Evaluation of the effect of laboratory methods on semen analysis and breeding soundness examination (BSE) classification in stallions.

The research investigates if the outcome of a stallion’s Breeding Soundness Examination (BSE) could vary based on the laboratory methods utilized for sperm analysis. The modern semen analysis techniques like Computer Assisted Sperm Motion Analysis (CASA) and Differential Interference Contrast (DIC) microscopy appear to provide more conservative estimates than traditional approaches, affecting the BSE outcome. However, these methods are unable to reliably predict varied fertility levels in highly fertile stallions.

Investigation Into Semen Analysis Techniques

• The research aimed to see if different laboratory methods, when applied to the BSE of a stallion, could affect the results. The BSE, recommended by the Society for Theriogenology, stipulates a stallion should have a minimum of one billion progressively motile, morphologically normal sperm (PMMNS) in the second of two ejaculates sourced one hour apart to be labeled as a Satisfactory Prospective Breeder.
• Formal evaluations of sperm motility, morphology, and concentration were conducted, with the hypothesis that the application of CASA and DIC microscopy would yield a more conservative figure of PMMNS.

Impact of Modern Techniques

• The researchers hypothesized that if CASA and DIC were used in the semen evaluation, fewer stallions would meet the historical standards set for the classification of a Satisfactory Prospective Breeder.
• Additionally, they wanted to see if the introduction of these modern technologies meant a more accurate prediction of a stallion’s fertility as compared to older, traditional methodologies.

Results of the Study

• The findings corroborated the hypothesis that when modern semen analysis techniques, such as CASA and DIC microscopy, were utilized, more conservative estimates of PMMNS were deduced than when traditional semen analysis techniques were utilised.
• It was found that the methodologies used could impact the results of the traditional BSE.
• However, none of the various techniques used in the study could convincingly predict different fertility levels among the sample group of moderately to highly fertile stallions.
• The only individual semen measure that had a significant connection with fertility was the percentage of morphologically normal sperm. This result was achieved through the application of DIC microscopy.

Implications of the Study

• The results suggest caution when applying the traditional ‘cutoff’ of 1 billion PMMNS for deciding breeding potential, especially when the aim is to differentiate between moderately and highly fertile stallions – regardless of the laboratory methods utilized for semen analysis.