In the present study, Indian shrimp, Penaeus indicus, were fed on diets supplemented with basil (Ocimum basilicum) oil (BO) to observe the growth performance, antioxidant and innate immune responses, ...and the resistance against Vibrio parahaemolyticus infection. The animals (5.0–5.5 g) were fed on diets supplemented with 0.0 (control), 1.0, 2.5 and 5 g BO/kg diet over 90 days. After the feeding trial, animals were intramuscularly injected by V. parahaemolyticus and observed for 96 h for mortality or any abnormal signs. Growth‐stimulating effects of dietary BO supplementation on final weight, weight gain percentage, specific growth rate and feed intake were observed. No significant differences were found in feed conversion ratio, protein efficiency ratio, protein productive value and animal survival. Feeding the animals on BO‐enriched diets did not significantly affect the chemical proximate composition of animals’ muscles. Increased values of total protein, albumin and globulin were observed in BO‐fed animals; meanwhile, aspartate and alanine aminotransferases as well as creatinine and urea levels significantly decreased in animals fed 2.5–5.0 g BO/kg diet. Activities of superoxide dismutase, catalase, glutathione peroxidase, lysozyme and phenol oxide activity significantly (p < .05) increased in the BO‐fed fish, with highest values in treatments of 2.5–5.0 g/kg diet. The dietary BO supplementation significantly (p < .05) decreased levels of malondialdehyde and nitrous oxide. After the bacterial challenge, 66.7 percent of animals in the control group were dead. The BO‐fed animals were more resistant against bacterial challenge especially at levels of 2.5–5.0 g/kg diet, which showed high relative percentage of survival (80.0–86.7 percent). In conclusion, dietary BO supplementation with levels of 2.5–5.0 g/kg diet proved beneficial effects to Indian shrimp where growth performance, antioxidant systems and innate immunity were stimulated. It also promoted the challenge of Indian shrimp against V. parahaemolyticus infection.
Immunostimulatory feed supplements have an increasingly interest in aquaculture management. Generally, an individual supplement was used in fish diets but it is expected that the use of ...multi‐supplements may show synergistic enhancements in fish performance, health, and immunity. Therefore, the present investigation was carried out to evaluate the use of dietary probiotic Lactobacillus plantarum and whey protein concentrate (WPC) in practical diets for Nile tilapia, Oreochromis niloticus. Hence, probiotic L. plantarum, WPC and their mixture were incorporated into a basal fish diet (300 g/kg crude protein) as follows: T1 = a basal control diet, T2 = a basal diet containing L. plantarum, T3 = a basal diet containing 1.0 g WCP/kg diet and T4, T5 or T6 = basal diets containing probiotic L. plantarum + 1.0, 2.0 or 3.0 g WCP/kg diet, respectively. Fish (15.2 ± 0.6 g) were fed on one of the tested diets up to apparent satiation twice a day for 60 days. After that, fish were intraperitoneally injected with pathogenic bacteria Aeromonas sobria and fish mortality was observed for 10 days postchallenge. Fish growth and feed intake were significantly improved by dietary probiotic L. plantarum (T2) and/or WPC (T3) over the control group (T1), and highest fish performance was observed in T5–T6 fish groups. Similarly, highest values of haematocrit, glucose, total proteins, albumin, and globulin were significantly observed in T5–T6 fish groups. Likewise, fish fed dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) showed antioxidants and immune‐stimulating activities better than the control group. Fish fed the control diet were more susceptible to A. sobria infection showing highest fish mortality (75.0%). Meanwhile, dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) enhanced significantly the fish resistance to A. sobria infection resulting in maximum values of relative percent of fish survival (73.3%–80.0%) in T5–T6 groups. The present investigation recommended the use of probiotic L. plantarum with 2.0 g WPC/kg diet to improve the growth, antioxidant, immunity responses and tolerance of Nile tilapia to A. sobria infection.
