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BLACK RHINOCEROS (Diceros bicornis)




Veterinary Section (Pages  )

Michele Miller, DVM, PhD

Veterinary Advisor

Black Rhinoceros Species Survival Plan


Nutrition Section (Pages  )

Ellen Dierenfeld, PhD

Nutritional Advisor

Black Rhinoceros Species Survival Plan

And Rhinoceros Taxon Advisory Group





A new veterinary advisor (Dr. Michele Miller, Disney’s Animal Kingdom) has been appointed by the black rhinoceros SSP. Dr. Michele Miller can be contacted at Disney’s Animal Kingdom, P.O. Box 10,000, Lake Buena Vista, FL  32830-1000; phone (407) 939-7316; e-mail:


Dr. Eric Miller will continue to serve as the veterinary advisor to the rhinoceros TAG.  Dr. Miller’s significant contributions as the veterinary advisor through the years have resulted in the accumulation of a large body of medical knowledge and research involving this species.


Revision of “Rhinoceros Blood and Tissue Collection Protocol”

The revision is an ongoing project and will hopefully be completed this year.  Those researchers interested in materials for TAG-approved research projects should contact the veterinary advisor with any updates.  The new protocol will be distributed to all institutions holding black rhinoceros and provide up-to-date sample and contact information for the research projects.


Pathology Advisor for Black Rhinoceros

Please contact Dr. Mary Duncan at the Saint Louis Zoo in the event of a black rhinoceros mortality.  A duplicate set of H&E slides or formalinized tissue should be submitted to her.  A copy of the SSP necropsy protocol is available on the AAZV website.



Annual vaccination with 5-way (? or 6-way) leptospiral vaccine continues to be recommended.


West Nile Virus

With the rapid spread of West Nile Virus across the country in 2002, a number of veterinarians have inquired about vaccinating rhinoceros.  To date, seroconversion (titer 1:640) has only been documented in one black rhinoceros that died from unrelated causes.  Serum or heparinized plasma samples from several institutions have been submitted to Cornell University as part of the WNV Surveillance Program for Zoos.  Results are pending.


Without documented morbidity or mortality associated with WNV infection in black rhinoceros, the risk of infection and disease is unknown.  WNV vaccination is not recommended at this time.  However, an informal survey of institutions holding black rhinoceros was used to determine if any animals were being vaccinated and possible adverse effects.  The following summary is based on responses from 21 institutions:

q       5 institutions have vaccinated black rhinoceros; 14 have not as of the time of the survey; 2 are planning to vaccinate

q       3 institutions used 1 ml IM (same as recommended equine dose); 2 used 2 mls IM

q       2 initial vaccinations were administered 2-4 weeks apart

q       3 institutions plan to booster annually; the others have not determined the revaccination schedule

q       No adverse reactions were reported.

q       1 institution has measured titer post-vaccination (results are pending); 1 other plans on measuring titers

q       A total of 17+ black rhinos have been vaccinated; approximately 29 have not (only those answering were included)

q       4 institutions report vaccinating other rhino species (white, Asian one-horned)

It is strongly recommended that both vaccinated and nonvaccinated rhinos have titers measured opportunistically.  Serologic results in domestic horses use plaque reduction neutralization testing (PRNT) to determine titers.  Vaccination with 2 doses elicited antibody titers >1:5 (1:5-1:1280) at approximately 2-3 weeks post second vaccination.  Preliminary results of the first efficacy trial appear favorable.  Protective titers in other species have not been determined.


Iron Overload in Black Rhinos

The following excerpt is a summary of recent observations from Dr. Don Paglia on iron overload in this species.




Chris Foggin recently sent necropsy tissues from a female black rhino, Checha, that had been hand-reared at Chipangali Wildlife Orphanage in Zimbabwe under conditions comparable to those in U.S. zoos.  She had a lifelong history of poor nutrition, shunning browse and consuming mostly fabricated horse pellets.  Even though she was only 9 years old, histopath showed her to be heavily overloaded with iron, comparable to the most severe cases that I have necropsied or reviewed among U.S. captive black rhinos, including several three-to-four times her age.  The liver was so severely affected that micronodular cirrhosis had already developed, (usually a late-stage complication affecting only a few of the very eldest in the U.S. population.)  Iron deposits were also present within the cardiac myocytes to an extent well beyond any I’ve seen previously, (except for Fossil Rim’s leukemic calf, “Echo” [S.B. No. 573], who was treated with a cardiotoxic drug.  Ref:  Paglia DE & Radcliffe RW.  Vet Pathol 37:86-88, 2000.) 


