm capacitation. These attributes of EPC provide an additional layer of protection to spermatozoa exposed to low temperatures, which may be translated into a higher post-thaw structural integrity and functional activity of male gametes.

Combination of nanoparticle green tea extract in tris-egg yolk extender and 39 °c thawing temperatures improve the sperm quality of post-thawed Kacang goat semen

Kacang goats are small ruminants produced by low-income households in smallholder and farm to reduce poverty and prevent undernutrition. Studies to find a cryopreservation protocol for Kacang goat semen are expected to multiplication of genetically superior animals selected by the paternal lineage. This study evaluated the effect of thawing temperature and supplementation of the green tea extract nanoparticle in skim milk-egg yolk (SM-EY) extender on post-thaw sperm quality of Kacang goat semen. Six ejaculates of Kacang goat were diluted in SM-EY supplemented or not (control group) with 0.001 mg/mL NPs GTE. The diluted semen was packaged with 0.25 mL straws (insemination dose: 60x10⁶ sptz/mL) and cryopreserved. Then, six samples of the control group and NPs GTE groups were thawed at 37°C or 39°C sterile water for 30 s and submitted to sperm quality evaluations. The sperm viability, motility, and intact of the plasma membrane (IPM) were higher (p<0.05) in NPs GTE group than control group. In contrast, the NPs GTE group presented lower (p<0.05) malondialdehyde levels and sperm DNA fragmentation (SDF) compared with the control group. The catalase levels were not significantly different (p > 0.05) between the control and NPs GTE groups. Thawing at 39°C resulted in higher (p<0.05) sperm viability, motility, and IPM than thawing at 37°C. However, thawing at 39°C group presented lower (p<0.05) malondialdehyde levels compared with thawing at 37°C. SDF and catalase levels were similar (p>0.05) between thawing at 37°C and thawing at 37°C. In conclusion, supplementation of 0.001 mg/mL of NPs GTE in SM-EY extender and thawing temperature of 39°C resulted in a better quality of frozen-thawed Kacang goat semen.

Supplementation of Alpha-lipoic acid-loaded nanoliposomes in semen extender improves freezability of buffalo spermatozoa

This research was designed to explore the protective effect of alpha-lipoic acid-loaded nanoliposomes (ALAN) during cryopreservation of buffalo sperm. Buffalo semen was cryopreserved in a tris-citrate egg yolk extender without any supplement (ALAN0, control group) or with ALAN at levels of 25, 50, 75 or 150 µg (ALAN25, ALAN50, ALAN75 and ALAN150, respectively). The ALAN had a size of 171.80 nm and a negative zeta potential (- 43.40 mV). The progressive motility, vitality and membrane integrity significantly improved in all ALAN groups (except ALAN25 for membrane integrity). ALAN150 group exhibited the best values of progressive sperm motility, vitality and membrane integrity after thawing at 37 °C for 30 s or incubated for 2 h at 37 °C and 5% CO₂ compared with those in other groups. Both ALAN75 and ALAN150 groups significantly improved the TAC, GR and catalase, while lipid peroxidation and early apoptotic spermatozoa significantly decreased in ALAN150 group followed by ALAN75 group. Collectively, the adding ALAN to buffalo semen freezing extender plays a substantial shielding function against cryodamage by preserving the sperm functional parameters.

Cryopreservation of Yak Semen: A Comprehensive Review

An urgent need to boost the sustainability and efficiency of animal production exists, owing to the growing global population. Enhancing the global fertility of animals, especially cattle, is essential to ameliorate this issue. Artificial insemination and sperm cryopreservation have a considerable and favorable influence on the quantity and quality of the cattle produced. Sperm cryopreservation is crucial for livestock production because it promotes and accelerates genetic diversity and the worldwide dispersion of animals with enhanced genetics. Owing to the importance of cryobiology in reproductive technologies, researchers are developing new approaches, and they are testing cryoprotectant drugs to enhance sperm cryosurvival. However, the viability of sperm after freezing is low and widely varies across breeding yaks. These faults are crucial because they impede advances in reproductive biotechnology and the study of mammalian gametes at a fundamental level. Using chemicals, researchers have developed and enhanced various extenders with varying degrees of efficiency to reduce cryodamage and oxidative stress. In this article, we review the cryopreservation of yak semen, the development of extenders, the difficulties faced during cryopreservation, and the evaluation of semen quality using various methodologies. This review might be helpful for researchers exploring semen cryopreservation in the future, as demand for enhanced cryopreservation exists to boost the post-thaw viability and fertility of sperm.

