Vitamin and mineral supplementation

Intake and digestion in two iguanid species fed a fiber-supplemented salad mixture: preliminary observations.

E. S. Dierenfeld

Department of Animal Health & Nutrition, St. Louis Zoo, St. Louis, MO, USA.

Two (1.1) adult green (Iguana iguana) and one (1.0) adult and 3 (2.1) juvenile rhinoceros iguanas (Cyclura cornuta cornuta) were fed a diet comprising a mixture of chopped salad greens, vegetables and fruit (recipe: 55% greens, 30% vegetables, 15% fruits) with or without a dried chopped grass hay supplement. The salad without added hay comprised (dry matter [DM] basis): 19.2% crude protein (CP), 26.0% neutral detergent fiber (NDF), 20.6% acid detergent fiber (ADF), 1.2% Ca, and 0.4% P. The same salad with 5% added chopped hay contained 18.2% CP, about 50% more fiber – 37.5% NDF, 29.8% ADF, and 1.0% Ca, 0.4% P. Adult lizards were housed individually, as was the single juvenile female rhinoceros iguana; the two juvenile males were housed together for a total of 5 data sets. Green iguanas were housed at 28.3°C, 44% RH and fed daily, whereas rhinoceros iguanas were housed at 27.7° C and 60 to 70% RH. and fed every 2 days. Feed intake and total fecal output data were collected over 4 (I. iguana) or 12 (C. cornuta) consecutive days with correction for desiccation in feeding pans for each diet treatment. The juvenile female rhinoceros iguana (body weight 1342 g) was fed 100 g salad every 2 days whereas the juvenile males (average body weight 1786 g) were fed 400 g total. The adult male (weight 6.82 kg) was offered 500 g salad. The adult green iguanas (weights 3820 kg and 3060 g for male and female, respectively) were each offered 225 g salad daily. Adult iguanas consumed 0.6 – 0.8 % of body weight on a DM basis daily when fed salad with no hay, and 0.4 – 0.7% with added hay. Average daily dry matter intake (DMI) for juvenile rhinoceros iguanas ranged from 0.3 – 1.0% of body weight when fed salad with no hay, and increased (0.4 – 1.4% DMI) when fed the hay-supplemented diet. There was a transitory effect of added fiber on palatability when supplemented diets were first presented. With the exception of one animal, intakes increased and stabilized after the initial offering of the altered diet (transition period 1 to 2 weeks). Dry matter digestibility (DMD) averaged 92% on the salad without hay in adult iguanas, but only ~30% in juveniles. DMD decreased to 73% with the added fiber in adults, but increased to 76% in juveniles. Overall protein digestion decreased from 89 to 76% with the diet change; responses by adults compared with juveniles, however, differed (adults decreased, juveniles increased). Fiber digestion decreased from 88% to 63% (NDF) and 87% to 67% (ADF) in iguanas. Surprisingly, juvenile rhinoceros iguanas displayed higher fiber digestion ability compared with the adult in this trial. Transit of food was apparently slowed by the addition of insoluble fiber, as defecation interval increased from daily to every two days in the green iguanas fed the hay-supplemented diet. Additionally, animals displayed higher fecal protein concentration in feces on the hay-supplemented diet, presumably from greater microbial contribution. Passage rates, however, were not measured in this initial study. Analyses of native foods eaten by iguanas suggest these animals are capable of utilizing higher fiber content than provided by most captive diets. Although high fiber diets can slow growth in young animals, maximal fiber digestion ability of adult iguanas has not been challenged in controlled feeding trials. Increased DMI, longer food retention, possible beneficial gut environment and microbial population alterations, and improved utilization of feeds may be realized by the addition of 5% chopped grass hay to produce-based diets fed to iguanas.

