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1.
Bacterial pathogens causing diseases in fishes have broad host ranges, and may cause high mortality or ongoing chronic infections. Pathogen treatments using antibiotics are becoming limited due to increasing concerns for the development of resistance and environmental dissemination of bacteria harboring resistance genes. This study aimed to determine whether nano‐emulsions of selected plant‐derived essential oils (Origanum vulgare, Eucalyptus globulus, Melaleuca alternifolia and Lavendula angustifolia) were bacteriostatic or bactericidal to Aeromonas hydrophila, Streptococcus iniae and Photobacteriumdamselae subspecies damselae. All treatments showed antibacterial activity, and in almost all cases the activity of the nano‐emulsions was superior to their essential oil counterparts. Origanum vulgare (oregano) nano‐emulsion had the most effective antibacterial activity, with a minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 3.12 µg/ml against all three species; substantially better than tetracycline. The present study highlights the potential of new formulations of essential oils to enhance bacterial disease control in cultured fish.  相似文献   

2.
This study evaluated the effect of short-term baths with the essential oils (EOs) of Lippia sidoides, Ocimum gratissimum and Zingiber officinale on the survival, haematological, biochemical and histopathological parameters of native fish tambaqui (Colossoma macropomum), challenged with Aeromonas hydrophila. After challenge, the fish infected with A. hydrophila received therapeutic baths of 60 min, for five consecutive days. Treatments were as follows: challenged and not treated; challenged and treated with 10 mg L?1 of gentamicin; challenged and treated with EO of L. sidoides (2.5 and 5.0 mg L?1); challenged and treated with EO of O. gratissimum (5.0 and 10.0 mg L?1); challenged and treated with Z. officinale EO (5.0 and 10.0 mg L?1). The highest survival rates were 89.5% (fish treated with 5.0 mg L?1 of O. gratissimum EO) and 75.0% (fish treated with 5.0 mg L?1 of L. sidoides EO). Reductions in the haematocrit percentage, haemoglobin and erythrocyte number were observed in fish treated with L. sidoides and Z. officinale EOs compared with control fish. Mild to moderate damage to the liver tissue of fish after challenge and EO treatments were observed. It is suggested that baths containing O. gratissimum and L. sidoides EOs consist in a viable treatment to increase survival rates of C. macropomum infected with A. hydrophila.  相似文献   

3.
The aim of this study was to evaluate dietary dosages of Microcystis on the immune response and disease resistance against infections due to the opportunistic pathogen Aeromonas hydrophila in Labeo rohita fingerlings. Labeo rohita fingerlings were fed diet containing 0 (Control), 0.5, 1.0 and 5 g Microcystis powder kg?1 dry diet for 90 days. Three replicate groups of fish averaging 20 ± 2 g were fed for 3 months daily. At 30 days interval, samples were assayed for different biochemical [serum total protein, albumin, globulin, albumin:globulin (A:G) ratio] and immunological (superoxide anion production, lysozyme and serum bactericidal activity) parameters. The results demonstrate that fish fed Microcystis showed increased levels of lysozyme, serum bactericidal activity, serum protein and albumin (P ≤ 0.05) as compared with the control group. After 90 days, fish were challenged with A. hydrophila and mortality (%) was recorded up to day 10 postchallenge. The group fed 1.0 g Microcystis kg?1 dry diet showed the highest percentage survival (72%). These results indicate that Microcystis aeruginosa stimulates the immunity and makes L. rohita more resistant to infection by A. hydrophila when fed in dried form in feed.  相似文献   

4.
The specific and non‐specific immune parameters and protection of European eels (Anguilla anguilla) were evaluated after bathing eels with Aeromonas hydrophila. Two hundred eels were distributed into two equal groups and bathed with Phosphate‐buffered saline (Control group) or 1.0 × 107 cfu mL?1 A. hydrophila (Test group) for 1 h respectively. Then, eels were bled aseptically from the caudal sinus on 1, 4, 7, 14 and 28 days post treatment. The blood cells were used to evaluate the cellular immunity and the serum was used to determine the titres of specific antibody as well as the activities of superoxide dismutase (SOD) and lysozyme. Eels from both groups were challenged by intraperitoneal injection of 1.0 × 107 cfu of A. hydrophila on 28 and 42 days post bathing. The results show that eels bathed in A. hydrophila significantly (P < 0.05) enhanced the proliferation of different types of blood cells and the serum titres of anti‐A. hydrophila antibody. The Relative Percent Survival (RPS) after challenge on 28 and 42 days post bathing in Test group vs. Control group was 40% and 50% respectively. These results suggest that bathing European eels in A. hydrophila would positively affect specific as well as non‐specific immune parameters and protect against A. hydrophila infection in freshwater farming.  相似文献   

