Effect of combination of dietary Bacillus subtilis and trans‐cinnamic acid on innate immune responses and resistance of rainbow trout,Oncorhynchus mykiss to Yersinia ruckeri

The present study investigated the effects of combination of dietary Bacillus subtilis and trans‐cinnamic acid on serum biochemical parameters, innate immune responses and resistance of rainbow trout, Oncorhynchus mykiss to Yersinia ruckeri. Six experimental groups of fish with mean weights of 20.58 ± 0.35 g were used in the study. Five experimental groups of fish were fed diets containing Bacillus subtilis (10⁷ per gram) or a mix of the Bacillus subtilis (BS) and trans‐cinnamic acid (25 mg/kg‐25trcBS, 50 mg/kg‐50trcBS, 75 mg/kg‐75 trcBS, 150 mg/kg‐150 trcBS), whereas an additive‐free basal diet served as the control (Cont). In this study, an increase was observed in granulocyte percentage, respiratory burst activity, phagocytic activity, phagocytic index, myeloperoxidase activity and total antiprotease activity especially in fish fed with mix of the BS and trans‐cinnamic acid‐supplemented diets (p < .05). Moreover, at the end of the 20‐day challenge period the survival rates and antibody titre (p < .05), and relative per cent survival were higher in the BS group and all trcBS groups compared with control group. As a conclusion, the results in the present study show that feeding rainbow trout with diets containing a mix of B. subtilis and trans‐cinnamic acid over a 60‐day period might be sufficient for improving fish immune responses and disease resistance against Y. ruckeri.     

Effects of dietary supplementation of citrus by‐products fermented with a probiotic microbe on growth performance,innate immunity and disease resistance against Edwardsiella tarda in juvenile olive flounder,Paralichthys olivaceus (Temminck & Schlegel)

Two consecutive studies were conducted to evaluate the dietary supplementation of citrus by‐products (CB) fermented with probiotic bacteria on growth performance, feed utilization, innate immune responses and disease resistance of juvenile olive flounder. In Experiment I, five diets were formulated to contain 0% (control) or 3% four different CB fermented with Bacillus subtilis (BS), Enterococcus faecium (EF), Lactobacillus rhamnosus (LR) and L. plantarum (LP) (designated as CON, CBF‐BS, CBF‐EF, CBF‐LR and CBF‐LP, respectively). During 10 weeks of a feeding trial, growth performance and feed efficiency were not significantly different among all the fish groups. However, fish fed CBF containing diets had significantly higher survivals than the CON group. Disease resistance of fish against Edwardsiella tarda was increased by the fermentation of CB. In Experiment II, we chose the BS as a promising probiotic and formulated five diets to contain 0%, 2%, 4%, 6% and 8% CBF‐BS. Growth performance was not significantly affected by the CBF‐BS supplementation during 6 weeks of a feeding trial. Innate immunity of fish was significantly enhanced by CBF‐BS supplementation. Myeloperoxidase and lysozyme activities were increased in a dose‐dependent manner by dietary CBF‐BS inclusions. In a consecutive challenge test against E. tarda, an increased disease resistance was found by CBF‐BS supplementation. These studies indicate that the fermentation process of CB with probiotic has beneficial effects on innate immunity and thereby increases disease resistance of olive flounder against E. tarda. Bacillus subtilis can be used as a promising probiotic microbe for by‐product fermentation in fish feeds.     

