甜菜碱对淡水白鲳的转甲基功效及蛋白质合成的影响

以淡水白鲳(Colossoma brachypomum)鱼种为试验对象,养殖试验周期为60 d。平均试验水温(26.5±0.5)℃。基础饲料粗蛋白水平(质量分数)为41.03％,添加盐酸甜菜碱水平(质量分数)分别为0、0.1％、0.2％、0.4％、O.6％和0.8％。试验结束后,停饲24h取样测定。结果表明,盐酸甜菜碱使整鱼水分含量呈下降趋势(P>0.05),粗蛋白含量呈上升趋势,其中,0.6％甜菜碱组整鱼粗蛋白提高11.89％(P<0.05);鱼肌肉含水量下降,0.1％、O.6％和O.8％甜菜碱组分别降低1.29％(P<0.05)、1.42％(P<0.05)和2.45％(P<0.01),肌肉粗蛋白含量提高,0.4％甜菜碱组提高3.19％(P<0.05);肝脏粗蛋白含量提高,0.2％、0.4％、0.6％和0.8％组分别提高1.04％、O.74％、0.75％和0.87％(4组P<0.01);盐酸甜菜碱显著提高肌肉和肝脏中RNA和TNA含量及RNA与DNA比率;盐酸甜菜碱显著提高肝脏中甜菜碱-高半胱氨酸甲基转移酶和胱硫醚β-合成酶总活力和比活力。本试验结果提示,甜菜碱在肝脏BHMT和β-CYST的双重调控下作为甲基供体参与机体代谢活动,使肝脏和肌肉中甲基化产物(如:核酸)含量增加,从而实现其促进蛋白质合成的功能。     

大蒜素对淡水白鲳生长影响的研究

在饲料中分别添加25、50、75、100mg/kg的大蒜素进行淡水白鲳饲养试验。40d后，与对照组相比，各试验组的增重率分别提高57.49%、91.25%、101.26%和87.74%，成活率分别提高8.13%、2.09%、7.5％、14.59%，饲料系数分别降低8.79%、12.13%、9.62%和1.67%，试验组鱼体肌肉中粗蛋白含量分别提高了3.82%、6.00%、17.69%、18.38%，粗脂肪含量分别降低了5.74%、3.95%、2.75和1.24%。综合考虑大蒜素对淡水白鲳生长性能的影响，认为大蒜素在淡水白鲳饲料中的适宜添加量应为51.86-74.15mg/kg。     

茶粕饲料开发受到关注

本刊讯：茶粕提取物在水产动物中应用．是当前研究的热点。茶粕提取物是糖萜素。有人做过试验，在淡水白鲳基础饲料中分别添加0、125、250、500、1000mg／kg糖萜素。试验结果表明。与对照组相比，250mg／kg糖萜索组增重率提高了57．14％；血清中胆固醇含量降低了11．0％；肌肉中胆固醇含量降低了46．05％。[第一段]     

网箱养殖淡水白鲳

网箱养殖淡水白鲳淡水白鲳生长快、抗病力强、肉质鲜美，能高密度养殖。我们水产站１９９４年夏季网箱养殖淡水白鲳鱼两箱。每箱成鱼产量３８０公斤，饲料系数为２．１。现将技术情况介绍如下；一、网箱的制作和设置；１．淡水白鲳上下颌有齿，网箱宜用塑料网片缝制。网箱...     

山羊羔肠道淋巴集结提取物对淡水白鲳免疫力及生长的影响

取出生30 d以内的山羊(Capra hircus)羔,分离其肠道淋巴集结,经匀浆、反复冻融、离心,制备提取物。用该提取物饲喂体质量(21.2±1.1)g的淡水白鲳(Colossoma brachypomum)以检验其对鱼类免疫力及生长的影响。实验组和对照组各设3个平行组,每个平行组有29尾鱼,饲于1个0.3 m3水族箱。实验组按质量比为2%的比例向基础饲料中添加提取物,对照组只投喂基础饲料。15 d后,实验组淡水白鲳的白细胞吞噬活性、血清抗菌活力、血清溶菌酶活性、血清溶血素、特定生长率、饵料系数均显著高于对照组(P<0.05);血清酚氧化酶和超氧化物歧化酶活性与对照组相比没有显著提高(P>0.05)。实验表明,山羊羔肠道淋巴集结提取物能提高淡水白鲳免疫力,并对其生长有明显的促进作用,其作为饲料添加剂具有良好的应用前景。     

饲料中添加甜菜碱对大口鲶生长的影响

甜菜碱是甜菜加工副产品中提取的甘氨酸甲基类酯，属于维生素类似物。具有特殊的生理功能，可以调节肾细胞的水份渗出，提高钠钾泵的功能，调节体内渗透压。常用作动物营养的甲基供体，参与氨基酸的合成和协同作用。甜菜碱在水产养殖方面常用作诱食剂。Ｎｅｌｓｏｎ１９８９，１９９１研究证实，添加甜菜碱对幼鱼具有显著的促生长，提高成活率的效果；李咏梅１９９８试验表明，饲料添加０．３％甜菜碱，能明显促进罗非鱼的生长。现将饲料中添加甜菜碱对大口鲶生长的影响报道如下。１材料与方法１．１试验材料试验用甜菜碱，购自某饲…     

