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Estimation of body fat in female rhesus monkeys.

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Estimation of Body Fat in Female Rhesus Monkeys
Yerkes Regional Primate Research Center (M.L.W ,S.M.S., M.E. W.) and
Department of Medicine (S.M.S.,
PI.M.%Emory University, Atlanta.
Gebrgia 30322
KEY WORDS Body fat, Rhesus Monkey, Tritiated water,
Morphometric measurement
Measurement of height (crown-rump length), body weight,
and abdominal subcutaneous fat depth, based on skinfold thickness taken from
13 female rhesus monkeys comprising two age groups were correlated with
body fat values derived from tritiated water determinations of total body
water. The manner with which each measure was related to percent body fat
differed as a function of age of the animal. In the young, nulliparous females,
crown-rump length was the single best predictor of body fat, whereas in the
older, multiparous females, skinfold thickness correlated most highly with
body fat. When all measurements, including the Quetelet index [(Wtkt? x
1,0001, were combined statistically and regressed against percent body fat, a
significant increase in predictive ability was obtained. When each age group
was considered separately, the resulting equations again reflected the agegroup biases. In addition, as an internal check on the validity of the regression
equations, an additional regression analysis was performed using morphometric data from selected animals in each age group. These equations yielded
accurate estimates of body fat when compared to determinations made from
total body water. These analyses indicate that the predictive accuracy of
morphometric data is greatly enhanced by using these measurements in concert. Furthermore, the utility of such predictions is influenced by the specific
physical characteristics of the subject population.
The estimation of body fat in primates has
generally been inferred from measurements
of body weight (Durnin and Rahaman, 1967;
Wilmore and Behnke, 1970;Young and Blondin, 1962). However, body weight does not
necessarily provide an accurate estimate of
body fat, since such factors as height, age,
sex, muscle mass, and bone density can differentially contribute to the weight measurement and thereby reduce the accuracy of body
fat estimates (Broxek, 1961). To overcome
these obstacles, some investigators have employed more direct methods of assessing relative adiposity. Measurement of subcutaneous fat depth in macaques using skinfold
calipers (Small, 1981; Walike et al., 1977) has
been found to provide reliable data, although
this technique is limited by its inability to
measure fat depth in a range of less than 2
mm (Hansen, personal communication), and
by changes in skinfold compressibility which
occur with old age (Broxek and Kinzey, 1960).
Ultrasonic measurement of fat has been employed successfully in humans (Bullen et al.,
1965; Haymes et al., 1976), although it has
yet to be validated for use in nonhuman primates. Other techniques, such as soft-tissue
roentgenograms, carcass analysis, and water
submersion, are unsuitable or economically
impractical in nonhuman primates. One additional method, the measurement of total
body water (Schloerb et al., 19501, has been
adapted for use in macaques (Kamis and Latif, 1981; Walike et al., 19771, and this technique appears to provide valid estimates of
body fat in monkeys.
Received September 16, 1983; revised November 17, 1983; accepted November 28,1983.
The ability to obtain accurate estimates of
body fat is critically important to such areas
of research as nutrition, development, and
reproduction. For this reason, estimates of
adiposity derived from morphometric data
must be validated against actual determinations of body fat, since such measures alone
can only provide data regarding relative differences among subjects. Furthermore, since
body composition may change as a function
of development, certain age-related factors
must be taken into account. To this end, measurements of height (crown-rump length),
weight, and abdominal subcutaneous fat
depth based on skinfold thickness and ultrasound were made in 13 female rhesus monkeys comprising two age groups. The ability
of these measures to estimate body fat accurately was established by means of multiple
regression against percent body fat derived
from total body water determinations. The
regression equations thus generated provide
a useful and practical index for the noninvasive assessment of percent body fat.
