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... Instead, they closely resembled the fatty acid profile of the respective diet consumed, as commonly observed [4]. It is well known that the fatty acid composition of an animal depends not only on desaturation/elongation, but also on other interacting aspects of lipid metabolism such as b-oxidation, substrate availability, tissue uptake and hormonal status [4,42,57]. High levels of oxidation of C 18 PUFA, which subsequently allows only small proportions for bioconversion, can be one possible explanation [58]. The elevated CPT1b expression in the carbohydrate fed group coincides with this hypothesis. ...
... In previous studies, transcriptional analysis (after feeding fish oil based diets with or without carbohydrates to the two trout lines) demonstrated the higher potential of the F line in intestinal lipid uptake, hepatic de novo fatty acid synthesis (further enhanced by dietary carbohydrates) and fatty acid bioconversion in both liver and intestine [23,24]. We hypothesized that replacing fish oil with vegetable oil may augment this genetic potential of the F line because vegetable oil lacks n-3 LC-PUFA, the critical component in fish oil responsible for down regulating the genes encoding enzymes involved in lipogenesis and fatty acid bioconversion [54,57,63]. But contrary to our expectation, changing the dietary lipid source eliminated the genetic advantage of the F line in chylomicron synthesis, lipogenesis as well as fatty acid desaturation and elongation. ...
... Concerning the difference between the lines, we had hypothesised a further augmentation of the fatty acid bioconversion potential in F line under the vegetable oil based dietary regime as it lacks n-3 LC-PUFA, the critical component in fish oil responsible for down regulating the genes encoding enzymes involved in fatty acid bioconversion and lipogenesis Torstensen and Tocher, 2010). But in total contrast, we found that the previously observed higher fatty acid bioconversion potential of the F line disappeared under the vegetable oil based dietary regime. ...
Thesis
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The aim of the thesis was to characterise the differences in digestive and metabolic utilisation of dietary carbohydrates between two lines of rainbow trout divergently selected for muscle fat content (Fat-F and Lean-L), when fed diets with (20%) or without gelatinised starch. In both lines, starch intake did not adversely affect growth, resulted in a moderate postprandial hyperglycemia, enhanced protein/lipid retention and a distinct intracellular signalling pattern in the liver involving the energy sensor AMPK and nutrient sensor TOR-S6. No difference between the two lines was observed for the apparent digestibility of starch, the mRNA levels of genes encoding glucose transporters in the intestine, regulation of postprandial glycemia and utilisation of glucose in the peripheral tissues (muscle and adipose tissue). However when compared to the L line, the F line was characterised by lower growth and feed efficiency; better capacity to store excess glucose as indicated by higher glycogen levels and mRNA levels of lipogenic markers in the liver (with no impact on glucose homeostasis); and a specific lipid metabolism (a greater potential to synthesise chylomicrons and to bioconvert fatty acids, coupled with a lower potential to oxidise fatty acids). In a separate study, replacement of fish oil in the diet with a blend of vegetable oils was found to suppress most of the molecular differences previously observed between the two genotypes. Starch intake under the vegetable oil diet regime led to different metabolic changes in the intestine and liver, for example, elicited a higher transcriptional response of key desaturase and elongase enzymes in both lines. Overall, our data demonstrated the existence of significant metabolic differences between the two trout lines, but it did not lead to better utilisation of dietary carbohydrates. In addition, our work highlights the importance of diet composition in the growth and metabolic response of different genotypes of fish
... A vast amount of experiments are carried out over the last two decades in evaluating potential alternatives to fish meal and fish oils in diets for salmonids. The main focus has been on ingredients derived from either plant origin (Thomassen and Røsjø, 1989;Rosenlund, et al., 2001;Gatlin, et al., 2007;Hemre, et al., 2009;Gunstone, 2011), terrestrial animal origin (Bureau, et al., 1999;Turchini, et al., 2009), Krill, Amphipods and Copepods (Olsen, et al., 2010) or single cell organisms from bacterial meal (Øverland, et al., 2010), yeast and algae . The current plant protein ingredients being used by the Norwegian aquaculture industry include soybean meal, sunflower meal, pea protein concentrate, beans, wheat gluten and corn gluten. ...
... The main plant oil production has since 2005 been palm oil, with a current production of more than 40 million tons per year. Of the major oilseeds, soybean oil production amounted to 37.7, rapeseed oil to 19.4 and sunflower oil to 10.1 million tons in -2008(Gunstone, 2011 Figure 1 The world oil seed production in 2009 (Soystats, 2010) Figure 4 The world production of pulses (PulseCanada, 2007) 6 3 ...
... The nutritional value is thus affected by processing steps carried out in order to remove oil. Gunstone (2011). The main concerns related to using plant oils in fish feed are the lack of VLC n-3 fatty acids, and the high content, in some oils, of saturated fatty acids. ...
... LC-PUFA are important structural components of cell membranes (Marsh 2008) and also act as eicosanoid precursors (Villalta et al. 2008) and regulators of gene expression (Lengqvist et al. 2004; Leaver et al. 2008). As LC-PUFA are essential nutrients in fish, their biosynthesis and metabolic regulation have become increasingly important scientific topics in recent years (Tocher 2010; Torstensen & Tocher 2010). It is thought that in general, freshwater teleosts possess the capacity to synthesize LC-PUFA from C18 precursors such as a-linolenic (LNA, 18:3n-3) and linoleic (LA, 18:2n- 6) acids. ...
... In contrast, marine fish are generally assumed to have a limited capability or inability to synthesize LC-PUFA in vivo from their C18 precursors and hence have a strict dietary requirement for LC-PUFA (Sargent et al. 2002; Seiliez et al. 2003). The biosynthesis of LC-PUFA from LNA and LA requires a series of fatty acyl desaturase (Fad) and elongation of very long-chain fatty acids (Elovl) enzymes such as D6Fad, D5Fad, Elovl5 and Elovl2 (Torstensen & Tocher 2010). Difference or absence in the activity of enzymes in one or more steps of the pathway will result in differential LC-PUFA biosynthetic capability in fish. ...
Article
The present study aimed to characterize the influence of salinity on the biosynthesis of long-chain polyunsaturated fatty acid (LC-PUFA) in rabbitfish Siganus canaliculatus. An eight-week feeding trial was performed in rabbitfish juveniles with diets containing fish oil (FO) or a blend of vegetable oils (perilla and Canola oils, VO) at two salinities, 32 and 10 ppt. The whole-body fatty acid mass balance (FAMB) method was used to evaluate the in vivo LC-PUFA biosynthetic activities, and the hepatic mRNA levels of Δ4 and Δ6/Δ5 fatty acyl desaturases (Fad) and elongase of very long-chain fatty acids (Elovl5) genes were determined by real-time quantitative PCR. The results showed that the ex novo production of LC-PUFA in fish receiving the VO diet was significantly higher than fish fed the FO diet at both salinities. Furthermore, LC-PUFA production at 10 ppt salinity was significantly higher than that at 32 ppt salinity in the VO dietary groups, whereas no effect of salinity was found in the FO dietary groups. Consistent with this, the calculated apparent in vivo desaturation and elongation activities were also higher in VO and low-salinity treatments. In addition, higher levels of Δ4 and Δ6/Δ5 fads mRNA expression were obtained at low salinity, which was consistent with the calculated enzyme activities. In contrast, the expression of elovl5 was lower than that of fads, and the levels were not consistent with the elongase activity. The results suggest that ambient salinity may affect the activity of the LC-PUFA biosynthetic pathway in rabbitfish through regulating fatty acyl desaturase and elongase activities, partly through a transcriptional control mechanism in the case of desaturases.
... In order to corroborate our results, we also investigated the expression of two other genes (Δ6-desaturase and Elovl5) that have key roles in fatty acid bioconversion [62,63]. The up-regulation of Δ6-desaturase we found in intestine and liver of V-fed fish support the results of several studies in different fish species [64]. Moreover, they are consistent with the increased activity of the LC-PUFA pathway observed in rainbow trout hepatocytes and enterocytes in response to vegetable oils-based diets [64,65]. ...
... The up-regulation of Δ6-desaturase we found in intestine and liver of V-fed fish support the results of several studies in different fish species [64]. Moreover, they are consistent with the increased activity of the LC-PUFA pathway observed in rainbow trout hepatocytes and enterocytes in response to vegetable oils-based diets [64,65]. In addition, the increase in the quantities of EPA+DHA (g fish -1 ) we found from juveniles to ongrowing V-fed fish provides further evidence that rainbow trout have the capacity to synthesize LC-PUFA from dietary precursors. ...
