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1.
In this study, four essential oils—cinnamon oil, leech lime oil, lemongrass oil, and turmeric oil—were examined for their
antimicrobial activities against Streptococcus iniae, a bacterium that is pathogenic in fish, in which it causes streptococcosis. Cinnamon oil was the most potent antimicrobial
agent among these oils, with a minimal inhibitory concentration (MIC) of 40 μg/ml. By using gas chromatography–mass spectrometry
(GC–MS), it was found that the major components of cinnamon oil were cinnamaldehyde (90.24), limonene (2.42%), cinnamyl acetate
(2.03%), linalool (1.16%), and α-terpineol (0.87%). Of these compounds, only cinnamaldehyde exhibited antimicrobial activity
against S. iniae, with an MIC of 20 μg/ml. In an in vivo trial, no mortality was apparent in fish fed on fish diets supplemented with 0.4%
(w/w) of cinnamon oil and with 0.1% (w/w) of oxytetracycline 5 days prior to infection with S. iniae. These results indicate that cinnamon oil had a protective effect on experimental S. iniae infection in tilapia, and thus has the potential to replace the antibiotics used to control this disease. 相似文献
2.
Streptococcus dysgalactiae strains have been isolated from cultured amberjack Seriola dumerili and yellowtail Seriola quinqueradiata in Japan. To characterize the fish isolates, we performed genetic analysis and compared the biochemical properties of these
isolates with those of the S. dysgalactiae subsp. dysgalactiae and S. dysgalactiae subsp. equisimilis strains isolated from mammals. The genetic analysis revealed that the fish isolates were genetically very similar to each
other with high DNA–DNA relatedness (>95.4%) and sequence homology. Meanwhile, the DNA relatedness between mammalian isolates
and the fish isolates was 73.4–82.6%. In biased sinusoidal gel electrophoresis (BSFGE) analysis, the restriction patterns
of mammalian isolates were different from those of fish isolates. The fish isolates did not show streptokinase activity in
plasminogen obtained from mammals. These characteristics enabled us to distinguish between the fish isolates and the Sdd and Sde strains isolated from mammals. In order to obtain epidemiological information on the fish isolates, BSFGE patterns from 284
S. dysgalactiae strains from fish in Japan were examined. Based on the results of BSFGE analysis, the fish isolates were classified into
16 groups (AP1–AP16) with restriction enzyme ApaI. The dendrogram based on BSFGE analysis indicated that all fish isolates using in this study were closely related. 相似文献
3.
The immediate-early gene (egr-1) expression was used to examine the neuron’s response in telencephalon of goldfish during spatial learning in small space.
Fishes were pre-exposed in the experimental apparatus and trained to pick food from the tray in a rectangular-shaped arena.
The apparatus was divided into identical compartments comprising three gates to provide different spatial tasks. After the
fish learned to pass through the gate one, two more gates were introduced one by one. Fish made more number of attempts and
took longer time (P < 0.05) to pass through the first gate than the gate two or three. This active learning induces the expression of egr-1 in telencephalon as established by western blot analysis. Subsequently, the fish learn quickly to cross the similar type
of second and third gate and make fewer errors with a corresponding decline in the level of egr-1 expression. As the fish learned to pass through all the three gates, third gate was replaced by modified gate three. Interestingly,
the level of egr-1 expression increased again, when the fish exhibit a high exploratory behavior to cross the modified gate three. The present
study shows that egr-1 expression is induced in the telencephalon of goldfish while intensively acquiring geometric spatial information to pass
through the gates. 相似文献
4.
Jinyong Zhang Fei Meng Hiroshi Yokoyama Jiro Miyahara Ikuo Takami Kazuo Ogawa 《Fisheries Science》2010,76(6):981-990
During the parasitological survey of cultured juvenile Pacific bluefin tuna (PBT) Thunnus orientalis in 2007 and 2008, two myxosporeans and one microsporidian were found. Morphological and molecular analysis showed that the
heart-infecting and brain-infecting myxosporeans are identified as Kudoa shiomitsui and K. yasunagai, respectively. This is a new host record for both species. High prevalence of infection (77–100%) with K. shiomitsui was observed in October to December (1–2 months post-transfer to sea cages), whereas only a few fish were infected with K. yasunagai. A microsporidian observed as white “cysts” in the trunk muscle of PBT had a resemblance to Microsporidium seriolae, the causative parasite of beko disease in yellowtail. Phylogenetic analysis showed that the microsporidian from PBT is closely
related to but distinct from several other muscle-infecting species such as M. seriolae, Microsporidium sp. RSB, and Microsporidium sp. SH. Additionally, the spore dimension (2.7 × 1.5 μm on average) was remarkably smaller than the others. These results
suggest that the present microsporidian is an undescribed species and designated Microsporidium sp. PBT. Prevalence and intensity of infection with Microsporidium sp. PBT reached a maximum of 100% and 20 cysts/fish, respectively. Although pathogenic effects of the two Kudoa species on fish health remain unknown, the microsporidian could be of concern to PBT aquaculture due to unsightly cysts in
the musculature, reducing the market value of the fish. 相似文献
5.
