MEASURING UVB AND VITAMIN D LEVELS IN KOMODO DRAGONSJ. Nijboer1, H. van Brug2 and H. van Leeuwen3
1Veterinary Department, Rotterdam Zoo, Van Aerssenlaan 49, 3039 KE Rotterdam, The Netherlands; 2Section Optica, TU-Delft; 3Dep. of Internal Medicine, Erasmus University, Rotterdam, The Netherlands.
Komodo dragons (Varanus komodoensis) are rare animals that only inhabit the islands of Komodo, Rintja, Padar and Flores in Indonesia. Currently only a few western zoos have these reptiles in their collection and unfortunately breeding results are poor in captivity. To date komodo dragons have only been bred in a few institutions. In 1992 and 1995 Rotterdam zoo received two adult komodo dragons from Singapore zoo and Surabaya zoo, but both died, in 1996 and 1998 respectively. In 1995 Rotterdam obtained 3 juvenile komodo dragons born at the National Zoo in 1994. From the literature it is known that juvenile komodo dragons in particular can suffer long bone fractures due to inadequate vitamin D synthesis through lack of UV-B light. Although the juvenile komodo dragons were exposed to UV-B in Washington they did not receive it in Rotterdam. There are two sources from which vitamin D3 (cholecalciferol) is provided normally: it is produced in the skin or it is absorbed by the diet. Vitamin D2 (ergocalciferol) is derived from plant sterols. In the skin 7-dehydrocholesterol is photochemically (using UV-B) converted to provitamin D3, then it isomerizes to vitamin D3. Vitamin D3 from the skin is bound to vitamin D binding protein which goes to the liver to be hydroxylated at the carbon 25 position by the enzyme 25-hydroxylase to form 25- hydroxyvitamin D3 (25-(OH)D3). Finally, in the proximal tubules of the kidney, the biologically most active metabolite: 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) is formed. In nature the 25-OH-D3 level in komodo dragons ranges from 150-200 nmol/l serum. After 19 months in the collection at Rotterdam, the blood values found in the juveniles of Rotterdam dropped to 18-31 nmol/l without adding extra vitamin D to the diet and without exposing them to UV-B. Supplying 450 IU vitamin D3
/kg food (calculated) did not show any marked effect: after 2 months the 25-OH-D3 levels ranged from 26 37 nmol/l. One of the juveniles went to Gran Canaria (Spain) and within 9 months the 25-OH-D3 level rose to 272 nmol/l. The other two juvenile Komodo dragons stayed in Rotterdam and obtained UV-B light. After 4 months the level of 25-OH-D3 had risen to 201 nmol/l and exposure for 12 months maintained this level (195 nmol/l). During the whole period the quantity of 1,25(OH)2D3 did not change significantly; this is in contradiction to 25-(OH)D3 which over the whole test period varied from 121.6 to 235.3 nmol/ml. Compared with humans, the circulating 25-(OH)D3 levels found in Komodo dragons in captivity are low, but the 1,25-(OH)2D3 levels are elevated. The assays used to measure vitamin D showed cross-reactivity between the comparable metabolites of vitamin D3 and vitamin D2. However, it is unlikely that the compounds measured are vitamin D2 compounds, as Komodo dragons only eat whole prey and so despite cross-reactivity, it is unlikely D2 compounds are changing. The current study shows that Komodo dragons respond to UV-B with a strong increase in circulating 25-(OH)D3. However, the increase is not paralleled by a comparable increase in serum 1,25-(OH)2D3 levels. These levels did not change after UV-B treatment. This can be interpreted as a mechanism against life-threatening hypercalcemia, a consequence of elevated 1,25-(OH)2D3 levels and a defence similar to that found in humans. The 25-(OH)D3 levels varies throughout the year depending on the season or sun exposure, however the serum 1,25-(OH)2D3 level does not show a comparable seasonal fluctuation but is steady throughout the year. Therefore, based on the data presented, it is questionable to conclude that Komodo dragons held in captivity without additional UV-B treatment actually suffer from vitamin D deficiency. Finally, in order to routinely check the intensity of UV-B radiation from the lamps it is necessary to have a measuring device which is ortable and small, and which is sensitive to the UV-B wavelength. To achieve this we designed and constructed an intensity meter which is sensitive to a narrow wavelength (10.17 nm at FWHM) around 302.01 nm.
