Review of surrogacy program for endangered victorian brush-tailed rock wallaby (Petrogale penicillata) with special reference to animal husbandry and veterinary considerations

A Retrospective Study of Macropod Progressive Periodontal Disease ("Lumpy Jaw") in Captive Macropods Across Australia and Europe: Using Data from the Past to Inform Future Macropod Management

Simple Summary

Macropod Progressive Periodontal Disease (MPPD), or ‘lumpy jaw’, is an often-fatal dental disease commonly reported in captive kangaroos and wallabies (macropods) worldwide. The disease is difficult to treat successfully, resulting in high recurrence and mortality rates. The aim of this study was to determine animal and environmental factors that may increase the risk of developing MPPD. We conducted a multi-institution study of MPPD in macropods in zoos in Australia, and compared data with those in European zoos, where macropods are popular exhibit animals. This study reports risk factors for the development of disease including region, age, sex and particular stressors, such as transport between enclosures and between zoos. This information contributes to the understanding of disease development and advances the evidence base for preventive management strategies. We recommend protocols to reduce or prevent outbreaks of MPPD in zoos, thus decreasing morbidity and mortality rates of this challenging disease. The implementation of these recommendations will benefit the welfare and health of captive macropods worldwide.

Abstract

Macropod Progressive Periodontal Disease (MPPD) is a well-recognised disease that causes high morbidity and mortality in captive macropods worldwide. Epidemiological data on MMPD are limited, although multiple risk factors associated with a captive environment appear to contribute to the development of clinical disease. The identification of risk factors associated with MPPD would assist with the development of preventive management strategies, potentially reducing mortality. Veterinary and husbandry records from eight institutions across Australia and Europe were analysed in a retrospective cohort study (1995 to 2016), examining risk factors for the development of MPPD. A review of records for 2759 macropods found incidence rates (IR) and risk of infection differed between geographic regions and individual institutions. The risk of developing MPPD increased with age, particularly for macropods >10 years (Australia Incidence Rate Ratio (IRR) 7.63, p < 0.001; Europe IRR 7.38, p < 0.001). Prognosis was typically poor, with 62.5% mortality reported for Australian and European regions combined. Practical recommendations to reduce disease risk have been developed, which will assist zoos in providing optimal long-term health management for captive macropods and, subsequently, have a positive impact on both the welfare and conservation of macropods housed in zoos globally.

Marsupial and monotreme milk-a review of its nutrient and immune properties

All mammals are characterized by the ability of females to produce milk. Marsupial (metatherian) and monotreme (prototherian) young are born in a highly altricial state and rely on their mother’s milk for the first part of their life. Here we review the role and importance of milk in marsupial and monotreme development. Milk is the primary source of sustenance for young marsupials and monotremes and its composition varies at different stages of development. We applied nutritional geometry techniques to a limited number of species with values available to analyze changes in macronutrient composition of milk at different stages. Macronutrient energy composition of marsupial milk varies between species and changes concentration during the course of lactation. As well as nourishment, marsupial and monotreme milk supplies growth and immune factors. Neonates are unable to mount a specific immune response shortly after birth and therefore rely on immunoglobulins, immunological cells and other immunologically important molecules transferred through milk. Milk is also essential to the development of the maternal-young bond and is achieved through feedback systems and odor preferences in eutherian mammals. However, we have much to learn about the role of milk in marsupial and monotreme mother-young bonding. Further research is warranted in gaining a better understanding of the role of milk as a source of nutrition, developmental factors and immunity, in a broader range of marsupial species, and monotremes.

Effects of nutritional manipulation on body composition in the developing marsupial, Macropus eugenii

When 60-day-old tammar wallaby pouch young (Macropus eugenii) are fostered to mothers at 120 days of lactation, their growth, developmental rate and maturation of their GH/IGF axes are markedly accelerated. To determine the effect of fostering on energy intake, body composition and fat accretion, we first measured total body fat and lean mass in these young. Next, we mimicked the triglyceride oleic and palmitic acid composition of 120-day milk by supplementing 60 day young with these fatty acids and comparing their growth with that of growth accelerated young. There was no difference in the weight or growth axis maturation of supplemented young but there was significantly more body fat in these and in the growth-accelerated fostered young than in controls. We conclude that the accelerated growth and GH/IGF axis maturation observed previously in fostered young is most likely due to increased milk consumption and earlier access to specific nutrients.

Biodiversity of parasite assemblages in the genus Petrogale and its relation to the phylogeny and biogeography of their hosts

Parasites form an integral part of overall biodiversity although they are often overlooked in conservation management, where emphasis is primarily directed towards the host. Parasites are often highly specialised to particular hosts, and thus may be just as threatened as the host they inhabit. For many of Australia’s wildlife species, little is known about their associated parasite communities. To begin to address this knowledge gap, we documented the parasite fauna described in the genetically diverse marsupial genus Petrogale, which contains seven species of conservation concern. The literature evaluation showed parasites of Petrogale to be highly diverse, with 17 species of protozoa, 8 species of cestodes, 102 species of nematodes and 30 species of ectoparasites identified in 16 of 17 Petrogale host species. A comparison of the parasite communities amongst Petrogale host species indicated a highly significant correlation between the parasite community similarity, and the phylogeny (P = 0.008) and biogeography (P = 0.0001) of their Petrogale hosts, suggesting high host specificity within their associated parasite assemblages. Five Petrogale species have established species recovery programs and their parasite communities should also be considered threatened, and management of parasite diversity required as part of these conservation programs.

