The protective effect of egg yolk from different avian species during the cryopreservation of Karayaka ram semen

A brief review of the methodology and cryoprotectants in selected fish and mammalian species

Cryopreservation is a valuable technique used to assist in the genetic improvement of cultured stocks and provide a continuous supply of good-quality semen for artificial insemination. Conserving semen by cryopreservation serves several purposes (e.g. artificial reproductive technologies and species conservation) and is also used in the clinical treatment of human infertility. However, the lifespan of cryopreserved semen is influenced by a range of factors, including storage temperature, cooling rate, chemical composition of the extender, the concentration of cryoprotectant, reactive oxygen species, seminal plasma composition and hygienic control. The choice of cryoprotectant is a vital factor underlying the success of animal semen cryopreservation. In this regard, extensive research has been carried out on various cryoprotectants, such as egg yolk, dimethyl sulfoxide, methanol, ethylene glycol and dimethylacetamide. Recent studies have also described the use of a range of new cryoprotectants for cryopreservation, including compounds of plant origin (soy), amino acids, antifreeze proteins, carbohydrates and cyclodextrins. Moreover, semen cryopreservation and storage require the use of liquid nitrogen or ultralow refrigeration methods for both long- and short-term storage. This review summarizes the general methods used for freezing semen and discusses the use of traditional and newly emerging cryoprotectants (permeable and non-permeable) for the cryopreservation of semen in selected fish and mammalian species.

Evaluation of the effect of melatonin implantation in rams and eCG dose in ewes synchronized by a CIDR-eCG protocol on reproductive performance of Lacaune sheep breed during non-breeding season

Sustainable production of milk is favorable in dairy sheep industry, which necessitates year-round reproduction of rams and ewes even during non-breeding season. Hence, protocols facilitating reproduction of rams and ewes during non-breeding season are of importance for this purpose. Therefore, the present study was conducted to investigate the effect of melatonin implantation in rams and administration of 400 IU eCG (E400) versus 300 IU eCG (E300) in ewes on reproductive performance of Lacaune sheep breed during non-breeding season. Rams were allocated to two groups including untreated (control, CON; n = 36) and melatonin-treated (MEL; n = 37). A subset of rams from CON (n = 7) and MEL (n = 7) groups were used for assessment of scrotal circumference, kinematic and functional characteristics of sperm, total antioxidant capacity (TAC) of semen and circulating testosterone on Days 0 (the beginning of study) and 60 (60 days after melatonin implantation). Further, the study had a 2 × 2 factorial design with four experimental groups including 1) ewes treated with E300 and introduced to CON rams (E300CON; n = 17 rams and 172 ewes), 2) ewes treated with E300 and introduced to MEL rams (E300MEL; n = 18 rams and 177 ewes), 3) ewes treated with E400 and introduced to CON rams (E400CON; n = 19 rams and 192 ewes), and ewes treated with E400 and introduced to MEL rams (E400MEL; n = 19 rams and 190 ewes). Melatonin implantation improved scrotal circumference, concentration, progressive motility, velocity, mitochondrial membrane potential and viability of sperm, TAC of semen, concentration of testosterone and fertility of rams (P < 0.05). Besides, E400 compared with E300 enhanced synchronization of estrus and fertility in ewes (P < 0.05). In conclusion, melatonin implantation promoted reproductive performance in Lacaune rams, and increase in dose of eCG improved reproductive performance in Lacaune ewes.

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.

