Effects of repeated electroejaculations on kinematic sperm subpopulations and quality markers of Mexican creole goats

Abstract

Here we show the effects of repeated electroejaculation (EE) on mean values of motility, mitochondrial functionality, and expression of active caspases on goat sperm obtained by EE. Evaluations were done using CASA and flow cytometry. A strategy for identification of kinematic sperm subpopulations, when individual data of sperm are not provided by the CASA system, is provided. Fifty semen samples, five of each of ten adult creole goats, were obtained by electroejaculation. Mean values of total motility, progressive motility and flow cytometry evaluations were compared among EEs. Relationships among mean values of variables were investigated using Spearman correlation and principal component analysis (PCA). For identification of kinematic sperm subpopulations, PCA followed by hierarchical clustering was applied on data of the intervals provided automatically by the CASA system. Total motility does no change after repeated EE. Mean values of motility parameters and molecular markers were unrelated in multivariate space, but bivariate correlations were found. Values in upper and lower intervals defined clearly the sperm subpopulations, which had motility parameters changing over time. Taken together, our results show that repeated EE does not affect mean values of total motility, that molecular markers are not related with motility parameters, and that it is possible to identify kinematic sperm subpopulations when individual data, of motility parameters, are not provided by the CASA system.

Keywords: Computer assisted semen analysis; Electroejaculation; Flow cytometry; Goat; Multivariate graphics; Multivariate statistics.