DIGESTIVE AND FEEDING BEHAVIOR DIFFERENCES BETWEEN LAPPET-FACED VULTURES (TORGOS TRACHELIOTOS) AND GRIFFON VULTURES (GYPS FULVUS) EX SITU.

Appropriate diets for ex situ wildlife are essential for animal health and welfare and yet ex situ facilities are often constrained by feed ingredient availability when attempting to replicate natural diets. In obligate carnivores such as vultures, digestive strategies are likely to have evolved alongside feeding behaviors, which may differ between even sympatric species. To begin to understand the digestive strategies of two Old World vulture species (lappet-faced vulture Torgos tracheliotos, n = 3, and griffon vulture Gyps fulvus, n = 4) of similar body size but divergent feeding habits, their feeding and digestion strategies on a diet of whole rats were compared. The food intake, color of excreta, excreta consistency, and carbon and nitrogen excretion were measured. Mean retention time of the digesta was analyzed using titanium dioxide as an inert marker in a diet of chicken carcass. Lappet-faced vultures consumed significantly greater quantities of food than griffon vultures and were less selective. Lappet-faced vultures primarily produced brown excreta while griffon vultures primarily produced green excreta, with much higher carbon and nitrogen concentrations. The consistency of excreta and the mean retention time did not differ between the species but may have been too variable to detect differences. A strong positive correlation was found between food intake per metabolic weight and the proportion of brown excreta, and both were negatively correlated with green excreta, as well as excreta concentrations of nitrogen and carbon. These findings align with their reported feeding ecology, with lappet-faced vultures showing adaptations to less-digestible carcass material compared with griffon vultures. Despite their similar size and overlapping natural habitat, these results suggest a need for differentiated feed provisioning for these species when under human care.

Method development to characterise elephant tail hairs by LA-ICP-MS to reflect changes in elemental chemistry.

This paper evaluated analytical methods used to generate time-series data from elephant tail hairs, which can be used to reflect changing exposure to environmental geochemistry. Elephant tail hairs were analysed by three methods sequentially, each providing data to inform subsequent analysis. Scanning Electron Microscopy (SEM) and X-ray Microanalysis visually showed the structure of the hair, specific structures such as tubules, and the mineral crusting around the edge of the hair, informing targeting of subsequent analysis by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). LA-ICP-MS generated time-series data which informed sectioning of the tail hairs for subsequent quantitative analysis for potentially toxic elements and micronutrients using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) of dissolved tail hairs. This novel approach to characterise the tail hair enabled time-series analysis to reflect changes in environmental exposure which may result from seasonal or geochemical spatial variation and could inform elephant movement patterns. The seasonal change between wet and dry seasons was reflected down the length of the hair. Correlations were seen between LA-ICP-MS data and ICP-MS data in several elements including Mg, P, Ca, Fe, Na, Mn and U. This study provided time-series data for the analysis of elephant tail hairs by evaluating analytical challenges to obtaining quantitative data, such as improving protocols to ensure removal of extraneous material, determining where to section the tail hairs to best reflect environmental changes/exposure and ensuring representative analyses. A protocol was established to determine mineral status across a 12-18 month time period utilizing single elephant tail hairs.

Nutrition of free-living Neotropical psittacine nestlings and implications for hand-feeding formulas.

