THE STRUCTURE OF THE DIGESTIVE SYSTEMS IN FEEDING OF MAMMALS:Reinhold R. Hofmann, Prof. Dr. 1
1 Institute for Zoo Biology and Wildlife Research, P.O. Box, 10315 Berlin, Germany
Phylogenetic development and structural adaptations determine optimal utilisation of species or type specific feeds and of feeding intervals. This basic rule is frequently ignored in zoo nutrition. Economy-based compromises must approach natural conditions again and even consider complex processes of adaptation to plant defence systems and seasonal adaptations/restructuring of the digestive tract. The relatively simply structured and short carnivore system is robust in comparison to herbivore systems. Hindgut fermentation systems show great phylogenetic diversity (rodents, lagomorphs, hyraxes, perissodactyls, proboscid etc.) but less adaptive plasticity than foregut fermenters (kangaroos, camelids, tragulids, ruminants). In zoo nutrition underrated and poorly understood is the complex system of salivary glands, which appear to display their multiple function cascades in species browsing on chemically protected ("antinutritiva") plants, not, however, on prefabricated feeds. Similarly, the evolutionary differentiation and co-evolution of ruminants and their main forage plants, as expressed in morphophysiological variations of several portions of their digestive system, is apparently evened out by standardised feeds with negative long-term results. The importance of selectivity, seasonal adaptations and limited capabilities to digest cellulose for most larger herbivores (> 3 kg, > 100 kg BW) is emphasised. Metabolic adjustments to photoperiodically induced availability and digestibility of forage plants, regression and atrophy of absorptive structures, cyclic restructuring and hypertrophic response to abundance of freely chosen (selected) nutrients can hardly be simulated under zoo regimes. They must, however, be taken into consideration in order to prevent long-term maladaptation (especially of selective ruminants), breakdown and irreversible destruction of macro and microstructures of the digestive system, which is originally "designed" for alternating physiological options (e. g. bypass of soluble nutrients). The widely observed fallacy of generalisations e. g. ignoring feeding type in favour of body mass only which, in turn, is transformed into grossly standardised, prefabricated feeds has been documented frequently as an uncontrolled development from initially compromising nutritional physiology to finally irreversible and fatal pathological processes. There is sufficient structural evidence that zoo nutrition, by necessity artificial, is a troublesome however rewarding biological art, but can also easily be harmful to captive animals and thus ethically doubtful.
MINERAL STATUS OF RUMINANTSW. Arnhold Dr. 1, M. Anke1, M. Edwards2, and G. Nötzold3
1 Friedrich Schiller University, Biological-Pharmaceutic Faculty, Institute for Nutrition and Environment, Dornburgerstrasse 23, 07743 Jena, Germany, 2 Zoological Society of San Diego, P.O. Box 551, San Diego CA 92112-0551, USA, 3 Zoological Garden Leipzig, Pfaffendorferstrasse 29, 04105 Leipzig, Germany
The breeding of rare animals is one of the main goals of zoos. Nutrition is an important component of captive reproduction programs. The assessment of the nutritional and especially of the mineral status of different species of ruminants depends on the knowledge of their normal status. Using the values of mineral concentration in organs which are regarded as the limit values for a sufficient mineral supply in cows and sheep may result in overestimating the incidence of mineral deficiency in wild ruminants. Due to the fact that mineral status is species-specific, organ tissues and hair of different species of ruminants were analyzed and compared with domestic ruminants. Tissues from the liver, kidney, cerebrum, rib, skeletal muscle, heart, lung, aorta, spleen, pancreas, and hair were obtained from ruminants, that were kept in captivity. The animals came from the Zoological Society of San Diego, from the Leipzig Zoo, and from the Zoo Delitzsch, Germany. For comparison, organ tissues from wild living and domestic ruminants were obtained from different locations of Eastern Germany and Northern California. After dry ashing of samples the Ca, Mg, Fe, Zn, Cu, Mn, and Mo concentration were analysed by atomic absorption spectroscopy (Jarrell Ash 850) or optical emission spectroscopy with inductively coupled plasma (Spectroflame D, Spectro Analytical Instrument). The mineral status of different ruminants depends on species, age and mineral intake. The results are discussed, and the mineral values limit for a sufficient supply are given in species of wild ruminants.
