Volume 70, 2018

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https://hdl.handle.net/10524/57158

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Improved Sampling of Hemolymph and Screening of Anti-Coagulants of Hemocytes in the Snail Babylonia areolata
(2018) Di, Guilan; Zhu, Guorong; Li, Yanfei; Ke, Caihuan; Zhang, Zhaoxia
Our aim was to improve sampling of hemolymph from the snail Babylonia areolata in order to evaluate the physiological and immune capacities of hemocytes in aquaculture. We also identified appropriate types of hemolymph anti-coagulants for B. areolata. Hemolymph samples were collected using an improved foot plantaris puncture method. We screened five types of anti-coagulants from Penaeid shrimp (A), marine decapods (B), abalone (C), and oyster (D), as well as a home-made anti-coagulant (E), to act against Babylonia areolata hemocytes on the basis of cell death rate and hemocyte aggregation. We improved the former foot plantaris puncture method and identified the home-made anti-coagulant as the best anti-coagulant from the five which we tested.
Cyclopamine Induced Expression of Immune-related Genes in Rainbow trout (Oncorhynchus mykiss) Head Kidney Leukocytes
(2018) Sõnmev, A.Y.; Özdemir, R.C.; Bilen, S.; zdemit, Y.K.
This study investigated the effect of cyclopamine, a hedgehog signaling inhibitor, on immune-related gene expression in rainbow trout head kidney leukocytes in vitro. At 1h sampling time COX 2, IFN-2, TNF-α, C3, MHC-II, Il-1β, IL-12, IL-10, and IL-6 increased significantly in groups exposed to cyclopamine at 30 μg/ml. However, in groups exposed to 10 and 20 μg/ml cyclopamine, the expression of these genes decreased significantly. At 4h sampling time, levels of COX-2, IFN-1, IFN-2, TNF-α, TGF-β, IgT, and MHC-II in groups exposed to 20 μg/ml cyclopamine increased. At 8h sampling time, COX2, IFN-Reg, and TNF-α expression in groups exposed to 10 and 30 μg/ml cyclopamine increased significantly compared to those in the controls. Conversely the expression decreased significantly for almost all other genes. At 12h sampling time, almost all genes increased significantly in groups exposed to 10 μg/ml cyclopamine compared to those in the controls. Notably, after 24h, the gene expression in all groups significantly decreased compared to the controls. Our results suggest that the activation of cyclopamine can be a useful tool for the examination of immune-related gene expression in the rainbow trout.
Effects of Dietary Surfactin Supplementation on Growth Performance, Intestinal Digestive Enzymes Activities, and Hepatic Antioxidant Potential of American Eel (Anguilla rostrata) Elvers
(2018) Zhai, S-W.; Zhao, P-Y.; hi, Y; Chen, X-H.; Liang, Y,
The 70-day trial was conducted to investigate the effects of surfactin on growth performance, intestinal digestive enzymes activities, and hepatic antioxidant potential on American eel (Anguilla rostrata) at elver stage. Six hundred American eel elvers were randomly divided into five treatments with three replicates per group, 40 fish per replicate. Dietary surfactin levels of the five treatment groups were 0, 25, 50, 100, and 200 mg/kg, respectively. Final body weight, weight gain rate, and feed efficiency were significantly affected by surfactin supplementation (P<0.05). There were no significant differences in feeding rate and survival rate among all groups (P>0.05). Protease and lipase activity in the intestine were significantly increased by surfactin supplementation (P<0.05), and amylase activity was similar among all groups (P>0.05). Malondialdehyde level, total antioxidation capacity level, and activities of superoxide dismutase, and glutathione peroxidase in intestine of fish were significantly (P<0.05) affected. No significant differences in CAT activities were found among all groups (P>0.05). The results demonstrated that dietary 25 mg/kg surfactin supplementation improves growth performance, some digestive enzyme activities in the intestine, and hepatic antioxidant potential of American eel at elver stage.
Effects of Dietary Protein and Lipid Levels on Growth Performance, Feed Utilization and Biochemical Parameters of Barbless Carp (Cyprinus pellegrini)
(2018) Zhang, J.; Zhang, X.; Wan, H.; Chen, L.; Lin, B.; Li, G.; Wang, Q.D.