在池塘中利用豆粕型饲料养殖淡水白鲳试验

在中国江苏省南京市进行的淡水白鲳养殖试验,示范了利用豆粕型全植物蛋白饲料从大规格鱼种养殖淡水白鲳商品鱼的生长性能.试验鱼放养在3口4亩(0.27公顷)的池塘内,放养密度为淡水白鲳800尾/亩,并搭配放养鲢鱼100尾/亩(即淡水白鲳12000尾/公顷和鲢鱼1500尾/公顷).经54天饲养,淡水白鲳从大约149克/尾长至平均628克/尾.平均毛产量为淡水白鲳496千克/亩(7440千克/公顷)和白鲢108千克/亩(1620千克/公顷).平均成活率分别为淡水白鲳98.7%和白鲢100%.养殖所用的大豆最大化饲料,含粗蛋白32%和脂类6%,且用大豆粕作为主要蛋白源,用该饲料养殖淡水白鲳的平均饲料转化率为1.12∶1.不摄食人工饲料的白鲢作为养殖的服务性鱼类,提供了额外的鱼产量,增加了养殖的经济收益.养殖的平均净收入为人民币1809元/亩(3285美元/公顷).平均的投资回报率为59.9%.利用美国大豆协会的大豆最大化饲料和80∶20池塘养殖模式,淡水白鲳在本试验中展示出了优异的生长表现和高效饲料转化效率.生产出的淡水白鲳规格一致、色彩鲜艳且体型匀称.养殖试验示范出的淡水白鲳短的养殖周期表明在中国温带地区的一个生产季节内可以生产两茬淡水白鲳.     

几种诱食剂对克氏原螯虾生长、血清生化指标及消化酶活性的影响

为研究饲料中添加诱食剂对克氏原螯虾生长、血液生化指标、肌肉常规营养成分及消化酶活性的影响,以初始体质量为(4.29±0.03)g的克氏原螯虾(Procambarus clarkii)为试验对象,选用克氏原螯虾231只,随机分为7个处理组,每个处理设3个重复,每组重复11只。采用单因素试验设计,在基础饲料中分别添加1%甜菜碱、TMAO、DMPT、复合氨基酸、大蒜素和复合诱食剂(40%甜菜碱+20%TMAO+20%DMPT+20%大蒜素),试验结束后测定克氏原螯虾生长性能、血清生化指标、肌肉常规营养成分和消化酶活性。结果显示,与对照组相比,在饲料中添加甜菜碱、TMAO、复合氨基酸、大蒜素、复合诱食剂均能显著提高克氏原螯虾的增重率,降低饲料系数(P0.05),复合诱食剂还可以显著提高其摄食率(P0.05);而对存活率没有显著影响(P0.05)。DMPT、复合氨基酸和复合诱食剂组均能显著降低血清谷丙转氨酶的水平;复合氨基酸组还能显著降低胆固醇的水平(P0.05)。添加甜菜碱、TMAO、DMPT、大蒜素和复合诱食剂组肌肉粗脂肪含量显著高于对照组(P0.05)。此外,在日粮中添加诱食剂能提高虾肠道消化酶活性(P0.05)。各组间血清谷草转氨酶、葡萄糖、总蛋白和白蛋白水平、肌肉水分和灰分含量差异均不显著(P0.05)。综上所述,饲料中添加诱食剂能显著提高克氏原螯虾的摄食、生长以及消化酶的活性。其中,复合诱食剂(40%甜菜碱+20%TMAO+20%DMPT+20%大蒜素)对促进克氏原螯虾生长效果最显著。     

淡水白鲳饲料添加剂养殖效果评价

根据淡水白鲳的营养需求，提出维生素预混料配方（维生素添加剂）和微量元素预混料配方（矿物质添加剂），与淡水白鲳基础日料配方，构成一套全价性的淡水白鲳用高效饲料配方，研制的饲料在工厂化封闭式内循环水体中单养条件下养殖淡水白鲳成鱼，经过170天的精心饲养管理，饲料系数平均为 1.89，其中：102#添加剂投喂的饲料系数平均为1.70。淡水白鲳平均规格达到873克，平均净产15.8kg/米^2。     

甜菜碱对尼罗罗非鱼诱食促长的研究

本试验是以罗非鱼基础饲料添加不同浓度甜菜碱纯品及不同复配品组成的配合饲料。在40天饲养试验中所得结果表明，饲料中添加0．3％的甜菜碱能明显促进罗非鱼的生长。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.