Non‐specific immune responses and intestinal immunity of common carp (Cyprinus carpio) fed Jujube (Ziziphus jujube) fruit extract

This study investigated the effects of Jujube (Ziziphus jujube) fruit extract (JFE) as an excellent source of nutrients and phytochemicals on the innate immune responses and expression of genes involved in intestinal immunity of common carp (Cyprinus carpio) fingerlings. Three hundred healthy carps (10.78 ± 0.05 g) fingerlings were randomly allocated to 12 fibre glass tanks (300L; 15 fish per tank) and fed for 8 weeks with experimental diets which contained different levels of JFE (0%, 0.25%, 0.5%, or 1%). Thereafter, serum non‐specific immune parameters [total immunoglobulin (Ig) as well as alternative complement (ACH50) and lysozyme activity (SL)] and expression of genes involved in intestinal immunity (lyz, tnf‐alpha, il1b, il8, il10, and tgfb) were measured. The results revealed a significant elevation of Ig level in the JFE‐fed fish (p < 0.05) over the control fish. However, there was no significant difference among treated groups in case of serum total Ig. The highest levels of SL and ACH50 were observed in fish fed 1% of JFE. Nonetheless, no significant difference was noticed regarding SL and ACH50 of control and other supplemented groups (0.25% and 0.5% JFE). Also, expression of lyz, tnf‐alpha, and il1b genes increased significantly (p < 0.05) in JFE‐fed fish, in a dose‐dependent manner. On the other hand, significant (p < 0.05) down‐regulation of il110 and tgfb were noticed in treated groups. The present findings suggested that extraction of Jujube, Z. jujube fruit, possesses beneficial effects on immune responses of common carp.     

Xylanase supplementation in plant protein‐enriched diets improves growth performance by optimizing the intestinal microflora and enhancing the intestinal immune function in grass carp grow‐out (Ctenopharyngodon idella)

This study investigated the effect of xylanase supplementation of a plant protein‐enriched diet on the growth performance and intestinal immune function of grass carp grow‐out (Ctenopharyngodon idella). Five hundred forty healthy grass carp grow‐out (232.74 ± 0.12 g) were fed diets containing graded levels of xylanase for 60 days. The fish were then challenged with Aeromonas hydrophila for 14 days. The results indicated that xylanase supplementation (a) improved fish growth performance and optimized the intestinal microflora; (b) increased lysozyme and acid phosphatase activities, complement and immunoglobulin M levels and antibacterial peptide hepcidin mRNA levels, thereby enhancing fish intestinal immune function; and (c) attenuated intestinal inflammation associated with the inhibition of the NF‐κB signalling pathway and activation of the TOR signalling pathway, resulting in the down‐regulation of pro‐inflammatory cytokines [except IL‐1β and IL‐12p40 in the distal intestine (DI) and IL‐6 in the proximal intestine (PI)] and up‐regulation of anti‐inflammatory cytokines [except IL‐4/13B and TGF‐β1 in the mid intestine (MI) and DI]. Finally, on the premise of a basal diet containing 45.8 g/kg araboxylans (AXs), the appropriate supplementation levels based on the ability to improve per cent weight gain (PWG) and prevent enteritis were estimated to be 1,527 and 1,608 U/kg, respectively.     

Possible effect of lesser galangal (Alpinia officinarum) extracts encapsulated into mesoporous silica nanoparticles on the immune status of rainbow trout (Oncorhynchus n)

