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Ekmann K.S.,Technical University of Denmark | Dalsgaard J.,Technical University of Denmark | Holm J.,BioMar A S | Campbell P.J.,BioMar Ltd | Skov P.V.,Technical University of Denmark
British Journal of Nutrition | Year: 2013

The effects of replacing a digestible energy source from fat (fish oil) with carbohydrate (wheat starch) on performance, glycogenesis and de novo lipogenesis was examined in triplicate groups of juvenile gilthead sea bream (Sparus aurata), fed four extruded experimental diets. In order to trace the metabolic fate of dietary starch, 0·7 % wheat starch was replaced with isotope-labelled starch (>98 % 13C). Fish were fed the experimental diets for three consecutive 10 d periods, and isotope ratio MS was applied to quantify 13C enrichment of liver and whole-body glycogen and lipid pools over the three feeding periods. Glycogenesis originating from dietary starch accounted for up to 68·8 and 38·8 % of the liver and whole-body glycogen pools, respectively, while up to 16·7 % of the liver lipid could be attributed to dietary starch. Between 5 and 8 % of dietary starch carbon was recovered in whole-body lipid, and estimated deposition rates of de novo synthesised lipid originating from starch ranged from 18·7 to 123·7 mg/kg biomass per d. Dietary treatments did not significantly affect growth, feed performance or body composition of the fish, while the hepatosomatic index and glycogen content of whole fish and livers correlated directly with dietary starch inclusion level. The study suggests that gilthead sea bream efficiently synthesises glycogen from both dietary starch and endogenous sources. In contrast, lipogenesis from carbon derived from starch seems to play a minor role in overall lipid synthesis and deposition under the specified experimental conditions. © 2012 The Authors.

Micallef G.,University of Aberdeen | Bickerdike R.,BioMar Ltd | Reiff C.,University of Aberdeen | Fernandes J.M.O.,University of Nordland | And 2 more authors.
Marine Biotechnology | Year: 2012

The skin of fish is the first line of defense against pathogens and parasites. The skin transcriptome of the Atlantic salmon is poorly characterized, and currently only 2,089 expressed sequence tags (ESTs) out of a total of half a million sequences are generated from skin-derived cDNA libraries. The primary aim of this study was to enhance the transcriptomic knowledge of salmon skin by using next-generation sequencing (NGS) technology, namely the Roche-454 platform. An equimolar mixture of high-quality RNA from skin and epidermal samples of salmon reared in either freshwater or seawater was used for 454-sequencing. This technique yielded over 600,000 reads, which were assembled into 34,696 isotigs using Newbler. Of these isotigs, 12 % had not been sequenced in Atlantic salmon, hence representing previously unreported salmon mRNAs that can potentially be skin-specific. Many full-length genes have been acquired, representing numerous biological processes. Mucin proteins are the main structural component of mucus and we examined in greater detail the sequences we obtained for these genes. Several isotigs exhibited homology to mammalian mucins (MUC2, MUC5AC and MUC5B). Mucin mRNAs are generally >10 kbp and contain large repetitive units, which pose a challenge towards full-length sequence discovery. To date, we have not unearthed any full-length salmon mucin genes with this dataset, but have both N- and C-terminal regions of a mucin type 5. This highlights the fact that, while NGS is indeed a formidable tool for sequence data mining of non-model species, it must be complemented with additional experimental and bioinformatic work to characterize some mRNA sequences with complex features. © 2012 Springer Science+Business Media, LLC.

Betancor M.B.,University of Stirling | Sprague M.,University of Stirling | Sayanova O.,Rothamsted Research | Usher S.,Rothamsted Research | And 4 more authors.
Aquaculture | Year: 2015

Currently, one alternative for dietary fish oil (FO) in aquafeeds is vegetable oils (VO) that are devoid of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs). Entirely new sources of n-3 LC-PUFA such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids through de novo production are a potential solution to fill the gap between supply and demand of these important nutrients. Camelina sativa was metabolically engineered to produce a seed oil (ECO) with >. 20% EPA and its potential to substitute for FO in Atlantic salmon feeds was tested. Fish were fed with one of the three experimental diets containing FO, wild-type camelina oil (WCO) or ECO as the sole lipid sources for 7. weeks. Inclusion of ECO did not affect any of the performance parameters studied and enhanced apparent digestibility of individual n-6 and n-3 PUFA compared to dietary WCO. High levels of EPA were maintained in brain, liver and intestine (pyloric caeca), and levels of DPA and DHA were increased in liver and intestine of fish fed ECO compared to fish fed WCO likely due to increased LC-PUFA biosynthesis based on up-regulation of the genes. Fish fed ECO showed slight lipid accumulation within hepatocytes similar to that with WCO, although not significantly different to fish fed FO. The regulation of a small number of genes could be attributed to the specific effect of ECO (311 features) with metabolism being the most affected category. The EPA oil from transgenic Camelina (ECO) could be used as a substitute for FO, however it is a hybrid oil containing both FO (EPA) and VO (18:2n-6) fatty acid signatures that resulted in similarly mixed metabolic and physiological responses. © 2015.

