Feline reproduction and artificial breeding technologies

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Increased interest in the domestic cat, both as a companion animal and as a model for rare felid species, has led to augmented research focusing on reproductive processes in this species. In the male, primary attention has been aligned to investigations of gamete retrieval and cryopreservation. Epididymal sperm cells obtained from reproductive tracts after neutering (simulating posthumous collection) do capacitate, as evidenced by attachment to homologous zonae with 30 min and maximum attachement after 4 h. Following cryopreservation, motility is observed, but is attenuated compared with pre-freeze values by 30–40%. However, this information does not correlate with fertilizing ability, as an average of less than 20% of the acrosomes remain intact post-thaw and fertilization rates are less than 2%. Investigations of non-invasive endocrine techniques have centered on the female and new methods for monitoring fecal steroids have been described and adapted to species such as the cheetah, lion, tiger, bobcat and serval. The most intense area of research has been development of artificial breeding techniques. Recently, a 50% success rate with laparoscopic artificial insemination has been demonstrated if semen deposition occurs after ovulation, whereas pregnancy rates are severely attenuated when insemination is performed before the ovulatory process. This technique now has been adapted to the leopard cat, cheetah, tiger and puma, with the birth of one offspring from each species. In vitro fertilization also has received much attention and results in 84–85% fertilization rates using Ham's F-10 medium with PMSG/hCG-stimulated cocytes (84 h between injections). Adaptation to non-domestic felids has resulted in the birth of one litter of tiger cubs and Indian desert cat. Salvage of female gametes by in vitro oocyte maturation and fertilization is a recently exploited area of research for the domestic cat. Approximately 50% of all oocytes placed in culture develop to the metaphase II stage, with gonadotropin-supplemented medium providing superior conditions for maturation. These oocytes are capable of undergoing fertilization (range, 11–36%), and embryos derived completely from male and female rescued gametes have been produced (fertilization rate, approximately 20%). Because of the enormous progress made with domestic cat artificial reproduction, the developed methods (e.g. semen cryopreservation, artificial insemination, in vitro fertilization, gamete salvage) will undoubtedly serve as important tools for strategic management of endangered species populations.