title: Comparison of measured and estimated fat-free weight, fat, potassium and nitrogen of growing guinea pigs.
abstract: Total body water (TBW), potassium (TBK), nitrogen (N), and fat were measured chemically on 27 guinea pigs ranging in weight from 82-849 g. Measured fat-free wet weight (FFWW) is the difference between body weight and fat extracted with ether. Estimated FFWW is either TBW or TBK divided by a measured or assumed concentration of either water or K in the FFWW. The coefficients of correlation between measured and estimated values of FFWW were identical, r = 0.99 with the 3 different concentration values used for K. By paired t analysis there were significant differences statistically between measured and estimated FFWW with the K "constants" 68.1 and 62.5, but no difference with the "constant" 65.5. The correlation coefficients between measured and estimated FFWW from water were r = 0.96 with the "constant" 73.2 g/100 g FFWW, and r = 0.99 with the "constant" 76.0 g/100 g FFWW. By the paired t test, measured and estimated FFWW differed significantly only with the "constant" 73.2. In the calculation of fat from K concentrations, only the value 65.5 could be used. The coefficients of correlation for measured and estimated fat were significant, although low. There was no difference correlations between N and body cell mass, body weight and measured and estimated FFWW, and between body cell mass and body weight and measured and estimated FFWW. There was statistically no difference between measured and estimated N by the paired t test.
mesh_terms: D000818:Animals; D001835:Body Weight; D006168:Guinea Pigs / Q000254:growth & development* / Q000378:metabolism; D008055:Lipids / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D011188:Potassium / Q000032:analysis*
chemical_list: D008055:Lipids; D009584:Nitrogen; D011188:Potassium