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1.
This study compared the efficacy of four products that are commonly used in hatchery for nutritional enhancement of rotifer Brachionus plicatilis as the starter food for yellowtail kingfish Seriola lalandi larvae. This experiment consisted of one fresh algae and three enrichment products: (1) Fresh algae were a mixture of Nannochloropsis and Isochrysis at 2:1 on a cell concentration basis; (2) S.presso, (Selco S.presso ®, INVE Aquaculture); (3) Algamac 3050® (Aquafauna, USA); (4) Nutrokol ® (Nutra‐Kol, Australia). Survival rates of the fish fed rotifers enriched with fresh microalgae (40.69%) and S.presso (31.21%) were higher than those fed Algamac 3050 (10.31%). On 3 day post hatch (DPH), fish feeding incidence in the fresh algae treatment was significantly higher than that in other treatments. On 6 DPH, fish showed the lowest feeding incidence in the Algamac 3050 treatment. The methods of enrichment did not affect total lipid levels in either rotifer or fish larvae, but Algamac 3050 enrichment achieved the highest DHA/EPA ratio and lowest EPA/ARA ratio in both rotifers and fish larvae. This study indicates that fresh algae can be replaced by S.presso, but Algamac 3050 is not as good as other formula for rotifer enrichment in rearing yellowtail kingfish larvae in this system.  相似文献   

2.
In aquaculture, exposure to stressful conditions and problems related to diseases often occur resulting in serious economic loss. The use of probiotics that control pathogens through different mechanisms, aiding digestion by exoenzyme supply and establishment of beneficial microflora in the digestive tract has got increased attention recently. Two different bacterial species Micrococcus MCCB 104 and Bacillus MCCB 101 were tested as probiotics for two cichlid species Etroplus suratensis and Oreochromis mossambicus. The strains were administered separately and together, at a rate of 103 CFU animal?1 day?1 for 28 days. The effects on digestive enzyme activity and growth were compared with those fed on control diet. FCR of E. suratensis was high in case of Bacillus alone as well as the mixed culture (Micrococcus and Bacillus together) than that of control. However, the SGR of E. suratensis was slightly lower than that of control during 14 days trial. SGR of both the treatments (Bacillus alone and mixed culture) was higher than that of the control on 28th day, and this might be due to the reason that specific duration is needed for the assimilation and conversion of nutrients into proteins. The intestinal digestive hydrolases of E. suratensis were profoundly enhanced mainly by Bacillus and mixed cultures. The hepatopancreatic versions of major digestive enzymes in E. suratensis were influenced variously by different probiotic treatments. The alpha‐amylase activity of hepatopancreas has been elevated significantly by mixed culture during 14 days experiments while on 28 days trials both Bacillus and mixed culture showed an enhancing effect. During 14 days feeding trials, the intestinal lipase activity has been prominently enhanced by all probiotic treatments. It is found that, in O. mossambicus, both 14 days and 28 days feeding experiments, the pepsin as well as intestinal digestive enzymes such as amylase, total alkaline protease, lipase and their hepatopancreatic counter parts showed a significant elevation in their specific activity. Intestinal alpha‐amylase and total alkaline proteases of O. mossambicus showed an increase in specific activities on both 14 days and 28 days feeding experiments with the Bacillus and Micrococcus combination. The hepatopancreatic enzymes were highly influenced by the Bacillus species in O. mossambicus. The results of this study suggest that live probiotic microorganisms such as Micrococcus MCCB 104 and Bacillus MCCB 101 may be incorporated while formulating the cost‐effective, nutritionally balanced diet of E. suratensis and O. mossambicus for better growth performance and nutrient utilization.  相似文献   

3.
During a series of experiments, bacteriological elements in scallop larval rearing were investigated: larvae susceptibility to pathogens as a function of their age, and the use of probiotic bacteria during larviculture. Younger larvae (d5 PF) were highly more susceptible to pathogenic‐challenge than their older siblings, which were challenged at an older age (d15 PF). A challenge with 104 CFU mL?1 of V. pectenicida killed 100% of d5 PF larvae 7 days following challenge, yet killed only 9% of d15 PF larvae 9 days following challenge. Use of the probiotics Phaeobacter gallaeciensis, Alteromonas macleodii 0444 and Neptunomonas sp. 0536, provided for larger larvae, a high yield of competent larvae and, perhaps more importantly, protection against pathogen‐challenge similar to levels achieved from antibiotic use. When challenged with V. pectenicida, d29 survivals were 20.3%, 85.1% and 75.0% respectively for control (no probiotic), antibiotic treated, and ‘probiotic mix’ administered larvae. Use of potential probiotic Pseudoalteromonas sp. D41 appeared to hinder scallop larvae. Future use of probiotics in scallop larval rearing would benefit from combined use of P. gallaeciensis, A. macleodii 0444 and Neptunomonas sp. 0536.  相似文献   

