Black soldier fly pulp in the diet of golden pompano: Effect on growth performance, liver antioxidant and intestinal health.

Black soldier fly (Hermetia illucens) has been widely researched as a protein source for fish meal replacement in aquaculture, but few studies have focused on its potential as a feed additive for growth and immune enhancement. We conducted a 56-day culture experiment to determine the impact of feed addition of black soldier fly pulp (BSFP, with 86.2% small peptides in dry basis) on growth performance, plasma biochemistry, liver antioxidant levels, intestinal immunity, digestion and microbiota of juvenile golden pompano (Trachinotus ovatus, 5.63 ± 0.02 g). BSFP was added to the basal diet at 0%, 1%, 3%, 5%, 7% and 9% (named Control, BSFP-1, BSFP-3, BSFP-5, BSFP-7, BSFP-9), respectively. BSFP increased the weight gain rate, specific growth rate, protein efficiency ratio and reduced the feed conversion rate of juvenile T. ovatus, the optimal growth performance was reached at BSFP-1, after which a negative feedback phenomenon was observed. Low levels of BSFP upregulated the expression of hepatic antioxidant, intestinal tight junctions, anti-inflammatory related genes and enhanced antioxidant, immune and intestinal digestive enzyme activities, which simultaneously reduced hepatic malondialdehyde and plasma aspartate transaminase and alanine aminotransferase concentrations. However, at BSFP-7, catalase activity was significantly reduced, while NF-κB p65 and pro-inflammatory cytokines transcription was significantly enhanced (P < 0.05). The results suggest that high doses of BSFP addition may damage fish health by inhibiting small peptide uptake, decreasing the activity of antioxidant enzyme and activating the canonical NF-κB pathway. Conversely, low doses of BSFP enhanced intestinal tight junction protein transcription, digestive enzyme activity and immune performance, inhibited pathogenic microbiota, while enhancing liver antioxidant capacity, which was associated with activated Nrf2-Keap1 pathway and suppressed NF-κB pathway, showing its potential as a feed additive to aquafeeds.

Effects of dietary chitosan on the growth, health status and disease resistance of golden pompano (Trachinotus ovatus).

The effects of dietary chitosan (0, 2, 4, 6, 8 and 10 g/kg) on the growth, health condition and disease resistance of golden pompano Trachinotus ovatus were evaluated. Dietary chitosan significantly enhanced weight gain, with the highest observed in fish fed the 6 g/kg chitosan diet. This chitosan level significantly promoted gut health by increasing villus length, lipase and protease activities and intestinal barrier-related genes expression. Meanwhile, dietary 6 g/kg chitosan improved the inflammatory response and anti-oxidative capacity of fish by regulating the expression of genes involved in NF-κB pathway and Nrf2 pathway, respectively. Furthermore, after challenge with Vibrio harveyi for 2 weeks, the survival rate increased significantly when dietary chitosan level was 6 g/kg. Overall, our results indicate that 6 g/kg chitosan is the optimal dose for enhancing growth, health and disease resistance of fish, but excessive chitosan (10 g/kg) weakens its beneficial effects.

Rhizoma curcumae Longae ameliorates high dietary carbohydrate-induced hepatic oxidative stress, inflammation in golden pompano Trachinotus ovatus.

In general, starch, as a complex carbohydrate, is the most economical energy source in aquaculture for its relatively low cost. However, excessive dietary levels of carbohydrate result in pathological conditions. An 8-week feeding trial with CT (control diet, containing 21% carbohydrate), HC (a high-carbohydrate diet, containing 50% carbohydrate) and HCR (a HC diet supplemented with 0.015% Rhizoma curcumae Longae) was performed to investigate the protective effect of curcumin on high-carbohydrate-induced hepatic oxidative stress and intestine lesion in juvenile Trachinotus ovatus. In the current study, HC group significantly decreased WGR, SGR, plasma CAT activity, intestinal C4 levels, hepatic Nrf2, Keap1, Bach1, HO1, CAT, and GPX mRNA expression as well as ZO-1, Occludin, and Claudin-3, TGF-ß mRNA transcription levels, while the opposite was true for plasma AST activity, hepatic MDA contents, intestinal Claudin-15, NF-κB, IL-1ß, IL-6, and TNF-α mRNA expression. In contrast with the HC group, the HCR group significantly increased the activities of hepatic CAT, SOD, intestinal C3, C4, IgG and LZM levels, hepatic Nrf2, Bach1, CAT, and GPX mRNA expression as well as intestinal ZO-1, Occludin, Claudin-3, TGF-ß and IL-10 mRNA expression levels, but the opposite trend was found in plasma triglyceride content, hepatic lipid deposition, hepatic Keap1 mRNA level as well as intestinal NF-κB, IL-6. In conclusion, high-carbohydrate diet can cause detrimental effect on physiological health status in Trachinotus ovatus, while adding Rhizoma curcumae Longae can improve hepatic and intestinal health status via attenuating the oxidative stress, inflammation, and reducing lipid deposition.

