Effect of Relaxin on Fertility Parameters of Frozen-Thawed Buffalo (Bubalus bubalis) Sperm

Relaxin (a regulatory-peptide) enhances cryotolerance, fertility potential and plasma reproductive hormones of Nili Ravi buffalo (Bubalus bubalis) during low breeding season

This study investigated the beneficial effects of relaxin on cryotolerance of buffalo spermatozoa and reproductive hormones during low breeding season. Collected semen was diluted in five aliquots with relaxin addition (0.25 mg/mL, 0.50 mg/mL, 0.75 mg/mL, 1 mg/mL, and control). After gentle dilution (37°C), cooling (4°C, 2 h), equilibration (4°C, 4 h), and packaging (straws, polyvinyl French, 0.5 mL), frozen (cell freezer), and thawed (37°C, 30 s) for analysis. Blood samples were collected at different time intervals i.e., -60, -30 and 0 min (pre-dose) and 30, 60, 90, 120 and 150 min (post-dose) from a jugular vein. This study manifest that adding relaxin (1 mg/ mL) in freezing medium ameliorates sperm motility, functionality (%), and seminal plasma total antioxidant capacity (TAC, μM/L) than control during low breeding season. Furthermore, we found that relaxin supplementation at 1 mg/mL significantly improves seminal plasma ATP concentrations (nmol/million) than control, 0.25 mg/mL, and 0.50 mg/mL, and fertility (control, and 0.75 mg/mL). Further, relaxin injection significantly improves plasma T, LH and IGF-1 levels (150 and 120 min vs. -60, and - 30), and FSH, KP, and GnRH concentrations (150 min vs. -60), during low breeding season. Taken together, this study revealed that relaxin ameliorates motility, functionality, and fertility of buffalo spermatozoa. Moreover, relaxin injection (1 mg/mL) improves essential reproductive hormones levels in buffalo signifying its importance in the field of reproductive physiology. Further studies are required to determine the exact mechanism of action of relaxin in enhancing semen quality, fertility and reproductive hormones.

Effect of Epidermal Growth Factor (EGF) on Cryopreserved Piedmontese Bull Semen Characteristics

The purpose of this study was to determine the effect on fresh and post-thaw beef bull semen quality of the supplementation of epidermal growth factor (EGF) to the semen extender at various concentrations (0-control, 50, 100, 200, and 400 ng/mL). For 8 weeks, sperm was collected from four fertile bulls, yielding a total of 32 ejaculates. Semen samples were pooled, diluted with Bullxcell^® extender, and then cooled, equilibrated, and frozen. After thawing, semen was tested for motility and velocity parameters. Furthermore, semen was evaluated for vitality, integrity, mitochondrial and antioxidant (SOD) activities, mucus penetration distance, and in vitro fertilizing capability. The supplementation with EGF prior to cryopreservation improved the total sperm motility at various concentrations over long incubation periods (from 1 to 4 h). Interestingly, EGF addition improved both progressive and rapid motility, particularly at 50, 200, and 400 ng/mL. In addition, EGF, primarily at 200 and 400 ng/mL, significantly increased several velocity parameters after different incubation periods. We can conclude that adding EGF to bull sperm extender before cryopreservation has a positive stimulatory effect on sperm motility without affecting vitality, integrity, or in vitro fertilizing capability.

A systematic review and meta-analysis of spermatozoa cryopreservation, in vitro and in vivo fertility practices in water buffalo