Thirteen female rhesus monkeys (Macaca
mulatta) housed at the Yerkes Primate Center Field Station served as subjects. These
animals were selected because they represented two distinct groups with regard to
size, age, and reproductive status. The two
groups were (1)nulliparous females (n = 6)
- mean age of 3.22 years ( & .02 years) and
(2) multiparous females (n = 7) - mean age
of 8.82 years ( & .52 years). All females were
members of mixed-sex social groups housed
in outdoor compounds. However, for the purposes of the present study, the animals were
moved indoors 24 hours prior to the study
onset and housed in individual cages. Upon
completion of the experiment, the animals
were returned to the original social groups.
Since this study was conducted during the
nonbreeding summer months, all subjects
were anovulatory and none of the adult females was pregnant or lactating.
The height, weight, and abdominal subcutaneous fat depth measurements were made
on anesthetized animals (ketamine HC1, 5
mgkg) in order to minimize measurement
error. All such measurements were made in
duplicate. Except when otherwise stated, food
and water were made available to the animals on a n ad lib schedule.
Crown-rump Length. Height measurements (cm) were made using Vernier anthropometric calipers (Gneupel, Switzerland)
according to the method outlined by Schultz
(1929). One end of the calipers was placed on
the cranial vertex (the highest point of the
head in the midsagittal plane) and the other
was positioned on the buttocks at the midline
of the horizontal plane which bisects the ischial callosities.
Subcutaneous Fat Depth. Subcutaneous fat
depth (mm) was measured using large skinfold calipers (Cambridge Scientific Instruments, Cambridge, MD). The calipers were
placed a t a point on the lower abdomen a t
the midline, approximately 2 cm below the
umbilicus. Ultrasound measurement (Scanoprobe, Model 731A, Ithaco, Ithaca, NY) of
subcutaneous fat depth (mm) was made at
the identical site on the abdomen. This site
was chosen because preliminary data had
revealed that triceps and subscapular sites
yielded unreliable measurements due to the
lack of fat deposits in these areas.
Body Weight. Body weight measurements
(Fairbanks Digital Scale, Model H90-7601,
Colt Industries, St. Johnsbury, VT) were
taken from animals that had been fasted for
approximately 16 hours. These measurements were recorded in kilograms (kg). The
height and weight measurements were also
incorporated into,the Quetelet index [(body
wt/htP x 1,000], since this index has been
found to provide a n unbiased estimate of adiposity (Billewicz et al., 1962; Keys et al.,
Total Body Water Determination. This determination was conducted according to a
modification of procedures described earlier
(Kamis and Latif, 1981; Schloerb et al., 1950;
Walike et al., 1977). The animals were deprived of food and water 16 hours prior to the
initiation of this procedure. A pretreatment
blood sample (3 ml) was obtained in the manner described previously (Walker et al., 1982).
The animals were then immediately administered a n injection into the saphenous vein
of 4 pCikg tritiated water (3HzO: Amersham
Corporation, Arlington Heights, IL).Four 3ml samples of blood were drawn from these
animals a t 30 minutes, 1, 2, and 3 hours
postinjection, by which time equilibration of
the tracer was completed. The blood samples
were obtained without anesthesia, and the
sera were separated by means of centrifugation and stored at -20" until later analysis.
The fecal material and urine were collected
from these animals for safe disposal and the
animals were not returned to their outdoor obtain the counting efficiency for each unsocial groups until their urinary radioactiv- known serum sample based on its AES ratio.
Total body water (TBW) was determined
ity had fallen to a level < .03 pCi/ml.
In order to determine the precise water according to the following calculation (Friiscontent of the serum, a 2-ml serum sample Hansen, 1957):
from each female was pipetted into a small
TBW = C1V1/C2,
glass scintillation vial. The gross weight of
C1-concentration of in‘ected 3H20,
the vial and serum was recorded and the
V1-volume of injected3! H20,
samples were then placed in a dry-ice bath
Cz-concentration of 3 ~ 2
and frozen. Once the serum samples reached
a t equilibrium.
a solid state, they were placed in a lyophilizer and freeze-dried. Complete lyophilization of the samples required approximately
2.5 hours, after which time the samples were As seen in Figure 1, equilibration of the
removed and reweighed. The percent water tracer was completed by 30 minutes postinin the serum samples was derived from the jection; hence the equilibrium value used in
ratio of dry to wet weights and ranged from all calculations represents a mean from the
87.7% to 90.1%. To determine whether the 1-, 2-, and 3-hour samples.
