Droplet digital PCR for fish pathogen detection and quantification: A systematic review and meta-analysis.

This study provides a comprehensive summary of the findings regarding the application and diagnostic efficacy of droplet digital PCR (ddPCR) in detecting viral and bacterial pathogens in aquaculture. Utilizing a systematic search of four databases up to 6 November 2023, we identified studies where ddPCR was deployed for pathogen detection in aquaculture settings, adhering to Preferred Reporting Items for Systematic Reviews and Meta-analysis of Diagnostic Test Accuracy guidelines. From the collected data, 16 studies retrieved, seven were included in a meta-analysis, encompassing 1121 biological samples from various fish species. The detection limits reported ranged markedly from 0.07 to 34 copies/µL. A direct comparison of the diagnostic performance between ddPCR with quantitative PCR (qPCR) proved challenging due to limited data, thus only a pooled sensitivity analysis was feasible. The results showed a pooled sensitivity of 0.750 (95% confidence interval [CI]: 0.487-0.944) for ddPCR, compared to 0.461 (95% CI: 0.294-0.632) for qPCR, with no statistically significant difference in sensitivity between the two methods (p = .5884). Notably, significant heterogeneity was observed among the studies (I2 = 93%-97%, p < .01), with the year of publication significantly influencing this heterogeneity (p < .001), but not the country of origin (p = .49). No publication bias was detected, and the studies generally exhibited a low risk of bias according to QUADAS-C criteria. While ddPCR and qPCR showed comparable sensitivities in pathogen detection, ddPCR's capability to precisely quantify pathogens without the need for standard curves highlights its potential utility. This characteristic could significantly enhance the accuracy and reliability of pathogen detection in aquaculture.

Synergetic response on herbal and probiotic applications: a review.

Herbs and their by-products are important traditional medicines and food supplements; they provide numerous beneficial effects for animals. Consequently, probiotics are living cell organisms, nontoxic, and friendly microbes. Probiotics have numerous beneficial activities such as inhibition of pathogens, enhancement of the immune system, growth, disease resistance, improving water quality, reducing toxic effects, synthesis of vitamins, prevention of cancer, reduction of irritable bowel syndrome, and more positive responses in animals. Herbal and probiotic combinations have more active responses and produce new substances to enhance beneficial responses in animals. Herbal and probiotic mixture report is still limited applications for animals. However, the mechanisms by which they interact with the immune system and gut microbiota in animals are largely unclear. This review provides some information on the effect of herbal and probiotic blend on animals. This review discusses current research advancements to fulfill research gaps and promote effective and healthy animal production.

Effects of extended dietary supplementation with Santalum album essential oil on hemato-biochemical changes, innate immune response, antioxidant status, and expression of related gene in Nile tilapia (Oreochromis niloticus).

The effects of long-term dietary supplementation with sandalwood (Santalum album L.) essential oil (SEO) was investigated on hemato-biochemical biomarkers, immune status, antioxidant capacity, and resistance against Staphylococcus aureus in Nile tilapia (Oreochromis niloticus). Five groups (with four replicates) of O. niloticus (12.60 ± 0.20 g) were fed diets supplemented with SEO at doses of 0, 0.5, 1.0, 2.0, and 4.0 mL/kg diet for 60 days. Results indicated a substantial increase in blood protein levels and lower serum cholesterol, cortisol, glucose, urea, creatinine levels and, transaminase activities of fish fed a 2.0-mL SEO/kg diet. Serum lysozyme activity, nitric oxide, complement-3 levels, and phagocytic activity were significantly improved in O. niloticus after 60 days of feeding SEO-supplemented diets. Dietary SEO at level of 2.0-mL SEO/kg diet increased the activities of SOD, CAT, and GPx, and decreased MDA levels in liver homogenate. In addition, dietary 2.0-mL SEO/kg diet significantly upregulated antioxidant genes expression (CAT, SOD, GPx, GST, and GSR) with downregulation of apoptotic genes (HSP70, TLR2, caspase-3, and PCNA) in the liver. Furthermore, SEO-enriched diets significantly down-regulated pro-inflammatory (TNF-α, IL-1ß, and IL-8) and up-regulated anti-inflammatory cytokine genes (TFG-ß and IL-10) in the spleen. Moreover, SEO fortification increased the relative percentage of survival against S. aureus challenge and regulated immune-antioxidant genes in the spleen after the challenge. Overall, the results revealed that long-term using SEO might strengthen the physiological performance, hepatic oxidant/antioxidant balance, innate immune response, and resistance of O. niloticus against bacterial infections.