An 8-week feeding trial was conducted to evaluate the effects of varying dietary protein (35%, 40%, 45%) and lipid (4%, 8%, 12%) levels with protein to energy (P/E) ratios ranging from 17.04 to 23.58 g protein/MJ on growth performance, feed utilization, and biochemical parameters of barbless carp (Cyprinus pellegrini). Fish fed diets with 40% protein exhibited higher thermal growth coefficient (TGC) and energy retention compared with fish fed the diets with 35% protein, higher protein efficiency ratio (PER), and protein retention, compared with fish fed diets with 35% and 45% protein. TGC and energy retention were significantly lower in fish fed the diets with 4% lipid compared to fish fed diets with 8% and 12% lipid. Fish fed the diet with 40% protein and 12% lipid had similar TGC as those fed the diets containing 8% and 12% lipid with 45% protein, but showed relatively better PER. Further, fish fed the diet with 40% protein and 12% lipid exhibited relatively lower plasma γ-glutamyl transferase, aspartate aminotransferase, and alanine aminotransferase activities, and total protein and blood urea nitrogen contents compared with fish fed the other diets. These results indicate that a diet containing 40% protein and 12% lipid with P/E of 19.38 g protein/MJ would be suitable for growth and health of barbless carp.
The Effects of High Temperatures on Survival Rates and Immunity of Saltwater Clam Meretrix meretrix from Different Geographical Populations
(2018) Chen, S.H.; Chen, A.H.; Wu, Y.P.; Zhang, Y.; Cao, Y.
High temperature has significant effects on the survival and immunity of organisms. In order to conduct a detailed investigation into the response of the saltwater clam Meretrix meretrix from different geographical populations (GuangXi, JiangSu, ShanDong, LiaoNing) to high temperatures, we examined the survival rates and antioxidant enzyme activities of these clams that were exposed to different temperature treatments (25°C, 35°C, 37.5°C, 40°C). Results showed that the survival rate of clams from GuangXi was highest at 40°C, followed by JiangSu. SOD and CAT activities of all the clams increased with the increasing temperatures, and then gradually decreased at 40°C over time. The expression levels of Hsp70 of M. meretrix from four populations were analyzed by qPCR sampled from the hepatopancreas after 72 h under different temperatures. Higher Hsp mRNA expression of GuangXi at 40°C indicated that clams of GuangXi have stronger high temperature resistance than those of the other geographical populations. Our findings provide a basis for the choice of cultured clams with a high temperature tolerance.
Effect of Psidium guajava and Phyllanthus acidus Leaf Extract on Immunostimulant Response of Nile Tilapia Against Streptococcus agalactiae Infection
(2018) Kamble, M.T.; Yakupitiyage, A.; Salin, K.R.; Chavan, B.R.
A study was conducted to investigate the efficacy of diets supplemented with aqueous extract of plants consisting of leaf-extracts of Psidium guajava (PGLE), Phyllanthus acidus (PALE), and the mixture of PGLE and PALE at the rates of 5 and 10 g/kg in the feed of Nile tilapia Oreochromis niloticus. Following 12 weeks of feeding, the fish were challenged with Streptococcus agalactiae for 15 days. Immuno-hematological parameters were measured before and after the challenge. Results showed significantly enhanced innate immune parameters after administration of the plant extracts. Respiratory burst activity, phagocytic assay, and serum lysozyme content were 2 to 3 times higher than that of the control treatment; PGLE-10 group showed the highest values, while fish fed PGLE-10 had the highest post-challenge WBC, RBC, Hb, and Hct values compared to the control. Survival rates were higher in the groups with dietary supplementation of plant extracts compared to the control. The positive immuno-hematological impact of plant extracts show that these can be effectively used as alternative prophylactic and antimicrobial agents in Nile tilapia culture.
Padina caulescens and Schizochytrium sp. as Supplemented Feed in the Nursery Production of Penaeus vannamei Post Larvae Reared in Biofloc Systems
(2018) Romero-García, P.G.; Pacheco-Vega, M.; Cadena-Roac, M.A.; Valdez-González, F.J.; Zavala-Leal, Ó.I.; Godínez-Siordia, D.E.; Blanco-Jarvio, A.
