In vitro evaluation of liquid-stored buffalo semen at 5°C diluted in soya lecithin based extender (Bioxcell®), tris-citric egg yolk, skim milk and egg yolk-citrate extenders

Effect of modified CEP-3 diluents with aqueous soybean extract on liquid semen quality in Ongole crossbred bull

Background and Aim

Egg yolk (EY) is commonly used as an extracellular cryoprotectant in semen diluents but has some negative effects. Therefore, this study aimed to assess the potential of lecithin derived from plants, such as soybeans, as an alternative extracellular cryoprotectant and to characterize liquid semen quality of Ongole crossbred bulls using a modified caudal epididymis plasma-3 [CEP-3 (m)] as a base diluent and aqueous soybean extract (ASE).

Materials and Methods

A bull with progressive motility (PM) of fresh semen >70% was used. Two soybean extracts were also used, namely, ASE 1 and ASE 2, obtained by extraction procedures 1 and 2, respectively. The study was conducted using an experimental design with 11 treatments and ten replications, with diluents comprising different levels of ASE 1 and ASE 2, as well as a positive control with 10% EY. The parameters measured were motility (M) and its kinetic parameters, including PM, M, velocity curve linear, velocity straight linear, velocity average pathway, linearity, straightness, wobble, amplitude lateral head beat cross frequency, and hyperactivity using computer-assisted sperm analysis, viability, and spermatozoa abnormalities.

Results

The CEP-3(m) diluent formula and ASE 1 at a 30% level maintained the PM of spermatozoa up to day 5 (40.7% ± 16.1%) of cold storage. Meanwhile, the CEP-3(m) diluent formula and ASE 2 could only maintain PM >40% until day 3 (42.1% ± 13.5%) of cold storage at a 30% level. The CEP-3(m) diluent and ASE 1 at a level of 25%-30% supported spermatozoa life (viability) up to day 5 with a value >80% (81.8 ± 3.5; 86.4 ± 2.6). The abnormality value of spermatozoa in various diluents during cold storage on days 0-5 was below 20%.

Conclusion

Soybean extracts 1 and 2 can substitute EYs as extracellular cryoprotectants in modified CEP-3 basic diluents. Soybean extract 1 can support the life of spermatozoa up to day 5 but may cause the viscosity and movement of spermatozoa to be hyperactive. Soybean extract 2 can support the life of spermatozoa up to the 3rd day of cold storage and produces progressive (non-rotating) movement patterns. Further, research is recommended with higher levels of ASE 2.

Extend the Survival of Human Sperm In Vitro in Non-Freezing Conditions: Damage Mechanisms, Preservation Technologies, and Clinical Applications

Preservation of human spermatozoa in vitro at normothermia or hypothermia maintaining their functions and fertility for several days plays a significant role in reproductive biology and medicine. However, it is well known that human spermatozoa left in vitro deteriorate over time irreversibly as the consequence of various stresses such as the change of osmolarity, energy deficiency, and oxidative damage, leading to substantial limitations including the need for semen examinations, fertility preservation, and assisted reproductive technology. These problems may be addressed with the aid of non-freezing storage techniques. The main and most effective preservation strategies are the partial or total replacement of seminal plasma with culture medium, named as extenders, and temperature-induced metabolic restriction. Semen extenders consist of buffers, osmolytes, and antioxidants, etc. to protect spermatozoa against the above-mentioned adverse factors. Extended preservation of human spermatozoa in vitro has a negative effect on sperm parameters, whereas its effect on ART outcomes remains inconsistent. The storage duration, temperature, and pre-treatment of semen should be determined according to the aims of preservation. Advanced techniques such as nanotechnology and omics have been introduced and show great potential in the lifespan extension of human sperm. It is certain that more patients will benefit from it in the near future. This review provided an overview of the current knowledge and prospects of prolonged non-freezing storage of human sperm in vitro.

