Hayley J. Stannard

Digestibility of feeding regimes of the red-tailed phascogale (Phascogale calura) and the kultarr (Antechinomys laniger) in captivity

Digestibility was studied in the red-tailed phascogale (Phascogale calura) and the kultarr (Antechinomys laniger), small insectivorous/carnivorous marsupials, to determine their nutrient requirements in captivity. The marsupials were fed a range of insects, rat (Rattus rattus) and small carnivore food (Wombaroo). Digestibility experiments were conducted for a total of 12 days, which incorporated a five-day adjustment phase followed by a seven-day collection period. The apparent digestibility values for the phascogale and kultarr were above 81% for dry matter, energy, protein and lipids on all diets provided. No significant difference was found between phascogales and kultarrs on the same diet with respect to apparent digestibility of dry matter, energy, protein and lipids. The apparent absorption of minerals varied for each diet for the phascogale and kultarr. Maintenance energy requirements were determined to be 954 kJ kg0.75 day–1 for the red-tailed phascogale and 695 kJ kg0.75 day–1 for the kultarr. Presented here are the most comprehensive data on diet digestibility for dasyurids thus far.

Longevity and breeding in captive red-tailed phascogales (Phascogale calura)

This paper reports successful breeding by 4-year-old female red-tailed phascogales (Phascogale calura) and that they can survive until at least 5 years of age in captivity, whilst males can survive until at least 2 years of age in captivity. These findings have implications for captive breeding programs, providing evidence that older females can be successfully bred. In the longer term we hope these findings may aid conservation efforts of this endangered dasyurid.

Dietary composition and nutritional outcomes in two marsupials, Sminthopsis macroura and S. crassicaudata

Abstract Little is known about the specific dietary preferences of many marsupials. We undertook digestion studies in 2 species of insectivorous marsupials, the stripe-faced dunnart (Sminthopsis macroura) and the fat-tailed dunnart (Sminthopsis crassicaudata), because these are 2 species that are regularly kept in captivity, although nothing is known about their nutritional requirements in the wild. Morphology and dimensions of the gastrointestinal tract of both species also were assessed. The test diets included 2 laboratory-type diets: cat formulation and Wombaroo small carnivore mix; and natural insect diets: adult crickets (Acheta domesticus), Australian wood cockroaches (Panesthia australis), and mealworm larvae (Tenebrio molitor). Composition of the test diets on a dry-matter basis varied considerably; ranges included gross energy 16–27 kJ/g, crude protein 38–64%, lipids 9–51%, calcium (Ca) 340–17,800 mg/kg, and phosphorus 6,600–16,000 mg/kg. Depending on the diet, the digestible energy intake ranged from 359 to 816 kJ kg−−0.75 day−1 for stripe-faced dunnarts and digestible energy intake ranged from 542 to 990 kJ kg−0.75 day−1 for fat-tailed dunnarts. No single diet was appropriate if fed alone, notably the insect diets, which required Ca supplementation. The morphology of the gastrointestinal tracts of both species was simple and consisted of a unilocular stomach and relatively uniform intestine. The morphometrics of the gastrointestinal tracts of fat-tailed dunnarts were proportionally larger than for stripe-faced dunnarts. Fat-tailed dunnarts also needed to consume more nutrients per unit of body mass for maintenance in captivity compared to stripe-faced dunnarts.

Changes to food intake and nutrition of female red-tailed phascogales (Phascogale calura) during late lactation

Reproduction and especially lactation are nutritionally costly for mammals. Maternal access to adequate and optimal nutrients is essential for fecundity, survival of offspring, and offspring growth rates. In eutherian species energy requirements during lactation can be heavily dependent on litter size and the body mass of the female. In marsupials litter size does not appear to affect nutritional requirements during lactation; however, studies of marsupial nutritional requirements during lactation are rare. Marsupials are distinct from eutherians as they give birth to young at a much more underdeveloped state and the majority of their investment into the growth of their offspring occurs postnatally. Nutritional requirements of adult female red-tailed phascogales (Phascogale calura) were measured to determine the differences between those lactating and not lactating. On average females that were lactating had maintenance energy requirements of 1728 ± 195 kJ kg(-0.75) d(-1), double that of non-lactating animals. There was no significant correlation between energy requirements and litter size among lactating female phascogales. Apparent absorption of macronutrients did not differ between lactating and non-lactating individuals. The study has shown that food needs to be increased by at least double during late lactation. Litter size appears to have no influence on maternal nutrient requirements when food is available ad libitum and offspring in smaller litters grow faster than those in larger litters.