Using plant extracts as immunostimulants in aquaculture has prove effectiv in resisting infectious disease, in addition to being safe and inexpensive. The present study is concerned about the prospective mode of action of using lesser galangal extract (Alpinia officinarum) encapsulated into amine surface functionalized mesoporous silica nanoparticles (MSN) in order to elevate the immune status of rainbow trout (Oncorhynchus mykiss). Fish were randomly divided into 6 groups and fed for 4 weeks with commercial diets supplemented with 0% (control), 0.5% and 1.5% of lesser galangal extract, and with previous concentrations encapsulated with MSN (0.5% + MSN, 1.5% + MSN) and MSN (without extract). The effects of the feeding trial on the innate humoural immune parameters (total protein, myeloperoxidase content, lysozyme antiproteases and bactericidal activities) in rainbow trout were examined. Also, the influence of dietary supplement on some immune‐related genes in rainbow trout head kidney (TNF, IL‐8, IL‐1b, LYZ2 and CD4) after challenge with Yersinia ruckeri was examined. The results revealed enhancement in immune parameters in all treatment groups compared to the control, especially in the fish group fed with 1.5% + MSN which showed the highest significant difference (p < .05) in total protein, lysozyme and antiproteases activities. Also, feeding lesser galangal extract encapsulated into MSN led to an increase in myeloperoxidase content and bactericidal activity. An improvement in the expression of immune‐related genes has been recorded in fish groups fed doses of lesser galangal extract and lesser galangal extract encapsulated into MSN compared to the control or to the group fed with MSN only. Particularly, the group fed with 0.5% + MSN showed a significant up‐regulation in most of the immune‐related genes. The current investigation supports using lesser galangal extract encapsulated into MSN in fish diets as a supplement to enhance the immune response of rainbow trout and elevate its resistance to infectious diseases.     

Effect of dietary supplementation of palm fruit extracts on the transcriptomes of growth,antioxidant enzyme and immune‐related genes in common carp (Cyprinus carpio) fingerlings

This study investigates the effects of date palm extracts [DPE] (Phoenix dactylifera L. Arecaceae) on growth, immune function and antioxidant system in common carp fingerlings (Cyprinus carpio). One hundred and twenty fish (4.06 ± 0.13 g) were divided into six groups fed on control diet or diets containing 200 mL kg^?1 DPE for 8 weeks. At the end of feeding trial, the expression of different genes was measured. Selected genes were grouped into three categories: growth factor genes in brain and liver [growth hormone (GH), insulin‐like growth factors I and II (IGF‐I and IGF‐II), antioxidant‐related genes in liver [glutathione S‐transferase‐alpha (GST‐α), glutathione reductase (GR) and glutathione peroxidase genes (GPX)] and immune‐related genes in head kidney [interleukin‐8 (IL‐8), interleukin‐10 (IL‐10) and transforming growth factor‐beta (TGF‐β) genes]. The relative expression of the growth‐related genes in fish fed DPE showed no significant increase compared to control group (P > 0.05). On the other hand, DPE altered the expression of genes encoding antioxidants enzymes in liver of fingerlings which was statistically significant with respect to the control samples in case GPX (P < 0.05). Also, DPE caused remarkable increases in the expression of the immune‐related genes (IL‐8, IL‐10 and TGF‐β) analysed on head kidney of common carp fingerlings compared to the control group (P < 0.05). In conclusion, it can be suggested that administration of DPE in early stages of common carp culture can promote immune efficacy and increase the antioxidant activity.     

Effect of dietary eucalyptol on stress markers,enzyme activities and immune indicators in serum and haematological characteristics of common carp (Cyprinus carpio) exposed to toxic concentration of ambient copper

In the present study, protective effects of dietary eucalyptol were investigated against copper toxicity in common carp (Cyprinus carpio). The fish were fed with diets supplemented with 0 (control), 0.5% and 1% eucalyptol for 14 days before exposure to 0.25 mg/L ambient copper for 7 days. Blood samples were taken from the fish before and 1, 3 and 7 days after copper challenge. Before copper challenge, eucalyptol significantly decrease serum aspartate aminotransferase (AST) activity, but increase blood WBC, RBC, hematocrit and haemoglobin, serum lysozyme, total immunoglobulin (Ig) compared with the control. Copper exposure led to stress, tissue damage and immunosuppression. After the copper challenge, significant elevation in serum cortisol, glucose, alanine aminotransferase (ALT) and AST, but decrease in blood RBC and WBC, and serum lysozyme, complement (ACH50) and total immunoglobulin (Ig) was observed. Eucalyptol administration significantly mitigated the increase in serum cortisol, glucose, ALT and AST, and decrease in WBC, ACH50, lysozyme and total Ig. Dietary 1% eucalyptol had significantly higher protective effects than 0.5% in the case of serum AST, lysozyme, total Ig and ACH50. In conclusion, eucalyptol has beneficial health effects on common carp and enables to mitigate copper‐induced stress, tissue damage, and immunosuppression. Eucalyptol at the dietary 1% level is recommended to protect common carp against adverse effects of copper toxicity.     

