首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 78 毫秒
1.
This study established that geosmin depuration from European eel is not affected by the water renewal rate of depuration tanks. A general fish bioaccumulation model extended with terms that account for effects of tank water renewal rate and system losses of chemicals, predicted strong effects of the water renewal rate of depuration tanks on geosmin depuration from European eel. Model predictions were validated in a depuration experiment with geosmin‐loaded European eel (n = 95) with a mean (SD) individual weight of 134.4 (5.0) g and a mean (SD) lipid content of 33.7 (2.8) % (w/w). Fish were depurated for 24, 48 or 72 h at three different tank water renewal rates (0.3, 3.3 and 33 day?1). Treatments were installed by three different mean (SD) water flow rates (13.8 (1.3), 143.5 (9.2) and 1511 (80) L kg fish?1 day?1) over 30‐L tanks. Eels eliminated geosmin from their bodies, but unlike the model predicted, this was independent of the water renewal rate of the depuration tanks. Although being eliminated from the fish, geosmin hardly appeared and certainly did not accumulate in the water of the depuration tanks as the model predicted. This observation may be explained by geosmin being eliminated from eel as metabolite rather than the parent compound. Geosmin elimination from eel seems not to occur according to the generally accepted passive diffusion mechanism for excretion of lipophilic chemicals, and geosmin biotransformation by the eel seems indicated. Clearly geosmin depuration from European eel cannot be enhanced by increasing water renewal rates of depuration tanks.  相似文献   

2.
The ‘earthy’ and ‘muddy’ off‐flavours in pond‐reared fish are due to the presence of geosmin or 2‐methylisoborneol in the flesh of the fish. Similar off‐flavours have been reported in fish raised in recirculating aquaculture systems (RAS); however, little information is available regarding the cause of these off‐flavours. Our hypothesis was that earthy and muddy off‐flavour compounds, found previously in pond‐raised fish, are also responsible for off‐flavours in fish raised in RAS. In this preliminary study, we examined water, biofilms in RAS and fillets from cultured arctic charr known to have off‐flavours and requiring depuration using instrumental [solid‐phase microextraction procedure and gas chromatograph‐mass spectrometry (GC‐MS)] and human sensory analyses. Geosmin was present in the samples taken from the biofilter and on the side walls of the tanks. Two‐methylisoborneol was only found in low levels in the samples. The GC‐MS results indicated the presence of geosmin in the fillets (705 ng kg?1), but lower levels were found in the water (30.5 ng L?1). Sensory analyses also detected an earthy flavour (i.e., geosmin presence) in the fillets, and, therefore, it appears that geosmin is the main compound responsible for the off‐flavour in RAS. Further studies are being performed to identify the microorganisms responsible for geosmin production in RAS.  相似文献   

3.
Aquatic animals raised in recirculating aquaculture systems (RAS) can develop preharvest “off-flavors” such as “earthy” or “musty” which are caused by the bioaccumulation of the odorous compounds geosmin or 2-methylisoborneol (MIB), respectively, in their flesh. Tainted aquatic products cause large economic losses to producers due to the inability to market them. Certain species of actinomycetes, a group of filamentous bacteria, have been attributed as the main sources of geosmin and MIB in RAS. Previous studies have demonstrated that certain nutritional factors can stimulate or inhibit bacterial biomass and geosmin production by certain actinomycetes. In the current study, the effects of two nitrate-nitrogen (NO3--N) levels (20–40 mg/L and 80–100 mg/L) on geosmin and MIB levels in culture water and the flesh of rainbow trout (Oncorhynchus mykiss) raised in RAS were monitored. Water and fish tissue samples were collected over an approximately nine-week period from six RAS, three replicates each of low and high NO3--N, and analyzed for geosmin concentrations using solid phase microextraction–gas chromatography–mass spectrometry. Results indicated no significant difference in geosmin concentrations in water or fish flesh between the low and high NO3--N RAS. Therefore, higher NO3--N levels that may occur in RAS will not adversely or beneficially impact geosmin-related off-flavor problems.  相似文献   

