吡啶甲酸铬对吉富罗非鱼生长、饲料利用和非特异性免疫功能的影响

本试验研究饲料不同水平吡啶甲酸铬对其生长、饲料利用,体成分、血液生化指标和非特异性免疫功能的影响。600尾吉富罗非鱼分为5个处理组,每个处理各设4个重复,每重复30尾鱼。每个处理铬添加量分别为0、0.4、0.8、1.2 mg/kg和10.0 mg/kg,在0.38 m3玻璃纤维钢桶中用开放式流水养殖,饲养8周。结果表明,饲料中添加吡啶甲酸铬对吉富罗非鱼的增重率、特异生长率、饲料系数、蛋白效率及蛋白质沉积率均有显著影响(P<0.05)。当铬添加量为0～0.8 mg/kg时,随着添加量增加,可显著提高吉富罗非鱼增重率、特定生长率、蛋白质效率和蛋白质沉积率(P<0.05),显著降低饲料系数(P<0.05),但对成活率和肝体比无显著影响(P>0.05);当饲料中添加为1.2 mg/kg～10.0 mg/kg时并未能进一步提高罗非鱼的生长和饲料利用。同时,铬添加水平为0～0.8 mg/kg,随着添加水平增加,显著提高吉富罗非鱼全鱼的蛋白质和磷含量(P<0.05),显著降低全鱼水分、脂肪和灰分含量(P<0.05),并显著提高吉富罗非鱼血清总蛋白含量以及肝胰脏AKP、ACP和LZM的活性(P<0.05),显著降低血清葡萄糖含量(P<0.05),但对血清胆固醇和甘油三酯含量及肝胰脏T-SOD活性无显著影响(P>0.05)。当饲料中添加铬1.2 mg/kg和10.0 mg/kg,除了显著降低肝胰脏AKP活性外(P<0.05),对血清生化指标和肝胰脏非特异性免疫酶活性无显著影响(P>0.05)。综合生长、饲料利用、体组成成分、血液生化指标和肝胰脏非特异性免疫酶活性的影响结果表明,对于0.91～4.93 g吉富罗非鱼,饲料中以吡啶甲酸铬的形式添加0.8～1.2 mg/kg铬为宜。     

CdSe/ZnS量子点对雄性尼罗罗非鱼红细胞微核率及核异常率的影响

[目的]探究CdSe/ZnS量子点对尼罗罗非鱼(Oreochromis niloticus)的遗传毒性。[方法]分别设空白对照组、NaCl对照组和Cd2+对照组以及浓度分别为20、200、2 000和4 000 nmol/L 4个量子点处理组,以腹腔注射方式对雄性尼罗罗非鱼体进行暴露,暴露后1、4、7、14及28 d进行静脉取血制作血涂片,通过微核率、核异常率及总核异常率检测其遗传毒性。[结果]各NaCl对照组与空白对照组均无显著差异。暴露1 d后各量子点处理组产生的微核率达到峰值后总体呈下降趋势。Cd2+对照组的微核率在整个试验期间均与NaCl对照组有显著差异,其微核率14 d达到峰值。核质外凸和核质内凹是核异常的主要类型,核固缩及不均等缢裂细胞类型在前期易被诱导。[结论]量子点外壳及表面修饰基团的综合作用对鱼体有诱导微核率及核异常率增加的效应,但随着时间的推移,罗非鱼能逐步解除该负面效应,由此推测鱼体最终能解除由QDs诱导的遗传毒性。     

