Sperm subpopulations in boar (Sus scrofa) and gazelle (Gazella dama mhorr)semen as revealed by pattern analysis of computer-assisted motility assessments

The aim of this study was to test the suitability of "pattern analysis" for the exploration of data provided by computer-assisted semen analysis metho ds. Data sets derived from the examination of boar sperm responses to bicar bonate and caffeine (measurements on 3208 spermatozoa) and from studies of semen cryopreservation in Mohor gazelles (7278 spermatozoa) were reanalyzed . A nonhierarchical classification method was used to generate initial subg roups of spermatozoa (9 for boar, 13 for gazelle). The subgroup centroids w ere fused, yielding three boar sperm subpopulations and four gazelle sperm subpopulations distinguished by sperm behaviors. Bicarbonate and caffeine b oth induced major transitions (p < 0.0001) of boar sperm behavior, detected as shifts in group membership (from group 2, i.e., active but nonlinear mo vement, into group 1, i.e., linear, rapid movement). Some spermatozoa (appr oximately 3%) were refractory to both caffeine and bicarbonate. The gazelle sperm subpopulation structure was affected by the inclusion of equex (sodi um triethanolamine lauryl sulfate) in the cryoprotective diluents. Equex su ppressed the appearance of spermatozoa with erratic behavior (p < 0.0001; h igh curvilinear velocity, low linearity, low straight-line velocity) after cryopreservation. The proportion of these erratic spermatozoa was positivel y correlated with animal age (r = 0.68, p = 0.029). Pattern analysis reveal ed novel aspects of the data not seen in the original investigations and us efully supplemented the more standard data analysis approaches.