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1.
This work aimed at validating the use of two prospective probionts (Arthrobacter sp. and Enterococcus sp.) at early stages of cod (Gadus morhua L.) rearing. Ova at late post‐fertilized stage and larvae during their first 4 weeks of life were bathed with both probionts, isolated previously from the cod‐rearing environment. This treatment was compared with groups fed rotifers supplemented with a commercial probiotic (Remus®) and those untreated. Microbiological analyses (total viable counts, presumptive Vibrio and lactic acid bacteria) were performed in rearing systems and larval survival, growth and development were assessed. Larval development was evaluated by proteolytic activity of larval lysates and immunological analysis of important proteins: apolipoprotein A‐I, haemoglobin, C‐reactive protein, C3 and cod serum proteins. Bacterial bathing led to a significantly higher larval weight, length and culturable microbial load in larval gastrointestinal (GI) tract when compared with the control and Remus groups. Development occurred earlier in bathed larvae. However, their survival was negatively affected compared with the control group, but was significantly higher than for the Remus group. The non‐pathogenicity of both probionts was demonstrated by intraperitoneal injection of 13 g cod juveniles. The results suggest that Arthrobacter and Enterococcus probionts affected the larval GI microbiota and contributed to growth, development and digestion, either directly or indirectly.  相似文献   

2.
The impacts of varying algal growth rates on the bacterial load in the cultures were studied for six marine microalgae: Skeletonema costatum ,Chaetoceros mülleri (Bacillariophyceae), Nannochloropsis oculata (Eustigmatophyceae), Isochrysis galbana, Pavlova lutheri (Haptophyceae), and Tetraselmis sp. (Prasinophyceae). Samples were taken in batch cultures during early exponential phase and in stationary phase when the growth rate was below 5% of maximum growth rate (µmax). Except for C. mülleri and N. oculata, the microalgae were thereafter grown semi-continuously at dilution rates of 20% and 60% of µmax and samples taken during a period of 10 days.Higher bacterial levels were associated with slow-growing microalgae on a per volume basis. Per algal cell, variations in the bacterial load were more related to species. Relatively high bacterial densities (5.7–16.4 CFU algal cell–1) with large proportions of opportunistic and haemolytic species were associated with the Bacillariophyceae. For the other species, the bacterial density was 0.2–4.3 CFU algal cell–1. Bacterial levels were in general lower and not affected to the same extent by algal growth conditions in Tetraselmis sp. and P. lutheri. No or very low levels of presumptive Vibrio spp. were observed, except in semi-continuous cultures of P. lutheri. Cultures of Tetraselmis sp. had low levels of opportunistic bacteria at all growth conditions.  相似文献   

3.
To assess the effect of addition of probiotics and carbon source on the microbial community structure within the shrimp culture, an enclosure system simulating a high density, intensive aquaculture of Litopenaeus vannamei was set up in Dianbai, Maoming, Guangdong province, China. The phylogenetic profiles of microbial communities in the enclosure system after addition of Bacillus and molasses were studied in the middle and final culture season (on the 45th, 75th and 95th day) using polymerase chain reaction‐denaturing gradient gel electrophoresis. A total of four groups, each containing a triplicate were set up: Group A (control), Group B (64% of daily feed was provided as molasses with Bacillus sp.), Group C (50% of daily feed amount provided as molasses with Bacillus sp.) and Group D (64% of daily feed amount as molasses alone). The results showed that α‐Proteobacteria, δ‐Proteobacteria, Bacteroidetes and Actinobacteria were the dominant bacteria. Moreover, the relative proportion of α‐Proteobacteria increased and that of Bacteroidetes decreased gradually with time. Pathogenic Flexibacter was the dominant genus in Group A on the 45th day, while the functional strains (Sphingomonas sp., Erythrobacter sp., Roseobacter sp., and Rhodobacter sp.) were detected multiple times in Groups B and C. Bacillus sp. was the cultivable, dominant bacterium in Groups B and C on the 95th day. Therefore, the combined use of Bacillus and molasses helped increase diversity of the microbial community, effectively inhibit pathogens, and promote the formation and development of a beneficial microbial community structure in the high density, intensive aquaculture of L. vannamei.  相似文献   

