Effects of four extenders on the quality of frozen semen in Arabian stallions

Stallion Sperm Freezing with Different Extenders: Role of Antioxidant Activity and Nitric Oxide Production

Sensitivity to freezing remains a critical issue in stallion semen cryopreservation procedures. To explore this topic in-depth, semen was collected from ten stallions, diluted with three different extenders, transported to the laboratory, and then centrifuged and frozen with four different extenders. We conducted analyses of sperm kinetics, mitochondrial membrane potential (MMP), and hydrogen peroxide content both before and after freezing. Additionally, we assessed antioxidant activity using the ABTS and FRAP methods and measured nitric oxide stable metabolites (NOx) in the blank extenders, seminal plasma, and extenders conditioned by spermatozoa before and after freezing. We found significant variability in the antioxidant activity and NOx content of the blank extenders and the seminal plasma. In the seminal plasma, ABTS-based antioxidant activity and NOx values were correlated with some sperm kinematic parameters and MMP in refrigerated semen, while no correlation was observed in frozen sperm parameters. Sperm function varied significantly between stallions but not between extenders, either before or after freezing. However, significant differences in antioxidant activities and NOx values were found among extenders conditioned following freezing. These results provide new insights into the factors contributing to the variability in individual stallions' tolerance to sperm freezing.

Effects of Different Diluents and Freezing Methods on Cryopreservation of Hu Ram Semen

The purpose of this study was to investigate the effects of different diluents and freezing methods on the quality of thawed sperm after cryopreservation and find an inexpensive and practical method for freezing Hu ram semen for use in inseminations under farm conditions. Ejaculates were collected from five Hu rams. In experiment I, ejaculates were diluted with eight different freezing diluents (basic diluents A, B, C, D, E, F, G, and H). After dilution and cooling, the samples were loaded into 0.25 mL straws and frozen using the liquid nitrogen fumigation method. In experiment II, diluent C was used as the basic diluent and the semen was frozen using liquid nitrogen fumigation and two program-controlled cooling methods. For analysis, frozen samples were evaluated in terms of motility parameters (total motility (TM), progressive motility (PM)), biokinetic characteristics (straight-line velocity (VSL), average path velocity (VAP), curvilinear velocity (VCL), amplitude of lateral head displacement (ALH), wobble movement coefficient (WOB), average motion degree (MAD)), reactive oxygen species (ROS) level, and membrane and acrosome integrity. In experiment I, diluent C had higher TM, PM, and acrosome and membrane integrity and lower ROS compared to other extenders (p < 0.05) except diluent A. Diluent C exhibited higher (p < 0.05) VCL, VAP, ALH, WOB, and MAD compared to diluents B, D, E, and F. In experiment II, TM and all biokinetic characteristics did not show significant differences (p > 0.05) amongst the three freezing methods. Liquid nitrogen fumigation resulted in higher (p < 0.05) PM, membrane integrity, acrosome integrity, and lower ROS level compared to the program. In conclusion, the thawed semen diluted with diluent C had higher quality compared to other diluents. The liquid nitrogen fumigation demonstrated superior semen cryopreservation effects compared to the program-controlled cooling method using diluent C.

Spirulina supplementation to the semen extender influences the quality and antioxidant parameters of chilled or cryopreserved Arabian stallion spermatozoa

The present study attempted to investigate the effect of various concentrations of spirulina platensis additions to the semen extender on Arabian stallion spermatozoa quality. Semen samples were collected with artificial vagina from five fertile stallions and diluted with an extender containing spirulina (2, 4, 6, and 8 mg/100 mL) or without spirulina (control). Aliquots of diluted semen were cooled (5°C, 90 min.) and frozen (-196°C, 7 d), then physical traits of thawed spermatozoa were examined. Furthermore, antioxidant activities of superoxide dismutase (SOD), glutathione reductase (GSR), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured in post-cooling and freezing spermatozoa. The results indicated that spirulina supplemented with the extender had no effect (P > 0.05) on sperm quality parameters and antioxidant activities after cooling. However, adding 6 mg spirulina/100 mL to the freezing extender improved (P < 0.05) the speed parameters and total motility percentage of frozen/thawed spermatozoa. Besides, supplementation of freezing extender with the previous level increased (P < 0.05) TAC, SOD and GSR concentrations/activities (0.86 ± 0.32 mM/L, 323.70 ± 12.81 U/mL, and 38.65 ± 1.90 U/mL, respectively) compared with the control (0.70 ± 0.25 mM/L, 165.80 ± 8.12 U/mL, and 25.70 ± 1.83 U/mL, respectively). While, lipid peroxidation of the frozen-thawed semen was reduced (P < 0.05, 17.97 ± 1.30 µmol/ L) compared with the control (29.39 ± 1.89 µmol/ L). Accordingly, the present results revealed that additions of 6 mg spirulina/100 mL to the freezing extender improved semen quality and reduced cryodamage of the Arabian stallion spermatozoa.

