Dietary supplementation to a plant-based diet for Atlantic salmon
Ontology highlight
ABSTRACT: The study evaluated effects of dietary cholesterol (CH), taurocholate (TC), choline (CN) and taurine (TA) in Atlantic salmon fed a plant based diet for 77 days. The additives did not affect growth or organ weights of Atlantic salmon, but promoted induction of cholesterol and plant sterol efflux in the intestine, whereas sterol uptake was suppressed. Microarray analyses in the liver indicated decreased cholesterol biosynthesis and enhanced conversion to bile acids. The marked effect of cholesterol on bile acid synthesis suggests that dietary cholesterol can be used to stimulate bile acid synthesis in fish. The study clearly demonstrated how Atlantic salmon adjusted metabolic functions in response to the dietary load of cholesterol, and has expanded our understanding of sterol metabolism and turnover that adds to the knowledge of these processes in fish. Feed supplementation with choline improved lipid absorption and suppressed abnormal accumulation of fat in the gut.
Project description:The study evaluated effects of dietary cholesterol (1.5%) in Atlantic salmon fed a plant based diet for 77 days. Cholesterol supplementation did not affect growth or organ weights of Atlantic salmon, but promoted induction of cholesterol and plant sterol efflux in the intestine, whereas sterol uptake was suppressed. Microarray analyses in the liver indicated decreased cholesterol biosynthesis and enhanced conversion to bile acids. The marked effect of cholesterol on bile acid synthesis suggests that dietary cholesterol can be used to stimulate bile acid synthesis in fish. The study clearly demonstrated how Atlantic salmon adjusted metabolic functions in response to the dietary load of cholesterol, and has expanded our understanding of sterol metabolism and turnover that adds to the knowledge of these processes in fish. Atlantic salmon received feeds based on plant ingredients with (CH) and without (K) supplementation of cholesterol. Liver samples were collected after 77 days. Five individuals from each group were analyzed with microarrays, pooled liver sample of salmon fed with commerical fish meal based feed was used as a reference.
Project description:Screening has revealed that modern-day feeds used in Atlantic salmon aquaculture might contain trace amounts of agricultural pesticides. To reach slaughter size, salmon are produced in open net pens in the sea. Unconsumed feed pellets and undigested feces deposited beneath the net pens represent a source of contamination for marine organisms. To examine the impacts of long-term and continuous dietary exposure to an organophosphorus pesticide (OP) found in Atlantic salmon feed, we fed juvenile Atlantic cod (Gadus morhua), an abundant species around North Atlantic fish farms, three concentrations (0.5, 4.2 and 23.2 mg/kg) of chlorpyrifos-methyl (CPM) for 30 days. Endpoints included liver and bile bioaccumulation, liver transcriptomics and metabolomics, as well as plasma cholinesterase activity, cortisol, liver 7-ethoxyresor-ufin-O-deethylase (EROD) activity and hypoxia tolerance. The results show that Atlantic cod can accumulate relatively high levels of CPM in the liver after continuous exposure, which is then metabolized and excreted via the bile. All three exposure concentrations led to significant inhibition of plasma cholinesterase activity, the primary target of CPM. Transcriptomics profiling pointed to effects on cholesterol and steroid biosynthesis. Metabolite profiling revealed that CPM induced responses reflecting detoxification by glutathione-S-transferase, inhibition of monoacylglycerol lipase, potential inhibition of carboxylesterase, and increased demand for ATP, followed by secondary inflammatory responses. A gradual hypoxia challenge test showed that all groups of exposed fish were less tolerant to low oxygen saturation than the controls. In conclusion, this study suggests that wild fish continuously feeding on leftover pellets near fish farms over time may be vulnerable to OPs.
