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1.
Diacronema vlkianum was grown in polyethylene bags at two different temperatures (18 and 26°C) in the laboratory. The biochemical composition level decreased when the temperature increased from 18 to 26°C. The maximum cell number at 18°C was 11.9 × 106 cells ml−1, while maximum cell number at 26°C was 1.6 × 106 cells ml−1. The maximum level of α-tocopherol was 257.7 ± 21.6 μg g−1 dry weight (DW) at 18°C. The highest total carotenoids and chlorophylls were 6.5 mg g−1 DW and 4.3 mg g−1 DW, respectively, and the main pigments were determined as astaxanthin and lutein. Polyunsaturated fatty acids were found to be the predominant group, reaching 39.5% of the total fatty acids at 18°C. This comprised 20:5(n − 3) as the main polyunsaturated fatty acids (20.4%, at 18°C) followed by 22:6(n − 3) (4.8%, at 18°C). The results suggest that D. vlkianum can be successfully used as feed in shellfish hatcheries or aquaculture hatcheries, either as a substitute or in association with other microalgae, when this algae is cultured at 18°C.  相似文献   

2.
The effects of 17β-estradiol injection (10?7mol/crayfish) in adult female Astacus leptodactylus on the reproductive efficiency (i.e., pleopodal egg and stage 1 juvenile numbers) were investigated. In addition, hepatosomatic index, gonodosomatic index, and 17β-estradiol (E2) levels of crayfish ovary, hepatopancreas, and heamolymph before and after injections were also determined. Results showed that E2 injection to females enhances the reproductive efficiency of A.leptodctylus. E2 injection significantly increased pleopodal egg and stage 1 juvenile numbers, GSI, HSI, and concentrations of E2 in heamolymph, ovary, and hepatopancreas. However, E2 injection did not accelerate time of mating and proportion of pleopodal egg-berried females at the first week of reproduction season in this species. This study highlights that to improve the reproductive efficiency of A.leptodctylus by using hormones to regulate the ovarian cycle, E2 should be used at least 1.5 months before the commencement of the breeding season.  相似文献   

3.
Culture of Ruditapes decussatus is clearly limited by the availability of seed, as this production proceeds almost exclusively from natural recruitment. Artificial spawning and larval rearing programs could provide an alternative source of spat. This study was designed to evaluate the effect of different conditioning temperatures on the broodstock maturation, spawning success and larval viability of two geographically (north and south of the Iberian Peninsula) distinct populations of European clam (R. decussatus) collected at different periods of the year in order to create “optimal” artificial spawning and larval rearing programs. Two batches of clams from each population were collected in October and February, and conditioned at 18 ± 1°C, 20 ± 1°C and 22 ± 1°C. Of the three variables analysed the timing of broodstock collection was the most determining factor for gametogenic development, spawning and larval rearing. Geographic origin and conditioning temperature also greatly affected the spawning. The results also showed that the February conditioning was more effective than October and that the best conditioning temperatures were 20 ± 1°C and 22 ± 1°C for the northern and southern populations, respectively. These results suggest that the efficient conditioning temperature for each population of the same species is related to the seasonal temperature regime from their geographic origin. Larval viability and growth performance seemed to be independent of the broodstock conditioning.  相似文献   

