Fertility and flow cytometry study of frozen-thawed sperm in cryopreservation medium supplemented with soybean lecithin

Association between different soy lecithin-based extenders and freezing rates in ram semen cryopreservation

The aim of the study was to evaluate the effect of the association between glycine-milk (GM) based extenders made with different concentrations of soy lecithin (SL) and freezing rates (FR) on semen quality after thawing. Pooled semen from rams (n = 12) were diluted in GM extenders with 20% egg yolk (EY-20%) or with different concentrations of SL: 0.5% (SL-0.5%), 1.0% (SL-1.0%), and 2.0% (SL-2.0%). The diluted semen (150 ×10⁶ spermatozoa/0.25 mL) was frozen at three FR of - 10, - 20, and - 60 °C/min, and subsequently thawed and analyzed. Results revealed that EY-20% and SL-2.0% had better kinetic parameters, and showed higher proportions of viable, non-apoptotic, plasma-membrane-intact spermatozoa (A^-/PI^-) and non-capacitated spermatozoa (F), and had lower acrosome-reacted spermatozoa (AR) in the EY-20% and satisfactory values for SL-2.0% compared to SL-0.5% and SL-1.0% (P < 0.05). The FR at - 20 and - 60 °C/min maintained higher A^-/PI^- and viable spermatozoa compared to - 10 °C/min. The combination EY-20% and - 60 °C/min showed the highest A^-/PI^- and F (P < 0.05) and the lowest AR, and it did not differ from the combinations EY-20% at - 20 °C/min and SL-2.0% at - 20 °C/min (P > 0.05). In conclusion, the combination EY-20% and - 60 °C/min, showed the best cryoprotective effects on ram spermatozoa. Changes in spermatozoa after thawing were related to the use of the type of extender, the amounts of the same compound in the extender, and the freezing rates to which they were subjected.

Fertility results after exocervical insemination using goat semen cryopreserved with extenders based on egg yolk, skim milk, or soybean lecithin

To evaluate the effects of four extenders on the post-thaw quality and fertility of goat semen, six Yunshang Black bucks' semen was collected, pooled, diluted with Andromed® (Andr®), Optidyl® (Opt®), P3644 Sigma l-phosphatidylcholine (l-α SL), and skim milk-based (Milk) extenders, and then cryopreserved. The sperm motilities, abnormalities, membrane and acrosome integrity, mitochondrial activity, apoptosis, and reactive oxygen species (ROS) production were evaluated after thawing. After exocervical insemination with the thawed semen, the pregnancy, lambing, and twinning rates were recorded and compared. The results showed that sperm motilities, membrane integrity, acrosome integrity, mitochondrial activity, and viable spermatozoa were significantly higher in the Andr® and Opt® groups than those in the l-α SL and Milk groups (p < .05). Furthermore, there was no difference between Andr® and Opt® (p > .05). The sperm abnormality was lower in semen frozen with the Andr® or Opt® extenders, as compared to the l-α SL or Milk extender (p < .05). Regarding, the viable cells with low ROS production, the optimal results were obtained in the semen frozen with Andr® and Opt® extenders. Following exocervical insemination, the pregnancy and lambing rates in the Milk group were significantly lower than those in the other groups (p < .05). No difference was found in the pregnancy and lambing rates between Andr®, Opt®, and l-α SL (p > .05). Furthermore, the twinning rates were similar between these four groups (p > .05). In conclusion, egg yolk or skim milk can be substituted by soybean lecithin during cryopreservation of goat semen.

Cryopreservation of Semen in Domestic Animals: A Review of Current Challenges, Applications, and Prospective Strategies

Cryopreservation is a way to preserve germplasm with applications in agriculture, biotechnology, and conservation of endangered animals. Cryopreservation has been available for over a century, yet, using current methods, only around 50% of spermatozoa retain their viability after cryopreservation. This loss is associated with damage to different sperm components including the plasma membrane, nucleus, mitochondria, proteins, mRNAs, and microRNAs. To mitigate this damage, conventional strategies use chemical additives that include classical cryoprotectants such as glycerol, as well as antioxidants, fatty acids, sugars, amino acids, and membrane stabilizers. However, clearly current protocols do not prevent all damage. This may be due to the imperfect function of antioxidants and the probable conversion of media components to more toxic forms during cryopreservation.

