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1.
The substitution of fish oil with wax ester‐rich calanoid copepod‐derived oil in diets for carnivorous fish, such as Atlantic salmon, has previously indicated lower lipid digestibility. This suggests that the fatty alcohols (FAlc) present in wax esters may be a poorer substrate for intestinal enzymes than the fatty acids (FA) in triacylglycerol (TAG), the major lipid in fish oil. The hypothesis tested was that the possible lower utilization of dietary FAlc by salmon enterocytes is at the level of uptake and that subsequent intracellular metabolism was identical to that of FA. A dual‐labelled FAlc–FA metabolism assay was employed to determine simultaneous FAlc and FA uptake and relative utilization in enterocytes isolated from pyloric caeca of Atlantic salmon fed either a diet supplemented with fish oil or wax ester‐rich Calanus oil. The diets were fed for 10 weeks before caecal enterocytes from each dietary group were isolated and incubated with equimolar mixtures of either [1‐14C]16:0 FA and [9,10(n)‐3H]16:0 FAlc, or [1‐14C]18:1n‐9 FA and [9,10(n)‐3H] 18:1n‐9 FAlc. Uptake was measured after 2 h with relative utilization of labelled FAlc and FA calculated as a percentage of uptakes. Differences in uptake were observed, with FA showing higher uptake than FAlc, and 18:1 chains a higher uptake than 16:0. A proportion of unesterified FAlc was possibly recovered in the cells, but the majority of FAlc was recovered in lipid classes such as TAG and phospholipids indicating substantial conversion of FAlc to FA followed by esterification. However, incorporation of FA and FAlc into esterified lipids was higher when derived from FA than from FAlc. Twenty‐five to fifty percentage of the absorbed 16:0 FA was recovered in TAG fraction of the enterocytes compared with 15–75% of 18:1 FA. Twenty to thirty percentage of the absorbed 16:0 FA was recovered in the phosphatidylcholine fraction of the enterocytes compared with only 5–15% of the 18:1 FA. Less than 15% of the fatty chains taken up by the cells were used for energy production, with significantly higher oxidation of 18:1 in enterocytes from fish fed the fish oil diet compared with the Calanus oil diet. However, overall, dietary copepod oil had little effect on FAlc and FA metabolism. Metabolic modification by elongation and/or desaturation was generally low at 1–5% of the uptake. We conclude that our hypothesis was generally proved in that the uptake of FAlc by salmon enterocytes was lower than the uptake of FA and that subsequent intracellular metabolism of FAlc was similar to that of FA. However, unesterified FAlc was possibly recovered in the cells suggesting that the conversion to FA may not be concomitant with uptake.  相似文献   

2.
To study how hepatic lipid turnover and lipid transport may be affected by complete replacement of dietary fish oil (FO) with a vegetable oil blend (VO) from start feeding until the adult stages, Atlantic salmon (Salmo salar L.) were fed either 100% FO‐ or 100% VO‐based diets (55% rapeseed oil, 30% palm oil and 15% linseed oil) from start feeding until 22 months. Liver and plasma lipoprotein lipid class levels and lipoprotein fatty acid composition were analysed through the seawater phase, whereas liver fatty acid composition, plasma cholesterol, triacylglycerol (TAG) and protein levels were analysed through both freshwater and seawater stages. Further, enzyme activity of liver fatty acid synthetase (FAS), NADH‐isocitrate dehydrogenase, malic enzyme, glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase and expression of the gene Peroxisome proliferator‐activated receptor γ (PPARγ) was analysed during both fresh water and seawater stages through the experiment. Dietary VO significantly increased salmon liver TAG and hence total liver lipid stores after 14 and 22 months of feeding. Further, after 22 months of feeding, plasma lipid levels and plasma low‐density lipoprotein (LDL) levels were significantly decreased in VO‐fed salmon compared with FO‐fed fish. The same trend, although not statistically significant, was seen for plasma very low‐density lipoprotein (VLDL). The activity of FAS was generally low throughout the experiment with the VO group having significantly lower activity after 16 months of feeding. The expression of PPARγ in livers increased prior to seawater transfer followed by a decrease, and then another increase towards the final sampling (22 months). Dietary vegetable oil replacement had no impact on PPARγ expression in salmon liver. In summary, liver TAG stores, plasma lipid and LDL levels were affected by dietary vegetable oil replacement in Atlantic salmon during a long–term feeding experiment. Current results indicate that high dietary vegetable oil inclusion increase hepatic TAG stores and decrease plasma lipid levels possible through decreased VLDL synthesis.  相似文献   

