Herbivorous reptiles and body mass: Effects on food intake, digesta retention, digestibility and gut capacity, and a comparison with mammals

Differences in the allometric scaling between gut capacity (with body mass, BM1.00) and food intake (with BM0.75) should theoretically result in a scaling of digesta retention time with BM0.25 and therefore a higher digestive efficiency in larger herbivores. This concept is an important part of the so-called ‘Jarman-Bell principle’ (JBP) that explains niche differentiation along a body size gradient in terms of digestive physiology. Empirical data in herbivorous mammals, however, do not confirm the scaling of retention time, or of digestive efficiency, with body mass. Here, we test these concepts in herbivorous reptiles, adding data of an experiment that measured food intake, digesta retention, digestibility and gut capacity in 23 tortoises (Testudo graeca, T. hermanni , Geochelone nigra, G. sulcata, Dipsochelys dussumieri) across a large BM range (0.5-180 kg) to a literature data collection. While dry matter gut fill scaled to BM1.07 and dry matter intake to BM0.76, digesta mean retention time (MRT) scaled to BM0.17; the scaling exponent was not significantly different from zero for species > 1 kg. Food intake level was a major determinant of MRT across reptiles and mammals. In contrast to dietary fibre level, BM was not a significant contributor to dry matter digestibility in a General Linear Model. Digestibility coefficients in reptiles depended on diet nutrient composition in a similar way as described in mammals. Although food intake is generally lower and digesta retention longer in reptiles than in mammals, digestive functions scale in a similar way in both clades, indicating universal principles in herbivore digestive physiology. The reasons why the theoretically derived JBP has little empirical support remain to be investigated. Until then, the JBP should not be evoked to explain niche differentiation along a body size axis in terms of digestive physiology

Feeding enrichment by self-operated food boxes for white-fronted lemurs (Eulemur fulvus albifrons) in the Masoala exhibit of the Zurich Zoo

In the new Masoala exhibit of the Zurich Zoo four self-operated food boxes were installed to encourage arboreal behavior and higher activity levels, and to increase the attractiveness to visitors of a group of three white-fronted lemurs (Eulemur fulvus albifrons) and one Alaotran gentle lemur (Hapalemur griseus alaotrensis). Data obtained by direct observations with and without food boxes present were compared. In addition, visitors were surveyed to investigate attractiveness of the lemurs. Overall activity and locomotor behavior increased due to food box presentation. Furthermore, the visitor survey documented that the lemurs were spotted more often in trees when the food boxes were present. Because behavior patterns of the subjects approached natural levels with food boxes, the presentation of self-operated food boxes seems a valuable tool to improve the captive environment of lemurs

Rates of radiologically confirmed pneumonia as defined by the World Health Organization in Northern Territory Indigenous children

Objective: To determine the burden of hospitalised, radiologically confirmed pneumonia (World Health Organization protocol) in Northern Territory Indigenous children

Large induced interface dipole moments without charge transfer: Buckybowls on metal surfaces

Charge carrier injection barriers at interfaces are crucial for the performance of organic electronic devices. In this respect, tuning the electronic interface potential or, in case of the metallic electrode, the work function for electronic level alignment is crucial. However, poor control over the interface structure and the work function of the combined materials is an obstacle for better device performance. Here we show that bowl-shaped molecules, based on buckminsterfullerene, induce very large interface dipole moments of up to 8.8 D on a copper surface. It is shown experimentally and theoretically that charge transfer between both components is negligible. The origin of the large dipole moments is revealed via dispersion-enabled density functional theory, displaying a strong rearrangement of charge in the metal underneath the molecular adsorbate