Project description:A study was conducted to determine if different levels of vegetable and fish oils can alter antiviral responses of salmon macrophage-like cells (MLCs). Atlantic salmon were fed diets containing 7.38% (FO7) or 5.09% (FO5) fish oil. These diets were designed to be relatively low in EPA+DHA (i.e. FO7: 1.41% and FO5: 1%), but near the requirement level, resulting in no significant change in salmon growth. After a 16-week feeding trial, macrophages isolated from fish in these dietary groups were stimulated by a viral mimic (dsRNA: pIC) or PBS (control) for 24 h. A 44K microarray experiment identified the diet-responsive transcripts between dietary treatments and pIC-responsive transcripts within each group.
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:Unintentional use of mold-infested plant-based feed ingredients are sources of mycotoxins in fish feeds. The presence of the emerging mycotoxins ENNB and BEA in Norwegian commercial fish feeds and plant-based feed ingredients has raised concerns regarding the health effects on farmed Atlantic salmon (Salmon salar). Atlantic salmon pre-smolts were exposed to a non-lethal single-dose of BEA and ENNB, and total RNA sequencing of the intestine and liver was carried out to evaluate gut health and identify possible hepatological changes after a single-dose dietary exposure. ENNB and BEA did not give acute toxicity, however ENNB caused the onset of pathways linked to acute intestinal inflammation and BEA exposures caused the onset of hepatic hematological disruption. The prevalence and concentration of ENNB found in today's commercial feed could affect the fish health if consumed over a longer time-period.
Project description:There is an increasing drive to replace fish oil (FO) in finfish aquaculture diets with vegetable oils (VO), driven by the short supply of FO derived from wild fish stocks. Little is known of the consequences for fish health after such substitution. The effect of dietary VO on hepatic gene expression was determined in Atlantic salmon (Salmo salar) byg a cDNA microarray analysis. Post-smolt farmed salmon were reared for x weeks on diets where the FO component of the feed was replaced with one of three different VOs - rapeseed (RO), soybean (SO) or linseed (LO). RNA from five fish fed on each diet was extracted. A total of 20 cDNA microarray hybridisations - TRAITS / SGP Atlantic salmon 17k feature cDNA microarray - were performed - 4 diets (three VO + FO control) x 5 individuals - using a common pooled reference control design. Data were obtained from 19 of the 20 hybridisations.
Project description:Atlantic salmon individuals were grown, from fresh water to salt water in tanks on diets with low fish meal (10%) and 1-1.25% total n-3 LC-PUFA levels. Dietary n-3 LC-PUFAs were supplemented by 1) fish oil (FO), 2) Schyzochytrium limacinum biomass (AA). Further, the fish from all treatments were mixed and redistributed in sea cages reared to slaughter (ca. 3kg body weight) on either FO or AA. Transcriptomics analyses in liver and intestinal tissues revealed significant dietary effects on the expression of immune modulating, as well as ion, lipid, protein and xenobiotic metabolism genes.
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:Transcriptomics ananlysis of olfactory organs of Atlantic salmon. Controls/untreated (C) fish were compared to fish that were exposed to low (L) or high (H) concentrations of hydrogen sulphide.
Project description:N-3 long chain polyunsaturated fatty acids (n-3LC-PUFA) are essential components of vertebrate membrane lipids and are now at critically low levels in modern Western diets. The main human dietary source for n-3LC-PUFA is fish and seafood, and over 50% of global fish production is currently supplied by aquaculture. However, increasing pressure to include vegetable oils, which are devoid of n-3LC-PUFA, in aquaculture feeds reduces their content in farmed fish flesh. The aim of this investigation was to infer mechanisms determining flesh n-3LC-PUFA content in Atlantic salmon. The TRAITS / SGP Atlantic salmon 17k feature cDNA microarray (ArrayExpress accession: A-MEXP-1790) was used to compare hepatic mRNA expression in 8 families, reared under common conditions, which exhibited contrasting high and low flesh n-3LC-PUFA levels at harvest. The microarray interrogations incorporated a common pooled reference design, comprising a total of 16 hybridisations (8 families x 2 - dye swap). Each family sample comprised RNA pooled from six sibs.