In Vitro versus Cryo-Induced Capacitation of Bovine Spermatozoa, Part 2: Changes in the Expression Patterns of Selected Transmembrane Channels and Protein Kinase A

Since the molecular similarities and differences among physiological capacitation and cryocapacitation have not been studied in detail, this study was designed to assess the gene and protein expression levels of the Cation channel of sperm (CatSper) 1 and 2, sodium bicarbonate (Na+/HCO3−) cotransporter (NBC) and protein kinase A (PKA) in un-capacitated (control), in vitro capacitated (CAP) and cryopreserved (CRYO) bovine spermatozoa. All samples were subjected to motility evaluation using the computer assisted sperm analysis and chlortetracycline (CTC) assay for the assessment of the capacitation patterns. Furthermore, quantitative reverse transcription PCR (qRT-PCR) and Western blots were used to monitor the expression patterns of the selected capacitation markers. The results showed a significant reduction in the gene and protein expression levels of CatSper1 and 2 in the CRYO group when compared to the CAP group (p < 0.0001). In the case of NBC, the results were not significantly different or were inconclusive. While a non-significant down-regulation of PKA was found in the CRYO group, a significant reduction in the expression of the PKA protein was found in frozen-thawed spermatozoa in comparison to the CAP group (p < 0.05). In conclusion, we may hypothesize that while in vitro capacitated and cryopreserved spermatozoa exhibit CTC-patterns consistent with capacitation events, the molecular machinery underlying CTC-positivity may be different.

Investigation of Changes in Spermatozoon Characteristics, Chromatin Structure, and Antioxidant/Oxidant Parameters after Freeze-Thawing of Hesperidin (Vitamin P) Doses Added to Ram Semen

We conducted this study to determine the potential cryopreservative effects of different hesperidin (vitamin P; H) doses on ram semen after freeze-thawing. Semen samples were obtained from Sönmez rams using an artificial vagina. The samples were divided into six groups: control, 10, 50, 100, 250, and 500 µg/mL H (C, H10, H50, H100, H250, and H500, respectively). At the end of the study, sperm motility and kinetic parameters, acrosome integrity (AI), mitochondrial membrane potential (MMP), viability, lipid peroxidation levels (LPL), chromatin damage, oxidant parameters, and antioxidant parameters were assayed. None of the doses of H added to the semen extender showed any enhancing effects on progressive motility compared to C (p > 0.05). In fact, H500 had negative effects (p < 0.05). Moreover, AI was the highest at the H10 dose, while LPL values were the lowest at the same dose (p < 0.05). The doses of H10 and H50 added to the Tris extender medium showed positive effects on sperm cell chromatin damage. Consequently, we can say that H doses used in this study are not effective on semen progressive motility, but the H10 dose is effective on AI and chromatin damage by reducing LPL.

Effect of supplementing L-cysteine and its group analogs on frozen semen quality of bulls: A meta-analysis

Background and Aim

The quality of frozen bull sperm after thawing is influenced by the primary diluent and antioxidant. This meta-analysis was conducted to determine the effect of supplementing L-cysteine and its group analogs on the quality of frozen bull sperm.

Materials and Methods

A total of 22 articles obtained from Google Scholar and Scopus were integrated into metadata. The effects of adding L-cysteine and its analogs (e.g., cysteine HCl and N-acetyl-L-cysteine), both of which are known as L-cysteine, were evaluated in this meta-analysis. The following parameters were examined: Abnormality, acrosome damage, acrosomal integrity, DNA damage, DNA integrity, malondialdehyde (MDA) content, plasma membrane integrity, pregnancy rate, progressive motility, sperm viability, and total motility. Data were analyzed using the mixed model methodology, with L-cysteine dosage as a fixed effect and different studies as random effects.

Results

L-cysteine supplementation significantly increased the total motility (p < 0.05) and MDA content of semen, following a linear pattern. Progressive motility, acrosomal integrity, and plasma membrane integrity were significantly increased, showing a quadratic pattern (p < 0.05). Abnormality and acrosome damage were significantly decreased (p < 0.05), following a quadratic and linear pattern, respectively. Other parameters remained unaffected by L-cysteine supplementation. L-cysteine and cysteine HCl significantly inhibited (p = 0.001) acrosome damage in thawed frozen sperm compared with control sperm.

Conclusion

Supplementing L-cysteine and its analog groups are recommended for freezing bull semen as it generally improves sperm quality.

Advances in sperm cryopreservation in farm animals: Cattle, horse, pig and sheep

Sperm cryopreservation is one of the most important procedures in the development of biotechnologies for assisted reproduction. In some farm animals, the use of cryopreserved sperm has so many benefits for which relevance has become more evident in recent decades. Values for post-thaw sperm quality, however, are variable among species and within individuals of the same species. There is no standardized methodology for each of the stages of the cryopreservation procedure (andrological examination, semen collection, dilution, centrifugation, resuspension of the pellet with the freezing medium, packaging, freezing and post-thaw sperm evaluation), which also contributes to differences among studies. Cryotolerance markers of sperm and seminal plasma (SP) have been evaluated for prediction of ejaculate freezability. In addition, in previous research, there has been a focus on supplementing cryopreservation media with different substances, such as enzymatic and non-enzymatic antioxidants. In most studies, inclusion of these substances have led to improved post-thaw sperm quality and fertilizing capacity as a result of minimizing the adverse effects on sperm structure and function. Another approach is the use of different cryoprotectants. The aim with this review article is to provide an update on sperm cryopreservation in farm animals. The main detrimental effects of cryopreservation are described, including the negative repercussion on reproductive performance. Furthermore, the potential use of molecular biomarkers to predict sperm cryotolerance is discussed, as well as the addition of substances that can mitigate the harmful impact of freezing and thawing on sperm.

