Experimental Control of Metacercariae of the Yellow Grub Clinostomum marginatum in Channel Catfish

Abstract

Metacercariae of yellow grub Clinostomum marginatum in the flesh of farm-raised channel catfish Ictalurus punctatus pose a potential marketing problem to fish farmers. Infected fish may not be marketable. Three compounds were tested as possible control agents. Droncit (praziquantel) and Masoten (trichlorfon) were used separately as a bath treatment. Droncit and ivermectin were injected into the musculature to control yellow grub metacercariae. The two treatment rates were 0.65 mg/L plus 15 mg/kg offish as a bath treatment and 25 mg/kg offish as an injected treatment for Droncit. Masoten was treated at a rate of 2 mg/L as a bath treatment and ivermectin (1% solution) was injected at a rate of 0.022 mL/kg. Droncit significantly reduced metacercariae in both bath and injection treatments. Ivermectin also significantly reduced the number of metacercariae, but was not as effective as Droncit. Masoten was ineffective. More study is needed to obtain dosage rates for Droncit and ivermectin that would eliminate yellow grub metacercariae from the flesh of channel catfish.     

Prevalence and intensity of infection of Cryptocotyle lingua (Creplin) and Diplostomum spathaceum (Rudolphi)--parasitic metacercariae of Baltic cod (Gadus morhua L.)

A parasitological investigation of Baltic cod, caught in the Bornholm Basin, showed that 1.6% were infected by C. lingua (metacercaria) and 22.5% were infected by D. spathaceum (metacercaria). Only the heavily C. lingua infected cod showed discoloured fillets due to metacercariae in the muscle. The highest intensity of infection of D. spathaceum was found in smaller cod, but only minor opaque spots were observed in the infected lenses. The low prevalence of C. lingua is supposed to be a result of the mixing of uninfected eastern cod with some infected western cod. Both cod from the eastern Baltic and part of the cod in the western Baltic are liable to be exposed to infection by D. spathaceum.     

黄颡鱼幼鱼的赖氨酸需要量

为评估饲料中赖氨酸水平对黄颡鱼幼鱼生长性能、营养成分和血液指标的影响,进而确定黄颡鱼幼鱼的赖氨酸需要量,试验设计6种等氮等脂的饲料(粗蛋白质45.00%,粗脂肪7.00%),饲料中晶体赖氨酸的添加水平分别为0、0.30%、0.60%、0.90%、1.20%和1.50%,实测各饲料中赖氨酸水平分别为1.58%、1.89%、2.15%、2.41%、2.67%和2.90%。试验选取初始体重为2.00 g左右的黄颡鱼幼鱼360尾,随机分为6组,每组3个重复,每个重复20尾,进行为期12周的养殖试验。结果表明:1.58%组黄颡鱼幼鱼的成活率显著低于其他各组(P0.05)。黄颡鱼幼鱼的增重率和特定生长率随着赖氨酸水平的增加呈先升高后降低趋势,且在赖氨酸水平为2.41%时具有最大的增重率和特定生长率。饲料效率和蛋白质效率均以1.58%组最低,显著低于除2.15%组外的其他各组(P0.05)。饲料中赖氨酸水平对黄颡鱼幼鱼的肥满度、肝体比和内脏比无显著影响(P0.05)。饲料中赖氨酸水平对全鱼和肌肉干物质、粗脂肪含量以及肌肉粗蛋白质含量均无显著影响(P0.05),但显著影响全鱼和肌肉粗灰分含量以及全鱼粗蛋白质含量(P0.05),全鱼和肌肉粗灰分含量均以2.41%组最低,全鱼粗蛋白质含量以2.41%组最高。饲料中赖氨酸水平对黄颡鱼幼鱼全血中红细胞数、白细胞数、血红蛋白含量、红细胞压积无显著影响(P0.05),对血清中总胆固醇、葡萄糖含量及谷草转氨酶活性亦无显著影响(P0.05),但对血清中谷丙转氨酶活性和甘油三酯含量有显著影响(P0.05)。以增重率为评价指标,通过线性模型分析得出黄颡鱼幼鱼对饲料中赖氨酸的需要量为2.61%(相当于饲料蛋白质的5.80%)。     