Hydroxytyrosol and resveratrol improves kinetic and flow cytometric parameters of cryopreserved bull semen with low cryotolerance

There is considerable interest in breeding programs to "rescue" semen with poor post-thaw fertility from bulls known as "bad freezers". We hypothesized that there may be an interaction between the post-thaw recovery of sperm and the efficacy of antioxidant addition to extenders. The current study assesses the effects of antioxidant additives hydroxytyrosol (HT) and resveratrol (RSV) on the post-thaw semen parameters in two groups of bulls classified as either high or low cryotolerant (i.e., "good" and "bad" freezers). Semen samples were collected from 40 bulls and processed in the extenders containing different concentrations of HT (experiment 1; 0, 25 and 50 µM) and RSV (experiment 2; 0.0, 0.01, 0.1 and 1 mM). In experiment 1, bulls in the low cryotolerance group had a significant improvement in post-thaw recovery at 25 µM and 50 µM (P < 0.05). These improvements were observed in motility and several cellular parameters. However, post-thaw semen quality in the high cryotolerance group was not significantly affected by the HT addition. In experiment 2, although RSV did not have any positive impact in high cryotolerance group, post-thaw recovery in the low cryotolerance bulls was significantly improved in 0.1 mM RSV. Oxidative stress markers in either high or low cryotolerance groups were not significantly changed by RSV addition (P > 0.05). It can be concluded that addition of optimized concentrations of HT and RSV to the extender could be a strategy for improving the post-thaw semen, especially in bulls with high genetic merit but low initial cryotolerance.

Effect of fortification of extender with α-terpineol and rosemary essential oil on post-thaw ovine semsen quality

The goal of the present study was to assess the viability of the cryopreserved ovine (Ovis aries) semen, upon supplementation with α-terpineol and rosemary essential oil (Rosmarinus officinalis). The collection of the semen from six rams formed the pool, collected once a week during 7 weeks. The diluted semen was packed into straws (0.25 ml) and frozen in a TK 3000® device. Both α-terpineol and rosemary essential oil were added in the concentrations of 6.25, 12.5 and 25 μg/ml to the TRIS-yolk extender forming six experimental groups; the control group received only the TRIS-yolk extender. The samples were analyzed after thawing regarding motility and vigor, integrity of the plasmatic membrane, thermoresistance test (TT), mitochondrial membrane potential, acrosomal integrity and computer-assisted semen analysis (CASA). The levels of the thiobarbituric acid reactive substances were also analyzed. According to the results obtained with the addition of the concentrations of 6.25, 12.5 and 25 μg/ml of α-terpineol, significantly reduced the parameters assessed through CASA (VSL, LIN and WOB) and TT. Rosemary essential oil did not have deleterious effects on the spermatozoa and did not reduce the oxidative stress in the concentrations studied, although it presented absolute values higher than those of the control in several parameters. Alpha-terpineol in the concentrations studied was not able to reduce the oxidative stress and had toxic effect over the ovine spermatozoa.

