免疫增强剂对锦鲤生长性能的影响

<正>近年来,国内外学者对鱼类免疫机制及其病害防治方法进行了大量研究,其中免疫增强剂因具有增强机体的抗应激能力已受到国际养殖界的高度重视。免疫增强剂是一类具有促进或诱发宿主防御反应、增强机体抗病能力的物质。免疫增强剂能够提高水生动物自身非特异性免疫能力,对特异性免疫应答不产生影响,因此,使用免疫增强剂被认为是一种提高水生动物免疫活性及疾病抵抗力的有效方法,具有重要应用价值。     

黄颡鱼免疫增强剂的研究现状和进展

免疫增强剂因能增强机体抗疾病感染的能力、作用时间较短且没有记忆成分,被认为是一种提高鱼体免疫力及对疾病抵抗能力的有效方法。文章综述了近年来免疫增强剂在黄颡鱼养殖中的应用研究现状,主要从微生物来源、动植物来源、营养因子类来源这3大类免疫增强剂对黄颡鱼免疫和抗病能力影响的研究进行了分析总结,展望了黄颡鱼免疫增强剂的研究和发展趋势,可为黄颡鱼健康养殖提供参考。     

渔用中药免疫增强剂的研究现状及其应用

现代水产养殖业追求优质高产，但高密度的养殖往往会导致鱼体的抗应激能力下降，病害增多，成活率下降，造成重大经济损失。同时，大量抗生素的使用，污染了水体，降低了水产品的品质。人们在寻求各种解决途径时已开始注意到中草药作为一种天然的、无污染的物质，具有来源广泛、价格低廉、不宜导致病原菌产生耐药性等优点，在水产上有很大的应用前景。现已证明200余种中草药有多方面的免疫活性，能影响和调节动物机体的免疫功能。本文综述了中药免疫增强剂在水产上的应用研究进展。     

免疫增强剂对鲤鱼内源蛋白酶活性的影响

<正>水产养殖中对水产动物疾病的防治常使用大量抗生素。由于抗生素等化学药物的长期使用或滥用,鱼类对抗生素的耐药致病菌株不断增多,使其免疫功能下降,药物在水产品中的残留也严重影响水产品的安全和人类的健康。近年来,国内外学者对鱼类免疫机制及其病害防治方法进行了大量研究,其中免疫增强剂因具有增强机体的抗应激能力已受到国际养殖业界的高度重视。免疫增强剂是一类具有促进或诱发宿主防御反应、增强机体抗病能力的物质。免疫增强剂能够提高     

中草药免疫增强剂在水产上的开发应用

鱼病的发生是机体本身、病原体和水环境3者相互作用的结果。鱼体是否生病，除了环境条件、病原体毒力、数量、入侵途径等条件外。主要还取决于鱼体本身，即鱼体免疫力的强弱。利用免疫增强剂来提高鱼类机体免疫力，对预防疾病的发生有十分重要的作用。因此，近年来，不少水产工作者已将目光移向水产免疫     

秋、冬季海水网箱养鱼应注意的几个关键问题

鱼类网箱养殖进入秋、冬季，随着气温的逐渐下降，病害发生情况总体趋好，但仍不能放松预防工作，特别是在白露节气前后，昼夜温差较大，为“白露瘟”高发季节，秋季又是台风多发期，因台风发生鱼体擦伤而引起细菌性疾病的现象屡见不鲜。而对于冬季，虽然鱼类是变温动物，但对低温环境的耐受能力却有一定的限度，不同种类的鱼耐受能力不同，若长期处于过低水温的环境中，鱼体易发水霉病等病害。     

鱼体抗病力及其提高措施

近年来鱼类养殖病害越来越严重：鱼类病害已超过１００种，其中危害严重的达１０多种，有些甚至造成了灾难性损失，如２０世纪９０年代初淡水鱼的暴发性出血性败血症、前几年广东部分地区流行的鳜鱼出血病等。造成这种状况的原因除了环境因素和人为因素外，还与鱼体自身的抗病力有关。本文浅谈鱼体的抗病力及其提高措施，供参考。１鱼体的抗病力在一定的条件下，只有外界因素的作用，或仅有病原体的存在，并不能使鱼生病，还取决于鱼体本身对疾病的抗病力。鱼体的抗病力实际上就是指鱼体的免疫力。鱼是一个活的生命，它有自己独特的免疫手段…     

