Establishment of semen collection technique using electroejaculator and semen cryopreservation of Javan leopard (Panthera pardus melas Cuvier, 1809)

Background and Aim:

The Javan leopard (Panthera pardus melas Cuvier, 1809) is a subspecies of Panthera pardus spp., spread across the African and Asian regions. Information on reproductive aspects is crucial for wild animals, including the Javan leopard. In this study, we aimed to developelectroejaculator (EE) techniques and evaluate cryopreservation success in Javan leopard semen.

Materials and Methods:

The semen of four adult Javan leopards was collected once a week using EE. Placement of the EE probe in the rectum was performed after ultrasound imaging (ultrasonography) to determine the prostate body location. The semen obtained was then evaluated macroscopically and microscopically. Three Javan leopards were used for cryopreservation. The ejaculate was divided into two parts [i.e., one part diluted with AndroMed^® (Minitüb, Tiefenbach, Germany) and the other part with Steridyl^®(Minitüb, Tiefenbach, Germany)] at a 1:1 ratio immediately after collection and evaluation. The semen was then packed in a 0.25 mL MiniStraw^® (Minitüb, Tiefenbach, Germany) then equilibrated at 4°C for 2 h. After equilibration, the straw was then frozen in liquid nitrogen vapor. Frozen semen was then stored in containers until further evaluation.

Results:

The results showed that ejaculation response occurred at all levels of stimulation, while erections did not always occur. The fastest ejaculation and erection occurred at the fourth voltage. The macroscopic evaluation showed that the semen volume was 0.80±0.26 mL, cloudy white, pH 7.44±0.14, and with watery semen consistency. The microscopic evaluation showed that the sperm motility was 66.98±0.39%, with sperm viability of 75.6±1.79%. Sperm concentration was 62.17±46.95×10⁶ mL⁻¹ with a total concentration of 42.14±23.51×10⁶ cells. Normal sperm morphology is only 40.72±6.26%.

Conclusion:

This study concluded that the development of a semen collection technique using an EE preceded by imaging of the EE probe location using ultrasound was effective for the ejaculation of Javan leopards. The characteristics of the semen of the Javan leopard showed moderate semen volume, sperm motility, and viability. Javan leopard showed low sperm concentration and normal sperm morphology.

Epididymal tail solid-surface vitrification as an effective method for domestic cat sperm cryobanking

This study aimed to describe the viability of domestic feline spermatozoa after epididymal tail vitrification. For this, 10 pairs of testis-epididymis complexes were used. The epididymal tails were vitrified using the solid-surface vitrification (SSV) method, in which two vitrification media containing ethylene glycol (EG) 40% or glycerol (GLY) 40% were tested. Vitrification with the presence of EG resulted in better results for all sperm motility parameters (motility, vigour and CASA) compared with GLY (P < 0.05). There were no statistical differences for sperm viability and acrosome integrity, plasma membrane integrity, or overall health of morphologically normal sperm before or after vitrification among experimental groups. In conclusion, epididymal tail vitrification appears to be a suitable method for long-term storage of cat sperm, especially if the procedure is performed with EG as the cryoprotectant.

Can amides be alternative cryoprotectors for the preservation of feline semen?

Sperm cryopreservation is a tool for the conservation of the genetic material of animals of genetic importance or for species preservation. In the case of domestic cats, this can be used to generate information about seminal harvest, evaluation and preservation, which is especially important due to its applicability to wild felids. This study evaluated seminal samples harvested by urethral catheterisation from 13 adult domestic cats. Samples were cryopreserved with experimental groups of extenders were defined by the penetrating cryoprotectant: 6% glycerol (GLY6%), 3% dimethylacetamide (DMA3%) and 3% dimethylformamide (DMF3%). The samples were thawed and evaluated by conventional microscopy and by computer-assisted sperm analysis (CASA). The structural and functional membrane integrity was assessed by supravital tests (EOS), hypoosmotic swelling tests (HOST) and flow cytometry (FC). There was a correlation (P < 0.05) between total motility and EOS (r = 0.54), HOST and FC (r = -0.62) and total motility and flow cytometry (r = 0.63), indicating that these are complementary parameters that increase the accuracy of the feline sperm quality evaluation post-thaw. The results regarding the structural and functional integrity of the sperm plasma membrane did not differ (P > 0.05) among groups. However, the DMA3% group had a lower (P < 0.05) percentage of morphological changes in the sperm tail compared to samples cryopreserved with GLY6% and DMF3%. Additionally, DMA3% provided lower values of immobile sperm post-thaw when compared to DMF3%. DMA is an interesting alternative to GLY and superior to DMF for the cryopreservation of feline semen at the studied concentrations.