Computation of Total Body Fat. Lean body
percent water in the samples was underestimated by using gross weight in the calcula- mass (LBM) and total body fat (TBF) were
tions (i.e., including the weight of the bottle), indirectly determined using the constant,
two lyophilized serum samples were rehy- 73.2, as the percent of water normally found
drated and pipetted into other vials. The in fat-free mammalian tissue (Behnke, 1941;
original vials were washed with ethanol and Moulton, 1923). Based on the calculation of
distilled water and then allowed to air-dry. TBW, percent body fat (%BF) was computed
The bottles were then weighed and the according to the following formulae (Schloerb
amount of water in the serum was recalcu- et al., 1950):
lated using net weights. The use .of gross
versus net weights yielded a mean difference 1)LBM = TBW/0.732
of .02% in the estimation of the water con- 2) TBF = Body Weight (BW) - LBM
tent, which is well within the range of nor- 3) %BF = TBFBW
mal measurement error. Since the specific
Data Analysis
activity of the water in the serum was used
from these measurements
in the calculations, the volume of serum was
corrected by the percent water in serum for were analyzed using a stepwise regression
analysis (Kerlinger and Pedhazur, 1973).
each female.
To measure the specific activity in the Simple correlational relationships between
serum samples, 500 p1 of serum was placed two variables were analyzed using Pearson
into microvials with 5 ml of commercial scintillation cocktail. The effect of quenching on
counting efficiency was determined by pipetting increasing volumes of nitromethane (0,
2 , 4 , 6 , 8 , 10,20,25 1) into scintillation vials
containing 7.9 x 10 disintegrations per minute (dpm) of 3H20. Nitromethane was used
because empirical studies demonstrate that
this compound yields quenching similar to
biological fluids and is highly stable over
time. Samples were counted in a liquid scintillation spectrometer (Packard Corporation)
and the automatic external standard (AES)
ratio, as well as the dpm’s, were obtained for
each. A quench curve plotting the AES ratio
versus counting efficiency was generated,
yielding a linear relationship (r = .995; a =
.068; b = 1.983). The counting efficiency for
Fig. 1. The specific activity in serum of the nullipathe quench curve ranged from 4.1%(25 pl) to rous and multiparous females a t 0 minutes (preinjection)
30.0%(0 pl). This quench curve was used to and 30,60,120, and 180 minutes post 3Hz0 injection.
TABLE 1. Morphometric data, including X (+ SEMI and ranges, for two age classes of female rhesus monkeys
(n = 6)
(n = 7)
BodyTotal body
Lean body
crn _ _ - _ kg
~ - - _ _
_ _ _ _ liters
1.7- 2.0
product-moment correlations (r). The two
groups of subjects were treated statistically
both individually and conjointly. Differences
between groups were analyzed using a t test
for independent measures. Data are presented as X -t SEM.
The basic morphometric data for both the
nulliparous and multiparous females are
given in Table 1. Determinations of subcutaneous fat depth using ultrasound were excluded, since this instrument was not
sufficiently sensitive to allow for the measurement of shallow fat depth and thus did
not discriminate among individuals. As can
be seen from these data, the multiparous females were, as expected, heavier, taller, and
fatter than nulliparous females.
The relationship among these morphometric measurements and estimates of body fat
for all females is shown by the correlation
matrix depicted in Table 2. As can be seen
from this table, all of these morphometric
measures were highly interrelated (P < .05).
Skinfold thickness correlated most highly
with percent body fat (r2 = .go), whereas
crown-rump length accounted for only 50%
of the variance in predicting percent body fat
(r2= 50). On the basis of these correlations,
skinfold thickness appears to be the single
best predictor of percent body fat, but either
body weight or the Quetelet index or crownrump length alone correlates well enough for
each to be a useful predictor.