3.
Alternative marine resources from lower trophic levels could partly cover the rapidly increasing needs for marine proteins and oils in the future. The North Atlantic calanoid copepod, Calanus finmarchicus, has a high level of lipids rich in n‐3 fatty acids. However, these animals have wax esters as the main lipid storage component rather than triacylglycerol (TAG). Although these esters are considered difficult to digest by many fish, is it well known that juvenile Atlantic salmon (Salmo salar) feed on zooplankton species. It is therefore possible that the capacity to utilize these lipids should be well developed in salmonids. Nonetheless, salmon hydrolyse wax esters slower than TAG and absorb fatty alcohols slower than fatty acids. However, salmon have several adaptations to digest diets rich in wax esters. These includes increased feed conversion, higher production of bile and higher activity of lipolytic enzymes in the midgut. Atlantic salmon has been shown to feed and grow on diets with a medium amount of wax esters (30% of the lipid) with results comparable to fish maintained on fish oil diets. Ingestion of higher level of wax esters (50% of the lipid) cause, however, poorer lipid digestibility and growth, so that optimal utilization of wax esters in Atlantic salmon is closer to 30% than 50% of the dietary lipid.  相似文献   

4.
Against a background of decreasing availability of fish oils for use in aquaculture, the present study was undertaken to examine whether a wax ester-rich oil derived from the calanoid copepod Calanus finmarchicus, could be used effectively by Atlantic salmon when supplied in their diet. Individually tagged Atlantic salmon of initial weight around 500 g were divided into replicate tanks of two dietary groups and fed either a fish oil supplemented diet, or an experimental diet coated with Calanus oil. Wax esters accounted for 37.5% of the lipids in the Calanus oil diet but were absent from the fish oil diet in which triacylglycerols (TAG) were the major lipid class. Over the feeding period (140 days) the salmon fed fish oil displayed a greater increase in length, but there was no significant difference between the two groups in weight gained. The specific growth rates (0.75) and the feed conversion ratio of fish fed the two diets were similar throughout the study. No differences were observed in the apparent digestibility coefficients (ADC) of fish fed Calanus oil or fish oil. The ADC of fatty acids decreased with chain length and increased with unsaturation. Long-chain alcohol utilization showed a similar tendency although there was a notable difference in that saturated long-chain alcohols were utilized better than the comparable fatty acid homologue. In fecal lipid of fish fed Calanus oil, the content of 16:0 alcohol decreased in both the free long-chain alcohol and wax ester fractions, while the corresponding fatty acid increased in the feces of both dietary groups of fish. In contrast, the proportion of the 22:1n−11 alcohol increased in both fecal wax esters and free long-chain alcohol fractions whereas 22:1n−11 fatty acid displayed no accumulation. The observed patterns of fatty acid and long-chain alcohol compositions in fecal lipid compared to those of the initial dietary lipid are consistent with the digestive lipases of salmon preferentially hydrolyzing esters containing polyunsaturated fatty acid (PUFA) moieties. The wax esters of Calanus oil contained substantial amounts of the n−3 PUFA, 20:5n−3 and 22:6n−3, that were effectively deposited in muscle and liver tissues. No major differences were seen in either lipid content/lipid classes or in gross fatty acid composition of these tissues between the two dietary groups. It is concluded that that Atlantic salmon in seawater can effectively utilize diets in which a major lipid component is derived from zooplankton rich in wax ester without any detrimental change in growth or body lipid composition. This finding gives support to the use of lipid from zooplankton from high latitudes as an alternative or as a supplement to fish oil and a provider of long-chain n−3 PUFA in diets for use in salmon aquaculture.  相似文献   

