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1.
The effects of partial replacement of fish meal (FM) with meal made from northern krill (Thysanoessa inermis), Antarctic krill (Euphausia superba) or Arctic amphipod (Themsto libellula) as protein source in the diets for Atlantic salmon (Salmo salar L.) and Atlantic halibut (Hippoglossus hippoglossus L.) on growth, feed conversion, macro‐nutrient utilization, muscle chemical composition and fish welfare were studied. Six experimental diets were prepared using a low‐temperature FM diet as control. The other diets included northern krill where 20, 40 or 60% of the dietary FM protein was replaced with protein from northern krill, and two diets where the FM protein was replaced with protein from Antarctic krill or Arctic amphipod at 40% protein replacement level. All diets were iso‐nitrogenous and iso‐caloric. Atlantic salmon grew from 410 g to approximately 1500 g during the 160 day experiment, and Atlantic halibut grew from 345 g to 500–600 g during the 150 day experiment. Inclusion of krill in the diets enhanced specific growth rate in salmon, especially during the first 100 days (P < 0.01), and in a dose–response manner in halibut for over the 150 day feeding period (P < 0.05). Feed conversion ratio did not differ between dietary treatments, and no difference was found in dry matter digestibility, protein digestibility and fish muscle composition. Good growth rates, blood parameters within normal ranges and low mortalities in all experimental treatments indicted that fish health was not affected either Atlantic salmon or Atlantic halibut fed the various zooplankton diets.  相似文献   

2.
The present study investigated the distribution of α‐tocopherol (vitamin E) in fillets of turbot (Scophthalmus maximus) and Atlantic halibut (Hippoglossus hippoglossus). Turbot and Atlantic halibut were fed commercial diets, supplemented with different levels of α‐tocopheryl acetate at the dietary target levels of 100, 500 and 1000 mg α‐tocopheryl acetate kg?1 diet. The actual levels were 72, 547 and 969 for turbot, while halibut received 189, 613 and 875 mg α‐tocopheryl acetate kg?1 diet. Turbot were fed the diets for 24 weeks, while Atlantic halibut were fed for 20 weeks prior to slaughter. At the end of the feeding periods fish had reached a final weight of around 1 kg. Fish were slaughtered and filleted. From the four fillets obtained per fish, 22 samples were taken from designated areas and analysed for their α‐tocopherol content. The average concentrations of α‐tocopherol incorporated in turbot and Atlantic halibut increased with increasing levels of α‐tocopheryl acetate in the diet. Atlantic halibut had significantly (P < 0.05) more α‐tocopherol in positions 2/II and 1/I than in position 9/IX. Turbot had significantly (P < 0.05) more α‐tocopherol in position 2/II than in positions 1/I, 4/IV and 11/XI. By mapping α‐tocopherol concentrations in fish fillets, a high degree of quality prediction may be established. Moreover, this study may help scientists in their choice of sampling position, when investigating if α‐tocopheryl acetate supplementation resulted in successful α‐tocopherol incorporation.  相似文献   

3.
Stress in response to anesthesia with benzocaine, MS-222, metomidate and isoeugenol was studied in Atlantic salmon (Salmo salar), Atlantic halibut (Hippoglossus hippoglossus), and Atlantic cod (Gadus morhua) with no concomitant stress from handling or confinement in association with anesthesia or sampling. All of the anesthetics tested induced a stress response in all species, displayed by a release of cortisol to the water. MS-222 anesthesia elicited the highest cortisol release rates, reaching maximum levels 0.5 h post-exposure and returning to basal levels after 3–4 h. Benzocaine anesthesia caused a bimodal response where the initial peak in cortisol release rate was followed by a second increase lasting towards the end of the trial (6 h). This bimodality was more profound in Atlantic salmon than in Atlantic halibut and Atlantic cod. Metomidate anesthesia induced the lowest release of cortisol of the agents tested in both Atlantic halibut and Atlantic cod, but resulted in a bimodal response in Atlantic salmon where the initial increase in cortisol release was followed by a larger increase peaking at 2–2.5 h post exposure before returning to basal levels after 5 h. The stress induced in Atlantic salmon by isoeugenol anesthesia resembled that of MS-222, but did not reach the same elevated level. Overall, the cortisol release was most profound in Atlantic salmon followed by Atlantic halibut and Atlantic cod.  相似文献   

