Fresh and post-thaw sperm quality after epididymal retrograde flushing in dogs and rabbits

Abstract

Cryopreservation of spermatozoa is an essential tool in reproductive biotechnology, but the freezing and thawing process can significantly impact sperm quality, particularly in epididymal spermatozoa, which are more sensitive to cryodamage. This study aimed to evaluate the effects of two different TRIS-based extenders and two thawing protocols on the post-thaw quality of epididymal spermatozoa collected from dogs and rabbits. Epididymal sperm was collected post-castration using retrograde flushing. Fresh sperm quality was assessed by evaluating sperm motility, vigor, viability, acrosome integrity and sperm abnormalities. The samples were then cryopreserved using two extenders with different TRIS concentrations (198 mM and 248 mM). Frozen samples were thawed using two different protocols: 37°C for 30 seconds and 70°C for 8 seconds. In dogs, spermatozoa preserved relatively high post-thaw quality, particularly in the group using the higher TRIS concentration and thawed at 70 °C. Rabbit spermatozoa demonstrated a marked decrease in all quality parameters after thawing, regardless of protocol. However, 37 °C thawing condition yielded slightly better motility outcomes. This study provides valuable insights into the impact of extender composition and thawing protocols on epididymal sperm preservation in dogs and rabbits. Understanding these factors can contribute to optimizing cryopreservation techniques for improved sperm functionality in both species.