4.
Common off-flavor compounds, including geosmin (GSM) and 2-methylisoborneol (MIB), bioaccumulate in Atlantic salmon Salmo salar cultured in recirculating aquaculture systems (RAS) resulting in earthy and musty taints that are unacceptable to consumers. To remediate off-flavor from market-ready salmon, RAS facilities generally relocate fish to separate finishing systems where feed is withheld and makeup water with very low to nondetectable GSM and MIB levels is rapidly exchanged, a process known as depuration. Several procedural aspects that affect salmon metabolism and the associated rate of off-flavor elimination, however, have not been fully evaluated. To this end, a study was carried out to assess the effects of swimming speed and dissolved oxygen (DO) concentration on GSM levels in water and fish flesh during a 10-day depuration period. Atlantic salmon (5–8 kg) originally cultured in a semi-commercial-scale RAS (150 m3 tank) were exposed to a concentrated GSM bath before being transferred to 12 replicated partial reuse depuration systems (5.4 m3 total volume). Two swimming speeds (0.3 and 0.6 body lengths/sec) and two DO levels (90% and 100% O2 saturation) were applied using a 2 × 2 factorial design (N = 3), and each system was operated with a 5-h hydraulic retention time, creating a water flushing to biomass ratio of 151 L/kg fish biomass/day. Geosmin was assessed at Days 0, 3, 6, and 10 in system water and salmon flesh. A borderline effect (P = 0.064; 0.068) of swimming speed was measured for water and fish, respectively, at Day 3, where slightly lower GSM was associated with low swimming speed (0.3 body lengths/sec); however, differences were not detected at Days 6 or 10 when salmon are commonly removed for slaughter. Overall, this research indicates that significant improvements in GSM depuration from RAS-produced Atlantic salmon are not expected when purging with swimming speeds and DO concentrations similar to those tested during this trial.  相似文献   

5.
A feeding trial was conducted to investigate the effects of different levels of calcium (Ca) on growth and tissue mineralization in Japanese seabass, Lateolabrax japonicus. Six experimental diets were formulated to contain different levels of Ca (2.9, 4.2, 6.5, 7.9, 10.2 and 31.0 g kg?1) from dietary ingredients and Ca‐lactate·5H2O. The diets were fed to three triplicate groups of Japanese seabass (initial weight, 12.5 ± 0.0 g) for 56 days. Dietary Ca had no significant effect on survival or feed efficiency; however, the highest Ca (31.0 g kg?1) diet significantly reduced weight gain, feeding rate and whole‐body and muscle protein and lipid contents, as well as serum Ca concentration and alkaline phosphatase activity. A significant reduction in vertebral Ca, P, Zn, Fe and Mn contents and scale Ca, P, Mg and Mn contents was observed in Japanese seabass as dietary Ca level increased. Deformed fish were primarily found in the 2.9 and 31.0 g Ca kg?1 groups, indicating that these fish had poor bone mineralization.  相似文献   

6.
This study was performed to evaluate the effect of dietary chitosan on haematology, innate immunity and protection against Vibrio anguillarum in Asian seabass, Lates calcarifer. A basal diet supplemented with 0, 5, 10 and 20 g chitosan kg?1 diet was fed to the four different groups for 60 days. The haematological (total erythrocyte count, total leucocyte count, total serum protein, albumin, globulin and albumin‐globulin ratio) and innate immune parameters (phagocytic ratio, respiratory burst, serum lysozyme and serum bactericidal activities) were monitored at fortnight interval to assess the effect of chitosan feeding in Asian seabass. All the studied haematological and innate immune parameters were increased significantly (P ≤ 0.05) in chitosan‐fed groups in comparison with control. However, the group fed diet containing 10 g chitosan Kg?1 feed showed highest haematological and innate immune parameters on 45th day in comparison with other groups. Moreover, the fish fed the diet containing 10 g chitosan Kg?1 feed had significantly higher post‐challenge survival (75.56 ± 4.44%) on the 30th day following V. anguillarum challenge. Therefore, this study suggests that chitosan at 10 g kg?1 diet could be used as prophylactic in Asian seabass culture to enhance the protection against any possible infection by V. anguillarum.  相似文献   