长期投喂黄芪多糖对黄颡鱼抗氧化及非特异性免疫指标的影响

本文旨在探讨添加不同水平的黄芪多糖(astraglus polysaccharides,APS)对黄颡鱼(Pelteobagrus fulvidraco)抗氧化及非特异性免疫指标的影响.选取2龄健康黄颡鱼540尾,随机分成6组,每组3个重复,每个重复30尾鱼,分别投喂在基础饲料中添加0(对照组)、300、600、900...     

植酸酶预处理饲料对斑点叉尾鮰生长及磷利用率的影响

本试验通过体外预处理方式在饲料中添加植酸酶,旨在探讨其对斑点叉尾鮰生长及磷利用率的影响.试验以初始条件一致、平均体重为(1.74±0.02)g的450尾斑点叉尾鮰(Icralurus punctatus)稚鱼为研究对象,采用单因素完全分组设计,随机分为5个组,每组3个重复,每个重复30尾鱼.D0组为对照组,饲喂基础饲料...     

黄颡鱼幼鱼对饲料中维生素C的需要量

以维生素C水平分别为1.9、18.9、36.8、78.4、156.5和316.0 mg/kg的6种等氮等脂饲料(含42%粗蛋白质和7%粗脂肪)投喂黄颡鱼(Pelteobagrus fulvidraco)幼鱼[初始体重(2.00±0.01)g]12周,研究饲料中维生素C水平对黄颡鱼幼鱼生长性能、抗氧化能力和免疫功能的影响。每种饲料设3个重复,每个重复放养20尾鱼。结果表明:1)当饲料中维生素C水平从1.9 mg/kg上升到156.5 mg/kg,增重率和特定生长率显著提高(P0.05),然而随着饲料中维生素C水平由156.5 mg/kg上升到316.0 mg/kg,黄颡鱼幼鱼的增重率和特定生长率反而有所下降。饲料中维生素C水平对存活率、饲料系数、蛋白质效率、肝体比和脏体比的影响不显著(P0.05)。2)饲料中维生素C水平对黄颡鱼幼鱼血液中血红蛋白含量和血清中葡萄糖、甘油三酯含量的影响显著(P0.05),而血液中红细胞数量、白细胞数量、红细胞压积及血清中总蛋白和胆固醇含量不受饲料中维生素C水平的显著影响(P0.05)。3)当饲料中维生素C水平由1.9 mg/kg上升到156.5 mg/kg时,血清中超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶的活性显著提高(P0.05),丙二醛含量显著下降(P0.05);当饲料中维生素C水平由156.5 mg/kg上升到316.0 mg/kg时,血清中超氧化物歧化酶、过氧化氢酶活性和丙二醛含量变化不显著(P0.05),但谷胱甘肽过氧化物酶活性出现显著下降(P0.05)。4)饲料中维生素C水平由1.9 mg/kg上升到156.5 mg/kg时,血清溶菌酶活性显著提高(P0.05),但随着维生素C水平的继续升高,溶菌酶活性变化不显著(P0.05)。随着饲料中维生素C水平的升高,头肾巨噬细胞吞噬百分率和呼吸爆发呈先上升后下降趋势,在维生素C水平为156.5 mg/kg时达到最大值。5)注射嗜水气单胞菌14 d后,饲料中维生素C水平为18.89和36.76 mg/kg时的累计存活率显著高于维生素C水平为1.9 mg/kg时(P0.05)。以特定生长率和血清中溶菌酶活性为评价指标,通过折线模型得出黄颡鱼幼鱼饲料中维生素C的需要量分别为114.5和142.3 mg/kg。     

