Effects of rapid cooling prior to freezing on the quality of canine cryopreserved spermatozoa

Using Dextran Instead of Egg Yolk in Extender for Cryopreservation of Spermatozoa of Dogs of Different Ages

Egg yolk is a very common supplement of extenders aimed to protect sperm from cryoinjury, but due to their biological risks and difficulties with media standardization, there is a search for alternative. In addition, sperm cryoresistance can be affected by the initial decrease of their functional characteristics caused by age. The aim of this work was to evaluate the efficiency of using dextran (molecular weight 500 kDa) in the extenders instead of egg yolk for the cryopreservation of spermatozoa of dogs (Chinese Crested breed) of different ages. The obtained ejaculates were divided into three groups depending on the animal's age: 1-3, 4-6 and 7-10 years old. Sperm was cryopreserved by using 7% glycerol and 20% egg yolk, or 20% dextran. The cryoresistance of spermatozoa of the oldest age category was dramatically decreased, which was manifested in their morphology, motility, and DNA fragmentation rate. There were no differences between the cryoprotectant effect of the dextran-based extender on spermatozoa and the egg yolk-based extender in all age categories of dogs. However, given the benefits of dextran-containing media, its use for the cryopreservation of canine spermatozoa has potential benefits that need to be confirmed by sperm fertilization outcomes.

Measurement of the reproductive efficiency of Arabian stallions intended for AI in Algeria

The aim of this study was to determine the reproductive efficiency of Arabian stallions presented at CNIAAG and selected for an artificial insemination (AI) program. Ten Arabian stallions between 8 and 15 years of age were subjected to an analysis of the reproductive parameters. Assessment of sexual behaviour, testicular measurements and appreciation of semen quality collected with the help of artificial vagina was done. There was a significant correlation between the sexual behaviour, the spermatic parameters and the testicular parameters, especially between the number of mounts with the motility and the daily sperm ejaculated (DSP) (r=0.99). The testicular volume total and mounts was highly correlated to the average volume of ejaculate (73.33 ± 60.27 ml) and total Sperm concentration (billions) (r=0.99) which allowed us to produce 38 straws intended for the preservation. Based on the results, it is concluded that there is a positive correlation between (TSW) and motility, the various measurements of testis size were highly correlated with each other; and consequently to predict the fertility of the stallions from the testicular measurements.

Improved viability and fertility of frozen-thawed dog sperm using adipose-derived mesenchymal stem cells

Cryopreservation procedures negatively affect the quality traits of sperm, causing certain changes at structural and molecular levels due to thermal, mechanical, osmotic, and oxidative damage. The objective of this study was to examine the potential of canine adipose-derived mesenchymal stem cells (Ad-MSCs) for providing protection to the dog sperm against cryo-damage. Canine Ad-MSCs were selected on the basis of the significantly higher gene expression for different proteins actively involved in the cell repair including annexin 1 (ANX1), histone H3 (H3) and high mobility group B (HMGB) protein compared to skin fibroblasts. Semen was collected from four healthy dogs by digital manipulation. The washed pooled ejaculates were diluted with buffer 2 (extender) supplemented without Ad-MSCs (Control), with 2.5 × 10⁶ Ad-MSCs/mL (Group 1) or with 5 × 10⁶ Ad-MSCs/mL (Group 2). Group 1 exhibited significantly higher post-thaw motility, live sperm, intact plasma membrane and normal acrosomes than the other groups. Additionally, Group 1 showed significantly higher expression levels of genes related to the repair of membranes (ANX1, dysferlin; DYSF, and fibronectin; FN1) and chromatin material (H3 and HMGB). Protein expression of ANX1, H 3, and FN1 was also statistically more in Group 1 than in Control. The results confirm that canine Ad-MSCs can effectively preserve the quality of frozen-thawed sperm by a reduction in cryoinjury. At an appropriate concentration, Ad-MSCs significantly improve the quality of post-thaw dog sperm.

Use of polyvinyl alcohol as a chemically defined compound in egg yolk-free extender for dog sperm cryopreservation

The objectives of this study were to investigate the effects of polyvinyl alcohol (PVA) as a chemically defined compound in egg yolk (EY)-free extender by determining the appropriate concentration of PVA and the effect of pH adjustment in EY-free PVA extenders on dog spermatozoa. Spermatozoa (1 × 10⁸  cells/ml) were frozen with EY-free extenders supplemented with 0 (control), 0.025, 0.05, 0.1, 0.2 or 0.3 g/100 ml PVA. Sperm progressive motility (PM) was assessed immediately after thawing (IAT) and post-thaw incubation (PTI), while viability, acrosome integrity and reactive oxygen species (ROS) levels were evaluated after PTI. Additionally, spermatozoa were frozen using EY-free PVA extenders before pH adjustment (6.45) and after adjustment of pH (6.85). Viability, PM, ROS and gene expression (BCL2 and SMCP) were assessed. Supplementation with 0.05 g/100 ml or more PVA significantly increased PM compared to the control group in the IAT and PTI. Post-thaw incubation significantly increased sperm motility in all groups. The acrosome integrity in all PVA groups was higher (p < .05) than the control without an effect on ROS and viability. Adjustment of the pH to 6.85 improved (p < .05) sperm PM compared to the non-adjusted groups without affecting viability, ROS or expression of BCL2 and SMCP. We suggest that PVA supplementation in EY-free Tris extenders can effectively protect dog spermatozoa during freezing and can maintain higher motility and acrosome integrity. Adjustment of pH in EY-free PVA extenders can improve post-thaw sperm motility. Therefore, PVA can be used as a compound in EY-free extender for the cryopreservation of dog spermatozoa.

