共查询到20条相似文献,搜索用时 14 毫秒
1.
Treatment of one-day-old yolksac larvae of tilapia ( Oreochromis mossambicus), by immersion in cortisol solution for two weeks, significantly enhanced growth. The standard length, tail length, head width and wet weight showed dose-dependent increases at concentrations of cortisol (hydrocortisone) from 0.05 ppm to 0.5 ppm, with no further increase at 1.0 ppm. However, cortisol at 5.0 ppm retarded the growth of the larvae without causing any morphological abnormality. Yolk absorption and the onset of free-swimming activity in the larvae were also accelerated by cortisol treatment. 相似文献
2.
选取4种不同品系罗非鱼, 分别为吉富罗非鱼(Oreochromis niloticus)、奥尼罗非鱼(O. niloticus×O. aureus)、红罗非鱼(O. nilotica♂× O. mossambica♀)和奥利亚罗非鱼(O. aureaus)。在26℃水温下饲养3周后, 选取规格基本一致的罗非鱼(体质量50.73 g±4.23 g)进行低温驯化实验。水温以3℃/d的速度从26℃降至8℃, 分别于水温为26℃、20℃、14℃和8℃时进行采样, 比较不同驯化阶段4种不同品系罗非鱼血清皮质醇和免疫相关指标的变化规律。结果表明, 与26℃时的免疫指标相比, 水温降至8℃时, 吉富与红罗非鱼血清皮质醇水平显著升高; 然而血清C3、C4、IgM以及头肾C型溶菌酶mRNA水平显著下降(P<0.05), 血清中高皮质醇水平对鱼体的免疫产生了抑制作用。水温为8℃时, 奥尼罗非鱼血清皮质醇、IgM和补体C3以及头肾抗菌肽mRNA水平显著升高; 奥利亚血清皮质醇、C4和IgM以及头肾C型溶菌酶mRNA水平与26℃时相比无显著差异, 然而血清溶菌酶与C3水平降低。驯化实验结束后, 比较了4种不同品系罗非鱼在8℃水温下48 h内的累积死亡率。吉富与红罗非鱼组累积死亡率较高, 分别达到43.3%和40.0%; 奥尼罗非鱼其次, 为23.3%; 奥利亚罗非鱼最低, 为20.0%。较高的血清IgM和头肾溶菌酶和抗菌肽mRNA水平可能有助于提高奥尼和奥利亚罗非鱼的抗低温应激能力, 增加低温时的成活率。本研究通过分析4种品系罗非鱼不同驯化阶段血清皮质醇和免疫相关指标, 探讨不同品系罗非鱼在低温驯化过程中的免疫保护机制, 旨在为下一步抗低温新品系罗非鱼的选育提供理论依据。 相似文献
3.
The tilapias are one of the most important fish groups in aquaculture.In spite of this, relatively few workers have attempted to establish the feedration that would suffice for their maintenance. The results that they present,moreover, do not match, which may be attributed as much to differences inanalytical procedure as to experimental protocol. In this work, previous dataonred tilapia by the late Dr was therefore reassessed in order to arrive at more reliableresults. The dataset was based on fish between 15 and 20g wet body mass givenvarious levels (0, 0.5, 1 & 3% of body mass) of three protein level diets(low: 13.1%, LP; medium, 28.7%, MP; high: 43.9%, HP) at two temperatures (20.9& 24.3 °C). The required feeding level to maintain drybodyweight was 2.52, 2.81 and 7.05 g kg –0.8 fishweight per day for the HP, MP and LP diets respectively at the highertemperature and 1.92, 2.32 and 5.04 g kg –0.8day –1 at the lower temperature. This gave rise to anaverage Q 10 coefficient of 2.22. The required feed quantity tomaintain body protein or body energy, however, was in most cases higher, partlybecause the fish initially had high protein and lipid and low ash content.Comparisons with other maintenance estimates for tilapia were also made and thereasons for discrepancies between the results obtained here and elsewherediscussed. 相似文献
4.
