Dietary Galla chinensis on white shrimp Penaeus vannamei: Promotes growth, nonspecific immunity, and disease resistance against Vibrio parahaemolyticus

Abstract

This study investigated the impact of Galla chinensis (GC) powder as a dietary supplement on the immunity, growth, and pathogen resistance of white shrimp, Penaeus vannamei. An in vitro analysis demonstrated that GC inhibited Vibrio with no discernible impact on Lactobacillus. Following this, GC was tested for toxicity on white shrimp hemocytes. GC showed harmlessness to white shrimp hemocytes since cell viability was over 80% at all dosages. The immune response of hemocytes in white shrimp to diets containing varying concentrations of GC was evaluated in an in vivo experiment. Five feeding regimens were trialed for 28 days, which were designated as GC0.5, GC1, GC2.5, and GC5 (0, 0.5, 1, 2.5, and 5 g/kg, respectively). The enhanced total hemocytes, phenoloxidase, phagocytic activity, and production of superoxide anion in white shrimp on day 7 of the feeding trial by administering a supplementary GC diet significantly stimulated the nonspecific immunity of white shrimp. Additionally, dietary GC substantially increased the expression of related genes in white shrimp hemocytes in vivo, including Toll, Imd, antimicrobial peptides, antioxidant defenses, clotting protein, and heat shock protein. The challenge experiment was conducted to assess the disease resistance of white shrimp fed with GC. The shrimps were fed dietary GC for 7 days while being challenged with Vibrio parahaemolyticus. The shrimp exhibited a substantial variation in survival rate during the bacteria challenge experiment due to the activation of related genes and the enhancement of non-specific immunity. The mortality of white shrimp was substantially reduced by the supplementary GC at a concentration of 1 g/kg during the bacteria challenge. A final feeding trial was conducted to assess the effects of dietary GC on the growth performance of white shrimp. The continuous administration of dietary GC at a dose of 1 g/kg to shrimp for 56 days resulted in the highest enhancement in shrimp growth among all treatments. This was evidenced by significantly increased final body weight, weight gain, specific growth rate, and decreased feed conversion ratios. Dietary GC at a dosage of 1 g/kg has been suggested for use to enhance the growth performance of white shrimp and improve immunological responses, particularly nonspecific immunity and related gene expression, as well as resistance to Vibrio parahaemolyticus.