Deslorelin implants control fertility in urban brushtail possums (Trichosurus vulpecula) without negatively influencing their body-condition index

CSIRO Wildlife Research (Impact Factor: 1.38). 01/2009; 36(4):324–332. DOI: 10.1071/WR08050

ABSTRACT Wild brushtail possums (Trichosurus vulpecula) occur in large numbers in the grounds of Perth Zoo, Western Australia. These possums are a problem because they consume feed the zoo buys for its captive animals, damage seedlings and trees and many need to be treated for injuries sustained during fights with conspecifics. A contraceptive implant, which contains the gonadotrophin releasing hormone (GnRH) agonist deslorelin, could be a potential method of managing this population. We tested the efficacy of the implant and its impact on the body-condition index of treated possums with Kaplan–Meier analysis and a mixed model with residual maximum likelihood. We implanted 60 female possums with deslorelin and monitored reproductive success of treated and untreated possums for the following 18 months. At the conclusion of the study, 80% of 20 treated females recaptured had shown no evidence of breeding activity, giving an average minimum duration of effective contraception of 381 days. The implant did not have a negative impact on the body-condition index of treated possums during the course of the study. Our results suggest that deslorelin implants could be an effective management tool for brushtail possums at Perth Zoo and in other urban environments.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel experimental model was developed in cattle to investigate the requirement for FSH and LH during ovarian follicle growth and development. On Day 5 of the estrous cycle, 7 heifers were each implanted with an osmotic minipump containing a GnRH agonist (GnRHa), Buserelin (release rate, 2.5 micrograms/h). Another 7 heifers served as controls. Each minipump was replaced 28 days later with a second pump, which was left in place for a further 20 days. Blood samples were collected daily throughout the experimental period, and frequent samples were also collected on both days of minipump insertion and at 10 days after insertion of the second pump. The ovaries of all heifers were scanned daily by real-time ultrasonography to monitor follicular dynamics. All controls displayed 2 or 3 waves of FSH and follicular development per estrous cycle during the experiment. Insertion of the first minipump produced a large LH and FSH surge and induced ovulation in all 7 animals. Within 8 days of the start of treatment, serum LH concentrations fell to basal levels; they then remained constant at this level throughout the infusion period, only beginning to recover 4-5 days after the termination of infusion. After the initial increase, FSH returned to basal levels before showing a normal wave that was coincident with the emergence, growth, and regression of a dominant follicle. However, despite the peak levels of FSH, dominant follicles from the next wave failed to grow beyond 7-9 mm; they remained at this size for 3 wk until 3-4 days after insertion of the second minipump, when FSH fell precipitously to reach low levels that were maintained throughout the remainder of the infusion. After this fall in FSH concentrations, these follicles regressed rapidly, and no antral follicles > 4 mm were detected until after the termination of treatment. Thereafter, FSH concentrations increased significantly; the increase was accompanied by the emergence of a follicular wave and development of a dominant follicle, with estrus observed 8-11 days later. In conclusion, this study has demonstrated clearly that in cattle the early stages of follicle development (< or = 4 mm) are not dependent on acute support by gonadotropins. However, FSH is required for further growth of follicles up to 9 mm, while LH pulses are indispensable for follicle development beyond 9 mm in diameter. The model developed in this study should be valuable for studying the control of ovarian follicle development and atresia in vivo.
    Biology of Reproduction 08/1996; 55(1):68-74. · 4.03 Impact Factor
  • Journal of Endocrinology 10/1962; 25:119-36. · 4.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two hundred possums were collected from an area in Westland, New Zealand. Their carcasses were macerated and total fat content was determined by chemical means. The reliability of existing indices (visual, kidney fat, back fat, marrow fat) for predicting the proportion of total fat in the body was investigated. Two indices were developed and tested; one based on fat depots in the mesogastrium, the other based on deviations from a standardized weight for length. The index based on weight deviations gives good results if derived from a large sample of animals, and has the advantage that it can be used on live animals under sedation. The marrow fat index gives good results if fat reserves are low, and the mesogastric index does at other times, when estimates are obtained by autopsy of a few animals. Analysis of variance showed that, within the population studied, time of the year and a season-age interaction were the only significant sources of heterogeneity in fat reserves.
    Australian Journal of Zoology - AUST J ZOOL. 01/1970; 18(4).


Available from
Jun 3, 2014