NDF digestibility:
Sheep, Horse and Black
Rhinoceros
4 sub-species
•
•
•
•
South-Central (Diceros bicornis minor)
South-Western (Diceros bicornis bicornis)
East-African (Diceros bicornis michael)
West-African (Diceros bicornis longpipes)
• Diceros Greek (Di= two Ceros= horn) and Latin
Bicornis (Bi= two Cornis= horn)
• So the southwestern black rhino is a two horn
two horn two horn…hmm
Physical Characteristics
• Black rhinos attain a weight of 2,100–2,900 lb (950–
1,300 kg); shoulder height of 56–63 in (143–160 cm);
and head and body length of 112–120 in (286–305 cm).
Male and female are similar in size.
• Despite name, the skin is gray to brownish gray in color,
and devoid of hairs.
• Horns are made of Keratin. Anterior horn is 16.5–54 in
(42–138 cm) in length, the posterior one 8–20 in (20–50
cm).
• Have a saddle-backed appearance, rounded ears, and
tend to hold the head high, except when feeding on low
vegetation.
Behavior
• Largely solitary, although groups of three to five
animals may occasionally form.
• A cow and her calf comprise the basic social
unit, and adult males are solitary, except when
courting a female
• When adult males meet, a complex bull
ceremony may take place, involving stiff-legged
scraping, imposing postures, and short charges
sometimes accompanied by screaming groans.
• Females are not territorial, but males will tolerate
submissive intruder males.
Behavior
• Males mark the environment with long
drag marks made by the legs, spray urine
over bushes or other objects, and deposit
feces on dung-heaps.
• Females use the same dung-heaps and
animals of both sexes scatter their
droppings with backwardly directed kicks.
Distribution
The Black Rhinoceros
once roamed the lower
half of Africa in
hundreds of thousands.
Today it survives in
pockets primarily in
Zimbabwe, South
Africa, Kenya, Namibia
and Tanzania.
Feeding Ecology and Diet
• Live primarily on grasslands, savannahs, and tropical bushland
habitats.
• Predominantly low-level browsers, feeding on small saplings and
shrubs under 5 ft (1.5 m) in height as well as a variety of herbs,
thorny wood, fruit and occasionally small amounts of grass. They
often browse in the morning and evening.
• Can eat up to 220 different species of plants.
• Can live up to 5 days without water during droughts.
• Acacia spp. are especially favored, as are various species of
Euphorbiaceae, including succulent forms with milky sap reputed to
be poisonous.
• The prehensile upper lip is used to pull twigs into the mouth, which
are then bitten off with the cheek teeth. They crop branch tips up to
0.4 in (10 mm) in thickness and 4–9.8 in (100–250 mm) in length.
The horns may be used to bend or break stems to reach higher
branches. Bark may also be stripped from certain trees.
Diet Composition of Non-Captive
Black Rhinoceroses
Shrubs/Trees
Herbs
Grass
Source
87-95
5-13
0
Joubert 1971
54-81
18-41
0
Mukinya 1977
81-94
6-19
0
Hall-martin 1982
47-93
5-51
0
Oloo 1994
93-95
3-5
1
Atkinson 1995
56-76
1-11
0-1
Pole 1995
69
31
0
Henning 2001
Digestion
Although all rhinos are hind-gut fermenters like
rabbits and horses…
The fact that Black Rhinos are browsers is
very important!
– Fundamental difference between fermentation
characteristics of browse and grass
• Browse has a faster fermentation rate and soon
reaches its maximum energy release
• Grass has a slow fermentation rate and still yields
energy after a longer period of time
Clauss et al 2006
Digestion
• White Rhino
– Squared off upper lip used to
“crop” grass
– Grazes on savannah
• Black Rhino
– Prehensile upper lip for
browsing
– Consumes bushes and
shrubs in forest
Comparative Anatomy: Black Rhino
•The stomach is simple, and the
cecum and colon in the hind-gut
serve as the main sites of
fermentation
•Short, wide colon
•Gradual transition from colon
ascendens to transversum
Clauss et al 2003, 2005a
Comparative Anatomy: Horse
• Monogastric herbivore with
extensive post-gastric
fermentation
•Simple stomach incapable of
utilization of forage-based
(high fiber) diets
•Abrupt shift from colon
ascendens to colon
transversum
Comparative Anatomy: Sheep
•Ruminant herbivore with extensive
pre-gastric fermentation
•Highly developed sacculated
stomach capable of extensive and
effective utilization of forage-based
(high fiber) diets
•Extensive fermentation before
primary sites of digestion and
absorption
Comparative Anatomy: length of
GIT (in meters)
Horse
Black Rhino
S. Intestine 26.7 (76%)
12.0 (66%)
Caecum
Colon total
DFC total
Total GIT
0.7 (5%)
4.9 (28%)
3.7 (20%)
18.5
1.0 (3%)
7.0 (20%)
4.5 (13%)
35.0
Frewein et al (1999)
Stevens/Hume (1995)
Comparative Anatomy
• There are two ways to increase passage
time in a tubular system: to shorten the
length or to increase diameter
• Body length does not always mean longer
GIT (horse and tapir longer than an
elephant!)