5.
Copepod oil (CO) from the marine zooplankton, Calanus finmarchicus, is a potential alternative to fish oils (FOs) for inclusion in aquafeeds. The oil is composed mainly of wax esters (WE) containing high levels of saturated fatty acids (SFAs) and monounsaturated fatty alcohols that are poorly digested by fish at low temperatures. Consequently, tissue lipid compositions may be adversely affected in salmon‐fed CO at low temperatures. This study examined the lipid and FA compositions of muscle and liver of Atlantic salmon reared at two temperatures (3 and 12 °C) and fed diets containing either FO or CO, supplying 50% of dietary lipid as WE, at two fat levels (～330 g kg?1, high; ～180 g kg?1, low). Fish were acclimatized to rearing temperature for 1 month and then fed one of four diets: high‐fat fish oil (HFFO), high‐fat Calanus oil (HFCO), low‐fat fish oil (LFFO) and low‐fat Calanus oil (LFCO). The fish were grown to produce an approximate doubling of initial weight at harvest (220 days at 3 °C and 67 days at 12 °C), and lipid content, lipid class composition and FA composition of liver and muscle were determined. The differences in tissue lipid composition between dietary groups were relatively small. The majority of FA in triacylglycerols (TAG) in both tissues were monounsaturated, and their levels were generally higher at 3 °C than 12 °C. Polyunsaturated fatty acids (PUFA), particularly (n‐3) PUFA, predominated in the polar lipids, and their level was not significantly affected by temperature. The PUFA content of TAG was highest (～26%) in the muscle of fish fed the HFCO diet at both temperatures. Tissue levels of SFAs were lower in fish‐fed diets containing HFCO than those fed HFFO, LFFO or LFCO, particularly at 3 °C. The results are consistent with Atlantic salmon being able to incorporate both the FA and fatty alcohol components of WE into tissue lipids but, overall, the effects of environmental temperature on tissue lipids were more pronounced in fish fed the CO diets than FO diets.  相似文献   

6.
This study investigated effects of linseed or fish oil–enriched finishing diets on the polyunsaturated fatty acids (PUFA) composition in dorsal muscle tissues of pond‐cultured common carp (Cyprinus carpio). After 180 days of dietary exposure to cereal diet containing vegetable oil (1%), carp were exposed to 7% linseed (LO) or 7% fish oil–enriched (FO) finishing diets for 30 days. FO supplied 17 and 20 mg fish?1 day?1, respectively, of the long‐chain n‐3 fatty acids eicosapentaenoic and docosahexaenoic acid for 30 days and doubled long‐chain PUFA concentrations in carp of the FO pond. The increased supply of short‐chain PUFA in LO resulted in higher short chain, but not long‐chain PUFA, showing that there was very little PUFA conversion. Thus, dietary short‐chain PUFA could not compensate for the low levels of dietary long‐chain PUFA in LO. However, moderate supply of dietary long‐chain PUFA in finishing diets for 30 days is very efficient in increasing nutritionally important long‐chain PUFA concentrations in carp.  相似文献   

