Mitchell A D, Conway J M, Potts W J
Growth Biology Laboratory, ARS, USDA, Beltsville, MD 20705, USA.
J Anim Sci. 1996 Nov;74(11):2663-71. doi: 10.2527/1996.74112663x.
Dual-energy x-ray absorptiometry (DXA) was evaluated as a method for measuring body composition of pigs. Forty-eight female pigs (10.2 to 60.5 kg) were killed and the whole bodies scanned on a DXA instrument. The DXA measurements provided readings of total tissue mass, percentage of fat, fat tissue mass, lean body mass, and bone mineral content. By chemical analysis, the whole body fat content of the pigs ranged from 9.3 to 24.3%, giving rise to DXA RST values (ratio of attenuation coefficients) ranging from 1.386 to 1.334. The average percentage body fat measured by DXA (18.2 +/- .9%) was not significantly different (P = .76) from the results by chemical analysis (17.8 +/- .6%); however, concordance correlation analysis revealed unacceptable accuracy in the DXA measurement due to a negative bias for smaller percentages and a positive bias for larger percentages. Total body fat measured by the two methods was also highly correlated (r = .989), and the average for DXA (7.31 +/- .62 kg) was not significantly different (P = .89) from the value for the chemical method (7.20 +/- .50 kg). The relationship between the DXA estimate of lean body mass and the amount of protein in the body by chemical analysis was described by the equation: kg protein = .227.kg DXA lean -1.28, with a correlation coefficient (r) of .968. The DXA measurements of total tissue mass and actual body weights were highly correlated (r = .999), with an acceptable concordance at the .05 level. Scans were also analyzed for regional composition of the front and back legs. It was generally difficult to determine anatomically how well soft tissue described by DXA regions corresponded to those dissected. The DXA and chemical results for regional analysis of back legs were in better agreement than those for the front legs. These results indicate that DXA may be used as a reliable method for measuring body composition of pigs, but needs more extensive calibration and may be more appropriate for total body rather than regional analysis.
双能X线吸收法（DXA）被评估为一种测量猪体成分的方法。48头体重在10.2至60.5千克之间的雌性猪被宰杀，并在DXA仪器上对其全身进行扫描。DXA测量提供了总组织质量、脂肪百分比、脂肪组织质量、瘦体重和骨矿物质含量的读数。通过化学分析，猪的全身脂肪含量在9.3%至24.3%之间，导致DXA的RST值（衰减系数之比）在1.386至1.334之间。DXA测量的平均体脂百分比（18.2±0.9%）与化学分析结果（17.8±0.6%）无显著差异（P = 0.76）；然而，一致性相关性分析显示，由于较小百分比存在负偏差，较大百分比存在正偏差，DXA测量的准确性不可接受。两种方法测量的全身脂肪也高度相关（r = 0.989），DXA测量的平均值（7.31±0.62千克）与化学方法测量的值（7.20±0.50千克）无显著差异（P = 0.89）。DXA估算的瘦体重与化学分析得出的体内蛋白量之间的关系由以下方程描述：蛋白千克数 = 0.227×DXA瘦体重千克数 - 1.28，相关系数（r）为0.968。DXA测量的总组织质量与实际体重高度相关（r = 0.999），在0.05水平上具有可接受的一致性。还对前后腿的区域组成进行了扫描分析。通常很难从解剖学上确定DXA区域所描述的软组织与解剖后的软组织对应程度如何。后腿区域分析的DXA和化学结果比前腿的结果更一致。这些结果表明，DXA可作为测量猪体成分的可靠方法，但需要更广泛的校准，可能更适合全身分析而非区域分析。
