Hilyses®, fermented Saccharomyces cerevisiae, enhances the growth performance and skin non-specific immune parameters in rainbow trout (Oncorhynchus mykiss)

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 dietary fermented Saccharomyces cerevisiae extract (Hilyses) supplementation on growth, hematology, immunity, antioxidants, and intestinal health in Nile tilapia

This study investigated the effects of dietary supplementation with the product Hilyses on growth performance, feed utilization, nutrient composition, hematological parameters, serum biochemistry, immune function, antioxidant status, and digestive enzyme activity in juvenile Nile tilapia (Oreochromis niloticus, initial body weight 4.24 ± 0.01 g). The fish were fed diets supplemented with Hilyses at concentrations of 0, 1, 2, or 3 g/kg for a period of 8 weeks. The results showed that supplementation with Hilyses at levels up to 2 g/kg diet significantly improved final body weight, weight gain, specific growth rate, feed efficiency ratio, protein efficiency ratio, apparent protein utilization, and energy utilization compared to the control diet without Hilyses. Carcass crude protein content and moisture were significantly higher in Hilyses-fed groups, while crude lipid content decreased at the 3 g/kg supplementation level. Hilyses supplementation enhanced various hematological parameters, including increased red blood cell count, total leukocyte count, hemoglobin concentration, hematocrit, and mean corpuscular volume. Serum biochemistry and immune function markers like total protein, albumin, complement component C3, IgM, and IgG were significantly elevated in the 2 and 3 g/kg Hilyses groups. Antioxidant enzyme activities (catalase, glutathione peroxidase, total superoxide dismutase) were enhanced, and lipid peroxidation was reduced, in the 2 g/kg Hilyses group. Digestive enzyme activities, particularly protease and lipase, were also improved with Hilyses supplementation. Histological examination showed reduced lipid deposition in the liver and increased branching of intestinal villi at the 2 g/kg Hilyses level. Overall, these results indicated that dietary Hilyses supplementation at 2 g/kg diet optimizes growth, feed utilization, nutrient composition, hematology, immunity, antioxidant status, and digestive function in juvenile Nile tilapia.

Influence of stocking density on the growth, immune and physiological responses, and cultivation environment of white-leg shrimp (Litopenaeus vannamei) in biofloc systems

Biofloc (BF) stands out as a promising system for sustainable shrimp farming. Optimizing various culture conditions, such as stocking density, carbohydrate source, and feeding management, is crucial for the widespread adoption of the BF system. This study compares the growth performance of white-leg shrimp (Litopenaeus vannamei) in culture ponds at low density (LD) with 50 organisms/m2 and high density (HD) with 200 organisms/m2. Post-larvae of white-leg shrimp were stocked for 16 weeks in both LD and HD groups. The LD group exhibited a superior survival rate, growth rate, and feed consumption compared to the HD group. The BF from the LD system recorded a significantly higher protein content (16.63 ± 0.21%) than the HD group (15.21 ± 0.34%). Heterotrophic bacterial counts in water did not significantly differ with stocking density. However, Vibrio count in water samples was higher in the HD group (3.59 ± 0.35 log CFU/mL) compared to the LD group (2.45 ± 0.43 log CFU/mL). The whole shrimp body analysis revealed significantly higher protein and lipid content in the LD group. In contrast, the total aerobic bacterial count in shrimp from the HD group was high, with the identification of Salmonella enterica ssp. arizonae. Additionally, Vibrio counts in shrimp samples were significantly higher in the HD group (4.63 ± 0.32 log CFU/g) compared to the LD group (3.57 ± 0.22 log CFU/g). The expression levels of immune-associated genes, including prophenoloxidase, transglutaminase, penaiedin 3, superoxide dismutase, lysozyme, serine proteinase, and the growth-related gene ras-related protein (rap-2a), were significantly enhanced in the LD group. Conversely, stress-related gene expression increased significantly in the HD group. Hepatopancreases amylase, lipase, and protease were higher in the LD group, while trypsin activity did not differ significantly. Antioxidant enzyme activity (catalase, glutathione, glutathione peroxidase, and superoxide dismutase) significantly increased in the LD group. The histological structure of hepatopancreas, musculature, and female gonads remained similar in both densities. However, negative effects were observed in the gills' histology of the HD group. These results suggest that increasing stocking density is associated with significantly negative biological, microbial, and physiological effects on white-leg shrimp under the BF system.

Dietary effects of Saccharomyces cerevisiae and Allium sativum on growth, antioxidant status, hepatic and intestinal histoarchitecture, expression of growth- and immune-related genes, and resistance of Oreochromis niloticus to Aeromonas sobria

This study investigated the benefits of yeast, Saccharomyces cerevisiae and/or garlic, Allium sativum supplementation in diets of Nile tilapia with regard to growth, antioxidant status, hepatic and intestinal histoarchitecture, expression of growth- and immune-related genes, and resistance to Aeromonas sobria infection. Fish (with an initial weight of 9.43 ± 0.08 g) were allocated to twelve hapas, organized into four triplicate treatment groups defined as control (no supplementation), yeast (4 g/kg diet), garlic (30 g/kg diet), and a mixture of both. This trial continued over a 60-day feeding period. Results revealed that combined treatment (yeast + garlic) demonstrated the most promising outcomes regarding growth, with significantly higher final body weights, weight gains, and specific growth rates compared to other groups. Moreover, this combination enhanced hepatic antioxidant status, as evidenced by elevated levels of reduced glutathione and activities of catalase and superoxide dismutase enzymes, reflecting improved defense against oxidative stress. Histological assessments of the livers and intestines demonstrated structural enhancements in yeast and garlic treatments, suggesting improvements in organ health. In comparison to the control, the gene expression analyses unveiled increased expression of growth-related (igf-1 and ghr1) and immune-related (il-10, lyz, and hep) genes in the test groups, indicating a possible reinforcement of the growth and immune responses. The combined treatment also showed the highest resistance to A. sobria infection, as evidenced by improved survival rates and lower mortality compared with the other groups. These findings highlight the benefits of a combination of both yeast and garlic as a dietary supplementation regimen. In conclusion, this study suggests that the combined treatment regimen could be considered an effective strategy to promote the health and productivity of Nile tilapia under production conditions.

Potential benefits of yeast Saccharomyces and their derivatives in dogs and cats: a review

Yeast Saccharomyces and its derivatives have been largely used in livestock and poultry nutrition for their potential positive impact on growth, performance, and general health. Originally included in animal diets as a source of protein, yeasts can also offer a wide range of by-products with interesting bioactive compounds that would confer uses beyond nutrition. Although its supplementation in livestock, poultry and even in humans is well documented, the available body of literature on the use of yeast and its derivatives in companion animals' food, mainly dogs and cats' diets, is still developing. Despite this, gut microbiota modulation, immune system enhancement or decreasing of potentially pathogenic microorganisms have been reported in pets when using these products, highlighting their possible role as probiotics, prebiotics, and postbiotics. This review attempts to provide the reader with a comprehensive on the effects of Saccharomyces and its derivatives in pets and the possible mechanisms that confer their functional properties.

Probiotics Mediate Intestinal Microbiome and Microbiota-Derived Metabolites Regulating the Growth and Immunity of Rainbow Trout (Oncorhynchus mykiss)

Emerging evidence confirms using probiotics in promoting growth and immunity of farmed fish. However, the molecular mechanisms underlying the host-microbiome interactions mediated by probiotics are not fully understood. In this study, we used rainbow trout (Oncorhynchus mykiss) as a model to investigate the internal mechanisms of host-microbiome interactions influenced by two probiotic bacteria, Bacillus velezensis and Lactobacillus sakei. We carried out experiments, including intestinal histology, serum physiology, and transcriptome and combined intestinal microbiome and metabolite profiling. Our results showed that both probiotics had a positive effect on growth, immunity, serum enzyme activity, the gut microbiome, and resistance to Aeromonas salmonicida in rainbow trout. Moreover, the intestinal microbial structure was reshaped with increased relative abundance of potential beneficial bacteria, such as Ruminococcus, Lachnospiraceae ucg-004, Leptotrichia, Bacillus coagulans, Porphyromonadaceae, Anaerococcus, and Photobacterium in the B. velezensis group and Paenibacillaceae and Eubacterium hallii in the L. sakei group. Metabolomic profiling and transcriptome analysis revealed upregulated metabolites as biomarkers, i.e., sucrose and l-malic acid in the B. velezensis group, and N-acetyl-l-phenylalanine, N-acetylneuraminic acid, and hydroxyproline in the L. sakei group. Additionally, a multiomics combined analysis illustrated significant positive correlations between the relative abundance of microflora, metabolites, and gene expression associated with immunity and growth. This study highlights the significant role of probiotics as effectors of intestinal microbial activity and shows that different probiotics can have a species-specific effect on the physiological regulation of the host. These findings contribute to a better understanding of the complex host-microbiome interactions in rainbow trout and may have implications for the use of probiotics in aquaculture. IMPORTANCE Probiotics are kinds of beneficial live microbes that impart beneficial effects on the host. Recent studies have proven that when given supplementation with probiotics, farmed fish showed improved disease prevention and growth promotion. However, the underlying metabolic functions regarding their involvement in regulating growth phenotypes, nutrient utilization, and immune response are not yet well understood in the aquaculture field. Given the active interactions between the gut microbiota and fish immune and growth performance, we conducted the supplementation experiments with the probiotics Bacillus velezensis and Lactobacillus sakei. The results showed that probiotics mediated intestinal microbiome- and microbiota-derived metabolites regulating the growth and immunity of fish, and different probiotics participated in the species-specific physiological regulation of the host. This study contributed to a better understanding of the functional interactions associated with host health and gut microbiota species.

