Sephadex and sephadex ion-exchange filtration improves the quality and freezability of low-grade buffalo semen ejaculates

New insights into semen separation techniques in buffaloes

Male infertility is frequently caused by idiopathic or unexplained reasons, resulting in an increase in demand for assisted reproductive technologies. In buffaloes, more than in other animals due to reproductive hardiness, successful fertilization needs spermatozoa to effectively transit the female reproductive system to reach the oocyte. This mechanism naturally picks high-quality sperm cells for conception, but when artificial reproductive technologies such as in vitro fertilization, intracytoplasmic sperm injection, or intrauterine insemination are utilized, alternative techniques of sperm selection are necessary. Currently, technology allows for sperm sorting based on motility, maturity, the lack of apoptotic components, proper morphology, and even sex. This study provides current knowledge on all known techniques of sperm cell sorting in buffaloes, evaluates their efficiency, and discusses the benefits and drawbacks of each approach.

Selection of spermatozoa with high motility and quality from bovine frozen-thawed semen using the centrifuge-free device

This study aimed to assess the potential of the centrifuge-free commercial device (MIGLIS®) in selecting functional frozen-thawed bovine sperm by migration-sedimentation, its effect on embryo development, and compare the potential with that of centrifugation-based techniques, including washing and Percoll density gradient centrifugation (DGC). In experiment 1, different dilutions (1.5×, 2×, and 3×) of frozen-thawed spermatozoa were assessed to identify the adequate one for the MIGLIS method. In experiment 2, the recovery rates, quality, and reactive oxygen species (ROS) concentrations of the spermatozoa selected using MIGLIS, washing, and Percoll DGC were compared. In experiment 3, the resultant in vitro fertilised embryos from spermatozoa selected using the three methods were evaluated for blastocyst formation rates and intracellular ROS concentrations at the 2-4 cell stage. The intracellular ROS concentrations were investigated using 2', 7'-dichlorodihydrofluorescein diacetate staining. Using the MIGLIS device, significantly more spermatozoa were recovered at 2× dilution compared with the other dilution ratio, but the motility was not affected by the dilution ratio. On the selection of spermatozoa using the three methods, employing MIGLIS decreased the recovery rates. However, the MIGLIS method increased motility, viability, and acrosome integrity rates compared to those in spermatozoa from the other methods. The ROS concentration of spermatozoa in the MIGLIS method was significantly lower than that in the washing method. Nevertheless, blastocyst formation rates were similar among the three methods, but the ROS concentration of early-stage embryos produced using MIGLIS was significantly lower than those produced using Percoll DGC. In conclusion, the MIGLIS method has the potential to select functional, high-quality frozen-thawed bovine spermatozoa.

Filtration techniques are advantageous over colloidal centrifugation in improving freezability of low-quality buffalo bull (Bubalus bubalis) ejaculates

The study compared efficacy of three sperm selection techniques in improving freezability of low-quality Murrah buffalo bull ejaculates. Sephadex (SEP), Sephadex ion-exchange filtration (SIE), and 40/80% BoviPure™ (BP) gradient centrifugation protocols were standardized (ejaculates, n = 24). In Experiment-I, Sephadex G-75, G-100, and combined Sephadex G (75-100) column filtrates were compared. In Experiment-II, BP protocols: 200 g-10 min, 250 g-5, and 10 min, 300 g-10, and 15 min were compared. In fresh semen, Sephadex G (75-100) filtration and 250 g-5 min BP protocol improved sperm functions and were used in Experiment-III, where SEP G (75-100), SIE G (75-100), and 250 g-5 min BP processed ejaculates (n = 48) were cryopreserved and compared at post-thaw stage. The mean recovery rate differed in order: SEP > SIE > BP. SIE filtration significantly improved progressive motility, livability, membrane integrity, bovine cervical mucus penetration and live non-apoptotic sperm. Compared with control, all three techniques equally reduced post-dilution and post-thaw lipid peroxidation (LPO) rate. SEP post-thaw filtrates observed lower cryocapacitation-like changes, LPO (C11-BODIPY581/591), and higher active mitochondria than other treatments. SIE and SEP equally improved post-thaw acrosome-intact sperm over BP. Filtration techniques, preferably, Sephadex ion-exchange filtration can most efficiently process low-quality buffalo bull ejaculates for cryopreservation and improve freezability.

Protective effects of different doses of MitoQ separately and combined with trehalose on oxidative stress and sperm function of cryopreserved Markhoz goat semen

The mitochondria-targeted antioxidant MitoQ has been regarded as an effective antioxidant agent against cryo-induced oxidative cellular damage. This study aimed to evaluate the use of different doses of MitoQ combined with trehalose to minimize mitochondrial impairment and oxidative stress during sperm cryopreservation of Markhoz goat. For this, semen samples (n = 50) were collected by electroejaculation every 5 days from 5 bucks in 10 replicates. On each collection day, 5 ejaculates (one ejaculate for each buck) were pooled and then diluted in eight different Tris-based extenders as follows: no additives (control), 20, 200, 2000 nM of MitoQ (MT20, MT200, MT 2000, respectively), 150 mM of trehalose (Tr), MT20+Tr, MT200+Tr, MT2000+Tr. The semen samples were frozen using a standard protocol, and sperm function and oxidative stress were evaluated after thawing. The semen extender supplemented with MT200+Tr had higher (P < 0.05) total and progressive motility, acrosome and membrane integrity, superoxide dismutase, glutathione peroxidase, total antioxidant capacity, and lower (P < 0.05) DNA fragmentation, malondialdehyde and intracellular hydrogen peroxide levels than the all other groups except MT200; meanwhile, MT200 was also improved (P < 0.05) in these parameters than in the control group. Furthermore, MT200 and MT200+Tr showed higher (P < 0.05) percentages of live cryopreserved sperm with high mitochondrial activity than other groups. However, abnormality percentage and catalase activity of frozen-thawed sperm were not affected by treatments (P > 0.05). To conclude, we have found that supplementation of 200 nM MitoQ alone or in combination with 150 mM trehalose to semen extender improved the quality of cryopreserved sperm in goats, which is associated with enhanced antioxidant enzymatic defense and mitochondrial activity and reduced DNA fragmentation.