7.
The effects of stearidonic acid (SDA; 18:4n‐3) derived from SDA‐enhanced, genetically modified soybeans (Monsanto Company, St Louis, MO, USA) on growth performance and fatty acid (FA) composition of large Atlantic salmon (Salmo salar; 2.1 kg initial weight) were evaluated. There was a stepwise decrease in feed intake and subsequent weight gain of immature Atlantic salmon with increased replacement of fish oil by SDA soy oil from 0%, 50% to 100% added oil. SDA increased and n‐3 highly unsaturated FA (n‐3 HUFA; eicosapentaenoic acid + docosahexaenoic acid) decreased in the diet and corresponding fillet with increased SDA oil inclusion. Salmon with the same weight gain fed SDA oil compared with rapeseed oil at 50% fish oil replacement had similar n‐3 HUFA fillet levels indicating little or no increased synthesis of n‐3 HUFA from SDA for deposition in the fillet. However, elongation of dietary SDA to 20:4n‐3 for deposition in the fillet of SDA oil fed fish was indicated. The increased SDA and 20:4n‐3 in the fillet of Atlantic salmon fed SDA oil compared with rapeseed oil at 50% fish oil replacement may be more effective as precursors for EPA in humans than 18:3n‐3 which was in the fillet at similar levels.  相似文献   

8.
This study evaluated the potential for manipulating the fatty acid composition of juvenile red seabream, Pagrus auratus. Prior to the start of the study, three groups of fish had been reared for 3 months on a fish oil based diet or diets where the added fish oil had been replaced with either canola or soybean oil. In the present study, fish that had previously been fed either the canola or soybean oil diets were fed a fish oil based diet. Three additional treatments included fish being maintained on their original diets of fish oil, canola oil or soybean oil. Fish were fed their respective diets twice daily to apparent satiety for 32 days. Samples of fish from each treatment were collected after 0, 1, 2, 4, 8, 16 and 32 days. Composition and growth of the fish were determined at each sample point. Most treatments showed no differences in growth performance, although fish fed a fish oil diet after previously being fed a soybean oil diet showed slightly better growth. No significant differences among treatments were observed in proximate composition of the fish, although there was a significant increase in total fat and individual fatty acid (g kg?1 live‐weight) content of the fish from all treatments over the period of the study. No significant changes in the relative fatty acid composition (% of total fatty acids) over time were observed in the three treatments where fish were maintained on their original diets. In contrast, fish that were previously fed either the canola or soybean oil diets and were then fed a fish oil diet had significant changes in both the relative (% of total fatty acids) and absolute (g kg?1 live‐weight) fatty acid content. Key changes observed included a decrease in the relative levels of polyunsaturated fatty acids (PUFA) such as 18 : 2n ? 6 and 18 : 3n ? 3. Increases in the relative levels of the long‐chain polyunsaturated fatty acids (lcPUFA) 20 : 5n ? 3 and 22 : 6n ? 3 were also observed in both treatments. The rates of absolute (g kg?1 live‐weight) change/accumulation of these fatty acids followed an exponential equation that differed for each fatty acid in each treatment. Examination of the retention efficiency of specific fatty acids also showed marked differences between fatty acids within treatments and also differences between treatments. Biologically important fatty acids such as 20 : 5n ? 3 and 22 : 6n ? 3 had only moderate retention efficiencies and these were unaffected by treatment. In contrast, the retention efficiencies of 18 : 2n ? 6 and 18 : 3n ? 3 suggested selective retention of these fatty acids when fed fish oil diets, but moderate catabolism when fed the plant oil diets. There were also high retention efficiencies of most saturated and monounsaturated fatty acids suggestive of active retention and/or active synthesis of these fatty acids by the fish. The results of this study, particularly the increases in lcPUFA, support the usefulness of a fish oil based finisher diet for fish raised predominantly on plant oil based diets.  相似文献   