A comparison of composition and sensory evaluation were performed on fillets of Oreochromis niloticus (wild type) and red hybrid tilapia (RHT) (Florida red tilapia ♂× red O. niloticus♀). Fifty male tilapia, 25 O. niloticus (initial weight 159.3 g) and 25 red hybrid (initial weight 132.4 g), were placed in each of three 2.0 m 3 volume tanks. The fish were fed a commercial feed containing 35.9% crude protein during the 120‐day experimental period and then killed in cold water (3°C). All the fish were filleted. Twelve fillets from each treatment were used for proximate analyses, five fillets from each treatment were used for fatty acids analyses and the remaining fillets were used for sensory evaluation. The compositional analyses showed similar moisture, true protein and ash content in both genetic groups, but a lower crude fat content was measured in the red hybrid fillets (0.70%) compared with that of O. niloticus fillets (0.97%). No differences between O. niloticus and the red hybrid were observed in their fillet profile of fatty acids. In the sensory evaluation test, a difference in fillet flavour between both genetic groups was perceived. Of the 112 consumers in the preference test, 81.2% perceived a difference in fillet flavour between the two tilapias, with a general preference for the red hybrid over the wild‐type O. niloticus. The benefits of cultivating a RHT with a low lipid content are discussed. 相似文献
5.
A novel virus, tilapia lake virus (TiLV), has been identified as a key pathogen responsible for disease outbreak and mass mortality of farmed tilapia. We used a deterministic susceptible‐infectious‐mortality (SIM) model to derive key disease information appraised with published TiLV‐induced cumulative mortality data. The relationship between tilapia mortality and TiLV exposure dosages was described by the Hill model. Furthermore, a disease control model was proposed to determine the status of controlled TiLV infection using a parsimonious control reproduction number ( RC)‐control line criterion. Results showed that the key disease determinants of transmission rate and basic reproduction number ( R0) could be derived. The median R0 estimate was 2.59 in a cohabitation setting with 2.6 × 10 5 TCID50 fish ?1 TiLV. The present RC‐control model can be employed to determine whether TiLV containment is feasible in an outbreak farm by quantifying the current level of transmission. The SIM model can then be applied to predict what additional control is required to manage RC < 1. We offer valuable tools for aquaculture engineers and public health scientists the mechanistic‐based assessment that allows a more rigorous evaluation of different control strategies to reduce waterborne diseases in aquaculture farming systems. 相似文献
6.
用RAPD 技术研究奥利亚罗非鱼和尼罗罗非鱼杂交子代和亲本的遗传关系及其在杂种优势中的应用。在所用的16 个随机引物中,有11 个引物在罗非鱼亲代和杂交子代间呈现多态。遗传相似性指数和遗传距离的计算结果表明,正交子代( 尼罗罗非鱼♀×奥利亚罗非鱼♂) 在遗传关系上界于亲代之间,不表现出明显的倾向性;而反交子代( 奥利亚罗非鱼♀×尼罗罗非鱼♂) 却与母本奥利亚罗非鱼极其相似。说明正、反交子代与两亲本遗传相似性有明显的不同,表明遗传性状介于两亲本之间的杂交子代更有可能形成显著的杂种优势。同时发现,扩增片段OPA071900 、OPA07960 、OPZ14720 和OPZ14600 可以作为鉴别尼罗罗非鱼、奥利亚罗非鱼和正交子代的遗传标记。 相似文献
7.
A comparison was made of some productive traits of Stirling Nile tilapia (wild type) ( Oreochromis niloticus, Linnaeus) and red hybrid tilapia (Florida red tilapia× Stirling red O. niloticus) males during a 98‐day grow‐out period. Twenty‐two males from each genetic group with initial weights of 139.0 g for O. niloticus and 207.3 g for the red hybrid were placed in triplicate tanks. The fish were fed with a feed containing 36.8% crude protein. Survival was 97.0% for the red hybrid and 83.3% for O. niloticus. Daily individual weight gains were 2.95 and 2.50 g and final body weights were 473.0 and 348.8 g for the red hybrid and O. niloticus respectively. Fillet yield was similar for both the species, with 33.4% for the red hybrid and 32.0% for O. niloticus. Fresh fillet lipid content was perceptibly less in the red hybrid (0.33%) than in O. niloticus (2.07%). Some benefits of a red low‐fat tilapia genotype are discussed. 相似文献
9.
