Effects of repeated superovulation and surgical oocyte collection on ovarian response and natural breeding ability of the tammar wallaby (Macropus eugenii).

The aim of this study was to assess the response of a marsupial, the tammar wallaby (Macropus eugenii) to repeated 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 administered 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 collected 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 treatment. 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 superovulation. Combined with other reproductive technologies, repeated superovulation has the potential to increase the production of offspring from rare or valuable marsupials in captivity.