Effects of hyperoxia during oxygen nanobubble treatment on innate immunity, growth performance, gill histology, and gut microbiome in Nile tilapia, Oreochromis niloticus.

Oxygen nanobubble (NB-O2) technology has been introduced to the aquaculture industry in recent years. This treatment usually results in a tremendously high level of dissolved oxygen (DO) in the water. However, little is known about the possible negative effects of hyperoxia due to NB-O2 treatment (hyper-NB-O2) on farmed fish. Here, we investigated i) the effect of short-term hyper-NB-O2 exposure (single treatment) on the innate immunity in Nile tilapia, Oreochromis niloticus, and ii) the effect of long-term hyper-NB-O2 exposure (26-day treatments) on survival, growth performance, gill histology, and gut microbiome in Nile tilapia. A single treatment with NB-O2 for 10 min in 50 L of water resulted in 24.2 ± 0.04 mg/L DO (approximately 2-3 × 107 nanoscale oxygen bubbles/mL). This treatment did not result in differences in expression of several immune-related genes (e.g., TNF-α, LYZ and HPS70) in various tissues (e.g., gill, head kidney, and spleen) compared to the non-treated control. Over a 26-day period of exposure, no significant differences were observed in survival and growth performance of the fish, but minor histological changes were occasionally noted on the gills. Analysis of the gut microbiome revealed a significant increase in the genera Bosea, Exiguobacterium, Hyphomicrobium, and Singulisphaera in the group receiving NB-O2. Moreover, no signs of "gas bubble disease" were observed in the fish throughout the duration of the experiment. Overall, these results suggest that both short- and long-term hyper-NB-O2 exposure appears to be benign and has no obvious adverse effects on fish.

Toxic and bioaccumulative effects of zinc nanoparticle exposure to goldfish, Carassius auratus (Linnaeus, 1758).

The widespread use of produced metal oxide nanoparticles (NPs) has increased major concerns about their impact on human as well as aquatic animal health. The present study shows that exposure to different concentrations of zinc oxide (ZnO) NPs led to high accumulations of Zn ions in the metabolic organs of fish (liver and gills), resulting in severe oxidative stress in Carassius auratus. The goldfish (C. auratus) was chosen as an aquatic species for the evaluation of the potential toxicity of aqueous ZnO-NPs (Treatments of hemoglobin and neutrophils (0, 0.5, 1, and 1.5 mg L- 1) following 14 days of exposure. A range of histological and hematological factors were examined. Exposure to the NPs produced significant reduction of red blood cell and white blood cell counts, hematocrit) were found to produce no significant differences in lymphocyte, monocyte, and eosinophil counts; as well as the mean corpuscular hemoglobin concentrations index (P > 0.05). Moreover, the results revealed significant alterations in serum biochemical parameters, hepatic enzyme levels, and immune and antioxidant responses; except for total protein and superoxide dismutase (SOD) of C. auratus exposed to ZnO-NPs, particularly at the 1 and 1.5 mg L- 1 concentrations. Fish exposed to 1 and 1.5 mg L-1 ZnO-NPs displayed a significant reduction in alternative complement pathway activity, lysozyme, and total protein contents of mucus compared to those in the control group. The results showed that hepatic SOD and catalase, and gill catalase activity were significantly decreased, and their malondialdehyde levels increased at 1 and 1.5 mg L-1 ZnO-NPs compared to the control group (P < 0.05). Significant accumulations of ZnO-NPs were observed in the liver, kidney, and gill tissues of fish leading to severe histopathological alterations in these organs. These results suggest that water-borne ZnO-NPs can easily accumulate in metabolic organs and lead to oxidative stress and destructive effects on the physiological features of C. auratus.

Effect of Different Levels of Chlorogenic Acid on Growth Performance, Immunological Responses, Antioxidant Defense, and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss) Juveniles.

