Sperm indexes obtained using computer-assisted morphometry provide a forecast of the freezability of canine sperm

Abstract

Sperm morphometric indexes obtained after principal component analysis were used to investigate its value as diagnostic tests for freezability. Semen from six dogs was frozen-thawed following a standard protocol. Before freezing, computer-assisted analysis of sperm morphometry (CASMA) was performed. The principal component analysis (a statistical technique for simplifying a dataset, by reducing multidimensional datasets to lower dimensions for analysis) performed in the data obtained after the CASMA analysis gave four morphometric indexes. After thawing, ejaculates were evaluated for early changes in sperm membranes using the combination of two fluorescent probes, YO-PRO-1 and ethidium homodimer and flow cytometry. Significant differences in the percentages of intact membranes post-thaw were observed among dogs (p < 0.01). Significant non-parametric correlations were found between index 3 and the percentage of intact membranes after thawing (R = 0.432 p < 0.05). Receiving operating system curves demonstrate a good diagnostic value for indexes 2 and 3 in the prediction of freezability, with areas under the curve of 0.798 and 0.786, respectively. © 2007 Blackwell Publishing Ltd.