Sperm Transcriptome Analysis Accurately Reveals Male Fertility Potential in Livestock

Nowadays, selection of superior male candidates in livestock as a source of frozen semen based on sperm quality at the cellular level is not considered accurate enough for predicting the potential of male fertility. Sperm transcriptome analysis approaches, such as messenger RNA levels, have been shown to correlate with fertility rates. Using this technology in livestock growth has become the principal method, which can be widely applied to predict male fertility potential in the livestock industry through the analysis of the sperm transcriptome. It provides the gene expression to validate the function of sperm in spermatogenesis, fertilization, and embryo development, as the parameters of male fertility. This review proposes a transcriptomic analysis approach as a high-throughput method to predict the fertility potential of livestock more accurately in the future.

In vitro versus cryo-induced capacitation of bovine spermatozoa, part 1: Structural, functional, and oxidative similarities and differences

Low temperatures during cryopreservation activate a cascade of changes, which may lead into irreversible damage and reduction of the fertilization potential, including the process of premature capacitation. The aim of our study was to evaluate the range of cell damage following the cryopreservation process and possible activation of cryocapacitation in bovine spermatozoa. For the experiments semen samples were obtained from 30 sexually mature Holstein bulls. Within the analysed parameters, we focused on the functional activity, structural integrity, capacitation status and oxidative profile. The samples were divided into three experimental groups, control (CTRL), in vitro capacitated (CAP) and cryopreserved (CRYO). Based on the collected data, there was a significant decrease in the sperm motility, mitochondrial membrane potential and concentration of cyclic adenosine monophosphate in the CRYO group when compared to CAP and CTRL (P<0.0001). A significant decrease (P<0.01; P<0.0001) in the membrane and acrosome integrity as well as DNA fragmentation index and a significant increase (P<0.0001) of necrotic cells were observed in the CRYO group. Following capacitation, a significant increase (P<0.01; P<0.0001) was recorded in the number of cells which underwent the acrosome reaction in the CRYO group against CAP and CTRL. Changes in the oxidative profile of the CRYO group indicates an increase (P<0.0001) in the reactive oxygen species generation, except for the superoxide radical, which was significantly higher (P<0.0001; P<0.001) in the CAP group in comparison with CRYO and CTRL. In summary, premature capacitation may be considered a consequence of cryopreservation and the assessed parameters could serve as physical markers of cryogenic damage to bovine spermatozoa in the future.

An evidence of Humanin-like peptide and Humanin mediated cryosurvival of spermatozoa in buffalo bulls

Buffalo spermatozoa are vulnerable to cryo-injuries due to inherent deficiency of endogenous antioxidants, high polyunsaturated fatty acids (PUFA) content in plasma membrane and low cholesterol/phospholipid (C/P) ratio. Humanin is a potent cytoprotective agent that protects the cells against oxidative stress and apoptosis. The present study was designed to establish the presence of Humanin in buffalo and effect of Humanin supplementation on freezability of buffalo spermatozoa. Indirect immunofluorescence test revealed presence of Humanin in ejaculated and epididymal spermatozoa, and, elongated spermatids and interstitial space in the testicular tissue section. Humanin levels in seminal plasma were significantly and positively correlated with sperm concentration and individual progressive motility (IPM) in good (n = 22; IPM >70%) and poor (n = 10; IPM <50%) quality ejaculates. For supplementation studies, a total of 24 ejaculates (IPM ≥70%) were collected and each ejaculate was then divided into four aliquots. First aliquot was diluted with egg yolk-tris-glycerol (EYTG) extender without Humanin and served as control group (Group I). Rest three aliquots were diluted with extender containing 2 (Group II), 5 (Group III) and 10 μM Humanin (Group IV), respectively. Semen was cryopreserved using standard protocol and evaluated at pre-freeze for lipid peroxidation (LPO) and post-thaw stages for spermatozoa kinematics, LPO, mitochondrial membrane potential (MMP), capacitation, apoptotic status and DNA integrity. The treatment group that showed best results (5 μM) was compared with control group for in vitro fertility assessment by homologous zona binding assay. The LPO levels were lower (p < 0.05) in 5 and 10 μM Humanin supplemented group. The MMP and DNA integrity were higher (p < 0.05) in 5 μM group than other groups. F-pattern was higher (p < 0.05) and B-pattern was lower (p < 0.05) in 5 and 10 μM Humanin supplemented groups. Lower apoptotic and higher viable spermatozoa (p < 0.05) were observed in 5 μM Humanin group. The mean number of spermatozoa bound to zona pellucida was higher (p < 0.05) in 5 μM Humanin treated group than the control group. The study established the presence of Humanin in buffalo spermatozoa and seminal plasma for very first time and concluded that Humanin supplementation at 5 μM concentration improves the freezability and in vitro fertility of buffalo spermatozoa.