5.
This study was aimed to address the promising evaluation of Cissus quadrangularis plant (stem) and lipopolysaccharide (LPS from bacteria) supplemented diets on innate immune response in Lates calcarifer fingerlings against Aeromonas hydrophila infection. Fingerlings were fed supplemented diets containing four different concentrations of C. quadrangularis (0.5, 1.0, 1.5 and 2.0 g kg?1 feed), LPS (25, 50, 75 and 100 mg kg?1 feed) and control (normal formulated diet) for 60 days. The fish fingerlings fed supplemented diet displayed significant differences (P < 0.05) in specific growth rate (SGR) and relative percentage survival compared to the control group fed without C. quadrangularis and LPS‐supplemented diet. Fingerlings were injected intraperitoneally with 100 μL lethal dose of A. hydrophila containing 1 × 106 CFU g?1. Supplementation of C. quadrangularis and LPS diet significantly increased biochemical profile such as protein, lipid and carbohydrate content, haematological parameters of L. calcarifer fingerlings in different experimental periods when compared with the control group. Dietary doses of C. quadrangularis and LPS‐supplemented diet significantly influenced growth performance and increased survival rate in L. calcarifer fingerlings against A. hydrophila infection.  相似文献   

6.
Four alkaloids (Sanguinarine, 6‐Methoxyl‐dihydro‐chelerythrine, Cryptopine and β‐Allocryptopine) were isolated from aerial parts of Macleaya microcarpa (Maxim) Fedde using bioassay‐guided isolation method, and the inhibitory activity of ethanolic extract, various fractions and these four alkaloids against four fish pathogenic bacteria (Aeromonas hydrophila, Aeromonas salmonicida, Vibrio anguillarum and Vibrio harveyi) was assessed in vitro using the agar dilution method and the microdilution assay method respectively. A. hydrophila was the most sensitive strain to all the tested compounds. Minimum inhibitory concentration (MIC) values were lower for sanguinarine against all tested Gram‐negative strains than other three alkaloids, with MIC values of 12.5 mg L?1 for A. hydrophila and 50 mg L?1 to other pathogenic bacteria. Followed by 6‐methoxyl‐dihydro‐chelerythrine, which showed considerable antibacterial activity with MIC values of 80 mg L?1 for A. hydrophila, 100 mg L?1 for V. harveyi, and 125 mg L?1 for both V. anguillarum and A. salmonicida. Cryptopine and β‐allocryptopine revealed similar inhibitory activity with MIC values of 100 mg L?1 for A. hydrophila and 200 mg L?1 for other three bacterial species. These finding provided evidence that extract, as well as isolated compounds from M. microcarpa might be potential sources novel antibacterial agents for the treatment of fish infectious diseases.  相似文献   

7.
This study evaluated the efficiency of differently prepared vaccines against Aeromonas hydrophila in the hybrid surubim (Pseudoplatystoma corruscans × P. reticulatum). Survival and haemato‐immunological parameters were compared between the treatments: non‐vaccinated fish (C); bacterin‐vaccinated fish (B); bacterin plus oral booster vaccinated fish (B+O); bacterin and toxoid‐vaccinated fish (B+T) and bacterin, toxoid and oral booster‐vaccinated fish (B+T+O). Fourteen‐days vaccinated fish from B+O and B+T+O were fed with an oral booster for 4 days. After 1 week, the fish were intraperitoneally challenged with 2 × 108 CFU mL?1 of A. hydrophila. Fish from the treatment B+T+O showed the lowest cumulative mortality (11.36%) 96 h after challenge, compared with other treatments (22.72–44.04%), and a relative survival of 74%. Serum immunoglobulin in B+T+O fish was higher than in other treatments. All vaccinated fish showed an increased agglutination titre when compared with non‐vaccinated fish, both before and after challenge. Fish fed with oral booster showed an increase in phagocytic percentage before and after challenge. It can be inferred that the oral booster vaccination was efficient in reducing mortality in hybrid surubim by enhancing the response against haemorrhagic septicaemia due to A. hydrophila infection.  相似文献   