Novelties in Ovine Assisted Reproductive Technologies – A Review

Artificial insemination (AI) as a part of assisted reproductive technologies represents the oldest and most widespread method used to accelerate genetic progress in all domestic animals. After its first implementation in ovine reproduction and almost 80 years afterward, AI is continuously used for improving the genetic merit, utilizing either fresh or short-time chilled semen. Nevertheless, regardless of the semen used for insemination, the conception rate (CR) is still lower in comparison to natural service. At least two factors are commonly thought to limit the success of the AI and reduce the CR: (1) failure of placing the semen directly into the uterus due to the specific anatomic structure of the ewe’s cervix; (2) lower viability of ram spermatozoa during cryopreservation (<30% progressively motile spermatozoa after thawing). This review elaborates on recent studies that aimed to achieve acceptable CR through the implementation of cervical or intrauterine insemination: deep intracervical, intrauterine trans-cervical, and intracornual. Several hormonal treatments (oxytocin, estrogen, or prostaglandin) were evaluated on inducing cervical dilation that facilitates insemination. A comprehensive analysis was given to the effects of several antioxidants (GSSG, GSH, and cysteine) supplemented in ram semen-freezing media. Sex-sorted ram semen fertility rate results were presented from our studies.

Selecting motile, non-apoptotic and induced spermatozoa for capacitation without centrifuging by MACS-Up method

In newly improved MACS-Up method, magnetic field has been applied to separate non-apoptotic spermatozoa directly from the neat semen. The spermatozoa during passing through a viscous layer, located on the neat semen, contacted with progesterone and induced for the capacitation. Then, a clean population of non-apoptotic, and capacitated spermatozoa were selected in the pure culture media. Selected spermatozoa may be useful for use in ART. The 80 semen samples from normozoospermic individuals were divided separately into 4 attempts. Semen analysis, SCSA (sperm chromatin structure assay), FLICA (fluorescein-labelled inhibitors of caspase) methods, immunoassay of phosphorylation of tyrosine residues of sperm proteins, nuclear DNA integrity, caspase 3 activity and sperm capacitation rate were all performed for evaluation of sperm parameters respectively. To examine all aspects, the MACS-Up method compared with DGC (density gradient centrifuging) and MACS-DGC methods separately. This method can isolate non-apoptotic spermatozoa directly from the neat semen, which has similar performance compared to the MACS-DGC method. Movement and passing spermatozoa through the viscous layer, and contact with progesterone, significantly induced spermatozoa for capacitation compared with the control group. Also, the MACS-Up in comparison with routine DGC method could select spermatozoa with significantly higher total and progressive motility, DNA integrity, induced sperm population for capacitation and normal morphology. MACS-Up can be developed as an effective, short-time, and ease of performing method and used practically to select functional spermatozoa as novel sperm selection procedure. However, for clinical use of MACS-Up, all clinical aspects of this method should be considered and evaluated.

Pre-treatment of ram semen extender with magnetic nanoparticles on freeze-thawed spermatozoa

Background

Extensive use of different nanoparticles caused significant concerns about their biological safety.

Objective

This study aimed to evaluate the effects of cryopreservation on ram semen after adding magnetic nanoparticles (MNPs) to separate X and Y chromosome‐bearing spermatozoa.

Methods

The experimental ram sperms in this research included treated spermatozoa (50 μg/ml MNPs) and non‐treated spermatozoa. DNA damage of spermatozoa was examined using an acridine orange (AO) assay. Sperm viability, membrane functionality, abnormality and malondialdehyde (MDA) level were also measured.

Results

Results indicated that the pre‐treatment of ram semen extender with MNPs did not significantly affect the semen parameters such as viability, membrane functionality, abnormality, as well as lipid peroxidation (LPO) levels and DNA integrity in comparison with the control group (p < 0.05).

Conclusions

These observations suggest that pre‐treatment of ram semen extender with MNPs after semen sexing did not have adverse effects on different semen parameters after cryopreservation.

In the current study, we evaluated the effects of cryopreservation on ram semen after adding magnetic nanoparticles (MNPs), then after thawing some semen parameters were evaluated.