Interestingly, the predictability of these
measures changed when the two groups of
females were considered separately. As seen
in Table 3, crown-rump length and percent
body fat were most highly correlated (r2 =
.86, P < .05) in nulliparous females. In multiparous females, however, these two variables correlated quite poorly (2 = .08, P >
.05). A similar disparity in the prediction of
percent body fat was found when skinfold
Body fat
TABLE 2. A correlation matrix depicting the
relationship among the measurements of skinfold
thickness (SF), crown-rump length (CR), body weight
(B W), the Quetelet index (QI),and percent body fat
(%BF) for all females
TABLE 3. A correlation matrix depicting the
relationship among the measurements of skinfold
thickness (SF), crouln-rump length CCR), body weight
IB W), the Quetelet index (QO, and percent body fat
i .38
'Those values above the diagonal represent the correlations
from nulliparous females whereas those helow the line are from
multiparous females.
thickness was used as the predictor. In multiparous females, skinfold thickness and percent body fat correlated highly (r2 = .96; P
< .05),whereas in nulliparous females, these
variables were nonsignificantly related (r2 =
.20, P > .05).
When all animals were included in a multiple regression analysis, a highly significant
relationship was found amon these morphometric measures (R = .97; R8 -- .94; F p g )
= 48.14, P < .Ol), yielding the following
+ 1 . 3 ~ +1 .39X2
+ (- 1 2 . 8 ) ~ ~
where: x1
x2 =
x3 =
skinfold thickness,
crown-rump length,
body weight.
The Quetelet index did not contribute significantly to the prediction of percent body fat
and was thus statistically excluded from the
regression equation. As with the simple correlations, the regression equation took a
somewhat different form when the data were
analyzed with the nulliparous and multipar o w females considered separately. The linear combination of height, weight, skinfold
thickness, and the Quetelet index regressed
against percent body fat in multiparous females yielded a correlation coefficient indicative of a strong linear relationship among
these variables (R = .99; R2 = .98; F(3,3).=
43.27, P < .01). However, the degree to which
each variable contributed to the equation differed from that found when the data from all
subjects were included in the analysis:
11.86 + 1.42x1
+ . 6 3 ~ 2+ (-2.17)x3
where: x1
skinfold thickness,
Quetelet index,
body weight.
Crown-rump length in multiparous females,
however, did not contribute sufficiently to
the predictability of the regression equation
to satisfy the criteria for statistical inclusion.
A similar stepwise regression analysis in
nulliparous females indicated that a highly
significant relationship exists among percent
body fat and height and skinfold thickness
(R = .97; R2 = .94; F(2,3)= 23.63, P < .05):
Y = -52.0 + 5.65~1+ 1 . 0 5 ~ 2 (7)
where: x1 = crown-rump length,
x2 = skinfold thickness.
However, in these females, neither the Quetelet index nor body weight contributed significantly to the equation.
To illustrate the difference between the
regression equations generated for the nulliparous and multiparous females, percent
body fat was predicted for each group using
the regression equation of the other group.
The mean predicted percent body fat for the
nulliparous females, using the regression
equation generated from data on multiparous females, was 11.2%(k.3) as compared to
the actual mean percent body fat of 7.8%
(+ 1.2).The difference between the two groups
in the observed versus predicted values was
significant (t(5) = -2.43, P < .05). The converse analysis was also performed in which
percent body fat for multiparous females was
predicted from the regression equation generated from the nulliparous females. The
predicted mean percent body fat was 37.7%
(*lO.l) as compared to the observed mean of
18.3% (k2.9), with the difference again being statistically significant (t(6) = -2.65,
P < .05).
As a n internal check of the validity of the
regression equations, two females were randomly selected from each group. Using data
from the remaining females, new regression
equations were generated. Actual body fat
measures then were compared to estimates
obtained from the new regression equations.
The observed mean percent body fat for the
two nulliparous females was 9.5% (f1.6)
compared to the predicted mean of 8.5%(5.2).