We monitored feeding behavior and survival of starved juvenile olive flounder experimentally infected with the gill monogenean
Neoheterobothrium hirame. Infected flounder increased amount of the time spent in the water column by 117% when trying to capture live mysids, Neomysis sp. They also showed different feeding patterns from those of uninfected fish and made fewer attacks towards prey during
one feeding attempt. Although the average numbers of mysids captured by individuals were similar between infected and uninfected
fish, heavily infected fish tended to catch less prey. These results indicate that N. hirame reduces the feeding efficiency of the host for capturing live prey and possibly makes them more vulnerable to predation during
feeding. We could not detect any obvious difference in survival rates between uninfected, lightly and heavily infected fish
during 3 months of starvation. There was no evidence that starvation makes fish more susceptible to N. hirame. The present study provides first experimental evidence that N. hirame affects feeding behavior of juvenile olive flounder and supports the idea that this parasite indirectly reducing the host’s
survival and may be responsible for the recent reduction of the flounder population in Japan. 相似文献
6.
Tamer Fawzy Ismail Atsushi Nakamura Kenji Nakanishi Takayuki Minami Takuya Murase Soetsu Yanagi Toshiaki Itami Terutoyo Yoshida 《Fisheries Science》2012,78(2):351-357
Resazurin microtiter assay (REMA) was carried out using four sulfonamides, three culture media, and four inoculum sizes as
a first screening step to establish an easy-to-interpret sulfonamides susceptibility testing method for Nocardia seriolae. The in vitro activity of sulfamonomethoxine (SMM) against 190 clinical N. seriolae isolates was then examined, and in vivo experimental treatment was performed. When the culture medium and the inoculum size
were considered in tandem, a 0.5× the original concentration of cation-adjusted Mueller–Hinton broth and an inoculum size
of 102 CFU/well showed the clearest endpoint reading for all tested drugs, and the REMA-generated data were in excellent agreement
with those generated by the reference Etest method. SMM activity showed minimum inhibitory concentration (MIC) values of 4–32 μg/ml
against all tested N. seriolae isolates. Treatment of amberjack groups experimentally infected with N. seriolae isolates having SMM MICs of 4 and 32 μg/ml, resulted in survival rates of 100% and 87.5% in the two groups, respectively.
In this study, we developed a simple visual method to test SMM activity against N. seriolae. 相似文献
7.
The effect of aqueous extract of Cratoxylum formosum on innate immune response and disease resistance in tilapia Oreochromis niloticus was investigated. The fish were fed diets containing 0% (control), 0.5% (diet 1), 1% (diet 2), and 1.5% (diet 3) of C. formosum aqueous extract for 30 days. At the end of the experimental period, parameters of innate immune response including phagocytosis
of blood leukocytes, lysozyme activity in plasma, and respiratory bust activity were examined. Feeding the fish with diet
2 and diet 3 for 20 days enhanced phagocytic activity and for 30 days stimulated lysozyme and respiratory burst activities.
Diet 1 increased the phagocytic activity at 30 days, but did not affect the other measured parameters. All parameters were
not significantly changed (P > 0.05) in the control group throughout the experiment. Following 30 days of feeding, fish were infected with S. agalactiae. The cumulative mortalities of bacterial-infected tilapia that were fed diet 1, diet 2, and diet 3 were 56, 12, and 10%,
respectively, compared with 85% in the control group. These results indicate that the aqueous extract of C. formosum may elevate the innate immune response and enhance disease resistance in tilapia. 相似文献
8.