4.
In this study, we evaluate the use of polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) for monitoring the effect of different aquaculture practices on sediment prokaryote (Archaea and Bacteria) communities. The effect of initial fish (gilthead seabream Sparus aurata) stocking density on the structural diversity of prokaryote communities of earth ponds bottom sediments was evaluated using PCR‐DGGE after a 5 month grow‐out period. An identical approach was used to monitor the effect of supplying different fish feeds [commercial feed (CD) versus an ecofeed (ECO)]. One additional variable was the use of copper sulphate (CuSO4) as an algicide in some of the experimental rearing tanks. The statistical analyses of prokaryote community profiles showed that the presence of fish in earth ponds significantly influenced the structure of sediment prokaryote communities, when compared with earth ponds without fish, independently of the stocking density. Our results also indicated that the structure of the prokaryote communities of earth ponds supplied with the ECO feed shared a strong similarity with that fed CD. Curiously, the use of CuSO4 in ponds receiving the ECO feed promoted significant differences on the structural composition of the bacterial community, but not on the archaeal community. DGGE molecular fingerprints are suitable for fast evaluation of new management practices in food‐fish production on earth ponds by monitoring shifts on microbial communities in bottom sediments.  相似文献   

5.
Abstract. A trial was conducted in 30 earthen ponds of approximately 100 m2 to evaluate the effects of nine supplemental feeds containing different protein: energy ratios on the growth and survival of Oreochromis niloticus (L.) in brackish water ponds. The formulated feeds had protein levels of 20%, 25% and 30% each at three energy levels of 3000 kcal, 3500 kcal and 4000 kcal. There was a control (diet 0) with no feeding and mean weight gain, growth rate, feed conversion rate and survival rate were determined. Fingerlings were acclimated from 0 to 29 ppt salinity before the trial and 20% of fish in each treatment were sampled every 30 days to monitor growth changes and adjust the feed. Mean weight gain was significantly different as follows: 30%:4000 kcal (102·21 g); 30% :3000 kcal (93·24g); 25%:3000 kcal (89·79g); 30%:3500 kcal (83·42g); 25%:4000 kcal (78·80g); 25%:3500 kcal (78·13g); 20%:3000 kcal (76·50g); 20%:4000 kcal (71·05g); 20%:3500 kcal (69·68 g) and control (59·11 g). Growth rates were significantly different (P < 0·05) and increased with increasing energy level at the 30% protein feeds but decreased at high energy levels in the 20% and 25% protein feeds. Feed conversion was significantly different due to interaction between protein and energy levels in the feeds, and was better at the 30%:3500 kcal feed, with a feed conversion of 1·55. Survival rates were not significantly different (P > 0·05).  相似文献   

6.
The copepod Pseudodiaptomus euryhalinus was fed 320 cells μL− 1 of monoalgal cultures of Chaetoceros muelleri, Nannochloropsis oculata, Isochrysis galbana, Tetraselmis suecica, or a commercial frozen concentrate of Tetraselmis sp., and the diet which gave the best production was compared in a second experiment to three mixed diets: C. muelleri:I. galbana supplied in 1:1 and 2:1 cell ratios and C. muelleri:I. galbana:frozen Tetraselmis sp. in 2:2:1 ratio. These gave better results than the cultures of N. oculata, I. galbana, T. suecica and the frozen Tetraselmis concentrate, but the production was similar to that obtained with C. muelleri supplied as a monoalgal diet, showing that the addition of C. muelleri may improve the performance of other monoalgal diets, whereas the addition of other microalgae is unlikely to improve the results obtained when C. muelleri is supplied as a monoalgal diet.  相似文献   

