S . A f r . J . A nim . S c i .9 ,4 7 * -1 1( 1 9 7 9 )
A NOTE ON CONDITION INDICES FOR ADULT MALE IMPALA, AEPYCERO-S
MELAMPUS
Receiptof MS 10-03-1979
R.H. Monro and J.D. Skinner
Mammal ResearchInstitute, University of hetoia, Pretorio,0002
(Key words:
Antebpe, body condition)
(Sleutelwoorde: IUidsbokke, kondisie)
OPSOMMING:
'N WAARDEBEPALING VAN KONDTSIEINDEKSE VIR VOLWASSE ROOIBOKRAMME,
AEPYCEROS
MELAMPUS
Maatstawwe van kondisie word bespreek en gedefineer. Agt-endertig kondisie indekse, geneem vanaf nege vol,,ial.;e rooibokram'n
me was getoets vir lini6re korrelasie met kondisie en totale liggaamwet. Indekse afgelei van die volledige disseksie vrin
boud was die
'n
betroubaarste, maal aangesien die niervetindeks ook betroubaar was, en heelwat makliker is om te bepaal. word dit aanbeveel as
'.'erkry
geskikte veldtegniek mits niewet teenwoordig is. N6g beenmurgvet n6g enige ander indeks wat vanaf lewendigc diere
kan word
bet goeie korrelasie getoon met kondisie.
SWMARY:
Citeria of condition are discused and defined. Thirty-eight condition indices taken from nine adult male impala were tested lor
linear correlation with condition and total body fat. lndices derived from the complete disection
of a buttock proved to be the most
reliable, but as the kidney fat index was also reliable, and considerably easier to obtain, this was recommended as a more suitable field
technique as long as perinephric fat was present. Neither bone marrow fat nor any of the indices which could be obtained from live
animals proved to be well correlated with condition.
However, in most studies of wild ungulates the
indices used have been bone marow fat (Chaetum,
1949; Sinclair & Duncan, 1972; Brooks, Hanks & Ludbrook, 1977), or the kidney fat index (Riney, 1955;
Caughley, l97O), although some authors consider the
latter to be inadequateas a singleindex for animals in
poor condition (e.g. Ransom, 1965). The same inadequacywould apply to animals in which perinephric
fat was completely absent for part of the year due to its
relatively early mobilisation under conditions of nutritional stress.On the other hand, Smith (1970)hasbeen
the only one to correlate a number of condition indices
with whole body constituentsand he concludedthat the
kidney fat index representedthe most workable technique, but leg fat, viceral fat and "live weight ratio"
(correctedlive weight) ^,_^ -L ___.^
r positive correlations
also showed
ffi
with whole body fat. Franzmann, Le Resche,Arneson
and Davis (1976), studying moose in Alaska, found
that a combination of packed red cell volume, total
plasrnaproteins, haemoglobin,calcium, and phosphorus
levels gave a reasonableindication of body condition.
The purpose of the present study was to investigate a number of condition indices for adult male
impala and to correlate these with body constituentsto
establishwhichgavethe best estimateof body condition.
Introduction
Assessingbody condition of wild African ungulates has become increasingly important in recent
years with a view to their management,as this reflects
not only their ability to survive under different conditions but also their potential asproducersof meat.Most
studieshave assumedthat condition can bestbe assesed
by someobjective measurementof the fat content of the
body as is common practice with domestic livestock,
despite the fact that in their best condition carcas fat
percentagesr:uely exceed 5 per cent comparedto 7 per
cent for emaciatedBos indicus steers,or 30 per cent for
those in good condition (Talbot, Payne, Ledger, Verdcourt & Talbot, 1965). Becausewild ungulates can
decline very markedly in body condition this leads to
the speculation that body protein may be utilised to a
much greater extent as a reservesource of energy, yet
few studies have included assessments
of body protein.
Smith (1970) however, did suggestthat this may be an
important sourceof energyunder stress.