The observed mean percent body fat for the
two multiparous females was 19.3% (k4.5)
compared to the predicted mean of 23.8%
The present analyses indicate that, when
taken in concert, morphometric measures can
provide valid estimates of percent body fat in
nonhuman primates. Although such estimates can be obtained from measures of
height, weight, and abdominal subcutaneous
fat depth, the utility of each may vary a s a
function of the particular physical characteristics of the subject population. When
younger, nulliparous and older, multiparous
females were treated statistically a s a homogeneous group, the correlation of percent
body fat with skinfold thickness and body
weight revealed a strong linear relationship.
In fact, skinfold thickness has been shown
previously to correlate most highly with adiposity in pigtailed macaques (Mucucu nemestrinu), with the strongest relationship
between body fat and skinfold thickness obtained from obese females (Walike et al.,
1977). Our data concur with this finding,
since in multiparous females, who tended to
weigh more and have greater subcutaneous
fat depth, the correlation between skinfold
thickness and percent body fat was much
higher than in smaller nulliparous females.
Certain disparities in the predictive relationship among such morphometric measures as
body weight, crown-rump length, and skinfold thickness have been found to occur in
subjects who are at the extremes of age,
height, and weight (Damon and Goldman,
1964). As can be seen from our data, the
range in skinfold thickness measures in the
nulliparous females was quite small. Evidently, due to a truncation in skinfold thickness values, this measure is a very poor
predictor in young females when used alone.
Moreover, since the lower limit of accurate
measurement of skinfold thickness is approximately 2 mm (Hansen, personal communication), young females are ill-suited to this
sort of morphometric estimation of body fat.
Instead, crown-rump length, which correlated most highly with percent body fat in
this age group, is a better predictor of percent
body fat in younger females.
In multiparous, fully adult females, skinfold thickness was a n excellent predictor of
percent body fat. Body weight and the Quetelet index also correlated highly with determinations of body fat. On the other hand,
crown-rump length correlated very poorly
with percent body fat, despite a wide range
of heights in these females. Furthermore, the
prediction of body fat derived from the
regression equation from the inappropriate
age group (i.e., predicting nulliparous values
from the multiparous regression equation
and vice versa) yielded widely disparate values for predicted and observed percent body
fat. In contrast, when data from both nulliparous and multiparous females were used
in the regression equations, estimates of body
fat were similar to actual measurements.
These data reemphasize the necessity to distinguish a priori the physical traits of the
animals and to select measurement techniques accordingly. In addition they illustrate that when using established regression
equations to generate estimates of body fat,
the population from which the equations are
derived must encompass the full range of
physical characteristics represented by the
population to be estimated.
The total body water method for determining body fat seems particularly well suited
for use in rhesus monkeys since the fraction
of water in fat-free tissue in smaller animals
has been found to be relatively constant (Pace
and Rathbun, 1945; Pitts, 1956). Whatever
measurement error results from total body
water determinations is generally dismissed
as simply reflecting irreducible variability in
individual body composition (Siri, 1961), although the degree of experimental error is
proportionately larger in smaller animals. In
addition, determinations of body fat from total body water is more practical than other
techniques such as carcass analysis, water
submersion, and soft tissue roentgenograms.
The high predictive accuracy between the
observed and predicted body fat estimates, as
generated from the regression equations, underscores the validity and general applicability of this method. In fact, our work generally
concurs with the finding in humans of a linear increase in percent body fat occurring
with age (Friis-Hansen, 1957).
This study illustrates that indirect assessments of morphology in macaques can provide accurate estimates of body composition,
circumventing the need for more invasive
and laborious techniques. Furthermore, multiple morphometric measures, taken in combination, provide more accurate estimates of
body fat than single measures taken alone.
The method of choice is a matter requiring
consideration of the developmental status of
the animals.
The authors would like to thank Dr. Barbara Hansen for her helpful advice and support. We would also like to thank Louise
Wright for her editorial assistance and
Thomas P. Gordon for his comments. This
work was supported, in part, by NSF grant
BNS13248, NIH grants RR00165, HD16305,
and VA Project 1517-005.
