Volume 69, 2017

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    Effects of Dietary Phosphorus Levels on Growth Performance, Plasma Biochemical Parameters and Relative Gene Expression of Lipogenesis of Bighead Carp, Aristichthys nobilis
    (2017) Ji, K.; Liang, H.; Mi, H.; Mokrani, A.; Xie J.; Liu, B.; Ge X.; Ren, M.
    An 8-week feeding trial was conducted to investigate the effects of dietary phosphorus levels on growth performance, plasma biochemical parameters, and lipogenesis gene expression of bighead carp. The results showed that weight gain (WG) and specific growth rate (SGR) increased with increasing dietary phosphorus levels up to 1.12%, and after that decreased. Feed conversion ratio (FCR) showed a converse trend compared with WG. Whole body protein and lipid contents significantly increased and decreased with increasing dietary phosphorus levels, respectively (P<0.05), whereas moisture and ash contents were not significantly affected by the dietary phosphorus levels (P>0.05). The highest values of the hepatosomatic index (HSI), total protein, and albumin contents were observed with 1.12% dietary phosphorus supplementation (P<0.05). Glucose levels increased with dietary phosphorus up to the level 1.32% phosphorus supplementation, and then decreased. Serum total cholesterol, total triglyceride, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphates activity were not significantly affected by dietary phosphorus levels (P>0.05). Excess phosphorus levels (1.32% and 1.59%) significantly down-regulated the relative gene expression levels of sterol regulatory element binding protein (SREBP) -1 and fatty acid synthase (FAS) (P<0.05). Based on WG and FCR, the optimal dietary phosphorus level should be 1.16%, using quadratic regression analysis.
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    Intestinal fatty acid binding protein gene (I-FABP) in golden pompano Trachinotus ovatus (Linnaeus 1758) larvae: ontogenetic expression and response to water temperature and nutrition manipulation
    (2017) Lin, M.; Tang, X.; Qin, J.G.; Ma, Z.; Wei, W
    The gene for fatty acid binding proteins (I-FABP) in golden pompano Trachinotus ovatus larvae was cloned and analyzed from hatch to 18 days-post hatch (DPH). The I-FABP gene (GenBank accession: MF034871) of golden pompano is composed of 815 bp with an open reading frame of 399 bp, encoded in one amino acid with a molecular weight of 15.24 kDa. The predicted amino acid sequence of I-FABP genes from golden pompano showed high similarity and identity with Japanese sea bass Lateolabrax japonicus (97% and 87.9%, AOW69620.1). The highest tissue expression of I-FABP genes was found in the intestine, followed by the eye on 18 DPH. During the ontogenetic development, the expression of I-FABP genes remained at a low level during the first five days, and reached the highest level on 12 and 18 DPH. The expression of I-FABP genes was not significantly affected by environmental temperature on 12 DPH, but was significantly affected by the temperature on 18 DPH. Nutrition enhancement with algae containing high fatty acids significantly affected the expression of I-FABP genes. The highest expression was observed in the non-enriched treatment, but the lowest expression was in the Nannochloropsis feeding treatment. Results of the present study indicate that the expression of the I-FABP gene varies with environmental temperature and nutritional conditions during the ontogenetic development of golden pompano larvae. The expression of I-FABP genes may be potentially used as an indicator for assessing nutrient supply and functional development of the digestive system in fish larvae.
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    Isolation and Characterization of Aeromonas veronii from Ornamental Fish Species in China
    (2017) Song, Y.; Hu, X.; Lü, A.; Sun, J.; Yiksung, Y.; Pei, C.; Zhang, C.; Li, L
    Aeromonas veronii infection of fish has become a significant problem in aquaculture. In this study, pure bacterial cultures were isolated from diseased ornamental fish suffering high mortality rate in China. These fish included zebrafish (Danio rerio), goldfish (Carassius auratus), oscar (Astronotus ocellatus), parrotfish (Amphilophus spp.) and crucian carp (Cyprinus carpio koi). Using morphologic, physiological, and biochemical characteristics and 16S rRNA sequences analysis, nine isolates, namely strains ZG-1, ZG-2, DW-1, DW-2, KL-1, DT-116, LS-912, SJ-1 and SJ-2 were identified as A. veronii. A phylogenetic tree constructed on the basis of 16S rRNA sequences strongly indicated that the isolates were most closely related to the species A. veronii (98.43-100% similarities). The pathogenicity of the isolate was confirmed in zebrafish with median lethal dose (LD50) ranging between 1.15×106 CFU/mL and 3.94×108 CFU/mL. Antibiotic susceptibility tests showed that the isolated strains were all susceptible to cephalosporins and chloramphenicol. Furthermore, histopathology of zebrafish showed leukocyte infiltration of gill filaments, necrosis of the hepatic cell and glomerulus hemorrhage. These results will provide a scientific reference for the prevention, control, and understanding of the pathogenic mechanism of A. veronii infection in fish.
