Use of a computerized system for evaluation of equine spermatozoal motility.

Three ejaculates from each of 3 stallions were used to evaluate a computerized system (Hamilton-Thorn motility analyzer; HTMA) for measuring equine spermatozoal motility. Variance components (ejaculate-within-stallion, chamber-within-ejaculate, and microscopic field-within-chamber) were determined for each stallion after diluting ejaculates to 25 x 10(6) spermatozoa/ml with a skim milk-glucose seminal extender. The HTMA was compared with frame-by-frame playback videomicrography (VIDEO) for determining: percentage of spermatozoal motility and spermatozoal number in microscopic fields; curvilinear velocity and straight-line velocity of individual spermatozoa for 5 track types; and repeatability of those velocity measurements. The effect of spermatozoal number per microscopic field on incidence of intersecting spermatozoa and the outcome of intersecting spermatozoa also were evaluated. Greatest variability in motility measures was generally attributed to the microscopic field-within-chamber component. The HTMA was highly correlated with VIDEO for estimation of spermatozoal numbers per microscopic field (r = 0.99; P less than 0.001) and motility (r = 0.97; P less than 0.001); however over the entire range of spermatozoal numbers, the HTMA yielded higher spermatozoal numbers per microscopic field (P less than 0.05) and higher motility (P less than 0.05) than did VIDEO. The HTMA- and VIDEO-derived measurements of curvilinear and straight-line velocities were highly correlated for all spermatozoal track types, but both measures were higher (P less than 0.05) by use of the HTMA than by use of VIDEO for most track types. For 3 of 5 track types, measurements of curvilinear and straight-line velocities were less variable (P less than 0.05), using the HTMA, rather than VIDEO.(ABSTRACT TRUNCATED AT 250 WORDS)