Effect of glycerol concentration, glycerol removal method, and straw type on the quality and fertility of frozen chicken semen

The long-term semen cryopreservation is increasingly crucial for conservation of endangered livestock and poultry species. Glycerol is the most widely used cryoprotectant for freezing chicken semen. Continuous improvement in details with glycerol may help increase the fertility of post-thawed semen. Two experiments were performed in the present study to investigate the effects of glycerol concentration, removal method, and straw type on the quality of post-thawed sperm. In experiment 1, glycerol concentration (3%, 5%, 7%, 9%, 11%, and 13%) and glycerol removal method (final dilution ratio 1:1, 1:2, 1:4, 1:8, 1:16, and 1:20) combination groups were investigated for post-thawed sperm quality, residual glycerol concentration, and fertility to find the best combinations. Experiment 2 was performed to evaluate the effects of straw type (0.25 and 0.5 mL) and glycerol concentration (3%, 5%, 7%, 9%, 11%, and 13%) on the post-thawed sperm quality. Results showed that post-thawed sperm motility of 6 glycerol concentration groups were different (P < 0.01). Sperm motility of 5%, 7%, 9%, 11% and 13% was higher than that of 3% (P < 0.01). There was no difference among different concentrations of glycerol in VSL, VCL, VAP, ALH, WOB, BCF, LIN, or STR (P > 0.05). As for the glycerol removal method, sperm motility of 1:8 dilution was the highest, followed by 1:1 and 1:2, while the difference among groups was not statistically significant (P = 0.11). Glycerol concentration and removal method had no interaction effect on sperm motion parameters (P > 0.05). The highest fertility (48.70%) was found for the 5% and 1:2 combination. There was no difference for sperm motility between 0.25 and 0.5 mL straws (P > 0.05). Glycerol concentration and straw type had no interaction effect on the sperm motion parameters (P > 0.05). It can be concluded from these observations that the combination of 5% glycerol and 1:2 dilution rendered higher fertility should be suggested in practice, and that both 0.25 and 0.50 mL straws fit the present procedure.

The Cryopreserved Sperm Traits of Various Ram Breeds: Towards Biodiversity Conservation

The aim of our research was to compare three Slovak sheep breeds in the quality parameters of cryopreserved sperm. The ejaculates of Slovak Dairy (SD), Native Wallachian (NW), and Improved Wallachian (IW) sheep rams (n = 12) were collected by electro-ejaculation. Heterospermic samples were created from suitable ejaculates, separately for each breed (at least 90% of total and 80% of progressive motility). Samples were equilibrated in a Triladyl® diluent and frozen by automated freezing. Sperm samples were subjected to the motility, morphology, (CASA), viability and apoptosis (DRAQ7/Yo-Pro-1), fertilizing capability (penetration/fertilization test (P/F) in vitro) and acrosomal status (transmission electron microscopy) assays before freezing and after thawing. It was found that there were no significant differences (p < 0.05) between the evaluated breeds in motility, viability, apoptosis, morphological properties, and fertilizing ability of cryopreserved sperm. Significant differences occurred in acrosomal status. Our results demonstrate that the use of the selected cryopreservation protocol is suitable for at least three different sheep breeds, which can greatly benefit the biodiversity protection and simplifies the creation of an animal genetic resources gene bank.

Spermatozoa Survival in Egg Yolk-Based and Soybean-Based Extenders at Ambient and Chilling Temperature in Domestic Turkeys (Meleagris gallopavo)

Populations of many galliform species have declined mainly due to habitat loss and over-hunting, notably the Congo peacock, which has been classified as a vulnerable species by the International Union for Conservation of Nature (IUCN). The domestic turkey, being a species of least concern, which has been reported to be closely related to peacocks, could serve as a model for the optimization of assisted reproductive technologies for the Congo peacock. This study was aimed at developing a suitable turkey semen extender for artificial insemination in field conditions. Semen was collected using the dorso-abdominal massage technique from seven turkey toms and analyzed. Ejaculates with >70% motility and >80% live spermatozoa were pooled and divided into four aliquots (four treatments). Each of the four treatments was extended in a soybean-based extender or an egg yolk-based extender, with or without L-ascorbic acid. Two liquid preservation protocols (ambient temperature (35 °C) and chilled (4 °C)) were employed, and quality parameters including motility, viability and morphology were evaluated. The results show that the two extenders were similar with regard to semen quality parameters, and L-ascorbic acid supplementation of the turkey semen extenders improved semen quality during liquid storage.