Successful transfer of a Goodfellow's tree kangaroo (Dendrolagus goodfellowi) pouch young to a yellow-footed rock wallaby (Petrogale xanthopus) surrogate

A 47-day-old orphaned Goodfellow's tree kangaroo (Dendrolagus goodfellowi) joey was successfully cross-fostered onto a yellow-footed rock wallaby (Petrogale xanthopus). The joey was subsequently taken for hand-rearing at age 5 months. This is the first report of the cross-fostering technique, well-established in other macropods, being applied to a Dendrolagus sp. This technique can be considered as a viable option to raise young orphaned tree kangaroos, and as a tool to accelerate breeding in captive breeding programs of Dendrolagus spp.

Reintroduction methods and a review of mortality in the brush-tailed rock-wallaby, Grampians National Park, Australia

Captive-bred brush-tailed rock-wallabies (BTRW) were reintroduced into the Grampians National Park, Australia, during 2008–12. Two release strategies (methods) were examined: ‘Small release with supplementation’ (Strategy 1) and ‘Larger release, no supplementation’ (Strategy 2). Of the 39 animals released, 18% survived. Thirty-six percent of all mortality occurred within the first 100 days. Under Strategy 1, 22 animals were released in five groups. Twenty deaths occurred across 48 months, with predation estimated to account for 15% of mortalities. Under Strategy 2, 17 individuals were reintroduced across one month. Twelve deaths occurred in the five months following release, with predation estimated to account for 83.4% of mortalities. Of the independent variables tested for their relationship to survival time after release, release strategy was the only significant predictor of survival time after release with the risk of death 3.2 times greater in Strategy 2. Independent variables tested for their relationship to predation risk indicated that release strategy was also the only significant predictor of predation risk, with the risk of death associated with predation 10.5 times greater in Strategy 2. Data suggested that fox predation was the main factor affecting BTRW establishment. Predation risk declined by 75% during the first six months after release. A significant positive relationship was also found between predation risk and colony supplementation events. We conclude that predation risk at Moora Moora Creek is reduced in releases of fewer animals, that it declines across time and that disturbing BTRW colonies through the introduction of new animals can increase predation risk. We recommend that future reintroductions should employ diverse exotic predator control measures at the landscape scale, time releases to periods of lowest predator activity, and limit colony disturbance to maintain group cohesion and social structure. Furthermore, the preferred method of population establishment should be single, small releases over multiple sites without supplementation. Further testing of the reintroduction biology of this species is urgently required.

Investigations into the health of brush-tailed rock-wallabies (Petrogale penicillata) before and after reintroduction

The health of reintroduced animals has received little attention despite the potential impacts of poor animal health on the overall success of the reintroduction and potential risks to the host environment. As part of a reintroduction program, captive-bred brush-tailed rock-wallabies (BTRWs) (Petrogale penicillata) were hardened-off for at least three months before release into the Grampians National Park, western Victoria. A total of 41 animals were involved in the project, with the 24 selected for hardening-off aged between 1.1 and 4.3 years. In all, 21 animals have been released, with data from 11 collected from all sites (captive, hardening-off and reintroduced). At each site animals were periodically trapped, anaesthetised, physically examined, weighed, and blood sampled for haematological and biochemical data over three calendar years. All reintroduced animals were radio-collared. This study presents data across sites (167 samples), two seasons (winter/spring, 95 samples; summer/autumn, 72 samples), two different age groups (juveniles <1.25 years and subadults/adults >1.25 years) and both sexes. Seventy percent of released BTRWs and 90% of sympatric macropodids were positive for macropod herpes virus; none of three BTRWs tested for toxoplasmosis was positive. Faeces were collected opportunistically for flotation and ectoparasites were collected and identified. While physical examinations with anaesthesia were safe and eliminated some animals from being released, they failed to detect all cases of oral cavity disease. A reference range of haematological and biochemical parameters have been established for this evolutionarily significant unit of BTRW. Lymphocyte/neutrophil ratios of released animals suggested that the main acute stressor is a handling phenomenon but the oxidative stress index suggested that animals were coping with their environment. Significant site differences were noted for several variables including red cell mass (red cell count, haemoglobin, haematocrit), white cell count, lymphocyte/neutrophil ratio, albumin globulin ratio, creatinine, urate, ascorbic acid, α-tocopherol, retinol, cholinesterase, total carotenoids and oxidative stress index. Significant seasonal differences were noted for some variables, including red cell mass, ascorbic acid, albumin globulin ratio, cholinesterase, total carotenoids and retinol. Significant age differences were noted for red cell mass, albumin and dietary antioxidants. The only sex-related difference related to higher retinol levels in females. Those parameters related to diet, e.g. albumin, retinol, α-tocopherol, ascorbic acid, and total carotenoids were consistent with those found in other rock-wallabies.