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Nutrition research on calcium homeostasis. II. Freshwater turtles (with recommendations)
Abstract
This review reports on a decade of nutrition research into calcium (Ca) homeostasis in freshwater turtles, including research on non-nutritive factors that are essential for Ca homeostasis [i.e. ontogeny, environmental temperature and humidity, and ultraviolet (UV) light and photoreception]. Recommendations for future research include long-term research programmes in three specific areas: (1) photoreception, UV light and biosynthesis, (2) Ca homeostasis and vitamin and mineral supplementation, and (3) developmental indices, gut transit time (GTT) and energy requirements.
... The Ca and P contents of the pellets and lyophilised beef heart were much lower than those of Gammarus and whole fish. Imbalanced diets having low Ca content lead to metabolic bone disease of nutritional origin in aquatic turtles as well (73). However, excess Ca intake (2.24% DM) may have a negative impact on the growth rate of aquatic turtles (74). ...
Captive chelonians should be fed a natural diet to achieve a growth rate similar to that of free-ranging animals. A wide range of commercially formulated foods dedicated to chelonians is available. Feeding commercial foods has the advantage of convenience. On the other hand, species-specific information on the nutritional requirements of chelonians is not available yet. The aim of this study was to analyse and evaluate commercial pellets and feeds for chelonians. Commercial pellets (ntortoise = 7, nturtle = 7, from 6 companies) dedicated to carnivorous aquatic turtles and herbivorous terrestrial tortoises, and other aquatic turtle feeds (lyophilised beef heart, dried aquatic invertebrates, and whole frozen fish) were bought in pet shops. Whole frozen fish served as a reference feed for carnivorous aquatic turtles. The chemical composition as well as calcium (Ca) and phosphorus (P) contents were determined. Single-sample t-test was used with the label information as null hypothesis and the results of own parallel analyses for crude protein (CP), ether extract (EE), crude fibre (CF), Ca and P. The labelling of some of the pellets was deficient as nutritive values, Ca or P data were missing (tortoise pellets: 4 out of 7; turtle pellets: 5 out of 7). The label data differed significantly (p<0.05) from the results of our own analysis for 13 out of the 14 pellets. None of the tortoise pellets met the requirements of the animals completely. Because of the inadequate Ca:P ratio only one turtle pellet could be accepted. Accordingly, none of the commercial pellets can be recommended as main or only feed. Key words: nutrition; pellet; metabolic bone disease; chelonian VREDNOTENJE KOMERCIALNIH ŽELV IN KRME ZA ŽELVE Izvleček: Želve v ujetništvu je potrebno hraniti z naravno krmo, da dosežejo podobno stopnjo rasti kot živali v prosti reji. Na voljo je širok izbor komercialno pripravljene hrane za želve. Prednost hranjenja želv s komercialno hrano je priročnost, vendar podatki o prehranskih potrebah za posamezne vrste želv še niso na voljo. Namen te raziskave je bil analizirati in ovrednotiti komercialne pelete in krmo za želve. V trgovinah za živali smo od 6 podjetij kupili komercialne pelete (npeleti za vodne želve = 7, npeleti za kopenkse želve = 7) za mesojede vodne in rastlinojede kopenske želve ter drugo krmo za vodne želve (liofilizirano goveje srce, posušene vodne nevretenčarje in zamrznjene cele ribe). Zamrznjene cele ribe smo uporabili kot referenčno krmo za mesojede vodne želve. Določili smo kemično sestavo in vsebnost kalcija (Ca) ter fosforja (P). Za ničelno hipotezo smo uporabili T-test enega vzorca s podatki na etiketi in rezultate lastne paralelne analize za surove beljakovine (an gl. crude proteins, CP), ekstrakt etra (angl. ether extract, EE), surovo vlaknino (angl. crude fibre, CF), Ca in P. Oznake nekaterih peletov so bile pomanjkljive, saj so manjkali podatki o hranilnih vrednostih, Ca in P (npeleti za kopenske želve = 4 od 7, npeleti za vodne želve = 5 od 7). Podatki na etiketi so se bistveno razlikovali (p < 0,05) od rezultatov naše analize pri 13 od 14 vrst peletov. Nobeni peleti za kopenske želve niso v celoti izpolnjevali potreb živali. Zaradi neustreznega razmerja Ca : P smo kot ustrezno določili le eno izmed 7 vrst peletov za vodne želve, zaradi česar nobenih od komercialnih peletov nismo določili kot priporočljivih za glavno ali edino krmo za želve. Ključne besede: prehrana; peleti; presnovna bolezen kosti; želve
... A dietary associative effect can occur when one item of the diet affects, positively or negatively, the digestive efficiency of other nutrients (Bjorndal, 1991). This effect is more common in herbivorous and omnivorous species, and its occurrence may increase because of microbial fermentation (McWilliams, 2005). An adverse effect of dietary lignocellulose on organic matter digestibility was observed in Galapagos tortoises (Geochelone nigra) (Hatt et al., 2005); and a negative correlation has been described between the dietary cell wall content and dry matter digestibility in tortoise species, including adults of red-footed tortoises, as well as reptiles in general (Bjorndal, 1989;Barboza, 1995ab;Hatt et al., 2005;Franz et al., 2011a). ...
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.
... The sun also delivers light, including radiation in the infrared (IR) and ultraviolet (UV) spectrums. UV radiation between 290 and 315 nm (UV-B) is particularly important for reptiles because most species utilize these wavelengths to synthesize vitamin D3 which is essential for calcium metabolism (Klaphake, 2010;McWilliams, 2005). While reptiles were traditionally thought to use sunlight primarily for vision and thermoregulation, other factors such as their vitamin D3 status and the intensity of visible light also influence basking behavior (Carman, Ferguson, Gehrmann, Chen, & Holick, 2000;Ferguson et al., 2003;Hertz, Fleishman, & Armsby, 1994;Karsten, Ferguson, Chen, & Holick, 2009). ...