Different supplementation of minerals in bats and the consequences on bone mineral density

A. Liesegang1, U. Firzlaff2, B. Kiefer3, W.J. Streich4, M. Clauss3

1 Institute of Animal Nutrition, ZÒrich, Switzerland, 2 Department Biologie II, Neurobiology, LMU, Munich, Germany, 3 Institute of Physiology, Physiological Chemistry and Animal Nutrition, Munich, Germany,4 Institute of Zoo and Wildlife Research (IZW) Berlin

In feeding insectivorous animals with live insects, the mineral supplementation of the insects is an important part of the dietary management. We investigated the consequences of mineral supplementation of mealworms at a facility where mustached bats (Pteronotus parnellii rubiginosus) from Trinidad were kept for experimental purposes. For 11 months after capture from the wild, the animals were constantly housed indoors under a constant photoperiod of 12h at 75 % relative humidity and fed a diet of mealworms. The mealworms were kept on a substrate of oat flakes. Death occurred spontaneously in several animals for no obvious reason, but the cranial skeleton was soft at palpation, a mineral deficiency was suspected. Consequently, the mealworms were placed on a mineral supplement one day prior to feeding, which increased their calcium content from app. 1 g/kg dry matter to app. 10 g/kg dry matter, and increased the calcium:phosphorus-ratio from app. 0.15 to app. 1.50.
We investigated bodies from animals that died at different stages of the husbandry process. Six animals were killed at capture from the wild, representing the free-ranging controls (Group A), eight animals died or were killed for experimental purposes while on the preliminary feeding regime (Group B), and six animals died or were killed for experimental purposes while on the final, supplemented feeding regime (Group C). After measuring the length of the radius with a digital caliper, total bone mineral density (BMD) was measured in the left radius with peripheral quantitative computer tomography (Stratec XCT 2000 bone scanner, Stratec Medizinaltechnik GmbH, Pforzheim, Germany). The measurements were taken in the middle of the diaphyses (at 50% of total length). Cortical BMD (Cortical mode 2; threshold for cortical bone >640 mg/cm3) was calculated by automated computation.
Bone mineral density was highest in group A. Group B had significantly lower bone mineral density than Group A. Interestingly, Group C, receiving supplementation, showed no significant difference compared to Group A.
The supplementation of minerals to the diet of bats did induce differences between the groups. The animals from the wild had similar densities in the radius as the supplemented bats whereas the animals receiving no supplementation showed significantly lower densities than animals from the wild. This supports the assumption that it is important to feed a mineral supplementation to captive bats to conserve their normal bone structure.

We thank the Wildlife Section of the Ministry of Agriculture, Land and Marine Resources , Trinidad, for the permission to capture and export the bats, and Mr. F. Muradali for the capture.

Observations on the antioxidant status of domestic equines as influenced by supplementary dietary antioxidants.

J.A. Lowe, D. Lucas, G. Paganga

Dodson and Horrell, Ringstead, Kettering, Northants NN14 4BX, UK

A study was undertaken to examine the effect of a combination of supplemental antioxidants on the antioxidant status (TAS) of modern, domesticated horse which, by way of management, housing and feeding is considered to experience a relatively high level of free radical challenge and often low and variable antioxidant intake. Six adult horses (12-31 years, 400-680 kg) received a diet of conserved forage and grass (3 hr / day) together with a compound feed corrected to an intake of vitamin E equivalent to 1.65mg/kg body mass (BM), so as to maintain condition pertinent to exercise intensity. Each horse received a metabolic body mass equivalent of supplemental antioxidants (vitamins E 0.05 mg/kg, C 0.09 mg/kg, bioflavanoids 15.5 mg/kg) for six months, followed by 3 month withdrawal period and a subsequent 3 month reintroduction. Routine 3 monthly plasma samples taken by the veterinary surgeon were used with informed consent to determine the antioxidant capacity (TEAC), vitamin C, E, cholesterol and triglyceride concentrations and resistance of low-density lipoprotein to oxidation (RLDLO). Each horse acted as its own control with comparisons using paired t-test for differences between periods. Plasma vitamin E,C, TEAC and RLDLO increased above initial values by 3 and at 6 months (mean4.5±SE1.63mg/ml to 6.1±2.58mg/ml P<0.05; 0.8±0.22mg/100ml to 1.2±0.26mg/100ml P<0.01; 0.7±0.13 to 0.9±0.07 P<0.001; 46±11.9min to 63±15.7min P=0.002 respectively). These values declined when the supplement was removed, but increased to at least the 6 month values after the supplement was re-introduced. No changes were observed in cholesterol (2.9±0.52mg/dl to 2.7±0.17mg/dl, P=0.2) or triglycerides (19.2±10.57mg/dl to 13.1±6.82mg/dl, P=0.06). The plasma vitamin E increase did not appear to be in proportion to the additional dietary supplemental vitamin E. Improvements in the values for TEAC and RLDLO suggest an improved recycling of endogenous vitamin E. Antioxidants are known to be more effective in increasing TAS in combination than in isolation. These observations indicate that the TAS of the horse - as in other animals such as the dog -, may be further improved by the addition of a combination of antioxidants. In this case the increase occurred even though the horses were receiving what is considered in the literature to be adequate vitamin E.

