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In this manuscript, three iso‐nitrogenous and iso‐lipidic diets containing 50, 150 and 250 g/kg of fishmeal (FM) were fed white shrimp Litopenaeus vannamei for 8 weeks. At the end of feeding, survival and percentage weight gain of shrimp were examined. Hepatopancreas and haemolymph were sampled, activities of superoxide dismutase (SOD) and catalase (CAT), nitric oxide (NO), glutathione (GSH) and malondialdehyde (MDA) levels in hepatopancreas, activities of SOD, CAT, acid phosphatase (ACP) and alkaline phosphatase (AKP), and NO, GSH, MDA in haemolymph were examined. Haemolymph was further subjected to GC‐MS analysis. Results indicated that no significant differences in survival rate and percentage weight gain were observed among three treatments. SOD activity and GSH levels in hepatopancreas, and CAT activity, AKP activity, GSH and MDA levels in haemolymph were significantly lower in shrimp fed 50 g/kg FM diet. GC‐MS analysis of haemolymph indicated that 81 metabolites were significantly altered in the three groups. Furthermore, 8 metabolism pathways were significantly influenced by dietary FM levels. In conclusion, dietary administration of 50 g/kg FM resulted in inhibition of antioxidant ability, and disordered the energy metabolism, one‐carbon metabolism and unsaturated fatty acid metabolism in shrimp.

An eight‐week feeding trial was conducted to evaluate the contribution of biofloc on dietary lipid requirement in whiteleg shrimp Litopenaeus vannamei. Five diets with graded levels of dietary lipid (45, 60, 90, 120 and 150 g/kg) were fed to juvenile shrimp. Final weight, weight gain and specific growth rate of shrimp fed diets with 60, 90 and 120 g/kg lipid levels were significantly higher than those of shrimp fed diets with lipid levels 45 and 150 g/kg (p

To evaluate the effects of dietary nano‐selenium (Nano‐Se) on antioxidant capacity and hypoxia tolerance of grass carp fed with high‐fat diet, experimental fishes were fed Nano‐Se supplemented diets at doses of 0 (Control), 0.3, 0.6, 0.9 and 1.2 mg/kg for 10 weeks. After feeding trial, a part of the fishes were exposed to hypoxia stress. Results showed that the survival ratio of grass carp significantly increased in 0.6 and 0.9 mg/kg Nano‐Se group, and the content of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) significantly decreased in 0.6–1.2 mg/kg Nano‐Se groups compared with the control group. In addition, dietary Nano‐Se significantly enhanced glutathione peroxidase (GPX) activity and reduced the malondialdehyde (MDA) content in fishes fed diets with 0.3 and 0.6 mg/kg Nano‐Se. Dietary Nano‐Se significantly elevated mRNA expression of GPX1 and catalase (CAT) by promoting the mRNA expression of NF‐E2‐related nuclear factor 2 (Nrf2) in the hepatopancreas. After hypoxia stress, the GPX and superoxide dismutase (SOD) activities were significantly enhanced, and the MDA content and mortality rate consequently decreased in fishes fed diets with 0.3 and 0.6 mg/kg Nano‐Se. In summary, these results suggested that optimal Nano‐Se in diet enhanced the antioxidant capacity and hypoxia tolerance of grass carp.

A feeding experiment was conducted to determine the optimum selenium requirement in juvenile Nile tilapia. Each of six purified diets with Se‐methionine levels at 0.05, 0.21, 0.41, 0.57, 0.79 and 1.00 mg/kg was assayed in triplicate with initial body weight of 3.00 ± 0.01 g for 8 weeks. The growth of fish was obviously increased when the dietary Se was less than 0.57 mg/kg diet and reached a plateau when the dietary Se was ≥0.57 mg/kg. Serum and hepatopancreatic glutathione peroxidase (GPx) activity increased markedly when the dietary Se was less than 0.57 mg/kg, but then decreased when the dietary Se was higher than 0.57 mg/kg. The malondialdehyde contents in hepatopancreas were significantly decreased when the dietary Se was higher than 0.79 mg/kg. No significant differences were observed in hepatopancreatic total antioxidant capability (T‐AOC) among the groups (p > .05). The results of this study indicated that Se addition as Se‐methionine was essential, while both the deficiency and excess levels of dietary Se would cause negative effects on growth or antioxidant capability in juvenile Nile tilapia. Based on broken‐line regression of WG and piecewise regression of liver GPx, the optimum requirement of Se for juvenile Nile tilapia is 0.57 mg/kg diet.

We evaluated the influence of different proportions of 5′‐inosine monophosphate (IMP) and 5′‐guanosine monophosphate (GMP) on growth, feed digestibility and activity of digestive enzymes of turbot Scophthalmus maximus. Weight gain and daily feed intake were significantly higher in S. maximus fed with IMP or GMP, in comparison with fish fed with neither IMP nor GMP. The growth of 0.05% IMP + 0.05% GMP group was the best, and the intestinal digestive function was improved. The addition of IMP and GMP to fish diets significantly increased the apparent feed digestibility coefficient of dry matter and protein, as well as intestinal protease activity. The highest intestinal protease activity was observed in fish fed with 1 g/kg IMP. However, the lipase activity in hepatopancreas decreased significantly after addition of nucleic acid. According to our results, the optimal level of dietary IMP is 1 g/kg, which is in line with most of the growth performance and feed digestibility.