4.
Major challenges in culture of Atlantic halibut larvae have been slow growth during the late larval stages and inferior juvenile quality due to pigmentation errors and incomplete eye migration during metamorphosis. The hypothesis of this study was that feeding on‐grown Artemia would alleviate these problems. Artemia were grown for 3–4 days on Origreen or Origo. The growth and nutrient composition of Artemia nauplii and on‐grown Artemia were analysed, and both Artemia types were fed to Atlantic halibut larvae, on‐grown Artemia from 15 days post‐first feeding (dpff). The body length of Artemia increased with 20%–70% in response to on‐growing. In all experiments, protein, free amino acids and the ratio of phospholipid to total lipid increased, while lipid and glycogen decreased. The fatty acid composition improved in some cases and not in others. The micronutrient profiles were not negatively affected in on‐grown Artemia. All these changes are thought to be beneficial for marine fish larvae. The final weight of Atlantic halibut postlarvae was similar, and 90% of the juveniles had complete eye migration in both groups. It is concluded that the present version of Artemia nauplii probably covers the nutrient requirements of Atlantic halibut larvae.  相似文献   

5.
The effect of adding 0%, 1%, 2% and 5% chitin from prawn shells in the diets for Atlantic cod, Atlantic halibut and Atlantic salmon on growth was investigated. Nutrient digestibility and feed utilization was investigated in salmon and cod. Atlantic cod grew from 186 ± 29 to 383 ± 78 g (N = 960) over 13 weeks. Dietary chitin had no effect on length, weight, condition, liver size or specific growth rate (SGR). The apparent digestibility (ADC) for protein ranged from 84.7% to 86.5%, lipid between 88.8% and 93.1% and dry matter from 96.1% to 96.6%. Feed utilization varied between 1.08 and 1.11 and was not correlated with dietary chitin content. Atlantic salmon tripled their weight from 199 ± 9 to 615 ± 75 g (N = 480) during the 13 weeks. High inclusions of chitin (>1%) reduced both growth rate and condition. Protein and lipid ADC was negatively correlated with dietary chitin. Feed utilization ranged between 0.86 and 0.90 and was not significantly affected by dietary chitin. Faecal protein increased significantly with increasing dietary chitin, while faecal dry matter and lipid did not. Individually tagged Atlantic halibut grew from 1300 ± 470 to 2061 ± 714 g (N = 70) during 6 months. Individual growth rates varied within each group from being slightly negative to 0.81%·day?1. Diet had no significant effect on growth rates. Atlantic cod and Atlantic halibut seems unaffected by up to 5% chitin additions in the diet, while chitin >1% of diet negatively affects growth and nutrient utilization in Atlantic salmon.  相似文献   

6.
Turbot and Atlantic halibut are highly valued fish species. However,very little is known about fillet shelf-life characteristics associated withboth species. Thus, fillet -tocopherol content and proximate compositionof wild turbot (1.5 kg) and Atlantic halibut (1.1 kg)caught off the south coast of Ireland and the north-west coast of Iceland,respectively, were investigated. In addition, the susceptibility of fillets, storedunder retail conditions, to lipid oxidation and colour change was studied.Proximate composition analysis showed that turbot had significantly highermoisture (P < 0.001) and lower protein (P < 0.001) contents compared toAtlantic halibut. Atlantic halibut incorporated significantly higher (P <0.001) levels of -tocopherol into fillets than turbot. Over 14 days ofstorage on ice, fillets from Atlantic halibut exhibited significantly lower (P =0.020) levels of lipid oxidation than those of turbot. However, malondialdehyde(MDA) concentrations were generally very low, never exceeding 0.6 gg–1 fillet. Turbot maintained a significantly higher (P< 0.001) pH over the storage period. The lightness (L* values) offillets from both species increased over 14 days of storage, but wassignificantly higher (P < 0.001) in Atlantic halibut than in turbot. Turbotdeveloped a relatively intense yellow colour during storage (decrease in hueangle and increase in b* values), whereas this was not the case forAtlantic halibut. The results of this study demonstrate that fillets of wildAtlantic halibut stored on ice, were less prone to lipid oxidation anddiscolouration than those of wild turbot. However, quality changes in turbotwere very small showing that both fish have tremendous shelf-life capacities interms of lipid oxidation. These findings are considered in the context of knownmaterial for farmed fish.  相似文献   