In domestic ungulatesa good asessmentof body
composition can be madeby detennining the amount of
disectable fat in the buttock, which is highly correlated
with the total fat content of the carcass(Orme, Cole,
Kincaid & Cooper, 1960;Butterfield,1962), and this has
also been used in some wild ungulate studies(Huntley
197l, Von La Chevallerie& Van Zyl, 1971), although it
has neverbeen shownntrether the samecorrelation exists
hocedure
Nine adult male impala from the northem Trans-
47
vaal were used in this investigation.Immediately after
they had been shot through the neck a venousblood
sampleof about 100 ml was collectedfrom eachanimal
in a heparinisedplastic bottle. After retuming to the
laboratory this blood was centrifugedfor one hour at
3 000 r.p.m. to separateoff the plasmaand to find the
haematocrit value (packedcell volume) usinggaduated
small calibre centrifuge tubes. After separation the
plasmawas kept frozenuntil it was requiredfor analysis.
After shootingthe animalswere encasedin plastic
sheetingto prevent excessiveloss of blood and body
fluids whilst in transit to the dissectinglaboratory.
Here, having estimatedage from horn shapeand madea
visual assessment
of condition from body conformation
following Riney (1960), the animals were weighed,
routine body measurements
were taken, and they were
then butchered. One buttock, which made up a mean
of 14,4 t 1,0 per cent of the carcas weight of each
animal, was dissectedinto muscle,bone and tendon,
and fat, the femures being kept frozen for later marrow fat analyses.Riney's (1955) kidney fat index
weight of perinephricfat
(KFI =
x 100 was calculated
weightof kidney
for eachanimal.
All the pieces of the carcasswere put into one
plastic bag, and the rest of the individual, except the
horns,but includingthe emptiedintestine,wasput into
another.Thesewere then left in a deep freezerovernight
before being separatelyminced in a "\ilolfking" mincing
machine capable of reducing all body componentsto
small fragments.Samplesof the well mixed mince from
eachbag were taken and dried to constantweight to find
their water content. Thesedried sampleswere then finely groundin preparationfor chemicalanalysesof protein,
fat, and ash content using the methodsof the Association of Official Agricultural Chemists(Honvitz, 1965).
Femur marrow water and fat contentswere found
by removingabout 5 cm of marrow from the centre of
each femoral shaft, weighing this, and drying it to
constantweight before extractingthe fat with ether in a
soxhlet apparatus.
The samplesof blood plasmawere analysedin two
batches:the first, from animalsone to five,was analysed
using the methods of Wooton (1974) for total plasma
proteins,Kingsley(1940) for serumalbumin,Coulombe
and Fourean (1963) for urea nitrogen,Falholt, Lund
and Falholt (1973) for free fatty acids,Watson(1960)
for cholesterol,and a "Merk" commercialkit (8. Merk,
Darmstadt,Germany)for total lipids.
The secondbatch, from animals six to nine, was
analysedusing a refractometer(American Optical Compony, Keene,N.H., U.S.A.) for total plasmaproteins,an
"Albustrate" reagent system (Warner-Lambert Co.,
Morris Plains, N.J., U.S.A.) for serum albumin, a
"Roche" test kit (Roche products,Beme,Switzerland)
for urea nitrogen,a "Dr HeinzHaury" testkit (Dr Heinz
Haury, Miinchen, Germany) for free fatty acids,and
"Dr Lange-Kiivetten-Test"
kits @r Bruno Lange,Berlin,
Germany)for cholesteroland total lipids.
48
lndices of body condition
Most indiceshavebeen usedwithout definingwhat
condition is in terms of body composition.Becauseother
sourcesof energy may be important in wild ungulates
some influence was given to theseby consideringbody
Body fat
conditionas
x 100,where fat and ashwere
Ash
both expressedas percentagesof dry weight. Fat was
thereforestill the most important element,but the total
amount of organicmatter alsoplayeda role in determining condition.
Apart from considering straightforward measurements of blood constituentsand fat as indicators of
condition, ffiy measurementwhich might increase or
decreasewith changingcondition could alsobe usedif it
were divided by any measurementwhich remained
reasonablyconstant. Thus in the live individual body
mass and heart girth are changing parameterswhich
could be divided by head length, metacarpallength,
hind foot length,body length or shoulderheight, while
in the slaughteredanimalcarcass
weight,buttock weight
or buttock circumferencecould be divided by carcass
length, metacarpallength, hind foot length or buttock
length to givean index of condition. In this study a total
of 38 possiblecondition indiceswere evaluatedby correiationwith the abovecriterion for condition and with
total body fat (per cent dry weight of organicmatter).
