Improvement of Post-Thaw Sperm Kinematics and DNA Integrity of Cross-Bred Bovine Sperm by Incorporating DGC as Selection Method Prior to Cryopreservation

Abstract

The aim of this study was to assess post-thaw sperm quality following initial sperm selection using density gradient centrifugation (DGC) prior to cryopreservation. Ejaculates from four mature Charolais cross Kedah-Kelantan bulls were collected using artificial vagina at IBVK Pahang, Malaysia. The ejaculates were aliquoted into 3 groups: non-cryopreserved group (NC); control group of cryopreserved sperm without DGC (ND) and treatment group of sperm undergoing DGC sperm selection before cryopreservation (CDGC). Prior to analysis, samples from both cryopreserved groups were thawed at 37 °C for 30 sec. All samples were analysed for kinematics parameters, viability and compromise in DNA integrity (evaluated as DNA Fragmentation Index, DFI). All kinematics parameters were analysed using computer aided sperm analysis (CASA). Results indicated significant (p < 0.05) kinematics parameter changes for all parameters of velocity (VCL, VSL, VAP) and progression (WOB, LIN, ALH and BCF). Unfortunately, changes in spermatozoa straightness were insignificant (STR) F(2, 68) = 1.004, p = 0.371. Spermatozoa viability had increased by 26.2% (p < 0.01) following the treatment. DFI revealed the treatment group recorded a significant reduction in DFI value (0.17% fragmented DNA). In conclusion, DGC sperm selection prior to cryopreservation reduced the effects of cryodamage and showed an improvement in post-thaw sperm quality, thus reducing the occurrence of asthenozoospermia in populations of frozen-thawed cross-bred bovine spermatozoa.