Effect of Sperm Cryopreservation in Farm Animals Using Nanotechnology

Sperm cryopreservation is one of the sublime biotechnologies for assisted reproduction. In recent decades, there has been an increasing trend in the use of preserved semen. Post-thaw semen quality and values vary among animals of the same species. Similarly, there are species-specific variations in sperm morphology, i.e., sperm head, kinetic properties, plasma membrane integrity, and freezability. Similarly, the viability of sperm varies in the female reproductive tract, i.e., from a few hours (in cattle) to several days (in chicken). Various steps of sperm cryopreservation, i.e., male health examination, semen collection, dilution, semen centrifugation, pre- and post-thaw semen quality evaluation, lack standardized methodology, that result in differences in opinions. Assisted reproductive technologies (ART), including sperm preservation, are not applied to the same extent in commercial poultry species as in mammalian species for management and economic reasons. Sperm preservation requires a reduction in physiological metabolism by extending the viable duration of the gametes. Physiologically and morphologically, spermatozoa are unique in structure and function to deliver paternal DNA and activate oocytes after fertilization. Variations in semen and sperm composition account for better handling of semen, which can aid in improved fertility. This review aims to provide an update on sperm cryopreservation in farm animals.

TMT-based quantitative N-glycoproteomic analysis reveals glycoprotein protection can improve the quality of frozen bovine sperm

Cryopreservation of bovine semen plays a vital role in accelerating genetic improvement and elite breeding, but it has a detrimental effect on sperm quality, resulting in the decline of the reproductive efficiency. The glycosylation modification of protein has irreplaceable roles in spermatozoa. Herein, the effect of cryopreservation on glycoproteins of bovine spermatozoa has been studied for the first time using a tandem mass tag (TMT)-labeled quantitative glycoproteome. A total of 2598 proteins and 492 glycoproteins were identified, including 83 different expression proteins (DEPs) and 44 different expression glycosylated proteins (DEGPs) between fresh and frozen spermatozoa. Thirty-three DEPs are glycoproteins, which demonstrates that glycoproteins of bovine sperm were seriously affected by cryopreservation. Moreover, the effects include glycoprotein expression, glycosylation modification, and substructure localization for proteins such as glycoproteins TEX101, ACRBP, and IZOMU4. The biologic functions of the 115 changed proteins are mainly involved in sperm capacitation, migration in female genitalia, and sperm-egg interaction. Mostly key regulators were identified to be glycoproteins, which confirms that glycosylated proteins played important roles in bovine sperm. This comprehensive study of sperm glycoproteins helps to unravel the cryoinjury mechanisms, thus implying that glycoprotein protection should be an effective way to improve the quality of frozen sperm.

Gamma-oryzanol supplemented in extender enhances the quality of semen cryopreservation and alters proteomic profile in Thai swamp buffalo

Reactive oxygen species (ROS) exert an adverse effect on sperm quality during the freezing process. Gamma-oryzanol is an effective antioxidant and has the ability to inhibit lipoperoxidation in various cells. Therefore, this study aims to investigate the effect of gamma-oryzanol supplementation in extender on post-thawed motility and proteomic profiles of swamp buffalo spermatozoa. Each ejaculate of an individual bull was divided into four equal aliquots. Gamma-oryzanol was supplemented at 0 (control), 0.1, 0.25, and 0.5 mM in tris-citrate egg yolk extender. The parameters of sperm motility were evaluated using computer assisted semen analyzer (CASA). The results showed that the progressive motility was significantly higher in 0.5 mM of gamma-oryzanol supplementation group when compared with the control group (p < 0.05), but no significant differences were observed among the treatments. In addition, a proteomic approach was applied to analyze the differentially expressed proteins in post-thawed sperm with or without gamma-oryzanol supplementation in extender. We confirmed that 2-phospho-d-glycerate hydro-lyase (ENO1), glutathione s-transferase mu 1 (GSTM1), phospholipid hydroperoxide glutathione peroxidase (GPX4), outer dense fiber protein 2 (ODF2), tektin-4 (TEKT4), tubulin beta-4B chain (TUBB4B), and ATP synthase subunit beta (ATP5B) were up-regulated in 0.5 mM of gamma-oryzanol supplementation group, which might be associated with the improved post-thawed motility observed in this treatment group. These results demonstrate the beneficial effect of gamma-oryzanol on post-thawed survival of swamp buffalo spermatozoa and help advance the understanding about molecular metabolism of sperm in this species.

Supplementation of Mito TEMPO and acetovanillone in semen extender improves freezability of buffalo spermatozoa

BACKGROUND

Oxidative stress is one of the leading factors responsible for poor post-thaw semen quality because of overproduction of reactive oxygen species (ROS) over neutralizing antioxidants present in semen. Mainly two ROS generation sites are present in spermatozoa, that is, mitochondria and plasma membrane. Therefore, the idea of targeting these specific sites for minimization of ROS production with the compounds having known mechanism of actions was built up as a core for this research.

OBJECTIVE

Present study was done to investigate the effects of Mito TEMPO and acetovanillone individually and in combination on freezability of buffalo spermatozoa.

