Johnson Maria S, Watts Randall J, Hammer Hugh S, Nagy Tim R, A Watts Stephen
Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294-3360.
Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294-1170.
J World Aquac Soc. 2017 Feb;48(1):122-131. doi: 10.1111/jwas.12324. Epub 2016 Jul 4.
Dual-energy X-ray absorptiometry (DXA) provides a noninvasive way to determine lean tissue mass (LTM), fat mass (FM), bone mineral content (BMC), and bone mineral density (BMD) in humans and small mammals. Live channel catfish (n=74, 78g - 1200 g) were anesthetized and scanned in both a lateral position and a dorsa-ventral position. Six individual fish (300g - 600g) were scanned five times each to determine precision by the coefficient of variation. Precision was good for LTM (0.75-1.06%) and for BMC and BMD (2-2.6%). Precision for FM was not good (27-34%), which was due to the very low FM (0-1g) recorded by the DXA. However, using the predicted values, FM precision improved to 5-5.5%. DXA values for LTM, FM, and BMC were significantly different from chemical analysis (< 0.001). DXA overestimated LTM and underestimated FM and BMC. However, all three compartments were strongly correlated with carcass values ( <0.0001). Using the prediction equations and the jackknife procedure, predicted values of LTM, FM, and BMC were not significantly different from the carcass values ( >0.05). DXA may also be a valuable tool for evaluating body condition longitudinally in commercial or in threatened or endangered fish species, where non-invasive procedures would be invaluable.
双能X线吸收法（DXA）提供了一种非侵入性方法，用于测定人类和小型哺乳动物的瘦体重（LTM）、脂肪量（FM）、骨矿物质含量（BMC）和骨矿物质密度（BMD）。将活体沟鲶（n = 74，78克 - 1200克）麻醉，并分别在侧位和背腹位进行扫描。对6条个体鱼（300克 - 600克）每条扫描5次，通过变异系数确定精密度。LTM（0.75 - 1.06%）以及BMC和BMD（2 - 2.6%）的精密度良好。FM的精密度不佳（27 - 34%），这是由于DXA记录的FM非常低（0 - 1克）。然而，使用预测值后，FM精密度提高到了5 - 5.5%。LTM、FM和BMC的DXA值与化学分析结果显著不同（< 0.001）。DXA高估了LTM，低估了FM和BMC。然而，所有三个部分与胴体值都有很强的相关性（<0.0001）。使用预测方程和留一法，LTM、FM和BMC的预测值与胴体值没有显著差异（>0.05）。对于商业养殖的或受威胁或濒危鱼类物种，DXA也可能是一种评估其纵向身体状况的有价值工具，因为非侵入性程序将非常宝贵。