We have previously reviewed necropsy materials from another Chipangali black rhino, Thunder, that also showed histopath evidence of increased hepatic iron which measured 1,765 ppm by quantitative assay.  Thunder was only 22 months old at the time of death, a remarkably short period in which to acquire tissue iron stores of such magnitude.  By contrast, another black rhino, Tsupa, living under more natural conditions in Malilangwe Conservancy, had an hepatic iron concentration of only 26 ppm. 


Checka and Thunder might well represent 2- and 9-year extrapolations from the cases originally reported by Nancy Kock et al. (J Zoo Wildlife Med 23:230-234, 1992), which showed progressive histopath evidence of iron accumulation following capture and boma confinement from a few weeks up to 2 years.  These two rhinos demonstrate how rapidly severe iron overloads can develop in this species under captive conditions, a phenomenon that I don’t believe we had fully appreciated before.  In addition, these observations add support to the hypothesis that iron accumulation is a consequence of essential differences between self-selected native forage and captive diets, such as the absence of certain natural chelators of dietary iron. 


Checka, incidentally, also had hematological, biochemical, and histopath evidence of both acute and chronic hemolysis.  So, contrary to widespread opinion, hemolytic anemia apparently has occurred in black rhinos living in Africa, but (most importantly) in an animal living under the restrictions of captivity. 


Japan and Australia


Some fragmentary data from black rhinos in Japan and Australia suggest that further studies of these populations would also be very important to understanding iron homeostasis in this species.


(1)       Satsuki (S.B. No. 560), born at the Hiroshima Zoo, was transferred to Honolulu Zoo 3 years ago when she was 4 years old.  At that time we measured entirely normal serum iron and transferrin saturation, in contrast to the significantly (as much as tenfold) elevated values we have found in juveniles of comparable age born in U.S. zoos.  If follow-up specimens can be obtained, they should be illuminating, regardless of whether iron values remain normal or increased.


(2)       Review of necropsy slides obtained by Nan Schaffer from a 2-year-old black rhino at Hiroshima Zoo (Lona, S.B. No. 445, a sibling of Satsuki) also showed normal iron stores by histopathology. 


(3)       Similarly, sera from Kusamona, a 5½-year-old male born and raised at Western Plains in Australia, showed low normal iron concentrations and transferrin saturations when he was moved to Fossil Rim at the end of October.  Since then, a disturbing trend has emerged as shown by the following table.


             Date             Serum Iron           Transferrin Saturation           Serum Ferritin         

         10/29/01          31, 79 mg/dl                       10, 25 %                 1,641; 1,629 ng/ml

         12/05/01                140                                  50                                    968

         12/10/01                  97                                  47                                  3,041

           4/02/02                229                                  64                               (pending)


In only 5 months, the iron and transferrin saturation values reached the elevated means for the U.S. black rhino population at large, (231 mg/dl and 65%), and ferritin concentrations now exceed the mean for captive-born juveniles (1,210 ng/ml).  (Note:  Since ferritin is an acute-phase reactant that can be induced by stress, the pre-shipment baseline value remains uncertain, but the progressive elevations in transferrin saturation alone should be viewed as a reliable indicator of developing pathology.) 


These observations suggest that black rhinos born in other countries, such as Japan and Australia, may not be developing the severe iron loads seen so commonly here in the U.S., but they may soon begin to accumulate iron when moved into U.S. zoological institutions.  Comparative studies of these populations would provide an unparalleled opportunity to test our current hypotheses on the role of diet and other environmental factors in regulation of iron balance in rhinos.


