ESTABLISHMENT OF A ZOOLOGICAL BROWSE DATA BASE

T. L. Lehr

, M.M. Moore

, S. Williams

and *N.A. Irlbeck

l, 2

Department of Animal Sciences; Colorado State University; Fort Collins, CO

Denver Zoological Gardens; Denver, CO

*N.A. Irlbeck, Ph.D., 212A Animal Sciences, Colorado State University Fort Collins, CO, 80523

Ph. (970)491-0668 Fax (970)491-5326 E-mail ni[email protected]

Abstract

Browse, a significant source of nutrition and enrichment for captive animals, is becoming

increasingly important and more widely used. Browse includes leaves and twigs from shrubs,

trees and herbaceous plants. It is supplemented to a wide range of captive animals including

hoofstock, primates, pachyderms, marsupials and even avian species. Despite the importance of

browse as a supplemental feed and enrichment tool, little research has investigated its nutritional

value or health implications. A browse data base of nutrient content, species preference and

health concerns would be advantageous to the zoo community. This need prompted us in the

development of such a data base. Initial horticulture surveys have indicated an interest from

institutions in several states agreeing to participate in data collection. The data base will use a

standardized protocol to evaluate variability in chemical composition of browse by season,

location, propagation technique and the target animal species. One year of data (20 species) has

been collected at the Denver Zoological Gardens and sampling is continuing. Several institutions

have submitted browse samples to be included. Browse information currently in the literature will

be incorporated as possible. A working data base will provide a greater understanding of the

utilization of browse and enable zoo staff to make more efficient and informed feeding decisions.

It is thought that the data base will ultimately serve to improve the health and quality of captive

animal lives throughout zoological facilities.

Key words: browse, forage, data base, horticulture

Introduction

Browse, the shoots, twigs and leaves of trees and herbaceous shrubs, has been an integral part of

feeding certain captive wild animals (herbivores especially folivores) for years and its use seems

to be increasing. Some of the increased use stems from using browse as an enrichment factor in

attempts to decrease boredom. While browse is being fed by many zoos throughout North

America and around the world, there is limited knowledge on the nutrient composition and/or

potential concerns of specific browse species. Many zoological institutions have browse lists that

are used to determine browse supplementation to animals. The scientific literature contains some

information on browse, in fact, a recent literature search found just under a 100 published articles

related to nutrient content, species preference and browse enrichment. Many of these article are

found in relatively unknown journals or conference proceedings that are hard to obtain by most

zoo personnel. Much of the information found in these articles is inconsistent, empirical and

confounded by season and region, thus making it difficult for zoo keepers and horticulturists to

utilize. It would be advantageous to the zoo community to standardize the information that is

available on browse, in order for zoo personnel to utilize that data for better animal feeding and

care. Thus, the objective of this study is to initiate the development of a zoological browse data

base.

Methods

Surveys

In 1991, an investigation into the use of browse for captive wild animals was conducted by the

Denver Zoological Garden's (DZG) senior staff horticulturist. That investigation resulted in an

initial 1992 survey being sent to zoos throughout the United States and Canada, as a collaborative

effort between the Association of Zoological Horticulture (AZH) and Colorado State University

(CSU). Of those initial surveys sent out in 1992, twelve were returned. The results of that survey

indicated inconsistent data on browse, including the nutritional content, specific plant parts fed,

seasonal use of browse and management of the browse plants. This resulted in a more

comprehensive survey (AZH) being sent out in 1996 to those twelve institutions responding to

the first survey. These twelve institutions provided a starting point for the development of the

proposed data base.

Denver Zoological Gardens Sample Collection

In 1996, 20 species of plants, and in 1997, 21 species of plants were harvested at the DZG

(Table 1). The selection of plants was based on those commonly used as browse plants for the

zoo's herbivore collection. The samples were harvested in the spring (May), summer (July) and

fall (September) to account for seasonal change.

Harvesting of the browse samples was managed to prevent allelopathic complications. Twenty,

25 cm lengths or branches of each species of browse were collected at each harvest. After

harvest, the diameter of each branch was recorded in centimeters. Harvested samples were then

refrigerated and transported for processing to CSU .

Processing the 20 branches of each plant species involved separating the plant into leaf and stem

fractions, leaving the pedicle with the leaf fraction. Each fraction was then dried in a laboratory

oven between 50-60 degrees Centigrade for 48 hours. Upon removal from the oven, the samples

were weighed to account for the leaf:stem ratio (dry matter basis) of each plant. Each plant

fraction was then ground using a 1 mm screen in a Wiley laboratory mill.