A 120-day trial was conducted to assess the effects of dietary fish oil replacement with vegetable oils on growth, lipid metabolism and antioxidant capacity of subadult swimming crab Portunus trituberculatus. Five isonitrogenous and isolipidic diets were formulated to replace 0, 250, 500, 750 and 1000g/kg of fish oil with a mixture of soybean and rapeseed oil (defined as D1-D5), and each treatment had 30 replicate crabs. Dietary fish oil replacement had no significant effects on growth of the crabs, while the D3 had the highest hepatosomatic index and total lipids in hepatopancreas. The triglyceride and lipase activities in hepatopancreas increased significantly with increasing dietary fish oil replacement. The D4 had the highest levels of alkaline phosphatase (ALP) and acid phosphatase (ACP) in the hepatopancreas, as well as the haemolymph ALP, ACP and peroxidase. The highest levels of haemolymph total antioxidant capacity, catalase and malondialdehyde were detected in D1. Total n-3 polyunsaturated fatty acids levels in hepatopancreas decreased significantly with increasing dietary fish oil replacement. In conclusion, dietary fish oil replacement had no significant effects on growth of P. trituberculatus, and 500g/kg of fish oil replacement could improve antioxidant capacity, but excessive replacement level will enhance lipid accumulation and peroxidation in the hepatopancreas.

The present study was to determine the time-dependent alterations in growth performance, histomorphology, digestive enzymes activities and the genes expression related to target of rapamycin (TOR) signalling pathway involved in hepatopancreas and intestine of Litopenaeus vannamei at 3, 6, 12, 18, 24 and 30 days after Aflatoxin B1 (AFB1) challenge. The results manifested that AFB1 could induce a significant decrease in growth performance and visible variations of the hepatopancreas and intestine structures in shrimp. Meanwhile, the digestive enzymes activities and genes expression level were significantly lower in the experimental group than in the control group and showed a time-dependent decrease (p < 0.05). The expression levels of tor and s6k were significantly higher in the experimental group than in the control group from days 6 to 24 and showed a tendency to increase first and then decrease as a whole (p < 0.05). Meanwhile, we analysed candidate pathways involved in hepatopancreas and intestine of shrimp in metabolic response to AFB1. The mainly disturbed pathways related to metabolism in hepatopancreas were involved in pyrimidine, glycosylphosphatidylinositol, glycosaminoglycan, vitamin and amino acid biosynthesis and metabolism, while the mainly disturbed metabolic pathways in intestine were glycosaminoglycan, vitamin and amino acid biosynthesis and metabolism.

l‐carnitine (LC) is required for transporting long‐chain fatty acids into the mitochondria, where β‐oxidation takes place, and it works as an antioxidant molecule against reactive oxygen species. This study evaluated the effects of LC on the growth and antioxidant function of Amur minnow (Phoxinus lagowskii Dybowskii). Five isonitrogenous (380.4 g/kg) and isoenergetic (17.63 MJ/kg) diets were supplemented with five LC levels: control level (0 mg/kg) and treatment levels (50, 400, 750, or 1,100 mg/kg) were fed to fish (18.19 ± 0.56 g) for 120 days. The results showed that the growth performance of fish fed a diet containing 400 mg/kg of LC was significantly higher than that of the control and those fed other LC level treatments. Similarly, the 400 mg/kg treatment had the best feed efficiency. Further, the levels of total antioxidant capacity and total glutathione in the serum and hepatopancreas of fish fed a diet containing 750 mg/kg of LC were significantly increased; however, malondialdehyde levels were significantly reduced compared to those of the control group. The activities of antioxidant enzymes of 750 mg/kg treatments in the serum and hepatopancreas were significantly higher than those of the control group, including total superoxide dismutase, catalase, glutathione peroxidase and gamma‐glutamyl‐cysteine synthetase. Finally, 750 mg/kg treatment significantly upregulated the mRNA relative expression of antioxidant enzymes and nuclear factor erythroid‐2‐related factor 2 and inhibited the mRNA level of kelch‐like ECH‐associated protein 1 in the hepatopancreas. In conclusion, the dietary LC level of 400–750 mg/kg could improve the growth performance, feed utilization and antioxidant defense system of Amur minnow under the culture conditions.

A 56‐day feeding trial was carried out to evaluate the interactive effects of chemically synthesized astaxanthin (Ax) and cholesterol (CHO) on the performances of kuruma shrimp juveniles. Six experimental diets containing 2 levels of Ax (0 and 0.6 g/kg diet) and 3 levels of CHO (0, 6 and 20 g/kg diet) were formulated in 2 × 3 factorial design. The results indicated that the interactions between dietary CHO and Ax were not significant on survival, growth performances, body proximate analysis, immune response and freshwater stress test. Significantly, better pigmentation performances and Ax contents of different parts of juveniles (whole body, muscle, carapace and head) were observed in higher Ax (Ax₀.₆)‐supplemented groups. Meanwhile, interactions of dietary Ax and CHO were also found on colour reading parameters and whole‐body Ax contents. In addition, juveniles fed with the diet containing Ax at 0.6 g/kg diet in addition to CHO at 0, 6 and 20 g/kg diet showed better performances on digestive enzyme activities (protease, lipase and amylase) of hepatopancreas than 0 g Ax/kg diet supplemented with CHO at 0, 6 and 20 g/kg diet. It was concluded that dietary Ax and CHO functioned interactively.

