Effect of Dietary Supplementation of Brewer's Yeast and GroBiotic®-A on Growth, Immune Responses, and Low-Salinity Tolerance of Pacific White Shrimp Litopenaeus vannamei Cultured in Recirculating Systems

Abstract

Two separate trials were conducted in clean recirculating systems at salinities of 32.9 (optimal) and 2 ppt (low-salinity challenge) to evaluate brewer's yeast and GroBiotic®-A, a commercial prebiotic, as dietary supplements for growth and health management of Pacific white shrimp Litopenaeus vannamei. The growth-promoting influences of brewer's yeast or GroBiotic®-A previously observed with fish were not demonstrated in these trials with shrimp, when each component was supplemented at 2% or 5% of the diet. No significant dietary effects on hematological and immunological responses—including total hemocyte count, hemolymph protein, phenoloxidase, hemocyte respiratory burst, and clearance efficiency of Vibrio harveyi—were observed in shrimp cultured at full strength salinity (30 ppt) in feeding trial 1 after a 10 week period. In a second feeding trial, dietary supplementation of GroBiotic®-A improved survival of shrimp cultured at low-salinity (2 ppt). Although the mechanism(s) for enhanced survival under low-salinity conditions by dietary immunostimulants or prebiotics have not been identified, these observations indicate potential use of prebiotics such as GroBiotic®-A for shrimp cultured in less than optimal environments.