Correlation between fatty acids levels in chicken, duck, goose, pigeon, quail and turkey egg yolks and post-thawed quality of ram semen

The comparison between adding egg yolks (EY) of chicken, duck, goose, pigeon, Japanese quail or turkey to the Tris glycerol extender on the quality of ram semen before freezing and post-thawing was evaluated. The correlation between fatty acids levels in egg yolks of different avian species and the post-thawed quality of ram semen was studied. The pooled ejaculates collected from five rams were extended with Tris EY glycerol extenders containing the EY of chicken, duck, goose, pigeon, quail or turkey and cryopreserved at -196°C. The straws were evaluated before freezing and post-thawing for sperm motility using a sperm cell analyser, vitality using a FluoVit kit and abnormality using a SpermBlue stain besides plasma-membrane and DNA integrities using a hypo-osmotic swelling test and a Halomax kit, respectively. The moisture, ash, protein and fatty acid (FA) contents of EY of chicken, duck, goose, pigeon, quail and turkey were analysed using a gas chromatograph. The chicken and quail EY extenders significantly improved the total progressive motility (32.05 ± 1.41 and 31.68 ± 1.43, respectively), vitality, plasma membrane and DNA integrities and abnormalities of post-thawing ram semen in comparison with other EY extenders. Pigeon EY had the lowest saturated fatty acids (SFAs) in comparison with the other types of EYs. The chicken and turkey EYs had the lowest percentage of (monounsaturated fatty acids) MUFAs in comparison with the other types of EYs. The highest percentage of polyunsaturated fatty acids (PUFAs) was observed in the turkey, pigeon and chicken EYs which were considered double or triple their percentage in duck and goose EYs, respectively. Significant positive correlations existed between SFAs levels and total motility, vitality, plasma membrane functionality and DNA integrity (0.77, 0.80, 0.67, 0.52, respectively). Significant negative correlations existed between gondoic EY levels and total motility, vitality, plasma membrane functionality and DNA integrity. In conclusion, the EYs of duck, goose, pigeon or turkey cannot substitute the chicken EY in ram semen extenders as they gave lower post-thawing quality. The quail EY can be used as a good replacer for chicken EY in the extender used for cryopreservation of ram semen. The EY composition of FAs can significantly affect the quality of ram semen post-thawing.

Implementation of a method for sperm cryopreservation in sceloporine lizards

Actual loss of lizard biodiversity continues, even with the implementation of conventional conservation programs. An approach including assisted reproductive techniques such as sperm cryopreservation may contribute to the management of endangered species. We developed a method for sperm cryopreservation in sceloporine lizards and compared the response among the studied species. Prior to the mating season, we obtained semen from adult males of Sceloporus aeneus (n = 21), Sceloporus grammicus (n = 20) and Sceloporus torquatus (n = 21) via pressure of the genital papilla. Volume and sperm concentration were measured before semen dilution in a Tris-egg yolk (TEY) medium to evaluate progressive motility, sperm viability, morphology, plasma membrane and acrosome integrity. Then, we cooled the remaining volumes to 5°C at a rate of 0.1°C per minute to incorporate glycerol (8% v/v) in two fractions. Immediately afterwards, we placed 40 μl of the mix on solid CO2 to form pellets and immersed them in liquid nitrogen for storage. We thawed the pellets at 29°C for 3 minutes and diluted them 1:1 (v/v) in TEY medium to assess sperm quality. We found a positive relationship between body weight and seminal volume in S. grammicus and S. torquatus and a negative correlation with sperm concentration in S. grammicus (P < 0.05). Moreover, we observed that the freezing-thawing process decreased sperm quality in the three species, mostly affecting motility and viability. However, S. torquatus and S. aeneus showed a higher sperm tolerance than S. grammicus.

Effects of adding mixed chicken and quail egg yolks to the cryodiluent on the quality of ram semen before and after cryopreservation