4.
The objective of this study was to investigate the effects of mixed Bacillus on growth, water quality and disease resistance against Vibrio harveyi in whiteleg shrimp (Litopenaeus vannamei). Postlarval shrimp (PL30) were fed with (a) a basal diet (the control), (b) a diet containing mixed freeze‐dried Bacillus probiotics (FB) and (c) addition of mixed microencapsulated Bacillus probiotics (MB) in culture water. Addition of FB and MB probiotics improved (p < .05) growth, feed efficiency, survival and culture water quality (ammonia and nitrite) compared to the control group although there was no difference (p > .05) between the two treated groups. Bacillus numbers in gastrointestinal tracts and culture water of FB‐ and MB‐administrated shrimp were higher (p < .05) than in the control. After a 30‐day culture, shrimp were infected with V. harveyi and monitored for 10 days. A significant reduction (p < .05) in cumulative mortality was observed in FB‐ and MB‐supplemented shrimp (43.24% and 45.05%, respectively), compared to the control (63.06%). This finding demonstrated that administration of microencapsulated probiotics was as effective as freeze‐dried probiotics for improving growth, feed efficiency, survival, Bacillus in gastrointestinal tracts, water quality (ammonia and nitrite) and conferring disease resistance to V. harveyi.  相似文献   

5.
The pattern of conservation and loss of fatty acids from the yolk sac during the endogenous feeding period and subsequent starvation was studied in pompano and snook larvae. Fundamental information on the early fatty acid dynamic and mobilization of pompano and snook larvae was collected. In both species, fatty acids were utilized as an energy source after hatching. Mono‐unsaturated fatty acids were catabolized, while saturated and poly‐unsaturated fatty acids were conserved. High levels of arachidonic acid (ARA) in pompano and snook eggs, as well as selective retention in the unfed larvae suggest a high dietary requirement for this fatty acid during the early stages of larval development. The effect of an ARA supplementation was therefore investigated in snook larvae at the rotifer feeding stage. The fatty acid profile of the larvae was successfully influenced to match that of wild eggs; however, no significant improvement in growth or survival was observed. Future research should be carried out over a longer period of time and include factors related to stress resistance.  相似文献   

6.
Taurine is an essential or conditionally essential nutrient for many species of marine fish, especially during early development. There is growing evidence that marine fish larvae benefit from taurine‐enriched rotifers; however, it is unknown if larvae benefit from taurine‐enriched Artemia. We investigated the effects of taurine‐enriched rotifers (Brachionus plicatilis) and Artemia franciscana on the growth and whole‐body taurine concentrations of California yellowtail (Seriola lalandi; CYT) larvae. The approach used in this study was to encapsulate taurine within microparticles (liposomes), which were then fed to rotifers and Artemia. We found that feeding taurine liposomes to rotifers and Artemia resulted in taurine concentrations in these prey species that were similar to or above those previously reported in copepods. At the end of the rotifer phase, CYT larvae fed taurine‐enriched rotifers showed increased growth (final dry weights; DW) and had higher whole body taurine concentrations when compared to larvae fed unenriched rotifers. At the end of the Artemia phase, CYT whole body taurine concentrations varied among dietary treatments. Larval lengths and DWs were not significantly different among treatments at the end of the Artemia phase, suggesting that the taurine concentrations of unenriched Artemia were sufficient to support the growth of CYT larvae.  相似文献   