Psittacidae is one of the most endangered families of birds in the world. Knowledge of their nutrition is important for understanding their survival and productivity in the wild, as well as for their adequate husbandry under human care. Hand-rearing is a common practice for psittacines, however research on their nutrition is limited. We analysed the predicted metabolisable energy, crude protein, crude fat, minerals and the essential amino acid profiles of the crop contents from free-living nestlings of scarlet macaws (Ara macao) and red-and-green macaws (Ara chloropterus) from southeastern Peru, Cuban Amazons (Amazona leucocephala bahamensis) from the Bahamas, lilac-crowned Amazons (Amazona finschi) from northwestern Mexico and thick-billed parrots (Rhynchopsitta pachyrhyncha) from northern Mexico. The crop content of the different parrot species displayed remarkably similar nutritional profiles, considering their diversity in habitats, geographic ranges and food sources. The crude protein and crude fat concentrations in crop samples were particularly similar for the Ara and Amazona species, while the thick-billed parrot stood out for its higher crude fat and lower crude protein content. Wider variations were found among the concentrations of sodium (Na) and iron (Fe), proline and tryptophan. Compared with the requirements of 6-12 weeks leghorn chickens, all free-ranging parrot diets contained lower crude protein, calcium (Ca), potassium (P) and Na concentrations. The hand-feeding formulas contained lower crude fat, magnesium (Mg), arginine, valine and phenylalanine concentrations, as well as much higher levels of Ca and zinc (Zn), in comparison with parrot crop samples. Our data suggest that a single formulation could be used to hand-rear Ara and Amazona sp. of 3 weeks of age and older, while a different formulation would likely be more appropriated for Rhynchopsitta sp. Experimental studies should evaluate if increasing the concentration of crude fat, Mg, arginine, valine and phenylalanine enhances psittacine chick growth and health.

Balancing the scales: Preliminary investigation of total energy expenditure and daily metabolizable energy intake in Matschie's tree kangaroo (Dendrolagus matschiei).

Matschie's tree kangaroo (Dendrolagus matschiei) is an endangered arboreal marsupial native to Papua New Guinea. Detailed field studies of its behavior and ecology are scarce due largely to its occupation of remote cloud forests and cryptic nature. Although this species has been in human care since the 1950s, much of its biology is still unknown. The current ex situ population is not sustainable due to health and reproductive problems, believed to stem largely from issues with diet and obesity. To better assess potential discrepancies between energy requirements and energy intake, we sought to 1) quantify total energy expenditure (TEE) of two zoo-housed Matschie's tree kangaroos (body mass = 9.0-9.7 kg) on a diet composed largely of leafy browse; 2) quantify food and macronutrient intake, apparent dry matter macronutrient digestibility, and metabolizable energy (ME) intake over a 14-month period; and 3) test for seasonal changes in ME intake due to seasonal differences in the varieties of leafy browse offered. Using the doubly labeled water method, we determined TEE for the female (288 kcal day -1) and male (411 kcal day -1). Resulting mean TEE was well below the expected value for marsupials and macropods (i.e., ~60% of the expected value based on body mass). The mean calculated ME intakes for the female and male were 307 kcal day-1 and 454 kcal day-1, respectively. There were significant seasonal differences in ME intakes, driven by reduced intake in the autumn. These results demonstrate that Matschie's tree kangaroos can be maintained at healthy body weights and conditions on fiber-rich and browse-heavy diets. Our findings contribute important insights into tree kangaroo energetics and physiology and can be applied to help reformulate the diet of Matschie's tree kangaroos at captive facilities to improve population health and sustainability.

Recommendations and Action Plans to Improve Ex Situ Nutrition and Health of Marine Teleosts.

The International Workshop for Ex-Situ Marine Teleost Nutrition and Health, hosted by Disney's Animals, Science and Environment in conjunction with the Comparative Nutrition Society, brought together over 50 animal experts and scientists representing 20 institutions to review current science and identify challenges of marine teleost nutrition and health. Invited speakers presented critical information and current research topics for areas of emphasis and expertise. Subject matter experts identified knowledge gaps and primary areas of focus to guide the scientific community's research efforts to improve the care of ex situ marine teleosts. The clinical medicine working group highlighted standardized approaches to ante- and postmortem sample collection, diet biosecurity and supplementation, advanced diagnostic methods, and expanded training in fish nutrition. Nutrition identified the creation of a husbandry and feeding management manual, comprehensive feeding program review and design, and specialty feeder/life stage nutrition as areas of focus, while animal husbandry focused on body condition scoring, feed delivery techniques, and behavioral husbandry topics. The physiology and chemistry and water quality working groups discussed components of the aquatic environment and their effects on fish health, including organic matter constituents, microbial diversity, disinfection, and managing microbiota. Finally, we reviewed how epidemiological approaches and considerations can improve our evaluation of aquarium teleost nutrition and health. The goals outlined by each working group and supporting literature discussion are detailed in this communication and represent our goals for the next 3 to 5 years, with the ultimate objective of the workshop being the production of a husbandry manual for marine teleost nutrition and health. Any scientists who feel that their experience, research, or interests align with these goals are invited to participate by contacting the authors.