7.
The aim of the study was to investigate the apparent digestibility coefficient (ADC) of defatted biomass derived from microalgae Nannochloropsis sp. and Desmodesmus sp. when fed to Atlantic salmon postsmolts in seawater. Two experiments, one employing cold‐pelleted and the other employing extruded pellets, were carried out to determine the ADC of dry matter (DM), protein, ash and energy. The test feeds consisted of a fishmeal‐based reference feed and the algal biomass, at a ratio of 70:30, and yttrium oxide as the inert marker. The ADC of DM and protein in fish fed microalgae‐incorporated cold‐pelleted feeds were significantly higher for Nannochloropsis sp. compared with Desmodesmus sp. The Nannochloropsis sp. inclusion in extruded feeds also led to higher ADCs of DM and energy compared with Desmodesmus sp. The extrusion processing significantly increased the ADC of ash in both defatted microalgae biomass, as well as ADCs of DM in Nannochloropsis and protein in Desmodesmus sp. In conclusion, the microalga Nannochloropsis sp. was more digestible than Desmodesmus sp., and extrusion processing can be used as a means to improve digestibility of certain nutrients.  相似文献   

8.
This study investigated the influence of fish feed deposition on the microbial community of sediments in a coastal lake. Microcosms were designed to simulate the addition of fish feeds to the sediment, and physicochemical factors as well as composition of microbial assemblages were analysed. Although total organic carbon and total organic nitrogen did not significantly increase, redox potential and total sulphides showed a transition of sediment environments into anaerobic condition due to the addition of fish feeds. The bacterial community composition shifted with fish feed deposition as revealed by the band profiles of denaturing gradient gel electrophoresis, Sørensen's similarity indices and cell numbers of sulphate‐reducing bacteria. Occurrence of anaerobic bacteria (sulphate and nitrate reducers) and disappearance of strictly aerobic bacteria were observed with fish feed inputs. The results clarify the succession of the microbial flora and suggest negative impact of uneaten fish feeds on the microbial community in sediment and resultant environmental deterioration of fish‐farming areas.  相似文献   

9.
Pond water quality and associated microbial biomass were studied in relation to the type of feed applied during the culture of the marine shrimp Penaeus vannamei . The feeds tested included conventional feedlot manure as well as two feeds based on bagasse, a sugarcane waste product. Physical and chemical parameters were studied during a 100 day trial in 200 m2 earthen ponds. Both bagasse-based feeds supported a significantly larger microbial community as measured by specific biomass numbers ( P < 0.01), ATP content ( P < 0.001) and amount of the particulate organic matter present on pond bottoms ( P < 0.025). For both bagasse-based treatments, the estimated bacterial cell number in the flocculent layer was 3.11 ± 1012/m2, compared to the much lower cell number of 7.53 ± 1010/m2 for control ponds. Harvest data suggest that bagasse forms a potential base for feeds when applied to extensive shrimp cultures.  相似文献   

10.
Strains of lactic acid bacteria (LAB) were isolated from several different sources and evaluated in vitro for potential probiotic effects in abalones. Two isolates (Lactobacillus sp. strain a3 and Enterococcus sp. strain s6) were highly resistant to bile salt and/or gastric juice and inhibited the growth of three abalone pathogens (Listonella anguillarum, Vibrio harveyi, and V. carchariae). Each of the LAB isolates was used to supplement diet of the abalone Haliotis gigantea for a period of 3 weeks. One group of animals received Lactobacillus sp. strain a3 added to commercial dry feed, one group received Enterococcus sp. strain s6 added to the feed, and a control group received only standard commercial feed. Culturable LAB counts of gut homogenates indicate the a3 colonized in the gut of abalones. Digestive enzyme activities and the concentrations of a number of volatile short-chain fatty acids (VSCFA) were elevated in the gut of abalones receiving feed supplemented with the two LAB strains. These results indicate that dietary supplementation can enable LAB colonization or persistence in the gut of abalone species and can potentially enhance probiotic effects.  相似文献   