Use of melatonin in sperm cryopreservation of farm animals: A brief review

Melatonin (MT) is a potent antioxidant with useful applications in several fields. Due to the capacity to scavenge free radicals and enhance cellular endogenous antioxidant defenses, MT is widely used in sperm cryopreservation to protect against oxidative stress-induced damage in frozen-thawed sperm. In this article, there is a review of positive effects of MT supplementation in cryopreservation of sperm from domestic ruminants and swine. There is direct or indirect scavenging of free radicals, preventing lipid peroxidation (LPO), and reducing oxidative stress, therefore, protecting membrane and DNA integrity, enhancing post-thaw antioxidant and enzymatic functions to maintain mitochondrial functions and activity, and regulating ATP production and utilization leading to maintenance of sperm quality, motility, and viability. In addition, MT reportedly inhibits sperm apoptosis, potentially by enhancing sperm viability and modulating abundances of mRNA transcripts.

Effects of Three Semen Extenders, Breeding Season Month and Freezing-Thawing Cycle on Spermatozoa Preservation of Portuguese Merino Sheep

Simple Summary

Spermatozoa (SPZ) viability, morphology and the kinetics of fresh and thawing Portuguese Merino Semen were evaluated at different breeding season months using an owner egg yolk-based semen extender (S-EXT) and two commercial lecithin-based semen extenders. The main significant differences between S-EXT were observed for thawed semen. The viability (30% vs. 15% of alive SPZ; p < 0.001), total motility (74% vs. 34%; p < 0.001), total progressive motility (18% vs. 5%; p < 0.001), straight line velocity (37 vs. 22 μm/s; p < 0.001) and beat cross frequency (13 vs. 6 Hz; p < 0.05) were higher in the owner egg yolk than in egg yolk-free-based S-EXT. Significant interactions between S-EXT, semen processing and/or months of semen collection were observed on several of the 22 evaluated SPZ parameters and should be elucidated in further studies. The egg yolk-based S-EXT was more consistent across the months in cryopreserving SPZ than commercial egg yolk- free-based S-EXT and still seems, to the present day, the most appropriate S-EXT to be used in (Merino) sheep.

Abstract

This study aimed to evaluate and compare the effect of three semen extenders (S-EXT) on 22 spermatozoa (SPZ) parameters (subjective and computer-assisted sperm analysis evaluations), before and after semen cryopreservation throughout different months of the breeding season in the Portuguese Merino breed. According to the multivariable model, the SPZ viability (alive %), kinetics subjective individual motility, total motility, total progressive motility and its subpopulations, and beat cross frequency) were higher in the egg yolk-based S-EXT improved by Estação Zootécnica National (Portugal) than in Ovixcell^® or Andromed^® extenders. All the differences were only observed in thawed semen, except for total motility and total progressive motility, in which Ovixcell^® also showed the poorest results on fresh semen. An interaction effect between S-EXT and semen processing was observed on 72.3% (17/22) of the evaluated parameters, evidencing a variable cryoprotective action between S-EXT. The SPZ viability was poorer in the onset of the breeding season (end of April/early May) than in the previous middle breeding season (November/early December), suggesting the influence of a short anoestrous season on ejaculate quality, even though the volume and SPZ concentration of the ejaculates remained stable throughout the experiment. Additionally, S-EXT x semen processing x month interaction effect on 59.1% (13/22) of the evaluated parameters evidenced the importance of SPZ time collection in a natural environment to cryopreserve ram’s semen. We concluded that, overall, the egg yolk-based S-EXT provided a greater value to the cryopreservation of Merino rams´ semen. Nevertheless, the causes of the interaction effect between S-EXT, semen processing and/or month on several SPZ parameters should be addressed, including SPZ molecular research in new studies, in order to improve egg yolk-based as well as in egg yolk-free-based S-EXT.