Effects of dietary Astragalus polysaccharides on growth, health and resistance to Vibrio harveyi of Lates calcarifer.

It is generally accepted that Astragalus polysaccharides (APS) supplementation can makes beneficial effects to fish. However, the adverse effects of APS to fish remains poorly understood. In the present study, Asian seabass Lates calcarifer were studied to assess the influence of different doses of APS on growth, health and resistance to Vibrio harveyi. Results showed that supplemental APS with 0.10 to 0.20% significantly boosted the growth performance, the protease and lipase activities of L. calcarifer. Compared with control diet, the villus length of L. calcarifer fed with APS supplemented diets was significantly higher. L. calcarifer fed with APS supplementation diets also significantly facilitated the antioxidant capacity and immune function. Meanwhile, supplemental APS with 0.10 to 0.15% significantly promoted liver health by up-regulating the expression of anti-inflammatory cytokines and down-regulating the expression of pro-inflammatory cytokines. Furthermore, survival rate of L. calcarifer challenged with V. harveyi was higher in diets supplemented with APS compared to the control. However, 0.20% APS significantly hindered the growth performance and caused immunostimulatory fatigue in L. calcarifer compared to 0.10% APS. Taken together, the present study demonstrates that supplementation APS with 0.10% is the optimal level for promoting the growth performance, health and resistance to V. harveyi of L. calcarifer, while 0.20% APS exerts adverse effects on L. calcarifer. Our findings provide novel recommendations for the application of APS supplementation in farmed fish.

Effects of dietary leucine levels on intestinal antioxidant status and immune response for juvenile golden pompano (Trachinotus ovatus) involved in Nrf2 and NF-κB signaling pathway.

The aim of the study was to evaluate the effects of dietary leucine level on growth performance, intestinal antioxidant status and immune response involved in Nrf2 and NF-κB signaling pathway in juvenile golden pompano (Trachinotus ovatus). A total of 450 juvenile golden pompano (9.15 ± 0.04 g) were fed three isonitrogenous diets with graded leucine levels [1.25% (control), 2.77% and 5.84%] for 8 weeks. The results showed that, compared with the control group, the WG was significantly improved in fish fed with 2.77% of dietary leucine (P < 0.05), and the 5.84% dietary leucine group had a tendency to increase. Compared to control group, 5.84% dietary leucine group significantly decreased the moisture and ash contents of whole body (P < 0.05), meanwhile, 2.77% dietary leucine group significantly decreased moisture content of whole body, but significantly improved the whole body crude lipid content (P < 0.05). Compared with the control group, the ALP level was significantly improved in fish fed with 2.77% of dietary leucine (P < 0.05). Inversely, the AST and ALT activities were significantly decreased in fish fed with 2.77% dietary leucine level (P < 0.05). Compared with the control group, GPx, T-AOC, SOD activities in group of 2.77% dietary arginine level were significantly increased (P < 0.05). However, MDA level showed a reverse trend, which was significantly decreased in fish fed with 2.77% dietary leucine level (P < 0.05). 2.77% dietary leucine levels significantly increased the relative expressions of Nrf2, HO-1, Cu/Zn-SOD, Mn-SOD and CAT (P < 0.05). In contrast, the relative expression of Keap1 showed a converse trend. Compared with the control group, the relative expressions of NF-κB, TNF-α and IL1-ß were significantly lowered in fish fed with 2.77% of dietary leucine (P < 0.05). Additionally, 2.77% dietary leucine level significantly improved the relative expressions of TGF-ß and IL-10 (P < 0.05). The 2.77% dietary leucine level significantly increased the muscular thickness compared with 5.84% dietary leucine level (P < 0.05). Furthermore, compared with the control group, the villus height and goblet cell counts were significantly improved in fish fed with 2.77% of dietary leucine (P < 0.05). These results indicated that the optimum dietary leucine plays an important role in promoting growth, enhancing antioxidant and immunity to maintain the intestinal health status of juvenile golden pompano.

Nutrient release from fish cage aquaculture and mitigation strategies in Daya Bay, southern China.