Many reptiles require ultraviolet-B radiation between 290 and 315 nm (UV-B) to synthesize vitamin D3 and process dietary calcium. In captivity, exposure to too little or too much UV-B can result in health problems such as metabolic bone disease. While it is recognized that UV-B is necessary to successfully maintain many reptiles in captivity, the actual levels of UV-B that species are exposed to in nature is poorly known. We measured the UV-B exposure of two species of chameleon (Calumma brevicorne and C. nasutum) in the field in Madagascar over a period of four months. We found that both species were exposed to less UV radiation than that which was available in full sun. Only on rare occasions were chameleons observed in areas with a UV Index (UVI) greater than 3.0, and the median UVI for both species was only 0.3. There was no daily temporal pattern in UV exposure for C. nasutum, but C. brevicorne was found in areas with lower UV levels in the late afternoon when compared to late morning. Additionally, C. nasutum males showed higher UV exposure than females in late morning. Our results suggest that both C. brevicorne and C. nasutum can be classified as Ferguson Zone 1 species, and should be provided with a UV-B gradient in captivity that offers access to UV-B radiation as well as adequate shaded refuge. K E Y W O R D S Calumma, captive husbandry, Ferguson Zone, reptile lighting, UV-Index
... However, most are opportunistic carnivores or omnivores, consuming invertebrates, small vertebrates, and aquatic vegetation (Bouchard and Bjorndal, 2006;Gibbons and Avery, 1990;Luiselli et al., 2011;Ottonello et al., 2005;Rhodin et al., 2008;Spencer et al., 1998). The wide spectrum of feeding strategies among freshwater turtles and their slow metabolism may explain their high tolerance for unbalanced diets in captivity, but their longevity and the energetic expense required for shell mineralization make them vulnerable to nutritional deficiencies in captivity (McWilliams, 2005). Moreover, the nutrient requirements for most species, especially those not routinely used in large-scale turtle farming, are poorly documented. ...
Freshwater turtles are commonly kept in captivity as pets, bred in zoos for conservation programs, and commercially farmed for pet markets and human consumption, but their nutrition can be challenging. However, based on practical experience, two main strategies may be identified: the use of non-calculated raw diets and the use of balanced commercial feeds. Raw diets are based on fresh, frozen and dried components including invertebrates, fish, rodents and plant matter; they imitate the variety of foods that are accessible to turtles in the wild and are considered most useful when turtles are bred for reintroduction into their natural habitat as part of conservation programs. Granulated, pelleted or extruded commercial diets are frequently used for farmed and pet turtles; they contain animal- and plant-based materials supplemented with vitamin and mineral premixes and calculated to reach the nutrient levels assumed to be optimal for most species. Until more species-specific information on the nutritional requirements of freshwater turtles is available, the Chinese softshell turtle (Pelodiscus sinensis), a commonly commercially farmed species for human consumption, may be used as a reference for other species in terms of suggested nutrients levels. Based on experimental data, the most important nutrients and their levels that should be included in turtle diets are crude protein (39.0 - 46.5%), crude fat (8.8%), Ca (5.7%), P (3.0%), methionine (1.03%), and cysteine (0.25%). The diet composition for freshwater turtles should be based on scientific knowledge and practical experience, so this paper aimed to present and discuss the available data on the nutrient requirements of turtles and the characteristics of the feed materials used in their nutrition.
... Indoor-housed mother-reared primate infants of any species are also at risk of developing deficiencies and rickets, as little vitamin D is transmitted in the milk to nursing infants. Basking reptiles, including iguanas and geckos, and chelonians may also be at risk for metabolic bone disease if not provided with adequate Ultraviolet A and Ultraviolet B light exposure (McWilliams, 2005). UV light has also been studied extensively in birds, where it may play an important role in sexual signaling, prey recognition, and navigation (Prescott et al., 2003;Rajchard, 2009). ...
The impact on welfare of the numerous characteristics of the living environment of a laboratory animal has received increasing attention in recent years. The standard research animal housing design of a box (the cage), within a bigger box (the animal room), within an even bigger box (the animal facility), has undergone transformation at many institutions, with the result that animals are often afforded more vertical space, access to the outdoors, windows to the outside, and many other design features (depending upon the species) that break from tradition. The living environment is typically considered to be comprised of physical, chemical, and biological factors that may have synergistic or competing effects on the welfare of an animal. Other less tangible aspects, such as enclosure space, social complexity, and the human factor play a critical role in laboratory animal welfare but pose special challenges to interpret their precise effects in the milieu of other environmental features. As efforts to optimize laboratory animal welfare through improved living environments, exemplified by the expanding emphasis on social housing and other forms of environmental enrichment, gain momentum in the industry, innovation and new technologies balanced with safety considerations for the animal and the personnel, animal management (e.g. animal observation, access to the animal), and the research objectives predominate. This chapter delineates key factors in the living environment that impact animal welfare with a view to highlighting areas that are well understood in terms of the impact on welfare and those that necessitate further research and more creativity.
Basking is an essential behavior for thermoregulation in turtles. Although basking is widely studied, this
behavior varies among populations, habitats, and microclimates. In this study, we evaluated the effectiveness of game
cameras for studying basking activity of Rio Grande Cooter (Pseudemys gorzugi), a New Mexico state-threatened
species. From August 2018 to July 2019, images were taken hourly from 07:00 to 19:00 at 3 locations along or near the
Black River, New Mexico. We used a generalized linear mixed-effect model to find associations between basking patterns
and environmental variables. The species was active year-round, with the greatest number of basking turtles in spring.
Basking activity was significantly correlated with water temperature, season, light intensity, difference between water and
air temperatures, and time of day. Game cameras were effective for long-term monitoring of turtles in this study. This
method was noninvasive and created low disturbances while providing high-resolution data. Overall, this study provides
a deeper understanding of the basking habits of P. gorzugi as well as its activity periods across seasons, which can also
aid in determining an appropriate time for conducting visual surveys of the species in southeastern New Mexico.
Reference intervals for blood biochemical analytes and packed cell volume are useful to veterinarians and conservation programs for monitoring the health of threatened species. Populations of the critically endangered Chinese three-striped box turtle, Cuora trifasciata (Bell, 1825), are heavily depleted in the wild because of overharvesting; and many individuals are now maintained in captive breeding programs. Reference intervals of biochemical analytes and packed cell volume were established for individuals of this species held in a captive breeding program at Kadoorie Farm and Botanic Garden, Hong Kong. Blood samples were obtained from 86 healthy individuals from a captive population during annual health examinations between 2006 and 2010. Packed cell volume and 17 biochemical analytes were measured, and data were analyzed using both multivariate and univariate statistical analyses. Significant differences in eight analytes between males and females were identified. Ten analytes were found to increase or decrease significantly with the body weight of the turtles. The reported plasma reference intervals, based on 2.5th and 97.5th percentiles, may serve as benchmarks for clinical assessment and conservation of this critically endangered species.
Juvenile snapping turtles may be highly susceptible to dehydration during over- land movement because of their aquatic nature and large surface area to volume ratio. The present study examined the influence of body size and relative humidity on rates of evaporative water loss and estimates of survival time. Larger hatchlings had higher rates of evaporative water loss but longer survival times resulting from their greater absolute water contents. Rates of evaporative water loss decreased, and estimated survival times increased with increasing relative humidity. The findings suggest that evaporative water loss may be an important factor influencing survivor- ship and behavior during overland movements of juvenile snapping turtles.