The current study is designed to assay the efficacy of chlorogenic acid (ChA) in the diet on growth performance, digestive enzyme activity, serum immunological, biochemical, and antioxidant variables, and mucosal immune response as well as disease resistance of rainbow trout (Oncorhynchus mykiss) juveniles. Rainbow trout juveniles received diets supplemented with different inclusion levels of ChA (0 (ctrl), 200 (CA1), 400 (CA2), 600 (CA3), and 800 (CA4) mg kg-1 diet) for 60 days. According to the findings, fish from CA3 and CA4 groups demonstrated the best results considering the final weight (FW) and weight gain (WG) (P < 0.05). Also, the group that received 600 mg kg-1 ChA-supplemented diet showed the lowest feed conversion ratio (FCR) and the highest specific growth rate (SGR) compared to other groups (P < 0.05). Moreover, the minimum survival rate (SR) was only detected in the CA4 treatment (P < 0.05). Regression analysis exhibited that rainbow trout growth indices were polynomially linked to dietary chlorogenic acid concentrations. In this regard, the optimal levels of chlorogenic acid according to growth parameters (FCR and SGR) were 0.71 and 0.62 gr kg-1 diet, respectively. The results exhibited superior performance of protease and amylase activities in CA2, CA3, and CA4 groups with the maximum amount in the group receiving 600 mg kg-1 ChA-enriched diet (P < 0.05). Serum lysozyme (LYZ), immunoglobulin (Ig), and components 3 and 4 (C3 and C4) values of CA2, CA3, and CA4 groups were significantly higher than others with the highest amount in the CA3 group (P <0.05). Additionally, serum nitroblue tetrazolium (NBT) value in the CA3 and CA4 groups and myeloperoxidase (MPO) in the CA3 group were notably more than others (P < 0.05). Moreover, the lowest aspartate aminotransferase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) and the highest total protein (TP) and globulin (GLO) values were observed in CA3 treatment (P < 0.05). CA2 and CA3 groups demonstrated increased serum catalase (CAT) and decreased malondialdehyde (MDA) values compared to the control while the highest CAT and lowest MDA values were observed in CA3 treatment (P < 0.05). Considering mucus immunity, the significantly maximum LYZ and protease values were demonstrated in CA2 and CA3 groups, and the highest ALP, Ig, and esterase values were demonstrated in the CA3 group. In comparison with the control, the mortality rates of the groups that received the ChA diets were remarkably (P < 0.05) lower postchallenge with Y. ruckeri, and the highest survival and relative percentage of survival (RPS) (P < 0.05) belonged to the CA3 group. Results obtained from the current study suggested ChA as a functional dietary additive to raise growth parameters, immune indices, antioxidant capacity, and resistance to disease in rainbow trout.

Quercetin Application for Common Carp (Cyprinus carpio): I. Effects on Growth Performance, Humoral Immunity, Antioxidant Status, Immune-Related Genes, and Resistance against Heat Stress.

This study was done to evaluate the effect of different quercetin levels on growth performance, immune responses, antioxidant status, serum biochemical factors, and high-temperature stress responses in common carp (Cyprinus carpio). A total number of 216 common carp with an average weight of 27.21 ± 53 g were divided into 12 tanks (four treatments × three replications) and fed 0 mg/kg quercetin (T0), 200 mg/kg quercetin (T1), 400 mg/kg quercetin (T2), and 600 mg/kg quercetin (T3) for 60 days. There were significant differences in growth performance, and the highest final body weight (FBW), weight gain (WG), specific growth rate (SGR), and feed intake (FI) were observed in T2 and T3 (P < 0.05). Different quercetin levels significantly increased complement pathway activity (ACH50) and lysozyme activity both before and after heat stress (P < 0.05). Catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) were significantly increased in fish exposed to heat stress, but fish fed with a supplemented diet with quercetin showed the lowest levels both before and after heat stress (P < 0.05). Superoxide dismutase (SOD) levels were significantly enhanced in fish fed diets supplemented with quercetin in both phases (P < 0.05). Different quercetin levels led to a significant decrease in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) before and after the challenging test (P < 0.05). Glucose and cortisol levels were significantly higher in the control group compared to the other treatments in both phases (P < 0.05). The expression of glutathione peroxidase (GPx) and lysozyme was markedly upregulated in fish fed with quercetin-supplemented diets (P < 0.05). No marked effects were observed for growth hormone (GR) and interleukin-8 (IL8) (P > 0.05). In conclusion, dietary quercetin supplementations (400-600 mg/kg quercetin) improved growth performance, immunity, and antioxidant status and increased tolerance to heat stress.

