Density gradient centrifugation of sperm from a subfertile stallion and effect of seminal plasma addition on fertility.

The study examines whether selecting sperm using a silane-coated silica colloid gradient centrifugation could improve the pregnancy rates of a valuable but subfertile stallion. It concludes that using density gradient centrifugation does improve pregnancy outcomes but the addition of seminal plasma from a high fertility stallion doesn’t significantly affect results.

Objective of the Study

• The study aims to evaluate the impact of sperm selection through a silane-coated silica colloid gradient centrifugation on the fertility of a subfertile stallion and understand if the addition of seminal plasma from a fertile stallion can enhance the pregnancy rates.

Methodology

• The research was conducted over three breeding seasons.
• In the 2008 breeding season, simple centrifugation and density gradient centrifugation of sperm were compared.
• In the subsequent seasons (2009 and 2010), the study further evaluated the impact of adding 5% seminal plasma to the extender after sperm selection.
• For all the mares, a deep horn uterine insemination was carried out with semen containing a specific number of morphologically normal and progressively motile sperm, post the induction of ovulation using hCG.
• Pregnancy was diagnosed via ultrasonography 14 days after ovulation.

Results

• The results indicated that the method of sperm selection significantly influenced the pregnancy rates. Using a density gradient in sperm selection process yielded higher per-cycle pregnancy rates compared to using simple centrifugation.
• The addition of seminal plasma, however, did not significantly impact the pregnancy rates. The study recorded almost equal per-cycle pregnancy rates with or without seminal plasma addition.
• Another important observation was the decreasing fertility of the stallion with age over the different breeding seasons.

Conclusion

• The study concludes that density gradient centrifugation could improve the pregnancy rates in a subfertile stallion in commercial breeding programs. On the contrary, the addition of seminal plasma does not appear to have a significant impact on the fertility outcomes.
• The research further points to an age-related decrease in stallion fertility, which is an important consideration in commercial breeding strategies.