MATERIALS AND METHODS

For the experiment, semen extender was supplemented with Mito TEMPO (50 μM), acetovanillone (50 μM), and a combination of Mito TEMPO + acetovanillone (50 μM+ 50 μM), designated as Group II, Group III, and Group IV, respectively. Control group without any supplementation was designated as Group I. A total of 24 ejaculates with individual progressive motility (IPM) of ≥70% were selected for the study. After final dilution, filling-sealing of straws, equilibration, and freezing were done as per the standard procedure. Semen samples were evaluated for IPM, plasma membrane integrity, lipid peroxidation, total antioxidant capacity (TAC), and cholesterol to phospholipids (C/P) ratio at both fresh and post-thaw stages. Evaluation of ROS, mitochondrial membrane potential (MMP), capacitation status (CTC assay), and in vitro fertility potential were conducted only on frozen-thawed samples.

RESULTS

The addition of Mito TEMPO (50 μM) and acetovanillone (50 μM) individually and in combination significantly (p < 0.05) improved post-thaw semen quality in terms of IPM, plasma membrane integrity, TAC, cholesterol content, C/P ratio, MMP, Chlortetracycline (CTC)-Full (F) pattern, and zona binding ability of buffalo spermatozoa, while significantly (p < 0.05) reduced ROS production, lipid peroxidation, and capacitation like changes as compared to the control group.

DISCUSSION

As Mito TEMPO acts as an SOD mimetic and also detoxifies ferrous iron at the mitochondria level, it aids in neutralization of excessive ROS production and minimizes oxidative stress-related damages that enhances the antioxidant potential of sperm mitochondria. Earlier studies also indicated improved post-thaw semen quality in 50 μM supplemented group. The improvement observed in acetovanillone (50 μM) group might be because of inhibition of Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase as this enzyme activation by various physical/chemical inducers during cryopreservation process leads to activation of CatSper channel resulting in calcium influx, premature capacitation, and acrosomal reaction like changes through activation of adenylate cyclase and cAMP/PKA-mediated tyrosine phosphorylation of sperm proteins. Acetovanillone also prevents NADPH oxidase-mediated inhibition of glutathione reductase activity, which has a vital role in protecting the structural and functional integrity of sperm plasma membrane.

CONCLUSION

Results indicated beneficial effects of supplementation of Mito TEMPO and acetovanillone on sperm freezability and individual supplementation was as efficient as the combination group for sustaining post-thaw semen quality.

Fertility Rate and Assessment of the Cytoprotective Capacity of Various Types of Holothuroidea Extracts on Spermatozoa

For years, compounds of natural origin have been the subject of extensive biomedical research due to very interesting, new ingredients potentially useful for various pharmaceutical, medical and industrial applications. The therapeutic properties and healing benefits of sea cucumbers may result from the presence of numerous, biologically active ingredients. Sperm subjected to processing and subsequent storage at low temperatures experience a number of damage, including the loss of the integrity of the cytoplasmic membrane, DNA and acrosome defragmentation. Therefore, the aim of this experiment was to investigate the cytoprotective potential of sea cucumber extract against cryopreserved sperm and semen fertility rate. Commercially available sea cucumber extract was taken from the cellulose shell, then 790 mg of powder was weighed out and placed in 3 glass tubes containing, respectively: 10 mL of water-glycerin solution (WG), water-ethanol (EC), glycerin-ethanol (GE), glycerin-DMSO (DG). Tubes were mixed with vortex for 3 min, then placed in a water bath and incubated for 16 h at 40 °C. Six simmental bulls, 3 years old, of known health status were used for the experiment. Semen was collected from each male once a week (for 18 weeks) using an artificial vagina. After an initial assessment of semen quality, the ejaculates were pooled to eliminate individual differences between males, then diluted to a final concentration of 80 × 10⁶ sperm/mL with a commercial extender (Optixcell, IMV, L’Aigle, France) and divided into 16 equal samples. Control (C) without additive, the test samples contained 2, 4, 6, 8 and 10 µL WG, 2, 4, 6, 8 and 10 µL WE, 2, 4, 6, 8 and 10 µL GE, 2, 4, 6, 8 and 10 µL DG. Semen was frozen/thawed and assessed for motility, viability, DNA defragmentation, mitochondrial membrane potential and acrosome integrity. It was shown a positive effect of water-glycerin (WG) and glycerine-ethanol (GE) extracts on the efficiency of sperm preservation at low temperatures. Established that, depending on the type of prepared extract, the sea cucumber can have both cytoprotective (WG, GE, WE) and cytotoxic (DG) effects. Moreover, too high concentrations of the extract can adversely affect the sperm in terms of parameters such as viability, motility, mitochondrial potential, and the integrity of the acrosome or DNA of cells. The present study, thanks to the use of model animals to study the cytoprotective potential of the sea cucumber extract, proves that it can be a potential candidate for use in semen cryopreservation technology to improve the efficiency of storage at low temperatures. Further research is needed to optimize the composition of individual types of extracts and their effect on sperm. The highest effectiveness of female fertilization was observed when doses from GE groups (2 and 4) were used for insemination. The results of this analysis prove that the addition of the tested extract may improve the fertilization efficiency.