Dietary Moringa oleferia leaf meal induce growth,innate immunity and cytokine expression in grass carp,Ctenopharyngodon idella

The present research was designed to investigate the growth promoting and immunostimulating properties of Moringa oleferia leaf meal (MLM) in grass carp. Juvenile grass carp (22.03 g ± 1.164) were fed with diets supplemented with 0, 50, 100 and 150 g/kg MLM for 48 days. At the end of feeding trial, skin mucus was used for analysis of lysozyme, protease, antiprotease and peroxidase activity. Head kidney was used for expression analysis of tumour necrosis factor‐alpha, interleukin‐8 and interferon‐γ. The obtained results showed that fish fed with 100 and 150 g/kg MLM had significant increase in weight gain and specific growth rate (p < .05). However, condition factor was not altered. The MLM (50 and 100 g/kg) inclusion resulted in higher mucus lysozyme and protease activity (p < .05), while peroxidase activity increased only in fish fed with 100 g/kg MLM and antiprotease activity was not altered. Expression of tnf‐α increased in a dose‐dependent manner, and significant (p < .05) increase was recorded in fish fed with 150 g/kg MLM. The expression of il‐8 and ifn‐γ increased in fish fed with 50 and 150 g/kg MLM; however, the increase was not significant (p > .05). In conclusion, supplementing juvenile grass carp feed with MLM up to 150 g/kg has growth promoting and immunostimulating effects.     

Effects of dietary supplementation of a marine thermotolerant bacterium,Bacillus paralicheniformis SO‐1, on growth performance and immune responses of Nile tilapia,Oreochromis niloticus

This study was carried out to evaluate the effects of dietary supplementation of thermotolerant bacterium on growth and immune responses of Nile tilapia (Oreochromis niloticus). Bacillus paralicheniformis SO‐1 was isolated from marine environments and incorporated into four isonitrogenous (300g/kg crude protein; cp) and isocaloric (18 MJ/kg) diets at four concentrations: 0, 5, 10 and 20 g/kg diet. Each diet was fed to triplicate groups of Nile tilapia (41.5 ± 0.5 g average weight) at a daily rate of 3% of their biomass, three times a day for 50 days. At the end of the feeding trial, the growth rates, feed utilization efficiency (feed conversion ratio, protein efficiency ratio, protein productive value), digestive enzymes (protease, amylase and lipase) activities, immunological response (serum lysozyme activity, phagocytic activity, respiratory burst and superoxide dismutase activity) and the expression of immune‐related genes [interleukin‐1 (IL‐1), interleukin‐4 (IL‐4) and interleukin‐12 (IL‐12)] were determined. Growth rates, digestive enzymes activities and immunological parameters were significantly improved (p < 0.05) with increasing supplemental SO‐1 up to 10 g/kg. However, further increase in bacterial concentration to 20 g/kg lead to significant decline in fish performance and immune response (p < 0.05). The expression of IL‐1, IL‐4 and IL‐12 genes was significantly up‐regulated (p < 0.05) in the liver of Nile tilapia fed SO‐1‐treated diets. This study clearly demonstrated that B. paralicheniformis SO‐1 could be considered as an efficient growth promoter and immune‐stimulating probiotic for farmed Nile tilapia.     

The effects of dietary Eucommia ulmoides Oliver on growth,feed utilization,antioxidant activity and immune responses of turbot (Scophthalmus maximus L.)

The present study was conducted to evaluate the effects of dietary Eucommia ulmoides (EU) on growth, feed utilization, antioxidant activity and immune responses of turbot fed a basal diet (CON) or EU‐supplemented diets with 5.0 g/kg (EU1), 10.0 g/kg (EU2) and 20.0 g/kg (EU3) EU leaf powder. After 70‐day trial, EU supplementation did not affect nutrient utilization, but reduced feed intake (FI) and specific growth rate (SGR) of fish at doses above 5.0 g/kg. Superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T‐AOC) activities in the EU‐supplemented groups were significantly higher than those in the control group at a dose of 20.0 g/kg. Significantly reduced malondialdehyde (MDA) contents were observed in EU‐supplemented groups at doses over 5.0 g/kg. Furthermore, fish fed 20.0 g/kg EU showed the highest lysozyme (LZM) activity among groups. The EU‐supplemented diets with doses above 5.0 g/kg significantly enhanced the mRNA expressions of cytokines. The expression level of major histocompatibility complex II alpha (MHC IIα) was significantly upregulated compared to that of the control fish when the supplemental level was at 20.0 g/kg. Taken together, the present study indicated that the EU could remarkably enhance the antioxidant activity, non‐specific immunity and maintain an active immune response in turbot.     

