| Abstrakt: |
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, 78-1200 g) were anesthetized and scanned in both a lateral position and a dorsa-ventral position. Six individual fish (300-600 g) 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 (0-1 g) 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 ( P < 0.001). DXA overestimated LTM and underestimated FM and BMC. However, all three compartments were strongly correlated with carcass values ( P < 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 ( P > 0.05). DXA may also be a valuable tool for evaluating body condition longitudinally in commercial or in threatened or endangered fish species, where noninvasive procedures would be invaluable. [ABSTRACT FROM AUTHOR] |