Modulation of humoral immunological and antioxidant responses and gut bacterial community and gene expression in rainbow trout, Oncorhynchus mykiss, by dietary lactic acid supplementation.

The present study was conducted to find the effects of dietary lactic acid (LA) supplementation on growth performance, hematological characteristics, humoral antioxidant and immunological factors, intestinal gene expression and bacteriological parameters in rainbow trout, Oncorhynchus mykiss. The fish (104 ± 0.90 g) were randomly distributed in twelve tanks (150 L water) as four treatments, receiving diets supplemented with 0, 5, 10, and 20 g/kg LA for 70 days. At the end of the feeding trial, no significant differences were observed in the fish growth performance and survival among the treatments. Blood/plasma red blood cell (5-20 g/kg LA), white blood cell (10 g/kg LA), hematocrit (5 and 10 g/kg LA), hemoglobin (5 and 10 g/kg LA), superoxide dismutase (10 g/kg LA), glutathione peroxidase (10 g/kg LA), total antioxidant capacity (10 g/kg LA), lysozyme (5-20 g/kg LA), and alternative complement activity (10 g/kg LA) significantly increased, as malondialdehyde (10 g/kg LA) significantly decreased in the LA-treated fish. Dietary LA supplementation induced no significant changes in the intestinal defensin gene expression, but significantly up-regulated the expression of toll-like receptor-3 (5-20 g/kg LA), Mx-9 (5-20 g/kg LA), and heat shock protein-70 (5 g/kg LA) genes; the highest expressions were observed at 5 g/kg LA supplementation. Dietary LA supplementation significantly increased total bacterial count (5 and 10 g/kg LA), Lactobacillus sp. (5-20 g/kg LA), and Bacteroides sp. (5-20 g/kg LA), but decreased Streptococcus iniae (5-20 g/kg LA) in the fish intestine; the highest Lactobacillus sp. And Bacteroides sp. Were observed in 10 and 5 g/kg LA supplementation, respectively. Overall, dietary LA supplementation, although has no significant effects on the fish growth performance, is beneficial to improve humoral antioxidant parameters, humoral and intestinal immunological parameters and intestinal microflora. According to the results, dietary 5-10 g/kg LA is recommended for the formulation of rainbow trout feed.

Bioactive immunostimulants as health-promoting feed additives in aquaculture: A review.

Bioactive immunostimulants could be derived from different sources like plants, animals, microbes, algae, yeast, etc. Bioactive immunostimulants are the most significant role to enhance aquatic production, as well as the cost of this method, which is effective, non-toxic, and environment-friendly. These immunostimulants are supportive to increase the immune system, growth, antioxidant, anti-inflammatory, and disease resistance of aquatic animals' health and also improve aquatic animal feed. Diseases are mainly targeted to the immune system of aquatic organisms in such a way that different processes of bioactive immunostimulants progress are considered imperative techniques for the development of aquaculture production. Communicable infections are the main problem for aquaculture, while the mortality and morbidity connected with some outbreaks significantly limit the productivity of some sectors. Aquaculture is considered the mainly developing food production sector globally. Protein insists is an important issue in human nutrition. Aquaculture has been an exercise for thousands of years, and it has now surpassed capture fisheries as the most vital source of seafood in the world. Limited study reports are available to focal point on bioactive immunostimulants in aquaculture applications. This review report provides information on the nutritional administration of bioactive immunostimulants, their types, functions, and beneficial impacts on aquatic animals' health as well as for the feed quality development in the aquaculture industry. The scope of this review combined to afford various kinds of natural derived bioactive molecules utilization and their beneficial effects in aquaculture applications.

Immunomulation effect of alginic acid and chitooligosaccharides in silver carp (Hypophthalmichthys molitrix).

