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Subject:
From:
Loren Cordain <[log in to unmask]>
Reply To:
Paleolithic Diet Symposium List <[log in to unmask]>
Date:
Thu, 17 Aug 2000 12:38:51 -0600
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In my recent post regarding the total amount of body fat in a 44kg kangaroo,
I erroneously reported the total amount of body fat predicted by the Pitts
and Bullard regression (1).  A 44kg kangaroo with a predicted body fat of
8.2% would have 3608 g of total fat, not 360.8 g.  Hence, the difference
between the total predicted fat and the amount actually dissected would be
(3608 g -113 g) 3,495 g.  This figure represents the non-dissectable fat
that is bound in cell membranes in various organs and tissues.
        However, it is unlikely that a 44 kg kangaroo with only 113 g of
dissectable fat would have this much non-dissectable structural fat bound to
tissues and organs.  Hence, the Pitts and Bullard equation almost certainly
overestimates the total amount of body fat in this kangaroo.  Total body fat
can also be estimated by knowing the various weights of the major tissues
and their relative fat percent and then summing these values. Here's a table
of estimated values for this 44 lb kangaroo:

Tissue          % carcass wt.   Organ wt. (g)   %fat    total fat (g)
muscle          0.50            22,000          0.02    440
bones           0.13            5720            .03     172
liver, organs   0.075           3300            0.04    132
washed GI tract 0.06            2640            0.02     53
blood           0.012             526           0.02     11
marrow          0.004             176           0.51     90
brain           0.0014              62          .093       6
skin            0.13             5720           0.10     572
storage fat     0.0026            114           0.82      94
GI contents,
hair,nails etc  0.085           3740            na      na
Total           1.00            44000           na      1568

Consequently, in all likelihood this particular 44 kg kangaroo would have a
total body fat content of about 3.6% by weight if total carcass analysis
were done via chemical extraction.  With 3.6 % body fat, our 3rd order
polynomial equations (2)show that an animal with 3.6% body fat by weight
would have 27% fat by energy and 73 % protein by energy.
        Note that traditional Aborigines would have singed the hair from the
hide and eaten the skin, a rich source of fat.  Even still, the protein
content of this lean kangaroo would have caused protein toxicity, if a
carbohydrate (plant food source) were not available to dilute (in effect)
the excessive protein in this animal's body.



Loren Cordain, Ph.D., Professor
Department of Health and Exercise Science
Colorado State University
Fort Collins, CO 80523
tel: (970) 491-7436
fax: (970) 491-0445
email:[log in to unmask]
http://www.colostate.edu/Colleges/CAHS/ess/cordain.htm

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