Veterinary Research Projects


1.  Project:  Epidemiological Survey of Rhinoceroses


Researcher:  Dr. Pam Dennis, The Ohio State University, College of Veterinary Medicine, Columbus, Ohio,  43210


In an effort to gain a better understanding of the underlying factors leading to reproductive and health problems in captive rhinoceros in the United States, the International Rhino Foundation has funded an advanced veterinary epidemiology training program focusing on the health of rhinoceros in captivity. This program adopts a broad, population level assessment to examine the factors limiting population growth in captive rhinoceros and to identify the risk factors associated with morbidity and mortality in these captive populations. This program is based at Ohio State University, with support from The Wilds and St. Louis Zoo. The advisory group is composed of Dr. Bill Saville, an epidemiologist in the Department of Veterinary Preventive Medicine at OSU, Dr. Eric Miller, Director of Animal Health at the Saint Louis Zoo, and Dr. Evan Blumer, research advisor for the IRF and director of The Wilds. Dr. Pam Dennis is the graduate fellow conducting the research.


A general survey was designed to gather information on the medical and husbandry status of black, white, and Greater One-Horned rhinoceros in captivity in the United States. The current focus of the study is directed towards completing the survey for all black rhino holding institutions, with the intention of visiting all facilities by the end of 2002.  Visiting each institution allows the collection of information by talking with the veterinary staff, the curators and keepers working with the animals, and the nutritionist or commissary staff. In addition, the medical and husbandry records of each animal are reviewed to gather pertinent information. The survey does not require an extensive time commitment from the institutions, typically less than an hour from the veterinary staff and husbandry staff. The success of this program is dependent on the active participation of all rhino-holding institutions. Without the support of each institution and the willingness of each institution to allow a visit from Dr. Pam Dennis, this survey cannot succeed.



2.  Project:  Phosphate Depletion in Captive Black Rhinoceros


Researchers:  Dr. Pam Dennis, Dr. Ray Ball, Dr. Bruce LeRoy, Dr. Janine Brown, Dr. Markus Hofmeyr, Harry Peachey


Black rhinoceroses in captivity suffer from many disease syndromes not seen in wild populations. Imbalances in their diet may cause captive animals to become phosphate depleted. Phosphate is essential for providing energy to cells and oxygen to tissues. Tissue hypoxia resulting from phosphate depletion may trigger the production of proteins that enhance the absorption of iron. Endogenous glucocorticoids, released during stressful events, may exacerbate the effects of phosphate depletion.  This research seeks to determine whether captive black rhinos are phosphate depleted and to investigate the relationships of glucocorticoids, iron, and phosphate in the disease syndromes of the captive black rhino. This project was recently funded by the Columbus Zoo / Ohio State University Cooperative Grants program. We are interested in adding rhinos to our study, particularly any animals that are affected with signs of any of the

black rhino syndromes, or are experiencing epistaxis, sudden onset of lameness or shifting leg lameness, hindlimb weakness, or anemia. Please contact Dr. Pam Dennis if you are interested in this study. Contact info: Dr. Pam Dennis, Ohio State University, Dept of Vet Preventive Medicine, 1900 Coffey Road, Columbus, OH 43210 (614) 292-1206,



3.  Project:  Comparative Cell Metabolism


Researchers:  Drs. Don Paglia, UCLA School of Medicine, Hematology Research Laboratory, Los Angeles, CA  90095-1732, and Dr. Eric Harley, University of Capetown, Medical School Observatory 7925, Capetown, Republic of South Africa.




4.  Project:  Pathological Review of Black Rhinoceros Tissues


Researcher:  Dr. Mary Duncan, Saint Louis Zoo, St. Louis, MO  63110-1396


Please send duplicate sets of pathology tissues from all deaths (and a copy of any pathology reports that you receive from your pathology sources).




5.  Project:  Comparative Cell-Mediated Immune Function in Rhinoceros and Potential Relevance to Disease Susceptibility in Captive Black Rhinos


Researchers:  Terri Roth, Ph.D. and Carrie Vance, Ph.D., Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, Cincinnati, OH  45220; Suzanne Kennedy-Stoskopf, D.V.M., Ph.D. (North Carolina State University); and  Korinn Saker, D.V.M., Ph.D. (Virginia-Maryland Regional College of Veterinary Medicine).