COMPARATIVE ANATOMY AND ECOLOGY OF PREGNANCY AND LACTATION INAlastair A. Macdonald BSc, PhD, Dr. M.B.A.1
1 Preclinical Veterinary Sciences, The University of Edinburgh, Summerhall, Edinburgh EH9 1QH,
Scotland, United Kingdom
The nutritional requirements of animals during pregnancy and lactation differ from the requirements of the growing animal, or the non-pregnant adult, as revealed by studies of non-domesticated species. However, relatively little information has been published to indicate the comparable requirements for pregnancy and lactation of most animals in the wild. Similarly, there is surprisingly little information available from the study of animals in zoological collections. Analyses of comparative anatomical and physiological data can contribute to our understanding of the problem. Similarly, behavioural and other data may help to indicate some aspects of the relationship between the pregnant or lactating animal and its environment. As with many other widespread groups of animals, the nature of the relationships which exist between the various Eurasian, African and Southeast Asian wild pig species and their respective environments during pregnancy and lactation has not attracted specific research attention. This review will firstly seek to gather together what is available, and, on the basis of analyses of this, to seek to establish an investigative framework within which future studies may be undertaken. The anatomical and physiological changes, which occur in different parts of the body of the sow during pregnancy and lactation, will be described for the different species of pig, and related changes in her behaviour and feeding patterns reviewed. The other participants in these developments, the fetal and neonatal piglets, will also be presented for investigation. The nature of their nutritional requirements for growth and development will be analysed. Where data permit, suggestions will be made with respect to conservation management during the pregnancy and lactation of these species.
STRUCTURAL FLEXIBILITY OF THE INTESTINE OF BURMESE PYTHON (PythonJ. Matthias Starck PD Dr.1
1 Institute of Systematic Zoology and Evolutionary Biology, Friedrich-Schiller-Universität,Erbertstraße 1, D-07743 Jena, Germany
Introduction: Burmese pythons have amazing guts. They consume large meals (up to 100% body mass) after long periods of fasting and adjust the structural and functional parameters of their gut to the actual needs. Within a short time after feeding, they build up an effective and active resorption organ. When the meal is digested the intestine is reduced again to resting state. The adjustment of structure and function of the intestine is rapid, reversible, and is repeated after each meal. Previous studies have shown that the resorptive capacity for various nutrients is upregulated briefly after feeding (Secor and Diamond 1994; Am J Physiol 266:G695-705; Secor and Diamond 1997 Physiol Zool 70: 202-212), and that dramatic structural changes occur after feeding (Starck and Burann, Zoology 101 Supplement 1: 41; Starck and Burann 1998: Zoology 101, in press). Within two days after feeding, size of the intestinal mucose increases to more than 300% of the resting stage. Immunhistological and morphometric data are presented, that study the cytological mechanism of observed organ size changes. Methods: Six young Burmese Pythons (Python molurus) were purchased from a commercial reptile farm. The animals were kept at 27°C and 50% humidity. Animals were fed live mice every in intervals of 6 weeks. Effects of feeding on intestinal morphology were studied by transcutaneous ultrasonography. For the comparison of effects of feeding on epithelial morphometry, and cellstructure, 3 fed animals were compared to 3 fasting animals. Animals ere sacrificed by an overdosis pentobarbital, and tissues were immidiately preserved in 5% paraformaldehyde in 0.1m phosphatebuffer for processing for lightmicroscopy and 2.5% lutardialdehyde for eletronmicroscopy, respectively. Results: Transcutaneous ultrasonography revealed a significant increase of the size of the small intestine and the liver. The size increase reached a maximum within two to three days after feeding. An significant increase of the thickness of the muscle layer could not be detected by ultrasonography, however, morphometry using histological sections revealed a strong increase in muscle layer too. Epithelial morphometry (i.e., size of the resorption surface), enterocyte cell size, and the number of mitochondria increase within two days after feeding to levels highly significant above resting stage. Enterycyte brush border length (microvilli length) and membrane bound alcaline phosphatase activity also increase within short time ofter feeding. Ongoing studies investigate changes of cell proliferation rates in the mucosal crypts and changes of rates of apoptosis at the tip of the villi as mechanisms that support structural flexibility. Discussion: Responses of the python's intestine reveal a high structural flexibility that allows the structure and function of the intestine to adjust to the actual needs. Preliminary data show that differential changes of cell proliferation activity drives the up- and down regulation of organ size. Supported by the German Research Foundation (DFG # STA 345/2/2 and STA 345/5-1).