In addition to the 20 branches collected at each harvest, two additional branches were collected

from each plant. These samples were also processed by separation into the leaf and stem

fractions. Each plant fraction was then dried at 100 degrees Centigrade for 48 hours to determine

the harvest dry matter concentration for each plant.

Laboratory Analyses

Samples of each plant fraction were analyzed (Irlbeck, 1997) for dry matter; ash content; crude

protein using the combustion method (AOAC, 1990a); detergent fiber analyses including neutral

detergent fibers (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL); and mineral

content using Inductively Coupled Plasma Emissions Spectroscopy (AOAC, 1990b) using

National Institute of Standards and Technology as standard reference material (Ca, K, Mg, Na, P,

Cu, Fe, Mn, Zn and Mo). The detergent fiber analyses (NDF, ADF and ADL) were sequentially

determined using the ANKOM method (ANKOM

200/220

Fiber Analyzer; Analytical

Instrumentation and Engineering; 140 Turk Hill Park; Fairport, NY 14450), utilizing a heat

resistant enzyme (Validase, HT 3401 Alpha-Amylase; Valley Research, Inc.; 1145 Northside

Blvd.; South Bend, IN 46615) for the NDF analyses.

Collaborating Zoological Institution Sample Collection

In 1997, the original twelve survey institutions were invited to send browse sample to CSU for

inclusion in the data base. The following protocol was developed and sent to each of the

institutions. Currently, the North Carolina Zoological Park (Table 2), the Columbus Zoo (Table

3) and the Phoenix Zoo (Table 4) have sent the first harvest of browse samples to CSU. Several

other institutions have verbally agreed to send samples and a permit to allow samples from

Calgary Zoo in Canada is pending.

The collaborating institutions were asked to contribute at least five, but no more than 20

different browse species. If the institutions were feeding similar browse to what is being analyzed

for the DZG, they were encouraged to send those to help account for regional differences in

nutrient content among these species. The identical harvesting techniques used in Denver were

sent to the collaborating institutions. The 20, 25 cm branches (Sample A) from each browse

species (intact with no separation of leaf and stem) were to be enclosed in a paper grocery bag,

each species having its own bag. The institutions were not responsible for separation of the plant

fractions (leaf and stem). These bags were to be marked with the following information: 1)

Sample A; 2) name of institution; 3) name of the browse species; and 4) harvest date. The second

sample of 2, 25 cm branches (Sample B) was to be enclosed in a ziploc bag to prevent water loss.

The Sample B bags were similarly marked as the Sample A bags. Both samples were to be

harvested on the same day and refrigerated until shipping. Samples were to be shipped no later

than the morning of the next day by overnight Air Express to CSU. It was requested that samples

were harvested and shipped early in the week to prevent deterioration of samples. Upon arrival at

CSU, the samples were processed and analyzed in the same manner as the browse samples from

the DZG.

The collaborating zoological institutions have already submitted information regarding the use

of shipped browse samples in the AZH survey. The information included in the survey includes

animal species the browse is fed to, time of year browse cuttings are made, the form browse is

fed in and any positive or adverse reactions observed due to the browse.

Development of the Data Base

Currently, a graduate student at CSU is working on preparing and inputting browse data into a

computerized data base (Microsoft Access -Version 7, Windows 95). The information that is

compiled from nutrient analyses of browse and corresponding surveys will be incorporated into

the data base. Compatible data from the literature will incorporated as possible with citations

being indicated. The final project will include common plant names, scientific plant name,

nutrient content based on harvest time and region, potential concerns (for example secondary

compounds) when feeding a browse, animal species that can and cannot be fed a specific browse

and the source of literature as it applies. Information from the data base will be accessible by

either plant name, region, secondary compounds found in browse species and animal species that

browse can be fed or not fed to.

Results

The browse survey sent out in 1996, will be reformatted and sent out again to all AZH-

associated institutions within the next two years.

The results of the nutritional analyses of the 1996 browse samples collected from the DZG will

be published in a corresponding journal in the near future (Irlbeck, 1997), as will the browse

sample from collaborating institutions.

The browse data base itself will be presented at future captive wild animal and AZH

conferences, along with submission to a nutrition-related journal.

Discussion

The importance of this browse data base is undeniable. There are several issues being addressed

by the data base that will ultimately enable zoo personnel to more safely feed browse to captive

wild animals. These issues include: 1) nutritional variation of the browse based on season,

location and year; 2) animal preferences; 3) concerns of secondary compounds such as alkaloids,

tannins and phenolics; and 4) management concerns for animal and browse species.