Article
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The effects of replacing fishmeal and fish oil with a plant-based diet were studied in juvenile (10g) and ongrowing (250-350g) rainbow trout from first-feeding. Feed-related differences in the intestinal and hepatic transcriptome were examined in juveniles after 7 months of feeding at 7°C. Based on microarray results obtained for juveniles, the expression of selected genes related to lipid, cholesterol and energy metabolisms, was assessed by RT-qPCR in ongrowing trout after 6 additional months of feeding at 17°C. Plasma glucose and cholesterol, lipid content and fatty acid profile of whole body were analyzed at both stages. After 7 months at 7°C, all juveniles reached the same body weight (10g), while at 13 months ongrowing fish fed the totally plant-based diet exhibited lower body weight (234 vs 330-337g). Body lipid content was higher in juveniles fed the totally plant-based diet (13.2 vs 9.4–9.9%), and plasma cholesterol was about 2-times lower in trout fed the plant-based diets at both stages. Fatty acid profile mirrored that of the respective diet, with low proportions of long-chain n-3 polyunsaturated fatty acids in fish fed plant-based diets. Genes involved in protein catabolism, carbohydrate metabolism and trafficking were down-regulated in the intestines of juveniles fed the plant-based diets. This was not true for ongrowing fish. Genes involved in lipid and cholesterol metabolisms were up-regulated in the livers of fish fed plant-based diets for both stages. In this study, feeding trout a totally plant-based diet from first-feeding affect a relatively low proportion of metabolism-related genes. In the longer term, when fish were reared at a higher temperature, only some of these changes were maintained (i.e. up-regulation of lipid/cholesterol metabolism). Although the plant-based diets tested in this study had no major deficiencies, small adjustments in the feed-formula are needed to further optimize growth performance while sparing marine resources.
... This agrees with the results of the current study where replacing up to 75% of fish meal protein with fish biosilage in common carp fingerling feeds did not result in any adverse alterations or abnormalities in fish liver structure (Figure 4). The nutritional adequacy of fish biosilage, as indicated by the histological examination of fish intestine and liver in the current study, may be ascribed partially to its content of fish oil rich in polyunsaturated fatty acids that reported to enhance general metabolism, tissue structural integrity, nutritional and health status of fish [9,24,25]. ...
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This study was carried out to evaluate the effects of locally produced fish biosilage as fish meal alternative on feeding, growth efficiency and gut histology in common carp C. Carpio fingerlings. Biosilage was prepared by fermenting marine bycatch fish with date fruit residues, domestic vinegar and citric acid. The produced biosilage was incorporated in feeds to replace 0, 25, 50 or 75% of fish meal protein. Fish were fed for 14 weeks and feeding and growth parameters were close in the four feed groups so as fish survival rate during the experiment (88.9-93.3%). Histological examination of intestine and liver sections has showed improvements when fish fed on the four different feeds. Initial fish group showed signs of nutritional deficiency through limited size of intestinal villi and hepatocytes. However, the histological structure of gut was improved after fish were fed on the experimental feeds without significant differences between fish meal or fish biosilage feeds. The study concluded that fish silage could replace fish meal without adverse effects on feeding, growth efficiency and gut histology.
... Since FO is a source of n-3 long-chain polyunsaturated fatty acids, the global need for FO for the aquaculture feed industry is still increasing. Therefore, oils from plant sources are considered to be a good alternative to FO to support sustainable aquaculture production; production of plant source oils is increasing and prices are lower than those for FO (Gunstone 2010). Some studies on FO replacement by vegetable oils have been reported with promising results (Montero et al. 2003;Lin and Shiau 2007;Yıldız et al. 2013;Yildirim et al. 2013). ...
Article
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A feeding study with Two-banded Seabream Diplodus vulgaris was conducted to determine the effects of replacement of fish oil (FO) by unrefined peanut oil (PO) on growth performance, feed utilization, body composition, fatty acid composition, and serum biochemical and hematological variables. Three isonitrogenous (35.8%) and isoenergetic (21.15 kJ/g) diets were formulated by replacing dietary FO with PO at levels of level 0%(PO0), 50% (PO50), or 100% (PO100). Fish were fed twice a day until satiation for an experimental period of 8 weeks. The best growth performance was observed in fish fed with the PO0 and PO50 diets. A significant increase was observed in hematocrit and mean corpuscular volume levels of fish fed with PO50 diet compared with the other groups. Hemoglobin, mean corpuscular hemoglobin, total protein, albumin, and globulin were not affected by dietary PO treatment and did not differ among experimental groups. The glucose level was highest in the PO100 group. Triglyceride and cholesterol levels were lower in fish fed diets with PO inclusions than in those fed the control diet. The fatty acid composition of fish was significantly affected by the experimental diets. Glutamic oxaloacetic transaminase, glutamic pyruvictransaminase, lactate dehydrogenase, and alkaline phosphatase were not affected by dietary PO treatment. The n-3:n-6 ratio in fish fed the PO0 diet was also higher than in fish fed the PO-supplemented diets. The results of the present study showed that FO could be substituted by PO up to 50% in Two-banded Seabream diets without any negative effect on growth performance or serum biochemical and hematological features.
... In fish they also have an important economic aspect, as fish are the primary source of n-3 LC-PUFA in the human diet [1]. Fish, like all vertebrates, are unable to synthesise polyunsaturated fatty acids (PUFA) de novo, and different teleost species have a range of capabilities in the bioconversion of dietary C 18 PUFA to LC-PUFA [2][3][4][5]. In general, and likely resulting from adaptation and evolution, fish can be classified into two different generic groups according to their respective fatty acid metabolism: those able to bioconvert dietary C 18 PUFA (essential fatty acids) such as linoleic acid (LA; 18:2n-6) and α-linolenic acid (ALA; 18:3n-3) into LC-PUFA; and those unable to bioconvert C 18 PUFA into LC-PUFA, and thus requiring dietary LC-PUFA to satisfy their essential fatty acid requirements [6]. ...
Article
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Rainbow trout, Oncorhynchus mykiss are intensively cultured globally. Understanding their requirement for long-chain polyunsaturated fatty acids (LC-PUFA) and the biochemistry of the enzymes and biosynthetic pathways required for fatty acid synthesis is important and highly relevant in current aquaculture. Most gnathostome vertebrates have two fatty acid desaturase (fads) genes with known functions in LC-PUFA biosynthesis and termed fads1 and fads2. However, teleost fish have exclusively fads2 genes. In rainbow trout, a fads2 cDNA had been previously cloned and found to encode an enzyme with ∆6 desaturase activity. In the present study, a second fads2 cDNA was cloned from the liver of rainbow trout and termed fads2b. The full-length mRNA contained 1578 nucleotides with an open reading frame of 1365 nucleotides that encoded a 454 amino acid protein with a predicted molecular weight of 52.48 kDa. The predicted Fads2b protein had the characteristic traits of the microsomal Fads family, including an N-terminal cytochrome b5 domain containing the heme-binding motif (HPPG), histidine boxes (HDXGH, HFQHH and QIEHH) and three transmembrane regions. The fads2b was expressed predominantly in the brain, liver, intestine and pyloric caeca. Expression of the fasd2b in yeast generated a protein that was found to specifically convert eicosatetraenoic acid (20:4n-3) to eicosapentaenoic acid (20:5n-3), and therefore functioned as a ∆5 desaturase. Therefore, rainbow trout have two fads2 genes that encode proteins with ∆5 and ∆6 desaturase activities, respectively, which enable this species to perform all the desaturation steps required for the biosynthesis of LC-PUFA from C18 precursors.
... Fish oil availability, however, is dependent on the success of marine fisheries that are unsustainable as historically utilized (Pauly et al., 2002;Shamshak and Anderson, 2008;Rana et al., 2009). Alternative plant lipid sources, including soybean oil, corn oil, linseed oil, rapeseed oil, and palm oil, are being investigated as potential replacements for fish oil, either partially or entirely, in aquafeed formulations (Rana et al., 2009;Gunstone, 2011). One of the most effective methods for reducing feed costs resides in minimizing the dietary lipid levels without compromising survival, growth, and normal physiological function of the animal. ...
... Consequently, the substitution of fish oil in aquafeed formulations with readily available and more economical terrestrial alternatives has been the object of intensive research effort (Turchini et al., 2009). This research focus has widely demonstrated that the substitution of fish oil with any alternative source results in a reflection of the dietary fatty acid composition in fish flesh, a potentially undesirable trait from an omega-3 long chain polyunsaturated fatty acid (n-3 LC- PUFA) consumption viewpoint (Rosenlund et al., 2010). Terrestrial alternatives to fish oil are characterised by a wide range of fatty acid compositions and are notably lacking in meaningful concentrations of LC-PUFA (Turchini et al., 2010). ...
Article
This study investigated effects of fish oil finishing diets on growth performance, fatty acid profiles and proximate composition of common carp Cyprinus carpio. Three isonitrogenous, isolipidic and isoenergetic diets were formulated. Diet 1 contained 50% fish oil and 50% canola oil and Diet 2 contained 50% fish oil and 50% poultry fat. The finishing diet (Diet 3) contained 100% fish oil. Fish were given different dietary treatments viz., T1 = 60 day feeding with Diet 1, T2 = 40 day (1-40) feeding with Diet 1 and 20 day (41-60) feeding with Diet 3, T3 = 60 day feeding with Diet 2, T4 = 40 day (1-40) feeding with Diet 2 and 20 day (41-60) feeding with Diet 3 and T5 = 60 day feeding with Diet 3. There was non-significant difference in the growth performance and proximate composition of fish in all the treatments. Inducing a dietary shift from canola oil based and poultry fat based feeds to fish oil based feeds supplied as finishing diet (i.e., T2 and T4) significantly increased long-chain PUFA concentrations in common carp as compared to those fed only canola oil (T1) and poultry fat (T3) based feeds. Amongst T2 and T4, treatment T2 appeared to be better with comparatively higher n-3 PUFAs and n-3/n-6 ratio. © 2016 Central Marine Fisheries Research Institute. All rights reserved.
