Growth, fillet yield, and muscle quality traits are not affected by a genotype by diet interaction in rainbow trout consuming diets that differ in lipid content

In this study, selectively bred rainbow trout (Oncorhynchus mykiss) with improved fillet yield were reared on three commercially available diets that varied in dietary lipid content: low lipid (LL, 18%), moderate lipid (ML, 24%), and high lipid (HL, 29%-33%). The objective was to determine if a genotype by diet interaction affects product yield and muscle quality traits in high fillet yield (HY) and low fillet yield (LY) lines of rainbow trout. Main effects of the genetic line (p < 0.05) were observed for viscera yield, carcass yield, and fillet yield that were more favorable in the HY line. Analysis of muscle quality traits indicated that selection for fillet yield did not compromise fillet quality. A genotype by diet interaction (p < 0.05) was observed for viscera lipid content at the 2 kg harvest, for which viscera lipid content was similar between the HY and LY lines for the LL and HL diets, but greater (p < 0.05) in the LY line for the ML diet. Collectively, these findings indicate that higher product yields in the selectively bred HY line of rainbow trout will persist across diets with variable crude lipid/energy contents.