Evaluation of Bioelectric Impedance to Predict Carcass Yield, Carcass Composition, and Fillet Composition in Farm‐Raised Catfish

Abstract

Abstract.— Bioelectric impedance analysis (BIA) was evaluated as a method for predicting carcass yield, fat, and moisture in live channel catfish, Ictalurus punctatus (N = 20), and fat and moisture in fillets from channel catfish (N= 20) and channel catfish female × blue catfish male, I. furcatus, hybrids (N= 20). Fish were cultured in ponds, fed a commercial catfish diet (28% protein), and harvested at market weight (450 g‐900 g, ∼19 months post‐hatch). Live channel catfish were tranquilized, weighed, and sexed. Resistance and reactance were measured with a four‐terminal impedance analyzer. Fish were then deheaded, eviscerated, weighed, and carcass yield was calculated. Fillets from channel catfish and channel catfish × blue catfish hybrids were measured for weight, resistance, and reactance. Carcasses and fillets were ground and fat and moisture were determined by chemical analysis. Regression models including total weight, resistance, and reactance as independent variables explained 71%, 75%, and 65% of the variation in carcass yield, fat, and moisture, respectively, in live fish. Regression models with fillet weight, resistance, and reactance as independent variables explained 62% and 41% of the variation in fillet fat and moisture, respectively, in channel catfish, and 53% and 58% of the variation in fillet fat and moisture, respectively, in channel catfish × blue catfish hybrids. Models including resistance and reactance explained significantly more variation in the traits measured than did models containing only whole weight as an independent variable. Improvements in prediction accuracy will be needed to make BIA a useful tool for predicting carcass yield, carcass composition, and fillet composition in farm‐raised catfish.