The domestic cat as a model for endangered species: analysis of gamete maturation, cryopreservation and embryo development

© 2014 Serena BarnesThe domestic cat represents an accepted model to develop assisted reproductive technologies for non-domestic cat gamete management. Despite technological advances in other animal models, application to the domestic cat has been limited. It is likely that current methods have not been properly optimised for cat gamete management. The purpose of this research is to determine if assisted reproduction can be further optimised for the cat model by investigating and validating modifications to both male and female focused techniques. Specifically, this included research on the abilities of two media systems to support oocyte maturation in the domestic cat, to compare of the abilities of two cryopreservation protocols to support survival of epididymal cat spermatozoa, and to describe the composition of follicular fluid from pre-ovulatory follicles to understand the nutritional requirements of domestic cat oocytes during maturation to improve current formulations of maturation medium and thus potentially generating higher blastocyst development rates from IVM oocytes. Overall, the findings of this thesis highlighted the insufficiencies of current embryo production methods from IVM cat oocytes, likely due to poor maturation conditions as opposed to inadequate embryo culture medium. This necessitated the analysis of metabolites in follicular fluid in order to identify components that can be used to develop a physiologically relevant maturation medium. While both cryopreservation protocols equally supported post-thaw survival of epididymal cat spermatozoa, findings from this thesis suggest a concentration of 8 × 106 mL-1 should be used for fertilisation and metabolic assays of post-thaw epididymal cat spermatozoa, as fertilisation and blastocyst development were not different between chilled and frozen-thawed treatments at this concentration and lower concentrations reduced the quality of post-thaw epididymal cat spermatozoa. Finally, the metabolic profiles of cat reproductive cells and fluids not only highlight the importance of metabolism as a parameter for cell quality in spermatozoa, but also the unique requirements of domestic cat oocytes and embryos