4.
GH-transgeniccoho salmon (Oncorhynchus kitsutch) juveniles were fed diets containing 3,5,3-triiodo-L-thyronine (T3; 30 ng/g fish) or 6-n-propyl-2-thiouracil (PTU; 20 ug/g fish), to assess the effect of these drugs on the physiology, growthand survival in comparison with untreated transgenicand non-transgenic salmon. After 84 days, food intake, feed efficiency, survival, growth, hepato-somatic index (HSI), viscera-somatic index (VSI), plasma L-thyroxine (T4), T3and growth hormone (GH) levels,and cranial morphological abnormalities were determined. Growth of transgenic salmon was significantly faster than the nontransgenic salmon,and was increased by exogenous T3and reduced by PTU. Food intake of transgenic salmon was higher than that of the nontransgenic group, but was reduced by exogenous PTU administration. Food conversion efficiency of transgenic salmon was lower than that of nontransgenic salmon,and also was increased by T3 but reduced by PTU in the transgenic fish. The survival rate in all transgenic groups was significantly higher than that of nontransgenic,and transgenic T3and PTU treatment groups showed higher survivals than the transgenic-control group. The HSIand VSI of the transgenic fish were higher than the nontransgenic fish;and both parameters in the transgenic salmon were increased by PTU, but reduced by T3. The plasma T4 level in transgenic salmon was approximately 1.5-fold higher relative to the nontransgenic fish, whereas no difference was observed among the transgenic groups. Plasma T3 levels in transgenic salmon were also approximately 2-fold higher relative to the nontransgenic fish. However, the plasma T3 level in transgenic animals was increased by exogenous T3 administration, but was reduced by exogenous PTU to that observed in nontransgenic salmon. The plasma GH level of transgenic fish was higher than that of the nontransgenic salmon,and the level was increased by the exogenous T3, whereas exogenous PTU did not reduce significantly GH levels in transgenic salmon. Transgenic fish also displayed cranium, jawand opercular abnormalities typical of the effects of this gene construct incoho salmon, indicating that some imbalance in growth processes has been induced. However, these abnormalities (especially cranial disruptions) were diminished by administration of exogenous PTU. In conclusion, exogenous T3and PTU treatments can induce hyperthyroidismand hypothyroidism, respectively,and have inverse effects on growthand skeletal abnormalities of transgenic salmon constitutively expressing GH.  相似文献   

5.
Aquaculture International - This study investigated the efficacy of trichlorfon against Neoechinorhynchus buttnerae, as well as its palatability, residue analysis, and the blood parameters of...  相似文献   

6.
β-1,3-Glucan at different dietary doses was administered to enhance the growth, immunity, and survival against nitrite stress in Pacific white shrimp, Litopenaeus vannamei. Four different diets supplemented with 0, 250, 500, or 1,000 mg of β-1,3-glucan kg−1 diets were fed to L. vannamei. Growth performance (weight gain and survival rate), physiological conditions (blood total protein, glucose, lactate, triacylglycerols, cholesterol levels) and immunological responses (superoxide dismutase, catalase, lysozyme, acid phosphatase, and alkaline phosphatase activities) of shrimp were recorded after 84-day feeding and 120 h after exposed to nitrite-N. After 84-day feeding, 250 mg kg−1 β-1,3-glucan diet resulted in better weight gain (P < 0.05). Before the nitrite stress, blood lactate, triacylglycerols, and cholesterol level in shrimp fed with 250 mg kg−1 β-1,3-glucan diet were significantly higher than those observed in shrimp fed with other diets (P < 0.05). Higher activities of catalase, lysozyme, and alkaline phosphatase were observed in shrimp fed with 500 or 1,000 mg kg−1 β-1,3-glucan diet as compared to those obtained in shrimp fed with other diets (P < 0.05). After 120-h nitrite stress, blood protein, lactate, superoxide dismutase, catalase, and alkaline phosphatase activities in shrimp fed with 500 or 1,000 mg kg−1 β-1,3-glucan were significantly higher than those observed in shrimp fed with other diets (P < 0.05). Glucose and triacylglycerol levels of shrimp fed with 500 or 1,000 mg kg−1 β-1,3-glucan were significantly lower than those observed in other diets (P < 0.05). In shrimp fed with 500 and 1,000 mg kg−1 β-1,3-glucan and 120-h after nitrite stress, the mortality was significantly lower than that observed in shrimp of control. Together, in this 84-day feeding trial, 250 mg kg−1 β-1,3-glucan improved growth, whereas 500 mg kg−1 β-1,3-glucan preferentially improved nitrite resistance, probably through accelerating energy metabolism and activating immune system.  相似文献   