The dietary effects of the green microalga Tetraselmis suecica (TS) on the growth, digestive enzymes, immune and antioxidant responses, genes expression, and disease resistance of Nile tilapia ...(Oreochromis niloticus) fingerlings were investigated. This microalga was mixed with the diet' ingredients at doses of 0.0 (the control), 5, 10, 15, and 20 g/kg diet and then fed to fish daily for 84 days. After the feeding trial, fish were experimentally challenged with Aeromonas sobria, infection and fish mortalities were recorded for another 10 days. Dietary TS significantly (p < 0.05) enhanced growth, digestive enzymes activities, and blood proteins, particularly at the level of 15 g/kg diet. Feeding the fish on 15 TS/kg feed exhibited highest mRNA expressions of GH and IGF‐1 genes as well as SOD, CAT, and GPx genes compared to other TS groups. Moreover, highest levels of hepatic antioxidant and immune indices were found in the treatment of 15 g TS/kg feed. Significant downregulation of IL‐1β and IL‐8 genes expression and significant upregulation of IL‐10 gene expression were observed in TS‐fed fish, principally in fish groups fed on 15−20 g TS/kg feed. Conversely, hepatic malondialdehyde levels, blood glucose, and the activities of transaminases (ALT and AST) were significantly (p < 0.05) decreased in fish fed with 15−20 g TS/kg diet. Serum bactericidal activity against A. sobria was significantly higher in TS‐fed fish groups, and its highest levels were found in treatments of 15−20 g/kg diet. Of interest, the survival rates of fish groups fed diets with 10−20 g TS/kg feed were higher after the challenge with A. sobria infection than the control group. Accordingly, we can conclude that supplementing fish diets with a 15 g TS/kg diet enhanced the growth, antioxidant and immune activities, and resistance of Nile tilapia fingerlings to possible A. sobria infection.
The current investigation was carried out to assess the efficacy of dietary garlic (GP) and/or chitosan (CH) powders to protect European sea bass,
Dicentrarchus labrax
, against the adverse effects ...of zearalenone (ZEN) toxicity. Hence, ZEN (0.725 g/kg diet) was incorporated in a fish diet alone or with 30 g GP and/or 10 g CH/kg diet and the treatments were assigned as a control diet (T1), a control diet + ZEN (T2), a control diet + ZEN + GP (T3), a control diet + ZEN + CH (T4), and a control diet + ZEN + GP + CH (T5). Fish (30.7 ± 0.6 g) fed one of the tested diets up to apparent satiation thrice a day for 4 weeks. After the feeding trial, fish were intraperitoneally injected with pathogenic bacteria
Vibrio alginolyticus
for 14 days during which fish mortality was observed. The dietary ZEN inhibited fish growth and feed utilization; meanwhile, co-supplementation of GP and/or CH restored the reduced fish performance as a result of reducing the ZEN toxicity. The ZEN toxicity induced macrocytic hypochromic anemia in European sea bass; however, significant reductions were observed in values of red blood cells (RBCs), hemoglobin (Hb), hematocrit (Ht), and mean corpuscular hemoglobin concentration (MCHC) together with significant elevations in mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) values in comparison with the control fish. Likewise, lymphopenia, monocytosis, leucopenia, eosinophilia, neutrophilia, and thrombocytopenia were the characteristic features of ZEN-toxicated fish with drastic reduction in white blood cells (WBCs) counts. Significant reductions in total protein, albumin, globulin, and lysozyme were also observed in fish serum due to ZEN toxicity. The co-supplementation of GP and/or CH to ZEN-fed fish elevated significantly values of RBCs, Hb, MCHC, and WBCs count with decreasing and increasing of its constituents. Significant rises in total protein, albumin, globulin, and lysozyme were observed with co-supplementation of GP and/or CH to ZEN-toxicated fish to be near these fed on the control diet. The ZEN toxicity also suppressed the fish immunity and subsequently elevated fish susceptibility to
V. alginolyticus
infection causing highest fish mortality as compared with other treatments. The co-supplementation of GP or CH to fish significantly enhanced their immunity causing a high relative percent of survival (RSP) of fish after bacterial infection (18.8 or 43.8%, respectively); meanwhile, fish fed both of GP and CH showed better RSP (68.8%). On the other hand, the co-supplementation of GP or CH reduced the ZEN residue (1.18 and 0.87 μg/kg dry weight) in fish muscles. These results show that CH was more effective than GP in enhancing fish immunity and protection against ZEN toxicity, whereas the co-supplementation of both GP and CH was most effective in protecting fish against ZEN toxicity resulting in lowest ZEN residue (0.53 μg/kg dry weight) in fish muscles.