7.
Litopenaeus vannamei is economically important shrimp species in worldwide aquaculture. This study was conducted to assess the effect of different levels of probiotic Pediococcus pentosaceus (PP) on growth performance, feed utilization, digestive enzyme activity, intestinal microflora count and body composition of L. vannamei. Four diets containing different concentrations [0 (PP0), 106 (PPI), 107 (PPII) and 108 (PPIII) CFU/g] of PP were formulated. After 8 weeks feeding trial, the experimental shrimps were challenged with Vibrio anguillarum and noted the surveillance. At the end of the feeding trial, the obtained results revealed a significant increase (p < .05) in final body weight, final length, weight gain (WG), survival rate, protease and amylase activities, lactobacillus sp. and Bacillus sp. intestinal count, total haemocyte counts (THC) and lysozyme activity in PPIII group when compared with the other groups. Similarly, WG, amylase activity, Bacillus sp. count, THC and lysozyme activity were significantly enhanced in case of PPII compared to the control group (p < .05). Interestingly, FCR and Vibrio sp. counts were significantly decreased in case of PPIII group when compared to the other groups (p < .05). Also, significant level of surveillance was noted in the challenging test with V. anguillarum. These results suggested that the P. pentosaceus improved the growth performance, digestive enzyme activity, immunity and tolerance against V. anguillarum of L. vannamei.  相似文献   

8.
The supply of microalgae to hatcheries is a limiting factor for the mass larval production of sea cucumber (Apostichopus japonicus) in Fujian Province, China. In this study, Nannochloropsis sp. isolated from the East China Sea was tested as food for A. japonicus larvae. The first trial compared the effect of mono‐, bi‐ and trialgal diets comprising three microalgae (Chaetoceros muelleri, Dunaliella tertiolecta and Nannochloropsis sp.) on A. japonicus larval growth, survival, settlement and juvenile growth. The results showed that there were no significant differences in survival and settlement between larvae fed with Nannochloropsis sp. and other diets. All diet treatments yielded similar juvenile sea cucumber output. In the second trial, A. japonicus larvae were fed equally four times daily at three different rations (5000, 20 000 and 40 000 cells mL?1 day?1). Larvae fed 20 000 cells mL?1 day?1 were significantly larger than larvae in other groups and experienced the highest survival rate. In the third trial, A. japonicus larvae were fed 20 000 cells mL?1 day?1 in three different frequency (2, 3 and 4 meals day?1). The greatest body length was observed in larvae that received 3 meals day?1. Survival and settlement of larvae fed 2 meals day?1 were significantly lower than other two groups. These results suggest that Nannochloropsis sp. can be used as a diet for the large‐scale production of A. japonicus seed, and larvae fed three times daily at a ration of 20 000 cell mL?1 day?1 are recommended for hatchery production of A. japonicus.  相似文献   

9.
Digestive enzyme profile is a good indicator of the nutritional and health status of the fish. The present investigation aims to evaluate the effect of exogenous bath treatment of hormones, cortisol and triiodothyronine, on the digestive enzyme activities and growth of carp Catla catla (Ham.) during ontogenic development. Catla larvae (4 days old) were given bath treatment with cortisol (hydrocortisone, 0.2 mg L?1), 3,5,3′‐triiodothyronine (T3, 2.5 mg L?1) and a combination of cortisol and T3 for 30 min. Digestive enzyme profile was recorded on every third day and was continued for 30 days. Larvae were fed with live food for initial 14 days and then weaned to mix feeding of live food and prepared diet. Significantly (P < 0.05) higher amylase, total protease, trypsin, chymotrypsin, lipase, chitinase and chitinobiase activities were found in the hormone‐treated groups compared to the control one during ontogenic development. Among the treated groups, amylase activity was highest in cortisol‐treated larvae. Total protease, trypsin, chymotrypsin, lipase, chitinase and chitinobiase activities were significantly (P < 0.05) higher in larvae exposed at combined treatment of cortisol and T3 compared to the other two groups in most sampling days. Average length, weight and specific growth rate of treated larvae were higher compared to the control one. The combined bath treatment of cortisol and triiodothyronine influenced the digestive enzyme activities of catla larvae and thereby enhanced the growth at early developmental stage. This helps the larvae to overcome the problems associated with early developmental stage.  相似文献   