Immunoprotective role of aloin and disease resistance in Labeo rohita, infected with bacterial fish pathogen, Aeromonas hydrophila

The effect of aloin on mucosal immune response and disease resistance was elucidated in Labeo rohita infected with the bacterial fish pathogen, Aeromonas hydrophila. Fishes were divided into four groups: (i) control, (ii) vehicle control, (iii) bacteria infected and (iv) bacteria infected and aloin treated. Fish were intraperitoneally injected with A. hydrophila suspension at the dose of 2 × 10⁶ CFU/fish at 0 day (d). Following bacterial injection at 0 d, fish were treated with aloin at a dose of 1 mg/kg body weight intraperitoneally at an interval of 24 h for 4 consecutive days. Mucus collected from fish of each group was analyzed at 2 d, 4 d, 6 d, 8 d and 10 d. In bacteria-infected fish, a significant decrease (P < 0.05) in the activity of certain enzymatic and non-enzymatic immune parameters was observed. The activity of these immune parameters showed a gradual recovery on administration of aloin in bacteria-infected fish. Cumulative mortality was also found to be low in the aloin-treated group as compared to that in the infected group. Thus, aloin could act as an immunostimulant and play a protective role against disease caused by bacteria.

Dietary Effects of Probiotic Lactobacillus casei on Some Immunity Indices of Common Carp (Cyprinus carpio) Exposed to Cadmium

The present study investigated the effect of feeding common carp with Lactobacillus probiotic supplement on growth, blood indices, and immunity of serum and mucus exposed to cadmium. A total of 250 common carp with an average weight of 15 ± 0.62 were divided into three groups: fish without probiotics, and fish with two levels of probiotic. At the end of a 42-day feeding period, 50% of the lethal concentrations of cadmium were exposed for 14 days and blood and immune indices of serum and mucus were measured. The results showed that growth indices, blood indices, and serum and mucus immunity were significantly different from the control group (P < 0.05). Finally, this study showed probiotics could improve the decreasing effect of cadmium in BWI and PBWI indices and the additive effect of cadmium in FCR and ALT. Probiotic was also able to completely improve the decreasing effect of cadmium on lymphocyte indices and the additive effect of cadmium on ALP and AST and monocyte.

Effects of Various Doses of Saccharomyces cerevisiae on the Growth, Survival Rate, and Blood Profile of Saline Red Tilapia (Oreochromisspp.) in the Semi-Intensive Culture Conditions

The availability of good feeding on fish performance is needed to improve the poor aquaculture condition. The study examines the effects of Saccharomyces cerevisiae supplementation on the growth, survival rate, and blood profile of saline red tilapia in the semi-intensive culture. Sixty saline red tilapia (4.58 ± 0.09 g) were divided into five groups and received standard feed with supplementation of S. cerevisiae at different doses: (A-E) 0, 5, 10, 15, and 20 g/kg feed. S. cerevisiae was sprayed onto the feed and given to fish three times/day for 49 days. The efficiency of feed utilization (EFU), feed conversion ratio (FCR), the protein efficiency ratio (PER), relative growth rate (RGR), survival rate (SR), and blood profiles were examined. The water quality parameters were also evaluated, including temperature, pH, dissolved oxygen, NH₃, and salinity. Data were analyzed using ANOVA followed by the Duncan test. The supplementation of 10 g/kg S. cerevisiae could significantly (p<0.05) increase EFU (85.13%), PER (3.76), RGR (4.53%), and survival rate (97.53%), and decrease FCR (1.42) of the saline red tilapia. All doses of S. cerevisiae significantly (p<0.05) increased the number of hematocytes (34.68, 35.96, 34.14, and 34.52%, respectively) and hemoglobin (12.98, 13.58, 12.73, and 12.67%, respectively) of fish. The highest number of erythrocytes and leucocytes was found in dose 10 g/kg feed. All water parameters were stable during the study. Therefore, S. cerevisiae can be used as a feed supplement for red tilapia fish to increase the growth, survival rate, and blood profile of the saline red tilapia.

Seasonal variations in the skin epidermal structure and mucosal immune parameters of rainbow trout skin (Oncorhynchus mykiss) at different stages of farming

The aim of this study was to investigate the seasonal changes in the epidermal structure and the innate immunity parameters of skin mucus in rainbow trout. The skin epidermis and mucus samples were collected over three consecutive seasons including winter, spring and late summer from three different weight groups i.e., 2-20 g (W1), 100-200 g (W2) and 400-600 g (W3) fish. The skin mucosal immunity analysis of rainbow trout showed that the haemagglutination activity increased significantly with increasing fish size from W1 to W3 in all three seasons, while no significant seasonal changes occurred in haemagglutination activity. Moreover, the bactericidal activity against fish pathogens increased significantly with increasing water bacterial load in late summer. The SDS-PAGE analysis of mucus showed a high amount of low molecular weight proteins (<35 kDa) in the late summer that was correlated with the increase in bactericidal activity. Histological analysis of the epidermis structure of rainbow trout skin showed that the density and size of goblet cells and consequently the mucus secretion significantly increased in W3 group in all seasons. In all three weight groups of fish, the density of goblet cells significantly increased from winter to spring and late summer along with increasing water temperature. Moreover, the goblet cell density showed a significant positive relationship with the soluble protein concentration and haemagglutination activity (p < 0.01). The results of this study demonstrated the more active immune role of the skin epidermal cells and mucus in rainbow trout during summer to protect fish against the pathogenic microorganisms. Given its potent bactericidal properties and the lack of haemolytic activity, the rainbow trout mucus might be used as a safe and inexpensive source for developing antimicrobial agents to prevent and treat some bacterial diseases in human and fish.

Dietary Beet Molasses Improved the Immune System of Common Carp (Cyprinus carpio) After Exposure to Titanium Oxide Nanoparticles, TiO2-NPs

This study was carried out to evaluate dietary effect of beet molasses on immunity indices of common carp treated with titanium oxide nanoparticles TiO2-NPs. 250 fish were distributed in four treatments containing 0, 0.5%, 1% and 2% molasses and fed for 42 days, then fish were exposed to TiO2-NPs during a 14-day. At the end of experiment, hematological, biochemichal and mucusal immunity indices were evaluated. The aboved indices showed a significant difference compare to the control group (p < 0.05). Blood monocyte and lymphocyte in the TiO2-NPs with molasses group was reduced, that means molasses in combination with TiO2-NPs could alleviate the effect of TiO2-NPs. In treatments of TiO2-NPs and molasses combination, molasses was able to reduce the additive effect of monocyte, mean corpuscular hemoglobin concentration, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. Molasses in combination with TiO2-NPs was able to improve the negative effect of TiO2-NPs, so 2% molasses in combination with TiO2-NPs, could neutralized undesirable effect of TiO2-NPs on common carp.

Toxicological effects of cadmium on the immune response and biomineralization of larval flounder Paralichthys olivaceus under seawater acidification

Seawater acidification can cause threats to both calcifying and uncalcifying marine organisms, affecting their acid-base regulatory functions, immune system and biomineralization. Marine pollutants, such as cadmium (Cd) that is globally distributed in coastal ecosystems, do not affect organisms alone but commonly as combined stressors. To investigate the toxicological effects of Cd on the immune and biomineralization of marine fishes under seawater acidification, flounder Paralichthys olivaceus was exposed to seawater acidification (control (pH 8.10), 7.70 and 7.30) and Cd exposure (control (0.36 μg L^-1), 0.01 and 0.15 mg L^-1 Cd) for 49 days from embryonic stage until they became settled. Immune and biomineralization-related biomarkers of flounder at the end of exposure were investigated. Results showed that single seawater acidification and Cd exposure or combined exposure significantly affected the immune system-related enzyme activities. Specifically, lysozyme (LZM) activity was significantly inhibited by single seawater acidification and Cd exposure, indicating innate immunosuppression under two stressors. Contents of IgM, HSP70 and MT were induced by seawater acidification or Cd exposure, indicating a detoxification mechanism that responded to the stressors. The expressions of immune-related genes were upregulated (hsp70 and mt) or downregulated (lzm) under Cd exposure. Of the biomineralization-related enzymes, activities of carbonic anhydrase (CA), Na⁺/K⁺-ATPase and Ca²⁺-ATPase increased under seawater acidification and Cd exposure, a potential mechanism in response to changes of acid-base balance induced by the stressors. Generally, immune and biomineralization of the flounder responded more sensitively to Cd exposure than seawater acidification. Seawater acidification aggravated the toxicological effects of Cd exposure on the two physiological functions, while high Cd exposure augmented their responses to seawater acidification.

