The Effect of Stocking Density and Carbon Sources on the Oxidative Status, and Nonspecific Immunity of Nile tilapia (Oreochromis niloticus) Reared under Biofloc Conditions

Abstract

The present study investigated the effect of stocking density and dietary carbon sources on the water quality, oxidative status, and immune-related genes of Nile tilapia (Oreochromis niloticus) reared under biofloc conditions (BFT). Eight groups were established at two levels of stocking densities (140 fish per m3: low stocking density, LSD) and (280 fish per m3: high stocking density, HSD) (5.15 ± 1.12 g) and kept in eight biofloc units containing water without carbon sources (control groups) or with glycerol, molasses, or starch. Red blood cells count, hemoglobin, and hematocrit values were reduced in fish stocked in control groups at LSD and HSD than biofloc groups. Control fish groups reared at both LSD and HSD have the highest significant (p < 0.05) white blood cells number than other fish groups. Meanwhile, fish groups that received glycerol, molasses, and starch maintained in both LSD and HSD presented a higher significant (p < 0.05) monocyte % than in the control group reared at both LSD and HSD. The fish group reared in biofloc conditions (BFT) using starch carbon source and reared at the HSD presented a significantly higher (p < 0.05) increase in total serum protein and albumin levels as well as globulin value than the control fish group reared at both LSD and HSD. The highest glucose and cortisol levels were showed in the control fish group reared at both LSD and HSD. Fish maintained in glycerol-based biofloc at LSD attained the highest (p < 0.05) serum superoxide dismutase (SOD), glutathione reductase (GR), and catalase than other experimental groups. Regarding the nonspecific immune status, significantly increased expression of CC-chemokines, CXC-chemokines, TLR7 and IL-8 genes was found in molasses based biofloc groups. The data of the present study revealed that using molasses promotes health status of Nile tilapia cultured in a biofloc system.

Biofloc Microbiome With Bioremediation and Health Benefits

“…In the experiment, it was demonstrated that the biofloc system significantly enhances shrimp survival, final body weights, and prophenoloxidase (proPO) cascade, which is one of the major innate immune responses in crustaceans, by upregulating prophenoloxidase activation enzyme, masquerade-like proteinase, prophenoloxidase1, prophenoloxidase2, serine proteinase1, and ras-related nuclear protein expression ( Kim et al, 2014 ). Similar findings were also observed in Labeo rohita ( Ahmad et al, 2016 ; Kamilya et al, 2017 ), Oreochromis niloticus ( Mansour and Esteban, 2017 ; Mirzakhani et al, 2019 ; Hwihy et al, 2021 ; Shourbela et al, 2021 ), Cyprinus carpio ( Bakhshi et al, 2018 ; Aalimahmoudi and Mohammadiazarm, 2019 ), and Apostichopus japonicus ( Chen et al, 2018 ), where animals reared in biofloc water display higher growth performance including improved feed efficiency ratio (FER), specific growth rate (SGR), and feed conversion ratio (FCR). Additionally, the cultured animals have enhanced non-specific immune response, highlighted by significantly increased serum protein, serum albumin, total immunoglobulin, lysozyme, respiratory burst, and myeloperoxidase activity.…”

Antiparasitic and Antibacterial Functionality of Essential Oils: An Alternative Approach for Sustainable Aquaculture

“…Using of these chemical substances cause mass killing of beneficial aquatic bacteria [13], produce multi-drugs resistant pathogens [14], and leaving residues in fish which can be transmitted to human [15,16]. These problems are the most concerning aquaculture sustainability [17,18], and infectious diseases and parasitic infestation treatment with natural substances/compounds are the demanding sustainable aquaculture features [19].…”

Use of two freshwater macrophytes, water hyacinth ( Eichhornia crassipes ) and coontail ( Ceratophyllum demersum ), as carbohydrate sources in biofloc system for Nile tilapia ( Oreochromis niloticus )

“…These sources include corn flour (García‐Ríos et al, 2019), wheat flour (García‐Ríos et al, 2019), oligosaccharides (Kishawy et al, 2020), sugar (García‐Ríos et al, 2019; Hisano, Barbosa, et al, 2021; Liu, Luo, et al, 2018; Long et al, 2015) and molasses (Hisano, Barbosa, et al, 2021; Khanjani, Alizadeh, & Sharifinia, 2021; Laice et al, 2021). The effectiveness of carbon supplementation depends on the carbon source, quality and quantity, time and frequency of application, total ammonia–nitrogen (TAN) concentration in the water, exogenous supplemental feeds and fish size and stocking density (El‐Sayed et al, 2021; Khanjani, Alizadeh, & Sharifinia, 2021; Shourbela et al, 2021).…”

“…. The analysis of gene expression was performed by comparative threshold cycle method 2 −ΔΔC t(Shourbela et al, 2021).…”