EXAMINATION OF THE DIGESTIBILITY OF CALCIUM, MAGNESIUM, ANDAnette Liesegang Dr. 1, Jean-Michel Hatt Dr.MSc2, Rhea Forrer3, Marcel Wanner Prof. Dr.1 and Ewald Isenbügel Prof. Dr.2
1 Institute of Animal Nutrition,
2 Division of Zoo Animals and Exotic Pets
3 Department of Laboratory Medicine of the Veterinary Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland
The growth of animals is characterised by high variability and depends largely on food, climate, and environmental conditions. Many diets of zoo animals are low in calcium or have a poor calcium:phosphorus ratio. To achieve an optimal growth, including a healthy skeleton and a powerful shield, a well-balanced supply with calcium and phosphorus is important. The knowledge of the digestibility of the minerals is the basis for a correct supplementation. Four captive born Galapagos giant tortoises (2 x 1995 / 2 x 1996) of Zurich Zoo were used. The animals had an average weight of 2123 g. They were housed inside at a mean temperature of 23°C, at 65 % humidity, and were exposed to a 12h light:12 h dark day including exposition to UV light. To get an idea of the transit time of digesta, carmin red (approximately 66 mg per kg BW) was given into the food once. After transit time was estimated (8-18 days), the animals were fed the same diet, which consisted of vegetables, herbs, and a mixture of different Ca sources (commercially available lime mixture, cuttle bones, egg shells, shell lime). Daily mixed faeces 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 endogen indicator for the determination of the digestibility. The energy content of the mixed feedstuffs was 15.23 MJ/kg dry matter, the crude fibre content was 131 g/kg dry matter, and the protein content was 194 g/kg dry matter. The Ca content of the above described feedstuffs was 5.72 % dry matter and the Ca:P ratio was 14:1. The digestibility of Ca was 61 % ±0.7 (SE). The two other examined minerals, Mg and P, had a digestibility of 62 % and 79 %, respectively. Other previous studies described, that Ca and P play an important role in the nutrition of reptiles, especially tortoises. During growth, it is even more important to have enough Ca. From these results, the digestibility of Ca, Mg, and P was very good in comparison with other animals.