Efficiency of Ringer B. Braun solution on stallion epididymal sperm motility and viability compared to the commercial extender within 72 hours of storage

Collection of epididymal stallion sperm offers the opportunity to retain and use genetic material from the males after elective castration or even post mortem. The aim of the present study was to evaluate the effect of the Ringer B. Braun solution on stallion epididymal sperm viability and motility during liquid storage for 72 h at 4 °C and at 20 °C. Eight stallions (3–10 years old) were used in the study. Sperm from the cauda epididymis was harvested immediately after routine castration. The sperm from epididymis was washed out and diluted with Ringer B. Braun solution and with a commercial semen extender which was used as a control. Samples from each horse were divided into two parts: one part of samples was stored at 4 ± 1 °C as recommended for the commercial semen extender, the other one was stored at 20 ± 1 °C. Sperm viability, motility, and pH were checked one hour after collection and dilution, and after 24, 48 and 72 h of incubation. The results of sperm viability, subjective and progressive sperm motility showed slightly higher results in semen samples diluted with Ringer B. Braun solution in one hour compared to the commercial extender, by 2.40 ± 0.49% for viability (P > 0.05), by 0.30 ± 9.92% for subjective motility (P > 0.05) and by 5.70 ± 6.07% for progressive motility (P > 0.05). We suggest that Ringer solution could be used for a short term storage (1–24 h) of equine epididymal semen at a 4 °C temperature.

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.

Hormonal Levels and Follicular Dynamics in Relation to the Oestrous Cycle in Barb and Arabian Mares, Algeria

This current study is an effort to understand the hormonal and follicular growth in the Barb and Arabian mares during the oestrous cycle; as mares are unique creatures. A total of 53 mares with 97 oestrous cycles were studied. The mares with a mean age of 10.38 ± 4.55 were examined by ultrasonography every day during their breeding season (2017). Two blood samples from each mare (n = 24) were obtained for progesterone (P4), oestrogen (oestradiol-17 beta) and follicle-stimulating hormone (FSH) determinations. The data revealed that the duration of the oestrous cycle was between 19 to 22 days. The pre-ovulatory follicle grew (3.02 ± 1.04) millimetre per day. The rate of cycles exploited in the mare (Arabian versus Barb) for conception was significantly different (P < 0.001). The maximal diameter of the follicle was 50.00 millimetre. The serum progesterone levels (P < 0.01) in mares were significantly higher in the luteal phase than those recorded during the time of oestrous. However, the levels of oestradiol and for FSH did not significantly change during the oestrous cycle in the mares. Determining the association between the size of the follicle and the hormone profiles were the most reliable criterion in the prediction of ovulation.

A preliminary study on the effects of E-Z Mixin® and EquiPlus® extenders supplemented with Edible Bird's Nest on the quality of chilled Arabian stallion semen

The aim of this study was to evaluate the effects of adding different concentrations of edible bird’s nest (EBN) which is secreted by swiftlet birds (Aerodramus fuciphagus), into EquiPlus® and E-Z Mixin® extenders on the quality of chilled Arabian stallion semen at various storage times (0, 24 and 48 h). Ten ejaculates were collected from five stallions, and diluted using the two extenders containing 0% (control), 0.12%, 0.24% and 0.24% of EBN + seminal plasma (SP). All the diluted semen samples were then cooled and stored at 5 °C, and examined at 0, 24 and 48 h. Sperm kinetic parameters were assessed using computer assisted sperm analysis (CASA) and viability were assessed using Hoechst33342/PI stain. In both extenders, total motility (TM) and progressive motility (PM) were significantly higher at 0.12% and 0.24% compared to 0.24% + SP at 24 and 48 h. At 0.12%, E-Z mixin® treated semen had significantly higher TM and PM than EquiPlus^® at 24 and 48 h. At 0.12% and 0.24%, average path velocity (VAP), straight-line velocity (VSL) and curvilinear velocity (VCL) were significantly higher in E-Z mixin® treated semen compared to EquiPlus^® at 24 and 48 h. Comparisons between the two extender types at different concentrations of EBN showed no significant difference in lateral head amplitude (ALH), linearity (LIN), straightness (STR), beat cross frequency (BCF) and viability, irrespective of the storage time. The percentage of viable was significantly higher in E-Z mixin® than EquiPlus® at 0 and 48 h in control and 0.12%. Supplementation of the E-Z mixin^® extender with 0.12% and 0.24% EBN concentrations in the absence of SP provided better CASA parameters such as TM, PM, VAP, VSL, and VCL at 24 and 48 h storage time. In conclusion, the results of this study indicated that chilled semen from Arabian stallion that was extended using E-Z mixin® and supplemented with 0.12% and 0.24% EBN concentrations performed better and yielded superior results in sperm kinetic parameters and % viable compared to EquiPlus® at 24 and 48 h storage time.

