溢多酶P-8901对罗非鱼生长性能的影响

在罗非鱼基础饲料(对照组)中分别添加不同比例溢多酶P-8901,探讨溢多酶P-8901对罗非鱼生产性能的影响。结果表明,在罗非鱼鱼种试验中,与对照组相比,添加100 g.t-1、150 g.t-1、180 g.t-1溢多酶P-8901试验组的饲料效率分别比对照组提高8.48%、7.89%和9.03%(P<0.05);增重率分别提高9.00%、10.33%和9.50%(P<0.01);生长率分别提高4.00%、4.48%和4.13%(P<0.01);蛋白质效率分别提高8.38%、7.75%和8.84%(P<0.01)。养成试验中,添加100 g.t-1、150 g.t-1、180 g.t-1溢多酶P-8901试验组饲料系数分别比对照组提高4.28%、5.41%和6.56%(P<0.05);增重率分别提高6.31%、7.94%和8.82%(P<0.01);生长率分别提高3.68%、4.72%和5.26%(P<0.01);蛋白质效率分别提高5.36%、7.53%和9.24%(P<0.01)。饲养结果表明,添加溢多酶P-8901能够明显提高饲料利用率,提高罗非鱼的生长性能,尤其对鱼种的效果比养成阶段更好。     

世界罗非鱼捕捞和养殖的动态特征研究

罗非鱼类原产于非洲和东南亚，具有生长迅速、耐粗食、肉质好等优点，目前已成为世界渔业的重要鱼品。世界罗非鱼生产以捕捞和养殖两种方式进行。九十年代，世界罗非鱼养殖业迅速崛起，养殖产量开始逐渐超过捕捞产量。世界罗非鱼养殖主要品种是尼罗罗非鱼。与此同时，世界罗非鱼的加工与贸易，亦有比较快速的发展。根据1981—2002年FAO关于罗非鱼捕捞和养殖的统计资料，分析了世界罗非鱼产业的动态特征，目前中国罗非鱼养殖年产量世界第一，有必要继续关注和提升中国罗非鱼养殖业发展的世界地位。     

三黄连散预防罗非鱼链球菌病临床应用研究

在开展三黄连散对人工感染罗非鱼无乳链球菌病预防效果研究的基础上,进一步验证以每千克饲料中添加13.2 g的三黄连散为推荐剂量,在生产中大面积应用的临床效果及安全性。设立三黄连散试验组、中药对照组和空白对照组3个组,每组300尾罗非鱼,连续用药7 d后,每组随机取30尾,测定增重率、器官指数、血液生理生化指标和肝脏抗氧化指标。用药后第8天,采用同居感染的方法感染鱼群,于感染后第14天计算保护率。结果表明,给药7 d后,与空白对照组相比,三黄连散试验组罗非鱼的增重率明显提高,器官指数和多项肝脏抗氧化指标均明显升高,血液生理生化指标总体无明显异常,预防无乳链球菌感染的保护率为43.67%。综上提示,三黄连散能够提高罗非鱼机体抵抗力,降低无乳链球菌感染罗非鱼的死亡率。     

Phenotypic and genotypic characterization of Streptococcus spp. isolated from tilapia (Oreochromis spp.) cultured in river-based cage and earthen ponds in Northern Thailand

Streptococcus spp. are major pathogenic bacteria associated with massive mortality in tilapia. This study investigated the phenotypic and genotypic characterization of Streptococcus agalactiae (GBS) and Streptococcus iniae (S. iniae) isolated from tilapia in river-based floating cage and earthen pond farms in northern Thailand. Isolates were identified by biochemical and molecular analyses. Capsular typing, enterobacterial repetitive intergenic consensus polymerase chain reaction and multilocus sequence typing were performed to investigate the genetic relatedness. Six and one isolates were confirmed as GBS and S. iniae, respectively. All Streptococcus spp. isolates were obtained from 4 river-based cage farms (4/33), while samples collected from earthen pond farms (N = 28) were negative for streptococcosis. All GBS with serotype Ⅲ and sequence type (ST) 283 was observed. The β-haemolytic GBS isolates were resistant to five antimicrobials, while the S. iniae was susceptible to all antimicrobials. This study indicates both GBS and S. iniae are the major bacterial pathogens responsible for streptococcosis infection in farmed tilapia of northern Thailand with GBS as dominant species. This survey highlights that the river-based cage farms seriously impact on the healthy development of the tilapia industry.     

Modeling and implementing the use of aeration to increase water temperature and dissolved oxygen in greenhouse aquaculture cages

In this study, an unique bamboo floating cage was built in order to heat the water used for rearing Nile tilapia (Oreochromis mossambicus x O. niloticus) and climbing perch (Anabas testudineus, Bloch) in Northern Thailand during the colder rainy and winter seasons. This special greenhouse fish cage (SGFC) was covered with polyethylene to heat the surface air with solar energy, and insulated to prevent heat loss. The water temperature at depths of 0.1, 0.3 and 0.8 m was modeled and measured. In various trials, the cages were aerated with and without heated air from the surface. It was found that the thermal efficiency of the SGFC integrated with hot air aeration at a water depth of 0.80 m was 32.65 %. Throughout the day, the average water temperature was 31.82 ± 0.68 °C, which was 0.76 °C higher than the water temperature outside the experiment, and the amount of oxygen in the water of 11.35 ± 0.13 mg/l. The SGFC can produce one extra fish harvest per year when compared with regular fish cages. Development equations to describe the thermal model were used for predicting the water temperature in the SGFC and thus validating the model. Moreover, the economic analysis of the SGFC found that the payback period was one year, seven months and fourteen days.     

