排序方式： 共有48条查询结果，搜索用时 46 毫秒
31.
星洲银罗非鱼线粒体细胞色素b基因的序列分析 总被引：1，自引：1，他引：0
克隆并测定了星洲银罗非鱼(Oreochromis sp.)细胞色素b基因(cyt b)的全序列,得到全长1 141bp的序列用于分析,用MEGA4.0分析软件与GenBank中的线粒体DNA序列进行序列比较,显示星洲银罗非鱼与其他鱼类的cyt b基因的同源性较高,同源度介于83%~93%间;根据星洲银罗非鱼与莫桑比克罗非鱼、尼罗罗非鱼等12种鱼类的cyt b基因序列构建的系统进化树,初步确定尼罗罗非鱼、莫桑比克罗非鱼为星洲银罗非鱼的父母本。 相似文献
32.
饲喂频率对奥尼罗非鱼仔稚鱼生长、体成分和消化酶活力的影响 总被引：2，自引：0，他引：2
研究在(28.0±1)℃条件下,5种不同饲喂频率对奥尼罗非鱼(Oreochromis niloticus×O.aureus)仔稚鱼的生长、体成分及几种消化酶活力的影响。结果显示:随着饲喂频率的增加,奥尼罗非鱼仔稚鱼的摄食率和特定生长率逐步提高,1次/d组的摄食率和特定生长率显著低于其他组(P<0.05);2、3、4、5次/d组的相对增重率之间差异不显著(P>0.05),但显著高于1次/d组;各组的饲料转化率随饲喂频率的增加而降低;胃蛋白酶、脂肪酶和淀粉酶活力随饲喂频率的增加而显著降低(P<0.05);各组胰蛋白酶变化差异不明显(P>0.05);随饲喂频率的增加,奥尼罗非鱼仔稚鱼的灰分和蛋白质含量无显著变化(P>0.05);脂肪含量显著上升,水分含量则明显下降(P<0.05)。分析表明,奥尼罗非鱼仔稚鱼最适饲喂频率为3次/d。 相似文献
33.
K. Diouf F. Guilhaumon C. Aliaume P. Ndiaye T. Do Chi J. Panfili 《Estuarine, Coastal and Shelf Science》2009
The knowledge of juvenile fish growth in extreme environmental conditions is a key to the understanding of adaptive responses and to the relevant management of natural populations. The juvenile growth of an extreme euryhaline tilapia species, Sarotherodon melanotheron (Cichlidae), was examined across a salinity gradient (20–118) in several West African estuarine ecosystems. Juveniles were collected during the reproduction period of two consecutive years (2003 and 2004) in six locations in the Saloum (Senegal) and Gambia estuaries. Age and growth were estimated using daily otolith microincrements. For each individual, otolith growth rates showed three different stages (slow, fast, decreasing): around 4 ± 0.5 μm d−1 during the first five days, 9 ± 0.5 μm d−1 during the next 15 days and 4 ± 0.50 μm d−1 at 60 days. Growth modelling and model comparisons were objectively made within an information theory framework using the multi-model inference from five growth models (linear, power, Gompertz, von Bertalanffy, and logistic). The combination of both the model adjustment inspection and the information theory model selection procedure allowed identification of the final set of models, including the less parameterised ones. The estimated growth rates were variable across spatial scales but not across temporal scales (except for one location), following exactly the salinity gradient with growth decrease towards the hypersaline conditions. The salinity gradient was closely related to all measured variables (condition factor, mean age, multi-model absolute growth rate) demonstrating the strong effect of hypersaline environmental conditions—induced by climate changes—on fish populations at an early stage. 相似文献
34.
Hybrid tilapia weighing 7.71 g were reared in seawater at 24.0–29.0°C for 8 weeks. The controls were fed to satiation twice
a day throughout the experiment, whereas treatment groups were fed at 0.5%, 1.5% or 3.0% body weight per day for 4 weeks,
and then to satiation for the remainder of the experiment. During the first 4-week period, there was a curvilinear relationship
between growth rate and ration size. Fish fed 0.5% and 1.5% rations displayed compensatory growth response of 2 weeks duration
during realimentation. The weight-adjusted growth rate of fish fed at 3% ration was not significantly different from that
of the controls by the end of the experiment, when none of the treatment groups had caught up in body weight with the controls.
Hyperphagia was observed for the first 2 weeks of realimenatation in fish previously fed at 3% ration, but persisted for the
whole realimentation period in groups previously fed at 0.5% and 1.5% rations. None of the feed restricted groups showed improved
digestibility, feed efficiency, or protein and energy retention efficiency.
Supported by the State Key Laboratory of Freshwater Ecology and Biotechnology of China and Shanghai Fisheries University (Grant
No. 200015). 相似文献
35.
为研究尺寸和镉(Cd2+)质量浓度对罗非鱼积累和转移水环境中Cd2+的影响,用室内培养的方法,选取4种尺寸的罗非鱼,设置不同质量浓度Cd2+的暴露试验,分别测定其半致死率、Cd2+积累量和对Cd2+的转移系数以及罗非鱼的相对增长率.结果表明:不同尺寸的罗非鱼对Cd2+的响应不同,其中,幼龄鱼的LC50浓度最低,体长为31.5±3.4 cm的罗非鱼LC50最高;低质量浓度Cd2+(0.5 mg/kg)处理下,罗非鱼尺寸不同,相同鱼组织对Cd2+的吸收积累量差异显著(P< 0.05),而高质量浓度Cd2+处理时,不同尺寸罗非鱼的同一组织对Cd2+的积累量无显著性差异;除体长27.4±2.9 cm罗非鱼外,相同尺寸的罗非鱼Cd2+转移系数都是低质量浓度显著大于高质量浓度(P< 0.05);高质量浓度Cd2+处理对各种尺寸罗非鱼质量增加的抑制率显著高于低质量浓度Cd2+处理的抑制率.此外,不同Cd2+质量浓度对相同尺寸的罗非鱼也产生不同的影响.因此,罗非鱼的尺寸和Cd2+质量浓度都对罗非鱼积累和转移Cd2+产生影响. 相似文献
36.
