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Adam J. Munn - One of the best experts on this subject based on the ideXlab platform.
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decreasing methane yield with increasing food intake keeps daily methane emissions constant in two foregut fermenting marsupials the western grey Kangaroo and red Kangaroo
The Journal of Experimental Biology, 2015Co-Authors: Adam J. Munn, Catharina Vendl, Marcus Clauss, Mathew Stewart, Keith E A Leggett, Jurgen Hummel, Michael KreuzerAbstract:Fundamental differences in methane (CH4) production between macropods (Kangaroos) and ruminants have been suggested and linked to differences in the composition of the forestomach microbiome. Using six western grey Kangaroos (Macropus fuliginosus) and four red Kangaroos (Macropus rufus), we measured daily absolute CH4 production in vivo as well as CH4 yield (CH4 per unit of intake of dry matter, gross energy or digestible fibre) by open-circuit respirometry. Two food intake levels were tested using a chopped lucerne hay (alfalfa) diet. Body mass-specific absolute CH4 production resembled values previously reported in wallabies and non-ruminant herbivores such as horses, and did not differ with food intake level, although there was no concomitant proportionate decrease in fibre digestibility with higher food intake. In contrast, CH4 yield decreased with increasing intake, and was intermediate between values reported for ruminants and non-ruminant herbivores. These results correspond to those in ruminants and other non-ruminant species where increased intake (and hence a shorter digesta retention in the gut) leads to a lower CH4 yield. We hypothesize that rather than harbouring a fundamentally different microbiome in their foregut, the microbiome of macropods is in a particular metabolic state more tuned towards growth (i.e. biomass production) rather than CH4 production. This is due to the short digesta retention time in macropods and the known distinct 'digesta washing' in the gut of macropods, where fluids move faster than particles and hence most likely wash out microbes from the forestomach. Although our data suggest that Kangaroos only produce about 27% of the body mass-specific volume of CH4 of ruminants, it remains to be modelled with species-specific growth rates and production conditions whether or not significantly lower CH4 amounts are emitted per kg of meat in Kangaroo than in beef or mutton production.
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feeding biology of two functionally different foregut fermenting mammals the marsupial red Kangaroo and the ruminant sheep how physiological ecology can inform land management
Journal of Zoology, 2010Co-Authors: Adam J. Munn, Terence J. Dawson, Steven R. McleodAbstract:Fermentative digestion in an expanded foregut region has evolved independently among Australia’s marsupial Kangaroos as well as among placental ruminants. However, notable differences occur in the form and function of the Kangaroo and ruminant forestomachs, the main site of fermentation; Kangaroos possess a tubiform forestomach, reminiscent of the horse colon, whereas ruminants possess a large vat-like structure. How these differences in gut form might influence Kangaroo and sheep ecologies is uncertain. We compared diet choice, apparent digestibility (dry matter), food intake and grazing behaviour of Australia’s largest Kangaroo, the red Kangaroo Macropus rufus and the ruminant sheep Ovis aries. Digestive efficiencies were comparable with other studies, 52% for Kangaroos and 59% for sheep, but were not significantly different. Per animal, the smaller red Kangaroos (body mass 24 kg) ingested less food than the larger sheep (50 kg), but both species engaged in food harvesting for the same length of time each day (c. 10 h). However, sheep spend additional time re-processing ingesta via rumination, a strategy not used by Kangaroos. Kangaroos were more selective in their diet, having a narrower niche compared with sheep. The tubiform forestomach of Kangaroos appears to support long foraging bouts, mainly in the evening and early morning; Kangaroos rested during the hottest parts of the day. Conversely, sheep feed in short bursts, and gut-filling during feeding bouts is partly dependent on the animal freeing forestomach space by ruminating previous meals, possibly increasing water requirements of sheep through activity and thermal loads associated with more frequent feeding. Water use (L day � 1 ) by Kangaroos was just 13% that of sheep, and Kangaroos were able to concentrate their urine more effectively than sheep, even though the Kangaroos’ diet contained a high amount of high-salt chenopods, providing further support for potentially lower grazing impacts of Kangaroos compared with domestic sheep in Australia’s arid rangelands.