Enhancement of sperm quality and fertility-related parameters in Hubbard grandparent rooster fed diets supplemented with soybean lecithin and vitamin E

The purpose of this study was to investigate the effect of dietary supplementation of different levels of soybean lecithin and vitamin E on semen quality parameters and some reproductive hormones in Hubbard grandparent roosters. The experiment was conducted in a 3 × 2 factorial arrangement with 3 levels of soybean lecithin (0, 1, and 2%) and 2 levels of vitamin E (0 and 300 mg/kg). Semen samples were collected on d 0, 20, 40 and 60 of the experiment and analyzed. Adding 1% soybean lecithin and vitamin E into the diet increased semen volume and sperm concentration, membrane integrity and viability (P < 0.05). Supplementing diets with 1 or 2% lecithin in addition to vitamin E significantly improved total motility and progressive motility (P < 0.05). Vitamin E significantly increased the amplitude of lateral head displacement (ALH) of sperm (P < 0.05). Although there was no effect on LH and FSH when diets were supplemented with vitamin E and 1 or 2% lecithin, testosterone concentration was increased (P < 0.05). Malondialdehyde (MDA) concentration was significantly lower in all 3 treatments containing vitamin E (P < 0.05). It can be concluded that supplementation of rooster diets with vitamin E and 1% lecithin can improve fertility related parameters in Hubbard grandparent roosters.

Effects of selective extenders on buffalo semen quality at physical and molecular level

This study was designed to investigate the effects of selective extenders on buffalo semen quality at physical and molecular level for screening a suitable extender for cryopreservation of buffalo semen. Semen was collected from four indigenous buffalo bulls using artificial vagina method twice in a week. After initial evaluation, each semen sample was divided into three aliquots and diluted with three different extenders (Tris-egg-yolk extender, Soya-milk extender and Andromed extender). After initial quality assessment the semen was frozen with liquid nitrogen vapor with a programmable bio freezer and finally stored at –196ºC liquid nitrogen. Post thaw semen quality evaluation was performed after 24 h of storage. The expression of aldoketoreductase family 1 member B1 (AKR1B1) and A-kinase anchoring proteins (AKAP4) transcripts in fresh and three extenders groups (post thaw) of buffalo sperm were observed. The total, progressive, static and slow motility and hypoosmotic swelling (HOS) reactivity of pre-freeze and post thaw sperms were varied significantly among Andromed, Tris-egg-yolk and Soyamilk based extender. Similar variations were also observed for different kinetic parameters of pre-freeze and post thaw buffalo sperm. However, no significant variations were found in AKR1B1 and AKAP4 genes expression among Andromed, Tris-egg-yolk and Soya milk extender groups considering pre-freeze and post thaw sperms characteristics. It may be concluded that, Tris-egg-yolk semen extender might be used for cryopreservation of buffalo semen at efficiency level similar as commercially available semen extender like Andromed.

Impact of in vitro fertilization by refrigerated versus frozen buffalo semen on developmental competence of buffalo embryos

The objective of this study was to evaluate the fertility of buffalo semen for in vitro embryo production (IVEP) by comparing the effectiveness of refrigerated versus frozen semen. Three OPU sessions were held at 30-day intervals. For oocyte fertilization three buffalo bulls were used, one per session. At each OPU-IVEP session, one ejaculate was collected and divided into two equal aliquots. Each aliquot was either refrigerated at 5ºC/24 hours or frozen. A TRIS extender containing 10% low density lipoproteins, 0.5% lecithin and 10 mM acetylcysteine was used adding 7% glycerol for freezing. Sperm motility/kinetic was evaluated by CASA and sperm membrane integrity by the hypoosmotic swelling test. The evaluations were performed at 0 h (post final dilution at 37ºC), at 4 and 24 hs post-incubation at 5ºC and post-thaw. At 24 hs incubation and immediately post thaw sperm cells were used for in vitro fertilization of buffalo oocytes equally distributed between both groups. Cleavage rates and embryo development were followed. The embryo/matured and embryo/cultured rates were 25.4 x 14.0% and 29.4 x 18.5% (P<0.05), for chilled and frozen semen, respectively. It is concluded that cooled semen can be used for in vitro embryo production in buffalo and that a better efficiency may be expected for cooled compared to frozen semen.

