Growth and metabolic responses of juvenile largemouth bass (Micropterus salmoides) to dietary vitamin c supplementation levels

To investigate the growth and metabolic responses of largemouth bass (Micropterus salmoides) to dietary vitamin c supplementation levels, quadruplicate groups of 30 largemouth bass juveniles were fed eight experimental diets with graded level of VC in cages floated in concrete tanks for 60 days. The result showed that growth, survival rate and digestive enzyme activity were strongly positively influenced by AMP100, AMP125 and AMP150. Treatment AMP125 significantly (P < 0.05) enhanced growth compared with AMP0, AMP25, AMP50 and AMP75. Tissue VC increased as VC level in diet increased, whole body crude protein and moisture were influenced by dietary VC supplementation. Dietary VC significantly influenced muscle amino acid and hepatic amino acyl transferase activity. Furthermore, AMP100, AMP125, AMP150 and AMP175 significantly triggered the up regulation of Insulin-like growth factors (IGFs) and growth hormone (GH) gene mRNA expression level in liver and muscle compared with AMP0. Also, AMP125 and AMP150 maintained liver morphology. Nevertheless, dietary VC enhances digestive enzyme activity, hepatic amino acyl transferase activity and growth-related gene mRNA expression. Therefore, 120.46-145.35 mg/kg is adequate to improve the utilization of amino acid for growth, expression of growth-related genes and liver integrity in juvenile largemouth bass.

Automated summary

The study showed that AMP100, AMP125, and AMP150 significantly improved the growth, survival rate, and digestive enzyme activity of largemouth bass juveniles, as well as positively influenced the expression levels of related genes. Dietary vitamin C supplementation levels also affected tissue vitamin C content, body composition, and enzyme activity in the fish.