Three experimental manipulations were conducted to assess the influence of heat source selection and active thermoregulation on ultraviolet (UV) light exposure in captive spiny-tailed iguanas (Oplurus cuvieri) at the Jersey Wildlife Preservation Trust. Four replicates per manipulation were conducted on six individual lizards. All animals were tested in a separate enclosure to which they were acclimated before observations. Data on choice of thermal sources were collected during the first 2 hr of light, when lizards were actively thermoregulating. Animals were allowed to choose between incandescent light, UV light and a non-light heat source (thermotube) in different combinations. Recorded temperatures close to the incandescent light (37°C) were always significantly higher than at the thermotube (33°C) and at the UV light (29°C).
Manipulation 1 offered the animals a choice of an UV light and an incandescent light as thermal sources. Manipulation 2 presented animals with the thermal choices in Manipulation 1, but substrates under each source in Manipulation 1 were switched. In Manipulation 3, animals could choose between an incandescent light and the thermotube.
All studied lizards were significantly more attracted to the incandescent light than to the UV light or thermotube. Incandescent light elicited a significantly higher proportion of basking behaviors in all individuals than the other sources. A high proportion of time basking was also spent in front of the thermotube but fewer individuals and less time were spent basking under the UV light. Heat source selection was generally found to be independent of substrate. Management applications of this preference are suggested for juvenile diurnal heliothermic iguanids. Zoo Biol 16:391–401, 1997.
We studied movement patterns, activity, and home range of the eastern spiny softshell turtle (Apalone spinifera) in northern Lake Champlain (Quebec, Canada; Vermont) from 1996 to 1999. This turtle population is at the northern limit of its range and considered threatened. Of the 30 individuals captured and marked, 15 females and eight males were equipped with radio-transmitters and monitored from two weeks to 29 months. Mean annual home range size for females (32.06 km 2 ,N 11) was significantly larger than for males (2.75 km2 ,N 4). Home ranges generally consisted of a spring-summer concentration area (0.90 km2) and a fall-winter concentration area (1.80 km2), plus the area traversed between these concentration areas. In general, movements did not vary significantly from May to September, but turtles were less active after mid-September. Three hibernacula and three nesting sites were identified. Seventy five percent of the radio-tracked individuals were concentrated in a small area surrounding one hibernaculum from September to April. We hypothesize that habitat fragmentation, both natural and resulting from human activities, was in part responsible for the large home range and long movements observed. Results indicate that, to conserve this spiny softshell turtle population, the seasonal concentration areas need strict protection, although a lakewide approach promoting the preservation of natural habitats is also necessary.
Calcium (Ca) and phosphorus (P) are very important minerals in reptile nutrition, but many diets still are not balanced. To achieve optimal growth, including a healthy skeleton and a strong shell, a well-balanced supply with these minerals is prerequisite. The purpose of this study was to evaluate the digestibility of diets with different calcium levels, with special emphasis on the digestibility of minerals. Fourteen captive-born juvenile Galapagos giant tortoises of the Zurich and Rotterdam Zoos were used. The animals were housed indoors at a mean temperature of 23°C and 25°C, and at 65% and 60% humidity, respectively. The animals from the same zoo were fed the same diet, which consisted of vegetables, herbs, and a mixture of different Ca sources. Daily mixed fecal samples of all tortoises were collected from day 8 to day 18. A Weender analysis was performed and the HCl-insoluble ash was used as an indigestible indicator (marker) for the determination of the apparent digestibility. The Ca content of the mixed feedstuffs of diet I was 1.43% on a dry matter basis, and the Ca:P ratio in the food was 3.9:1. In diet II, the Ca content was 2.06% on a dry matter basis, and the Ca:P ratio in the food was 4.8:1. Diet III contained 7.33% of Ca on a dry matter basis, and the Ca:P ratio in the food was 6.7:1. The digestibility of Ca in diet I was 42%. The other examined minerals, Mg and P, had a digestibility of 54% and 84%, respectively. In diet II, the digestibility of Ca was 63%, of Mg 76%, and of P 88%, and in diet III the digestibility of Ca was 82%, of Mg 92%, and of P 91%. The results of this study indicated that higher Ca concentrations in the diet led to an increased apparent digestibility of Ca, Mg, and P. The influence of an increased fat and decreased fiber content in diet III concerning digestibility is discussed. Zoo Biol 20:367–374, 2001. © 2001 Wiley-Liss, Inc.
The pineal complex of reptiles is a morphologically and functionally con-nected set of organs that originates as an evagination of the roof of the dien-cephalon. It is formed by two structures: the pineal organ and the parietal eye. The pineal gland is present in Chelonia, Squamata and Rhynchocephalia, but not in Crocodilia. The parietal eye is present in some species of lizards (Squama-ta) and in the tuatara (Rhynchocephalia). Both the pineal gland and the parietal eye are photosensitive. In particular, the parietal eye is an highly organized pho-toreceptive structure, with a well-defined lens, cornea and retina. The most important (and studied) secretory product of this complex is the hormone melat-onin which is synthesized by both organs (pineal and parietal eye). The pineal organ is believed to be the neuroendocrine transducer of changes in photoperiod and environmental temperature and it has been demonstrated to have a func-tional role in many aspects of reptilian biology. Melatonin has an influence on the mechanisms controlling thermoregulation (behavioral and physiological), because its manipulation or removal may produce significant alterations of behavioral and physiological thermoregulatory parameters. The reptilian pineal complex may also possess self-sustained circadian oscillators which are involved in the circadian organization of these animals and in their reproduction. It is believed that many of the roles played by the pineal complex are mediated by the hormone melatonin, since exogenous administration of melatonin may affect the animal's physiology and/or behavior. The present paper will review the cur-rent knowledge about the neuroendocrinology and functional roles of the reptil-ian pineal complex.
Several species of freshwater turtles in the family Emydidae undergo an ontogenetic dietary shift; as juvenile turtles mature, they change from a primarily carnivorous to a primarily herbivorous diet. It has been hypothesized that this shift results from an unfavorable ratio of gut capacity to metabolic rate that prevents small reptiles from processing adequate volumes of plant material to meet their energetic demands. Effects of dietary dilution on intake were evaluated in two size classes of red-eared sliders (Trachemys scripta elegans) to test whether small reptiles have a lower capacity to compensate for low-quality diets through increased intake than do larger conspecifics. Artificial diets with an inert diluent were offered to two size classes of turtles, and mass-specific intakes of dry matter, energy, and nitrogen were calculated. Both small (28.7+/-4.9 g body mass, mean mass+/-SD) and large (1,230+/-94 g body mass) turtles compensated for dietary dilution and maintained constant energy and nitrogen intakes on diets with lower energy content than common aquatic plants. Thus, body size did not affect the ability to respond to nutritional dilution, which suggests that processing limitations imposed by small body size do not constrain juveniles from adopting an herbivorous diet.