Improvement of the in vitro fertilization and embryo development using frozen-thawed spermatozoa of microminipigs

This study aimed to compare the quality and the penetration ability of frozen–thawed spermatozoa from three microminipigs and Large White boars and to evaluate the effects of caffeine and heparin as well as the sperm–oocyte co-incubation length on the fertilization and embryonic development in vitro. Results showed that the fertilization rates of spermatozoa from three microminipig boars were significantly lower than those of a Large White boar. In the post-thaw spermatozoa from one of three microminipig boars, the sperm quality, penetration ability, and the oocyte development after in vitro fertilization were significantly lower than those of the spermatozoa from other boars. The caffeine supplementation in the fertilization media increased the rates of fertilization and blastocyst formation for the microminipig spermatozoa with low sperm quality. In addition to caffeine supplementation, the rates of fertilization and blastocyst formation after using microminipig spermatozoa were significantly higher with a 10 h sperm–oocyte co-incubation than with 3 h of co-incubation length. Our results indicate that the differences between the males and the breed influence the quality and fertility of frozen–thawed boar spermatozoa. In conclusion, the presence of caffeine in the in vitro fertilization (IVF) medium and adequate length of sperm–oocyte co-incubation may have beneficial effects for improving IVF results when using microminipig spermatozoa with low quality.

Effect of Tris-extender supplemented with a combination of turmeric and ethylene glycol on buffalo bull semen freezability and in vivo fertility

The objective of this study was to evaluate the effect of Tris-extender supplemented with a combination of turmeric and ethylene glycol on buffalo bull semen preservability and in vivo fertility. Five tubes (each contain 5 ml Tris-citric acid-fructose yolk, TCFY). The first tube contains turmeric extract and ethylene glycol and kept as a control. The other four tubes contain 1.5% ethylene glycol plus turmeric extract as follows: 100 μl/5 ml, 200 μl/5 ml, 300 μl/5 ml, and 400 μl/5 ml v/v). Pooled bull semen was added to the Tris extender and to Tris turmeric ethylene glycol. Extended semen was subjected to semen freezing protocol. Semen assessment was carried out. In Tris turmeric ethylene glycol post-cooling, sperm motility and alive sperms were significantly higher in the first concentration of Tris turmeric ethylene glycol (TTE₁), sperm abnormalities were significantly lower in TTE₁ and TTE₂, and sperm membrane integrity (HOST) was significantly higher in TTE₁ and acrosome percent was significantly higher in TTE₁, TTE₂, and TTE₄ if compared to the control. Post-thawing, sperm motility was significantly higher in TTE₁ as compared to the control and other concentrations of TE. All concentrations of TE were significantly higher in sperm membrane integrity (HOST) as relative to the control. Alive sperms were kept in TTE₁ as the control. Acrosome percent was kept in most concentrations as the control. It is concluded that, in cooled and post-thawed semen, the first concentration (TTE₁) gave the best sperm quality and conception rate.

Sperm binding to hyaluronan is an excellent predictor of Nili-Ravi buffalo bull fertility

This study reports the first evaluation of sperm hyaluronan binding assay (HBA) for predicting the fertility of Nili-Ravi buffalo bulls in relation to standard parameters of sperm quality. Cryopreserved semen doses of low (n = 6), medium (n = 3) and high fertility (n = 8) bulls based on their respective return rates were used. Significantly, more spermatozoa bound to hyaluronan from the most fertile bulls (57.15% ± 1.44) compared with medium (42.46% ± 1.08) and low fertility bulls (29.70% ± 0.78). A strongly positive correlation (r = .824, p < .01) was found between HBA and fertility that predicts a 67.9% variability (r²  = .679, p < .01) in fertility. HBA was also strongly positively correlated with sperm viability (r = .679, p < .01) followed by their live/dead ratio (r = .637, p < .01), uncapacitated spermatozoa (r = .631, p < .01), normal apical ridge (r = .459, p < .01), motility (r = .434, p < .01), mature spermatozoa with low residual histones (r = .364, p < .01), high plasma membrane integrity (r = .316, p < .01) and nonfragmented DNA levels (r = .236, p < .05). It was negatively correlated with spermatozoa having reacted acrosome (r = -.654, p < .01). A fertility model built using a combination of sperm HBA and either sperm livability or viability predicts, respectively, 86.1% (r²  = .861, p < .01) and 85.9% (r²  = .859, p < .01) variability in buffalo bull fertility. In conclusion, sperm HBA may prove to be a single robust predictor of Nili-Ravi buffalo bull fertility.

Effects of letrozole administration on growth and reproductive performance in Markhoz goat bucklings