The benefits of browse seem obvious as it supplements the animal's diet with additional nutrients

and fiber. Therefore, the days of just adding a little browse in an exhibit may be limited. We need

to have some idea of what we are feeding these animals. Despite the significant amount of

research done on the nutritional content of various browse species, the nutrient content of most

browse species is still relatively unknown. It is hoped that the data base can be utilized in some

cases to find an acceptable substitute for an animal's natural browse. For example, one study

stated that the natural browse of South-East Asian Colobines (Presbyts rubicunda and

melalophos) contained 43.7-66.7% NDF, 30.5-52.3% ADF and 14.4-28.3% lignin. The fiber

analyses of diets fed to these same species in European zoos only analyzed to 32.2% NDF, 17.7%

ADF and 3.9% lignin (Nijboer and Dierenfeld, 1995). A subtle change in fiber content like this

could potentially compromise the gastrointestinal tract and health of these animals. This is only

one example and there are a myriad of other species that this can be applied to. Therefore, the use

of the data base could assist in finding a more comparable fiber source for various endangered

species.

As indicated in the previous paragraph, when feeding captive wild animals, the natural diet is

the first key in determining what the animals should be fed. Browse as a source of fiber alone can

be an important integral of the animal's diet, especially if the animal is an herbivore. When

feeding an herbivore, complications will arise if inadequate amounts (too much or not enough) of

fiber are fed. Complications that could arise are obesity (fiber, thus browse is lower in caloric

content and gives a feeling of satiety) and disruption of normal digestive function such as

diarrhea, bloat, impaction, torsion, acidosis, pathogenic infections, lumpy jaw and dental

concerns (Church, 1988; Barboza and Hume, 1989; Hume and Barboza, 1993). For many species

of animals, it is essential that the "right" form of fiber is fed. For example, in 1964, Hill

documented that 50% of langur mortality was directly attributed to gastrointestinal problems as a

direct result of diet. Also, in 1984, Clemons presented data insinuating that 40% of herbivore

deaths were due to acute or chronic gastrointestinal concerns. It is apparent that browse, and

particularly what type of browse is fed to an animal will affect its health and well-being.

It has been documented in the domestic animal literature for years that the environment the plant

is grown, thus seasonal effects will affect the nutritive quality of a browse sample. Also, the

maturity of the plant will affect nutritional quality and its availability to the animals. In general,

the hotter the environment (usually later in the season), the amount of lignin and cellulose will

increase. Plants grown in more temperate (cool and moist) environments will have less lignin.

Therefore, plants harvested in the early or later part of a season, will generally be of higher

nutritive value (Baker and Hobbs, 1982; Ha1l-Martin et al., 1982; Hobbs et al., 1981). This can,

however, also be changed by the maturity of the plant. In general, the more mature the plant, the

lower the nutritive value because of an increase in lignin and cellulose (Church, 1988; Van Soest,

1982). It should also be addressed, that since different areas of the country and world will have

different environments, the nutritive value will change with different regions. Likewise, the

environment is never the same from year to the next, thus, there is a change in nutrient quality

due to year alone. This just provides all the more impetus to add as many years’ data from as

many regions as possible to increase the validity of the data base values.

While observing animals being fed browse at the Denver Zoological Gardens and reading the

results of the horticulture survey, it is obvious that animals have preferences for certain types of

browse. Being aware of these preferences and feeding those browse types, if at all possible, can

serve to ease the management of these animals. Some of these preferences may be due to

secondary compounds found in some browse, some of which are potentially dangerous (Baer,

1989; Gardner et al., 1985). A few of the secondary compounds found in plants include tannins,

phenolics and alkaloids. It has been documented that animals select browse components based on

the content of secondary compounds. For example, the koala (Phascolarctos cinerus) has adapted

to Eucalyptus forage which contains volatile oils. These oils can be dangerous and are believed to

influence selection of the leaves by the koala (Barboza and Hume, 1989). Other research suggests

that the South Indian Leaf-Monkey (Presbytis johnii) and other colobines, may be able to

detoxify some alkaloids found in some browse species and select their browse components based

on low tannin content (Oates et al., 1980). Recently in 1995, two zebra (Equus grevyi) were

found to be suffering from the symptoms of Red Maple (Acer rubrum) Toxicosis (Weber and

Miller, 1997). Both animals were treated for hemolytic anemia, however, the older animal still

died. The first case of hemolytic anemia from Red Maple leaves in horses was documented in

1981, but this was the first case documented in another equid, the zebra. The irony of this case

was that the animals had been held in this enclosure with the trees for over 15 years and this was

the first time it had been a concern. Obviously a specific change in the environment resulted in

the death of an animal.