Factors affecting rabbit sperm cryopreservation: a mini-review

Rabbits are an important animal species for meeting the nutritional requirements of the world's growing population due to the high conversion rate of feed. In most countries, the rabbit industry currently relies on artificial insemination with fresh or chilled and frozen-thawed spermatozoa. Various factors during the freezing process, including diluents, sperm preparation and freezing techniques, antioxidants, sudden temperature changes, ice formation and osmotic stress, have been proposed as reasons for the poor sperm quality post thaw. Despite the extensive progress reached in the field of rabbit sperm cryopreservation, new methodological approaches that could overcome problems in sperm cryopreservation are necessary. The aim of this review was to describe the factors that affect the cryopreservation of rabbit sperm.

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.

Peroxisome proliferator-activated receptors (PPARs) as a mediator of dietary fatty acids affects reproductive performance in broiler breeder roosters

This study analyzed the effects of dietary sources of omega-3 and omega-6 fatty acids on semen parameters and fertility potential in broiler breeder roosters. The mRNA and protein profiles of peroxisome proliferator-activated receptors-γ (PPAR-γ) expression in sperm as potential mediator of FAs were considered. Roosters were categorized into three groups and received their diets for 24 weeks as follows: 1) control diet received a basal diet (CTRL); 2) Fish oil based diet (FO) received the basal diet supplemented with 15 g/kg of diet fish oil; and 3) sunflower oil based diet (SO) received the basal diet supplemented with 15 g/kg of diet sunflower oil. While the different diets had significant effects on semen parameters, the effect of sampling time was not significant. The effect of the diets on sperm parameters were significantly higher in the SO and FO groups in total motility, progressive motility, amplitude of lateral head displacement, linearity, straightness, wobble and viability (P ≤ 0.05). Fertility rate was significantly improved in the FO and SO groups (P = 0001). The highest value for PPAR-γ mRNA was observed in the SO group compared to other groups (P ≤ 0.05). Moreover, supplementation of the roosters' diets with FO and SO increased PPAR-γ protein expression compared to the control. It seems that PPAR-γ could be a strong potential mediator of the underlying mechanism of improvement in semen parameters and reproductive performance of roosters under the effects of both dietary omega-3 and omega-6 polyunsaturated fatty acids.

Topical application of cervix with hyaluronan improves fertility in goats inseminated with frozen-thawed semen

Objective

Artificial insemination plays an important role in genetic improvement in the goat farming system. The aim of this study was to investigate the effect of cervical application of hyaluronan (HA) on the fertility in goats after cervical artificial insemination using frozen-thawed (F-T) semen.

Methods

After oestrous synchronisation with progesterone sponges and pregnant mare serum gonadotropin injection, both nulli- and multi-parous goats, were randomly allocated to 2 groups, and were inseminated with 0.25 mL of F-T semen (150×10⁶ spermatozoa) twice at 52 h and 56 h after sponge removal. Prior to the insemination, goats in Group 1 only were given topical cervical HA application at 48 h after sponge removal. Site of insemination was recorded as os-cervix or intra-cervix or intra-uterus. Pregnancy was tested ultrasonographically 42 days after insemination. The data on pregnancy rates and percentage of animals according to the site of semen deposition were compared by Chi-square analysis.

Results

The overall pregnancy rate was significantly (p<0.004) higher in goats with prior application to the cervix with HA (63.3%) than without (36.0%). Same pattern was observed in the pregnancy rates of nulli- and multi-parous goats in both the groups. Percentage of nulliparous goats according to the site of insemination in the HA group did not differ between first and the second insemination. However, in multiparous goats the percentage of animals inseminated intra-cervically was significantly increased (p≤0.05) between the first and the second inseminations.

Conclusion

The results suggest that significantly higher fertility rate in the “HA goats” compared to the “without HA” group was because of deeper insemination facilitated by topical cervical application of HA. The deeper insemination into the cervical canal increase the rate of fertilisation when the cervical artificial insemination is performed.

