Reproduction (2003) 125, 701–707 Research Effects of repeated superovulation and surgical oocyte collection on ovarian response and natural breeding ability of the tammar wallaby (Macropus eugenii ) G. M. Magarey, J. C. Rodger, J. M. Buist and K. E. Mate ∗ Cooperative Research Centre for Conservation and Management of Marsupials, Department of Biological Sciences, Macquarie University, NSW 2109, Australia The aim of this study was to assess the response of a mar- supial, the tammar wallaby (Macropus eugenii ) to re- peated superovulation and surgical oocyte collection and monitor any effects on subsequent natural breeding ability. Animals (n = 5 per group) were superovulated once, twice or three times with pig FSH (pFSH; 6 mg ad- ministered twice per day for 4 days) followed by 4 mg pig LH (pLH). There was an interval of either 5–6 weeks (n = 9) or 12 weeks (n = 1) between the first and second superovulation and 13–17 weeks (n = 5) between the second and third superovulation. Oocytes were co- llected surgically after each treatment. Serum was collected at the time of each treatment to monitor the formation of anti-pFSH and anti-pLH antibodies. Animals were allowed to mate naturally in the season following superovulation treatment(s). There was no significant difference between groups in the number of large follicles (2–5 mm diameter, mean ± standard error) produced in response to the first (21.2 ± 4.3), second (18.0 ± 6.5) or third (29.0 ± 4.9) superovulation treat- ment. Eggs were recovered from approximately 80% of follicles that were flushed during laparotomy. There were significant concentrations of anti-pFSH and anti-pLH antibodies (P < 0.05) detected in previously superovulated animals at the time of the second superovulation but not at the time of the third superovulation. The anti- gonadotrophin antibodies present at the time of repeated superovulation did not cause a significant decrease in average number of follicles. All animals produced pouch young in the breeding seasons after repeated superovu- lation. Combined with other reproductive technologies, repeated superovulation has the potential to increase the production of offspring from rare or valuable marsupials in captivity. Introduction Assisted reproductive technologies are complex but increasingly important tools that can be applied to conservation (Rodger 1990; Holt and Pickard, 1999; Wildt et al., 2001). Successful application involves investigation and modification of each technology to suit the unique reproductive physiology of the target species, which is largely unknown for most threatened marsupials. The tammar wallaby (Macropus eugenii ) is an esta- blished marsupial model and has therefore been used to develop a number of reproductive technologies including superovulation (Molinia et al., 1998a), sperm cryopreservation (Molinia and Rodger, 1996; Taggart et al., 1996), artificial insemination (Molinia et al., 1998b; Johnston and Holt, 2001) and oocyte maturation (Mate and Rodger, 1993). Superovulation is a critically important technology for the tammar wallaby as it is *Correspondence Email: kmate@possum.bio.mq.edu.au naturally monovular and highly seasonal, with breeding restricted to the period of decreasing daylength between the summer and winter solstices (reviewed by Hinds et al., 1990). Superovulation protocols have been devel- oped for several other marsupials (Rodger and Mate, 1988; Rodger et al., 1992; Hickford et al., 2001), primarily as research tools. The repeatability and subsequent effects of superovulation on the donor have not been addressed in any marsupial, as oocytes or embryos are usually collected from animals during experimental studies. As repeated superovulation and oocyte collection potentially play a pivotal role in marsupial assisted breeding programmes, it is critical that they do not affect the future natural breeding ability of valuable animals. Laparoscopic oocyte collection after superovulation has been performed in the brushtail possum (Trichosurus vulpecula; Mate et al., 1992). However, details such as oocyte collection rate and subsequent fertility were not reported. Collection of follicular oocytes by laparoscopy or laparotomy is well established in many eutherian species including numerous ungulates (Loskutoff et al., c  2003 Society for Reproduction and Fertility 1470-1626/2003 Downloaded from Bioscientifica.com at 07/16/2020 11:45:09AM via Massachusetts Inst of Technology