Results
The actual condition ratings of the nine animals
accordingto three different criteriaare givenin Table l.
Table I
Three a.ssessments
of the physical cctnditionof nine male
impala shot in the northern Transvaalbetween
June 1976 and September1977
bodyfat
(fat and ashas per
thr// A
^ _
=-*-*100
cent of dry weight)
BF = Total body fat (per cent dry weight of organic
matter)
Vis = Visual estimate(madejust before dissectionof
animal)
Animal
number
F/A
BF
Vis
I
2
3
4
5
6
7
8
9
1 3 5, l
32,5
822
80J
27,1
36,3
19,5
42,2
22,8
24,0
6,5
Good
Good
Good
Fair
Fair
Good
Poor
Good
Fair
ls3
16,1
6,0
79
49
8,8
5,1
It is apparent from this table that visual estimation of
condition from body conformation was neither defintive nor particularly accurate in terms of actual body
composition, but that percentagebody fat (BF) and
Knna/
-=
A good negativeconelation was found between
the percentageof water (W) and the percentageof fat
(F) in the wet femur marrow, supporting the findings
of Neiland (1970) and others. The regressionequation
generatedby the presentresultswas
?ot
x 100 (F/A)
were in fairly good agreement
F = 8 9A 3 - 0 9 3 w ( r = 0 B 9 ) .
in the assessment
of condition.
The basic data collected from the nine impala,
includingKFI and the resultsof bone marrow and blood
analysesare given in Table 2 with the coefficientsof
correlationfor the linear regression
of all the condition
indices evaluatedagainst F/A and BF. Table 3 shows
the chemicalbody condition of the impala.
lt is clear that the only three indices which could
be used as indicatorsof condition as here defined are,
buttock fat per cent wet weight,KFI and buttock bone
and tendon per cent wet weight, as thesewere the only
ones that were significantlycorrelatedwith F/A and BF.
Table 2
The body measurements,
blood constituentsand conelation coefficientsfor condition indices
bdY
, , , i t t ^ f E ' t , -=--#x
wtth
lA
t"
100 (fat ond ash as per cent dry weight) and BF =body fat (per cent dry weigltt of organic
matter) for nine adult mnle impalo shot in the northern TransvaalbetweenJune 1976 and September1977
N=9
Meant SD
Body masskg
Body length cm
Carcasweight kg
Carcass
length cm
Buttock weight kg
Kidney fat index
Buttock fat per cent wet weight
Buttock bone and tendon
per cent wet weight
Femurmarrow per cent H2O
Femur marrow fat per cent dry weight
Hematocritper cent
Total plasmaproteinsg/100ml
Albumin g/100 ml
Albumin : Globulin ratio
Blood ureanitrogenmg/100ml
Total lipids mglt00 rnl
Freefatty acidsmgll
mg/100rnl
Cholesterol
57,2 +
137,3 t
349 t
749 t
49 +
8,5
7,2
5,9
3,7
0,7
Range
0,58
39,0
130,0
229
71,5
3,8
3,1
0,56
64,CI
149,0
4tp
81,0
5,7 +
102,7 +
2,32 +
14,7 +
1,7
42,5 t
24A
81,6 + 2l3
48,3 I
5J
6,7 +
12
29 +
0,8
og2 +
0,52
18,5 t
4,6
269,8 t 186,0
0,13 +
0,07
82,3 + 27,l
12,3
8,1
27,4
4l,l
5,3
1,8
0J8
12,5
65,0
0,02
35,0
l7 I
85,6
97S
56,5
8,7
42
194
26,7
580,0
0,24
118,0
))1
098 r
+
F/A
BF
0,53
0,50
0,45
0,44
0,66
0gs
096
0,65
093**
0 B 5* *
0,84
0,63
033
0,84*
053
03t
0,17
0,66
020
033
0,68
0,49
030
0,04
o22
+
+
+
+
+
0,65
o2l
031
0,70
051
028
0,05
* P< 0 , 0 1
**P<0,001
Remainder n on-signifi cant
Table 3
The chemical body composition of nine dehorned mole impala shot in the northem TransvualbetweenJune 1976
and September1977. HzO =per c€trt wet weight : all other figures refer to dry weight. Mean t S D and Range
Hzo
weight(kg)
Protein(fl )
F a t( % )
Ashg , )
9 7 1 , 3+ | , 7 ( 6 1, g- - 74 , 1 ) 1 3,$ + | ,7 (1 2 ,6 - 1 5,6 ) 6 6 , t+ 4 3 6 7 , g - 7 2 3 8 ,9 + 5,6(3g -20 ,4) 1 7 3 ! 1 5 ( 1 5 , 1 - 2 0
,0)
49
ltre decision as to what levels of F/A or BF
representgood or poor condition is of coursecompletely
arbitrary, The following values could be used as a guide
for adult male impala:
As both buttock fat and buttock bone and tendon
determinations required complete buttock dissection,
and as the former was positively and the latter negatively correlated with condition, it seemed sensible to
combine thes€two indicesas
Buttockfat
Buttock bone and tendon
the buttock
to give an even more reliable index
dissection index (BDI). Correlation coefficients for this
index were 0,97 and for all indicescorrelationwith F/A
was ratherbetter than with BF.