This study was conducted to investigate the effects of dietary probiotic quorum sensing degrader Bacillus cereus on the growth performance, intestinal short‐chain fatty acid levels, antioxidant status and histopathological response of Macrobrachium rosenbergii against Aeromonas hydrophila. M. rosenbergii juveniles were fed with 10⁴ cfu/g probiotic B. cereus, while the control group was fed without B. cereus. After 28 days of feeding, growth performance was significantly higher (p 0.05) were observed for acetic acid or butyric acid levels. Dietary B. cereus supplementation significantly (p

We evaluated the effects of dietary vitamin E on the reproductive performance and antioxidant capacity of Macrobrachium nipponense female shrimp. Prawns were fed 0, 40, 80, 160, 320 or 640 mg vitamin E/kg diet for 60 days. The 80 mg/kg group had the highest weight gain and lowest feed conversion rates. And the highest spawning rates were observed in the 80 mg/kg group with no significant differences among the groups. The highest activities of lysozyme, acid phosphatase and alkaline phosphatase in hepatopancreas were obtained in the 160 mg/kg group. The activities of superoxide dismutase, catalase and glutathione peroxidase showed a decreasing trend in the hepatopancreas. The lowest content of malondialdehyde was obtained with 80 and 160 mg/kg vitamin E. Histological results showed that the number of restzellen cells in hepatopancreas and a number of follicular cells in ovaries increased with 160 mg/kg vitamin E. However, 640 mg/kg vitamin E resulted in damaged hepatopancreas tubules and oocytes. The highest vitellogenin and vitellogenin receptor gene expressions were observed with 160 mg/kg vitamin E. These results provide evidence that dietary vitamin E with 80 and 160 mg/kg plays a positive impact on reproductive performance and antioxidant capacity of female shrimp.

To determine the effects of linolenic acid (LNA, 18:3n‐3) in oriental river prawn (Macrobrachium nipponense), an 8‐week feeding experiment was conducted using six isonitrogenous and isoenergetic semi‐purified diets containing 0.07 g/kg (control), 7.3 g/kg, 16.6 g/kg, 20.2 g/kg, 27.3 g/kg and 36.3 g/kg LNA. The hepatopancreas lipid content decreased significantly when dietary LNA content was >20.2 g/kg. Fatty acid analysis revealed that the percentage of 18:3n‐3 in the hepatopancreas significantly increased with increasing dietary LNA levels, while 20:5n‐3, 22:5n‐3 and 22:6n‐3 levels in the hepatopancreas decreased in a curvilinear manner as dietary LNA increased. Additionally, qRT‐PCR results revealed that hepatopancreas mRNA expression of acetyl‐CoA carboxylase (ACC) decreased with increasing dietary LNA, while the greatest carnitine palmitoyl transferase‐1(CPT1) mRNA expression was observed in the 2.73 g/kg and 36.3 g/kg groups. Furthermore, hepatopancreas mRNA expression of acyl‐CoA delta‐9 desaturase (SCD) and fatty acyl elongase 6(elovl6) was downregulated when prawns fed the diets containing >20.2 g/kg LNA. These results indicate that dietary 18:3n‐3 could decrease lipid deposition through increased fatty acid β‐oxidation and modulated fatty acid synthesis, and alter fatty acid composition by regulating fatty acyl elongase and fatty acyl desaturase mRNA expression in the M. nipponense.

To investigate the effects of dietary bile acids (BA) on growth and metabolism of lipid in grass carp (Ctenopharyngodon idella, C. idella) at high dietary lipid level, a basal diet (50 g kg–¹ lipid, 5L group) was supplemented with 20 g kg–¹ soybean oil (70 g kg–¹ lipid, 7L group); then, 0.06 g/kg BA was added in 7L diet to form the third diet (7L+BA group). The 96 C. idella (69.86 ± 6.24 g) were divided into three groups (duplicate per group) and fed three diets, respectively, for 8 weeks, and then, growth and lipid metabolism were determined. Results showed that growth of fish in 7L+BA group was significantly higher than 5L and 7L groups. The lipid level in whole body, hepatopancreas and muscle of grass carp in 7L+BA group were significantly lower than 7L group. Relative expression of lipid catabolism genes in hepatopancreas and muscle of 7L+BA group was significantly higher than 5L group. The amount of microbiota in intestine of fish in 7L+BA group was significantly higher than the other two groups. The present results indicated that BA in 7L diet improved growth of fish by increasing protein synthesizing, decreasing lipid content in fish body and by regulating amount of microbiota in intestine of fish.

Mobilization patterns of energy reserves during starvation are highly variable among crustaceans, and understanding this process is useful to satisfy the nutritional requirements of cultured organisms. The aim of this study was to elucidate the mobilization patterns on early and advanced juveniles—first free stage and one-gram juveniles—of redclaw crayfish (Cherax quadricarinatus). A biochemical approach was used to analyse the organic carbon, total proteins, lipids and glycogen levels of the entire animal, and a histochemical approach was adopted to identify location of metabolites in the hepatopancreas and abdominal muscle. While starvation did not affect early juvenile protein levels, it showed a significant decrease in advanced juveniles. Histochemical analysis showed that lipid storage of hepatopancreas R cells was depleted near point of no return (PNR) and recovered after feeding. Glycogen storage was localized in the F cells of the hepatopancreas, and among muscle fibres of the abdomen, where after feeding, a pronounced accumulation was observed. Early and advanced juveniles of redclaw crayfish showed different patterns of consumption mainly related to the protein level, which was the most abundant reserve in advanced juveniles and the most consumed during starvation. Hepatopancreas R cells were confirmed as the principal lipid storage, whereas the abdominal muscle was the main glycogen storage. In crustacean aquaculture, the understanding of resistance to temporary feed deprivation is relevant to achieve an adequate feeding management, thereby avoiding the overfeeding and diminishing operating costs. Fil: Calvo, Natalia Soledad. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de la Reproducción y Crecimiento de Crustáceos Decápodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Stumpf, Liane. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de la Reproducción y Crecimiento de Crustáceos Decápodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina Fil: Cortés Jacinto, E.. Centro de Investigaciones Biológicas del Noroeste; México Fil: Castillo Díaz, Fernando. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de la Reproducción y Crecimiento de Crustáceos Decápodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lopez, Laura Susana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de la Reproducción y Crecimiento de Crustáceos Decápodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina

