CROSS-CALIBRATION OF FAT AND LEAN MEASUREMENTS BY DUAL-ENERGY X-RAY ABSORPTIOMETRY TO PIG CARCASS ANALYSIS IN THE PEDIATRIC BODY-WEIGHT RANGE

The objective of this study was to cross-calibrate measurements of bod y composition by dual-energy X-ray absorptiometry (DXA) with chemical analysis of carcasses of pigs in the pediatric range of body weight. E ighteen pigs (25.5 +/- 7.0 kg; 9.9-32.8% body fat) were scanned in dup licate by using DXA with a Lunar DPX-L densitometer in the pediatric m edium and ii adult fast-detail scan modes. Pigs were then killed and t heir carcasses analyzed completely. Carcass lean and fat contents were highly correlated with DXA measurements in both scan modes (Pearson r values > 0.98). For lean mass, the relation between carcass content a nd DXA measures was not significantly different from the line of ident ity in the adult mode, but was in the pediatric mode. For fat mass, th e relations between carcass content and DXA measures were significantl y different from the Line of identity in both the adult and pediatric modes. In duplicate scans, the reliability of DXA measures of lean mas s and fat mass was excellent in both scan modes. Because neither the a dult nor the pediatric scan mode provided accurate measures of fat and lean mass, we derived specific correction factors to improve the meas urement of total fat and lean compartments, thereby calibrating the Lu nar DPX-L to the laboratory standard of carcass analysis in pigs.