This study has been completed and manuscripts are in preparation.  The following is a summary of some of the results.


Hypothesis: Captive black rhinoceros experience immune dysfunction not observed in captive white rhinoceros.  Objectives: Compare immune function in black and white rhinoceros.  Blood was obtained from 10 black and 10 white rhinos.  Criteria for inclusion in the study were animals that had been conditioned to stand for blood collection without sedation.  Participating institutions were Milwaukee Zoo, Fort Worth Zoo, White Oak Conservation Center, Fossil Rim, and Disney Animal Kingdom.  


Each investigator used different techniques to evaluate some aspect of the immune system. The results are mutually supportive and suggest that black rhinoceros have an impaired ability to manage infections efficiently.  The findings are consistent with the opportunistic infections seen in this species and may provide insight into pathogenesis of mucocutaneous ulcerative disease and idiopathic hemorrhagic vasculopathy.


Dr. Saker’s data suggests that specific innate immune cell function is impaired in the black rhinoceros compared to the white rhinoceros.  Phagocytosis, a crucial first step in the uptake of infectious agents by neutrophils and monocytes/macrophages, is decreased in the black rhinoceros studied.  Respiratory burst, an indirect measure for intracellular killing, is also decreased in the black rhinoceros studied. White blood cell and RBC GPx activity was significantly lower in the black rhino group compared to the white rhinos.


Drs. Roth and Vance elected to test an Aspergillus filtrate in an antigen specific lymphoproliferative assay because of the high incidence of mortalities in black rhinoceros from Aspergillus pneumonia.  They tested several different concentrations of the filtrate, which is appropriate and necessary to determine optimal threshold concentrations, and demonstrated an increased response in white rhinoceros at the highest antigen concentration.  This suggests that black rhinoceros are immunocompromised because they are unable to mount a lymphoproliferative response to the same antigen preparation.


Cytokines are proteins and glycoproteins that modulate immune responses. .  For this investigation, constitutive mRNA expression was measured for IL 6, 12, and 10. Interleukin-6 is a pro-inflammatory cytokine involved with the non-specific recruitment of inflammatory cells to a site of injury.  There was no significant difference between the two species of rhinos in the expression of this cytokine.  Interleukin-12 could not be measured for all rhinoceros because there was insufficient overlap between the competitive fragment dilutions and the host target cDNA. There was no significant difference in IL-12 mRNA expression between the 5 black rhinoceros and 4 white rhinoceros for which measurements could be made. IL-10 is considered an immunosuppressive cytokine. Elevated levels of IL-10 mRNA in the black rhinoceros were higher than all but 2 white rhinos (that were older and had some chronic medical conditions).  The apparent elevated levels of IL-10 may be normal for black rhinoceros.  The same may be true of the elevated fecal corticosterone levels found in the animals tested.


Black rhinoceros also had significantly high ferritin levels that increased with age.  This was expected as it has been previously documented.


6.  Project:  Immunology, Virology, and Determination of Genetic Code of Various Aspects of Rhinoceroses Health and Genome


Researcher:  Dr. Mike Worley, Zoological Society of San Diego, San Diego, CA  92101


- Analysis of MHC class II (DRB) alleles in approximately 250 wild-caught or free-ranging black rhinos representing individuals from three distinct geographical regions (Kenya-northern Tanzania, Zimbabwe-South Africa, and northwestern Namibia) that theoretically represent three subspecies.  Data, independently and in conjunction with microsatellite data from international collaborators, will be used to to determine the diversity of MHC alleles in distinct microbial environments and the relationships of putative subspecies.


-Analysis of MHC class I alleles in black rhinos.  The emphasis at this time is the characterization of diversity, polymorphism, and evolution of alleles from each of three distinct loci we have detected.  We will follow this phase of the research with an effort

to detect locus-specific sequences peripheral to the highly polymorphic second and third exons that can be utilized as primers to genotype individuals using genomic DNA.


-Sequencing of the complete open reading frame of each of several genes associated with defense against oxidative stress (catalase and lactoferrin) or involvement/association with iron storage pathology (Hfe, transferrin, transferrin receptor-2).  Hfe is completed for

black, white, Indian, and Sumatran rhinos while catalase is completed for African species.  This will be followed by detection of mutations within the ORF of specific genes for subsequent epidemiologicals investigations and identification of individuals possessing increased susceptibility to iron overload.