Poster : Increasing calcium content in Jamaican field crickets (Gryllus assimilis)

K.Eidhof , D.Venema, D.Kuiper, T.R. Huisman

1Dept of Animal Management, Van Hall Instituut, Leeuwarden,

Crickets are a poor calcium source but often used as feed insects for reptiles and other captive animals. A method to enhance the calcium content of crickets is feeding them a diet with a very high calcium content (>8%). This so called ‘gut loading’ is already well researched in house crickets (Acheta domesticus) but never in Jamaican field crickets (Gryllus assimilus).
In an experiment we tested the effect of gut loading with one base diet (0.84% Ca) and three experimental calcium fortified diets (8%, 10%, 12% Ca respectively). All feed was finely ground and its dry matter content was 95%.
The calcium content in the dry matter of the crickets fed the base diet increased during 144 hours from 0.20 % to 0.27%. After 48 hours feeding the 8% diet, dry matter calcium content in crickets was 1.3%. Similar levels were reached after 24 hours feeding the 10% and 12% diet. After 72 hours feeding the experimental diets Ca levels in the crickets reached their maximum. After this the levels decreased in the 10% and 12% groups, probably due to reduced intake, but remained constant in the 8% group. A positive calcium phosphorus ratio was reached after 48 hours feeding the 8% diet and 24 hours feeding the 10 % and 12% diets.
Crickets consumed slightly more from the 10% and 12% diets, maybe due to energy dilution in the experimental diets. During the experiment hardly any mortality was observed.
Crickets fed the 10% experimental diet for 24 hours were offered for one week to growing leopard geckos. They accepted the crickets well.
For fast increase of calcium levels in crickets we recommend at least 10% Ca in the diet offered. When the crickets are kept for a longer period before feeding we recommend 8% Ca in the diet.

Poster: Vitamin A, D, E and B1 content in diets of captive piscivorous animals

M. de Boer1, H. Oorsprong1, S.J. de Goede1, M. Janse2, C.Berndt3

1Dept. of Animal Management, Van Hall Instituut, Leeuwarden
2 Burgers’ Zoo, Arnhem, The Netherlands
3 Noorder Dierenpark Emmen, The Netherlands;

Literature indicates that when feeding fish to piscivorous (fish-eating) animals, due to the unsaturated fatty acid content and risk of presence of thiaminase in fish, there is a necessity to supplement vitamin E and B1. Results of a preliminary survey indicated that there are important differences between zoos pertaining to the dosage of vitamin supplements. Quite often multivitamin supplements are used instead of specially manufactured supplements.
To get more insight in present supplementation practices in Dutch Zoos a more detailed survey was started. Data on the ingredient composition, including supplements, were collected for eleven different species (3 bird species, 2 marine mammal species and 6 shark species). With these data energy and vitamin content of the diets were calculated using various food tables.
Diets (fish and supplements offered) from 26 separate groups of animals from 7 zoos were evaluated. Results indicate that for 24 groups supplementation with vitamin A seems not necessary. In 11 cases animals are offered more vitamin A than the upper safe levels. However, it is not clear whether the existing upper safe levels in literature are also applicable to specialised piscivores.
All animals receive enough vitamin D. For 25 groups there seems no need for supplementation. In 15 cases animals get more than the recommended upper safe level. The comment on Vitamin A upper safe levels also applies to vitamin D.
In eight cases the calculated dietary vitamin B1 levels were lower than recommended in literature. Vitamin E levels were also in eight cases lower than recommended. In a few cases shortages could be explained because it appeared that totally inadequate supplements (designed for ruminants) were used.
Overall, there were dramatic differences in the use of supplements and their dosage.
It is strongly recommended that supplementation practices for piscivorous animals in Dutch zoos are thoroughly re-evaluated.
A major obstacle in this project was the lack of reliable data on the nutrient content of whole fish. A proposal will be made to help solving this important problem.