EVALUATION OF THE CYCLOPROPANE ABSORPTION METHOD OF MEASURING AVIAN BODY-FAT

The mean absolute percent error of predicting the fat mass of 40 Rock Doves (Columba livia) by the cyclopropane absorption method was 11%. A sensitivity analysis of some of the 15 variables used in computing fa t mass by the cyclopropane absorption method showed that: (1) cloacal temperature was a good measure of body-fat temperature, (2) the lipid solubility coefficient of cyclopropane reported for rats was appropria te for pigeons, (3) minimum error occurred with an animal density of 1 .08, (4) error was relatively insensitive to a range of reasonable est imates of body water, and (5) the most accurate method of measuring ch amber volume was unclear. We list advantages and disadvantages of this user-unfriendly method and provide recommendations for future users. This method does not require a calibration based on fat extracted from dead birds; the accuracy and precision of a system assembled to measu re the fat mass of live birds can be evaluated with olive oil standard s. The accuracy of estimating fat mass of a living bird seems to be di ctated, in large part, by the analytical equipment and procedures used rather than by the bird.