Diseases are a major limiting factor for sustainable aquaculture production, with lasting effects on socio-economic development and an increasing use of antimicrobials in fish. Imprudent use of such antibiotics has been subjected to criticism from scientists and environmentalists due to their negative impact on humans, animals, and the environment. The present investigation aims to study the dietary effect of NAAM compound on growth, haematology, digestive enzyme capacity, antioxidant status, immunity, and disease resistance in Oreochromis niloticus . The experiment compared fish in control and treatment (1 kg/ton feed) for a 45-day period. At the end of the feeding trial, the experimental animals were infected with Aeromonas hydrophila , Edwardsiella tarda , Streptococcus agalactiae , Pseudomonas aeruginosa , Vibrio harveyi and mortality was recorded for 21 days.
The treated group showed a significant increase in weight gain, specific growth rate and decreased feed conversion ratio compared to the control group. Further, NAAM compound supplementation in experimental fish significantly increased the digestive enzyme capacity (enteropeptidase , trypsin, pancrealipase, and amylopsin) in the treated group. Haematological parameters and antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) were significantly improved in fish fed NAAM compound-supplemented diets. Meanwhile, malondialdehyde levels were significantly decreased in serum and liver of fish fed with NAAM compound-supplemented diets. In the NAAM compound treated group, total protein and albumin were significantly decreased, while cholesterol and triglyceride levels were increased.
The dietary effect of NAAM compound caused significant improvements in innate immunity (NBT, phagocytic, and lysozyme activity) in tilapia compared to the control. The pathogen challenge study revealed that there was a significant difference in the survival rate of fish in the control (only feed), control + florfenicol, NAAM compound treatment (1 kg/ton feed), and NAAM compound treatment (2 kg/ton feed after pathogen injection). These findings revealed that dietary NAAM compound could exhibit a profitable effect on growth performance, haematology and serum biochemistry, antioxidant status, digestive enzyme capacity, immunity, disease resistance, and overall health status of O. niloticus.