Immune defence mechanisms presented in liver homogenates and bile of gilthead seabream (Sparus aurata)

Because the role of the liver of fishes in providing possible immunity remains largely unknown, the aim of this work was to identify and characterize different humoral defence mechanisms in the liver homogenates and bile of gilthead seabream (Sparus aurata) for the first time. Total protein levels and several immune parameters (complement activity, lysozyme and immunoglobulin M level) were studied. Furthermore, the activity of some lytic (proteases, antiproteases, esterase, alkaline phosphatase) and antioxidant (superoxide dismutase, catalase and peroxidase) enzymes was determined. Finally, bacteriostatic activity on three opportunist fish pathogens (Vibrio harveyi, Vibrio angillarum and Photobacterium damselae) was measured. Lysozyme and antiprotease activity were undetected in liver and bile, while natural haemolytic complement activity was only detected in bile, and immunoglobulin M was detected in both samples. The levels of proteases, esterase and antioxidant enzymes were greater in bile than in liver homogenates, while the level of alkaline phosphatase was very low in both samples. In addition, while no bacteriostatic activity was detected on liver homogenates, the bile revealed a very potent bacteriostatic activity against all the tested pathogenic bacteria. These results corroborate that fish liver - especially fish bile - contains many factors involved in innate immunity that could be useful for better understanding the role of the liver as an organ involved in fish immune functions as well as the possible contribution of bile to gut mucosal immunity.

Role of mucosal immune response and histopathological study in European eel (Anguilla anguilla L.) intraperitoneal challenged by Vibrio anguillarum or Tenacibaculum soleae

The external mucus layer that covers fish skin contains numerous immune substances scarcely studied that act as the first line of defence against a broad spectrum of pathogens. This study aimed to characterize and describe for the first time several humoral immune defence parameters in the skin mucus of the European eel (Anguilla anguilla) after intraperitoneal injection with Vibrio anguillarum or Tenacibaculum soleae. This study evaluated several immune-related enzymes and bactericidal activity against fish pathogenic bacteria in the skin mucus of European eels at 24, 48, and 72 h post-challenge. The results demonstrated that European eel skin mucus showed significant increments in peroxidase and lysozyme activity at 48 and 72 h after V. anguillarum challenge, compared to other experimental groups. In the case of antiprotease activity, an increase was observed at 24 h in the skin mucus of fish challenged with V. anguillarum compared to unchallenged fish, while this activity was undetected at 48 and 72 h. In contrast, protease activity had decreased at 48 and 72 h in the skin mucus of fish challenged with V. anguillarum compared to the unchallenged group. Regarding bactericidal activity, a high growth capacity of T. soleae was observed in the skin mucus of all experimental groups. Interestingly, the skin mucus from fish challenged with V. anguillarum exhibited increased bactericidal activity against this bacterium at 48 h, compared to unchallenged fish. Finally, severe histopathological alterations were observed in the gills and liver at the end of the trial (72 h), whereas the skin showed only an overspread presence of goblet cells in the challenged fish compared to unchallenged fish. The present results may give new insights into the mucosal immune system of this primitive species with potential applications in aquaculture.

Scope of Archaea in Fish Feed: a New Chapter in Aquafeed Probiotics?

The outbreak of diseases leading to substantial loss is a major bottleneck in aquaculture. Over the last decades, the concept of using feed probiotics was more in focus to address the growth and health of cultivable aquatic organisms. The objective of this review is to provide an overview of the distinct functionality of archaea from conventional probiotics in nutrient utilization, specific caloric contribution, evading immune response and processing thermal resistance. The prime limitation of conventional probiotics is the viability of desired microbes under harsh feed processing conditions. To overcome the constraints of commercial probiotics pertaining to incompatibility towards industrial processing procedure, a super microbe, archaea, appears to be a potential alternative approach in aquaculture. The peculiarity of the archaeal cell wall provides them with heat stability and rigidity under industrial processing conditions. Besides, archaea being one of the gut microbial communities participates in various health-oriented biological functions in animals. Thus, the current review devoted that administration of archaea in aquafeed could be a promising strategy in aquaculture. Archaea may be used as a potential probiotic with the possible modes of functions and advantages over conventional probiotics in aquafeed preparation. The present review also provides the challenges associated with the use of archaea for aquaculture and a brief outline of the patents on archaea to highlight the various use of archaea in different sectors.

Effects of Potential Probiotic Enterococcus casseliflavus (EC-001) on Growth Performance, Immunity, and Resistance to Aeromonas hydrophila Infection in Common Carp (Cyprinus carpio)

The effects of different levels of dietary Enterococcus casseliflavus (EC-001), as a potential probiotic, were investigated on the growth performance, hemato-biochemical parameters, immune responses, and resistance to Aeromonas hydrophila infection in common carp (Cyprinus carpio) fingerlings. Accordingly, fish (N = 720; 12.0 ± 0.5 g) were distributed into four treatments receiving different dietary levels of E. casseliflavus, EC-001 (0 [control], 1 × 10⁷, 10⁸, and 10⁹ CFU g^-1 feed), for 8 weeks. The fish fed with a diet containing 10⁹ CFU g^-1 showed the highest weight gain and specific growth rate, along with the lowest feed conversion ratio, compared with the control group (P < 0.05). Red and white blood cells, hemoglobin, hematocrit, neutrophils, and monocytes significantly increased in the fish fed with 1 × 10⁸ and 10⁹ CFU g^-1 (P < 0.05). Dietary inclusion of 1 × 10⁸ and 10⁹ CFU g^-1 significantly increased serum total protein, albumin, and immunoglobulin content (P < 0.05). Feeding the fish with 1 × 10⁹ CFU g^-1 resulted in a significant increase in serum and skin mucus lysozyme activity compared with the other groups (P < 0.05). Complement component 3 and skin mucus protease activity were also significantly higher in all the fish treated with dietary E. casseliflavus (EC-001) compared with the control group (P < 0.05). The cumulative mortality in the treated fish was lower (ranging from 10 to 22%) than the control group (31%) after challenging the fish with A. hydrophila infection, while the fish fed with E. casseliflavus (EC-001) at 1 × 10⁹ CFU g^-1 exhibited the lowest mortality rate (P < 0.05). In conclusion, our results revealed the potential probiotic effects of E. casseliflavus (EC-001) for enhancing growth performance, immunity, and disease resistance of common carp.

Cutaneous mucosal immune-parameters and intestinal immune-relevant genes expression in streptococcal-infected rainbow trout (Oncorhynchus mykiss): A comparative study with the administration of florfenicol and olive leaf extract

This study evaluated changes in cutaneous mucosal immunity (total protein (TP) and immunoglobulin (TIg), lysozyme, protease, esterase, and alkaline phosphatase (ALP)) and some immune-related genes expression (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-8, hepcidin-like antimicrobial peptides (HAMP), and immunoglobulin M (IgM)) in the intestine of rainbow trout (Oncorhynchus mykiss) orally-administrated florfenicol (FFC) and/or olive leaf extract (OLE), experimentally infected with Streptococcus iniae. The juvenile fish (55 ± 7.6 g) were divided into different groups according to the use of added OLE (80 g kg^-1 food), the presence/absence of FFC (15 mg kg^-1 body weight for 10 consecutive days), and the streptococcal infectivity (2.87 × 10⁷ CFU mL^-1 as 30% of LD₅₀-96h). The extract's chemical composition was analyzed using the high-performance liquid chromatography (HPLC) system. The skin mucus and intestine of fish were sampled after a 10-day therapeutic period for all groups, and their noted indices were measured. Our results signified that the oleuropein, quercetin, and trans-ferulic acid were the most obvious active components of OLE which were found by HPLC analysis. The combined use of OLE and FFC could lowered some skin mucus immunological indices (e.g., TP, TIg, and ALP), and the gene expression of inflammatory cytokines (e.g., TNF-α and IL-1β) of rainbow trout. Moreover, lysozyme and protease activities respectively were invigorated by the FFC and OLE treatment. Also, the use of OLE as a potential medicine induced the gene expression of HAMP. As the prevention approach, it would be recommended to find the best dose of OLE alone or in combination with the drug through therapeutics period before the farm involved in the streptococcal infection.

Effect of dietary supplementation with yeast Saccharomyces cerevisiae on skin, serum and liver of gilthead seabream (Sparus aurata L)

The effect of dietary supplementation with Saccharomyces cerevisiae on gilthead seabream (Sparus aurata L.) was studied. Four replicates of fish (n = 6) were fed with a commercial diet containing 0 (control, no yeast added) or 10 mg per kilogram of heat-killed (30 min, 60°C) S. cerevisiae. After 4 weeks, half of the fish (two replicates) were injured and continued with the same diet. At 3 and 7 days post-wounding, samples of blood, skin mucus, skin and liver were obtained from each fish. The results showed that calcium concentrations were significantly higher (with respect to control fish) in the serum from fish sampled at 3 days post-wounding, whereas antioxidant enzymes in the skin mucus were altered after wounding (at both 3 and 7 days). Histological analyses revealed oedema, signs of inflammation and white cell recruitment together with a reduction in the epidermis layer in the wounded regions of fish fed control diet. Yeast supplementation did not change growth performance and helped maintain the normal serum calcium concentrations in wounded fish. Furthermore, a reduction in inflammation around wounds in the animals fed yeast with respect to that fed control diet was evident in the histological study. Furthermore, increased levels of stress-related gene expression in liver and skin from wounded fish were obtained. Overall, yeast supplementation seemed to be a functional and appropriate dietary additive to improve skin recovery reducing the stress resulting from wounds.

