Effects of post-mortem storage conditions of bovine epididymides on sperm characteristics: investigating a tool for preservation of sperm from endangered species

To preserve genetic diversity in threatened populations of domestic and wild animals, cryopreservation combined with reproductive technologies are useful. Here, we present a reliable and efficient protocol enabling preservation of epididymal sperm using domestic cattle as a model species. We propose that this technique has great potential in conservation of threatened species because it can be used to rescue genetic variation in the event of unexpected death, castration or in situations where obtaining an ejaculate is not feasible.AbstractThe aim of this study was to establish and validate a reliable and efficient protocol for the recovery and cryopreservation of epididymal spermatozoa used for in vitro fertilization, using bulls of two different age classes. Testicles from 26 (37–51 weeks old, group 1) and 19 (52–115 weeks old, group 2) Danish Holstein bulls were collected after slaughter and stored at 5°C. After 0, 24 or 48 h, epididymides were isolated and spermatozoa collected. Assessments included spermatozoal motility, viability and morphology before and after cryopreservation and in vitro embryo production. Results showed that live spermatozoa can be collected from epididymides of bulls after their death. Storage of the testicles at 5°C for 24 h followed by cryopreservation of recovered epididymal spermatozoa resulted in 21% (group 1) and 31% (group 2) blastocysts produced in vitro. These results illustrate that epididymal spermatozoa recovered from testicles kept in specific conditions can be used to preserve genetic material from endangered and threatened species or populations in nature as well as in domestic and zoo animals.