F / A < 3 0 : B F ( 6 , 6 : P o o r: B D I( 3 , 7 5 : K F l ( 4 , 1
F / A3 0 - 5 0 : B F6 , 6 - 1 0 ,:0F a i r : B D I3 , 7 5 - 4 , 2 5K:F I 4 - 1 7
F ' / A> 5 0 : B F > 1 0 , 0 : G o o d :B D I) 6 2 5 : K F I l I 7 J
Discussion
Conclusions
The present resultsshowedthat a far more reliable
index of condition was obtainable from individual
dead animals than from live animals, and it was only
within the scope of this investigation to recommend
those methods of appraisal even though a live animal
index might be preferable as a managementtool. Such
an index could posibly be obtained from the tritiated
water (TOH) techniques of estimatingbody composition used by Meisner and Bieler (1975) and others,
although these would be difficult to apply to large
numbersof wild animals.
Nthough a large number of measurablecondition
indices were tested in this study very few of them
proved to be significantly and consistentlycorrelatedto
actual body condition as here defined. Similarly, visual
assessmentmade on criteria of body conformation
did not appearto accuratelyreflect body composition.
The "buttock dissectionindex" was found to show the
closestconelationwith condition,but due to the greater
ease with which it could be obtained the "kidney fat
index" was recornmendedas the most suitable field
technique" Bone marrow fat was not significantly
(P<0,1) correlatedwith body condition and unfortunately no reliable index of condition was obtained
from live animals.
As for domestic animals the best individual indicator of condition found in the presentstudy was the
percentage of dissectable fat in the buttock. When
combined with the proportion of bone and tendon in
the buttock as BDI this became even more reliable.
For generaluse 'iiis index could be said to have a linear
relationship with r:ondition (F/A) roughly expressedby
the equation F/A = 8 x BDI. Its relationshipto total
body fat (BF) cur be givenby the equationBF = 1,4 x
The low levels of fat found in impala suggestthat
adiposetissue may not be used as a major source of
energy storagein this species.The fat-relateddefinitions
of condition usedin this study may therefore not reflect
the true physiological state of the animals. Future
researchin this field would benefit from a better understandingof the metabolicreactionsof tropical ungulates
to nutritional stres, allowing "condition" to be more
realisticallydefined.
BDI+ | 2s.
The disadvantageof the indices requiring buttock
dissection lay in the time and effort required to obtain
them. One of the essentialattributesof a good workable
condition index is that it shouldbe relativelyeasyto obtain in the field, and for this reasonthe slightly lessreliablekidney fat index (KFD seemedpreferableto the buttock indices,as long askidney fat were presentthroughout the year. It was much quicker to obtain and was still
highly significurtly correlated with physical condition.
Its approdmate relationship to F/A and BF respectively
are givenby the following equations:F/A = 1,5 x KFI +
2 4 ; B F = 2 , 2 6x K F I + 5 , 5 .
Acknowledgements
Grateful acknowledgementis due to EA. Galpin,
R. Galpin and AJ. Fick for the supply of impala;
R J). Carr and D.G. Skinner for field assistance;Mn CJ.
Potgieterfor laboratory assistance;
Prof. J.MM. Brown,
Prof. K. van der Walt and Prof. DJJ. Potgieterand the
Director of the Researchlnstitute for Animal and Dairy
Science,Irene, for the use of variousresearchfacilities.