Influence of adding zeolite loaded with different charges to semen extender on sperm quality in rabbits after cryopreservation

The aim of the present study was to investigate the effect of supplementing rabbit semen extender with zeolite loaded with different charges (Z⁺ or Z^-, Z^±) on sperm cryopreservation. Semen was collected from six healthy, fertile New Zealand rabbit bucks using an artificial vagina. The collected ejaculates were pooled and diluted with a tris-yolk fructose (TYF) extender supplemented with Z^± (+16, +12, +8, -16, -12, and -8) at a concentration of 1% for a final sperm concentration of 25 × 10⁶ sperm cells/mL. The diluted semen samples were then cryopreserved in 0.25 mL straws and stored in liquid nitrogen for 1 month. To evaluate sperm quality, we examined sperm progressive motility, vitality, morphological abnormalities, and plasma membrane integrity. In addition, apoptotic rates were determined using flow cytometry and by examining sperm ultrastructure under a transmission electron microscope (TEM). Moreover, total antioxidant capacity and markers of lipid peroxidation were measured in the extender after thawing. Addition of Z^± had a positive effect on progressive motility, vitality, and membrane integrity after an equilibration period and post-thawing as compared with the controls (P < 0.05). Z^± supplementation, particularly with a strong negative charge, also decreased the percentages of apoptotic and necrotic sperm cells compared to controls (P < 0.05), as shown both by flow cytometry and TEM. This was not associated with any marked effects on the oxidative biomarkers in the extender. In conclusion, addition of Z^± to semen extender improved post-thawing sperm quality by improving sperm characteristics, decreasing apoptosis, and minimizing sperm damage during cryopreservation.

Effect of glucose concentration and cryopreservation on mitochondrial functions of bull spermatozoa and relationship with sire conception rate

Mitochondrial function is essential for sperm viability, not only from a sperm metabolism perspective, but also for improvement of sperm storage in liquid and frozen states. Bull sperm have notable metabolic variability with energy production for motility and subsequently for fertilizing capacity resulting from both glycolysis and oxidative phosphorylation. The objective of this study was to determine mitochondrial function of sperm using high-throughput Seahorse Analyzer technology in fresh semen and subsequent to freezing-thawing when there was incubation in media commonly used for sperm storage (relatively large glucose concentration) and female tract (relatively small glucose concentration). Additionally, there were determinations whether there were differences in values for fertility variables by regressing sire conception rate on values for mitochondrial variables when there was evaluation of semen from bulls with varying fertility. Media with larger concentrations of glucose inhibited mitochondrial function in fresh sperm, as indicated by less maximal oxygen consumption, spare respiratory capacity and coupling efficiency when compared to sperm in the media containing less glucose. Furthermore, there was greater (P <  0.05) mitochondrial function in cryopreserved-thawed compared to fresh samples with there being no effect of incubation media. These results indicate that mitochondrial damage from cryopreservation cannot be simply overcome post-thawing with glucose supplementation of bull semen incubation media. The increase in mitochondrial function is likely due to "non-productive" oxygen consumption to maintain the mitochondrial proton gradient. Furthermore, there was a negative association of mitochondrial proton leakage with sire conception rate indicating this could be a potential biomarker of bull fertility.

Semen evaluation: methodological advancements in sperm quality-specific fertility assessment - A review

Assessment of male fertility is based on the evaluation of sperm. Semen evaluation measures various sperm quality parameters as fertility indicators. However, semen evaluation has limitations, and it requires the advancement and application of strict quality control methods to interpret the results. This article reviews the recent advances in evaluating various sperm-specific quality characteristics and methodologies, with the help of different assays to assess sperm-fertility status. Sperm evaluation methods that include conventional microscopic methods, computer-assisted sperm analyzers (CASA), and flow cytometric analysis, provide precise information related to sperm morphology and function. Moreover, profiling fertility-related biomarkers in sperm or seminal plasma can be helpful in predicting fertility. Identification of different sperm proteins and diagnosis of DNA damage has positively contributed to the existing pool of knowledge about sperm physiology and molecular anomalies associated with different infertility issues in males. Advances in methods and sperm-specific evaluation has subsequently resulted in a better understanding of sperm biology that has improved the diagnosis and clinical management of male factor infertility. Accurate sperm evaluation is of paramount importance in the application of artificial insemination and assisted reproductive technology. However, no single test can precisely determine fertility; the selection of an appropriate test or a set of tests and parameters is required to accurately determine the fertility of specific animal species. Therefore, a need to further calibrate the CASA and advance the gene expression tests is recommended for faster and field-level applications.

Advancing Semen Evaluation Using Lipidomics

Developing a deeper understanding of biological components of sperm is essential to improving cryopreservation techniques and reproductive technologies. To fully ascertain the functional determinants of fertility, lipidomic methods have come to the forefront. Lipidomics is the study of the lipid profile (lipidome) within a cell, tissue, or organism and provides a quantitative analysis of the lipid content in that sample. Sperm cells are composed of various lipids, each with their unique contribution to the overall function of the cell. Lipidomics has already been used to find new and exciting information regarding the fatty acid content of sperm cells from different species. While the applications of lipidomics are rapidly evolving, gaps in the knowledge base remain unresolved. Current limitations of lipidomics studies include the number of available samples to analyze and the total amount of cells within those samples needed to detect changes in the lipid profiles across different subjects. The information obtained through lipidomics research is essential to systems and cellular biology. This review provides a concise analysis of the most recent developments in lipidomic research. This scientific resource is important because these developments can be used to not only combat the reproductive challenges faced when using cryopreserved semen and artificial reproductive technologies in livestock such as cattle, but also other mammals, such as humans or endangered species.