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field metabolic rate and water turnover of red Kangaroos and sheep in an arid rangeland an empirically derived dry sheep equivalent for Kangaroos
Australian Journal of Zoology, 2009Co-Authors: Adam J. Munn, David B Croft, Steven R. Mcleod, Michael B Thompson, Terence J. Dawson, Chris R DickmanAbstract:Sustainable management of pastures requires detailed knowledge of total grazing pressure, but this information is critically lacking in Australia’s rangelands where livestock co-occur with large herbivorous marsupials. We present the first comparative measure of the field metabolic rate (an index of food requirement) of Australia’s largest marsupial, the red Kangaroo (Macropus rufus), with that of domestic sheep (Ovis aries; merino breed). We tested the assumption that the grazing pressure of red Kangaroos is equivalent to 0.7 sheep, and show this to be a two-fold overestimation of their contribution to total grazing. Moreover, Kangaroos had extraordinarily lower rates of water turnover, being only 13% that of sheep. Consequently, our data support arguments that the removal of Kangaroos may not markedly improve rangeland capacity for domestic stock. Furthermore, given the low resource requirements of Kangaroos, their use in consumptive and non-consumptive enterprises can provide additional benefits for Australia’s rangelands than may occur under traditional rangeland practices.
Andrew A Biewener - One of the best experts on this subject based on the ideXlab platform.
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scaling of the ankle extensor muscle tendon units and the biomechanical implications for bipedal hopping locomotion in the post pouch Kangaroo macropus fuliginosus
Journal of Anatomy, 2017Co-Authors: Andrew A Biewener, Edward P Snelling, David A Taggart, Andrea Fuller, Duncan Mitchell, Shane K Maloney, Roger S SeymourAbstract:Bipedal hopping is used by macropods, including rat-Kangaroos, wallabies and Kangaroos (superfamily Macropodoidea). Interspecific scaling of the ankle extensor muscle-tendon units in the lower hindlimbs of these hopping bipeds shows that peak tendon stress increases disproportionately with body size. Consequently, large Kangaroos store and recover more strain energy in their tendons, making hopping more efficient, but their tendons are at greater risk of rupture. This is the first intraspecific scaling analysis on the functional morphology of the ankle extensor muscle-tendon units (gastrocnemius, plantaris and flexor digitorum longus) in one of the largest extant species of hopping mammal, the western grey Kangaroo Macropus fuliginosus (5.8–70.5 kg post-pouch body mass). The effective mechanical advantage of the ankle extensors does not vary with post-pouch body mass, scaling with an exponent not significantly different from 0.0. Therefore, larger Kangaroos balance rotational moments around the ankle by generating muscle forces proportional to weight-related gravitational forces. Maximum force is dependent upon the physiological cross-sectional area of the muscle, which we found scales geometrically with a mean exponent of only 0.67, rather than 1.0. Therefore, larger Kangaroos are limited in their capacity to oppose large external forces around the ankle, potentially compromising fast or accelerative hopping. The strain energy return capacity of the ankle extensor tendons increases with a mean exponent of ~1.0, which is much shallower than the exponent derived from interspecific analyses of hopping mammals (~1.4–1.9). Tendon safety factor (ratio of rupture stress to estimated peak hopping stress) is lowest in the gastrocnemius (< 2), and it decreases with body mass with an exponent of −0.15, extrapolating to a predicted rupture at 160 kg. Extinct giant Kangaroos weighing 250 kg could therefore not have engaged in fast hopping using ‘scaled-up’ lower hindlimb morphology of extant western grey Kangaroos.
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elastic energy storage in the hopping of Kangaroo rats dipodomys spectabilis
Journal of Zoology, 2009Co-Authors: Andrew A Biewener, Mcn R Alexander, Norman HeglundAbstract:Bipedal hopping of Kangaroo rats has been studied by making force plate records and X-ray cinematograph films simultaneously. Calculations using the data so obtained, and anatomical data, show that energy saving by elastic storage is much less important than in Kangaroos.