The study of antioxidant enzymes and immune‐related genes expression in common carp (Cyprinus carpio) fingerlings fed different prebiotics

The aim of the present study was to study the effects of different prebiotics (galacto‐, fructooligosaccharide and inulin) on immune response and oxidative stress of common carp (Cyprinus carpio) fingerlings at the molecular level. A total number of 240 fish (13.85 ± 0.85 g) were supplied and randomly stocked in twelve fiberglass tanks (20 specimens per tank). Fish were fed a basal formulated diet (Control) or basal diet supplemented with equal level (2%) of different prebiotics (four treatments repeated in triplicated) for 8 weeks. At the end of feeding trial, the expression of immune‐related genes (interleukin 1 beta [IL‐1β], IL‐8, IL‐10, lysozyme [LYZ], tumour necrosis factor alpha [TNF‐α] and transforming growth factor beta [TGF‐β]) were determined in head kidney and intestine tissues and the expression of antioxidant‐related genes (glutathione S‐transferase [GST‐α], glutathione reductase [GR] and glutathione peroxidase genes [GPX]) were studied in intestine. The results revealed that dietary administration of prebiotics modulated the expression of immune‐related genes and the degree of expression was affected by the type of prebiotics and the organ that was used for analyses. Also, evaluation of antioxidant genes expression showed that GSTα and GR expression levels increased as a result of feeding common carp with the prebiotics. According to these findings, it can be concluded that feeding on different prebiotics had altered effects on the expression of immune and antioxidant‐related genes.     

Dietary 1,8‐cinoele affects serum enzymatic activities and immunological characteristics in common carp (Cyprinus carpio) exposed to ambient ammonia

The present study aimed to investigate effects of dietary 1,8‐cineole (cineole) on common carp (Cyprinus carpio) health under ammonia toxicity. The fish were fed with four diets supplemented by 0 (control), 0.1 (0.1C), 0.5 (0.5C), and 1 (1C) percent cineole for 2 weeks, before a 24‐hr ammonia exposure. Blood samples were taken before and after ammonia exposure. The results showed that ammonia exposure significantly (p < 0.05) increased serum urea levels, and decreased serum alternative complement (ACH50) activity and serum total immunoglobulin (Ig) levels. Cineole significantly (p < 0.05) increased serum ACH50 activity (0.1% and 0.5% levels) and total Ig levels (0.5% levels). There was no significant difference (p > 0.05) in serum total protein, albumin and globulin levels among the treatments. Before ammonia exposure, there was no significant difference (p > 0.05) in serum alkaline phosphatase (ALP), alanine transaminase (ALT), and lysozyme activities among the cineole treatments. The treatment 0.5C had the lowest lactate dehydrogenase (LDH) and aspartate transaminase (AST) activities before ammonia exposure. After ammonia exposure, serum LDH and ALT activities increased in all treatments, but the treatment 0.5C had the lowest activities. Serum ALP activities increased after the ammonia exposure in the control and 1C groups. Serum AST and lysozyme activities increased after the challenge in all groups except for the 0.5C group. Overall, the results suggest that ammonia exposure causes increase in serum LDH, ALP, AST, and ALT activities and decreased immune responses, which are indicator of tissue damage and immunosuppression. 0.5% cineole is capable to suppress adverse effects of ammonia intoxication in carp.     

Effects of dietary phenylalanine on growth,digestive and brush border enzyme activities and antioxidant capacity in the hepatopancreas and intestine of young grass carp (Ctenopharyngodon idella)