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    Stenotrophomonas maltophilia: an Emerging Pathogen of Ascites Disease in Farmed Yellow Catfish Pelteobagrus fulvidraco
    (2017) Haipeng, Cao H.; Guo, C.; An, J; .Lu, L.,; Yang, X.,; Yang, Y.
    Ascites disease causes significant economic losses in yellow catfish Pelteobagrus fulvidraco. Yet only scare information is reported on Stenotrophomonas maltophilia as a pathogen for yellow catfish. In this study, a virulent strain, temporarily named WY1, was isolated from diseased yellow catfish fry suffering from ascites disease, identified phenotypically and molecularly as S. maltophilia. A phylogenetic tree was constructed to examine isolate WY1 and compare it to other known isolates. In addition, isolate WY1 is apparently susceptible to aminoglycosides and tetracycline drugs for veterinary uses in aquaculture as revealed when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of S. maltophilia as a pathogen of ascites disease in farmed yellow catfish.
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    The Efficacy of Chamomile (Matricaria chamomilla l.) Oil as a Promising Anaesthetic Agent for Two Freshwater Aquarium Fish Species
    (2017) Can, E.; Kizak, V; Özçiçek, E; Sehaneyildiz, C
    The efficacy of anesthetic chamomile oil (from Matricaria chamomilla L.) was evaluated in two freshwater aquarium fish species, Electric Blue Hap (Sciaenochromis fryeri) and Yellow Princess (Labidochromis caeruleus). Fish were exposed to ten concentrations of anesthetic (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 ml/L). The optimal doses identified as 0.6 ml/L for deep anesthesia (A5) for both two species. The minimal sedative dose at the stage of loss of equilibrium (A3) was found to be 0.3 ml/L. The induction time generally decreased significantly with increasing concentrations of chamomile oil for all treatment groups. Recovery time tended to increase with increased chamomile oil at concentrations lower than 0.7 ml/L, but after this concentration it decreased. Chamomile oil proved to be effective as an anesthetic for both ornamental fish species. These findings suggest that chamomile oil is a promising anesthetic agent for aquaculture. However, further studies should be focused on species based investigations on the effect of temperature, transfer of fish, and their effect on antioxidant and oxidant status, in order to gather further information.
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    Six practical diets were formulated to contain 2.6 (the basal diet), 48.9, 95.5, 189.83, 382.4, 779.53 mg/kg vitamin C diet. After 8 weeks of feeding, growth performance, antioxidant status, and innate immunity of juvenile pufferfish were analyzed. Results showed that specific growth rate and protein efficiency ratio in fish fed diets supplemented with vitamin C were significantly higher than in fish fed the control diet. Dietary vitamin C significantly up-regulated the expression levels of growth hormone receptors and Insulin-like growth factor. Blood cell numbers and respiratory burst activity were enhanced in fish fed vitamin C diet. Serum alkaline phosphatase, glutamic-pyruvic transaminase, and glutamic-oxaloacetic transaminase activity were significantly influenced by the dietary vitamin C levels. Fish fed diets supplemented with vitamin C showed increased hepatic superoxide dismutase, glutathione peroxidase, and catalase activity, but decreased malondialdehyde activity. In addition, we found that dietary vitamin C can significantly up-regulate the expression levels of immune-related genes (HSP70, HSP90, BAFF, TNF-α and IL-6) in liver. These results indicate that dietary vitamin C can significantly influence growth performance, antioxidant status, and innate immunity of pufferfish.