The effects of adding mixed chicken and Japanese quail egg yolks (EYs) to the cryodiluent on the quality of ram semen before freezing and post-thawing were evaluated. Additionally, the composition of chicken and quail egg EYs and their mixture were analyzed for results explanation. The semen was collected from rams (n = 5) and extended with cryodiluent containing the EY of chicken, quail or their mixture (1:1). The extended semen was chilled slowly to 5 °C within 2 h and equilibrated for 2 h, before frozen on the liquid nitrogen vapor and cryopreserved at -196 °C. The straws were evaluated before freezing and post-thawing for sperm motility, vitality and abnormality besides plasma-membrane and DNA integrities. The moisture, ash, protein, and fatty acid (FA) contents of chicken EY, quail EY and their mixture were analyzed. Sperm vitality, plasma membrane integrity and DNA integrity before freezing were significantly (P < 0.05) higher in quail EY than chicken EY and mixed EYs cryodiluent. The chicken EY extender significantly improved the vitality, plasma membrane and DNA integrities of post-thawed ram semen in comparison with quail EY or mixed EYs extenders. While, the post-thawing sperm abnormalities was lower (P ≤ 0.05) in quail EY than chicken EY and mixed EYs cryodiluent. The post-thawing sperm motion kinetics parameters were higher in quail EY than chicken EY and mixed EYs cryodiluent. The highest percentages of moisture, ash, saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were detected in quail EY had. While, the highest percentages of fat, protein and polyunsaturated fatty acids (PUFAs) were detected in chicken EY. In conclusion, using of chicken EY can improve total motility, vitality, plasma membrane integrity and DNA integrity of cryopreserved ram semen. While, using of quail EY can improve sperm abnormalities and kinetic motion parameters of cryopreserved ram semen. Mixing chicken and quail EYs added no value for post-thawing ram semen parameters.

A diluent containing coconut water, fructose, and chicken egg yolk increases rooster sperm quality at 5°C

Aim:

The present study was conducted to evaluate the quality of rooster sperm at 5°C after treatment with a diluent containing coconut water, fructose, and chicken egg yolk and stored the semen sample at 5°C.

Materials and Methods:

Ten semen samples from 10 healthy roosters were subjected to four different treatments. For the treatments, 0.2 ml fresh semen with a sperm concentration of 5.2×10⁹ cell/ml was mixed with T0 (no diluent), T1 (0.34 ml coconut water and 6 µl fructose), T2 (0.274 ml coconut water, 0.12 ml egg yolk, and 6 µl fructose), and T3 (0.34 ml egg yolk and 6 µl fructose) solutions. Each treated solution was stored at 5°C and evaluated both macroscopically and microscopically. Macroscopically, semen volume, pH, and sperm concentration were evaluated. The microscopic sperm characteristics examined included total motility (i.e., rapid, medium, or slow), progressive and non-progressive motility, viability, and spermatozoa abnormalities noted at different storage times. The results showed that spermatozoa motility was under 40%.

Results:

The results indicated that sperm viability significantly affected (p<0.05). The highest mean value of sperm viability on day 7 of storage was found after treatment with the T2 solution (46.100±0.5677%). Similarly, spermatozoa abnormalities were significantly lower after treatment with the T2 solution (6.680±1.702%).

Conclusion:

The addition of a diluent containing coconut water, egg yolk, and fructose helped in the better preservation spermatozoa motility, as well as viability for up to 7 days when the semen samples were stored at 5°C.

Ostrich egg yolk improves post thaw quality and in vivo fertility of Nili Ravi buffalo (Bubalus bubalis) bull spermatozoa

Egg yolk containing a higher ratio of phospholipids and cholesterol may have better cryoprotective effect to buffalo spermatozoa during cryopreservation. Our objectives were to ascertain the comparison of Ostrich and chicken egg yolk in semen extender on post thaw quality, motion dynamics and in vivo fertility of Nili Ravi buffalo (Bubalus bubalis) bull spermatozoa. Semen samples (n = 45) from five bulls were collected once a week for a period of nine weeks and diluted in Triladyl^® extender having different concentrations of Ostrich egg yolk (10%, 15%, 20%) and 20% chicken egg yolk as control at 37 °C. Diluted semen samples were frozen in 0.54 mL French straws with programmable freezer. Post thaw sperm progressive motility (%), morphology (%), average path velocity (μm/s), straight line velocity (μm/s), Linearity (%), straightness (%), length of straight line path (μm), plasma membrane integrity (%), acrosome membrane integrity (%), DNA integrity (%) and mitochondrial activity were higher (P < 0.05) in spermatozoa cryopreserved in extender containing 20% Ostrich egg yolk as compared to 20% chicken egg yolk and other groups. The fertility rates (67.61% vs 54.2%) were higher (P < 0.05) in buffaloes inseminated with semen doses frozen in extender containing 20% Ostrich egg yolk than the 20% chicken egg yolk. It is concluded that 20% Ostrich egg yolk in extender improves post thaw semen quality, motion dynamics and in vivo fertility in Nili Ravi buffaloes.

