The response to substitution of soybean with faba bean protein concentrate on hepatic transcriptome of Atlantic salmon (Salmo salar)
ABSTRACT: The production of carnivorous fish such as Atlantic salmon (Salmo salar) is dependent on the availability of high quality protein required as a sustainable substitute for the formulation of the feeds. Plants have arguably the greatest potential, however a major limitation is associated with the presence of anti-nutritional factors. Investigating novel raw materials involves understanding the physiological consequences of the substitution. The primary aim of the present study was to assess the metabolic response of salmon to increasing inclusion of air-classified faba bean protein concentrate (BPC) in feeds as a replacement for soy (SPC). Specifically, we focused on the hepatic transcriptome response to dietary BPC inclusion over a range including commercially relevant levels (e.g. 11-22%) to levels giving impaired performance (45 %). The present investigation provided a profile of the salmon hepatic response to BPC indicating that fish tolerated moderate substitution of dietary SPC with BPC with no evident negative effects on the hepatic physiology of the fish. The analysis of extreme levels of substitution provided insights into physiological mechanisms that are significantly altered providing the basis for further investigation and improvement.
Project description:High-quality sources of protein for the formulation of feeds of carnivorous fish species such as Atlantic salmon are currently being sought. In an earlier screening trial we evaluated for the first time in Atlantic salmon (Salmo salar) the applicability of air-classified faba bean (Vicia faba) protein concentrate (BPC) inclusions in combination with soy protein concentrate (SPC) and fishmeal (FM) using parr as a model. Based on the results in parr in freshwater, the present study tested the hypothesis that BPC can effectively replace SPC as a dietary protein source in post-smolt Atlantic salmon in seawater. Herein we compare three dietary treatments, including BPC0 (no BPC), BPC20 (20% BPC) and BPC40 (40% BPC). Full details on diet formulation are available in the publication.
Project description:The present study aimed to determine the impact of dietary docosahexaenoic acid (DHA) on the metabolism of Atlantic salmon (Salmo salar). The effects of diets containing increasing levels of DHA (1 g kg-1, 5 g kg-1, 10 g kg-1, 15 g kg-1 and 20 g kg-1) on the liver transcriptome of post-smolt salmon was determined using regression analysis to elucidate patterns of gene expression and responses of specific metabolic pathways. Total RNA was isolated from liver of individual fish and analyzed using a custom 44K Atlantic salmon oligo-microarray. The expression of up to 911 unique annotated genes was significantly affected by dietary DHA inclusion relative to a low DHA reference diet. Using regression analysis, 797 unique genes were found with a significant linear correlation between expression level and dietary DHA. Gene-Set Enrichment Analysis (GSEA) identified a range of pathways that were significantly affected by dietary DHA content. Pathways that showed a significant response to dietary DHA level included those for long-chain polyunsaturated fatty acid biosynthesis, fatty acid elongation, steroid biosynthesis, glycan biosynthesis, protein export and protein processing in the endoplasmic reticulum. These findings suggest that in addition to clear roles in influencing lipid metabolic pathways, DHA also has key functional roles in other biosynthetic pathways distinct from lipid metabolism.
Project description:In the present study, a faba bean protein isolate (wBPC) with almost ~80 % crude protein produced by a wet process was investigated in feeds for Atlantic salmon in seawater. Four dietary treatments were tested including one treatment with high inclusion of fishmeal (400 g kg-1, named FM) and three treatments with low fishmeal (216 g kg-1) and increasing inclusions of faba bean protein concentrate (0, 70 and 140 g kg-1) substituting soy protein concentrate (236, 125 and 45 g kg-1), named SPC, BPC7 and BPC14 respectively.
Project description:The inclusion of intact phospholipids in the diet is essential during larval development and can improve culture performance of many fish species. The effects of supplementation of dietary phospholipid from marine (krill) or plant (soy lecithin) sources were investigated in Atlantic salmon, Salmo salar. First feeding fry were fed diets containing either krill oil supplying phospholipid at 2.6% of diet (named K2.6) or soybean lecithin supplying phospholipid at 2.6 % (S2.6), 3.6 % (S3.6) of diet. A control diet (B) without supplemented phospholipid was also supplied. Fish were sampled at ~ 2.5 g (~1990 ˚ day post fertilization, dpf) and ~10 g (2850 ˚dpf). By comparison of the intestinal transcriptome in specifically chosen contrasts, it was determined that by 2850˚dpf fish possessed a profile that resembled that of mature and differentiated intestinal cell types with a number of changes specific to glycerophospholipid metabolism. It was shown that intact phospholipids and particularly phosphatidylcholine are essential during larval development and that this requirement is associated with the inability of enterocytes in young fry to endogenously synthesize sufficient phospholipid for the efficient export of dietary lipid. In the immature phase (~1990 ˚dpf), the dietary phospholipid content as well as its class composition impacted on several biochemical and morphological parameters including growth, but these differences were not associated with differences in intestinal transcriptomes. The results of this study have made an important contribution to our understanding of the mechanisms associated with lipid transport and phospholipid biosynthesis in early life stages of fish.
