A comparative analysis of sperm selection procedures prior to cryopreservation for Nili-Ravi buffalo bull (Bubalus bubalis) semen-: Assessment of its impact on post-thaw sperm functional quality

Abstract

Sperm selection techniques have been developed to get sperm suspensions enriched in motile and functional cells. Studies show that selection before cryopreservation improves post-thaw quality of cryopreserved sperm but information on buffalo bull sperm is scarce. The study was aimed to 1) perform a comparative analysis of sperm selection procedures; Swim-Up (SU), Sephadex™-G15 Filtration (S-G15) or Glass Wool Filtration (GWF) for total and motile cell recovery, 2) to assess the impact of sperm selection prior to cryopreservation on sperm quality (motility, morphology, cell membrane and normal apical ridge, viability and livability, chromatin integrity) and sperm functionality (Embryo Cleavage after IVF with selected sperm) in post-thawed suspensions of buffalo bull sperm. Semen was collected from 5 Nili Ravi buffalo bulls maintained at the Semen Production Unit Qadirabad, District Sahiwal, Pakistan. Ejaculates were divided into four aliquots for SU, S-G15 and GWF and control. After sperm selection, total and motile sperm recovery was highest in GWF samples (total sperm=84.08±8.39%; motile sperm=80.42±3.57%). An improvement (P<0.05) in all post-thaw parameters was observed in S-G15-selected sperm and, in some parameters in GWF-filtered sperm suspensions compared to control. The highest (P<0.05) embryo cleavage rate (%) was achieved with frozen-thawed sperm selected with S-G15 prior to cryopreservation (44.72±4.18) compared to control (21.98±3.00). In conclusion, post thaw sperm quality was improved after sperm selection from fresh buffalo bull semen through S-G15 and GWF procedures compared to SU and control while, the fertility rate (cleavage rate) was improved with sperm processed using the S-G15 procedure.

Keywords: Buffalo bull spermatozoa; Cryopreservation; Filtration; Glass wool filtration; Sephadex™; Swim up.