... The biosynthesis of LC-PUFA from a-linolenic (18:3n-3, LNA) and linoleic (18:2n-6, LA) acids requires a series of fatty acyl desaturase (Fads) and elongation of very long-chain fatty acids (Elovl) enzymes [9]. Fish species vary in their capacity to biosynthesize LC-PUFA depending on their complement of these key enzymes [1,10]. ...
Article
Both the spotted scat Scatophagus argus and rabbitfish Siganus canaliculatus belong to the few cultured herbivorous marine teleost, however, their fatty acyl desaturase (Fad) system involved in long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis are different. The S. argus has a △6 Fad, while the rabbitfish has △4 and △6/△5 Fad, which were the first report in vertebrate and marine teleost, respectively. In order to compare the characteristics of elongases of very long-chain fatty acids (Elovl) between them, two Elovl cDNAs were cloned from S. argus in the present study. One has 885 bp of open read fragment (ORF) encoding a protein with 294 amino acid (aa) showing Elovl5 activity functionally characterized by heterologous expression in yeast, which was primarily active for the elongation of C18 and C20 PUFA. The other has 915 bp of ORF coding for a 305 aa protein showing Elovl4 activity, which was more efficient in the elongation of C20 and C22 PUFA. Tissue distribution analyses by RT-PCR showed that elovl5 was highly expressed in liver compared to other tissues determined, whereas elovl4 transcripts were only detected in eye. The expression of elovl5 and elovl4 were significantly affected by dietary fatty acid composition, with highest expression of mRNA in liver and eye of fish fed a diet with an 18:3n-3/18:2n-6 ratio of 1.7:1. These results indicated that the S. argus has a similar Elovl system in the LC-PUFA biosynthetic pathway to that of rabbitfish although their Fad system was different, suggesting that the diversification of fish LC-PUFA biosynthesis specificities is more associated with its Fad system. These new insights expand our knowledge and understanding of the molecular basis and regulation of LC-PUFA biosynthesis in fish.
... This agrees with the results of the current study where replacing up to 75% of fish meal protein with fish biosilage in common carp fingerling feeds did not result in any adverse alterations or abnormalities in fish liver structure (Figure 4). The nutritional adequacy of fish biosilage, as indicated by the histological examination of fish intestine and liver in the current study, may be ascribed partially to its content of fish oil rich in polyunsaturated fatty acids that reported to enhance general metabolism, tissue structural integrity, nutritional and health status of fish [9,24,25]. ...
Article
Full-text available
This study was carried out to evaluate the effects of locally produced fish biosilage as fish meal alternative on feeding, growth efficiency and gut histology in common carp C. Carpio fingerlings. Biosilage was prepared by fermenting marine by-catch fish with date fruit residues, domestic vinegar and citric acid. The produced biosilage was incorporated in feeds to replace 0, 25, 50 or 75% of fish meal protein. Fish were fed for 14 weeks and feeding and growth parameters were close in the four feed groups so as fish survival rate during the experiment (88.9-93.3%). Histological examination of intestine and liver sections has showed improvements when fish fed on the four different feeds. Initial fish group showed signs of nutritional deficiency through limited size of intestinal villi and hepatocytes. However, the histological structure of gut was improved after fish were fed on the experimental feeds without significant differences between fish meal or fish biosilage feeds. The study concluded that fish silage could replace fish meal without adverse effects on feeding, growth efficiency and gut histology.
... Secondly, 18:C fatty acids, and particularly LA, is also abundant in the marine trophic chain, where algae and other organisms are rich in this fatty acid ( Tsuchiya, 2000, 2002; Ortiz et al., 2006), and all of these organisms are candidates to be predated both by escaped fish and those of natural occurrence around farm structures and in the wild. Thirdly, aquafeed formulae are continuously changing depending on the availability and prices of ingredients , and consequently the fatty acid profile of aquafeeds is not stable (Gunstone, 2010). Thus, farm-associated animals and aquaculture fish do not always receive the same dietary fatty acid composition. ...
Article
Escapes of farmed fish into the ecosystem have recently received a marked interest from scientists for their competition with wild populations or the risk of genetic contamination. Fatty acid profiles have been proposed as bio-indicators due to the inclusion of terrestrial oils in aquafeed ingredients. This study evaluated 1) the effect of wasted food on the fatty acid content of a farm-associated fish and 2) the suitability of fatty acid profiles as a bioindicator of aquaculture-ecosystem interactions, using the bogue (Boops boops) as a model. This species is an opportunistic fish usually associated with-or even found in-sea farms, and with a high natural occurrence along the Mediterranean and Atlantic coasts. The results showed that fish farms had a direct effect on the condition index, muscle and whole lipid content of bogue inside or around the sea cage, and this effect disappeared completely at 3 km from the cages. Despite the fact that aquafeeds also affected the bogue fatty acid profiles by increasing linoleic and oleic acids and reducing DHA, these profiles were very similar to those of bogue sampled close to a sewage outfall, denoting that these fatty acids are not exclusively influenced by aquaculture and therefore should not be considered as good biomarkers for escapees. However, bogues influenced by aquaculture were higher in linolenic acid than those found further than 3 km from the farm or close to the sewage, suggesting this fatty acid as a better indicator of aquaculture influence.
... Rinchard et al. (2007) reported that rainbow trout only retain high proportion of 18:3n-3 in case of shortage . Bioconversion pathways for the elongation of polyunsaturated fatty acids have been reported (Buzzi et al. 1997; Bell et al. 2001; Torstensen & Tocher 2010), where elongases are proposed to be responsible such that 18:2n- 6, 18:3n-6, 18:3n-3 and 18:4n-3 are elongated to 20:2n-6, 20:3n-6, 20:3n-3 and 20:4n-6, respectively. However, in this study, 20:2n-6 and 20:4n-6 were only detected in significant amounts in fish fed the PO diet, and 20:3n-6 and 20:3n-3 were not detected at all. ...
Article
This study investigated the effect of the replacement of fish oil (FO) with DHA-Gold (DHA-G)-supplemented plant oils (PO) in rainbow trout fed plant-protein-based diets. Five diets (450 mg g−1 digestible protein and 150 mg g−1 crude lipid) were fed to rainbow trout (initial weight 37 ± 0.5 g) for 12 weeks in a 15 °C recirculating water system. The lipid inclusion types and levels were FO, PO and PO with DHA-G supplemented at 30 mg g−1, 60 mg g−1 or 90 mg g−1 of the diet replacement for corn oil. Fish fed 90 mg g−1 DHA-G were significantly larger and consumed more feed than fish-fed PO or FO (218 g and 2.6% bwd−1 versus 181 g and 2.4% and 190 g and 2.3%, respectively). Feed conversion ratio was significantly increased in fish fed 90 mg g−1 DHA-G (0.99) as compared to fish-fed FO (0.90) and 30 mg g−1 DHA-G (0.91). Panellists found trout fillets from fish fed the 90 mg g−1 DHA-G diet to have significantly fishier aroma and flavour than fish fed the FO diet. Fatty acid analysis demonstrated that 60 mg g−1 or 90 mg g−1 DHA-G supplementation increased PO fed fish fillet DHA to fatty acid levels equivalent or higher than those fish fed a FO diet.
... This agrees with the results of the current study where replacing up to 75% of fish meal protein with fish biosilage in common carp fingerling feeds did not result in any adverse alterations or abnormalities in fish liver structure (Figure 4). The nutritional adequacy of fish biosilage, as indicated by the histological examination of fish intestine and liver in the current study, may be ascribed partially to its content of fish oil rich in polyunsaturated fatty acids that reported to enhance general metabolism, tissue structural integrity, nutritional and health status of fish [9,24,25]. ...
Data
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This study was carried out to evaluate the effects of locally produced fish biosilage as fish meal alternative on feeding, growth efficiency and gut histology in common carp C. Carpio fingerlings. Biosilage was prepared by fermenting marine bycatch fish with date fruit residues, domestic vinegar and citric acid. The produced biosilage was incorporated in feeds to replace 0, 25, 50 or 75% of fish meal protein. Fish were fed for 14 weeks and feeding and growth parameters were close in the four feed groups so as fish survival rate during the experiment (88.9-93.3%). Histological examination of intestine and liver sections has showed improvements when fish fed on the four different feeds. Initial fish group showed signs of nutritional deficiency through limited size of intestinal villi and hepatocytes. However, the histological structure of gut was improved after fish were fed on the experimental feeds without significant differences between fish meal or fish biosilage feeds. The study concluded that fish silage could replace fish meal without adverse effects on feeding, growth efficiency and gut histology.