Finfish cage culture is the most predominant form of mariculture. The rapid expansion of fish cage culture systems has raised concerns about their environmental impact, such as nutrient release. In this study, for the first time, we estimated the release of nitrogen (N) and phosphorus (P) from fish cage culture in Daya Bay, southern China, by constructing N and P budget models based on a mass balance principle. In addition, the contribution and importance of nutrients from fish culture and other nutrient sources, including submarine groundwater discharge, benthic sediments, local rivers, and atmospheric deposition were assessed. The annual amount of N and P released from fish cage culture was 205.6 metric tons (hereafter tons) of N and 39.2 tons of P, including 142.7 tons of dissolved inorganic nitrogen (DIN) and 15.1 tons of dissolved inorganic phosphorus (DIP). Among the analyzed nutrient sources, the contributions of DIN and DIP from fish culture were 7.0% and 2.7%, respectively. For cages consuming conventional trash fish, 142 kg of N and 26 kg of P were released into the environment per ton of fish products, much higher than the values (72 kg N and 17.3 kg P) for cages using formulated feed. In fish culture, the dissolved nutrients were more N rich, but the particulate nutrients were more P rich. The ratio of cage-derived N and P was 21.1, higher than the ratio of coastal seawater (27.1), indicating that cage culture may also impact the local nutrient forms around farming regions. Oyster cultivation and harvest removed 126.3 tons of N and 35.1 tons of P from of the bay. Replacing trash fish with formulated feed and co-culturing of nutrient extractive species (e.g., bivalves, macroalgae) and deposit-feeding species (e.g., sea cucumber) in fish culture zones can be efficient nutrient mitigation strategies.

The effects of dietary Lycium barbarum extract on growth performance, liver health and immune related genes expression in hybrid grouper (Epinephelus lanceolatus♂ × E. fuscoguttatus♀) fed high lipid diets.

Growth performance, hepatic morphology and antioxidant ability, and expressions of antioxidant, inflammatory and apoptosis related genes were investigated in hybrid grouper fed high lipid diets containing 0, 0.5, 1, 2 and 10 g kg-1Lycium barbarum extract (LBE) for 8-week feeding. The study showed that dietary LBE significantly increased weight gain rate (WGR) and specific growth rate (SGR) of fish (P < 0.05), the highest WGR and SGR were observed in fish fed 10.00 g kg-1 LBE diet. Dietary LBE improved liver morphology by decreasing hepatocyte necrosis and inflammatory cell infiltration induced by high lipid diets. Meanwhile, high lipid diets supplemented with 0.5-2 g kg-1 LBE improved hepatic antioxidant ability by increasing the expression of antioxidant genes (GPx and CAT) and decreasing Keap1 mRNA levels. Moreover, dietary supplementation with 0.50-2.00 g kg -1 LBE significantly decreased IL-8, caspase-3, caspase-8 and caspase-9 mRNA levels and significantly increased IL-10 and TGF-ß1 mRNA levels in the liver of fish fed high lipid diets. In conclusion, high lipid diets supplemented with LBE improved growth performance, feed utilization and liver health in hybrid groupers by increasing hepatic antioxidant enzymes activity and its genes expression, as well as inhibition of hepatic inflammatory response and apoptosis.

Effects of dietary Spirulina platensis on growth performance, hematological and serum biochemical parameters, hepatic antioxidant status, immune responses and disease resistance of Coral trout Plectropomus leopardus (Lacepede, 1802).

The present study investigated the effects of dietary Spirulina platensis supplementation on growth performance, hematological and serum biochemical parameters, hepatic antioxidant status, immune responses and resistance to the pathogen infection in Coral trout Plectropomus leopardus. The fish were fed for 8-week with diets containing different levels of S. platensis: 0% (C), 2% (SP2), 4% (SP4), 6% (SP6), 8% (SP8) and 10% (SP10) as treatment groups, followed by a Vibrio harveyi infection test for 14 d. The study indicated that dietary supplementation with Spirulina platensis could significantly improve growth performance, and the highest weight gain rate (WGR) and specific growth rate (SGR) were observed in group SP10 (P < .05). Red cell count (RBC), white cell count (WBC), hemoglobin (Hb) and total antioxidant capacity (T-AOC) in the S. platensis supplemented groups were significantly higher than those of group C (P < .05). However, the levels of cholesterol, triglyceride and malondialdehyde (MDA) contents, and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities decreased with the increasing of dietary S. platensis levels. Compared with group C, the lysozyme (LYZ) and respiratory burst activities (RBA), and immunoglobulin (Ig) and complement contents in group SP4, SP6, SP8 and SP10 increased significantly than those of group C respectively (P < .05). After challenge with V. harveyi, the survival rate in group SP4, SP6, SP8 and SP10 was significantly higher than that of group C, and the highest survival rate was in group SP10 (P < .05). These results indicated that P. leopardus fed a diet supplemented with S. platensis (especially at 10%) could significantly promote its growth performance, improve its hepatic antioxidant status, and enhance its immune ability and resistance to V. harveyi infection.