7.
Atlantic halibut (Hippoglossus hippoglossus L.) larvae were fed enriched Artemia or zooplankton in duplicate tanks from 0 to 60 days after first‐feeding. Both diets and the larvae were analysed for vitamin A (VA) in order to confirm earlier findings, in which Artemia fed larvae had lower levels of VA compared with larvae fed zooplankton. Furthermore, we wanted to investigate the composition of the retinoids in the larvae. The results showed that Artemia and zooplankton contains low levels of VA, probably too low to sustain the assumed requirement. Nevertheless, larvae fed Artemia had the same level of retinal and retinol as larvae fed zooplankton. We found a significant lower level of retinyl esters in larvae fed Artemia. The total VA level was lower in larvae fed Artemia only at the end of the feeding trial after the onset of metamorphosis. Our conclusion is that feeding Artemia to Atlantic halibut larvae is not likely to cause VA deficiency.  相似文献   

8.
Τhe uptake and distribution of lipopolysaccharide (LPS), isolated from Aeromonas salmonicida, was investigated in Atlantic cod, Gadus morhua L., turbot, Scophthalmus maximus L., and Atlantic halibut, Hippoglossus hippoglossus L. LPS was radiolabelled by bromine oxidation and subsequent sodium borotritide reduction (3H-LPS), and fluorescence-labelled by introducing a fluorescein isothiocyanate derivative (FITC-LPS). After intravenous and intraperitoneal injections in cod, high amounts of radioactive LPS (3H-LPS) were present in heart, spleen and kidney throughout the experimental period (1–168 h). After peroral administration, a high amount of 3H-LPS was observed in intestinal tissues, whereas internal organs and tissues contained considerably lower amounts. Following intravenous administration of 3H-LPS in turbot, high contents of radioactivity were revealed in spleen, liver and kidney, whereas the content in heart was lower than in blood at the sampling times (1–24 h). The same pattern was observed after intraperitoneal administration. The spleen and liver contained high amounts of radioactivity when the turbots were intubated perorally with 3H-LPS. The spleen, kidney and heart were the main scavenging organs following intravenous administration of 3H-LPS in Atlantic halibut. A minor amount of radioactivity was present in the liver. The same pattern emerged after intraperitoneal injection in halibut. As observed for turbot, the spleen was the main accumulation site for 3H-LPS following peroral administration. Fluorescence microscopy of sections of organs and tissues from cod, intravenously and intraperitoneally injected with FITC-LPS, revealed that endocardial cells of both atrium and ventricle contained large amounts of the fluorochrome, whereas in turbot and halibut only atrial endothelial cells accumulated the substance. In all species, macrophages in kidney and spleen contained FITC-LPS and in the spleen the fluorochrome was trapped in the ellipsoidal walls. At later time points (e.g. 48 h) in the turbot spleen, FITC-LPS was located in cells adjacent to the ellipsoidal walls. Halibut endothelial cells that were located in the connective tissue of the intestine and gills also contained FITC-LPS. After peroral administration to the different fish species, specific fluorescence was found only in intestinal epithelial cells of halibut and in cells located in the lamina propria. Fluorescence was not detected in internal organs such as the kidney, spleen and liver after peroral administration of FITC-LPS. Gel chromatographic analysis of plasma samples from cod, turbot and halibut after intravenous and intraperitoneal injections showed that high molecular weight radioactivity was present. A minor amount of radioactivity that corresponded to low molecular weight substances was also observed. In conclusion, there is a high degree of variation with respect to the site of accumulation and some variation in the type of cells involved in the uptake of purified LPS in cod, turbot and halibut.  相似文献   