Natalie M Warburton - One of the best experts on this subject based on the ideXlab platform.
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The fibular meniscus of the Kangaroo as an adaptation against external tibial rotation during saltatorial locomotion.
Journal of Anatomy, 2017Co-Authors: Adrian C. Miller, Martin A. Cake, Natalie M WarburtonAbstract:The Kangaroo knee is, as in other species, a complex diarthrodial joint dependent on interacting osseous, cartilaginous and ligamentous components for its stability. While principal load bearing occurs through the femorotibial articulation, additional lateral articulations involving the fibula and lateral fabella also contribute to the functional arrangement. Several fibrocartilage and ligamentous structures in this joint remain unexplained or have been misunderstood in previous studies. In this study, we review the existing literature on the structure of the Kangaroo 'knee' before providing a new description of the gross anatomical and histological structures. In particular, we present strong evidence that the previously described 'femorofibular disc' is best described as a fibular meniscus on the basis of its gross and histological anatomy. Further, we found it to be joined by a distinct tendinous tract connecting one belly of the m. gastrocnemius with the lateral meniscus, via a hyaline cartilage cornu of the enlarged lateral fabella. The complex of ligaments connecting the fibular meniscus to the surrounding connective tissues and muscles appears to provide a strong resistance to external rotation of the tibia, via the restriction of independent movement of the proximal fibula. We suggest this may be an adaptation to resist the rotational torque applied across the joint during bipedal saltatory locomotion in Kangaroos.
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Anatomical adaptations of the hind limb musculature of tree-Kangaroos for arboreal locomotion (Marsupialia : Macropodinae)
Australian Journal of Zoology, 2012Co-Authors: Natalie M Warburton, Maud Yakovleff, Auréline MalricAbstract:Tree-Kangaroos (Dendrolagini) are Australasian marsupials that inhabit tropical forests of far north-eastern Queensland and New Guinea. The secondary adaptation of tree-Kangaroos to an arboreal lifestyle from a terrestrial heritage offers an excellent opportunity to study the adaptation of the musculoskeletal system for arboreal locomotion, particularly from a template well adapted to terrestrial bipedal saltation. We present a detailed descriptive study of the hind limb musculature of Lumholtz’s tree-Kangaroo (D. lumholtzi) in comparison to other macropodines to test whether the hind limb musculature of tree-Kangaroos is functionally adapted to the different mechanical demands of locomotion in the uneven three-dimensional arboreal environment. The hind limb musculature of Lumholtz’s tree-Kangaroo (Dendrolagus lumholtzi), the western brush wallaby (Macropus irma), the western grey Kangaroo (Macropus fuliginosus) and the quokka (Setonix brachyurus) are described. The hind limb anatomy of D. lumholtzi differed from that of the terrestrial macropodines in that the muscles had a greater degree of internal differentiation, relatively longer fleshy bellies and very short, stout tendons of insertion. There was also a modified arrangement of muscle origins and insertions that enhance mechanical advantage. Differences in the relative proportions of the hind limb muscle mass between tree-Kangaroos and terrestrial macropodines reflect adaptation of the limb musculature of tree-Kangaroos for arboreal locomotion. The hind limb musculature of Setonix was different to that of both Dendrolagus and Macropus, possibly reflecting its more basal phylogenetic position within the Macropodinae.