The appearance of diverse diseases in cultured shrimp has led to the search for alternative prevention strategies. One of these alternatives is Biofloc technology (BFT). However, this requires further optimization. The objective of this work is to improve this system by adding microalgae (Schizochytrium sp.), probiotic bacteria (Lactobacillus fermentum), and macroalga (Padina caulescens), which in addition to maintaining the quality of water in the Penaeus vannamei culture, improves growth parameters at the maternity stage. We installed an experiment that included six different treatments in culture tanks containing 250 L of seawater each, and 500 shrimp (68 mg) m/3, and evaluated the results for 35 days, in which we gradually decreased the inert-feed to 50-75% and substituted it with 50-25% of P. caulescens. The results showed that, in comparison to the control, survival, and final weight of the shrimps improved and improved further with the use of probiotic bacteria, Schizochytrium sp. and P. caulescens and probiotic bacteria enabled a reduction of 50% of the inert feed. Therefore, we recommended the use of P. caulescens, Schizochytrium sp. (LPU-1), and L. fermentum (T-19) in BFT cultures for P. vannamei.
Pharmacokinetics and Tissue Residence of Various Doses of Levamisole in Crucian Carp at Different Water Temperatures
(2018) Li, G.; Liu, Y.; Gao, C.; Dai, X.; Yang, B.; Liu, T.; Zu, X.
The pharmacokinetics of levamisole in crucian carp, including the absorption, distribution, and clearance rates in different tissues, were studied at different temperatures and doses for the theoretical basis of proper usage and withdrawal time. The fish were divided into three groups denoted A, B and C. The A and B groups were treated once at a dosage of 5 mg/kg levamisole, at 19 ± 1°C and 26 ± 1°C water temperature, respectively. The C group was treated at a dosage of 20 mg/kg levamisole at 19 ± 1°C water temperature. Then plasma, muscle, hepatopancreas, and kidney tissues samples were collected and pretreated, then measured using an ultra performance liquid chromatography-ultraviolet method. Plasma data were analyzed using DAS 3.0 pharmacokinetics software. Total area under the curve (AUC0-t) and elimination half-life (t1/2z) had a negative correlation with water temperature, and a positive correlation with dosage. Apparent volume of distribution (Vz) and total clearance rate (CLz) was positively correlated with temperature, and a negatively correlated with dosage. Levamisole was absorbed quickly to reach its peak concentration. The drug concentration and residence time in hepatopancreal and kidney were considerably higher and longer respectively than in the muscle and plasma suggesting that the hepatopancreas and kidney may be important metabolic organs for levamisole.
Dietary Supplementation of Glycyrrhetinic Acid (GA) Promoting Lipid Lipolysis from Blunt Snout Bream Megalobrama amblycephala by TNF-α and LPL Expression
(2018) Liu, M-y; Liu, G-x.; Zhou, M.; Liu, W-b.; Jiang, G.
Glycyrrhetinic acid (GA), which is a main active principal constituent of liquorice, is extensively used as a non-nutrition sweetener or antiinflammatory in Chinese medicine. This study was carried out to evaluate the effects of different GA levels on growth, biometric parameters, plasma lipid metabolites, Tumor necrosis factor alpha (TNF-α) and Lipoprotein lipase (LPL) gene expression of Megalobrama amblycephala (average weight, 68.78 ±1.13 g). Three diets were formulated to contain various levels of GA (0, 30 and 300 mg/kg). Fish were randomly distributed into 12 cages and fed three times daily for 8 weeks. Dietary GA levels have little significant effect on weight gain and feed conversion ratio. Intraperitoneal fat ratio and viscera/body ratio decreased significantly as dietary GA levels increased, and hepatosomatic index tended to decrease as dietary GA levels increased. Plasma triglycerides, cholesterol, and non-esterified free fatty acid levels also decreased as dietary GA concentrations increased. Adipose tissue and liver TNF-α expression increased significantly with increasing dietary GA levels; whereas, LPL expression showed an opposite trend. Results of this study indicate that dietary supplementation of 300 mg/kg GA had a positive effect in promoting lipid lipolysis in Megalobrama amblycephala without having a negative effect on growth through the regulation of TNF-α and LPL expression.
