Optimum Dietary Level of L-ascorbic Acid for Japanese Eel, Anguilla japonica

A feeding experiment was conducted to determine the optimum dietary level of ascorbic acid (AsA) for Japanese eel juveniles using L-ascorbic acid Ca based on growth, AsA content in tissues, hematology, and bactericidal activity of serum with Escherichia coli . Test diets with six levels of AsA (3, 10, 27,126, 645, and 3,135-mg/kg diet) as Ca ascorbate were fed to juvenile Japanese eels (11.0 ± 0.2 g) once a day for 8 wk. High survival rates (> 80%) were observed among all dietary treatment groups. The specific growth rates of the fish fed diets containing 3 and 10-mg AsA/kg were significantly (P < 0.05) lower than those of other groups. Liver and brain AsA contents of the fish fed diets containing 3, 10, and 27-mg AsA/kg were significantly (P < 0.05) lower than those of the fish fed diets containing 645 and 3,135-mg AsA/kg. Hemoglobin content tended to be higher in the fish fed diets containing 645 and 3,135-mg AsA/kg than those of the fish fed other diets. Hematocrit value and total serum protein content of the fish fed diets containing 645 and 3135 mg AsA/kg were significantly (P < 0.05) higher than those of the other groups. The fish fed diets containing more than 27-mg AsAlkg showed a higher bactericidal activity of serum than the fish fed the diets containing 3-mg and 10-mg AsA/kg. The optimum dietary level of AsA for the Japanese eel juveniles growth was estimated to be more than 27-mg AsA/kg. Furthermore, the inclusion of 645-mg AsA/kg or more also increased the hematocrit, hemoglobin, total serum protein value, and liver and brain vitamin C concentrations.     

Reevaluation of the Dietary Protein Requirements and Optimum Dietary Protein to Energy Ratios in Japanese Eel, Anguilla japonica

A 2 × 3 factorial design was used to reevaluate the dietary protein requirements and to determine the optimum dietary protein to energy (P/E) ratios in Japanese eel, Anguilla japonica, reared in the recirculating system. For each of two experiments, six experimental diets (₄₅P₁₆, ₄₅P₁₇, ₄₅P₁₉, ₅₀P₁₆, ₅₀P₁₇, and ₅₀P₁₉) were formulated and prepared to contain two protein levels (45 and 50%) and three energy levels (16, 17, and 19 kJ/g diet) at each protein level. In the first experiment, glass eel of initial weight 0.1 ± 0.02 g (mean ± SD) were used, while the second experiment was conducted with juvenile eel of initial weight 15.0 ± 3 g (mean ± SD). The first and second experimental periods were 6 and 16 wk for the glass and juvenile eel, respectively. At the end of the first experiment, there were no protein, energy, and their interaction effects. Also, there were no significant differences in weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) for glass Japanese eel fed all diets. Although there were no significant differences in growth parameters of glass eel fed all experimental diets, these parameters were higher for fish fed ₅₀P₁₆ than for fish fed the other diets. For the second experiment, there were significant protein effects on WG, SGR, and PER (P < 0.05). However, there were neither significant energy effects nor protein and energy interaction effects on WG, SGR, FE, and PER. Fish fed ₄₅P₁₉ had a higher WG, SGR, and PER than did fish fed ₄₅P₁₆, ₅₀P₁₆, and ₅₀P₁₉ (P < 0.05). However, there were no significant differences in growth parameters among fish fed ₄₅P₁₆, ₄₅P₁₇, ₅₀P₁₆, ₅₀P₁₇, and ₅₀P₁₉ and among those fed ₄₅P₁₇, ₄₅P₁₉, and ₅₀P₁₇. These results may indicate that the optimum dietary protein requirement and the P/E ratio could be 44.3% and 24.1 mg protein/kJ (₄₅P₁₉), respectively, in juvenile Japanese eel, based on WG, SGR, and PER.     

花鳗、欧鳗和日本鳗肌肉无机元素的分析

采用电感耦合等等子体发射光谱仪对花鳗、欧鳗和日本鳗肌肉无机元素组成进行了测定。结果表明:花鳗肌肉中Ca含量最高,P含量次之。欧鳗和日本鳗肌肉中P含量最高,Ca含量次之。三种鳗鲡肌肉中Na、Mg、K含量相近且高低顺序相同,花鳗肌肉中常量元素和Zn、Fe、Mn的含量均高于欧鳗和日本鳗。三种鳗鲡肌肉中均含人体不可缺少的微量元素Zn。据此可认为花鳗营养价值最高。     