Clostridium butyricum as probiotic for promoting growth performance,feed utilization,gut health and microbiota community of tilapia (Oreochromis niloticus × O. aureus)

The feeding trial was conducted to evaluate the potentials of Clostridium butyricum in the diet of tilapia. Fish (~14 g) were fed with basal diet supplemented with 0 (Control), 0.5 (C‐1), 1 (C‐2), 2 (C‐3), 4 (C‐4) and 8 (C‐5) g/kg commercial probiotic‐containing C. butyricum (1.5 × 10⁸ CFU/g) for 8 weeks. The results showed that weight gain significantly increased, and feed conversion ratio decreased in the C‐2, C‐3 and C‐4 groups (p < .05). The protein retention (except C‐1 group), lipid retention and apparent digestibility coefficient (ADC) of dry matter in probiotic supplementation groups were significantly enhanced, and ADC of protein in the C‐4 group was also improved (p < .05). The supplementation of probiotic significantly increased villus height in anterior intestines and reduced the numbers of intestinal Escherichia coli (p < .05). High‐throughput sequencing showed that top three phyla namely Planctomycetes in all probiotic‐containing groups, Proteobacteria in the C‐1 and C‐2 groups and Chloroflexi in the C‐3 group had higher level than the NC group. The cumulative mortality was reduced by dietary probiotic after challenging with Aeromonas hydrophila (p < .05). In conclusion, C. butyricum can be supplemented at 1–2 g/kg feed for promoting the growth, feed utilization, gut health and microbiota of tilapia.     

Effect of polysaccharides extracts of algae Ulva rigida on growth,antioxidant, immune response and resistance of shrimp,Litopenaeus vannamei against Photobacterium damselae

This study was carried out to investigate the effect of water‐soluble polysaccharides extract of algae Ulva rigida (WPU) as dietary supplement on growth performance, antioxidant enzyme activity, lysozyme and phenoloxidase activity, and resistance of shrimp (Litopenaeus vannamei) subjected to bacterial infection with Photobacterium damselae. Three replicate groups of shrimp (1.0 g) were fed four diets containing four levels, 0 or control, 0.5, 1 and 1.5 g/kg of WPU for 8 weeks over the growth trial. Thereafter, 30 shrimps from each dietary treatment were infected with bacteria P. damselae to evaluate disease resistance of infected shrimp. The results of this study showed that WPU was effective as a growth promoter for L. vannamei. The best growth rate was observed in shrimp fed 1.5 g/kg of WPU diet. Regarding antioxidant defences, the diets supplemented with three levels of WPU stimulated glutathione peroxidase and catalase activates in experimental shrimps. MDA content of L. vannamei‐fed diet containing WPU 1.5 and WPU 1.0 was lower than WPU 0 and WPU 0. 5 diets. Also, lysozyme and phenoloxidase activities of shrimp receiving WPU at 1.0 and 1.5 level were significantly higher than those fed WPU 0 and WPU 0.5 diets. In addition, using WPU extract in all diets decreased mortality in L. vannamei in a dose‐dependent manner after challenge with P. damselae. These results suggest that incorporation of water‐soluble polysaccharides from green algae U. rigida at 1.5 g/kg doses improves growth and antioxidant activity and enhances the immune responses in shrimp L. vannamei.     