Bacillus mycoides: An Emerging Pathogen of Ulcerative Disease in Farmed Largemouth Bass Micropterus salmoides
(2018) Cao, H.; Yang, Y.; Lu, L.; Yang, X.; Ai, X.
Ulcerative disease causes significant economic losses in largemouth bass Micropterus salmoides production. Yet information reported on Bacillus mycoides as a pathogen for largemouth bass is scarce. In this study, a virulent strain, temporarily named LYS1, was isolated from diseased M. salmoides suffering from ulcerative disease, identified phenotypically and molecularly as B. mycoides. A phylogenetic tree was constructed to examine isolate LYS1 and compare it to other known isolates. In addition, isolate LYS1 appears to be susceptible to aminoglycosides and quinolones drugs for veterinary use in aquaculture as seen when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of B. mycoides as a pathogen of ulcerative disease in farmed largemouth bass
Heat Shock Protein 70 Gene of Ya-Fish (Schizothorax Prenanti) Responses to Thermal Stress and Bacterial Challenges
(2018) Peng, S; Liu, J.X; Pu, Y.D; Wang, H.; Geng, Y.; Wang, K.Y.; Li, Z.Q.; Du, Z.J.; Chen, D.F.
The homeostasis of Ya-fish (Schizothorax prenanti) health may be affected by a wide variety of stressful stimuli from the complex aquatic environment. Heat shock proteins are extensively distributed and highly conserved in various animals, particularly Hsp70 which is a novel and potential biomarker for stressful environmental factors and disease conditions. The expression of SpHsp70 was detected to evaluate the potential use of SpHsp70 as a warning signal for some stimuli. In this study, freshwater Schizothorax prenanti were exposed to thermal stress and pathogenic bacteria in the aquatic environment. Results showed that SpHsp70 were ubiquitously and differentially expressed in nine examined organs/tissues. In Ya-fish, stessorspecific reactions were observed after different bacterial challenges. At the acute stage, SpHsp70 expression was significantly up-regulated in the kidney after Streptococcus agalactiae challenge, however SpHsp70 expression significantly increased in the spleen after Aeromonas hydrophila challenge. These reactions suggest that the response of SpHsp70 to bacterial stimuli depends on different stressors. Hence, thermal sensitivity and stressorspecificity precluded the simple use of SpHsp70 as warning information in S. prenanti.
Response of Antioxidant Enzymes and Digestive Enzymes to Temperature Stress in Lates Calcarifer Larvae
(2018) Cui, P; Yin, S; Cheng, Z; Qiao, X; Zhou, Q.
A 60-day feeding trial was conducted to evaluate the effects of dietary chromium methionine (Cr-Met) supplementation on growth performance, digestive enzymes, hematological characteristics, and carbohydrate metabolic key enzyme activities in juvenile common carp (Cyprinus carpio). Seven diets (32.2% crude protein, 6% crude lipids of dry matter) were formulated to contain graded levels of Cr3+ (0.31, 0.43, 0.57, 0.73, 1.13, 1.90 and 3.64 mg/kg, respectively). Each diet was randomly assigned to triplicate groups of 60 juvenile common carp (approximately 40.95±4.80 g), which were stocked in plastic tanks. The results indicated that the highest weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER), were observed in fish fed the diet containing 1.13 mg/kg Cr3+. There were no significant differences in the wholebody compositions; however the glycogen levels in the muscle and hepatopancreas in fish fed the basal diet were lower than those fed the other diets. The insulin (INS) and glycogen (GC) concentrations in the serum were not significantly influenced by the dietary Cr-Met levels. However, fish fed the basal diet had higher glucose and cortisol concentrations, and lower insulin receptor (ISR) and LDH concentrations in the serum than those fed diets supplemented with Cr-Met. Fish fed the 1.13 mg/kg Cr3+ diet had significantly higher hexokinase (HK), 6-phosphofructo-1-kinase (6-PFK1), glucose-6-phosphate dehydrogenase (G6PDH), glycogen synthase (GS), and lower phosphoenolpyruvate carboxykinase (PEPCK) activities than those fed the basal diet. Based on the two-slope broken line model analysis between SGR and dietary Cr3+ levels, the optimal dietary Cr3+ supplement level was estimated to be 1.09 mg/kg for juvenile common carp.