9.
Vitellogenin (VTG) synthesis was induced by repeated injections of estradiol-17 in juvenile Atlantic halibut (Hippoglossus hippoglossus). VTG eluted as a large, phosphoprotein containing peak on DEAE-Sephacel chromatography of plasma from estradiol-17 treated juvenile and mature female, but not mature male halibut. A purification procedure for Atlantic halibut VTG was developed, where VTG was precipitated with MgCl2, EDTA and distilled water, and the precipitated protein submitted to anion exchange chromatography on DEAE-Sephacel. Precipitated VTG eluted as a broad, partly dissociated peak on DEAE-Sephacel, when chromatography was run at 4°C, but the protein appeared intact when analysed both by SDS PAGE and native PAGE. DEAE-Sephacel chromatography at room temperature resulted in an irregular elution pattern and a dissociated protein fraction, as analysed by SDS PAGE. Biochemical characterization of VTG showed that the molecular mass of the monomer was ca 160 kDa, as estimated by SDS-PAGE. The total lipid content was 19.8% w/w, with 64%, or 12.7% of the total weight, as phospholipid. Protein bound phosphorus constituted 0.62% w/w of halibut VTG. Plasma dilution curves from mature and maturing female halibut were parallel with a dilution curve from halibut egg yolk homogenate in an homologous RIA. Plasma from mature male, but not juvenile halibut crossreacted with the VTG antiserum.  相似文献   

10.
Three different concentrations (107, 105 and 103 TCID50 ml?1) of infectious pancreatic necrosis virus (IPNV) serotype Sp isolated from Atlantic halibut, Hippoglossus hippoglossus L., were used to bath-challenge Atlantic halibut yolk-sac larvae. The larvae challenged with 107 TCID50 ml?1 suffered significantly higher cumulative mortality than the other challenged groups and the control group, and affected individuals displayed necrosis of the intestine, liver and kidney. In larvae from the groups challenged with 107 and 105 TCID50 ml?1, IPNV was detected by immunohistochemistry and in situ RNA/DNA hybridization in the intestine, liver and kidney. In addition, some individuals stained IPNV-positive in the heart and eye/ brain region. Detection by in situ hybridization did not appear to be more sensitive than immunohistochemistry. However, background staining was virtually absent in comparison with immunohistochemistry, and the staining seemed to be more distinctly localized to the cytoplasm of infected cells. The results show that farmed halibut yolk-sac larvae can be infected by IPNV immediately after hatching, with resulting high mortality. As the larvae are not immunologically mature at this stage of development, vaccination is not recommended.  相似文献   

11.
Three different concentrations (107, 105 and 103 TCID50 ml-1) of infectious pancreatic necrosis virus (IPNV) serotype Sp isolated from Atlantic halibut, Hippoglossus hippoglossus L., were used to bath-challenge Atlantic halibut yolk-sac larvae. The larvae challenged with 107 TCID50 ml-1 suffered significantly higher cumulative mortality than the other challenged groups and the control group, and affected individuals displayed necrosis of the intestine, liver and kidney. In larvae from the groups challenged with 107 and 105 TCID50 ml-1, IPNV was detected by immunohistochemistry and in situ RNA/DNA hybridization in the intestine, liver and kidney. In addition, some individuals stained IPNV-positive in the heart and eye/brain region. Detection by in situ hybridization did not appear to be more sensitive than immunohistochemistry. However, background staining was virtually absent in comparison with immunohistochemistry, and the staining seemed to be more distinctly localized to the cytoplasm of infected cells. The results show that farmed halibut yolk-sac larvae can be infected by IPNV immediately after hatching, with resulting high mortality. As the larvae are not immunologically mature at this stage of development, vaccination is not recommended.  相似文献   

