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991.
A feeding trial aimed to determine the effects of dietary lipid level on growth performance, body composition and digestive enzymes activity of juvenile sea cucumber, Apostichopus japonicus. Diets with six crude lipid levels (1.9, 13.8, 29.1, 43.6, 59.6 and 71.6 g kg?1) were fed to sea cucumbers (initial weights 0.65 ± 0.01 g) at a density of 30 juveniles, once a day. After 60 days, body weight gain (BWG), specific growth rate (SGR), feed intake (FI) and protein efficiency ratio (PER) decreased with increasing dietary lipid levels. The sea cucumbers fed 1.9 g kg?1 crude lipid showed significantly higher (P < 0.05) BWG than those of the sea cucumbers fed 59.6 and 71.6 g kg?1 crude lipid. Intestinal protease and lipase activities generally increased with increasing dietary lipid levels. Eicosapentaenoic acid (EPA) content of body walls generally increased with increasing dietary lipid levels. Docosahexaenoic acid (DHA) content of body walls reached the maximum value at a dietary lipid level of 13.8 g kg?1. N‐3 highly unsaturated fatty acid content followed the same pattern of DHA. According to the growth performance and body composition of sea cucumbers, it can be indicated that the optimum dietary lipid level for juvenile sea cucumbers is between 1.9 and 13.8 g kg?1.  相似文献   
992.
993.
Biofloc rearing media provides a potential food source for shrimp reared in limited or zero water exchange systems. This culture system is environmentally friendly as it is based on limited water use and minimal effluent is released into the surrounding environment. In this study, we evaluated the survival, growth performance and salinity stress tolerance of pink shrimp Farfantepenaeus paulensis postlarvae reared from PL10 to PL25 in a biofloc technology limited water exchange system. PL (mean ± SD weight and length of 14 ± 10 mg and 8.10 ± 0.7 mm, respectively) were reared in nine 40-L plastic tanks with a stocking density of 10PL/L. Three culture treatments were applied (1) culture in the presence of bioflocs and commercial feed supply (FLOC + CF); (2) culture in the presence of biofloc without feed supply (FLOC) and (3) culture in clear water with feed supply (control). Final biomass and survival were significantly higher in FLOC + CF treatment than the control (P < 0.05), but did not differ from FLOC. PL reared in the FLOC + CF treatment achieved a significantly higher final weight, weight gain and length in comparison with the other two treatments (P < 0.05). No significant difference (P > 0.05) between treatments was found for salinity tolerance over 24 and 48 h durations. The proximate analysis of floc shown high levels of crude protein (30.4%), but low levels of crude lipids (0.5%). The continuous availability of bioflocs had a significant effect on growth and survival of F. paulensis postlarvae cultured in BFT nursery systems.  相似文献   
994.
995.
Cyprinid herpesvirus 3 (CyHV‐3) is an alloherpesvirus, and it is the aetiological agent of koi herpesvirus disease. Although the complex morphogenic stages of the replication cycle of CyHV‐3 were shown to resemble that of other members of the Herpesvirales, detailed analysis of the sequence and timing of these events was not definitively determined. This study describes these features through a time course using cyprinid cell cultures (KF‐1 and CCB) infected with CyHV‐3 (KHV isolate, H361) and analysed by transmission electron microscopy. Rapid viral entry was noted, with high levels of intracellular virus within 1–4 h post‐infection (hpi). Intranuclear capsid assembly, paracrystalline array formation and primary envelopment of capsids occurred within 4 hpi. Between 1 and 3 days post‐infection (dpi), intracytoplasmic secondary envelopment occurred, as well as budding of infectious virions at the plasma membrane. At 5–7 dpi, the cytoplasm contained cytopathic vacuoles, enveloped virions within vesicles, and abundant non‐enveloped capsids; also there was frequent nuclear deformation. Several morphological features are suggestive of inefficient viral assembly, with production of non‐infectious particles, particularly in KF‐1 cells. The timing of this alloherpesvirus morphogenesis is similar to other members of the Herpesvirales, but there may be possible implications of using different cell lines for CyHV‐3 propagation.  相似文献   
996.