• Browsing Rhino’s have a short and wide
ceacum (46-91 cm) compared to horses
(15-18 cm)
Clauss et al 2003
Comparative Anatomy:
Average Mean Retention Times
50
45
40
35
MRT (h)
30
25
20
15
10
5
0
Sheep
A longer retention time=
Slower passage rate
Horse
B. Rhino
Clauss et al 2005a,
Illius and Gordon 1995
Clinical Study: Digestion Coefficients
for the Black Rhinoceros (Clauss et al 2006)
• Objective of this study was to determine if
horses were appropriate models for nutrient
recommendations for the Black Rhinoceros
• Current practice applies the equine model to
grazing hind gut fermenters such as the white
rhinoceros
• It was unknown prior to this study if browsing
behavior would reduce digestion coefficients,
making the horse a poor model
• Did expect that browsers would display a shorter
ingesta retention time and lower digestion
coefficients as compared to grazers when on
comparable diets
Clinical Study: Digestion Coefficients
for the Black Rhinoceros
Materials and Methods:
•Eight rhinos were used, selected from 3 zoos.
Animals were kept separate during the trial to allow for
collection of feces and recording of dietary intake.
•Protocols developed for domestic sheep (Mason and
Frederickson 1979) were used to evaluate nutritional
components including dry matter (DM) and Neutral
Detergent Fiber (NDF).
•Study compared the digestibility of rhinos to horses using
previously published studies.
•Additional data on browsing and grazing rhinos was also
included from published and unpublished studies.
Clinical Study
Materials and Methods:
• The diets varied in total make-up but
included some % of the following:
lucerne hay, grass hay, browse,
concentrates, fruits and vegetables
• Main concern was a crude fiber content
that averaged 25 and crude protein
averaging 15.
Clinical Study: Digestion Coefficients
for the Black Rhinoceros
Results:
When compared with horses from previously
conducted studies (on similar rations), the
black rhinoceros achieved lower digestion
coefficients
Clauss Study Results:
Horses outperform Rhinos
Clinical Study: Digestion Coefficients
for the Black Rhinoceros
Potential reasons:
• Comparatively shorter ingesta retention times in the
black rhino (Clauss et al 2005b)
•Among wild ruminant species, it has been demonstrated
that browsing species achieve lower coefficients than
grazing species (Iason and Van Weiren 1999)
•Hackenberger (1987) demonstrated that the African
elephant which is thought to be adapted to a diet with
more browse material than its Asian counterpart also
displays shorter retention times and decreased digestion
of grass hay
Don’t take our word for it…
Browsers vs. Grazers
Why?
• The digestive strategy of long retention
times to increase digestion coefficients is
an evolutionary adaptation one would
expect in grazing species- whether hind
gut or foregut fermenters
– Grass has a slow fermentative rate and still
gives energy even after a long period of time
The why, continued
• Shorter retention times are expected in
browsing species
– browse has a faster fermentation rate and
soon reaches its maximum energy release
– So if you gave a browsing rhino Alfalfa, you’d
expect that it wouldn’t reach its full energy
potential because its not fermented long
enough. You’d also expect that he’d want to
eat a lot more.
So, the Black Rhino comes to NUT
115 and eats alfalfa pellets…
Real and Expected Digestibility order
Sheep 63.7 DM/43.9 NDF
Horse 58.6 DM/27.2 NDF
Rhino ~53 DM/~26 NDF
FYI: More on the Vit E
Question
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•
•
•
•
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Problem: Rhinoceros accumulate body stores of iron over their lifetime that may be
associated with numerous maladies: ie captive black rhinoceroses have a history of
disease and death characterized by hemolytic anemia and mucocutaneous ulceration
Current trends: Iron and copper supplements have been routinely given to captive
rhinos. In the absence of species specific data, nutrient levels are based on work
performed with domestic livestock.
Potential Causes: Many nutrients listed as possible causes in the syndromes may be
linked in some way to each other
Specific nutrients of concern: ferric iron antagonist to vitamin E, interactions between
absorption of dietary iron and vitamin E, and linkages between copper and iron
absorption/functioning.
Wild Rhino Diet: Natural browse of black rhinoceros contains secondary plant
compounds including tannins that may decrease mineral absorption. It is possible that
these chemicals may bind excess dietary iron in the natural diet. Commercial hays
contain tannins, but at lower levels… and are fed to captive rhinos (budget, absence of
data, etc)
Diets without tannins are hypothesized to cause increased iron absorption and an
insufficient antioxidant status, and therefore to contribute to disease symptoms
observed in captive black rhinos
Current study at the Brookfield Zoo (Illinois): "Dietary Iron Absorption and the Role of Tannins in Eastern (Diceros bicornis michaeli)
and Southern Black Rhino (Diceros bicornis minor), a Comparison"
Website: http://www.sosrhino.org/research/black_rhino_nutrition2.php last acessed 3/13/06
References
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HUMMEL J; HATT J.M (2006) Digestion coefficients achieved by the black rhinoceros (diceros bicornis), a
large browsing hind gut fermenter. Journal of Animal Physiology and Animal Nutrition 90: 325-334.
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