The Effect of Dietary Chitosan and Chitin Supplementation on the Survival and Immune Reactivity of Crayfish, Procambarus clarkii

White spot syndrome virus (WSSV) is an important viral pathogen responsible for severe economic loss to shrimp aquaculture. The effect of oral administration of chitosan and chitin against WSSV in crayfish Procambarus clarkii was investigated. Six groups of 20 crayfish, P. clarkii, in triplicate were diet supplemented with chitosan or chitin at 5, 10, and 15 mg/g for 4 wks, and orally challenged with WSSV. The cumulative mortalities in the groups fed with chitosan at 10 mg/g was significantly lower (P < 0.05) than the control but the other groups were not. The relative percent survival (RPS) showed that chitosan provided better protection against WSSV than chitin (P < 0.05). Polymerase chain reaction (PCR) analysis showed that the surviving crayfish were WSSV negative. The immunological parameters analyzed revealed that the crayfish fed with chitosan and chitin showed significantly higher level of total hemocyte count (THC), prophenoloxidase (proPO), and superoxide dismutase (SOD) when compared to the control groups.