This study investigated the effects of phenylalanine on growth, digestive and absorptive ability and antioxidant status of young grass carp (Ctenopharyngodon idella). Young grass carp were fed diets containing 3.4 (basal diet), 6.1, 9.1, 11.5, 14.0 and 16.8 g phenylalanine kg^?1 diet with a fixed of 10.7 g tyrosine kg^?1 diet for 8 weeks. Percent weight gain (PWG), feed efficiency and feed intake of fish were the lowest in fish fed the basal diet (P < 0.05). Trypsin, lipase and amylase activities in the hepatopancreas, and antioxidants including glutathione contents and glutathione reducase activities in the hepatopancreas and intestine were all the highest in fish fed 11.5 g phenylalanine kg^?1 diet (P < 0.05). Trypsin, chymotrypsin and amylase activities in whole intestine, and creatine kinase, Na⁺, K⁺‐ATPase and alkaline phosphatase activities in the proximal intestine, and superoxide dismutase activities in the hepatopancreas and intestine were all the highest when phenylalanine at level of 9.1 g kg^?1 diet (P < 0.05). In conclusion, phenylalanine improved growth, digestive and absorptive ability, and antioxidant capacity of young grass carp. The phenylalanine requirement of young grass carp (256–629 g) based on PWG was 10.4 g kg^?1 diet or 3.44 g 100 g^?1 protein.     

Effects of dietary soy isoflavones on growth,antioxidant status,immune response and resistance of juvenile grass carp (Ctenopharyngodon idella) to Aeromonas hydrophila challenge

The current study was conducted to evaluate the effect of dietary soy isoflavones (SI) on growth performance, antioxidant status, immune response and resistance to Aeromonas hydrophila in juvenile grass carp (Ctenopharyngodon idella). Six diets were formulated to contain 0 (control), 10, 50, 100, 500 or 1,000 mg SI per kg feed. Each diet was randomly allotted to triplicate net cages, and each net cage was stocked with 30 fish. The fish were fed one of the experimental diets to satiation twice per day for 60 days. The results showed that the WGR and DGC of the 500 mg/kg SI‐supplemented group were significantly higher than those of the non‐SI‐supplemented group (p < .05). Serum LZM and IgM activities in the SI‐supplemented groups were improved compared to the control group. SOD and GSH‐Px levels of fish fed the diet containing 500 mg/kg SI were significantly enhanced compared to those of fish fed the control diet (p < .05). Additionally, serum CAT, GSH‐Px and AKP activities in 50, 100 and 500 mg/kg SI‐supplemented groups were significantly higher than that in the control group (p < .05). The expression of most immune‐related genes (including IFN‐γ2, TNF‐α, M‐CSF2, IL‐6, IL‐12p40 and IL‐4) was significantly affected by dietary supplementation of SI. The group fed with 500 mg/kg SI had the highest 7‐day cumulative survival rate after challenge test (p < .05). The current results revealed that dietary inclusion of SI could improve the immune response and resistance against A. hydrophila and the supplementation level is suggested to be 500 mg/kg diet.     

Effects of dietary inclusion of various concentrations of Scutellaria baicalensis Georgi extract on growth,body composition,serum chemistry and challenge test of far eastern catfish (Silurus asotus)

Effects of various concentrations of Scutellaria baicalensis (SB) extract in diets on growth, body composition, serum chemistry and disease challenge test of far eastern catfish (Silurus asotus) were determined and compared with a commercially available immune enhancer. Eight experimental diets were prepared in triplicate: control (Con) diet without supplementation of SB and SB‐0.25, SB‐0.5, SB‐1, SB‐2, SB‐3 and SB‐5 diets containing SB at concentrations of 0.25, 0.5, 1, 2, 3 and 5%, respectively. In addition, 0.1% of a commercial immune enhancer product (CP) was also tested. No significant difference in weight gain of fish was found. Feed consumption, feed efficiency ratio and protein retention of fish were not affected by the experimental diets. At the end of the 8‐week feeding trial, 10 externally normal fish from each tank were infected by Vibrio anguillarum or Strepotococcus iniae. Cumulative mortality of fish fed the Con diet was higher than that of fish fed the all other diets in 10 and 25 days after V. anguillarum or S. iniae infection. Results of this study indicated that dietary inclusion of SB extract was effective in improving survival of eastern catfish after V. anguillarum and S. iniae infection, but the various concentrations of SB did not affect fish performance.     

