Potential influence of jaggery-based biofloc technology at different C:N ratios on water quality, growth performance, innate immunity, immune-related genes expression profiles, and disease resistance against Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus)

Abstract

Biofloc technology is increasingly becoming the most promising aquaculture tool especially in places where water is scarce and the land is very expensive. The dynamics of water quality, as well as plankton and microbial abundance, are collectively necessary for successful fish farming. The prospective use of jaggery as a potential carbon source and its influence on water quality, growth performance, innate immunity, serum bactericidal capacity, and disease resistance to Aeromonas hydrophila was investigated in Oreochromis niloticus. A completely randomized design was used in triplicates, where the control group was reared in a water system with no carbon source, while T1, T2, and T3 groups were raised in biofloc systems at C:N ratios of C:N12, C:N15, and C:N20, respectively. Water specimens were collected daily and fortnightly, while blood, serum, and head kidneys were collected at 75 days of experimental period for further analysis. TAN, nitrite, and ammonia values were considerably reduced, while the TSS values elevated significantly in all treated groups compared to the control. Jaggery-based biofloc system (JB-BFT) has a pronounced effect on hematological and growth performance parameters rather than control. Similarly, serum antioxidants, lysozyme, protease, antiprotease and bactericidal capacity were significantly increased (p < 0.05) in the treated groups in a dose-dependent manner. LYZ, TNF-α, and IL-1β genes were upregulated in proportion to C:N ratios with the highest fold in C:N20. Furthermore, fish treated with JB-BFT presented lower cumulative mortalities and better relative levels of production (RLP) after experimental challenge with A. hydrophila compared to control. In conclusion, JB-BFT has a robust influence on Nile tilapia (O. niloticus) innate immunity through favorable innovation of various immune-cells and enzymes as well as upregulating the expression levels of immune-related genes. This study offers jaggery as a new carbon source with unique properties that satisfy all considerations of biofloc technology in an eco-friendly manner.

Keywords: Biofloc; Experimental challenge; Innate immunity; Jaggery powder; Nile tilapia.