We hypothesized the vitamin D-deficient green iguanas with depleted calcium stores would seek to augment calcium intake by self-selection of a high calcium source. Eight green iguanas were offered free-choice ground oystershell in addition to their regular diet. Of these, two had not been exposed to ultraviolet (UV-B) radiation for > 5 years and were demonstrated to be vitamin D-deficient by low circulating levels of the principal vitamin D metabolite, calcidiol (25-hydroxy-cholecalciferol). The six others had been exposed to a UV-B emitting bulb for the previous 3 years and had high circulating calcidiol levels. Average daily food intake (expressed as dry matter per kg body mass) did not differ between the Low-D and High-D iguanas. The daily oystershell intake of the Low-D iguanas (0.02–0.03 g/kg) was lower than that of the High-D iguanas (0.06–0.70 g/kg), leading to a significant difference in calcium intake. The failure of iguanas to increase calcium intake in response to vitamin D-deficiency was puzzling and suggests that vitamin D, as a steroid hormone, may play some role in the expression of calcium appetite. Zoo Biol 16:201–207, 1997. © 1997 Wiley-Liss, Inc.
We determined the effects of dietary protein and on growth rates, food consumption rates, digestion rates, and digestive efficiencies of juvenile slider turtles (Trachemys scripta). Results from this study provide a clearer understanding of how these environmental factors interact in influencing body sizes and growth rates of individuals in wild slider turtle populations. Changes in plastron length, carapace length, and body mass were significantly greater for T. scripta eating 25% and 40% crude protein diets than for those eating 10% crude protein. Those consuming 10% crude protein showed significant decreases in body mass and plastron length over a 13-wk period. Individuals at of 15°, 22°, 28°, or 34° C had food ingestion rates (kJ wk⁻¹) that increased markedly with an increase in . Increasing dietary crude protein concentration increased turtle ingestion rates and influenced the positive effect of . Increasing dietary crude protein concentration alone did not significantly affect turtle consumption rates but did significantly influence the positive effect of . Digestive efficiencies were very high (because of the pelleted diet). Those turtles that ate at 15° C had a digestive efciency of 99.5%, as compared with 98.3% at 22° C, 94.8% at 28° C, and 95.8% at 34° C. Dietary protein concentration did not influence the digestive efficiencies of T. scripta. These data suggest that dietary protein is an important nutritional component to the growth of juvenile slider turtles and that elevated thermal conditions, combined with a high dietary protein availability, may explain the very high growth rates of slider turtles in some wild populations.
We measured body temperatures of free-ranging Brisbane River Turtles, Emydura signata with radiotelemetry. These and other species of freshwater turtle are commonly observed "basking" on logs or other elevated sites, a behavior which is usually interpreted as thermoregulatory. However, body temperatures of eight E. signata monitored for more than 112 turtle days in winter, spring, and summer showed a striking thermoconformity with the water and provided no data showing that this species routinely elevates its body temperature above water temperature. The biological significance of basking is obscure in this population of E. signata, and the study highlights the need for direct measurements of body temperature in freeranging individuals of other freshwater turtle species.
Diet selection and optimization may be affected by nonadditive interactions (or associative effects) among ingested diet items. Associative effects occur when one diet item affects the digestion (either positively or negatively) of another diet item. Feeding trials were conducted with an opportunistic omnivore, the yellow-bellied slider turtle (Trachemys scripta scripta) on three diets: duckweed, insect larvae, and duckweed/larvae mix. Diet has a significant effect on digestibilities and intake, but not on transit time. There was a significant associative effect in the duckweed/larvae diet. For all diet components except lipids, the digestive efficiencies measured in the duckweed/larvae diet were significantly greater than those predicted from the digestive efficiencies for duckweed and larvae diets when fed alone. The presence of larvae in the digesta significantly improved the digestive processing of duckweed, probably by supporting greater numbers or diversity of cellulolytic microbes. A given mass of duckweed provided @?70% more energy and 20% more nitrogen to the turtle when ingested with insect larvae than when ingested alone. Associative effects should be incorporated in optimal foraging models and studies of diet selection because the value of a diet item can vary with the foods with which it is ingested. The assigned value must include not only the direct nutritional gain from the item, but also the indirect nutritional gain (or loss) through positive (or negative) effects on digestion of food items with which it is ingested.
The Florida red-bellied turtle, Pseudemys nelsoni, on a diet of the aquatic plant Hydrilla verticillata, has high digestive efficiencies for dry matter, organic matter, energy, and cell walls, and moderate digestive efficiency for nitrogen. High cell wall digestibilities are a result of microbial fermentation in both the small and large intestines. Digestibilities are higher than most values reported for herbivorous reptiles on foliage diets. Mass-specific intake falls within the range measured in freefeeding herbivorous reptiles. Fermentation in the small intestine has not been reported previously in reptiles. Endproducts of fermentation-volatile fatty acids (VFAs) and gases-and concentration and rate of production of VFAs are similar to those in other herbivores. Fermentation in the small intestine has important nutritional consequences, such as a competition between endogenous enzymes and gut microflora for the highly nutritious, soluble substrate in the digesta of the small intestine. Energy from VFAs produced by the microbial fermentation approximates the total daily energy gain to P. nelsoni on a hydrilla diet. One might havepredicted, based on the large ratio ofsmall intestine length to large intestine length, that P. nelsoni would not have relied on fermentation. The shift of fermentation into the small intestine demonstrates that, at least in P. nelsoni, digestive strategy is not constrained by gut morphology.
The O₂ consumption and CO₂ production of embryonic snapping turtles (Chelydra serpentina) were measured during incubation on substrates differing in water potential. Embryos incubated on a substrate with a water potential of-150 kPa (relatively wet) consumed more O₂ and produced more CO₂ than embryos incubated on a substrate with a water potential of-850 kPa (relatively dry). However, the greater metabolic rate of embryos incubated on the wet substrate was entirely due to their larger size and does not represent an intensification of their metabolism. Nor did embryos incubated on the wet substrate convert yolk more efficiently compared with those incubated on the dry substrate. Incubation on the wet substrate did, however, enable embryos to follow the same growth trajectory longer than did embryos incubated on the dry substrate.
