Dietary lysine affects growth performance, whole-body composition and growth-related gene expression in the yellow drumNibea albiflora

Excess and deficient dietary lysine intake can have negative impacts on fish growth, emphasizing the importance of developing species-specific formulations. A 50-day feeding experiment was conducted to evaluate the optimal dietaryl-lysine demand for juvenileNibea albiflora. Fish were fed six diets, in which thel-lysine content was 13.1, 18.1, 23.1, 28.1, 33.1 and 38.1 g/kg dry diet (measured values). The 18.1-33.1 g/kg diets significantly enhanced weight gain and specific growth rate. Similarly, feed efficiency was highest in fish fed the 23.1 and 33.1 g/kg diets. The protein efficiency ratio of fish fed 13.1 g/kg diet was significantly lower than those of fish fed 23.1, 28.1 and 33.1 g/kg diets. The 28.1 g/kg diet resulted in higher whole-body protein content than other diets. The expression level IGF-I and IGF-IR in liver and muscle significantly increased by proper dietary lysine, respectively. Based on a second-order polynomial model of weight gain, the optimal demand ofl-lysine in the diet for juvenileN. albiflorais 24.85 g/kg diet. These results have practical implications for improving growth performance and feed utilization in juvenileN. albiflora.