Retrospective Analysis of Cataract Formation and Nutritional Etiology in a Managed Collection of Parakeet Auklets (Aethia psittacula).

The parakeet auklet (Aethia psittacula) is a piscivorous seabird with a natural diet of various invertebrate and teleost species, which is challenging to replicate in a managed collection. A high prevalence of early onset cataracts was observed in a managed collection of parakeet auklets at the North Carolina Zoo (Asheboro, NC, USA), which was hypothesized to be related to inappropriate vitamin A and E levels. From 1994 to 2002, these parakeet auklets were offered dietary supplementation comprising Vita-Zu small bird tablets. In June 2002, the birds were transitioned to only Thiamin-E paste (vitamin E and thiamin only). Plasma samples were collected from birds with and without cataracts from 1998 to 2005 and submitted for vitamin A (retinol) and vitamin E (α-tocopherol) analysis. Food items comprising the birds' diet were also evaluated for vitamin content. This information was combined with clinical and necropsy data from medical records from 1994 to 2015. A total of 78% of birds (39/50) developed cataracts, with a median age of onset of 7 years (range, 2-12 years). Cataracts ranged from incipient to hypermature during both routine ophthalmic examinations and postmortem evaluations. The median (range) of plasma retinol and α-tocopherol values were 1.99 µg/mL (0.20-6.68 µg/mL) and 15.39 µg/mL (3.40-96.27 µg/mL), respectively. There were no significant differences in plasma concentrations of vitamins based on the animals' sex, origin, presence of cataracts, or administered vitamin supplementation product. No other etiologies for cataract development were identified in the population. Further research in free-ranging parakeet auklet nutrition and cataract occurrence is warranted for continued species collection management.

Starch and fiber intake effects on energy metabolism, growth, and carapacial scute pyramiding of red-footed tortoise hatchlings (Chelonoidis carbonaria).

Tortoise husbandry includes reports of excessive growth and carapace pyramiding, although triggers still remain to be fully elucidated. Juvenile red-footed tortoises (Chelonoidis carbonaria) were fed with two different diets, one high in fiber (HF; 14.2% crude fiber; 39.2% neutral detergent fiber, NDF; dry matter basis, DMB) and one high in starch (HS; 27.7% DMB), to assess effects on energy metabolism, nutrient digestibility, and growth. A total of 20 hatchlings (10 per diet) were used to evaluate: apparent digestibility coefficients (Da) of nutrients and gross energy (GE), passage times at 5 and 11 months of age; resting and post-prandial metabolic rates at 6 and 12 months of age; growth rates; pyramiding; and estimated body composition. Animals fed HS showed higher mass-specific intake of digestible energy (113.9 ± 32.1 kJ kg-1 day-1 vs. 99.6 ± 35.3 kJ kg-1 day-1; P < 0.05), digestible DM (6.1 ± 1.8 g kg-1 day-1 vs. 5.0 ± 1.8 g kg-1 day-1; P < 0.01), shorter transit (3 ± 1 days vs. 4 ± 1 days; P < 0.01) and retention times (8 ± 2 days vs. 10 ± 2 days; P < 0.01), and higher Da of DM, starch, NDF, and GE. Crude protein Da was higher for HF. Rest and post-prandial metabolic rates, and pyramiding degree were not affected by diets. At 13 months, the animals from HS presented wider plastrons and carapaces, and higher carapace width growth rates. In addition, these animals had lower body mineral content (1.88 ± 0.15% vs. 2.15 ± 0.19%; P < 0.01) and bone density (0.13 ± 0.01 g mm-2 vs. 0.15 ± 0.02 g mm-2; P < 0.02). Results provide evidence that highly digestible foods can accelerate shell growth and lower mineralization in this species.

A comparison of nutritional value of native and alien food plants for a critically endangered island flying-fox.