Effects of dietary dandelion extract on intestinal morphology, antioxidant status, immune function and physical barrier function of juvenile golden pompano Trachinotus ovatus.

Intestinal morphology, antioxidant status, immune function and tight junction proteins mRNA expression were examined in golden pompano (Trachinotus ovatus) that fed respectively six diets containing dandelion extracts (DE) at 0, 0.5, 1, 2, 4 and 10 g kg-1 after 8 weeks feeding. The study indicated that dietary DE significantly improved intestinal antioxidant abilities by increasing SOD, CAT, T-AOC activities and up-regulating intestinal cat, gpx mRNA levels, but by decreasing MDA content and down-regulating intestinal keap1 mRNA levels in golden pompano. Meanwhile, dietary DE improved intestinal morphology, suggesting that enhances intestinal digestion and absorption, by increasing muscle thickness, villus length, villus width and villus number in the foregut and hindgut; as well as villus number, villus width and muscle thickness in the midgut (P < .05). Dietary DE enhanced intestinal barrier function by increasing intestinal zo-1 and occludin mRNA levels, but by decreasing the mRNA levels of claudin-12 and claudin-15. Furthermore, dietary DE improved intestinal immunity via increasing goblet cells numbers and regulating expression of immune-related genes. In conclusion, dietary DE supplementation promoted intestine health by improving intestine morphology, immunity, antioxidant abilities and intestinal barrier in golden pompano.

Effects of dietary ginkgo biloba leaf extract on growth performance, plasma biochemical parameters, fish composition, immune responses, liver histology, and immune and apoptosis-related genes expression of hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀) fed high lipid diets.

For thousands of years, leaves from the Ginkgo biloba tree have been a common treatment in Chinese medicine. The present study was conducted to investigate the effects of dietary ginkgo biloba leaf extract (GBE) supplementation on growth performance, plasma biochemical parameters, fish composition, immune responses, liver histology, and immune and apoptosis-related genes expression of hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀) fed high lipid diets. A basal diet supplemented with GBE at 0, 0.50, 1.00, 2.00, 4.00 and 10.00 g kg-1 was fed to hybrid grouper for 8 weeks. The study indicated that dietary GBE did not improve growth performance and feed utilization but it reduced intraperitoneal fat rate. There were no significant differences in condition factor, viscerosomatic index, hepatosomatic index, spleen index, relative gut length, food intake, protein deposit rate and survival among all groups (P > 0.05). Dietary supplementation with 0.50-4.00 g GBE kg-1 diets effectively increased plasma HDL content and decreased plasma GLU, LDL and TG content in fish. Furthermore, dietary GBE had a significant effect on moisture, crude protein and lipid in the liver, and protein in the whole body of fish (P < 0.05). Dietary supplementation with 0.50-1.00 g GBE kg-1 diets effectively decreased occurrence rates of the hepatocyte swelling, hepatocyte vacuolization, and nuclei shifting to the cellular periphery cytoplasmic vacuolization, meanwhile hepatic antioxidant enzymes (SOD, CAT and T-AOC) activities significantly increased whereas MDA content significantly decreased in fish fed diets supplemented with GBE (P < 0.05). Moreover, dietary GBE up-regulated the expression of antioxidant genes (CAT, GPx and GR), immune-related genes (MHC2 and TLR3) and anti-inflammatory cytokines (IL-10 and TGF-ß1), while dietary supplementation with 0.50-4.00 g GBE kg-1 diets down-regulated apoptosis-related genes (p53, caspase-9, caspase-8 and caspase-3) expression in the head kidney of hybrid grouper. These results indicated that hybrid grouper fed diets supplemented with GBE did not improve growth performance and feed utilization but it had hypolipidemic effects, improved hepatic antioxidant status, maintained normal liver histology and preserved liver function, increased immune-related genes expression and decreased apoptosis-related genes expression in the head kidney of hybrid grouper.

Effects of dietary hawthorn extract on growth performance, immune responses, growth- and immune-related genes expression of juvenile golden pompano (Trachinotus ovatus) and its susceptibility to Vibrio harveyi infection.