11.
Eight hundred and eighty‐five strains of bacterial isolates from various samples associated with the natural habitat of Macrobrachium rosenbergii were screened for their probiotic potential. Two putative probionts namely Bacillus NL110 and Vibrio NE17 isolated from the larvae and egg samples, respectively, were selected for experimental studies and were introduced to the juveniles of M. rosenbergii (0.080±0.001 g) through different modes such as through feed, water and both. The probiotic potential of the above bacteria in terms of improvements in water quality, growth, survival, specific growth rate (SGR), feed conversion ratio and immune parameters was evaluated. The treatment groups showed a significant improvement in SGR and weight gain (P<0.001). Survival among different treatment groups was better than that in the control group. There were also significant improvements in the water quality parameters such as the concentration of nitrate and ammonia in the treatment groups (P<0.05). Improvements in immune parameters such as the total haemocyte count (P<0.05), phenoloxidase activity and respiratory burst were also significant (P<0.001). It is concluded that screening of the natural microflora of cultured fish and shellfish for putative probionts might yield probiotic strains of bacteria that could be utilized for an environment‐friendly and organic mode of aquaculture.  相似文献   

12.
The aquafeed development has been initiated for horseshoe crabs in captivity. However, much of the attentions were to the juveniles for their widely used in research. Until recently, the research had incorporated the adult horseshoe crabs. This study aims to 1) determine the best alternative feeds for adult males of Carcinoscorpius rotundicauda, 2) measure the acceptance rate of feed, and 3) feeding utilization. Three semi‐moist pellets were either developed or purchased: fish (Decapterus russeli) and cockle (Anadara granosa) pellets (A), fish pellets (B) and keropok pellets (C). Natural feeds act as control: cockle, Anadara granosa (D) and fish, D. russeli (E). The horseshoe crabs were fed daily for 5 weeks and were analysed on their feed percentage consumption, body weight changes, feeding rate (FR), absorption efficiency (AE), feeding conversion ratio (FCR) and specific growth rate (SGR). Feed A was consumed the most (56.21%) with the highest FR (1.88%). It was influenced by the pellet's hardness, where horseshoe crabs favoured softer pellets. Body weight changes, FCR and SGR also showed a similar trend of favouring alternative feed over natural feed. Alternative feeds served a better feed than the natural feed and can be an option for future natural feed replacement for adult horseshoe crabs in captivity. Alternative feed served a better diet than the natural feed and Feed B served the best feed among the three alternative feeds with good C. rotundicauda growth performance and the feed itself is cost‐wise.  相似文献   

13.
A study was conducted to test the performance of a high‐density (>3000 individuals/mL) continuous recirculating system for rotifers (B. rotundiformis) fed nonviable Nannochloropsis oculata and using sodium hydroxymethanesulfonate to neutralize ammonia. Three different microalgae feed rates (g of N. oculata [68 × 109 cells/mL] per million rotifers/d) were tested in successive trials. In Trial 1 (feed rate = 1.5), during a 30‐d period, rotifers were harvested daily to 3000 individuals/mL, for an average yield of 178 million/d. Feed efficiency (million rotifers/g/d) was 0.33. In Trial 2 (feed rate = 1.1), during a 32‐d period, an average of 106 million rotifers were harvested daily, and feed efficiency was 0.26. In Trial 3 (feed rate = 1.3), during a 30‐d period, an average of 107 million rotifers was harvested daily, and feed efficiency was 0.23. An economic analysis based on a feed rate of 1.5 showed that production cost was 40% lower than the traditional batch culture method (US$ 0.29 vs. 0.46 per million rotifers/d). The continuous culture system tested reliably produced large quantities of rotifers on a daily basis without the use of a biofilter and with a lower production cost than a batch culture system.  相似文献   

