Effects of supplementation with different zinc-based products on the growth and health of Nile tilapia.

Zinc is one of the essential microelements for the metabolism of animals. Zinc nanoparticles may have higher bioavailability due to their low specific surface area, facilitating absorption by fish. The present study aimed to evaluate the effects of supplementation with different zinc-based products on the growth and health of Nile tilapia Oreochromis niloticus. Zinc, in different sizes (nanoparticles or bulk) and forms (inorganic or organic), were used as a supplement in the tilapia diet at a dose of 15 mg kg feed-1 for 60 days. At the end of the feeding trial, production performance, hemato-immunological parameters, activity of antioxidant system enzymes, exposure to Streptococcus agalactiae and zinc concentration in the muscle were examined. After the bacterial challenge, the mean corpuscular hemoglobin concentration (MCHC) significantly increased in the fish treated with organic zinc, inorganic nano zinc, and organic nano zinc, while in the control group (inorganic zinc), MCHC remained unchanged. Regarding defense cells, dietary inorganic nano zinc increased the number of basophils (1.50 ± 1.10) compared to organic zinc (0.80 ± 0.90). Lymphocyte count increased after the challenge only in the organic zinc treatments (bulk and nanoparticles). Neutrophils decreased in the control (inorganic zinc) (2.20 ± 1.70) and inorganic nano zinc (2.60 ± 2.70) treatments after the challenge. When compared before and after the bacterial challenge, the plasma antimicrobial titer significantly increased after the bacterial challenge in all treatments. No significant differences were observed for total proteins, enzymes (SOD and CAT), cumulative survival and zinc deposition on fillet. In conclusion, organic zinc in nanoparticles or bulk size increased Nile tilapia innate defense during bacterial infection. However, the other parameters evaluated were not affected by zinc particle size or form (organic or inorganic), indicating that further evaluations should be conducted with organic zinc in nanoparticles or bulk size in the tilapia diet.

Effects of Shrimp Shell-Derived Chitosan on Growth, Immunity, Intestinal Morphology, and Gene Expression of Nile Tilapia (Oreochromis niloticus) Reared in a Biofloc System.

Chitosan (CH) shows great potential as an immunostimulatory feed additive in aquaculture. This study evaluates the effects of varying dietary CH levels on the growth, immunity, intestinal morphology, and antioxidant status of Nile tilapia (Oreochromis niloticus) reared in a biofloc system. Tilapia fingerlings (mean weight 13.54 ± 0.05 g) were fed diets supplemented with 0 (CH0), 5 (CH5), 10 (CH10), 20 (CH20), and 40 (CH40) mL·kg-1 of CH for 8 weeks. Parameters were assessed after 4 and 8 weeks. Their final weight was not affected by CH supplementation, but CH at 10 mL·kg-1 significantly improved weight gain (WG) and specific growth rate (SGR) compared to the control (p < 0.05) at 8 weeks. Skin mucus lysozyme and peroxidase activities were lower in the chitosan-treated groups at weeks 4 and 8. Intestinal villi length and width were enhanced by 10 and 20 mL·kg-1 CH compared to the control. However, 40 mL·kg-1 CH caused detrimental impacts on the villi and muscular layer. CH supplementation, especially 5-10 mL·kg-1, increased liver and intestinal expressions of interleukin 1 (IL-1), interleukin 8 (IL-8), LPS-binding protein (LBP), glutathione reductase (GSR), glutathione peroxidase (GPX), and glutathione S-transferase (GST-α) compared to the control group. Overall, dietary CH at 10 mL·kg-1 can effectively promote growth, intestinal morphology, innate immunity, and antioxidant capacity in Nile tilapia fingerlings reared in biofloc systems.

Impacts of astaxanthin-enriched Paracoccus carotinifaciens on growth, immune responses, and reproduction performance of broodstock Nile tilapia during winter season.