Exogenous catalase improves the goat seminal attributes at refrigeration temperature

The objective of the present study was to evaluate the potential benefit of catalase (CAT) on sperm functional parameters (motility, viability, membrane integrity and acrosomal integrity) during liquid storage of buck spermatozoa at 0 h, 24 h, 48 h, 72 h and 96 h. Semen samples from bucks were pooled to avoid individual effect and diluted with tris-egg yolk-fructose extender with catalase (0 U/ mL (control), 200 U/mL, 400 U/ mL, 600 U/ mL and 800 U/ mL) at a final concentration of 400 million/mL. No significant difference was observed between treatments at 24 h with respect to motility, viability and plasma membrane integrity. However, acrosome integrity of control was significantly higher as compared to other concentrations. Motility, viability, plasma membrane and acrosome integrity were observed significantly highest for CAT @ 600 U/mL in comparison to other concentrations at 48 h, 72 h and 96 h of liquid storage at refrigeration temperature. The seminal parameters declined with the progression of storage time and remained over 50% even after 72 h at refrigeration temperature in CAT @ 600 U/mL. It can be concluded that the addition of CAT @ 600 U/mL in semen diluent along with 20% egg yolk reduced the detrimental effects of cooling on motility, viability, plasma membrane and acrosome integrity.

Liquid storage of dromedary camel semen in different extenders

This study was conducted to assess the effects of commercial extenders and storage temperature on dromedary camel sperm quality during liquid preservation. In Experiment 1, ejaculates (n = five males; replicated seven times) were split and diluted with synthetic (OPTIXcell, EquiPlus, INRA96, Bioxcell or AndroMed; Experiment 1a) or egg-yolk based (Biladyl, Green buffer or Triladyl; Experiment 1b) extenders and stored for 48 h at 4 °C. In Experiment 2, split ejaculates (n = five males; replicated six times) were used to directly compare Green buffer, OPTIXcell and Triladyl extenders over 48 h of storage at 4 °C. Ejaculates collected in Experiment 3 (n = five males; replicated five times) were diluted with Green buffer or Triladyl before chilled storage for 48 h at 4 or 15 °C. Sperm kinematics, viability and acrosome integrity were assessed during liquid storage. In Experiment 1a, there was the greatest total sperm motility (TM) in the OPTIXcell group following 24 and 48 h of storage, while in Experiment 1b, there was the greatest TM after 48 h of storage with Triladyl and Green buffer. In Experiment 2, there were greater TM and viable acrosome intact spermatozoa in the Triladyl and Green buffer than with OPTIXcell group. In Experiment 3, there was a greater TM in the Triladyl than Green buffer group at 24 and 48 h of storage regardless of storage temperature (which had no effect on sperm quality). In conclusion, camel sperm have greater viability when preserved in liquid form for 48 h following dilution with Triladyl and storage at either 4 or 15 °C.

Cryoprotective effect of low-density lipoproteins on post thaw semen quality in Hariana bull

The study aimed to evaluate the cryoprotective effect of low-density lipoprotein in Hariana bull semen. Four adult Hariana bull (3-4 years) after thorough andrological examination were selected for experiment. Semen was collected from each bull twice a week; total of 32 ejaculates (8 from each bull) were collected during the experiment. Collected sample from each bull was divided into 5 equal aliquots. Four aliquots were diluted separately with a Tris-based extender containing different concentration of low-density lipoproteins viz. 7% (T-1), 8% (T-2), 9% (T-3) and 10% (T- 4) as treatment while routinely used extender containing 20% hen egg yolk was used as control (C) to achieve final concentration of 125 million spermatozoa/ml. The diluted samples were cryopreserved and evaluated after 7 days. A significantly higher value of percent live sperms, sperm positive for hypo osmotic swelling test, sperms with intact acrosome and sperms exhibiting pattern F (uncapacitated sperm) were significantly higher in T-3 as compared to other treatment groups and control. The kinematic characters exhibited by sperm i.e forward progression %, VCL (μm/sec), VSL (μm/sec), VAP (μm/sec), Lin (%), Str (%), BCF (Hz) and ALH (μm) were significantly higher in T-3 as compared to other treatment group and control. In conclusion, extender containing 9% low density lipoproteins has better capacity to maintain the sperm character in post thaw Hariana bull semen and can be a preferred concentration to be utilized for cryopreservation with improved conception rate.