RATION MODELLING FOR GROWING OSTRICHES (Struthio camelus)G.P.J Janssens*, K. Vanhemelryck, M. Hesta, V. Debal, J. Debraekeleer and R.O.M De Wilde
Laboratory of Animal Nutrition, Ghent University, Heidestraat 19, B-9820 Merelbeke, Belgium
In comparison to most husbandry animals, nutritional requirements of ostriches (Struthio camelus) have been scarcely investigated. Because of the time and finance consuming character of metabolism trials, an alternative method is suggested to come to adequate feeding of growing ostriches. As the digestive system of ostriches shows analogies to the equine digestive system, a computer model was built to predict energy and protein requirements for ostriches, based on two data sets : 1) the VEP/VREp system, a protein and energy evaluation system for horses developed by the Centraal Veevoederbureau in the Netherlands (4) and 2) the experimentally obtained true metabolisable energy values for ostriches (TMEo) from South-African research (1,2,3). These already available TMEo values were used to calibrate the VEP values for a wide range of feedstuffs by linear regression fitting. The energy requirement, protein requirement and dry matter intake were estimated through body weight and growth rate, based on the formulae from several studies (5,6,7) respectively. The model was constructed in Microsoft Excel. To test the model, two groups of 50 ostriches of similar origin were chosen in a way that they both had a similar variation in age (162-232 d) and initial body weight (19-73 kg). The first group received a high-fibre diet and the second group received a low-fibre diet. The growth rates, feed intakes and feed conversion ratios were used to calibrate the model.
1. Brand TS, De Brabander L, van Schalkwyck SJ, Pfister B, Hayes JP, 2000. Br Poult Sci 41, 201- 203.
2. Cilliers SC, Hayes JP, Maritz JS, Chwalibog A, du Preez JJ, 1994. Anim Prod 59, 309-313.
3. Cilliers SC, Hayes JP, Sales J, Chwalibog A, du Preez JJ, 1998. Anim Feed Sci Tech 71, 369-373.
4. CVB, 1996.
5. Degen AA, Kam A, Rosenstrauch A, Plavnik I, 1991. Anim Prod 52, 225-232.
6. Du Preez JJ, Jarvis MJF, Capatos D, de Kock J, 1990. Proc 29th Ann Congr South Afr Soc Anim Prod L3.5
7. Du Preez JJ, 1991. In: DJ Farrell (ed.), Recent Advances in Animal Nutrition in Australia 14pp.
A COMPARISON BETWEEN THE NUTRITIONAL CONTENT OF DIETSA.K. Bond
Bristol Zoo Gardens, Clifton, Bristol, BS8 3HA, UK and Cardiff University, The Department of
Biosciences, Park Place, Cardiff.
