Establishment and Maintenance of a Laboratory
Meredith J. Smith2, R.M. Hope1
and C.M. Chesson1.
Department, University of Adelaide, Adelaide.
University of Adelaide, G.P.O. Box 498,
Adelaide, S. Aust. 5001
Line drawing courtesy Sue Stranger.
Click on thumbnail to enlarge
The Fat-tailed Dunnart Sminthopsis
crassicaudata (Gould) is an insectivorous
marsupial widely distributed in southern
Australia. Adults weigh about 14 g and have a
head-and-body length of about 90 mm and tail
length about 60 mm. Martin (1965) bred this
species in the laboratory and recognised its
potential value as an experimental animal.
Females are polyoestrous, with an oestrous cycle
length of 31. I ± standard error0.7 days(n = 25)
and a gestation period of 13-16 days. A maximum
of 10 young can be suckled, although more than
10 may be born. The young are suckled for about
70 days and the mother has an oestrous 1-2 days
after suckling ceases. Hence a second litter may
be born 82-90 days after the first. Young
females may have their first oestrous when 115
days old (Godfrey and Crowcroft 1971; Ewer
recorded breeding of S. crassicaudata in
captivity was in 1962 by G. Gregory, a medical
practitioner at Leigh Creek, South Australia
(Martin 1965). In 1964 Martin set up a colony of
S. crassicaudata in the Zoology
Department, R.A. Fisher Laboratories, University
of Adelaide, with seven animals captured near
Warramboo in the upper Eyre Peninsula district
of South Australia (Fig. I). Some additional
wild-caught animals were subsequently introduced
into this colony and in 1967 it was amalgamated
with another colony established at the South
Australian Museum in 1965. The colony in the
Zoology Department formed the focal point of
successive studies by Martin (1965), Ewer
(1968), Hope and Godfrey (1968), Smith and
Godfrey (1970), and Godfrey and Crowcroft
(1971). This colony was eventually disbanded in
In 1965, nine
animals from the Zoology Department and three
wild-caught were used to start a colony at the
Genetics Department, R . A. Fisher Laboratories,
University of Adelaide. This colony, which has
been maintained continuously since then, has
been supplemented from time to time with animals
taken from the wild and also with animals bred
in captivity by G. Gregory, by P.R. Birks of
Adelaide, or in the Zoology Department colony.
Between 1968 and 1974, 54 animals caught in the
southeast of South Australia; Eyre Peninsula;
the lower Flinders Ranges; the Loxton Renmark
area of the River Murray; or in central
Australia were introduced into the colony at the
Genetics Department. Of these, 12 females and 9
males reproduced. The last animal from the wild
was introduced in October 1974, and the last
from any source was on the 10 January 1975, when
four captive-bred animals were received from P.R.
affecting reproduction in female S.
crassicaudata in captivity have been
identified (Smith, et al.) 1978).
Continuous long-day illumination (16 hours
light; 8 hours dark) for more than 6 months
leads to most females entering anoestrous. They
remain anoestrous during a following 3-week
period of short- day illumination (8L:l6D) but
come into oestrous again 20-30 days after the
onset of l6L:8D. Significantly more litters
are born in pairings that have experienced short
days than in those continuously exposed to long
days (Smith eta!. 1978). Analysis of the
colony’s breeding record from 1968 to 1976
showed that in 23 of the 44 fertile first
pairings the litter was conceived within 10
weeks of pairing. Moreover, of 77 females that
eventually produced a litter, 33 did not do so
as a result of their first pairing and some did
not give birth until their third or even fourth
pairing (Smith et al. 1978). Thus a
female that does not produce a litter after
being paired with one male for two or three
oestrous cycles is more likely to reproduce if
paired with a different male than if she stays
with the first male. Females older than 30
months produced less than 4% of total litters
(Smith et al. 1978). In this paper we
describe the management of the colony and
consider the success of reproduction in 1977-78.