Cryopreservation of Nili-Ravi buffalo (Bubalus bubalis) semen in AndroMed® extender; in vitro and in vivo evaluation

The study was designed to evaluate AndroMed^® for the freezability and fertility of Nili-Ravi buffalo semen. Semen was collected from four adult Nili-Ravi buffalo (Bubalus bubalis) bulls for 3 weeks (replicate). Semen ejaculates from each buffalo bull were divided into three aliquots. One aliquot was used for evaluation of motility, plasma membrane integrity, livability, viability, DNA integrity and normal apical ridge. Remaining two aliquots were diluted (37°C; 50 × 10⁶ spermatozoa/ml) in tris-citric egg yolk or AndroMed^® extender and cryopreserved in 0.5 ml French straws. After thawing, per cent post-thaw motility (47.9 ± 0.8, 49.2 ± 1.7), plasma membrane integrity (44.4 ± 1.2, 46.8 ± 1.8) and normal apical ridge (81.4 ± 0.3, 83.2 ± 0.3) were recorded similar (p > .05) in tris-citric egg yolk and AndroMed^® extender. Higher (p < .05) percentage of sperm livability (70.5 ± 1.4 and 64.4 ± 1.0), viability (67.5 ± 1.5 and 61.5 ± 0.6) and DNA integrity (97.0 ± 0.3 and 93.4 ± 0.21) were recorded in AndroMed^® compared to tris-citric egg yolk post-thaw. Values for all the aforementioned spermatozoal quality parameters were observed lower (p < .05) in frozen-thawed compared to fresh semen irrespective of the experimental extenders. Fertility rates of buffalo semen did not differ (p > .05) either cryopreserved in tris-citric egg yolk or AndroMed^® extender (45.5% vs. 49%). It is concluded that AndroMed^® is capable in protecting the buffalo bull sperm during freeze-thawing process and can be adopted safely for routine use replacing the tris-citric egg yolk extender in artificial insemination programme.

Effect of different concentrations of soybean lecithin and virgin coconut oil in Tris-based extender on the quality of chilled and frozen-thawed bull semen

AIM

The objective of this study was to evaluate the effects of different concentrations of soybean lecithin (SL) and virgin coconut oil (VCO) in Tris-based extender on chilled and frozen-thawed bull semen quality parameters.

MATERIALS AND METHODS

A total of 24 ejaculates were collected from four bulls via an electroejaculator. Semen samples were diluted with 2% VCO in Tris-based extender which consists of various concentrations of SL (1, 1.25, 1.5, and 1.75%). A 20% egg yolk in Tris used as a positive control (C+). The diluted semen samples were divided into two fractions; one for chilling which were stored at 4°C for 24, 72, and 144 h before evaluated for semen quality parameters. The second fraction used for freezing was chilled for 3 h at 4°C, packed into 0.25 mL straws and then cryopreserved in liquid nitrogen. The samples were then evaluated after 7 and 14 days. Chilled and frozen semen samples were thawed at 37°C and assessed for general motility using computer-assisted semen analysis, viability, acrosome integrity and morphology (eosin-nigrosin stain), membrane integrity, and lipid peroxidation using thiobarbituric acid reaction test.

RESULTS

The results showed that all the quality parameters assessed were significantly (p<0.05) improved at 1.5% SL concentration in chilled semen. Treatment groups of 1, 1.25, 1.5, and 1.75% SL were higher in quality parameters than the control group (C+) in chilled semen. However, all the quality parameters in frozen-thawed semen were significantly higher in the C+ than the treated groups.

CONCLUSION

In conclusion, supplementation of 1.5% SL in 2% VCO Tris-based extender enhanced the chilled bull semen. However, there was no marked improvement in the frozen-thawed quality parameters after treatment.