Studies of digesta transit in the desert tortoise (Xerobates agassizii, formerly Gopherus agassizii) voluntarily eating a succulent diet (green, growing Erodium cicutarium, red-stemmed filaree) or a dry diet (dead Schismus barbatus, split grass), indicated that digesta flow was determined primarily by a gut-fill effect. Total food consumed between the times of marker ingestion and marker excretion remained constant for a given diet, regardless of feeding rate, and was related allometrically to body mass (exponent = 0.707). Higher feeding rates and their correspondingly shorter transit times occasioned lower digestibilities of dry matter, gross energy, and cell-wall components. The gastrointestinal tracts of tortoises eating green E. cicutarium contained nearly three times as much dry matter as when the tortoises were eating dry S. barbatus. This difference in gut fill may be related to the different physical (structural) properties of green and dry plantparts. Gravid females had a reduced gut fill, presumably because eggs in the oviduct reduce the potential gut volume. Unfortunately, insufficient data were obtained for gravid females (n = 3) to allow formulation of a predictive equation for food intake and transit time in females carrying eggs.
The occurrence of free and glycosidic vitamin D3 and its metabolises in Cestrum diurnum leaves was investigated. The chloroform extract of the leaves (containing free vitamin D3 and its metabolites) and the chloroform-methanol (1:2) extract (containing glycosidic vitamin D3 and its metabolites) of the residue after glycosidase treatment were partially purified by column chromatography. Fractions corresponding to authentic vitamin D3, 25-hydroxy vitamin D3 (25-OH-D3) and 1,25-dihydroxy vitamin D3 (1,25-(OH)2D3) were found to be biologically active. These fractions were also analysed and quantified by HPLC. This is the first demonstration of the presence of free vitamin D3, 25-OH-D3 and 1,25-(OH)2D3 in a carcinogenic plant. Apart from the free forms, the corresponding glycosidic metabolites were also found. The concentration of free metabolises was much higher than that of the glycosidic forms.
We hypothesized the vitamin D-deficient green iguanas with depleted calcium stores would seek to augment calcium intake by self-selection of a high calcium source. Eight green iguanas were offered free-choice ground oystershell in addition to their regular diet. Of these, two had not been exposed to ultraviolet (UV-B) radiation for > 5 years and were demonstrated to be vitamin D-deficient by low circulating levels of the principal vitamin D metabolite, calcidiol (25-hydroxy-cholecalciferol). The six others had been exposed to a UV-B emitting bulb for the previous 3 years and had high circulating calcidiol levels. Average daily food intake (expressed as dry matter per kg body mass) did not differ between the Low-D and High-D iguanas. The daily oystershell intake of the Low-D iguanas (0.02–0.03 g/kg) was lower than that of the High-D iguanas (0.06–0.70 g/kg), leading to a significant difference in calcium intake. The failure of iguanas to increase calcium intake in response to vitamin D-deficiency was puzzling and suggests that vitamin D, as a steroid hormone, may play some role in the expression of calcium appetite. Zoo Biol 16:201–207, 1997. © 1997 Wiley-Liss, Inc.
It has been speculated that pyramiding, a condition in which the scutes of the carapace become deformed and elevated, may be caused by an imbalance in dietary calcium (Ca) and/or phosphorus (P). This was tested by feeding 48 red-eared sliders (Trachemys scripta elegans), 12–14 weeks old, one of four diets for 150 days. The control diet was 67% krill and 33% flour (DM), providing 1.38% Ca and 1.03% P. The high Ca (2.24%) and high P (2.56%) diets were created by adding limestone or sodium phosphate, respectively, to the control diet. The fourth diet contained 2.95% Ca and 2.48% P, with a Ca:P ratio similar to the control diet. Turtles were maintained in groups of four in 12 10-gallon aquariums with incandescent heat lamps and full spectrum fluorescent lamps (n = 3 tanks/diet). The incidence of pyramiding, body weight, and carapace length were measured every 50 days. Pyramiding was not induced in any group during this study, with all turtles having shells of normal shape and appearance. At the beginning of the study, the turtles weighed 8.37 ± 1.50 g (mean ± SEM), with a carapace length of 35.08 ± 1.88 mm. Those receiving the control and high Ca/high P diets grew significantly faster in body weight than the turtles receiving the high Ca diet, with the turtles on the high P diet being intermediate (control: 10.83 ± 1.49a; high Ca: 5.82 ± .78b; high P: 7.77 ± 1.94a,b; high Ca/high P: 9.01 ± 1.88a g of gain; P = 0.013). The carapaces of turtles on the high Ca diet also grew significantly slower than those of all other groups (control: 9.87 ± 1.10a; high Ca: 5.18 ± .73b; high P: 8.22 ± 2.17a; high Ca/high P: 8.20 ± 1.07a mm of gain; P = 0.010). These data suggest that oversupplementation of calcium may be detrimental to growth performance in young turtles. Zoo Biol 17:17–24, 1998. © 1998 Wiley-Liss, Inc.
Leaves of Cestrum diurnum grown in Hyderabad, India were tested for vitamin D-like activity in vitamin D-deficient rat and chick and also in rachitic rat models. Vitamin D-dependent serum and bone parameters, and calcium transport by the gut which were altered in vitamin D-deficiency were restored to control levels (ie to the levels found in rats given vitamin D3 from weanling, 25 IU day−1) by incorporation of C diurnum leaf powder at a 2% level in the diet. Similarly, in rachitic rats, the extent of new bone calcification was significantly improved either by C diurnum leaf incorporation in the diet or by vitamin D3 administration. An approximate estimate of the vitamin D-like activity indicated that the plant had about 100000 IU cholecalciferol equivalents kg−1 dry leaf powder, which is three times higher than the values reported earlier. This may be because of long exposure to sunlight of the plants grown in this part of the world.
In laboratory tests, young Chelydra serpentina and Trachemys scripta altered their distribution in the presence of a temperature gradient, Selection of temperatures in the gradient for hatchlings and yearlings showed that body temperatures (T(b)s) of C. serpentina were lower than T. scripta,but the difference was insignificant. Relatively low TbS could allow greater activity range and reduced metabolic maintenance cost for C. serpentina, which seldom leaves water. Published by Elsevier Science Ltd.
The active vitamin D metabolite 1,25-dihydroxyvitamin D3 [1,25-D3] is thought to promote many of its actions through interaction with a specific intracellular receptor. The discovery of such receptors in monocytes and activated lymphocytes has led investigators to evaluate the role of the hormone on the immune system. The sterol inhibits lymphocyte proliferation and immunoglobulin production in a dose-dependent fashion. At a molecular level, 1,25-D3 inhibits the accumulation of mRNA for IL-2, IFN-γ, and GM-CSF. At a cellular level, the hormone interferes with T helper cell (Th) function, reducing Th-induction of immunoglobulin production by B cells and inhibiting the passive transfer of cellular immunity by Th-clones in vivo. The sterol promotes suppressor cell activity and inhibits the generation of cytotoxic and NK cells. Class II antigen expression on lymphocytes and monocytes is also affected by the hormone.When given in vivo, 1,25-D3 has been particularly effective in the prevention of autoimmune diseases such as experimental autoimmune encephalomyelitis and murine lupus but its efficacy has been limited by its hypercalcemic effect. Synthetic vitamin D3 analogues showing excellent 1,25-D3-receptor binding but less pronounced hypercalcemic effects in vivo have recently enhanced the immunosuppressive properties of the hormone in autoimmunity and transplantation.