Ram semen preserved at 0°C with soybean lecithin Tris-based extender substituted for egg yolk

OBJECTIVE

The present study evaluated the preservation of ram semen at 0°C using soybean lecithin with a Tris-fructose extender.

METHODS

Semen was collected by artificial vagina ejaculation from six rams with proven fertility. High quality ejaculates were diluted by soybean lecithin (0.25%, 0.5%, 0.75%, 1.0%, 1.25%) using Tris-fructose extender and control (Tris-fructose egg yolk extender), respectively. The ejaculates were diluted to a concentration of 5×108 sperm/mL, followed by cooling to 0°C in 90 min and maintaining the temperature for 12 days. The diluted semen samples were examined and recorded for sperm progressive motility, acrosome integrity at 0, 24, 72, 144, 216, 288 h, respectively. Two hundred and twenty-three ewes were inseminated for 216 h with optimal soybean lecithin concentrated semen or control via trans-cervical insemination.

RESULTS

The results showed that there were no differences in sperm progressive motility at 0, 24, 72, and 144 h (p>0.05). After 216 h, the sperm progressive motility in the control group and 0.5% concentration groups was significantly higher when compared to 0.25% concentration (p<0.05). The 0.5% concentration group demonstrated the highest survival rate and had no difference with the control group (p>0.05). At 216 h, the sperm progressive motility of all groups was still above 50%. The acrosome integrity of all groups was decreased with prolongation of storage time, but there was no difference at each time point (p>0.05). There was no significant difference in the lambing rate and pregnancy rate between the 0.5% concentration group and the control group (p>0.05).

CONCLUSION

These results suggest that ram sperm is capable of fertilization after preservation at 0°C with 0.5% of soybean lecithin in Tris-based extender substituted for egg yolk and produce normal offspring after insemination.

Cryoprotective activity of phosphorus-containing phenol

The antioxidant and cryoprotective efficiencies of a 3,5-di-tert-butyl-4-hydroxyphenyl)methylenediphosphonic acid (MDPA) differ significantly for sperm cells of various species of sturgeon fish (Russian sturgeon, beluga and Stellate sturgeon). The ability of phosphorus-containing phenol MDPA to decrease the level of lipid peroxidation of sperm, beneficial effect on the activity indicators of the sperm of native sturgeon and of the defrosted one after deep freezing as well as on the fertility of sperm cells was shown.

Effect of substituting different concentrations of soybean lecithin and egg yolk in tris-based extender on goat semen cryopreservation

This study aimed to investigate the effects of different concentrations of soybean lecithin (SL; 0.5%, 1%, and 1.5%) and egg yolk (EY) in Tris-based extenders on the semen quality parameters of post-thawed goat semen. Sixteen ejaculates were collected from eight healthy, mature Chongming White goats (3-5 years of age). Each ejaculate was divided into five equal aliquots, and then each pellet was diluted with one of the five Tris-based extenders containing 20% EY, 0.5% SL, 1% SL, 2% SL, or 3% SL. The cooled diluted semen was loaded into 0.5 mL polyvinyl French straws and cryopreserved in liquid nitrogen. Frozen semen samples were thawed at 37 °C and assessed for sperm motility, viability, plasma acrosome integrity, membrane integrity, and mitochondria integrity, and the spermatozoa were assessed for reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA). The semen extended in the 2.0% SL extract tended to have a higher sperm viability (57.44%), motility (52.14%), membrane integrity (45.31%), acrosome integrity (52.96%), and mitochondrial activity (50.21%) than the other SL-based extender concentrations (P < 0.05). The 2.0% SL treatment group was equivalent to the semen extended in 20% EY (P > 0.05). The extenders supplemented 20% EY or 2.0% SL significantly increased the SOD activity and decreased the ROS and MDA activities compared to the other groups (P < 0.05). In conclusion, the extenders supplemented with 20% EY and 2.0% SL had similar effects on spermatozoa preservation. These results indicate that a soybean lecithin-based diluent may be used as an alternative extender to egg yolk for the cryopreservation of goat semen.

