We just finished a study on striped mice using doubly labelled water, estimating daily energy expenditure, fat free mass and fat mass.
We find surprisingly low fat mass and wonder whether this could be due to us using a wrong estimate for the hydration coefficient, i.e. % hydration of FFM (73.2%). Is it possible that in arid adapted rodents this value is lower?
Hi Carsten.
Studies have shown that hydration can range from 62% to 74% among bird and mammal species. See:
D. S. Reynolds, T. H. Kunz, in Body Composition Analysis of
Animals: A Handbook of Non-Destructive Methods, (Ed: J. R.
Speakman), Cambridge University Press, Cambridge,
2001, pp. 39–55.
Because there are species differences and issues with seasonal changes in adiposity, we calibrated a predictive equation based on isotope dilution and
morphometric data against proximate analysis when working with arctic ground squirrels.
For methods, please see:
Lee, TN, Fridinger, RW, Barnes, BM, Buck, CL and DM O’Brien. (2011) Estimating lean mass over a wide range of body composition: A calibration of deuterium dilution in the arctic ground squirrel. Rapid Communications in Mass Spectrometry. 25, 3491–3496.
Hi Carsten
I recommend you the book:
Extreme Measures. The ecological energetics of birds and mammals (2012) by Brian McNab from Florida Museum of Natural History in Gainesville, Florida.
There are a chapter about Life in hot dry and wram moist environments
You can find concepts, methods and data interpretations.
Thanks for all the replies.
But what we need is hydration of FFM, not water content of the whole body(which can be determined via DLW, but the calculation depends on the hydration coefficient).
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