The inhibition of spermatic cystine/glutamate antiporter xCT (SLC7A11) influences the ability of cryopreserved stallion sperm to bind to heterologous zonae pellucidae

Sperm are redox-regulated cells, and deregulation of their redox status is considered to affect male fertility and to reduce their fertilizing ability following biotechnological procedures, such as cryopreservation. Cystine (CysS), after incorporation in sperm via SLC7A11 antiporter, has been demonstrated to increase intracellular GSH content, the most important non enzymatic antioxidant. This study was aimed at investigating the role of SLC7A11 antiporter on frozen-thawed stallion sperm ability to respond to in vitro capacitating environment after post-thaw incubation with CysS and/or Sulfasalazine (SS), a specific inhibitor of SLC7A11 antiporter. Viability, motility, immunolocalization of tyrosine phosphorylated proteins and the ability to bind to heterologous zonae pellucidae were evaluated. Thawed sperm from seven stallions (2 ejaculates/stallion) was washed and resuspended in Tyrodes media; each thawed ejaculate was divided in Control (CTR) and 3 samples supplemented with: 0.5 mM Cystine (CysS), 500 μM Sulfasalazine (SS) and 0.5 mM CysS + 500 μM SS (CysS + SS). After 1 h of incubation at 37 °C, samples were washed twice, resuspended in capacitating BWW medium and incubated at 38 °C under 5% CO₂. After 30 and 60 min, sperm motility, viability and tyrosine phosphorylated protein immunolocalization, used as capacitation status index, were evaluated. After 30 min of capacitation, 4 × 10⁵ sperm were co-incubated with denuded pig oocytes in capacitation medium for 30 min for the heterologous binding assay. None of the sperm parameters studied (motility, viability and tyrosine phosphorylation) showed any difference respective to control. The number of sperm bound per oocyte (mean ± SEM) tended to increase in CysS group (44.0 ± 12.3) respect CTR (40.8 ± 10.8) while decreased in SS group (32.4 ± 7.8) (p < 0.01). Moreover, CysS + SS group showed a lower binding rate (32.0 ± 10.0) compared to CysS (p < 0.001). Our results suggest that CysS supplementation of thawed stallion sperm can influence their ability to bind to heterologous zona pellucidae as the inhibition of CysS incorporation by SLC7A11 reduced the number of sperm bound per oocyte. This effect does not seem to be ascribed to a modification of sperm motility, membrane integrity and tyrosine phosphorylation.

Efficiency of Tris-Based Extender Steridyl for Semen Cryopreservation in Stallions

Simple Summary

The cryopreservation and long-term storage of semen is one of the methods for accelerated improvement of the genetic qualities of animals. However, horse breeders prefer to use fresh or chilled semen, as the fertilizing capacity of frozen equine semen is much lower. It is important to find extenders, or a combination of extenders, that will improve semen survival after freezing. It is also important that the extender can be easily and simply prepared for use. Steridyl is a concentrate to which you just need to add sterilized water. This extender was developed for ruminants. In this study we tested Steridyl for freezing stallion semen. The motility, morphology, energy metabolism, DNA damage, and fertility of sperm frozen in Steridyl were evaluated. As a result, Steridyl was shown to be a good extender for equine semen freezing.

Abstract

The fertilizing ability of stallion sperm after freezing is lower than in other species. The search for the optimal extender, combination of extenders, and the freezing protocol is relevant. The aim of this study was to compare lactose-chelate-citrate-yolk (LCCY) extender, usually used in Russia, and Steridyl^® (Minitube) for freezing sperm of stallions. Steridyl is a concentrated extender medium for freezing ruminant semen. It already contains sterilized egg yolk. Semen was collected from nine stallions, aged from 7 to 12 years old. The total and progressive motility of sperm frozen in Steridyl was significantly higher than in semen frozen in LCCY. The number of spermatozoa with normal morphology in samples frozen in LCCY was 60.4 ± 1.72%, and with Steridyl, 72.4 ± 2.10% (p < 0.01). Semen frozen in Steridyl showed good stimulation of respiration by 2.4-DNP, which indicates that oxidative phosphorylation was retained after freezing–thawing. No differences among the extenders were seen with the DNA integrity of spermatozoa. Six out of ten (60%) mares were pregnant after artificial insemination (AI) by LCCY frozen semen, and 9/12 (75%) by Steridyl frozen semen. No differences among extenders were seen in pregnancy rate. In conclusion, Steridyl was proven to be a good diluent for freezing stallion semen, even though it was developed for ruminants.