10.
The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.  相似文献   

11.
The effect of a commercially available compound probiotics product containing Bacillus subtilis YB‐1 (50%) and Bacillus cereus YB‐2 (50%) fed to sea cucumbers, Apostichopus japonicus (Selenka) on challenge infections and non‐specific immune responses was assessed. Sea cucumbers (were randomly allocated into nine aquariums at a density of 30 sea cucumbers per tank and triplicate groups) were fed diets containing 0 (control), 107 and 1010 cfu (g diet)?1 of the probiotics mixture for 32 days. The growth factors and immunological parameters were measured. In addition, the effects on resistance against Vibrio alginolyticus infection were also evaluated. The results indicate that all the immunological parameters (phagocytic activity, superoxide anion production, lysozyme activity, catalase activity and phenoloxidase activity) measured and the growth rate of sea cucumbers fed 1010 cfu of the probiotics mixture were significantly (P < 0.05) improved than control groups at 16 and 32 days. After challenging, the cumulative mortality for the control was 100%, whereas the cumulative mortality for sea cucumbers fed 1010 cfu of the probiotics mixture was 47% (P < 0.05). Although the total autochthonous intestinal heterotrophic bacterial counts were not affected by dietary treatment (P > 0.05), Bacillus sp. levels were significantly elevated in sea cucumbers fed the probiotics mixture (P < 0.05). These results confirmed that administration of the probiotics mixture in the diet stimulated non‐specific immune responses and enhanced the growth performance of sea cucumbers, and was effective in controlling infections caused by V. alginolyticus.  相似文献   

12.
Controlled incorporation of selected microalgae and bacteria in aquaculture systems can be beneficial because they can act as microbiological control. That is why the characteristics of biofilm generated naturally in Seriola lalandi culture cages were analysed, their potential benefit to the growth of larvae was studied, and their controlled use for improving the larval viability and as a vector to improve incorporation of previously studied probiotic bacteria was tested. According to biodiversity results, these biofilms are composed of a diatom–bacteria mix showing a decrease in biodiversity in laboratory culture conditions being dominated by Navicula phyllepta and bacteria of the family Rhodobacteraceae. This can be produced on mesh substrates incorporated in bioreactors with rapid growth rate and adhesiveness. Preliminary results from the addition of substrates with this specific biofilm in larvae culture systems showed that it is consumed by the larvae without negative effects, while positive effects on the viability of larvae in combination with probiotics were observed. Considering preliminary results, the addition of these specific substrates with diatom–bacteria biofilms could be a good improvement for aquaculture systems and together with the use of probiotics can contribute to maintaining a stable and controlled system improving the viability of the larval fish culture in its early stages.  相似文献   

13.
Three in vivo experiments were conducted to measure the effectiveness of commercial Bacillus probiotics on survival and development of Litopenaeus vannamei larvae from nauplii 3–4 (N3–4) to zoea 3 (Z3) stages. Experiment I: Nine commercial Bacillus probiotics were individually added to larvae twice at N6 and Z1 at levels of 2, 20, and 100 mg L?1. Only six of nine products at 20 mg L?1 exhibited higher or significantly higher larval survival (P < 0.05) than the control. Experiment II: Two superior products from the first experiment were administered to larvae with six dose frequencies at 20 mg L?1. For both products, three doses, once at each of N3–4, N6 and Z1 stages, yielded the best larval survival and development rates (P < 0.05), and these were confirmed by enhanced activities of tryptase and amylase. Experiment III: The isolates of these two products, identified as Bacillus subtilis and Bacillus licheniformis, were delivered to larvae singly at concentrations of 1.0 × 108 and 1.0 × 109 CFU L?1, or at the same concentrations by mixing the two equally. At 1.0 × 109 CFU L?1, B. subtilis exerted more beneficial effects on larvae than B. licheniformis or the mixture. Therefore, the optimal dosage and dose frequency of commercial Bacillus products should be evaluated prior to large‐scale application in shrimp hatcheries to avoid futility or even adverse effects, as spore counts and non‐bacterial ingredients are key factors influencing the efficacy of Bacillus probiotics.  相似文献   

