Articles 111-120

Considerations on feeds used for zoo ruminants

J. Hummel1, M. Hovenjürgen2, E. Niess2, K.. Johansen3, J.Nijboer4, W.Zimmermann1

1Zoo Cologne, Riehler Str. 173, 50735 Köln, Germany;
2Institute of Animal Nutrition,
University of Bonn, Germany
3Zoo Copenhagen,Denmark
4Zoo Rotterdam, The Netherlands

According to several authors, the nutrition of wild ruminants in captivity still poses some challenges. Factors like concentrate/roughage ratio and the distribution of concentrate consumption over the day have to be considered important when planning a suitable feeding schedule for these animals. Another obviously very important factor for the planning of a diet is the chemical composition and the fermentative pattern of the feeds.
To be able to quantify their fermentative pattern, the gas production of several feeds fed to captive okapi in different facilities was measured via the HFT (Hohenheimer Futterwerttest), a common in vitro technique for evaluating feedstuffs for ruminants. The HFT relates the gas produced by a feed/rumen inoculum mixture to the energy yield of a feedstuff. Gas production is highly correlated to the production of fatty acids. It was recorded after 2h, 4h, 6h, 8h, 10h, 12h and 24h to get information about the rate of fermentation during the first 12 h of fermentation and of the energy yield after 24h.
As expected, feeds like banana or apple resulted in a rather high fermentation rate; during the first 4 hours, these feeds showed higher fermentation rates than all other feeds due to their high sugar content. Fermentation rate of unmolassed beet pulp (6-7 % sugar) was comparable to that of oats and wheat. In this study, dried forage meal (e.g. on a lucerne/clover basis) had a rather low energetic value, even when compared to the lucerne hay used in the facilities. When feeding ruminants reported to show selective foraging behaviour in the wild, there are often speculations about significantly higher demands of these animals for easy digestible feeds. Anyway, they seem to be prone for the known problems occurring in ruminants when fed diets high in sugar and starch. Results will be discussed in respect of their significance for dietary planning and suggestions for favourable concentrates will be made. It is concluded that in vitro techniques like the HFT can be an important tool in evaluating zoo feeds.

The effect of dietary sugar content on glucosuria in a female okapi (Okapia johnstoni)

F. Vercammen1, R. De Deken2, J. Brandt2

1Royal Zoological Society of Antwerp, Antwerp, Belgium
2Veterinary Department, Institute of Tropical Medicine, Antwerp, Belgium

As early as 1980, Glatston & Smith reported that urine of many healthy adult okapis can contain high amounts of glucose. In Antwerp Zoo 5 adults older than 8 years old and one young animal of 3 years old showed glucosuria, whereas 5 other young animals (between 1.5 and 4 years of age) remained negative. The reasons for chronic glucosuria in healthy ruminants remain unexplained yet. Theoretically, a continuous high dietary intake of sugars might be the cause, provided that a ruminal bypass and / or escape exists in this concentrate selector (as suggested for the roe deer, Rowell-Schäfer 1999). In the wild, okapis browse more than 100 species of plants and prefer fast growing heliophilics, but they do not eat mushrooms (Hart & Hart, 1988). In captivity okapis are fed several fruits and vegetables containing high amounts of sugars (mainly bananas, apples and carrots). In order to examine the role of the diet on the glucosuria, a diet with a reduced sugar content was administered during 170 days to an adult female okapi. Over the first 90 days the initial amount of 2.4 kg of bananas, apples and carrots (800 g each) was gradually changed to 0.4 kg carrots and maximum 0.5 kg other vegetables (endives, celery, chicory, tomato, courgette, cucumber and aubergine). Afterwards, on average 0.150 kg more luzern hay per day was consumed. The decrease in dietary sugars amounted to approximately 0.2 kg. This was mainly due to a lower (i.e. 3.76 %) dry matter intake in the second diet, although the sugar content on dry matter base of the two diets was almost the same. Once a month at normal micturation, midstream urine samples were taken and stored at –20°C. The five samples were analysed simultaneously. Urinary glucose (mg/dl) and creatinine (mg/dl) were quantitatively determined using dry biochemistry (Kodak - Johnson & Johnson). To compensate for the variations in volume of the excreted urine, the ratios of glucose and creatinine in each sample were calculated (Finco, 1989; Spieker, 1989). These ratios were 13.56, 9.95, 7.21 and 6.32 after 1, 2, 3 and 5.5 months, respectively. Just before the end of the observation period, the animal had to be anesthetised for hoof trimming and urine was obtained afterwards. The ratio was then 8.88, but a likely explanation of this is the administration of medetomidine, since hyperglycemia is one of the known side-effects of an a2-agonist (Lees, 1991). These preliminary results seem to indicate an impact of decreasing dietary sugars on the glucosuria. However, more data of captive okapis are needed. Obviously, it would be very interesting to compare data of urine samples from captive okapis with those from okapis in Epulu (Central Africa) living in more natural conditions.