-Characterization of geographical-specific differences in the glycoprotein B gene sequences of two novel lymphotropic gammaherpesviruses "discovered" in our lab.  The  DNA polymerase and glycoprotein B genes have been entirely sequenced for each virus and virus-specific primers constructed for molecular detection of latency/infection.  PBMC genomic DNA from the DRB study is being used for the geographical study.


-Characterization and utilization of CD antigen-specific monoclonal antibodies for monitoring the numbers and relative ratios of leukocyte subsets in all species of rhinos.  This project was initiated in my lab several years ago with the help of Jeff Stott while he was on a pseudo sabattical at Hubbs-Sea World.  All that remains of the characterization is the determination of the molecular weight(s) of the target antigens for each antibody.  There are now 63 antibodies many of which are redundant.  However, we do have

antibodies for platelets, granulocytes, myeloid lineage (granulocytes, monocytes), mononuclear cells, monocyte subsets, and lymphocyte subsets.



7.  Project:  Evaluation of Antiphospholipid Syndrome


Researcher:  Dr. Ray Ball, Busch Gardens, Tampa, Florida


The antiphospholipid syndrome (APS) is defined as the occurrence of venous and arterial thrombosis, recurrent fetal losses, and frequently a moderate thrombocytopenia in the presence of the phospholipid antibodies (aPL), namely lupus anticoagulant (aLA), anticardiolipin antibodies (aCL), or both.  This is a broad definition in a syndrome that can affect virtually any body system.  Comparisons between APS and black rhino syndromes may not be obvious at first but there may be some parallels.


Antiphospholipid ELISA has been performed on several black rhinos from various institutes via direct contributions and from the SSP Serum bank in St Louis. Fifteen out of 24 animals tested showed a significant amount of antibodies to the mixture of anionic phospholipid in the test.  Many animals had only one sample tested but a few showed a rising level that persisted.  In one case a captive born animal was negative at one month of age and at 10 years of age has one of the highest titers.  Other neonates/juveniles are negative at this time.  A wild caught imported sample from Zimbabwe was also negative. Six out of nine animals sampled in one facility have tested with a significant amount of antibodies to the mixture of anionic phospholipid in the test while two additional animals with clinical problems seen in captivity have demonstrated a rising titer to the to the mixture of anionic phospholipid in the test.  Twelve individual black rhinos tested from Kruger National Park all had levels considered being negative; two of these animals had been bred and born in Europe and Florida and live in a semi-free ranging state for about 2 years.   These results are certainly preliminary but are substantial enough to continue.  Histories need to be examined closer on all animals but it is known that several of them have some of the clinical manifestations seen in captive black rhinos.  Wild rhinos are intended to be sampled at capture and at opportunistic intervals while in bomas for APS antibodies.


Samples are requested with histories from animals with any of the syndromes that have affected black rhinos in captivity.  Neonates/juveniles are also to be looked at as well as pregnant animals, animals with embryonic/fetal losses (from all causes).  Beta-2-glycoprotein (B2-GPI) and IL-3 will hopefully be examined in these animals and wild animals when the opportunity arises. Please contact Ray Ball, DVM at Busch Gardens 813-987-5562, Fax 813-987-5562, e-mail at for more details and shipping arrangements.


8.  Project:  Evaluation of Iron Metabolism as a Function of Age and Diet


Researcher:  Dr. Michele Miller, Disney’s Animal Kingdom, Lake Buena Vista, Florida


Captive black rhinoceros have increased hemosiderosis as compared to captive white rhinoceros (Ceratotherium simum) (JE Smith, PS Chavey, RE Miller, 1995).  This appears to be a condition of captivity, since recently captured animals do not have this condition.  Antecdotal information indicates that diet and environmental factors play an important role, since black rhinoceros born in other countries, such as Japan and Australia, do not develop the severe iron loads seen in captive animals in North America (D Paglia, pers. comm.).  Iron accumulation in tissues can lead to a variety of pathological conditions, and may lead to fatal toxicosis.  Therefore, monitoring the amount of stored iron and iron secretion is important in determining methods of prevention and treatment. 