12.
Atlantic halibut juveniles, which have been fed Artemia during larval development, frequently demonstrate malpigmentation and impaired eye migration. This is in contrast to the high percentage of normally developed larvae fed copepods, reared under similar conditions. Nutrition is therefore an important component influencing larval development. Analyses of the nutrient composition of Artemia and copepods show that Atlantic halibut larvae fed Artemia probably receive sufficient amounts of vitamin A by converting canthaxanthin, while iodine may be deficient, possibly leading to interrupted thyroid hormone synthesis. An unbalanced fatty acid composition, such as high levels of arachidonic acid and low levels of docosahexaenoic acid, can be another limiting factor in Artemia. Vitamin A, fatty acids and thyroid hormones have all been shown to affect pigmentation in flatfish. They are ligands to nuclear receptors, thyroid hormone receptors, retinoic acid receptors, retinoic X receptors and peroxisomal proliferator‐activated receptors, which are members of the superfamily of steroid hormone receptors. The receptors interact with each other to promote gene expression that modulates proliferation and differentiation of cells. Our hypothesis is that these interactions are important for development during flatfish metamorphosis. Very little data exist on the topic of impaired eye migration. However, energy limitation, iodine deficiency and an unbalanced fatty acid composition have been proposed as possible explanations. Here, we review the literature on development of pigment cells and the possible mechanisms behind the effects of vitamin A, fatty acids and thyroid hormone on pigmentation and eye migration during development of Atlantic halibut larvae.  相似文献   

13.
Juvenile Atlantic halibut (Hippoglossus hippoglossus L.) and turbot (Scophthalmus maximus L.) acclimated to 8–9 °C sea water were transferred to sea water at 1 °C for 7 days. An immediate spasm-like response was noticed in the turbot after the transfer, but not in the halibut. None of the fish died. The turbot suffered from substantial physiological disturbances after the transfer. Their blood plasma Cl– concentration increased and muscle water content decreased markedly. The plasma glucose concentration was several times higher than the control level from day one onwards. A decrease in the haematocrit was recorded some hours after transfer, followed by a marked increase on day 7. In halibut, the plasma Cl– concentration fell somewhat during the first days, but returned thereafter to its pretransfer level. The muscle water content was unchanged. Both haematocrit and plasma glucose concentration were unchanged until day 7, when both were significantly higher. The differences in the response to low-temperature challenge between halibut and turbot are probably related to genetic differences in temperature tolerance, which reflect differences in the distribution of the species.  相似文献   

14.
Folate mobilization from the yolk compartment during larval development was studied by analysing the folate concentration in whole body, embryo and yolk in a single batch of Atlantic halibut, Hippoglossus hippoglossus L., eggs and larvae that showed successful fertilization and development. There was a net loss of approx. 50% of folate from yolk during endogenous feeding. Further, only 23% of the decrease in yolk folate was retained in the larval body. The data suggest a need for folate for metabolic and growth purposes during embryogenesis of approximately 2 μg g?1 weight gain. Relative to these data and published folate requirement for cold‐water species, batches of egg from 16 Atlantic halibut brood fish contained variable and, for some batches, critically low levels of folate. This may constitute a potential problem for larval development until start feeding.  相似文献   

15.
Decrease in the quality and quantity of Atlantic halibut, Hippoglossus hippoglossus L., semen towards the end of the reproductive season hampers production of good-quality embryos. Therefore, cryopreservation of spermatozoa is a method showing potential to facilitate controlled reproduction in Atlantic halibut. The present study aimed at establishing the appropriate cryopreservation procedure. We tested 20 extenders composed of four various diluents and five cryoprotectants (DMSO, DMA, methanol, propylene glycol, and glycerol) to determine the best extender. Then, we examined cryopreservation quality using various methods of loading and various volumes of cryopreserved samples. In most of the tested variants, sperm diluted with an extender showed high motility after 24-h incubation despite the high osmotic pressure of the extender. Modified turbot extender (MTE) was the best of the tested diluents, securing the highest post-thaw motility (P < 0.05), and DMSO, DMA, and methanol were the best cryoprotectants (P < 0.05). There was no significant effect of 15-min equilibration of semen in MTE-based extenders prior to freezing on post-thaw motility (P > 0.05). MTE-based extender was chosen as the most suitable. Semen cryopreserved in straws, Eppendorfs or Ziploc bags in volumes ranging from 0.25 to 20 ml showed similar high fertilization ability. Survival of larvae produced with the cryopreserved sperm did not differ from controls produced with freshly collected sperm. Motility 3 h after thawing was high but depended on the type of cryoprotectant and the volume of cryopreserved sperm (P < 0.05). The developed cryopreservation procedure has been applied at our Atlantic halibut breeding station for seed production.  相似文献   