... However, this disease is rarely detected in the common carp because it does not store large quantity of lipids in the liver but instead uses visceral lipids as a primary storage site (Yilmaz and Genc, 2006;Steffens and Wirth, 2007;Bohme et al., 2014). On the other hand, the nutritional adequacy of fish biosilage, as indicated by the histological examination of fish intestine and liver in the current study, may be partially ascribed to its content of fish oil which represent about 22% of dry matter with fatty acid profile rich in polyunsaturated fatty acids that are reported to enhance general metabolism, tissue structural integrity, nutritional and health status of fish (Turchini et al., 2009;Torstensen et al., 2010;Fard et al., 2014). ...
Thesis
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This study is carried out to evaluate the utilization of marine fish by-catch silage fermented with date fruit residues as carbohydrate substrate in feeds for fry and fingerlings of the common carp Cyprinus carpio L. The study aim also to assess some physiological and histological effects of this fish biosilage inclusion into fish feeds. Marine fish by-catch sample consist of 23 marine fish species belonging to 18 families. A series of experiments are conducted to determine the optimum conditions for fermented fish silage production. Evaluation is based on several biochemical analyses. Date fruit residues DFR are widely available agricultural waste which is added successfully at 10% to fermentation medium. Domestic vinegar was served as inoculum when added at 20% of the total fermentation medium. Citric acid at 2% provides adequate acidity to start ensiling process. The produced silage is further improved by adding an antioxidant and antimycotic agent to conserve lipid quality and decrease histamine content. Fish meal is prepared by the standard method from the same fish sample for comparison purposes. Amino acid profile of fish silage is closer to the raw fish than fish meal especially the essential amino acids and is considered acceptable for fish feeding according to the documented criteria. Fatty acid profile of fish silage oil has been very rich in unsaturated fatty acids especially PUFA which consisted 47% of fatty acids in fish silage comparing to 37% in fish meal and this makes it a valuable source for marine fish oil in fish nutrition. To evaluate fish biosilage as a fish meal alternative in carp fry feeds, it is included to replace 0, 25, 50 and 75% of fish meal protein in isonitrogenous (42% CP) and isocaloric (4600 Kcal/kg) feeds. Physical quality properties of the prepared feeds are tested to determine the effect of silage inclusion. Bulk density, pellet durability and water stability have been improved by increasing silage addition while settling velocity and floatability show an opposite trend in comparison with the fish meal feed. The results of feeding and growth performance study which is performed with carp fry (average weight 0.68 gm) indicate very close resemblance between the four different feeds as assessed by weight gain, specific growth rate SGR, thermal growth coefficient TGU, feed conversion ratio FCR, protein efficiency ratio PER and survival rate. Another feeding trial is carried out with carp fingerlings (average weight 5.81 gm) fed isonitrogenous (35% CP) and isocaloric (4400 Kcal/kg) with similar fish silage inclusion rates as for fry feed. Silage inclusion rate of 50% is very close in feeding and growth performance parameters to fish meal basal feed. Higher silage addition has significantly lowered many parameters except for feed intake which increase with silage addition rate. Water quality parameters in both feeding experiments with fish fry and fingerlings has not been influenced adversely by silage inclusion in feeds. Apparent digestibility coefficients of major feed nutrients were improved with silage addition especially protein ADC which reach 89.88% in 75% silage feed in comparison with 82.55% in fish meal feed. Proximate composition of fish fingerlings fed on different experimental feeds showed no significant differences. However, fatty acid profile has been improved with increasing silage inclusion especially ω3-PUFA which elevated significantly from 7.98 to 10.18% in fish meal and 75% fish silage feed groups, respectively. Lipid and glycogen contents in fish liver and muscle do not differ significantly with silage addition in feed. General haematological parameters show no significant differences between the four feed groups despite silage inclusion rate so as plasma proteins. However, plasma lipid profile is improved with silage inclusion because of fish oil content in silage especially the total cholesterol levels which decrease by 20% in fish meal and 30% in 75% fish silage feed groups. The histological study includes the measurement of some tissue and cellular components of fish intestine and liver. The results of this study show no significant differences between fish meal basal feed and silage containing feed groups as to the examined components. This result is confirmed by examining the gross histology of intestine and liver sections which show no abnormal signs. Glycogen detection in hepatic tissue by PAS stain reveals rather similar pattern of distribution among liver section of different feed groups. However, lipid detection by both osmium tetraoxide and Sudan Black B stains demonstrate gradual improvement in hepatic lipid stores with silage addition in feed although carp liver has proved not to be a primary storage site for lipids. No signs of disturbance or abnormality of lipid metabolism are detected in the examined hepatic tissue sections. The study concludes that fish biosilage can be easily prepared by using local raw materials such as by-catch fish, DFR and vinegar. It is also a good partial alternative for fish meal in diets for fry and fingerlings of the common carp for its suitable nutritional properties. However, more improvements are needed before its exploitation in practical feeds especially some important physical quality parameters of feed. The study recommends some aspects to further investigation of fish silage and its application in aquafeeds.
... Substitution of FO by vegetable oils or fat of terrestrial animals is a good alternative to reduce costs and improve the fish production. However, this may influence many biochemical processes, such as changing the tissues fatty acid composition, digestibility, catabolism, desaturation and elongation of fatty acids and the eicosanoids synthesis (Torstensen & Tocher 2010). Previous studies have reported that the incorporation of oils from other sources, as vegetables and terrestrial animals , in the diet, is generally reflected in the fatty acid composition of the liver and muscles (Torstensen, Lie & Frøyland 2000; Bell, McEvoy, Tocher, McGhee, Campbell & Sargent 2001; Bell, Henderson, Tocher, McGhee, Dick, Porter, Smullen & Sargent 2002; Glencross 2003; Higgs, Balfry, Oakes, Rowsandell, Skura & Deacon 2006; Turchini & Francis 2009; Glencross, Rutherford & Jones 2011 ). ...
Article
For many fish species, dietary fish oil (FO) has been substituted with other oils such as poultry oil (PO) without affecting growth performance. However, in barramundi, the mechanisms by which fatty acid metabolism is regulated are poorly understood, and the effects of FO substitution are unknown. This study defined changes in the expression of genes controlling the metabolism of fatty acids in barramundi over a 24-h time period after a single meal. From one to 12 h after a single feeding event, the expression of fatty acid synthesis genes in the liver was upregulated, while genes involved in the β-oxidation showed minimal alteration. However, the expression of β-oxidation genes was significantly correlated with the expression of genes regulating fatty acid synthesis. In a second experiment, the changes in liver fatty acid composition and gene expression were defined after FO was substituted with PO. Liver fatty acid profile reflected the diet composition, with some subtle exceptions supporting the enrichment of certain long-chain polyunsaturated fatty acids in the liver. The fish from all experimental groups preferentially retained more docosahexaenoic acid than eicosapentaenoic acid in the liver, suggesting a bioconversion of this fatty acid to intermediate fatty acids. Replacement of FO with PO significantly regulated genes controlling both fatty acid synthesis and catabolism pathways, potentially related to a higher percentage of monounsaturated fatty acids, in the livers of fish fed these diets. The results demonstrated that diet composition significantly altered the lipid metabolism in barramundi and that there was a balance between direct dietary effects and endogenous synthetic capacity.
... With respect to fish oil replacement , practical alternatives at present include vegetable oils that lack the omega-3 long chain polyunsaturated fatty acids (n − 3 LC- PUFA), eicosapentaenoic (20:5n − 3, EPA) and docosahexaenoic (22:6n−3, DHA) acids. Canola oils are among the most abundantly produced vegetable oils globally, and are good candidates to replace of aquaculture feeds (Gunstone, 2010; Turchini and Mailer, 2010 ). The potential replacement of fish oil with canola oil into fish feeds was previously investigated, particularly for their ready and constant availability, relatively low price and energy availability (Turchini and Mailer, 2010). ...
... The rise in the use of vegetable oils (VO) as a feedstock in the biofuel industry, which started in the early 2000s, generated a subsequent increment in their prices that peaked in 2008 (Gunstone, 2011). This shift in the use of VO towards non-food uses created competition between the feed and the biofuel industries, since both oilseeds and feed grains used as ingredients in diets increased in price, placing the animal feed industry in a difficult situation. ...
Article
Alternatives to the use of native vegetable oils (VO) as fish oil (FO) replacers in aqua feeds were evaluated. Acid oils are a free fatty acid (FFA)-rich by-product mainly from the refining of VO. Re-esterified oils are the final product of a chemical esterification reaction between acid oils and glycerol, and have less FFA and more mono- and diacylglycerols (MAG and DAG), known for being good emulsifiers, than crude VO. Therefore, they could have a higher nutritive value than that of the native and acid oils. In two earlier studies in rainbow trout (Trullàs et al., 2015, 2016), diets including acid and/or re-esterified VO resulted in total fatty acid apparent digestibility coefficients above 95%. Moreover, no negative effects on growth, plasma biochemical parameters and morphology of tissues were observed when compared to the native oil diet. For all these reasons, the present study aimed at assessing their effects on the final quality of fillets of rainbow trout. Triplicate groups of rainbow trout were fed eight experimental diets containing 15% of different types of experimental rapeseed oils in addition to 5% of FO during 72 days. The experimental rapeseed oils were native (RNO), acid (RAO), re-esterified (REO), or blends (66% RN-33% RAO/33% RN-66% RAO or 66% REO-33% RAO/33% REO-66% RAO). Commercial FO was used for the control diet (F). The colorimetric analysis resulted in significant differences only in b* and C* in both fresh and thawed fillets, as well as in significant correlations between the colorimetric parameters among diets. For the total fat content, fillets of fish fed the control diet obtained the highest values, which were higher than those of fish fed diets containing RNO and the blend 66% REO-33% RAO. No differences in texture, liquid holding capacity, and TBARS were found among fillets of fish fed the different diets. Regarding tocopherol concentrations in fillets, α-tocopherol was significantly higher (P < 0.05) in fillets of fish fed the control diet than in those fed RA/RE, while β + γ-tocopherol was significantly lower in fillets of fish fed C than in the rest. Even though the aforementioned differences were found, they did not seem to be relevant concerning the final quality of fillet.
