Dietary Sago Caterpillar Meal Enhances Innate Immunity and Resistance to Vibriosis in Nile Tilapia (Oreochromis niloticus)

Vibriosis, caused by Vibrio spp., is a major bacterial infection leading to high mortality rates in fish. Enhancing the innate immune response through dietary immunostimulants is a promising preventive approach. This study investigated the effects of dietary inclusion of sago caterpillar meal (Rhynchophorus ferrugineus) on the growth performance and innate immune response of Nile tilapia (Oreochromis niloticus) following infection with Vibrio harveyi. A completely randomized design was employed with four dietary treatments (0%, 10%, 20% and 30% sago caterpillar meal) and three replicates per treatment. Tilapia were fed these diets for 30 days, after which a bacterial challenge test was conducted. Immune response was assessed by measuring total leukocyte count and bacterial load in fish gills, while growth performance was evaluated based on daily weight and length gain, specific growth rate (SGR), feed conversion ratio (FCR) and survival rate. Results showed that dietary sago caterpillar meal significantly influenced total leukocyte count, bacterial concentration in the gills, daily weight gain, SGR and survival rate. However, no significant effects were observed on daily length gain or FCR. The optimal concentration for enhancing immune response and growth performance was found to be 20% sago caterpillar meal. These findings suggest that sago caterpillar meal is a potential immunostimulant and growth enhancer in Nile tilapia culture.