7.
A study was conducted to investigate effects and interactions of magnesium (Mg) and vitamin E (VE) on growth performance, body composition, hepatic antioxidant capacity and serum biochemistry parameters of juvenile Japanese seabass Lateolabrax japonicus under oxidative stress condition. Fish (initial average body weight of 6.10 ± 0.20 g) were fed 9 oxidized oil diets supplemented with 3 grade levels of Mg (0, 520 and 1570 mg kg?1 diet) and VE (0, 60 and 200 mg kg?1 diet) for 8 weeks in freshwater. The results showed that diets supplemented 520 mg kg?1 Mg and/or 60 mg kg?1 VE had highest growth and muscle lipid content. There were highest total superoxide dismutase, catalase, glutathione peroxidase activities and lowest malondialdehyde content in liver of fish fed diets supplemented 520 mg kg?1 Mg and/or 60 mg kg?1 VE. Contrary to Mg concentrations, Ca concentrations and Ca/Mg ratio in whole body were inversely related to dietary Mg levels. However, combined deficiency or excess of dietary Mg and VE led to the decrease of hepatic antioxidant capacity, body lipid deposition and growth of Japanese seabass under oxidative stress condition.  相似文献   

8.
This study investigates the effect of digestible protein levels in experimental diets for meagre (Argyrosomus regius). A group of 253 fish, 52 g of mean weight, was distributed in 12 tanks, three replicates per treatment. Four isolipidic diets (170 g kg?1 crude lipid) with different digestible protein levels (350 g kg?1, 430 g kg?1, 490 g kg?1 and 530 g kg?1) were formulated using commercial ingredients. The trial lasted 62 days. Meagre fed diets 430, 490 and 530 g kg?1 obtained higher TGC (2.47, 2.57, 2.69 × 10?3, respectively) than fish fed diet 350 g kg?1 (2.14 × 10?3). Group of fish fed diet with 350 g kg?1 DP showed the lowest ammonia excretion level. According to the in vitro digestibility trial diets with 350 and 430 g kg?1 DP released less amino acids in comparison with diet with 49% DP, although in vivo digestibility test did not show significant differences among diets 430, 490 and 530 g kg?1 DP. Using the quadratic regression, optimal digestible protein intake according to the ECR for rearing juvenile meagre was recorded in 0.8 g DP/100 g fish and day.  相似文献   

9.
Land-based Atlantic salmon, Salmo salar, grow-out facilities utilize depuration to remediate off-flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m3 in an 18 m3 depuration tank. Feed was withheld 1 day before transfer and throughout the 7-day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2-methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration.  相似文献   

10.
Nucleotide (NT) could enhance growth, feeding and immunity in higher vertebrate and fish. Chinese perch (Siniperca chuatsi) refuse artificial diet in natural water, whereas the NT might promote its feeding of domestication diet. The present study was designed to investigate the effect of dietary NT on growth, feed intake, feed utilization, body composition, serum biochemistry and nitrogen metabolism in juvenile Siniperca chuatsi. 0, 0.5, 1.0, 1.5, 2.0 and 4.0 g NT kg?1 diet were supplemented in each diet, respectively. Triplicate groups of Chinese perch (36.21 ± 0.98 g) were fed twice a day to apparent satiation for 8 weeks. The results showed that fish fed with 1.5 g NT kg?1 diet had the highest weight gain (WG), specific growth rate, feed efficiency, feed intake, protein efficiency ratio and protein retention efficiency. The crude protein content in whole body was highest in fish fed the diet containing 1.5 g NT kg?1 diet. Dietary NT supplementation significantly increased the neuropeptide Y gene expression and significantly decreased the agouti‐related protein and pro‐opiomelanocortin gene expressions in brain. NT supplementation decreased urea nitrogen content, aspartate aminotransferase (AST) and alanine aminotransferase activities in serum. The hepatic AST activity was increased first and then decreased, and the highest activity was observed in fish fed with 1 g NT kg?1 diet. Inversely, the activity of glutamate dehydrogenase (GDH) in liver and adenosine 5′‐monophosphate deaminase in muscle decreased first and then increased, and the lowest activity was observed in fish fed with 1.5 g NT kg?1 diet. Similarly, the gene expression levels of GDH and arginase in liver were lowest in fish fed with 1.5 g NT kg?1 diet. Based on the broken‐line regression analysis of WG in the present experimental condition, 1.44 g NT kg?1 diet was the optimum supplementation level in juvenile Siniperca chuatsi.  相似文献   