When presented with a mixed diet, birds will preferentially select certain components. It is therefore inappropriate to assess the nutritional content of diets offered to the bird, with the assumption that all of the nutrients are ingested in those proportions. The effect of this selection process on the diet consumed, and therefore the nutrients eaten, will depend on how selective the species is. This study used Zootrition to compare the nutritional content of diets offered and diets eaten by Mindanao bleeding heart doves (Gallicolumba criniger) and superb fruit doves (Ptilinopus superbus) at Bristol Zoo Gardens. The nutrients present in both the offered diet and the eaten diet were compared to recommended nutrient requirements for domestic pigeons1, the closest species for which nutrient requirements have been suggested. Nutrients containing missing values were ignored, resulting in the analysis of only 14 of a possible 55 nutrients present in the Zootrition software. These two species are fed the same diet, yet they showed a marked difference in their selectivity for the components of that iet. The superb fruit doves displayed strong preferences for dried fruit and apple. Although they only ate 59% (by weight) of the total diet offered, they ate 98% of the dried fruit offered and 86% of the apple offered. This strong selective behaviour resulted in the composition of the eaten diet to differ greatly from that of the offered diet, reducing the proportion of insectivorous mixes from 10% to 2% of the diet and completely eliminating Mazuri Sea Duck from the diet. Differences in the composition of the food offered and the food eaten by the Mindanao bleeding heart doves were less marked than for the Superb fruit dove. This apparently low level of selection still produced large differences in nutrient composition between the diet eaten and the diet offered. In the eaten diet the proportion of dried mixed fruit was reduced by a third (by weight) whereas the proportion of mixed pulses was doubled. For both species, the change in composition of the diet as a result of selection caused the proportion of nutrients eaten to differ from the proportion offered. The selective behaviour of the superb fruit dove lowered the proportions of crude protein and crude fat in the diet by about 30%. Interestingly, in the diet eaten by the Mindanao bleeding heart the opposite occurred. The proportion of crude protein was increased by one third, and the proportion of crude fat was increased by almost two thirds. The levels of the nutrients offered and the nutrients eaten by both species did not match those recommended. The health of both species and in particular, the breeding success of the Mindanao Bleeding Hearts, suggests that the nutrient recommendations for domestic pigeons is not an accurate representation of the nutrient requirements of these two species. Alternatively, an exact match to the required nutrients may not be necessary for health or successful breeding. 1 Recommended nutrients for pigeons :Breeding, Racing, Molting. Branson W.R et al, Avian Medicine, Principles and application, (1994).
DIET SELECTION BY THE WHITE-NAPED PHEASANT PIGEON Otidiphaps nobilisH. Marqués1*, M. D. Baucells2, E. Albanell2 and G. Navidad1
1Parque Zoológico de Barcelona, Parque de la Ciudadela s/n, 08003 Barcelona, Spain;
2Departamento de Ciencia Animal y de los Alimentos, Facultad de Veterinaria, Universitat Autònoma de Barcelona, Bellaterra, Barcelona Spain.
Otidiphaps nobilis aruensis is an endemic columbiforme from Aru Isle (South-West of New Guinea). It is poorly represented in captivity and there is not enough information known about the biology and wild status of this endangered specie. However, due to its insular situation, its wild status may be critical. The Barcelona Zoo holds 18 individuals (53 %) of the total European captive population, with two wild caught breeding pairs. The aim of this study was to determine the diet consumed by the captive population of these birds at the Barcelona Zoo, and some of the factors that could have an influence on diet selection. The study was carried on at the Barcelona Zoo with 11 (8.3) captive born individuals (descendants from the two breeding pairs), between 5 and 20 months of age at the time of study. The animals were housed individually and the intake was evaluated through three experimental periods (see Marques et al., 2000 for further details on housing and methodology). The diet consisted on 10 ingredients grouped in 4 categories: grains (wheat, millet and canary seed), commercial feeds (Zeigler Fruguivore Supplement, Universal Insectivorous Diet Witte Molen, Egg rearing Food With Hedgerow Plants Kasper Faunafoods), animal protein (mealworms, hard boiled egg), and vegetables (lettuce and fruit mix: apple, pear, banana, carrot). All ingredients were offered close to add libitum, except for the mealworms (Zophoba sp.), which were used to encourage birds to go on a weighing scale. The animals on this diet kept growing normally and looked healthy. The data obtained were analyzed by Proc Tabulate and Proc Mixed of SAS. The animals consumed a total of 33,2 ± 0,82 g of diet (22 ± 1,30 g on a dry matter basis, DMB). This amount was 4 times lower than the offered. Great differences among individuals were observed on diet selection, but the mean diet composition was: 38 % grains, 25 % commercial foods, 19 % animal protein, and 18 % vegetables. None of the ingredients was consumed more that 40 % of the amount offered, except for the mealworms. There were significant differences on ingredient selection among ages (juveniles 20 35 weeks old, n=7; elders 43 82 weeks old, n=4). The younger animals consumed significantly less grains than the older animals (10,3 ± 1,27 g vs. 17,2 ± 2,27 g; P<0,001). The younger animals, had instead, a tendency to eat more commercial foods (P=0,07). Additionally, some differences were observed among individuals that came from different progenitors in the consumption of some grains (i.e. wheat and canary seed). Whereas no differences in any of the other ingredient groups was detected. Curiously, males consumed significantly more lettuce than females (1,67 ± 0,5 g vs. 0,56 ± 0,5 g; P<0,01). This project has been granted by the Durrell Wildlife Conservation Trust.
