Routine assessment of motility of ejaculated stallion spermatozoa using a novel computer-assisted motility analyzer (QualispermTM)

Visual motility analysis is the basis for routine quality evaluation of stallion semen, although its prognostic value for fertilizing ability is considered low. The present study evaluated the ability of a novel computer-assisted motility analyzer (QualiSpermTM) to determine the motility and velocity of ejaculated, extended stallion spermatozoa (collected from 10 stallions, 3 ejaculates/stallion) and following two different colloidal centrifugation methods (oneor twolayer), compared to visual evaluation by two independent operators. The QualispermTM instrument was able to retrieve and analyze ~10 times more spermatozoa per sample compared to routine visual estimation on the same time frame (~1,100 vs ~100 spermatozoa). The proportion of motile spermatozoa increased after the colloid-separation, compared to the extended ejaculates (P < 0.05) in some stallions. However, owing to the large variation seen among ejaculates and stallions, both for extended ejaculate (P < 0.05) as well as for the colloid centrifugations (P < 0.01), the differences were lost when the entire population was examined statistically. Interestingly, significant differences were seen for individual stallions between the measurements of QualispermTM and observers, as well as between observers (P < 0.05). Apart from the significantly higher number of spermatozoa analyzed at one time, the QualispermTM system provided a parameter that could simply not be estimated by visual assessment; mean sperm velocity (in μm/sec). Sperm velocity, upon which every computer assisted instrumentation base their evaluations, varied among stallions (and ejaculates within stallions, P < 0.05), with a tendency to increase after colloid-separation, thus suggesting the QualispermTM system might be able to differentiate sperm sub-populations. Due to its higher accuracy (in terms of sperm numbers examined) and speed, the QualispermTM system appears to be a suitable instrument for routine evaluation of equine semen.