Currently available methods for assessing iron stores include measuring nonheme iron concentration in liver, bone marrow, and spleen; quantitating iron mobilized by phlebotomy; or assess chelator-induced urinary iron excretion.  Due to the logistical difficulty of obtaining these samples in black rhinoceros, other indirect methods can be used.  These include serum iron, ferritin, total iron binding capacity, haptoglobin and urinary iron (JE Smith, et al., 1995).


Since iron accumulation would hypothetically worsen with age in a captive animal, serial samples over time might allow detection of excess iron loads in time to start intervention (i.e., chelation, therapeutic phlebotomy).  This baseline would also allow comparison of iron absorption from different diets.


Proposal:  Monitor urine iron, urine specific gravity, urine creatinine, serum iron (and other trace minerals), total iron binding capacity (TIBC), ferritin, ceruloplasmin, haptoglobin, hematocrit and total protein, in juvenile and adult black rhinoceros exposed to the same dietary and environmental factors to determine the effects of age and create baseline for diet changes or other interventions.


Any diet or health changes will be recorded.  Diet analyses of pellet, hay, and browse is performed with each new batch delivered.  Data will be analyzed for effects of age and gender.  Data collected before and after any diet changes will be compared.




Black Rhinoceros Deaths

July 1, 2001 – July 31, 2002


Southern Black Rhinoceros (Diceros bicornis minor)


SB#/Institution  Sex      DOB                DOD                Cause of Death


468/White Oak            F          1982 (wild)      22Sept01         Sudden death due to liver and

                                                                                                kidney failure, sepsis.

                                                                                                Generalized hemosiderosis,

                                                                                                biliary cysts, mineralized

                                                                                                blood vessels and other age-

                                                                                                related changes.

                                                                                                Mild lymphocytic

                                                                                                encephalitis – WNV


                                                                                                negative; WNV titer 1:640

                                                                                                at time of death.


466/Fossil Rim F          1977 (wild)      8Dec01            ?


Eastern Black Rhinoceros (Diceros bicornis michaeli)


SB#/Institution  Sex      DOB                DOD                Cause of Death

869/San Francisco        F          14Nov01         14Nov01         ?


409/Detroit                   M         1952 (wild)      5Dec01            ?                                                                     



Rhinoceros Nutrition Research Update 2002

Ellen S. Dierenfeld, Wildlife Conservation Society

Nutrition Advisor, Rhino TAG


Project Updates:


Feeding Trials with Captive Black Rhinoceros and Different Dietary Tannins.  Investigators:  Marcus Clauss (University of Munich) et al. and represents a continuation of the project reported last year. Samples for passage rate analysis (n=7 trials) have been processed and the analyses have been finished. The average fluid and particle passage rates for the 7 animals were 35.0 (± 8.1, range 27.4-48.0) and 42.5 (± 13.8, range 31.0-67.1) hours, respectively. The particle marker was retained 1.1-1.4 times longer than the fluid marker. Animals that had a higher dry matter intake had faster passage rates. However, there seemed to be a pattern that indicated that an increase in food intake could not accelerate passage in a constant way. At a particle passage of about 30-40 h, passage seems to not have been further accelerated by an increased intake. In a similar way, food intake seemed to have a negative effect on dry matter digestibility, but again only up to a certain threshold of about 50 % digestibility. Accordingly, the passage rate did show a positive correlation with digestibility, but again, within the range of about 30-45 h of passage, digestibility did not seem to be influenced.


Status of iron analyses:  One final feeding trial for iron absorption was performed in June (with one animal at Zurich Zoo; this animal had not been included in the regular absorption schedule last winter because it can only be bled reliably during reasonably warm weather). With this last trial done, the blood samples are now ready for isotope analysis, which will be instigated after the summer break. Similarly, these last blood samples complete the batches of samples that shall be analysed under the supervision of Don Paglia in Los Angeles.  Mineral, fatty acid, and antioxidant analyses of blood samples is pending.