The present study was conducted to investigate the effects of dietary hawthorn extract (HTE) supplementation on growth performance, immune responses, hepatic antioxidant abilities, growth- and immune-related and heat shock protein genes expression and resistance to the pathogen Vibrio harveyi in Trachinotus ovatus. A basal diet supplemented with HTE at 0 (Diet 1), 0.50 (Diet 2), 1.00 (Diet 3), 2.00 (Diet 4), 4.00 (Diet 5) and 10.00 (Diet 6) g kg-1 were fed to golden pompano for 8 weeks. The highest final body weight, weight gain rate, specific growth rate, feed efficiency ratio and protein efficiency rate were observed in fish fed Diet 2 (P < 0.05). Dietary HTE significantly increased plasma complement 3, complement 4 and immunoglobulin M content (P < 0.05). Hepatic antioxidant enzymes (SOD, T-AOC, CAT, GPx, GR) significantly increased (P < 0.05), whereas MDA content decreased first and then increased in fish fed HTE supplement. After challenge with Vibrio harveyi, significant higher post-challenge survival was observed in fish fed Diet 2 and Diet 3 than the control group (P < 0.05). Transcription levels of growth-related genes (IGF-I and IGF-II) were significantly up-regulated in fish fed HTE supplement (P < 0.05), whereas HSP70 and HSP90 mRNA levels were significantly down-regulated (P < 0.05). With respect to immune-related genes, such as tumour necrosis factor-alpha (TNF-α), interleukin-8 (IL-8) and inhibitor protein κBα (IκB-α), upregulation was observed in the liver of fish fed with the diet supplemented with HTE. In contrast, the expression of antioxidant enzyme genes (CAT, GPx, MnSOD and Keap1) and cytokines (IL-10, TGF-ß1 and TOR) was downregulated. These results indicated that golden pompano fed a diet supplemented with 0.50 g kg-1 HTE could significantly promote growth performance and growth-related genes expression, strengthen immunity, and improve hepatic antioxidative abilities and resistance to Vibrio harveyi infection.

Effects of dietary dandelion extracts on growth performance, body composition, plasma biochemical parameters, immune responses and disease resistance of juvenile golden pompano Trachinotus ovatus.

The present study was conducted to investigate the effects of dietary dandelion extracts (DE) supplementation on growth performance, feed utilization, body composition, plasma biochemical indices, immune responses, hepatic antioxidant abilities, and resistance to the pathogen Vibrio harveyi in Trachinotus ovatus. A basal diet supplemented with DE at 0, 0.50, 1.00, 2.00, 4.00 and 10.00 g kg-1 were fed to golden pompano for 8 weeks. The study indicated that dietary supplementation with DE could significantly improve final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed efficiency ratio (FER), feed intake (FI), protein efficiency ratio (PER) and protein deposit rate (PDR) (P < 0.05). The highest FBW, WGR, SGR, FI and PDR were observed in fish fed 1.00 g kg-1 dietary DE (P < 0.05). The highest FER and PER were recorded at 0.50 g kg-1 dietary DE (P < 0.05). Condition factor, viscerosomatic index, hepatosomatic index and survival were not significantly different among all groups. Fish fed 1.00 g kg-1 dietary DE showed significant increase in plasma total protein, complement 4 content and alkaline phosphatase, lysozyme, glutathione reductase (GSR) activity, but significant decrease in triglyceride, low density lipoprotein cholesterol, malondialdehyde (MDA) content and aspartate aminotransferase activities compared to the control group (P < 0.05). Hepatic antioxidant enzymes (SOD, T-AOC, CAT, GSH-Px, GSR) significantly increased whereas MDA content significantly decreased in fish fed 1.00 g kg-1 DE supplement (P < 0.05). After challenge with Vibrio harveyi, significant higher post-challenge survival was observed in fish fed DE supplement (P < 0.05). These results indicated that golden pompano fed a diet supplemented with DE (especially at 1.00 g kg-1 of fed supplement) could significantly promote its growth performance, feed utilization, body protein deposit, immune ability, hepatic and plasma antioxidative enzyme activities and improve its resistance to infection by Vibrio harveyi.

Effects of dietary soybean isoflavones on non-specific immune responses and hepatic antioxidant abilities and mRNA expression of two heat shock proteins (HSPs) in juvenile golden pompano Trachinotus ovatus under pH stress.

