Post-thaw Quality of Modified Dextran Swim-up Separated Bull’s Semen Fractions

Abstract

Development of alternative, less harmful and feasible sperm sexing procedures through swim-up technique are cost-effective and highly desirable for domestic animals, especially bulls. Hence, the study was planned to assess fresh and post-thaw sperm quality after dextran swim-up separation. Semen was collected from four bulls to evaluate sperm quality, and separated fractions were divided into two groups (10 and 15 min.) according to the time allowed for swim-up separation using dextran transition layer and later cryopreserved using Tris-based extender. It was observed that concentration of spermatozoa and progressive motility% significantly (P<0.05) and motility% insignificantly (P>0.05) decreased in all fractions of two groups in comparison to fresh whole semen. We found significantly (P<0.05) the highest concentration of spermatozoa in Fraction 1 in both time groups. No significant (P>0.05) difference was observed in different parameters except motility% of Fraction 4 of two groups. Notably, there was no significant (P>0.05) difference found in kinematic parameters of fractioned semen collected at 10- and 15-minutes interval. After freezing and thawing, motility% and progressive motility% significantly (P<0.05) decreased in all fractions irrespective of groups. The highest post-thaw motility (45.57±7.54) and progressive motility% (5.42±1.50) was observed in Fraction 2 and Fraction 4 of 15 min group, respectively. This preliminary study could help animal andrologist to design sex preselective semen preparation protocol in a cost-effective way.