The growth, immune response, and reproductive performance of broodstock of Nile tilapia (Oreochromis niloticus) under winter stress conditions were investigated the effects of supplementary diets with astaxanthin-enriched Paracoccus carotinifaciens. Throughout an eight-week period in the winter season, male and female tilapia were fed with diets containing different levels of P. carotinifaciens dietary supplementation: 0 g/kg (T1; control), 5 g/kg (T2), 10 g/kg (T3), and 20 g/kg (T4). Subsequently, a four-week mating system was implemented during the winter stress period. The results revealed that there were no significant differences observed in growth, hematological indices, and blood chemical profiles among all treatment groups for both male and female tilapia. However, a significant increase in cholesterol content was noted in both male and female tilapia fed with the T4 diet (p<0.05). The total carotenoid content in the muscle was evaluated, and significantly higher values were found in both male and female tilapia that fed T4 supplementation (p<0.05). Moreover, immunological parameters such as myeloperoxidase and antioxidant parameters in the liver including superoxide dismutase activity and catalase enzyme activity showed significant increases in tilapia fed with the T4 diet. The impact of P. carotinifaciens supplementation on broodstock tilapia indicated a significant increase in spermatozoa concentration in males and increased egg production in females after consumption of the T4 diet (p<0.05). Thus, this study highlighted that the presence of astaxanthin-enriched P. carotinifaciens in the diet of broodstock Nile tilapia can lead to the accumulation of carotenoids in their muscle tissue, improvement in antioxidant status, enhancement of immune function, and potential enhancement of reproductive capabilities, even under overwintering conditions.

Impacts of Aegle marmelos fruit extract as a medicinal herb on growth performance, antioxidant and immune responses, digestive enzymes, and disease resistance against Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus).

An experiment was conducted to investigate the effects of Aegle marmelos fruit (AMF) extract on the growth performance, biochemical parameters, immune response, antioxidative capacity, and digestive enzyme activity of Nile tilapia (Oreochromis niloticus). Fish were fed a diet supplemented with AMF at concentrations of 0 (AMF0; control), 5 (AMF5), 10 (AMF10), 15 (AMF15), or 20 (AMF20) g/kg for 8 weeks. The results show that the final body weight, weight gain, specific growth rate, average daily gain, and feed conversion ratio were significantly higher in fish fed AMF15 and AMF20 compared to those fed the control diet (P < 0.05). Moreover, significant increases in antioxidant enzyme activities and non-specific immune responses were observed in groups fed AMF15 and AMF20. Interestingly, the level of cholesterol decreased with increasing AMF concentrations in the diet. As dietary AMF levels increased, digestive enzyme activities significantly improved. After the feeding trial, fish were injected intraperitoneally with Streptococcus agalactiae, and the 14-day cumulative mortality was calculated. A high survival rate after challenge with S. agalactiae was observed in all groups that received AMF-supplemented feed. Therefore, the present study suggests that supplementing the diet of Nile tilapia with AMF at a concentration of 20 g/kg could encourage their growth, improve their immunity and antioxidant status, and provide strong protection against S. agalactiae.

Dietary Guduchi (Tinospora cordifolia) enhanced the growth performance, antioxidative capacity, immune response and ameliorated stress-related markers induced by hypoxia stress in Nile tilapia (Oreochromis niloticus).

Nile tilapia can tolerate a wide range of farming conditions; however, fluctuations in the environmental conditions may impair their health status. The incorporation of medicinal herbs in aquafeed is suggested to overcome stressful conditions. In this study, dietary Guduchi (Tinospora cordifolia) was evaluated on the growth performance, antioxidative capacity, immune response, and resistance of Nile tilapia against hypoxia stress. Fish fed five diets incorporated with Guduchi at 0, 2, 4, 6, and 8 g/kg for 56 days then exposed with hypoxia stress for 72 h. The growth performance, feed intake, and feed efficiency ratio were significantly (P < 0.05) increased by including Guduchi in tilapia diets regardless of the inclusion level. Similarly, the lipase and protease activities were markedly (P < 0.05) increased in tilapia fed dietary Guduchi. The activities of lysozyme and bactericidal activities in serum and mucus, nitro-blue tetrazolium (NBT), and alternative complement activity (ACH50) were markedly (P < 0.05) enhanced in tilapia treated with Guduchi supplements regardless of the dose. Additionally, the activities of liver and intestinal superoxide dismutase, catalase, and glutathione peroxidase were markedly enhanced (P < 0.05) by including Guduchi in tilapia diets compared with the control. Before and after hypoxia stress, tilapia-fed dietary Guduchi had lower glucose and cortisol levels than fish-fed Guduchi-free diets (P < 0.05). In all groups, glucose and cortisol levels were markedly higher after hypoxia compared before hypoxia stress (P < 0.05). In conclusion, dietary Guduchi can be included at 5.17-5.49 g/kg to enhance the growth performance, digestive enzyme activity, immune and antioxidative responses, and the resistance of Nile tilapia against hypoxia stress.

