Freezability of mithun (Bos frontalis) semen

Abstract

The present study was conducted to assess the freezability of the mithun semen. Post-thaw physicomorphological parameters (PMPs) such as post-thaw motility, viability, total sperm abnormality, integrity of acrosome, plasma membrane and nucleus and vanguard distance travelled in bovine cervical mucus by sperm (BCMPT) of ejaculates, biochemical attributes such as, aspartate amino transaminase (AST), alanine amino transaminase (ALT) and lactate dehydrogenase (LDH) and in vitro zona binding ability of spermatozoa with heterologous (buffalo) oocyte were studied in freezable and nonfreezable ejaculates. Ejaculates (50) were collected from healthy matured mithun bulls and grouped based on the post-thaw motility into freezable and nonfreezable. These selected ejaculates were extended with standard Tris egg yolk citrate glycerol extender and stored at ultra low temperature (–196°C). Post-thaw PMPs, binding index (BI) and binding % (BP) and biochemical profiles were examined with standard protocols. The results revealed that the PMPs, biochemical profiles, BI and BP differed significantly between freezable and nonfreezable ejaculates. The post-thaw motility was positively correlated with livability, intactness of acrosome, plasma membrane, nucleus and vanguard distance travelled by sperm and negatively correlated with post-thaw total sperm abnormality. It was concluded that the post-thaw PMPs and BI and BP were significantly higher, biochemical intracellular enzymatic profiles were significantly lower in freezable than in nonfreezable ejaculates indicates freezable sperm has functionally stable sperm structures and higher intactness of plasma and acrosomal membrane to motile faster and in forward direction to reach the fertilization site and successful conception.