Effects of dietary yeast nucleotides on the growth performance and muscle quality of juvenile largemouth bass (Micropterus salmoides)

Abstract

This study explored the role of dietary yeast nucleotide (YN) on the growth performance and muscle quality of juvenile largemouth bass (LMB). Six experimental extruded diets containing 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0% of YN respectively were fed to LMB (7.03 ± 0.04 g) for 8 weeks. The results showed excellent growth performance that WGR of LMB fed 0.2% YN diet was significantly higher than the control and other treatment groups (P < 0.05). The YN groups had higher crude protein and serum total protein contents, but lower crude lipid and serum triglyceride levels than the control (P < 0.05). The higher accumulation of free essential amino acids, Thr, Asp, Glu, Lys and Met were observed in muscle of LMB fed YN diets. Free amino acids, free flavor amino acids, Asp, Glu, Pro, Lys and Ala in LMB muscle of 0.2% and 0.4% groups were significantly higher than the control (P < 0.05). Furthermore, polyunsaturated fatty acids and EPA in muscle were significantly higher in the YN group compared to the control (P < 0.05). The hardness, chewiness, and gumminess of the muscle in the LMB were enhanced when fed the YN diet. Gumminess was significantly higher in the YN group than in the control (P < 0.05). Additionally, there was a significant increase in both numbers and proportions of muscle fiber (< 20 μm) observed within the YN groups when compared to those within the control (P < 0.05), whereas intercellular space showed an opposite trend. The expression levels of MyoD, Myf5, and Myf6 genes were significantly higher in the YN group compared to the control at dietary levels ranging from 0.2% to 0.6% (P < 0.05). Based on the comprehensive evaluation of indicators, this study suggests that optimal dietary supplementation of YN is between 0.2% and 0.4%.

Keywords

• Micropterus salmoides
• Extruded feeds
• Growth performance
• Muscle quality
• Myogenic regulatory factors