The effect of Streptomyces strains RL8 and N7 on the growth, survival and histological structure of the hepatopancreas of Litopenaeus vannamei was determined. Shrimp post-larvae of 0.02 ± 0.01 g were fed with diets supplemented with Streptomyces spp. RL8 and N7 at 108 CFU g⁻1 of feed for 30 days, followed by challenge with Vibrio parahaemolyticus. Toxicity was also assessed by recording the mortality associated with the use of 1-100 g/L of cell mass and 108-1010 CFU/g of feed of these strains in Artemia salina and L. vannamei, respectively. The group treated with Streptomyces sp. RL8 had significantly better weight gain (0.62 ± 0.18 g) and survival rates (84.44 ± 5.7%) after challenge, whereas the one fed with Streptomyces sp. N7 showed significantly higher survival rate (57.77 ± 6.8%) than the control group (0.55 ± 0.20 g and 11.11 ± 9.0%, respectively). The hepatopancreas of Streptomyces-fed shrimps showed better histological integrity with significantly lower degree of atrophy and necrotic tubules than their unfed counterpart. No toxicity associated with these strains was found. Consequently, they can be excellent probiotic candidates to improve the physiological status and prevent infectious diseases of cultured L. vannamei.

This study investigated the effect of starvation (78 days) and refeeding (33 days) on the oxidative stress [malondialdehyde (MDA)] and the non-enzymatic antioxidants [vitamin E (VE), vitamin C (VC), vitamin A (VA), beta carotene (βC) and reduced glutathione (GSH)] in the hepatopancreas, muscle and gill tissues of freshwater crayfish (Astacus leptodactylus). Crayfish were divided into three experimental groups: control (fed), starved (not fed) crayfish for 78 days and refeeding crayfish for 33 days after 78 days of starvation. The biochemical analysis of the tissues was conducted at 3, 18, 33, 48, 63 and 78 days of starvation and feeding and at 3, 18 and 33 days of refeeding. It was determined that crayfish can withstand starvation period of 78 days. In all of the periods, the MDA levels were significantly higher in the tissues of starved crayfish when compared with the control. The findings of this study demonstrate that starvation has a negative effect on the VE, VC, VA, βC and GSH levels in the crayfish. The measured parameters returned to control values after 33 days of the refeeding. Additionally, the starvation resulted in decreased levels of VE, VA and βC in the abdomen muscle of crayfish consumed by humans.

1H-NMR analysis of the hepatopancreas, muscle and haemolymph of Astacus leptodactylus after feeding with polyphenol-enriched diet is reported. 1H-NMR spectra of lipophilic extracts showed the presence of cholesterol, fatty acid residues, phospholipids and triglycerides. 1H-NMR spectra of aqueous extracts identified 35 metabolites in the hepatopancreas, 31 in the muscle and 22 in the haemolymph. A total of 20 metabolites (amino acids and their derivatives) were present in the hepatopancreas, the muscle and the haemolymph. A total of 10 metabolites were present in both the hepatopancreas and the muscle (five amino acids, 2-hydroxybutyrate, choline, myo-inositol, glycogen and uracil). 2-Hydroxyisobutyrate and creatine were present in both the hepatopancreas and the haemolymph. Phosphorylethanolamine, phosphocholine and fumarate were present only in the hepatopancreas and isoleucine only in the muscle. Statistical analysis showed that the percentage of weight gain was statistically higher in polyphenol-enriched diet groups compared to the control and that polyphenols had a stimulating effect on the general metabolism. No stress-related metabolites were higher in crayfish fed with polyphenol-enriched diet. Conversely, phosphatidylcholine, cholesterol and DHA, linked to resistance to environmental stress and diseases, were higher compared to the control diet. This study indicates that 1H-NMR is a useful tool to study the metabolomics in relation to diet differences.

An 8-week feeding trial was conducted to determine the dietary leucine requirement for juvenile swimming crabs reared in cement pools. Six isonitrogenous and isolipidic practical diets (430 g/kg crude protein and 70 g/kg crude lipid) were formulated to contain graded leucine levels which ranged from 16.7 to 26.7 g/kg (dry weight). Each diet was randomly assigned to triplicate groups of 60 juvenile swimming crabs (initial average weight 3.75 ± 0.12 g) that were stocked in rectangle plastic baskets. The results of the present study indicated that dietary leucine levels significantly influenced weight gain (WG) and specific growth ratio (SGR) (p .05). Total protein, cholesterol, triglyceride and glucose in serum were significantly affected by the dietary leucine levels. Aspartate aminotransferase (AST) and alanine aminotransferase activities in hemolymph, AST and superoxide dismutase activities in hepatopancreas were significantly affected by dietary leucine levels; moreover, crab fed the 16.7 g/kg leucine diet had higher malondialdehyde in hemolymph and hepatopancreas than those fed the other diets. Crab fed the diet containing 24.9 g/kg leucine had higher phenoloxidase activity in hemolymph than those fed the other diets. Based on two-slope broken-line model of SGR against dietary leucine levels, the optimal dietary leucine requirement for growth was estimated to be 22.1 g/kg of the dry diet (corresponding to 51.4 g/kg of dietary protein on a dry weight basis). In summary, findings of this study indicated that dietary leucine could improve growth performance and antioxidant status.

