Along with the intensification of culture systems to meet the increasing global demands, there was an elevated risk for diseases outbreak and substantial loss for farmers. In view of several ...drawbacks caused by prophylactic administration of antibiotics, strict regulations have been established to ban or minimize their application in aquaculture. As an alternative to antibiotics, dietary administration of feed additives has received increasing attention during the past three decades. Probiotics, prebiotics, synbiotics and medicinal plants were among the most promising feed supplements for control or treatments of bacterial, viral and parasitic diseases of fish and shellfish. The present review summarizes and discusses the topic of potential application of probiotics as a means of disease control with comprehensive look at the available literature. The possible mode of action of probiotics (Strengthening immune response, competition for binding sites, production of antibacterial substances, and competition for nutrients) in providing protection against diseases is described. Besides, we have classified different pathogens and separately described the effects of probiotics as protective strategy. Furthermore, we have addressed the gaps of existing knowledge as well as the topics that merit further investigations. Overall, the present review paper revealed potential of different probiont to be used as protective agent against various pathogens.
In fish, like other organisms, the lack of balance between the production of reactive oxygen species (ROS) and antioxidant defense system (so-called oxidative stress) can cause DNA hydroxylation, ...protein denaturation, lipid peroxidation, apoptosis, and ultimately cell damage. To improve the antioxidant defense capability, different approaches such as the administration of synthetic antioxidants were practiced. During the past years, dietary approaches have been suggested as a promising way of increasing the antioxidant defense activity in different fish and shellfish species. Among them, microbial feed additives (including pre-, pro-, and synbiotics) showed promising effects in terms of affecting antioxidant enzymes activities. Their mechanism of action in influencing the antioxidant system is not fully understood. The present review briefly discussed the antioxidant defense activity in fish, influencing factors with special focus on dietary approaches and microbial feed additives. In addition, the proposed mechanism of action of microbial feed additives on the antioxidant system has been discussed.
Water quality encompasses the water physical, biological, and chemical parameters. It generally affects the fish growth and welfare. Thus, the success of a commercial aquaculture project depends on ...supplying the optimum water quality for prompt fish growth at the minimum cost of resources. Although the aquaculture environment is a complicated system, depending on various water quality variables, only less of them have a critical role. One of these vital parameters is dissolved oxygen (DO) level, which requires continuous oversight in aquaculture systems. In addition, the processes of natural stream refinement require suitable DO levels in order to extend for aerobic life forms. The depletion of DO concentration (called hypoxia) in pond water causes great stress on fish where DO levels that remain below 1–2 mg/L for a few hours can adversely affect fish growth resulting in fish death. Furthermore, hypoxia has substantial effects on fish physiological and immune responses, making them more susceptible to diseases. Therefore, to avoid disease outbreak in modern aquaculture production systems where fish are intensified and more crowded, increasing attention should be taken into account on DO levels.
The present study investigates the efficiency of graded levels (0, 0.25, 0.5, 1 and 2%) of sodium propionate (SP) on Caspian white fish (Rutilus frisii kutum) fry growth performance, skin mucus ...immune response as well as humoral immune parameters. Fish were divided into 5 groups repeated in triplicates and each group were fed on experimental diets for 7 weeks. Growth performance parameters, skin mucus total immunoglobulin (Ig) level, lysozyme, protease and alkaline phosphatase (ALP) activity as well as the non-specific humoral immune response (total Ig, lysozyme, alternative haemolytic complement activity (ACH50) were determined at the end of feeding trial. The results showed that supplementation of diet with 0.25% SP significantly improved growth performance compared control group (P < 0.05). Evaluation of skin mucus immune parameters revealed significant elevation in fish fed SP supplemented diet (P < 0.05). Variation in the levels of responses was evident among different SP level and more pronounced in 0.25% and 0.5% treatments. Regarding non-specific humoral response, remarkably increased lysozyme and ACH50 activities were observed in 0.25% and 0.5% groups compared other treatments (P < 0.05); highest level in 0.25% SP fed fish. No significant change was noticed for serum total Ig compared control group (P > 0.05), except 0.25% SP treatment which was significantly higher than those in other groups (P < 0.05). These results revealed that inclusion of administration of 0.25% and 0.5% SP in early stage of the Caspian white fish culture could improve mucosal and non-specific immune responses as well as performance.