Does advanced age affect reproductive variables, semen composition, and liquid semen storage during different seasons in Boujaâd rams?

The present research was conducted to evaluate the effects of season and age on scrotal circumference (SC), semen characteristics, semen composition, and sperm motility during liquid storage in Boujaâd rams. Semen was collected throughout 1 year from April 2014 to March 2015. Two ram groups, namely older rams including animals aged 5.5 to 6 years of age, and younger rams including animals aged 2.5 to 3 years of age were used. Scrotal circumferences, semen characteristics, and some biochemical variables from semen were measured. After collection and evaluation, the semen was extended in skim milk (SM) at 15 °C to a concentration of 0.8 × 10⁹ spermatozoa/ml. Thereafter, samples were evaluated at different storage times (0, 8, and 24 h). The results indicate that older rams had greater values of SC, lesser semen quality, protein, lipid, and cholesterol concentrations than younger rams. Nevertheless, for both groups there were the least values for semen quality and semen composition in winter. The semen collected from younger rams had greater motility after liquid storage compared with that of the older rams. The least semen quality after liquid storage was recorded in the winter compared with the other seasons of the year for both age groups. In conclusion, results of the present study indicate that older Boujaâd sheep have lesser semen quality, different semen composition than younger rams after liquid storage and during different seasons of the year. Furthermore, there was a strong correlation between semen composition and motility of stored ram semen.

Effects of adding egg yolks of different avian species to Tris glycerol extender on the post-thawing quality of buck semen

The effects of adding egg yolks (EY) of different avian species to the Tris glycerol extender was evaluated for post-thawing quality of buck semen. The semen samples collected from seven Aardi bucks were pooled and diluted 1:4 with the Tris glycerol diluents containing the egg yolks of chicken (C), pigeon (P), goose (G), Japanese quail (Q), duck (D), or turkey (T). The diluted semen samples were gradually cooled to 5 °C within 2 h, equilibrated at 5 °C for 2 h, and then frozen in liquid nitrogen vapor for 8 min before storing them at -196 °C. The frozen straws were thawed at 37 °C for 30 s and evaluated for sperm motility, vitality, abnormality, plasma-membrane integrity, and DNA fragmentation. The malondialdehyde (MDA) and reduced glutathione (GSH) activities were measured. The egg yolk samples of the above-mentioned avian species (n = 7/species) were analyzed for moisture, ash, protein, fatty acid (FA), and trace element contents. The use of the chicken EY (C) diluent resulted in better post-thawing buck semen quality, including the total progressive sperm motility parameters, sperm vitality, plasma membrane intactness, DNA integrity, and sperm abnormalities percentages, in comparison with the EY diluents of the other avian species. The lowest MDA and the highest GSH activities were observed in the C diluent. The chicken EY had the highest percentages of margaric and linolenic FAs and the lowest percentages of palmitoleic and myristic FAs. Moreover, the percentage of oleic FA was lower in the chicken EY than in the EYs of other species, except turkey. Additionally, the chicken EY had the significantly lowest concentration of Cu, Zn, Fe, and Mn. In conclusion, the use of chicken egg yolk extender is recommended for buck semen cryopreservation. The egg yolks of the other avian species studied cannot substitute the chicken EY as they gave poorer post-thawing semen quality. The EY composition, especially FA profile and trace elements concentration, significantly affected the post-thawing quality of buck semen.