    (2017) Cheng, C-H; Liang, H-Y.; Guo, Z-X.; Wang, A-L; Ye, C-X
    Six practical diets were formulated to contain 2.6 (the basal diet), 48.9, 95.5, 189.83, 382.4, 779.53 mg/kg vitamin C diet. After 8 weeks of feeding, growth performance, antioxidant status, and innate immunity of juvenile pufferfish were analyzed. Results showed that specific growth rate and protein efficiency ratio in fish fed diets supplemented with vitamin C were significantly higher than in fish fed the control diet. Dietary vitamin C significantly up-regulated the expression levels of growth hormone receptors and Insulin-like growth factor. Blood cell numbers and respiratory burst activity were enhanced in fish fed vitamin C diet. Serum alkaline phosphatase, glutamic-pyruvic transaminase, and glutamic-oxaloacetic transaminase activity were significantly influenced by the dietary vitamin C levels. Fish fed diets supplemented with vitamin C showed increased hepatic superoxide dismutase, glutathione peroxidase, and catalase activity, but decreased malondialdehyde activity. In addition, we found that dietary vitamin C can significantly up-regulate the expression levels of immune-related genes (HSP70, HSP90, BAFF, TNF-α and IL-6) in liver. These results indicate that dietary vitamin C can significantly influence growth performance, antioxidant status, and innate immunity of pufferfish.
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    Effects of Different Levels of Dietary Surfactin Supplementation on Intestinal Morphology, and Intestinal Microflora of Growth Retarded Marbled Eel Juveniles (Anguilla marmaorata)
    (2017) Zhai, S-W.; Chen, X-H.; Wang, M-H.
    This 70 day trial was conducted to investigate the effects of surfactin on intestinal morphology and intestinal microflora of growth retarded marbled eels (Anguilla marmorata). A total of six hundred and forty marbled eels at elver stage were randomly allocated to 4 treatment groups on the basis of body weight. There were 4 replicate tanks in each treatment group with 40 fish per tank. Four diets were formulated with four levels of dietary surfactin: 0, 25, 50, and 100 mg/kg, respectively. Fish were fed twice daily to apparent satiation for 70 days. Retarded marbled eels fed diets with surfactin supplementation had enhanced mucosa folds in their intestines (P<0.05). It seems that the quantity of mucosa folds increased with the increasing surfactin levels in the diet. Dietary surfactin supplementation decreased the E. coli population significantly (P<0.05), and increased the Lactobacillus population significantly (P<0.05), but had no effect on total bacterial population in intestines of marbled eels (P>0.05). Results of the present study indicate that surfactin improves intestinal function in retarded elvers of marbled eels.
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    Effects of Dietary Astaxanthin on Growth Performance, Hepatic Antioxidative Activity, hsp70, and HIF-1α Gene Expression of Juvenile Golden Pompano (Trachinotus ovatus)
    (2017) Xie, J-J; Chen, X.; Liu, Y-J; Tian, L-X; Xie, S-W; Niu, J.
    The present study was conducted to investigate the effects of different astaxanthin (AST) levels on growth performance, hepatic antioxidative activity, heat shock protein 70 (hsp70), and hypoxia-inducible factor-1 alpha (HIF-1α) gene expression of juvenile golden pompano. Fish (mean initial body weight 5.8±0.05g) were fed six isonitrogenous and isoenergetic diets (AST-0, AST-0.005, AST-0.01, AST-0.05, AST-0.1, AST-0.2) containing various supplemented levels of astaxanthin (0%, 0.005%, 0.01%, 0.05%, 0.1%, 0.2%, respectively) in triplicate for 8 weeks. Growth performance (final body weight, FBW; weight gain, WG), and survival of fish fed diets containing astaxanthin above 0.01% were significantly higher (P<0.05) than of fish fed AST-0 and AST-0.005 diets; feed conversion ratio (FCR) showed the opposite trend (P<0.05). Fish fed 0.01% astaxanthin diet showed the highest value of survival. Hepatic antioxidant status (total antioxidant status, TAS; superoxide dismutase, SOD; carbonyl protein content) of shrimp improved significantly when dietary astaxanthin was over 0.01%. Relative expression profiles of hepatic hsp 70 mRNA and HIF-1α mRNA increased with increased dietary astaxanthin levels. The relative expression profiles of hepatic hsp 70 mRNA and HIF-1α mRNA of shrimp fed diets containing astaxanthin above 0.01% were obviously higher than those of shrimp fed AST-0 and AST-0.005 diets. Linear regression analysis on WG and HIF-1a mRNA indicated that the optimum dietary AST levels for optimal growth and immunity of juvenile pompano were 0.011% and 0.013%, respectively.
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    Polyculture of Sea Cucumber Holothuria scabra with Pacific White Shrimp Litopenaeus vannamei
    (2017) Jiang, S.; Zhou, F.; Mo, X., Huang, J.; Yang, Q.,Y.