Nanotechnology is a recent unique technique generally used for nutrition and therapy purposes among others. In this respect, the present study was carried out to evaluate the antimicrobial activity ...of chitosan nanoparticles (CNP) against various microorganisms (fungi and bacteria) isolated from diseased or health Nile tilapia,
Oreochromis niloticus
. The CNP was prepared based on the ionic gelation of chitosan with tripolyphosphate anion and its mean size was 35 nm with a narrow size distribution and zeta potential of 61.2 mV. The lethal dose of pathogenic bacterial isolates for Nile tilapia was successfully standardized. Clinical signs including weakness, slower movement, swimming closer to the surface, fin hemorrhages, and red patches at the gut regions were observed. Enlargement of spleen followed by tissue necrosis along with signs of hemorrhagic septicemia was also seen in infected fish. Fungal and bacterial isolates were exposed to different CNP doses and it is noticed that CNP inhibited all examined fungal and bacterial isolates in a dose-dependent manner. However, high CNP doses (80 μg/ml) gave highest inhibition zones where
Aspergillus flavus
,
Mucor
sp., and
Candida
sp. were more susceptible, whereas
Aspergillus niger
,
A. fumigatus
, and
Fusarium
sp. were more resistant. Similarly, largest inhibition zones of tested bacteria were obtained at high CNP dose (20 μg/ml). And
Aeromonas sobria
,
A. hydrophila
, and
Pseudomonas aeruginosa
were the most susceptible bacterial strain; meanwhile,
Staphylococcus aureus
and
Pseudomonas fluorescens
were the most resistant ones. The minimal inhibitory concentration of CNP against the examined bacteria ranged from 0.156 to 2.5 μg/ml causing their minimal counts. The transmission electron microscope images revealed that CNP showed antagonistic action against
A. hydrophila
causing disruption of cell membranes and the leakage of cytoplasm. In a practical experiment, Nile tilapia fed dietary CNP at levels of 0.0 and 1.0 g/kg diet for 3 weeks and post-challenged with different pathogenic bacteria via intraperitoneal injection. It is noticed that fish fed a CNP-enriched diet showed less mortality with all bacterial strains (6.7–20%), while, fish fed a CNP-free diet showed highest mortality (66.7–100%). The dietary CNP protected Nile tilapia efficiently against
A. hydrophila
,
A. sobria
, and
Streptococcus agalactiae
infections with relative level of protection (RLP) value of 93.3%, while the RLP against
Staphylococcus aureus
was 70.0%.
Pathogens isolated from fish appear to possess considerable antimicrobial resistance and represent a problem for the economy and public health. Natural antimicrobial substitutes to traditional ...antibiotics represent an essential tool in the fight against antibiotic resistance. Nanotechnology has shown considerable potential in different research fields, and the antimicrobial properties of silver nanoparticles are known. Silver has been used for medical purposes since ancient times because of its bactericidal properties, and the highly reactive surfaces of silver nanoparticles (AgNPs) indicate that they might have a function in antimicrobial applications. This work aimed to study the antimicrobial properties of biologically produced AgNPs from Origanum vulgare leaves compared to chemically produced AgNPs. Both types were characterized by UV–vis spectrophotometry, TEM, and dynamic light scattering and tested against three bacterial strains (Streptococcus agalactiae, and Aeromonas hydrophila, both isolated from Nile tilapia and Vibrio alginolyticus, isolated from sea bass) and three fungal strains (Aspergillus flavus, Fusarium moniliforme, and Candida albicans, all isolated from Nile tilapia). Disk diffusion test and evaluation of ultrastructure changes of tested microorganisms treated with AgNPs by transmission electron microscopy were performed. Moreover, the hemolytic properties of AgNPs were studied on chicken and goat red blood cells. The results obtained declare that the green biological production of silver nanoparticles is safer and more effective than the chemical one; moreover, AgNPs have interesting dose-dependent antimicrobial properties, with better results for biologically produced ones; their effectiveness against tested bacterial and fungal strains opens the way to their use to limit fish diseases, increase economy and improve human health.