Finco D.R., 1989. In: Clinical Biochemistry of Domestic Animals, 4th Edition, Academic Press Inc, San Diego, USA: 496-542. Glatston A.R. & Smit S., 1980. Acta Zool et Path Antverpiensia 75: 49-58.
Hart J.A. & Hart T.B., 1988. Acta Zool et Path Antverpiensia 80: 19-28. Lees P., 1991. In: Veterinary Applied Pharmacology and Therapeutics, 5th Edition, Baillière Tindall, London, UK: 328-354.
Rowell-Schäfer A., 1999. Inaugural-Dissertation, Journal-Nr. 2266, Berlin, Germany: 1-113.
Spieker R., 1989. Berl Münch Tierarztl Wochenschr 102: 52-56.

Blood parameters of captive roe deer (Capreolus capreolus) fawns on diets of different tannin content

M. Clauss 1, M. Lechner-Doll2, K. Lason2, T. Grune3

1Institute of Animal Physiology, Physiol. Chemistry and Animal Nutrition, Munich, Germany
2Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany
3Neuroscientific Research Center, Charité, Berlin, Germany

Potentially beneficial effects of dietary tannins have received increasing attention in human health sciences during recent years. Due to reports on a deliberate ingestion of dietary tannins in roe deer, we wanted to determine potentially advantageous factors of long-term, low-dose tannin feeding in this species by evaluating blood parameters.
Two groups of four hand-raised roe deer fawns were fed on a pelleted diet only. For eight months, the tannin group was supplemented with tannic acid as 3 % of the original feed mixture; for another two months, quebracho was added accordingly. Blood was collected during immobilisation after both periods, and analysed according to standard laboratory procedures.
After tannic acid feeding, the roe deer had significantly lower hemoglobin concentrations, packed cell volumes (PCV), lower glucose and higher total protein values. The general trend for tannin animals to have lower mineral concentrations was only significant for zinc after the tannic acid period. After tannic acid feeding, tannin animals had higher glutathione peroxidase (GSH) (p=0.051) and S GSH (p=0.050) concentrations; after quebracho feeding, control animals had higher malondialdehyd values. After tannic acid feeding, tannin animals had lower thyroxin values.
The small sample size precludes most generalizations. The reduction in mineral levels and parameters of iron metabolism (hemoglobin, PCV) could be expected from similar reports in other species. The lower thyroxine and glucose values could be indicative of a generally lower metabolic turnover in tannin-fed animals, which could have contributed to the higher feed conversion efficiency observed in these animals. For several parameters, the trend observed among our animals was in accord with reported values for free-ranging roe deer (that have a hypothetically consistent tannin intake). The influence of tannins on antioxidant status and its relevance for captive animals should be further investigated.