光照周期对尼罗罗非鱼幼鱼昼夜节律调节的作用

为了研究尼罗罗非鱼幼鱼游泳行为在不喂食时是否存在昼夜节律和光照周期的调节作用,设计了光周期为光照(L)∶黑暗(D)=12 h∶12 h,持续的黑暗(DD),持续的光照(LL),光周期为L∶D=6 h∶6 h和光周期为L∶D=2 h∶2 h。结果表明:(1)光周期为L∶D=12 h∶12 h时,尼罗罗非鱼具有明显的昼夜节律,昼夜节律周期为(24. 3±0. 2) h;(2)尼罗罗非鱼的昼夜节律在持续的黑暗和光照下仍然存在,分别为(25. 1±1. 1) h和(25. 6±1. 0) h;(3)光周期为L∶D=6 h∶6 h时,尼罗罗非鱼仍具有明显的昼夜节律(12. 6±0. 5) h;(4)在光周期为L∶D=2 h∶2 h时,尼罗罗非鱼的昼夜游泳行为仍具有明显的昼夜节律,节律周期为(4. 0±2. 0) h。这些结果表明,尼罗罗非鱼具有以24 h为周期的内源性生物钟,但相比与外源性光照调控,内源性的生物钟对罗非鱼的调控较弱,外源性的光照周期才是调节尼罗罗非鱼幼鱼昼夜行为节律的主要因素。     

吉富罗非鱼对饲料精氨酸的需要量

以饲料精氨酸水平分别为0.67%、0.94%、1.24%、1.58%、1.86%和2.11%的6种等氮等能的半纯化饲料(粗蛋白质含量30.21%,总能17.77 MJ/kg),投喂初始体重为(81.52±2.00)g的吉富罗非鱼60 d,考察饲料精氨酸水平对吉富罗非鱼生长性能、饲料利用、体成分、血清生化指标和非特异性免疫指标的影响,以期获得吉富罗非鱼对饲料精氨酸的最佳需要量。每种饲料投喂3个网箱,每个网箱放养15尾鱼。结果表明:随着饲料精氨酸水平的升高,吉富罗非鱼的增重率、特定生长率、蛋白质效率以及蛋白质沉积率均呈现先上升后下降的趋势,并均在1.58%组达到最高值,与其他组差异显著(P0.05);饲料系数、肝体比、脏体比则呈现先下降后上升的趋势,饲料系数在1.58%组达到最低值,与其他组差异显著(P0.05);全鱼粗脂肪和肌肉粗灰分含量的变化趋势与饲料系数相似,肌肉粗脂肪呈现与增重率和特定生长率相似的变化趋势,而全鱼粗灰分和肌肉粗蛋白质含量则呈先上升后稳定的趋势。饲料精氨酸水平对吉富罗非鱼的肥满度,全鱼水分、粗蛋白质及肌肉水分含量无显著影响(P0.05)。肌肉中各氨基酸(除酪氨酸、甘氨酸、丙氨酸外)、必需氨基酸、总氨基酸含量均随饲料精氨酸水平的升高呈先上升后下降的趋势。饲料精氨酸水平显著影响血清中谷草转氨酶、谷丙转氨酶活性及总胆固醇、甘油三酯、总蛋白、尿素氮和葡萄糖含量(P0.05),也显著影响肝脏和血清中总超氧化物歧化酶、总一氧化氮合酶和溶菌酶的活性(P0.05)。以增重率、饲料系数和蛋白质效率为主要评价指标,通过二次回归分析可知,吉富罗非鱼对饲料中精氨酸需要量为1.51%~1.58%,占饲料蛋白质的4.99%~5.25%。     

用RAPD分析对罗非鱼遗传变异的研究及其对杂种优势的应用

应用ＲＡＰＤ技术检测了一个奥利亚罗非鱼养殖群体和湘湖、美国和沙市三个尼罗非鱼和尼罗罗非鱼在群体内或群体间存在遗传差异。ＯＰＺ０６、Ｐ）Ｚ１０、ＯＰＺ１２和ＯＰＺ１９四个引物都有一个扩增片段具有种的特异性,可以作为临别尼罗罗非鱼和奥利亚罗非鱼的遗传标记。群体内遗传相似性指数（Ｓ）表明,湘湖、美国和沙市三群体尼罗罗非鱼都保留了较高水平的遗传变异（Ｓ分别为０．７９８、０．７９５和０８２４）,而奥利亚罗非     

Enhancing Growth of Common Carp, Rohu and Mozambique Tilapia through Plant Substrate: The Role of Bacterial Biofilm