    An experimental study of polyculture of sea cucumber Holothuria scabra with Pacific white shrimp Litopenaeus vannamei was carried out in the laboratory. Results indicated that nutrient structure of the culture system was influenced significantly by the sea cucumber: the phosphate and nitrate concentrations were enhanced more obviously in the polyculture system (PS) than in the monoculture system (MS), but by contrast, the ammonium concentration remained low in the PS. The sulfide contents of the sediment were reduced in the PS to 10.32±1.85mg/kg, accounting for about 2/5 of that in the MS. The PS of sea cucumbers had positive effects on the growth and survival of shrimp, the specific growth rate of weight of shrimp in the PS was 2.89±0.63%/day and significantly higher than that of the MS (average 2.05±0.57%/d). Survival rate of the shrimp in PS was 79.3±22.9%, dramatically higher than that of the MS (average 64.0±17.5%). In the PS, the shrimp had no negative effect on the sea cucumbers who ingested and assimilated food residue in the sediment of the culture system with an assimilation efficiency of 42.06±10.62% for organic matter. PS of sea cucumber Holothuria scabra in the shrimp culture system had both environmental and economic benefits. This PS method could contribute to sustainable development of aquaculture in China
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    Shewanella putrefaciens: an emerging pathogen for farmed yellow catfish Pelteobagrus fulvidraco
    (2017) Yang, Yibin; Guo, Cheng; Cao, Haipeng; Lu, Liqun; Yang, Xianle
    Bacteriosis has caused significant economic losses in farmed yellow catfish Pelteobagrus fulvidraco. Information is limited on Shewanella putrefaciens as a pathogen for yellow catfish. In this study, a virulent strain, temporarily named Y2, was isolated from diseased yellow catfish, identified phenotypically and molecularly as S. putrefaciens. A phylogenetic tree was constructed to examine isolate Y2 and compare it to other known isolates. In addition, isolate Y2 is apparently susceptible to aminoglycosides and tetracycline drugs for veterinary use in aquaculture as revealed when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of S. putrefaciens as an emerging pathogen for cultured yellow catfish.
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    Dietary Protein Requirement of Juvenile Ide, Leuciscus idus in Relation to Growth Performance, Whole-body Composition and Plasma Parameters
    (2017) Ren, Mingchun; Ji, Ke; Liang, Hualiang; Ge, Xianping; Mi, Haifeng
    A 60-day feeding trial was conducted to determine the dietary protein requirements of juvenile ide, Leuciscus idus. Six iso-energetic experimental diets were formulated to contain graded protein levels ranging from 26.5% to 50.9% of dry diet. At the end of feeding trial, final weight (FW), weight gain (WG), and specific growth rate (SGR) increased significantly with increasing dietary protein levels up to 36.4%, and thereafter decreased with further increase of dietary protein levels (P<0.05). Feed conversion ratio (FCR) showed a converse trend (P<0.05). Hepatosomatic index and viscerosomatic index were negatively related to dietary protein levels (P<0.05). Increase of dietary protein levels significantly improved whole-body protein content and decreased lipid content (P<0.05). White blood cell counts, red blood cell, hemoglobin, and hematocrit, were independent of dietary protein levels (P>0.05). Plasma protein content was not significantly affected by dietary protein levels (P>0.05), while plasma triglyceride and glucose concentrations were decreased significantly with increasing dietary protein levels (P<0.05). The highest aspartic transaminase activity was observed in fish fed diet 26.5% protein, and the lowest value was observed in 36.4% protein group (P<0.05). Based on SGR and FCR, the dietary protein requirement of juvenile ide was determined to be 36.9%-37.7% of dry diet. Dietary methionine and lysine levels for optimal growth was calculated to be 0.83% and 2.25% of dry diet, respectively.