1978 the whole colony was maintained in one
windowless room 3.7 mx 2.2 mand2.5 mhighlit by
eight 40 W fluorescent tubes hung vertically,
four at each end of the room, and six 60 W
incandescent globes on the ceiling. A
continuously glowing neon pilot light (0.05 W)
prevented absolute darkness when the main lights
were off. The lights were always switched off at
1300. The room was ventilated by ducted air, the
temperature of which was maintained at 25°C by a
thermostat operating in the return air vent.
Some of the air was exhausted by a continuously
run- fling exhaust fan. The system was not
influenced by, and did not affect, any other
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were positioned on five shelves of Dexion
framework fitted on the two long walls of the
room. The cages, 53 cm x 36 cm x 22 cm high, had
galvanized iron sides, galvanized mesh top with
hinged lid, and plate-glass front. They were
bottomless and each stood in a tray containing
loam 2-3 cm deep. Each cage contained a nest box
in the form of a plastic container 20 cm x 10 cm
x 5 cm, with the lid perforated and a 4 cm
diameter entrance hole in one end. The nest box
was loosely filled with shredded paper (Fig.2).
Exercise wheels were provided in most cages.
were washed in germicide (Surgidene, Gibson
Chemicals Ltd. Adelaide) and the loam was
renewed about every 4 weeks. Mite infestations
were controlled with flea powder (Bayer,
The weekly diet which supported the growth
and reproduction of at least four generations of
S. crassicaudata consisted of two meals
of jellied raw egg; three meals of raw beef
heart, fat-free and minced; one of meal- worms
(larvae of Tenebrio sp.), and one of
mealworms if available or processed lambs brains
(The Nestle Company, Sydney). The jellied egg
and the minced beef heart were presented in
paper patty pans (National, Thebarton) which
were discarded after use. Each day fresh food
(10 g beef per animal), more than the animals
needed, was put in the cages at about midday so
that it was fresh when the animals became active
after the lights were switched off. Food left
over from the previous day was removed. Water
was always available in every cage.
Vitamin and mineral supplements were added to
the minced beef heart once a week, as follows:
ABDEC (Parke Davis, Caringbah, N.S.W.) diluted
60 times to form a stock solution given as
10mL/1.4 kg beef, that is 10mL/140 animals;
potassium iodide stock solution in distilled
water (0.015% by weight), given as 5mL/1.4 kg
beef, that is 5.mL/140 animals, and a mixture of
10 parts by weight of calcium orthophosphate
powder (Ca.,(P03)4) and 1part of vitamin E
powder [d-α tocopheryl acid succinate
(1000 i.u./l6 g): White-E, Medical Research
(Marketing) Pty Ltd, North Ryde, N.S.W.].
The liquid supplements were mixed with the beef
mince: the powder supplement was sprinkled over
the beef in the patty pans.
In June 1978
the minced beef heart was replaced by tinned pet
food (Whiskas, Uncle Ben’s of Australia,
Wodonga. Victoria). Later the jellied raw egg
was replaced by jellied powdered egg. In
January 1981 the calcium orthophosphate was
replaced by calcium carbonate powder.
The young of
a litter were separated from their mother when
70 days old and were caged in groups of three or
four of the same sex. Females were first
paired when 6 months old and males when 8 months
Before being paired the male was placed in a
clean cage, and after about I week the female
was introduced into the male’s cage. Sometimes
two females were caged with one male. The
pouches of paired females were examined once per
week (Fig. 3) and as soon as a litter was found,
the male was removed. Lactating females were
examined weekly but the pouch was not opened
unless the absence of a bulge suggested that the
litter had been lost.
As soon as the litter had been separated from
the mother, the mother was returned to the male
so that mating might occur at the post-weaning
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For the past
2 years, pairs that have not produced a litter
within 3 months of pairing have been separated
and each animal has been paired with another.
Usually males and females were removed from
pairs when they reached 30 months old.