Supplementation of heat‐inactivated Bacillus clausii DE5 in diets for grouper,Epinephelus coioides,improves feed utilization,intestinal and systemic immune responses and not growth performance

In recent years, more and more attentions have been paid to the development and application of probiotics in aquaculture, and viable probiotics have been extensively studied, while rare information was available about inactivated probiotics in aquaculture. Therefore, in this study, a feeding trial was designed to investigate the effect of dietary supplementation of heat‐inactivated probiotic Bacillus clausii DE5 on growth performance, immune response and key immune genes expression in head kidney and intestine in grouper Epinephelus coioides. Fish were fed for 60 days with control diet (C) and two experimental diets containing 1.0 × 10⁸ CFU/g live (T1) and heat‐inactivated (T2) B. clausii DE5, respectively. The probiotic treatments did not affect the final weight, weight gain (WG) and specific growth rate (SGR) of E. coioides at days 30 and 60 (p > .05), while both heat‐inactivated and live B. clausii DE5 significantly decreased the feed intake and feed conversion ratio (FCR) at day 60 (p < .05). Serum lysozyme activity and complement C3 level in the two probiotic treatments were significantly higher than those in the control (p < .05). The lysozyme activity and complement C3 level at day 60 were significantly higher than those at day 30 (p < .05), while no significant interaction effect between diet and administration date was observed. Moreover, the heat‐inactivated B. clausii DE5 significantly improved the expression of TLR5, pro‐inflammatory cytokines (IL‐8 and IL‐1β) and TGF‐β1 in head kidney and intestine (p < .05), while the live probiotic did not show any significant effect on the expression of these key immune‐related genes in head kidney and intestine. These results indicate that dietary supplementation of heat‐inactivated B. clausii DE5 effectively improved feed utilization and both the local and systemic immune responses of E. coioides.     

Dietary Houttuynia cordata leaf extract and meal enhances the immunity and expression of immune genes in Labeo rohita (Hamilton, 1822)

A feeding trial was conducted to explore the effect of dietary Houttuynia cordata leaf extract (HCLE) and leaf meal (HCLM) on immunological responses and expression of interferon‐gamma (IFN‐γ) and tumour necrosis factor‐alpha (TNF‐α) gene in Labeo rohita fingerlings. Six isonitrogenous (350 g/kg CP) and isocaloric (17 MJ/kg DE) purified experimental diets were formulated with Houttuynia cordata leaf extract and leaf meal comprising control, C (0 g/kg HCLE and HCLM), E2.5 (2.5 g/kg HCLE), E5 (5 g/kg HCLE), E10 (10 g/kg HCLE), M10 (10 g/kg HCLM) and M20 (20 g/kg HCLM). Labeo rohita fingerlings (3.37 ± 0.23 g) were distributed in six experimental groups in triplicates following the complete random distribution. Fish were fed twice daily with respective experimental diets for a period of 60 days. A significantly (p < .05) lower lactate dehydrogenase, malate dehydrogenase, superoxide dismutase and catalase activities were registered in supplemented groups compared with control group, while respiratory burst and lysozyme activities were significantly (p < .05) higher in E10 group compared with other experimental groups. Haemoglobin, total leucocyte count, total erythrocyte count and haematocrit values were significantly (p < .05) higher in E10 group. The expression of IFN‐γ and TNF‐α in both the kidney and liver was significantly up‐regulated in leaf extract and meal supplemented groups with the highest expression in the fish of E10 group. Overall, these results suggest that the dietary supplementation of ethanolic extract of the Houttuynia cordata leaf at 10 g/kg level can enhance the immune response of L. rohita fingerlings.     

Effects of alternative dietary oils on immune response,expression of immune‐related genes and disease resistance in juvenile Nile tilapia,Oreochromis niloticus

