Validation of Dual‐energy X‐ray Absorptiometry to Predict Body Composition of Channel Catfish, Ictalurus punctatus

Abstract

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 (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 non-invasive procedures would be invaluable.

Assessing body composition and dietary phosphorus retention using Dual‐energy X‐ray absorptiometry (DXA): Application on juvenile rainbow trout, Oncorhynchus mykiss (Walbaum)

“…When data from the two groups (frozen and thawed) were analysed separately, this difference was lower when fish were frozen (CV min‐max = 0.31–5.2 and 0.81–10.3 for frozen and thawed fish respectively). This strong fit is in accordance with other studies performed in broilers (CV = 0.5–1.1; Mitchell et al, 1997), rats (CV = 2.2; Lu et al, 1994), channel catfish (CV = 0.33–0.40; Johnson et al, 2017) and in striped bass (CV = 6.1–13.4; Wood, 2004).…”

“…There was also a weaker relationship in the thawed carcass (Frozen/thawed × Time, p < .001). This poor prediction of fat carcass content by DXA has already been reported in channel catfish (Johnson et al, 2017) and hybrid striped bass ( M. chrysops × M. saxatilis ; Wood et al, 2004) with R 2 of 27 to 34 and 50 to 55% respectively. Additionally, the relationship between DXA fat estimates and analytical crude lipid is mostly influenced by frozen/thawed conditions ( p < .001) and although both increase with time ( p < .001), the relationship is different (Frozen/thawed x Time, p = .012; Figure 1b).…”

“…The interest in understanding body composition dynamics points to the importance of having adequate tools to estimate the chemical composition of whole‐body fish. Traditionally, dissection has been used to isolate lean, fat and bone tissue deposition (Soladoye et al., 2016), and chemical analyses of the carcass composition are still thoroughly employed (Johnson, Watts, Hammer, Nagy, & Watts, 2017; Wood, 2004; Lovett et al., 2019).…”

“…Its principle has been widely described in the literature (Brienne, Denoyelle, Baussart, & Daudin, 2001; Jebb, 1997) and its accuracy demonstrated in pigs (Pomar & Rivest, 1996; Scholz, Mitchell, Förster, & Pursel, 2007), broilers (Mitchell, Rosebrough, & Conway, 1997; Shim et al., 2012) and beef (rib carcasses; Mitchell, Solomon, & Rumsey, 1997). In fish, few studies have been conducted to validate DXA accuracy for estimation of whole‐body composition (Johnson et al, 2017; Lovett et al., 2019; Wood, 2004). These reports concluded that DXA appears to be a viable tool for assessment of whole‐body composition for king salmon, channel catfish and hybrid striped bass.…”

Validation of Body Condition Indices and Quantitative Magnetic Resonance in Estimating Body Composition in a Small Lizard

“…However, validation of these methods has yielded mixed results and their accuracy of predicting body composition of small animals (<25 g) is poor and understudied (Fischer et al., ; Scott et al., ). Dual‐energy X‐ray absorptiometry has been validated in snakes (Secor and Nagy, ) and fish (Johnson et al., ) and is more easily and accurately used for measuring body composition than TOBEC and cyclopropane gas. Bioimpedance spectroscopy has also shown excellent accuracy in predicting TBW, fat‐free mass, and fat mass in rats (Smith et al., ).…”