Effects of dietary myo-inositol on growth, antioxidative capacity, and nonspecific immunity in skin mucus of taimen Hucho taimen fry

In this study, the effects of dietary myo-inositol on the skin mucosal immunity and growth of taimen (Hucho taimen) fry were determined. Triplicate groups of 500 fish (initial weight 5.58 ± 0.15 g) were fed different diets containing graded levels of myo-inositol (28.75, 127.83, 343.83, 565.81, and 738.15 mg kg^-1) until satiation for 56 days. Thereafter, the nonspecific skin mucus immune parameters, antioxidative capacity, and growth performance were measured. The skin mucus protein and the activities of alkaline phosphatase were significantly higher than those in the control group (P < 0.05). However, there were no significant differences in lysozyme activity among the treatments (P > 0.05). The antimicrobial activity and minimum inhibitory concentration of the skin mucus were increased significantly by myo-inositol supplementation (P < 0.05). The superoxide dismutase, catalase, and glutathione peroxidase activities were significantly elevated in the treatment groups (P < 0.05), whereas the malondialdehyde contents were significantly decreased (P < 0.05). Low-level myo-inositol (28.75 mg kg^-1) led to a significantly lower weight gain, feed efficiency, condition factor, and survival rate compared with the other treatments (P < 0.05). In conclusion, dietary myo-inositol deficiency (28.75 mg kg^-1) adversely affects the skin mucus immune parameters, antioxidative capacity, and growth performance of Hucho taimen fry.

Effects of dietary Lactobacillus plantarum (KC426951) in biofloc and stagnant-renewal culture systems on growth performance, mucosal parameters, and serum innate responses of Nile tilapia Oreochromis niloticus

Effects of dietary Lactobacillus plantarum (KC426951) on growth and innate responses of Nile tilapia Oreochromis niloticus were evaluated in biofloc technology system and stagnant-renewal culture system (SRCS). The 90-day-long experiment contained four treatments: SRCS without probiotic (T1), SRCS with probiotic (T2), biofloc without probiotic (T3), and biofloc with probiotic (T4). The administration dose of probiotic was 2 × 10⁸ CFU kg^-1 diet. At the end of experiment, the mean final weights, specific growth rates, feed conversion ratios, and total biomass were significantly (P < 0.05) better in BFT treatments, with no significant effect of probiotic on these parameters in both culture systems. Meanwhile, skin mucosal parameters including total protein (TP), lysozyme (LYZ), alkaline phosphatase (ALP), and protease (PRO) activity were significantly enhanced following probiotic supplementation. T4 treatment displayed a significantly higher LYZ and ALP activity in mucus versus other treatments. Also, serum alternative complement activity was significantly heightened in probiotic-supplemented fish. Superoxide dismutase activity in T4 was detected higher than that of SRCS groups. The results of the current study demonstrated the enhancement of some mucosal and serum innate responses of Nile tilapia in both culture systems upon L. plantarum (KC426951) supplementation.

Influence of dietary fermented Saccharomyces cerevisiae on growth performance, oxidative stress parameters, and immune response of cultured Oreochromis niloticus

Our trial was performed to investigate the effect of fully fermented yeast Sacharomyces cerevisiae (Hilyses, ICC Company, Brazil) on the growth performance and immune response of Oreochromis niloticus. In this study, a total of 270 O. niloticus (50.7 ± 0.8 g) were randomly divided into 3 groups in triplicates. The control group was fed on the basal diet while the other two groups were fed on a basal diet supplemented with 0.2% and 0.4% of Hilyses. The trial period extended for 2 months. At the end of the feeding trial, oxidant and antioxidant parameters (MDA, catalase, and glutathione reductase), some innate immunological parameters and immune-related gene expression were measured. Histological examination of liver, spleen, kidney, and intestine was performed. Further, fish groups were challenged against Gram-negative and Gram-positive bacteria; A. hydrophila and L. garvieae. The results revealed significant improvement (p < 0.05) in growth performance and feed utilization in Hilyses-treated groups versus the control group. Blood parameters and liver and kidney functions of Hilyses-supplemented groups were similar to those of the control group. The histological findings of treated groups showed normal tissue structure with multiple focal lymphoid aggregations in the spleen, kidney, and intestine. Both levels of Hilyses successfully enhanced phagocytic activity/index, lysozyme activity, and gene expression of TNF-α, and IL-1β. Fish group fed on 0.4% Hilyses exhibited the highest expression of IL-1β and the least mortality percentages post challenges. Thus, dietary supplementation of Hilyses could promote the growth performance and immunity and increase the resistance of O. niloticus against diseases.

Comparative study of host-associated and commercial probiotic effects on serum and mucosal immune parameters, intestinal microbiota, digestive enzymes activity and growth performance of roach (Rutilus rutilus caspicus) fingerlings

The study aimed to isolate host-associated probiotic (HAP) lactic acid bacteria from intestine of adult Caspian roach and compare the efficacy of HAP with a commercially available probiotic strain (Pediococcus acidilactici) on the growth and feed utilisation, digestive enzymes and systemic and mucosal immune system of roach fingerling. The HAP strain isolated from roach intestine was Enterococcus faecium strain CGMCC1.2136. The experiment was a simple completely randomized design and lasted for eight weeks. Two hundred and seventy fish with an average weight of 12 g randomly distributed into nine tanks. The trial consisted of three treatments with three respective replications. During the experimental period, fish received basal diet without any bacterial supplementation (as the control group), basal diet enriched with 10⁸ CFU g^-1 HAP or 10⁷ CFU g^-1 CP. At the end of the experiment, serum immune parameters of those fish fed HAP including alkaline phosphatase activity, total protein content, total immunoglobulin level, lysozyme activity and complement activity (ACH50) were significantly higher that other experimental groups (P < 0.05). Similarly, dietary supplementation of HAP resulted in better mucosal immune parameters in comparison to control group and commercial probiotic administration (P < 0.05). Intestinal heterotrophic bacteria and autochthonous LAB counts of those fish fed HAP were significantly higher than other experimental groups at the end of the experiment as well as 15 days seizing probiotic administrations (P < 0.05). Fish fed with HAP containing diet presented significantly higher amylase, lipase and protease activity in comparison to the CP fed fish and the control group (P < 0.05). Growth indices of those fish fed HAP were significantly higher than other treatments (P < 0.05). The highest carcass protein and ash content along with the lowest body moisture content belonged to those fish received HAP (P < 0.05). In conclusion, the use host-HAP resulted in better immune competence and growth performance and it seems aquaculture sector should probably focus on the development of probiotics isolated from the cultured species instead of using terrestrial probiotics with greatly different requirements and environmental conditions.

Coping with exposure to hypoxia: modifications in stress parameters in gilthead seabream (Sparus aurata) fed spirulina (Arthrospira platensis) and brewer's yeast (Saccharomyces cerevisiae)

This study aimed to investigate the stress response of Sparus aurata specimens fed with nutraceutical aquafeed brewer's yeast (Saccharomyces cerevisiae) and spirulina (Arthrospira platensis). For that purpose, 96 (169.0 ± 2.8 g) animals were distributed randomly in 12 tanks (8 fish per tank, 4 replicates) and divided in 3 groups (D1, casein/gelatin, control; D2, brewer's yeast; D3, spirulina) and fed for 30 days. At the end of this period, fish from two replicates of each experimental diet were submitted to air exposure for 60 s while the fish from the other two replicates were maintained undisturbed (control). Afterwards, samples of blood, skin mucus, and head kidney were collected. The results revealed that after air exposure, cortisol, and glucose levels increased in the groups fed D1 (18.5 ± 2.6 mg/mL; 7.3 ± 0.6 mmol/L, respectively) and D2 (20.0 ± 6.2 mg/mL; 7.7 ± 0.6 mmol/L), but glucose not increased in fish fed D3 (13.7 ± 2.6 mg/mL; 5.5 ± 0.3 mmol/L). Lactate levels increased in all stressed groups, but in D1, its levels were significantly higher. After stress procedure, immunoglobulin M (IgM) levels in mucus increased only in fish fed D3 (0.1901 ± 0.0126 U/mL). Furthermore, there was a reduction in the expression of some genes involved in stress response (coxIV, prdx3, csfl-r, ucp1, and sod in fish fed D2 and D3). csf1 decreased only in stressed fish fed D2. However, cat increased in fish fed with D3. In summary, these findings points to the beneficial effects of spirulina and brewer's yeast to improve stress resistance in aquaculture practices of gilthead seabream.