谷氨酰胺对黄颡鱼幼鱼抗氧化能力和非特异性免疫力的影响

本试验旨在研究谷氨酰胺对黄颡鱼幼鱼抗氧化能力及非特异性免疫力的影响。选取平均体重为(2.49±0.04)g的黄颡鱼幼鱼240尾,随机分为4组,每组3个重复,每个重复20尾。4组试验鱼分别饲喂谷氨酰胺添加量为0(对照)、0.1%、0.2%、0.4%的等氮等能试验饲料。试验期为10周。结果表明:饲料中添加0.2%的谷氨酰胺可以显著提高黄颡鱼幼鱼的血清总蛋白、球蛋白、甘油三酯、高密度脂蛋白和低密度脂蛋白含量(P0.05);各组黄颡鱼幼鱼的血清谷丙转氨酶、谷草转氨酶和碱性磷酸酶活性差异不显著(P0.05);饲料中添加0.1%的谷氨酰胺可以显著提高黄颡鱼幼鱼肝脏中过氧化氢酶、谷胱甘肽过氧化物酶及肌肉中超氧化物歧化酶、谷胱甘肽过氧化物酶的活性(P0.05);随着饲料中谷氨酰胺添加量的增加,头肾巨噬细胞的吞噬指数呈升高趋势,且0.2%和0.4%组较对照组显著升高(P0.05),但0.2%和0.4%组间差异不显著(P0.05)。由此可见,饲料中添加0.1%~0.2%的谷氨酰胺能够提高机体的抗氧化能力和非特异性免疫力。     

红藻糖苷对黄颡鱼幼鱼生长性能及血液学指标的影响

本试验旨在研究饲料中添加红藻糖苷对黄颡鱼幼鱼生长性能及血液学指标的影响。将大小均一、初始体重为(2.49±0.04)g的黄颡鱼幼鱼240尾,随机分为4组,每组3个重复,每个重复放养20尾,分别投喂添加0(对照组)、0.1%、0.2%和0.4%红藻糖苷的试验饲料。试验期为10周。结果表明:0.1%组的终末体重、增重率和蛋白质效率均显著高于其他各组(P0.05),特定生长率显著高于除0.2%组外的其他各组(P0.05)。饲料中添加不同水平红藻糖苷对黄颡鱼幼鱼存活率、饲料效率、肥满度、肝体指数和脏体指数的影响不显著(P0.05)。在红藻糖苷添加量为0.1%时,血清总蛋白、胆固醇、甘油三酯和葡萄糖含量均较高,谷丙转氨酶和谷草转氨酶活性均最低,且球蛋白和高密度脂蛋白含量显著高于其他各组(P0.05)。饲料中添加不同水平红藻糖苷对黄颡鱼幼鱼的全血血红蛋白含量及白细胞和红细胞数量无显著影响(P0.05)。由此得出,在饲料中添加0.1%的红藻糖苷可以促进黄颡鱼幼鱼的生长,并改善其部分血清生化指标。     

Effect of Temperature and Dissolved Oxygen Concentration on Edwardsiella ictaluri in Experimentally Infected Channel Catfish

Abstract

Channel catfish Ictalurus punctatus were experimentally infected with Edwardsiella ictaluri by immersion exposure. After clinical disease ran its course for 52 d, the surviving fish were exposed to one of the following environmental regimes in troughs: 25°C with aeration, 25°C with no aeration, or variable temperature (18–23°C) with no aeration. After 29 d of exposure to the environmental regimes, various organs and tissues of the fish were assayed to determine the effects of these conditions on E. ictaluri concentrations (colony-forming units/mL of tissue sample). The concentrations of this pathogen were significantly (P < 0.05) higher in all tissues (trunk kidney, liver, head kidney, blood, spleen, gallbladder, muscle, brain, and gonad) 52 d postinfection than 29 d after exposure to any of the environmental regimes (81 d postinfection). Fish exposed to a near-normal concentration of dissolved oxygen (6.4 mg/L) and a constant temperature of 25°C had E. ictaluri concentrations that were significantly (P < 0.01) lower than those offish exposed to a low oxygen concentration (2.6 or 1.8 mg/L) and either a constant or a variable temperature.     

