scholarly journals Digestive plasticity of the small intestine and the fermentative hindgut in a marsupial herbivore, the tammar wallaby (Macropus eugenii)

2006 ◽  
Vol 54 (4) ◽  
pp. 287 ◽  
Author(s):  
Adam J. Munn ◽  
Peter Banks ◽  
Ian D. Hume
Keyword(s):  
Small Intestine ◽  
Body Mass ◽  
Alimentary Tract ◽  
Nutritional Ecology ◽  
Tammar Wallaby ◽  
Proximal Colon ◽  
The Body ◽  
Macropus Eugenii ◽  
Diet Versus ◽  
Pelleted Diet

We investigated the effects of a ground, pelleted diet versus natural forage on the gross morphology of the gastrointestinal tract of a medium-sized (5–7 kg body mass) macropodid marsupial, the tammar wallaby (Macropus eugenii). The empty wet mass (g) of the small intestine of tammar wallabies maintained on a pelleted diet for 6 weeks was 22% greater than that of animals maintained on natural forage, once body mass was taken into account by ANCOVA. Similarly, the body-mass-adjusted length of the tammar wallaby caecum and proximal colon combined was 25% longer in animals maintained on the pelleted diet compared with those maintained on forage. Our data suggest that food particle size may be directly involved in controlling the size of the post-gastric alimentary tract in tammar wallabies, and thus in their diet choice and nutritional ecology. Notably, this is the first study that links phenotypic plasticity of the gut directly to diet in a marsupial and we conclude that the tammar wallaby is an excellent model for exploring the causes and consequences of digestive plasticity in macropodid marsupials.

Studies on the Nutrition of Macropodine Marsupials. 4. Digestion in the Stomach and the Intestine of Macropus Giganteus, Thylogale Thetis and Macropus Eugenii.

1982 ◽  
Vol 30 (5) ◽  
pp. 767 ◽  
Author(s):  
DW Dellow ◽  
ID Hume
Keyword(s):  
Organic Matter ◽  
Large Intestine ◽  
Volatile Fatty Acids ◽  
Tammar Wallaby ◽  
Proximal Colon ◽  
Soluble Carbohydrate ◽  
Macropus Eugenii ◽  
Apparent Loss ◽  
Digestible Organic Matter ◽  
Acid Detergent Fibre

4. Digestion in the stomach, small intestine and large intestine of the red-necked pademelon (Thylogale thetis), the tammar wallaby (Macropus eugenii) and the eastern grey kangaroo (M. giganteus) fed on chopped lucerne hay freely was estimated in a slaughter experiment by reference to chromic sesquioxide added to the diet. Concentrations of volatile fatty acids and ammonia, and pH, indicated that microbial activity in the forestomach and large intestine (caecum and proximal colon) was extensive. In all 3 species virtually all of the soluble carbohydrate, 17% of apparently digestible crude protein, 62 to 65% of apparently digestible organic matter and 82 to 85% of digestible acid-detergent fibre were digested in the forestomach. There was a progressive loss of dietary substrates along the length of the forestomach; readily fermentable carbohydrate was digested largely in the sacciform forestomach and cranial region of the tubiform forestomach, and the rate of apparent loss of organic matter decreased along the tubiform forestomach.

Electromyography of the Stomach and Small-Intestine of the Tammar Wallaby, Macropus-Eugenii, and the Quokka, Setonix-Brachyurus

1988 ◽  
Vol 36 (4) ◽  
pp. 363 ◽  
Author(s):  
KC Richardson ◽  
RS Wyburn
Keyword(s):  
Small Intestine ◽  
Action Potential ◽  
Slow Wave ◽  
Action Potentials ◽  
Tammar Wallaby ◽  
Electromyographic Activity ◽  
Bipolar Electrodes ◽  
Macropus Eugenii ◽  
Potential Activity ◽  
Frequency Gradient