Response of Antioxidant Enzymes and Digestive Enzymes to Temperature Stress in Lates Calcarifer Larvae
(2018) Tang X.; Liu Y.; Wu X.; Cheng H.; Meng X.; Ma Z
Acute temperature stress in 15-day post-hatch (DPH) Lates calcarifer larvae was studied using the semi-static bioassay method to understand the physical response of fish larvae to low temperature. In this study, 20oC, 22oC, 24oC, and 26oC were tested and 28oC was the control. Antioxidant enzyme activity including superoxide dismutase (SOD), peroxidase (POD), catalase, acid phosphatase (ACP), glutathione peroxidase (GSH-Px) and digestive enzymes including lipase, amylase, trypsin, pepsin were used as the physical indicators. SOD activities were elevated to scavenge excess reactive oxygen species (ROS) after exposure to lower temperatures, and their activities increased dramatically in relation to the increasing residue time. POD enzyme activity maintained a low level in the early stage of cold exposure and increased to a high level in relation to exposure time. Catalase, GSH-Px, and ACP activities were elevated in fish after exposure to lower temperatures compared to those in fish maintained at 28oC. Lipase activity decreased after exposure to lower temperatures and modestly elevated over time. The highest amylase activity was observed in the control group. However, trypsin and pepsin activity was elevated with the decrease of environmental temperature. Our results indicate that lower temperature significantly affects activity of antioxidant enzymes and digestive enzymes in barramundi larvae. Barramundi larvae exhibited a certain tolerance of low temperature for a short period. Results from the present study will improve our understanding of the physical response of warm water fish to low temperatures and can therefore guide hatchery practices for Lates calcarifer.
Effect of Dietary Tryptophan Levels on Growth and Hemato-Immunological Parameters in Juvenile Nile Tilapia Oreochromis niloticus
(2018) Wu Y.; Zhang L.; Teng T.; Sun R.; Wang W.; Wang Y.; Mi H.
An 8-week feeding trial was conducted to evaluate the effects of dietary tryptophan on growth performance, feed utilization, hematological parameters and non-specific immune responses of juvenile Nile tilapia. Six isonitrogenous and isoenergetic diets were formulated to contain graded levels of L- tryptophan (0.102%, 0.171%, 0.223%, 0.284%, 0.331% and 0.391% of dry weight respectively) from dietary ingredients and crystalline tryptophan. Each diet was randomly assigned to triplicate groups of 25 juvenile fish (1.41±0.01g) three times daily (8:30, 12:30, and 17:00 hours) to apparent satiation. Results showed that weight gain (WG) and special growth rate (SGR) increased with increased dietary tryptophan levels up to 0.284% and remained nearly the same thereafter. Dietary tryptophan requirement was best expressed by the quadratic regression equation y=-6251x2+3525x+538.1 R²= 0.895; based on weight gain against dietary tryptophan levels, with optimal dietary tryptophan requirement estimated to be 0.282% of the diet; corresponding to 6.24% of dietary protein on a dry weight basis. Tryptophan supplementation had no impact on the survival rate, body composition, antioxidant activities, hematological parameters, and non- specific immune parameters of tilapia. Our study indicated that tryptophan supplementation enhanced growth and promoted normal physiology. Our findings could be useful in the aquaculture industry.
Dietary Lipid Level Affects Growth Performance, Antioxidant Capacity, Hematological Characteristics and Lipid Metabolism in Juvenile Black Seabream (Acanthopagrus schlegelii)
(2018) Pan T-t; Qiu H.; Zhu T-t; Lu Y.; Yuan Y.; Zhou Q.; in M.
An 8-week feeding trial was conducted to investigate the effects of dietary lipid levels on growth,antioxidant capacity,hematological characteristics,and lipid metabolismof juvenile black seabream (Acanthopagrus schlegelii) of initial weight 4.33 ± 0.01 g. Three isonitrogenous diets were formulated to contain lipid levels of 36.8 (Diet1, control group), 82.9 (Diet2) and 136g/kg(Diet3). After the feeding trial, fish fed high lipid levels (Diet2 and Diet3) showed higher growth performance and feed efficiency compared to low level (Diet1) group. The hematological characteristics were significantly higher in Diet3 than Diet1. Fish fed Diet3 had significantly highermalondialdehyde (MDA) content and catalase (CAT) activity in serum than Diet1group. Conversely, the hepatic glutathione peroxidase (GSH-Px) and fatty acid synthase (Fas) activity were significantly lower in fish fed Diet3. Overall, this study indicated that juvenile black seabream could adapt high lipid diet (82.9~136g/kg) by regulating growth,hematological characteristics,and lipid metabolism.