Dose Titration of Sarafloxacin (A-56620) against Edwardsiella ictaluri Infection in Channel Catfish

Abstract

Two dose-titration studies were performed with sarafloxacin (A-56620) on channel catfish Ictalurus punctatus infected with Edwardsiella ictaluri. Fish were infected with E. ictaluri by water-bath exposure and subsequently fed rations for 5 d to equal 0, 2, 6, 10, or 14 mg sarafloxacin/kg body weight per day. In trial I, mortality was significantly reduced from 69% for fish receiving no medication to 17% for those receiving 10 or 14 mg sarafloxacin/kg per day (P ≤ 0.01). In trial II, mortality was reduced from 33% of the nonmedicated infected group to 5 and 10% offish receiving 10 and 14 mg sarafloxacin/kg per day, respectively. Fish receiving 2 or 6 mg sarafloxacin/kg per day had intermediate mortality rates.     

Effect of Vitamin E on the Immune Response of Channel Catfish to Edwardsiella ictaluri

Abstract

Three-month-old fingerling channel catfish Ictalurus punctatus were fed purified diets supplemented with ∝-tocopherol acetate to provide 0, 60, and 2,500 mg vitamin E/kg for 180 d. A 30-s immersion bath and an oral booster were used to deliver a bacterin of formalin-killed Edwardsiella ictaluri to half of the fish from each dietary treatment. Resistance of red blood cells to peroxidation was used as an index of antioxidant status. The susceptibility of red blood cells to oxidative hemolysis decreased with increasing levels of dietary vitamin E. Vaccinated and nonvaccinated fish were evaluated for agglutinating antibody titers and macrophage activity. Humoral antibody titers in response to E. ictaluri were significantly (P ≤ 0.05) higher in vaccinated fish than in nonvaccinated fish; however, no such differences in agglutinating antibody titers were detected among any of the dietary treatment groups. Both vaccination and vitamin E significantly enhanced the ability of macrophages to phagocytize virulent E. ictaluri. Results of this study indicate that elevated levels of dietary vitamin E may affect the ability of channel catfish to respond immunologically to bacterial pathogens.     

Effect of Waterborne Potassium Permanganate Exposure on Manganese Content in Liver and Axial Muscle of Channel Catfish

Abstract

Adult channel catfish Ictalurus punctatus were exposed to waterborne potassium permanganate for 12 weeks to determine if such exposure would alter the manganese content of axial muscle or liver tissue. Continuous exposure to 0.5 mg KMnO₄/L or exposure to 1 or 2 mg KMnO₄/L on alternate days did not cause a significant increase in manganese in axial muscle or liver tissue. The mean (±SE) concentration of manganese in axial muscle of unexposed controls was 0.262 ± 0.018 mg/kg (wet weight). Means of manganese concentrations in axial muscle of the three exposure groups during the 12 weeks of exposure were 0.289 ± 0.021 mg/kg, 0.269 ± 0.018 mg/kg, and 0.239 ± 0.013 mg/kg for 0.5 (continuous), 1, or 2 mg/L (alternate days), respectively. At specific sampling times there were differences between controls and exposure groups; however, no trend toward higher or lower manganese concentrations in muscle could be detected within groups. The mean (±SE) concentration of manganese in liver tissue of controls was 1.67 ± 0.09 mg/kg (wet weight). Manganese concentrations in liver tissue of the three exposure groups were 1.57 ± 0.07 mg/kg, 1.68 ± 0.08 mg/kg, and 1.58 ± 0.10 mg/kg, for 0.5 (continuous), 1, or 2 mg/L (alternate days), respectively. Manganese was thought to accumulate in liver tissue, however, there were no statistically significant differences between those groups and the controls. Results suggest that potassium permanganate used as a waterborne disease therapeutant for channel catfish does not alter manganese content of edible muscle of channel catfish and should not present any hazard to human consumers.     