Individual and combined efficacy of chitooligosaccharides (COS) and alginic acid (AA) at 1 g, 2 g, and 3 g per kg diet was assessed on growth and disease resistance in silver carp (Hypophthalmichthys molitrix) against Edwardsiella ictaluri. Growth parameters including specific growth rate (SGR), weight gain (WG), and feed conversion rate (FCR) were significant in fish fed 2 g and 3 g kg-1 of COS or AA, and fish fed combined COS + AA at 1, 2 and 3 kg-1 diet. In all groups, the survival rate (SR) was recorded 100%, except in group fed 2 g kg-1 AA diet. All the hematological and biochemical profiles significantly increased in groups fed 2 g and 3 g kg-1 of COS, AA, and COS + AA diets. Lipase and amylase enzyme activities and superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPx) antioxidant enzyme activities were significantly increased in fish fed 2 g and 3 g kg-1 of COS, AA, and COS + AA diet. Respiratory burst (RB), lysozyme (Lyz), reactive oxygen species (ROS) activities, and immunoglobuline (Ig) level were enhanced significantly in fish fed 2 g kg-1 of COS or COS + AA and all 3 g kg-1 diets, whereas nitric acid (NO) production and serum AP activity were improved in 2 g kg-1 COS + AA and 3 g kg-1 COS or COS + AA diets. Pro-inflammatory cytokine such as IL-8 mRNA transcriptions was significant in 2 g kg-1 COS + AA diet and all 3 g kg-1 diet. The IL-10 anti-inflammatory cytokine mRNA transcriptions were significant in 3 g kg-1 COS or COS + AA diets. This study was confirmed that H. molitrix fed with 3 g kg-1 COS or COS + AA diets were better activity when compared to other diet.

Antioxidative and immunostimulant potential of fruit derived biomolecules in aquaculture.

Huge amounts of non-edible by-products could be generated from fruit industrial processes. They consist mainly of peels together with low amounts of pulp and seeds. These by-products pose an environmental hazard due to soil, air, and water pollution. Moreover, treating these by-products is very expensive and under strict governmental regulations. Nevertheless, they are an excellent source of bioactive constituents, such as phenols, flavonoids, terpenes, and glucans. Based on their constituents, these by-products can significantly enhance the antioxidant defense, immune response, and modulation of gut microbiota and host resistance against various diseases. Therefore, sustainable valorization of fruits by-products can efficiently obtain value-added products that improve the well-being of organisms and reduce environmental stress, in addition to earning an additional industrial income. Since aquaculture is a vital economic sector, there is urgent to look for inexpensive natural food additives that improve health and maintain high nutritional quality for farming organisms without harming the environment and human health. Therefore, using fruit wastes as feed additives represents a striking alternative for fruitful aquaculture. In order to make use of these value-added products, it is a dire need to determine their biological effects on aquaculture organisms by understanding their mechanism of action. In this context, this review will holistically address a comprehensive focus on utilizing fruits by-products and their immunostimulant and antioxidative action.

Dietary red macroalgae (Halopithys incurva) improved systemic an mucosal immune and antioxidant parameters and modulated related gene expression in zebrafish (Danio rerio).

In the present study, the effects of dietary Halopithys incurva, a red macroalgae species, (0.25, 0.50, 1%) on whole-body serum and skin mucus immune system, antioxidant system and expression of various genes in zebrafish were investigated. At the end of the 8-week study, total protein, total immunoglobulin and lysozyme activities in whole-body serum and skin mucus increased in fish fed H. incurva (P < 0.05). While an increase was observed in superoxide dismutase (SOD), Catalase (CAT) and glutathione peroxidase (GPx) which are antioxidant enzyme activities in whole-body serum and skin mucus, a decrease in malondialdehyde (MDA) levels was detected (P < 0.05). All of the immune-related genes examined, such as Interleukin-1 beta (IL-1ß), Tumor necrosis factor-alpha (TNF-α), Interferon-gamma (INF- γ), were upregulated by the addition of 0.5% H. incurva (P < 0.05). While SOD and GPx, which are antioxidant enzyme-related genes, were remarkably upregulated in macroalgae fed fish (P < 0.05), no change was observed in CAT gene expression (P > 0.05). Based on the results of this study, it is considered that the addition of 0.5% H. incurva to the diets of commercially farmed fish will increase their immune and antioxidant defences and may contribute to the aquaculture sector for more sustainability.

Effects of dietary rambutan (Nephelium lappaceum L.) peel powder on growth performance, immune response and immune-related gene expressions of striped catfish (Pangasianodon hypophthalmus) raised in biofloc system.