A preliminary study of physical energy distribution model of Sciaenops ocellatus under swimming conditions
(2018) Ping W.; Shuai C.; Yudong L.; Yun P.; Fukun G.
This study focused on Sciaenops ocellatus in deep-water cage culture studying the changes of the main energy substances and metabolites during swimming. Based on our results, a physical energy distribution model was constructed. The main conclusions were as follows: (1) A power function relationship between the maximum swimming time and swimming speed of the red drum was found. (2) At high swimming speed, there was a significant increase in red drum blood glucose concentration, a slight decrease in the amount of muscle glycogen, and a significant decrease in hepatic glycogen. When fish were close to fatigue, hepatic glycogen concentration was close to depletion, so hepatic glycogen concentration in the red drum can be used as an important indicator to determine sustained swimming ability in the fish. (3) There was a significant increase in lactic acid and lactic acid concentration during swimming at a high speed, which indicated that the process of high-speed swimming in the red drum was accompanied by anaerobic respiration and aerobic respiration. (4) This study established a simple swimming physical energy distribution model of red drum based on the energy consumption of hepatic glycogen. The model shows a linear relationship between time and swimming speed. (5) A calculation method for the maximum tidal current velocity in red drum farming areas was put forward based on the physical energy distribution model of the red drum and the rules of the tidal currents. Thish may give practical reference for farming site selection.
Comparative Analysis of Non-Specific Immunity of Clarias fuscus, Silurus asotus, and Silurus meridionalis
(2018) Xia H.; Liu L.; Han Q.; Yang P.; Luo Y.; Wang W; Wu X.; Chen N.; Chen F.; Zhou Y.
Clarias fuscus, Silurus asotus and Silurus meridionalis are economically important species in the aquaculture industry in China. However, comparative analysis of immune indices of C. fuscus, S. asotus, and S. eridionalis has been rarely been conducted. In the present study, head kidney and spleen indices and blood serum immunologically related enzyme activity of C. fuscus, S. asotus, and S. meridionalis were detected. Both head kidney and spleen body ratios were highest in S. meridionalis, followed by S. asotus, and lowest in C. fuscus. This suggests that the degree of lymphocyte proliferation and immune function of S. eridionalis might be strongest compared to S. asotus and C. fuscus. Blood serum lysozyme activity, superoxide dismutase (SOD) activity, and alkaline phosphatase activity, were highest in S. meridionalis, followed by S. asotus, but lowest in C. fuscus. Compared to S. asotus, acid phosphatase activity and catalase activity was higher in C. fuscus. Both acid phosphatase and catalase activities were highest in S. meridionalis, which was in line with lysozyme, superoxide dismutase (SOD), alkaline phosphatase, head kidney and spleen body ratios. This indicated that compared to S. asotus and C. fuscus, the immune function of S. meridionalis was strongest, and might have the greatest resistance to invaders like parasites, bacteria, and viruses. These results provide a theoretical basis for selection of varieties and optimization of germplasm in fish culture production and may be very valuable in future research.
Histopathology and Detection of Cyprinid Herpesvirus Infection in Two Koi Farms in Tianjin City (China)
(2018) Liu X.; Hu X.; Lü A.; Sun J.; Chen C.; Huo Y.; Song Y.
