浅谈水产微生物制剂的净水与肥水

随着饲料在高密度养殖中的大量投入,饵料残余和水产动物的排泄物在水中大量积增以及防治病害药物的大量使用,造成养殖水体污染,导致水产养殖环境日趋恶化、病害频发、抗生素滥用等问题出现.在此情况下,微生物制剂和生物肥料以其天然、无毒、无副作用、无污染、无残留和价廉、高效、安全可靠的优越性,正在被广泛的推广应用于生产,创造了巨大的经济效益,成为水产健康和高效养殖的一个重要保障.     

中草药免疫增强剂在水产养殖中的应用进展

<正>随着我国水产养殖集约化和规模化程度的不断提高,养殖水域的污染日益严重,养殖病害频繁发生。若长期使用抗生素或其它化学药物来防治水产病害,容易引发一系列水域生态环境和水产食品安全问题。因此,提高水产养殖对象的免疫力,是减少水产病害,保证水     

水产养殖中应用中草药多糖的研究

随着我国水产养殖规模化和集约化的不断提高,水产动物养殖病害也日益严重,成为制约水产养殖业健康可持续发展的主要瓶颈。传统方法是采用抗生素和其他化学药物来控制水产动物疾病,但随之出现的渔药滥用和误用现象,一方面导致环境的污染和恶化;     

高新科技产品与水产养殖的出路

随着市场经济浪潮的起落，对我市水产养殖业发展起着正、负面的影响。1999年由于水产品价格相对稳定，大部分农民瞄准了市场。加上采用较科学的养殖技术，水产养殖取得良好效益。因此今年我市对农业布局进行大面积调整，把水产养殖作为重点，以致出现一边倒的现象。而目前海鲈、罗氏沼虾的价格急跌且长期疲软，水产养殖效益急剧下降。甚至亏本。加之由于高密度的养殖、不合理使用抗生素、环境污染严重而导致水产养殖病害泛滥。     

病害频发,呼唤“疫苗时代”

正中国-东南亚国家淡水养殖病害防控国际学术研讨会在广州召开随着水产养殖的发展,过于集约化的养殖方式使得各种病害频发,进而导致了药物的滥用。药物滥用就会造成抗药病原产生、水产品药物残留、环境污染等一系列问题,目前,越来越多的人开始转变方向,思考水产养殖业能否从"抗生素时代"跨     

抗菌肽作为水产饲料添加剂的应用前景

近年来,随着水产养殖业的快速发展、高密度集约化程度的增大,养殖病害问题逐年增加,抗生素等药物滥用情况严重,致使部分水产品中的药物残留量增加或严重超标,不仅威胁到食品安全,也影响了水产品的出口,给我国的水产养殖业造成了巨大的经济损失。由于目前水产养殖中抗生素耐药菌株的出现速度已经远远超过了抗生素研发速度,并且现有的抗生素开发策略多局限于既有的抗生素类别,难以有实质上的突破,一种新的抗生素出现不久很快就会有病菌产生耐药。     

试谈水产养殖动植物病害防控中的问题与对策

随着我国水产养殖业竞争加剧,养殖种类逐渐增多,养殖密度也不断加大,工、农业废水和城市生活污水的污染以及水产养殖业自身产生所谓"自家污染"日益加重,导致水产养殖环境急剧恶化,各种病害对水产养殖动植物的危害也日益严重。据全国水产技术推广总站在全国范围内进行的水产养殖动植物病害监测结果统计,近年来,严重危害水产养殖动植物的病害高达100多种,由于水产养殖动植物病害造成的直接经济损失每年高达百亿元以上。我国水产养殖动植物病害防控正面临异常严峻的形势。     

15种抗菌中药凝集实验初步分析

我国是水产养殖大国,但是水产病害一直是制约水产养殖发展的主要因素。为治疗和预防鱼虾贝类的疾病,广泛使用各种化学药物和抗生素。长期用药,不仅使病原菌的抗药性越来越明显,而且药物残留和环境污染日趋严重,生态养殖和科学防治成为水产养殖面临的迫切问题。在长期的养殖活动中,发现采用中药如黄连、大黄、板蓝根等对水产病害有一定的防治功能。     

陕西省水产养殖病情测报工作现状、存在问题及建议

<正>水产养殖动物病情测报是水产技术推广部门的一项重要的公益性职能,加强病情测报、预警预报和防治工作对于减少养殖病害发生,降低因病害带来的经济损失,促进我省水产养殖持续、健康、稳定发展具有重要意义。我省开展病害测报工作已有十余年,从2016年起使用病害测报系统软件上传数据,2016年我省共上传测报数据1156条,全面较好地反映我省水产养殖疾病的发生情况。一、水产养殖病害测报工作现状1.水产养殖病害测报网络初步建立按照全国水产推广总站部署和要求,我省已初步建立了"省—市—县—场"四级病害监测及防治网络,并积极开展工作。根据各地水产养殖     

水产养殖用快速药敏选药试剂盒使用技术

正水产养殖生产中滥用渔药特别是抗生素会导致水产致病菌的耐药性、水产品药残、环境污染及生态破坏等问题。要从源头上解决抗生素滥用问题,关键是在水产病害治疗前进行药敏试验,从而在正确诊断的基础上对症用药。为此,泰州市春达公司已成功研制"水产养殖用快速药敏选药试剂盒",现将该项测菌用药新技术介绍如下。一、快速选药试剂盒的价值和使用原理细菌性病害由动物体内或环境中的致病菌感染、传播引起。致病菌的抗生素敏感性变化很快,仅凭以往经验用     

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.     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

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).     

The optimal dietary protein level of juvenile silver sillago Sillago sihama at three dietary lipid levels

A 5 × 3 factorial growth trial was conducted to evaluate optimal dietary protein and lipid levels (dietary protein level, DP; dietary lipid level, DL) for juvenile Sillago sihama (S. sihama) (2.0 ± 0.02 g, initial weight). Fish were fed 15 diets containing 5 DPs (350, 400, 450, 500 and 550 g/kg) and 3 DLs (60, 90 and 120 g/kg) for 8 weeks. The interaction between proteins and lipids significantly influenced the feed conversion ratio, condition factor, body composition, antioxidant indices and lipase activity (p < .05). DP 450 g/kg showed the highest average final body weight. DPs 500 and 550 g/kg significantly decreased the protein efficiency ratio (p < .05). DL 120 g/kg showed the highest percentage weight gain. The low feed conversion ratio was found in diets P45L12, P55L9 and P55L12. Diet P45L12 showed high superoxide dismutase activities. DP 450 g/kg showed the lowest average malondialdehyde content. Lipase activity was increased by increasing DP (p < .05) with a fall at DP 550 g/kg. Under the present experimental conditions, the optimal DP for S. sihama was 450 g/kg under the DL 120 g/kg.     

Vitamin D3 and the renal handling of phosphate in American eels

Cholecalciferol (Vitamin D₃) increased plasma inorganic phosphate concentration in American eels,Anguilla rostrata, in a dose-dependent fashion. This response was more marked in phosphate loaded fish. In control as well as phosphate loaded eels the hyperphosphatemic response to D₃ was associated with a sharp reduction in renal phosphate clearance relative to¹⁴C-polyethelene glycol (PEG) clearance. Glomerular filtration and urine flow rates were not affected by D₃. As renal phosphate clearance, even in phosphate loaded eels, never significantly exceeded that of PEG, it is suggested that D₃ reduced the relative clearance rate of phosphate by increasing renal phosphate reabsorption rather than by reducing the tubular secretion of phosphate.