双酶法水解罗非鱼下脚料制备降血糖肽的工艺研究

以水解度和α-葡萄糖苷酶抑制率为评价指标,确定双酶复合水解罗非鱼下脚料的方案,并通过单因素试验和正交试验进行优化,最后得到最适酶解工艺参数为先在碱性蛋白酶在温度50℃,加酶量10000 U/g,pH值9.5,底物质量分数6%条件下水解;再在胰蛋白酶在温度37℃,加酶量10000 U/g,pH值8条件下水解100 min。此工艺条件下罗非鱼下脚料水解度、水解产物的α-葡萄糖苷酶抑制率分别为48.26%和41.46%。     

Effects of Dietary Protein Levels on Gonad Maturation, Size and Age at First Maturity, Fecundity and Growth of Nile Tilapia

Six-week-old Nile tilapia (Oreochromis niloticus) fry with an average weight (SD) of 0.51(0.2) g were reared for 140 days on five formulated, isocaloric diets of different protein levels (25, 30, 40 and 45% by dry weight). Fish fed diets of higher protein levels (40 and 45%) showed better growth and feed conversion ratio than those on lower protein levels. Fast-growing fish matured earlier. Maturation rate was affected by the dietary protein levels. Males matured earlier than females: the first mature males were recorded when they were 14 weeks old, whereas the females matured after 18 weeks. In both sexes, mean percentage of mature fish rose with increasing dietary protein level, the percentage of mature males being higher than that of the females. Similarly, the percentage of mature fish rose with the increasing age of fish, with more than 50% males and females mature at the age of 22 and 24 weeks, respectively, the exception being the 25% protein diet fed fish, where the percentage of mature fish was below 50%. In all treatments, spawning was initiated when the fish were 22 weeks old. Smallest size at spawning of males and females was 9.2 cm (13.1 g) and 8.1 cm (8.9 g), respectively, and dietary protein levels influenced the size of fish at first maturity. For both sexes, no difference was found in the gonado-somatic index (GSI) among different treatments. Fecundity increased with increasing dietary protein levels, but significant differences were found only between 40–45% and 25–35% dietary protein levels. The relative fecundity (eggs g^–1 female) was higher at the lower dietary protein levels (25–35%) than at the higher dietary protein levels (40–45%). The dietary protein levels did not have any significant influence on the size and weight of mature eggs. The chemical composition of fish and mature ovaries was significantly influenced by the dietary protein level.     

盐度对台湾红罗非鱼能量收支的影响

在水温２８℃的条件下,不限量投喂颗粒饵料,测定了台湾红罗非鱼在淡水和盐度为７,１４,２、,２８和３５％的能量收支。结果表明;盐度对台湾红罗非鱼的特定生长率,转化效率和最大摄食率均有显著影响,盐度为１４‰时,特定生长率和转化效率均达到最高水平,分别为１．４３％和５１．８８％,此时,摄食率也达了大,每天为体重的２．７５％,盐度对吸收效率无显著影响,对物质,蛋白质和能量的吸收效率的平均值分别为６２．９８     

温度和盐度对吉富品系尼罗罗非鱼受精率和孵化率的联合影响

采用中心复合设计和响应曲面方法研究了温度(T,℃)和盐度(S)对吉富品系尼罗罗非鱼人工受精率(FR,％)和孵化率(HR,％)的综合影响.设定的温度范围为20～34,盐度范围为0～18.建立了温度、盐度与受精和孵化之间关系的定量模型,并通过分析明确了温度与盐度的最优组合.结果表明,吉富罗非鱼在温度与盐度较高或较低范围内受精率与孵化率都处于较低水平.温度和盐度的一次与二次效应对受精与孵化均有极显著的影响(P＜0.01).温度与盐度二者间协同效应不显著(P＞0.05).建立了吉富罗非鱼受精率与孵化率的多项式方程,复相关系数分别达到了0.957 8和0.960 1 (P＜0.01),可以用于预测吉富罗非鱼的受精率和孵化率.利用统计优化技术明确,在温度27.14℃,盐度8.95时,罗非鱼最佳的受精率为80.8％,孵化率为77.63％.本研究旨在考察温度与盐度同时变化对吉富罗非鱼受精率与孵化率的影响,探讨最佳温度－盐度组合以增加吉富罗非鱼苗种产量.     

不同盐度下“吉丽”罗非鱼(尼罗罗非鱼♀×萨罗罗非鱼♂)NKCC1a mRNA的组织特异性表达

应用实时荧光定量PCR技术(qRT-PCR),以"吉丽"罗非鱼[尼罗罗非鱼(Oreochromis niloticus,♀)×萨罗罗非鱼(Sarotherodon melanotheron,♂)]为材料,研究NKCCla基因表达的盐度-组织特异性.研究结果表明:(1)NKCCla基因mRNA表达量存在显著的组织特异性,在低于25盐度环境中,NKCCla mRNA在鳃、肝、肾及肠中均有表达;当盐度从0提高到48时,表达量在鳃中与盐度变化呈高度正相关(R＞0.9,P＜0.01),在肠和肾中与盐度变化呈负相关(P≈-0.7,P＜0.05),但在肝中则不受盐度变化的影响.(2)当盐度提高到64,NKCCla基因mRNA表达最在鳃和肠3 h后达最高值,5 h后下降,前后变化差异显著(P＜0.05);表达量在肝中则是在5 h后达最高值,变化差异也显著(P＜0.05);表达量在肾中持续下降,但差异不显著.以上结果揭示,在盐度高于25的环境中,"吉丽"罗非鱼主要由鳃组织的NKCCla排出多余的离子以维持鱼体的水盐平衡,由此认为鳃组织在"吉丽"罗非鱼高渗透压调节中起最主要作用.