This study evaluated the growth performance, testicular and semen characteristics, and hormonal profile of Markhoz (Iranian Angora) bucklings injected with letrozole (LTZ). Twenty-eight 4-4.5 month old bucks were randomly assigned into four groups and received either 0.25 mg/kg body weight (BW) LTZ subcutaneously (sc LTZ) or intramuscularly (im LTZ), and also sc (sc CONT) or im (im CONT) controls every week for 3 months. The study was performed at the beginning of the breeding season in Sanandaj Animal Husbandry Research Station (46.99 °E, 35.31 °N). The results showed that LTZ causes increased final body weight (25.78 ± 1.61 kg), higher average daily gain (104 ± 0.03 g/days), and decreased feed conversion ratio (7.81 ± 2.57) (P < 0.05). The pre-slaughter, hot, and cold carcass weights (27.56 ± 2.40, 11.45 ± 1.07 and 11.11 ± 1.05 kg, respectively) were (P < 0.05) heavier in LTZ groups while other carcass characteristics did not differ between groups. No differences occurred between the groups in biochemical parameters, except high-density lipoprotein levels (35.47 ± 2.43 mg/dL) which was higher in LTZ treatments (P < 0.05). LTZ-treated bucks had larger scrotal circumference (20.12 ± 5.75 cm), higher relative testicular weight (560.91 ± 78.59 mg/100 g BW) and volume (175.5 ± 29.71 cm³), greater diameter of seminiferous tubules (224.5 ± 5.21 μm), and number of Sertoli cells (8.39 ± 0.77) (P < 0.05). Semen volume (0.74 ± 0.16 mL), sperm concentration (2.64 ± 0.19 × 10^-9/mL), total sperm per ejaculate (1.95 ± 0.49 × 10^-9), and semen index (1248 ± 323) increased (P < 0.05) by LTZ treatments, while semen pH (6.77), motility (80.91%), progressive motility (76.75%), viability (83.35%), abnormality (13.70%), acrosome integrity (78.06%), and membrane integrity (80.05%) of sperm remained unaffected. Intratesticular and serum testosterone (T) levels (7.97 ± 0.89 ng/mg protein and 2.47 ± 0.59 ng/mL, respectively), serum luteinizing hormone (LH), growth hormone (GH) levels (1.71 ± 0.24 and 3.62 ± 0.33 ng/mL, respectively) of LTZ groups were elevated, whereas intratesticular and serum estradiol (E2) levels (84.14 ± 8.15 pg/mg protein and 32.33 ± 2.16 pg/mL, respectively) decreased (P < 0.05). No differences were recorded between the sc and im routes of LTZ administration in the measured parameters. To conclude, we have found that LTZ treatment improves growth and reproductive functions of goat bucklings associated with increased serum LH and GH, elevated T and reduced E2 levels in both serum and testis.

Supplementation of l-tryptophan (an aromatic amino acid) in tris citric acid extender enhances post-thaw progressive motility, plasmalemma, mitochondrial membrane potential, acrosome, and DNA integrities, and in vivo fertility rate of buffalo (Bubalus bubalis) bull spermatozoa

The aromatic amino acid l-tryptophan is an essential and versatile molecule, acts by transferring an electron to free radicals and protects the plasma membrane from injuries. The aim of the present study was to investigate the effects of l-tryptophan in extender on semen quality parameters, in vitro longevity and in vivo fertility rate of buffalo spermatozoa during cryopreservation. Two ejaculates were collected from each bull (n = 2 ejaculates and n = 4 bulls) with artificial vagina at 42 °C followed by initial evaluation for volume, motility, concentrations and were diluted in five extenders (C = lacking l-tryptophan, D1 = 25 μ M l-tryptophan, D2 = 50 μ M l-tryptophan, D3 = 75 μ M l-tryptophan, and D4 = 100 μ M l-tryptophan) respectively, and cryopreserved. The experiment was repeated four times (n = 4 replicates). At post-dilution, sperm plasma membrane integrity (PMI, %), supravital plasma membrane integrity (SVPMI, %), hypo-resistivity (HR, %) and acrosome integrity (ACR-I, %) were significantly higher (P < 0.05) in extender supplemented with D4 than control. At post-thawing, progressive motility (PM, %), PMI, SVPMI, HR, ACR-I, and DNA-I of buffalo bull spermatozoa were significantly higher in D4 than control. Sperm in vitro longevity (%) assessed in terms of PM, SVPMI, and ACR-1 were significantly higher in D4 than control. Sperm mitochondrial membrane potential (%) was higher in treated groups than the control. The in vivo fertility rate was significantly higher in D4 than control (60.17% vs. 44.17%, P < 0.05). It is concluded that the supplementation of l-tryptophan in tris citric acid extender improves semen quality parameters, in vitro longevity and in vivo fertility rate of buffalo spermatozoa during freezing and thawing process.

Stimulating effects of Quercetin (QUE) in tris citric acid extender on post thaw quality and in vivo fertility of buffalo (Bubalus bubalis) bull spermatozoa

Aim of this study was to evaluate the stimulating effects of quercetin (QUE) on post thaw quality and in vivo fertility of buffalo (Bubalus bubalis) bull spermatozoa. QUE is a well-known flavonoid having antioxidant properties to scavenge free radicals. Semen was collected from three buffalo bull through artificial vagina (42 °C) and were evaluated initially for volume, motility, concentration, followed by dilution in five extenders (n = 5 aliquots, control, C = no QUE; treatment 1, T1 = 50 μM QUE; treatment 2, T2 = 100 μM QUE; treatment 3, T3 = 150 μM QUE and treatment 4, T4 = 200 μM QUE supplementation). The experiment was repeated thrice (n = 3 replicates). At post dilution, sperm progressive motility (PM, %) plasma membrane integrity (PMI, %), supra vital plasma membrane integrity (SVPMI, %) and acrosome integrity (ACR-1, %) of buffalo bull were significantly higher (P < 0.05) in extenders supplemented with QUE than C. At thawing, sperm PM of buffalo bull was higher in T3 and T4 than C, T1 and T2. Sperm SVPMI was significantly higher in T2, T3 and T4 than C and T1. Sperm ACR-I was higher in T3 and T4 than C, T1 and T2. Sperm DNA integrity was higher in T4 than C. QUE supplementation increased in vitro semen quality during 30 and 60 min of incubation at 37 °C than C. The in vivo fertility was higher in T3 and T4 than C (%, 61.82 vs. 65.22 vs. 46.90). It is concluded that QUE @ 150 and 200 μM improved post thaw semen quality and in vivo fertility of buffalo bull.