•Miswak leaf powder (MLP) dietary addition (2.5 up to 10 g kg−1 diet) was examined in O. niloticus.•Enhanced growth performance was investigated in the fish fed diet containing 2.5 g MLP.•Dietary 5 ...and 10 g MLP increased disease resistance, activated antioxidative status and immunity response of O. niloticus.•High levels of MLP significantly increased crude protein content of O. niloticus body.•MLP extract showed strong antimicrobial and antifungal activity against fish pathogens.
The feeding experiment's main purpose was to estimate the influence of fortification of tilapia diets with miswak leaf powder (MLP) on performance, digestive enzyme activity, chemical body composition, antioxidant status, immune response, and resistance against bacterial and fungal infections. O. niloticus fingerlings (15.22 ± 0.06 g) were fed four formulated diets fortified with MLP at 0, 2.5, 5, and 10 g kg−1 diet for 56 days. The fish were injected with Aeromonas hydrophila for 14 days at the end of the feeding trial, and then the mortality percentage was recorded daily in all treated groups. The obtained results showed that dietary administration of MLP at 2.5 g kg−1 recorded significantly higher values in all growth, feed utilization, and feed efficiency parameters. The digestive enzyme activity was significantly (P < 0.01) higher in fish fed a low level of MLP (2.5 or 5 g kg−1) when compared with the control group. Furthermore, the higher concentration of MLP (10 g kg−1) significantly reduced the mortality rate induced by Aeromonas hydrophila infection, increased crude protein percentage in fish body and represented highly in vitro antibacterial and antifungal efficiency. Based on the findings of the challenge tests against A. hydrophilia, higher survival was found in infected fish, explaining that MLP at high level of 10 g kg can be used to resist the outbreak of the A. hydophilia disease in tilapia. In conclusion, our obtained data showed that applied MLP in tilapia diets could promote performance, feed efficiency, antioxidant status, immune activity, and enhanced resistance of O. niloticus against infections.
Recently, nanoparticles have attracted attention as a preventive tool for certain infectious diseases affecting fish in aquaculture. Furthermore, freshwater fishes are frequently vulnerable to summer ...mass morality caused by Aeromonas bacteria. In this regard, we focused on the evaluation of the in vitro and in vivo antimicrobial activity of chitosan (CNPs) and silver (AgNPs) nanoparticles against Aeromonas hydrophila subsp. hydrophila. CNPs and AgNPs were prepared at a mean particle size of 9.03 and 12.8 nm and a charge equalled+36.4 and −19.3 mV for CNPs and AgNPs, respectively. A.
hydrophila subsp. hydrophila, Aeromonas caviae, and Aeromonas punctata were retrieved and identified by traditional and molecular techniques. The sensitivity of the obtained bacteria to eight different antibiotic discs was also tested. The antibiotic sensitivity studies revealed the presence of multidrug-resistant (MDR) Aeromonas species (spp.). The bacterium that showed the highest multidrug resistance against the tested antibiotic discs was Aeromonas hydrophila subsp. hydrophila. Therefore, CNPs and AgNPs were in vitro tested against the isolated bacterium and exhibited inhibition zones of 15 and 25 mm, respectively. TEM images also showed that CNPs and AgNPs had an antagonistic action against the same bacterium causing loss of architecture and bacterial death.
