Equine sperm-bound antisperm antibodies are associated with poor semen quality.

The research investigates the connection between antisperm antibodies (ASAs) and poor semen quality in stallions, and found that ASA binding is associated with poorer semen quality and is more prevalent in non-satisfactory breeders.

Objective and Methodology

• The objective of this study was to investigate the frequency of antisperm antibodies (ASAs) in semen samples from satisfactory and non-satisfactory breeder stallions, the effect of these ASAs on semen quality, and factors that might affect this diagnosis.
• 21 stallions were subjected to breeding soundness examinations. The researchers measured the percentage of two types of ASAs bound to the sperm, specifically, IgG and IgA.
• These measurements were made using flow cytometry, a technique used to measure physical and chemical characteristics of a population of cells or particles.

Results

• The frequency of IgA-bound spermatozoa was found to be higher in non-satisfactory breeder stallions than satisfactory ones, indicating a potential reason for the unsatisfactory breeding performance.
• IgG-binding or presence of IgG-positive ejaculates did not differ significantly based on the breeding performance of the stallions.
• IgG-positive stallions had lower total sperm motility, concentration, and total numbers than IgG-negative ones, especially in the first ejaculate, and fewer sperm concentration in the second ejaculate.
• IgA-positive stallions also had lower total sperm motility, normal spermatozoa, and total numbers compared to IgA-negative stallions in both the first and second ejaculates.

Seasonal Effects

• The study found that while IgG antigen binding did not show a seasonal trend, IgA binding was higher during the non-breeding season than the breeding season in the first ejaculate.
• This indicates that the presence of IgA ASAs can potentially be affected by external circumstances and might influence breeding performance based on the season.

Conclusion

• The presence of IgG binding was prevalent in both groups of stallions, but the IgA binding was, on average, higher and more common in non-satisfactory breeders.
• Both of these types of antisperm antibodies were associated with poor semen quality, indicating their role in infertility issues in stallions.
• While sexual rest and the season appeared to affect IgA binding, they did not have the same effect on IgG binding.