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    Effect of Dietary Soybean Lecithin and Cholesterol on Growth, Antioxidant Status and Fatty Acid Composition of Juvenile Swimming Crab, Portunus trituberculatus
    (2017) Sun, Peng; Jin, Min; Ding, Liyun; Lu, You; Yuan, Ye; Ma, Hongna; Zhoua, Qicun
    An 8-week feeding trial was conducted to evaluate the effects of dietary soybean lecithin and cholesterol levels on the growth, antioxidant status and fatty acid composition in the tissues of swimming crab (Portunus trituberculatus). Eight experimental diets were formulated to contain four levels of soybean lecithin (0, 10, 20 and 40 g kg-1 of diet) and two cholesterol levels (0 and 6 g kg-1 of diet). Each diet was randomly assigned to triplicate groups of 60 swimming crabs (approximately 3.70 ± 0.03 g). The highest weight gain (WG), specific growth rate (SGR) and molting frequency (MF) were observed with crabs fed the diet supplemented with 40 g kg-1 lecithin and 6 g kg-1 cholesterol. Crabs fed the diet without lecithin and cholesterol had a lower WG and SGR as compared to those fed the other diets. Cholesterol, triglyceride and glucose concentrations in the serum were significantly influenced by soybean lecithin and cholesterol levels. Crabs fed the diets containing 40 g kg-1 lecithin with or without cholesterol supplementation had lower malondialdehyde (MDA) in the hepatopancreas as compared to those fed the other diets. Moreover, glutathione peroxidase (GPx) and lysozyme activities in the hepatopancreas were significantly affected by the dietary soybean lecithin and cholesterol levels. Highly unsaturated fatty acids (HUFAs) in the muscles were not significantly influenced by the dietary soybean lecithin and cholesterol levels. The concentrations of total HUFA in hepatopancreas were significantly influenced by the dietary soybean lecithin and cholesterol levels. In conclusion, interaction between dietary soybean lecithin and cholesterol affects growth performance, feed utilization and fatty acids in the hepatopancreas, dietary soybean lecithin and cholesterol supplementation enhance lipid transportation and metabolism
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    Aeromonas hydrophila induces apoptosis in pufferfish, Takifugu obscurus
    (2017) Cheng, Chang-Hong; Guo, Zhi-Xun; Wang, An-Li
    Aeromonas hydrophila is a Gram-negative opportunistic pathogen causing motile aeromonad septicemia, which results in great economic losses in freshwater fish farming. In this study, we investigated the effect of A. hydrophila on apoptosis of pufferfish blood cells. Total blood cell count, reactive oxygen species (ROS) production, cytoplasmic free-Ca2+ (cf-Ca2+) concentration, nitric oxide (NO) production, apoptotic cell ratio and the transcription levels of caspase-3 in the pufferfish blood cells were determined after A. hydrophila infection. Results showed that A. hydrophila infection significantly depressed the total blood cell count, and significantly increased ROS production, cf-Ca2+ concentration, NO production and apoptotic cell ratio. The transcription levels of caspase-3 increased significantly after A. hydrophila infection. Taken together, our results suggest that A. hydrophila infection alters ROS, cf-Ca2+, NO levels, and active caspase-3, which lead to cell apoptosis.
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    Molecular Characterization and Possible Immune Function of Two Members of Interleukin Family from Trachinotus ovatus
    (2017) Zhu, Kecheng; Guo, Huayang; Zhang, Nan; Jiang, Shigui; Zhang, Dianchang
    Interleukins (ILs) are a group of cytokines which play a core regulatory role in the immune system. In the present study, two members of the IL family, IL7 and IL8, were detected in Trachinotus ovatus. IL7 and IL8 cDNAs of T. ovatus consist of a 492 bp and 300 bp ORF (open reading frame) encoding a polypeptide of 163 and 99 amino acids, respectively. Multiple sequence alignment revealed that IL7 and IL8 contain characteristic arrangements of several conserved cysteine residues, which in T. ovatus are in positions 20, 57, 67, 105, 140, 152 and 35, 37, 61, 78, respectively. The phylogenetic tree showed that all ILs fell into four categories. Moreover, IL7 and IL8 mRNA of T. ovatus were constitutively expressed at different levels in all examined tissues, except muscle. Transcripts of IL7 were mainly expressed in liver, intestine, kidney, stomach, and fin, while transcripts of IL8 were highly detected in the eye, liver, kidney, and intestine of healthy fish. After Photobacterium damselae innoculation, mRNA levels of IL7 were higher than IL8 in the spleen and intestine, however, mRNA expression levels of IL7 were lower than IL8 in kidney 3 h post-injection. These results suggest that the two IL molecules play an important role in the inflammatory response of T. ovatus.
