Comparative efficacy of coconut water diluent with different semen extenders for cryopreservation of Nili Ravi buffalo bull semen

Abstract

In this study, efforts were made to investigate fresh semen parameters and to select a suitable extender for buffalo semen cryopreservation. Experiment I, fresh undiluted seminal parameters were determined while Experiment II, efficacy comparison of coconut water extender (CWE) with tris citric acid extender (TCAE) and skimmed milk extender (SME) was made. Four bulls single ejaculate was collected weekly for 5 and 10 weeks for Experiment I and II, respectively however osmotic pressure replicates were 16 and 6 for semen and seminal plasma, respectively. In Experiment I, each bull spermatozoa concentration, motility (%), semen volume and pooled semen percentage NAR, PMI, viability and MTT (3-(4, 5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide) reduction rate was checked. In Experiment II, pooled semen added to extenders and then equilibrated (4oC) and filled to obtain 20×106 spermatozoa/0.5 ml straws before plunging in liquid nitrogen. Percentage thawed spermatozoa viability, normal acrosomal ridge (NAR), motility, DNA damage, plasma membrane integrity (PMI) and lipid peroxidation (nM) recorded. In Experiment I, seminal parameters as spermatozoa concentration (1226.43±71.48 million/mL), semen volume (2.84±0.14 mL), viability (90.05±0.71%), motility (77.13±0.71%), PMI (86.23±0.34%), NAR (94.67±0.30%) and MTT reduction rate (0.290±0.06) while osmotic pressure of seminal plasma (294.83±3.87 mOsm/kg) and semen (290.87±2.58 mOsm/kg) was recorded. In Experiment II, TCAE higher (P<0.05) sperm motility noted compared to CWE and SME whereas percentage viability, NAR, PMI, DNA damage was non-significant. Lipid peroxidation compared to SME and TCAE was higher (P<0.05) in CWE. In conclusion, based on sperm motility and lipid per oxidation, TCAE was more efficient for cryopreservation of buffalo semen.