Effects of bioactive substance from turmeric on growth, skin mucosal immunity and antioxidant factors in common carp, Cyprinus carpio

Present study evaluated the effects of curcumin, the principal curcuminoid of turmeric, on Cyprinus carpio growth, skin mucosal immune parameters, immune-related gene expression, and susceptibility to pathogen challenge. Diets containing four various concentrations of curcumin (g Kg^-1): 0 g [basal diet], 5 g [T5], 10 g [T10], and 15 g [T15] were fed to the carp (average weight: 16.37 g) for 8 weeks. Growth parameters were analysed at 4 and 8 weeks post-feeding. Skin mucosal immune responses and expression were examined in 8 weeks post-feeding. Growth performance was significantly higher in T10 and T15, with final weight gain of 102.26 ± 2.31 g and specific growth rate of 3.24 ± 0.37, respectively. The lowest feed conversion ratio (2.35 ± 0.16) was recorded in T15 than in the control (P < 0.05). Among the skin mucosal immune parameters examined, lysozyme (36.8 ± 4.03 U mL^-1), total immunoglobulin (6.74 ± 0.5 mg mL^-1), protein level (18.7 ± 1.62 mg mL^-1), alkaline phosphatase (96.37 ± 6.3 IU L^-1), and protease activity (9.47 ± 0.82%) were significantly higher in T15, while the peroxidase activity was higher in T10 (10.24 ± 0.9 U mg^-1 protein). Further, lysozyme, superoxide dismutase (SOD) and catalase (CAT) activities were measured in serum and found to be higher in T10 or T15 than in the control (P < 0.05). However, malondialdehyde level decreased significantly in T10 and T15. Furthermore, antioxidant genes (SOD, CAT, nuclear factor erythroid 2-related factor 2) and anti-inflammatory cytokine Interleukin-10 were upregulated in the head kidney, intestine, and hepatopancreas of fish in T10 and T15. Conversely, expression of pro-inflammatory cytokines (IL-1β, tumour necrosis factor-alpha), signalling molecule NF-κBp65 were down-regulated in the tested tissues of T10 and T15. Expression of Toll-like receptor 22 (TLR22) was down regulated in head-kidney and intestine of T15. Fish from T15 exhibited significantly higher relative post-challenge survival (69.70%) against Aeromonas hydrophila challenge. Results of the present study suggest that dietary supplements of curcumin at 15 g Kg^-1can significantly improve the growth performance, skin mucosal and serum antioxidant parameters, and strengthen the immunity of C. carpio. Therefore, curcumin represents a promising food additive for carps in aquaculture.

Growth performance, immune response, and digestive enzyme activity in Pacific white shrimp, Penaeus vannamei Boone, 1931, fed dietary microbial lysozyme

The present study investigates the effects of the dietary microbial lysozyme (ML) as an immunostimulant, on the growth performance, some immune parameters and digestive enzyme of Pacific white shrimp, Penaeus vannamei. Six hundred shrimps were obtained and randomly allocated into four groups as follows with three replicates. The shrimps were fed diets supplemented with 0 (control), 0.5, 1, and 2 g kg^-1 ML for 4 months. The results indicated that dietary supplementation of ML significantly improved final weight, weight gain, average daily weight gain rate (ADG), feed conversion rate (FCR), and feed efficiency rate (FER) compared to the control (P ˂ 0.05). However, weight gain specific growth rate (SGR) and survival rate were not significantly affected by dietary ML (P ˃ 0.05). Dietary ML had a progressive effects on some immune parameters status including total antioxidant capacity (TAOC), superoxide dismutase (SOD), glutathione peroxidase (GPX), lysozyme (LYZ), alkaline phosphatase (ALP), phenoloxidase (PO) and acid phosphatase (ACP) activity as well as differential haemocyte count (DHC) and total haemocyte count (THC), in shrimps treated with the lysozyme than untreated shrimps (P ˂ 0.05). However, feeding with ML had no significant effect on plasma malondialdehyde (MDA) level (P ˃ 0.05). Furthermore, intestinal digestive enzymes (lipase, protease, and amylase) in shrimp fed with dietary ML were significantly (P ˂ 0.05) higher than those fed with non-supplemented control basal diet. Thus, the results indicate that oral administration of ML can be recommended for shrimp feed to improve immune response as well digestive enzymes activity modulation.

Biology, environmental and nutritional modulation of skin mucus alkaline phosphatase in fish: A review

Alkaline phosphatase (AP) is a major, recently recognized component of innate immunity. The intestinal AP (IAP) isoform plays a pivotal role in controlling gastrointestinal and systemic inflammation in terrestrial mammals. This is so essentially through detoxification (by dephosphorylation) of proinflammatory microbial components that can no longer be recognized by so-called toll-like receptors, thus preventing cellular inflammatory cascade activation. A unique feature of fish is the presence of AP in skin and epidermal mucus (skin mucus AP) but its actual functions and underlying mechanisms of action are presently unknown. Here, we gather and analyse knowledge available on skin mucus AP in order to provide a holistic view of this important protective enzyme. Our main conclusions are that skin mucus AP is responsive to biotic and abiotic factors, including nutrients and bioactive feed components, prebiotics and probiotics. Importantly, both skin mucus AP and IAP appear to correlate, thus raising the interesting possibility that skin mucus AP be used as a proxy for IAP in future nutritional studies. Blood serum AP also seems to correlate with skin mucus AP, though biological interpretation for such relationship is presently unknown. Finally, the precise isoform/s of AP present in skin should be identified and underlying molecular mechanisms of skin mucus AP actions deciphered.

Increased parasite resistance of greater amberjack (Seriola dumerili Risso 1810) juveniles fed a cMOS supplemented diet is associated with upregulation of a discrete set of immune genes in mucosal tissues

The main objective of this study was to determine the effect of two forms of mannan oligosaccharides (MOS: Bio-Mos^® and cMOS: Actigen^®, Alltech Inc, USA) and their combination on greater amberjack (Seriola dumerili) growth performance and feed efficiency, immune parameters and resistance against ectoparasite (Neobenedenia girellae) infection. Fish were fed for 90 days with 5 g kg^-1 MOS, 2 g kg^-1 cMOS or a combination of both prebiotics, in a Seriola commercial base diet (Skretting, Norway). At the end of the feeding period, no differences were found in growth performance or feed efficiency. Inclusion of MOS also had no effect on lysozyme activity in skin mucus and serum, but the supplementation of diets with cMOS induced a significant increase of serum bactericidal activity. Dietary cMOS also reduced significantly greater amberjack skin parasite levels, parasite total length and the number of parasites detected per unit of fish surface following a cohabitation challenge with N. girellae, whereas no effect of MOS was detected on these parameters. Of 17 immune genes studied cMOS dietary inclusion up-regulated hepcidin, defensin, Mx protein, interferon-γ (IFNγ), mucin-2 (MUC-2), interleukin-1β (IL-1B), IL-10 and immunoglobulin-T (IgT) gene expression in gills and/or skin. MOS supplementation had a larger impact on spleen and head kidney gene expression, where piscidin, defensin, iNOS, Mx protein, interferons, IL-1β, IL-10, IL-17 and IL-22 were all upregulated. In posterior gut dietary MOS and cMOS both induced IL-10, IgM and IgT, but with MOS also increasing piscidin, MUC-2, and IL-1β whilst cMOS induced hepcidin, defensin and IFNγ. In general, the combination of MOS and cMOS resulted in fewer or lower increases in all tissues, possibly due to an overstimulation effect. The utilization of cMOS at the dose used here has clear benefits on parasite resistance in greater amberjack, linked to upregulation of a discrete set of immune genes in mucosal tissues.

Dietary administration of eryngii mushroom (Pleurotus eryngii) powder on haemato-immunological responses, bactericidal activity of skin mucus and growth performance of koi carp fingerlings (Cyprinus carpio koi)

The aim of present study was to evaluate the effects of edible eryngii mushroom powder, Pleurotus eryngii (PE), for 63 days on haematological parameters, the serum immune responses, skin mucus, bactericidal activity, stress resistance, growth performance and digestive enzyme activities of Koi carp fingerlings (Cyprinus carpio koi). Fish were divided into five groups and each group was fed with dietary PE with five graded levels (0, 0.5, 1, 1.5 and 2%). The results showed a significant dose-dependent increase of Ht, Hb, MCV and MCH levels in fish fed dietary PE (P < 0.05). The highest levels of WBCs, lymphocytes and monocytes were measured in fish fed 1.5% and 2% of dietary PE (P < 0.05). The activities of total IG, lysozyme, Alternative haemolytic complement activity in serum of fish fed with 2% of dietary PE for 63 days as well as 5-min air exposure challenge test were significantly higher than other groups (P < 0.05). The most bactericidal activity was observed in skin mucus of fish fed with 1.5% of dietary PE against Streptococcus iniae (P < 0.05). The highest ratio of the lactobacillus count to the total viable count was observed in fish fed 2% of dietary PE. The α-amylase activity of fish fed with dietary PE (1, 1.5 and 2%) were significantly higher than control group (P < 0.05). Feeding fish 2% of dietary PE increased the trypsin and lipase activity compared to others groups (P < 0.05). The growth performance of fish fed 1.5% of dietary PE improved compared to control group (P < 0.05). The results revealed that feeding koi fish with dietary supplementation of PE (1.5 and 2%) improved the selected humoral innate immune responses, bactericidal activity of skin mucus and growth performance of koi fish.

Modulation of rainbow trout (Oncorhynchus mykiss) cutaneous mucosal immune responses following anesthesia: A comparative study on different anesthetic agents

The present study investigated the possible effects of different anesthetic agents including MS222 (50 ppm), 2-Phenoxyethanol (2-PE) (0.2 mL L^-1) and clove oil (25 ppm), on cutaneous mucosal immune parameters in rainbow trout (Oncorhynchus mykiss). The induction and recovery times for each anesthetic agent were assessed. Also, the immune parameters were measured in skin mucus, 1 and 24 h post anesthesia. No significant difference was observed among treatments at 1 h post-anesthesia except for bactericidal and alkaline phosphatase (ALP) activities which was significantly enhanced in fish exposed to 2-PE compared to other anesthetics. At 24 h post-anesthesia, most of the skin mucosal immune parameters were increased upon exposure to clove oil but decreased following exposure to 2-PE. However, no significant change was noticed after MS222 exposure. These results demonstrated that the anesthetics type should be considered to avoid possible immunosuppression in farmed fish. Furthermore, the present results could be useful for better understanding of alterations in cutaneous mucosal immunity in response to chemical stressors such as anesthetic agents.

