对虾白便综合征的研究进展

简述了对虾白便综合征(white feces syndrome,WFS)的发病症状、流行特点和危害。分析了对虾白便综合征的病因,包括:肝胰腺和肠道病变、弧菌感染、肝肠孢虫感染、消化系统微生物结构变化和其他因素。从种苗、水质、饲料和管理等方面提出了对虾白便综合征的防治措施。     

Studies on Vaccination of Channel Catfish,Ictalurus punctatus,Against Edwardsiella ictaluri

Enteric septicemia of cattish (ESC), caused by the bacterium Edwardsiella ictaluri, has become the most significant disease problem affecting the commercial channel catfish, Ictalurus punctatus, industry in the United States. Although antibiotics are used extensively for the control of ESC, there are inherent problems associated with their use. Consequently, experiments were initiated to evaluate the effectiveness of vaccination program that used immersion and oral delivery methods to administer a killed E. ictaluri vaccine to fry and fingerling channel cafish. In a preliminary pond study with laboratory challenge, mortality in a group vaccinated with a combination of immersion and oral procedures was only 5.0% in both high- and low-dose challenges. This was significantly different (P c 0.01) from non-vaccinated controls, which had 46.7%mortality in the lowdose challenge and the 6 1.7% mortality in the highdose challenge. This corresponds to relative percent survival (RPS) values of 89.3 and 91.9 respectively. Subsequent field trials further indicated the efficacy of a vaccination program for the prevention of ESC in channel catfish. In 1987-1988, a field study was conducted using 12 commercial ponds, with three replicates of four treatments. The four treatments included vaccination by immersion only, oral only, a combination of both immersion and oral procedures, and non-vaccinated conwols. Relative percent survival was 57.4 for the immersion only treatment, 50.3 for the oral only treatment, and 53.5 for the combination immersion and oral treatment. In 1989-1990, no significant difference was found between vaccinated and non-vaccinated fish. However, in 1989-1990, a vaccine-oil emulsion was topcoated on a floating feed, rather than incorporating vaccine in a sinking pellet. In 1990-1991, overall mortality in vaccinated fish was significantly less (P < 0.05) than non-vaccinated fish, with 41.2% mortality in vaccinates compared to 63.5% in non-vaccinated fish, for an RPS of 35.1. In examining RPS values for individual farms, two farms had excellent results, with RPS values of 81.3 and 76.9; two farms had only moderate success, with RPS values of 26.6 and 15.4; and one location had greater mortality in the vaccinated fish than in the non-vaccinated fish. However, that farm had only two ponds in the study and experienced significant losses to proliferative gill disease in the pond with vaccinated fish.     

Oleous Extraction of Carotenoids from Shrimp Cephalothorax and its Effect on a Microencapsulated Diet with Nauplii Larvae

ABSTRACT

Carotenoids were oil extracted from shrimp-cephalothorax meal at two meal:oil ratios (1:5 and 1:10) and two meal-particle sizes (0.150 and 0.150–0.177 mm). Extraction results were significant at 0.150 mm in particle size and a meal:oil ratio of 1:10, obtaining 286 mgL^?1 of pigments. Pigmented oil was microencapsulated to reduce deterioration by spray drying using two encapsulating blends: Mesquite gum-whey-protein concentrate and Arabic gum-mesquite gum-maltodextrin 10 DE. Microcapsule morphology and thermo-oxidative stability were evaluated. The Arabic/mesquite gum blend showed the best morphology and stability. A bioassay using Litopenaeus vannamei nauplii was performed using microalgae as a control. Results indicated that pigmented oil microcapsules increased the survival percentage when compared with the control. Larvae growth evaluated as the exoskeleton length was significantly different from the control favoring the pigmented oil diet. Larvae behavior measured as DI and PLI_c showed no significant differences among the two treatments and the control.     

Aquatic Products and Human Nutrition

No abstract available for this article.     

基于Deep Forest算法的对虾急性肝胰腺坏死病(AHPND)预警数学模型构建

为预报池塘养殖凡纳对虾(Penaeus vannamei)急性肝胰腺坏死病(AHPND)的发生,自2020年开始,笔者对凡纳对虾养殖区开展了连续监测工作,包括与疾病发生相关的环境理化因子、微生物因子、虾体自身健康状况等18个候选预警因子指标,通过数据标准化处理后分析病原、宿主与环境之间的相关性,对候选预警因子进行筛选,基于Python语言编程结合Deep Forest、LightGBM、XGBoost算法进行数据建模和预测性能评判,仿真环境为Python2.7,以预警因子指标作为输入样本(即警兆),以对虾是否发病指标作为输出结果(即警情),根据输入样本和输出结果各自建立输入数据矩阵和目标数据矩阵,利用原始数据矩阵对输入样本进行初始化,结合函数方程进行拟合,拟合的源代码能利用已知环境、病原及对虾免疫指标数据对目标警情进行预测。最终建立了基于Deep Forest算法的虾体(肝胰腺内)细菌总数、虾体弧菌(Vibrio)占比、水体细菌总数和盐度的4维向量预警预报模型,准确率达89.00%。本研究将人工智能算法应用到对虾AHPND发生的预测预报,相关研究结果为对虾AHPND疾病预警预报建立了预警数学模型,并为对虾健康养殖和疾病防控提供了技术支撑和有力保障。     

Optimizing multi-stage shrimp production systems

Multi-stage penaeid shrimp grow-out systems have considerable advantage over conventional single-stage grow-out systems. A multi-stage shrimp grow-out system has more than one production stage wherein the shrimp stocking density changes as the shrimp grow in size and are moved from one production stage to the next. The shrimp stocking density (shrimp/m²) is at its highest when the shrimp post larvae enter the first production stage and is reduced each time the shrimp are transferred to subsequent stages. The use of multi-stage instead of single-stage production systems has been considered by numerous authors. This paper presents a methodology by which to select the optimum number of stages for a production system and, using available data, demonstrates that optimum efficiency can be achieved, in most cases, by using a two-stage production system consisting of a prolonged nursery stage followed by a grow-out stage.     

