Current status of semen preservation in the ram, boar and stallion.

This research focuses on the challenges and limitations associated with preserving stallion semen, including the decreased fertility rate and need for more investigation into these issues.

Study Findings

• The research indicated significant barriers in both short and long term preservation of stallion semen.
• Notably, it was found that the extended or cooled spermatozoa have an impaired fertilizing capacity.
• With the use of hydrogen ion extenders, the observed fertility was reduced regardless of whether glycerol was present or not if the semen was inseminated immediately after extension.
• On the other hand, using cream-gel extender did not have any negative impact on fertility if inseminated immediately after extension. However, fertility was impaired if stored at 5° C for 24 hours or in the presence of glycerol.

Implications of the Findings

• The study also noted that the fertilizing capacity of the extended frozen spermatozoa was severely impacted. Interestingly, this impairment was not evenly distributed but varied significantly between individual stallions.
• Pregnancy rates ranged from 50 to 80% for raw semen from the same stallion in the frozen studies. However, as this shows a considerable difference, researchers caution against applying results from limited samples to the broader population.
• These findings suggest that while preservation of stallion spermatozoa is possible, the process hampers their fertilizing capacity to a certain extent. The root causes of this impairment need further investigation.

Future Research Direction

• Once the reasons for this impairment are better understood, researchers will need to revise evaluations about the number of motile spermatozoa needed per insemination and the frequency of insemination required for optimal fertilization.
• This study hence calls for further research to better understand these mechanisms, which, when resolved, can ultimately lead to effective long-term preservation of stallion semen.