8.
Diseases caused by motile aeromonads in freshwater fish have been generally assumed to be linked with mainly Aeromonas hydrophila while other species were probably overlooked. Here, we identified two isolates of non‐A. hydrophila recovered from Nile tilapia exhibiting disease and mortality after exposed to transport‐induced stress and subsequently confirmed their virulence in artificial infection. The bacterial isolates were identified as Aeromonas jandaei and Aeromonas veronii based on phenotypic features and homology of 16S rDNA. Experimental infection revealed that the high dose of A. jandaei (3.7 × 106 CFU fish?1) and A. veronii (8.9 × 106 CFU fish?1) killed 100% of experimental fish within 24 h, while a 10‐fold reduction dose killed 70% and 50% of fish, respectively. When the challenge dose was reduced 100‐fold, mortality of the fish exposed to A. jandaei and A. veronii decreased to 20% and 10%, respectively. The survivors from the latter dose administration were rechallenged with respective bacterial species. Lower mortality of rechallenged fish (0%–12.5%) compared to the control groups receiving a primary infection (37.5%) suggested that the survivors after primary infection were able to resist secondary infection. Fish exposed to either A. jandaei or A. veronii exhibited similar clinical signs and histological manifestation.  相似文献   

9.
In the present study, the chemical composition and antifungal activity of the essential oils of the three Lamiaceae species, black tyme (Thymbra spicata L.), oregano (Origanum onites L.) and savory (Satureja tymbra L.) against Saprolegnia parasitica Coker strains (3) were evaluated. The composition of oils was analysed by gas chromatography/mass spectrometry (GC/MS). The major constituent of the oils was carvacrol (82.68% in Thymbra spicata, 82.24% in Origanum onites and 52.38% in Satureja tymbra). The antifungal activity of essential oils was determined by a tube dilution and disc diffusion method. All essential oils inhibited fungal strains at concentration of 100 μL mL?1. The essential oil of O. onites and T. spicata was the most active (MIC 10 and 50 μL mL?1, respectively). Thymol did not show inhibiting activity. The essential oils exhibited stronger inhibition than pure carvacrol. Essential oil derived from Tymbra, Origanum and Satureja species has the potential to be used as health control of rainbow trout (Oncorhyncus mykiss) against S. parasitica infection. This study describes the antifungal activity of three essential oils for developing alternative and native control methods against Saprolegniasis.  相似文献   

10.
Sanguinarine (SA), with antimicrobial and antiparasitic activities against fish pathogens, exhibits great potential commercial use in aquaculture. However, little information on pharmacokinetics of SA restricts further application in aquaculture. In this study, pharmacokinetics of SA in common carp (Cyprinus carpio) following a single intraperitoneal administration [10 mg kg?1 BW (body weight)] was evaluated by high‐performance liquid chromatography (HPLC). The peak concentration (Cmax) of SA in kidney was 11.8 μg g?1, which was higher than in other tissues and plasma. The terminal half‐life in fish tissue and plasma was as follows: 42.3 h (kidney) > 37.2 h (liver) > 20.1 h (gill) > 18.8 h (muscle) > 10.9 h (spleen) > 10.0 h (plasma). Additionally, we determined the bacterial loads in tissues of common carp infected with Aeromonas hydrophila after i.p. administration of SA at 0, 5, 10 and 20 mg kg?1 BW. The results showed that i.p. administration of SA at 10 mg kg?1 BW significantly enhanced antibacterial efficacy against A. hydrophila, where the antibacterial ratio in the gill, kidney, spleen and liver on day 5 was 95.13%, 93.33%, 90.09% and 92.82%, respectively. Overall, these results suggested the potential of SA to treat A. hydrophila infection in common carp farming industry.  相似文献   

11.
A 50‐day growth trial was conducted to evaluate the efficacy of Chlorella vulgaris (Beijerinck) as an ingredient in the diets of giant freshwater prawn Macrobrachium rosenbergii (De Man) postlarvae (PL30). Immune response (total haemocyte count and prophenoloxidase activity) was also assessed by subjecting postlarvae to a challenge test against Aeromonas hydrophila (Chester) for 14 days. Iso‐nitrogenous and iso‐lipidic test diets were prepared using a fishmeal‐based‐positive control diet (D0) and four basal diets with inclusion levels of 2% (D2), 4% (D4), 6% (D6) and 8% (D8) C. vulgaris. Postlarvae of M. rosenbergii were randomly stocked (mean initial body weight of 0.19 ± 0.02 g) in 30‐L tanks in three replicates per dietary treatment for evaluation of growth performance. Another set of postlarvae (mean initial body weight of 1.25 ± 0.02 g) was randomly distributed in 95‐L tanks in three replicates per dietary treatment for the assessment of immune response. Results showed that specific growth rate was significantly higher (P < 0.05) in postlarvae fed D4 and D6. Variations in values for carcass protein, lipid, moisture and ash were also evident. Postlarvae fed diets with Chlorella showed increased prophenol oxidase activity and total haemocyte counts. Moreover, survival rate after challenge with A. hydrophila was significantly increased (P < 0.05). Inclusion of C. vulgaris in diets enhanced immune response and resistance of M. rosenbergii postlarvae against A. hydrophila infection.  相似文献   

