title: The role of photoperiod on the initiation of the breeding season of the brushtail possum (Trichosurus vulpecula).
abstract: The role of photoperiod on the initiation of the breeding season of brushtail possums was investigated in possums housed in three light regimens: a short-day, a natural and a long-day photoperiod. Seven possums were housed in a natural photoperiod. Four possums were transferred to a short-day photoperiod (10 h light, 14 h dark) and eight possums to a long-day photoperiod (14 h light, 10 h dark) on 22 November, when the daylength was 13.34 h. The first rises in plasma progesterone concentrations were observed on 9 January +/- 9 days (n = 4), 11 March +/- 6 days (n = 7) and 6 May +/- 6 days (n = 8), for possums held in short-day, natural or long-day photoperiods respectively. Similarly, births were observed on 12 January and 14 February in the short-day group, from 3 March to 8 May for the natural photoperiod group, and from 5 May to 8 August for the long-day group. These results suggest that photoperiod is important in the timing of the breeding season. However, annual breeding will commence in a nonstimulatory long-day photoperiod. Thus a long-day photoperiod does not prevent breeding activity.
authors.affiliation: Department of Anatomy, University of Queensland, Brisbane, Australia.
authors.forename: R T
authors.initials: RT
authors.lastname: Gemmell
authors.forename: C
authors.initials: C
authors.lastname: Sernia
mesh_terms: D000818:Animals; D005260:Female; D008027:Light; D008394:Marsupialia / Q000097:blood / Q000502:physiology*; D010507:Periodicity; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012098:Reproduction / Q000502:physiology*
chemical_list: D011374:Progesterone