This study was conducted to investigate the effects of dietary protease on growth performance, feed utilization, whole-body proximate composition, nutrient digestibility, intestinal and hepatopancreas structure of juvenile Gibel carp, Carassius auratus gibelio (mean weight 8.08 ± 0.18 g). Six diets were prepared, including a positive control diet (dietary protein 350 g/kg, PC), one negative control diet (dietary protein 33 g/kg, NC) and four protease supplementations diets, which were 75, 150, 300 and 600 mg/kg protease NC diet. After 12 weeks of diet feeding in indoor recycle aquarium tanks, no significant difference (p > .05) was found on growth performance between fish fed diet with 75–600 mg/kg protease and the PC group. Compared with the fish fed the NC diet, the specific growth rate of fish fed 300 mg/kg protease increased significantly (p .05) by the dietary treatment. Serum alkaline phosphatase and albumin were significantly affected by dietary protease (p .05). Foregut muscular thickness was thinner (p .05) by the dietary treatments. Based on the regression analysis of weight gain rate, the optimal dietary inclusion level of protease was 400 mg/kg in the diet for juvenile Carassius auratus gibelio.

To investigate the effect of fermented meal mixture of silkworm pupae, rapeseed and wheat (FMM) on growth and health of juvenile mirror carp (Cyprinus carpio var. specularis), fish meal (FM) was replaced with FMM where FMM was increasingly added in the diets by 0, 40, 80, 120, 160 g kg−1 and FM decreased accordingly to form five isonitrogenous (365 g kg−1 crude protein) and isolipidic (60 g kg−1 crude lipid) diets, being FM, T1, T2, T3 and T4 groups. 270 mirror carp (9.70 ± 1.02 g) were randomly divided into five groups (each group having three replicates) and fed for 58 days. Following termination of the experiment, the fish growth, body composition and health status were analysed. Growth, feed utilization and crude lipid content were negatively correlated with FMM levels in the diet. Increasing the FMM levels led to decreased serum TG, total cholesterol, LDL-c, MDA and SOD, while GOT and GPT increased. Relative expression of TNF-α1 and IL-6 genes in hepatopancreas increased in the T3 and T4 groups and the spleen index showed significant differences in the T2 and T3 groups. In conclusion, 40 g kg−1 FMM can be included into diets of juvenile mirror carp, while 80–160 g kg−1 FMM inclusion adversely affects the growth and health status of the fish.

In aquaculture, exposure to stressful conditions and problems related to diseases often occur resulting in serious economic loss. The use of probiotics that control pathogens through different mechanisms, aiding digestion by exoenzyme supply and establishment of beneficial microflora in the digestive tract has got increased attention recently. Two different bacterial species Micrococcus MCCB 104 and Bacillus MCCB 101 were tested as probiotics for two cichlid species Etroplus suratensis and Oreochromis mossambicus. The strains were administered separately and together, at a rate of 103 CFU animal−1 day−1 for 28 days. The effects on digestive enzyme activity and growth were compared with those fed on control diet. FCR of E. suratensis was high in case of Bacillus alone as well as the mixed culture (Micrococcus and Bacillus together) than that of control. However, the SGR of E. suratensis was slightly lower than that of control during 14 days trial. SGR of both the treatments (Bacillus alone and mixed culture) was higher than that of the control on 28th day, and this might be due to the reason that specific duration is needed for the assimilation and conversion of nutrients into proteins. The intestinal digestive hydrolases of E. suratensis were profoundly enhanced mainly by Bacillus and mixed cultures. The hepatopancreatic versions of major digestive enzymes in E. suratensis were influenced variously by different probiotic treatments. The alpha-amylase activity of hepatopancreas has been elevated significantly by mixed culture during 14 days experiments while on 28 days trials both Bacillus and mixed culture showed an enhancing effect. During 14 days feeding trials, the intestinal lipase activity has been prominently enhanced by all probiotic treatments. It is found that, in O. mossambicus, both 14 days and 28 days feeding experiments, the pepsin as well as intestinal digestive enzymes such as amylase, total alkaline protease, lipase and their hepatopancreatic counter parts showed a significant elevation in their specific activity. Intestinal alpha-amylase and total alkaline proteases of O. mossambicus showed an increase in specific activities on both 14 days and 28 days feeding experiments with the Bacillus and Micrococcus combination. The hepatopancreatic enzymes were highly influenced by the Bacillus species in O. mossambicus. The results of this study suggest that live probiotic microorganisms such as Micrococcus MCCB 104 and Bacillus MCCB 101 may be incorporated while formulating the cost-effective, nutritionally balanced diet of E. suratensis and O. mossambicus for better growth performance and nutrient utilization.

This experiment was conducted to study the effects of different forms and levels of manganese (Mn) on the growth performance, antioxidant activities, tissue Mn content and cytosolic manganese superoxide dismutase (cMnSOD) gene expression of Litopenaeus vannamei. Treatments consisted of 0, 10, 20, 30, 40 and 60 mg Mn kg−1 from manganese sulphate (Mn-S) and manganese methionine (Mn-Met), providing the actual dietary value of 5.17, 15.62, 25.55, 34.22, 44.48 and 67.90 mg Mn kg−1 Mn-S, and 5.17, 15.71, 25.36, 35.86, 45.16 and 65.06 mg Mn kg−1 Mn-Met, respectively. Each diet was fed to triplicate groups of L. vannamei (initial body weight: 1.925 ± 0.002 g) in a recirculated fresh water rearing system for 8 weeks. Weight gain rate (WGR) increased in prawns provided with from 25.55 to 44.48 mg Mn kg−1 Mn-S and 15.71 to 45.16 mg Mn kg−1 Mn-Met and then declined above these levels. The lowest protein efficiency ratio (PER) and the highest feed conversion rate (FCR) were observed in prawns fed the control diet (P 0.05). Survival rate (SR) was not affected by the dietary treatments (P > 0.05). Total SOD and Mn-SOD activities were higher in the hepatopancreas of prawns fed with Mn-supplemented diets from 15.71 to 44.48 mg Mn kg−1 (P