Reference: Marquès H., Gonzalo C., Navidad G., Colom, L. (2000). Study of the diet fed to captive white-naped pheasant pigeons (Otidiphaps nobilis aruensis) at the Barcelona Zoo. Proc. Comp. Nutr. Soc. pp 132-137.
ASSESSING DIETS FOR CONGO PEAFOWL Afdropavo congensis AT JERSEY ZOOK. Foster
Durrell Wildlife Conservation Trust, Les Augrès Manor, Trinity, Jersey JE3 5BP, Channel Islands, British Isles
Nutrition is a crucial aspect of the conservation of endangered species as it has direct consequences for the successful maintenance and breeding of species in captivity. Congo peafowl, Afropavo congensis, are considered vulnerable in the wild and there is managed captive breeding programme (EEP). However, the birds suffer from health and breeding problems in captivity. Chick mortality is high, resulting in low population growth. Causes of adult death (n=15) and disorders identified at post mortem in Congo peafowl at Jersey Zoo (1998-2000) included several which may be diet-related: obstruction of the oviduct caused by egg retention, egg peritonitis, kidney failure, heart failure, fat accumulation around the heart, hyperlipaemia, liver disease, lipidosis, gout and myocardial degeneration. This study was undertaken in order to calculate the nutrient composition of the diets provided to and consumed by the peafowl in order to evaluate the quality of the diet. The diets provided to Congo peafowl (n=11) consisted of chopped fruits, sprinkled with the vitamin and mineral supplement Nutrobal, and a dry mixture containing pheasant breeder pellets, cracked corn, universal insectivorous mix, bread crumbs, carrot, and egg. Mealworms were also provided daily. The diet was quantified over 10 days by weighing the amounts of food provided and left over per aviary (n=5), allowing calculation of the amount consumed per aviary, per individual and per kilogram body mass. As chopped fruit items were presented as a mixture, the remains could not feasibly be separated for individual weighing, so the birds were assumed not to be selective when consuming food. Control feeds were used to correct the feed remains for weight changes due to water loss or gain. The dietary management software Zootrition (Wildlife Conservation Society, 1999) was used to analyse the nutritional composition of the diet, which was then compared to the nutrient requirement levels of pheasants Phasianus colchicus. The peafowl showed a preference for the dry food over the fruit mixture. The most important imbalances in the diet were insufficient calcium and elevated fat levels, which have been linked to egg retention and fat accumulation respectively. The diets consumed contained inadequate amounts of protein when compared to the breeding requirements of pheasants, although the protein levels were adequate for a maintenance diet. A few difficulties in interpreting results arose from the lack of data in the nutritional breakdown of some food items. New diets were formulated for both breeding and maintenance periods, to try to rectify some of the inadequacies. It is desirable for captive diets to vary with season, as they do in the wild. However, Congo peafowl appear to breed year-round at Jersey Zoo, which makes it difficult to define specific breeding and maintenance periods. Although the required nutrients and seasonal patterns are likely to vary between Congo peafowl and the temperate pheasant model, this analysis is still a valuable tool in assessing diets to ensure the provision of well balanced diets to maintain healthy birds in captivity.