Receptor autoradiography was used for the demonstration of specific binding of the tritiated steroid hormone 1,25-dihydroxyvitamin D3 in the eyes and associated tissues of Anolis carolinensis. A 100-fold excess of non-labelled 1,25-dihyroxyvitamin D3 abolished specific nuclear binding of tracer. Nuclear [3H]-1,25-dihydroxyvitamin D3 binding was present in all animals in the retina stratum ganglionare and stratum nucleare externum as well as in the cornea; however, binding was absent in the optic nerve, except in cells of the surrounding arachnoidea. Additional cranial tissues such as chondrocytes in the sclera, parasphenoid, skeletal muscle cells, and epithelial cells of the lacrimal and Harderian glands exhibited nuclear labelling. The results suggest that 1,25-dihydroxyvitamin D3 has genomic regulatory actions that involve cell proliferation, differentiation, and functions of certain cells of the eye and associated cranial tissues. The presence of vitamin D receptors in tissues of the eye and skeletal muscle in the reptile is in part different from that observed in mammals. In general, receptors for vitamin D and related target tissues appear to be even more extensive in lizards than has been observed in rodents, which may reflect a more extensive dependency of these tissues on solar environment and active seasonal and circadian regulation.
We described the diet of Emydura macquarii, an omnivorous turtle from south-eastern Australia, compared its digestive performance on diets of fish or plants at two temperatures, and related how both diet and temperature affect its food selection in nature. Filamentous algae constituted 61% of the stomach content of E. macquarii. The turtles rarely fed on motile prey, but selected carrion from the lagoon bottom and terrestrial insects (Diptera, Hymenoptera and Coleoptera) trapped on the surface of the water. Digestive efficiency of E. macquarii was affected little by body temperature, in contrast to consumption rates and rates of passage which were strongly influenced by both temperature and diet. In combination, these responses resulted in a slower rate of digestion at 20°C than at 30°C. Digestive efficiency of E. macquarii on a herbivorous diet at 30°C (49%) was about half that of turtles on a carnivorous diet (91%), but they had longer transit times (118 h on the plant diet versus 70 h). Lower consumption rates and longer mean retention times in turtles fed plants compared those fed fish relate to slower digestive processing of the plant. Rapid processing and higher consumption rates of fish by E. macquarii resulted in higher energy gains compared to turtles consuming plants (almost 100 times more energy at 30°C). The laboratory results suggest that fish carrion and aquatic and terrestrial invertebrates are probably essential dietary items of E. macquarii in the wild, because its metabolic requirements cannot be met from aquatic macrophytes alone.
Ultraviolet-A radiation (320-400 nm) is scattered rapidly in water. Despite this fact, UV is present in biologically useful amounts to at least 100 m deep in clear aquatic environments. Discovery of UV visual pigments with peak absorption at around 360 nm in teleost cone photoreceptors indicates that many teleost fishes may be adapted for vision in the UV range. Considering the characteristic absorption curve for visual pigments, about 18% of the downwelling light that illuminates objects at 30-m depth would be available to W-sensitive cones. Strong scattering of UV radiation should produce unique imaging conditions as a very bright UV background in the horizontal view and a marked veiling effect that, with distance, obscures an image. Many teleosts have three, or even four, classes of cone cells mediating colour vision in their retina and one can be sensitive to UV. These UV-sensitive cones contain a visual pigment based on a unique opsin which is highly conserved between fish species. Several powerful methods exist for demonstration of UV vision, but all are rather demanding in terms of technique and equipment. Demonstration that the eye lacks W-blocking compounds that are present in many fish eyes is a simpler method that can indicate the possibility of UV vision. The only experimental evidence for the use of UV vision by fishes is connected to planktivory: detection of UV-opaque objects at close range against a bright UV background is enhanced by the physical properties of UV light. Once present, perhaps for the function of detecting food, UV vision may well be co-opted through natural selection for other functions. Recent discovery that UV vision is critically important for mate choice in some birds and lizards is a strong object lesson for fish ecologists and behaviourists. Other possible functions amount to far more than merely adding a fourth dimension to the visible spectrum. Since UV is scattered so effectively in water, it may be useful for social signalling at short range and reduce the possibility of detection by other, illegitimate, receivers. Since humans are blind to UV light, we may be significantly in error, in many cases, in our attempts to understand and evaluate Visual aspects of fish behaviour. A survey of the reflectance properties of skin pigments in fishes reveals a rich array of pigments with reflectance peaks in the UV. For example, the same yellow to our eyes may comprise two perceptually different colours to fish, yellow and UV-yellow. It is clearly necessary for us to anticipate that many fishes may have some form of UV vision. (C) 1999 The Fisheries Society of the British Isles.
Thesis (M.A.)--State University of New York, College at Buffalo, 1988. Includes bibliographical references (leaves 48-58).
The exchange of water between a chelonian egg and its subterranean environment is influenced by numerous factors, the most important of which are (1) structure of the calcareous layer of the eggshell, (2) water potential and temperature in the nest, and (3) fraction of the eggshell that actually contacts soil in the nest cavity. Eggs with relatively porous shells tend to absorb large quantities of water from cool, moist environments and to lose large amounts of water to warm, dry ones. Net water-exchange by such eggs also tends to be more favorable (= positive) when soil contacts the entire eggshell than when a large fraction of the shell is exposed to air trapped inside the nest cavity. In contrast, eggs with relatively impermeable shells usually exchange only small amounts of water with their environment, regardless of the physical conditions that prevail inside the nest. The pattern of net water-exchange, together with size (and water content) of the freshly laid egg, determines the amount of water that is available to sustain the embryo. An embryo having access to a relatively large reserve of water will consume more of its yolk and grow to larger size before hatching than will an embryo having access to a smaller reserve of water. Large, well-hydrated hatchlings may survive better than small, dehydrated animals during the trek overland from nest to water. If so, a cooler, wetter nest will also be a better nest.
The photoproduction of vitamin D in the skin was essential for the evolutionary development of terrestrial vertebrates. During exposure to sunlight, previtamin D3 formed in the skin is isomerized to vitamin D3 (calciol) by a temperature-dependent process. Since early land vertebrates were poikilothermic, the relatively slow conversion of previtamin D3 to vitamin D3 at ambient temperature put them at serious risk for developing vitamin D deficiency, thus leading to a poorly mineralized skeleton that could have ultimately halted further evolutionary development of vertebrates on land. We evaluated the rate of isomerization of previtamin D3 to vitamin D3 in the skin of iguanas and found the isomerization rate was enhanced by 1100% and 1700% at 25 degrees C and 5 degrees C, respectively. It is likely that the membrane entrapment of previtamin D3 in its s-cis,s-cis conformation is responsible for the markedly enhanced conversion of previtamin D3 to vitamin D3. The membrane-enhanced production of vitamin D3 ensures the critical supply of vitamin D3 to poikilothermic animals such as iguanas.