日本鳗鲡游泳能力和游泳行为研究

研究日本鳗鲡的游泳能力特性指标和游泳行为,为日本鳗鲡的保护及渔业管理提供参考。在（22±0.5）℃试验水温下,针对体长为21.4～43.5 cm,体重11～62 g的日本鳗鲡,利用自循环明渠变坡水槽,采用流速递增法开展鱼类感应流速、临界游泳速度和爆发游泳速度的试验研究。结果表明（：1）闽江流域日本鳗鲡的感应流速为（3.3～4.8）cm/s,即（0.109～0.196）BL/s;临界游泳速度为（49.5～86.5）cm/s,即（1.874～2.331）BL/s;爆发游泳速度为（86.9～135.9）cm/s,即（2.982～4.062）BL/s。（2）日本鳗鲡的绝对特征流速随体长的增加而增加,相对特征流速随体长的增加而减小。（3）随着流速的递增,日本鳗鲡游泳形态分为5个阶段：顺流爬越、逆流转向静止、逆流上溯爬越、逆流冲刺后静止、逆流后退。以日本鳗鲡为主要过鱼对象时,建议鱼道内最小水流速度应大于10.0 cm/s,高流速区最大设计水流大于70.0 cm/s,小于112.0 cm/s。研究结果可为闽江鱼道水力设计提供依据。     

人工感染嗜水气单胞菌对日本鳗鲡血清酶活力的影响

为了解日本鳗鲡(Anguilla japonica)受嗜水气单胞菌(Aeromonas hydrophila)感染后血清酶活力的变化规律,将日本鳗鲡分为感染组和对照组,每组30尾,腹腔分别注射0.1 mL浓度为3×106CFU/mL的菌液和等量灭菌生理盐水。在注射后0、1、5、9、13、17、21、25、29、33 d从两组各取3尾日本鳗鲡,尾静脉取血,测定其酸性磷酸酶(ACP)、超氧化物歧化酶(SOD)、一氧化氮合酶(NOS)活力的变化规律。结果显示:注射嗜水气单胞菌一段时间后,实验组鳗鲡的ACP和SOD的活力都显著高于对照组,且都在21 d时达到最高值,随后逐渐下降。结果表明:嗜水气单胞菌感染后,日本鳗鲡能够通过提高血清中ACP和SOD活力来提高机体对嗜水气单胞菌的免疫力,而对一氧化氮合酶的活力没有显著影响。     

不同生长状况下日本鳗鲡耗氧率的初步测定

日本鳗鲡（Ａｎｇｕｉｌａｊａｐｏｎｉｃａ）是我国淡水养殖的主要名优鱼类。鳗鲡养殖过程中,会出现为数不少的生长缓慢的个体,这些个体饲养２年,仍然达不到每尾１５０ｇ以上的出口商品规格,俗称“老头苗”,对养鳗的经济效益产生很大的影响。关于鱼类耗氧率的测定研...     

循环水养殖系统培育日本鳗鲡和美洲鳗鲡苗种的研究

采用具有气泡反冲洗型珠子过滤器的循环水养殖系统对日本鳗鲡和美洲鳗鲡进行了苗种培育的研究。2种鳗苗的放养密度约为传统模式的8～10倍,试验期间换水量约为20%～45%。结果显示:日本鳗苗和美洲鳗苗成活率均≥96.74%,高于传统模式。投喂水丝蚓阶段,日本鳗苗特定生长率和饲料系数分别为(7.08±0.08)%/d和4.92±0.03,美洲鳗苗分别为(4.83±0.06)%/d和4.74±0.19。投喂配合饲料阶段,日本鳗苗分别为(2.30±0.19)%/d和1.30±0.02,美洲鳗苗分别为(1.69±0.05)%/d和1.76±0.06。研究表明,该循环水养殖系统可适用于日本鳗苗和美洲鳗苗的培育,并具有节能、减排和无药残等优点,为开发资源节约型和环境友好型的鳗鲡育苗模式提供参考。     

鳗鱼养殖技术之一日本鳗鲡静水养殖实用技术

在山东省乃至北方大部分地区,利用静水养殖成鳗,后捕捞,随行上市(市场价50元/kg~60元/kg),具有较高的经济效益。现将日本鳗鲡静水养殖技术介绍如下:一、池塘条件池塘面积1亩~2亩,水深约1.2m米为宜。池壁为砖石水泥结构,并用水泥抹光,且池壁顶部向池内出檐5cm~10cm。池壁要深入池底下33cm左右,以防擦伤鳗体。池底除要求不漏水以外,还要求牢固坚硬,以防鳗体钻进泥底,也便于捕捞。要求去掉淤泥,如淤泥过多而不易除去,可采取长时间曝晒池底的方法使淤泥变硬,再经平整后铺入20cm厚的石渣压实,其上再铺5cm~10cm的小石渣,最上面以5cm厚的细石砾或黄…     

日本鳗鲡人工繁育研究的进展

从日本鳗鲡亲本的选择、人工催熟催产技术、仔鳗的饵料开发、仔鳗的培育装置及培育方法等方面综述了目前在日本鳗鲡繁育方面的最新研究成果,以期为国内日本鳗鲡的人工繁殖研究提供参考资料.     