Management of browse itself has its own challenges. Some plants when consistently harvested

either by insects, animals or by man will produce secondary compounds to deter that behavior. In

fact, some plants will produce chemicals to prevent other species of plants from growing in the

same area, thus preventing competition from another species. This is called allelopathy (Gardner,

1985). One example of allelopathy occurred in the last few years at the DZG. In this incident,

native grasses were planted in from of a hoofstock exhibit. Between the rabbits and the peacocks,

the plants were leveled to a height of a few inches for the fIrst year. The next year, the plants

grew several feet in height as no animal would graze it, most likely from an allelopathic response

(Moore, 1997). This same phenomena may occur if browse samples are collected from the same

plant repeatedly in the same season. The plant, with its chemical defenses may prevent animals

from consuming the browse, perhaps explaining why animals will eat a browse one time and not

another. Thus, the harvesting of browse needs to be done on a rotational basis. Information on the

production of these secondary compounds can be of benefits to zoo personnel, both plant and

animal staff.

Challenges

There are three major concerns challenging this project. They include: 1) information

distribution; 2) funding; and 3) the need for a substantial amount of labor. The decision still

needs to be made on how to distribute the information from the data base, so that it can be best

used by the captive wild animal community .The two options seem to be: 1) to market the

information and use the profits to fund further research; or 2) provide the information as a

service, potentially making it available on the Internet. Obviously, this is a decision that will need

to be made in the near future. Laboratory analyses of the browse samples is expensive both from

a monetary form and in labor. Funding sources are essential to meet the needs of this project.

Initial funding for the analyses has been provided by the DZG, but new sources are needed. Also,

the amount of labor needed to accumulate this information is tremendous. Browse samples need

to be harvested, processed, analyzed and the resulting information entered into the data base. It is

hoped that these issues will be resolved soon.

Future Implications

The use of Near Infrared Spectrophotometry (NIR) is used extensively in forage and grain

analyses for captive wild and domestic animals alike. It offers a quick and inexpensive way to

determine the nutrient analyses of a feed prior to being fed to animals. To date, however, NIR

cannot be used for browse nutrient analyses as the equations needed to calibrate the NIR are not

available. To adequately develop these equations, thousands of laboratory analyses on browse

samples need to be completed. The results of these analyses can be used to develop the equations,

the NIR can be calibrated and then used for browse nutrient analyses. From a recent grant, a NIR

is available at CSU and the laboratory analyses accumulated thus far are being used in the initial

stages of calibrating the machine. It is planned in the future that a NIR can be used for browse

analyses anywhere in the world.

It is also planned that the browse data base will take on an International aspect. The permits are

being processed to obtain the browse samples from Canada. Plans have been made to bring

browse samples back from Australia in the Fall of 1998.

Conclusions

A standardized browse data base would benefit captive wild animals by providing information

on: 1) nutrient content of browse species as affected by season, region and plant maturity; 2)

protection from concerns of secondary compounds that could elicit toxic responses; and 3)

cultivation and harvesting techniques for the browse species to be safely fed.

Acknowledgments

The authors would like to thank the following individuals for their efforts and support: I) Dr.

Richard P. Reading, Director of the Department of Conservation Biology, Denver Zoological

Gardens for the initial funding for this project; 2) Virginia Wall for her efforts in harvesting and

forwarding samples from the North Carolina Zoological Park; 3) Steve Belcher for his efforts in

harvesting and forwarding samples from the Columbus Zoo; and 4) Mark Fleming, Wendy

Haughey and Cesar Cordova for their efforts in harvesting and forwarding samples from the

Phoenix Zoo. Thank you.

References

Association of Official Analytical Chemists. OFFICIAL METHODS OF ANALYSES

(PROTEIN [CRUDE] IN ANIMAL FEED: COMBUSTION METHOD -990.03). 15th

Edition. 1990a.

Association of Official Analytical Chemists. INDUCTIVELY COUPLED PLASMA

EMISSIONS SPECTROSCOPIC METHOD -985.01. 15th Edition. 1990b.

Baker, D.L. and Hobbs, N.T. Composition and quality of elk summer diets in Colorado.

JOURNAL OF WILDLIFE MANAGEMENT 46(3):694- 703. 1982.

Baer, D.J. Toxins in plant and animal products. PROCEEDINGS EIGHTH DR. SCROLL

CONFERENCE ON THE NU1RITION OF CAPTIVE WILD ANIMALS. Lincoln Park

Zoological Society. Chicago, IL 1989.

Barboza, P .S. and Hume, I.D. Designing Diets for Herbivorous Marsupials. PROCEEDINGS

EIGHTH DR. SCROLL CONFERENCE ON THE NUTRITION OF CAPTIVE WILD

ANIMALS. Lincoln Park Zoological Society. Chicago, IL 1989.