14.
Live prey used in aquaculture to feed marine larval fish – rotifer and Artemia nauplii – lack the necessary levels of n‐3 polyunsaturated fatty acids (n‐3 PUFA) which are considered essential for the development of fish larvae. Due to the high voracity, visual feeding in conditions of relatively high luminosity, and cannibalism observed in meagre larvae, a study of its nutritional requirements is needed. In this study, the effect of different enrichment products with different docosahexaenoic acid (DHA) concentrations used to enrich rotifers and Artemia metanauplii have been tested on growth, survival, and lipid composition of the larvae of meagre. The larvae fed live prey enriched with Algamac 3050 (AG) showed a significantly higher growth than the rest of the groups at the end of the larval rearing, while the larvae fed preys enriched with Multigain (MG) had a higher survival rate. DHA levels in larvae fed prey enriched with MG were significantly higher than in those fed AG‐enriched prey. High levels of DHA in Artemia metanauplii must be used to achieve optimal growth and survival of meagre larvae.  相似文献   

15.
Y. Wang  M. Li  K. Filer  Y. Xue  Q. Ai  K. Mai 《Aquaculture Nutrition》2017,23(5):1113-1120
This trial was conducted to evaluate the effects of replacing dietary fish oil with Schizochytrium meal for Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Six test microdiets were formulated using Schizochytrium meal to replace 0 g/kg, 250 g/kg, 500 g/kg, 750 g/kg, 1000 g/kg or 1500 g/kg fish oil DHA. No significant differences were observed in survival, growth, final body length and activities of digestive enzyme among shrimp fed different diets (p > .05). No significant differences were observed in C20:5n‐3 (EPA) in muscle samples (p > .05). C18:3n‐3 and C20:4n‐6 in muscle increased as Schizochytrium meal replacement level increased (p < .05). No significant differences were observed in C22:6n‐3 (DHA) and n‐3 fatty acids among shrimp fed diets that algae meal replaced 0 g/kg ‐ 1000 g/kg of fish oil. Shrimp fed diet R150 had higher DHA content than other groups and had higher n‐3 fatty acids than that of shrimp fed diets R50, R75 and R100 (p < .05). C18:2n‐6, PUFA and n‐6 fatty acids in muscle increased, while n‐3/n‐6 ratio decreased with increasing algae meal replacement level from 0 g/kg to 1000 g/kg (p < .05). In conclusion, Schizochytrium meal could replace 1500 g/kg fish oil DHA in the microdiets without negatively affecting shrimp larvae survival, growth and activities of digestive enzyme.  相似文献   

16.
The aim of this study was to compare the nutritional composition and effects of short periods with cultivated copepod nauplii versus rotifers in first‐feeding. Atlantic cod (Gadus morhua) and ballan wrasse (Labrus bergylta) larvae were given four different dietary regimes in the earliest start‐feeding period. One group was fed the copepod Acartia tonsa nauplii (Cop), a second fed enriched rotifers (RotMG), a third fed unenriched rotifers (RotChl) and a fourth copepods for the seven first days of feeding and enriched rotifers the rest of the period (Cop7). Cod larvae were fed Artemia sp. between 20 and 40 dph (days posthatching), and ballan wrasse between 36 and 40 dph, with weaning to a formulated diet thereafter. In addition to assessing growth and survival, response to handling stress was measured. This study showed that even short periods of feeding with cultivated copepod nauplii (7 days) had positive long‐term effects on the growth and viability of the fish larvae. At the end of both studies (60 days posthatching), fish larvae fed copepods showed higher survival, better growth and viability than larvae fed rotifers. This underlines the importance of early larval nutrition.  相似文献   

17.
Fish are always susceptible to a wide variety of deadly pathogens which cause a huge loss in aquaculture industries. In this investigation, we have demonstrated the in vivo probiotic efficiency of Bacillus sp. MVF1 (GenBank Acc. No. KP256503) in Labeo rohita challenged with pathogenic strain of Aeromonas hydrophila (MTCC 1739). To check the probiotic potential of the selected bacterial strain, fish were divided into four groups: control, D1, D2 and D3. A total of 100 days (70 days probiotic feeding + 71th day sampling and 28 days challenged test + 29th day sampling) of feeding trial was conducted. To establish the probiotic potential of Bacillus sp. MVF1, certain haematological parameters (haemoglobin, total erythrocyte and leucocyte count), serum biochemical parameters (total protein, albumin and globulin), immune parameters (serum lysozyme and total IgM levels) and hepatic stress profile (malondialdehyde production, superoxide dismutase and catalase activity) have been measured. Our results demonstrated that red blood cell number, white blood cell number and haemoglobin content were much higher in D2 group fish compared to other groups and control fish. Similarly, total protein contents, albumin concentration, globulin concentration, lysozyme activity and IgM production were also recorded to be highest in D2 group fish. This finding clearly indicated the probiotic potential of Bacillus sp. MVF1 in L. rohita. Furthermore, our results also demonstrated that 1 × 107 CFU g?1 feed (D2) provides better immunity compared to 1 × 105 (D1) and 1 × 109 (D3). Due to beneficial effects, the bacterium Bacillus sp. MVF1 might be useful in aquaculture industries to reduce the disease susceptibility.  相似文献   