... Moreover, the nutritional state of fish can influence their immune function and disease resistance. Canola/rapeseed oils (CO/RO) are among the most abundantly produced vegetable oils globally, and production is on the rise (Gunstone 2010), making them good candidates to replace, at least partially, the fish oil normally included in aquaculture feeds (Turchini and Mailer 2010). Low-erucic acid canola oil is rich in 18 carbon fatty acids, most notably the monounsaturated fatty acids (MUFAs), 18:1 n -9 (oleic acid) as well as 18:2 n-6 (linoleic acid) and 18:3 n-3 (linolenic acid), and low in saturated fatty acids (SFAs) (Opsahl-Ferstad et al. 2003). ...
Article
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This study was undertaken to assess the effects of feeding European seabass (Dicentrarchus labrax) canola oil-added diets on growth, health status and liver and intestine histomorphology. Seabass (56.18 ± 0.16 g initial body weight) were fed one of three fish meal-based diets with *48 % crude protein and *16.0 % lipid, combining fish oil (FO) and canola oil (CO) for 12 weeks. The diets contained: zero (control, CTRL), 45 (CO50) or 63 (CO70) g CO kg-1 assigned in triplicates to three dietary groups. The results indicated that neither dietary oil type (FO or CO) nor CO level adversely affected (P[0.05) the growth, feed utilization or major blood constituents’ composition as an indicator of the overall health status of fish. Despite the CO diets influence on head kidney macrophage activity being unappreciable (P[0.05), there was a reducing trend with an increase in CO level incorporation. The CO70 diet induced a minor fat infiltration in hepatocytes and leucocytes infiltration, hyperplasia of the basal nuclei and supranuclear vacuolization of the enterocytes of the distal intestine. The present observations suggest that it is possible to incorporate up to 63 g CO Kg-1 in the feed for European seabass juveniles without major negative effects on growth, health status or liver and intestinal histomorphology. Keywords European seabass � Dicentrarchus labrax � Canola oil � Growth � Haematology � Liver and intestine histology
... A reduction in LC-PUFA levels results in changes in re-acylation H. Xu, et al. Progress in Lipid Research 80 (2020) 101064 mechanisms and phospholipid synthesis rates, and consequently lower lipoprotein assembly and lipid transportation [292]. Interestingly, dietary LC-PUFA also affects lipid deposition in interaction with water temperature. ...
Article
Fish are the main source of long-chain polyunsaturated fatty acids (LC-PUFA, > C18) for human consumption. In general, it has been widely observed that the fatty acid (FA) profiles of farmed fish are reflective of the diet. However, the degree of tissue FA “distortion” based on incorporation of different dietary FA into fish tissues varies greatly depending on FA type, fish species and environmental factors. In terms of fish FA composition, this variation has not been comprehensively reviewed, raising the question: “Are fish what they eat?”. To date, this remains unanswered in detail. To this end, the present review quantitatively summarized the ‘diet-fish’ FA relationship via an analysis of FA composition in diets and fish tissues from 290 articles published between 1998 and 2018. Comparison of this relationship among different fish species, tissue types or individual FA was summarized. Furthermore, the influence of environmental factors such as temperature and salinity, as well as of experimental conditions such as fish size and trophic level, feeding duration, and dietary lipid level on this relationship are discussed herein. Moreover, as a means of restoring LC-PUFA in fish, an emphasis was paid to the fish oil finishing strategy after long-term feeding with alternative lipid sources. It is envisaged that the present review will be beneficial in providing a more comprehensive understanding of the fundamental relationship between the FA composition in diets, and subsequently, in the farmed fish. Such information is integral to maintaining the quality of farmed fish fillets from the perspective of FA composition.
... This is consistent with previous studies where the apparent in vivo fatty acid metabolism was assessed in fish fed diets containing some FO Turchini et al., 2013), confirming Table 8 Apparent in vivo fatty acid β-oxidation (nmol/g of fish/day) in fish fed the six experimental diets for 14 weeks (only fatty acid that recorded β-oxidation in at least one treatment are reported). the notion that the presence of dietary n−3 LC-PUFA is responsible for limiting their possible in vivo biosynthesis (Thomassen et al., 2012;Torstensen and Tocher, 2011;Zheng et al., 2004). ...
Article
Amongst the various available alternative oils, tallow (TAL) has attracted limited research interest and is not commonly used in commercial aquafeeds. This is likely due to concerns of consumers' perception and its high saturated fatty acid (SFA) content, which raises concerns about its digestibility, particularly for species cultured in cold water conditions, such as the Atlantic salmon (Salmo salar). Conversely TAL is conveniently priced and has a very low n − 6 polyunsaturated fatty acid (PUFA) content, which may be beneficial to the final product quality. In many parts of the world, modern salmon aquafeed commonly contains poultry by-product oil (PbO) as the alternative lipid source to replace fish oil (FO). Accordingly, the control diet used for the present experiment contained 75% PbO and 25% FO, as the added dietary lipid sources. Five additional experimental diets were formulated to progressively increase the level of TAL inclusion substituting PbO in 10% increments (10–50%), with a constant amount of FO (25%). A feeding trial was conducted using triplicate groups of Atlantic salmon over a 14 week time period at 10 °C. No difference in growth performance was recorded between treatments, but TAL substitution impacted lipid and fatty acid digestibility. The apparent in vivo β-oxidation of SFA intensified with TAL inclusion, whilst n − 3 PUFA β-oxidation decreased. TAL inclusion also resulted in increased apparent in vivo bioconversion of 22:5n − 3 to 22:6n − 3. This was also reflected in fillet and whole body n − 3 long chain PUFA (LC-PUFA) composition. TAL inclusion impacted positively on the fillet n − 3/n − 6 PUFA ratio. This study suggests that TAL appears to be a viable alternative oil, with potential for inclusion in commercial aquafeeds.
... argued that the increased FA b-oxidation resulting from a reduced dietary cholesterol supply may be due to the increased energy and acetyl-CoA demands that are required for the increased cholesterol synthesis [43,44]. A second objective of the present study was to assess if dietary cholesterol had any effect on fatty acid metabolism, as the key enzymes involved this pathway are known to be affected by several physiological and nutritional factors [45], including dietary fatty acid composition and cholesterol [17]. Specifically, in rats, dietary supplementation of cholesterol has been shown to increase the activity of stearyl-CoA desaturase (D9fad), leading to accumulation of MUFA [17,42], whereas the activities of D5fad and D6fad were both shown to be reduced by dietary cholesterol [15,16,18]. ...
Article
Full-text available
Teleost fish, as with all vertebrates, are capable of synthesizing cholesterol and as such have no dietary requirement for it. Thus, limited research has addressed the potential effects of dietary cholesterol in fish, even if fish meal and fish oil are increasingly replaced by vegetable alternatives in modern aquafeeds, resulting in progressively reduced dietary cholesterol content. The objective of this study was to determine if dietary cholesterol fortification in a vegetable oil-based diet can manifest any effects on growth and feed utilization performance in the salmonid fish, the rainbow trout. In addition, given a series of studies in mammals have shown that dietary cholesterol can directly affect the fatty acid metabolism, the apparent in vivo fatty acid metabolism of fish fed the experimental diets was assessed. Triplicate groups of juvenile fish were fed one of two identical vegetable oil-based diets, with additional cholesterol fortification (high cholesterol; H-Chol) or without (low cholesterol; L-Chol), for 12 weeks. No effects were observed on growth and feed efficiency, however, in fish fed H-Col no biosynthesis of cholesterol, and a remarkably decreased apparent in vivo fatty acid β-oxidation were recorded, whilst in L-Chol fed fish, cholesterol was abundantly biosynthesised and an increased apparent in vivo fatty acid β-oxidation was observed. Only minor effects were observed on the activity of stearyl-CoA desaturase, but a significant increase was observed for both the transcription rate in liver and the apparent in vivo activity of the fatty acid Δ-6 desaturase and elongase, with increasing dietary cholesterol. This study showed that the possible effects of reduced dietary cholesterol in current aquafeeds can be significant and warrant future investigations.