7.
Biquara is one of the main fish species caught in the northeast coast of Brazil but presents low commercial value. Therefore, the elaboration of biquara-based products with the addition of plant bran as a source of dietary fiber should be studied as a way to add value to biquara. The objective of the present study was to evaluate the physicochemical, microbiological, and sensory aspects of fishburgers made with biquara fillet with the addition of wheat bran (WB) (0, 1, 2, and 3%). The increase in WB decreased moisture and increased protein levels, ash, fiber, carbohydrates, and energy value. In addition, the inclusion of WB increased the cooking shrinkage and decreased hardness and cohesiveness of the samples. The fishburgers with the greatest WB levels presented a reddish-yellow hue. The microbial counts of the products were below the maximum limit allowed by the Brazilian legislation. The overall acceptance of the fishburgers improved with the addition of 0 to 2% WB. Therefore, the biquara fillets have a potential for the elaboration of fishburgers with the addition of 2% WB, once the products presented suitable physicochemical composition, sensory acceptance, and hygienic sanitary control according to the current national legislation.  相似文献   

8.
A nutrition trial was conducted to investigate the effects of dietary lipid levels and supplemental Ulva meal on growth performance, feed efficiency, nutrient utilization, and body composition of juvenile Nile tilapia, Oreochromis niloticus. Four isonitrogenous (CP 40%) diets containing 0% and 5% Ulva meal were formulated to contain 10% (low-lipid; LL) and 20% (high-lipid; HL) crude lipid. Triplicate groups of fish (~10 g) were fed to apparent satiation three times daily for 16 weeks. Fish fed 5% Ulva meal showed an increased growth performance (P < 0.05) compared with fish fed non-Ulva supplemented diets, irrespective of dietary lipid level. In particular, the incorporation of Ulva meal improved specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER). Feeding fish 5% Ulva meal diets resulted in significantly lower carcass lipid content. The results indicate that 5% inclusion of Ulva meal at both dietary lipid levels improves growth performance, feed efficiency, nutrient utilization, and body composition of Nile tilapia.  相似文献   

9.
In the present study, we examined the long-term effects of environmental salinity, diet (35% and 25% crude protein) and 17-methyltestosterone (MT) on corresponding levels of pituitary and serum growth hormone (GH) and prolactins (tPRL177 and tPRL188) in the tilapia (Oreochromis mossambicus). We observed no discernible patterns in serum GH that would suggest an effect of salinity, diet or MT. However, serum GH levels in all treatments declined at 1 and 3h after first feeding. Serum tPRL177 and tPRL188 were significantly higher in freshwater (FW) than in seawater (SW) and levels were significantly affected by dietary protein. tPRL177 levels were higher in all groups fed a 35% protein diet, but tPRL188 levels were higher only in the groups fed the MT-treated 35% protein diet; only serum tPRL188 levels were affected by MT. Moreover, serum tPRL177 and tPRL188 increased throughout the sampling time-course. Subsequent work using fasted tilapia suggests that first feeding is likely to initiate the post-prandial suppression of serum GH levels. In contrast with the picture observed in blood, pituitary glands of SW animals showed higher levels of GH than FW fish. Pituitary GH was elevated by MT in both FW and SW. We also observed that pituitary tPRL177 and tPRL188 levels were higher in FW fish than in SW fish; tPRL177 and tPRL188 levels were elevated by MT only in FW animals. To assess the somatomedin activity of plasma from FW- and SW-reared tilapia, we measured [35S]-sulfate incorporation into ceratobranchial cartilage explants in vitro. Plasma from SW-adapted tilapia showed greater activity in this assay than plasma from FW-reared tilapia, suggesting that the GH-dependent IGF bioactivity of plasma is higher in SW-reared tilapia. Collectively, these studies suggest that the growth-promoting actions of SW rearing and of MT administration in tilapia may be linked to elevations in GH and/or prolactin (tPRL177 and tPRL188)levels.  相似文献   