•Dietary sodium propionate increased mucosal immune response in Caspian white fish fry.•Sodium propionate beneficially affected non-specific humoral immune responses.•Sodium propionate fed Caspian white fish fry showed improved growth performance.•Low levels of sodium propionate inclusion were more beneficial.
The gut immune system is, the main option for maintaining host's health, affected by numerous factors comprising dietary constituents and commensal bacteria. These dietary components that affect the ...intestinal immunity and considered as an alternative of antibiotics are called immunosaccharides. Fructooligosaccharide (FOS), Galactooligosaccharide (GOS), inulin, dietary carbohydrates, and xylooligosaccharide (XOS) are among the most studied prebiotics in human as well as in aquaculture. Although prebiotics and probiotics have revealed potential as treatment for numerous illnesses in both human and fish, a comprehensive understanding of the molecular mechanism behind direct and indirect effect on the intestinal immune response will help more and perhaps extra effective therapy intended for ailments. This review covers the most newly deep-rooted scientific outcomes about the direct and indirect mechanism through which these dietetic strategies can affect intestinal immunity of terrestrial and aquatic animals. Prebiotics exert an influence on gut immune system via the increase in lysozyme and phagocytic activity, macrophage activation and stimulation of monocyte-derived dendritic cells. Furthermore, these functional molecules also enhance epithelial barrier function, beneficial gut microbial population, and production of intermediate metabolites for example short chain fatty acids (SCFAs) that assist in balancing the immune system. Moreover, emphasis will be sited on the relationship among food/feed, the microbiota, and the gut immune system. In conclusion, further studies are nonetheless essential to confirm the direct effect of prebiotics on immune response.
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•Prebiotics promote innate and intestinal immune system.•The indirect effects of prebiotics on immune response are clearer than direct effects.•SCFAs are main key regulator of immune response by indirect method.•FOS, GOS and Inulin are most useful prebiotics in modulating the immune response.
Restriction or ban on antibiotic administration in aquaculture encourages the development of environment‐friendly feed additives as immunostimulants. Short‐chain fatty acids (SCFAs) and their salts ...are ‘Generally Regarded as Safe’ and are often used as antimicrobials in the livestock feed industry. Formate, acetate, propionate, butyrate and their salts are among the most studied SCFAs in aquaculture. These SCFAs affect the host performance as well as physiological response upon three ways: either through effects of the feeds that are being administered, through effects on the gastrointestinal tract of the animal or through direct effects on metabolism. To date, most of the available data are focused on the effects of SCFAs on growth performance and feed utilization. Despite extensive research studies on the effects of the different type of SCFAs and their salts on growth performance and feed utilization, the effects of these feed additives on the health of aquatic organisms have only been receiving attention recently. The results of the studies demonstrated beneficial effects of SCFAs as promising feed additives in aquaculture. The present review article summarizes and discusses the topic of dietary administration of SCFAs and their salts in aquaculture with a closer look at the recent findings regarding the effects of SCFAs on growth performance and health status of fish and shellfish. Furthermore, this review identifies the gaps of existing knowledge regarding the roles of SCFAs in the growth and health status of aquatic animals and suggests research areas that merit further investigations.