Behnke, AR (1941) Fat content and composition of the
body. Harvey Lect. 37:198-226.
Billewicz, WZ, Kemsley, WFF, and Thomson, AM (1962)
Indices of adiposity. Br. J. Prev. SOC.
Med. 16t183-188.
Brogek, J (1961)In J Brozek and A Henschel (eds): Techniques for Measuring Body Composition. Washington,
D.C.: Nat. Acad. Sci. Natl. Res. Council, pp. 3-35.
Brogek, J, and Kinzey, W (1960)Age changes in skinfold
compressibility. J. Gerontol. 15:45-51.
Bullen, BA, Quaade, F, Olesen, E, and Lund, SA (1965)
Ultrasonic reflections used for measuring subcutaneous fat in humans. Hum. Biol. 37:375-384.
Damon, A, and Goldman, RF (1964) Predicting fat from
body measurements: Densiometric validation of ten
anthropometric equations. Human Biol. 36:32-44.
Durnin, JV,and Rahaman, MM (1967) The assessment
of the amount of fat in the human body from measurements of skinfold thickness. Br. J. Nutr. 21;681-689.
Friis-Hansen, B (1957) Changes in body water compartments during growth. Acta Paediatrica 46:l-68.
Haymes, EM, Lundegren, HM, Loomis, JL, and Buskirk,
ER (1976) Validity of the ultrasonic technique as a
method of measuring subcutaneous adipose tissue.
Ann. Human Biol. 3:245-251.
Kamis, AB, and Latif, NB (1981) Turnover and total
body water in macaque (Macaca fascicularis) and gibbon (Hylobates lar). Comp. Biochem. Physiol. 70Ar4546.
Kerlinger, FN, and Pedhazur, E J (1973)Multiple Regres-
sion in Behavioral Research. New York: Holt, Rinehart
and Winston, Inc.
Keys, A, Fidanza, F, Karvonen, MJ, Kimura, N, and
Taylor, HL (1972) Indices of relative weight and obesity. J. Chron. Dis. 25:329-343.
Moulton, CR (1923) Age and chemical development in
mammals. J. Biol. Chem. 57:79-97.
Pace, N, and Rathbun, EN (1945) Studies on body composition. 111. The body water and chemically combined
nitrogen content in relation to fat content. J. Biol.
Chem. 158:685-691.
Pitts, GC (1956) Body fat accumulation in the guinea
pig. Am. J. Physiol. 185:41-48.
Schloerb, PR, Friis-Hansen, BJ, Edelman, IS, Solomon,
AK, and Moore, FD (1950) The measurement of total
body water in the human subject by deuterium oxide
dilution. J. Clin. Invest. 29:1296-1310.
Schultz, AH (1929) The techniques of measuring the
outer body of human fetuses and of primates in general. Contrib. Embryol. Carnegie Inst. Washington
Siri, WE (1961) Body composition from fluid spaces and
density: Analysis of methods. In J Brozek and A Henschel (eds): Techniques for Measuring Body Composition. Washington, DC: Nat. Acad. Sci. Natl. Res.
Council, pp. 223-244.
Small, MF (1981) Body fat, rank and nutritional status
in a captive group of rhesus macaques. Int. J. Primatol.
Walike, BC, Goodner, CJ, Koerker, DJ, Chideckel, EW,
and Kalnasv. LW (1977) Assessment of obesitv in Dietailed maca&es (~I?ucacanemestrinu). J. Med Prikatol. 6:151-162.
Walker, ML, Gordon, TP, and Wilson, ME (1982) Reproductive performance in capture-acclimated female rhesus monkeys (Mucuca mulattd. J. Med. Primatol.
Wilmore, JH,and Behnke, Ar (1970) An anthropometric
estimation of body density and lean body weight in
young women. Am. J. Clin. Nutr. 27:267-274.
Young, CM, and Blondin, J (1962) Estimating body
weight and fatness in young women. J. Am. Dietetic
Assoc. 41:452-455.
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