Optimal concentration of Rho-associated coiled-coil kinase (ROCK) inhibitor improved sperm membrane functionality and fertilizing ability of cryopreserved-thawed feline sperm

Sperm cryopreservation induces irreversible loss of viability and fertilizing ability. This study aimed at examining the effects of Rho-associated, coiled-coil kinase (ROCK) inhibitor on quality of frozen-thawed feline sperm. Ejaculated semen from individual cats (n = 6) was examined for the expression of LIMK1 and LIMK2 mediated ROCK cascade. The effects of ROCK inhibitor during cooling and cryopreservation on sperm quality and fertilizing ability were also examined. Feline sperm were treated with different concentrations of ROCK inhibitor (10, 20 and 40 μM) during cooling at 4 °C and cryopreservation. Sperm cooled and conventionally cryopreserved without ROCK inhibitor (0 μM) served as a control group. The ROCK cascade was confirmed in feline sperm as they expressed mRNA of LIMK1 and LIMK2 genes. Cryopreservation significantly reduced sperm quality in terms of viability (91.63 ± 3.96 vs. 60.11 ± 8.93), progressive motility (91.67 ± 3.54 vs. 46.67 ± 8.66) and acrosome integrity (93.49 ± 3.64 vs. 63.81 ± 5.31) for fresh and frozen-thawed sperm, respectively (p < 0.05). The positive effects of ROCK inhibitor on sperm quality were pronounced at 1 and 3 h post-thaw. ROCK inhibitor at 10 μM significantly improved sperm motility and membrane functionality compared to those observed in a control group (0 μM) (p < 0.05). In vitro fertilization revealed that supplement ROCK inhibitor at 10 μM during cryopreservation significantly improved in vitro fertilizing ability of the frozen-thawed sperm (p < 0.05). However, it did not subsequently increase morula and blastocyst rates (p > 0.05). Increased concentrations of ROCK inhibitor to 20 and 40 μM did not further improve the quality of frozen-thawed sperm. In conclusion, an optimal concentration (10 μM) of the ROCK inhibitor added into cooling medium could improve post-thaw sperm quality.

Cryopreservation of margay (Leopardus wiedii) spermatozoa: Effects of different extenders and frozen protocols

Sperm cryopreservation offers many benefits to wild felids conservation programs. However, the implementation of these programs is limited by the different responses of each species to the cryopreservation protocols and extenders used, requiring the formulation of species-specific protocols. For this purpose, semen samples from 6 margays (Leopardus wiedii) were submitted to 2 cryopreservation protocols: 1) manual freezing (cooling rate of - 0.33 °C/min at 5 °C/180 min and freezing rate with two steps - 9 °C/min for 2 min and -19.1 °C/min for 2 min) and 2) automatic freezing machine (cooling rate of - 0.25 °C/min at 5 °C/120 min and freezing rate with one step -20 °C/min for 8.3 min) using 2 commercial extenders, an egg yolk-based (Test Yolk Buffer; TYB) and an egg yolk-free extender (AndroMed; MED). Post-thawed sperm quality was assessed at 3 time points (immediately after thawing and 1 and 2 h post-thawed) by sperm motility index (SMI), plasma membrane and acrosomal integrity, and mitochondrial membrane potential (MMP). Regarding SMI, TYB yielded superior results (29.4 ± 3.5%) compared to MED (11.2 ± 2.8%; p < 0.002) immediately after thawing until 2 h after thawing (TYB 3.9 ± 1.7% and MED 0.0 ± 0.0%; p < 0.05). Furthermore, the automated freezing method provided higher motility compared to the manual freezing procedure immediately post-thaw (25.08 ± 3.66% and 15.78 ± 3.29%, respectively) and 1 h post-thaw (13.71 ± 2.56% and 6.03 ± 1.97%, respectively; p < 0.05). The percentage of intact acrosomes and plasma membranes and the percentage of sperm with high MMP were superior for TYB when compared to MED regardless of cryopreservation protocol (p < 0.05). Conversely, the interaction between cryopreservation protocols and extenders was observed for MMP where TYB exhibits better results compared to MED (p < 0.05) in both procedures, but it was higher in automated procedures. For MED, no changes were found in MMP between procedures. Considering only TYB, samples showed higher MMP when submitted to an automated procedure (p < 0.05). In conclusion, the slow cooling rates with shorter time of exposure to glycerol contributed to minimize cryodamage in the Margays' sperm. Moreover, results indicated that association between TYB and automatic freezing machine ensured the minimal quality of spermatozoa after thawing required for further use in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).

