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Hummel J.,University of Bonn | Hammer S.,Al Wabra Wildlife Preservation AWWP | Hammer C.,Al Wabra Wildlife Preservation AWWP | Ruf J.,University of Zürich | And 3 more authors.
Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology | Year: 2015

Digesta retention patterns have been suggested to play a major role in ruminant diversification. Two major digestion types have been proposed, termed 'cattle-type' and 'moose-type', that broadly correspond to the feeding categories of grazers and intermediate feeders on the one, and browsers on the other hand. We measured and calculated the mean retention time (MRT) of a solute and a particle (<2mm) marker in the gastrointestinal tract (GIT) and the reticulorumen (RR) of a small grazer, the Indian blackbuck (Antilope cervicapra, n=5, body mass of 26±4kg) and an intermediate feeder, the nilgai (Boselaphus tragocamelus, n=5, body mass of 168±21kg). MRTsolute and MRTparticle were 29±4.1h and 60±6.6h in blackbuck and 28±2.5h and 54±8.9h in the nilgai for the GIT, and 14±1.7h, 45±5.0h, 19±2.0h and 45±8.4h for the RR, respectively. With a selectivity factor (SF, the ratio of MRTparticle to MRTsolute) in the RR of 3.2±0.28 for blackbuck and 2.3±0.36 for nilgai, both species are clearly in the category of 'cattle-type' ruminants. In particular, the high SFRR of blackbuck, in spite of its small body size, is remarkable, and leads to specific predictions on the RR anatomy of this species (such as a particularly large omasum), which can be tested in further studies. The adaptive value of a high SFRR is mainly considered as an increase in microbial productivity in the RR. © 2014 Elsevier Inc.


Dittmann M.T.,University of Zürich | Dittmann M.T.,ETH Zurich | Hummel J.,University of Bonn | Hummel J.,University of Gottingen | And 9 more authors.
Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology | Year: 2015

Digesta flow plays an important role in ruminant digestive physiology. We measured the mean retention time (MRT) of a solute and a particle marker in the gastrointestinal tract (GIT) and the reticulorumen (RR) of five gazelles and one dikdik species. Species-specific differences were independent from body mass (BM) or food intake. Comparative evaluations (including up to 31 other ruminant species) indicate that MRT GIT relate positively to BM, and are less related to feeding type (the percentage of grass in the natural diet, %grass) than MRT RR. The MRTparticleRR is related to BM and (as a trend) %grass, matching a higher RR capacity with increasing BM in grazers compared to browsers. MRTsoluteRR is neither linked to BM nor to %grass but shows a consistent phylogenetic signal. Selectivity factors (SF; MRTparticle/MRTsolute, proxies for the degree of digesta washing) are positively related to %grass, with a threshold effect, where species with >20% grass have higher SF. These findings suggest that in different ruminant taxa, morphophysiological adaptations controlling MRTsoluteRR evolved to achieve a similar SF RR in relation to a %grass threshold. A high SF could facilitate an increased microbial yield from the forestomach. Reasons for variation in SF above the %grass threshold might represent important drivers of ruminant diversification and await closer investigation. © 2015.


Dittmann M.T.,University of Zürich | Dittmann M.T.,ETH Zurich | Hebel C.,Al Wabra Wildlife Preservation AWWP | Arif A.,Al Wabra Wildlife Preservation AWWP | And 2 more authors.
Mammalian Biology | Year: 2015

The basal metabolic rate of mammals correlates with body mass, but deviations from this regression have been observed and explanations comprise ecological adaptations, reproductive strategies or phylogeny. Certain mammalian groups, adapted to arid environments, show comparatively lower metabolic rates. To expand existing datasets and to investigate metabolic rates in ruminants adapted to arid environments, we conducted respiration measurements with three gazelle species (Gazella spekei, G. gazella and N. soemmerringii, total n = 16). After an adaptation period to a diet of fresh lucerne offered ad libitum, subjects were put separately into respiration boxes for 24. h where they had free access to food and water. Oxygen consumption and carbon dioxide production were measured with a modular system of gas analyzers and pumps. Mean and resting metabolic rate (RMR) were calculated by accounting for the entire measurement phase or the lowest 20 oxygen measurements, respectively. N. soemmerringii had the lowest relative RMR values and the highest respiratory coefficients compared to the other species. Measured values were compared to expected RMR values calculated based on body mass. Gazella spekei and G. gazella showed higher RMR values than expected, while the RMR of N. soemmerringii was in the range of expected values. Our results indicate that not all mammals adapted to aridity have lower metabolic rates under conditions of unlimited resources and that in these cases other physiological adaptations might be of higher importance. Further extensions of the datasets could allow explaining which deviations of metabolic rate from the body mass regressions result from convergent adaptations. © 2015 Deutsche Gesellschaft für Säugetierkunde.