Feed supplements to fish are generally used to overcome any expected diseases and stressors and to sustain eco-friendly fish farming. One of these feed supplements is chitosan, which stimulated ...growth and immune properties for many aquatic organisms. It is expected that the nano-sized materials may have stronger immune activation in fish than the ordinary size. Therefore, the current study was conducted to evaluate the effect of dietary chitosan nanoparticles (CNP) on growth performance, antioxidant activity, and innate immunity of Nile tilapia, Oreochromis niloticus (L.). Fish (19.8 ± 0.59 g) were fed on diets enriched with 0.0, 0.25, 0.5, 1.0, and 2.0 g CNP/kg diet for 45 days. Fish performance was significantly improved with increasing CNP levels over the control diet with optimum level of 1.0 g CNP/kg diet. Antioxidant-stimulated activity was observed due to dietary CNP supplementation over the control diet in a dose-dependent manner. However, malondialdehyde level decreased significantly, whereas activities of catalase, superoxide dismutase, lysozyme, and respiratory burst increased significantly due to CNP supplementation in a dose-dependent manner. The current study evoked that dietary CNP showed strong immune modulatory properties and enhanced significantly the performance and health of Nile tilapia with optimum level of 1.0 g CNP/kg diet.
•Nile tilapia was fed on diets enriched with different CNP levels for 45 days.•Fish performance improved significantly with increasing CNP levels with optimum level of 1.0 g/kg diet.•Antioxidant-stimulated activities were observed with dietary CNP over the control diet especially at high levels.•Dietary CNP enhanced the immune response of Nile tilapia in a dose dependent manner.
The antibacterial activity of aqueous (AE) or ethanolic extracts (EE) of caper (Capparis spinosa) against Streptococcus agalactiae was evaluated in vitro. Both caper extracts showed antagonistic ...activity against S. agalactiae and the inhibition zones in case of ethanolic extracts were larger than those of aqueous ones. Additionally, TEM investigations show that S. agalactiae cells treated with both C. spinosa extracts were damaged and degraded and this damage was greater in case of ethanolic extract. Another study was done to assess the promotion effects of dietary caper (C. spinosa) extracts on growth, antioxidant and immune activity, and inflammation cytokine responses of Nile tilapia (Oreochromis niloticus) and its resistance to S. agalactiae infection. However, fish (40 ± 2 g) were fed on diets containing 1.0 and 2.0 g/kg feed of each caper extract as well as the control group (free of caper) for 6 weeks. Fish were intraperitoneally injected (IP) with Streptococcus agalactiae at the end of the feeding trial, and fish mortality was tracked for additional ten days. Compared with other treatments, fish fed on 2.0 g EE/kg feed had higher counts of white and red blood cells as well as higher hemoglobin levels accompanied with lower AST and ALT activities. Antioxidant (superoxide dismutase and catalase activities) and immune, total protein, globulin, lysozyme, and immunoglobulin M) indices were increased along with significant decline in MDA levels in both caper extracts treated fish groups compared to the control group. Significant promotion in fish growth was affected positively with the increase in both caper extracts; particularly, the larger fish growth was observed in the treatment of 2.0 g EE/kg feed. Expressions of IL-1β and IL-8 were declined; meanwhile levels of IL-10, SOD and CAT genes were upregulated in fish fed on 2.0 g EE/kg feed compared to other groups. After being challenged with S. agalactiae infection, fish survival was considerably (P < 0.05) greater in fish groups that fed on diets with caper extracts; particularly 2.0 g EE/kg feed (75%); while all fish fed on the control one were dead. According to these findings, the antioxidant and immune response of Nile tilapia fingerlings is stimulated by ethanolic extract of caper (2.0 g/kg feed), which also enhanced the growth performance and fish resistance to S. agalactiae infection.
•Nile tilapia were fed on 0.0, 1.0 and 2.0 g/kg feed of aqueous (AE) or ethanolic extracts (EE) of caper for 6 weeks.•Highest antioxidant and immune response was observed in the 2.0 g EE/kg feed group compared with other groups.•Expression of IL-1β and IL-8 genes declined; while levels of IL-10, SOD and CAT genes upregulated in fish fed on 2.0 g EE/kg feed.•Fish fed on 2.0 g EE/kg feed were more resistant to S. agalactiae infection compared with other groups.•Significant promotion in fish growth was observed in EE > AE > the control fish groups; particularly at 2.0 g EE/kg feed.
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