Effects of egg yolk and soybean lecithin on sperm quality determined by computer-assisted sperm analysis and confocal laser scanning microscope in chilled canine sperm

The reduction of spermatozoa survival time is a major problem of canine chilled sperm for artificial insemination. The aim of the study was to improve the quality of canine chilled sperm during storage time. We therefore, evaluated the effects of eight treatments with different levels of soybean lecithin concentration (1, 3 and 5%) and egg yolk (20%) in Tris-citric-fructose or Tris-citric-fructose-mineral salts extender on chilled canine sperm quality during 10 days of storage. The sperm motility was analysed by computer-assisted sperm analysis (CASA), whereas plasma membrane integrity, acrosome membrane integrity and mitochondrial membrane potential parameters were determined using a fluorescent staining combination of propidium iodide (PI), Hoechst 33342 (H342), fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1) by confocal laser scanning microscope. The results showed that egg yolk was found to be better than soybean lecithin in Tris-citric-fructose or Tris-citric-fructose-mineral salts extender for maintaining the quality of chilled canine sperm within 10 days of storage (P < 0.05). Although egg yolk in Tris-citric-fructose extender could maintain the motility better than other extenders, egg yolk in Tris-citric-fructose-mineral salts extender was the highest in intact plasma membrane, intact acrosome membrane and high mitochondrial membrane potential (P < 0.05). In contrast, the sperm quality of soybean lecithin in Tris-citric-fructose-mineral salts extender was lower than that of soybean lecithin in Tris-citric-fructose extender, and soybean lecithin 1% was greater than soybean lecithin 3% and 5% in plasma membrane integrity, acrosome membrane integrity and mitochondrial membrane potential (P < 0.05). In conclusion, soybean lecithin cannot replace egg yolk in Tris-citric-fructose or Tris-citric-fructose-mineral salts extenders, and egg yolk in Tris-citric-fructose-mineral salts extender is superior to other extenders in chilling canine sperm.

Dietary supplementation with flaxseed oil as source of Omega-3 fatty acids improves seminal quality and reproductive performance in aged broiler breeder roosters

Reproductive performance in aged broiler breeder roosters is not desirable. The purpose of this study was to assess the effects of dietary flaxseed oil and vitamin E on the semen parameters, hormonal profiles, fatty acid analysis of sperm, and fertility performance of aged roosters. Twenty four roosters were assigned into four treatments and received their diets as following: 1) basal diet as control group (CTRL), 2) basal diet supplemented with 200 mg/kg vitamin E (CTRL + VITE), 3) basal diet supplemented with 2% flaxseed oil (FLAX) and 4) basal diet supplemented with 2% flaxseed oil plus 200 mg/kg vitamin E (FLAX + VITE). Roosters were fed their diets for 60 days and then, different characteristics of reproduction in the roosters were examined during experiment. Different diets affected semen parameters (P ≤ 0.05) except semen volume and morphology. Various characteristics of semen were significant (P ≤ 0.05) during different times of experiment excluding the total motility, membrane integrity and morphology. The higher percentage of sperm concentration, total motility, progressive motility, viability and membrane integrity accorded with a lower lipid peroxidation were observed in the roosters fed diet of FLAX + VITE (P ≤ 0.05). A higher concentration of testosterone was detected in roosters fed FALX + VITE at day 60 (P ≤ 0.05). Moreover, the percentage docosapantaenoic acid (DPA), docosahexaenoic acid (DHA) of sperm were increased in the diet of FLAX (P ≤ 0.05). Finally, rate of fertility after artificial insemination was significantly higher in the diet of FLAX + VITE. It seems that supplementation of aged roosters' diet with flaxseed oil and VITE improves the semen performance and fertility potential that can be a suitable strategy to preserve the reproductive performance of aged rooters.