日本鳗鲡排卵的人工诱导

对日本鳗鲡(Anguillajaponica)卵巢发育的时间与催产率的关系进行研究,对卵母细胞在体内胚泡破裂(GVBD)的发生过程、以及用17α-OHP和17α,20β-DHP诱导日本鳗鲡排卵的方式、时机和催产效果进行观察,结果表明,卵巢发育时间越长,催产率越低。造成催产率低的原因主要是由于日本鳗鲡在卵母细胞成熟后期,雌鳗个体对催产药物敏感性差异较大,催产时机难以掌握。通过采用适合日本鳗鲡卵母细胞的透明液观察GVBD的发生过程,并根据每个个体GVBD的发生速度,制订适宜的催产方案基本解决了上述难题。本实验采用CP、HCG、17α-OHP或17α,20β-DHP混合催产,使其平均催产率由35 4%分别提高到91 9%和93 0%。17α-OHP和17α,20β-DHP的催产剂量为5mg/(500g)和10mg/(500g)。在(21±0 5)℃水温条件下,催产效应时间分别为15～18h和13～16h。     

鳗鲡血液细胞的研究

本文通过鳗鲡血液有形成份Ｗｒｉｇｈｔ染色并进行显微分析，辩识其红血细胞、嗜中性粒细胞、嗜酸性粒细胞、嗜碱生粒细胞、小淋巴细胞、单核细胞和血栓细胞并加以分析。     

日本鳗鲡腐皮病病原菌的分子生物学鉴定

福清市水产技术推广站从患腐皮病的日本鳗鲡上分离到1株病原菌Ms37101NG,经人工感染试验确定为致病菌.同时菌株Ms37101NG经常规生理生化鉴定属于气单胞菌属.为了进一步确定其分类地位,本试验采用了分子生物学的鉴定方法,测定了菌株Ms37101NG的16SrRNA基因部分序列.16SrRNA基因系统进化分析表明,...     

Effects of temperature on vitellogenesis in Japanese eel Anguilla japonica

ABSTRACT:   Cultured immature female Japanese eels acclimated to sea water at either 10 or 20°C were treated weekly with salmon gonadotropin fraction (sGTH) in order to investigate the effects of water temperature on artificial induction of ovarian maturation. In eels maintained at 20°C, ovulation was induced in 11 of 18 fish during the experimental period of 13 weeks, whereas at 10°C all fish showed a low gonadosomatic index (GSI) at the end of the experiment. Plasma vitellogenin levels were higher in eels kept at 20°C than in eels at 10°C throughout the experiment. However, no significant differences were observed in the plasma testosterone and estradiol-17β levels between groups. Eels pretreated with sGTHs at 10°C for 13 weeks were separated to two different temperature (10 and 20°C) groups, and received the same weekly sGTH injections. In eels transferred to 20°C, plasma vitellogenin levels, GSI and oocyte diameter were increased, but these values were maintained at low levels in eels that remained at 10°C. These results clearly indicate that water temperature is an important factor regulating vitellogenesis in the Japanese eel.     

A new viral epizootic of Anguilla japonica Temminck and Schlegel

Abstract. In 1969, a new kind of epizootic occurred among eels in Japan and virological investigation was initiated. A new virus designated eel virus european (EVE) was isolated and biological, cytological, serological tests and infectivity trials were carried out. In its CPE on RTG-2 cells and additionally in its biological properties and particle size, EVE was found to be similar to infectious pancreatic necrosis virus (IPNV). Serologically, EVE was similar to the ď Honnincthun, France, strain of IPNV. However, infectivity trials showed that EVE and IPNV differed; EVE killed Japanese eels Anguilla japonica but not rainbow trout fry Salmo gairdneri , while IPN virus killed rainbow trout fry but not eels. We consider EVE to be the primary agent causing the new epizootic and propose the name viral kidney disease for the resulting clinical condition.     

日本鳗鲡产卵后生存及其繁育

为证明日本鳗鲡(Anguilla japonica)生活史最后一步一产后鳗的命运,本研究模拟产后的日本鳗鲡继续在海水中养殖,观察其存活率及繁育情况.结果表明,产后鳗在海水中停食约18 d后,体能得到恢复,部分亲鱼开始出现摄食,1个月左右全部恢复摄食,经244 d养殖,雌、雄鳗体质量增加,存活率达94.6%.随后,给产后鳗注射外源性促性腺激素(鲤鱼脑垂体匀浆CPE和人绒毛膜促性腺激素HCG)后激发其退化的性腺(卵巢和精巢)重新发育(与当年银鳗作对照).通过性腺组织切片观察产后鳗和对照鳗性腺发育成熟的全过程及其差异,发现产后鳗起初性腺发育比当年银鳗差,但经多次注射激素后,产后鳗性腺成熟与当年银鳗同步,证明产后鳗生殖细胞对激素的敏感件高.应用17α,20β-双羟孕酮和促性腺激素释放激素类似物(GnRH-A3)使催熟的产后鳗和对照鳗均产卵和排精,并孵化出仔鱼,从而有力地证明,鳗鲡产后虽体质弱,但待体能恢复后能够继续生存和繁殖.本研究旨在探讨利用产后鳗作为今后鳗鲡人工繁殖亲鳗的可行性.     