12.
The aim of this study was to evaluate the effects of dietary lipids on protein‐sparing and lipoprotein lipase (LPL) mRNA expression in culture using 360 juvenile soft‐shelled turtles (Pelodiscussinensis) (initial weight 4.26 ± 0.14 g). The turtles were allotted to six diets with three duplicates for 60 days. A control diet with 46% protein and 55% fishmeal (CD) and five isonitrogenous diets with 41.3% protein and 45% fishmeal (F, S, L1, L2 and L3) were used, containing the following three lipid types: fish oil, soybean oil and mixed oils (soybean oil: fish oil = 1:1). The results showed that the survival rate was not affected by dietary lipids (P > 0.05). The highest weight gain and lowest feed coefficient ratio were seen in the L3 diets (P < 0.05). Turtles fed with L2 and L3 diets had lower superoxide dismutase activities, higher alanine aminotransferase activities and higher cholesterol concentrations than those exposed to other diets (P < 0.05). Hepatic LPL activity and LPL mRNA expression were higher in the L3 diets than in the other diets (P < 0.05). Overall, there were obvious protein‐sparing effects of dietary lipids and LPL mRNA expression was stimulated by high dietary lipids in soft‐shelled turtles in this study.  相似文献   

13.
In this study, the effect of extracts of two herbs (Oliviera decumbens and Satureja khuzestanica) on immune response of carp was investigated. At the beginning of experiment, fish were divided to two groups including vaccinated (using vaccine developed against A. hydrophila) and non‐vaccinated. Fish in both groups were fed diets containing O. decumbens and S. khuzestanica and combination of two herbal extracts for 5 weeks. Control fish (negative control) and fish vaccinated only (positive control) were fed basal diets without supplements of herbal extracts. Lysozyme activity, antibody titre, complement activity and bactericidal activity in serum were measured. After 5 weeks feeding, fish were infected with A. hydrophila and mortalities were recorded. In both experimental groups, no significant differences were found in terms of alternative haemolytic complement (ACH50) activity and antibody titres of Serum. In non‐vaccinated fish group, lysozyme and bactericidal activity of fish fed S. khuzestanica or combination of O. decumbens and S. khuzestanica was higher compared with control and other experimental treatments. In vaccinated fish group, the lysozyme and bactericidal activity was not significant in all treatments compared with control group. The results of this study showed that feeding non‐vaccinated and vaccinated carp with only S. khuzestanica or in combination with O. decumbens enhance only some immunity indices including lysozyme and bactericidal activity in non‐vaccinated fish and these extracts have no immunological stimulatory role on vaccinated individuals.  相似文献   

14.
A 60 days study was conducted to evaluate the efficacy of water extract of Ocimum sanctum Linn. leaf on the immune response and disease resistance of Labeo rohita fingerlings against the Aeromonas hydrophila infection. Ocimum sanctum extract was incorporated in the diets (at 0.0%, 0.05%, 0.1%, 0.2%, 0.5% and 1%) of Labeo rohita, rohu fingerlings (6.6 ± 0.013 g). After 42 days blood, plasma and serum were sampled to determine super oxide anion production, lysozyme activity, total immunoglobulin in plasma, blood glucose, serum total protein, albumin, globulin, albumin:globulin ratio, WBC, RBC, haemoglobin content. Fish were challenged with A. hydrophila after 42 days and mortalities were recorded over 18 days post infection. The results demonstrate enhanced super oxide anion production, lysozyme activity, total immunoglobulin in plasma, serum total protein, globulin, total RBC counts, total WBC counts and haemoglobin content (P < 0.05) in treatments group compared with control group. Dietary O. sanctum extracts of 0.2% showed significantly (P < 0.05) higher protection relative percentage survival (RPS 40.00 ± 5.773%) against A. hydrophila infection than control. These results indicate that O. sanctum leaf extract stimulates the immunity and makes L. rohita more resistant to bacterial infection (A. hydrophila).  相似文献   