9.
The major aim of the current study was to evaluate the effect of substituting fish oil (FO) for a vegetable oil blend (VO) as dietary lipid source on lipid catabolism in Atlantic salmon (Salmo salar L.). The experiment endured from the start of feeding until the salmon reached 2.5 kg. Total and peroxisomal β‐oxidation capacities were determined in red and white muscle and liver. In addition, fatty acid productive value (FAPV) was calculated during the four time periods the experiment was divided into. In all the three tissues, an increased β‐oxidation capacity was found prior to seawater transfer; however, calculating the difference between the peroxisomal β‐oxidation capacity and the total, the peroxisomal β‐oxidation increased more than the mitochondrial β‐oxidation capacity. Hence, in liver and red muscle, 100%and 70%, respectively, of the total β‐oxidation capacity was accounted by peroxisomes prior to seawater transfer, compared with approximately 60% and 3% during the seawater phase. In contrast, white‐muscle mitochondria was the main organelle responsible for oxidizing fatty acids during the entire experiment (>90%). However, during the period of high energy demand (parr‐smolt transformation), fish fed VO exhibited significantly lower β‐oxidation capacity than fish fed FO, coinciding with low FAPV and low specific growth rate (SGR). Further, during periods of high growth rate, fish oxidized even essential fatty acids (18:2n‐6, 18:3n‐3, 20:5n‐3, and 22:6n‐3) when given in surplus. Low dietary levels of essential fatty acids gave significantly higher FAPV of these fatty acids in the whole body. However, the FAPV of 22:1n‐11 was low, indicating that this fatty acid is highly utilized as a substrate for β‐oxidation, irrespective of the dietary levels. There were no differences in whole lipid content between fish fed either FO or VO.  相似文献   

10.
The long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are produced by phytoplankton in the marine food web. Zooplankton acts as an important link between phytoplankton and fish at higher trophic levels and may therefore be a potential source for these fatty acids. The copepod Calanus finmarchicus is a lipid-rich zooplankton present in large amounts in the North Atlantic Ocean. The astaxanthin-rich oil contains 80–90 % wax esters consisting of mainly long-chain monounsaturated fatty alcohols esterified to saturated or unsaturated fatty acids. The long-chain n-3 fatty acids may account for 20–30% of the fatty acids in the wax esters. The wax ester rich oil is well utilized by fish, and the history of utilization, safety, and tolerability of wax esters for humans are being addressed. Recent reports indicate that oil from C. finmarchicus may have beneficial health effects beyond those which may be ascribed to intake of EPA and DHA alone.  相似文献   

11.
To date aquaculture’s reliance on dietary marine sources has been calculated on a fish weight‐to‐weight basis without considering the absolute amounts of nutrients but this approach neglects the often considerable differences in the nutritional value of fish. We propose simple nutrient‐to‐nutrient‐based dependency measures that take into account these nutritional differences. In the first study reported here, individually tagged Atlantic salmon (Salmo salar) were reared in seawater supplied tanks with feed collection facilities. In the second, commercial net pens were used to grow over 200 000 fish. For both studies, a low marine ingredient feed containing approximately 165 g kg?1 fishmeal was compared to a control feed (approx 300 g kg?1 fishmeal) whilst fish oil inclusion was less markedly reduced. The low marine feeds supported similar growth and feed efficiency compared to the control feeds. With the low marine ingredient feeds, the weight of salmon protein and lipid produced through growth exceeded the weight of marine protein and lipid consumed by the fish meaning that salmon farming can be a net producer of fish protein and oil. The amount of n‐3 long‐chain polyunsaturated fatty acids deposited was sufficient to meet current recommendations from human health organizations.  相似文献   

12.
Changes in fatty acid metabolism in Atlantic salmon (Salmo salar) induced by vegetable oil (VO) replacement of fish oil (FO) and high dietary oil in aquaculture diets can have negative impacts on the nutritional quality of the product for the human consumer, including altered flesh fatty acid composition and lipid content. A dietary trial was designed to investigate the twin problems of FO replacement and high energy diets in salmon throughout the entire production cycle. Salmon were grown from first feeding to around 2 kg on diets in which FO was completely replaced by a 1:1 blend of linseed and rapeseed oils at low (14–17%) and high (25–35%) dietary oil levels. This paper reports specifically on the influence of diet on various aspects of fatty acid metabolism. Fatty acid compositions of liver, intestinal tissue and gill were altered by the diets with increased proportions of C18 polyunsaturated fatty acids and decreased proportions of n-3 highly unsaturated fatty acids (HUFA) in fish fed VO compared to fish fed FO. HUFA synthesis in hepatocytes and enterocytes was significantly higher in fish fed VO, whereas β-oxidation was unaltered by either dietary oil content or type. Over the entire production cycle, HUFA synthesis in hepatocytes showed a decreasing trend with age interrupted by a large peak in activity at seawater transfer. Gill cell prostaglandin (PG) production showed a possible seasonal trend, with peak activities in winter and low activities in summer and at seawater transfer. PG production in seawater was lower in fish fed the high oil diets with the lowest PG production generally observed in fish fed high VO. The changes in fatty acid metabolism induced by high dietary oil and VO replacement contribute to altered flesh lipid content and fatty acid compositions, and so merit continued investigation to minimize any negative impacts that sustainable, environmentally-friendly and cost-effective aquaculture diets could have in the future. Abbreviations: FO - fish oil; HUFA - highly unsaturated fatty acids acids (carbon chain length ≥C 20 with ≥3 double bonds); LO - linseed oil; RO - rapeseed oil; VO - vegetable oil. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