To investigate the emotional reactivity of fish in a novel environment, the swimway test was developed. The swimway apparatus
consists of a shaded start chamber and an open, illuminated swimway. Fish were first introduced and habituated to the start
chamber. A door partitioning the start chamber from the swimway was then opened, and behavioral responses of the fish in the
apparatus were measured. By using the swimway test, behavioral responses to a novel environment of bluegill Lepomis macrochirus, crucian carp Carassius langsdorfii, and goldfish Carassius auratus were quantified and compared. The emotional reactivities in blue gill were found to be the lowest and crucian carp the highest,
indicating bluegill are relatively active or ‘bold’, and that the crucian carp are relatively passive or ‘shy’, in a novel
environment. It is suggested that the swimway test is applicable to examning inter-species differences in relative emotional
reactivity or boldness in a simplified novel situation. 相似文献
9.
Megumi Matsumoto Mahumoud Tanekey Amer Kyosuke Araki Atsushi Nishitani Kazuma Hayashi Yutaka Takeuchi Kazuhiro Shiozaki Atsushi Yamamoto 《Fisheries Science》2018,84(5):857-867
Interleukin-10 (IL-10) is an anti-inflammatory cytokine and negatively regulates cell-mediated immunity (CMI) induction by inhibiting cytokine production in type 1 T helper cells. IL-10 genes have been isolated from several fish, and inflammatory cytokine inhibition by IL-10 has been well examined. However, a CMI regulator of IL-10 in fish has not yet been identified. In this study, we cloned the IL-10 gene in amberjack Seriola dumerili and analyzed its function using its recombinant protein (rIL-10). In an in vitro culture experiment, gene expression of inflammatory cytokines was suppressed in leukocytes incubated with rIL-10 compared with cells that only received Nocardia seriolae stimulation. This result suggests amberjack IL-10 has conserved function as an inflammatory cytokine inhibitor. Bactericidal activity of amberjack cells against intracellular pathogen stimulation was decreased in a rIL-10 dose-dependent manner. Furthermore, a significant reduction in the T-bet/GATA-3 ratio was observed in N. seriolae living cell (LC)?+?rIL-10-injected fish. Taken together, these results suggest amberjack rIL-10 suppresses CMI induction both in vitro and in vivo. In addition, the number of IgM+ cells among spleen leukocytes in N. seriolae?+?rIL-10-injected fish was higher than in only N. seriolae LC, suggesting that Th2-dominant immunity was induced by adding rIL-10. 相似文献
10.
We analysed the genetic diversity of Melicertus kerathurus (Penaeidae), a commercially valuable penaeid shrimp that is distributed in the Mediterranean Sea and eastern Atlantic Ocean.
We examined the polymorphism of a 494 bp DNA segment of the mitochondrial COI region in 173 individuals, sampled in nine Mediterranean
and two Atlantic samples, covering the whole range of the species from the tropical waters of the Gulf of Guinea to the eastern
part of the Mediterranean Sea. The mean nucleotide and haplotype diversities were π = 0.00275 and h = 0.718, respectively, for the global data set, with the highest values occurring in the African samples and the lowest in
the Adriatic Sea. A clear sample differentiation was found (F
st = 0.194), but this did not reflect a geographical pattern and there were only faint traces of an Atlantic–Mediterranean subdivision.
Mismatch analysis and a high significant negative value of Tajima’s D suggested that M. kerathurus is not at mutation drift-equilibrium, but underwent a recent expansion after a period of low effective sample size. A postglacial
recolonisation of the Mediterranean from an Atlantic refuge could be hypothesised based on these data. 相似文献
11.
Besides various physiological and biological indices, stress in fish can be expressed directly by changes in their behaviour.
Electrofishing point sampling approach based on CPUE (catch per unit effort) was used to evaluate fish density (escapement)
into the littoral zones of four Czech ponds as a reaction to the occurrence and hunting activities of great cormorant (Phalacrocorax carbo sinensis) flocks. The behaviour of two-year-old common carp (Cyprinus carpio) before and after cormorant arrival was compared. Significant differences (P < 0.001) in CPUE were recorded in fish density before and after cormorant arrival on all of four ponds under study—Žofinsky:
0.04 ± 0.18 and 22.38 ± 26.87 (mean ± SD), Stary Hospodář: 0.05 ± 0.29 and 25.49 ± 25.45, Žebrákov: 0.16 ± 0.57 and 28.58 ± 24.75
and Travičny: 0.03 ± 0.19 and 17.18 ± 18.20, respectively. The evaluation of fish wounding in the CPUE fish samples proved
the proportion of fish injured by cormorant attacks ranging from 3.33 to 18.19% in the ponds under study. 相似文献
12.