The effect of crude guava leaf tannins on motility, viability, and intact plasma membrane of stored spermatozoa of Etawa crossbred goats

Aim

The aim of this study was to know crude guava leaf tannins effect on motility, viability, and intact plasma membrane of stored spermatozoa of Etawa crossbred goats.

Materials and Methods

Macroscopic assessment of normal Etawa crossbred semen was followed by dilution with a glucose solution at a 1:10 ratio to increase volume. The diluted semen was treated by adding crude guava leaf tannins into 1 ml of the semen glucose diluent, and five treatments were obtained, namely, control group (C), with no added tannins; treatment Group 1 (T1), with 3%; treatment Group 2 (T2), with 6% tannins; treatment Group 3 (T3), with 12% tannins; and treatment Group 4 (T4), with 24% tannins. Each treatment used five replications. Then, microscopic analysis of the treated and control semen was carried out after 15 days of storage at 4-5°C temperature. The parameters observed were motility, pH, viability, abnormality, and intact spermatozoa plasma membrane.

Results

The spermatozoa motility in Group C was the highest (76.60±1.47). The motility in Group T1 did not differ from that in Group C, but was different and higher than that in Groups T2, T3, and T4. The pH of Group C tended to be acidic after 15 days of storage (4.78±0.01) as compared to the initial pH of fresh semen (6.76±0.12). The pH in Group C did not differ from that in the Groups T1 and T2, but differed from that in the T3 and T4 groups; the pH in the T3 and T4 groups was similar. The viability of spermatozoa in the T1 group was higher than that in all treatments (64.60±2.76); the lowest values were found in Group C (28.94±1.02). Group C had the lowest number of normal spermatozoa, with a mean of 72.58±3.48. The total number of abnormalities in the T2 group did not differ from those in the T3 group, and abnormalities in the T4 group did not differ from those in Group C, which exhibited the highest abnormalities in the head, neck, and tail. The most significant decrease was observed in the intact plasma membrane of spermatozoa on addition of 12% and 24% crude guava leaf tannin in glucose diluents.

Conclusion

The addition of 3% crude guava leaf tannin to crossbred Etawa goat semen diluted with glucose diluent and stored for 15 days at 4-5°C resulted in a significant effect on spermatozoa motility, viability, and intact plasma membrane, whereas the administration of 24% crude guava leaf tannin resulted in low live percentage of spermatozoa.

Retrospective study of the reproductive performance of Barb and Thoroughbred stallions in Algeria

Background and Aim

The Barb horse occupies a prominent place in the history, culture, and equestrian traditions of the Maghreb (Algeria, Morocco, and Tunisia). Although many studies on the breed standard and morphometry have been published, there are no studies on its fertility and reproductive potential. Thus, this work aimed to study the fertility of Barb, Arabian Purebred, and Thoroughbred horses in Algeria.

Materials and Methods

A total of 168 stallions and 1202 mares at the Chaouchaoua Stud farm in Tiaret, Algeria, were included in the study. The reproductive performance during 1592 cycles over 10 consecutive mating seasons (2003-2012) was evaluated. Multivariate analysis with logistic regression was used to analyze the reproductive parameters such as the number of cycles operated, number of pregnant mares, pregnancy rate per cycle, seasonal pregnancy rate, and embryonic mortality rate, and to determine the influence of breed, stallion's age, and year of the study on reproduction.

Results

Statistical analysis showed that stallion breed was a significant influencing factor for the number of pregnant barren mares (Odds ratio [OR]=1.72; p=0.03; 95% confidence interval [CI]=1.05, 2.84) seasonal pregnancy rate (OR=1.40; p<0.001; 95% CI=1.29, 1.53). Additionally, the reproductive performance of the Barb stallion was superior to that of the Thoroughbred stallion. With regard to the significant influence of stallion's age of >5 years on the number of pregnant foaling mares and seasonal pregnancy rate, significant interactions were observed between the stallion's breed and age, and the pregnancy rate per cycle: in the Barb breed, the pregnancy rate per cycle increased with the age of the stallion, while in the Thoroughbred, it decreased with age. Moreover, a significant effect of the year of the study on the pregnancy rate per cycle and number of pregnant foaling mares was observed. In contrast, the number of cycles and embryonic mortality rate were not influenced by the breed and age of the stallion, or the year of the study.

Conclusion

The Algerian Barb horse attained a similar level of fertility compared with that of the Arabian Purebred and Thoroughbred stallions depending on its age and reproductive performance.