The expression of immune‐related genes and immune responses to Aeromonas hydrophila were investigated on Oreochromis niloticus (6.07 ± 0.07 g), by feeding them six different diets for 8 weeks to apparent satiation. Diets contained fish oil (60g/kg FO), virgin coconut oil (60g/kg VCO) and corn oil (60g/kg CO) as sole lipids or blends of 30g/kg FO + 30g/kg VCO (3FVCO), 30g/kg FO + 30g/kg CO (3FCO) and 30g/kg VCO + 30g/kg CO (VO). Fish fed 3FCO recorded higher final weight, percentage weight gain (%WG) and specific growth rate (%SGR) but not significantly higher than all other groups. Triglyceride was higher in fish fed 3FCO than 3FVCO and CO (p ? 0.05), whereas total immunoglobulin (TIg) was not significant (p ? 0.05) between groups. Lysozyme activity was significantly higher in fish fed diet CO while groups FO, 3FCO and VCO recorded the least activities (p ? 0.05). Although alternative complement activity (ACH₅₀), complement proteins (C3 and C4), was not influenced, antibody titre production was significantly higher in fish fed diet 3FCO and lower in group CO. mRNA expression of IL‐1β was significantly upregulated in fish fed VO while the expression of C‐type lysozyme and TGF‐β was not significantly influenced across treatments, although group fed FO recorded higher expression levels, respectively. Lower mortalities of fish were recorded in groups fed 3FCO and VO after 14 days postchallenge with A. hydrophila disease indicating the enhancing effects of vegetable oils to boost immune response and resistance to disease. The study concludes that alternative lipid sources with high polyunsaturated fatty acids (PUFAs‐ALA and LA) (CO) and blend of saturated fatty acids (SFA)(VCO) can partially and or exclusively replace FO with an improved effect on tilapia and resistance to A. hydrophila in tilapia.     

Effects of dietary probiotic Lactobacillus plantarum and whey protein concentrate on the productive parameters,immunity response and susceptibility of Nile tilapia,Oreochromis niloticus (L.), to Aeromonas sobria infection

Immunostimulatory feed supplements have an increasingly interest in aquaculture management. Generally, an individual supplement was used in fish diets but it is expected that the use of multi‐supplements may show synergistic enhancements in fish performance, health, and immunity. Therefore, the present investigation was carried out to evaluate the use of dietary probiotic Lactobacillus plantarum and whey protein concentrate (WPC) in practical diets for Nile tilapia, Oreochromis niloticus. Hence, probiotic L. plantarum, WPC and their mixture were incorporated into a basal fish diet (300 g/kg crude protein) as follows: T1 = a basal control diet, T2 = a basal diet containing L. plantarum, T3 = a basal diet containing 1.0 g WCP/kg diet and T4, T5 or T6 = basal diets containing probiotic L. plantarum + 1.0, 2.0 or 3.0 g WCP/kg diet, respectively. Fish (15.2 ± 0.6 g) were fed on one of the tested diets up to apparent satiation twice a day for 60 days. After that, fish were intraperitoneally injected with pathogenic bacteria Aeromonas sobria and fish mortality was observed for 10 days postchallenge. Fish growth and feed intake were significantly improved by dietary probiotic L. plantarum (T2) and/or WPC (T3) over the control group (T1), and highest fish performance was observed in T5–T6 fish groups. Similarly, highest values of haematocrit, glucose, total proteins, albumin, and globulin were significantly observed in T5–T6 fish groups. Likewise, fish fed dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) showed antioxidants and immune‐stimulating activities better than the control group. Fish fed the control diet were more susceptible to A. sobria infection showing highest fish mortality (75.0%). Meanwhile, dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) enhanced significantly the fish resistance to A. sobria infection resulting in maximum values of relative percent of fish survival (73.3%–80.0%) in T5–T6 groups. The present investigation recommended the use of probiotic L. plantarum with 2.0 g WPC/kg diet to improve the growth, antioxidant, immunity responses and tolerance of Nile tilapia to A. sobria infection.     