... In terms of dietary oil, depending on plant source and diet formulation covering essential fatty acid requirements, replacement of 60-75% of the diet fish oil does not substantially reduce growth, FCR, and feed intake (Sales and Glencross, 2011;Turchini et al., 2009). On the other hand, replacing 100% of fish oil with plant oil has been reported to significantly reduce FCR, growth, and lower deposition of unsaturated fatty acids (i.e., EPA-DHA), with the effect depending on the fatty acid profile and the proportion of the different saturation categories of the plant oil being used (Glencross and Turchini, 2010;Lazzarotto et al., 2018;Torstensen and Tocher, 2010). ...
... However, in feeds for marine carnivorous fish the use of VO as a sole lipid source is limited by the high dietary requirements of these species LC-PUFA ( Benedito-Palos et al., 2009). The high requirements for LC-PUFA are due to the limited ability to these species of bioconvert C 18 polyunsaturated fatty acids (PUFA; namely linoleic acid -18:2n-6, LA-and α-linolenic acid -18:3n-3, ALA-) into for LC-PUFA (namely arachidonic acid - 20:4n-6, ARA-, eicosapentaenoic acid -20:5n-3, EPAand docosahexaenoic acid -22:6n-3, DHA-) (Torstensen and Tocher, 2010). European sea bass, Dicentrarchus labrax, is a strict carnivorous marine fish and it has been suggested to have extremely low rates of PUFA bioconversion (Mourente et al., 2005a, Mourente et al., 2005b). ...
Article
Triplicate groups of 20 European sea bass (35 g) were fed five diets in which the added lipid was 100% fish oil (FO), 40% (CSO40), 60% (CSO60), 80% (CSO80) and 100% (CSO100) refined cottonseed oil (CSO), for a period of 120 days. Overall fish growth, feed conversion ratio and protein utilization were unaffected by dietary treatment, but hepatosomatic and visceral fat indexes increased with increasing dietary CSO. Fillet fatty acid composition of total lipids reflected the fatty acids in the test diets. The monounsaturated fatty acids were significantly higher in fillet of fish fed diet FO, CSO40 and CSO60 compared to other treatments while saturated and polyunsaturated fatty acids (PUFA) were not affected by the dietary treatment. Some fatty acids (18:0, 18:1n-9, 20:5n-3 and 22:6n-3) were present in higher concentration in fillet lipid than in the CSO100 dietary lipid indicating accumulation in fillet relative to test diets. Retention of n-3 LC-PUFA within the fillet was increasingly inefficient among fish fed increasing levels of FO. Thus, this study suggests that CSO can be considered as a relatively effective substitute for fish oil in European sea bass (35 g) in terms of growth performances and feed efficiency as far as fish meal is present in the diet.
... Fish oil availability, however, is dependent on the success of marine fisheries that are unsustainable as historically utilized (Pauly et al., 2002;Shamshak and Anderson, 2008;Rana et al., 2009). Alternative plant lipid sources, including soybean oil, corn oil, linseed oil, rapeseed oil, and palm oil, are being investigated as potential replacements for fish oil, either partially or entirely, in aquafeed formulations (Rana et al., 2009;Gunstone, 2011). One of the most effective methods for reducing feed costs resides in minimizing the dietary lipid levels without compromising survival, growth, and normal physiological function of the animal. ...
Article
Dietary lipids serve as important sources of energy and essential fatty acids for aquatic animals. Sources of animal and plant oils are increasingly limited as well as expensive, and dietary requirements associated with the inclusion of these oils must be carefully evaluated to facilitate sustainable and affordable formulations. In this study, we investigated quantities of menhaden oil (MO) with and without soybean lecithin or soybean oil (SO) to determine appropriate levels for optimal somatic growth for pre-gonadal juvenile Lytechinus variegatus. We prepared semi-purified diets that varied in neutral lipid content (0, 2, 4, or 8% dry matter) and soy lecithin (0 or 2%) and exchanged lipids reciprocally with purified starch while holding constant all other nutrients. We maintained laboratory-reared juvenile L. variegatus (average initial wet weight 82 ± 0.7 mg, mean ± SE, n = 9 treatment- 1) in recirculating seawater systems and fed each daily a sub-satiation ration for five weeks. We assessed wet weights and test diameters every two weeks and at the end of the experiment (5 wk). Level of MO with or without soybean lecithin did not significantly affect wet weight gain; however, increasing levels of SO in the diet reduced wet weight gain and dry matter production efficiency and increased feed conversion ratio. Dry gut weight was positively correlated with level of MO. Lipid level in the gut increased with increasing dietary lipid level, regardless of source. These data suggest the composition of the SO is inhibitory for either nutrient absorption or metabolic processes associated with growth at this life stage. Diets containing total lipid levels of approximately 5 to 6% that include sources of n-3 fatty acids may support optimal growth for pre-gonadal juvenile L. variegatus.
Article
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Marine fish are generally unable to produce sufficient quantities of n-3 highly unsaturated fatty acid (n-3 HUFA) such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). Consequently, the seed production of marine fish requires careful nutritional enrichment of live feeds such as rotifers and brine shrimp Artemia to meet n-3 HUFA requirements for normal growth. Another strategy for improving n-3 HUFA availability is modifying the biosynthetic pathway of marine fish using transgenic technology. In this study, we conducted a feeding trial with non-transgenic and transgenic nibe croaker Nibea mitsukurii carrying the elongation of very long-chain fatty acids protein 2 (Elovl2) gene isolated from masu salmon Oncorhynchus masou and three groups of Artemia (non-enriched and enriched with two products). For all Artemia groups, docosapentaenoic acid (DPA, 22:5n-3), which is a direct product of Elovl2, was significantly higher in the transgenic fish than that in non-transgenic fish, despite the absence of DPA in all diets. Thus, applying transgenic techniques to marine fish at the larval stage are a powerful strategy for modifying n-3 HUFA biosynthetic pathways.
Article
The Pacific lamprey Entosphenus tridentatus is an ancestral species of critical importance to the ecosystem and indigenous cultures in the Pacific Northwest. Conservation aquaculture has been proposed as a potential technique to restore Pacific lamprey populations. Intensive culture methods and diets for this species have not been developed. A sixteen week feeding trial tested the effects of seven diet treatments on the survival, growth, fatty acid profile and whole body lipid content of Pacific lamprey ammocoetes. Dietary treatments were: active dry yeast, yeast plus fish oil emulsion, micro-algae, micro-algae plus fish oil emulsion, yeast with micro-algae, yeast with micro-algae plus fish oil emulsion and yeast with larval fish diet. Each diet was offered to five replicate tanks stocked with 20 ammocoetes that were 51 days post hatch. Survival during the trial was not affected by diet. The greatest length and weight increases were in fish fed diets containing yeast. Growth decreased as the amount of algae in the diet was increased. Lipid retention was significantly higher in fish fed yeast with larval fish diet relative to the other treatments. Feed conversion ratio was lowest in fish fed diets containing yeast. Whole body fatty acid profiles tended to reflect the fatty acid profile of the diet. Percentages of 20:5n-3 and 22:6n-3 were significantly higher in fish fed diets containing fish oil emulsion. Overall, yeast with larval fish diet provided the best growth performance in larval Pacific lamprey.
Book
This book is about the fish we eat, fish that not only sustains us but also provides us with pleasure and well-being. Fish is also a valuable source of nutraceuticals and pharmaceuticals. We follow a holistic approach in this book viewing fish in its entirety from the food that fish need in order to grow to the pharmaceutical applications of fish oil. 2014 is a historic year, it is the first year in human history where the amount of fish we consume from aquaculture will surpass that from the wild. As it seems that aquaculture will play a vital role in the future feeding of mankind, it should be considered imperative that it be done in a responsible and sustainable way. Food security is both the top political and scientific priority today. With this book, we try to provoke some thoughts as to how fish is produced, how it is valorised and what could be done in the future. We address within this book the issue of resource management, fish nutritional requirements, aquatic food security, nutritional value of marine oils and fish themselves as well as to how we can further exploit marine oil usage in the production of nutraceuticals and pharmaceuticals. (Imprint: Nova) https://www.novapublishers.com/catalog/product_info.php?products_id=53103&osCsid=
Article
It is known that fatty acids (FA) regulate lipid metabolism by modulating the expression of numerous genes. In order to gain a better understanding of the effect of individual FA on lipid metabolism related genes in rainbow trout (Oncorhynchus mykiss), an in vitro time-course study was implemented where twelve individual FA (butyric 4:0; caprylic 8:0; palmitic (PAM) 16:0; stearic (STA) 18:0; palmitoleic16:1n-7; oleic 18:1n-9; 11-cis-eicosenoic 20:1n-9; linoleic (LNA) 18:2n-6; α-linolenic (ALA) 18:3n-3; eicosapentenoic (EPA) 20:5n-3; docosahexaenoic (DHA) 22:6n-3; arachidonic (ARA) 20:4n-6) were incubated in rainbow trout liver slices. The effect of FA administration over time was evaluated on the expression of leptin, PPARα and CPT-1 (lipid oxidative related genes). Leptin mRNA expression was down regulated by saturated fatty acids (SFA) and LNA, and was up regulated by monounsaturated fatty acids (MUFA) and long chain PUFA, whilst STA and ALA had no effect. PPARα and CPT-1mRNA expression were up regulated by SFA, MUFA, ALA, ARA and DHA; and down regulated by LNA and EPA. These results suggest that there are individual and specific FA induced modifications of leptin, PPARα and CPT-1 gene expression in rainbow trout, and it is envisaged that such results may provide highly valuable information for future practical applications in fish nutrition.