11.
The experiment was designed to investigate the dietary factors that might enhance or interfere with astaxanthin (Ax) absorption in salmon including potentially interfering factors such as certain carotenoids (zeaxanthin and lutein), plant sterols, fibre and enhancing compounds such as cholesterol and vitamin E. Two hundred and eighty‐eight salmon (778 ± 78 g) were reared in sea water under controlled conditions and fed practical experimental diets. The experimental diets were supplemented with 40 mg Ax kg?1, in addition to various dietary factors, including cholesterol (2%), vitamin E (450 IU kg?1), wheat bran (5%), lutein (40 mg kg?1), zeaxanthin (40 mg kg?1) and phytosterol (2%). After 26 days of feeding, blood was collected and plasma was separated to determine the plasma Ax concentration. Ax was not detected in the plasma of fish fed the non‐pigmented diet. Fish fed diet containing 2% cholesterol significantly improved Ax absorption, which was reflected in the higher Ax concentration in plasma of Atlantic salmon. Other supplements including vitamin E, wheat bran, lutein, zeaxanthin and phytosterols in diet had no significant effect on plasma Ax concentration . Fish fed diet containing 2% cholesterol significantly increased cholesterol concentration in fish plasma. Phytosterol had no benefit to lower cholesterol plasma level in fish fed 2% phytosterol‐supplemented diet.  相似文献   

12.
A growth trial was conducted to examine the effect of dietary digestible energy (DE) content on methionine (Met) utilization and requirement in juvenile Nile tilapia (Oreochromis niloticus). Ten iso‐nitrogenous (288 g kg?1 protein) practical diets, with two DE levels (10.9 MJ kg?1; 12.4 MJ kg?1) and five methionine supplementation levels (0, 1, 2, 4 and 6 g kg?1), were hand‐fed twice daily to triplicate groups of Nile tilapia (initial body weight 8.95 ± 0.06 g) for 8 weeks. Weight gain (WG) and specific growth rate (SGR) increased significantly with increasing dietary methionine concentration at the same DE content (P < 0.001). At the same dietary methionine level, WG and SGR of fish fed high‐DE diets were significantly higher than that of fish fed low‐DE diets (P = 0.0001), although no interaction was found between dietary DE and methionine supplementation. Based on quadratic regression analysis between dietary methionine concentration and weight gain, optimal methionine requirement for maximum growth, expressed as g Met required kg?1 diet (low‐ versus high‐DE diets), increased as diet DE concentration increased (7.34 versus 9.90 g kg?1 diet, respectively; with cysteine 4.70 g kg?1 diet). The results indicated that diet DE content affects methionine utilization and requirement in juvenile Nile tilapia, fish fed high‐DE diets required more methionine for maximum growth.  相似文献   