A 10‐week feeding trial was conducted to investigate the interaction between tilapia genotype and dietary protein level on the growth, feed utilization efficiency and body composition of Nile tilapia [ Oreochromis niloticus L., F 9 generation of genetically improved farmed tilapia (GIFT) strain] and red hybrid tilapia ( Oreochromis sp.). Two isoenergetic diets (15.5 kJ g −1 diet) containing 25% or 35% crude protein were formulated and fed to triplicate groups of tilapia (12.8±0.2 g) at a fixed daily ration of 4% of their body weight. The growth performance of the GIFT tilapia fed 25% or 35% dietary protein was significantly higher ( P<0.05) compared with red tilapia at either protein level. Increasing the dietary protein level by 10% led to a further 10% increase in the final weight of GIFT tilapia but no further increase was observed in the weight gain of red tilapia. Growth was influenced by the interaction between diet and tilapia genotype. Feed conversion ratios were 14% and 33% better in GIFT tilapia compared with red tilapia fed the 25% or 35% protein diet respectively. Protein efficiency ratio and net protein utilization were influenced by both diet and tilapia genotype, but not the interaction between the two. The apparent digestibility coefficients of dry matter and protein did not differ significantly between the two diets and tilapia genotypes but lipid digestibility was 1.2–4.7% higher for the GIFT tilapia. Tilapia whole‐body protein content was significantly influenced by both diet and tilapia genotype. The higher growth potential, better feed utilization efficiency and higher body protein content of GIFT tilapia compared with red tilapia should have a positive impact on tilapia farming in terms of production costs. 相似文献
10.
研究了奥尼罗非鱼和吉富罗非鱼对低温和重金属的抗逆性。抗冻性实验结果表明,奥尼罗非鱼的抗冻性优于吉富罗非鱼。抗冻性较好的奥尼罗非鱼对重金属的抗逆性研究结果表明,在相同浓度的不同重金属作用下,奥尼罗非鱼幼苗对受试3种重金属离子(Pb2+、Cr6+、Cu2+)的抗逆性均随着作用时间的延长而下降。在相同条件下,对受试3种重金属离子的抗逆性:Cr6+Cu2+Pb2+。 相似文献
11.
为了探究红罗非鱼越冬期体色变异的分子机制,实验构建了其2种体色(正常粉红体色和变黑体色)皮肤组织的小RNA文库,每组4个重复,组装后平均每组分别获得12 190 544和11 891 890条过滤后的读长(clean reads),获得miRNA成熟序列669个,其中337个是已知的miRNAs。鉴定出越冬期变黑体色相对于正常粉红体色鱼的差异表达miRNAs 26个,其中上调11个,下调15个,且12个为已知的miRNAs,可能在红罗非鱼越冬期体色变异过程中发挥重要作用。富集分析发现了大量代谢和体色调控相关的通路。研究表明,红罗非鱼越冬期的体色变异可能是色素细胞的增殖和迁移形成的,与代谢相关的调控通路在其中发挥重要作用,为解析红罗非鱼越冬期体色变异的机制奠定了基础。 相似文献
13.
This study examined the adverse effects of feed-delivered melamine (MEL) and cyanuric acid (CYA) in red tilapia. Diet 1 (without MEL and CYA), diets 2–4 (with MEL and CYA at 2.5, 5 and 7.5 g kg −1 diet, respectively) and diets 5 and 6 (with either MEL or CYA at 10 g kg −1 diet) were examined. MEL alone lowered both growth and FCR ( P < 0.05), and CYA alone reduced the FCR of tilapia. Protein efficiency ratio and apparent net utilization of fish on diets 2–6 were poor ( P < 0.05). The renal tubules of fish ingested MEL-CYA combination had melamine–cyanurate crystals. On the other hand, diets with only one chemical did not induce such crystals. MEL and CYA in whole body, fillet or viscera reflected their dietary inclusion levels. The levels of Hsp70 were increased in the liver of fish that ingested MEL and CYA, in combination or singly ( P < 0.05). However, in the kidney, such an increase was visible only in the fish that received diet 4 ( P < 0.05). Combination of MEL and CYA at inclusion levels > 5 g kg −1 diet induced the activity of catalase in liver and the activity of glutathione peroxidase in liver and kidneys. Therefore, these adulterants should not be included in fish feeds. 相似文献
14.
