Dietary supplementation of Gracilaria corticata extracts improved immunity of white leg shrimp exposed to white spot virus

In order to investigate the resistance of shrimp against white spot disease by Gracilaria corticata algae, 300 Vannamei shrimp in two groups were fed with and without algae extract for 14 days. At the end of the experiment, half of the shrimp of each group were exposed to the white spot virus. After the challenge, during days 0, 3, 9, 18 and 25, the survival rate and immune factors of shrimp were examined. According to the results, survival rate of shrimp fed with algae extract was higher than the shrimp were fed by commercial pellet without the algae extract (positive control) significantly (P < 0.05). Immune system enhancement from the first to twenty fifth day and the highest levels of THC, TPP, SOD, POD and PO were observed in group Algae on twenty fifth day of the experiment. This condition was also observed in group AV, but less than group A with a significant difference (P <0.05). Considering the function of algae in stimulating the immune system, it seems that during the culture period, algae supplementation in the diet can be used as a proposed strategy to control white spot disease.