Saadeldin I, Ba-Awadh H, G. Al-Mutary M, F. Moumen A, N. Alowaimer A, Abdalla H. Efficiency of Commercial Egg Yolk-Free and Egg Yolk-Supplemented Tris-Based Extenders for Dromedary Camel Semen Cryopreservation

Simple Summary

This study compared the efficiency of commercial egg yolk-free (AndroMed, OPTIXcell) and egg yolk-supplemented (Triladyl, Steridyl) Tris-based extenders for semen cryopreservation in dromedary camels. The camel-specific extender SHOTOR was used for reference. SHOTOR, Triladyl, Steridyl, AndroMed, and OPTIXcell can all be used for camel semen cryopreservation; however, SHOTOR and Triladyl provide the best post-thawing sperm quality.

Abstract

This study compared the efficiency of commercial egg yolk-free (AndroMed, OPTIXcell) and egg yolk-supplemented (Triladyl, Steridyl) Tris-based extenders for semen cryopreservation in seven adult dromedary camels. The camel-specific extender SHOTOR was used as control. The collected semen samples were evaluated and diluted with SHOTOR, Triladyl, Steridyl, AndroMed, or OPTIXcell. The diluted semen was gradually cooled and equilibrated for two hours before liquid nitrogen freezing. Semen was evaluated prior to freezing and after freeze-thawing cycles for motility, kinetics, vitality, abnormality, plasma membrane integrity, and DNA fragmentation using computer-assisted sperm analysis. In pre-freezing evaluation, progressive sperm motility was higher in SHOTOR-diluted samples (21.54 ± 1.83) than in samples diluted with Steridyl, OPTIXcell, or AndroMed (15.76 ± 1.80, 17.43 ± 1.10, and 13.27 ± 1.07, respectively). Moreover, Triladyl and SHOTOR resulted in significantly (p < 0.05) better sperm vitality and DNA integrity than all other diluents, but Triladyl resulted in a significantly (p < 0.05) better plasma membrane integrity (87.77 ± 0.31) than SHOTOR (85.48 ± 0.58). In the post-thawing evaluation, Triladyl led to significantly (p < 0.05) higher sperm motility (38.63 ± 0.81%; p < 0.05) when compared to SHOTOR, Steridyl or AndroMed (35.09 ± 1.341%, 34.4 ± 0.84%, and 31.99 ± 1.48%, respectively), with OPTIXcell being the least efficient (28.39 ± 0.86%). Progressive sperm motility was the highest when using Triladyl. Post-thawing curvilinear, straight line and average path sperm velocities were highest with Triladyl and lowest with AndroMed. Triladyl led to the highest linearity coefficient and straightness sperm coefficient, while SHOTOR to the highest DNA and plasma membrane integrity. OPTIXcell and AndroMed resulted in poor post-thawing sperm vitality, while Steridyl was less efficient than Triladyl. The highest rate of sperm abnormalities was recorded with OPTIXcell and the lowest with SHOTOR or Triladyl. In conclusion, SHOTOR, Triladyl, Steridyl, AndroMed, and OPTIXcell can all be used for camel semen cryopreservation; however, SHOTOR and Triladyl provided the best post-thawing sperm quality. Based on our findings, Triladyl is the best commercially available extender for dromedary camel semen cryopreservation to date.

Sperm cryopreservation in the Far-Eastern wildcat (Prionailurus bengalensis euptilurus)

The Far-Eastern wildcat (Prionailurus bengalensis euptilurus) is a rare and poorly investigated nondomestic felid species. An attempt of freezing and cryopreserving Far-Eastern wildcat spermatozoa in CaniPlus Freeze (CPF) medium is reported. Sperm was collected by electroejaculation from five adult Far-Eastern wildcat captive-born males. Epididymal spermatozoa from five adult randomly bred domestic cat males were used as a reference. The viability of frozen-thawed spermatozoa evaluated by double staining with SYBR Green I and PI followed by the subsequent confocal laser scanning microscopy (CLSM) was 38.2% ± 3.0% for the domestic cat and 38.0% ± 10.2% for the Far-Eastern wildcat. The motility of frozen-thawed spermatozoa was 30.8% ± 9.8% for the domestic cat and 33.7% ± 15.1% for the Far-Eastern wildcat. Sperm morphology was assessed by light microscopy. The total percentage of normal spermatozoa after freezing and thawing was 51.9 ± 5.9 for the domestic cat and 55.0% ± 6.4% for the Far-Eastern wildcat. Defects of flagella were the most frequently observed abnormalities in both species (32.2% ± 4.8% and 30.8% ± 4.4% of all reported anomalies for the domestic cat and Far-Eastern wildcat, respectively). Domestic cat epididymal and Far-Eastern ejaculatory spermatozoa fertilized in vitro-matured oocytes of the domestic cat (30.0% ± 5.5% and 35.5% ± 15.0%, respectively). Taken together, these results suggest that the freezing of Far-Eastern wildcat spermatozoa with CPF medium is a suitable method for Felidae cryopreservation.