Evaluating the effects of dietary resistant starch on growth,digestion, metabolism,immunity and resistance to ammonia stress in Litopenaeus vannamei

Resistant starch (RS) is considered to be a good alternative to antibiotics. A 56‐day feeding trial was followed by induction of acute ammonia stress to evaluate the effects of dietary RS on growth, digestion, metabolism, immunity and resistance to ammonia stress in Litopenaeus vannamei. The four diets used differed only in RS content: 0 g/kg (Control), 10 g/kg (RS1), 30 g/kg (RS2) and 50 g/kg (RS3). The results showed that dietary RS improved the growth and the survival rates of shrimp exposed to ammonia stress. At 56 days, the activity of digestive and metabolic enzymes (amylase, lipase, pepsin, hexokinase and pyruvate kinase) was increased in the three RS groups, while trypsin activity only increased in the RS1 and RS2 groups; immune‐related parameters (the total antioxidant capacity; the activity of superoxide dismutase, total nitric oxide synthase and phenoloxidase; and the expression of heat‐shock protein 70, thioredoxin, prophenoloxidase, lysozyme and toll gene) were increased in the three RS groups. After exposure to ammonia stress, all the selected immune parameters of the three RS groups were higher than those of the control group at 24 hr. Therefore, dietary RS improved the growth, digestion, metabolism, immunity and resistance to ammonia stress in L. vannamei.     

Effect of dietary supplementation with a synbiotic (Lacto Forte) on growth performance,haematological and histological profiles,the innate immune response and resistance to bacterial disease in Oreochromis niloticus

This study investigated the effects of a synbiotic Lacto Forte on growth performance, haemato‐immunological responses, plasma bactericidal capacity, histological profiles and resistance of Oreochromis niloticus to Pseudomonas fluorescens. The experimental fish were divided into three groups; two of them (T1 and T2) were given Lacto Forte incorporated diets at increasing level (0.7 and 1.5 g/kg, respectively) and an additive‐free basal diet served as the control (T0) for 30 and 45 days. At the end of the feeding trial, a challenge was performed using a virulent strain of P. fluorescens and mortalities were recorded over an additional 14‐days period. The results showed that Lacto Forte has a pronounced effect on haematological and growth performance parameters at 1.5 g/kg rather than 0.5 g/kg (p < 0.05). Plasma lysozyme, proteases, antiproteases and bactericidal capacity were significantly enhanced (p < 0.05) in Lacto Forte‐treated groups, particularly after 45 days of supplementation. Long‐term supplementation with Lacto Forte (1.5 g/kg) induced degenerative changes in the liver, spleen and intestine. Additionally, a significant increase (p < 0.05) in survival rates were found in Lacto Forte‐treated groups compared to the control one 14 days post‐challenge. As a result, Lacto Forte fortifies tilapia immune response and can be used as a surrogate for antibiotics to control P. fluorescens.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Dietary butyric acid improved growth,digestive enzyme activities and humoral immune parameters in Barramundi (Lates calcarifer)

A six‐week feeding trial was conducted to determine the effect of butyric acid (BA) inclusion in diet on performance of Barramundi (Lates calcarifer). Fish (12.0 ± 0.2 g) were fed with four experimental diets contained 0.0 (control), 2.5, 5.0 and 10.0 g BA/kg in triplicate. Fish fed on 5 and 10 g BA/kg diets had higher growth and total alkaline protease and lipase activities than the other treatments. Fillet protein content in BA‐supplemented groups was higher than the control. Liver catalase activity was highest in 2.5 g BA/kg group compared with the other groups. The values of liver superoxide dismutase activity and serum total protein concentration in 5 and 10 g BA/kg treatments were higher than those in the control (p < .05). Moreover, the highest and the lowest levels of serum lysozyme activity were noticed in the 10 g BA/kg and the control groups, respectively (p < .05). Also, the highest respiratory burst activity was observed in fish fed 5 g BA/kg feed. Supplementing diet with 2.5 or 5 g BA/kg resulted in higher serum haemolytic activity in fish compared with the other groups. The number of red and white blood cells increased in fish fed BA‐supplemented diets compared with the control (p < .05). In conclusion, the results of this study showed inclusion of BA at 5 g/kg diet in L. calcarifer juveniles improved growth and upgraded the general health condition by enhancing fish antioxidant enzyme activities and haemato‐immunological responses.     