13.
A 10‐week study was conducted to investigate the effects of feeding rate and frequency on growth performance, digestion and nutrients balances of Atlantic salmon (Salmo salar) in replicated recirculating aquaculture systems (RAS). Replicated groups of juvenile salmon weighing 90 ± 2.5 g (mean ± SD) were fed a commercial feed (21.63 MJ kg?1 gross energy) to designed feeding rate (1.4%, 1.6% and 1.8% body weight day?1, BW day?1) and feeding frequency (2 and 4 meals day?1) combinations. Specific growth ratio varied between 1.15 ± 0.02 and 1.37 ± 0.16% day?1, and feed conversion ratio ranged from 0.96 ± 0.03 to 1.16 ± 0.02. The nitrogen and phosphorus retention rates were from 36.50 ± 1.94 to 47.08 ± 5.23% and from 20.42 ± 1.05 to 38.59 ± 2.80%. Apparent digestibility coefficients (ADC) in dry matter, protein, lipid and energy showed no significant differences for all groups. However, fish fed at 1.6% BW day?1 and 4 meal day?1 groups had relatively better growth and nutrient retention efficiency compared to other groups. In addition, concentrations of nitrogenous and phosphorous compounds were also detected in this study. These results suggested that salmon of 100–200 g in RAS could in practice be fed at 1.6% BW day?1 and 4 meals day?1, taking environmental impacts into account.  相似文献   

14.
Use of immunostimulants as a prophylactic measure against diseases in fish is considered as an effective alternative to antibiotic use. Plant‐derived immunostimulants have recently received more attention, as most of them are cost‐effective and eco‐friendly. This study was carried out with the objective of evaluating the possible immunostimulatory activity of intraperitoneally injected water soluble fraction of Nyctanthes arbortristis (an Indian medicinal plant) leaves on (i) specific immunity (antibody response), (ii) nonspecific immunity (Lysozyme activity, ROS production) and (iii) functional immunity in terms of disease resistance against Aeromonas hydrophila in Oreochromis mossambicus. The results of the study showed that all the tested doses (i.e. 3.2, 16, 80 and 400 mg kg?1) of water soluble fraction of Nyctanthes arbortristis leaves significantly enhanced both primary and secondary antibody responses to heat killed A. hydrophila. Significant enhancement in serum lysozyme activity by all the doses of water soluble fraction was observed on day 10. The lower doses of 3.2 and 16 mg kg?1 of water soluble fraction alone enhanced intracellular ROS production. Fish treated with both single and double dose of water soluble fraction showed maximum disease resistance. The highest dose (400 mg kg?1) of water soluble fraction exhibited highest relative per cent survival in both single dose and double dose groups.  相似文献   

15.
Cadmium (Cd) is a toxic environmental pollutant with a long biological half‐life and can produce both hepatic and renal injuries in mammals and fish. Squid viscera meal (SVM), an effective attractant for aquatic animals, is widely used as an ingredient in aquafeeds. However, SVM is rich in Cd and its complexes. A study was conducted to evaluate the effects of dietary SVM on the growth and Cd deposition in tissues of Japanese seabass, Lateolabrax japonicus. Three practical diets were formulated to contain 0, 50 and 100 g SVM kg?1 diet, respectively, containing 0.21, 7.26 and 12.08 mg Cd kg?1 diet. Each diet was randomly assigned to triplicate groups of 80 Japanese seabass (mean initial weight, 10.89±0.21 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Fish were fed twice daily (06:30 and 16:30 hours) to satiation for 8 weeks. The results showed that there were no significant differences in fish survival among three dietary treatments, but significant higher specific growth rates (SGR) were observed in the fish fed diets with 50 or 100 g SVM kg?1 diet than that from the control group (P<0.05). The Cd concentrations in the kidney, liver and gill were found in a decreasing order at each treatment, and positively correlated with dietary Cd levels. Fish fed diets with 50 and 100 g SVM kg?1 diet had significantly higher Cd accumulations in the kidney (3.25, 5.85 mg kg?1), liver (0.76, 1.26 mg kg?1) and gill (0.42, 0.58 mg kg?1) compared with the control group (0.82, 0.34 and 0.32 mg kg?1 respectively) (P<0.05). The Cd concentration in fish muscle; however, was undetectable in any treatment. Therefore, based on these results, accumulation of Cd in edible tissue (muscle) of farmed Japanese seabass is not a food safety issue. However, long‐term feeding of diets with SVM may result in accumulation of Cd in the kidneys, liver and gills of fish.  相似文献   

