Enhancement of growth performance, digestive enzyme activity and survival of whiteleg shrimp, <i>Litopenaeus vannamei</i> fed dietary synbiotics

This study aimed to isolate lactic acid bacteria (LAB) from the intestines of whiteleg shrimp ( Litopenaeus vannamei ) for potential probiotic use and to evaluate the effects of dietary synbiotic supplementation on shrimp growth performance and digestive enzyme activity. A total of 249 LAB isolates were obtained from shrimp intestines collected in extensive ponds in Ca Mau province. Among these, 15 isolates exhibited strong antagonistic activity against Vibrio parahaemolyticus , with inhibition zones ranging from 6 to 11 mm. Most isolates were Gram-positive, non-motile, non-spore-forming, and exhibited cell shapes ranging from short rods to spherical. Four isolates demonstrated strong protease and leu-aminopeptidase activities, although α-amylase production was relatively low. Strain LAB8.1CM was identified as Lactiplantibacillus plantarum based on 16S rRNA gene sequencing (99.7% homology) and exhibited promising probiotic characteristics, indicating its potential as a safe feed additive. In a 60-day feeding trial, shrimp were assigned to five dietary treatments: control (basal diet), prebiotic (0.2% banana extract), probiotic ( L. plantarum 10 8 CFU/kg), synbiotic-0.2% (banana extract 0.2% + L. plantarum 10 8 CFU/kg), and synbiotic-0.4% (banana extract 0.4% + L. plantarum 10 8 CFU/kg), each with three replicates. Synbiotic supplementation significantly improved digestive enzyme activities, including α-amylase, β-galactosidase, protease, and leu-aminopeptidase. Growth performance parameters, such as weight gain, daily weight gain, specific growth rate, and feed conversion ratio, were also significantly enhanced, particularly in shrimp fed the synbiotic-0.2% diet. Survival rates did not differ significantly among treatments. These findings indicate that dietary supplementation with selected LAB strains, in combination with prebiotics, can effectively enhance growth, digestion, and health in whiteleg shrimp, highlighting their potential as synbiotic feed additives for sustainable aquaculture practices.