Pistachio hull polysaccharide protects Nile tilapia against LPS-induced excessive inflammatory responses and oxidative stress, possibly via TLR2 and Nrf2 signaling pathways.

Polysaccharides are polymeric carbohydrates found in living organisms, which have several physiological functions. In the present study, Nile tilapia (Oreochromis niloticus) were fed diets containing three levels (0%, 0.2%, and 0.6%) of Pistacia vera hull polysaccharide (PHP) for 45 days and then injected with PBS or bacterial lipopolysaccharide (LPS). Before the LPS challenge, Nile tilapia fed 0.2% and 0.6% PHP showed significantly increased mean final weight and weight gain compared to those received 0% PHP. The specific growth rate and feed conversion ratio were significantly improved in the treatment fed 0.6% PHP compared to the remaining groups. After LPS challenge, the activities of liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase exhibited the highest values in the 0.6% PHP group. Malondialdehyde (MDA) levels were significantly augmented in the model (fed 0% PHP diet and injected with LPS) and 0.2% PHP groups compared to the control. However, MDA showed decreased levels in the 0.6% PHP group. LPS induced higher mRNA and/or protein levels of Toll-like receptor 2 (TLR2), nuclear factor kappa B (NF-κB), myeloid differentiation primary response protein 88 (Myd88), tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and interferon γ (IFN-γ) in Nile tilapia liver. However, PHP administration significantly upregulated the expression of interleukin 10 (IL-10), nuclear erythroid 2-related factor 2 (Nrf2), SOD, and CAT, but markedly suppressed TLR2, NF-κB, Myd88, and pro-inflammatory cytokine expression and/or production in the liver. The findings of the current study indicated that PHP has positive effects on growth performance, immune gene-related expression, and antioxidative activities. We can conclude that PHP can attenuate LPS-induced oxidative stress and inflammatory responses in vivo, possibly via induction of Nrf2 and blockade of TLR2/Myd88/NF-κB pathways in Nile tilapia.

Influences of spent coffee grounds on skin mucosal and serum immunities, disease resistance, and growth rate of Nile tilapia (Oreochromis niloticus) reared under biofloc system.

The study was executed to find out the potential effects spent coffee ground (SCG) on Nile tilapia's skin mucosal and serum immunities, disease prevention, and growth rate reared in a biofloc system. Nile tilapia fingerlings (average weight 15.25 ± 0.07 g) were disseminated into 15 aquaria (150 L tank-1) at a density of 20 fish per aquarium and treated five diets: SCG1 (control), SCG2 (10 g kg-1), SCG3 (20 g kg-1), SCG4 (40 g kg-1), and SCG5 (80 g kg-1) for eight weeks. A Completely Randomized Design (CRD) with three replications was applied. Growth rate, skin mucus, and serum immunities were quantified every 4 weeks; whereas the challenge study was conducted at the termination of the feeding trial. The outputs indicated that dietary incorporation of SCG give rise to the enhancement of SGR and FCR in comparison with the control, with best levels noted in fish fed SCG2 diet. Similarly, significant enhancements in skin mucosal and serum immunities were revealed in fish treated SCG2 over the control and other SCG diets. Likewise, higher survival rates against Streptococcus agalactiae were displayed in fish fed SCG, with the maximum level displayed in the fish treated SCG2. In conclusion, dietary supplementation of SCG2 (10 g kg-1) can be potential used as immunostimulants in tilapia aquaculture.

Dietary organic selenium improves growth, serum biochemical indices, immune responses, antioxidative capacity, and modulates transcription of stress-related genes in Nile tilapia reared under sub-optimal temperature.

