Effect of Cryopreservation on Casa Characteristics, Mitochondrial Transmembrane Potential, Plasma and Acrosome Integrities, Morphology and in vivo Fertility of Buffalo Bull Spermatozoa.

Background: Application of frozen-thawed semen is an important tool for improving the vivo fertility, but the process of freezing and thawing causes significant damage to spermatozoa.

Objective: The aim of this study was to evaluate the effect of cryopreservation on CASA characteristics, mitochondrial transmembrane potential, plasma, and acrosome integrities, morphology and in vivo fertility of buffalo bull spermatozoa.

Methods: Semen was collected from four mature buffalo bulls with artificial vagina at 42 °C. Ejaculates having > 1 mL volume, > 60 % sperm visual motility and > 0.5 x 109 sperm/mL concentration from each bull were diluted in Tris-citric acid egg yolk glycerol extender (TCA) making two aliquots per bull for analysis at post dilution and cryopreserved respectively.

Results: Analysis of variance (ANOVA) showed that the process of freezing and thawing significantly reduced (P < 0.05) CASA characteristics including total motility (TM, %), progressive motility (PM, %), rapid velocity (RV, %), average path velocity (VAP, µm/sec), straight line velocity (VSL, µm/sec), curvilinear velocity (VCL, µm/sec), beat cross frequency (BCF, Hz), straightness (STR, %) and linearity (LIN, %). Furthermore, the process of freezing and thawing significantly reduced (P < 0.05) subjective motility (SM, %), Supra-vital plasma membrane integrity (SVPMI, %), high mitochondrial membrane potential (HMMP, %), viable spermatozoa with intact acrosome (V/IACR, %). Moreover, it was observed that the freezing thawing process significantly decreased the in vivo fertility (%, 50.35 % vs. 61.39 %; P < 0.05) as compared to post diluted semen.

Conclusions: It is concluded that the process of freezing and thawing significantly reduced semen quality and in vivo fertility of buffalo bull in terms of various functional parameters.