Size economies and optimal scheduling in shrimp production: results from a computer simulation model

This paper describes a computer simulation model developed to analyze the economics of shrimp production under different stocking regimes, harvesting schedules, and farm sizes. The operation examined is ‘closed-market’ where all stages of production occur on-site, and the final product, adult shrimp, are sold in the market. The model was parameterized using existing market data and secondary production data collected from experimental units at the Oceanic Institute in Hawaii. Results indicated that a weekly stocking and harvesting regime is more profitable than either a biweekly or 8-week stocking and harvesting regime. Scale economies indicated that the minimum farm size is twenty-six growout ponds and the optimal farm size is 64 growout ponds.     

Hydrology of inland brackishwater shrimp ponds in Chachoengsao, Thailand

This study focuses on a new trend in shrimp aquaculture, the development of brackishwater ponds for Penaeus monodon culture in inland freshwater areas of Thailand’s Central Plain. Water balances were calculated for ponds and reservoirs at an inland shrimp farm in Chachoengsao, Thailand, between May and July 1999. Regulated inflow and outflow were the largest water fluxes, averaging 0.94 and 0.70 cm/day. Other daily average water gains were rainfall (0.52 cm/day) and runoff (1.7 cm/day), and other water losses were evaporation (0.31 cm/day) and seepage (0.52 cm/day). Over an entire crop cycle, of average length 109 days, average water inputs were: initial pond filling (84 cm); regulated inflow (103 cm); rainfall (57 cm); and runoff (3 cm). Average outputs were: regulated outflow (76 cm); seepage (57 cm); evaporation (34 cm); and draining at harvest (87 cm). The main feature of note in the water balance is the large volume of regulated outflow. All regulated outflow and most (82%) of the pondwater drained at harvest went directly to the irrigation canal system. Such large volumes of discharge could have serious environmental implications because small inland waterways have low assimilative capacity and pond effluent is saline. Consumptive water use for 14 inland shrimp ponds and reservoirs averaged 0.83±0.14 cm/day. Consumptive water use was also measured for 11 nearby rice fields, the main land use in the regions where inland shrimp farming is proliferating. Rice paddy water use averaged 0.91±0.17 cm/day. There was no significant difference in the daily consumptive water use of shrimp ponds and rice fields, suggesting that conversion from rice farming to shrimp farming would have little net impact on water availability for irrigation.     

加工方式对海水虾及其制品中SO2含量的影响

亚硫酸盐(以SO_2残留量计)超标是目前影响虾类及其制品质量安全的主要因素之一。本文研究了水煮、蒸、微波烘烤、油炸、风干等加工方式对海水虾中二氧化硫(SO_2)残留量的影响。结果显示,水煮、蒸、微波烘烤和油炸等加工方式可有效降低虾肉中SO_2残留量,降低效果从高到低依次为水煮、蒸、微波烘烤和油炸。在风干过程中,虾肉中SO_2残留量呈先升高后降低的趋势,温度越高,对SO_2的脱除效果越好。在20℃、40℃、60℃、80℃条件下风干加工虾米,当水分含量达到成品要求时,虾米中SO_2残留率分别为132.00%、146.70%、78.25%和48.90%。常温风干方式不利于海米中SO_2消除。脱壳处理可有效降低虾米和烤虾中SO_2残留量。本研究结果将为海水虾中SO_2残留量的控制和限量指标制定提供科学依据,对消费者和生产者利用加工手段降低海水虾中SO_2残留量也具有借鉴意义。     

Antibacterial activity of immobilized silver nanoparticles on TEPA‐Den‐SiO2 against shrimp pathogen,Vibrio sp. Persian1

In this study, we prepared silver nanoparticles immobilized onto silica sand beads as an antibacterial material against pathogenic luminous Vibrio sp. Persian1. Silica beads were modified with 3‐aminopropyltriethoxysilane (APTES), cyanuric chlorid and tetraethylene pentamine, and silver nanoparticles were generated in various concentrations (0.5, 1, and 2 mM g^?1 of silica beads) of AgNO₃ on the surface using chemical reduction. Ag/TEPA‐Den‐SiO₂ samples were characterized by TEM, FE‐SEM/EDS, FT‐IR and ICP OES and their antibacterial activity assayed by zone of inhibition and test tube tests against pathogenic Vibrio sp. The results of the zone inhibitory test revealed that all the Ag/TEPA‐Den‐SiO₂ samples had an antibacterial effect against luminous Vibrio sp. Persian1. In addition, the tube test results showed 100% killing of bacteria in 2 h contact period. Ag/TEPA‐Den‐SiO₂ samples maintained their antibacterial activity after 14‐day immersion in seawater by slow release of silver ions. These results suggest that Ag/TEPA‐Den‐SiO₂ substrates could be effective antibacterial materials for disinfection of seawater used to culture Penaeid shrimp larvae.