水产饲料中的免疫添加剂

鱼类免疫添加剂包括具有正调节功能的免疫增强剂和具有负调节功能的免疫抑制剂。免疫增强剂是指一些单独使用即能引起机体出现短暂免疫功能增强的物质，一般可分为：生物性免疫增强剂、细菌性免疫增强剂、化学性免疫增强剂、营养性免疫增强剂、中草药免疫增强剂等。免疫增强剂可用于治疗某些传染病如真菌感染、免疫性疾病及非免疫性疾病。     

免疫增强剂在水产养殖中的应用

免疫增强剂作为一种有效控制鱼类疾病的物质，在水产养殖中已得到广泛地应用。目前较常用的免疫增强剂主要有合成化学剂类、微生物类衍生物、动植物提取物、维生素以及激素和乳铁蛋白等。国内外对多糖、几丁质、乳铁蛋白等在鱼虾中的抗病作用做了大量报道，对促生长作用的免疫增强剂(VB、VC、生长激素、促乳素等)也有过不少研究。在虾贝类非特异性免疫系统中，免疫增强剂主要是通过激活吞噬细胞、激活酚氧化酶活力等来提高机体的抗病能力；在鱼类免疫系统中则主要表现为激活抗菌溶菌活力、提高抗体免疫效应以及激活补体等。机体内的免疫活性与机体的抗病能力密切相关，免疫增强剂能有效增强免疫因子的活性，对控制细菌性病原(鳗弧菌、分支杆菌等)和病毒性病原(对虾白斑病毒、鲤痘疮病毒等)有重要意义。在给予免疫增强剂的途径中，注射法是最有效的方法，口服法和浸泡法因其使用便捷也有过不少报道，但这两种方法会随着时间的延长而使药效受到影响。过多、过量的服用免疫增强剂会导致机体的免疫抑制。然而，在实际养殖过程中，免疫增强剂造成的负面影响却没有引起人们的足够重视。从总体上来说，免疫增强剂能有效降低水产动物的患病几率，促进机体生长。但我们必须看到它不是对所有疾病都能起到积极的预防效果，因而在使用免疫增强剂的过程中，应在类型、剂量、方法及病理状况等多种因素的综合考虑下，来有效地应用它，为水产养殖业服务。     

鱼类病害防治误区及对策

随着鱼类养殖规模化、集约化程度的提高，水环境的恶化，鱼类的病害问题日渐突出。但是人们在鱼病的防治上，存在许多误区，防治措施不力，加重了疾病造成的危害。本文就鱼类养殖中病害防治的误区进行了探讨，并提出对策，以期提高鱼病的防治效果。 一、误区 １．缺乏防病意识，管理失当 （１）消毒不严：水体中存在着大量的条件性致病微生物，这些微生物有的是水生的，有的是通过各种途径带入并长期潜伏在水体或鱼体中，但并不引起疾病，只有当环境突变，鱼体抵抗力下降，则可迅速致病。一些养殖者认为，既然水中长期存在着大量的病原微生…     

Probiotics,immunostimulants, plant products and oral vaccines,and their role as feed supplements in the control of bacterial fish diseases

There is a rapidly increasing literature pointing to the success of probiotics, immunostimulants, plant products and oral vaccines in immunomodulation, namely stimulation of the innate, cellular and/or humoral immune response, and the control of bacterial fish diseases. Probiotics are regarded as live micro‐organisms administered orally and leading to health benefits. However, in contrast with the use in terrestrial animals, a diverse range of micro‐organisms have been evaluated in aquaculture with the mode of action often reflecting immunomodulation. Moreover, the need for living cells has been questioned. Also, key subcellular components, including lipopolysaccharides, have been attributed to the beneficial effect in fish. Here, there is a link with immunostimulants, which may also be administered orally. Furthermore, numerous plant products have been reported to have health benefits, namely protection against disease for which stimulation of some immune parameters has been reported. Oral vaccines confer protection against some diseases, although the mode of action is usually linked to humoral rather than the innate and cellular immune responses. This review explores the relationship between probiotics, immunostimulants, plant products and oral vaccines.     

The use of immunostimulating herbs in fish. An overview of research

The use of immunostimulants as an alternative to the drugs, chemicals and antibiotics currently being used to control fish diseases in fish culture is attracting the attention of many researchers. In this context, many have focused on the use of medicinal plant products as potential therapeutic measures for modulating the immune response and, specifically, on the use of herbs to prevent and control fish diseases. Medicinal plants (plant remedies) are a deeply rooted component of the cultural heritage of many people from diverse cultures and countries and are, as such, closely linked to the maintenance of good health. The aim of this paper is to review research currently being carried out on the herbs and herbal extracts that have been shown to modulate the immune system of fish. Special attention is given to the use of Chinese and Indian herbs.     