烁生肽(R)替代鱼粉对黄颡鱼幼鱼生长及饲料利用的影响

本研究旨在研究烁生肽@(SourceR peptide,SP)替代日粮中鱼粉对黄颡鱼幼鱼生长、饲料利用效率、体组成成分以及脂肪和蛋白质保留效率的影响.选取体况良好、体重3～4 g的黄颡鱼幼鱼随机分成5组,每组设3个重复,每个重复放养20尾.基础日粮中用烁生肽R等氮替代日粮中0%(DO)、25%(D1)、50%(D2)、75%(D3)、100%(D4)的鱼粉,配制成5组等氮等能日粮.每组随机分配1种日粮,每天按体重的3%～5%投饲率分别在09:00和16:00两次投喂,试验期为42 d.结果表明,D1组鱼体增重率、特定生长率、饲料效率、蛋白质效率显著高于其他各组(P＜0.05),D2、D0、D3、D4组依次降低;脂肪保留效率以D1、D2、DO、D3、D4的顺序逐渐降低,其中D3、D4组显著低于D1组(P＜0.05);D1组蛋白质保留效率显著高于其他各组(P＜0.05),DO、D2、D3、D4组依次降低,D3、D4组显著低于其他各组(P＜0.05);烁生肽R替代鱼粉对黄颡鱼内脏比、肝体比、体蛋白质含量、体灰分含量无显著影响(P＞0.05),各组鱼体粗脂肪含量差异显著性不同.由结果可知,烁生肽@替代适宜比例(25%、50%)鱼粉可以促进黄颡鱼幼鱼生长,并提高饲料、蛋白质效率,降低饲料成本.     

The efficacy of praziquantel (Droncit R) against Raillietina tetragona (Molin, 1958) in domestic fowl

The efficacy of different dose rates of Praziquantel (Droncit R) in tablet and liquid (injectable) form against Raillietina tetragona in the domestic fowl was studied. A dose of 10 mg kg-1 of Praziquantel in tablet form and 0.15 ml kg-1 in liquid form was found to be effective against R. tetragona infection irrespective of age, sex and intensity of infestation of the host. Intramuscular (IM) administration of liquid Praziquantel was found to be more effective than subcutaneous (SC) administration. Susceptibility of the parasite to this drug increased with age.     

Comparative Susceptibility of Channel Catfish,Blue Catfish,and their Hybrid Cross to Experimental Challenge with Bolbophorus damnificus (Digenea: Bolbophoridae) Cercariae

Abstract

The digenetic trematode Bolbophorus damnificus has been implicated in significant losses in catfish aquaculture since the late 1990s. The complex life cycle sequentially involves the American white pelican Pelecanus erythrorhynchos, the marsh rams horn snail Planorbella trivolvis, and Channel Catfish Ictalurus punctatus. Research supports anecdotal reports from the industry, suggesting that the hybrid of Channel Catfish×Blue Catfish I. furcatus is less susceptible to disease agents that have been historically prohibitive to Channel Catfish production, namely the gram-negative bacteria Edwardsiella ictaluri and Flavobacterium columnare, as well as the myxozoan parasite Henneguya ictaluri. This current research compared the susceptibility of Channel Catfish, Blue Catfish, and their hybrid cross to an experimental challenge by B. damnificus. Fish were exposed to 0, 100, 200, and 400 B. damnificus cercariae per fish, and the numbers of metacercariae per fish were determined 14 d postchallenge. Metacercariae were recovered from all challenged fish. There were no significant differences among fish groups challenged with the same dose, suggesting Channel and Blue Catfish and their hybrid are comparably susceptible to B. damnificus infection. As such, it is recommended that producers raising hybrid catfish remain diligent in controlling populations of the snail intermediate host to prevent production losses attributed to B. damnificus, especially when loafing pelicans have been observed at the aquaculture operation.