Ruminants: why browsers are non-grazers

M. Clauss1, M. Lechner-Doll2, W.J. Streich2

1Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Veterinaerstr. 13, 80539 Munich,
2Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany

The validity of Hofmann’s classification of ruminants into different feeding types (BR = browsers, IM = intermediate feeders, GR = grazers) has repeatedly been challenged and recently refuted on the base of Hofmann’s own morphological data. Due to experiences with captive wild ruminants, we inteded to test whether a grass-avoidance, similar to the observed hay-avoidance in captivity, could be found in data on free-ranging BR as well, and whether an anatomical feature could be isolated that accounts for such a forage discrimination. The analysis of two available data sets on the foraging patterns of free-ranging ruminants showed that, while GR species ingest also browse in differing proportions, BR species have a significantly narrower range of foraging diversity, i.e. they include grass in their diets to much lesser proportions. A comparison of data on the thickness of the rumen pillars in different ruminant species showed that BR have significantly weaker rumen pillars than GR. These results can be interpreted in terms of the mechanical characteristics of the different forages in the rumen: grass tends to induce a rumen contents stratification, and therefore GR had to evolve a strong rumen musculature. The natural forage of BR, however, does not induce a rumen contents stratification, these animals therefore never needed to evolve a strong rumen musculature, and consecutively will avoid stratifying forages, i.e. grass. While it is no mechanical problem to ingest browse when adapted to the characteristics of grass, vice, versa, there is.
We propose that the mechanical properties of the different forages, in particular the tendency of grasses to stratify, were the main driving forces of ruminant feeding type diversification, and are responsible for the increased particle retention, increased particle communition and fibre digestibility observed in GR.

The attribution of a feeding type to a ruminant species based on morphological parameters: the example of the okapi (Okapia johnstoni)

M. Clauss1, J. Hummel2, J. Völlm3

1Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Veterinaerstr. 13, 80539 Munich, Germany
2Zoological Garden of Cologne, Germany
3Zoological Garden of Basle, Switzerland

While Hofmann’s work provides a plethora of morphological parameters by which he attributed the different ruminant species to one of the three feeding types (BR = browsers, IM = intermediate feeders, GR = grazers), he did not set up a scheme by which potential followers could investigate further species, or rank his measurements according to importance. We intended to replicate the classification of a species of known free-ranging foraging behaviour but which had not yet been classified according to Hofmann, by the use of different morphological measurements.
An adult, captive, female okapi had to be euthanazed due to chronic illness and old age. Several measurements of the feeding apparatus and the digestive tract were performed according to standard anatomical practices.
According to the size and structure of its forestomach – a relatively small rumen capacity, low reticular crests, a small omasum and weak rumen pillars, the okapi would be classified as a typical BR. Measurements of the tongue and the incisor arcade supported this classification. In contrast, the relative weights of both parotid salivary glands and liver did not fit the pattern claimed for BR. deviations from Hofmann’s original scheme have been reported previously especially for the salivary glands.
The question of whether Hofmann’s classification can be replicated in anatomical terms is an academic one. For the management of a species, all available information – anatomical, physiological, and from observations in the wild – should be collated. In this respect, the classification of a species as a BR, with a relatively smaller and weaker rumen, should be regarded as an indication of particular proneness to digestive problems.

Faecal dry matter content in captive wild ruminants: implications for the browser/grazer-dichotomy

M. Clauss1, M. Lechner-Doll2, W.J. Streich2

1Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Veterinaerstr. 13, 80539 Munich, Germany
2Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany

