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1.
Atlantic halibut larvae were fed Artemia enriched with two different oil emulsions (cod liver oil and 2050TG) from first feeding to 70 days after first-feeding (dpff). Larvae fed 2050TG enriched Artemia had better growth, survival and eye migration than larvae fed the cod liver oil enriched Artemia, while pigmentation rate was similar in the two groups. In addition to the difference in fatty acids, the two emulsions differed in lipid class composition, since 2050TG is a synthetic oil and a mixture of mono-, di- and tri-acylglycerol, while cod liver oil is a tri-acylglycerol. Total lipid level, estimated as fatty acid methyl esters (FAME) was similar in the two Artemia types, but sum of n-6 and n-3 fatty acids, arachidonic acid (20:4n-6, ARA), docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) were higher in Artemia enriched with 2050TG than in the cod liver oil enriched Artemia. However, the main difference in fatty acid composition in the larvae, was a higher DHA (% of total fatty acids) in 2050TG larvae than in cod liver oil larvae. The lipid level measured as FAME was up to four times higher in the 2050TG larvae than in the cod liver oil larvae, and the reason for this may have been a better bioavailability of the partly digested lipid in the 2050TG emulsion. The correlation between a high level of lipid in the larval tissues (e.g. high energy status) and improved eye migration in larvae fed the 2050TG enriched Artemia supports the hypothesis that energy limitation on the larval stage may be a cause of the impaired eye migration commonly observed in farmed Atlantic halibut juveniles. 相似文献
2.
Land-cover and structural changes in a western Norwegian cultural landscape since 1865, based on an old cadastral map and a field survey 总被引：4，自引：2，他引：4
Liv Norunn Hamre Stein Tage Domaas Ingvild Austad Knut Rydgren 《Landscape Ecology》2007,22(10):1563-1574
Many studies of land-cover and structural changes in cultural landscapes have used historical maps as a source for information
about past land-cover. All transformations of historical maps onto modern coordinate systems are however burdened with difficulties
when it comes to accuracy. We show that a detailed land survey of the present landscape may enable transformation of an old
cadastral map directly onto the present terrain with very high accuracy. The detailed resulting map enabled us to locate remnants
of semi-natural grasslands and man-made structures with continuity from 1865 and to test hypotheses about relationships between
landscape changes and landscape characteristics. The main land-cover change 1865–2002 was decrease of arable fields, and addition
of three new land-cover classes: horticultural, orchard and abandoned areas. Of the 330 man-made structures present in 1865,
only 58 remained in 2002, while 63 new structures had been built after 1865. We found that semi-natural grasslands with continuity
since 1865 were situated on ground with significantly lower production capacity than mean 1865 production capacity. The man-made
structures with continuity since 1865 were also associated with areas with significantly lower production capacity than the
1865 mean, situated in significantly steeper terrain but not further from the hamlet. Our study illustrates the potential
of digitised and accurately transformed historical cadastral maps combined with detailed field surveys for analysis of land-cover
and structural changes in the cultural landscape. 相似文献
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4.
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
5.
The duration of efficacy of emamectin benzoate in the control of Caligus curtus infestations in Atlantic cod, Gadus morhua L., was studied following an administration of 50 μg kg?1 for seven consecutive days. No lice were found on medicated fish when challenged 1 week (challenge 1) or 5 weeks (challenge 2) following termination of medication, whereas the mean abundance of lice among the unmedicated fish was 17.9 and 19.3 lice per fish in challenge 1 and 2, respectively. Muscle concentrations of 19.5 ± 8.2 ng g?1 and 3.4 ± 0.9 ng g?1, respectively, and skin concentrations of 23.1 ± 10.8 and 4.2 ± 1.0 ng g?1, respectively, were found 27 and 55 days following the termination of medication. Tissue concentrations and the duration of efficacy indicate a dosing regime for emamectin in cod, similar to the regime used for Atlantic salmon, Salmo salar L. 相似文献
6.
Minimum requirement of vitamin E for Atlantic salmon, Salmo salar L., at first feeding 总被引：1，自引：0，他引：1
The minimum requirement of vitamin E for Atlantic salmon, Salmo salar L., at first feeding was found to be 60 mg dl-α-tocopheryl acetate per kg dry diet. The dry diet contained 5.6% polyunsaturated fatty acids, which is similar to that used in practical diets at first feeding. Preliminary results indicate that the optimal dietary vitamin E level is 120 mg dl-α-tocopheryl acetate per kg dry diet, or more. Further research is necessary to confirm this hypothesis. 相似文献
7.
