Assessment of viability, chromatin structure stability, mitochondrial function and motility of stallion fresh sperm by using objective methodologies

Methodologies, such as flow cytometry and computer assisted sperm analysis (CASA), provide objective, reproducible, rapid and multi-parametric evaluation of semen quality. In this study, semen samples collected from six stallions were analysed for viability (by propidium iodide), chromatin stability by sperm chromatin structure assay (SCSA) and mitochondrial membrane potential by JC-1 using flow cytometry. Total and progressive motility, average path velocity (VAP), curvilinear velocity (VCL) and straight-line velocity (VSL) were determined by CASA system. The cytofluorimetric analysis provided results with low intra-assay variability respect to motility analysis by CASA system. The data on viability and mitochondrial assessment were rather uniform between stallions. The SCSA was able to distinguish potential fertility levels between stallions. In fact statistical differences were found between stallions especially for %-DFI and SD-DFI parameter. The %-DFI parameter was negatively correlated with VCL parameter. The higher repeatability of %-DFI parameter respect to those of other SCSA parameters confirms the importance of this parameter notoriously related to fertility. In conclusion, the simultaneous assessment of different functional sperm parameters, by flow cytometry and CASA, may be allow to obtain detailed and repeatable evaluations of sperm quality in the stallion, usually not considered in breeding selection programs.