THE EFFECTIVENESS OF DUAL ENERGY X-RAY ABSORPTIOMETRY TO NON-INVASIVELY DETERMINE BODY COMPOSITION OF HYBRID STRIPED BASS

Abstract

The primary objective of this research project was to determine if dual energy x-ray absorptiometry was a valid method for non-invasively determining body composition of hybrid striped bass (Morone chrysops ♀ x. Morone saxatilis ♂). The first study utilized four dietary treatments to create a population with a broad range of body compositions. Fish were scanned using the Lunar model DPX-L dual energy x-ray absorptiometer in detailed medium and high resolution scan modes, manually analyzed for region of interest, in stacks, and scanned with a Hologic model QDR-4500A fan beam DXA. When compared to proximate analysis, results produced significant correlations and regression equations for: water and protein compared to lean, grams of fat, and ash compared to bone mineral composition. The second study utilized four dietary treatments of various energy:protein ratios to determine the ability of DXA to distinguish variations in body composition in accordance with dietary treatment. Fish were scanned with the Lunar model DPX-L DXA as well as the Lunar PIXImus DXA. The two scan values were compared to one another as well as to proximate analysis. Significant correlations and regression equations were calculated for the same comparisons as listed above. Fan beam DXA was less reliable as a predictor of body composition than pencil beam, and there was no difference between values from scan modes for the pencil beam DXA. PIXImus DXA was limited by size of the scan area, but was as successful as the larger pencil beam method for predicting certain parameters of body composition.