A 56-day feeding experiment was carried out to investigate the influences of dietary organic selenium (OS) on the growth, body composition, serum biochemistry, stress responses, and immune indices of Nile tilapia reared under sub-optimal temperature. Fish (5.61 ± 0.5 g) were allotted in seven experimental groups (5 replicates per each) and fed on a basal diet supplemented with 0.0 (CTR), 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 mg OS/kg diet and reared under temperature ranged 21.50 ± 0.50 °C. Final body weight, weight gain, and specific growth rate were significantly increased in OS groups compared to the CTR group. Moreover, the feed conversion ratio was significantly decreased in OS groups, especially at fish groups fed 0.3-0.6 mg OS/kg diet compared to the other groups. The lowest survival rate (%) was found in OS groups between 0.0 and 0.2 mg/kg diet. A significant increase in the crude protein (%) and dry matter (%) in OS groups alongside a significant decrease in the ash (%) compared to the CTR group. Blood proteins (total protein, albumin, and globulin), reduced glutathione, immunoglobulin M, and complement C3 values alongside the serum lysozyme and catalase activities were significantly increased compared to the CTR group. Contrarywise, serum transaminases (alanine transaminase and aspartate transaminase), cortisol, urea, and creatinine values were significantly decreased in OS groups than the CTR group. No significant differences were noticed in the mRNA transcripts of the hepatic heat shock protein 70 among all experimental groups. Meanwhile, significant differences were observed in the mRNA transcripts of hepatic heat shock protein 27, superoxide dismutase, and glutathione peroxidase genes among all experimental groups. The second order polynomial regressions illustrated that the optimal inclusion OS level in diets for Nile tilapia reared under sub-optimal temperature is 0.36-0.39 mg/kg diet based on weight gain and cortisol levels, respectively. Conclusively, the present study exemplified that dietary inclusion with 0.36-0.39 mg OS/kg diet improved the growth, immunity and modulate the stress responses in Nile tilapia reared under sub-optimal temperature.

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.

Gut immune-related gene expression, histomorphometry and hematoimmunological assays in Nile tilapia (Oreochromis niloticus) fed Aspergillus oryzae fermented olive cake.

Fermentation strategy is well documented to improve the nutritional value of agricultural waste by-products such olive cake (OC), which, in turn, provides healthy, safe, and affordable feedstuff. This study assessed the combined impact of Aspergillus oryzae-fermented OC (AFOC) on the growth performance, intestinal morphometry, blood biochemistry, lysozyme activity, gut immune-related genes, and flesh quality of Nile tilapia. We divided 225 fish into five groups and further subdivided into three replicates (n = 15 each) and fed them five diets (Control, AFOC5, AFOC10, AFOC15, AFOC20) to determine AFOC nutritional value and its optimized incorporation level in the diet. The trial continued for 3 months. The crude protein content of OC improved by 7.77% after A. oryzae fermentation, while lipid content decreased by 14.19%. In addition, growth and feed utilization significantly improved at (10.8-11.2) % AFOC dietary level. High-density lipoprotein (HDL) significantly improved, and the serum lysozyme level was significantly higher in the AFOC10 group compared to other groups. Interestingly, gut-related inflammatory cytokines tumor necrosis factor alpha (TNF- α) and interleukin 1 beta (IL-1ß) revealed higher relative mRNA expression in the AFOC10 group compared to other groups. The histomorphometric parameters was greatly influenced by the AFOC incorporation level (10%-20%). These findings suggested that A. orzae fermentation modifies the nutritional quality of OC, as seen through its positive impact on the growth performance, local and systemic immunity, and intestinal absorptive capacity of Nile tilapia. The recommended dose for dietary AFOC was around 11.

Effects of sodium butyrate and Lippia origanoides essential oil blend on growth, intestinal microbiota, histology, and haemato-immunological response of Nile tilapia.

This study aimed to verify the effects of dietary supplementation with sodium butyrate and Lippia origanoides, combined and isolated, on the health and zootechnical performance of Nile tilapia juveniles Oreochromis niloticus. A total of 120 fish (5.38 ± 0.65 g) were randomly distributed in 12 experimental units and fed different experimental diets for 30 days, namely: commercial diet without supplementation (Unsupplemented); commercial diet supplemented with 0.5% sodium butyrate (Butyrate); commercial diet supplemented with 0.125% L. origanoides (Lippia) and commercial diet supplemented with a mixture of 0.5% sodium butyrate and 0.125% L. origanoides (Butyrate + Lippia). After preparing the experimental diets there was an increase in the pH of diet Butyrate when compared to the other diets. After 30 days the fish supplemented with Butyrate + Lippia showed reduction significate in the mean corpuscular haemoglobin, concentration of total heterotrophic bacteria in the intestine, and lymphocyte infiltrates in the liver. Besides that, the supplementation with Butyrate + Lippia promoted an increased number of intestinal villi compared to the fish Unsupplemented ones. Additionally, fish fed a diet containing only Lippia presented an increase in the villus perimeter in the posterior region of the gut and in the red blood cell number. Animals supplemented only with sodium butyrate demonstrated increased lactic acid bacterium in the gut and macrosteatosis in the liver, besides decreased melanomacrophages in the spleen. The use of sodium butyrate associated with essential oil had positive effects on the intestinal microbiota, intestinal structure, liver, and spleen integrity, suggesting a greater efficiency of the compounds when used together in the nutrition of Nile tilapia juveniles.