15.
Aeromonas hydrophila and Gyrodactylus cichlidarum are common pathogens that induce significant economic losses in farm‐reared Nile tilapia. Nowadays, the sudden appearance of fish mortalities was exaggerated due to mixed and multiple infections. During summer 2016, mass mortality among earthen pond‐farmed Nile tilapia was reported. Clinico‐pathological, bacteriological and parasitological examinations have been demonstrated. As well, the water quality parameters were assessed. The clinical and histopathological findings of the moribund and recently dead fish were characterized by generalized septicaemic signs. The water quality parameters were significantly elevated over the permissible levels, whereas there was an elevation in nitrite (0.04 mg/L), un‐ionized ammonia (0.8 mg/L), hydrogen sulphide levels (153.1 mg/L) and organic matter content (3.79 mg/L). A. hydrophila was identified based on phenotypic characterization, API 20E features and the homology of 16S rRNA gene sequence analysis. In addition, PCR data confirmed the presence of aerolysin (aerA) and haemolysin (hly) genes in the identified A. hydrophila isolates. Gene sequencing and phylogenetic analysis based on 16S rRNA sequence confirmed that A. hydrophila H/A (accession No. MN726928) of the present study displayed 98%–99% identity with the 16S rRNA gene of A. hydrophila. Furthermore, the monogenetic trematode, G. cichlidarum was identified in the wet mounts from the skin and gills of the examined fish with a high infestation rate. In this context, it was reported that the synergistic co‐infection of A. hydrophila and G. cichlidarum with deteriorated water quality parameters could induce exaggerated fish mortalities during hot weather.  相似文献   

16.
In the present study, the chemical composition and the antifungal properties against Saprolegnia parasitica (in vitro and in vivo) of the essential oils of thyme (Satureja cuneifolia) from Mediterranean region of Turkey were evaluated for the first time. The composition of oils was analysed using gas chromatography/mass spectrometry (GC/MS). The major constituents of oil of S. cuneifolia were cavracrol (46,84%) and cymene (16.90%). Antifungal effects of S. cuneifolia essential oil against S. parasitica strains (A1 and E1) were detected by disc diffusion and tube dilution assays. The antifungal effect of S. cuneifolia was determined to be stronger against S. parasitica E1 isolate (MIC 50 μL mL?1, MLC 250 μL mL?1) compared with S. parasitica A1 isolate (MIC 50 μL mL?1, MLC 500 μL mL?1). Following in vitro assays, effective doses of S. cuneifolia for disease control in rainbow trout eggs experimentally infected with S. parasitica were investigated. For this aim, infected eggs were treated with the essential oil (0, 5, 10, 20 and 50 ppm) during incubation period (21 days) after fertilization. Formalin (5 mL L?1) was used as positive control. Hatching rate of eggs at the end of incubation period were calculated. The highest hatching rates were recorded in S. parasitica E1 strain at 5 and 10 ppm concentrations of S. cuneifolia and in S. parasitica A1 strain at 10 and 20 ppm (P < 0.05).  相似文献   

17.
This study evaluated the effects of Jerusalem artichoke (JA) and Lactobacillus plantarum singly or combined on growth, immunity and disease resistance of Pangasius bocourti. In the first experiment, different concentrations of JA (0, 5, 10, 20, 40, 80 and 160 g kg?1) were administered to determine an optimal concentration on growth of P. bocourti. In the second experiment, the optimal concentration of JA (5 g kg?1) was combined with 108 cfu g?1 L. plantarum. In the final experiment, five randomly selected fish from the second experiment were challenged with Aeromonas hydrophila. Treatments for second and third experiments were 0 g kg?1 JA (Diet 1), 5 g kg?1 JA (Diet 2), 108 cfu g?1 L. plantarum (Diet 3) and 5 g kg?1 JA + 108 cfu g?1 L. plantarum (Diet 4). Fish fed 5 g kg?1 JA or 108 cfu g?1 of L. plantarum significantly improved specific growth rate (SGR), feed conversion ratio (FCR), serum lysozyme activity and postchallenge survival rate (PCSR). Dietary in the combination of JA and L. plantarum showed significantly enhanced SGR, FCR, serum lysozyme, phagocytosis, respiratory burst activities and PCSR compared with control and individual applications. Dietary JA and L. plantarum significantly stimulated growth, immunity and disease resistance of P. bocourti.  相似文献   