This study determined the effect of dietary soybean isoflavones on non-specific immunity and on mRNA expression of two HSPs in juvenile golden pompano Trachinotus ovatus under pH stress. Six diets were formulated to contain 0, 10, 20, 40, 60 and 80 mg/kg of soybean isoflavones. Each diet was fed to triplicate groups of fish in cylindrical tanks. After 56 days of feeding, 15 fish per tank were exposed to pH stress (pH ≈ 9.2) for 24 h. Serum total protein (TP), respiratory burst activity (RBA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP), lysozyme (LYZ), complement 3 (C3), complement 4 (C4), cortisol, hepatic total antioxidant capacity (T-AOC), superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT) and the relative mRNA expression of heat shock protein 70 (HSP70) and 90 (HSP90) were investigated. The results showed that after pH stress, serum TP, RBA, LYZ, C4, hepatic T-AOC and CAT levels were significantly reduced (P < 0.05) while serum ALT, hepatic MDA and HSP70 and HSP90 mRNA expression levels were significantly increased (P < 0.05). On the other hand, supplementation with soybean isoflavones significantly reduced levels of serum ALT (20, 40, 60 mg/kg soybean isoflavones groups) and hepatic MDA (40, 60 and 80 mg/kg soybean isoflavones groups). Supplemented groups had increased serum TP content (40 mg/kg soybean isoflavones groups), RBA (20 and 40 mg/kg soybean isoflavones groups), LYZ (40 and 60 mg/kg soybean isoflavones groups), C3(20, 40, 60 and 80 mg/kg soybean isoflavones groups), hepatic SOD activity (40, 60 and 80 mg/kg soybean isoflavones groups) as well as increased relative mRNA expression of hepatic HSP70 (40, 60 and 80 mg/kg soybean isoflavones groups) and HSP90 (40 and 60 mg/kg soybean isoflavones groups) (P < 0.05). These results indicate that ingestion of a basal diet supplemented with 40-60 mg/kg soybean isoflavones could enhance resistance against pH stress in T. Ovatus to some degree.

Effects of dietary chlorogenic acid on growth performance, antioxidant capacity of white shrimp Litopenaeus vannamei under normal condition and combined stress of low-salinity and nitrite.

An eight-week feeding trial followed by an acute combined stress test of low-salinity and nitrite were performed to evaluate effects of chlorogenic acid (CGA) on growth performance and antioxidant capacity of white shrimp Litopenaeus vannamei. Shrimp were randomly allocated in 12 tanks (30 shrimp per tank) and triplicate tanks were fed with a control diet or diets containing different levels of CGA (100, 200 and 400 mg kg(-1) feed) as treatment groups. Growth performance including weight gain (WG), biomass gain (BG), feed conversion ratio (FCR), and feed intake were determined after feeding for 56 days. Antioxidant capacity were evaluated by determining the activity of total antioxidant status (TAS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) as well as the gene expression of GSH-Px and CAT in the hepatopancreas of shrimp at the end of feeding trial and again at the end of the combined stress test. The results indicated that supplemention of CGA had no significant effects on the growth performance and the activities of TAS, SOD, GSH-Px and CAT in hepatopancreas of shrimp cultured under normal conditions for 56 days. However, compared with the control group, CGA (200, 400 mg kg(-1) feed) significantly improved the resistance of L. vannamei against the combined stress of low-salinity and nitrite, as indicated by the significant (P < 0.05) higher survival, higher activities of TAS, GSH-Px and CAT, as well as higher transcript levels of GPx and CAT gene in shrimp treated with CGA in the combined tress test. Our findings suggested that CGA possessed dual-modulatory effects on antioxidant capacity of L. vannamei and could be a potential feed additive that can enhance shrimp resistance against environmental stresses. The recommended application dosage is 200 mg kg(-1) and further studies are needed to clarify the action model of CGA efficiency.

The effects of dietary soybean isoflavones on growth, innate immune responses, hepatic antioxidant abilities and disease resistance of juvenile golden pompano Trachinotus ovatus.