14.
The effect of dietary probiotics (Bacillus subtilis, Bacillus licheniformis and Enterococcus faecium) used singularly and synergistically on the growth performance, intestinal microbiota and health status of rainbow trout (Oncorhynchus mykiss Walbaum) were assessed after 10 weeks feeding on supplemented diets. No significant improvements of weight gain or specific growth rate were observed in the probiotic fed groups. However, a significant improvement of feed conversion ratio was observed in the group fed E. faecium. High levels of probiotic species were observed in the posterior gastrointestinal tract as transient digesta‐associated populations and potentially resident mucosal populations. Bacillus subtilis and B. licheniformis levels accounted for 36% of the total culturable microbial population adhered to the mucosa and 62% in the digesta. E. faecium levels accounted for 45% of the mucosal population and 89% of the population in the digesta. An increase of serum lysozyme activity was observed in the fish fed diets containing the Bacillus probionts and elevated leukocyte levels were observed in fish fed diets containing Bacillus + E. faecium synergistically. The results of the current study demonstrate potential for B. subtilis, B. licheniformis and E. faecium to improve feed utilization, modulate intestinal microbiota and the health status of rainbow trout.  相似文献   

15.
The copepod Cyclopina kasignete is a potential live food in aquaculture and its fatty acid components and digestive enzymes were investigated. Three dry algal products (mixed algae, Melosira sp. and Nannochloropsis oculata) and two fresh microalgae (Tisochrysis lutea and N. oculata) were fed to the copepod for 30 days. The essential fatty acids (EFA) in copepods were altered by feeding different types of dry algae. The copepod fed dry Melosira sp. or fresh T. lutea contained higher eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (ARA), protease and trypsin than fed on other algae. The copepod contained a similar fatty acid profile and digestive enzymes by feeding either dry or fresh N. oculata. Between fresh algal species, the copepod fed T. lutea contained higher EPA, DHA and ARA than that fed fresh N. oculata. The amounts of EPA and DHA in copepods were more concentrated than those in the dietary algae, suggesting that the copepod has the ability to accumulate some EFA. This study indicates that dietary algae can modify the nutritional composition and in digestive enzymes copepods, which in turn may be able to transfer suitable nutrients and digestive enzymes to fish larvae in aquaculture.  相似文献   

16.
Turkish Towel Chondracanthus exasperates and taurine were added to alternative plant‐based feeds for juvenile sablefish Anoplopoma fimbria to evaluate the effect of these ingredients, alone or combined, on fish growth, feed intake and efficiency, whole body nutrient composition, and liver histomorphology. Fish growth was significantly increased with the addition of taurine, and to a lesser extent, Turkish Towel to the experimental feeds. Feed efficiency and protein retention were significantly improved with the addition of taurine, but were unaffected by Turkish Towel addition. As expected, whole body taurine content was significantly affected by taurine addition. Increases in whole body lipid were observed with both taurine and Turkish Towel addition, with a significant interaction between the two factors. Liver histomorphology was generally normal; however, histopathologic changes were observed in some fish at the end of the experiment. The occurrence of hepatocellular nuclear pleomorphism and clear cell foci was less among fish that had received the Turkish Towel feeds. The addition of taurine had no effect on the number of fish with a histopathologic change. Overall, results from this study reaffirm taurine supplementation is beneficial to sablefish receiving plant‐based feeds and indicate Turkish Towel may be a promising feed ingredient for this species.  相似文献   

17.
To quantify the efficacy and cost of different soya protein ingredients, heated soya beans (HSB) and underprocessed (SB) full‐fat soya beans (FFSB), soya protein concentrate (SPC) and trim waste from Pacific whiting (Merluccius productus) were incorporated into feeds for the cold water marine sablefish (Anoplopoma fimbria). Feed ingredients for this study were processed using an experimental heated ball mill with demonstrated potential as an affordable process for rural or small‐scale feed production. The three feed treatments were formulated with equal amounts of soya protein and Pacific whiting process trim. The three feed treatments contained 46% protein and 18% lipid as dry matter. Three 480‐L tanks of 10 fish were used to evaluate each of the three feed treatments. Fish were fed to satiation every 2 days for 8 weeks. Weight gain of the treatment groups ranged between 56% and 105% over the course of the study. Fish growth was significantly better among fish receiving the feeds containing HSB and SPC than a feed containing SB. At the conclusion of the study, histomorphologic evaluations of the distal intestines of final fish were conducted. Varying levels of inflammation were measured for all three treatments. Fisher's exact test showed a significant reduction in mononuclear cell infiltration among fish fed heat‐treated full‐fat soya beans vs those receiving underprocessed full‐fat soya beans. Fish receiving HSB feed had significantly lower intestinal inflammation than SB fish. Based on our results, cost savings of $ 0.253/kg were calculated for the HSB feed over the SPC feed.  相似文献   