The lighting regime was 16 hours of light and 8
hours of dark each day (l6L:8D) for 6 months,
then a period of 3 weeks of 8 hours of light and
16 hours of dark(8L:16D) followed by a return to
of urine and determination of oestrous.
from their nest boxes during the light period
usually urinated immediately they were caught.
cornified epithelial cells were abundant in the
urine, and could be seen in a drop of urine
examined with a microscope. Cells were rare or
absent throughout the rest of the oestrous cycle
A I : I
mixture of oxygen and nitrous oxide containing
ethrane, or enflurane (Abbott Laboratories,
Sydney), 4%, administered from an “Enfluratec”
anaesthetic machine at 1 L/min was suitable for
anaesthesia of short duration.
In a room heated to 37°C and with an exhaust fan
running, one animal was placed in each of two
anaesthetic vessels. After 10 minutes, one
animal was taken out of the vessel and its
muzzle was put into a facemask” supplied with
gas from the anaesthetic machine. A third animal
was placed in the vacated anaesthetic vessel
while the first animal was removed from the
face-mask and a sample of its blood was taken.
As soon as the blood had been obtained, the
animal was placed in a small recovery vessel,
open to the air, and in which drinking water was
available. Recovery took about 5 minutes.
Meanwhile the second animal was being bled.
taken from anaesthetised animals by puncturing
the orbital sinus with a 2 I-gauge needle and
drawing the resulting drops of blood into a
heparinized syringe (Hope and Godfrey 1968).
About 0.25-0.3 mL of blood were collected.
Blood could be obtained from 15 animals in 1.5-2
hours, i.e. the time involved is about 6-8
minutes per animal. Nearly 400 blood samples
have been taken since ethrane has been used, and
10 animals have died during anaesthesia and
bleeding, to give a de4th rate of 2.6%.
and 1978, 66 females produced 117 litters, and
in 66 pairings that existed for 10 weeks or
longer, no litter was born. The proportion of
females giving birth was particularly high among
young adults. Twenty-five females paired when
less than 7 months old bore a litter in their
first pairing, 20 of them within 12 weeks of
pairing. Fourteen other females paired when less
than 7 months old remained nulliparous in first
pairings lasting more than 9 weeks; 13 of these
nonfertile pairings lasted more than 12 weeks.
females comprised 3 first-generation
laboratory-bred, 27 second-generation, 31 third
generation and 5 fourth-generation
number of litters borne by a female was 5 but
neither of the two females that produced 5
litters reared them all. Only one female
reared all of 4 litters: four females reared all
of 3 litters (Table 1).
click to enlarge
Of the 117
litters produced by females that gave birth
during 1977-78 in 87 litters at least one young
survived to weaning, but 30 litters were lost
completely before weaning, that is in about only
two-thirds of the litters born were any young
reared to weaning. The loss of young within
litters has not been analysed because of the
difficulty in obtaining the correct number for
the initial size of the litter. As the animals
were examined weekly, some litters were 6 days
old when first counted and some young could have
been lost by then.
females lost their first litter. 12 their
second. 4 their third. 2 their fourth
litters and I female lost her fifth litter.
Of the 30
litters lost completely, 11 died after their
mother died. Necropsy of these females
revealed that the death usually resulted from
pneumonia or pleurisy.
In the 87
litters in which at least one young survived,
the modal litter size at weaning was 6 (Fig. 4)
and the mean litter size was 5.2, standard
deviation 2.0. Although several litters of 10
were found in the pouch, 9 was the maximum
number reared to weaning. If the number of
litters lost completely are included in the
calculation, the mean litter size is 3.9,
standard deviation 2.9.
The mean number of young reared, summed over
all litters (120) for each parous female, was
7.0, standard deviation 5.7. However, this
mean under-estimates the reproductive success of
the females because 19 of the females were still
of reproductive age at the time of analysis and
several of them did rear more young. The
maximum number of young reared by one female was
23, but very few reared more than 15 (Fig. 5).