Effects of Neutral Phytase Supplementation on Biochemical Parameters in Grass Carp,Ctenopharyngodon idellus,and Gibel Carp,Carassius auratus gibelio,Fed Different Levels of Monocalcium Phosphate

Two 8‐wk studies were conducted to evaluate the effects of neutral phytase supplementation on hemato‐biochemical status, liver biochemical parameter, and intestinal digestive enzyme activity of grass carp, Ctenopharyngodon idellus, and gibel carp, Carassius auratus gibelio, fed with different levels of monocalcium phosphate (MCP). The control diet was prepared with 2% MCP but without phytase (P2.0). The other three experimental diets were prepared with the addition of 1.5, 1.0, and 0.5% MCP, respectively, when supplemented with 500 U/kg neutral phytase in each diet and designated as PP1.5, PP1.0, and PP0.5, respectively. The results indicated that the serum alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) activities, as well as the albumin (ALB) content were increased in grass carp (P < 0.05) and gibel carp (P > 0.05) fed with phytase‐supplemented diets. Meanwhile, the serum cholesterol, high‐density lipoprotein, and total protein contents of the two species of fish were increased in comparison to the control. In addition, dietary phytase inclusion did not significantly affect hepatic ALP, ALT, and AST activities in the two species of carp fed with different levels of MCP. Amylase activity increased in foregut and hindgut of both species when fed with the phytase‐supplemented diets while lipase activity was reduced in the foregut and hindgut in both fish. This study suggests that neutral phytase supplementation increases serum ALP, ALT, and AST activities but does not notably affect these enzyme activities in the liver of the two species of carp when fed different levels of MCP. On the other hand, amylase activity increased while lipase activity was reduced in the intestine of the species of carp fed with phytase‐supplemented diets.     

Pre‐challenge and post‐challenge haemato‐immunological changes in Oreochromis niloticus (Linnaeus, 1758) fed argan oil against Lactococcus garvieae

The present study investigated the effects of argan oil, obtained from Argania spinosa, on pre‐ and post‐challenge immuno‐haematological and biochemical responses of Nile tilapia, Oreochromis niloticus. For this purpose, the fish were fed diets containing 0, 0.5%, 1% or 2% argan oil for 45 days. Following 45 days of feeding, fish were challenged with Lactococcus garvieae and mortality was recorded for 15 days. During the pre‐challenge period, significantly higher respiratory burst activity, total white blood cell (WBC), serum lysozyme activity and myeloperoxidase activity were determined in the argan oil‐fed groups. The serum glucose and cholesterol levels decreased whilst total protein and albumin did not change in the groups fed with argan oil‐supplemented diets. After challenge with Lactococcus garvieae, the percentage survival (%) was found to be the highest in the 1% and 2% argan oil‐supplemented feeding groups. Also, there was a significant increase in weight gain, specific growth rate and feed conversion ratio in those fish fed argan oil. The results of this study indicated that after the supplementation of fish diets with argan oil, especially at 1% and 2% concentrations, the immunological, haematological and biochemical values remained similar in both the pre‐ and post‐challenge periods and the immune response against L. garvieae in Nile tilapia was modulated.     

Extracts of Oliviera decumbens and Satureja khuzestanica as immunostimulants affect some innate immunity indices of Cyprinus carpio against Aeromonas hydrophila infection

In this study, the effect of extracts of two herbs (Oliviera decumbens and Satureja khuzestanica) on immune response of carp was investigated. At the beginning of experiment, fish were divided to two groups including vaccinated (using vaccine developed against A. hydrophila) and non‐vaccinated. Fish in both groups were fed diets containing O. decumbens and S. khuzestanica and combination of two herbal extracts for 5 weeks. Control fish (negative control) and fish vaccinated only (positive control) were fed basal diets without supplements of herbal extracts. Lysozyme activity, antibody titre, complement activity and bactericidal activity in serum were measured. After 5 weeks feeding, fish were infected with A. hydrophila and mortalities were recorded. In both experimental groups, no significant differences were found in terms of alternative haemolytic complement (ACH50) activity and antibody titres of Serum. In non‐vaccinated fish group, lysozyme and bactericidal activity of fish fed S. khuzestanica or combination of O. decumbens and S. khuzestanica was higher compared with control and other experimental treatments. In vaccinated fish group, the lysozyme and bactericidal activity was not significant in all treatments compared with control group. The results of this study showed that feeding non‐vaccinated and vaccinated carp with only S. khuzestanica or in combination with O. decumbens enhance only some immunity indices including lysozyme and bactericidal activity in non‐vaccinated fish and these extracts have no immunological stimulatory role on vaccinated individuals.     