13.
Six groups of Atlantic salmon, initial weight 142 ± 1 g, were fed increasing dietary inclusion of rapeseed oil (RO) in a regression design and one group was fed a 50% olive oil/50% capelin oil diet. Fatty acid composition was measured in red and white muscle, liver, and fatty acid and lipid class composition was measured in plasma and in the lipoproteins; very low density lipoprotein, low density lipoprotein, high density lipoprotein and nonlipoprotein fraction after 22 and 42 weeks of feeding. Further, the activities of liver NADH‐isocitrate dehydrogenase (ICDH), malic enzyme, glucose‐6‐phosphate dehydrogenase (G6PDH) and 6‐phosphogluconate dehydrogenase were measured at each sampling point. After 42 weeks of feeding the experimental diets, the tissue and lipoprotein fatty acid composition was highly affected by dietary fatty acid composition. Regressions showed that 22:1n ? 11, 18:1n ? 9, 18:3n ? 3 and 18:2n ? 6 are readily metabolized in all tissues analysed. Further, 20:5n ? 3 seems to be metabolized in muscle and retained in liver. 22:6n ? 3 was selectively retained in all the analysed tissues, and with higher retention in liver and plasma with higher polar lipid/neutral lipid ratio compared to white and red muscle. Liver from salmon fed 100% RO showed decreased G6PDH and increased ICDH activities compared to the other dietary groups; however, no linear relationship related to increased RO inclusion was detected. The amount of plasma lipoproteins, liver monoene fatty acid level and lipogenic enzyme activity decreased from the autumn to the winter sampling with concomitant decrease in temperature.  相似文献   

14.
A 12‐week feeding trial was conducted to investigate the interactive effects between water temperature and diets supplemented with different blends of fish oil, rapeseed oil and crude palm oil (CPO) on the apparent nutrient and fatty acid digestibility in Atlantic salmon. Two isolipidic extruded diets with added fish oil fixed at 50% and CPO supplemented at 10% or 25% of total added oil, at the expense of rapeseed oil, were formulated and fed to groups of Atlantic salmon (about 3.4 kg) maintained in floating cages. There were no significant effects (P>0.05) of diet on growth, feed utilization efficiency, muscle total lipid or pigment concentrations. Fatty acid compositions of muscle and liver lipids were mostly not significantly different in salmon fed the two experimental diets but showed elevated concentrations of 18:1n‐9 and 18:2n‐6 compared with initial values. Decreasing water temperatures (11–6°C) did not significantly affect protein, lipid or energy apparent digestibilities of the diets with different oil blends. However, dry matter digestibility decreased significantly in fish fed the diet with CPO at 25% of added oil. Increasing dietary CPO levels and decreasing water temperature significantly reduced the apparent digestibility (AD) of saturated fatty acids. The AD of the saturates decreased with increasing chain length within each temperature regimen irrespective of CPO level fed to the fish. The AD of monoenes and polyunsaturated fatty acids was not affected by dietary CPO levels or water temperature. No significant interaction between diet and water temperature effects was detected on the AD of all nutrients and fatty acids. The results of this study showed that the inclusion of CPO up to about 10% (wt/wt) in Atlantic salmon feeds resulted in negligible differences in nutrient and fatty acid digestibility that did not affect growth performance of fish at the range of water temperatures generally encountered in the grow‐out phase.  相似文献   