Epitheliocystis in Swiss brown trout (Salmo trutta) is a chlamydial infection, mainly caused by Candidatus Piscichlamydia salmonis and Candidatus Clavichlamydia salmonicola. To gain a better understanding of the temporal development of infections in wild brown trout, we investigated epitheliocystis infections during the course of the summer and autumn months of a single year (2015), and compared this to sampling points over the span of the years 2012–2014. The survey focused on tributaries (Venoge and Boiron) of the Rhone flowing in to Lake Geneva. When evaluated histologically, epitheliocystis infections were found throughout the period of investigation with the exception of the month of June. Fifty to 86 animals per sampling were investigated. Highest prevalence and infection intensities were seen in September. A correlation between epitheliocystis infection and water temperatures was not evident. Interyear comparison revealed consistent levels of prevalence and infection intensities in late summer. The absence of infections in June, combined with the consistent interyear results, indicates seasonal fluctuation of epitheliocystis infections in brown trout with a reservoir persisting during winter months from which infections can re‐initiate each year. This could either be at levels below detection limits within the brown trout population itself or in an alternative host.  相似文献   
997.
Fusarium oxysporum species complex (FOSC) is a highly diverse fungus. Recently, F. oxysporum infection was identified from zebrafish (Danio rerio) culturing system in Korea. Initially, a rapid whitish smudge was appeared in the water with the fungal blooming on walls of fish tanks. Microscopic studies were conducted on fungal hyphae, colony pigmentation and chlamydospore formation and the presence of macro‐ and microspores confirmed that the isolated fungus as F. oxysporum. Furthermore, isolated F. oxysporum was confirmed by internal transcribed spacer sequencing which matched (100%) to nine F. oxysporum sequences available in GenBank. Experimental hypodermic injection of F. oxysporum into adult zebrafish showed the development of fungal mycelium and pathogenicity similar to signs observed. Histopathologic results revealed a presence of F. oxysporum hyphae in zebrafish muscle. Fusarium oxysporum growth was increased with sea salt in a concentration‐dependent manner. Antifungal susceptibility results revealed that F. oxysporum is resistant to copper sulphate (up to 200 μg mL?1) and sensitive to nystatin (up to 40 μg mL?1). This is the first report of FOSC from zebrafish culture system, suggesting it appears as an emerging pathogen, thus posing a significant risk on zebrafish facilities in the world.  相似文献   
998.
Pseudomonas fluorescens are known bacterial pathogens in fish. The P. fluorescens group contains at least nine different bacterial species, although species from fish have rarely been differentiated. Two isolated fish kills affecting wild bluegills, Lepomis macrochirus Rafinesque, and pumpkinseed sunfish, Lepomis gibbosus (Linnaeus), occurred in the spring of 2015 during cool water temperatures (12.5°C–15.5°C). Disease signs included severe bacteraemia with rare gross external signs. Pure bacterial cultures isolated from kidneys of all affected fish were identified as P. fluorescens using the API 20NE system, while no bacteria were isolated from asymptomatic fish. To further identify the species of bacterium within the P. fluorescens complex, genetic analysis of the 16S rRNA, rpoD and gyrB genes was conducted. DNA sequences of bacterial isolates from both mortality events were identical and had close identity (≥99.7%) to Pseudomonas mandelii. Although likely widespread in the aquatic environment, this is the first report of a bacterium closely resembling P. mandelii infecting and causing disease in fish. The bacterium grew at temperatures between 5°C and 30°C, but not at 37°C. It is possible that infections in fish were a result of immunosuppression associated with spring conditions combined with the psychrotrophic nature of the bacterium.  相似文献   
999.
1000.
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