Koi herpesvirus (KHV) is the etiologic agent of koi herpesvirus disease (KHVD) causing mass mortalities in common carp (Cyprinus carpio carpio), koi (Cyprinus carpio koi), and ghost carp (Cyprinus carpio goi) populations. In this study, we report new outbreaks of the koi herpesvirus (KHV) disease in a koi carp farm in Tianjin city, northern China. From June to September 2017, severe mortalities of koi juvenile and broodstock occurred in ornamental fish, and infected koi carp which showed signs of lethargy and loss of appetite, and clinical signs including sunken eyes, gill necrosis, and excessive secretion of mucus. Histopathologically, the gills showed hyperplasia and degeneration of epithelial cells and fusion of the lamellae, and foci necrosis was found in gills, liver, kidney, and spleen. In addition, KHV and Carp edema virus (CEV) were detected in the diseased koi fish by diagnostic PCR tests for the viruses. The results showed that the nucleotide sequences of thymidine kinase (TK), DNA polymerase (SphI-5), and four open reading frame (ORF 25, ORF 56, ORF 72, ORF 81) genes confirmed the highest identity with other KHV strains such as KHV-I, KHV-U and KHV-J, but the CEV was negative. The phylogenetic tree showed KHV-TJ1708 and KHV-TJ1709 clustered with the Asian strain KHV-J (AP008984). Results of the present study confirmed the prevalence of Carp herpes disease (KHVD) in China koi populations by means of clinical examination, histopathology and molecular technique. These data will provide a reference for diagnosis, quarantine, and surveillance of KHV in China.
Effect of Dietary Carbohydrate Levels on the Growth and Liver Function of Carp Cyprinus carpio
(2018) Sun J.; Cui P.; Cheng Z.; Bai D.; Qiao X.
This experiment was conducted to study the effects of carbohydrate levels on the growth and liver function of Tianjin carp, Cyprinus carpio (mean body weight, 60.82 ± 0.38 g). Three diets, including 30% protein and 5.5% fat (dry matter) and 0, 15, or 30% corn starch (carbohydrate source) were provided to control, low carbohydrate, or high carbohydrate treatment groups, respectively. Weight gain, specific growth rate, hepatopancreas somatic index, and liver glycogen content were significantly higher in fish fed the 30% corn starch diet than fish fed 0% corn starch (P<0.05) but did not differ between the other two treatment groups. Protein efficiency ratio increased significantly as corn starch level increased (P<0.05), but feed conversion ratio showed the opposite trend (P<0.05). Glutamic pyruvic transaminase activity in the serum significantly increased with increasing corn starch levels (P<0.05), but total protein (decreasing trend) and glutamic-oxaloacetic transaminase (increasing trend) did not differ among dietary treatments. Histomorphological analysis of hepatopancreas sections showed that fish fed 15% or 30% corn starch diets presented mild hydropic degeneration and fatty degeneration or severe fatty degeneration, respectively. In summary, although carbohydrates promote carp growth, they enhance glycogen and fat accumulation in the hepatopancreas, reducing its function.
Effect of Dietary Methionine on Taurine Distribution and Non-specific Immune Responses in Juvenile Blunt Snout Bream, Megalobrama amblycephala at A Constant Dietary Cystine Level
(2018) Zhang W.; Xia S.; Ge X.; Ren M.; Liu B.; Liao Y.
A 9-week feeding trial was conducted to investigate taurine distribution by supplementation of methionine in juvenile Megalobrama amblycephala at a constant dietary cystine level. Six semi-purified diets were formulated to contain graded dietary methionine levels from 0.39-1.54% in about 0.25% increments. At the end of feeding trial, plasma methionine content significantly increased with increasing dietary methionine level from 0.39 to 1.0% (P < 0.05) and thereafter reached a plateau. The taurine content of muscle, intestine, liver, and eye in the fish fed dietary methionine level ranged from 1.24-1.54% and was significantly higher than that of the control group (P < 0.05). Taurine content of the brain in fish fed 1.54% methionine diet was higher than the fish fed 0.39% (P < 0.05). Cysteine sulfinic acid decarboxylase content significantly increased with increasing dietary methionine level from 0.39-0.85% (P < 0.05) and thereafter stayed at a similar level. Supplementation with methionine significantly increased (P < 0.05) plasma total protein (TP) content, complement 3 (C3) content and superoxide dismutase (SOD) activity (0.85% methionine diet groups), aspartate transaminase (AST) activity (1.24% methionine diet groups) and albumin content (1.0% methionine diet groups). Supplemented groups had significantly decreased plasma urea content (0.85% methionine diet groups) (P < 0.05). In conclusion, these results indicate that crystalline methionine can be utilized efficiently, juvenile blunt snout bream were able to convert methionine to taurine directly, and appropriate dietary methionine supplementation improves non-specific immune responses in blunt snout bream.

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