Experiments were conducted to enhance the growth of common carp (Cyprinus carpio), rohu (Labeo rohita) and Mozambique tilapia (Oreochromis mossambicus) through use of sugarcane bagasse as substrate. Bagasse was suspended in water with or without supplementation with fertilizers. Bagasse supplemented with cattle dung and urea favoured higher zooplankton production and significantly (p < 0.05) increased fish growth by over 50% compared to bagasse or fertilizers on their own. This higher production of fish is attributed to bacterial biofilm promoted on the substrate which, apart from forming food for zooplankton and fish, contributed to improved water quality by lowering ammonia.     

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.     

氨氮与拥挤胁迫对吉富品系尼罗罗非鱼幼鱼生长和肝脏抗氧化指标的联合影响

采用中心复合试验设计(CCD)和响应曲面方法(response surface methodology,RSM),探讨了氨氮(0.02 ～ 2.00 mg/L)和养殖密度(1～5尾/10 L)对吉富罗非鱼幼鱼生长和肝脏抗氧化指标的联合影响.结果表明,本试验条件下,氨氮和养殖密度的一次与二次效应对特定生长率有显著影响(P＜0.05),随着氨氮或养殖密度的上升,特定生长率呈先上升后下降的变化.氨氮与养殖密度之间存在互作效应(P＜0.05),氨氮浓度为0.02 ～0.20 mg/L,养殖密度在1～2尾/10 L时,幼鱼特定生长率较高;而氨氮浓度高于0.20 mg/L,养殖密度在3尾/10 L左右时,生长速度较快.肝脏丙二醛(MDA)含量随氨氮浓度和养殖密度的上升而上升,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活力呈先上升后下降的变化.氨氮与养殖密度的一次效应对MDA含量和两种酶活力均有显著影响(P＜0.05),二次效应对两种酶活力的表达有极显著影响(P＜0.01);氨氮与养殖密度对CAT活力有互作效应,高浓度氨氮与高养殖密度环境会抑制SOD和CAT活力的表达.因子与响应值间二次多项回归方程的决定系数分别达到0.972 4、0.913 2、0.938 9和0.969 2(P＜0.01),可用于预测;氨氮效应对生长和抗氧化酶活力的影响较养殖密度明显.建议在罗非鱼的养殖过程中合理安排好养殖密度,保持溶氧充足,降低氨氮胁迫,提高罗非鱼的生长与抗病力.     

盐酸诺氟沙星在奥尼罗非鱼体内的生物利用度研究

采用高效液相色谱法分别测定静脉注射和混饲口灌奥尼罗非鱼(Oreochromis aureus×O.niloticus)盐酸诺氟沙星后鱼体血液中该药含量变化,用3P97药动学软件分析药动学参数,计算生物利用度.结果表明,在(25±1)℃水温下,以10 mg/kg剂量对奥尼罗非鱼静脉注射和混饲口灌盐酸诺氟沙星,静脉注射药时...     

一个奥利亚罗非鱼雌性特异性SCAR标记的建立

以奥利亚罗非鱼Oreochromis aureus为实验材料,通过对800多条随机引物的筛选,获得了1个奥利亚罗非鱼雌性特异性的、长度为1 488 bp的RAPD标记片段RAPD71699-1488,经琼脂糖凝胶电泳后回收、克隆、测序,并根据测序结果设计PCR特异引物,再经PCR条件优化,成功地将该RAPD标记片段转化为实验结果稳定、操作简便的SCAR标记,即SCAROaF1488。采用双重PCR技术,以mtDNA 16S rRNA基因片段为PCR扩增阳性对照,对该标记的有效性在两个群体共200个个体(雌、雄各100个)中进行验证。结果显示,标记检测结果与表型性别的符合度为100%。SCA-ROaF1 488标记的获得为奥利亚罗非鱼遗传性别鉴定及标记辅助选择提供了有效工具,为深入研究鱼类性别相关基因及性别决定机制提供了重要线索和新的思路。