Habitat loss and alteration are two of the biggest threats facing insular flying-foxes. Altered habitats are often re-vegetated with introduced or domestic plant species on which flying-foxes may forage. However, these alien food plants may not meet the nutritional requirements of flying-foxes. The critically endangered Christmas Island flying-fox (CIFF; Pteropus natalis) is subject to habitat alteration and the introduction of alien food plants, and therefore is a good model species to evaluate the potential impact of alien plant species on insular flying-foxes. In this study, we evaluated nutritional content of native food plants to determine how flying-foxes historically met their nutritional requirements. Furthermore, we compared the nutritional content of native and alien fruits to predict possible impacts of alien plants on insular flying-foxes. Native and alien fruits and flowers, and native foliage (leaves, petals, and petioles) commonly consumed by the CIFF were collected and evaluated for soluble sugars, crude protein, non-fiber carbohydrates, and nine minerals. Evaluation of native food plants suggests that flying-foxes meet energy requirements by consuming fruit and nectar. However, fruit and nectar are low in protein and essential minerals required for demanding life periods; therefore, flying-foxes likely supplement their diets with pollen and foliage. Thus, flying-foxes require a diverse array of plants to meet their nutritional requirements. Compared to native fruits, alien fruits contained significantly higher non-fiber carbohydrates, and this may provide an important energy source, particularly from species that bear fruit year-round. Median mineral concentrations in alien fruit species, however, were deficient compared to native fruits, suggesting major (or even seasonal) shifts in the proportion of alien species in the CIFF diet could lead to nutritional imbalances. This study confirms the need to quantify nutritional parameters in addition to feeding ecology when evaluating habitat quality to inform conservation actions that can be applied both locally and globally.

Fatty acid profiles of crop contents of free-living psittacine nestlings and of commercial hand-feeding formulas.

Research on psittacine nutrition is limited, and nestling requirements are poorly understood. This study analysed fatty acid (FA) profiles of crop contents of free-living scarlet macaws (Ara macao, n = 18), red-and-green macaws (Ara chloropterus, n = 5), Cuban parrots (Amazona leucocephala bahamensis, n = 27), lilac-crowned Amazons (Amazona finschi, n = 33) and thick-billed parrots (Rhynchopsitta pachyrhyncha, n = 32). The same analysis was carried out on 15 commercial parrot hand-feeding formulas. The mean FA concentration of the crop samples of each species ranged from 15% to 53% DM for crop samples and ranged from 6% to 22% for hand-feeding formulas. Long-chain FA represented over 92% of all FA in the crop samples and over 81% of all FA in the commercial formulas. Parrot species shared similarities in saturation profiles of crop samples, ranging between 13%-29% saturated fatty acids (SFA), 12%-40% monounsaturated fatty acids (MUFA) and 39%-58% polyunsaturated fatty acids (PUFA). All studied psittacines, except for the red-and-green macaw, were within the range of values for hand-rearing formulas. Palmitic acid was the most common SFA in scarlet macaws, red-and-green macaws, Cuban parrot, thick-billed parrot and in all but one commercial formula. Palmitic and stearic acids dominated the SFA in the samples of the Lilac-crowned Amazon. Oleic acid was the most common MUFA in all hand-feeding formulas as well as in the crop samples, except for the lilac-crowned amazon and the thick-billed parrot where vaccenic acid dominated. Linoleic acid was by far the most common PUFA found in the crop samples as well as in the hand-feeding formulas. PUFA were largely dominated by the n6 family, both in the crop samples and the formulas. The data presented on nestling diets of free-living parrot species provide a foundation for future researchers to test whether increasing FA concentration in hand-feeding formulas improves nestling development or if species-specific formulas will be advantageous.

Feed intake and dietary composition of iron (Fe), copper (Cu), vitamin E, and tannic acid of five captive black rhinoceros (Diceros bicornis) in a UK collection.