Received October 22, 2013; accepted January 5, 2014     

Induction and Evaluation of Proliferative Gill Disease in Channel Catfish Fingerlings

Abstract

Proliferative gill disease (PGD) was first reported in channel catfish Ictalurus punctatus at commercial farms in 1981 and is caused by the myxozoan parasite Henneguya ictaluri. The disease affects the gills and is characterized by severe branchial inflammation, epithelial hyperplasia, lamellar fusion, and lysis of chondrocytes. Presumptive diagnosis is based on the presence of lytic areas in the cartilage of the primary lamellae on microscopic examination and is confirmed histologically by the presence of the organism. In these trials, PGD was induced by exposing channel catfish fingerlings to fresh or aged infectious water collected from a pond containing fish diagnosed with severe PGD. The severity of disease was graded by histological scoring and microscopic examination of wet mounts to determine the percentage of gill filaments containing chondrolytic lesions. Exposure of fish to infectious pond water was shown to produce pathological lesions consistent with PGD, and the percentage of gill filaments containing chondrolytic lesions was positively correlated with histological scoring of gill pathology. The number of trophozoite stages in the gills was shown to increase with the severity of the disease. In most cases, however, parasitic cells were not observed in tissue samples with chondrolytic lesions during the early stages of infection. These observations indicate that pathology and lysis of chondrocytes can occur prior to detection of the organism by histopathology. Exposing fish to infectious pond water that was aged for 1 d produced negligible gill pathology and implies that the infectivity of the H. ictaluri actinospore stage is short lived. Removing fish from the source of infection promoted repair of damaged gill tissue; within 14 d of fish transfer to clean water, gill pathology associated with the acute infection was negligible.     

长期投喂黄芪多糖对黄颡鱼免疫细胞活性的影响

本试验旨在研究黄芪多糖(Astragalus polysaccharides,APS)对黄颡鱼(Pelteobagrus fulvidraco)免疫细胞活性的影响.540尾鱼被随机分成6组,每组3个重复,每个重复30尾鱼,分别投喂添加0、300、600、900、1 200、1 500 mg/kg APS的饲料,饲养期为...     

Effects of Feeding Spirulina on Specific and Nonspecific Immune Responses of Channel Catfish

Abstract

Administration of various immunostimulants to fish has resulted in enhanced immune responses. The purpose of this study was to determine if feeding Spirulina, a processed form of the blue-green alga Spirulina platensis, enhanced specific and nonspecific immunity and resistance against Edwardsiella ictaluri infection in channel catfish Ictalurus punctatus. Peritoneal phagocytes from fish fed Spirulina showed enhanced phagocytosis to zymosan and increased chemotaxis to E. ictaluri exoantigen. No significant difference in mortality due to E. ictaluri existed between fish fed Spirulina and fish fed a basal diet. No significant difference in antibody titer or in the percentage of fish positive for E. ictaluri antibody was found between the groups after immunization with formalin-killed E. ictaluri. Spirulina-fed fish had significantly higher antibody titers to key hole limpet hemocyanin (KLH) on day 22, and a greater percentage of these fish were positive for KLH antibody on days 15 and 36. Feeding Spirulina enhanced nonspecific cellular immune responses such as chemotaxis and phagocytosis but did not provide protection against infection with E. ictaluri. The use of Spirulina in feed resulted in enhanced antibody responses to KLH, a thymus-dependent antigen, but not to E. ictaluri, a thymus-independent antigen. These results indicate that stimulation of the nonspecific immune system of channel catfish does not provide enhanced protection from E. ictaluri.