Fig 5 & 6
click to enlarge
days is the minimum interval between successive
parturitions when the first litter is reared to
weaning. The observed interval ranged from 82
days to 545 days, and 3 I times out of 43
(72%) the second litter was born less than 120
days after the previous one (Fig. 6). Hence 72%
of females who produced a subsequent litter
after a successful lactation were fertilised at
either their first or second post-weaning
Young females that experienced 16L: 8D
from birth and whose mothers received l6L
8D during pregnancy became mature by the
expected age of 6 months. Twenty females that
gave birth in 1978, when less than 9 months old,
were themselves born in 1978 when the main
colony was never exposed to short days. Thus
females can mature without experiencing short
females that produced second and third litters
in near minimum time did so while experiencing
long days continuously. Of the 12 females who
produced a litter more than 119 days after the
birth of the preceding litter that was reared, 4
had not received 8L:l6D, one had received it
early in lactation and 7 had experienced an
8L:l6D period that ended 31-75 days before the
In the 6 months after the fresh beef heart
in the diet was replaced by tinned pet food,
reproduction did not appear to decline but the
reproductive rates of animals on the two diets
cannot be compared because the new diet has not
been used long enough.
The rate of
increase of the colony’s population was limited
by an unfortunately high death rate not only
among pouch young, but also among juveniles and
adults (Fig. 7). The cause of death was
usually an infection of the respiratory tract.
Death was rapid and we were seldom aware of
the animal’s debility.
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Diet has been implicated in the failure of
laboratory colonies of Sminthopsis to
thrive. Nutritional deficiency is believed to
have caused the extinction of a colony of S.
macroura (synonym S. larapinta)
(Godfrey 1969). In a colony of S.
crassicaudata started by the Radiobiology
Unit of the Medical Research Council in
Berkshire, England. many animals died with
enlarged thyroid glands. The symptoms
suggested an iodine deficiency, but although the
animals were given much more iodine,
reproduction ceased and the colony died out (Breckon
and Hulse 1972).
When prenatal and early postnatal mortality in
the colony at the Zoology Department became very
high at the beginning of the 1967 breeding
season, one massive dose of both Vitamin E and
iodine given to all individuals was sufficient
to return the breeding to normal 6 weeks later
(Godfrey and Crowcroft 1971).
Management is important in maintaining a high
rate of reproduction. Pairing of young females
as soon as they reached 6 months of age and
reconstitution of the pair as soon as the litter
was 70 days old were important in management.
Small cages (floor area 0. 19m2)
were large enough to allow the animals to breed
and to rear young. Larger cages (floor area
0.56 m2) as are used to house S.
macroura at the U.S.A. National Zoological
Park (Collins 1973) are not necessary, nor are
the 4m2 pens used to provoke
resistant S. crassicaudata into breeding
(Godrey and Crowcroft 1971).
crassicaudata bred in the laboratory
resembled their wild conspecifics in that
oestrous cycles stopped during short days,
either autumn in the wild, or 8L:16D in the
laboratory, and resumed during long days (Morton
1978: Smith et al. 1978).
Laboratory-bred S. crassicaudata
differed from the wild populations in that the
females became sexually mature at 6 months and
without having experienced short days, whereas
the wild animals do not reproduce until after
the winter following their birth (Morton 1978).
Also, laboratory females can produce and rear
as many as five litters successively whereas
wild females are not known to produce more than
two litters per season nor to reproduce in a
second season (Morton 1978; Smith et al.
few insectivorous marsupials have been
established in the laboratory but of these, S.
crassicaudata compares favourably in rate
of reproduction and in viability of the colony.
Colonies of Dasyuroides byrnei and of
Dasycercus cristicauda have been
established at La Trobe University and two
generations of Dasycercus and three of
Dasyuroides had been raised by 1971 (Woolley
1971). S. macroura (syn. S.