10.
Male goldeye were treated with (D-Ala6, Pro9-N ethylamide) — LHRH (LHRH-A) in saline or a silastic pellet (100 µg.kg–1 body weight) and changes in plasma gonadotropin (GtH), 17,20-dihydroxy-4-pregnen-3-one (17,20P) and testosterone (T) levels were determined by radioimmunoassay. LHRH-A increased plasma GtH levels, with the response to LHRH-A in saline being of much greater magnitude and duration than the response to silastic pellet implants. Seasonal differences were found in the response to LHRH-A. Spermiated fish were the most responsive, recrudescing fish the least, and regressed fish displayed an intermediate response. Plasma 17,20P levels were elevated in response to LHRHA in fish of all sexual stages although the magnitude of the increase was not related to the magnitude of the increase in GtH levels. Treatment with LHRH-A also resulted in a transitory increase in plasma T levels. The endocrine control of GtH and steroid secretion in goldeye is discussed in relation to studies in cyprinids and salmonids. Address for reprint requests: Department of Zoology, University of Alberta, Edmonton, Alberta T6G 2E9 Canada.  相似文献   

11.
The stone loach, Barbatula barbatula (L.), is a typical and dominant intermediate host of Raphidascaris acus in lowland streams of Central Europe. The prevalence of infection of R. acus in B. barbatula from the River Haná ranged throughout the year from 73.3 to 100%. The abundance and the mean intensity of infection also varied throughout the year with a peak in September. Larvae were located mainly in the liver parenchyma. High numbers of larvae and their migration through the tissue caused cyst- or abscess-like formations in the host parenchyma. The severity of the disease condition ranged from mild to severe. We speculate that the infection of stone loach by R. acus larvae regulates the population density and abundance of the intermediate host in lowland streams where natural predators are absent.  相似文献   

12.
The effect of supplemented commercial diets with diethylstilbestrol (DES—15, 30 and 60 mg kg?1) and 17 β-estradiol (E2—30 and 60 mg kg?1), two chemicals commonly used in sex reversal procedure in fish, on survival and growth parameters of juvenile European catfish (Silurus glanis) was evaluated. During the two experiments, lasting 28 days each, fish were kept at temperature 25.2–26.5 °C, pH 7.4–9.3 and oxygen concentration 5.0–7.3 mg O2 dm?3. DES supplementation resulted in depressed growth rate of catfish. In experimental groups fed with E2, no negative effect on growth parameters was found. Both chemicals did not result in observed mortality. In all of the experimental DES groups, hepatosomatic index increased significantly, which suggests negative influence on physiological condition of catfish. DES supplementation significantly changed cytological factors of liver cells and caused hepatic alterations in parenchyma, such as vacuolization and blood congestion. Similarly, supplementation of E2 in food resulted in changes in cytological parameters of hepatocytes. However, E2 did not cause pathological changes within the liver tissue. Histological examination of the catfish gonads showed 19 and 38 % of sterile fish after treatment with 30 and 60 mg kg?1 of DES, respectively. The results suggest that DES served in food could be ineffective in hormonal feminization process of European catfish. No disturbances of sex differentiation process after E2 treatment were observed. However, slight feminization effect in the highest level of E2 treatment group was recorded.  相似文献   

13.
A set of feeding trials was carried out for different microalgal species and processed diets for the culture of the New Zealand pipi, Paphies australis. Five microalgal species (Isochrysis galbana clone T-ISO, Pavlova lutheri, Tetraselmis suecica, Chaetoceros muelleri, and Thalassiora pseudonana clone 3H) and three formulated diets (baker's yeast, wheat flour, and corn flour) were fed to spat, juvenile, and adult pipi for 21 days. Unfed pipi were used in the control group. The spat and juvenile pipi showed a major shell increase with I. galbana while the greatest wet weight increase was obtained with P. lutheri. The shells of adult pipi grew better with corn flour, and the P. lutheri-fed group obtained the greatest wet weight. Results of proximate analysis in adult pipi revealed that proteins and lipids were accumulated in the tissue for all fed groups, while carbohydrate levels were depleted in all treatments including the control group. It is suggested that the gonads have developed during the experiment.  相似文献   