Sperm quality characteristics and fertilization capacity after cryopreservation of rooster semen in extender exposed to a magnetic field

There has not been as much success in the effectiveness of avian semen cryopreservation as that of mammalian semen cryopreservation. This has been attributed to the unique characteristics of poultry sperm. In the area of mammalian semen, the use of magnetized extenders has enhanced the cryo-resistance of sperm in some species. The applicability of this strategy to avian semen has not yet been evaluated. The purpose of this study was to evaluate the effects on sperm quality and fertility after magnetization of extenders and use of these extenders for cryopreservation of rooster semen. Extenders were passed between two neodymium magnets that produced different magnetic induction values (0, 2000, 4000 and 6000 G). Physicochemical properties of the extenders were assessed and then semen samples were cryopreserved in the magnetized extenders. The smallest cluster sizes and zeta potentials in the extenders were observed in the extender magnetized at 2000 gauss (G). There were greater percentages of sperm total motility, viability and mitochondrial membrane potential in semen treated with the extender magnetized at 2000 G A greater percentage of sperm with enhanced membrane functionality was observed when sperm were stored in extenders magnetized with 2000 G and 4000 G. In a field trial, there were greater percentages of fertility and hatching rates of eggs using semen treated with extenders magnetized at 2000 G and 4000 G. Cryopreservation of rooster semen with magnetized extenders at 2000-4000 G resulted in enhanced quality indices of thawed sperm as well as the fertility capacity of the cryopreserved semen.

Sperm cryopreservation: A review on current molecular cryobiology and advanced approaches

The cryopreservation of spermatozoa was introduced in the 1960s as a route to fertility preservation. Despite the extensive progress that has been made in this field, the biological and biochemical mechanisms involved in cryopreservation have not been thoroughly elucidated to date. Various factors during the freezing process, including sudden temperature changes, ice formation and osmotic stress, have been proposed as reasons for poor sperm quality post-thaw. Little is known regarding the new aspects of sperm cryobiology, such as epigenetic and proteomic modulation of sperm and trans-generational effects of sperm freezing. This article reviews recent reports on molecular and cellular modifications of spermatozoa during cryopreservation in order to collate the existing understanding in this field. The aim is to discuss current freezing techniques and novel strategies that have been developed for sperm protection against cryo-damage, as well as evaluating the probable effects of sperm freezing on offspring health.

Effect of egg yolk plasma and soybean lecithin on rooster frozen-thawed sperm quality and fertility

This experiment was conducted to study the effects of egg yolk plasma (10%, 15% and 20%), soybean lecithin (0.5%, 1% and 1.5%) and whole egg yolk (WEY) (control) on post-thawed sperm quality, hatchability and fertility outcomes. In experiment 1, sperm motility, abnormalities, membrane integrity, viability, apoptosis status, mitochondrial activity were studied following freeze-thawing. The best quality of frozen-thawed rooster sperm was chosen to be used for the assessment of the hatchability and fertility rate in experiment 2. The significantly higher percentages of post-thawing sperm total and progressive sperm motilities, membrane integrity, viability were observed in 1% soybean lecithin and 20% egg yolk plasma in comparison with 0.5 and 1% soybean lecithin, 10% egg yolk plasma and control, except for 15% egg yolk plasma (P < 0.05). Using 20% egg yolk plasma in the extender improved mitochondrial activity. Supplementation of 1% soybean lecithin and 20% egg yolk plasma into the extender resulted in the least percentages of dead sperm (P < 0.05). Sperm abnormalities and early apoptosis did not differ in various extender supplementations. In experiment 2, higher percentages of hatchability and fertility rate were observed in semen containing 1% soybean lecithin and 20% egg yolk plasma compared with the WEY group. The results showed that supplementation of the rooster sperm extender with 1% soybean lecithin and 20% egg yolk plasma resulted in higher quality of frozen-thawed sperm.