This study aimed to evaluate the effects of rambutan peel powder (RP) on growth, skin mucosal and serum immunities, and immune-related gene expression of striped catfish (Pangasianodon hypophthalmus) reared in a biofloc system. Three hundred fingerlings (17.14 ± 0.12 g fish-1) were randomly selected and assigned to five treatments corresponding to five diets: 0 g kg-1 (control - RP0); 10 g kg-1 (RP10); 20 g kg-1 (RP20); 40 g kg-1 (RP40), and 80 g kg-1 (RP80) for 8 weeks. At weeks 4 and 8 post-feeding, growth, skin mucus, and serum immunity parameters were determined, whereas immune-related gene expressions were performed at the end of the feeding trial. Based on the results, skin mucus lysozyme (SML) and skin mucus peroxidase (SMP) were significantly higher in fish fed the RP diets compared to the control diet (P < 0.05). The highest SML and SMP levels were observed in fish fed RP40 diet, followed by RP20, RP80, RP10, and RP0. Fish-fed RP diets had higher serum lysozyme and serum peroxidase activities, with the highest value found in the RP40 diet (P < 0.05), followed by RP20, RP80, and RP10. Similarly, immune-related gene expressions (IFN2a, IFN2b, and MHCII) in the liver were significantly up-regulated in fish fed RP40. Up-regulation (P < 0.05) of IL-1, IFN2a, IFN2b, and MHCII genes was also observed in fish intestines, with the highest values observed in fish fed RP40 diet, followed by RP10, RP20, RP80, and RP0. Fish-fed diet RP diets also showed enhanced growth and FCR compared to the control, with the highest values observed in fish fed diet RP40. However, no significant differences in survival rates were found among diets. In conclusion, dietary inclusion of RP at 40 g kg-1 resulted in better growth performance, immune response, and immune related gene expressions of striped catfish (Pangasianodon hypophthalmus).

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.

The synergistic effects of plant polysaccharide and Pediococcus acidilactici as a synbiotic additive on growth, antioxidant status, immune response, and resistance of Nile tilapia (Oreochromis niloticus) against Aeromonas hydrophila.

This study evaluated the growth performance, immune responses, and disease resistance of Nile tilapia upon pistachio hulls derived polysaccharide (PHDP) and Pediococcus acidilactici (PA) separately or as synbiotic. Fish received four types of diets: T1, control; T2, PHDP (0.1%); T3, PA (0.2%); T4, PHDP (0.1%) +PA (0.2%) for 56 days. The results showed that final weight and weight gain were markedly higher in fish fed T4 diet than that given T1 and T2 diets (P ≤ 0.05). In addition, a significantly greater specific growth rate was obtained by the T4 diet compared to the control. Fish survival was significantly improved in all supplemented diets compared to the control. On the other hand, the activities of lipase, protease, and amylase showed significant increases in the T4 group compared with other feeding groups. The total leucocytes and lymphocytes proportion significantly elevated in T3 and T4 than remaining groups (P ≤ 0.05). Further, fish fed T3 diet presented significantly higher serum total protein, total immunoglobulin, lysozyme activity (LYZ), alternative complement activity (ACH50), and alkaline phosphatase activity compared to fish fed T1 and T2 diets, while the mentioned indices were found significantly highest in T4 group than others. Fish received T3 and T4 diets had higher skin mucus LYZ and ACH50 than those fed T1 and T2 diets (P ≤ 0.05). The malondialdehyde levels were significantly declined in T3 and T4 when compared to the control. Fish fed T3 and T4 diets demonstrated significantly enhanced superoxide dismutase, catalase, and glutathione peroxidase activities compared to the control. The intestinal propionic acid significantly increased by T2 and T4 diets, while the highest levels of acetic acid detected in fish given T4 diet. The expression levels of tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and interleukin 10 (IL-10) were significantly affected by T3 and T4 supplements. The efficacy of T4 diet against Aeromonas hydrophila infection was documented by a significantly lower mortality rate. In conclusion, the combination of PHDP and PA presented promising results as a synbiotic feed additive for Nile tilapia.

Effects of dietary thyme essential oil and prebiotic administration on rainbow trout (Oncorhynchus mykiss) welfare and performance.