Evaluation of pigeon egg yolk for post thaw quality, enzyme leakage and fertility of buffalo (Bubalus bubalis) bull spermatozoa

Egg yolk is used as a cryoprotectant in semen preservation. However, its composition varies according to the species which may influence its effectiveness during the freeze-thaw process. Therefore, study was conducted to identify the optimum level of pigeon egg yolk (PEY) in Tris citric acid (TCA) extender for freezability and in vivo fertility of buffalo semen. Semen was collected at weekly intervals for a period of three weeks (replicates) from 6 Nili Ravi buffalo bulls (2 ejaculates/bull/replicate) and diluted with TCA extender (50 × 10⁶ motile spermatozoa ml^-1) containing 5%, 10%, 15% and 20% PEY or 20% CEY (control) and cryopreserved. Post-thaw sperm quality and extracellular enzymes leakage was assessed after thawing. Sperm motility, plasma membrane integrity, livability and viability was significantly higher in extenders containing 10% and 15% PEY compared to 5% PEY, 20% PEY or 20% CEY (controls). A dose-dependent decrease was recorded in the chromatin damage for the PEY, being lowest for the 15% and 20% PEY which was significantly less compared to controls (20% CEY). The extracellular GOT and LDH leakage was significantly lower (P < 0.05) in extender containing 10% and 15% PEY compared to the controls. Semen collected from 2 bulls, cryopreserved in extenders containing 15% PEY or 20% chicken egg yolk was assessed for fertility after artificial inseminations. A total of 400 buffaloes were inseminated (100 inseminations/extender/bull). The overall fertility rate was significantly higher (P < 0.05) with semen cryopreserved in extender containing 15% PEY (56%) compared to 20% CEY (42%; controls). In conclusion, pigeon egg yolk at 15% offers advantages over 20% chicken egg yolk in terms of in vitro post-thaw semen quality and in vivo fertility of buffalo.

Comparison of in vitro and in vivo fertilizing potential of buffalo bull semen frozen in egg yolk-, soya bean lecithin- and liposome-based extenders

The objective of this study was to compare different extenders for post-thaw in vitro sperm function and in vivo fertility of buffalo semen. Accordingly, sperm of 30 ejaculates extended in egg yolk (TRIS with 20% egg yolk; EY), two soya lecithin-based (SL-1; AndroMed® and SL-2; Bioxcell® ) and a liposome-based extender (LS; OptiXcell® ) were tested. The post-thaw semen was evaluated for computer-assisted sperm analysis (CASA), sperm viability, membrane and acrosome integrity, DNA integrity and acrosome reaction and first service pregnancy rate (FSPR) in a fixed-time artificial insemination programme. Total motility and VCL were the only CASA-based parameters that exhibited significantly higher (p < .05) percentage in LS among these extenders. Post-thaw percentage of acrosome integrity (55.9 ± 1.4, 58.1 ± 2.0, 55.8 ± 2.0, 56.6 ± 2.3) and DNA integrity (68.8 ± 2.0, 69.2 ± 2.3, 71.3 ± 2.1, 69.1 ± 2.1) did not differ (p > .05) in EY, SL-1, SL-2 and LS extender, respectively. However, a variable response in terms of efficacy of different extenders for sperm viability and plasma membrane integrity was observed. Assessment of inducibility of acrosome reaction showed significant differences between extenders (51.9 ± 2.1, 44.3 ± 2.4, 46.1 ± 2.3 and 58.1 ± 3.1%, respectively, for EY, SL-1, SL-2 and LS). Furthermore, field trials revealed significantly higher (p < .05) FSPR of LS-extended semen as compared to that for EY, SL-1 and SL-2 extender (46.3%, 41.2%, 31.2% and 29.7%, respectively). It is concluded that the liposome-based extender is more effective than egg yolk- and soya lecithin-based extenders and may be used for cryopreservation of buffalo semen in the future.

