Modulation of growth, immune response, and immune-antioxidant related gene expression of Nile tilapia (Oreochromis niloticus) reared under biofloc system using mango peel powder.

This study aimed to investigate the effects of mango peel powder (MGPP) on growth, innate immunity, and immune-antioxidant related gene expression of Nile tilapia reared under biofloc system. Three hundred Nile tilapia (average weight 14.78 ± 0.05 g) were distributed into 15 fiber tanks (300 L per tank) assigned to five treatments in triplication. Fish were fed basal diet containing different levels MGPP as follows: 0 (MGPP0: control), 6.25 (MGPP 6.25), 12.5 (MGPP 12.25), 25 (MGPP 25), and 50 (MGPP 50) g kg-1 diet for 8 weeks. Specific growth rate (SGR), weight gain (WG), final weight (FW), feed conversion ratio (FCR), skin mucus of lysozyme (SMLA), and peroxidase activities (SMPA), serum of lysozyme (SL) and peroxidase (SP) were measured every for weeks; while immune-antioxidant-related gene expressions were determined after 8 weeks post-feeding. The results indicated that MGPP 25 diet resulted in higher SGR, WG, FW, and FCR but no significant differences among treatments were noticed. In terms of immune responses, lysozyme and peroxidase activities in mucus and serum were significantly higher in MGPP 12.5 and MGPP 25 diets against the control. Similarly, significant up-regulation of IL-1 and IL-8 gene expressions was observed in fish fed MGPP 25 against the control. However, no significant differences in LBP, GSTa, GPX, and GSR among treatments were observed. Overall, dietary inclusion of MGPP 25 significantly enhanced immune response and immune related gene expressions but not growth performance and antioxidant gene expressions. The results implied that MGPP can be potentially used as an immunostimulants in Nile tilapia culture.

In-Situ Biofloc Affects the Core Prokaryotes Community Composition in Gut and Enhances Growth of Nile Tilapia (Oreochromis niloticus).

Biofloc technology is commonly applied in intensive tilapia (Oreochromis niloticus) culture to maintain water quality, supply the fish with extra protein, and improve fish growth. However, the effect of dietary supplementation of processed biofloc on the gut prokaryotic (bacteria and archaea) community composition of tilapia is not well understood. In this study one recirculating aquaculture system was used to test how biofloc, including in-situ biofloc, dietary supplementation of ex-situ live or dead biofloc, influence fish gut prokaryotic community composition and growth performance in comparison to a biofloc-free control treatment. A core gut prokaryotic community was identified among all treatments by analyzing the temporal variations in gut prokaryotes. In-situ produced biofloc significantly increased the prokaryotic diversity in the gut by reducing the relative abundance of dominant Cetobacterium and increasing the relative abundance of potentially beneficial bacteria. The in-situ biofloc delivered a unique prokaryotic community in fish gut, while dietary supplementation of tilapias with 5% and 10% processed biofloc (live or dead) only changed the relative abundance of minor prokaryotic taxa outside the gut core microbiota. The modulatory effect of in-situ biofloc on tilapia gut microbiota was associated with the distinct microbial community in the biofloc water and undisturbed biofloc. The growth-promoting effect on tilapia was only detected in the in-situ biofloc treatment, while dietary supplementation of processed biofloc had no effect on fish growth performance as compared to the control treatment.

Dietary inclusion of watermelon rind powder and Lactobacillus plantarum: Effects on Nile tilapia's growth, skin mucus and serum immunities, and disease resistance.

An eight-week investigation was conducted to access the potential impact of dietary watermelon rind powder (WMRP) and L. plantarum CR1T5 (LP) administered individually or in combination on immunity, disease resistance, and growth rate of Nile tilapia fingerlings cultured in a biofloc system. Three hundred twenty fish (average weight 16.57 ± 0.14 g) were distributed into 16 tanks at a rate of 20 fish per tank. The fish were fed different diets: Diet 1 (0 g kg-1 WMRP and 0 CFU g-1 L. plantarum) (control), Diet 2 (40 g kg-1 WMRP), Diet 3 (108 CFU g-1 LP), and Diet 4 (40 g kg-1 WMRP + 108 CFU g-1 LP) for eight weeks. A completely randomized design (CRD) with four replications was applied. Skin mucus, serum immunity, and growth parameters were analyzed every 4 weeks, and a challenge study against S. agalactiae was conducted at the end of the experiment. The findings showed that the inclusion of WMRP + LP, administrated individually or in a mixture, significantly (P<0.05) stimulated growth, skin mucus, and serum immune parameters of Nile tilapia fingerlings compared with the control. The highest values were detected in fish fed the combination of WMRP and LP, as opposed to individual administration of either WMRP or LP, in which no significant differences were detected. Within the challenge study, the relative percent survival (RPS) in Diet 2, Diet 3, and Diet 4 was 48.0%, 52.0%, and 68.0%, respectively. Fish fed 40 g kg-1 WMRP + LP produced significantly higher RPS and protection against S. agalactiae than the other treated groups. Current results suggest that the dual administration of WMRP and LP maybe an effective feed additive for Nile tilapia grown in an indoor biofloc system, capable of improving growth parameters and increasing resistance to S. agalactiae infection.

Dietary inclusion of chestnut (Castanea sativa) polyphenols to Nile tilapia reared in biofloc technology: Impacts on growth, immunity, and disease resistance against Streptococcus agalactiae.

A feeding trial was carried out to examine the effects of adding chestnut (Castanea sativa) polyphenols (CSP) on the growth, skin mucus and serum immune parameters of Nile tilapia (Oreochromis niloticus). Five experimental diets with inclusion levels of 0, 1, 2, 4, and 8 g kg-1 of CSP were fed to Nile tilapia fingerlings (12.77 ± 0.17 g fish-1) during an eight-week trial. Fish were analyzed on the fourth and eighth week to determine the influences of CSP on growth, skin mucus, and serum immune parameters. Challenging test versus Streptococcus agalactiae was evaluated at the end of the trial. Fish fed with CSP enriched diets displayed a significant increase (P ≤ 0.05) in growth and a decline in feed conversion ratio (P ≤ 0.05). Similarly, skin mucus and serum immune parameters were significantly increased (P ≤ 0.05) in fish fed CSP with respect to the control. The effects were already evident four weeks after the CSP administration. The disease protection test displayed that the fish's survival rate was significantly higher (P < 0.05) in CSP diets over the control. The relative percentage of survival (RSP) was 62.5, 75.0, 58.3, and 37.5 in fish fed diets contained 1, 2, 4, and 8 g kg-1 CSP, respectively. The best effect on growth, immune response, and disease resistance were shown in Nile tilapia fed with a diet supplementation of 2 g kg-1 CSP.