Effect of dietary chitosan on growth performance,haematology, immune response,intestine morphology,intestine microbiota and disease resistance in gibel carp (Carassius auratus gibelio)

A 75‐day experiment was conducted with juvenile gibel carp (Carassius auratus gibelio) (4.80 ± 0.01 g) to evaluate effects of dietary chitosan on fish growth performance, haematology, intestine morphology and immune response. Six isonitrogenous (crude protein: 383 g kg^?1), isolipid (97.5 g kg^?1) and isocaloric (gross energy: 16.7 kJ g^?1) diets were formulated to contain 0, 1800, 4000, 7500, 10 000, 20 000 mg kg^?1 chitosan, respectively. The results showed that the growth was depressed when the fish fed with 10 000 mg kg^?1 chitosan. Serum cholesterol, triglyceride and low‐density lipoprotein decreased in 10 000 and 20 000 mg kg^?1 chitosan. On day 75, blood leucocyte phagocytic activity respiratory burst and alternative pathway of complement haemolytic activity were enhanced in 4000 mg kg^?1 chitosan. The number of goblet cell, intraepithelial lymphocyte of mid‐intestine and microvilli height of distal intestine increased at 4000 mg kg^?1 dietary chitosan. Dietary chitosan modulated intestine microbiota, depressed pathogen bacteria Aeromonas veronii‐like and improved Cellulomonas hominis‐like, Bacillus oceanisediminis‐like and two uncultured bacterium‐like species on day 75. Dietary 7500 and 10 000 mg kg^?1 chitosan enhanced the protection against Aeromonas hydrophila infection. In conclusion, oral administration of dietary 7500 mg kg^?1 chitosan for 75 days is recommended for the survival of gibel carp.     

Effects of pyridoxine on antioxidative parameters in juvenile Jian carp (Cyprinus carpio var. Jian)

To investigate the effects of dietary pyridoxine (PN) on antioxidant status of fish in serum, intestine and trunk kidney, 1050 juvenile Jian carp (11.7 ± 0.1 g) were used for the experiment. The carp were divided into seven groups and fed diets containing graded levels of PN (0.20, 1.71, 3.23, 4.96, 6.32, 8.58 and 12.39 mg kg^?1 of diet) for 80 days. Results of the study showed that content of malondialdehyde in serum, intestine and kidney tissues was the highest when fed the diet containing 1.71 mg PN kg^?1 diet (P < 0.05). Meanwhile, the protein carbonyl content of intestine and kidney tissue showed a downward trend to a point (P < 0.05). Conversely, activities of superoxide dismutase, catalase, glutathione peroxidase (GSH‐Px), glutathione S‐transferase, glutathione reductase and glutathione (GSH) content in serum, intestine and kidney tissue were generally higher in PN‐supplemented diets than unsupplemented diet (P < 0.05). The present results indicated that the PN decreased lipid peroxidation and protein oxidation in fish, and partly because of its improved antioxidant enzymes activities and levels of GSH.     

Effects of sodium butyrate stimulation on immune‐related mRNA‐miRNA network in intestine of grass carp

Sodium butyrate is one of the most popular feed additives in animal husbandry. In recent years, sodium butyrate has been increasingly used as supplement in aquaculture. The present study is to investigate the intestinal mRNA and microRNA response to diet with sodium butyrate in grass carp (Ctenopharyngodon idella), an important aquaculture species in China. mRNA and microRNA profiles of intestine of grass carp fed with diet contained 0, 1.0, 2.5, 5.0, 7.5 and 10.0 g/kg sodium butyrate were obtained by RNA‐seq using Illumina Hiseq 2,500 platform. The feeding trial was performed using 18 individuals of 1‐year‐old grass carp (n = 3 for each group) and lasted for 40 days in tanks in laboratory. A total of 349,860,852 sequence reads were generated from six intestinal libraries. Functional analysis of differentially expressed genes showed that genes participated in immune pathways tend to be activated by sodium butyrate supplementation. A total of 700 microRNAs were obtained, including 275 conserved microRNAs and 425 novel microRNAs which are potentially involved in regulating 14,300 genes. Spearman's correlation analysis identified 18 pairs of microRNA‐mRNA associated with immune pathways (p < .01 and R<?0.5). The potential genes targeted by microRNAs include CXCL12, AKT1S1, Cab39 and MHCII which are important genes associated with intestinal immune pathways. To our knowledge, this is the first integrated profiling of both mRNA and microRNA in intestine with supplementation of sodium butyrate in grass carp. The present results suggest that sodium butyrate affects intestinal immune system by regulating microRNA‐mRNA interaction in fish.     