An 8-week feeding trial followed by an acute combined stress of low-salinity and nitrite were designed to examine the effects of Rhodiola rosea on growth, body composition and antioxidant capacity of the white shrimp Litopenaeus vannamei. Shrimp (3.60 ± 0.03 g) were randomly allocated to 4 groups, with 3 replicates per group and 30 shrimp per replicate. The dietary groups were given as follows: control and diets containing R. rosea (300, 1000 and 3000 mg kg−1). Antioxidant capacity including total antioxidant status (TAS), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) as well as gene expression of GSH-Px and CAT in hepatopancreas of shrimp was analysed at the end of feeding trial and again during the combined stress. The results showed that supplemental R. rosea had no significant impacts on growth and whole body composition of shrimp. There was significant effect of R. rosea supplementation dose and times on the antioxidant status parameters of L. vannamei. R. rosea (3000 mg kg−1) significantly improved the resistance of L. vannamei against the combined stress of low-salinity and nitrite, as indicated by the significant higher activities of TAS, GSH-Px and CAT (P

Facilitative glucose transporter 1 (GLUT1) is a transporter protein for glucose transport via the plasma membrane of the cells to provide energy through carbohydrate metabolism. GLUT1 cDNA from Litopenaeus vannamei was obtained and analysed in this study. Full-length GLUT1 cDNA is 2062 bp long and contained a 1506-bp ORF encoding a 502 amino acid protein, a 270-bp 5′UTR and a 284-bp 3′UTR. When shrimp were under acute low salinity stress, the expression in hepatopancreas, muscle, gill and eyestalk was all up-regulated at 12 h (P

Two trials were conducted to evaluate the performance of Pacific white shrimp Litopenaeus vannamei offered diets containing various copper (Cu) levels from Cu hydroxychloride (Cu2(OH)3Cl) containing 58.81% copper in the clear water recirculating system. In both trials, the basal diet (360 g kg−1 protein, 80 g kg−1 lipid) containing approximately 10 mg Cu kg−1 was primarily comprised of fishmeal, soybean meal, corn protein concentrate and whole wheat. In trial 1, test diets were produced supplementing the basal diet with 5, 10, 20, 40 and 60 mg Cu kg−1 from Cu hydroxychloride. Four replicate groups of 15 shrimp per tank (initial weight 0.28 g) were offered diets in slight excess over 8 weeks. In trial 2, the basal diet was supplemented with 30, 90, 150, 210 and 270 mg Cu kg−1 from Cu hydroxychloride. Seven replicate groups of 15 shrimp per tank (initial weight 0.22 g) were offered feed in slight excess over 7 weeks. At the end of the two growth trials, no significant differences were observed in final biomass, final mean weight, percentage weight gain, feed conversion ratio (FCR) and survival. In trial 1, the Cu concentrations of the carapace, hepatopancreas and whole shrimp linearly increased with increasing dietary Cu supplements. In trial 2, polynomial regression of Cu concentrations of the carapace, hepatopancreas and whole shrimp against analysed dietary Cu content indicated that a plateau was reached at 215 mg analysed Cu kg−1. Results of this study indicate that there was no negative effect of high levels of Cu supplement with regard to growth and survival. Tissue levels generally increased up to around 200 mg Cu kg−1 diet and then decreased, possibly indicating a shift in physiology.

A 7-week growth trial was conducted to evaluate the effects of dietary soybean meal (SBM) on digestive enzyme activity of intestinal mucosa, mRNA levels of digestive enzymes in hepatopancreas, and the mid-intestinal and hepatopancreas histology of gibel carp CAS III (Carassius auratus gibelio). Four different growth phases of gibel carp (initial body weight: fry, 0.8 g; juvenile, 5.0 g; 1-year-old, 62.7 g; and broodstock, 135.6 g) were tested. Seven isonitrogenous and iso-energetic diets were formulated to contain different SBM replacement levels (0%, 20%, 40%, 60%, 80% and 100% of dietary fish meal protein), and another diet (SBMAA) contained all SBM protein and supplied crystalline amino acids. The results showed that the activities of mid-intestine trypsin, α-amylase and gamma glutamyl transpeptidase reduced with increased dietary SBM, while the chymotrypsin activity increased first and then decreased. The ultrastructures of intestinal epithelial cells and hepatopancreas cells in fry and broodstock fish were distinctly affected by 200 g kg-1 dietary SBM. Supplementation of dietary amino acid to the highest replacement groups was not sufficient to improve digestive and absorptive capacities and growth performance. Gibel carp may be adapted to dietary SBM through increase in gene expression of hepatopancreas digestive enzymes and has potential to utilize proceeded SBM as feedstuffs.

Six diets were formulated with vitamin B6 levels (2.6, 32.7, 54.8, 90.7, 119.6 and 247.4 mg kg−1, dry diet) to determine the requirement for juvenile Pacific white shrimp, Litopenaeus vannamei. Triplicate groups of 40 juvenile shrimp (approximately 1.0 g) were provided four times each day to apparent satiation (8 weeks). Weight gain (WG), specific growth rate, feeding efficiency, protein efficiency ratio (PER) and protein productive value of the shrimp were significantly influenced by the vitamin B6 levels. No significant differences in whole-body and muscle composition, except for dry matter and protein contents in whole body. Vitamin B6 concentration in the hepatopancreas significantly increased with the dietary vitamin B6 level increasing from 2.6 to 32.7 mg kg−1. High-density lipoprotein cholesterol in the haemolymph improved with the dietary vitamin B6 levels increasing from 2.6 to 90.7 mg kg−1 diet and no significant differences in low-density lipoprotein cholesterol, cholesterol, glucose and total protein concentrations. Aspartate aminotransferase, alanine aminotransferase, superoxide dismutase, catalase and lysozyme in the haemolymph were significantly influenced by dietary vitamin B6 levels. The optimal dietary vitamin B6 requirements estimated using a two-slope broken-line model based on WG and SGR and an exponential model based on the vitamin B6 concentration in the hepatopancreas were 110.39, 110.08 and 167.5 mg kg−1, respectively.