The effect of exposure of bacterial suspensions to UV radiation by means of the dose-response curves was assessed. The D37 and D10 values were used for subsequent statistical analysis of the results. The aim of this article is to evaluate the sensitivity to UV radiation of several microorganisms of different habitats (Rhizobium meliloti, Rhodobacter sphaeroides, Escherichia coli, and Deinococcus radiodurans), two mutants with nonfunctional SOS DNA repair system (R.meliloti recA
- and E. coli recA
-), and a mutant in the synthesis of carotenoids (R. sphaeroides crtD). The results reveal that D. radiodurans was an extremely resistant bacterium, R. meliloti was more resistant than R. sphaeroides, and E. coli was the most sensitive bacterium tested. The high sensitivity of recA
- mutants was also verify. Moreover, it seems that the possession of pigments had no important effect in the sensitivity of R. sphaeroides to UV radiation.
Structural homology between the high-affinity thyroxine (T4)-binding protein (TBP) in the plasma of the turtle, Trachemys scripta, and vitamin D-binding proteins (DBP) of mammals prompted an investigation of plasma vitamin D binding in the turtle. Several lines of evidence indicate that the TBP represents the primary binding protein for 25-OH-cholecalciferol (D3) in the turtle plasma. D3-binding protein in whole plasma migrates in the same position as TBP by size-exclusion chromatography and polyacrylamide gel electrophoresis; it is electrophoretically distinct from sex hormone-binding proteins. D3 binding to purified TBP alone is enhanced (up to sevenfold) in the presence of plasma proteins, including albumin; with this correction, the D3-binding activity of plasma corresponds to expected TBP titers. Plasma selectively stripped of TBP by affinity chromatography and purified turtle albumin have only trace D3-binding activity. Variations in physiological state (thyroidal status, age, and sex) previously associated with variable T4 binding (and TBP levels) in T. scripta show correlated variability in plasma D3 binding. D3 binding is also highly correlated with T4 binding (r = 0.81; P < 0.001) for plasma samples taken from 30 adults representing 10 different species of Trachemys. D3 binding in plasma exhibits a high-affinity site (Ka = 2.3 x 10(8) M-1) and a second lower-affinity (Ka = 2 x 10(6) M-1), higher-capacity site; capacities are highly variable. Purified TBP has a comparable high affinity (Ka = 2.8 x 10(8) M-1), with a capacity close to 1 mol/mol. Binding of T4 and D3 are not competitive, indicating separate binding sites for the two ligands; in fact, T4 tends to enhance the affinity and the capacity for D3. A single protein in turtle plasma ("TBP/DBP") functions in the transport of two different hormones normally served by two distinct binding proteins (representing different multigene families) in mammals. These results have implications for the mediation of T4 effects on growth.
Ten clinically healthy green iguanas (Iguana iguana) imported from South America were examined, and haematological and biochemical measurements were made on samples of blood. This paper describes the methods of blood sampling, handling and laboratory analysis, and presents the results as a set of normal blood ranges for the green iguana.
Vitamin D binding protein (DBP) was isolated from the plasma of the snapping turtle, Chelydra serpentina (mixed sex adult), and compared with the previously characterized dual function binding plasma protein that binds both thyroxine (T4) and vitamin D (tsTDBP) in an emydid turtle, Trachemys scripta. Purification of Chelydra serpentina DBP (csDBP) was accomplished by ion exchange chromatography, preparative polyacrylamide gel electrophoresis, and reverse-phase high-performance liquid chromatography. Estimates of increased purification (ca. 71-fold), recovery (ca. 1.5%), and corresponding plasma concentration (ca. 0.6 mg/ml) are confounded by interference with other proteins. A protein was identified that showed the same high affinity for 25-OH-cholecalciferol (vitamin D3) as the tsTDBP, and the two exhibited similar heat resistances in binding. The csDBP and tsTDBP had similar molecular weights by SDS-PAGE (ca. 58 kDa), showed immunological cross reactivity, and differed by only three residues, representing conservative substitutions, in the 30 NH2-terminal amino acid sequence. A slightly lesser homology (up to 89% similarity based on conservative substitutions) was seen with three mammalian DBPs. However, unlike tsTDBP, the DBP from the snapper did not bind T4. These data support the view that the DBP of emydid turtles secondarily evolved a second T4 binding site, and this is probably independent of the D3 binding domain.
Individual variation in physiological traits may have important consequences for offspring survivorship and adult fitness. Variance in offspring phenotypes is due to interindividual differences in genotype, environment, and/or maternal effects. This study examined the contributions of incubation environment, maternal effects, and clutch identity to individual variation in metabolic rates in the common snapping turtle, Chelydra serpentina. We measured standard metabolic rate, as determined by oxygen consumption, for 246 individuals representing 24 clutches at 15 degrees and 25 degrees C, and we measured standard metabolic rates additionally for 34 individuals at 20 degrees and 30 degrees C. Standard metabolic rate for 34 snapping turtles measured at 15 degrees, 20 degrees, 25 degrees, and 30 degrees C increased with increasing temperature. Mean standard metabolic rate for 246 individuals was 0.247 microL O(2) min(-1) g(-1) at 15 degrees C and 0.919 microL O(2) min(-1) g(-1) at 25 degrees C. At 15 degrees C, mass at hatching, individual mass, and egg mass had no significant effects on metabolic rate, but at 25 degrees C, mass at hatching, individual mass, and egg mass did have significant effects on metabolic rate. Incubation temperature had no significant effect on metabolic rate at 15 degrees, but it did have a significant effect at 25 degrees C. Clutch identity had a significant effect on metabolic rate at both 15 degrees and 25 degrees C. Interindividual variation in standard metabolic rate due to incubation temperature, and especially clutch identity, could have large effects on energy budgets. Results suggest that there were both environmental and genetic effects on standard metabolic rate.