The effects singular or combined administration of fermentable fiber and probiotic on mucosal immune parameters, digestive enzyme activity, gut microbiota and growth performance of Caspian white fish (Rutilus frisii kutum) fingerlings

The aim of the present study was to investigate the effects of single or combined administration of dietary fermentable fiber (Vitacel^®) and probiotic PrimaLac^® on mucosal immune parameters, digestive enzyme activity, gut microbiota and growth performance of Caspian white fish (Rutilus frisii kutum) fingerlings. Fish were transferred to laboratory, acclimatized for two weeks and then fish (0.56 ± 0.026 g) were allocated into 12 tanks (30 fish per tank). Triplicate groups were fed a basal diet (Control) or basal diet supplemented with fermentable fiber [Vitacel^®] (FF), probiotic [PrimaLac^®] (P) and combined fermentable fiber and probiotic (FF + P). At the end of feeding trial, growth performance and feed utilization parameters were significantly (P < 0.05) improved in FF, P and FF + P treatments compared control group. Evaluation of digestive enzyme activity revealed significant (P < 0.05) increase of lipase activity in fish fed supplemented diet. However, amylase, protease and alkaline phosphatase were significantly higher (P < 0.05) only in P and FF + P treatments. Furthermore, total autochthonous intestinal microbiota and autochthonous LAB levels significantly increased in fish fed supplemented diet (P < 0.05). Also, inclusion of FF, P and FF + P in Caspian white fish diet remarkably increased skin mucus immune parameters compared control group (P < 0.05). These results indicate that singular or combined administration of FF and P can be considered as a beneficial dietary supplement for early stages of Caspian white fish (Rutilus fresii kutumn) culture.

Dietary supplementation of probiotic Bacillus licheniformis Dahb1 improves growth performance, mucus and serum immune parameters, antioxidant enzyme activity as well as resistance against Aeromonas hydrophila in tilapia Oreochromis mossambicus

The present study evaluated the dietary supplementation of probiotic Bacillus licheniformis Dahb1 on the growth performance, immune parameters and antioxidant enzymes activities in serum and mucus as well as resistance against Aeromonas hydrophila in Mozambique tilapia Oreochromis mossambicus. Fish (24 ± 2.5 g) were fed separately with three diets, 1) commercial diet (control), 2) diet containing probiotic at 10⁵ cfu g^-1 (D1) and 3) diet containing probiotic at 10⁷ cfu g^-1 (D2) for 4 weeks. Growth performance in term of final weight (FW) specific growth rate (SGR) and feed conversion ratio (FCR), immune parameters of total protein (TP), alkaline phosphatase (ALP), myeloperoxidase (MPO), lysozyme (LYZ), reactive oxygen species (ROS), reactive nitrogen species (RNS) and antioxidant parameters of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in serum and mucus were evaluated after 2^nd and 4^th weeks. The FW, SGR, and FCR of fish fed with D1 and D2 significantly improved (p < 0.05). The activities of ALP, LYZ and MPO in the mucus were significantly higher (p < 0.05) in fish that fed D1 and D2. The TP, ROS, RNS, SOD and GPx in the serum were significantly higher (p < 0.05) in fish that fed D1 and D2. In addition, the challenge test showed that fish fed D1 and D2 enhanced significantly (p < 0.05) the resistance against A. hydrophila (1 × 10⁷ cells ml^-1). In conclusion, probiotic B. licheniformis Dahb1 can be applied in diet at 10⁷ cfu g^-1 to improve healthy status and resistance against A. hydrophila in tilapia farming.

Role of aloin in the modulation of certain immune parameters in skin mucus of an Indian major carp, Labeo rohita

Enhancement of immune system seems to be the most promising method of preventing fish diseases. Several herbal products have immunostimulant properties, and are environmental friendly, economical and can act against a broad spectrum of pathogens. Present study was designed with an aim to evaluate the role of aloin, extracted from a herb Aloe barbadensis, in the modulation of certain immune parameters in an Indian major carp, Labeo rohita. Fishes were divided into control, vehicle control and aloin treated groups. Experiments were conducted for 7 days and fishes from the three groups were analyzed at 2d, 4d, 6d and 8d. The results demonstrated that at different intervals, L. rohita administered with aloin showed a significant increase in the activity of enzymes - lysozyme, protease, carboxylesterase, alkaline phosphatase, acid phosphatase, catalase and peroxidase, and non-enzymatic factors hemagglutinin and alternate complement compared with that of the controls. Thus, it can be concluded that administration of aloin is beneficial in enhancing the immune response and hence it can be used as potent immunostimulant in aquaculture.

Functional diets modulate the acute phase protein response in Oncorhynchus mykiss subjected to chronic stress and challenged with Vibrio anguillarum

The acute phase response to pathogens alters the production of proinflammatory cytokines that, in turn, activate the synthesis of acute phase proteins. These proteins neutralize, prevent, and indicate tissue damage, thereby influencing the specific immune response and allowing the organism to regain homeostasis. Functional diets based in pre- and probiotics are used in aquaculture to improve fish health and resistance to diseases, but there is an information gap on the mechanisms involved in these effects and if these diets are efficient when fish are raised under high stocking densities. This study aimed an evaluation of the acute phase response in Oncorhynchus mykiss fed functional diets supplemented with pre- and probiotics (i.e. mannan-oligosaccharides and Saccharomyces cerevisiae, respectively) and challenged by either Vibrio anguillarum or chronic stress via maintenance under high stocking densities. For this, the relative expression of acute phase response related genes in liver, and of inflammatory response related genes in head kidney was evaluated by RT-qPCR. The supplemented diets differentially modulated the acute phase protein response to the assessed challenge conditions, specifically evidencing an overexpression of the genes HAPT, SAA, LECT2, and IL-1β under chronic stress and of HAPT, IL-1β, IL8, and LECT2 at 24 h post-challenge with V. anguillarum. The observed early-stage regulation of acute phase proteins and of the immune response by the probiotic S. cerevisiae and by prebiotic mannan-oligosaccharides suggests that both supplements have high immunostimulatory potentials for fish farmed under high stocking densities.

Effects of dietary supplementation with fenugreek seeds, alone or in combination with probiotics, on gilthead seabream (Sparus aurata L.) skin mucosal immunity

Despite increasing interest in modulating the immune response of fish, providing a combination of probiotics and herbal immunostimulants in aquafeed has rarely has been studied. The effects on gilthead seabream (Sparus aurata L.) of the dietary administration of fenugreek (Trigonella foenum graecum) seeds alone (FE), or combined with one of the following probiotic strains: Bacillus licheniformis (FEBL), Lactobacillus plantarum (FELP) or Bacillus subtilis (FEBS) were evaluated. Fish were fed a control or one of the supplemented diets for 3 weeks. After 2 and 3 weeks of the feeding trial, the abundance of terminal carbohydrates, IgM levels, enzymatic activities (proteases, alkaline phosphatase, esterase and ceruloplasmin) and bactericidal activity were determined in skin mucus. Our results demonstrated that the dietary administration of FE in combination with L. plantarum, particularly, increased carbohydrate abundance, the activity of certain enzymes such as ceruloplasmin, and bactericidal activity against the pathogenic bacterium Photobacterium damselae and the non-pathogenic bacterium B. subtilis in skin mucus at the end of the trial. The carbohydrates most affected by the FELP diet were mannose/glucose, N-acetyl-d-galactosamine and N-acetyl-β-d-glucosamine. Interestingly, IgM levels were significantly higher in fish fed the FELP and FEBS diets whilst protease activity generally increased in all supplemented diets, which could suggests that the main effect in this activity was to the result of FE supplementation although that fact cannot be confirmed because the effects of probiotics addition alone were not studied. These results suggest that the combined dietary administration of fenugreek and L. plantarum will best enhance the skin mucosal immunity response of gilthead seabream.

Dietary Myrtle (Myrtus communis L.) improved non-specific immune parameters and bactericidal activity of skin mucus in rainbow trout (Oncorhynchus mykiss) fingerlings

The present study examined the effects of dietary Myrtle (Myrtus communis L.) on non-specific immune parameters and bactericidal activity of skin mucus in rainbow trout (Oncorhynchus mykiss) fingerlings. Three hundred and sixty fingerlings (6.50 ± 0.55 g (were distributed in twelve cages (65 × 65 × 65 cm) with a metal framework. The study included four treatments repeated in triplicates. The treatments were feeding trouts with experimental diets containing different levels (0, 0.5, 1 and 1.5%) of Myrtle powder. The fingerlings were fed on experimental diet for sixty days and then skin mucus non-specific immune parameters as well as bactericidal activity were measured. At the end of the trial, the highest skin mucus soluble protein level was observed in group fed with 1.5% Myrtle (P < 0.05). The alkaline phosphatase (ALP) activity was significantly increased in fish groups fed 1 and 1.5% Myrtle compared with the control group (P < 0.05). However, evaluation of skin mucus lysozyme activity showed no significant difference between treatments and control group (P > 0.05). Also, no antibacterial activity was detected against Escherichia coli, Staphylococcus aureus and Salmonella enterica in all treatments and control group. Whereas skin mucus of rainbow trout showed antimicrobial activity against fish pathogens (Aeromonas hydrophila and Yersinia ruckeri) in 1 and 1.5% Myrtle treatments. These results indicated beneficial effects of dietary Myrtle on mucosal immune parameters of fingerling rainbow trout.