Issei Nishiki Mikiko Furukawa Sho Matui Toshiaki Itami Toshihiro Nakai Terutoyo Yoshida 《Fisheries Science》2011,77(3):367-373
In Japan, Lactococcus garvieae infection has been the main fish disease in aquaculture. Although commercial oral and injectable vaccines have been used
to prevent L. garvieae infection in Japan, L. garvieae has been isolated not only from unvaccinated fish but also from vaccinated fish in which immunity induced by vaccination
had diminished. In order to obtain epidemiological information on this fish pathogen, we conducted biased sinusoidal field
gel electrophoresis (BSFGE) pattern analysis and phage typing of L. garvieae isolates (n = 427) from fish in Japan. These isolates were obtained from 13 different fish species between 1980 and 2007. In the BSFGE
analysis, L. garvieae isolates were classified into 17 groups (S1–S17) based on the SmaI digestion patterns and into four groups (A1–A4) based on the ApaI digestion patterns. Phage typing revealed five different phage susceptibility profiles (A–E) in L. garvieae isolates. Since 2005, comparisons of the results of phage typing and BSFGE have indicated the presence of a novel genotype
(S16/A4) with phage type E. All the strains belonging to this type showed lincomycin sensitivity. 相似文献
13.
Bacillus circulans PB7, isolated from the intestine of Catla catla, was evaluated for use as a probiotic supplement in the feeds for the fingerlings of Catla catla. The effect of supplement on the growth performance, feed utilization efficiency, and immune response was evaluated. Catla
fingerlings (ave. wt. 6.48 ± 0.43 g) were fed diets supplemented with 2 × 104 (feed C1), 2 × 105 (feed C2), and 2 × 106 (feed C3) B. circulans PB 7 cells per 100 g feed for 60 days at 5% of the body weight per day in two equal instalments in triplicate treatments.
The control feed (CC) was not supplemented with the B. circulans. All the feeds were isocaloric and isonitrogenous. Fish fed with feed C2 displayed better growth, significantly (P ≤ 0.05) highest RNA/DNA ratio, a lower feed conversion ratio (FCR), and a higher protein efficiency ratio (PER) than the
other experimental diets. Highest carcass protein and lipid was also observed in the fish fed C2 feed compared to the others.
Significantly (P ≤ 0.05), highest protease was recorded in fish fed feed C2 (47.9 ± 0.016) and lowest in fish fed feed C3 (32.10 ± 0.009),
where α-amylase activity did not differ significantly (P ≤ 0.05) beyond the lowest inclusion level. ALP, ACP, GOT, and GPT in the liver of Catla catla were the highest (P ≤ 0.05) in fish fed C2 feed. The highest TSP, albumin, and globulin was observed in fish treated with C2 feed after 60 days
feeding trial, but the lowest glucose level was observed in the same treatment. After the feeding trial, the non-specific
immunity levels and disease resistance of fish were also studied. Phagocytic ratio, phagocytic index, and leucocrit value
were the highest in fish fed feed C2. After the feeding trial, the fish were challenged for 10 days by bath exposure to Aeromonas hydrophila (AH1) (105c.f.u. ml−1 for 1 h, and, after 7 days, 107c.f.u. ml−1 for 1 h). Highest survival percentage was observed in fish fed with feed C2 compared with only 6.66% in the controls, which
indicated the effectiveness of B. circulans PB 7 in reducing disease caused by A. hydrophila. 相似文献
14.