Effects of replacing fishmeal with fermented and non‐fermented rapeseed meal on the growth,immune and antioxidant responses of red sea bream (Pagrus major)

The effect of rapeseed meal (RM) and Aspergillus oryzae fermented rapeseed meal (RM‐Koji) on red sea bream (Pagrus major) was examined. Three groups of fish (initial weight, 4.5 ± 0.02 g) were fed a basal diet (RM0) and two test diets where half of fishmeal was replaced by RM (RM50) and RM‐Koji (FRM50) for 56 days. The obtained results showed that fish fed RM0 and FRM50 exerted significantly higher growth performance, feed utilization and haemoglobin level but lower triglyceride and cholesterol than RM50 group (p < 0.05). Interestingly, except of antiprotease activity, all the immune parameters including lysozyme, respiratory burst (NBT) and bactericidal activities were significantly increased in fish fed RM0 and FRM50 diets compared to RM50 diet (p < 0.05). In addition, malondialdehyde and reactive oxygen metabolites were significantly reduced in RM0 and FRM50 groups over RM50 group (p < 0.05). The present results suggest that fermented RM induced better growth performance and immune responses than feeding red sea bream with non‐fermented RM and both RM and RM‐Koji improved the antioxidative status of fish, making RM‐Koji an interesting candidate as a functional feed for aquatic animals.     

Effects of Chinese herbal medicines mixture on growth performance digestive enzyme activity immune response of juvenile Japanese seabass,Lateolabrax japonicus

A single factorial experiment was conducted to investigate the effects of Chinese herbal medicines mixture (CHMM) on growth performance, digestive enzyme activity and immune response of Japanese seabass, Lateolabrax japonicus (initial weight 5.01 ± 0.32 g). The fish were fed diets containing six levels of CHMM (0, 4, 8, 12, 16 and 20 g/kg) for 4 weeks. The results showed that the weight gain rate and specific growth rate (SGR) enhanced significantly in fish fed diet containing 8 g/kg CHMM (p < .05), while the feed conversion ratio (FCR) in the 4 and 8 g/kg CHMM groups reduced significantly compared with the control (p < .05). The body crude protein levels in 8 and 16 g/kg groups were significantly higher than the control (p < .05). The pepsin, amylase and lipase activities elevated significantly in the stomach of fish fed 8 g/kg CHMM, while the erepsin and lipase in the intestine of fish in 12 and 16 g/kg groups were higher significantly than the control (p < .05). The lysozyme, alkaline phosphatase, acid phosphatase (ACP), total antioxidative capacity activities in serum of fish fed 12 g/kg CHMM were higher significantly than those in the control (p < .05), while the total superoxide dismutase (SOD), total antioxidative capacity, catalase, alkaline phosphatase (AKP) and ACP activities in hepatopancreas of fish in 12 g/kg group were all significantly higher than those in the control (p < .05). Regression analysis showed that the relationships between dietary CHMM levels and either FCR, SGR, erepsin, pepsin or lysozyme activities were best expressed by quadratic or cubic regression equations, and the optimal inclusion levels are 11.4, 10.7, 10.7, 8.4 and 10.5 g/kg for maximum FCR, SGR, erepsin, pepsin and lysozyme activities, respectively. Under the present experimental condition, the optimal supplementary level of CHMM in the diet of Japanese seabass is 8–12 g/kg.     