Dietary yeast Sterigmatomyces halophilus enhances mucosal immunity of gilthead seabream (Sparus aurata L.)

A yeast was isolated from hypersaline sediments, grown and phylogenetically characterized as Sterigmatomyces halophilus strainN16. The dietary administration of this yeast was studied for its effect on skin mucosal immune and antioxidant status of gilthead seabream (Sparus aurata L.). Fish were fed a commercial diet (control, non-supplemented diet), or the same commercial diet supplemented with 0.55% or 1.1% of yeast for 15 and 30 days. One month after the end of the trial, fish from all treatments were intraperitoneally injected with pathogenic Vibrio parahaemolyticus and further fed with the same diets for one week, after which fish were also sampled. Significant increases were observed in the immune activities determined in the fish fed the yeast supplemented diets compared with the values recorded in mucus of fish from the control group. The expression levels of trypsin (one of the main digestive enzymes) and several immune-related genes (IL-1β, TNF-α, IgM, C3 and lysozyme) were also evaluated by real-time PCR in intestine and skin. Interestingly, trypsin gene expression in intestine was up regulated in both experimental diets compared with the control group, particularly in fish fed with 0.55% of S. halophilus at any time of the experimental trial. Immune-related genes in intestine and skin were strongly expressed principally in fish fed with 0.55% of S. halophilus for 15 days and 1.1% for 30 days and after infection, respectively. The present results suggest that the yeast S. halophilus can be considered as a novel fish immunostimulant. The excellent potential of marine microorganisms isolated from extreme environments with beneficial properties for fish is discussed.

Effects of synbiotics on immunity and disease resistance of narrow-clawed crayfish, Astacus leptodactylus leptodactylus (Eschscholtz, 1823)

The aim of this study was to evaluate the effects of prebiotics (mannanoligosaccharide and xylooligosaccharide), probiotics (Enterococcus faecalis and Pediococcus acidilactici) and synbiotics for 126 days on the immune responses, hemolymph indices, antioxidant enzymes, and biological responses after a 48-hour Aeromonas hydrophila exposure of sub-adult crayfish (11.45 ± 1.87 g). Most antibacterial activities were observed in the shell mucus of crayfish fed a diet containing xylooligosaccharide + E. faecalis and mannanoligosaccharide + Pediococcus acidilactici against Nocardia brasilience and Vibrio harveyi (p < 0.05). Feeding crayfish a xylooligosaccharide + E. faecalis diet increased protein levels and the activities of alkaline phosphatase and lysozyme in the shell mucus after the feeding trial and 48 h after the A. hydrophila-injection challenge (p < 0.05). The highest ratio of the lactobacillus count to the total viable count was observed in synbiotic diets (p < 0.05). Feeding crayfish a xylooligosaccharide + E. faecalis diet increased the growth rate and the resistance to the A. hydrophila-injection challenge (p < 0.05). These results revealed that feeding crayfish with synbiotic diets was more effective than a single administration with prebiotics and probiotics.

Yeast derived from lignocellulosic biomass as a sustainable feed resource for use in aquaculture

The global expansion in aquaculture production implies an emerging need of suitable and sustainable protein sources. Currently, the fish feed industry is dependent on high-quality protein sources of marine and plant origin. Yeast derived from processing of low-value and non-food lignocellulosic biomass is a potential sustainable source of protein in fish diets. Following enzymatic hydrolysis, the hexose and pentose sugars of lignocellulosic substrates and supplementary nutrients can be converted into protein-rich yeast biomass by fermentation. Studies have shown that yeasts such as Saccharomyces cerevisiae, Candida utilis and Kluyveromyces marxianus have favourable amino acid composition and excellent properties as protein sources in diets for fish, including carnivorous species such as Atlantic salmon and rainbow trout. Suitable downstream processing of the biomass to disrupt cell walls is required to secure high nutrient digestibility. A number of studies have shown various immunological and health benefits from feeding fish low levels of yeast and yeast-derived cell wall fractions. This review summarises current literature on the potential of yeast from lignocellulosic biomass as an alternative protein source for the aquaculture industry. It is concluded that further research and development within yeast production can be important to secure the future sustainability and economic viability of intensive aquaculture. © 2016 Society of Chemical Industry.

Dietary galactooligosaccharide elicits positive effects on non-specific immune parameters and growth performance in Caspian white fish (Rutilus frisii kutum) fry

An eight-weeks feeding trial was conducted to investigate the effects of galactooligosaccharide (GOS), on the skin and serum non-specific immune parameters and growth performance of Caspian white fish (Rutilus frisii kutum) fry. Fish (2.07 ± 0.08 g) were fed different levels of GOS (0%, 1%, 2% and 3%). No significant (P > 0.05) difference was observed in mucus protease activity, but inclusion of 1% GOS significantly (P < 0.05) elevated total immunoglobulin (Ig) level and lysozyme activity. Evaluation of serum non-specific immune parameters revealed significant (P < 0.05) increase in serum total Ig and lysozyme activity of fish fed 1% or 2% GOS compared those of fish fed control diet. Furthermore, the serum alternative haemolytic complement activity (ACH50) was significantly (P < 0.05) elevated in all prebiotic groups regardless of inclusion levels. Administration of GOS in diet significantly (P < 0.05) improved growth performance and feed utilisation. The results of the present study revealed that GOS administration is beneficial by improving immune response and growth performance of Caspian white fish.

The effects of galactooligosaccharide on systemic and mucosal immune response, growth performance and appetite related gene transcript in goldfish (Carassius auratus gibelio)

The present study investigates the effects of supplementation of goldfish (Carassius auratus gibelio) diet with galactooligosaccharide (GOS) on serum immune response, mucosal immune parameters as well as appetite-related (Ghrelin) and immune-related (TNF-1α and TNF-2α) genes expression. One hundred and eighty fish with an average weight of 4.88 ± 0.28 g were stocked in twelve 500-L fiberglass tank assigned to four treatments repeated in triplicates. Fish were fed on experimental diets contain 0.5, 1 and 2% GOS for 6 weeks. Supplementation of diet with GOS had no remarkable effect on goldfish growth performance (P > 0.05). Evaluation of serum innate immune parameters revealed that supplementation of diet with GOS significantly elevated total protein, Albumin, Globulins, Lysozyme and Alkaline phosphatase activity as well as agglutination compared to control group in a dose dependent manner (P < 0.0.5). Also, Fish fed 2% GOS supplemented diet showed increased skin mucus immune response (total protein and lysozyme activity) compared other groups (P < 0.0.5); except in case of ALP activity. Molecular studies on appetite (ghrelin) and inflammatory cytokine (TNF-1α and TNF-2α) genes expression revealed remarkably decrease and increase, respectively in GOS fed fish (P < 0.0.5). These results showed immunomodulatory effects of dietary GOS on serum and skin mucus response as well as expression of inflammatory cytokines in goldfish, though this supplement decreased appetite gene expression and had no effect on growth performance.

Stress and immune responses in skin of turbot (Scophthalmus maximus) under different stocking densities

Fish skin and its mucus provide the first line of defense against chemical, physical and biological stressors, but little is known about the role of skin and its mucus in immune response to crowding stress. In the present study, we investigated the stress and immune responses in skin of turbot (Scophthalmus maximus) under different stocking densities. Turbot (average weight 185.4 g) were reared for 120 days under three densities: low density (LD), medium density (MD), and high density (HD). After 120 days, fish were weighed and sampled to obtain blood, mucus and skin tissues which were used for analyses of biochemical parameters and genes expression. The results showed HD treatment significantly suppressed growth and enhanced plasma cortisol and glucose levels (P < 0.05). In mucus, the activities of lysozyme (LZM), alkaline phosphatase (ALP) and esterase in HD treatment were lower than LD and MD treatments (P < 0.05) In skin, HD treatment resulted in up-regulation in malondialdehyde (MDA) formation and heat shock protein 70 (HSP 70) mRNA level, and down-regulation in activity of superoxide dismutase (SOD) and the transcriptions of glutathione-s-transferase (GST), interleukin-1β (IL-1β), tumor necrosis factor -α (TNF-α), insulin-like growth factor- (IGF-) and LZM (P < 0.05). Overall, the data suggested that overly high stocking density was a stressor which caused an immunosuppression in skin of turbot. Moreover, this information would help to understand the skin immunity and their relation with stress and disease in fish.

