Improvement of flesh quality in rainbow trout (Oncorhynchus mykiss) fed supranutritional dietary selenium yeast is associated with the inhibited muscle protein degradation

Supranutritional dietary selenium (Se) has been demonstrated beneficial for fish health, however, its effects on fish flesh quality remain unclear. This study investigated the effects of supranutritional dietary Se on the flesh quality of rainbow trout (Oncorhynchus mykiss) and their potential mechanism. Fish were fed a basal diet supplemented with or without graded Se yeast for 10weeks. Results showed that Se supplementation significantly increased fillet crude protein and enhanced fillet water-holding capacity as well as fillet firmness. Supplementing with both 2 and 4mg/kg Se significantly downregulated the expressions of two autophagy-lysosome-related genes (autophagy-related 12-like and gamma-aminobutyric acid type A receptor-associated protein-like 1) in fish muscle, while supplementing with 4mg/kg Se also significantly downregulated the expression of two ubiquitin-proteasome-related genes (muscle RING finger 2 and F-box protein 25). Correlation analysis indicated that the improved fillet quality parameters were closely correlated with the expressions of these differentially expressed genes. This study revealed that dietary Se was effective for the improvement of rainbow trout flesh quality, and the improved fish flesh quality was associated with the inhibited protein degradation in fish muscle.