Penn M.H.,Aquaculture Protein Center a CoE | Bendiksen E.A.,BioMar AS | Campbell P.,BioMar Ltd | Krogdahl A.S.,Aquaculture Protein Center a CoE
Aquaculture | Year: 2011

The current study investigated the effects of pea protein concentrate, soy protein concentrate and corn gluten, either singly at high inclusion, or in combination, each at lower inclusion, in diets for Atlantic salmon (Salmo salar L.). Growth performance, nutrient digestibility, intestinal brush border enzyme activity, and intestinal histology were studied in an 8-week feeding trial. Triplicate groups of Atlantic salmon (2.36kg initial weight) were kept in sea water at winter temperature. Five diets were tested, including a control diet based on fish meal (FM diet; 250gkg-1 fishmeal) and four low fishmeal (100gkg-1) diets: a diet containing 350gkg-1 pea protein concentrate (PPC diet), a diet containing 300gkg-1 soy protein concentrate (SPC diet), a diet containing 300gkg-1 corn gluten (CG diet) and a combination diet containing 130gkg-1 pea protein concentrate, 105gkg-1 soy protein concentrate and 105gkg-1 corn gluten (CMB diet). Fish fed CG and PPC diets showed lower SGR than fish fed the FM diet and there was a trend (P<0.09) towards a higher feed conversion (FCR) in the fish receiving the CG and PPC diets. Apparent fat digestibility was lower in fish fed SPC, PPC and CMB diets compared to FM. No difference in apparent crude protein digestibility was observed. Feeding the PPC diet resulted in reduced relative weight and inflammation in the distal intestine similar to those described for soy enteritis. Additionally, fish fed the PPC diet had reduced brush border enzyme activities in the distal intestine and increased trypsin activity in the digesta from the distal intestine region. In conclusion, pea protein concentrate at high inclusion was shown to induce an enteropathy in the distal intestine of Atlantic salmon and caution should be used when including it in formulated feeds for Atlantic salmon. © 2010 Elsevier B.V.

Lund I.,Technical University of Denmark | Dalsgaard J.,Technical University of Denmark | Rasmussen H.T.,Innovation Center Denmark | Holm J.,BioMar Ltd | Jokumsen A.,Technical University of Denmark
Aquaculture | Year: 2011

This study examined the effects on nutrient utilization and fish performance when replacing 16, 31, and 47% of fish meal protein (corresponding to replacing 15, 29 and 44%, respectively, of total dietary protein) with a fixed matrix of organic pea, horsebean and rapeseed plant protein concentrates (PPC) in a ratio of 1.07:1.00:0.66. Four iso-energetic and iso-nitrogenous diets were produced to include 0, 136, 274 or 410gkg-1 of the organic PPC matrix, respectively. The organic protein ingredients were chosen based on their high protein content, and the matrix was established to mirror the amino acid composition of fish meal. The plant ingredients were dried, dehulled, grinded and air classified in accordance with the European Union Commission Regulation on organic aquaculture production, increasing the protein concentrations up to 577gkg-1 dry matter. Two experiments were carried out using juvenile rainbow trout (Oncorhynchus mykiss): 1) a digestibility study to examine the apparent digestibility of protein, lipid, nitrogen-free extract (NFE), total phosphorus and phytate-phosphorus, followed by a water sampling period to determine the output of nitrogen and phosphorus and enabling the setup of nitrogen and phosphorus mass-balances; and 2) a 57day growth study including 3 growth periods each of 19days and using pit-tagged fish. Substituting fish meal with organic PPC significantly increased the apparent digestibility coefficient (ADC) of protein and lipid (P<0.008) at the highest PPC inclusion level, while there was a significant (P<0.044) decrease in the ADC of NFE with increasing PPC inclusion level. The apparent digestibility coefficient of phytate-phosphorus was significantly lower (P<0.005) at the highest PPC inclusion level compared to the fish meal control diet. The mass-balances revealed a significant increase in the excretion of ammonium-nitrogen (NH4N, P<0.017) at the two highest PPC inclusion levels and a decrease in phosphorus (P<0.009) excretion at the highest organic PPC inclusion level. There was no overall effect on the specific growth rates (SGRs) or feed conversion ratios (FCRs). The study thus demonstrated that it is possible to replace fish meal by 47% organic PPC without compromising rainbow trout performance. However, the results also indicated that it will be difficult to replace much more than this as long as supplementation with synthetic amino acids and exogenous phytase is not allowed in organic feed. © 2011 Elsevier B.V.

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