Electromyographic activity recorded by chronically implanted bipolar electrodes showed the tammar wallaby (Macropus eugenii) and the quokka (Setonix brachyurus) to have slow wave activity over the entire stomach and small intestine. Slow wave mean frequency (min-') were: 5.5 and 5.3 for the forestomach; 5.4 and 5.0 for the pylorus; 26 and 17.8 for the duodenum; and 25 and 17.5 for the ileum in the tammar and quokka, respectively. There was virtually no frequency gradient of the slow wave along the length of the small intestine in both macropods, which is extremely unusual. Action potentials were recorded from the quokka stomach but not from the tammar stomach. Action potentials were recorded from the small intestine of both species. The pattern of action potential activity was similar in both species. There were periods of up to 30 minutes during which the intestine was quiescent (q) with no action potential activity. This was followed by extended periods when bursts of action potentials occurred irregularly to be followed by periods of about 5 minutes when action potentials were associated with every slow wave.

Molar progression and tooth wear in tammar (Macropus eugenii) and parma (Macropus parma) wallabies

2003 ◽  
Vol 51 (2) ◽  
pp. 137 ◽  
Author(s):  
R. G. Lentle ◽  
I. D. Hume ◽  
K. J. Stafford ◽  
M. Kennedy ◽  
S. Haslett ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Body Mass ◽  
Functional Significance ◽  
Tooth Wear ◽  
Tammar Wallaby ◽  
Molar Tooth ◽  
Forward Movement ◽  
Tooth Morphology ◽  
Macropus Eugenii ◽  
Tooth Length

We investigated the functional significance of molar progression and the influence of diet on the usefulness of molar progression as an index of age in two macropodid marsupials, the tammar wallaby (Macropus eugenii), a grazing species, and the parma wallaby (Macropus parma), a browser/grazer, by exploring the relationships between the index of molar progression and several skull and tooth parameters. We also tested allometric models that related molar progression and aspects of tooth morphology to body mass. Results support the notion that molar progression in these closely related macropods results from 'mesial shift'(forward movement resulting from growth of the bones of the skull bearing the dentary, the anterior viscerocranium) rather than from 'mesial drift' (forward movement of molars relative to the anterior viscerocranium).There were no significant differences between the two species in the rate of molar progression despite differences in diet. Instead, the greater reliance of tammar wallabies on grasses was reflected in differences in their tooth morphology from that of parma wallabies. The sum of the breadths of erupted molariform teeth of tammars increased significantly faster with body mass and with length of the anterior viscerocranium than in parma wallabies and approximated a theoretical model for compensation with metabolic body mass more closely than models based on other morphological parameters.The total mesiodistal length of dentition, the mesiodistal lengths of the component teeth of the proximal molar row, and the distance between the mesial and distal lophs were all significantly lower in tammar wallabies than in parma wallabies. These differences result in tammar wallabies having greater numbers of transverse cutting edges per unit of molar tooth length, which maximises the efficiency of comminution of long grass fibres.

Comparisons of indices of molar progression and dental function of brush-tailed rock-wallabies (Petrogale penicillata) with tammar (Macropus eugenii) and parma (Macropus parma) wallabies

2003 ◽  
Vol 51 (3) ◽  
pp. 259 ◽  
Author(s):  
R. G. Lentle ◽  
I. D. Hume ◽  
K. J. Stafford ◽  
M. Kennedy ◽  
S. Haslett ◽  
...  
Keyword(s):  
Body Mass ◽  
Tammar Wallaby ◽  
Mean Value ◽  
Dietary Habit ◽  
Macropus Eugenii ◽  
Total Length ◽  
Rate Of Increase ◽  
The Mean

We measured parameters of molar progression and dental function in the brush-tailed rock-wallaby (Petrogale pencilliata) (a browser/grazer) and compared them with data from the tammar wallaby (Macropus eugenii) (a grazer) and the parma wallaby (Macropus parma) (a grazer/browser).Although the mean value of the molar index (MI) was higher in rock-wallabies than in parma and tammar wallabies the mean rate of increase of log(MI) with log(body mass) was similar in the three species. Reported differences between these species in their rates of molar progression with age may therefore result from differences in their rates of bodily growth. The findings indicate that molar progression in the rock-wallaby is governed by the growth of the bones of the viscerocranium (mesial shift), rather than by diet-induced movement of the teeth within the bones of the viscerocranium (mesial drift), and was not influenced by the persistence of P4 premolars. It is therefore unlikely that differences in the rate of molar progression are directly linked to differences in diet.The relationship between functional dental parameters and body mass differed between brush-tailed rock-wallabies and tammar wallabies, species of differing dietary habit, but did not differ between brush-tailed rock-wallabies and parma wallabies, species of more similar dietary habit. Thus the total length of upper transverse lophine ridges and the interlophine distances of the M1 to M3 upper molars of brush-tailed rock-wallabies were not different from those of parma wallabies but were significantly greater than those of tammar wallabies. These differences can be interpreted in terms of greater emphasis on crushing/grinding of browse in the rock-wallabies and parma wallabies.