Rubber seed oil has a high potency to be used as a new lipid source within red tilapia diet. However, the rubber seed oil contains antinutritional factor such as hydrogen cyanide (HCN). HCN is classified into heat‐labile; therefore, heating effectively reduces the HCN content. Based on this fact, this research evaluated the use of rubber seed oil with and without heating as lipid source in red tilapia diet. Four isonitrogenous and isocaloric diets were prepared as experimental diet. Each test diet contains different lipid sources such as crude palm oil + corn oil (CTRL), crude palm oil + rubber seed oil with heating (CPO:PRSO), 100% rubber seed oil with heating (PRSO) and 100% RSO without heating (URSO). In average, there were no significant differences (Tukey: p < .05) among test diet except diet with 100% rubber seed oil without heating. It concluded that 100% rubber seed with heating within test diet has no effect on growth, feed performance, blood profile, cholesterol plasma, body and liver glycogen, malondialdehyde (MDA) and the activity of superoxide dismutase (SOD). 相似文献
15.
In teleosts, cortisol is one of the key factors regulating the adaptation to environmental challenges, such as salinity changes. This paper compares interrenal function between fully adapted freshwater (FW) and sea water (SW) specimens of the euryhaline teleost Oreochromis mossambicus (tilapia), combining morphometric and biosynthetic approaches. Interrenal tissue and two tissues producing interrenal secretagogues (ACTH and ANP; atrial natriuretic peptide) were studied. The results demonstrate that sea water adaptation concurs with a sustained stimulation of the interrenal cells, as evidenced by a marked hyperplasia of the cells and the higher initial ex vivo cortisol release in seawater adapted tilapia. This difference was not reflected in ultrastructural differences in the pituitary corticotropes. Plasma ACTH levels were also similar in FW and SW adapted tilapia. Moreover, in vitro data indicate that the ACTH sensitivity of the interrenal cells of both groups was also similar. A second potential interrenal secretagogue (ANP) has recently been implicated in teleost ionic regulation during salinity changes. However, plasma immunoreactive ANP levels and in vitro production of the hormone were also indistinguishable between FW and SW tilapia. ANP pretreatment of tilapia head kidneys in vitro strongly inhibited the response to ACTH, an effect previously undocumented for teleosts. Whereas the sustained stimulation of the interrenal cells under sea water conditions corroborates results obtained with other teleost species, thereby supporting a hypoosmoregulatory role for cortisol, it also is evident that notable species differences exist regarding the regulation of the interrenal gland under these conditions. 相似文献
17.
Horizontal transmission of various bacterial pathogens in tilapia is well described, but there is scant information regarding their vertical transmission. This study aimed to determine the possibility of vertical transmission of two commonly reported bacterial pathogens ( Francisella noatunensis subsp. orientalis and Shewanella putrefaciens) in natural stocks of red tilapia ( Oreochromis spp.). Vertical transmission of these pathogens via gametes was evaluated using in vitro fertilization from 10 different families and analysing for the presence of bacteria in milt, unfertilized eggs, fertilized eggs and offspring at various ages (1‐day‐old larvae, 10‐day‐old fry and 30‐day‐old fingerlings), as well as water samples using colorimetric LAMP assay. The study revealed that both F. n. orientalis (6/10) and S. putrefaciens (4/10) was transmitted vertically to the fertilized eggs. Analysis of the water samples from different water sources (brood stock tanks, hatching chamber and larval rearing tanks) showed that both the pathogens were present in water samples with highest prevalence for F. n. orientalis followed by S. putrefaciens. Analyses for the presence of two pathogens in various organs (gonads, gill, liver, spleen, kidney and brain) of the healthy tilapia broodstock without any clinical symptoms of disease demonstrated they were carriers of S. putrefaciens and F. n. orientalis. This is the first documented evidence that vertical transmission via the broodstock of tilapia may also play an important role in transmitting these problematic pathogens to their progeny and underlines the necessity to modify the current disease management strategies in tilapia aquaculture. 相似文献
18.
