Effect of Red Seaweed Kappaphycus alvarezii on Growth, Survival, and Disease Resistance of Pacific White Shrimp Litopenaeus vannamei Against Vibrio harveyi in the Nursery Phase

In this study, the effect of red seaweed Kappaphycus alvarezii by-product meal on growth, survival, and disease resistance of white shrimp Litopenaeus vannamei against Vibrio harveyi was evaluated in the nursery phase. Shrimp was fed for 30 days with four different diets: control  (0 g kg-1), 5 g kg-1, 10 g kg-1 and 15 g kg-1 seaweed supplemented feed. The seaweed supplementation at the higher concentrations (10 and 15 g kg-1) was found to increase the survival of the shrimp, even though not significantly. The highest total biomass obtained in the shrimp group fed with 15 g kg-1 seaweed diet (P>0.05). Following feeding test, bacterial challenge test using pathogenic V. harveyi was done on the shrimp group previously fed with 15 g kg-1 seaweed diet. The findings showed that seaweed-supplementation significantly increased up to 10% higher shrimp survival after Vibrio challenge. Based on the results of histopathological analysis, hepatopancreas from seaweed-supplemented shrimp showed decreasing tubular epithelial cell lesion by Vibrio infection, suggesting that compounds contained in K. alvarezii by-product meal could have protected shrimp hepatopancreas from distructive effect of Vibrio infection. In general, red seaweed K. alvarezii enrichment on shrimp diet provides protection against V. harveyi infectionduring the shrimp nursery phase.