The black rhinoceros (Diceros bicornis) is a critically endangered species facing multiple anthropogenic pressures in its natural home range across Africa. Black rhinoceros are difficult to maintain ex situ and subject to diseases that are linked with captive dietary factors. Hemochromatosis is of particular concern, as it is a common finding at necropsy of captive adults, and has been linked to excessive dietary iron intake. This intake study investigates the select nutrient composition of the diets offered to and consumed by five captive black rhinoceros in a UK zoo to evaluate, ensure adequacy, and/or make adjustments if necessary. Alfalfa hay, pellets and six browse species offered were analyzed for iron (Fe), copper (Cu), vitamin E, and tannic acid content. Intakes were quantified and evaluated against levels found in wild diets and the currently available feeding guidelines for black rhinoceros. Diets eaten by five individual rhinoceros (1.4%-2.3% of bodyweight dry matter [DM] intake), comprising 68%-82% hay, 6%-13% pellets, and 13%-27% browse, contained 76-98 mg/kg Fe (on a DM basis), fell within the ranges of plants eaten by free-ranging rhinoceros (45-140 mg/kg DM), as well as values recommended for captive-fed browsing rhinoceros (50-100 mg/kg DM). Consumed diets were found to be marginal to adequate in Cu (9-11 mg/kg DM) compared with the recommended 10 mg/kg DM; dietary vitamin E ranged from 54 to 79 IU/kg DM, and tannic acid measured 13-14 g/kg DM. Commercial pellets were the primary contributor of dietary Fe, Cu, and vitamin E, containing up to 10 times more of each of those nutrients than the forages. Native browses were important sources of lower Fe ingredients, as well as appropriate levels of dietary Cu and vitamin E (dependent on species). Interestingly, pellets (23 g/kg) and alfalfa hay (14 g/kg) contained higher concentrations of tannic acid compared with any of the browses fed (4-13 g/kg). All nutritional parameters evaluated were close to recommended dietary levels, diets resembled values consumed in the wild, and the animals remained clinically healthy throughout the study. Overall, diets were considered nutritionally adequate for captive feeding of black rhinoceros; evaluating the nutrient composition of all ingredients, including browse plants in diets, provides important information for achieving optimal nutrient balance.

Potential bio-indicators for assessment of mineral status in elephants.

The aim of this study was two-fold: (1) identify suitable bio-indicators to assess elemental status in elephants using captive elephant samples, and (2) understand how geochemistry influences mineral intake. Tail hair, toenail, faeces, plasma and urine were collected quarterly from 21 elephants at five UK zoos. All elephant food, soil from enclosure(s), and drinking water were also sampled. Elemental analysis was conducted on all samples, using inductively coupled plasma mass spectrometry, focusing on biologically functional minerals (Ca, Cu, Fe, K, Mg, Mn, Na, P, Se and Zn) and trace metals (As, Cd, Pb, U and V). Linear mixed modelling was used to identify how keeper-fed diet, water and soil were reflected in sample bio-indicators. No sample matrix reflected the status of all assessed elements. Toenail was the best bio-indicator of intake for the most elements reviewed in this study, with keeper-fed diet being the strongest predictor. Calcium status was reflected in faeces, (p 0.019, R2 between elephant within zoo - 0.608). In this study urine was of no value in determining mineral status here and plasma was of limited value. Results aimed to define the most suitable bio-indicators to assess captive animal health and encourage onward application to wildlife management.

Spatial geochemistry influences the home range of elephants.