Influence of the immature testis on sexual differentiation in the tammar wallaby, Macropus eugenii (Macropodidae: Marsupialia)

1989 ◽  
Vol 1 (3) ◽  
pp. 243 ◽  
Author(s):  
CH Tyndale-Biscoe ◽  
LA Hinds
Keyword(s):  
Sex Chromosome ◽  
Tammar Wallaby ◽  
Mammary Glands ◽  
Compensatory Hypertrophy ◽  
The Body ◽  
Mullerian Duct ◽  
Müllerian Duct ◽  
Erectile Tissue ◽  
Macropus Eugenii ◽  
Genetical Control

Reproduction in the tammar wallaby, Macropus eugenii (Desmarest), is highly seasonal in the females but not the males. This study was designed to determine whether the difference is established during early life as a result of exposure to the developing testes. At day 10 after birth, when the sex can be distinguished externally, testes were removed from males and placed under the flank skin of females, while other groups of males and females were subjected to surgery without interfering with the gonads. The testis grafts remained palpable for 3-6 months. Sex-chromosome constitution was confirmed by karyotyping. At 3 years of age, the body weights and dimensions of the grafted females were not significantly different from those of the sham-operated females, whereas those of the castrated males were significantly larger and were equal to those of the sham-operated males, indicating that there is genetical control of growth independent of the testis in this species of marsupial. During 5 years of observations, none of the grafted females ever produced young, whereas all of the sham-operated females produced young each year from the second year. The grafted females had a mixture of male and female reproductive structures. The pouch and mammary glands developed normally, as did the Mullerian duct derivatives, the vaginal complex, the uteri and the oviducts. The ovaries were either devoid of oocytes and follicles or had reduced numbers, the Wolffian ducts were retained to varying degrees, the urogenital strand had developed into a prostate indistinguishable in size and structure from that of intact males, and the genital tubercle had developed into a normal-sized penis with a crus penis and Cowper's glands. In the castrated males, the scrotum developed normally and contained the gubernaculum and vas deferens. There was no evidence of Mullerian duct derivatives, and the urogenital strand was a simple canal, as in females. There were no Cowper's glands and no penis or erectile tissue. In one hemicastrated male, there was no development of the penis, although the remaining testis occupied the scrotum and showed compensatory hypertrophy. These findings indicate that the testis, at day 10, has a profound influence on the early differentiation of the Wolffian ducts, prostate and penis but cannot influence the differentiation of the Mullerian duct derivatives. The testis does not have any effect on the development of the pouch, mammary glands or scrotum or on somatic growth, all of which are apparently under independent genetical control.

The Structure and Radiographic Anatomy of the Alimentary Tract of the Tammar Wallaby, Macropus Eugenii (Marsupialia) 1. The Stomach.

1980 ◽  
Vol 28 (3) ◽  
pp. 367 ◽  
Author(s):  
KC Richardson
Keyword(s):  
Gastric Emptying ◽  
Contrast Agent ◽  
Distal Part ◽  
Alimentary Tract ◽  
Tammar Wallaby ◽  
Barium Sulphate ◽  
Macropus Eugenii ◽  
Middle Compartment ◽  
The Right

A description is given of the gross and radiographic anatomy of the stomach of Macropus eugenii. The stomach is in the form of a sigmoid tube beginning at a blind sac on the left side and ending at the caudally directed pylorus on the right side. It is haustrated over the whole length of the proximal compartment and most of the middle compartment. The distal part of the middle compartment, and the distal compartment, are not haustrated. The time, but not the pattern, of distribution and mixing with digesta of orally administered barium sulphate is shown to be different in wallabies which had been recently fed and those which had not been fed for 24 h. The contrast agent was carried from the cardia towards the caudal gastric flexure along the ventricular groove. The barium sulphate first dispersed both cranially and caudally from the ends of the groove and was subsequently mixed with digesta. Gastric emptying was difficult to determine radiographically. No radiopaque material was seen in the duodenum, and digesta were therefore assumed to have passed rapidly through into the jejunum.