A 76-day feeding trial was carried out to evaluate the effects of Lysine and Methionine supplementation on growth and digestive capacity of grass carp (Ctenopharyngodon idella) fed plant protein diets using high-level canola meal (CM). Fish with initial average weight 103.9 ± 0.6 g were fed three extruded diets. Fish meal (FM) diet was formulated as the normal control with 40 g kg−1 FM and 300 g kg−1 CM; CM diet was prepared by replacing all FM with CM (total 340 g kg−1) without Lys or Met supplementation; CM supplement (CMS) diet was similar to CM diet but was supplemented with essential amino acids (EAA) to ensure the levels of Lys and Met similar to those in the FM diet. Feed intake, feed efficiency and specific growth rate of the grass carp fed CMS and FM diets were similar (P > 0.05), but higher than those of the grass carp fed CM diet (P

An 8-week feeding trial was conducted to evaluate the effects of dietary aflatoxin B1 (AFB1) on growth performance, haematological parameters and histological changes in juvenile Pacific white shrimp, Litopenaeus vannamei. Six practical diets (455 g kg-1 protein, 78 g kg-1 lipid) with different levels of AFB1 (0, 25, 50, 100, 500, 1000 μg kg−1) were formulated. Each diet was fed to triplicate groups of shrimps (initial weight: 0.52 g). The results showed that shrimp fed with control diet (0 μg kg−1 AFB1) had significant higher weight gain (WG) and specific growth rate (SGR) than other groups. However, there were no significant differences in feed efficiency (FE) or hepatosomatic index (HSI) among all groups. Compared to the control diet, AFB1 supplementation significantly changed the activities of shrimp serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total antioxidant capacity (T-AOC) and glutathione S-transferase (GST) and the content of cholesterol (CHO). Histological damages were identified in the hepatopancreas of shrimp when dietary AFB1 level was over 107.6 μg kg−1. Based on this study, it was concluded that the AFB1 level in Pacific white shrimp diet should be

To investigate the effects of niacin on growth, digestion and absorption capacity, and the potential mechanism for digestive and brush border enzyme activities, grass carp (Ctenopharyngodon idella) (256 ± 0.41 g) were fed diets containing 3.95 (basal diet group), 14.92, 24.98, 35.03, 44.97 and 55.01 mg niacin kg−1 diet for 8 weeks. Results indicated that percentage weight gain (PWG), feed intake and feed efficiency were the lowest in basal group (P

The aim of this study was to screen Bacillus strains from the guts of Scophthalmus maximus, Paralichthys olivacues, Epinephelus coioides and Clupanodon punctatus, for use as probiotics in aquaculture. Eight Bacillus strains were screened, and strain M001 was selected for probiotic study based on its antagonistic activity against multiple aquatic bacterial pathogens including Vibrio anguillarum, V.campbellii, V.vulnificus, V.parahamolyticus, Streptococcus sp. and Edwardsiella tarda. M001 was identified as B.amyloliquefaciens based on the biochemical tests and 16S rRNA gene analysis. In vitro experiments revealed that M001 was able to grow at a wider range of temperature, pH and salinity and was capable to use turbot mucus as nutrient for growth. Additionally, M001 isolate greatly inhibited the growth of V.anguillarum by producing antibacterial substances and was acid tolerance, non-antibiotic resistance and non-harmful. Thereafter, the potential probiotic effect of M001 was tested in turbot by dietary administration of M001 at a dose of 10(8)CFUg(-1) diet for 42days. No significant differences of weight gain, specific growth rate and feed ratio were found in the M001-diet group of fish compared with control fish, but which increased, respectively, by 5.5%, 4.7% and 7.0% after 42days of feeding. Several digestive enzyme activities were found to increase significantly in the M001-diet group, including protease and amylase activities in hepatopancreas, protease activity in intestine and lipase activity in stomach (P

The impact of dietary α-tocopherol on juvenile Chinese mitten crab Eriocheir sinensis was experimentally evaluated in a 10-week study. Crab were fed with nine diets including three levels of α-tocopherol (0, 100 and 300 mg kg−1 diet) and three levels of fish oil oxidation (fresh, moderate and high) in triplicates. Fresh and moderate oil oxidization enhanced weight gain, but moderate and high oil oxidization lowered survival and feed efficiency. The 100-mg α-tocopherol kg−1 diet resulted in higher hepatopancreas MDA than other α-tocopherol diets. High oil oxidization led to the lowest serum superoxide dismutase (SOD) and glutathione peroxidase (GPH-PX). The serum SOD and GPH-PX activities in crab fed 100 mg α-tocopherol were higher than in those fed other α-tocopherol diets. The diet without α-tocopherol addition lowered lysozyme and phenoloxidase (PO) activities compared to other α-tocopherol diets. Fresh fish oil diet increased PO activity compared to oxidized oils. High oil oxidization caused significantly more mortality than fresh or moderate oxidization after 7-d postchallenge with Aeromonas hydrophila. Supplementation with α-tocopherol significantly enhanced resistance to bacterial infection. This study indicates that α-tocopherol can protect lipid from peroxidation and enhance disease resistance.