The unique geochemistry surrounding the Palabora Mining Company (PMC) land may act as a micronutrient hotspot, attracting elephants to the area. The PMC produces refined copper and extracts phosphates and other minerals. Understanding the spatial influence of geochemistry on the home range size of African elephants is important for elephant population management and conservation. The home ranges of collared elephants surrounding the PMC were significantly smaller (P = 0.001) than conspecifics in surrounding reserves, suggesting that their resource needs were met within these smaller areas. Environmental samples (soil, water and plants) were analysed from the mine area and along six transects radiating from the mine centre. Tail hair and faecal samples from elephants at the PMC, and conspecifics within the surrounding area were analysed. All samples were analysed for minerals essential to health and potentially toxic elements (PTEs; As, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, P, Pb, Se, U, V and Zn). Results show that the geochemistry at the PMC is different compared to surrounding areas, with significant elevations seen in all analysed minerals and PTEs in soil closer to the mine, thereby drawing the elephants to the area. Additionally significant elevations were seen in elements analysed in water and vegetation samples. Elephant tail hair from elephants at the mine was significantly greater in Cd, whilst Mg, P, Cu, As, Cd, Pb and U concentrations were significantly greater in elephant faecal samples at the mine compared to the non-mine samples. When micronutrient hotspots overlap with human activity (such as mining), this can lead to poor human-elephant coexistence and thus conflict. When managing elephant populations, the influence of mineral provision on elephant movement must be considered. Such detailed resource information can inform conservation efforts for coordinated programmes (UN SDGs 15 and 17) and underpin sustainable economic activity (UN SDG 8, 11 and 12).

Composition of browses consumed by Matschie's tree kangaroo (Dendrolagus matschiei) sampled from home ranges in Papua New Guinea.

Twenty-six samples (n = 24 spp.) of foods eaten, including ferns, shrubs, vines, orchids, herbaceous plants, and tree leaves, were collected from the Yopno, Uruwa, and Som Conservation Area at approximately 1,800 m altitude on the Huon Peninsula, Papua New Guinea (PNG). Samples were weighed fresh in the field and transported to the Lae National Herbarium in PNG for drying and confirmed identification, before transporting to the US for analysis of primary nutrient composition and minerals. Water content averaged 76 ± 10% (mean ± standard deviation); on a dry matter (DM) basis, foods averaged moderate protein (11 ± 5%), and soluble carbohydrate (27 ± 8%) content, along with exceptionally low starch (1 ± 1%) and crude fat (3 ± 2%) values, and moderate to high values in fiber fractions (neutral detergent fiber 52 ± 13%, acid detergent fiber 39 ± 10%, lignin 15 ± 6%). Calculated metabolizable energy content of native forages averaged 1.9 ± 0.3 Mcal/kg DM (ruminant model). Macromineral concentrations (DM basis) were not exceptional (calcium 1.1 ± 1.0%, phosphorus 0.2 ± 0.1%, magnesium 0.3 ± 0.2%, potassium 1.8 ± 0.9%, sodium 0.02 ± 0.02%), and select trace minerals were within anticipated ranges for herbivores (copper 12 ± 13 mg/kg, iron 48 ± 26 mg/kg, zinc 34 ± 18 mg/kg) with the exception of manganese (268 ± 225 mg/kg), which could be considered on the high end of dietary adequacy for most herbivores. These data provide useful information that can be used to adjust nutrient targets for dietary development and feeding management of captive populations of tree kangaroos.

Milk Composition of Asian Elephants (Elephas maximus) in a Natural Environment in Myanmar during Late Lactation.

The nutritional content of milk from free-living Asian elephants has not previously been reported, despite being vital for better management of captive populations. This study analyzed both milk composition and consumed plant species of Asian elephants managed in their natural environment in Myanmar. Longitudinal samples (n = 36) were obtained during both the wet and the dry season from six mature females in mid to late lactation in 2016 and 2017. Milk composition averaged 82.44% water, with 17.56% total solids containing 5.23% protein, 15.10% fat, 0.87% ash, and 0.18 µg/mL vitamin E. Solids and protein increased with lactation month. Total protein in milk was higher during the wet vs. the dry season. Observed factors linked with maternal (age, parity, size and origin) and calf traits (sex) had significant associations with milk nutrient levels. Primary forages consumed contained moderate protein and fiber. Higher dietary protein during the wet season (11-25%) compared to the dry season (6-19%) may be linked with increased milk protein observed. Our results call for further field studies of milk and diet composition, over entire seasons/lactation periods, and across maternal and calf traits, to improve feeding management, with an overall goal of maximized health and survival.

Circulating nutrient concentrations in free-ranging Humboldt penguins (Spheniscus humboldti) in Punta San Juan, Peru.