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Functional morphology of the forelimb of living and extinct tree-Kangaroos (Marsupialia: Macropodidae)
Journal of Morphology, 2011Co-Authors: Natalie M Warburton, Kathryn J. Harvey, Gavin J. Prideaux, James O'sheaAbstract:Tree-Kangaroos are a unique group of arboreal marsupials that evolved from terrestrial ancestors. The recent discovery of well-preserved specimens of extinct tree-Kangaroo species (genus Bohra) within Pleistocene cave deposits of south-central Australia provides a unique opportunity to examine adaptive evolution of tree-Kangaroos. Here, we provide the first detailed description of the functional anatomy of the forelimb, a central component of the locomotor complex, in the extant Dendrolagus lumholtzi, and compare its structure and function with representatives of other extant marsupial families. Several features were interpreted as adaptations for coping with a discontinuous, uneven and three-dimensional arboreal substrate through enhanced muscular strength and dexterity for propulsion, grasping, and gripping with the forelimbs. The forelimb musculoskeletal anatomy of Dendrolagus differed from terrestrial Kangaroos in the following principal ways: a stronger emphasis on the development of muscles groups responsible for adduction, grasping, and gripping; the enlargement of muscles that retract the humerus; and modified shape of the scapula and bony articulations of the forelimb bones to allow improved mobility. Many of these attributes are convergent with other arboreal marsupials. Tree-Kangaroos, however, still retain the characteristic bauplan of their terrestrial ancestors, particularly with regard to skeletal morphology, and the muscular anatomy of the forelimb highlights a basic conservatism within the group. In many instances, the skeletal remains of Bohra have similar features to Dendrolagus that suggest adaptations to an arboreal habit. Despite the irony of their retrieval from deposits of the Nullarbor “Treeless” Plain, forelimb morphology clearly shows that the species of Bohra were well adapted to an arboreal habitat.
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A new Pleistocene tree-Kangaroo (Diprotodontia: Macropodidae) from the Nullarbor Plain of south-central Australia
Journal of Vertebrate Paleontology, 2008Co-Authors: Gavin J. Prideaux, Natalie M WarburtonAbstract:This paper describes a new tree-Kangaroo of the extinct genus Bohra (B. illuminata sp. nov.). Its remains were collected from a diverse middle Pleistocene fauna preserved in caves recently discovered beneath the Nullarbor Plain of south-central Australia. The adult holotype and juvenile paratype are represented by associated cranial and postcranial material. They confirm that two previously known species, B. paulae and B. wilkinsonorum, which were described on the basis of disparate parts of the skeleton, are congeneric. While Bohra is closest in morphology to the extant tree-Kangaroo genus Dendrolagus, it shares several similarities with Petrogale (rock-wallabies). This is consistent with recent molecular studies that suggest that tree-Kangaroos and rock-wallabies share a common ancestry.
Jeremy F. Burn - One of the best experts on this subject based on the ideXlab platform.
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Scaling of elastic energy storage in mammalian limb tendons: do small mammals really lose out?
Biology Letters, 2005Co-Authors: Sharon R. Bullimore, Jeremy F. BurnAbstract:It is widely believed that elastic energy storage is more important in the locomotion of larger mammals. This is based on: (a) comparison of Kangaroos with the smaller Kangaroo rat; and (b) calculations that predict that the capacity for elastic energy storage relative to body mass increases with size. Here we argue that: (i) data from Kangaroos and Kangaroo rats cannot be generalized to other mammals; (ii) the elastic energy storage capacity relative to body mass is not indicative of the importance of elastic energy to an animal; and (iii) the contribution of elastic energy to the mechanical work of locomotion will not increase as rapidly with size as the mass-specific energy storage capacity, because larger mammals must do relatively more mechanical work per stride. We predict how the ratio of elastic energy storage to mechanical work will change with size in quadrupedal mammals by combining empirical scaling relationships from the literature. The results suggest that the percentage contribution of elastic energy to the mechanical work of locomotion decreases with size, so that elastic energy is more important in the locomotion of smaller mammals. This now needs to be tested experimentally.
Norman Heglund - One of the best experts on this subject based on the ideXlab platform.
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elastic energy storage in the hopping of Kangaroo rats dipodomys spectabilis
Journal of Zoology, 2009Co-Authors: Andrew A Biewener, Mcn R Alexander, Norman HeglundAbstract:Bipedal hopping of Kangaroo rats has been studied by making force plate records and X-ray cinematograph films simultaneously. Calculations using the data so obtained, and anatomical data, show that energy saving by elastic storage is much less important than in Kangaroos.