Addition of seminal plasma to post-thawing equine semen: what is the effect on sperm cell viability?

This research studied the effects of adding seminal plasma after thawing horse semen on sperm cell viability. Findings suggest that adding seminal plasma (autologous or homologous) can boost semen fertility by increasing the population of cells showing plasma and acrosomal membrane integrity.

Objective and Methodology

• The study aimed to establish the effects of adding seminal plasma to horse semen after it has been frozen and then thawed.
• A total of five ejaculates were collected from each of four stallions known to be fertile and then cryopreserved (frozen).
• The semen was divided into three groups for treatment: no seminal plasma addition (NOSP), addition of homologous seminal plasma (from a different healthy animal – HSP), and addition of autologous seminal plasma (from the same animal – ASP).

Findings

• The addition of 20% seminal plasma led to an increase in the cell population that displayed both plasma and acrosomal membrane integrity.
• The study found no effect on the total motility, the number of cells with mitochondrial membrane potential, or the sperm’s velocities.
• However, beat/cross-frequency, straightness, and linearity were reduced in the ASP and HSP groups.
• Unexpectedly, the addition of homologous seminal plasma reduced the proportion of cells with progressive motility and addition of autologous seminal plasma reduced the amplitude of the lateral head displacement.

Conclusion and Implications

• Considering the increase in the cell populations that had both acrosomal and plasma membrane integrity, it is proposed that adding seminal plasma (autologous or homologous) to thawed semen before insemination could possibly enhance the fertility of the semen.
• This could potentially be a significant finding for the field of equine reproduction management, possibly improving the outcomes of artificial insemination procedures.