Free-ranging Humboldt penguin (HP, Spheniscus humboldti) populations are under pressure from resource competition with industrial fisheries, habitat loss, and El Niño Southern Oscillation events. Foraging patterns for this top marine predator change during periods of aberrant oceanographic conditions and scarce fish stock numbers. These radical dietary fluctuations can lead to poor fertility, early embryonic death, poor hatchability, suppressed immune function, high chick mortality, and illness. To understand the variability of nutrient status in reproductive seasons, we measured select circulating nutrient concentrations (fat-soluble vitamins A, D, E, and carotenoids, fatty acids, amino acids, minerals, and electrolytes) of 105 HP at Punta San Juan, Peru during the first reproductive seasons of 2007 and 2008. We determined significant differences in nutrient status between sexes, years of sampling, and reproductive stages. Males (4.5 ± 0.38 kg) weighed more than females (4.0 ± 0.29 kg) and exhibited higher concentrations of vitamin A (0.71 ± 0.11 vs. 0.61 ± 0.12 µg/ml) and docosahexaenoic acid (6.70 ± 1.61 vs. 5.65 ± 1.59%). Males also displayed lower concentrations of ß-carotene (0.01 ± 0.01 vs. 0.012 ± 0.001 µg/ml) and phosphorus (3.43 ± 0.83 vs. 4.40 ± 1.66 mg/dl). Comparison between the 2 years showed most circulating amino acid concentrations were higher in 2007. Significant differences in circulating amino acids and vitamins were also noted between different reproductive stages. These results demonstrate concentrations of nutrients can vary due to the physiological state of the animal, as well as the overall dynamics of their marine ecosystem habitat.

Captivity-induced metabolic programming in an endangered felid: implications for species conservation.

Reintroduction of captive-bred individuals into the wild is an important conservation activity. However, environmental conditions can influence developmental programming, potentially causing metabolic disorders in adults. These effects are investigated here for the first time in an endangered species. Using body weight and feed intake data for Iberian lynx (Lynx pardinus) (n = 22), we compared the growth of captive versus wild born and/or reared individuals. Captive-born individuals gained weight as a function of calorie intake, unlike wild-born individuals. When compared with females reared in the wild, captive-reared females achieved a larger body size, without evidence of obesity. Captivity-associated changes to metabolic programming may compromise survival in the wild if an increased body size incurs a greater energy requirement. Large body size may also confer a competitive advantage over smaller, wild-born individuals, disrupting the social organisation of existing wild populations, and inferring long-term implications for the phenotypic composition of wild populations.

Gaining insights in the nutritional metabolism of amphibians: analyzing body nutrient profiles of the African clawed frog, Xenopus laevis.

Whole bodies of Xenopus laevis (n = 19) were analysed for chemical composition and morphometrics. The nutrient profile (macronutrients, amino acids, fatty acids and minerals) was evaluated by sex; interactions among variables with body weights and lengths, and comparisons made with different species of marine and fresh water fish. Significant differences were found in morphometric measurements, water content, several minerals and fatty acids between sexes of X. laevis. Amino acid profiles differed in methionine, proline and cysteine, which could underlie different metabolic pathways in frogs when compared to fish. In addition, fatty acid profiles revealed more monounsaturated and n - 6 polyunsaturated fatty acids in frogs than in fish, more similar to values reported for terrestrial than aquatic vertebrates. Important interactions were also found between body measurements and fat, calcium, and phosphorus, as well as between essential and non-essential amino acids. The results indicate that frogs might have particular biochemical pathways for several nutrients, dependent on sex and linked to body weight, which ultimately could reflect specific nutrient needs.

African savanna elephants (Loxodonta africana) as an example of a herbivore making movement choices based on nutritional needs.