Rotifers enriched with iodine,copper and manganese had no effect on larval cod (Gadus morhua) growth,mineral status or redox system gene mRNA levels 
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下载免费PDF全文 Sam Penglase Kristin Hamre Pål A Olsvik Espen Grøtan Andreas Nordgreen 《Aquaculture Research》2015,46(8):1793-1800
It currently remains unclear if rotifers contain sufficient mineral levels to meet larval fish requirements. In this study, rotifers were enriched with a commercial enrichment (control), or with additional iodine, iodine and copper, or iodine, copper and manganese, and the effects of feeding these rotifers to Atlantic cod (Gadus morhua) larvae from 3 to 18 days post hatch were investigated. Rotifer enrichment with minerals was successful, but Mn enrichment also increased rotifer zinc levels. No differences were observed between treatments in larval growth or survival, or in the mRNA levels in the majority of the redox system genes analysed. Only Zn levels increased in cod larvae in response to mineral enrichment of rotifers. Apart from Zn, little evidence was found to suggest that cod larvae require increased concentrations above the control rotifer levels of the essential elements studied here. 相似文献
8.
Effect of induced hyperoxia on the antioxidant status of Atlantic salmon Salmo salar L. fed three different levels of dietary vitamin E 总被引：4，自引：0，他引：4
Atlantic salmon smolt (64 g) were fed 40, 300 or 1100 mg kg?1 all‐rac‐α‐tocopheryl acetate feed under normoxic and moderate hyperoxic conditions for 12 weeks. After 7 weeks, however, the hyperoxic fish were subjected to a temporary severe supersaturation of dissolved oxygen with development of gas bubble disease and substantial mortality as a result. Liver α‐tocopherol (α‐TOH) levels reflected the dietary input after 6 and 12 weeks of feeding. Increased levels of thiobarbituric‐reactive substances (TBARS) in the liver of hyperoxygenated fish after 6 weeks indicate that moderate hyperoxic conditions may represent an oxidative challenge to the fish. After 12 weeks, liver ascorbic acid (AA) content was reduced in hyperoxygenated fish, and a decreasing tendency was also found in the liver content of α‐TOH. Effects of oxygen supersaturation were also observed on liver antioxidant enzyme activities, content of glutathione and total mercapthans in liver, phagocytic chemiluminescent response and total plasma protein level, indicating a disturbed redox balance. No effects of dietary vitamin E were observed on any of the measured parameters, indicating that high levels of dietary vitamin E under these circumstances did not protect the fish against oxidative stress. 相似文献
9.
The objective of this study was to examine the biochemical composition of intensively reared rotifers after enrichment with three commonly used enrichment media, Multigain, Ori‐Green and DHA‐enriched freshwater algae Chlorella, using standard enrichment protocols at a local cod larvae producer and compare it with that of natural zooplankton from Lofilab AS, a cod larvae producer using semi‐intensive rearing techniques. Unenriched rotifers were analysed to examine whether the enrichment procedures were successful in increasing the content of essential nutrients to level requirements for marine fish larvae. Neither total lipids nor proteins were affected by enrichment. Unenriched rotifers were significantly lower in highly unsaturated fatty acids (HUFAs) and significantly higher in linoleic acid (LA, C18:2, n‐6), than were zooplankton. Enrichment with Chlorella and Multigain increased the HUFAs significantly, while they were slightly reduced after enrichment with Ori‐Green. Total amino acids and mineral content were unaffected by enrichment. Zooplankton was rich in taurine and selenium, whereas rotifers were devoid of it, both prior to and after enrichment. Using zooplankton as a reference for the nutritional requirements of marine fish larvae, results from this study demonstrate that enrichment media currently in use are not effective for enhancing the nutritional quality of rotifers. 相似文献
10.
Kristin Hamre Marit Bjrnevik Marit Espe Luis E. C. Conceio Johan Johansen Joana Silva Marie Hillestad Antony J. Prabhu John F. Taylor Douglas R. Tocher Erik‐Jan Lock Gro‐Ingunn Hemre 《Aquaculture Nutrition》2020,26(3):936-945
During the past 20 years, plant ingredients have taken over as the main constituents in feed for Atlantic salmon. This has changed the nutrient composition of the feeds, the bioavailability of nutrients and perhaps nutrient metabolism. Plant‐based diets also contain more anti‐nutrients. The EU‐funded project ARRAINA re‐evaluated recommendations for micronutrient supplementation to Atlantic salmon feeds, and the present study compared a diet supplemented with micronutrients according to NRC (2011) (control diet, 100% NP (nutrient package)) with a diet supplemented according to the new recommendations (New NP). Tissue concentrations of pyridoxine, pantothenic acid, niacin, vitamin C, Zn and Se were significantly higher; and Cu was lower in Atlantic salmon fed the diet with the New NP compared to the control fish. The New NP also gave a near significant effect on growth, decreased muscle firmness and increased muscle cell size, and it affected metabolism of nitrogen‐containing metabolites in the muscle. While we cannot be certain which micronutrient(s) gave these effects, the B vitamins are probable candidates, since they are mediators of intermediary metabolism and have been shown to influence some of the affected metabolites. 相似文献