18.
It is assumed that Florida pompano have dietary EPA (20:5n‐3) and DHA (22:6n‐3) requirements. However, it is unclear whether both are equally important in meeting demand for n‐3 long‐chain polyunsaturated fatty acids (LC‐PUFAs) or whether the requirement(s) can be influenced by other fatty acids. Accordingly, we assessed production performance and tissue composition of juvenile Florida pompano (41.0 ± 0.5 g) fed diets containing fish oil; beef tallow; or beef tallow partially or fully supplemented with EPA, DHA or both. After 8 weeks, no signs of fatty acid deficiency were observed. Although fish performance did not vary significantly among the dietary treatments, fish fed the DHA‐supplemented feeds exhibited numerically superior growth than those fed the other diets. Fillets of fish fed the beef tallow‐based diets contained reduced levels of n‐3 fatty acids and LC‐PUFAs and elevated levels of MUFAs and n‐6 fatty acids, although dietary supplementation with EPA and/or DHA attenuated these effects somewhat. Our results suggest that beef tallow is suitable as a primary lipid source in Florida pompano feeds and n‐3 LC‐PUFA requirements may be met by as little as 4 g/kg EPA and 4 g/kg DHA. However, there may be value in supplementing tallow‐based diets with DHA to enhance tissue levels and possibly growth.  相似文献   

19.
In the present study, a potential Lactobacilli probiotics were isolated from Japanese eels (Anguilla japonica) and characterized and evaluated for their possible use in eel farming. Sixteen Lactobacilli were isolated from intestines of Japanese eels, using selective media. The lactobacilli strains (represented as PL1 to PL16) were screened by their ability to produce digestive enzyme. Among these, three strains (PL11, PL13 and PL16) producing four digestive enzymes (amylase, cellulase, protease and phytase) simultaneously were characterized further using API ZYM kit. From these, PL11 (Lactobacillu (L.) pentosus) was identified as potential probiotics candidate producing 15 enzymes among 20 tested. Further examination of biological activities of PL11 revealed tolerance against pH, artificial bile juice and antibacterial activity against several fish pathogenic bacteria. The in vitro competitive exclusion assay also revealed 88.4% reduction in adhesion of fish pathogen (Edwardsiella tarda) by PL11 to host intestinal mucus. In vitro incubation of Japanese eel foregut with Baclight‐labelled PL11 showed colonization of the enterocyte surface by confocal and scanning electron microscopy. In summary, PL11 isolated from eels could serve as a potential probiotics with acid and bile tolerance, production of digestive enzymes, antibacterial activity and inhibition of fish pathogen adhesion to intestinal mucus.  相似文献   

20.
A 20‐week feeding trial was conducted to measure growth, nutrient utilization and faecal/gut bacterial counts in triplicate groups of red hybrid tilapia, Oreochromis sp., when fed diets supplemented with 0.5% organic acids blend (OAB), 1.0% OAB, 0.5% oxytetracycline (OTC) or a control diet (no additives). At the end of the feeding trial, tilapia were challenged with Streptococcus agalactiae for 22 days. Fish fed the OTC diet had significantly higher (P < 0.05) growth than the control treatment, while growth between fish fed the OTC or OAB diets was not significantly different (P > 0.05). Phosphorus, dry matter and ash digestibility were significantly higher in the 1.0% OAB diet than the control diet. Fish fed the OAB diets had significantly lower colony‐forming units of adherent gut bacteria compared to the control or OTC treatments while those fed the 1.0% OAB diet had the lowest total faecal bacterial counts. Tilapia fed the 0.5% OTC or OAB diet had significantly higher resistance to S. agalactiae than those fed the control diet. This study indicates that dietary organic acids can potentially replace OTC as a growth promoter and antimicrobial in tilapia feeds.  相似文献   

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