Dietary lysine affects growth performance, whole‐body composition and growth‐related gene expression in the yellow drum Nibea 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 dietary l-lysine demand for juvenile Nibea albiflora. Fish were fed six diets, in which the l-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 of l-lysine in the diet for juvenile N. albiflora is 24.85 g/kg diet. These results have practical implications for improving growth performance and feed utilization in juvenile N. albiflora.