A comparison of semen diluents on the in vitro and in vivo fertility of liquid bull semen

The aim of this study was to assess the effect of semen diluent on calving rate (CR) following artificial insemination with liquid bull semen stored for up to 3 d postcollection. In experiment 1, the effect of storing liquid semen maintained at a constant ambient temperature in 1 of 7 different diluents [Caprogen (homemade), OptiXcell, BioXcell, BullXcell, INRA96, NutriXcell, or AndroMed (all commercially available)] on total and progressive motility was assessed on d 0, 1, 2, and 3 postcollection. In experiment 2, the field fertility of liquid semen diluted in Caprogen, BioXcell, or INRA96 and inseminated on d 1, 2, or 3 postcollection was assessed in comparison to frozen-thawed semen (total of n = 19,126 inseminations). In experiment 3, the effect of storage temperature fluctuations (4 and 18°C) on total and progressive motility following dilution in Caprogen, BioXcell, and INRA96 was assessed on d 0, 1, 2, and 3 postcollection. In experiment 1, semen stored in Caprogen, BioXcell, and INRA96 resulted in the highest total and progressive motility on d 1, 2, and 3 of storage compared with OptiXcell, BullXcell, NutriXcell, and AndroMed. In experiment 2, an effect of diluent on CR was found as semen diluted in BioXcell had a lower CR on d 1, 2, and 3 of storage (46.3, 35.4, and 34.0%, respectively) in comparison with Caprogen (55.8, 52.0, and 51.9%, respectively), INRA96 (55.0, 55.1, and 52.2%, respectively), and frozen-thawed semen (59.7%). Effects were found of parity, cow fertility sub-index, as well as the number of days in milk on CR. In experiment 3, when the storage temperature of diluted semen fluctuated between 4 and 18°C, to mimic what occurs in the field (nighttime vs. daytime), BioXcell had the lowest total and progressive motility in comparison to Caprogen and INRA96. In conclusion, diluent significantly affected sperm motility when stored for up to 3 d. Semen diluted in INRA96 resulted in a similar CR to semen diluted in Caprogen and to frozen-thawed semen, whereas that diluted in BioXcell resulted in a decreased CR. Consistent with this finding, semen diluted in BioXcell was less tolerant of temperature fluctuations than that stored in Caprogen or INRA96. Given that it can be used directly off the shelf, INRA96 may be a suitable alternative to Caprogen for the storage of liquid bull semen.

Cryopreservation of bull semen: Evolution from egg yolk based to soybean based extenders

Since the inception of bovine semen cryopreservation, egg yolk and milk based extenders have been used to protect sperm from the detrimental effects of cooling and freezing. In recent years, demand for alternatives to conventional commercial extenders has arisen as the risk of introducing exotic diseases through transporting egg yolk based products has been recognized. Egg yolk can also interfere with sperm evaluation and the presence of particulate material in the extender may reduce fertility. Soybeans contain lecithin, a phospholipid fraction that can substitute for high molecular weight lipoprotein and phospholipids from egg yolk and prevent or ameliorate damage to the sperm plasma membrane that occurs during extension, cooling, and cryopreservation. Soy lecithin based extenders have been evaluated for processing and freezing bovine semen, although extender from soybean milk has not been studied as extensively. Commercially available soy lecithin based extenders are used increasingly but remain under scrutiny and are not universally accepted. With these observations in mind, this review is intended to examine effects of conventional cryopreservation procedures, methods of assessment, and potential for developing soybean extract as an acceptable alternative to traditional egg yolk and milk based extenders for bull sperm cryopreservation.

Comparative evaluation of Nabi and Beltsville extenders for cryopreservation of rooster semen

Two experiments were conducted to evaluate the new rooster semen freezing extender which is containing a low level of glycerol and soybean lecithin as an alternative protective agent in the extender. The aim of the first experiment was to evaluate a new extender for freeze-thawing rooster semen known as "Nabi" extender compared to Beltsville. Second experiment was also performed to determine whether the Nabi extender has negative reactions on fertilization after artificial insemination (AI) or no. In the first experiment, post-thaw motion parameters, mitochondrial function and sperm apoptosis were analyzed using Sperm Class Analyzer (SCA), rhodamine-123 and Annexin-V, respectively for frozen-thawed semen in Nabi and Beltsville extender. Results showed that total motility, progressive motility, velocity parameters (VCL, VSL, VAP, LIN and STR) and live spermatozoa with active mitochondria were significantly higher in Nabi compare to Beltsville extender (P < 0.01). Also, the percentages of post-thawed live and early apoptotic spermatozoa were significantly higher in Nabi compared to Beltsville extender (14.46 ± 0.95 vs. 19.27 ± 0.95 and 14.83 ± 4.51 vs. 39.27 ± 4.51, respectively). For apoptotic spermatozoa, the percentages of post-thawed late apoptotic spermatozoa were significantly lower in Nabi (29.66 ± 3.11) compared to Beltsville extender (69.07 ± 3.11), but the type of extender had no effect on the percentages of post-thawed necrotic spermatozoa. In the second experiment, 20 broiler breeder hens (Ross 308) were inseminated with thawed semen using the new freezing diluents or fresh semen for determination of fertility rate. Fertility rate with thawed semen (with Nabi extender) was lower compared to fresh semen (by approximately 8% points). It can be concluded that Nabi extender would improve post-thawed rooster sperm in vitro quality compared to Beltsville extender. The fertility rates of insemination in hens with freeze-thaw sperm were comparable with fresh sperm.

