Effects of irradiated chitosan on growth, immune repsonse and survival of Nile tilapia (Oreochromis niloticus) juveniles

• Main Authors: Vytiaco, Kristine Gonzales, Eguia, Maria Rowena R., Amar, Edgar C., Carandang, Jose Santos R., VI, Flores, Mary Jane C.
• Format: text
• Published: Animo Repository 2016
• Subjects: Nile tilapia; Chitosan—Physiological effect; Biology
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/11606
• Institution: De La Salle University

In aquaculture, use of harmful chemicals to minimize the incidence of diseases in farmed aquatic animals is not encouraged. Hence natural, organic immunostimulants have been promoted for aquatic animal health management. This study investigated the effects of irradiated chitosan on the growth, immune response and survival of Nile tilapia. Uniformly-sized tilapia juveniles (30 pcs/tank) were randomly stocked in triplicate tanks each for (a) Treatment where fish were fed a diet containing 10gKg-1 irradiated chitosan and (b) Control where fish were fed the same formulated feed but without irradiated chitosan. Growth and food utilization parameters were noted. Specific Growth Rate (SGR), Mean Weight Gain (MWG) and Feed Conversion Efficiency (FCE) were analyzed using t-test. The efficacy of irradiated chitosan as an immunostimulant was measured using total immunoglobulin (Ig), lysozyme andnitroblue tetrazolium (NBT) assays while its antimicrobial ability was assessed through bacterial challenge tests using a virulent strain of Aeromonashydrophila. Results showed that irradiated chitosan in the feed do not retard the growth of O. niloticus as seen in a higher SGR (1.41+0.14% per day) and MWG (5.07 +1.66g) however there was no significant difference between treatments. FCE (0.52+0.05) was higher in fish fed diet with irradiated chitosan indicating better feed performance. There was likewise an increase in the immune activity in the Treatment group especially from the 21st day of feeding. The survival percentage of O. niloticus during the bacterial challenge test was significantly higher in the treatment group (86.95%) compared to the control (50%) after 14 days of oral administration. In conclusion, 10 g kg-1 of irradiated chitosan in the fish diet enhances the growth, immune response and survival of Nile tilapia (O. niloticus).