Supplementation of tris-based extender with plasma egg yolk of six avian species and camel skim milk for chilled preservation of dromedary camel semen

The present study was conducted to investigate a suitable source (Expt. 1) and concentration (Expt. 2) of plasma egg yolk (PEY) and concentration of camel skim milk (CSM; Expt. 3) to supplement tris based extender for chilled storage of dromedary camel semen. In Expt. 1, PEY (20%) of six avian species (domestic chicken, domestic duck, Japanese quail, partridge, pigeon and guinea fowl) was added to semen extender. In Expt. 2, different concentrations (0, 10, 20, 30 and 40%) of selected PEY from Expt.1 were added to semen extender. In both Expt. 1 and 2, CSM remained constant (20%). In Expt. 3, semen extender was supplemented with different concentrations of CSM (0, 20, 40, 60 and 80%) while the concentration of PEY remained constant. The sperm viability parameters were assessed at 6, 12 and 24h following chilled storage. In Expt. 1, progressive forward motility (PFM) of diluted semen supplemented with pigeon PEY was similar to domestic duck and Japanese quail PEYs (P>0.05) and superior to other PEYs (P<0.05). In Expt. 2, PFM following the addition of 20% pigeon PEY was similar to 10 and 30% (P>0.05) and greater than 0 and 40% (P<0.05). In Expt. 3, total motility, PFM and live percentage of sperm were better in 20% compared to 40, 60 and 80% CSM (P<0.05). In the last experiment, PFM in 20% was better than 0% CSM (P<0.05). In conclusion, pigeon PEY at the concentration of 20% and CSM at the concentration of 20% could provide beneficial effect on some of the sperm viability parameters during chilled storage of dromedary camel semen.

Effect of season on scrotal circumference, semen characteristics, seminal plasma composition and spermatozoa motility during liquid storage in INRA180 rams

The present study was undertaken to assess the effect of seasons on scrotal circumference, semen characteristics, seminal plasma composition, and sperm motility during liquid storage of INRA180 rams. The semen was collected from five mature INRA180 rams (2-3 years of age) during one year (from April 2014 to March 2015). Scrotal circumferences, semen characteristics, some biochemical parameters of seminal plasma were evaluated. Immediately after collection and evaluation, the semen was pooled and extended in skim milk (SM) at 15°C to reach 0.8×109 spermatozoa/ml. Thereafter, samples were evaluated at different storage times (0, 8, and 24h). The results showed that scrotal circumference, semen quality and the concentration of total protein in seminal plasma were relatively constant during the year (P>0.05). However, total lipid and cholesterol concentrations increased significantly (P<0.001) in winter and summer. The result showed also that progressive motility was higher in winter and summer after 24h of storage (P<0.01). In contrast, no difference was recorded regarding total motility (P>0.05). To conclude, the INRA180 rams have the ability to produce semen with high quality all over the year. The only parameters showing seasonal variations are cholesterol, total lipid, and progressive motility.

Effects of low-density lipoproteins extracted from different avian yolks on boar spermatozoa quality following freezing–thawing

Low-density lipoproteins (LDL) is known to protect boar sperm during freezing–thawing, but little information is known about the effects of LDL extracted from different avian egg yolks on post-thaw boar semen quality. The purpose of this study was to compare and analyze the effects of LDL at various concentrations and different species on boar sperm quality after freezing–thawing. LDL extracted from the yolk of hen egg, duck egg, quail egg, pigeon egg or ostrich egg was added to the extender at the concentrations of 0.06, 0.07, 0.08, 0.09 and 0.1 g/ml, respectively, and their effects on frozen–thawed boar sperm quality were assessed. According to all measured parameters, the results showed that sperm motility, acrosome integrity and plasma membrane integrity were 43.20%, 52.57% and 48.13%, respectively, after being frozen–thawed with 0.09 g/ml LDL extracted from pigeon egg yolk. All these quality parameters were higher than that of other groups (P < 0.05). In conclusion, our results confirmed that LDL extracted from pigeon egg yolk had the best cryoprotective effects on frozen–thawed boar sperm among all of the groups supplemented with LDL from five kinds of avian egg in extender. The optimum concentration of LDL extracted from pigeon egg in boar semen freezing extender was 0.09 g/ml.