The present study was conducted to investigate the effects of dietary soybean isoflavones (SI) supplementation on growth performance, innate immune responses, hepatic antioxidant abilities, heat shock protein 70 (HSP70) gene expression and resistance to the pathogen Vibrio harveyi in Trachinotus ovatus. A basal diet was supplemented with SI at 0, 10, 20, 40, 60, 80 mg kg(-1) feed for 8 weeks. Significantly maximum weight gain (WG) and specific growth rate (SGR) were observed in treatment with 40 mg kg(-1) SI supplement (P < 0.05). Feed conversion ratio (FCR), feeding rate (FR) and survival rate were not significantly different among treatments. Fish fed a diet with 40 mg kg(-1) SI showed significant increase in plasma total protein content, complement 3 content, lysozyme activity as well as respiratory burst activity, but decrease in alanine aminotransferase and aspartate aminotransferase activities (P < 0.05). Increased plasma alkaline phosphatase activity, hepatic total antioxidative capacity, catalase activity and superoxide dismutase activity were also noticed in fish fed SI at 40 or 60 mg kg(-1) (P < 0.05). On the contrary, the lowest hepatic malondialdehyde (MDA) content was observed in fish fed SI at 40 mg kg(-1) (P < 0.05). Compared with the control, the relative level of HSP70 mRNA in fish fed SI at 40-80 mg kg(-1) were significantly increased, respectively (P < 0.05). After challenge with V. harveyi, significant higher post-challenge survival was observed in fish fed diets with 40-80 mg kg(-1) SI supplement than that in control group (P < 0.05). These results indicated that dietary intake containing SI could enhance the immune ability of fish and improve its resistance to infection by V. harveyi. Especially supplementation with 40 mg kg(-1) SI to the fish for 8 weeks showed remarkable improvement in the growth, non-specific immune responses, hepatic antioxidant abilities and HSP70 gene expression.

Effect of guava leaves on growth and the non-specific immune response of Penaeus monodon.

Guava (Psidium guajava L.) leaf extracts have antiviral and antibacterial activity against shrimp pathogens such as yellow-head virus (YHV), white spot syndrome virus (WSSV), and Vibrio harveyi, which make it a potential water disinfectant for use in shrimp culture. In this study, the safety of guava leaf supplementation in shrimp was evaluated by studying its influence on growth and the non-specific immune response of Penaeus monodon. Six diets containing different levels of guava leaves (0% [basal diet], 0.025% [G1], 0.05% [G2], 0.1% [G3], 0.2% [G4], and 0.4% [G5]) were fed to groups of shrimp (1.576 ± 0.011 g body weight) in triplicate for 56 days. Growth performance (final body weight, WG, PWG, SGR) of shrimp fed guava leaf diets was significantly higher (P < 0.05) than that of shrimp fed on the basal diet. The G1 diet resulted in the highest body weight gain (308.44%), followed by the G2 (295.45%), G3 (283.05%), G5 (281.29%), G4 (276.11%), and finally the basal diet (214.58%). Survival of shrimp in the G1 diet group was higher than that of shrimp in the control and the other experimental groups; however, no statistical differences (P > 0.05) were found. Dietary supplementation with guava leaf improved the activities of prophenoloxidase (PO) and nitric oxide synthase (NOS) in serum, and of superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP), and lysozyme (LSZ) both in serum and hepatopancreas of shrimp. In the experimental groups, the activities of these enzymes followed a similar pattern of change; they increased initially at low levels of dietary supplementation and then decreased with increasing concentrations of dietary guava leaf. Serum PO and SOD activities in shrimp fed the G1 diet reached 7.50 U ml(-1) and 178.33 U ml(-1), respectively, with PO activity being significantly higher than in controls. In shrimp fed the G1 diet, SOD, ACP, and AKP activities in hepatopancreas were significantly higher than in the controls, reaching 57.32 U g(-1), 23.28 U g(-1), and 19.35 U g(-1) protein, respectively. The highest activities of serum ACP, AKP, LSZ, and of hepatopancreas LSZ, were observed in the G3 diet group. Total nitric oxide synthase (TNOS) activity was highest (64.80 U ml(-1)) in the G4 diet group, which was significantly higher than that observed in the control group. These results suggest that dietary guava leaf supplementation could enhance the growth performance and non-specific immune response of P. monodon. Therefore, guava leaf is considered safe for use as a water disinfectant in shrimp culture.

Dietary supplementation of honeysuckle improves the growth, survival and immunity of Penaeus monodon.