15.
Relative gene expression pattern of fatty acid transport proteins (FATP and cd36), intracellular fatty acid-binding proteins (FABP3, FABP10 and FABP11), β-oxidation-related genes [carnitine palmitoyl transferase II (CPTII), peroxisome proliferator-activated receptor β (PPARβ), acyl-CoA oxidase (AOX), long-chain fatty acyl-CoA synthetase (FACS), acyl-CoA dehydrogenase (dehydrogenase)] and uncoupling protein 2 (UCP2) was assessed by RT-qPCR in Atlantic salmon muscle (red and white), liver, heart, myosepta and visceral fat. FABP11, a FABP isoform not previously described in Atlantic salmon, was highly expressed in visceral fat and myosepta and at the lower level in red muscle, white muscle, myosepta and heart. Furthermore, Atlantic salmon were fed either a diet containing fish oil (FO) or a complete replacement of FO with a vegetable oil blend (55% rapeseed oil, 30% palm oil and 15% linseed oil; VO) for the production cycle (27 months from start of feeding and until ∼4.5 kg mean weight). The expression of genes related to β-oxidation, fatty acid uptake and transport in the white muscle indicate ( n  = 3) significant down-regulation in VO fed Atlantic salmon and correlated with previously reported white muscle triacylglycerol stores and β-oxidation. FABP11 in visceral fat and myosepta was also down-regulated in VO fed fish.  相似文献   

16.
We evaluated the effect of a diet containing insect meal and insect oil on nutrient utilization, tissue fatty acid profile and lipid metabolism of freshwater Atlantic salmon (Salmo salar). Insect meal and insect oil from black soldier fly larvae (Hermetia illucens, L.; BSF), naturally high in lauric acid (12:0), were used to produce five experimental diets for an eight‐week feeding trial. 85% of the dietary protein was replaced by insect meal and/or all the vegetable oil was replaced by one of two types of insect oil. A typical industrial diet, with protein from fishmeal and soy protein concentrate (50:50) and lipids from fish oil and vegetable oil (33:66), was fed to a control group. The dietary BSF larvae did not modify feed intake or whole body lipid content. Despite the high content of saturated fatty acids in the insect‐based diets, the apparent digestibility coefficients of all fatty acids were high. There was a decrease in liver triacylglycerols of salmon fed the insect‐based diets compared to the fish fed the control diet. This is likely due to the rapid oxidation and low deposition of the medium‐chain fatty acid lauric acid.  相似文献   

17.
High dietary content of vegetable oil (VO) has been associated with increased intestinal lipid accumulations in fish. The extent of this in aquacultured Atlantic salmon (Salmo salar L.) and its health effects are not certain. Samples were therefore collected from two separate feeding trials to investigate the effect of high dietary VO on intestinal lipid accumulations in Atlantic salmon. In the first trial, the fish were fed diets high in plant protein and with fish oil or ~80% of the fish oil replaced with either olive oil, rapeseed oil or soybean oil in a land‐based experimental set‐up. The second trial was performed in sea cages under commercial production conditions, and the fish were fed two dietary concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (9.7% or 5.5% EPA + DHA of total fatty acids). Neither dietary VO nor variations in EPA and DHA led to any significant effects on intestinal health or lipid accumulations. There were, however, indications of a delayed lipid transport in the rapeseed oil‐fed fish of the first trial, possibly caused by high dietary ≥18‐carbon fatty acids and low dietary 16:0 fatty acid and cholesterol.  相似文献   