Cross‐effects of dietary probiotic supplementation and rearing temperature on growth performance,digestive enzyme activities,cumulative mortality and innate immune response in seabass (Dicentrarchus labrax)

Probiotic influence on fish immune response and digestive capacity is extensively discussed in aquaculture. In this experiment, a feeding trial was carried out for 100 days to evaluate the cross‐effects of probiotic supplementation and rearing temperature (17, 20 and 23°C) in juvenile seabass (Dicentrarchus labrax). The experimental diet was supplemented with a commercial probiotic blend (Biomin AquaStar Growout) at 3 g/kg diet (5.23 × 10⁸ CFU/kg diet), and tested against a non‐supplemented diet (control). Growth performance and innate immune responses were analysed at 70 and 100 days of feeding, whereas digestive enzyme activities were determined at 100 days of feeding. At the end of the feeding trial, fish were subjected to a handling stress and cumulative mortality was recorded. Digestive enzyme activities were influenced by temperature, with α‐amylase and lipase activities peaking at the higher temperature (23°C) and trypsin at the lower temperature (17°C). Immune parameters showed a significant temperature versus feeding duration effect, with complement system (ACH50) and peroxidase peaking at 70 and 100 days of feeding, respectively. Poststress cumulative mortality was higher at the lowest temperature (17°C), especially in fish fed the control diet. In conclusion, water temperature was the main variable affecting the studied parameters, whereas the dietary probiotic supplementation had influence on the chymotrypsin activity and survival rate in seabass reared at 17°C.     

Dietary supplements of guanosine improve the growth,non‐specific immunity of sea cucumber,Apostichopus japonicus Selenka,and its resistance against Vibrio splendidus

The growth response, non‐specific immune activities and disease resistance were measured in sea cucumber, Apostichopus japonicus Selenka (initial average weight 6.80 ± 0.10 g), when fed diets supplemented with graded levels of guanosine from the guanosine‐5’‐monophosphate disodium (GMP) at 0 (control), 0.3, 0.6 and 1.2 g/kg for 8 weeks. The results showed that GMP supplemented at 0.6 and 1.2 g/kg significantly enhanced the growth of sea cucumber. Sea cucumber fed a diet with 0.6 g/kg of GMP had significantly higher intracellular superoxide anion production, nitric oxide synthase activity, lysozyme activity and the total superoxide dismutase (T‐SOD) activity than those in control group (p < .05). Increased lysozyme activity and T‐SOD activity were also found in sea cucumber fed GMP at 1.2 g/kg. Moreover, there was significantly lower cumulative mortality after the disease challenge in sea cucumber fed the diets with 0.6 and 1.2 g/kg GMP than that in control and 0.3 g/kg GMP groups (p < .05), and no significant difference was observed between 0.6 and 1.2 g/kg GMP groups. These results suggested that feeding GMP at a dose of 0.6 g/kg could enhance growth, non‐specific immunity of sea cucumber as well as its resistance against Vibrio splendidus.     

The effects of Coriandrum sativum L. as feed additive on mucosal immune parameters,antioxidant defence and,immune‐related genes expression in zebrafish (Danio rerio)

This study investigates the effects of Coriander (C. sativum) on the growth, antioxidant, and immune‐associated genes and serum and mucosal immune parameters in zebrafish (D. rerio). The experimental fish were treated with 0 [control], 5, 10 and 20 g/kg coriander supplemented diets for 8 weeks. The results revealed that coriander remarkably increased mucosal immune parameters (the total Immunoglobulin, protease and lysozyme activity). The highest levels of the measured parameters were noticed in 20 g/kg CP treatment. Also, the zebrafish fed 20 g/kg coriander powder showed significantly higher expression gene for lysozyme and TNF‐alpha. The same results were noticed in case of IL‐1B gene expression. In case of sod gene expression there was no significant difference between treatments. However, regarding cat gene expression, significant difference was noticed between 20 g/kg CP treatment and other groups. In addition, no significant changes were observed between coriander fed zebrafish and control treatments regarding GH gene expression level, although IGF‐I remarkable up‐regulate in 20 g/kg coriander powder treatment compared other groups. In conclusion, it can be proposed that dietary Coriander powder can improve mucosal immune parameters and immune and antioxidant genes expression.