Project description:Current commercially available feeds for salmon are predominantly made of plant ingredients, with consequent changes to the composition and contents of a range of nutrients and other components in the diet. There are concerns that, with these major changes in raw materials, new feeds will affect not only the composition and contents of nutrients, but also the bioavailability and, combined with the limited knowledge of micronutrient requirements for Atlantic salmon, this might impact growth performance and health of the fish. The present study investigated the effects of graded levels of a micronutrient package supplemented to feeds formulated with low levels of marine ingredients and fed to diploid and triploid Atlantic salmon throughout the freshwater phase. Specifically, fish were fed three diets containing low levels of FM and FO and identical in formulation other than being supplemented with 3 levels (L1, 100 %; L2, 200 % and L3, 400 %) of a micronutrient mix formulated as a modification of current nutrient levels reported for salmon. Duplicate groups of diploid and triploid parr were fed the experimental diets from around 30 g to seawater transfer and the effects on growth performance, feed efficiency, biochemical composition, liver histology, hepatic gene expression (transcriptome) and smoltification efficiency determined. Microarray analysis revealed that the hepatic transcriptome profile of diploid fish fed diet L2 was more similar to that observed in triploids fed diet L3 than to those fed L2, suggesting that micronutrient requirements of triploid salmon may differ from levels accepted in diploid salmon. Different levels of micronutrient supplementation affected the expression of key genes involved in lipid metabolism. In particular sterol biosynthesis pathways (steroid and terpenoid backbone synthesis) were down-regulated in both L2-fed diploids and L3-fed triploids when compared with diet L1-fed diploids and triploids, respectively. Gene sets analysis showed an up-regulation of genes involved in immune processes in triploid salmon fed diet L3. Another biological category affected by diet in triploid salmon was genetic information processing. In fish fed diet L3 down-regulation of RNA degradation, proteasome, RNA polymerase, spliceosome and ribosome was observed, suggesting a decrease in protein turnover in this group, which may indicate a decrease in energy expenditure. In addition, one-carbon metabolism was affected by diet in diploid and triploid salmon.
Project description:Atlantic salmon (Salmo salar) has been selectively bred in Europe since the 1970s and the process of domestication has led to both phenotypic and genotypic differences between wild and farmed fish. Despite strict regulations large numbers of fish escape annually from fish farms, a concern for both aquaculturalists and those managing wild fish stocks. A better understanding of the interactions between domesticated and wild salmon is essential to the continued sustainability of the aquaculture industry and to the maintenance of healthy wild stocks. One major concern is that of potential interbreeding of escapees with wild fish leading to potentially detrimental genetic changes in wild populations. Advances in high throughput technologies allow the role of genome-wide gene transcription to be studied in relation to both micro- and macro- evolutionary change. In this study, we have compared the transcriptomes of Norwegian wild and domesticated stocks at two life stages: yolk sac and first-feeding salmon fry and reared under identical conditions. These preliminary data improve knowledge of potential transcriptional difference between domesticated and wild salmon and will hopefully provide a better understanding of the fitness consequences of such interactions.