16.
Ethoxyquin (EQ) is the most common synthetic antioxidant used for preventing rancidity in fish foodstuffs. However, literature related to the effects of dietary EQ on performance of fish was limited. The present study was conducted to investigate the effects of EQ on performance and EQ residue in muscle of juvenile Japanese seabass Lateolabrax japonicus and to estimate the optimal EQ concentration in the diet. Graded levels [0 (control), 50, 150, 450 and 1350 mg EQ kg?1 diet] of EQ were added to the basal diet, resulting in five dietary treatments in the experiment. Each diet was fed to triplicate groups of seabass (initial body weight 8.01 ± 0.76 g) for 12 weeks in floating sea cages (1.5 × 1.5 × 2.0 m, 30 fish per cage). Survival ranged from 78.9 to 86.7%, and was irrespective of dietary EQ levels. The specific growth rate (SGR) of fish fed diets supplemented with ≤50 mg kg?1 EQ had significantly (P < 0.05) higher SGR than fish fed diets supplemented with ≥150 mg kg?1 EQ, the highest SGR was observed in fish fed diet with 50 mg kg?1 EQ supplementation. Feed intake (FI) and feed efficiency (FE) were not significantly (P > 0.05) different among dietary treatments. Fish fed diets with 50 and 1350 mg kg?1 EQ had a significant (P < 0.05) lower body lipid content than fish in the control group. Muscle EQ level significantly increased when dietary EQ increased. Optimal EQ concentration estimated by polynomial regression based on maximum growth of juvenile Japanese seabass was 13.78 mg kg?1 diet.  相似文献   

17.
Skipjack tuna viscera hydrolysate (TVH) was produced by enzymatic hydrolysis using alcalase. A study of the effect of time and enzyme concentration was performed and formed the basis for preparing TVH with the desired degree of hydrolysis (DH). An enzyme to substrate ratio of 5 g kg−1 (TVH A1) and 16.4 g kg−1 (TVH A2) at pH 8.0 with a temperature of 50 °C, and hydrolysis time of 60 min were found to be optimal conditions to obtain hydrolysis of 42.9% and 62.9%, respectively. Both TVH A1 and TVH A2 were analysed for chemical and amino acid composition and peptide size. The effectiveness of TVH at different DH as feeding attractants was estimated in a feeding trial at different inclusion levels. Ten experimental diets , including a fish meal‐based reference diet, were fed to Asian seabass for 28 days. Fish fed the diet supplemented with 30 g kg−1 of TVH A2, and the reference diet showed the highest feed intake (P < 0.05). The growth performance of fish fed diets supplemented with TVH was slightly higher than those of fish fed the control diet, but the reference group showed a significantly higher growth rate (P < 0.05). These findings suggest that the supplementation of feed with TVH that has been processed under suitable conditions can improve feed palatability and growth performance when utilizing alternative protein sources in Asian seabass diets.  相似文献   

