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

Abstract

Dual‐energy X‐ray absorptiometry (DXA) was evaluated to estimate body composition of rainbow trout (Oncorhynchus mykiss), with an emphasis on phosphorus (P) retention. Ninety rainbow trout (36‐136 g) fed with control (1.10%) or low‐P (0.55%) diets were scanned using a DXA instrument, both frozen and thawed. Whole‐body scans were analysed using the ‘rat whole body’ scan mode. Chemical analyses determined crude lipid and crude protein, water, ash, phosphorus (P) and calcium (Ca). Except for lipid, DXA predicted accurately body composition. The prediction capabilities of the model were assessed by comparing actual and simulated body composition using the generated equations. Results showed good agreement except for lipid and P for which adjusted equations were proposed resulting in highly improved predictions. To predict total carcass P, P retention/excretion, an equation predicting body P was developed and adjusted based on the validation (Body P [g] = −0.087 + 0.103 [BMC] + 0.00336 [lean], R2 = .91, p < .001). Retention and loading estimates for P using models from DXA are similar to those from chemical methods. Our results suggest that DXA can estimate body content of protein, moisture, ash and P; refinement is needed to predict body lipid content.

Genetic Parameters and Genome-Wide Association Studies of Quality Traits Characterised Using Imaging Technologies in Rainbow Trout, Oncorhynchus mykiss

“…Our study mainly targeted the development of muscle and adipose tissues. However, processing yields can be strongly affected by bony tissues, for which alternative technologies such as X-ray tomography ( Ceballos-Francisco et al, 2020 ) or Dual-energy X-ray absorptiometry ( Ndiaye et al, 2020 ) may be useful in characterising development or in predicting the relative phosphorus composition of carcasses.…”

Dual-energy X-ray absorptiometry: an effective approach for predicting broiler chicken body composition

“…The equipment software uses the reduction of the dual X-ray beam caused by distinct absorbing materials to estimate the values of total tissue, soft lean tissue ( SLT ), fat tissue, bone mineral content ( BMC ), and fat percentage in the projected figures ( Schallier et al, 2019 ). DEXA has been proven useful in animal science; its application varies between prediction of intramuscular fat in beef steak ( Nunes et al, 2023 ), body composition of swine ( Soladoye et al, 2016 ; Kasper et al, 2021 ), body composition and phosphorus retention in rainbow trout ( Ndiaye et al, 2020 ), mineral density and content in laying hens ( Hester et al, 2004 ; Schreiweis et al, 2004 ), broiler bone resistance ( Shim et al, 2012 ), and growth performance ( Castro et al, 2019 ; Meyer et al, 2019 ). Furthermore, DEXA is a promising noninvasive method for longitudinal studies to determine fast heating production, and consequently net energy requirements of chicken growth ( Martinez et al, 2022a ; Suesuttajit et al, 2022 ), and longitudinal studies about potential body growth of broiler and pullet strains ( Alves et al, 2019 ; Gonçalves et al, 2020 ).…”