Effects of Tris (hydroxymethyl) aminomethane on the quality of frozen-thawed boar spermatozoa

Tris (hydroxymethyl) aminomethane (Tris) has been used as a pH regulator for buffering the pH of dilution extenders for boar semen, such as the Modena extender. The purpose of the present study was to assess the effects of Tris supplementation at different concentrations (0, 8, 24 and 72 μM) into the freezing extender on the quality and fertilising capacity of frozen-thawed boar spermatozoa. The results showed that the supplementation of 24 μM of Tris gave significantly higher percentages of sperm viability and plasma membrane integrity than those of the control group at any time point of assessment (0 h and 3 h post-thawing) (P < 0.05). However, there were no significant differences in the acrosome integrity parameter among the groups. Higher percentages of sperm motility were observed in the spermatozoa cryopreserved with 24 μM of Tris compared to the control groups when the samples were analysed 0 h after thawing (P < 0.05). However, an increase of the Tris concentration to 72 μM did not enhance the sperm motility parameters. The total numbers of fertilised oocytes and blastocysts obtained with spermatozoa frozen with 24 μM Tris were significantly higher than those of the control group without Tris (P < 0.05). In conclusion, the supplementation of 24 μM Tris into the freezing extender contributes to a better boar sperm quality and fertilising capacity after the process of freezing and thawing.

Effects of chlorogenic acid and caffeic acid on the quality of frozen-thawed boar sperm

Chlorogenic acid (CGA) and caffeic acid (CA) are potent antioxidants that are mostly found in coffee beans. This study aimed to investigate the effects of CGA and CA supplementation during semen freezing on the quality of frozen-thawed boar spermatozoa. The antioxidants CGA and CA were added to a semen extender to achieve final concentrations of 50, 100, 200 and 400 µM. Supplementation of 100 µM CGA and CA yielded a significantly higher percentage of sperm viability (increased by 8%-10%) and plasma membrane integrity (increased by 4%-6%) than the control groups without the antioxidants at 0 and 3 hr after thawing (p < 0.05). At a concentration of 100 µM, CGA and CA also yielded beneficial effects on total and progressive sperm motility. Increases of CGA and CA concentrations to more than 200 µM did not enhance any sperm quality parameters. When the sperm penetrability and oocyte development by spermatozoa frozen with CGA and CA were evaluated, CGA and CA supplementations had no positive effects on the percentages of total fertilization, monospermic fertilization, cleavage and blastocyst formation. In conclusion, the supplementation of 100 µM CGA and CA during sperm freezing improved certain sperm parameters including motility, viability and plasma membrane integrity.

Effects of fulvic acids on goat sperm

The effects of adding fulvic acids (FAs) to semen extenders on the quality parameters of frozen–thawed goat buck spermatozoa remain undetermined. Buck semen samples collected from six mature goat bucks once a week were diluted with Tris–egg yolk-based extenders. The diluted semen samples were supplemented with FAs (0.2, 0.4 and 0.6%, w/w), cryopreserved, and evaluated for sperm-quality parameters. Addition of FAs to the extender increased progressive motility, acrosome integrity, membrane integrity, and superoxide dismutase and catalase activities and decreased percentage abnormality and sperm malondialdehyde level compared with the control group. However, excessive FA addition (>0.4%, w/w) to semen extenders did not improve the efficiency. The results indicated that FAs could be a promising cryoprotectant for goat buck sperm.

Effect of sunflower lecithin on Kalahari Red goat semen during cryopreservation

Soybean lecithin had been used as an alternative to egg yolk in domestic animal semen extender during cryopreservation due to its characteristic phospholipid content which played a major cryoprotective role. This composition of soybean lecithin informed the replacement of soybean with sunflower lecithin (SL) in the extender for the Kalahari Red (KR) buck semen cryopreservation in this study. Effect of different levels of SL on the quality of the KR buck semen during cryopreservation using slow freezing method was evaluated. Semen samples were collected from four KR bucks of between two and two and half of age using artificial vagina, evaluated for motility and then diluted in extenders containing different levels of SL (1.5%, 3.0% and 4.5%) as experimental group and 0% SL or 20% egg yolk as control. Semen parameters including motility, acrosome integrity (AcI), membrane integrity (MI), malondialdehyde (MDA) concentration, cholesterol level and seminal arginase activity were evaluated for. The results showed that motility, acrosome integrity (AI) and membrane integrity were comparable at 0%, (22.00 ± 4.58, 82.00 ± 3.51 and 96.00 ± 2.03); 1.5%, (23.00 ± 2.08, 87.00 ± 3.79 and 89.00 ± 2.08); 3.0%, (13.00 ± 2.52, 81.33 ± 0.41 and 76.67 ± 1.20) and 4.5% (11.00 ± 4.51, 85.33 ± 9.88 and 84.00 ± 8.50), respectively, after thawing. SL at 0% had the highest (P < 0.05) values for MDA, cholesterol and seminal arginase activity (1.10 ± 0.008 nmol/ml, 236.35 ± 4.08 mg/dl and 0.54 ± 3.3 E-3 units/mg protein, respectively). Our data suggest that 1.5% sunflower lecithin can be used in place of soy lecithin as a substitute for egg yolk during the cryopreservation of caprine semen.

