Body composition analysis of pigs from 5 to 97 kg by dual-energy X-ray absorptiometry

A total of 231 pigs were anesthetized and then scanned by DXA using a Lunar DPXL instrument. The weight of the pigs ranged from 5 to 97 kg (av. = 37.7 kg). Of the total, 98 pigs were scanned using the pediatric mode and 133 pigs were scanned using the adult mode. After scanning, the pigs were euthanized entire body homogenized by grinding, and analyzed chemically for fat, water, protein and total body mineral content. The mean value for the DXA total tissue mass (37.1 kg) was not significantly (P>0.05, N = 231) different from the mean body weight. The mean DXA value for percent fat was 14.6 and was significantly less (P < 0.05) than the mean value (17.6%) measured by CHEM analysis. The greatest discrepancy occurred in pigs with < 15% body fat. From a prediction equation using the DXA R value [% fat = 493 − 349(DXA R value)], the DXA estimated percent fat was 18.0%, compared to 17.6% by CHEM analysis (P> 0.05). Using a prediction equation [g protein = −1.062 + 0.22 (g DXA lean)], the DXA estimate for body protein content was 17.8%, compared to 17.1% (P < 0.05, N = 131) by CHEM analysis. The DXA estimate for body water content [g water = 508 + 0.749(g DXA lean)] was 63.8%, compared to 62.6% (P < 0.05, N = 231) by CHEM analysis. The bone mineral content of 83 of the pigs measured by DXA was 2.40%, compared to 2.54% (P < 0.05, N = 83) estimated from CHEM analysis of total body ash [g bone MINERAL = g total body ash − 0.0085(g DXA lean)].