B. Kiefer1*, U. Gansloßer2 and E. Kienzle 1

1Institute of Physiology, Physiological Chemistry and Animal Nutrition, Faculty of Veterinary Science, Ludwig-Maximilian-University, Munich, Veterinärstr. 13, D-80539 München, Germany; 2Zoological Institute I, Friedrich-Alexander-University of Erlangen-Nürnberg, Staudtstr.5, D-91058 Erlangen

Within the framework of a study on behavioural ecology and resource use in white rhinos, a study on nutrition of both free-ranging and captive white rhinos was conducted. This project about the quality and digestibility of white rhino food comprises two parts. The field study was conducted on a private game farm in South Africa where a healthy population of 65 white rhinos lives in an area of 30 000 ha.

By following the tracks of individual rhinos, together with an experienced game tracker, samples of grass were collected from feeding sites. The grass species were identified and an equivalent to the amount consumed by the individual was cut and collected. Owing to the mean retention time of ingesta we tracked the same animal two days later to get a faecal sample. Two grass and faecal samples from each of three males were collected by tracking them individually. The second part of the project was an experimental study with a group of five white rhinos in the zoo of Erfurt in Germany. The rhinos (one male, four females) were fed with four different diets. Each diet was given for a period of 15 days in the following order: grass only, grass with pellets (Pachyderm supplementary diet from Mazuri Zoo Foods), hay only, and hay with pellets. Together with the pellets a certain amount of the marker Cr2O3 was fed to the animals. Samples of each diet were collected daily. Faecal samples were collected every morning during the last ten days of each 15-day period. These samples were then pooled for each of the four periods. During the study the captive animals’ behaviour was observed using scan and focus sampling methods in order to analyse the potential influence of food quality on the activity and social behaviour. The following parameters were determined in the food and faecal samples of both studies: By Weender Analysis:

  • dry matter, ash, crude protein, crude oil, crude fibre, nitrogen free extractions
    Analysis of cell wall constituents by Van Soest detergent tests:

  • total cell wall contents (NDF), lignocellulose fraction (ADF), lignin (ADL), hemicellulose (NDFADF), cellulose (ADF-ADL)

  • various minerals (phosphorous, calcium, etc.)

  • gross energy (calorimeter)

  • Cr2O3

  • Digestibility: The apparent digestibility is defined as the difference between the nutrient intake and the nutrient output expressed as a percentage of the nutrient intake. In this project it was generally not possible to collect the total forage intake or the total faecal output per animal. Owing to that it is necessary to determine the apparent digestibility indirectly with a marker. This marker must be a substance which passes the digestive tract without being changed or absorbed, e.g. lignin or chromic oxide. In this study the natural marker lignin – a part of all grasses – was used if only one type of food was given. In the two feeding periods with two different types of food (grass with pellets or hay with pellets) the double marker method with lignin and chromium oxide was used. The aim of the project is to compare the results of the field study and the experimental feeding trial in order to valuate similarities and differences of food quality and digestibility in detail. The results will help to improve the husbandry of captive rhinos.


    T. Woodfine1* & G. Matipano2

    1 Marwell Preservation Trust, Colden Common, Winchester, Hampshire, S021 1JH, UK; 2 Department of National Parks & Wildlife Management, PO Box CY140, Causeway, Harare, Zimbabwe.

    Principal browse species consumed by black rhinoceros Diceros bicornis in Matusodona National Park were analysed as part of a habitat assessment and study aimed at understanding nutritional aspects of translocating animals within Zimbabwe. Information derived from this work emphasising seasonal variations in the nutritional composition of browse, which may be of interest to managers of captive Diceros is presented. Potential differences between wild and captive diet composition are highlighted by comparing browse analyses with the nutritional content of black rhino diet at a UK zoological park.


    J. Hummel1,2* and L. Kolter1

    1Cologne Zoo; 2Institute of Animal Nutrition/University of Bonn

    Feeding of many browsing ruminants still poses some challenge to the holding facilities. There is an ongoing discussion to what extent this type of ruminant is able to digest fiber. Digestibility depends on the time the food stays in the fermenting chambers of an animal. Although there has been already some research on okapi nutrition and digestive physiology, important data like passage rates are still lacking from this mid-sized browser. In this project nutritional data (passage rate; feed intake, digestibility) and ethological data (activity budget) were collected to get an extensive picture of okapi digestive physiology. As a preliminary report of this ongoing study, data on passage rates and related data are presented.