Sephadex filtration as successful alternative to density-gradient centrifugation procedures for ram sperm selection with improved kinetics

Density-gradients centrifugation (DGC) and filtration columns (FC) are used to separate deformed or dead sperm, debris, and other cells that may negatively affect the fertilizing capacity of sperm in fresh, chilled and frozen/thawed semen. The present study was conducted to evaluate the suitability of DGC (BoviPure®, Percoll® and Accudenz®) and FC (Sephadex G-15®) sperm selection procedures for fresh-extended and cold-stored ram semen by assessment of post-treatment sperm quality variables. Twenty normospermic ejaculates from ten adult Merino rams were used. Sperm concentration of recovered cells was greater (P < 0.001) after BoviPure treatment than other procedures in both fresh and cold semen. With the Sephadex method, there were more desirable values than with use of DGC procedures in several sperm motility variables measured by using the CASA system. In non-refrigerated semen samples, the percentage of progressive sperm motility (%PSM) after Sephadex filtration was greater (P < 0.05) than after BoviPure treatment; the straightline velocity (VSL) value after Sephadex filtration was greater (P < 0.01) than after Accudenz treatment; the amplitude of lateral head displacement (ALH) after Sephadex and Accudenz treatment was less than non-filtered semen (P < 0.001) and after Percoll (P < 0.01) and BoviPure (P < 0.05) treatments. In cold-stored semen samples, the %PSM after Sephadex filtration was greater than non-filtered (P < 0.05) semen and after BoviPure (P < 0.05), Percoll (P < 0.05) and Accudenz (P < 0.001) treatments. It is concluded that Sephadex column filtration can be used to select ram sperm in non-refrigerated and cooled semen, because percentage progressively motile sperm and some other sperm motility characteristics are greater with use of this techniques as compared with use of DGC methods.

Sperm preparation through Sephadex™ filtration improves in vitro fertilization rate of buffalo oocytes

Routinely, swim-up method is used to separate high-quality sperm; however, long processing time and close cell-to-cell contact during the centrifugation step are inevitable elements of oxidative stress to sperm. The objective was to evaluate Sephadex^™ and glass wool filtration to separate motile, intact and viable sperm for in vitro fertilization in buffalo. The cumulus-oocyte complexes (COCs) were collected from ovaries of slaughtered buffaloes by aspiration and matured for 24 hr in CO₂ incubator at 38.5°C and 5% CO₂ . Matured COCs were rinsed twice in fertilization TALP and placed in the pre-warmed fertilization medium without sperm. Cryopreserved buffalo semen was thawed at 37°C for 30 s and processed through Sephadex^™ , glass wool filtration and swim-up (control). Total and motile sperm recovery rates were assessed, resuspended in fertilization TALP and incubated for 15-20 min in CO₂ incubator. Samples prepared by each method were divided into two aliquots: one aliquot was studied for sperm quality (progressive motility, membrane integrity, viability, liveability), while the other was subjected to co-incubation with sets of 10-15 in vitro matured oocytes. Data on sperm quality were analysed by ANOVA, while in vitro fertilizing rates were compared by chi-squared test using SPSS-20. Least significant difference (LSD) test was used to compare treatment means. Glass wool filtration yielded higher total and motile sperm recovery rate, while Sephadex^™ filtration improved (p < .05) sperm quality (progressive motility, membrane integrity, viability, liveability). Sperm preparation through Sephadex filtration yielded higher in vitro fertilization rate in terms of cleavage rate compared to glass wool filtration and swim-up (control). In conclusion, cryopreserved Nili-Ravi buffalo sperm selected through Sephadex filtration showed improved quality and yielded better fertilization rates (cleavage rate) of in vitro matured/fertilized oocytes. Sephadex filtration could be a promising technique for use in in vitro fertilization in buffalo.

Programmable fast-freezing method improves the post-thaw motion dynamics, integrities of plasmalemma, mitochondrial transmembrane, DNA and, acrosome, and in vivo fertility of water buffalo (Bubalus bubalis) spermatozoa

The effects of freezing methods (FR1, nonprogrammable/static, 5 cm above liquid nitrogen [LN₂ ] for 10 min, plunging in LN₂ ; FR2, programmable medium, +4°C to -15°C at 3°C min^-1 , from -15 to -80°C at 10°C min^-1 and final holding for 1 min at -80°C, plunging in LN₂ ; FR3, programmable fast, from initial holding at +4°C for 2 min, from +4°C to -20°C at 10°C min^-1 , from -20°C to -100°C at 30°C min^-1 , final holding for 1 min at -100°C and plunging in LN₂ ) were assessed on post-thaw in vitro quality and in vivo fertility of water buffalo spermatozoa. Mean sperm progressive motility (%), rapid velocity (%), average path velocity (μm s^-1 ), straight line velocity (μm s^-1 ), curved line velocity (μm s^-1 ), integrities (%) of plasmalemma, mitochondrial transmembrane, DNA and acrosome were higher (p < .05) in samples cryopreserved with FR3 compared to FR1 and FR2. Similarly, in vivo fertility (%) of buffalo spermatozoa was higher (p < .05) with FR3 than FR1 (%; 68.0 versus 50.0). We concluded that programmable fast-freezing method (FR3) improves the post-thaw in vitro quality and in vivo fertility of water buffalo spermatozoa.

