Influence of bovine follicular fluid on thawed bovine spermatozoa - assessment by CASA system and flow cytometry

The aim of this study was to analyze the effect of bovine follicular fluid on the survival, morphology and kinetic parameters of bovine thawed spermatozoa under laboratory conditions.

The semen from 5 bulls of proven fertility was incubated in follicular and physiological fluid for 8 hours. During this time assessment using the CASA system was performed. At the beginning and the end of incubation process evaluation by flow cytometry was conducted.

The results of the sperm motility assessment showed a significant decrease in the analyzed parameters both in the follicular and physiological fluid. A significant reduction in all parameters characterizing movement properties in the semen incubated in the follicular fluid was found. In the physiological fluid, a similar trend was demonstrated only for the following properties: VAP, VSL, VCL, ALH, BCF. A significant difference was found for both fluids in: VCL (p=0.026), ALH (p=0.038) and LIN (p⟨0.001) at the beginning of incubation. The results of the plasma membrane integrity assessment showed a statistically significant increase in the percentage of dying sperm at the 8th hour of the incubation in the follicular fluid. In the case of semen incubation in physiological fluid, a statistically significant decrease in the percentage of live non-damaged cells was found with a simultaneous increase in the subpopulation of undamaged dead cells.

Follicular fluid rapidly accelerates the capacitation process. The results of flow cytometry support the hypothesis concerning the ability of follicular fluid to prolong sperm survival.