BACKGROUND: The increasing human population and global intensification of agriculture have had a major impact on the world's natural ecosystems and caused devastating effects on populations of mega-herbivores such as the African savanna elephants, through habitat reduction and fragmentation and increased human-animal conflict. Animals with vast home ranges are forced into increasingly smaller geographical areas, often restricted by fencing or encroaching anthropogenic activities, resulting in huge pressures on these areas to meet the animals' resource needs. This can present a nutritional challenge and cause animals to adapt their movement patterns to meet their dietary needs for specific minerals, potentially causing human-animal conflict. The aim of this review is to consolidate understanding of nutritional drivers for animal movement, especially that of African savanna elephants and focus the direction of future research. Peer reviewed literature available was generally geographically specific and studies conducted on isolated populations of individual species. African savanna elephants have the capacity to extensively alter the landscape and have been more greatly studied than other herbivores, making them a good example species to use for this review. Alongside this, their movement choices, potentially linked with nutritional drivers could be applicable to a range of other species. Relevant case study examples of other herbivores moving based on nutritional needs are discussed. METHODS: Three databases were searched in this review: Scopus, Web of Science and Google Scholar, using identified search terms. Inclusion and exclusion criteria were determined and applied as required. Additional grey literature was reviewed as appropriate. RESULTS: Initial searches yielded 1,870 records prior to application of inclusion and exclusion criteria. A less detailed review of grey literature, and additional peer-reviewed literature which did not meet the inclusion criteria but was deemed relevant by the authors was also conducted to ensure thorough coverage of the subject. DISCUSSION: A review of peer reviewed literature was undertaken to examine nutritional drivers for African elephant movement, exploring documented examples from free-ranging African savanna elephants and, where relevant, other herbivore species. This could help inform prediction or mitigation of human-elephant conflict, potentially when animals move according to nutritional needs, and related drivers for this movement. In addition, appropriate grey literature was included to capture current research.

The interplay between voluntary food intake, dietary carbohydrate-lipid ratio and nutrient metabolism in an amphibian, (Xenopus laevis).

Digestion of food and metabolism of frogs are little studied at the moment, and such processes could be very particular in the case of amphibians, given their ectothermic and carnivorous nature which may lead them to use nutrients through specific biochemical pathways. In the present study, 24 adult Xenopus laevis (six replicates with two frogs per treatment) were randomly assigned to two diets with different carbohydrate:fat ratio (4.5:1 and 2.1:1), changing the dietary glucogenic and lipogenic proportions. Food intake (FI) per unit metabolic body weight (MBW) as well as macronutrient digestibility were calculated, and circulating blood acylcarnitines and amino acids measured, in order to evaluate the effect of the diet treatments. Results demonstrated that food intake regulated most of the changes in the parameters evaluated; significant differences were obtained in crude protein and fat digestibilities through the effect of FI/MBW (p<0.05), whereas diet treatment had a significant effect on the levels of malonyl-CoA. Food intake also significantly impacted malonyl, isovaleryl, hydroxyisovaleryl and long chain fatty acid concentrations; significant (p<0.05) interactions between those metabolites were detected owing to diet. The findings obtained suggest that food intake was the main factor controlling digestion and metabolism in X. laevis, with frogs preferring to utilise protein and fat as primary sources for energy production in the citric acid cycle, reflecting characteristics of a strict carnivore physiological model.

Exploiting a readily available but hard to digest resource: A review of exudativorous mammals identified thus far and how they cope in captivity.

Gum is a widely available carbohydrate, composed mainly of non-digestible structural carbohydrates. No mammalian enzymes can digest gum; therefore, a mammal ingesting gum must rely on microbial fermentation to access the energy it possesses. Gums are relatively nutrient poor. Despite this, some mammals have evolved to exploit this food resource. We aim to review the literature for all mammal species which have been recorded to ingest gum, whether quantified or not, and discuss this in the context of their evolutionary adaptations. We also investigated the recommended captive diets for these species to look at whether gum is recommended. We conducted a literature search on ISI Web of Knowledge to tabulate all mammal species observed ingesting gum and classified them as obligate, facultative or opportunistic feeders. We encountered 94 mammal species that eat gum in the wild (27 obligate feeders, 34 facultative feeders and 33 opportunistic feeders). Obligate feeders have entirely evolved to exploit this resource but were found to not be given gum in captivity, which may explain why they are failing to thrive, as opposed to facultative feeders, which have fewer issues. Gum may be necessary for the health of obligate feeders in captivity. Future research should focus on the physiological effects that gum ingestion poses on different digestive systems.