Medicinal plant derivatives as immunostimulants: an alternative to chemotherapeutics and antibiotics in aquaculture

Aquaculture makes a significant contribution in the production of protein-rich food for human consumption. Aquaculture practices encounter many challenges, and one of the most devastating problems is disease outbreaks caused by microbial pathogens. To control disease outbreaks, several chemotherapeutics and antibiotics were used indiscriminately, which in turn leads to residual problems in the surrounding environment affecting higher animals and also humans. Immunostimulants are considered as an alternative for antibiotics, which will boost the immune system of the cultured organism, thus effectively countering the assault of pathogens. The use of plant materials as immunostimulant will be an ecofriendly approach for the control of pathogens. The botanicals present in the plants have a key role in enhancing the fish immunity. This review focuses on the importance of plant material as immunostimulant in the control of diseases in aquaculture.     

Dietary Beta-Glucans and Nucleotides Enhance Resistance of Red-Tail Black Shark (Epalzeorhynchos bicolor, fam. Cyprinidae) to Streptococcus iniae Infection

Two experiments were conducted to examine the effect of commercially available beta‐glucan (Macrogard) and nucleotide (Aquagen) on the resistance to Streptococcus iniae infections in vaccinated or nonvaccinated juvenile red‐tail black sharks (Epalzeorhynchos bicolor, RTB) (1.4 ± 0.4 g weight total (WT), 5.6 ± 0.5 cm total length (TL)). The immunostimulants were added to a control diet formulated without any yeast source following the recommended doses of 1 g/kg feed for the beta‐glucan and 2 g/kg feed for the nucleotide. Beginning 4 d after introduction into tanks, fish were fed the experimental diets for 24 d, at 3% body weight per day, divided into two feedings. At the end of this period, fish were challenged by an intracoelomic injection of S. iniae. In the first experiment, both vaccinated and nonvaccinated fish were fed one of the two immunostimulants. In the second experiment, only vaccinated fish were fed the immunostimulants. Fish were vaccinated a week after being introduced into the system and challenged by intracoelomic injection with 1.5 × 10⁵ S. iniae colony‐forming units /fish after three additional weeks; mortality was recorded for 2 wk after the bacterial challenge. In the first experiment, the mortality of both vaccinated and nonvaccinated fish fed beta‐glucan (23 ± 7% and 82 ± 1%, respectively) or nucleotide (28 ± 6% and 86 ± 5%, respectively) was significantly lower than the mortality of the control groups (35 ± 4% and 93 ± 5%, respectively), but there was no significant difference in mortality between fish fed beta‐glucan or nucleotide. In the second experiment, the mortality of vaccinated fish fed beta‐glucan (25 ± 7%) or nucleotide (43 ± 9%) was significantly lower than that of vaccinated fish fed the control diet (69 ± 7%). In both experiments, there was no significant difference in growth rate among fish fed immunostimulants or the control diet. The results of this investigation demonstrated the efficacy of beta‐glucans and nucleotides in increasing resistance to S. iniae in RTB sharks.     

Current research on the use of plant‐derived products in farmed fish

Over the years, aquaculture has shown increasing development in terms of production. However, due to intensive farming practices, infectious diseases represent the main problem in fish farms, causing heavy economic losses. The use of antibiotics for controlling diseases is widely criticized for its negative impact, including selection of antibiotic‐resistant bacterial strains, immunosuppression, environmental pollution and accumulation of chemical residues in fish tissues. On the other hand, though vaccination is the most effective prophylactic method of preventing disease outbreaks, the development of effective formulations is often hindered by high production costs and the antigenic heterogeneity of the microbial strains. Recently, there has been increased interest in the possibility of using medicinal herbs as immunostimulants, capable of enhancing immune responses and disease resistance of cultured fish. Plant‐derived products seem to represent a promising source of bioactive molecules, being at the same time readily available, inexpensive and biocompatible. The aim of this article is to provide an overview of recent research dealing with the use of medicinal plants in aquaculture. Special attention is given to the information about the effects of plant extracts/products on fish growth, haematological profiles, immune responses and resistance to infectious diseases.     

