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This study was performed to assess the nutritional value of Streptocephalus dichotomus nauplii and compared with standard larval diet and parthenogenetic strain of Artemia nauplii. The effectiveness of live feed was determined by feeding freshwater prawn Macrobrachium rosenbergii postlarvae. Results on the growth rate, weight gain, survival, fatty acid and amino acid composition show a significant variation between the dietary treatments. Mean larval growth was significantly different ( P < 0.001) between control diet (13.5 ± 0.5 mm) and live feeds ( Streptocephalus nauplii; 18.4 ± 0.5 mm and Artemia nauplii 18.7 ± 0.2 mm). The weight of larvae-fed Streptocephalus (41.1 ± 1.44 mg) and Artemia nauplii (41.7 ± 0.2 mg) was not significantly different; however, treatment with live feeds was significantly higher than the control (16.3 ± 0.5 mg) ( P < 0.001). Proximate composition on the fairy shrimp reveals that they are rich in protein, lipid, essential amino acids (EAA) and essential fatty acids (EFA). The polyenoic unsaturated fatty acid (18 : 2 n-6 and 18 : 3 n-3) and highly unsaturated fatty acid (20 : 4 n-3 and 20 : 5 n-3) show a dramatic increase in larval tissue relative to its proportional composition in the live diets. Amino acid composition in the live feeds, Streptocephalus and Artemia nauplii, perfectly reflects on the amino acid proportions in the larvae-fed diets which confirm its utilization. 相似文献
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Optimal egg viability storage conditions in two commercial fairy shrimps (Crustacea: Branchiopoda: Anostraca) from Thailand 
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下载免费PDF全文 Optimal egg viability storage conditions for two commercial fairy shrimps, Branchinella thailandensis and Streptocephalus sirindhornae, were investigated. Eggs for each treatment were kept under eight different conditions at four different temperatures for 24 months. Every 2 months, representative eggs were hatched to evaluate hatching percentages. Low temperature and oxygen, darkness and dry conditions significantly influenced egg hatchability of both species. Undehydrated eggs hatchability in all conditions ranged from 0 to 10% in S. sirindhornae and 0 to 20% in B. thailandensis. Hatching percentages of B. thailandensis were higher than those of S. sirindhornae. Hatchability under all experimental regimes continuously decreased over time, except for dry eggs stored at ?18°C in dark‐anoxic conditions. Hatchability was markedly delayed in both species over time. We demonstrate that both species’ eggs can be stored at ?18°C at least for 24 months with high hatchability in B. thailandensis (80%) and S. sirindhornae (60%) under dry, dark, anoxic conditions. 相似文献
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The antibacterial effects of organic salts, chemical disinfectants and antibiotics were evaluated on cultures of Aeromonas hydrophila C03, Aeromonas sobria C26, A. sobria C29, Aeromonas caviae C24 and Acinetobacter sp. SH‐94B, the pathogens that cause black disease found in fairy shrimps (Streptocephalus sirindhornae Sanoamuang et al. (2000) and Branchinella thailandensis Sanoamuang, Saengphan & Murugan) of Thailand. The minimal inhibitory concentrations (MICs) of organic salts (sodium chloride and potassium chloride) and antibiotics (oxytetracycline dihydrate, streptomycin sulphate, kanamycin monosulphate, chloramphenicol and ampicillin) were determined using the agar‐dilution method. The effect of chemical disinfectants (sodium hypochlorite and chlorine dioxide) was evaluated by exposing bacteria to different concentrations of these chemicals for different periods of time. Interestingly, all strains were intrinsically resistant to 0.25–3% sodium chloride and potassium chloride. The effect of sodium hypochlorite was greater than that of chlorine dioxide, and 5–20 μg mL?1 of sodium hypochlorite was sufficient to inhibit the growth of these bacteria, but the exposure time varied, depending on the bacterial species. Of the antibiotics tested, chloramphenicol and oxytetracycline dihydrate completely inhibited the selected strains. Chloramphenicol showed the highest antibacterial effect against all pathogenic species – the MIC and minimal bactericidal concentration (MBC) ranged from 0.8 to 3.1 μg mL?1 from 3.1 to 6.25 μg mL?1, respectively. To achieve control of black disease during cultivation of fairy shrimp, data derived from this study can be used as a basis for further toxicity tests in vivo. 相似文献
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In this study, black disease infecting fairy shrimps, Streptocephalus sirindhornae Sanoamuang, Murugan, Weekers & Dumont, and Branchinella thailandensis Sanoamuang, Saengphan & Murugan, in Thailand, was investigated. The typical signs of the disease are the appearance of black spots on the cuticle, located mainly on the dorsal side and thoracopods. A number of rod-shaped bacteria aggregated in the black spots and were visualized by scanning electron microscopy. The histopathological results showed that a haemocytic response to the infection resulted in a dense melanized core of bacteria. In addition, generalized septicaemia by rod-shaped bacteria was also observed in the infected tissue. Of the 31 isolates, Aeromonas spp. were predominantly isolated and six strains were selected for the experimental infections. The most pathogenic strain was identified molecularly as A. hydrophila. When fairy shrimp were infected at bacterial concentrations of 10(4) and 10(6) cfu mL(-1) , the overall infection levels were 73.33 ± 6.67% and 93.33 ± 6.67%, respectively. The experimentally infected fairy shrimp showed abnormal swimming and died within 24-48 h after the appearance of the dark pigment. 相似文献
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This study was conducted with cysts of Streptocephalus proboscideus obtained from the University of Gent‐Belgium. The cysts were hatched in Environmental Protection Agency (EPA) medium. The nauplii were reared at the Sturgeon Research Institute using a pure culture of Scenedesmus obliquus alga supplied at a density of 5 × 103 cell mL−1 that gradually increased to 1 × 104, 5 × 104 and 1 × 105 cell mL−1 with the growth of the nauplii. The nauplii attained sexual maturity and started producing cysts in 8 days and yielded a mean cyst number of 220±40 female−1 brood−1 cysts. These cysts were used in the larviculture of Persian sturgeon, Acipenser persicus (Borodin). Forty‐three larvae of Persian sturgeon (mean weight: 15.4±1.1 mg; mean length: 27.1±2.7 mm) with roughly absorbed yolk sacs were stocked in three aquaria and fed S. proboscideus nauplii at 8‐h intervals. By the end of the experiment (day 5), the mean weight and length of Persian sturgeon larvae were 51.4±13.3 mg and 20.7±1.4 mm respectively. 相似文献
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