Hot water extract of Pleurotus pulmonarius stalk waste enhances innate immune response and immune-related gene expression in red hybrid tilapia Oreochromis sp. following challenge with pathogen-associated molecular patterns.

In aquaculture, commercial fish such as red hybrid tilapia are usually raised at high density to boost the production within a short period of time. This overcrowded environment, however, may cause stress to the cultured fish and increase susceptibility to infectious diseases. Antibiotics and chemotherapeutics are used by fish farmers to overcome these challenges, but this may increase the production cost. Studies have reported on the potential of mushroom polysaccharides that can act as immunostimulants to enhance the immune response and disease resistance in fish. In the current study, hot water extract (HWE) from mushroom stalk waste (MSW) was used to formulate fish feed and hence administered to red hybrid tilapia to observe the activation of immune system. Upon 30 days of feeding, the fish were challenged with pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharides (LPS) and polyinosinic:polycytidylic acid (poly (I:C)) to mimic bacterial and viral infection, respectively. HWE supplementation promoted better feed utilisation in red hybrid tilapia although it did not increase the body weight gain and specific growth rate compared to the control diet. The innate immunological parameters such as phagocytic activity and respiratory burst activity were significantly higher in HWE-supplemented group than that of the control group following PAMPs challenges. HWE-supplemented diet also resulted in higher mRNA transcription of il1b and tnfa in midgut, spleen and head kidney at 1-day post PAMPs injection. Tlr3 exhibited the highest upregulation in the HWE fed fish injected with poly (I:C). At 3-days post PAMPs injection, both ighm and tcrb expression were upregulated significantly in the spleen and head kidney. Results showed that HWE supplementation enhances the immune responses of red hybrid tilapia and induced a higher serum bactericidal activity against S. agalactiae.

Modulation of growth, innate immunity, and disease resistance of Nile tilapia (Oreochromis niloticus) culture under biofloc system by supplementing pineapple peel powder and Lactobacillus plantarum.

Eight weeks feeding experiment was managed to evaluate the impacts of dietary addition of pineapple peel powder (PAPP) and Lactobacillus plantarum CR1T5 (LP) individual or mixed on growth performance, skin mucus and serum immunities, as well as disease resistance of Nile tilapia. Fish (average weight 20.91 ± 0.11 g) were fed four diets: Diet 1 (0 g kg-1 PAPP and 0 CFU g-1 L. plantarum, Diet 2 (10 g kg-1 PAPP), Diet 3 (108 CFU g-1L. plantarum), and Diet 4 (10 g kg-1 PAPP + 108 CFU g-1L. plantarum). Serum and mucus immune responses, as well as growth rate, were assessed every 4 weeks. Ten fish were chosen for the challenge test with Streptococcus agalactiae after 8 weeks post-feeding. The findings showed that PAPP and/or LP diets increased (P ≤ 0.05) growth performance, skin mucus, and serum immune responses. The best data were obtained in fish fed a mixture of PAPP and LP. Nevertheless, no variation (P > 0.05) was recorded between groups fed PAPP or LP. The relative survival percentage (RSP, %) in Diet 2, Diet 3, and Diet 4 was 46.15%, 50.0%, and 73.08%. Fish fed mixture of PAPP + LP recorded the best (P < 0.05) survival rate versus other treatments. The current findings recommended using a mixture of PAPP and LP as promising functional additives for aquaculture practice.

Immune response and protective efficacy of two new adjuvants, Montanide™ ISA 763B VG and Montanide™ GEL02, administered with a Streptococcus agalactiae ghost vaccine in Nile tilapia (Oreochromis niloticus).