Influence of seminal plasma during different stages of bovine sperm cryopreservation

This study aimed to evaluate the effect of seminal plasma on bovine sperm cryopreservation and to assess the integrity of plasma and acrosomal membranes, mitochondrial potential, remodelling of F-actin cytoskeleton and sperm chromatin fragmentation during the cooling, equilibrium and freezing/thawing stages. Six ejaculates collected from seven Nelore bulls (n = 42) were used in this study. Each ejaculate was divided into two aliquots (with seminal plasma = SP group; without seminal plasma = NSP group) and packed to a final concentration of 50 × 10⁶ sperm per straw. Statistical analyses were performed using SAS software (version 9.3), and p ≤ .05 was considered significant. A time effect was observed for all sperm characteristics (p < .05), except for chromatin fragmentation (p > .05). The presence of seminal plasma better preserved the acrosomal integrity (SP = 75.2% and NSP = 71.7%; p < .05) and also provided lower F-actin remodelling during cryopreservation process (SP = 29.9% and NSP = 32.4%; p < .05). Regarding to the cryopreservation stages, it was observed that cooling step induced higher remodelling of F-actin than the equilibrium and freezing/thawing stages (56.3%, 32.2% and 23.9%, respectively; p < .05). The equilibrium step had minor influence on overall sperm characteristics while the freezing/thawing stage was responsible for the highest percentage of damage in plasma membrane (-65.2%), acrosomal membrane (-34.0%) and mitochondrial potential (-48.1%). On the other hand, none of the cryopreservation stages affected chromatin integrity. It was concluded that the presence of seminal plasma provides increased acrosomal integrity and reduced remodelling of F-actin cytoskeleton. Higher F-actin remodelling is observed after the cooling step while the freezing/thawing step is most damaging to sperm membranes and mitochondrial potential during bovine sperm cryopreservation.

Antimicrobial activity of silver-carbon nanoparticles on the bacterial flora of bull semen

The spermicidal effects of silver nanoparticles (AgNPs) hinder its application in the field of artificial insemination. In this study, silver-carbon NPs (Ag@C NPs) was synthesized and applied as an alternative antibiotic agent for bull semen extender. Ag@C NPs were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption flame spectroscopy, transmission electron microscope (TEM), and high-resolution TEM (HR-TEM). Data analysis revealed the successful synthesis of Ag@C NPs with a particle size of 1-5 nm (average particle size of 2.5 nm) embedded into carbon. The antimicrobial activity of Ag@C NPs was tested against bacteriospermia of fresh semen collected from five fertile bulls (three ejaculates/bull). Escherichia coli (E. Coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa) were isolated from fresh semen samples and identified by culture, staining, and conventional biochemical tests. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Ag@C NPs against bacteriospermia was determined at 5 and 37 °C. Ag@C NPs showed efficient antimicrobial activity (MIC: 3.125-12.5 μg/mL) against the tested strains and strong bactericidal effect on S. aureus, and P. aeruginosa (MBC: 3.125 μg/mL), with no detrimental effect (P ˃ 0.05) on the percentage of sperm motility (70.71 ± 4.82; 74.65 ± 4.46), plasma membrane integrity (68.39 ± 4.31; 72.38 ± 4.91), acrosome integrity (88.40 ± 13.21; 86.77 ± 14.23), and normal sperm morphology (86.85 ± 7.43; 87.82 ± 8.15) at concentrations of 15 and 30 μg/mL, respectively, after a cold storage of 48 h. However, Ag@C NPs showed a detrimental effect on sperm parameters in a dose dependent manner at concentrations ≥60 μg/mL. Ag@C NPs showed no adverse effect on the sperm's ultrastructure with limited sperm internalization at MIC. In conclusion, Ag@C NPs could be used as an alternative antibiotic agent for bull semen extender without a significant cytotoxic effect on the sperm during cold storage. However, further investigations for their effects on embryo production and female genitalia are still required.

Nanoparticles in pregnancy: the next frontier in reproductive therapeutics

BACKGROUND

Nanotechnology involves the engineering of structures on a molecular level. Nanomedicine and nano-delivery systems have been designed to deliver therapeutic agents to a target site or organ in a controlled manner, maximizing efficacy while minimizing off-target effects of the therapeutic agent administered. In both reproductive medicine and obstetrics, developing innovative therapeutics is often tempered by fears of damage to the gamete, embryo or developing foetus or of negatively impacting a woman's reproductive potential. Thus, nanomedicine delivery systems may provide alternative targeted intervention strategies, treating the source of the disease and minimizing long-term consequences for the mother and/or her foetus.