Among the feeding types introduced by Hofmann (BR = browsers, IM = intermediate feeders, GR = grazers) the IM/GR have been able to conquer a greater variety of habitat niches than the evolutionary older BR. One would expect such a difference in habitat variation to be reflected by a variety in morphophysiological adaptations.
We therefore investigated the faecal dry matter (DM) content in the faeces of 245 individuals of 81 captive wild ruminant species. Animal sampled were adult, did not have diarrhoea, and had ad libitum access to drinking water. DM content was determined by drying cleaned faeces to constant weight.
While there was no difference in average faecal DM content between the feeding types, frugivores and BR had a much narrower range of faecal DM contents than IM, which in turn, although they comprised the majority of the species sampled, had a narrower range of faecal DM content than GR.
As it has been shown that faecal DM content correlates to the length of the colon descendens, and the animals investigated in our study were not subjected to varying heat stress, the faecal DM content could be interpreted as a surrogate measure for the colon descendens length. The data are in accord with the observation that among the GR, the hippotraginae have very long, and the bovinae very short hindguts. Thus, the greater variation in faecal DM content can be interpreted as indicative of a greater variation in anatomical hindgut design in GR. Integrating the knowledge of forestomach differentiation, GR are therefore considered ‘morphophysiologically progressive ruminants’, while BR are regarded as ‘morphophysiologically conservative ruminants’.

Reaction of a group of captive giraffe (giraffa camelopardalis) to the introduction of a tannin-containing pelleted diet

M. Clauss1, E.J. Flach2, M. Lechner-Doll3, J.-M. Hatt4

1Institute of Animal Physiology, Physiol. Chemistry and Animal Nutrition, Munich, Germany
2Institute of Zoology, Whipsnade Wild Animal Park, Dunstable, UK
3Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany
4Division of Zoo Animals and Exotic Pets, Zurich, Switzerland

As it had recently been reported from preference trials that captive roe deer (Capreolus capreolus), a small ruminant browser, deliberately included tannins in its diet we intended to test the effect of offering a tannin-containing diet to captive giraffe. Three individual adult giraffe and a group of three growing animals were used. Food consumption was determined for a week before and two weeks after the addition of a tannic acid-containing pelleted feed to the regular diet. Food and faecal samples were taken throughout the trial period to determine digestibility coefficients by the lignin method.
The giraffe differed enormously in their response to the additional tannin feed. One adult animal refused the tannin feed completely. The growing animals and another adult animal ingested differing proportions of the tannin feed, and the last adult animal preferred the tannin feed over the regular pelleted diet in constantly increasing amounts. However, even this animal reduced its tannin intake after 16 days. The total dry matter intake of the two adult animals that ingested the tannin feeds increased significantly after the introduction of the new diet item. Digestibility coefficients for the different periods did not differ consistently. The results indicate that individual feeding preferences can make it difficult to determine species-specific ones. Although the results of two adults and the subadult group seemed to suggest a preference for a certain amount of tannins at first, this trend was reversed after 10- 15 days. With respect to the increased feed consumption, one should not exclusively consider effects of the tannins, but of the general feed variety. As an increase of food ingestion could be a desired effect in captive giraffe, further studies on the effect of dietary variation in this species should be investigated.

Tannin-binding salivary proteins in three cative rhinoceros species

J. Gehrke1, J. Fickel1, M. Lechner-Doll1, R. Hermes1, E.J. Flach2, J.-M. Hatt3, M. Clauss4

1Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany
2Institute of Zoology, Whipsnade Wild Animal Park, Bedfordshire, UK
3Divison of Zoo Animals and Exotic Pets, Veterinary Faculty, Zurich, Switzerland
4Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Germany

It has been demonstrated that the presence of salivary tannin-binding proteins (TBP) in mammalian herbivores is related to their dietary habits, with browsers having higher concentrations. As the three main representatives of the rhinoceroses differ in their natural diet – the white rhino (Ceratotherium simum) a strict grazer, the black rhino (Diceros bicornis) a strict browser, and the Indian rhino (Rhinoceros unicornis) a mixed feeder with grass as the major portion of its natural diet, we intended to demonstrate an according pattern in salivary TBP distribution.
Saliva was collected from 9 white, 10 black and 8 Indian rhinos from different zoological institutions and analysed for TBP by tannin binding assay, using a hydrolyzable (tannic acid) and a condensed (quebracho sol) tannin as standards.
Black rhino saliva bound significantly higher concentrations of both hydrolyzable and condensed tannins than white rhino saliva. Indian rhino saliva had a capacity to bind hydrolizable tannins similar to that of the black rhino, but a significantly higher capacity to bind condensed tannin than black rhino saliva.
Whereas results for white and black rhinos are as expected, the high condensed tanninbinding capacity of Indian rhino saliva is surprising. In evolutionary terms, the Indian rhino possibly adapted to a grass diet later than the white rhino, and the high salivary TBP might be an evolutionary leftover from relatively recent times when browse was a larger constituent of the Indian rhino’s diet.
This study was partly supported by a grant of the International Rhino Foundation and SOS Rhino to MC.