Streptococcus agalactiae is one of the most important pathogens infecting tilapia worldwide and causes meningoencephalitis, septicemia and high mortalities with considerable losses. Various types of vaccines have been developed against S. agalactiae infection, such as inactivated vaccines, live attenuated vaccines and subunit vaccines. Bacterial ghosts (BGs) are nonliving, empty cell envelopes and have been reported as novel vaccine candidates. Therefore, the main aims of this study were to develop an S. agalactiae ghost vaccine (SAGV) and to evaluate the immune response and protective effect of SAGV against S. agalactiae with two novel adjuvants, Montanide™ ISA 763B VG and Montanide™ GEL02. Nile tilapia, mean weight 50 g, were divided into four groups as follows; 1) fish injected with PBS as control, 2) fish injected with the SAGV alone; 3) fish injected with the SAGV+Montanide™ ISA 763B VG; and 4) fish injected with SAGV+Montanide™ GEL02. Following vaccination, innate immunity parameters including serum lysozyme, myeloperoxidase, catalase, and bactericidal activity were all significantly enhanced. Moreover, specific serum IgM antibodies were induced and reached their highest level 2-8 weeks post vaccination. Importantly, the relative percent survival of tilapia vaccinated against the SAGV formulated with both adjuvants was 80-93%. Furthermore, the transcription of immune-related genes (IgM, TCRß, IL-1ß, IL-8 and TNFα) were up-regulated in tilapia after vaccination, indicating that both cellular and humoral immune responses were induced by these adjuvanted vaccines. In summary, Montanide™ ISA 763B VG and Montanide™ GEL02 can enhance immunoprotection induced by the SAGV vaccine against streptococcosis, demonstrating that both have value as potential adjuvants of fish vaccines.

Ginkgo biloba leaf extract improves growth, intestinal histomorphometry, immunity, antioxidant status and modulates transcription of cytokine genes in hapa-reared Oreochromis niloticus.

This study was designed to evaluate the impacts of dietary supplementation with Ginkgo biloba leaf extract (GBL) on the growth, intestinal histomorphometry, immunity, antioxidant status, and expression of cytokine genes in Nile tilapia reared in the hapas. A control diet was enriched with different GBL levels (0.0, 5.0, 7.0, and 9.0 g/kg) to form 4 experimental diets and were fed to Nile tilapia for 8 weeks. The findings illustrated that dietary GBL significantly enhanced the growth and feed utilization indices compared to those reared in the control group. A dose-dependent increase of hepatic catalase, superoxide dismutase, and glutathione peroxidase activities alongside a decline of hepatic malondialdehyde levels were recorded in GBL groups compared with the control. Serum lysozyme activity, complement C3, and immunoglobulin M levels were significantly increased in GBL groups compared with the control group. Moreover, dietary GBL maintained the normal intestinal and hepatopancreatic histological structures with a significant increase of some histomorphometric measurements of proximal, middle, and distal intestinal parts of the treated fish. Interestingly, dietary GBL supplementation significantly increased the mRNA expression of interleukin-1 beta (IL-1ß), IL-6, IL-10, tumor necrosis factor alpha (TNF-α) and interferon gamma (INF-γ) genes in the splenic tissues of treated fish over the control group. To conclude, it could be recommended to use GBL as a functional phytogenic feed additive to improve the growth, hepatic and intestinal health status, hepatic antioxidant status, and immunity of treated Nile tilapia. Besides, the second order polynomial regression revealed that 7.50 g GBL/kg diet is the optimal inclusion level to improve growth with no negative impacts on the overall health condition of treated Nile tilapia.

Dietary cinnamaldehyde nanoemulsion boosts growth and transcriptomes of antioxidant and immune related genes to fight Streptococcus agalactiae infection in Nile tilapia (Oreochromis niloticus).

The present study was conducted to investigate the effects of dietary cinnamaldehyde nanoemulsion (CNE) on growth, digestive activities, antioxidant and immune responses and resistance against Streptococcus agalactiae (S. agalactiae) in Nile tilapia. Four experimental diets were formulated containing CNE at levels of 0, 100, 200 and 300 mg/kg diet for 12 weeks. At the end of the experiment, all fish were challenged by S. agalactiae. The results showed that the final body weight was increased in fish groups fed 200 and 300 mg CNE/kg diet by 18.4 and 17.2% with respect to the control group. Moreover, feed conversion ratio and digestive enzymes' activities were improved in groups fed 200 and 300 then 100 mg of dietary CNE/kg diet. Groups fed CNE exhibited a significant increase in serum immune-related parameters when compared with control group. Additionally, the hypocholesterolemic effects was achieved after CNE feeding unlike the control group in a dose dependent manner. With increasing dietary CNE levels, genes expression of cytokines and antioxidant enzymes were upregulated. Less severe adverse clinical symptoms and respectable cumulative mortalities associated with S. agalactiae infection were observed in fish fed CNE. To our knowledge, this study was the first offering a protective effect of CNE against S. agalactiae infection in Nile tilapia with a maximum down-regulation of cylE and hylB virulence genes expression noticed in group fed 300 mg of CNE/kg diet (up to 0.10 and 0.19- fold, respectively). Therefore, the present study recommended that an incorporation of CNE at level of 300 mg/kg diet for Nile tilapia could promote their growth, enhance their immunity and antioxidant status and provide protection against virulent S. agalactiae.