The aim of this study was to examine the combined effects of thyme essential oil (TEO) and prebiotic (Immunogen ®) on growth performance, hematological parameters, innate immunity, and oxidative status of rainbow trout, Oncorhynchus mykiss. For this purpose, the fish (11.92 ± 0.06 g) were fed (3% of biomass) experimental diets that contained 0 (Control; without Immunogen and/or TEO); 1% TEO + 0.1% Immunogen (T1); 1% TEO + 0.2% Immunogen (T2); 2% TEO + 0.1% Immunogen (T3) and 2% TEO + 0.2% Immunogen (T4) for 60 days. According to results, all experimental treatments exhibited similar final weight, weight gain, specific growth rate (SGR), and survival rate (SR), which were significantly higher than those of the control treatment. Although all treatments reduced the feed conversion ratio (FCR) compared to the control group, the lowest value was observed in T4. All experimental treatments showed a significant increase in amylase and protease activity compared to the control group. Moreover, the fish fed on T4 and T1 diets showed the highest and lowest lipase activity. Dietary TEO and Immunogen supplementations significantly increased WBC count and Hb level compared to the control group. Fish fed on control and T2 diets displayed lower hematocrit than fish fed on other experimental diets. The highest and lowest MCH index were recorded in T3 and control groups, respectively. The fish fed diets supplemented with T3 diet presented significantly higher MCV index compared to the control and T2 treatment. All experimental treatments exhibited similar AST, and ALP activities, which were significantly lower than those of the control group. Also, the lowest ALT activity was observed in T2 and T4 treatments compared to other groups. Dietary TEO and Immunogen supplementations significantly enhanced skin mucus total Ig, total protein level, and ACH50, protease, and lysozyme. All experimental treatments exhibited enhanced intestine total Ig, ACH50, and lysozyme level. Dietary thyme essential oil and Immunogen supplementations significantly enhanced liver antioxidant parameters including catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and superoxide dismutase (SOD) and decreased MDA production compared to fish fed on control diet. As a result, it can be suggested that the combination of thyme essential oil and Immunogen (specially 2% TEO + 0.2% Immunogen) is useful for enhancing the yield and well-being of farmed rainbow trout.

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 plant pigment on blood-digestive physiology, antioxidant-immune response, and inflammatory gene transcriptional regulation in spotted snakehead (Channa punctata) infected with Pseudomonas aeruginosa.

The current study addressed to investigate the effect of lycopene (LYC) on blood physiology, digestive-antioxidant enzyme activity, specific-nonspecific immune response, and inflammatory gene transcriptional regulation (cytokines, heat shock proteins, vitellogenins) in spotted snakehead (Channa punctata) against Pseudomonas aeruginosa. In unchallenged and challenged fish treated with 200 mg LYC enriched diet the growth performance and digestive-antioxidant enzymes increased after 30 days, whereas with inclusion of 100 or 400 mg LYC in the diets, the increase manifested on or after 45 days. No mortality in fish treated with any LYC diet against P. aeruginosa was revealed. In the unchallenged and challenged fish the phagocytic (PC) activity in head kidney (HK) and spleen were significantly enhanced when fed the control diet or other LYC diets, whereas the respiratory burst (RB) activity and nitric oxide (NO) production significantly increased when fed the 200 mg diet for 45 and 60 days. Similarly, the lysozyme (Lyz) activity in the HK and spleen, and total Ig content in serum were significantly higher in both groups fed the 200 mg LYC diet for 15, 45, and 60 days. Heat shock protein (Hsp 70) was significantly improved in the uninfected group fed the 200 mg LYC diet for 45 and 60 days, but Hsp27 did not significantly change among the experimental groups at any time points. TNF-α and IL-6 mRNA pro-inflammatory cytokine expression significantly increased in both groups fed the 200 mg LYC diet after 45 and 60 days, while the IL-12 mRNA expression was moderate in both groups fed the same diet for 60 days. The IL-10 did not significant mRNA expression between groups at any sampling. The iNOS and NF-κB mRNA expression was pointedly high in both groups fed the 200 mg LYC diet on day 45 and 60. Vitellogenin A (VgA) mRNA was significantly higher in the uninfected fish fed the 100 and 200 mg LYC diets for 45 and 60 days, but VgB did not reveal significant difference between the treatment groups at any time points. The present results suggest that supplementation of LYC at 200 mg significantly modulate the blood physiology, digestive-antioxidant enzymes, specific-nonspecific immune parameters, and cytokines, Hsp, and vitellogenins in spotted snakehead against P. aeruginosa.