Two trials were conducted to determine the effects of honeysuckle on shrimp, Penaeus monodon, first on growth performance, secondly on the immune response of shrimp. In trial 1, shrimp (mean initial wet weight about 3.02 g) were fed with five diets containing 0% (basal diet), 0.1%, 0.2%, 0.4% and 0.8% honeysuckle in triplicate for 60 days. Growth performance (final body wet weight, FBW; weight gain, WG; biomass gain, BG) of shrimp fed honeysuckle diets were higher (P < 0.05) than that of shrimp fed the basal diet, shrimp fed 0.4% honeysuckle diet showed the highest value of growth performance. Shrimp fed 0.2% honeysuckle diet showed highest value of survival. The total antioxidant status (TAS) and glutathione peroxidase (GSH-Px) activity of shrimp fed 0.2%, 0.4% and 0.8% honeysuckle diets were higher (P < 0.05) than those of shrimp fed basal and 0.1% honeysuckle diets. Hepatopancreas malondialdehyde (MDA) of shrimp fed honeysuckle diets were lower (P < 0.05) than that of shrimp fed the basal diet. Total haemocyte count of shrimp fed the basal diet was lower (P < 0.05) than that of shrimp fed honeysuckle diets. Haemolymph clotting time of shrimp had the opposite trend with the total haemocyte count of shrimp. In trial 2, the shrimp were exposed to air during a simulated live transportation for 36 h after the rearing trial. The antioxidant responses were characterized by lower TAS and higher antioxidant enzyme activities (superoxide dismutase: SOD, GSH-Px) and higher oxidative stress level (MDA) in the hepatopancreas compared to levels found in trial 1. No mortalities were observed in any diet groups after 36 h of simulated live transportation. The glutathione (GSH) content and TAS of shrimp fed 0.2%, 0.4% and 0.8% honeysuckle diets were higher (P < 0.05) than those of shrimp fed the basal and 0.1% honeysuckle diets. The SOD activity of shrimp fed the basal diet was higher (P < 0.05) than that of shrimp fed honeysuckle diets. The GSH-Px activity of shrimp fed the basal diet was lower (P < 0.05) than that of shrimp fed 0.2%, 0.4% and 0.8% honeysuckle diets but without significant difference (P > 0.05) with shrimp fed 0.1% honeysuckle diet. Moreover, the oxidative stress level (MDA) recorded in the hepatopancreas with shrimp submitted to the honeysuckle diets were lower. In conclusion, results suggested that dietary intake containing honeysuckle could enhance the growth performance of P. monodon and improve its resistance to air exposure during simulated live transportation. Considering the effect of honeysuckle on both growth performance and survival of P. monodon, the level of honeysuckle supplemented in the diet should be between 0.2% and 0.4%.

Dietary values of astaxanthin and canthaxanthin in Penaeus monodon in the presence and absence of cholesterol supplementation: effect on growth, nutrient digestibility and tissue carotenoid composition.

Penaeus monodon (mean initial wet weight 1·19 (SE 0·01) g) were fed seven diets in triplicate: a control diet (D1) without carotenoids; three diets formulated to supply 0·1 % astaxanthin alone (D2), 0·2 % astaxanthin alone (D3), and a combination of 0·1 % astaxanthin and 1 % cholesterol (D4); three diets with 0·07 % canthaxanthin alone (D5), 0·13 % canthaxanthin alone (D6), and a combination of 0·07 % canthaxanthin and 1 % cholesterol (D7). Weight gain (WG, %), specific growth rate (SGR, %/d) and survival were chosen as parameters of shrimp growth performance. Total antioxidant status (TAS), superoxide dismutase (SOD), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were chosen as indices of shrimp plasma antioxidant capacity. Meanwhile, digestibility, retention efficiency and tissue carotenoids were also investigated to determine the additive effect of cholesterol on the efficiency of astaxanthin and canthaxanthin. After 74 d rearing, WG and SGR of shrimp fed D2-D4 and D7 were higher than those of shrimp fed D1 (P < 0·05). Shrimp fed D4 had the highest survival. The apparent digestibility coefficients (ADC) of astaxanthin in D2-D4 were higher than those of canthaxanthin in D5-D7 (P < 0·05). Although ADC of astaxanthin were quite high (>98 %) in D2-D4 and no differences were found among them (P>0·05), the carotenoid retention efficiencies in the whole body, muscle and shell (D2-D3 treatments) were considerably low; however, cholesterol supplementation significantly improved the carotenoid retention efficiencies in the whole body, muscle and shell (D4 treatment). Accordingly, the addition of cholesterol also significantly enhanced the carotenoid contents of tissues. Shrimp fed supplemented carotenoid diets (D2-D7) had higher TAS and lower SOD, ALT and AST than shrimp fed D1 (P < 0·05). A low dissolved oxygen stress test was conducted for 7 d after the rearing trial and shrimp survival was also compared among the treatments. The survival of shrimp fed the diets supplemented with astaxanthin or canthaxanthin was higher than that of shrimp fed D1 during the stress test (P < 0·05). In conclusion, all data suggested that astaxanthin was better than canthaxanthin as the dietary carotenoid source in the commercial diet of P. monodon, and the supplement of cholesterol could positively enhance the efficiency of astaxanthin and canthaxanthin.