Changes in bull sperm kinematics after single layer centrifugation

The objective of this study was to evaluate bull sperm kinematics after centrifugation through a single layer of a colloid [Single Layer Centrifugation (SLC)]. Ejaculates from 20 bulls were extended and stored at 4-6°C for 24 h during transport to the laboratory for SLC through Androcoll-B, followed by measurement of sperm kinematics in all samples. Total motility (86% and 88% for uncentrifuged and SLC samples, respectively) and progressive motility (84% for both the groups) were similar (p > 0.05). In contrast, straightness (STR) (0.65 vs 0.69), linearity (LIN) (0.32 vs 0.35) and beat cross frequency (BCF) (22.3 vs 23.6 Hz) were significantly higher in the SLC-selected samples than in the uncentrifuged samples, whereas velocity of the average path (VAP) (95 vs 90 μm/s), curvilinear velocity (VCL) (192 vs 180 μm/s), amplitude of lateral head deviation (ALH) (7 μm vs 6.5 μm) and hypermotility (49% vs 38%) were significantly decreased. The kinematics of the samples with the poorest motility was improved most by SLC. In conclusion, even though SLC had no direct effect on total and progressive motility, it appeared to have a positive influence on several other kinematic parameters that may be important for fertilization after artificial insemination.

Effects of skim-milk supplementation on the quality and penetrating ability of boar semen after long-term preservation at 15 °C

This study investigated the effects of skim-milk supplementation on the quality and penetrating ability of boar semen preserved at 15 °C. When boar semen samples were preserved in Modified Modena extender supplemented with various concentrations (0, 7.5, 15, 30 and 50 mg/mL) of skim milk powder at 15 °C for 4 weeks, higher sperm motility and viability were observed in the case of 7.5 mg/mL skim-milk supplementation compared with the control group (0 mg/mL) during the preservation (P < 0.05). When in vitro matured oocytes were co-incubated with boar sperm that had been preserved in Modified Modena extender with three different concentrations (0, 7.5 or 15 mg/mL) of skim milk powder at 15 °C for two weeks, there were no apparent effects of skim-milk supplementation on the rates of fertilisation and development to blastocysts of oocytes after co-incubation. However, the monospermic fertilisation rate of sperm preserved with 15 mg/mL skim milk powder was higher (P < 0.05) than that of fresh non-preserved sperm, but did not differ among the preservation groups. The results indicate that the supplementation of Modified Modena extender with 7.5 mg/mL skim milk powder improves the motility and viability, but not the penetrating ability, of sperm after liquid preservation for at least two weeks.

Effects of green tea polyphenol on the quality of canine semen after long-term storage at 5°C

The aim of the present study was to determine the effects of green tea polyphenol on the quality of canine semen after long-term storage at 5°C. The supplementation of a Tris-egg yolk extender with polyphenol (0.5, 0.75, or 1mg/mL) increased the motility and viability of sperm preserved for four weeks at 5°C.

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

This study was designed to compare the quality of liquid-stored buffalo bull spermatozoa in soya lecithin based extender Bioxcell(®) (BIOX), milk (MILK), tris-citric egg yolk (TEY) and egg yolk-citrate (EYC) extender at 5°C. Semen was collected from five Nili-Ravi buffalo (Bubalus bubalis) bulls of 6-7 years of age with artificial vagina over a period of 3 weeks (two consecutive ejaculates once in a week). Semen ejaculates having more than 60% motility were pooled, split into four aliquots, diluted (37°C; 10 × 10(6) motile spermatozoa/ml), cooled from 37 to 5°C in 2 h (0.275°C/min) and stored for 5 days. Sperm motility, viability, plasma membrane integrity (PMI) and normal acrosomal ridge were studied at first, third and fifth day of storage. Higher values of progressive sperm motility (%), sperm viability (%), sperm PMI (%) and normal apical ridge (%) were observed in BIOX, MILK and TEY extenders at first, third and fifth day of storage than EYC extender. Progressive sperm motility, sperm viability and sperm PMI in BIOX(®) extender were not different from MILK and TEY extenders at 1st and third day storage period. However, at fifth day of storage, the values for these parameters remained significantly higher (p<0.05) in BIOX(®) compared with MILK, TEY and EYC extenders. At fifth day of storage, the semen quality parameters for Bioxcell(®) were comparable to those with MILK and TEY extenders at third day of storage. In conclusion, motility, viability and PMI of buffalo bull spermatozoa remained similar in Bioxcell(®) , milk and TEY extender at first and third days of storage at 5°C. Yet, the values for the aforementioned parameters in Bioxcell(®) were higher compared with milk, TEY and EYC extender at fifth day of storage at 5°C.

Practical applications of sperm selection techniques as a tool for improving reproductive efficiency

Modern biotechnologies are used extensively in the animal breeding industry today. Therefore, it is essential that sperm handling procedures do not modulate the normal physiological mechanisms occurring in the female reproductive tract. In this paper, the different selection mechanisms occurring in vivo are described briefly, together with their relevance to artificial insemination, followed by a detailed description of the different selection processes used in reproductive biotechnologies. These selection methods included fractionated semen collection, cryopreservation, biomimetic sperm selection, selection based on hyaluronic acid binding, and last, but not least, sperm sex selection. Biomimetic sperm selection for AI or for cryopreservation could improve pregnancy rates and help to reverse the decline in fertility seen in several domestic species over the recent decades. Similarly, selection for hyaluronic acid binding sites may enable the most mature spermatozoa to be selected for IVF or ICSI.

