Preliminary investigation into the prevalence of mucormycosis in the platypus (Ornithorhynchus anatinus) in three catchments in north-west Tasmania.

OBJECTIVE: To investigate the distribution and prevalence of mucormycosis in platypus (Ornithorhynchus anatinus) from the Inglis, Emu and Black-Detention catchment areas in north-west Tasmania. PROCEDURE: A field study was performed and resulted in the examination of 44 wild platypuses; in addition, one dead platypus and two live platypuses were examined after they were independently submitted to a local veterinary clinic. RESULTS: No cases of mucormycosis were conclusively diagnosed. One platypus with signs consistent with those previously described in cases of mucormycosis was captured in the Emu River catchment. However, laboratory tests did not provide a definitive diagnosis for the lesion. Two platypuses from the Inglis catchment area had signs very similar to those previously described in cases of mucormycosis, but laboratory tests found Corynebacterium ulcerans to be the likely cause of the cutaneous ulcers on one of these platypuses and an unidentified fungal agent to be the cause of a cutaneous nodule in the other. CONCLUSIONS: These findings do not prove that mucormycosis is absent from the populations studied. However, they may indicate that the prevalence of disease is low. The possibility that Mucor amphibiorum is present in a subclinical form in platypuses, or infecting another reservoir, is not excluded. The findings also suggest that caution should be exercised when diagnosing mucormycosis based on clinical findings alone and raise the possibility that some cases may have been incorrectly diagnosed.

Milk consumption and growth in a marsupial arboreal folivore, the common ringtail possum, Pseudocheirus peregrinus.

This study examines the milk consumption and growth energetics of the smallest arboreal folivore in Australia, Pseudocheirus peregrinus. Mass increase was sigmoidal, and young ceased sucking milk between 27 and 30 wk (mean = 29.3 +/- 1 wk). This length of lactation was 129% of that predicted allometrically from data for other marsupials. The mean Gompertz constant (0.01) calculated for seven young suggests that P. peregrinus has a slow rate of growth compared with other marsupial species. Milk intake was measured with isotopic turnover techniques. The estimated total milk energy yield (11.9 MJ kg-1) for a ringtail possum suckling two young was similar to that of the only other marsupial herbivore for which data are available (Macropus eugenii). However, peak milk energy output (154.4 kJ kg-0.75 d-1) was lower than that in other herbivores. The body mass accrued from milk consumption by young ringtail possums at various stages of lactation was similar to that of other marsupials, suggesting that the slow rate of growth in this species is a result of a limited rate of supply of milk energy from the mother and not an inefficient conversion of milk energy in the young.

Energy allocation for reproduction in a marsupial arboreal folivore, the common ringtail possum (Pseudocheirus peregrinus).

This study examines the annual energetics of a small folivorous marsupial, Pseudocheirus peregrinus. Particular attention was given to the energy and time allocated to reproduction by the females. Daily energy expenditure was measured directly using the doubly labelled water technique. Energy transferred to the young via the milk was estimated from information on milk composition and production. There was no significant seasonal variation in the energy expenditure or water influx of males or females. The mean daily energy expenditure of a 1-kg non-lactating adult ringtail possum was 615 kJ day-1 or 2.2 times standard metabolic rate. Females showed significant changes in daily energy expenditure according to their reproductive status. Without the burden of lactation the total annual energy expenditure of an adult female was estimated as 212.4 MJ kg-1 year-1. The total annual energy expenditure of a female rearing two young was 247.5 MJ kg-1 year-1, with the late stage of lactation constituting the most energetically expensive period accounting for 30% of the total yearly energy expenditure during 24% of the time. Total metabolisable energy allocation during reproduction (22 MJ kg) was similar to estimates available for other herbivores, although, the peak metabolisable energy allocation during lactation (759 kJ day-1) was lower than values available for other herbivores. The total energy requirement for reproduction (metabolisable energy plus potential energy exported to young via milk) suggests that the ringtail possum also has a relatively low overall energy investment in reproduction. It is suggested that the lactational strategy of the ringtail possum has been selected in order to spread the energy demands of reproduction over time due to constraints on the rate of energy intake imposed by a leaf diet and/or to prolong the mother-young bond. The strategies a female ringtail possum may employ to achieve energy balance when faced with the energy demands of reproduction are discussed.