Contrary to expectations, bleeding of all animals used in the trials was not possible; a surrogate analytical measurement that could serve as an indicator for the influence of the dietary tannin treatments on the antioxidant status of the animals, through antioxidant status of the faeces, was identified.  Samples were analyzed at the University of Parma, and showed a distinct increase in both animals after the quebracho tannin treatment at both Whipsnade and Zurich zoo. Interestingly, neither tannic acid nor browse feeding had a measurable influence on the faecal antioxidant status, and differences appeared to be institution-specific (possibly due to differences in concentrate:forage ratios in the diet). 


Status of savliva analyses: Analyses of saliva for tannin-binding proteins were completed, including a comparison of white and Indian rhinos. Interestingly, the Indian rhino had generally higher levels of salivary tannin-binding proteins, especially for condensed tannins. In the black rhinos, only tannic acid feeding resulted in an increase in salivary tannin-binding proteins – albeit for both hydrolysable and condensed tannins.  In the black rhino, the tannic acid ingredient resulted in a significant physiological feedback. This indicates that these animals are well adapted to deal with hydrolysable tannins. The question remains whether the tannins will have another beneficial effect for the animals. The fact that quebracho seemingly did not trigger a feedback mechanism and seemingly passed the intestinal tract unabsorbed (c.f. the antioxidant data) could indicate that this tannin might be particularly suitable for a reduction in iron availability. These results raise new questions about the feeding habits of the Indian rhino – which is thought to be a “mixed feeder” with about 75 % of grass in its natural diet.  The presence of tannin-binding proteins in this species could be indicative of either an evolutionarily recent switch to a grass-dominated diet, or of natural feeding habits that have not been recorded yet.













This project was funded by a grant (R-2000-11) from the International Rhino Foundation/SOS Rhino


Nutritional Studies on Captive Indian Rhinos.  Investigators: Marcus Clauss, Carmen Polster, & Prof. E. Kienzle, Institute of Animal Physiology and Animal Nutrition, Munich (official supervisor for the dissertation of C. Polster); Prof. H. Wiesner (Director of Munich Zoo), Dr. K. Baumgartner (Vet of Nürnberg Zoo); and Dr. F. von Houwald (Curator of Basle Zoo).   Feeding trials with 7 Indian rhinos from 3 different institutions on two dietary regimes per animal were performed from March-May 2002. The dietary regimes consisted of the diet regularly fed at the according institution, and the same diet without the concentrates. Each feeding trial consisted of a one-week adaptation period and a one-week collection period. Food intake and faecal excretion were measured. Faeces were collected in toto. Additionally, passage rates were determined in seven trials. Water consumption was measured if possible, and urine samples were taken.


Preliminary results suggest a good correlation between dry matter intake and passage rates, with passage ranging from 55 to 74 hrs. There was no evident correlation between passage rate and dry matter digestibility. The scope of the passage rates – about 60 hours – should result in optimal digestive efficiency; a distinct increase in digestive efficiency at these long passage rates seems unlikely. In general, the crude fibre content of the whole diet (% dry matter) was negatively correlated to the dry matter digestibility – the same correlation is found e.g. in horses, elephants, etc.  There was an evident correlation between the amount of water consumed and the urinary creatinine concentration; the urinary creatinine concentration will be important later on for the interpretation of the results of urine analysis for calcium. The most interesting finding, up to now, seems to be the distinct difference in dry matter digestibility between the three facilities, and differences in digestion with and without the concentrate portion of the diet. Differences are most likely due to a difference in roughage quality (analyses not finished), and underline the general importance of roughage assessment for a rational dietary management. In November, C. Polster will carry out similar trials at the Wildlife Conservation Society, New York (supervision: E.S. Dierenfeld). The full range of results from her study are expected by the end of the year. This project was funded by a grant from the International Rhino Foundation/SOS Rhino.


Dietary Iron Absorption and the Role of Tannins in Eastern (Diceros bicornis michaeli) and Southern Black Rhinoceros (Diceros bicornis minor), a Comparison. Investigators: Sue Crissey & Tom Meehan, Brookfield Zoo; Ann Ward, Fort Worth Zoo.  Participating facilities: Brookfield Zoo, Dallas Zoo, Fort Worth Zoo, Fossil Rim Wildlife Center, and El Coyote Ranch.