Effects of filtration of semen doses from subfertile boars through neuter Sephadex columns

This study was designed to develop a method of improving the quality of sperm obtained from subfertile Piétrain boars. Seminal doses were filtered through neuter Sephadex columns (G-25 Medium, G-50 Fine, G-50 Medium and G-75, length 10 +/- 0.5 cm, flow rate 1 ml/20 s). Doses were prepared by pooling 10 ml semen samples collected from 58 asthenoteratospermic boars and diluted the sperm-cell rich fraction 1 : 6 in Betsville thawing solution extender. Sperm quality was determined before and after the filtering process. Sperm morphology and motility were assessed using the computer program SCA 2002 production, and sperm vitality was evaluated by fluorescence multistaining. ORT and HRT tests were used to determine the osmotic resistance of spermatozoa, and metabolic performance was assessed by measuring l-lactate production. Results indicate that the filtration process rendered increased proportions of mature spermatozoa and of viable spermatozoa with an intact acrosome, nucleus and mitochondrial sheath. Sperm filtration led to decreased percentages of spermatozoa with proximal and distal droplets and of agglutinated spermatozoa, along with slightly diminished ORT values. HRT scores and L-lactate production were unaffected. Our findings indicate that filtering through a Sephadex column improves the sperm morphology and vitality of seminal doses obtained from subfertile boars, but produces no functional changes in the spermatozoa. All four column types yielded similar results.

Duck egg yolk in extender improves the freezability of buffalo bull spermatozoa

We investigated the use of duck egg yolk (DEY), Guinea fowl egg yolk (GFEY) and Indian indigenous hen (Desi) egg yolk (IDEY) in extender for improving the post-thaw quality of buffalo (Bubalus bubalis) bull spermatozoa, and compared it with commercial hen egg yolk (CHEY; control). For this purpose, two consecutive ejaculates of semen from each of two Nili-Ravi buffalo bulls were collected on 1 day each week for 5 weeks (replicates; n=5) with artificial vagina (42 degrees C). Split pooled ejaculates, were diluted in tris-citric acid glycerol extender containing either DEY or GFEY or IDEY or CHEY at 37 degrees C. Extended semen was cooled to 4 degrees C in 2 h and equilibrated for 4 h at 4 degrees C. Cooled semen was then filled in 0.5 ml straws at 4 degrees C and frozen in programmable cell freezer. Thawing of semen was performed at 37 degrees C for 30 s. Sperm motility, plasma membrane integrity and sperm morphology (acrosome integrity, head, mid-piece and tail abnormalities) of each semen sample were assessed at 0, 3 and 6 h after thawing and incubation at 37 degrees C. Visual motility (%) and percentage of intact plasma membranes assessed at 6h post-thaw of buffalo bull spermatozoa were highest (P<0.05) due to DEY as compared to GFEY, IDEY and control. The percentage of spermatozoa with normal acrosomes at 0, 3 and 6 h post-thaw was highest (P<0.05) in DEY extender than GFEY, IDEY and CHEY. Sperm tail abnormalities (%) observed at 0, 3 and 6 h post-thaw in samples cryopreserved with freezing extender having DEY were lower (P<0.05) as compared to extender containing GFEY, IDEY and CHEY. In conclusion, DEY compared to other avian yolks in extender improves the frozen-thawed quality of buffalo bull spermatozoa.

Reproduction in the Water Buffalo

In this paper, an account of various aspects related to buffalo reproduction are given. Fundamental concepts of the reproductive physiology as well as manipulation of the reproductive function will be presented. This will include an overview of the most recent developments of the oestrous cycle and the ovulation control, new strategies of reproductive management for the improvement of genetic gain and the application of newly developed reproductive technologies, such as in vitro embryo production, embryo and sperm sexing and cloning.

Assessment of the efficacy of Sephadex G-15 filtration of bovine spermatozoa for cryopreservation

Semen from five dairy AI bulls was split-filtered through a Sephadex G-15 filter and frozen in a Tris-citric acid buffer egg yolk-based extender. The effect of filtration was studied morphologically for individual sperm abnormalities. Computer-assisted sperm analysis (CASA) was used for motility and sperm motion assessment. Flow cytometry was used to disclose sperm viability (SYBR-14/PI), mitochondrial membrane potential (Mitotracker Deep Red/SYBR 14), acrosome integrity (SYBR 14/PE-PNA/PI), plasma membrane stability (Merocyanine 540/YO-PRO 1/Hoechst 333342), and chromatin stability (acridine orange staining). Filtration significantly reduced the concentration of recovered spermatozoa (P < 0.01), but improved semen quality, reducing the number of spermatozoa with various forms of morphological defects. Filtration also affected percentages of sperm motility after equilibration and after freezing/thawing. Sperm motion characteristics were, however, not significantly affected by filtration at any stage of the cryopreservation protocol, including post-extension, equilibration, or freezing/thawing. Filtration enhanced sperm viability after thawing (P < 0.05), but had no significant effect (P > 0.05) on recovery of spermatozoa with high mitochondrial potential, intact acrosomes, or preserved sperm chromatin structure. Sperm plasma membrane stability was also not affected by the filtration method used (P > 0.05). It can be concluded that filtration effectively separates weaken or abnormal spermatozoa in pre-freezing semen samples and therefore the procedure could be recommended to improve post-thaw sperm viability of selected, fertile sires.