14.
The aim of this research was to formulate a unique product, croaker pâté, and to determine its physicochemical, microbiological, and sensorial characterization. Three formulations of pâté were elaborated. The pâtés fit in the stipulated regulations for the microbiological test. Regarding the texture, the pâtés presented a significant difference (p < 0.05) among each other. In the sensorial tests, the favorite pâté of the panel was formulation 3; in the acceptance test, it had higher levels of acceptance for color, flavor, and global acceptance in comparison with commercial pâté.  相似文献   

15.
随着养殖面积、规模的不断扩大,养殖病害日益严重,国家将对养殖生产中给人类可能构成威胁的养殖疾病列为疫病,其中水生动物疫病五种。依法实施疫政,必须建立完善的防疫体系,目前为了防治重大疾病,大量的化学药物在养殖生产中使用,超剂量的使用不仅增加养殖成本,同时造成水域污染和残留。为了加强病害防治能力、普及防病知识,现将全国水产技术推广总站病防处组织编辑的《水生动物疾病检疫图说》选取部分章节连载,供大家参考。  相似文献   

16.
A 28-day indoor trial was conducted to evaluate the water quality, phytoplankton composition and growth of Litopenaeus vannamei in an integrated biofloc system with Gracilaria birdiae and Gracilaria domingensis. The experimental design was completely randomized with three treatments: control (shrimp monoculture); SB (shrimp and G. birdiae) and SD (shrimp and G. domingensis), all with three replicates. Random sampling was done (6 % of total population per experimental unit) to confirm white spot syndrome Virus (WSSV) infection using nested-PCR analysis due to suspicion of presence of the virus in the experiment (treatment and control groups). Shrimp L. vannamei (2.63 ± 0.10 g) were stocked in experimental tanks at a density of 425 shrimp m?3, and the Gracilaria was stocked at a biomass of 2.0 kg m?3. Shrimp mortality began in both the experimental and control groups at 10 days of culture. The integrated biofloc system (shrimp and seaweed) increased settleable solids (by 26–52 %); final weight (by 6–21 %); weekly growth (by 17–43 %); weight gain (by 17–43 %); specific growth rate (by 16–36 %); and yield (by 5–7 %) and decreased feed conversion ratio (by 21–28 %) and Cyanobacteria density about 16 % as compared to the control (shrimp monoculture). The use of red seaweed Gracilaria in an integrated biofloc system can enhance shrimp growth and reduce Cyanobacteria density in the presence of WSSV.  相似文献   

17.
Aquaculture International - Pacific white shrimp (Penaeus vannamei) farming is an important commercial aquaculture production system contributing substantially to the economic and societal...  相似文献   

18.
Pure bacterial cultures were isolated from diseased snakeheads, Channa maculata (Lacepède), suffering high mortality in a farm in Zhongshan, southern China. Three isolates, namely ZS20100725, ZS20100725-1 and ZS20100725-2, were identified as Aeromonas schubertii. All the isolates showed high 16S rRNA sequence similarities with A. schubertii. The isolates exhibited strong virulence to snakeheads in experimental challenges with LD(50) ranging between 1.4 × 10(4) and 6.4 × 10(6) CFU g(-1). Two of the isolates were positive for haemolysin, elastase, lipase and lecithinase by phenotypic determination, which was further confirmed by PCR amplification of the haemolysin and elastase genes. In sterile liquid medium, the best growth conditions of strain ZS20100725 were 30 °C, pH 7 and 0.5% salinity (w/v). Antibiotic susceptibility tests showed that strain ZS20100725 was susceptible to cefoxitin, cefoperazone and chloramphenicol. Furthermore, histopathology of diseased snakeheads infected with A. schubertii showed necrosis and congestion in liver, kidney and spleen and also damage to the cardiac muscle, intestine and gills.  相似文献   

19.
Zhang  Zhe  Yang  Zhangwu  Ding  Ning  Xiong  Weiwei  Zheng  Guofu  Lin  Qi  Zhang  Gen 《Fisheries Science》2018,84(2):399-404
Fisheries Science - Pearl gentian grouper (Epinephelus fuscoguttatus ♀&nbsp;×&nbsp;Epinephelus lanceolatus ♂) is an important commercial and economic fish from the...  相似文献   

20.
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