Alternative procedures for the cryopreservation of brown bear ejaculates depending on the flexibility of the "in cooling" period (5°C)

The adaptability of cryopreservation protocols for brown bear spermatozoa collected under field conditions and frozen in a nearby laboratory (transported for a few hours) or shipped to a reference laboratory for sex sorting (transported for a few days) was evaluated. Forty-nine electroejaculates from 15 mature brown bears were extended to 100×10(6) sperm/mL in a TES-Tris-Fructose based extender and cryopreserved (-20°C/min to -100°C and stored at -196°C). After thawing, the quality of the seminal samples was assessed for total (TM), progressive (PM) motility and kinetic parameters - by CASA -, and viability (VIAB), viable and non-apoptotic status (YOPRO-), high membrane mitochondrial potential (MIT) and intact acrosomes (iACR) - by flow cytometry -. In Experiment 1, we assessed different storage times (0, 0.5, 1 - control -, 4-5, 7-8 and 11-12 h) at 5°C from final dilution to freezing. After thawing, non-equilibrated samples (0 h) showed lower values of iACR, TM and PM. No significant differences were found for the different periods of equilibration tested. In Experiment 2, we evaluated three long-term storage times (24, 48 and 72 h) at 5°C before freezing using storage for 1h as control. The post-thawing quality of brown bear spermatozoa declined markedly after 48-72 h of pre-freezing. In conclusion, our findings suggest the possibility of extending the pre-freezing cooling period up to 24h post-collection without freezing. This knowledge should enable the adaptation of the freezing protocols for when a special handling conditions are required such as the shipment of seminal samples to technological centers for the pre-freezing application of enhancer spermatic biotechnologies.

Soya-lecithin in extender improves the freezability and fertility of buffalo (Bubalus bubalis) bull spermatozoa

Egg yolk is routinely used as a cryoprotectant in semen extenders. However, it may contain cryoprotective antagonists, and there are hygienic risks associated with its use. Proteins of plant origin, like soya-lecithin, lack these hazards. The aim of this study was to use soya-lecithin as a cryoprotectant in extender and to investigate its effects on in vitro quality and in vivo fertility of buffalo semen. Semen from three buffalo bulls was frozen in tris-citric extender containing 5.0%, 10% or 15% soya-lecithin or 20% egg yolk. Sperm motility, plasma membrane integrity and viability were assessed post-dilution, pre-freezing and post-thaw. In Post-dilution and pre-freezing, the values for motility, plasma membrane integrity and viability remained higher (p ≤ 0.05) in extenders containing 10% soya-lecithin and control compared with extender containing 5% and 15% soya-lecithin. However, motility, plasma membrane integrity and viability were higher (p < 0.05) in extender containing 10% soya-lecithin compared with control and extenders containing 5% and 15% soya-lecithin. Semen from two buffalo bulls was frozen in tris-citric extender containing either 10% soya-lecithin or 20% egg yolk. Higher (p < 0.05) fertility rate was recorded in buffaloes inseminated with semen containing 10% soya-lecithin (56%) compared with 20% egg yolk (41.5%). The results suggest that 10% soya-lecithin in extender improves the freezability and fertility of buffalo bull spermatozoa and can be used as an alternate to egg yolk in cryopreservation of buffalo semen.