Relationship of Breed and Seminal Quality With Protamination and DNA Integrity of Bovine Spermatozoa

During spermatogenesis, most histones are replaced by protamines in the process known as protamination. Protamine deficiency is one of the factors that contribute to DNA instability and damage, which can affect the fertility of bulls. The objective of this study was to evaluate the relationship of breed and seminal quality with the protamination and DNA integrity of bovine sperm. A total of 30 semen samples from five Guzerat bulls and five Blanco Orejinegro (BON) bulls were used. Motility and kinematics were evaluated with a CASA system, morphology by eosin-nigrosin staining and membrane integrity with the HOST test. DNA integrity, viability and protamination deficiency were assessed by flow cytometry (IP/CMA3). Linear models, correlation analysis and comparison of means by Tukey test were performed. The proportion of viable protaminated sperm (CMA3-negative) for BON and Guzerat was 78.9% ± 1.4% and 73.8% ± 3.1%, respectively (p < 0.05). DNA fragmentation was 0.60% ± 0.06% for BON and 0.34% ± 0.04% for Guzerat (p < 0.05) and was negatively correlated with protamination (-0.18, p < 0.01). Positive correlations of protaminated viable spermatozoa with total motility (0.68), progressive motility (0.66), membrane integrity (0.52), rapid sperm (0.71), average path velocity (0.44), linear (0.34) and curvilinear (0.54) velocities were found (p < 0.001). Protamination of bovine sperm correlates with semen quality and is influenced by bull breed.