Article
Long-chain unsaturated n-3 fatty acids are of remarkable significance in human nutrition. They have antiatherosclerotic efficacy and other beneficial health effects too. Aquaculture fish, e.g. cyprinids, such as silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio), tench (Tinca tinca), and salmonids like Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) as well as European catfish (Silurus glanis), Baltic whitefish (Coregonus maraena), European seabass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), and Nile tilapia (Oreochromis niloticus), are rich in these fatty acids. When fed on suitable diets, the fatty acid composition of cultured fish can be influenced advantageously. Several clinical tests proved the effectiveness of the consumption of farmed fish in promoting human health. Thus, aquaculture fish can be recommended as wholesome food.
Article
This study aimed to test the hypothesis that the efficiency of a finishing period can be improved by reducing the initial fat content of fish fillets, by means of a period of food deprivation. Two groups of rainbow trout (Oncorhynchus mykiss) were fed for an 18‐week grow‐out period on a vegetable oil‐based diet (VO) or a fish oil‐based diet (FO). VO fed fish were then split into two sub groups: one (VO/FO) was shifted to the FO diet for 8 weeks, whilst the other (UF/FO) was deprived of food (unfed) for 2 weeks and then fed the FO diet for the remaining 6 weeks. The control treatment (FO/FO) was represented by fish continuously fed FO. The subsequent reduction of total fat in the UF/FO treatment was then responsible for a much faster recovery towards a FO‐like fatty acid profile, validating the proposed hypothesis. However, the modification of the fatty acid composition of fish fillets during the feed withholding period, coupled with the postponement of the finishing diet, resulted in only minor beneficial effects of this strategy, and the loss of potential weight gain. However, the n‐3 LC‐PUFA content in UF/VO fish fillets was significantly higher than fish subjected to the VO/FO treatment.
Article
Rainbow trout were fed diets containing either fish meal and fish oil (FM-FO) (control) or diets in which 40% of the fishmeal was substituted with a mixture of ingredients grown organically including plant protein concentrate (PP) in combination with either fish oil (FO) as lipid source, or one of the following organic plant oils; rapeseed (RO), linseed/flaxseed (LO), grape seed (GO), or sunflower (SO). The impact of these substitutions was investigated by measuring fish muscle fatty acid profile as well as oxidative and color stability of the fillet during 14 days ice storage. The inclusion of plant protein concentrate did not affect the fatty acid profile significantly but resulted in a slightly improved oxidative stability of the fish fillets as compared to the control diet. The fatty acid profile of the oil used was in general well reflected in the fish muscle fatty acid profile. Fish fed PP-RO were the most oxidatively stable during ice storage but the omega-3 fatty acid content was reduced by 40% compared to fish fed the FM-FO control diet. Replacing FO by LO was not suitable as it induced oxidation and the fillet contained 40–50% less of long chain omega-3 fatty acids.
Article
Largemouth bass (LMB; ~15.2 g initial weight) was fed one of the five experimental, and a fishmeal (FM)/fish oil (FO) control diet and two commercial (Xinxin, Coppens) LMB feeds for 10 weeks. Fish were dispersed into 24, 110‐L aquaria (n = 20/tank) configured as a recirculating system. Aquaria were arbitrarily allocated to dietary treatments in triplicate (n = 60/fish diet). The FM component of experimental diets was replaced using poultry by‐product meal and soy protein concentrate. One experimental diet contained FO, whereas in others, FO was replaced with canola, flax and/or algal oil or combinations thereof. At trial end, there were no differences among fish‐fed various diets in terms of feed conversion or protein efficiency ratios. Weight gain and survival were similar for experimental groups, and LMB fed the Xinxin commercial feed, but the Coppens feed returned inferior (p < 0.05) weights and higher mortality. Condition factor, fillet yield and intraperitoneal fat ratios were unaffected by diet but hepatosomatic index varied. The Coppens feed caused greatest differences in whole‐body protein, lipid and ash contents (p < 0.001). Whole‐body fatty acid profiles reflected those of the diet, with algal oil enriched feed illustrating enhanced DHA:EPA ratios.
Article
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This study aimed to evaluate the effects of dietary lipid source and carbohydrate content on the oxidative status of European sea bass ( Dicentrarchus labrax ) juveniles. For that purpose, four diets were formulated with fish oil (FO) and vegetable oils (VO) as the lipid source and with 20 or 0 % gelatinised starch as the carbohydrate source, in a 2×2 factorial design. Liver and intestine antioxidant enzyme activities (catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD)), hepatic and intestinal lipid peroxidation (LPO), as well as hepatic oxidative stress index (OSI), were measured in fish fed the experimental diets for 73 d ( n 9 fish/diet). Carbohydrate-rich diets promoted a decrease in hepatic LPO and OSI, whereas the lipid source induced no changes. Inversely, dietary lipid source, but not dietary carbohydrate concentration, affected LPO in the intestine. Lower intestinal LPO was observed in VO groups. Enzymes responsive to dietary treatments were GR, G6PD and CAT in the liver and GR and GPX in the intestine. Dietary carbohydrate induced GR and G6PD activities and depressed CAT activity in the liver. GPX and GR activities were increased in the intestine of fish fed VO diets. Overall, effects of diet composition on oxidative status were tissue-related: the liver and intestine were strongly responsive to dietary carbohydrates and lipid sources, respectively. Furthermore, different metabolic routes were more active to deal with the oxidative stress in the two organs studied.
Chapter
Interest in dietary lipid and fatty acids has increased in recent years due to the fact that supplies of marine resources for feeds are now limiting aquaculture development. This chapter discusses the biochemistry and metabolism of lipids and fatty acids. There are many studies demonstrating that changes in dietary fatty acid compositions can affect fish health and welfare. Many of the reported effects could be a direct consequence of altered cellular fatty acid compositions, particularly of crucial biomembranes, with associated important functional consequences. Specifically, alterations to dietary n-3 PUFA: n-6 PUFA ratios and, particularly dietary EPA: ARA ratios have important consequences for eicosanoid metabolism. The chapter summarizes that dietary lipid and fatty acids have a range of effects that could influence fish health and welfare; however, these are variable depending upon factors including fish species, level and duration of dietary alteration, other dietary components, and environmental conditions.
Article
The farming of marine carnivorous fishes coupled with the development of high‐energy diets is placing demand on traditional feed ingredients, such as fish oil (FO). Oils of terrestrial origin with high content of n‐3 such as camelina seed (CSO) and chia oil (CO) have been shown to be good alternatives as fish oil replacement in the diets of cultured fish. The current study assessed the effect of inclusion of n‐3 C18 rich oils on nutrient profile and quality of flesh in gilthead seabream (≈ 61.5 g) after feeding isoproteic and isolipidic diets in which camelina seed (CSO) or chia oil (CO) totally or partially replaced fish oil for 110 days. Fillet fatty acid (FA) profile reflected dietary FA profile, characterized by increased C18 polyunsaturated FA (PUFA) and a reduced highly unsaturated FA (HUFA) whereas n–3/n–6 ratios were increased in fish fed diets with CSO or CO content. However, indices of atherogenicity and thrombogenicity, calculated from the fillet FA profile as indices for the health quality for consumers, were reduced with dietary addition of CSO or CO due to the increased fillet content of C18 n‐3 PUFA in CSO and CO fed fish. In spite of the differences in fillet FA profiles, sensory quality of flesh did not vary among fish from different dietary groups. Instrumental texture and colour analyses revealed significantly different values in cooked fillets in comparison to the raw fillets. Overall, dietary inclusion of CSO or CO enhanced the nutritional value of fish flesh as well as the production of healthier fillets. Practical applications: This study suggests fish oil could be totally replaced with camelina or chia oil in the diet of gilthead sea bream without negatively affecting sensory characteristics. The dietary inclusion of these oils could enhance the nutritional quality of fish fillets, and could receive wide application in the aquafeed and animal feed producing sector. This article is protected by copyright. All rights reserved
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Vegetable oils (VO) are possible substitutes for fish oil in aquafeeds but their use is limited by their lack of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA). However, oilseed crops can be modified to produce n-3 LC-PUFA such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, representing a potential option to fill the gap between supply and demand of these important nutrients. Camelina sativa was metabolically engineered to produce a seed oil with around 15 % total n-3 LC-PUFA to potentially substitute for fish oil in salmon feeds. Post-smolt Atlantic salmon (Salmo salar) were fed for 11-weeks with one of three experimental diets containing either fish oil (FO), wild-type Camelina oil (WCO) or transgenic Camelina oil (DCO) as added lipid source to evaluate fish performance, nutrient digestibility, tissue n-3 LC-PUFA, and metabolic impact determined by liver transcriptome analysis. The DCO diet did not affect any of the performance or health parameters studied and enhanced apparent digestibility of EPA and DHA compared to the WCO diet. The level of total n-3 LC-PUFA was higher in all the tissues of DCO-fed fish than in WCO-fed fish with levels in liver similar to those in fish fed FO. Endogenous LC-PUFA biosynthetic activity was observed in fish fed both the Camelina oil diets as indicated by the liver transcriptome and levels of intermediate metabolites such as docosapentaenoic acid, with data suggesting that the dietary combination of EPA and DHA inhibited desaturation and elongation activities. Expression of genes involved in phospholipid and triacylglycerol metabolism followed a similar pattern in fish fed DCO and WCO despite the difference in n-3 LC-PUFA contents.
