The Development of Assisted Reproductive Techniques for Managing Maned Wolves (Chrysocyon brachyurus) Ex situ
Date
2013-02-12
Authors
Johnson, Amy E. M.
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Abstract
The maned wolf, a neotropical canid, is currently threatened due to habitat loss, road mortality and human-wolf conflict. The global captive population serves as an ‘ark’ for retaining genetic diversity in the event of severe stochastic changes to the wild population. However, the captive population is declining in gene diversity due to a small and aging population and poor reproductive output. The development of assisted reproductive techniques, such as sperm cryopreservation and artificial insemination (AI), has the potential to enhance genetic management but a lack of basic knowledge pertaining to the reproductive biology of the maned wolf is delaying this process. Specific objectives of the study were to 1) investigate susceptibility of maned wolf spermatozoa to osmotic stress by examining sperm viability after exposure to hypertonic solutions and dilution back into isotonic medium; 2) determine the effects of cryoprotectants, cooling and warming rates on cryosurvival of maned wolf sperm through evaluating post-thaw survival of samples cooled and warmed at various rates in the presence of different cryoprotectants; and 3) investigate the influence of management conditions on female’s response to hormonal induction of ovarian activity and ovulation by utilizing fecal gonadal steroid monitoring. The results obtained from this study suggest that maned wolf spermatozoa are highly susceptible to dehydration but are tolerant of exposure to cryoprotectants (1 M glycerol and 1 M DMSO). Additionally, optimal cryosurvival of maned wolf spermatozoa can be achieved by using 1 M DMSO as a cryoprotectant along with a rapid warming rate (50 C for 10 s). Furthermore, a field-friendly dry shipper approach achieves similar post-thaw motility to the other cooling methods used in this study (7 cm above LN2 or 3 cm above LN2). Finally, a 2.1 mg deslorelin implant consistently induces ovarian activity and ovulation in paired, but not singleton, female maned wolves. However, exogenous recombinant luteinizing hormone (reLH; 0.0375 mg) induces ovulation in singleton females after the induction of ovarian activity with deslorelin. The findings obtained from this research greatly improve our understanding of maned wolf physiology, specifically sperm cryosensitivity and female reproductive biology, while also providing insights into improved comparative approaches for sperm cryopreservation and induction of ovarian activity for timed AI.
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Keywords
Sperm cryopreservation, Maned wolf, Induced ovulation, Artificial insemination, Osmotic stress, Canid reproduction