Dietary spirulina (Arthrospira platenesis) mitigated the adverse effects of imidacloprid insecticide on the growth performance, haemato-biochemical, antioxidant, and immune responses of Nile tilapia.

The present study was performed to evaluate the toxic effects of imidacloprid (IMI) insecticide on the growth performance, oxidative status, and immune response of Nile tilapia, Oreochromis niloticus (L.), and the protective role of dietary supplementation of spirulina, Arthrospira platensis, (SP). Fish (20.2 ± 0.5 g) were assigned to bifactorial design (2 IMI levels x 3 SP levels) to represent 6 treatments in triplicates. Spirulina was incorporated in diets at levels of 0.0 (control), 20, and 40 g/kg diet. Under each SP level, fish were exposed to 0.0 or 0.05 µg IMI/L. Fish in each treatment were fed on the corresponding diets up to apparent satiation thrice a day for 8 weeks. Two-way ANOVA revealed a significant decline in growth indices, hepatic superoxide dismutase, catalase, and glutathione peroxidase activities in the IMI-exposed fish. Contrariwise, serum alanine and aspartate aminotransferases, alkaline phosphatase, urea, creatinine, and malondialdehyde levels were markedly higher along with significant reductions of the reduced glutathione, nitric oxide as well as lysozyme values in the IMI-exposed fish group. The dietary supplementation of SP showed stimulating effects on the growth performance, haemato-biochemical, oxidants/antioxidants, and immune biomarkers of Nile tilapia with optimum level of 20 g SP/kg diet. Interestingly, the dietary supplementation of SP to Nile tilapia attenuated the above-mentioned variables with improving the growth performance, haemato-biochemical, oxidative stress, and immunity biomarkers. Therefore, the dietary supplementation of 20 g SP /kg diet could be a valuable candidate as a natural antioxidant for ameliorating the IMI toxicity in Nile tilapia.

The influence of coconut oil on the growth, immune, and antioxidative responses and the intestinal digestive enzymes and histomorphometry features of Nile tilapia (Oreochromis niloticus).

The trials of finding non-conventional and alternative aquafeed ingredients are increasing. In this sense, this study evaluated the influence of coconut oil on the growth, feed utilization, immune, and antioxidative responses of Nile tilapia. Five test diets were formulated by mixing coconut oil with the other ingredients at 0, 1, 2, 3, and 4% of the total ration and presented for tilapia for 60 successive days. The final weight, SGR, weight gain (WG), and feed intake were superior in fish delivered 2% of coconut oil (P < 0.05). Concurrently, fish that received 2% coconut oil had lower FCR and higher PER than fish of the control and 4% groups (P < 0.05). Higher lipase activity was observed in fish of 2% and 3% levels than the remaining groups (P < 0.05). Besides, the amylase and protease activities of fish in 1%, 2%, and 3% groups were higher than the 0% level (P < 0.05). The total blood cholesterol, RBCs, and PCV showed higher values in Nile tilapia fed 2% and 3% coconut oil (P < 0.05). The lysozyme and phagocytic activities were higher in fish fed 2% and 3% levels than the control (P < 0.05), while the phagocytic index in 2% and 3% levels was higher than 0% and 4% levels. Furthermore, SOD and CAT were higher in fish fed 1%, 2%, and 3% than fish fed 0% and 4% levels while GSH was higher in fish of 1%, 2%, and 3% than fish fed 0% level (P < 0.05). However, the MDA level was markedly lower in fish fed 25, 3%, and 4% coconut oil than the 0% level (P < 0.05). The intestine's histological structure in all groups appeared normal, forming of intestinal villi projecting from the intestinal wall. Also, the structure of the hepatopancreas had a normal architecture in all groups. To sum up, the inclusion of coconut oil at 2 to 3% is recommended as a replacer for fish oil in Nile tilapia diets.