Application of immunostimulants in aquaculture: current knowledge and future perspectives

Similar to other industries, aquaculture constantly requires new techniques to increase production yields. Modern technologies and different scientific fields, such as biotechnology and microbiology, provide important tools that could lead to a higher quality and a greater quantity of products. New feeding practices in farming typically play an important role in aquaculture, and the addition of various additives to a balanced feed formula to achieve better growth is a common practice of many fish and shrimp feed manufacturers and farmers. As ‘bio‐friendly agents’, immunostimulants, such as biological factors, probiotics and vitamins, can be introduced into the culture environment to control and kill pathogenic bacteria, as well as to promote growth of the cultured organisms. In addition, immunostimulants are non‐pathogenic and non‐toxic and do not produce undesirable side effects when administered to aquatic organisms. In this review, we summarize previous studies performed with both traditional immunostimulants and the most promising new generation of immunostimulants, such as polysaccharides, nutrients, oligosaccharides, herbs, microorganisms, prebiotics and different biological factors. This review primarily focuses on their protective efficacies and on what is known concerning their effects on the immune systems of aquatic organisms when delivered in vivo.     

Nutrition and health of aquaculture fish

Under intensive culture conditions, fish are subject to increased stress owing to environmental (water quality and hypoxia) and health conditions (parasites and infectious diseases). All these factors have negative impacts on fish well-being and overall performance, with consequent economic losses. Though good management practices contribute to reduce stressor effects, stress susceptibility is always high under crowded conditions. Adequate nutrition is essential to avoid deficiency signs, maintain adequate animal performance and sustain normal health. Further, it is becoming evident that diets overfortified with specific nutrients [amino acids, essential fatty acids (FAs), vitamins or minerals] at levels above requirement may improve health condition and disease resistance. Diet supplements are also being evaluated for their antioxidant potential, as fish are potentially at risk of peroxidative attack because of the large quantities of highly unsaturated FAs in both fish tissues and diets. Functional constituents other than essential nutrients (such as probiotics, prebiotics and immunostimulants) are also currently being considered in fish nutrition aiming to improve fish growth and/or feed efficiency, health status, stress tolerance and resistance to diseases. Such products are becoming more and more important for reducing antibiotic utilization in aquafarms, as these have environmental impacts, may accumulate in animal tissues and increase bacterial resistance. This study reviews knowledge of the effect of diet nutrients on health, welfare and improvement of disease resistance in fish.     

Effect of Garlic,Echinacea, Organic Green and Vet-Yeast on Survival,Weight Gain,and Bacterial Challenge of Overwintered Nile Tilapia Fry (Orechromis niloticus)

The purpose of this study was to examine the effect of some immunostimulants and probiotics on the survival rate, final weight, and disease resistance of overwintered tilapia fry. There were five treatments: T1 (control) fed a balanced diet (35% protein) without additives. Treatments 2 to 5 were fed diets supplemented with 4% garlic, 4 g/kg Echinacea, 4 g/kg Organic Green or 4 g/kg Vet-Yeast, respectively. Growth and resistance to disease challenge with Aeromonas hydrophila and Pseudomonas flourescens were not different among treatments, but survival of overwintered fry increased in treatments fed probiotics or immunostimulents. The use of garlic in overwintering feeds could allow hatchery operators to increase their prices for fry and fish farmers to stock production ponds earlier, increasing hatchery revenues by 74% and improving land use efficiency and productivity for the Egyptian aquaculture industry.     

棕点石斑鱼中草药免疫增强剂的快速筛选

采用离体外周血白细胞与中草药水提液共同孵育法,快速筛选棕点石斑鱼中草药免疫增强剂。39种生药量浓度为100 mg/ml 的中草药水提液及添加5.0 mg/ml 酵母聚糖的中草药水提液分别与棕点石斑鱼外周血白细胞孵育后,采用氮蓝四唑(NBT)还原法检测各种中草药水提液对棕点石斑鱼外周血白细胞氧呼吸爆发活性的影响,再以吞噬乳胶微球法检测具有显著增强白细胞氧呼吸爆发活性效果的中草药对棕点石斑鱼白细胞吞噬活性的影响,筛选中草药免疫增强剂,并将其拌料饲喂棕点石斑鱼,考察其对棕点石斑鱼外周血和头肾白细胞氧呼吸爆发活性的影响。结果显示,39种中草药中有10种对棕点石斑鱼离体白细胞氧呼吸爆发活性显著提高15%以上,3种酵母聚糖添加组对白细胞氧呼吸爆发活性提高70%以上;筛选出可同时提高棕点石斑鱼离体白细胞的氧呼吸爆发活性和吞噬活性的 3种中草药,它们分别为鸡血藤、黄柏和墨旱莲。拌料饲喂实验结果显示,饲喂1%的鸡血藤、黄柏和墨旱莲可显著提高棕点石斑鱼体内外周血和头肾白细胞氧呼吸爆发活性。