Project description:The aim of the present study was to generate an experimental model to characterize the nutrigenomic profile of a plant-derived nutritional stress (S30 = 300 g Kg-1 Soybean Meal). Our results provided: a) a snapshot of molecular signatures describing a chronic and advanced nutritional stress to which future nutrigenomic studies might refer to; and b) a platform for the identification of candidate genes for the molecular phenotyping of several physiological parameters in liver and distal intestine. Atlantic salmon was used as a model. The nutritional stress was induced by inclusions of dietary defatted soybean meal (SBM) up to a level of 300 g kg-1, being this ingredient extensively demonstrated to induce reduced performance and enteropathy in the distal intestine (Baeverfjord and Krogdahl, 1996;Urán et al., 2009;URÁN et al., 2008). A control treatment with no SBM (S0) as well as intermediate levels of inclusion (100 g kg-1 and 200 g kg-1 SBM) were included to span a range of optimal and sub-optimal conditions. Performance parameters were measured and impaired growth was taken as an indicator of pronounced and chronic nutritional stress. Molecular analyses were performed in two tissues, liver and distal intestine. Distal intestine was chosen for being the site most morphologically and physiologically affected during the development of intestinal pathologies associated with plant ingredients such as SBM (Baeverfjord and Krogdahl, 1996;Kortner et al., 2011), while liver for being arguably the most metabolic active tissue. These tissues have been the most investigated targets in nutritional studies on fish so far. To the best of our knowledge, this study is the most comprehensive of its kind to report on the transcriptomic profile of the distal intestine and the liver, hence highlighting the supporting role of this tissue, in fish undergoing SBM-induced nutritional stress. Skugor et al (, 2011) described gene expression profiles of liver and intestine in fish fed 200 g kg-1 SBM inclusion using a 11K trout array. By investigating a larger number of probes (44K) in a more severe nutritional stress (300 g kg-1), our work will add further nutrigenomic information to the current literature.
Project description:A common-garden experiment was carried out to compare two genetically distinct strains of Atlantic salmon (Salmo salar) fed diets formulated with either high (CHO) or low (NoCHO) carbohydrate (starch). Twenty salmon from either a commercial farmed strain or a land-locked population were placed in two tanks (10 fish of each population in each tank) and fed either CHO or NoCHO feeds for 32 days. At the end of the experimental period fish were fasted for 8 h, euthanized and samples of blood and liver collected. Both diet and population had an effect on circulating glucose levels with land-locked salmon showing hypoglycaemia and dietary starch increasing this parameter. In contrast, land-locked salmon showed increased plasma triacylglycerol levels regardless of dietary treatment. This enhanced ability to metabolise dietary starch in land-locked compared to farmed salmon stock was also reflected at a molecular (gene) level as most of the metabolic pathways evaluated in the present study were mainly affected by the factor population rather than by diet. In particular, lower expression of genes for mitochondrial metabolism in land-locked salmon reflects drastic differences in energy metabolism between the populations. The liver transcriptome analysis highlighted some new gene candidates such as elovl6 to evaluate in future studies assessing the capacity of salmonids to cope with feeds containing higher levels of dietary starch.
Project description:This study compared the transcriptome of salmon fed diets with different levels and/or composition of LC_PUFA. Feeds were formulated with either DHA (Docosahexaenoic acid) alone (either 1% of the diet or 2% of the diet) or with a combination of DHA and EPA (Eicosapentaenoic acid) or DHA and ARA (Arachidonic acid). NOTE: Two treatments used in this trial (1% DHA and 2% DHA) were also used in an experiment previously submitted (E-MTAB-3180). Specifically, arrays 62_3, 69_1, 67_1, 62_2, 70_4, 65_2, 76_4, 66_3, 73_3, 70_2.
Project description:The natural food for Atlantic salmon (Salmo salar) in freshwater has relatively lower levels of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) than found in prey for post-smolt salmon in seawater. Land-locked salmon such as the Gullspång population feed exclusively on freshwater type lipids during its entire life cycle, a successful adaptation derived from divergent evolution. Studying land-locked populations may provide insights into the molecular and genetic control mechanisms that determine and regulate n-3 LC-PUFA biosynthesis and retention in Atlantic salmon. A two factorial study was performed comparing land-locked and farmed salmon parr fed diets formulated with fish or rapeseed oil for 8 weeks. The land-locked parr had higher capacity to synthesise n-3 LC-PUFA as indicated by higher expression and activity of desaturase and elongase enzymes. The data suggested that the land-locked salmon had reduced sensitivity to dietary fatty acid composition and that dietary docosahexaenoic acid (DHA) did not appear to suppress expression of LC-PUFA biosynthetic genes or activity of the biosynthesis pathway, probably an evolutionary adaptation to a natural diet lower in DHA. Increased biosynthetic activity did not translate to enhanced n-3 LC-PUFA contents in the flesh and diet was the only factor affecting this parameter. Additionally, high lipogenic and glycolytic potentials were found in land-locked salmon, together with decreased lipolysis which in turn could indicate increased use of carbohydrates as an energy source and a sparing of lipid.