Determination of appropriate cryopreservation protocols for epididymal cat spermatozoa

Effects of Equex and glycerol additions and sample dilution step on frozen-thawed epididymal cat spermatozoa were investigated. The epididymal sperm pellets were resuspended in extenders using one- (groups III and IV) or two- (groups I, II, V and VI) step dilution. For one-step dilution, the pellets were resuspended in plain egg yolk-Tris medium (EYT) + 5% glycerol with (IV)/without (III) 0.5% Equex and cooled (4(°) C, 1 h). For two-step dilution, the pellets were resuspended in EYT (I and V) and in EYT + 3% glycerol (II and VI), cooled and further diluted with EYT + 10% glycerol with (I)/without (V) 1% Equex and with EYT + 7% glycerol with (II)/without (VI) 1% Equex. Immediately after freeze-thawing, no differences (p > 0.05) were found in the motility, viability and membrane integrity (HOST) among the groups except the lowest HOST in IV (p = 0.005 to p = 0.04). The acrosome integrity (FITC) in group I was comparable to that in group II (p > 0.05) and was higher than the rest (p < 0.001 to p = 0.02). At 2 h after thawing, the motility, viability and HOST were comparable among the groups (p > 0.05) except the lower percentages of viability in III (p = 0.008 to p = 0.3) and of HOST in IV (p = 0.005 to p = 0.2). Two-step dilutions with Equex (I, II) were more beneficial for the FITC at 2 h than without Equex (V) (p = 0.005 and p = 0.02) and than one-step dilutions (III, IV) (p < 0.001 to p = 0.02). In conclusion, epididymal cat sperm quality after freeze-thawing could be improved when Equex was added and two-step dilution was performed during freezing. The extenders prepared for the first step of dilution could be with (3%) or without (0%) glycerol.

Sperm-TALP: an alternative extender for retrieving and diluting epididymal sperm in the domestic cat

Effects of sperm-TALP (TALP) on the quality of fresh-extended and frozen-thawed epididymal cat sperm were evaluated. The epididymides suspended in Tris-glucose-citrate solution (Tris), a conventional medium, and TALP were cut into small pieces to recover epididymal sperm. In experiment 1, the sperm pellets remained after centrifugation were re-suspended (1 : 2, v/v) in Tris and TALP. The sperm quality in all four groups, that is, sperm retrieved with Tris (I and II) or TALP (III and IV) and diluted with Tris (I and III) or TALP (II and IV) was assessed. The sperm motility at the 0-h incubation in TALP-TALP was superior to that of the rest (p < 0.001 to p = 0.04). At the 2-h incubation, the motility in Tris/TALP-TALP was greater than that in Tris/TALP-Tris (p ≤ 0.001). In experiment 2, after centrifugation, the sperm pellets were added with freezing extenders and frozen. The thawed sperm previously retrieved from the epididymides with Tris and TALP were allotted so as not to further diluted (Tris/TALP-O) and to further diluted (1 : 1, v/v) with Tris (Tris/TALP-Tris) and TALP (Tris/TALP-TALP) and were evaluated the quality. At both incubation times, the motility of frozen-thawed sperm recovered with TALP (TALP-O/Tris/TALP) was comparable with or significantly higher than that in the Tris groups (Tris-O/Tris/TALP; p = 0.003 to p > 0.05). The motility and viability of thawed sperm in Tris-Tris were significantly decreased during the 2-h incubation (p = 0.007 for the motility and p = 0.01 for the viability). In both experiments, neither type of diluent (Tris vs TALP) nor incubation time (0 vs 2 h) significantly affected the sperm membrane integrity under hypo-osmotic condition (p > 0.05). According to beneficial effects on the quality of fresh-extended and frozen-thawed sperm demonstrated, sperm-TALP could be used as an alternative medium for recovering sperm from the epididymides and for diluting epididymal sperm in the domestic cat.