Streptococcus agalactiae causes a severe systemic disease in fish, and the routes of entry are still ill‐defined. To address this issue, two groups of 33 red tilapia Oreochromis spp. each of 10 g were orally infected with S. agalactiae ( n = 30), and by immersion ( n = 30), six individuals were control‐uninfected fish. Three tilapias were killed at each time point from 30 min to 96 h post‐inoculation (pi); controls were killed at 96 h. Samples from most tissues were examined by haematoxylin–eosin (H&E), indirect immunoperoxidase (IPI) and periodic acid‐Schiff; only intestine from fish infected by gavage was evaluated by transmission electron microscopy. The results of both experiments suggest that the main entry site of S. agalactiae in tilapia is the gastrointestinal epithelium; mucus seems to play an important defensive role, and environmental conditions may be an important predisposing factor for the infection. 相似文献
19.
Farming of red tilapia is increasing rapidly. However, its commercial farming development is challenged by lack of clear information on genetic basis for skin colour and pigmentation differences due to environmental changes. This study investigated the effects of photoperiod (light:dark, L:D) on the growth and skin colour variation of Malaysian red tilapia. A total of 180 fish weighing 150.48 ± 0.44 g were reared under natural photoperiod (13L:11D, control), prolonged lightness (24L:0D) and prolonged darkness (0L:24D) in three replicates for 78 days. The weight gain of fish cultured under both prolonged light and darkness were significantly higher than fish under natural photoperiod. The tyrosinase level in ventral skin was significantly higher for fish cultured under prolonged darkness condition than in the other two photoperiod regimes. Contrary, the cysteine level in the dorsal skin was significantly higher in the fish cultured under natural photoperiod than in prolonged light and darkness. The relative mRNA expressions of SRY‐related HMG‐Box 10 ( sox 10), tyrosine ( tyr), tyrosine‐related protein 1 ( tyrp‐1) and solute carrier family 7 member 11 ( slc7a11) genes were significantly higher in ventral skin of fish under prolonged darkness than the other two photoperiods. This study demonstrates that photoperiod has an impact on melanogenesis and growth of red tilapia. Understanding the effects of photoperiod on genetic basis of red tilapia will help in selective breeding programme of the important economic traits for the development of commercial red tilapia farming. 相似文献
20.
为了解马来西亚红罗非鱼体色分化变异的遗传分子机制,以期解决其越冬期的体色变异问题,本研究比较了越冬期不同温度处理(16、20、25和30°C)对其表观体色、酪氨酸酶活性以及皮肤色素带和黑色素细胞的影响。实验50 d后发现,16°C组大部分鱼体较实验开始时变黑,整个鱼体呈现青灰色,20°C组多数鱼体腹部也变为青灰色。随着温度的升高,红罗非鱼背部皮肤、腹部皮肤和血清中酪氨酸酶的活性逐渐升高,25°C时达到最高值,而随着温度的继续升高,30°C组鱼的酪氨酸酶活性反而降低。血液中tyr m RNA的表达量随着温度的升高而升高,25和30°C组红罗非鱼肌肉中的tyr m RNA表达量也显著高于16和20°C组。切片显微结构发现,随着温度的升高,红罗非鱼背部皮肤的黑色素细胞数量减少。研究表明,马来西亚红罗非鱼越冬期的体色变异可能是其皮肤黑色素细胞数量和体内酪氨酸酶活性改变的结果,深入研究其调控机制有助于了解鱼类体色遗传机理并进行体色性状的改良。 相似文献
|