Dittmann M.T.,University of Zürich | Dittmann M.T.,ETH Zurich | Hebel C.,Al Wabra Wildlife Preservation AWWP | Hammer S.,Al Wabra Wildlife Preservation AWWP | And 6 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2014

Basal metabolic rates in mammals are mainly determined by body mass, but also by ecological factors. Some mammalian species inhabiting hot, dry environments were found to have lower metabolic rates compared to temperate species. We studied energy metabolism in Phillip's dikdik (Madoqua saltiana phillipsi), a small antelope inhabiting xeric shrubland habitats in the Eastern 'horn' of Africa, and compared results to literature data. We measured body mass (BM) changes and digestibility in 12 adults kept on different food intake levels to determine, by extrapolation to zero BM change, maintenance energy requirements (MEm) for metabolizable energy (ME). The MEm averaged at 404±20kJMEkgBM-0.75d-1. In addition we conducted 24h-chamber respirometry with seven fed (non-fasted) individuals. Their mean metabolic rate as calculated from oxygen consumption was 403±51kJkgBM-0.75d-1, corroborating the results of the feeding experiments. Selecting the 20 lowest values of the respiration measurement period to estimate resting metabolic rate (RMR) resulted in a mean RMR of 244±39kJkgBM-0.75d-1, which was not significantly lower than the expected basal metabolic rate of 293kJkgBM-0.75d-1. Therefore, resting metabolism was similar to the expected average basal metabolism of a mammal of this size, which suggests a comparatively low metabolic rate in dikdiks. Compared to literature data Phillip's dikdiks have a MEm similar to measurements reported for small domestic ruminants, but considerably lower than those reported for other wild ruminant species inhabiting temperate and cold climates. © 2013.


Muller D.W.H.,University of Zürich | Hammer S.,Al Wabra Wildlife Preservation AWWP | Hammer C.,Al Wabra Wildlife Preservation AWWP | Hatt J..-M.,University of Zürich | Clauss M.,University of Zürich
International Zoo Yearbook | Year: 2013

Successful management of herds of captive wildlife (small populations) requires monitoring of herd size over years. In many zoos, herd size is documented in the course of annual inventories without considering other epidemiological parameters. Here, the concept of the 'anti-clockwise cycle' of the relation between mortality and population size is introduced for herd management. Four different phases of this cycle can be distinguished: (I) herd size increases while mortality decreases; (II) herd size and mortality increase; (III) herd size decreases and mortality still increases; (IV) herd size and mortality decrease. Consequently, a herd can still prosper in size (I, II) while an increase in mortality rates (II) already indicates that it is heading towards collapse (III). All four phases of the cycle of herd development could be observed in 28 small, closed ruminant breeding groups at the Al Wabra Wildlife Preservation, Qatar. Applications of the concept presented here to evaluate herd development in captivity may help to stabilize or even increase the size of a herd in care, which is particularly important for breeding herds of threatened species. The 'anti-clockwise cycle' shows that a simple monitoring of the herd size in numbers is not enough to evaluate the sustainability and quality of the herd. © 2013 The Zoological Society of London.


PubMed | University of Zürich, University of Bonn and Al Wabra Wildlife Preservation AWWP
Type: | Journal: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology | Year: 2015

Digesta retention patterns have been suggested to play a major role in ruminant diversification. Two major digestion types have been proposed, termed cattle-type and moose-type, that broadly correspond to the feeding categories of grazers and intermediate feeders on the one, and browsers on the other hand. We measured and calculated the mean retention time (MRT) of a solute and a particle (<2 mm) marker in the gastrointestinal tract (GIT) and the reticulorumen (RR) of a small grazer, the Indian blackbuck (Antilope cervicapra, n=5, body mass of 264 kg) and an intermediate feeder, the nilgai (Boselaphus tragocamelus, n=5, body mass of 16821 kg). MRT(solute) and MRT(particle) were 294.1 h and 606.6 h in blackbuck and 282.5 h and 548.9 h in the nilgai for the GIT, and 141.7 h, 455.0 h, 192.0 h and 458.4 h for the RR, respectively. With a selectivity factor (SF, the ratio of MRT(particle) to MRT(solute)) in the RR of 3.20.28 for blackbuck and 2.30.36 for nilgai, both species are clearly in the category of cattle-type ruminants. In particular, the high SFRR of blackbuck, in spite of its small body size, is remarkable, and leads to specific predictions on the RR anatomy of this species (such as a particularly large omasum), which can be tested in further studies. The adaptive value of a high SFRR is mainly considered as an increase in microbial productivity in the RR.

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