Effect of a diet enriched with sodium propionate on growth performance, antioxidant property, innate-adaptive immune response, and growth-related genes expression in critically endangered beluga sturgeon (Huso huso).

Organic acids are active substances required for improving the productivity and wellbeing of aquatic animals. Herein, the study investigated the effects of sodium propionate on growth performance, antioxidative and immune responses, and growth-related genes expression in beluga sturgeon (Huso huso). For eight weeks, fish fed sodium propionate at 0, 1.2, 2.5, and 5 g kg-1. The final weight, weight gain, and SGR were substantially increased while FCR decreased by dietary sodium propionate at 2.5 and 5 g kg-1 (P < 0.05). The expression of Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) was markedly upregulated (P < 0.05) by dietary sodium propionate in the gills and livers of beluga. The highest mRNA level of GH and IGF-1 has been observed in fish fed a 2.5 g sodium propionate/kg diet. The red blood cells count, and hemoglobin level were meaningfully increased (P < 0.05) by 2.5 and 5 g sodium propionate/kg diet compared with 0 and 1.2 g kg-1 levels. Further, the hematocrit level was increased (P < 0.05) by a dietary 5 g sodium propionate/kg diet. The total protein level and lysozyme activity were meaningfully increased (P < 0.05) by 2.5 and 5 g sodium propionate/kg diet compared with 0 and 1.2 g kg-1 levels. The highest superoxide dismutase was observed in fish fed 2.5 g sodium propionate/kg diet. Catalase activity was significantly higher in fish fed 5 g kg-1 than 1.2 g kg-1. The glutathione peroxidase activity was markedly higher in fish fed 2.5, and 5 g kg-1 than fish fed control diet. The lowest malondialdehyde levels were observed in fish fed 1.2, and 2.5 g sodium propionate/kg diets. Moreover, the highest mucosal total protein, total immunoglobulin and lysozyme were recorded in fish fed 2.5, and 5 g sodium propionate/kg diets. The obtained results indicate that dietary sodium propionate is recommended at 2.5-5 g kg-1 to improve beluga sturgeon's growth performance, feed utilization, and wellbeing.

Dietary Salvia officinalis leaves enhances antioxidant-immune-capacity, resistance to Aeromonas sobria challenge, and growth of Cyprinus carpio.

The current perspective is a pioneer to assess the efficacy of Salvia officinalis leave powder (SOLP) on growth, intestinal enzymes, physiological and antioxidant status, immunological response, and gene expression of Common carp (Cyprinus carpio). We also looked into fish resistance after being challenged with Aeromonas sobria, a pathogenic zoonotic bacteria. Fish (N = 120) were fed four different experimental diets in triplicate for 8 weeks. The control diet (SOLP0 - without SOLP); meanwhile, the other three diets included SOLP of 2, 4, and 8 g kg-1 concentrations (SOLP2, SOLP4, and SOLP8), respectively. Findings demonstrated that fish fed SOLP4 and SOLP8 diets had better growth performance and improved digestion by noticeable enhancing lipase and amylase enzymes activity than other groups. Additionally, the antioxidant (superoxide dismutase and glutathione peroxidase) and immune activities (immunoglobulin M, nitric oxide, and antiprotease) clarified a significant increase (p < 0.05) in SOLP4 and SOLP8 groups. Enriched diets with SOLP4 and SOLP8 exhibited better expression of splenic genes (IL-1ß, IL-6, IL-10, TLR-2, and SOD), intestinal genes (Slc26a6) and (PepT1 or Slc15a1), and muscular genes (IGF-1 and SOD), while MSTN was down-regulated. After 8 weeks of the experimental trial, C. carpio challenged by A. sobria exhibited the highest cumulative mortality (66.67%), while SOLP8-dietary intervention showed the best results in enhancing the fish resistance against A. sobria by lessening mortalities to 13.33% followed by SOLP4 diet (20%). The outcomes indicate that the expression of splenic, muscular, and intestinal genes confirm the efficacy of SOLP on enhancing growth, digestion, and immune-antioxidant status, and recommend the potential use of SOLP especially at 4 g kg-1 level as a valuable natural economic diet additive in C. carpio culture for sustaining aquaculture.