18.
The relative contributions of feed sources were determined through the isotopic signal (δ13C and δ15N) and fatty acid profile of feed items, shrimp muscle, and eggs of Litopenaeus vannamei reared in a biofloc system. In the growout phase, the isotope analysis showed the biofloc particle size class ≥250 μm contributed 55–100%; size ≥50 < 250 μm contributed 0–22%; and artificial feed contributed 0–45%. Principal component analysis applied to fatty acid profiles showed that biofloc ≥250 μm and artificial feed were the most important items in shrimp growout. For the egg production, isotope analysis suggested that the most important feed sources according to their relative contributions were polychaetes (0–100%), followed by artemia biomass (0–86%) and semi‐moist feed (0–66%), with lower contributions from squid, mussel, and the muscle of L. vannamei broodstock that had been cultured in biofloc. In terms of fatty acids, the most important items were artemia, polychaetes, and semi‐moist feeds. This work clarified the importance of feed sources for shrimp during culture in biofloc systems and during reproduction. Analysis of stable isotopes and fatty acids can be successfully used to trace the assimilation of nutrients during the nutrition of shrimp.  相似文献   

19.
Stable carbon isotope ratios (?3C) and stomach contents were used to determine the diet of channel catfish (Ictalurus punctatus) and freshwater Malaysian prawns (Macrobrachium rosen-bergii) in polyculture. Catfish stomach contents were dominated by formulated rations. Macrophyte fragments and catfish ration were predominate in prawn stomachs. Catfish ?13C ratios became lighter from June to October, which paralleled the change in ?13C ratio of the formulated feeds fed to the fish. Prawn ?13C ratios became heavier from June to October with a change in diet from seston to aquatic macrophytes and formulated catfish feed. Formulated feeds contributed 68-99% of catfish growth, and “natural” pond biota, principally insects, the remainder. Prawns depended to a greater extent on the autotrophic food web for their diet. Seston and macrophytes contributed 18-75% of prawn growth, and formulated feeds the remainder. The prawns fed on seston at small sizes (<7 g) and consumed more aquatic macrophytes and formulated catfish ration at larger sizes (<7 g).  相似文献   

20.
Protein digestibility by gastrointestinal homogenates of Dicentrarchus labrax, was investigated in 5 feeds in relation to their amino acids composition and their ability to sustain growth of D. labrax post larval juveniles. Gastric proteolysis was found to contribute <25% of the total proteolytic capacity. Correlation was found between intestinal proteolytic capacity and the feed protein content of three pairs of amino acids. The sum of basic amino acids, arginine + lysine in the feed protein exhibited a positive correlation with susceptibility to proteolysis. The sum of the acid amino acids glycine and proline showed a negative correlation.Comparison of the intestinal proteolytic enzymatic activities in 3 growth stages of this species revealed similar profiles. Post larval and large juveniles had similar proteolytic capacities when compared on the basis of equal activity on an artificial substrate of Trypsin. Specific growth rates of post larval fish fed on these 5 feeds correlated positively with their protein digestibility as measured with large juvenile's intestinal homogenates. The results suggest that in this species, the efficiency of feeds in sustaining growth at the post larval stage can be estimated by measuring the feed protein digestibility by the proteolytic system of larger sized juveniles.  相似文献   

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