Immunomodulation by Coriandrum sativum seeds (Coriander) and its ameliorative effect on lead‐induced immunotoxicity in Nile tilapia (Oreochromis niloticus L.)

The current study was carried out to evaluate the effects of dietary supplementation of Coriandrum sativum seed powder (CP) and extract (CE) on some immune functions of Oreochromis niloticus, without or with exposure to the immunotoxicant metal lead (Pb). Fish (n = 300) were divided into ten groups, in triplicate. First group (Cont) was fed on the basal control diet. Second (CP20) and third (CP30) groups were fed on CP‐supplemented diets at 20 mg/kg and 30 mg/kg respectively, while fourth (CE20) and fifth (CE30) groups were fed on CE‐supplemented diets at 20 mg/kg and 30 mg/kg respectively. Fish of the sixth (Cont‐Pb), seventh (CP20‐Pb), eighth (CP30‐Pb), ninth (CE20‐Pb) and tenth (CE30‐Pb) groups were exposed to lead (Pb) at 20.2 mg/L and received same diets presented to groups; Cont, CP20, CP30, CE20 and CE30 respectively. The experiment lasted for 45 days. CP and CE dietary supplementation not only significantly enhanced the immune functions, serum lysozyme, nitric oxide, bactericidal activities and relative expression of interleukin‐1β (IL‐1β) of O. niloticus in a concentration‐dependent manner, but also ameliorated the lead‐induced immunosuppressive effects, especially in CE30 received groups. Additionally, lead‐induced fish mortality and levels of lead residues in fish musculature were significantly reduced in response to feeding on CP‐ and CE‐supplemented diets, especially in CE30. Therefore, it could be concluded that coriander dietary supplementation, especially the extract (CE) at 30 mg/kg diet, could be used to enhance the immune response of O. niloticus and to counteract the immunotoxic effects of lead exposure.     

Use of probiotics to enhance growth,stimulate immunity and confer disease resistance to Aeromonas salmonicida in rainbow trout (Oncorhynchus mykiss)

An 8‐week feeding trial was conducted to evaluate the effects of dietary probiotics on growth, non‐specific immune responses and disease resistance in juvenile rainbow trout, Oncorhynchus mykiss. Fish averaging 5.8 ± 0.8 g (mean ± SD) were fed one of the five experimental diets; one control (Cont), and four other diets were prepared by supplementing single probiotics 1 (Bacillus subtilis; SP₁, 0.5%), single probiotics 2 (Bacillus licheniformis; SP₂, 0.5%), multi‐probiotics (B. subtilis + B. licheniformis; MP, 0.5%) and oxytetracycline (OTC) at 5 g OTC kg^?1 diet. After 8 weeks of the feeding trial, weight gain and specific growth rate of fish fed SP₁, SP₂ and OTC diets were significantly higher than those of fish fed Cont diet (P < 0.05). Superoxide dismutase (SOD) and lysozyme activities of fish fed SP₁, SP₂ and MP diets were significantly higher than those of fish fed Cont diet (P < 0.05). There were no significant differences in SOD and lysozyme activities among fish fed SP₁, SP₂, MP and OTC diets. In challenge test with Aeromonas salmonicida for 15 days, fish fed SP₁, SP₂ and MP diets showed significantly higher cumulative survival rate than those of fish fed Cont diet (P < 0.05). However, there were no significant differences in cumulative survival rate among fish fed SP₁, SP₂, MP and OTC diets. Although there was a little advantage in fish fed MP diet in terms of non‐specific immune responses, single or multi‐probiotics are equally effective statistically. These results indicate that single or multi‐probiotics had equal beneficial effects as an antibiotic replacer on growth performance, non‐specific immune responses and disease resistance in juvenile rainbow trout.