Induction of salivary tannin-binding proteins in captive black rhinoceros (Diceros bicornis) by dietary tannins

M. Clauss1, J. Gehrke2, J. Fickel2, M. Lechner-Doll2, E.J. Flach3, E.S. Dierenfeld4, J.-M. Hatt5

1Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Germany
2Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany
3Institute of Zoology, Whipsnade Wild Animal Park, Bedfordshire, UK
4Nutrition Department, Wildlife Conservation Society, New York, USA
5Divison of Zoo Animals and Exotic Pets, Zurich, Switzerland

In some rodents and in goats, it has been demonstrated that salivary tannin-binding proteins (TBP) can be increased by dietary tannin levels, whereas dietary levels in browsing ruminants cannot influenced their concentration. Although the black rhinoceros is a strict browser and tannins have been found in its natural diet, potential seasonal shifts in dietary tannin concentrations have not been investigated to date. If such shifts are hypothesized, these animals would benefit from a tunable mechanism to produce TBP.
Six black rhinos from three different zoological institutions were sampled for this study. Each feeding period lasted for three months. Animals received their regular zoo diet, or the same diet with an addition of 5 % tannic acid (hydrolysable tannin) or quebracho (condensed tannin) to the pelleted ingredient of their diet. Saliva samples were analysed by tannin binding assay, using tannic acid and quebracho as standards.
There was a significant increase in tannic acid-binding capacity both after tannic acid and after quebracho feeding. Tannic acid feeding did not increase quebracho-binding capacity. After quebracho feeding, there was a trend of increased quebracho-binding capacity, however this was not significant.
The results indicate that the black rhinos investigated increased their production of salivary TBP in response to increased levels of dietary tannins. The fact that TBP capable to bind hydrolyzable tannin were more responsive to dietary stimulation could indicate that hydrolyzable tannins play a greater role in the black rhino’s natural environment than condensed tannins.
This study was partly supported by a grant of the International Rhino Foundation and SOS Rhino to MC.

Salivary tannin-binding proteins are not affected by mid-term feeding history in captive roe deer (Capreolus capreolus)

J. Gehrke1, J. Fickel1, M. Lechner-Doll1, K. Lason1, M. Clauss2

1Institute of Zoo Biology and Wildlife Research (IZW) Berlin, Germany
2Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Germany

Whereas in some monogastric rodents, salivary tannin-binding proteins (TBP) have been shown to vary according to dietary induction, there has been contradictory evidence among ruminant species: deer showed no increase after tannin feeding, but goats did. In order to test whether the constant exposure to a tannin source could influence the development of TBP in growing roe deer, we performed an experiment with eight hand-raised roe deer fawns on two different dietary regimes.
Both groups received a pelleted diet only. For eight months, the tannin group was supplemented with tannic acid as 3 % of the original feed mixture; for another two months, quebracho was added accordingly. Saliva was collected during immobilisation after both periods, and analysed for TBP by tannin binding assay. There was no difference in the salivary TBP concentration between the two groups.
As roe deer are strict browsers, the presence of salivary TBP could be part of the overall genetic makeup of the species, and this could be the case in the other deer species previously investigated. In contrast, goats, as intermediate feeders, can include different forages in their diet, and therefore should profit from the potential to adapt their salivary proteins to the type of forage actually ingested. The presence of an induction mechanism for TBP could therefore be indicative of the evolutionary feeding history of an animal species.