Unal G Erdoğan E Oğuz AR Kaptaner B Kankaya E Elp M 《Fish physiology and biochemistry》2008,34(4):447-454
Chalcalburnus tarichi is an endemic cyprinid species living in the Lake Van basin, in eastern Anatolia, Turkey. The present study was undertaken
to determine which hormones induce oocyte maturation in C. tarichi. The levels of 17α,20β,21-trihydroxyprogesterone (20β-S), progesterone (P), 17α-hydroxyprogesterone (17α-HOP), 11-deoxycortisol
(11-DOC), and 17α-hydroxy-20β-dihydroprogesterone (17,20β-P) were measured in fish caught from Lake Van and the Karasu River,
and injected with human chorionic hormone (hCG) (1,000 and 1,500 IU/kg). Oocytes of fish caught from the lake were also incubated
in vitro with different doses (50, 200, and 1,000 ng/ml) of 20β-S, 17α-HOP, 11-DOC, and 17,20β-P. 11-DOC was found to be the
most effective hormone among those measured for inducing oocyte maturation in vivo and in vitro. 17,20β-P could not be determined
in the plasma of any fish in vivo (P < 0.05). 1,000 IU/kg dose of hCG given by injection caused a statistically significant increase in all plasma hormone levels
(P < 0.05). It was found that there was a significant decrease in the P level only at 1,500 IU/kg dose of hCG injected (P < 0.05), while the level of other hormones increased at this dose (P < 0.05). It was also determined that all the hormones were effective in germinal vesicle breakdown (GVBD) in in vitro oocyte
culture (P < 0.05). However, 11-DOC was found to be the most effective hormone in GVBD at a dose of 200 ng/ml (70% GVBD). In conclusion,
11-DOC synthesized during final oocyte maturation in C. tarichi was found to be a potent inducer of GVBD, which shows that 11-DOC may be described as an oocyte maturation steroid in this
species. 相似文献
15.
Otolith microchemical analyses of the strontium (Sr) and calcium (Ca) concentrations in the eels Anguilla japonica and A. anguilla caught in Tokyo Bay were undertaken to reconstruct the eels’ migratory histories. A. japonica in the yellow stage (immature stage) were caught in a bay without any adjacent rivers or streams. A. anguilla was in the silver stage (early maturing stage), and the eel was confirmed to have just begun spawning migration to the open
ocean from Tokyo Bay based on the otolith Sr:Ca ratios, which showed a typical catadromous life history with low Sr:Ca ratio
values throughout the eel’s life after recruitment. The mean Sr:Ca ratios in A. japonica from the elver mark to the otolith edge indicated the eels belonged to several general categories of migratory histories,
including sea eels (average Sr:Ca ratio ≥6.0 × 10−3) and estuarine eels (average Sr:Ca ratio 2.5 to 6.0 × 10−3) based on the criteria reported previously in A. japonica. All eels had a certain freshwater life period, although the period was highly variable among fish. These results indicate
that A. japonica has a flexible pattern of migration, with the ability to adapt to various habitats and salinities. 相似文献
16.
Carlo C. Lazado Christopher Marlowe A. Caipang Sanchala Gallage Monica F. Brinchmann Viswanath Kiron 《Fish physiology and biochemistry》2010,36(4):883-891
This study identified phytase-producing bacteria that were previously isolated from the gastrointestinal tract of Atlantic
cod, Gadus morhua and determined its effect on head kidney leukocytes. Out of the 216 bacterial strains tested, the two phytase producers were
identified as Pseudomonas sp. and Psychrobacter sp. based on their 16S rDNA sequence. Crude phytase from these two bacterial strains was produced employing the shake flask
method. Even though the total protein of the crude phytase was not significantly different for the two bacteria, the phytase
activity of the crude enzyme produced by Pseudomonas sp. (97.1 ± 16.7 U) was significantly higher than that of the enzyme from Psychrobacter sp. (75.9 ± 2.4 U). When cod head kidney leukocytes were incubated with the crude phytase (50 μg ml−1), it resulted in enhanced cell proliferation, higher myeloperoxidase, and acid phosphatase activities. Extracellular responses—respiratory
burst activity and hydrogen peroxide production were not enhanced by the crude enzyme. As a consequence, the growth of two
pathogenic bacteria Aeromonas salmonicida and Vibrio anguillarum was not suppressed by the supernatants obtained from head kidney leukocytes incubated with the crude bacterial phytase. Thus,
the enzyme from phytase-producing intestinal bacteria of Atlantic cod can stimulate intracellular head kidney leukocyte activities
but not the production of extracellular substances that are involved in antibacterial response. These have implications on
the potential use of bacterial phytase as feed supplement to boost cellular immune response of the fish and could be employed
as a health management strategy in culture systems. 相似文献
17.