Observation of reproductive strategies of captive kultarrs (Antechinomys laniger)

Captive kultarrs (Antechinomys laniger) were bred from June to February. Their gestation period was longer than 12 days, as suggested by previous research. Pouches were observed to determine whether births occurred. Individuals were capable of producing offspring in their second and third year of life, which has been suspected previously, but never demonstrated in other published studies.

To bask or not to bask: Behavioural thermoregulation in two species of dasyurid, Phascogale calura and Antechinomys laniger

Torpor is an important physiological process used to reduce body temperature and thus energy needs in mammals and birds. Rewarming from torpor can be costly. In some small mammals basking is used to reduce the cost of rewarming from torpor. The use and duration of basking was measured in two native Australian marsupials, the red-tailed phascogale (Phascogale calura) and kultarr (Antechinomys laniger), using a heat rock. Animals were observed via video cameras to determine whether they used basking behaviours and whether this behaviour was affected by food availability. Both species became accustomed to the heat rock as time progressed. Absence of food increased basking duration and frequency in some individuals but not all animals. Generally kultarrs basked for longer periods than phascogales, and kultarrs would bask at all hours of the day while phascogales showed a strict nocturnal regime (1900-0700h). The results demonstrate that basking may be an important behavioural adaptation of the kultarr; while the phascogale requires further research.

Description of the gastrointestinal tract and associated organs of the kultarr (Antechinomys laniger)

This paper provides a macro- and microscopic description of the digestive tract of the kultarr (Antechinomys laniger), a small dasyurid marsupial. The digestive tract was simple, with no external differentiation between the small and large intestine, and lacked a caecum. Mean gross length of the kultarr digestive tract was 165.232.1mm. Microscopically, the tissues had cell types similar to those of other mammals. The new information will aid future post-mortem investigations of captive kultarrs and future studies of nutrition.

A suspected case of myopathy in a free-ranging eastern grey kangaroo (Macropus giganteus)

Macropods are susceptible to capture myopathy. A post mortem examination, and haematological and blood chemistry analysis was conducted on a male eastern grey kangaroo (Macropus giganteus) believed to have capture myopathy. Changes in blood chemistry and necrosis of muscle tissue are the most prevalent sign of myopathy in eastern grey kangaroos.

Rate of passage through the kultarr (Antechinomys laniger) digestive tract

The kultarr (Antechinomys laniger) is a small insectivorous marsupial that has undergone significant declines in geographical range. Limited studies have been undertaken on kultarr biology and therefore there is a lack of understanding of its basic biological and ecological requirements. Rate of passage in the kultarr, determined using mealworm cuticle as a marker in minced beef, was 1.6 ± 0.2 h and mean retention time was 3.9 ± 1.2 h. The rapid transit time was consistent for an animal of equivalent body mass, dietary preference and gastrointestinal tract morphology. Mean retention time was short, similar to that of other mammals with a small body mass. This study provides the first insight into gastrointestinal physiology of the little known kultarr.

Dead mouse hopping: Tyzzer’s disease in spinifex hopping-mice (Notomys alexis)

Tyzzers disease is caused by Clostridium piliformes and affects a wide range of domestic and wildlife species. Non-descript signs, if any, and a short incubation period make Tyzzers disease difficult to diagnose and treat before death occurs. Here we describe an unexpected outbreak of Tyzzers disease in a colony of native Australian spinifex hopping-mice (Notomys alexis). In this study captive hopping-mice were used in a nutrition trial (n=11), and others were housed in close proximity (n=4). During the nutrition trial, two hopping-mice exhibited signs of lethargy and diarrhoea, and were removed from the trial but died soon after. Other hopping-mice exhibited limited clinical signs of ill-health, prior to their death. In total four animals were found dead, and another seven were euthanised, to prevent a potential disease outbreak. Tyzzers disease was confirmed post-mortem using histopathology silver stain to detect the bacilli-shaped bacteria (C. piliformes) in liver tissue of two hopping-mice. After Tyzzers disease was confirmed enhanced infection control measures were implemented. Enhanced control measures included the use of metal containers for food and water, sick animals were fed and cleaned last, 5% sodium hypochlorite was used as the cleaning agent, stricter hand washing protocols and a change of gloves between feeding animals, and strict limits on persons entering the facility. Control measures for this disease should include euthanasia of any animals suspected to be infected, complete disinfection of all enclosures and associated equipment using sodium hypochlorite. Molecular methods could be employed to ensure complete removal of bacterial spores prior to new animals being moved into enclosures where affected animals were housed. Tyzzers disease is a fast spreading disease which can cause detrimental effects to captive colonies and their environment. Captive colonies subjected to stress are at risk of Tyzzers disease. Appropriate quarantine procedures, close montoring and quick action in response to signs of illness will ensure Tyzzers disease outbreaks do not occur.