OBJECTIVE AND RATIONALE

This review summarizes the current state of nanomedicine technology in reproductive medicine and obstetrics, including safety, potential applications, future directions and the hurdles for translation.

SEARCH METHODS

A comprehensive electronic literature search of PubMed and Web of Science databases was performed to identify studies published in English up until February 2020. Relevant keywords were used to obtain information regarding use of nanoparticle technology in fertility and gene therapy, early pregnancy complications (ectopic pregnancy and gestational trophoblastic disease) and obstetric complications (preeclampsia, foetal growth restriction, preterm birth and gestational diabetes) and for selective treatment of the mother or foetus. Safety of specific nanoparticles to the gamete, embryo and foetus was also investigated.

OUTCOMES

Pre-clinical research in the development of nanoparticle therapeutic delivery is being undertaken in many fields of reproductive medicine. Non-hormonal-targeted nanoparticle therapy for fibroids and endometriosis may provide fertility-sparing medical management. Delivery of interventions via nanotechnology provides opportunities for gene manipulation and delivery in mammalian gametes. Targeting cytotoxic treatments to early pregnancy tissue provides an alternative approach to manage ectopic pregnancies and gestational trophoblastic disease. In pregnancy, nanotherapeutic delivery offers options to stably deliver silencing RNA and microRNA inhibitors to the placenta to regulate gene expression, opening doors to novel genetic treatments for preeclampsia and foetal growth restriction. Restricting delivery of teratogenic drugs to the maternal compartment (such as warfarin) may reduce risks to the foetus. Alternatively, targeted delivery of drugs to the foetus (such as those to treat foetal arrythmias) may minimize side effects for the mother.

WIDER IMPLICATIONS

We expect that further development of targeted therapies using nanoparticles in a reproductive setting has promise to eventually allow safe and directed treatments for conditions impacting the health and reproductive capacity of women and for the management of pregnancy and serious pregnancy complications.

A Polyphenol-Rich Extract From Entada abyssinica Reduces Oxidative Damage in Cryopreserved Ram Semen

The Splinter bean, Entada abyssinica, is widely used in folk medicine. In the current work, we profiled the secondary metabolites from E. abyssinica bark extract using LC-MS and investigated its effect on cryopreserved ram semen. Twenty-eight compounds, including tannins and gallic acid derivatives that prevailed in the extract, were tentatively identified. Results showed that the quality of the post-thawed semen showed a significant improvement when the extract was added to the extender at a concentration of 375 μg/mL. The progressive motility and plasma membrane integrity of sperm cells were significantly increased in the post-thawed semen; however, the total antioxidant capacity (TAC) was insignificantly increased. A significant decrease in the concentration of hydrogen peroxide was detected as well. No significant changes were observed in activities of lactate dehydrogenase (LDH), alanine aminotransaminase (ALT), and aspartate transaminase (AST) within the treated samples. Intact sperm percentage was significantly increased, while apoptotic and necrotic sperm percentages were reduced significantly. Molecular docking of some individual components from the extract revealed their potential to interfere with the apoptosis cascade in which Bcl-2 is involved. In conclusion, Entada abyssinica appears to be useful for cryopreservation presumably owing to its polyphenol content that has potent antioxidant capacity scavenging reactive oxygen species (ROS), enhancing the endogenous antioxidant system and inhibiting lipid peroxidation.

Comparative analysis of various step-dilution techniques on the quality of frozen Limousin bull semen

Background and Aim:

Indonesia has two National Artificial Insemination centers and 17 Regional Artificial Insemination Centers. The frozen semen production techniques differed between the centers, including the type of diluent and semen dilution technique. The aim of the research was to compare the quality of frozen Limousin bull semen diluted using different techniques.

Materials and Methods:

Semen was collected from three sexually mature Limousin bulls using an artificial vagina. Immediately after collection, the semen was evaluated macroscopically and microscopically. Semen that had >70% motile sperm and <20% sperm abnormality was divided into three tubes and diluted with skim milk-egg yolk (SMEY) using three different dilution techniques: One-step dilution (100% SMEY with 8% glycerol) at room temperature ([RT] 20°C until 25°C) two-step dilution (50% SMEY without glycerol at RT, stored at 5°C; and 50% SMEY with 16% glycerol after 1 h stored at 5°C); and three-step dilution (50% SMEY without glycerol at RT, stored at 5°C; and 50% SMEY with 16% glycerol added twice at 1 h and 1.5 h after being stored at 5°C). The diluted semen was loaded into 0.25 mL mini straws, equilibrated, and frozen using a freezing machine. Sperm motility, viability, membranes, DNA integrity, and concentrations of malondialdehyde (MDA) and aspartate aminotransferase (AST) enzymes were evaluated after thawing.

Results:

The results showed that there were no significant differences in sperm motility and DNA integrity between dilutions (p>0.05). However, sperm viability and membrane intactness of one-step dilutions were higher than those of three-step dilutions. The concentrations of MDA and AST enzymes of sperm in one-step dilutions were lower than those of three-step dilutions (p<0.05).

Conclusion:

It was concluded that the one-step-dilution technique was better than three-step dilution for cryopreservation of Limousin bull semen.