Shude Xu Liang Zhang Qingyang Wu Xuebing Liu Shuqi Wang Cuihong You Yuanyou Li 《Aquaculture International》2011,19(5):1007-1018
In order to evaluate the feasibility of dried seaweed Gracilaria lemaneiformis (Bory) as a dietary ingredient for the rabbitfish Siganus canaliculatus (Park), juvenile fish (average weight 15.64 ± 0.15 g) were fed with two isonitrogenous (32% crude protein) and isolipid (8%
lipid) diets for 8 weeks, with one diet incorporating 33% of dried G. lemaneiformis (DGL), which accounted for 6% protein and 17% carbohydrate (DGL-diet), and the other containing no DGL (control diet). After
8 weeks, the growth performance and feed utilization efficiency of fish fed with the DGL-diet were inferior to fish fed with
the control diet, although some non-specific immunity parameters were better in fish fed with the DGL-diet compared with those
of fish fed control diet. Nutritional composition (whole body composition, amino acid, and fatty acid composition in dorsal
muscle) except methionine and tyrosine in muscle showed no differences between the two groups. Furthermore, the survival rate
of fish and apparent digestibility coefficient of diets were the same between the two groups. These results indicated that
incorporation of DGL in diet of S. canaliculatus is feasible, and further studies are recommended to optimize the level of DGL in diet of S. canaliculatus to improve growth performance. 相似文献
18.
The ability of the probiotic bacterium Sulfitobacter to inhibit the growth of two virulent strains (psh-9019 and ATCC 43306) of the fish pathogenic bacterium Vibrio anguillarum was tested. Probiotic and pathogenic bacteria were inoculated individually or together in three different types of media.
Two of the phytoplankton media tested were filtrates of phytoplankton Chlorella vulgaris cultures, either the live phytoplankton (live-CV) or a condensed phytoplankton (condensed-CV). Phytoplankton culture medium,
ESM, was used as a control medium without phytoplankton. In ESM, Sulfitobacter decreased the viable cell counts of both V. anguillarum strains by tenfold. In the live-CV filtrate, V. anguillarum was eradicated by Sulfitobacter within one week. Although colony counts of strain ATCC 43306 declined during the two-week co-incubation with Sulfitobacter, its growth was not fully inhibited; however, the counts were tenfold lower than that in control ESM medium. Neither of the
pathogenic V. anguillarum strains were inhibited nor eradicated by Sulfitobacter in the condensed-CV filtrate medium. Our study indicates that commercially available condensed phytoplankton can enhance
the growth of V. anguillarum. Thus, the addition of live phytoplankton, including the introduction of Roseobacter clade bacteria to fish larvae tanks, leads to better biocontrol of the fish pathogen V. anguillarum. 相似文献
19.
The ability of an algicidal bacterium Marinobacter salsuginis strain BS2, isolated from shrimp pond water, to reduce shrimp mortality was investigated under laboratory conditions. When
two species of shrimp (Penaeus monodon and Litopenaeus vannamei) (body length 1.5–1.8 cm) were cultured together with the dinoflagellate Noctiluca scintillans, nearly 80 % of the shrimps died within 7 days. However, when bacterial strain BS2 was also added to the culture, N. scintillans was killed within 48 h, and shrimp survival rates on the 7th day improved from 23 to 87 % for both P. monodon and L. vannamei. The bacterium BS2 alone had no effect on shrimp condition. Under conditions of increased dissolved oxygen, the effect of
using BS2 was greater, and shrimp survival rates improved even more dramatically, from 26 to 98 %. These studies provide the
first evidence that the use of killing bacteria, isolated from shrimp culture water, can suppress harmful algal blooms (HABs)
and thus restore the efficiency of shrimp production. The control of HABs in this way in shrimp culture farms would be a major
benefit for shrimp production. 相似文献
20.
Chinese chive Allium tuberosum oil was studied for its diallyl sulfide content and its antimicrobial activity against Flavobacterium columnare in fish both in vitro and. The oil was found to have a very low concentration of diallyl monosulfide relative to the other
diallyl sulfides (diallyl disulfide, diallyl trisulfide, and diallyl tetrasulfide) identified. In the in vitro study, the
Chinese chive oil had a bacteriocidal effect on all tested strains of F. columnare, with varied minimal inhibitory concentrations. The median lethal dose (LD50) of FC4 for Nile tilapia Oreochromis niloticus was determined to be 3.72 × 103 CFU/fish. In the in vivo trial, no mortality was observed in fish fed fish diets supplemented with 800 mg/kg Chinese chive
oil and 100 mg/kg of oxytetracycline hydrochloride 5 days prior to infection with F. columnare strain 4 at a LD50. These results indicate that Chinese chive oil has the potential to replace antibiotics for controlling fish disease caused
by F. columnare. 相似文献