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    Effects of Feeding Frequency and Ration Level on Growth Performance and Non-Specific Immunity of Juvenile Turbot (Scophthalmus maximus) at Different Growth Stages
    (2017) Zheng, Keke; Liang, Mengqing; Fang, Wei; Kon, Fanhua; Xu, Houguo
    Four growth trials were carried out to optimize a feeding regime for turbot in industrial aquaculture systems at 15±0.5°C. Six ration levels (50%, 60%, 70%, 80%, 90%, and 100%) of satiation were tested in trial I and five ration levels (60%, 70%, 80%, 90% and 100%) of satiation were tested in trial III. For optimal feeding frequency, turbot were fed to satiation for 1 meal/day, 2 meals/day, 3 meals/day in trial II, and 1 meal every other day, 1 meal/day, and 2 meals/day in trial IV. The average initial body weight of fish was 28.90±0.07g for trials I & II, and 181.75±1.05g for trials III & IV. Growth performance generally decreased and feed utilization increased with decreasing ration levels, while no significant differences were observed with small sized turbot fed to 80%, 90%, 100% levels of satiation, and with large sized turbot fed to 90% & 100% levels of satiation. There was no increase in size heterogeneity with decreasing ration levels. Ration levels significantly influenced water quality. There were no significant differences in growth and feed efficiency among turbot fed with different feeding frequencies. Feeding small size turbot once a day and large size turbot once every other day at a ration level of 80% satiation is suggested for better feed utilization and less waste output.
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    Dietary Probiotic Bacillus licheniformis TC22 Increases Growth, Immunity, and Disease Resistance, against Vibrio splendidus Infection in Juvenile Sea Cucumbers Apostichopus japonicus
    (2017) Zha, Yancui; Yuan, Lei; Li, Mingzhu; Wan, Junli; Wang, Yiyan; Sun, Hushan
    In this study we examined the effects of probiotic Bacillus licheniformis TC22 on growth, immunity, and disease resistance against Vibrio splendidus in juvenile sea cucumbers Apostichopus japonicus. For 30 days, sea cucumbers were fed diets with TC22 at 0 (control), 105, 107, and 109 CFU/g respectively. Results showed that dietary TC22 at 109 CFU/g significantly improved (P<0.05) growth of sea cucumbers. Dietary TC22 had no significant effects on total coelomocytes count, acid phosphatase activity, and superoxide dismutase activity in these animals (P>0.05). Dietary TC22 at 109 CFU/g significantly improved phagocytosis, and total nitric oxide synthase activity in sea cucumbers (P<0.05). Compared to the control, dietary TC22 had no significant effects on respiratory burst activity (P>0.05). Respiratory burst in sea cucumbers fed dietary TC22 at 109 CFU/g was significantly higher than those fed dietary TC22 at 107 CFU/g (P<0.05). Cumulative mortality after V. splendidus challenge decreased significantly in the sea cucumbers fed with TC22 at 109 CFU/g (P<0.05). The present study confirmed dietary B. licheniformis TC22 at 109 CFU/g could significantly improve immunity and disease resistance in juvenile A. japonicus.
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    Isolation and Characterization of Acinetobacter lwoffii from the Intestine of Grass Carp (Ctenopharyngodon idella)
    (2017) Lü, Aijun; Wei, Zhen; Hu, Xiucai; Sun, Jingfeng; Pei, Chao; Zhang, Chao; Li, Li; Li, AiLing
    Acinetobacter lwoffii infections are largely concentrated in mammals; very few reports are available for such infections in fish. In this study, a Gram-negative rod bacillus was isolated from the intestine of grass carp (Ctenopharyngodon idella), and designed as strain CY1. The isolated strain was then identified as A. lwoffii according to morphological, physiological, and biochemical properties, and 16S rDNA sequencing. The phylogenetic tree constructed on the basis of 16S rDNA sequences indicated that strain CY1 is most closely related to A. lwoffii, and has 98.08% similarity with type strain ATCC17925. Experimental infection assays were conducted, and a cumulative mortality rate of 75% was observed in grass carp. Antimicrobial susceptibility test showed that the isolated strain CY1 was highly susceptible to most antimicrobial agents tested, including aminoglycosides, β-lactams, and quinolones. To our knowledge, this is the first report on pathogenic A. lwoffii in grass carp.
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    Profitability Analysis of Monosex Tilapia Production under Three Culture Models in Hebei and Southern Coastal Provinces of China
    (2017) Safina, N.; Yongming, Y.; Andrew, S., Pei, S.; Yuan, Y.; Yunyun, D.