References
BROOKS, P.M., HANKS, J.-& LUDBROOK, J.V., 1977. Bone marrow as an index of condition in African ungulates.
S. Afr. J. Wildl. Res.7 ,61.
Nature, Ipnd. 195, 193.
BUTTERFIELD, R.M., 1962. Prediction of muscle content of steer carcasses.
CAUGHLEY, G., 1970. Fat reservesof Himalayanthar in New Zealandby season,sex, areaand age.N.Z. J. Sci. 13,
2W .
CIIAETLIM, E,L., 1949. Bone marrow as an index of malnutrition in deer. I/ew York Conserttationist3, 19.
50
COULOMBE, J.J- & FAUREAN, L., 1963. A new simple semi-micromethod for colorimetricdetenninationof urea.
Ct in.Chem .9 ,l 0 2 .
FALHOLT, K., LUND, B.& FALHOLT,W., 1973.Aneasy colorimetricmicromethodforroutine determinationof
free fatty acidsin plasma.Clin. Chim.Acta.46, 105.
FRANZMANN, A.W., LE RESCHE,R.E., ARNESON, P.D.& DAVIS, J.L., l976.Moose productivity and physiology.
AlaskaDept Fistrand Game,P-R Proj. final rep. W-17-R.87 pp. multilith.
HORWITZ, W., 1965. (Editor). Official methods of analysk of the Association of Official Agriculturol Chemists.
BenjaminFranklin Sta.Washington.9th Edn. 832 pp.
HUNTLEY, B.J., 197l. Seasonalvariation in the physicalcondition of maturemaleblesbokand kudu. J" S. Afr. Wildl.
M g m t . A s s .l , 1 7 .
K I N G S L E Y , G . R . ,1 9 4 0 .A r a p i d m e t h o d f o r t h e s e p a r a t i o n o sf e r u m a l b u m i n a n d g l o b u l i n . l . b i o l . C h e m
1 3. 3 , 7 3 1 .
MEISSNER, H.H. & BIELER, E.U., 1975. A note on the validity of usingcombinationsof predictiveequationsfor
estimatingbody compositionfrom tritiated water space.S. Afr. J. Anim. Scl. 5, 7.
NEILAND, K.A., 1970. Weight of dried marrow as indicator of fat in caribou femurs.J. Wildl. Mgmt. 34,904.
lean in maturebeef from
ORME, L.8., COLE, J.W.,KINCAID, C.M. & COOPER,RJ., 1960.Predictingtotal carcass
weightsof certainentire muscles.J. Anim. Sci. t9,726.
RANSOM, A.B., 1965.Kidney and marrow fat as indicatorsof white taileddeer condition.J. Wildl.Mgmt.29,397.
RINEY, T., 1955. Evaluatingcondition in free rangingred deer with specialreferenceto New Zealand.N.Z. J- Sci.
Technol.36 (B),429.
physical condition of some ungulates../. Wildl. Mgmt. 24,92.
RINEY, T., 1960. A field technique for assessing
SINCLAIR, A.R.E. & DUNCAN, P., 1972. Indices of condition in tropical ruminants.E- Afr. l'lildl. J. 10, 143.
E Afr. Wildl.J.8,123.
SMITH, N.S., 1970. Appraisalof condition estimationmethodsfor EastAfrican ungulates.
TALBOT, L.M., PAYNE, W.J.A.,LEDGER, HP., VERDCOURT,L.D.&TALBOT,M.H., 1965.The meat production
potential of wild animals in Africa. Tech. Comm. Commonw. Bureau Anim. Breed. Genetics,Edinb. 16,42pp.
VON LA CHEVALLERIE,M.& VAN ZYL,J.H.M., 1971. Growth and carcassdevelopment of the springbok
A n t idor cas mor suptalis marsupia lis, Zimmerrnann.Agro animolia 3, | | 5 .
WATSON, D. 1960. A simple method for the determination of serum cholesterol.Ain. Chim. Acta. 5, 637.
WOOTON, I.D.P., 1974. Microanalltsrsin medical biochemisny. Churchill, Livingstone,Edingburgh and London.
5t h E dn.3 0 7 p p .
51