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The reliance of the aquafeed industry on marine resources has to be reduced by innovative approaches in fish nutrition. Thus, a three-factorial approach (fish oil reduced diet, phytochemical genistein, and temperature reduction) was chosen to investigate the interaction of effects on growth performance and tissue omega-3 long chain polyunsaturated fatty acid (LC-PUFA) levels in juvenile sea bream (Sparus aurata, 12.5 ± 2.2 g). Genistein is a phytoestrogen with estrogen-like activity and thus LC-PUFA increasing potential. A decrease in the rearing temperature was chosen based on the positive effects of low temperature on fish lipid quality. The experimental diets were reduced in marine ingredients and had a fish oil content of either 6% dry matter (DM; F6: positive control) or 2% DM (F2: negative control) and were administered in the plain variant or with inclusion of 0.15% DM genistein (F6 + G and F2 + G). The feeding trial was performed simultaneously at 23°C and 19°C. The results indicated that solely temperature had a significant effect on growth performance and whole body nutrient composition of sea bream. Nevertheless, the interaction of all three factors significantly affected the fatty acid compositions of liver and fillet tissue. Most importantly, they led to a significant increase by 4.3% of fillet LC-PUFA content in sea bream fed with the diet F6 + G in comparison to control fish fed diet F6, when both groups were held at 19°C. It is hypothesized that genistein can act via estrogen-like as well as other mechanisms and that the dietary LC-PUFA content may impact its mode of action. Temperature most likely exhibited its effects indirectly via altered growth rates and metabolism. Although effects of all three factors and of genistein in particular were only marginal, they highlight a possibility to utilize the genetic capacity of sea bream to improve tissue lipid quality.
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Background: Silver barb (Puntius gonionotus) is a promising medium-sized carp for freshwater aquaculture in Asia. This study's aim was to investigate the ideal dietary α-linolenic acid (ALA): linoleic acid (LA) ratio for maximizing long chain polyunsaturated fatty acids (LC-PUFA) synthesis and their deposition in the muscle of silver barb, at par that of fish oil based control diet. Result: Fish (11.07 ± 0.12 g of initial body weight) were fed for 60 days with five experimental iso-proteinous, iso-lipidic and iso-caloric diets, supplemented with linseed oil and peanut oil at varying levels to get ALA/LA ratios of 0.35, 0.51, 0.91, 2.04, 2.66 and a control diet prepared by supplementing fish oil. Dietary ALA/LA ratio did not influence the growth performance of fish. With increased dietary ALA/LA ratios LA content decreased and ALA content increased in muscle and liver of silver barb. The n-3 LC-PUFA level in muscle and liver were not influenced on feeding different ratios of ALA/LA, whereas n-6 LC-PUFA was decreased in the muscle and increased in the liver with increased dietary level of ALA/LA ratios. Increasing dietary ALA/LA ratio increased Δ6fad and elovl5mRNA expression in the liver, muscle, brain and intestinal tissues of silver barbs. Conclusion: Silver barb possess the ability to elongate and desaturate ALA and LA to their end products EPA and DHA. The highest level expression of Δ6 fad and elovl5 mRNA at the dietary ALA/LA ratios of 2.66 suggests greater affinity of these enzyme towards ALA than LA in silver barb. This article is protected by copyright. All rights reserved.
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A nine week feeding trial was conducted to evaluate one custom formulation, and six commercially available diets when fed to juveniles of the endangered Lost River Sucker Deltistes luxatus (LRS). The seven treatments included: two catfish diets, a tilapia diet, a shrimp diet, a general warm water fish diet, a general fish diet, and a feed formulated at the Abernathy Fish Technology Center (Abernathy Sucker diet). The general fish diet produced fish that were significantly larger than the fish fed the other diets. The LRS fed the general fish diet or the Abernathy Sucker diet averaged 99.0% survival for the duration of the trial, which was significantly higher than in LRS fed all other diets except for one catfish diet. Spinal deformities were significantly less frequent in fish fed the general fish diet and the Abernathy Sucker diet. Whole body proximate and fatty acid composition were affected by diet. Whole body fatty acid profiles generally mirrored the diet profiles. The general fish diet appears to be an effective diet for juvenile LRS, although the Abernathy Sucker diet should be considered for further development, as it yielded high survival and no incidence of spinal deformity.
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Camelina and chia oils are among the vegetable oils (VOs) with high content of α‐linolenic acid (ALA) and a combination of antioxidants, giving them nutritional advantage over other VOs used in aquafeeds. The present study evaluated the effects of dietary substitution of fish oil with oils from camelina or chia on the growth performance, fatty acid (FA) composition, gene expression and blood haematology in gilthead sea bream after a 90‐day feeding trial. Five isoproteic and isolipidic diets were formulated in which fish oil was 100% (camelina oil, CSO diet; and chia oil, CO diet) or 60% (MIX1 and MIX2 diets containing camelina and chia oils, respectively) replaced with camelina or chia oils. Growth performance and FA profiles of fish were significantly affected by the dietary treatments (p < .05). Contents of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (ARA) decreased, whereas n‐3 polyunsaturated fatty acid (PUFA) and n‐3/n‐6 ratio increased in fish fed diets containing oils from camelina or chia. An up‐regulation in the expression of genes involved in PUFA metabolism and the subsequent in vivo bioconversion of precursor FAs into highly unsaturated fatty acid (HUFA, C ≥ 20 and n ≥ 3) were recorded in fish fed VO‐based diets. Red blood cells (RBC), white blood cells (WBC), haemoglobin and haematocrit did not differ among fish fed the experimental diets. Our overall results suggested that replacement of fish oil with camelina or chia oil did not adversely affect growth performance in gilthead sea bream, except for those fed CSO diet. Our results also demonstrate that fatty acid profile of fish can be modified by the dietary inclusion level of camelina or chia oils.
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The Theory of Planned Behavior (TPB) has so far found few applications in aquaculture research. Using Rogers’ innovation adoption characteristics as a complementary framework, we explore its relevance in describing Indian carp farmers’ perceptions of the attributes of fish feed containing non-conventional ingredients (seaweeds, freshwater macrophytes, microalgae and microbes), and in understanding the factors influencing their intention to use these feeds. We find that fish farmers familiar with manufactured feed tend to have more positive attitudes to the inclusion of non-conventional ingredients in fish feed than those who are not. Perceived peer pressure, importance and benefits from the novel aquafeed, perceived comparative advantage and uncertainty regarding outcomes from its use are the main determinants of intention to adopt the proposed feed innovation. The combined application of the TPB and Rogers’ innovation framework provides valuable insights into fish farmers’ attitudes and behavioral intention toward innovation adoption, and we recommend its wider use for designing interventions that promote technological innovations and improved farm management. By exploring the underpinnings of intention to adopt an innovation, our study contributes to the literature on fish farmers’ behavior and attitudes to innovations in aquaculture.
Thesis
Efeitos da suplementação da dieta com diferentes fontes de ácidos graxos no metabolismo lipídico de fêmeas de Epinephelus marginatus - Effects of dietary supplementation with different fatty acids sources in the lipid metabolism of Epinephelus marginatus females São Paulo 2016
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Largely attributable to concerns surrounding sustainability, the utilisation of omega-3 long-chain polyunsaturated fatty acid-rich (n-3 LC-PUFA) fish oils in aquafeeds for farmed fish species is an increasingly concerning issue. Therefore, strategies to maximise the deposition efficiency of these key health beneficial fatty acids are being investigated. The present study examined the effects of four vegetable-based dietary lipid sources (linseed, olive, palm and sunflower oil) on the deposition efficiency of n-3 LC-PUFA and the circulating blood plasma concentrations of the appetite-regulating hormones, leptin and ghrelin, during the grow-out and finishing phases in rainbow trout culture. Minimal detrimental effects were noted in fish performance; however, major modifications were apparent in tissue fatty acid compositions, which generally reflected that of the diet. These modifications diminished somewhat following the fish oil finishing phase, but longer-lasting effects remained evident. The fatty acid composition of the alternative oils was demonstrated to have a modulatory effect on the deposition efficiency of n-3 LC-PUFA and on the key endocrine hormones involved in appetite regulation, growth and feed intake during both the grow-out and finishing phases. In particular, n-6 PUFA (sunflower oil diet) appeared to 'spare' the catabolism of n-3 LC-PUFA and, as such, resulted in the highest retention of these fatty acids, ultimately highlighting new nutritional approaches to maximise the maintenance of the qualitative benefits of fish oils when they are used in feeds for aquaculture species.
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