Dietary ß-glucan (MacroGard®) improves innate immune responses and disease resistance in Nile tilapia regardless of the administration period.

The effects of dietary ß-glucan on innate immune responses have been shown in a number of different vertebrate species. However, there is conflicting information about the period of administration (shorter vs. longer), and it is also unclear to what extent ß-glucan's effects can be observed post-treatment in fish. Thus, we fed Nile tilapia for 0 (control group; 45 days of control diet), 15 (30 days of control followed by 15 days of ß-glucan), 30 (15 days of control followed by 30 days of ß-glucan) or 45 days with a diet containing 0.1% of ß-glucan (MacroGard®). We evaluated the growth performance at the end of the ß-glucan feeding trial and the innate immune function immediately after the feeding trial and 7 and 14 days post-feeding trial. In addition, at day 10 post-feeding trial, we assessed the tilapia's resistance against a bacterial infection. No significant differences were observed in growth performance between the groups; however, fish fed with ß-glucan for 30 and 45 days had higher (approx. 8%) relative weight gain compared to the control. Regardless of the administration period, fish fed with ß-glucan had higher innate immune responses immediately after the feeding trial such as lysozyme activity in plasma, liver and intestine and respiratory burst compared to the control, and in general these differences were gradually reduced over the withdrawal period (up to 14 days). No differences were observed in the plasma hemolytic activity of the complement or myeloperoxidase activity in plasma or intestine. Moreover, fish from the control group had early mortalities (2 vs. 4-5 days post-infection, respectively) and a lower survival rate (60 vs. 80%, respectively) compared to fish fed with ß-glucan for 15 or 30 days, and, interestingly, fish fed for 45 days with ß-glucan had no mortality. This study indicates that regardless of the administration period (i.e., 15 up to 45 days), the ß-glucan improved the innate immune responses and the tilapia's resistance to disease, and this protection could be observed up to 10 days post-feeding trial, adding in vivo evidence that ß-glucan may contribute to a trained innate immunity. Additionally, we showed that a longer period of administration did not cause immunosuppression as previously hypothesized but promoted further growth and immune performance. These findings are relevant to the aquaculture industry and demonstrate that a longer ß-glucan feeding protocol may be considered to achieve better results.

Effects of bovine lactoferrin and chitosan nanoparticles on serum biochemical indices, antioxidative enzymes, transcriptomic responses, and resistance of Nile tilapia against Aeromonas hydrophila.

The present study was carried out to investigate the effects of dietary bovine lactoferrin (BLF) or chitosan nanoparticles (CHN) alone or in combinations on serum biochemical indices, antioxidative capacity, transcriptomic responses, non-specific immunity, and resistance of Nile tilapia (Oreochromis niloticus) against challenge with Aeromonas hydrophila. Fish were fed on the basal diet with no supplements and served as control (CTR), and six other experimental diets containing different levels of BLF (800 and 1200 mg per kg diet), CHN (500 and 1000 mg per kg diet), and their combinations (400 mg BLF plus 250 mg CHN per kg diet, and 600 mg BLF plus 500 mg CHN per kg diet) for 45 days. At the end of the experiment, serum, and tissue specimens (liver and kidney) were collected, fish in all groups were challenged with A. hydrophila and then observed for another ten days to calculate the RPS. Compared to the CTR group, no significant differences were recorded in TP, ALB, GLO, BUN, and CREAT values among all treatments. Serum LYZ, ALT, AST, and ALP enzyme activities were significantly increased in all experimental groups over the CTR (P < 0.05), and their highest values were recorded in the combined treatments. Moreover, dietary supplementation with CHN (1000 mg/kg) and combined treatments significantly increased the SOD, CAT, and GSH-Px enzyme activities compared to other groups (P < 0.05). The highest mRNA expression levels of IGF-1 gene in liver, and IL-1ß, and IFN-γ genes in kidneys were found in CHN (1000 mg/kg) group and combined treatments more than other groups. Interestingly, no, or mild histopathological alterations were noticed in the hepatopancreas and posterior kidney of the treated groups. A significantly higher RPS was identified in the combined treatments challenged with A. hydrophila compared with the CTR group. This study exemplifies the positive impacts of dietary supplementation with BLF or CHN alone or combinations on the antioxidative status, immunity, and disease resistance of Nile tilapia.