Measured effect of collection and cooling conditions on the motility and the water transport parameters at subzero temperatures of equine spermatozoa.

This study evaluates the impact of collection and cooling conditions on the movement and water transport parameters of horse sperm at below freezing temperatures. The researchers describe how cold shock and osmotic stress created by certain collection procedures can significantly change the water transport responses and motility of sperm, which in turn can affect the quality of samples that are cryopreserved or cold-stored.

Overview of the Study

• The research was prompted by previous findings regarding the effects of exterior ice and cryoprotective agents on equine sperm’s volumetric shrinkage response and membrane permeability parameters.
• The authors sought to determine how collection and refrigeration conditions influenced the motility and water transport characteristics of equine sperm at subzero temperatures.

Methodology

• The stallion samples used in the study were collected employing either a commercial lubricant that caused osmotic stress to the sperm or an artificial vagina lubricated with water-insoluble Vaseline.
• For some tests, the sperm was cooled at a rate of 1 degree Celsius per minute, from 20°C to 4°C to trigger a cold shock reaction.
• They also used an Equitainer to maintain controlled cooling rates (≤ 0.3 degrees Celsius min-1) at temperatures greater than 0 degrees Celsius.

Findings

• The research revealed that the water transport response in sperm specimens experiencing cold shock and osmotic stress significantly varied when compared to the control samples.
• While osmotic stress was seen to affect the water transport response, this impact was not considerable enough to be statistically significant.
• The study also found that osmotic stress led to a noticeable decrease in the motility of extended semen specimens, which could compromise the quality of cryopreserved or cold-stored sperm.

Conclusion

• The study concluded that cold shock changes the behaviour of equine sperm in cryopreservation procedures due to modifications in the water transport characteristics of the plasma membrane.
• Although osmotic stress did not significantly influence equine sperm water transport, it played a significant role in decreasing sperm motility, which could then lower the quality of cold-stored or cryopreserved sperm.