16.
An egg incubator system specially designed to meet the requirements of Atlantic halibut, Hippoglossus hippoglossus L., eggs is described. Compared to other pelagic marine fish eggs, halibut eggs are frequently found to be heavy and lacking in buoyancy in seawater incubators. The biological features of halibut eggs which explain the choice of system design are discussed. In addition to the biological requirements, the system described is designed to meet the demands of commercial hatcheries where handling of large egg masses with a minimum of labour is needed. The incubation method has proved by experience to give high survival rates throughout egg development.  相似文献   

17.
Four experiments were conducted to investigate the effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus L. Fish (22–75 g) fed three (3 ×) or five times per day (5 × day?1) under constant light and temperature (13±1°C) consumed significantly more feed than fish fed 1 × day?1 but by the end of the experiment only fish fed 5 × day?1 were heavier and had greater specific growth rates (SGR). Under simulated winter conditions (9L:15D, 5±1°C), halibut (～300 g) fed every other day consumed more feed, had a greater SGR and final weight compared with fish fed every third day. Feed conversion ratios were not different among treatment groups in any of the experiments. These results suggest that growth rates may be improved by feeding juvenile halibut more than 1 × day?1.  相似文献   

18.
The effects of incubation salinity on survival and morphological development of yolk sac larvae of Atlantic halibut, Hippoglossus hippoglossus (L.), were studied at two salinities, 35.5%o and 32.3%o. Yolk sac larvae incubated at 35.5%o developed early tail deformities before 50 day-degrees (9 days post-hatch), and necrosis, oedema and calculus in the urinary bladder at about 150 day-degrees (28 days post-hatch). However, the incidence and severity of mouth deformity was not influenced by salinity. The cumulative mortality up to first feeding was 17% when the larvae were incubated at 3 5.5%o compared to 7% at 32.3%o. A broad variation between the different larval groups was noted in the extent of injuries induced by the higher salinity. Therefore, salinity must be considered as a critical environmental parameter for the yolk sac larvae of Atlantic halibut in aquaculture.  相似文献   

19.
Lipid classes, fatty acids, free amino acidsand protein content in captive Atlantic halibut(Hippoglossus hippoglossus) eggs weremeasured to investigate the changes in thebiochemical composition of eggs and larvae inboth the embryonic and early larval stages.Total free amino acids decreased continuously(p < 0.01) over the embryonic and larval stagesinvestigated. Triacylglycerol was significantlygreater at hatch than at all other stages(p < 0.05). When hatching occurred, there wasalso a significant increase in all phospholipidclasses. It is suggested that free amino acidsmay be the source of carbon skeletons for lipidsynthesis at hatching.  相似文献   

20.
The effect of extended photoperiods on growth and age at first maturity was investigated in 166 (79 females and 87 males) individually tagged Atlantic halibut Hippoglossus hippoglossus and in 114 (50 females and 64 males) individually tagged turbot Scophthalmus maximus. The halibut were reared at 11 °C on four different light regimes from 10 February to 6 July 1996: simulated natural photoperiod, (LDN), continuous light (LD24:0), constant 8 h light and 16 h darkness (LD8:16) and LD8:16 switched to continuous light 4 May 1996 (LD8:16–24:0). From 6 July 1996 to 9 February 1998 the LD24:0 and LD8:16–24:0 were reared together under continuous light and the LDN and LD8:16 together under natural photoperiod. The turbot were reared at 16 °C on three different light regimes: constant light (LD24:0), 16 h light:8 h darkness (LD16:8), or simulated natural photoperiod (LDN). After 6 months on the different photoperiods, the turbot was reared together on LDN for approximately 12 months until first maturation. Juveniles subjected to continuous light (halibut) or extended photoperiods (halibut and turbot) exhibited faster growth than those experiencing a natural photoperiod or a constant short day. Moreover, when the photoperiod increased naturally with day-length or when fish were abruptly switched from being reared on short-day conditions to continuous light, a subsequent increase in growth rate was observed. This growth enhancing effect of extended photoperiods was more apparent on a short time scale in Atlantic halibut than in turbot, but both species show significant long-term effects of extended photoperiods in the form of enhanced growth. In both species lower maturation of males was seen in groups exposed to extended or continuous light compared to LDN and this could be used to reduce precocious maturation in males leading to overall increase in somatic growth. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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