Assisted reproductive technologies for endangered felids

Abstract

Assisted reproductive technologies (ART) could overcome many of the challenges associated with zoo-based conservation programs for
endangered felids. Although felids are 1 of the most well-studied groups of zoo species, our understanding of feline biology and the
protocols for ART in cats are still far behind what is available for rodents, livestock, and humans. The dangerous nature of these animals
has shaped experimental designs to study nondomestic cats and determined which ART are the most relevant. Domestic cats have been
produced by artificial insemination, in vitro fertilization, and embryo transfer, providing basic protocols that can be extrapolated to
nondomestic cats. Variation in estrous cycle dynamics among species and variable rates of spontaneous ovulation between individuals
necessitate the use of exogenous hormones for most ART procedures. For artificial insemination, pregnancies have been produced by
vaginal, uterine, and oviductal inseminations. Oviductal inseminations may be the most broadly applicable based on the minimal
number of sperm required, but these procedures are logistically challenging for large cats. In vitro fertilization is effective for producing
viable, early-stage embryos, but culture conditions for blastocyst production remain suboptimal. In addition, performing long-term
culture outside of the appropriate laboratory environment is problematic. Further optimization of oocyte and embryo vitrification
would expand the applicability of these technologies. Other research priorities are the development of methods for real-time cycle
monitoring and alternative gonadotropin products for stimulation of follicular development and ovulation. Finally, theriogenologists
are encouraged to contact their local zoos if they are interested in providing their expertise to these efforts.