Church, D.C. (Editor). THE RUMINANT ANIMAL -DIGESTIVE PHYSIOLOGY AND

NUTRITION. Prentice Hall; Englewood Cliffs, NJ 1988.

Clemons, E. T .Gastrointestinal Disorders of Adult Zoo Mammals. PROCEEDINGS FOURTH

DR. SCROLL CONFERENCE ON THE NUTRITION OF CAPTIVE WILD ANIMALS.

Lincoln Park Zoological Society. Chicago, IL 1984.

Gardner, F.P., Pearce, R.B. and Mitchell, R.L. PHYSIOLOGY OF CROP PLANTS. Iowa State

University Press. Ames, IA 1985.

Hall-Martin, A.J., Erasmus, T. and Botha, B.P. Seasonal variation of diet and faeces composition

of black rhinoceros (Dicoros bicornis) in the Addo Elephant National Park. KOEDOE 25:63-

82. 1982.

Hill, W.C.O. The maintenance of langurs (Colobidae) in captivity: Experiences and some

suggestions. FOLIA PRIMATOLOGY 2:222-231. 1964.

Hobbs, N.T., Baker, D.L., Ellis, J.E. and Swift, D.M. Composition and quality of elk winter diets

in Colorado. JOURNAL OF WILDLIFE MANAGEMENT 45(1):156-171. 1981.

Hume, I.D. and Barboza, P.S. Designing artificial diets for captive marsupials. ZOO AND

WILDLIFE MEDICINE -CURRENT THERAPY 3. PP.281-288 W.B. Sanders Company,

London. 1993.

Irlbeck, N.A. UNPUBLISHED DATA. Colorado State University, Fort Collins CO 1997. Moore,

M.M. PERSONAL COMMUNICATION. Senior Staff Horticulturist, Denver Zoological

Gardens, Denver CO 1997.

Nijboer, J. and Dierenfeld, E.S. Comparison of diets fed to South-East Asian Colobines in North

America and European zoos versus natural diets. Abstract PROCEEDINGS FIRST

CONFERENCE NUTRITION ADVISORY GROUP. University of Guelph. 1995.

Oates, J.F., Waterman, P.G. and Choo, G.M. Food selection by the South Indian Leaf-Monkey,

Presbytis johnii, in relation to leaf chemistry .OECOLOGIA, 45:45-56. 1980.

Van Soest, P.J. NUTRITIONAL ECOLOGY OF THE RUMINANT. O & B Books, Inc.;

Corvallis OR. 1982.

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Table 2. Plant species collected from North Carolina Zoological Park in 1997

for nutrient analyses

determination in the development of a browse data base.

Common Name Scientific Name

Areca Palm Chrysalidocarpus luctescens

Autumn Olive Elaeagnus umbrellata

Black Bamboo Phyllostachys nigra

Black Willow Salix nigra

Bamboo Phyllostachys aureosulcata

Canna Canna X generalis

Dwarf Banana Musa acuminata

Giant Reed Grass Arundo donax

Honeylocust Gleditsia triacanthos

Red Maple Acer rubrum

Thorny Elaeagnus Elaeagnus pungens

Wax Myrtle Myrica cerifera

Weeping Fig Ficus benjamina

Winged Elm Ulmos alata

1One harvest has been collected and the second is pending seasonal changes.

Table 3. Plant species collected from the Columbus Zoo in 1997

for nutrient analyses determination in

the development of a browse data base.

Common Name

Scientific Name

Bailey's Red Twig Dogwood Comus sericia 'Baileyi’

Common Hackberry Celtis occidentalis

Crabapple Malus cv.

Honeylocust Gleditsia triacanthos var. inermis cvs.

Pennsylvania Ash Fraxinus Pennsylvanica

Willowwood Viburnum Viburnum X rhytidophylloides ‘Willowwood’

Yellow Twig Dogwood Comus serica 'Flaviramea’

1.One harvest has been collected and the second is pending seasonal changes.

Table 4. Plant species collected from the Phoenix Zoo in 1997

for nutrient analyses determination in the

development of a browse data base.

Common Name Scientific Name

Four-winged Saltbrush Atriplex canescens

Honeylocust Gleditisa triacanthos v. inermis

Horsetail Tree/She Oak Casuarina equisethifolia

African Sumac

Rhus lancea

Sissoo Dahlbergia sissoo

Bottle Tree Brachychiton populne.s

Yellow Trumpet Flower Tecoma stan.s. cv. 'Jubilee'

Carob

Ceratonia siliqua

One harvest has been collected and the second is pending seasonal changes.