    Passage rates of 2 adult male okapis (weight app. 200 and 240 kg) were measured. They were determined by using cobalt-EDTA as marker for the fluid phase and chromium mordanted fibers as particle phase marker (particle size of marker fibers <2 mm). Faecal samples for passage rates were collected over 10 days, the use of a time lapse video recorder allowed the determination of the exact time of faecal production during the night. Marker excretion curves and mean retention times (MRT) were calculated by assuming the formula of Grovum and Williams (1973) as a suitable model and by performing nonlinear regression of the measured marker concentrations. Titanium oxide (TiO2) was used as a marker for faecal output. Dry matter intake of the animals was 3,15 kg (animal A) and 3,90 kg (animal B) per day. Dry matter digestibility was 68% (A) and 71% (B), NDF-digestibility with 46% (A) and 48% (B) was rather low. Animal B consumed a diet with a higher proportion of grain based concentrate. Calculated mean retention times were 34,9 h (A) and 33,0 h (B) for the fluid phase and 48,6 h (A) and 46,6 h (B) for the particle phase. Selectivity factors of the whole gut (MRT particle phase / MRT fluid phase) were 1,39 (A) and 1,41 (B).
    Reference: Grovum, W. L.; Williams, V. J. (1973): Rate of passage of digesta in sheep. 4. Passage of marker through the alimentary tract and the biological relevance of rate-constants derived from the changes in concentration of marker in faeces. British Journal of Nutrition 30, 313- 329.


    Plowman* and I. Turner

    Paignton Zoo Environmental Park, Totnes Road, Paignton, Devon TQ4 7EU

    Provision of browse has potential nutritional and behavioural benefits for many zoo animals species; for some it may even be an essential component of proper nutrition. However, browse supply is often limited, particularly in city zoos and during winter in temperate regions. This limitation is ften exacerbated by lack of knowledge of which types of browse are suitable for use with which animals and fear of toxic effects. This can result in zoos being restricted to only a very few browse species which are known to be safe. To address this problem a database of browse use for mammals within Federation member zoos has been compiled by the Research Group and the Plant Group of the Federation of Zoological Gardens of Great Britain and Ireland. A questionnaire was sent to all member zoos to request information on which browse species they provide for which mammal species. Additional information such as restrictions on parts of the plant used, seasons when used, quantities used, any adverse effects resulting from use etc. was also requested. A Microsoft Access database has been compiled with the information from this survey. It can be searched by plant or animal name and returns the number of zoos which have provided a particular plant for a particular mammal without any adverse effects. The database can also be searched for adverse effects and full information about every plant/animal/zoo combination can be accessed. The database does not make browse recommendations, but allows zoo staff to see how many other zoos use a particular plant species and for which mammals, and thus enables them to make better judgements as to its likely safety. The database holds approximately 2000 records and includes 113 different plant taxa. The average number of plant taxa used as browse in a zoo is 18, with a maximum of 42. Therefore, by reference to the database, all zoos should be able to considerably increase the range of browse species they use. The database is available on CD-ROM from the Federation of Zoological Gardens of Great Britain and Ireland. Also included on the CD-ROM is a web-interactive directory of poison plant information combining all records from several web-based poisonous plants databases. This allows quick and easy access to all relevant toxicity information available for several hundred plant species. The CD will thus be an invaluable tool for all zoos needing to review their browse provision for mammals.


    J-M. Hatt1* and M. Clauss2

    1Zurich Zoo and Division of Zoo Animals and Exotic Pets, University of Zurich, Winterthurerstrasse
    260, CH – 8057 Zurich; 2Institute of Animal Physiology, Physiological Chemistry and Animal
    Nutrition, Ludwig-Maximilians-University, D-80539 Munich

    A major challenge in zoo animal nutrition is the adequate feeding of browsers, such as certain
    antelopes, giraffes (Giraffa camelopardalis), moose (Alces alces) or black rhinos (Diceros bicornis). The supplementation of browse in these species has been recognised to constitute an important factor
    in the feeding of these species. Whereas in spring and summer it is fairly easy to provide adequate
    browse, during winter months when browse is scarce, diets of theses species may become unbalanced.

    As substitutes zoos may recur to feeding alternative feedstuffs such as apple pomace or may freeze browse during the summer months, which can be offered in the winter. However, these methods are cost and energy intensive and may require large storing capacities which often are not available. A practical alternative is the production of browse silage, which is cheap and easy to produce. At Zurich Zoo this method has successfully been applied for five years. In late spring as much available browse as possible (diameter up to 3 cm) is processed in a chaffcutter. Subsequently the browse is tightly filled into plastic containers (Volume 200 l) which are closed airtight and stored at temperatures not higher than 20°C. No additives are added to the browse. Currently approximately 1200 kg of browse silage is produced annually with this method. From November onwards the silage is fed to four black rhinoceros (Diceros bicornis) on a daily basis. Chemical analysis of the browse before and after silage process shows no significant alteration in composition (Table 1). The silage is very popular in black rhinoceros and represents an excellent enrichment of the diet. Furthermore it provides the animals with a variety of secondary plant compounds such as lignin or tannins which are naturally ingested by browsers in the wild and may contribute to their adequate digestion.

    Table 1: Chemical analysis of browse (willow and maple) before and after silage process
    Before* After*
    Dry matter % 47.8 46.8
    Organic matter %DM 96.4 96.2
    Crude protein % DM 4.9 5.3
    Crude fat % DM 1.0 1.3
    Crude ash % DM 3.6 3.8
    Crude fibre % DM 51.6 53.2
    ADF % DM 60.1 63.7
    Lignin % DM 14.7 16.6
    Cellulose % DM 45.4 47.1
    Gross energy MJ/kg DM 18.8 19.0
    Calcium % 0.9 0.9
    Phosphorus % 0.1 0.1
    * Differences between data in columns are not significant