We explored different aspects of buffalo spermatozoa during cryopreservation. The meta-data comprised of 285 studies, published from January 2008 to March 2020. A free web tool CADIMA as well as PRISMA 2009 Flow Diagram were used for carrying out this study. The inter-reviewer agreement among studies allocated was satisfactory for criteria A (selection bias), B (performance bias), C (detection bias) and D (attrition bias), respectively. India led the percent (%) research ladder with 34.4, followed by Pakistan (29.5), Egypt (12.3), Iran (7.7), Italy (5.6), Indonesia (3.2), China (2.1), Brazil (1.4), Thailand (1.1), Philippines and Bulgaria (0.7 each), Saudi Arabia, Turkey, Vietnam, and USA (0.4 each). Among four categories of studies, Group-1 evaluated only supplements/additives/media in the freezing semen extender (n = 191/285; 67.02%); Group-2 conducted in vivo fertilization (n = 62/285; 21.75%) and Group-3 conducted in vitro fertilization/ cleavage rate/penetration rate/ blastocyst yields (n = 28/285; 9.82%) with their specific cryodiluents/media, respectively. Group-4 conducted different experimental supplements/additives/media and carried out both in vitro and in vivo fertilization simultaneously (n = 4/285; 1.40%). Conventional spermatozoa cryopreservation was reported by 51.9% studies followed by programmable fast freezing by 20.7% studies. A few leading extender types included BioXcell (3.9%); Soyamilk-skim (3.5%); and Andromed (2.1%). The study also describes French straws for semen filling, cooling temperatures, extension time, equilibration time, cryopreservation stages, thawing temperatures, seasons, thawing time, and stains used during semen evaluation assays. The study concludes that the research on spermatozoa cryopreservation of buffalo is largely conducted at quality level and a need of applying these findings for evaluation of fertility potential (in vivo and in vitro) is indispensable for effective genetic improvement.

Effect of relaxin on cryopreserved beef bull semen characteristics

This study aimed to improve the quality of cryopreserved beef bull (Piedmontese) semen by incorporation of relaxin in diluted semen before cryopreservation procedures. Semen samples were collected from 4 proven fertile bulls, using artificial vagina, once per week for 8 consecutive weeks and pooled together then diluted with Bullxcell® extender, and supplemented with different concentrations of relaxin (0 (control), 25, 50 and 100 ng/ml) before cooling, equilibration and freezing procedures. Frozen semen was thawed and assessed for motility by Computer-Assisted Sperm Analysis and vitality parameters such as acrosome, plasma membrane and DNA integrities, apoptosis, mitochondrial membrane potential, mucus penetration and SOD activity. The developmental potential of bovine embryos produced in vitro by using relaxin-treated was also investigated. In the present study, 50 and 100 ng/ml relaxin incorporation in extended bull semen before cryopreservation induced a reduction of sperm motility immediately after thawing (0h), whereas, during long incubation periods (1-2 h), relaxin showed a significant positive effect on sperm quality by improving the sperm motility and velocity parameters. Interestingly, sperm vitality was improved by 25 and 100 ng/ml relaxin and the blastocyst developmental rate was significantly increased in the 25 ng/ml relaxin group compared with controls (52/118, 44.0% vs. 32/116, 27.6%, respectively). These findings suggest a potential use of relaxin at the doses tested in the present study as an additive in the cryopreservation media of bull semen to improve sperm quality.

Effect of relaxin on semen quality variables of cryopreserved stallion semen

The aim of the study was to ascertain effects of different concentrations of relaxin added to extender medium during the pre-freezing incubation periods on quality variables of stallion frozen-thawed spermatozoa. Semen samples collected from three stallions were filtered, diluted with skim milk, and centrifuged at 600g for 10 min. Sperm pellets were suspended in BotuCrio freezing medium to a final concentration of 50 × 10⁶ sperm/mL. The diluted semen was divided into five experimental groups supplemented with 0 (control), 12.5, 25, 50, or 100 ng/mL of relaxin. The semen samples were transferred into 0.5 mL straws, equilibrated at 5 °C for 30 min, and placed in liquid nitrogen (LN₂) vapour for 15 min before being plunged into LN₂. After thawing, sperm samples were evaluated for motility and velocity variables, mitochondrial membrane potential, apoptosis, and plasma membrane and DNA integrities. For sperm motility variables, there were dose- and time-dependent effects, with the largest values recorded when 12.5 and 25 ng/mL relaxin were used for 0-120 min of incubation. Furthermore, at all of the concentrations at which there were evaluations, relaxin additions to semen diluent led to a marked improvement in sperm mitochondrial membrane potential and a lesser percentage of apoptotic cells compared to the control group. Plasma membranes and DNA integrities were not affected by relaxin supplementations to the diluent. In conclusion, supplementation of relaxin in extender before semen cryopreservation, especially at 12.5 and 25 ng/mL, had a positive effect on the sperm quality variables.