18.
The present trial was performed to evaluate the effect of dietary incorporation of dried Spirulina, Chlorella and their mixture on the immune status of Nile tilapia (Oreochromis niloticus) before and after artificial infection with pathogenic bacterium Aeromonas hydrophila (A. hydrophila). Two hundred and forty fish were divided into four groups: (a) a control group fed on a basal diet only, (b) a second group fed on a diet containing Spirulina 15%, (c) a third group fed on a diet containing Chlorella 15%, and (d) a fourth group fed on a diet containing a mixture of both Spirulina 15% and Chlorella 15%. At the end of the experiment (9 weeks), the four groups were experimentally infected with A. hydrophila for 7 days. Antioxidant enzymes, lysozyme and bactericidal activities and histopathological changes were determined just before the challenge test and 7 days post‐challenge. Significant (p ≤ 0.05) increases in fish body protein% before the challenge test and increases in serum antioxidant enzymes, lysozyme and bactericidal activity in the Chlorella and algal mixture groups before and after the challenge test were observed. Spirulina, Chlorella and their mixture groups significantly decreased serum malondialdehyde compared to the control group before and after the challenge test. Using Spirulina, Chlorella and their mixture mitigated the necrotic and degenerative changes induced by A. hydrophila and revealed well‐developed and multiple melanomacrophage centres. Thus, dietary Spirulina, Chlorella and their mixture inclusion in Nile tilapia fish proved to have a protective effect against A. hydrophila infection.  相似文献   

19.
A 35 days feeding trial was conducted to assess the haemato‐immunological response of Labeo rohita fingerlings fed ethanolic leaf extracts of Psidium guajava and Mangifera indica, and infected with Aeromonas hydrophila. Six iso‐nitrogenous (354.6–361.6 g kg?1) purified diets were prepared with graded level of leaf extracts viz., control (basal feed without any extract); TG‐5 (5 g kg?1 guava extract); TG‐10 (10 g kg?1 guava extract); TM‐5 (5 g kg?1 mango extract); TM‐10 (10 g kg?1 mango extract); and TGM (5 g kg?1 guava extract +5 g kg?1 mango extract). Haematological, immunological, biochemical, along with antioxidant enzyme activities were examined after a 35 day‐feeding trial and following a 7 day challenge with A. hydrophila. The haemoglobin, total leucocyte and erythrocyte counts, respiratory burst activity, lysozyme, total protein, albumin and globulin contents increased significantly (P < 0.05) in leaf extracts fed groups compared with the control in pre‐ and post‐challenge conditions. A significant (P < 0.05) decrease was observed in SOD (superoxide dismutase) and catalase activities of the treatment groups compared with the higher value in control. The trends in mortality indicated that groups of fish showing significantly elevated haemato‐immunological responses had the lowest mortality following challenge with A. hydrophila. The results showed that extracts of P. guajava and M. indica appear to be potential immunostimulant at an inclusion level of 5 g kg?1 in the diet of rohu. But, mixing of both the extract at similar level did not show any synergistic effect, which needs to be tested at its lower level of inclusion.  相似文献   

20.
Dietary supplementation (0, 10, 20, 40, 60, 80 g kg?1) of a nucleotide source (NuPro®) was evaluated on growth, nutrient utilization, haemato‐immunological responses and resistance to experimental infection of Nile tilapia. Fish (2.63 ± 0.63 g) were fed experimental diets to satiation three times a day for 75 days. Feed intake increased linearly with increasing levels of NuPro® promoting higher weight gain (P < 0.05). Survival, feed conversion and protein retention were not affected. Following the growth trial, fish were challenged with Aeromonas hydrophila by intraperitoneal injection. Survival and innate immune responses (phagocytosis and lysozyme activity) were not significantly affected. However, among the haematological variables, thrombocyte, leucocyte and monocyte counts increased linearly (P < 0.05). The indirect measurement of digestibility in juvenile Nile tilapia (122.32 ± 11 g) indicated a linear decrease in protein (1.41%), dry matter (5.72%) and energy (4.10%) digestibility coefficients as dietary supplementation increased (P < 0.05). NuPro® showed to be a beneficial additive to be supplemented in diets for juvenile Nile tilapia, providing 32.8% increase in feed intake and 28.8% in weight gain, as well as in thrombocyte, leucocyte and monocyte counts in blood, possibly indicating a more efficient defence response in the highest dietary supplementation levels tested.  相似文献   

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