Iarapina) breed readily in captivity and
although Godfrey’s (1969) colony died out after
two generations, a colony of the same species
was thriving at the U.S.A. National Zoological
Park, where a fourth generation litter of
captive bred animals had been born (Collins
1973). Quantitative data for rates of
reproduction and of survival in these colonies
of dasyurids are unavailable at present. In
colonies of the omnivorous didelphid Marmosa
robinsoni, litters have been produced in the
ratio of one for every 3-4.6 pairings when the
animals were paired only when females were in
oestrous (Barnes and Barthold 1969; Godfrey
1975). In the Brookfield Zoo colony the mean
litter size was 7.8, standard deviation 3.1, in
the parental generation, 9.1, standard deviation
2.7, in the second laboratory-bred generation
(Godfrey 1975); the number weaned from each
litter was not given. Females bred for only 1
year and a low proportion of laboratory-bred
females contributed to the next generation, with
only 8 of 52 first generation and 13 of 39
second generation females becoming parous
(Godrey 1975). S. crassicaudata’s mean
reproductive rate of more than 7 young weaned
per parous female, and with more than half of
the paired females producing, can be favourably
compared with the data for Marmosa robinsoni.
Of the several persons who have at times
cared for the colony we especially acknowledge
the assistance of Mrs D. Golding. We thank Dr
P. Baverstock, IMVS, Adelaide, for his advice on
Ethrane anaesthesia. We are grateful to M.
Archer, F. Aslin, P. Birks, L. Corbett, T.
Dennis, B. Eves, G. Godfrey, 0. Gregory, 1.
Hann, R. Lang,D. Pratt and J. Ramsey for
(providing us with animals and to the South
Australian National Parks and Wildlife Service
for their permission to take wild S.
and Hulse, E.V. (1972). Difficulties in the
management of Sminthopsis crassicaudata
due to iodine deficiency and thyroid disease.
Lab. Anim. 6: 109-18.
and Barthold, S.W. (1969) Reproduction and
breeding behaviour in an experimental colony of
Marmosa mitls Bangs (Didelphidae). J.
Reprod. Fertil., Suppl. 6:477-82.
(1973) Monotremes and marsupials: a reference
for zoological institutions. (Smithsonian
Institution Press: Washington.)
(1968) A preliminary survey of behaviour in
captivity of the dasyurid marsupial,
Sminthopsis crassicaudata (Gould). Z.
Tierpsychol. 25: 319-65.
K. (1969) Reproduction in a laboratory colony of
the marsupial mouse Sminthopsis larapinta
(Marsupialia: Dasyuridae). Aust. J. Zool. 17:
(1975) A study of oestrous and fecundity in a
laboratory colony of Mouse Opossums Marmosa
robinsoni. J. Zool., Lond. 175: 541-55.
and Crowcroft, P. (1971) Breeding the fat-tailed
marsupial mouse in captivity. In: Lucas, J.
(ed.), Inter. Zoo. Yearb. 11: 34-8.
and Godfrey, G.K. (1968) Transferrin
polymorphism in the Australian marsupial mouse
Sminthopsis crassicaudara (Gould). Aust.
J. Biol. Sci. 21: 587-91.
(1965) The potentialities of the fat-tailed
marsupial mouse, Sminthopsis crassicaudara
(Gould) as a laboratory animal. Aust. J.
(1978) An ecological study of Sminthopsis
crassicaudara (Marsupialia: Dasyuridae). lii.
Reproduction and life history.
Aust. Wild. Res. 5: 22 1-48.
and Godfrey. G.K. (1970) Ovulation induced by
gonadotrophins in the marsupial Sininthopsis
crassicaudata (Gould). J. Re prod. Fertil.
Bennett,J.H. andChessonC.M. (1978) Photoperiod
and some other factors affecting reproduction in
female Stninrhopsis crssicaudata (Gould)
(Marsupialia: Dasyuridae) in captivity. Aust. J.
Zool. 26: 449-63.
(1971) Maintenance and breeding of laboratory
colonies. Dasvuroides bvrnei and
Dasvcercus cristicauda. In: Lucas. J. (ed.).
Inter. Zoo Yearb. 11:351-4.
reproduced from an article from ‘The Management
of Australian Mammals in Captivity’, by D. D.
Evans, 1982 with many thanks and