日本鳗鲡(Anguilla japonica)脾脏小分子抗菌肽的分离纯化

为分离日本鳗鲡脾脏中的抗菌肽,实验采用10 ku和3 ku切向流中空纤维柱对脾脏醋酸粗提物进行分级分离,并结合阳离子交换层析和反相高效液相层析技术对小于10 ku和小于3 ku 2部分样品分别进行分离纯化。结果显示,2种分子量截留纤维柱超滤获得了大于10 ku、小于10 ku和小于3 ku 3部分样品。小于10 ku和小于3 ku蛋白样品抗菌活性较大于10 ku样品强。对小于10 ku样品经阳离子交换层析以及采用pH 9缓冲液进行反相高效液相层析分离纯化,获得一个抗菌肽,质谱分析其分子量为1 391.82 u;对小于3 ku样品经阳离子交换层析并采用pH 9和pH 2两种缓冲液进行反相高效液相层析分离纯化,获得一个抗菌肽,质谱分析其分子量为839.19 u。研究表明,日本鳗鲡脾脏中起抗菌活性的主要成分是一些小分子蛋白。     

Effects of dietary propolis supplementation on growth performance, immune responses, disease resistance and body composition of juvenile eel, Anguilla japonica

This study was conducted to investigate the effects of dietary propolis supplementation on growth performance, immune responses, disease resistance and body composition of juvenile eel, Anguilla japonica, in order to evaluate its bioavailability as a feed additive for this species. A total of 540 fish averaging 7.7?±?0.22?g (mean?±?SD) were randomly distributed into 18 tanks in groups of 30, and each tank was then randomly assigned to one of three replicates of six diets containing 0 (P₀), 0.25 (P_0.25), 0.5 (P_0.5), 1.0 (P₁), 2.0 (P₂) and 4.0 (P₄) % dietary propolis. At the end of 12?weeks of feeding trial, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) of fish fed P_0.5 diet were significantly higher than those of fish fed P₀, P₁, P₂ and P₄ diets (P?<?0.05). These parameters were 148.9%, 0.72% day^?1, 94.4% and 2.9, respectively for fish fed P_0.5 diet. Serum lysozyme activity of fish fed P_0.5 (105.7 units mL^?1) and P₁ (106.0 units mL^?1) diets were significantly higher than those of fish fed P₀, P_0.25, P₂ and P₄ diets. Mucus lysozyme activity of fish fed P₁ (8.4 units 10?cm^?2) diet was significantly higher than those of fish fed P₀, P₂ and P₄ diets. Results indicated that the optimum dietary propolis supplementation levels could be 0.25?C0.5% for optimum growth and feed efficiency, and 0.5?C1% for enhanced immune responses and disease resistance in eel, A. japonica. This study may suggest that the dietary propolis level for the optimum immune responses could be higher than the level for the optimum growth of eel.     

荻芦溪日本鳗鲡的食性研究

本试验于1987年每月或隔月从福建莆田获芦溪采集日本鳗鲡(Anguilla japonica)共256尾进行该种的食性研究。结果显示鳗鲡为典型的肉食性鱼类。其主要食物为蟹类、虾类和鱼类,次要食物为摇蚊科、蜉蝣目和蜻蜓目等的幼虫。鳗鲡的摄食强度随体长增长而增强,在6—7月份最强,年平均空肠率为24.8%。鳗鲡的食物组成随季节不同和个体大小而有所差异。     

水库网箱养鳗试验

鳗鲡Anguilla japonica是出口创汇、国内外市场都十分行销的鲜活商品,利用我国沿海宝贵的天然鳗苗资源,培育鳗种或饲养成鳗已引起产业部门的重视。目前国内外养鳗以流水或静水式水池养鳗为多见,存在着设备投资大,水质不易控制,生产成本高等缺陷。本试验在千岛湖(大型水库)中设置网箱1000余m~2,设计了整套放养技术措施,当年黑仔鳗养成的鳗种平均规格达到74.29克.每平方米产量为34.5公斤,其中16.7%的产量当年达到商品规格,较一般池塘养鳗显示出本轻利重的优越性。水库网箱养鳗的成功亦为水库开展其他高价值鱼类的饲养提供了一条有益的经验。