Effect of relaxin on semen quality variables of cryopreserved stallion semen.

This research studies the effect of relaxin, a protein hormone, on the quality of frozen and thawed stallion sperm. It finds that adding relaxin to the solution used for freezing the sperm improves some measures of its quality.

Objective of the study

• The researcher’s intention was to assess the influence of different concentrations of relaxin supplemented to the semen preservation solution during the pre-freezing stage on the quality variables of previously frozen and thawed stallion sperm. This investigation addresses the need to improve sperm preservation procedures to maintain the conception potential of stallion sperm.

Research Methodology

• Stallion semen samples were collected, cleaned and diluted in skim milk.
• These diluted samples were then subjected to centrifugation to extract sperm pellets.
• Pellets were suspended in a specific freezing medium known as BotuCrio to prepare a defined concentration of sperm.
• These semen samples were split into five groups supplemented with varying relaxin doses of 0 (control), 12.5, 25, 50, or 100 ng/mL.
• The semen was then packed in straws, settled at 5 °C for 30 minutes, placed in liquid nitrogen vapour for 15 minutes and moved into liquid nitrogen for freezing.
• Post-thaw, sperm samples underwent quality assessments including motility and speed variables, mitochondrial membrane potential, cell death (apoptosis), and the integrity of plasma membrane and DNA.

Major Findings

• For sperm motility factors, the researchers observed both dose and time-dependent effects.
• The highest performance was noted when relaxin in the amounts of 12.5 and 25 ng/mL was used during the pre-freezing incubation stage for 0-120 mins.
• In all evaluations, the addition of relaxin to the semen diluent resulted in a significant increase in sperm mitochondrial membrane potential and a lower percentage of apoptotic cells in comparison to the control group.
• The integrity of the plasma membranes and DNA remained unchanged with relaxin supplementations to the diluent.

Conclusion

• The study concluded that the addition of relaxin to the extender prior to sperm cryopreservation, particularly at concentrations of 12.5 and 25 ng/mL, had a positive impact on sperm quality variables.