WHAT CAN THE NUTRITIONIST DO WITH THE RESULTS FROM THEGerry M. Dorrestein DVM PhD1
1 Department of Veterinary Pathology, Utrecht University, Yalelaan 1, 3584 Cl Utrecht, The Netherlands
There is abundant evidence that diet and health are intimately connected (Ullrey and Allen, 1993). A disease may be a primary consequence of nutritient deficiencies or excesses, or it may be complicated by opportunistic microbial invaders that take advantage of the hosts decreased resistance. Disease in many cases will lead to mortality, all animals will die. It is an essential part of zoo management to have a necropsy done on every animal that dies.The main reason is obvious. Zoo management, including the veterinarian, need to know why the animal died. There is, however, much more information to be collected from a dead animal. Every death animal is a sample from a collection and will provide information about the quality of preventive medicine (e.g. parasites), about the presence of carrier status of certain infectious diseases (e.g. mycobacteriose, salmonellose, campylobacteriose, chlamydiose), but also about possible nutritional problems (e.g. hypovitaminosis A, D3, E; hypervitaminosis A, D3 or Se, Ca deficiency, iron/copper storage, arteriosclerosis, fatty liver). All these nutritional problems lead to pathological changes of tissues recognisable by the pathologist. The result of these findings will be that the nutritionist will check the diet or to confirm such a diagnosis an analysis of organs can be performed. However, not always are nutritional problems directly reflected in pathological changes. Certain postmortem findings (e.g. chronic aspergillosis, candidiasis) are often correlated to a chronically deficient diet resulting in an impaired immune system. It is even more difficult when a specific disease patterns, all including wasting, are initiated by an inadequate diet, or related to insufficient energy or inadequate protein intake. It is easier when an animal keeps eating till it dies than when an animal stops eating and dies subsequently. We have seen actually animals dying of starvation, because it was not obvious which shift of keepers was supposed to feed the animals! In the presentation, examples will be shown to explain the different types of information the nutrionist can read from necropsy reports. These examples will be illustrated with some typical cases as regularly seen in our necropsy room.
IRON IN THE LIVER OF ANIMALS IN THE ZOO; A PATHOLOGISTS POINT OF VIEWGerry M. Dorrestein DVM, PhD1, Lilian de Sa DVM1, and Sandra Ratiarison1
1 Department of Veterinary Pathology, Utrecht University, Yalelaan 1, 3584 Cl Utrecht, The Netherlands
The demonstration of iron in organs, especially liver and spleen, is a common finding in the histological evaluation of (zoo) animals. Iron is easy to demonstrate with the Prussian blue stain. There is also an abundance of reference literature about the possible causes and meaning of iron storage (hemosiderosis and hemochromatosis), especially in mynahs, starlings, toucans and birds of paradise. In combination with additional information like animals species, diet and disease history the pathologist can say much more on the meaning of these findings. Also the location of the iron in the hepatocytes and/or macrophages (including Kupffer-cells) is essential for evaluating the background of this "storage". In some situations, especially in birds, the spleen can be used to differentiate between a dietary overload or excessive hemolysis. Etiologically there are several possible backgrounds for iron in the liver: oral intake of iron, infectious diseases, and excessive hemolysis. It is essential to differentiate between the different possible causes, because some involve diet management, others do not. In a study we re-evaluated the livers of 945 birds (13 orders), 179 New world monkeys (11 families) and 136 artiodactyla (6 families, 32 genera) using Prussian blue, scoring from 0 to 4 for the staining intensity. We also differentiated for localisation: hepatocytes, macrophages or both. The results indicate different sensitivity to iron-storage in different species or groups of animals. There was is some species a remarkable difference in iron load between two larger zoos indicating differences in iron diet contents. In many species iron was only restricted to the reticulo-endothelial-system, which might be related to specific iron absorption by macrophages. This information indicated the need for more research, but above all communication between the nutritionist and the pathologist about the diet in relation to the finding of iron in the liver. In the necropsy reports "iron" should be differentiated in "iron in macrophages" and "iron in hepatocytes. It is also essential in this study that all material is collected from animals that died spontaneously for some pathological reason. It is the opinion of the authors that iron in the hepatocytes is always directly related to iron intake via the gastrointestinal tract unless iron injections were used for therapeutical reasons.