The polysaccharide – fucoidan was extracted from brown seaweed Sargassum wightii and its antibacterial activity was screened by agar well diffusion method. The maximum zone of inhibition observed was 15.66 mm in 20 mg mL−1 concentration against Vibrio parahaemolyticus. The Minimum Inhibitory Concentration (MIC) of the fucoidan was 12 mg mL−1 against V. parahaemolyticus. The fucoidan was then enriched with Artemia nauplii at four different concentrations such as 100, 200, 300 and 400 mg L−1 for 12 h. The enriched Artemia nauplii were fed to Penaeus monodon post-larvae for 20 days and the growth performance was assessed. The weight gain and SGR of the control group were 0.2432 g and 15.78%, respectively. But, in experimental groups fed with fucoidan enriched Artemia nauplii, the weight gain and SGR were increased and were respectively ranged from 0.2602 to 0.3161 g and from 16.11 to 17.05%. The P. monodon post-larvae were challenged with V. parahaemolyticus for a period of 30 days showed a reduction in mortality percentage of experimental groups over the control group and it was ranged between 36.97 and 89.86%. During the challenge test, the V. parahaemolyticus load was also enumerated from the infected shrimp at every 10 day intervals. In the control group, the Vibrio load showed a linear increase in hepatopancreas and muscle tissues from 10th to 30th days of challenge test, whereas in the experimental groups, the Vibrio load established a declining trend with the advancement of challenged test.

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

A 56-day feeding trial was carried out to investigate the effect of dietary glutamate (Glu) supplementation on growth performance, digestive enzyme activities and intestinal antioxidant capacity of grass carp (Ctenopharyngodon idella). A total of 540 grass carp with average initial weight of 370 ± 3.8 g were fed three diets supplemented with 0, 8 and 16 g kg−1 Glu. The per cent weight gain, specific growth rate, feed conversion ratio, and protein and lipid productive value were significantly improved by dietary Glu supplementation. Feed intake, condition factor, visceral somatic index and perivisceral fat ratio were not significantly different between dietary groups. Hepatosomatic index, intestinal somatic index, intestine length index, intestine protein content, trypsin activity in hepatopancreas and intestine, lipase activity in proximal and mid-intestine (MI) and hepatopancreas, alkaline phosphatase and gamma-glutamyl transpeptidase activities in intestine, creatine kinase activities in the mid- and distal intestine, intestinal folds height in the proximal and MI were significantly increased with increased Glu. Malondialdehyde and protein carbonyl contents in the intestine decreased with increased Glu. Superoxide anion and hydroxyl radical scavenging ability, glutathione reducase, catalase and total superoxide dismutase activities, and glutathione content in the intestine were increased with increased Glu. These results suggested that dietary Glu supplementation increased intestinal antioxidant capacity, digestive and absorptive ability and improved fish growth.

This study was conducted to evaluate the effect of linseed oil (LO) replacing different levels of fish oil (FO) on growth, muscle fatty acid composition and metabolism of gift tilapia (Oreochromis niloticus) (mean initial weight 22 ± 0.5 g) in indoor recycle aquarium tanks for 8 weeks. Fish fed the diet with 50% of the oil as LO had higher final body weight (FWG), specific growth rate (SGR) and protein efficiency ratio (PER) than the other groups (P

A total of 1400 juvenile Jian carp (Cyprinus carpio var. Jian) (8.93 ± 0.03 g) were fed diets containing graded levels of vitamin K at 0.027 (basal diet), 1.52, 3.02, 4.51, 6.02 and 7.52 mg kg−1 diet for 60 days to investigate the effects of vitamin K on growth, enzyme activities and antioxidant capacity in the hepatopancreas and intestine. Percentage weight gain (PWG), feed intake and feed efficiency of fish were improved by vitamin K. Activities of trypsin, chymotrypsin, amylase and lipase in the intestine and hepatopancreas and Na+, K+-ATPase, creatine kinase, alkaline phosphatase and gamma-glutamyl transpeptidase in the intestine were increased by vitamin K. Malondialdehyde and protein carbonyl contents in the hepatopancreas and intestine were decreased with vitamin K supplements. Certain level of vitamin K increased antihydroxyl radical, antisuperoxide anion, superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase and glutathione reductase activities and glutathione contents in the hepatopancreas and intestine. Intestinal Lactobacillus, E. coli and Aeromonas were changed with vitamin K supplements. Together, these results indicate that vitamin K improved fish growth, digestive and absorptive ability, and anti-oxidant capacity. The dietary vitamin K requirement of juvenile Jian carp (8.93–73.7 g) based on PWG was 3.13 mg kg−1 diet.

Juvenile Litopenaeus vannamei were fed for 8 weeks with diets containing four ratios of protein to carbohydrate (CBH) at P26 : C30, P30 : C25, P34 : C19 and P38 : C14, respectively, at 3.0 g L−1 salinity. Shrimp weight gain of P34 : C19 group was the highest and differed from the shrimp fed the P26 : C30 or P30 : C25 diet. Shrimp fed the P26 : C30 diet obtained higher survival than those fed other diets. Shrimp fed the P34 : C19 diet contained the highest body protein and lipid, which were significantly higher than those fed the P38 : C14 diet. Shrimp fed the P30 : C25 diet had the highest haemolymph glucose content, which was significantly higher than those fed the P26 : C30 or P38 : C14 diet. Shrimp muscle glycogen of the P26 : C30 group was the highest. Hepatopancreas B-cell number of shrimp fed the P26 : C30 diet was lower than those fed other diets, and the R cell number was the highest in the shrimp fed the P30 : C25 diet. This study indicates that the protein-sparing effect by CBH occurred in the P30 : C25 and P34 : C19 groups because these proteins to CBH ratios can support normal growth. Within the range of basic energy demand, the high dietary CBH to protein ratio can improve L. vannamei survival at low salinity.