A comparison of the gross gastrointestinal morphology of genetically-similar tammar wallabies (Macropus eugenii) from different nutritional environments

2004 ◽  
Vol 52 (4) ◽  
pp. 437 ◽  
Author(s):  
R. G. Lentle ◽  
K. J. Stafford ◽  
I. D. Hume
Keyword(s):  
Multivariate Analysis ◽  
Small Intestine ◽  
Poor Quality ◽  
The Body ◽  
Lower Body ◽  
Macropus Eugenii ◽  
Quality Food ◽  
The North ◽  
Small Intestines ◽  
Secondary Fermentation

The gross morphology of the body and gastrointestinal tract of genetically-similar tammar wallabies (Macropus eugenii) that had been introduced into two different nutritional environments on the North Island of New Zealand were compared using multivariate analysis. Tammar wallabies from Kawau Island had significantly lower body mass per unit body length than those from the Rotorua district where food was more abundant. Furthermore, wallabies from Kawau Island had longer small intestines and caecae relative to other gut regions than did those from the Rotorua district. This suggests that poor-quality food might reduce the efficiency of primary fermentation in the forestomach; similarly, the efficiency of digestion and absorption in the small intestine might be reduced. In addition, poor-quality food might promote secondary fermentation in the hindgut of grazing tammar wallabies.

scholarly journals Acrosome formation during sperm transit through the epididymis in two marsupials, the tammar wallaby (Macropus eugenii) and the brushtail possum (Trichosurus vulpecula)

1999 ◽  
Vol 194 (2) ◽  
pp. 223-232
Author(s):  
MINJIE LIN ◽  
JOHN C. RODGER
Keyword(s):  
Spatial Information ◽  
Dorsal Surface ◽  
Tammar Wallaby ◽  
Sperm Head ◽  
The Body ◽  
Brushtail Possum ◽  
Trichosurus Vulpecula ◽  
Macropus Eugenii ◽  
Acrosomal Membrane ◽  
Acrosome Formation

In certain Australian marsupials including the tammar wallaby (Macropus eugenii) and the brushtail possum (Trichosurus vulpecula), formation of the acrosome is not completed in the testis but during a complex differentiation process as spermatozoa pass through the epididymis. Using transmission and scanning electron microscopy this paper defined the process of acrosome formation in the epididymis, providing temporal and spatial information on the striking reorganisation of the acrosomal membranes and matrix and of the overlying sperm surface involved. On leaving the testis wallaby and possum spermatozoa had elongated ‘scoop’-shaped acrosomes projecting from the dorsal surface of the head. During passage down the epididymis, this structure condensed into the compact button-like organelle found on ejaculated spermatozoa. This condensation was achieved by a complex process of infolding and fusion of the lateral projections of the ‘scoop’. In the head of the epididymis the rims of the lateral scoop projections became shorter and thickened and folded inwards, to eventually meet midway along the longitudinal axis of the acrosome. As spermatozoa passed through the body of the epididymis the lateral projections fused together. Evidence of this fusion of the immature outer acrosomal membrane is the presence of vesicles within the acrosomal matrix which persist even in ejaculated spermatozoa. When spermatozoa have reached the tail of the epididymis the acrosome condenses into its mature form, as a small button-like structure contained within the depression on the anterior end of the nucleus. During the infolding process, the membranes associated with the immature acrosome are either engulfed into the acrosomal matrix (outer acrosomal membrane), or eliminated from the sperm head as tubular membrane elements (cytoplasmic membrane). Thus the surface and organelles of the testicular sperm head are transient structures in those marsupials with posttesticular acrosome formation and this must be taken into consideration in attempts to dissect the cell and molecular biology of fertilisation.

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