    The purpose of this study was to understand and compare profitability indices of tilapia production under monoculture, polyculture, and integrated culture models. The study covered a total of 47 tilapia farmers in Guangdong, Guangxi, Fujian, Hainan, Yunnan provinces in the southern coastal areas, and Hebei province in Northern China. The study focused on two objectives: (i) Socioeconomic and production characteristics that influence tilapia production; (ii) Profitability indices, and breakeven analysis of tilapia production using a structured questionnaire. All calculations for the 3 culture models in this study are based on 1mu (667m2 or 0.666 ha). The study found that all tilapia farms visited were owned by males. About 72.9% of the farmers were 30 to 50 years of age; 50% of the farmers had undergone vocational training. Tilapia farm production areas averaged 70.2mu (~4.7 ha) per farmer, and pond aquaculture accounted for 87.5% of their production. Tilapia production costs were an average of US$1168.4 (1 yuan=US$6.6). Positive Gross Margins (GM) and Net Incomes (NFI) were observed. Tilapia production was economically viable with positive Benefit Cost Ratio (BCR) of US$0.24 in monoculture, and US$0.15 in other culture models. Farmers with low yields, especially tilapia cultured in an integrated model were expected to sell fish at US$0.93per kilogram to recover invested capital within a single production season averaging 6 months. Positive Returns on Investment (ROI) of US$0.22-0.15/kg were observed in monoculture and polyculture respectively. In conclusion, the study found that for farmers to increase tilapia production profit margins, tilapia stocking densities need to increase, especially under integrated culture, and improvements are needed in fish feed utilization to reduce current feed conversion ratios (FCR). In order to boost sales, farmers must ensure production of quality fish, and seek alternative markets such as Africa.
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    Supplemental Effects of AAMC, an Anionic Alkali Mineral Complex, in Diets for Pacific White Shrimp (Litopenaeus vannamei)
    (2017) Bui, H.T.D.; Khosravi, S.; Lee, C.; Kim, M-G.; Lim, S-J.; Shin, C-H.; Yoo, B-W.; Soo, I.C.; Lee, K-J.
    A 6-week feeding trial was conducted to evaluate the effect of dietary supplementation of Anionic Alkali Mineral Complex (AAMC) on growth performance, feed utilization, innate immunity, and disease resistance of L. vannamei. Graded levels of AAMC solution were included in a basal diet; 0% (Control), 0.05%, 0.1%, 0.2% and 0.4%. Shrimp fed diets supplemented with 0.2% and 0.4% AAMC had the highest growth performance, and compared to the control treatment, final body weight and specific growth rates were significantly higher (P<0.05). Feed utilization also improved significantly with AAMC supplementation. Non-specific immune responses of shrimp were significantly affected by dietary supplementation of AAMC; total hemocyte count of shrimp fed 0.1% and 0.2% diets was significantly higher the control diet shrimp group. Phenoloxidase and lysozyme activity was significantly higher in shrimp fed 0.2% diet compared to the control diet group. Glutathione peroxidase activity was significantly enhanced with dietary supplementation of 0.1%–0.2% AAMC. In a challenge test with Vibrio harveyi, shrimp fed 0.2% AAMC disease resistance was significantly higher than in shrimp fed the control diet. Overall, the results indicate that dietary supplement of AAMC improved growth, diet utilization, innate immunity, and disease resistance of Pacific white shrimp and approximately 0.2% in diets appeared to be the optimum supplemental level.
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    Rapid and Sensitive Detection of Vibrio natriegens in Portunus trituberculatus with the Loop-Mediated Isothermal Amplification Test
    (2017) Bi, K.R.; Lu, Z.H.; Yan, B.L.; Gao, H.; Qianaa, J.
    In order to detect Vibrio natriegens in Portunus trituberculatus, a loop-mediated isothermal amplification (LAMP) method was developed and evaluated. In this study LAMP primers were designed to correspond to the gyrB gene sequences. With Bst DNA polymerase, the LAMP assay was completed within 100 min at 65 C in a water bath. Amplification products were observed directly with agar gel or with the naked eye after the addition of SYBR Green I. The sensitivity of the LAMP assay for the detection of V. natriegens is about 1.32×10-2 fg/mL DNA template, whereas using duplex PCR the detection of V. natriegens was possible up to 13.2 pg/mL DNA template. There were no cross-reactions with other Vibrio strains indicating a high specificity of the LAMP. The novel LAMP assay in this study can be used as a valuable, rapid, and sensitive detection tool for the detection of V. natriegens both in the laboratory and for use in commercial aquaculture