18.
The effective implementation of a finishing strategy (wash‐out) following a grow‐out phase on a vegetable oil‐based diet requires a period of several weeks. However, fish performance during this final stage has received little attention. As such, in the present study the growth performance during both, the initial grow‐out and the final wash‐out phases, were evaluated in Murray cod (Maccullochella peelii peelii). Prior to finishing on a fish oil‐based diet, fish were fed one of three diets that differed in the lipid source: fish oil, a low polyunsaturated fatty acid (PUFA) vegetable oil mix, and a high PUFA vegetable oil mix. At the end of the grow‐out period the fatty acid composition of Murray cod fillets were reflective of the respective diets; whilst, during the finishing period, those differences decreased in degree and occurrence. The restoration of original fatty acid make up was more rapid in fish previously fed with the low PUFA vegetable oil diet. During the final wash‐out period, fish previously fed the vegetable oil‐based diets grew significantly (P < 0.05) faster (1.45 ± 0.03 and 1.43 ± 0.05, specific growth rate, % day−1) than fish continuously fed with the fish oil‐based diet (1.24 ± 0.04). This study suggests that the depauperated levels of highly unsaturated fatty acids in fish previously fed vegetable oil‐based diets can positively stimulate lipid metabolism and general fish metabolism, consequently promoting a growth enhancement in fish when reverted to a fish oil‐based diet. This effect could be termed ‘lipo‐compensatory growth’.  相似文献   

19.
Calanoid copepods are a rich source of marine lipid for potential use in aquafeeds. Copepod oil is primarily composed of wax esters (WE) and there are concerns over the efficiency of wax ester, versus triacylglycerol (TAG), digestion and utilization in fish. As smoltification represents a period of major physiological adaptation, the present study examined the digestibility of a high WE diet ( Calanus oil; 48% WE, 26% TAG), compared with a TAG diet (fish oil; 58% TAG), in Atlantic salmon freshwater presmolts and seawater postsmolts, of similar age (9 months) and weight (112 g and 141 g initial, respectively), over a 98-day period at constant temperature. Fish grew significantly better, and possessed lower feed conversion ratios (FCR), in seawater than freshwater. However, total lipid apparent digestibility coefficient (ADC) values were significantly lower in seawater fish, as were total fasted bile volumes. Dietary Calanus oil also had a significant effect, reducing growth and lipid ADC values in both freshwater and seawater groups. Postsmolts fed dietary Calanus oil had the poorest lipid ADC values and analysis of faecal lipid class composition revealed that 33% of the remaining lipid was WE and 32% fatty alcohols. Dietary prevalent 22:1n-11 and 20:1n-9 fatty alcohols were particularly poorly utilized. A decrease in primary bile acid, taurocholate, concentration was observed in the bile of dietary Calanus oil groups which could be related to the lower cholesterol content of the diet. The dietary WE : TAG ratio is discussed in relation to life stage and biliary intestinal adaptation to the seawater environment postsmoltification.  相似文献   

20.
Adult Atlantic salmon (Salmo salar; approximately 800 g start weight) were fed diets with a high replacement of fish meal (FM) with plant proteins (70% replacement), and either fish oil (FO) or 80% of the FO replaced by olive oil (OO), rapeseed oil (RO) or soybean oil (SO) during 28 weeks in triplicate. Varying the lipid source only gave non‐significant effects on growth and final weight. However, a significantly reduced feed intake was observed in the SO fed fish, and both feed utilization and lipid digestibility were significantly reduced in the FO fed fish. Limited levels of dietary 18:3n‐3, precursor to EPA and DHA, resulted in no net production of EPA and DHA despite increased mRNA expression of delta‐5‐desaturase and delta‐6‐desaturase in all vegetable oil fed fish. Net production of marine protein, but not of marine omega‐3 fatty acids, is thus possible in Atlantic salmon fed 80% dietary vegetable oil and 70% plant proteins resulting in an estimated net production of 1.3 kg Atlantic salmon protein from 1 kg of FM protein. Production of one 1 kg of Atlantic salmon on this diet required only 800 g of wild fish resources (Fish in ‐ Fish out < 1).  相似文献   

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