Open access publications in the SLU publication database

Abstract

Chilling and freezing of spermatozoa permits transport and exchange of genetic material over distance. Frozen spermatozoa, which can be preserved over longer periods, can contribute to widening the gene pools of endangered canids and felids, as well as of domestic dogs and cats. In the present study different storage methods for dog and cat spermatozoa were evaluated. The viability of dog spermatozoa that had been cold stored for 1–2 days prior to freezing was assessed. The results revealed that there was no significant deterioration in motility, sperm plasma membrane integrity or acrosome integrity post-thaw. The results suggest that it would be possible for dog owners to collect semen nearer home and send it chilled to a semen bank for freezing and long-term storage. In the cat, we investigated susceptibility to cold shock and the beneficial effects of egg yolk in the extender used for cold storage. The results of these studies indicate that neither epididymal nor electroejaculated cat spermatozoa are susceptible to cold shock, and that 20% egg yolk in the extender is beneficial for motility and acrosome integrity in epididymal and electro-ejaculated cat spermatozoa. Electroejaculated spermatozoa proved superior to epididymal spermatozoa from the same tomcats in terms of motility, sperm plasma membrane integrity and acrosome intactness. The sperm-zona binding capacity of dog and cat zona pellucidae (ZPs) was tested using a zona pellucida binding assay (ZBA). In the dog the aim was to test whether different oocyte pools differed in their sperm-binding capacity, and whether 1- or 4-hour co-incubation was required. The results revealed that variation in oocytes should be taken into account when performing the ZBA, and that 1-hour co-incubation of spermatozoa and oocytes appears to be sufficient for fresh and chilled spermatozoa, but not for frozen-thawed (FT) spermatozoa, depending on the freezing medium used. A ZBA for cats was also performed to determine whether FT oocytes could be used (as in the dog) and whether they have equal binding capacity to fresh, in vitro-matured (IVM) oocytes. It was concluded that FT oocytes are not suitable for ZBAs in the cat.