Avaliação da descompactação da cromatina de espermatozoides bovinos por três diferentes métodos

Abstract

Sires with a normal semen analysis can be classified as subfertile or they can have periods of subfertility because of its low reproductive performance. Changes in chromatin compaction of spermatozoa in cattle are found, and they are possible explanations for this kind of behavior. Therefore, this study was conducted with the objective to compare three different methods of analysis of sperm chromatin that can be used in the diagnosis of fertility bulls.Seven semen samples of subfertile cattle were evaluated using the three methods, which are them: flow cytometry (SCSA), toluidine blue staining (TB) and transmission electron microscopy (TEM). In samples stained with TB, semen samples were evaluated in case of decompaction and heterogeneity of chromatin. The SCSA evaluated the proportion of sperm heads stained in red (abnormal heads) and green (normal heads). In TEM evaluated the areas of heads with unpacking chromatin. As statistics evaluations were performed the Kruskal-Wallis test and as a post-test, Wilcoxon was also used. The Pearson correlation test was also conducted. There was positive and significant correlation between SCSA and TEM, besides the positive and significant correlation between TB and TEM. It was found a negative correlation between unpacking of chromatin and heterogeneity by TB, however there was no significant correlation between SCSA and TB. It was concluded that TEM identifies similar changes as in the SCSA test, and TEM is more sensitive for the identification of chromatin alterations in bull sperm than SCSA, and the computational image analysis stained with TB does not identify the same changes as in the SCSA.