Synbiotic containing Kappaphycus alvarezii, Spirulina sp. and Halomonas alkaliphila improves survival, growth and vibriosis resistance in whiteleg shrimp (Litopenaeus vannamei) post-larval culture

The high losses in shrimp production due to mortality caused by Vibrio opportunistic pathogens still constitute a significant challenge in the shrimp industry. Synbiotic feed supplementation appears to be a promising control strategy to maintain healthy shrimp stock. In this study, the effects of synbiotic-containing prebiotic seaweeds Kappaphycus alvarezii and Spirulina sp. as well as probiotic Halomonas alkaliphila were evaluated on the survival, growth, and vibriosis of Litopenaeus vannamei during the post-larval stage. Five different feeds were tested: commercial feed, prebiotics K. alvarezii and Spirulina sp.-supplemented feed, and synbiotic-supplemented feed using K. alvarezii, Spirulina sp. and probiotic H. alkaliphila with different concentrations of 108, 109, and 1010 CFU.kg−1. Following 14 days after the feeding test, the highest shrimp survival (91.46 ± 0.05%) was obtained in the treatment group fed with synbiotic-supplemented feed containing 0.375% K. alvarezii, 0.125% Spirulina sp., and H. alkaliphila at 109 CFU.kg−1 (p < 0.05). A 7-day challenge test against opportunistic bacteria Vibrio harveyii was then performed using three treatment groups: (1) synbiotic, containing 0.375% K. alvarezii, 0.125% Spirulina sp., and H. alkaliphila at 109 CFU.kg−1; (2) prebiotic, with 0.375% K. alvarezii, 0.125% Spirulina sp.; and (3) control, using commercial feed. The highest shrimp survival of (79.9 ± 0.05%) was found in the synbiotic treatment group, followed by the prebiotic and control treatment groups (p < 0.05). Overall results suggested that synbiotic-supplemented feed containing 0.375% K. alvarezii, 0.125% Spirulina sp., and H. alkaliphila at 109 CFU.kg−1 significantly improved shrimp survival even when challenged with V. harveyii. Thus, this synbiotic can be potentially applied as an alternative biocontrol strategy against vibriosis in intensive shrimp post-larval culture.