
Enhancing fillet yield in rainbow trout-a key driver of economic efficiency in aquaculture-can be achieved through targeted selective breeding supported by advanced genomic tools, according to a recent study published in Marine Biotechnology.
Researchers at the USDA’s National Center for Cool and Cold Water Aquaculture have identified the genetic and physiological mechanisms behind higher fillet yield comparing the transcriptomic profiles of selectively bred rainbow trout lines.
Over the course of three generations of selective breeding, the team developed a high-yield line of rainbow trout that produced fillets with 2.5 percentage points more yield than a low-yield line, both derived from the same founder stock. Their findings suggest that this improvement stems from greater muscle cell proliferation during early growth stages and a consistent reduction in protein degradation throughout development.
What sets this study apart from previous work is its detailed transcriptomic anaylsis, which uncovers the biological mechanisms behind improved fillet yield-a trait often overlooked in favour of growth rate of feed conversion efficiency.
According to the authors, analyses of gene expression in muscle and liver tissue at three developmental stages- 2 grams, 60 grams, and 300 grams- revealed over 3,600 differentially expressed genes between the high-yield and low-yield lines. These differences were associated with greater muscle hypertrophy, more efficient energy metabolism, and reduced visceral fat in the high-yield fish.
By pinpoint the biological pathways and gene networks involved in these processes, the study offers valuable guidance for the development of genomic markers that could accelerate the selection of high-yield phenotypes in commercial breeding programmes.
“Our findings show that enhanced muscle yield in the high-yield line is driven by a combination of muscle cell hyperplasia during juvenile stages and reduced protein degradation throughout development,” the authors state.
These results mark an important step toward more efficient and sustainable rainbow trout farming, enabling producers to target fillet yield-a key determinant of profitability-with greater precision.