海水养残罗非鱼补偿生长的生物能量机制 总被引：25，自引：0，他引：25
1998年4月28日－6月24日和5月20日－7月14日分别在汕头大学南澳海洋生物实验站研究了杂交罗非鱼停喂（简称绝食）或限量投喂（简称限食）后的初偿生长，探讨了杂交罗非鱼补偿生长的生物能量学机制，结果表明，海水养殖杂交罗非鱼在饱食状态下的能量收支为100C＝32.8G 50.8R 15.3F 1.4U，在液复生长期间，对照鱼的食物能和代谢能高于绝食鱼或限食鱼，但其单位体重的食物能，代谢能，生长能，粪能和排泄能均明显低于补偿生长的绝食鱼或限食鱼，绝食或限食后海水养殖杂交罗非鱼的能量收支模式示发生明显变化。 相似文献
37.
尼罗罗非鱼对两种网目定置网片反应特性的比较 总被引：3，自引：0，他引：3
本文就尼罗罗非鱼对两种网目(12.6和8.4cm)定置网片的反应特性进行了比较研究。结果表明:在两网片邻近区域内的分布尾次数较中间区域为少;随着时间推移,其分布重心有移向大网目网片一侧的倾向。此外,罗非鱼对两种网目网片的趋网、碰网、穿网尾次数及趋网、碰网、穿网时刻也有一定的差异。 相似文献
38.
采用6种等蛋白质(34.4%)、等能量(16.10MJ/kg)试验日粮,研究了尼罗系吉富罗非鱼幼鱼实用日粮中蔗糖糖蜜替代小麦次粉的养殖效果与血糖代谢变化。结果表明,56d试验期间各试验组鱼均无死亡;蔗糖糖蜜替代小麦次粉40%—100%日粮组鱼的摄食量、特定生长率、饲料效益和蛋白效益均高于小麦次粉组鱼,当蔗糖糖蜜100%替代小麦次粉时,其摄食量、特定生长率和饲料效益蛋白效益比均显著性上升(P<0.05)。各试验组鱼鱼体营养成分(蛋白质、脂肪、灰分和水分)和肝体指数无显著性差异(P>0.05),肝脏结构正常。蔗糖糖蜜组鱼血浆中血糖、总蛋白、胆固醇、甘油三酯含量明显高于小麦次粉组鱼(P<0.05)。本试验结果认为,蔗糖糖蜜在尼罗系吉富罗非鱼幼鱼实用日粮中可以完全替代小麦次粉,蔗糖糖蜜对尼罗系吉富罗非鱼幼鱼具有较好的生长效益、节约日粮蛋白质效益和适口性,其主要原因与摄食蔗糖糖蜜后尼罗系罗非鱼幼鱼产生的较长时间高血糖现象有关。 相似文献
39.
低温贮藏罗非鱼微生物学质量变化特性和保藏期 总被引：14，自引：0，他引：14
进行了罗非鱼在0,5,10,15℃贮藏过程中的微生物学质量变化特性和高品质期、货架期的研究,并对其特定腐败菌假单胞菌、细菌总数、VBN与感官评价的一致程度进行了探讨。结果表明,罗非鱼在0～15℃温度区域是淡水鱼中鲜度下降慢的鱼种,在0,5,10,15℃贮藏中,罗非鱼的高品质期分别为11,6,3和1.5d,货架期分别为20,9.5,5和2.5d。高品质期和货架期终点的假单胞菌数平均为(6.27±0.23)Log10cfu·g-1和(7.70±0.11)Log10cfu·g-1,显示了假单胞菌计数与罗非鱼的感官鲜度及保藏期具有较可靠的一致性。高品质期和货架期终点的细菌总数平均为(6.84±0.60)Log10cfu·g-1和(8.08±0.41)Log10cfu·g-1,VBN值平均为(11.8±1.38)mg·100-1·g-1和(20.1±1.66)mg·100-1·g-1,均无显著差异(P>0.05),表明细菌总数和VBN作为罗非鱼低温贮藏的鲜度指标与感官鲜度评价有较好的一致性。 相似文献
40.
Elsayed M.YOUNIS 《中国海洋湖沼学报》2015,33(3):696-704
The effects of rearing temperature on white muscle and hepatic phosphofructokinase(PFK),pyruvate kinase(PK),lactate dehydrogenase(LDH),aspartate aminotransferase(AST) and alanine aminotransferase(ALT) were examined in fingerlings of blue tilapia,O reochromis aureus. The experiment was conducted for 14 weeks at temperatures of 18,22,26,30,and 34°C. The activity of the glycolytic enzymes PFK,PK,and LDH in white muscle increased significantly with increase in water temperature. A reverse trend was observed for these enzymes in the liver,except for LDH,which behaved in the same manner as in white muscle. Cytosolic AST and ALT activity increased in both white muscle and liver in response to warm thermal acclimatization,while a reduction in mitochondrial AST and ALT activity was noticed at high temperatures in comparison with those at a lower temperature. 相似文献