The Effect of Different Concentrations of Caffeine, Pentoxifylline and 2’-Deoxyadenosine on the Biological Properties of Frozen-Thawed Canine Semen

Artificial insemination (AI) and semen cryopreservation are the most accessible and commonly used techniques for breeding domestic animals. Among many parameters, such as plasma membrane integrity and acrosome structure, one of the key factors that determine the quality of frozen-thawed samples for artificial insemination is sperm motility. Sperm motility is one of the key parameters that determine the quality of frozen-thawed samples for AI. The total number of progressively motile spermatozoa in thawed canine semen is correlated with fertility. A variety of substances were used to compare sperm motility with the control. The aim of this study was to determine the effect of semen extender supplementation with motility stimulants, pentoxifylline (PTX), caffeine (CAF) and 2’-deoxyadenosine (DX), after different post-thaw incubation times (30, 60, 120 min) on the motility, selected kinematic parameters, plasma membrane integrity and mitochondrial membrane potential of cryopreserved canine spermatozoa. During attempts to improve the quality of cryopreserved semen, the applied substances exerted beneficial effects at a concentration of 10 mM. We demonstrated that both phosphodiesterase inhibitors, caffeine and pentoxifylline, as well as 2’-deoxyadenosine increased the motility and selected kinematic parameters of thawed canine spermatozoa.

Assessment of motion and kinematic characteristics of frozen-thawed Sirohi goat semen using computer-assisted semen analysis

Aim:

The aim was to determine the motion and kinematics characteristic of frozen-thawed spermatozoa in Sirohi goat using computer-assisted semen analysis.

Materials and Methods:

A study was carried out in Sirohi buck. Semen collection was made biweekly from each buck with the help of artificial vagina. A total of 12 ejaculates were collected from two bucks (six ejaculates from each buck). Freshly collected semen was pooled and later evaluated. The pooled semen sample was extended with standard glycerolated egg yolk tris extender and later subjected to a process of cryopreservation. The motion and kinematic characteristics of spermatozoa were studied during freez-thawing process.

Results:

Significantly (p<0.01) higher value of live percent, hypo-osmotic swelling test, and acrosomal integrity were recorded in neat semen followed by diluted and frozen thaw semen. The proportion of spermatozoa showing slow progression were the highest in the neat and diluted semen followed by rapid and non-progressively motile, while a reverse pattern was observed in the frozen thaw semen where the proportion of non-progressively motile spermatozoa were significantly (p<0.01) higher followed by slow and rapid progression.

Conclusion:

This study showed that the best results for motion, vitality, plasma membrane integrity, and acrosome status were obtained in the neat semen followed by diluted and frozen thaw semen. Further, the process of cryopreservation results in a shift of motility from slow to non-progressive in the post-thaw semen with a significant decrease in the path velocities when compared to neat and diluted semen. Hence, it can be concluded that freezing-thawing process reduces the motility and kinematic characters spermatozoa and may be an important factor affecting the fertilizing ability of spermatozoa resulting in poor conception rate after insemination in goats.

Maintaining canine sperm function and osmolyte content with multistep freezing protocol and different cryoprotective agents

Cryopreservation procedures cause osmotic stress to spermatozoa following cryoinjury and reduce their content of osmolytes. Conventional method for cryoprotectant loading and dilution on canine semen freezing which could be categorized in single step protocol, makes decreasing in sperm performance such as motility, morphology and viability. Therefore, the objective of the present study was to determine if a multistep protocol using glycerol or ethylene glycol can be used to overcome the osmotic sensitivity of canine spermatozoa, and to identify osmolytes that were involved in regulation of osmotic stress. A multistep protocol, comprising serial loading and dilution of cryoprotective agents by dividing the total volume of extender into 4 steps (14%, 19%, 27%, and 40%) every 30s, was compared to a single step method. Frozen-thawed spermatozoa in the multistep group showed superior quality (P<0.05) compared with the single step process in progressive motility (23.3 ± 1.3% vs. 12.5 ± 1.6%), intact membranes (66.5 ± 2.8% vs. 49.5 ± 2.6%) and bent tail (29.2 ± 3.2% vs. 46.2 ± 1.9%). Multistep also succeeded in minimizing loss of the osmolytes carnitine (20.6 ± 2.0 nmol/U G6PDH vs. 10.8 ± 2.1 nmol/U G6PDH) and glutamate (18.4 ± 1.6 nmol/U G6PDH vs. 14.4 ± 0.8 nmol/U G6PDH) compared to the single step group. Moreover, glycerol with multistep was more advantageous for maintaining sperm quality than ethylene glycol. In conclusion, the multistep protocol with glycerol can be used to improve the morphology, motility and osmolytes content of frozen-thawed canine spermatozoa.