18.
A digestibility and a growth trial were conducted in this study respectively. Firstly, the apparent digestibility coefficients (ADC) of nutrients and energy in meat and bone meal, porcine meal (PM), hydrolysed feather meal, poultry by‐products meal, fishmeal (FM), soybean meal and spray‐dried blood meal were determined. In experiment 2, an 8‐week growth trial was conducted to evaluate the effects of the substitution of FM by PM under the digestible ideal protein concept at two protein levels in the diets of Japanese seabass, Lateolabrax japonicus. A FM‐based control diet (FM diet; FM: 320 g kg?1, crude protein: 434.9 g kg?1, crude lipid: 124.6 g kg?1) and three other diets were formulated to contain 115 g kg?1 PM and only 160 g kg?1 FM. Two diets were formulated on a crude protein basis without (PM diet) or with (PMA diet) essential amino acid (EAA) supplementation respectively. A low‐protein diet was designed (LPMA diet, crude protein: 400.9 g kg?1, crude lipid: 96.3 g kg?1) with the same level of FM and PM but with the same digestible protein/ digestible energy and EAA profile as the FM diet. The results showed that nitrogen and total amino acid digestibility of the tested ingredients were ranged from 85.6% to 95.5% and from 87.6% to 95.5% respectively. Apparent digestibility coefficients of protein for FM and PM were 91.2% and 95.9% respectively. In the growth trial, the weight gain rate and feed conversion ratio of fish fed the PMA diet did not show a significant difference from those of the control group, but were significantly higher than those of the PM and LPMA groups (P<0.05). Growth was related linearly to lysine and methionine intakes. It was shown that PM could be utilized in the Japanese seabass diet up to 115 g kg?1 to replace about 160 g kg?1 of FM protein under an ideal protein profile. Essential amino acid deficiency (diet PM) or a lower protein level despite having an ideal amino acid profile (diet LPMA) could not support the optimal growth of Japanese seabass.  相似文献   

19.
Elvers and glass eels of Anguilla anguilla were fed diets containing two types of feeding stimulants (FS) that were based on processed marine (MBFS) and yeast proteins (YBFS). Elvers (1.5 ± 0.3 g) were fed seven diets (MBFS and YBFS diets at 20 g kg?1, 40 g kg?1 and 60 g kg?1 plus control) for 60 days. Glass eels (250 ± 100 mg) were weaned to 60 g kg?1 MBFS, 60 g kg?1 YBFS and control diets for 30 days. Diets containing 60 g kg?1 FS had a beneficial effect in terms of growth, homogenous size distribution and feed intake in elvers. Elvers fed 60 g kg?1 MBFS and YBFS diets grew 11.9% and 5.6% faster than the control group. No differences in growth and size distribution were detected in glass eels fed 60 g kg?1 MBFS and YBFS diets. However, FS affected the digestive system maturation; fish fed the 60 g kg?1 MBFS and YBFS diets showed higher and intermediate values in the specific enzyme activities in comparison with the control group. This study revealed that the incorporation of FS into a pelleted diet was beneficial on the overall performance of European glass eels and elvers. However, the observed results were different depending on the eel’s stage of development, as well as the type and inclusion level of the FS.  相似文献   

20.
A 15‐week trial was carried out to estimate the effects of functional compound additives (FCA) on intestinal morphology and microbiome in Japanese seabass, Lateolabrax japonicus, fed diets with soybean meal (SBM) partially replacing fish meal (FM). The formulation of FCA was the mixture of antioxidant, immunopotentiator and Mintrex® trace elements. Four isonitrogenous (45%) and isolipidic (11%) diets, including FM42 (the control group without FCA), FM35 (15% FM protein substitution level with FCA), FM21 (50% FM protein substitution level with FCA) and FM21‐N (50% FM protein substitution level without FCA) were formulated. Quadruplicate groups of seabass (initial average weight 125.65 ± 0.60 g) were randomly handfed each diet twice daily in seawater floating cage. No significant differences were found in microvillus height (HMV) and muscular thickness (MT) of distal intestine among fish fed FM42, FM35 and FM21, whereas the HMV, MT and fold height (HF) in seabass fed FM42 were significantly higher than those of seabass fed FM21‐N (P < 0.05). Seabass fed FM21‐N had more obvious enteritis parameters such as tissue disruption, wider lamina propria and less mucosal fold than those in seabass fed FM21. High‐throughput sequencing technology of gut flora showed that Proteobacteria was the most dominant bacteria at phylum level among groups. There was no significant difference in relative abundance and composition of gut microflora among groups. In conclusion, supplementation of FCA might partially eliminate SBM‐induced enteritis, but the composition and relative abundance of intestinal microflora were not affected by dietary treatments.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号