A complex and dynamic community of microorganisms, play important roles within the fish gastrointestinal (GI) tract. Of the bacteria colonizing the GI tract, are lactic acid bacteria (LAB) generally ...considered as favorable microorganism due to their abilities to stimulating host GI development, digestive function, mucosal tolerance, stimulating immune response, and improved disease resistance. In early finfish studies, were culture-dependent methods used to enumerate bacterial population levels within the GI tract. However, due to limitations by using culture methods, culture-independent techniques have been used during the last decade. These investigations have revealed the presence of
, and
as indigenous species. Numerous strains of LAB isolated from finfish are able to produce antibacterial substances toward different potential fish pathogenic bacteria as well as human pathogens. LAB are revealed be the most promising bacterial genera as probiotic in aquaculture. During the decade numerous investigations are performed on evaluation of probiotic properties of different genus and species of LAB. Except limited contradictory reports, most of administered strains displayed beneficial effects on both, growth-and reproductive performance, immune responses and disease resistance of finfish. This eventually led to industrial scale up and introduction LAB-based commercial probiotics. Pathogenic LAB belonging to the genera
, and
have been detected from ascites, kidney, liver, heart, and spleen of several finfish species. These pathogenic bacteria will be addressed in present review which includes their impacts on finfish aquaculture, possible routes for treatment. Finfish share many common structures and functions of the immune system with warm-blooded animals, although apparent differences exist. This similarity in the immune system may result in many shared LAB effects between finfish and land animals. LAB-fed fish show an increase in innate immune activities leading to disease resistances: neutrophil activity, lysozyme secretion, phagocytosis, and production of pro-inflammatory cytokines (
β
, and
α). However, some LAB strains preferentially induces
instead, a potent anti-inflammatory cytokine. These results indicate that LAB may vary in their immunological effects depending on the species and hosts. So far, the immunological studies using LAB have been focused on their effects on innate immunity. However, these studies need to be further extended by investigating their involvement in the modulation of adaptive immunity. The present review paper focuses on recent findings in the field of isolation and detection of LAB, their administration as probiotic in aquaculture and their interaction with fish immune responses. Furthermore, the mode of action of probiotics on finfish are discussed.
The present study explores the effect of dietary sodium propionate on mucosal immune response and expression of antioxidant enzyme genes in zebra fish (
Danio rerio
). Six hundred healthy zebra fish ...(0.42 ± 0.06 g) supplied, randomly stocked in 12 aquariums and fed on basal diets supplemented with different levels of sodium propionate 0 (control), 5, 10 and 20 g kg
−1
for 8 weeks. At the end of the feeding trial, mucosal immune parameters (TNF-α, IL-1β, Lyz), antioxidant enzyme (SOD, CAT) as well as heat shock protein 70 (HSP70) gene expression were measured. The results revealed feeding on sodium propionate significantly up-regulated inflammatory response genes (TNF-α, IL-1β, Lyz) in a dose-dependent manner (
P
< 0.05). However, antioxidant enzyme genes significantly down-regulated in the treated group compared with control (
P
< 0.05). Also, HSP70 gene expression was higher in the liver of fish fed the basal diet and deceased with elevation of sodium propionate levels in the diet. These results showed beneficial effects of dietary sodium propionate on mucosal immune response as well as the antioxidant defense of zebra fish.
Aquaculture offers a promising source of economic and healthy protein for human consumption and improved wellbeing. This has led to the development of the aquaculture industry, led through advanced ...production technologies and culture systems in many parts of the world. The intensification of fish production systems by farmers to meet consumer's needs, as well as to generate increased profits, creates a source of stress and the added occurrence of disease and subsequent loss. The negative environmental effects of chemical use have caused legislation to imposed regulations and restrictions to decrease their therapeutic or prophylactic use in aquaculture. As a result, dietary approaches have been suggested as an alternative. Medicinal herbs have been investigated for use in finfish diets to improve immune response and disease resistance. This review paper discusses the suggested modes of action of the effects of medicinal herbs on fish physiology and the immune systems. In addition, a comprehensive literature review on the effects on bacterial, viral, and parasitic diseases is also presented. An added objective was to address the gap between existing knowledge and future perspectives for the improvement of fish health and disease resistance through the use of natural products.
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