Effects of dietary 5-aminolevulinic acid on growth performance and nonspecific immunity of Litopenaeus vannamei, as determined by transcriptomic analysis

Abstract

5-aminolevulinic acid (5-ALA) is an endogenous non-protein amino acid that is frequently used in modern agriculture. This study set out to determine how dietary 5-ALA affected the nonspecific immunity and growth performance of Litopenaeus vannamei. The shrimp were supplemented with dietary 5-ALA at 0, 15, 30, 45, and 60 mg/kg for three months. Transcriptome data of the control group and the group supplemented with 45 mg/kg dietary 5-ALA were obtained using transcriptome sequencing. 592 DEGs were identified, of which 426 were up-regulated and 166 were down-regulated. The pathways and genes associated with growth performance and nonspecific immunity were confirmed using qRT-PCR. The highest survival rate, body length growth rate, and weight gain values were observed in shrimp fed diets containing 45 mg/kg 5-ALA. L. vannamei in this group had a significantly higher total hemocyte count, phagocytosis rate and respiratory burst value than those in the control group. High doses of dietary 5-ALA (45 mg/kg, 60 mg/kg) significantly increased the activities of catalase, superoxide dismutase, oxidized glutathione, glutathione-peroxidase, phenoloxidase, lysozyme, acid phosphatase, and alkaline phosphatase. At the transcriptional level, dietary 5-ALA significantly up-regulated the expression levels of antioxidant immune-related genes. The optimal concentration of 5-ALA supplementation was 39.43 mg/kg, as indicated by a broken line regression. Our study suggested that dietary 5-ALA positively impacts the growth and nonspecific immunity of L. vannamei, providing a novel theoretical basis for further research into 5-ALA as a dietary supplement.