The effects of feeding with synbiotic (Pediococcus acidilactici and fructooligosaccharide) enriched adult Artemia on skin mucus immune responses, stress resistance, intestinal microbiota and performance of angelfish (Pterophyllum scalare)

The aim of this study was to evaluate the effects of feeding on synbiotic (Pediococcus acidilactici and fructooligosaccharide) enriched adult Artemia franciscana on skin mucus immune responses, stress resistance, intestinal microbiota and growth performance of angelfish (Pterophyllum scalare). Three hundred and sixty fish with initial weight 3.2 ± 0.13 g were randomly divided into twelve aquaria (50 L) assigned to four groups in triplicates. Fish were fed for 7 weeks with dietary treatments, including treatment 1: feeding adult Artemia without enrichment (control group), treatment 2: feeding adult Artemia enriched with lyophilised probiotic P. acidilactici (700 mg L(-1)), 3: feeding adult Artemia enriched with prebiotic fructooligosaccharide (FOS) (100 mg L(-1)), group 4: feeding adult Artemia enriched with synbiotic (P. acidilactici (700 mg L(-1)) + FOS (100 mg L(-1))). Skin mucus immune responses (lysozyme activity, total Immunoglobulin and protease), stress resistance against environmental stress (acute decrease of temperature and increase salinity), intestinal microbiota as well as growth indices were measured at the end of feeding trial. Artemia enriched with synbiotic significantly improved growth performance compared to other treatments (P < 0.05). The highest weight gain and specific growth rate (SGR) was observed in synbiotic fed fish (P < 0.05). Compared to the other treatments, the population of lactic acid bacteria was significantly higher in the intestinal microbiota of fish fed synbiotic supplemented diet (P < 0.05). In the environmental stress challenge test, the maximum resistance to abrupt decrease of temperature (17 °C) or elevation of salinity (12 g per liter) was observed in the synbiotic treatment. Also, the total immunoglobulin and lysozyme activity level of skin mucus was significantly elevated in fish fed Artemia enriched with synbiotic (P < 0.05). These results revealed that feeding angelfish with synbiotic enriched Artemia was more effective than singular enrichment with probiotics or prebiotics.

The effects of garlic-supplemented diets on skin mucosal immune responses, stress resistance and growth performance of the Caspian roach (Rutilus rutilus) fry

This study was conducted to evaluate the effects of garlic supplementation on some skin mucus immune parameters, mucus antimicrobial activity and growth performance of the Caspian roach (Rutilus rutilus caspicus) fry. Fish (1 ± 0.07 g) were divided into four groups fed diets containing 0 (control), 5, 10 and 15 g kg(-1) garlic for 8 weeks. The results showed that there was a significant increase in weight gain and specific growth rate in those fish fed garlic diets compared with the control (P < 0.05). Condition factor was not significantly affected by garlic dosage. At the end of trial, the epidermal mucus protein level, alkaline phosphatase and antimicrobial activity against 2 g-negative bacteria (Escherichia coli and Serratia marcescens) and gram-positive bacteria (Streptococcus faecium and Micrococcus luteus) were measured. Skin mucus alkaline phosphatase, protein levels and antimicrobial activity were increased following garlic administration, and the bacterial growth inhibition zones were significantly elevated in garlic-fed fish (P < 0.05). In salinity stress experiment, no differences were observed for survival rate among the experimental diets. No mortality was recorded during the feeding trial. These results indicated that dietary garlic beneficially affects the skin mucus immune parameters and growth performance of the Caspian roach fry.

Enrichment of gilthead seabream (Sparus aurata L.) diet with palm fruit extracts and probiotics: Effects on skin mucosal immunity

Fish skin mucus contains numerous immune substances still poorly studied. To date, there are no studies regarding the possible influence of dietary supplements on such important substances. In the present work, a commercial diet used as control diet was enriched with: 1) probiotic Shewanella putrefaciens (Pdp11 diet, 10(9) cfu g(-1)); 2) probiotic Bacillus sp. (Bacillus diet, 10(9) ufc g(-1)); 3) aqueous date palm fruits extracts (DPE diet, 4%), and 4) a combination of Pdp11 + Bacillus sp + aqueous DPE (Mix diet). After 2 and 4 weeks of the feeding trial, enzymatic activities (proteases, antiproteases and peroxidases), IgM levels and terminal carbohydrates abundance were determined in skin mucus. In addition, the expression of certain immune related genes was evaluated in the skin. Our results demonstrated the significant alteration of the terminal carbohydrate abundance in skin mucus. Carbohydrates more affected by experimental diets were N-acetyl-galactosamine, N-acetyl-glucosamine, galactose, mannose, glucose and fucose. IgM, peroxidase activity and protease were also significantly higher in fish fed enriched diets. For last, an important up-regulation on the immune related gene studied on the skin was also detected. Present findings provide robust evidence that fish skin mucosal immunity can be improved by the diet.

Terminal carbohydrate composition, IgM level and enzymatic and bacteriostatic activity of European sea bass (Dicentrarchus labrax) skin epidermis extracts

Although the skin is one of the main defense barriers of fish to date, very little is known about the immune implications and the properties of the numerous substances present in skin cells. In the present study, terminal carbohydrate composition and some components of the skin immunity (total IgM level, and several enzymatic and bacteriostatic activities) present on aqueous and organic epidermal extracts of European sea bass (Dicentrarchus labrax) were determined. Most of the parameters measured followed a protein concentration dose-response. Curiously, both skin extracts have similar levels of total IgM. However, aqueous extracts showed higher presence of some terminal carbohydrates, alkaline phosphatase and esterase activities and lower proteases and ceruloplasmin activities than epidermal organic extracts. Regarding the bacteriostatic activity, the growth of all the bacterial strains tested was reduced when cultivated in presence of organic extracts, being the observed reduction correlated to the protein concentration present in the extract sample. On the contrary, skin aqueous extracts have no significant effect on bacterial growth or even allow bacteria to overgrow, suggesting that the bacteria could use the extracts as a nutrient source. The results are discussed and compared with the same activities studied on fish skin mucus in order to understand their possible implications on mucosal immunity.

Modulation of innate immune response, mucosal parameters and disease resistance in rainbow trout (Oncorhynchus mykiss) upon synbiotic feeding

The present study investigates the effects of dietary supplements of galactooligosaccharides (GOS), Pediococcus acidilactici and P. acidilactici + GOS on innate immune response, skin mucus as well as disease resistance of rainbow trout (Oncorhynchus mykiss) fingerlings (15.04 ± 0.52 g). After 8 weeks of feeding, several innate immune (lysozyme, alternative complement and respiratory burst activities) and skin mucus parameters (bactericidal activity against Streptococcus faecium, Streptococcus iniae, Serratia marcescens, Staphylococcus aureus and Escherichia coli and mucus protein content) were studied. The results indicated that the three supplemented diet significantly increased innate immune response and skin mucus parameters in rainbow trout. The highest innate immune response, skin mucus activity as well as protein level was observed in synbiotic fed fish. Furthermore, at the end of the feeding experiment, some fish were intraperitoneally injected with Streptococcus iniae to determine the disease resistance. The mortality of fingerlings fed supplemented diet was significantly lower than fish from control group being the lowest mortality recorded in synbiotic fed fish group.

Evaluation of waterborne exposure to heavy metals in innate immune defences present on skin mucus of gilthead seabream (Sparus aurata)

Aquatic animals are continuously exposed to chemical pollutants but the effects evoked in skin surfaces, which receive the most direct contact with them, are poorly investigated. Terminal carbohydrate composition and immunological components present in skin mucus of gilthead seabream (Sparus aurata L.) specimens exposed to waterborne sublethal dosages of heavy metals [arsenic (As2O3), cadmium (CdCl2) and mercury (CH3HgCl) at 5, 5 and 0.04 μM, respectively for 2, 10 and 30 days were analysed. Moreover, the presence of a fucose binding lectin (FBL) was evaluated by western blot and the protein profiles were by SDS-PAGE and HPLC. Results showed little effects of heavy metals in the presence of several terminal carbohydrates with few increments or decrements. Most of the enzyme activities related to immune responses were increased upon heavy metal exposure in the skin mucus including bactericidal activity. Methylmercury produced the most dramatic changes increasing all the activities. Moreover, the FBL was undetected in any of the control fish skin mucus but was evident in all the heavy metal exposed fish. In addition, As and Cd produced a clear change in the protein profile as evidenced by the lack of a protein band of around 12 kDa which is absent. These protein changes were more evident with the HPLC study showing the presence of different peaks and differences in intensity. The present results could be useful for better understanding the role and their behaviour of the mucosal immunity in skin as a key component of the innate immune system against pollutants.

The effects of Lactobacillus acidophilus as feed supplement on skin mucosal immune parameters, intestinal microbiota, stress resistance and growth performance of black swordtail (Xiphophorus helleri)

The present study evaluates the effects of different levels of dietary Lactobacillus acidophilus as feed supplement on intestinal microbiota, skin mucus immune parameters and salinity stress resistance as well as growth performance of black swordtail (Xiphophorus helleri). One-thousand and eight hundred healthy black swordtail larvae (0.03 ± 0.001 g) were randomly distributed in 12 tanks (100 L) at a density of 150 fish per aquaria and fed different levels of dietary L. acidophilus (0, 1.5 × 10(8), 3 × 10(8) and 6 × 10(8) CFU g(-1)) for 10 weeks. At the end of trial, there were significant differences among antibacterial activity of skin mucus in probiotic fed fish and control group (P < 0.05). Furthermore, the skin mucus protein level and alkaline phosphatase activity in control group were significantly lower than those of L. acidophilus fed fish (P < 0.05). Microbiological assessments revealed that feeding with probiotic supplemented diet remarkably increased total autochthonous bacteria and autochthonous lactic acid bacteria levels (P < 0.05). The results showed that dietary administration of L. acidophilus significantly elevated black swordtail resistance against salinity stress (i.e survival %) (P < 0.05). Also, dietary administration of different levels of L. acidophilus improved weight gain, SGR, FCR compared to fish fed unsupplemented diet (P < 0.05). These results demonstrate beneficial effects of dietary L. acidophilus on mucosal immune parameters, intestinal microbiota, stress resistance and growth parameters of black swordtail and the appropriate inclusion is 6 × 10(8) CFU g(-1).