Overview:  Four diet treatments are offered for 6 months each to assess the effect of tannins on iron status, antioxidant status, diet digestibility and fatty acid composition of plasma.  Each institution is at a different stage within the study but all zoos have completed procedures necessary to successfully collect blood and digestibility data.  The 1st diet treatment evaluated current diets, and indicated that diets consumed varied widely among participating zoos (concentrate 25-48%, alfalfa hay 37-55%, grass hay 7-19% of the diet, dry matter basis.)  Subsequent diet treatments include each animal at each zoo consuming the same pellet to hay ratios.  Specifications for the pelleted diet for the 2nd treatment have been set with manufacture soon to follow; in-house laboratory analysis has expanded to include analysis for the digestibility marker C36, an alkane.  The addition of analysis for indigestible NDF as a digestibility marker by Purina Mills has been added to provide more definitive data as well. This project was funded by a grant from the International Rhino Foundation/SOS Rhino.



New publications:


Beutler, E.; West, C.; Speir. J.A.; Wilson, I.A.; Worley, M. The HGE Gene of Browsing and Grazing Rhinoceroses: a Possible Site of Adaptation to a Low-Iron Diet. Blood Cells, Mole, Dis. 2001. 27(1): 342-350.


Clauss, M., D.A. Jessup, E.C. Norkus, M.F. Holick, W.J. Streich, and E.S. Dierenfeld. 2002. Fat Soluble Vitamins in Blood and Tissues of Free-Ranging and Captive Rhinoceros Species.  J. Wildl. Dis. 38(2): 402 - 413. 


Clauss, M., J. Gehrke, J. Fickel, M. Lechner-Doll, E.J. Flach, E.S. Dierenfeld, J.-M. Hatt. 2002. Induction of Salivary Tannin-Binding Proteins in Captive Black Rhinoceros (Diceros bicornis) by Dietary Tannins. Proc. Comp. Nutr. Soc. 4:   Antwerp, Belgium.


Clauss, M.,  T. Froeschle, M. Lechner-Doll, E.S. Dierenfeld, and J.-M. Hatt. 2002.

Fluid and Particle Passage Rate in Captive Black Rhinoceros (Diceros bicornis).  Proc. Comp. Nutr. Soc. 4:   Antwerp, Belgium.


Gehrke, J., J. Fickel, M. Lechner-Doll, R. Hermes, E.J. Flach, J.-M. Hatt, Clauss, M.. 2002.  Tannin-binding salivary proteins in three captive rhinoceros species. Proc. Comp. Nutr. Soc. 4:   Antwerp, Belgium. 


Grant, J.B., D.L. Brown, and E.S. Dierenfeld.  2002. Essential Fatty Acid Profiles Differ Across Diets and Browse of Black Rhinoceros.  J. Wildl. Dis. 38:132-142.


Paglia. D.E.; Kenny, D.E.; Dierenfeld, E.S.; Tsu, I-H. Role of Excessive Maternal Iron in the Pathogenesis of Congenital Leukoencephalomalacia in Captive Black Rhinoceros (Diceros bicornis). Am. J. Vet. Res. 2001. 62(3): 343-349.


Radcliffe, R.W., S.B. Citino, E.S. Dierenfeld, T.J. Foose, D.E. Paglia, J.S. Romo.  2002.  Intensive Management and Preventative Medicine Protocol for the Sumatran Rhinoceros (Dicerorhinus sumatrensis).  Report on: I. Sumatran Rhino Reproductive and Health Assessment  II. Intensive Management and Preventative Medicine Protocol for the Sumatran Rhinoceros, R.W. Radcliffe, R.M. Radcliffe, T.L. Roth, M.H.T. Troedsson, and C.H. Radcliffe.


Ward, A.M., A. Hunt.  2001.  Summary of mineral and iron binding polyphenolic plant compound levels in diets offered captive black rhinoceros (Diceros bicornis) in 3 zoos and 1 ranch in Texas.  Proc 4th NAG Conf., Orlando, FL. Pp. 173-186.




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