Sperm Motility Evaluation in Stallion Fresh, Cooled and Frozen Semen Using a Portable Computer‐Assisted Sperm Analysis System

Semen analysis is an important laboratory diagnostic test for stallions. Evaluation of sperm motility is integral to basic semen analysis and results are important for breeding management and clinical practice. Computer-assisted sperm analysis (CASA) allows objective sperm motility evaluation and increases analytical precision. The objective of the present study was to validate a portable CASA system (AndroScope). Fresh/cooled semen samples (33 ejaculates, 18 stallions) and frozen semen (40 ejaculates and one epididymal flush, 27 stallions) were evaluated using the AndroScope and the IVOS II CASA system ('gold standard'). Positive associations (R² = 0.31 to 0.83, p < 0.0001) between the systems were observed for all sperm motility estimates. The percentage of motile sperm was lower (p < 0.0001) with the AndroScope than with IVOS II (mean difference: -4.2%), but the percentage of progressively normal sperm did not differ between the two systems. Systemic differences were observed for sperm kinetic estimates. Sperm velocities, ALH, and BCF were lower (p < 0.0001) with the AndroScope, observations likely associated with the slower video acquisition frame rate used by this system when compared with the IVOS II (45 Hz vs. 60 Hz, respectively). In conclusion, the AndroScope produced precise results for all sperm motility parameters. The ability to identify and track sperm, and to analyse single sperm kinematics seemed similar to that of the 'gold standard' system used for validation. The AndroScope video acquisition frame rate must be taken into consideration when evaluating sperm kinetics and setting thresholds for classification of different motile sperm subpopulations.