We tested two hypotheses: first, that the inferior anoxia tolerance of the softshell turtle, Apalone spinifera, compared to the western painted turtle, Chrysemys picta bellii, is related to its less mineralized shell, and second, that turtle bone, like its shell, stores lactate during prolonged anoxia. Lactate concentrations of blood, hindlimb bone, and shell were measured on normoxic Apalone and Chrysemys and after anoxic submergence at 10 degrees C for 2 and 9 d, respectively. Blood and shell concentrations of Ca(2+), Mg(2+), Na(+), K(+), and inorganic phosphate (P(i); for shell only) were also measured. Because a preliminary study indicated lactate distribution in Chrysemys throughout its skeleton during anoxia at 20 degrees C, we used hindlimb bones as representative skeletal samples. Apalone shell, though a similar percentage of body mass as Chrysemys shell, had higher water content (76.9% vs. 27.9%) and only 20%-25% as much Ca(2+), Mg(2+), CO(2), and P(i). When incubated at constant pH of 6.0 or 6.5, Apalone shell powder released only 25% as much buffer per gram wet weight as Chrysemys shell. In addition, plasma [Ca(2+)] and [Mg(2+)] increased less in Apalone during anoxia at an equivalent plasma lactate concentration. Lactate concentrations increased in the shell and skeletal bone in both species. Despite less mineralization, Apalone shell took up lactate comparably to Chrysemys. In conclusion, a weaker compensatory response to lactic acidosis in Apalone correlates with lower shell mineralization and buffer release and may partially account for the poorer anoxia tolerance of this species.
We dissected hearts from near-term embryos and hatchlings of common snapping turtles (Chelydridae: Chelydra serpentina) whose eggs had incubated on wet or dry substrates, and then dried and individually weighed the heart and yolk-free carcass from each animal. Hearts and carcasses of prenatal and neonatal animals grew at different rates, and the patterns of growth by both heart and carcass differed between wet and dry environments. Hearts grew faster, both in actual mass and in mass adjusted for variation in body size, in embryos and hatchlings whose eggs were incubated on dry substrates than in animals whose eggs were held on wet media. This finding is consistent with a hypothesis that embryos incubating in dry settings experience hypovolemia secondary to dehydration and that enlargement of the heart compensates, in part, for the associated increase in viscosity of the blood. Embryonic turtles seemingly exhibit the same plasticity and response that would be expected from other vertebrate ectotherms subjected to the physiological challenges associated with desiccation and an associated reduction in blood volume.
Evaluation of vitamin D concentrations in Uro-mastyx spp. with and without radiographic evidence of dystrophic mineralization
- B L Raphael
- S B James
- R A Cook
Raphael, B. L., James, S. B. & Cook, R. A. (1999): Evaluation of vitamin D concentrations in Uro-mastyx spp. with and without radiographic evidence of dystrophic mineralization. Proceedings of the American Association of Zoo Veterinarians 1999: 20–23
The pineal complex of reptiles: physiological andbehavioral Ecology and Evolution 9: 313–333. roles The common diseases of captive reptiles: their symptoms, treatment, and prevention
- G Tosini
- J O Truitt
Tosini, G. (1997): The pineal complex of reptiles: physiological andbehavioral Ecology and Evolution 9: 313–333. roles. Ethology, Truitt, J. O. (1962): The common diseases of captive reptiles: their symptoms, treatment, and prevention. Coral Gables, FL: privately published
Metabolic bone disease
- Dc Washington
- Smithsonian Institution
- T H Boyer
Washington, DC: Smithsonian Institution. Boyer, T. H. (1996): Metabolic bone disease. In Reptile medicine and surgery: 385–392.
Reptile lighting: a current perspective
- Gehrmann
Gehrmann, W. H. (1996): Reptile lighting: a current perspective. Vivarium 8: 44–45.
Nutrient composition of whole prey commonly fed to reptiles and amphibians
- Dierenfeld
Dierenfeld, E. S. & Barker, D. (1995): Nutrient composition of whole prey commonly fed to reptiles and amphibians. Proceedings of the Association of Reptilian and Amphibian Veterinarians 1995: 3–15.
Food preferences, feeding practices and nutritional problems of captive reptiles
- Kollias
Kollias, G. V. & Gentz, E. J. (1996): Food pref-erences, feeding practices and nutritional problems of captive reptiles. Proceedings of the Association of Amphibian and Reptilian Veterinarians 1996: 107–110.
An illuminating discussion of vitamin D, ultraviolet radiation and reptiles
- Bernard
Bernard, J. B. & Ullrey, D. E. (1995): An illumi-nating discussion of vitamin D, ultraviolet radiation and reptiles. Proceedings of the Association of Rep-tilian and Amphibian Veterinarians 1995: 40–42.
Head starting Blanding's tur-tles (Emydoidea blandingii): a strategy for enhance-ment of a fragmented population
- G V Kollias
- M M Zgola
- T K Weinkle
- A B Breisch
Kollias, G. V., Zgola, M. M., Weinkle, T. K. & Breisch, A. B. (1997): Head starting Blanding's tur-tles (Emydoidea blandingii): a strategy for enhance-ment of a fragmented population. Proceedings of the American Association of Zoo Veterinarians 1997: 306–307.
Turtles, tor-toises and terrapins
- D R Mader
Mader, D. R. (Ed.). Philadelphia, PA: W. B. Saunders Co. Boyer, H. B. & Boyer, D. M. (1996): Turtles, tor-toises and terrapins. In Reptile medicine and surgery: 61–78.
Clinical nutrition of reptiles and amphibians
- Donoghue
Donoghue, S. (1995): Clinical nutrition of reptiles and amphibians. Proceedings of the Association of Reptilian and Amphibian Veterinarians 1995: 16–37.
© The Zoological Society of London Analysis of the maintenance diet offered to lories and lorikeets (Psittaciformes; Loriinae)
Int. Zoo Yb. (2005) 39: 85–98
© The Zoological Society of London
Analysis of the maintenance diet offered to lories and
lorikeets
(Psittaciformes; Loriinae)
Evaluation of vitamin D concentrations in Uromastyx spp. with and without radiographic evidence of dystrophic mineralization Diseases of reptiles Visceral gout in birds and reptiles
- B L Raphael
- S B James
- R A Cook
- H Reichenbach-Klinke
- E K A Elkan
Raphael, B. L., James, S. B. & Cook, R. A. (1999):
Evaluation of vitamin D concentrations in Uromastyx spp. with and without radiographic evidence
of dystrophic mineralization. Proceedings of the
American Association of Zoo Veterinarians 1999:
20–23.
Reichenbach-Klinke, H. & Elkan, E. (1965):
Diseases of reptiles. Hong Kong: TFH Publications.
Slifka, K. A. (1997): Visceral gout in birds and reptiles. In Proceedings of the ninth Dr. Scholl conference
on the nutrition of captive wild animals: 134–139.
Spain and 3 Rainforest Clinic for Birds
- Loro Researcher
- Parque
Researcher, Loro Parque Fundación, Tenerife, Spain and 3 Rainforest Clinic for Birds,
PO Box 508, Loxahatchee, Florida 33470, USA