DIGESTIVE STRATEGIES IN MEAT AND FISH EATING BIRDSDavid C. Houston Dr.1
1 Division of Environmental & Evolutionary Biology, University of Glasgow, Graham Kerr Building, Glasgow G12 8QQ, Scotland, United Kingdom
Birds of prey and fish-eating birds show inter-specific variation in the efficiency with which they digest their food. This variation is associated with differences in gut morphology and digestion rate. We have carried out feeding trials and post-mortem studies of gross gut morphology. These suggest that in both groups there is an apparent trade-off between digestion rate and digestion efficiency; species with rapid digestion tend to show rather inefficient digestion. In raptors there is also a negative correlation between gut size and digestive efficiency. Such a trend is not evident in piscivorous birds, probably due to an overriding link between metabolic rate and gut size. We consider the factors, which determine the digestion strategy adopted by a bird species. Fast but inefficient digestion may be selected if the consequent rapid weight loss following a meal results in improved foraging success, giving a greater overall rate of energy gain. This might occur in pursuit foraging birds, which rely on rapid acceleration and agility to catch prey. Finally we consider the implications of variation in digestion strategy for prey selection.
CAROTENOID METABOLISM IN ORNAMENTAL FISHRimi Obra1, A. I.Macartnez1, M.Boaz1, and S. M. Priestley1
1 Waltham Centre For Pet Nutrition, Melton Mowbray, Leicestershire, United Kingdom
Carotenoids are one of the most widespread groups of natural pigments in nature, with over five hundred identified. The primary source of carotenoids in the food chain is from photosynthetic plant tissue such as algae. Consequently, the vibrant red, orange and yellow pigments in the flesh, skin and exoskeleton of animals such as flamingos, koi, salmon and shrimp are a result of carotenoid ingestion and metabolism. Fish, like other animals, are incapable of synthesising carotenoids de novo and therefore acquire them from dietary sources such as plants and crustacea. There is a general tendency amongst aquatic animals to preferentially accumulate xanthophylls rather than carotene pigments. Xanthophylls are a classification of carotenoids which include; Astaxanthin (red), Canthaxanthin (pink), Zeaxanthin (orange) and Lutein (yellow). Carotenes include b- carotene and g -carotene. The main bank of carotenoids in fish is the integument, within highly specialised cells called chromatophores. Chromatophores are classified according to the colour of pigment that they contain. Erythrophores stock red or orange carotenoids and xanthophores primarily store yellow carotenoids. Research has been conducted to investigate the pigmentation dynamics of goldfish (Carassius auratus). Goldfish belong to the Cyprinidae family, which are able to biosynthesise astaxanthin (red) from lutein sources (yellow). Goldfish with uniform skin pigmentation (n=280) were selected from quarantined stock. Experimental diets, which were iso-caloric, were formulated with different carotenoid sources. These included sources of lutein, astaxanthin, capsanthin and capsorubin. Combinations and differing levels of carotenoid sources were also used so that eight experimental diets were fed in total. The performance of these diets were compared against a control base diet, devoid in carotenoids. Twenty fish were maintained on each experimental diet during the course of the 12-week trial. Fish were fed at 2% bodyweight per day, in three feeds a day, five days a week. A panel of trained assessors were used to colour assess the fish at weeks 0, 3, 6, 9 and 12. Each fish was scored under uniform fluorescent light against an 8 graded colour chart ranging from pale yellow "1" to deep red "8". In addition to this, groups of fish were also ranked relative to others, thus resulting in a hierarchy of perceived intensity of colour. Results were analysed using multiple ANOVA. At week 0, all the fish fell between the scores 1 to 3 (pale yellow to yellow). By the end of the 12-week trial, mix of the eight diets tested had resulted in significant increases in the colour score of fish. These were lutein sources fed at both 3% and 0.5% inclusion in the diet, the capsanthin source fed at 3% nd 0.5%, and a combination of a lutein and a capsanthin source fed at 3%. All colour and ranking scores correlated. The rate of colour change was generally fastest during the first three weeks of the trial. Of all the diets tested, a source of lutein fed at a level of 3% in the diet resulted in the fastest and most significant colour change. No significant decreases in colour were observed 23 weeks following the cessation of supplementation.