Article

Seven fish oil substitutes over a rainbow trout grow-out cycle: I) Effects on performance and fatty acid metabolism

September 2013
Aquaculture Nutrition 19(s1):82–94

DOI:10.1111/anu.12046

Authors:

Giovanni M Turchini

University of Melbourne

Karen Hermon

Deakin University, Warrnambool, Australia

Benjamin J Cleveland

University of Melbourne

James A Emery

Deakin University

Show all 6 authorsHide

A long-term feeding trial was implemented on rainbow trout (Oncorhynchus mykiss) to assess the effects of seven alternative oils on fish performance and fatty acid metabolism. The tested oils were as follows: monola (a high oleic acid canola cultivar; MO), canola (rapeseed; CO), poultry by-product (chicken fat; PbPO), palm (PO), sunflower (SFO), high oleic acid sunflower (HOSFO) and soybean (SBO). All tested oils were included at a 75% substitution level of fish oil (FO) and were compared with a control diet containing 100% FO. PO, and to a lesser extent PbPO, exhibited impaired performance and lower digestibility values. All treatments containing low levels of saturated fatty acids (namely MO, CO, SFO, HOSFO and SBO) recorded an apparent in vivo fatty acid de novo production. The apparent in vivo fatty acid b-oxidation was proportional to fatty acid dietary supply and limited apparent in vivo fatty acid bioconversion (elongation and desaturation) was recorded, primarily acting on n-6 PUFA. In all treatments, dietary 20:5n-3 was actively bioconverted into 22:6n-3. It was shown that when some FO is provided with the diet, the in vivo fatty acid metabolism plays a minor role in determining final fatty acid make-up of fish whole bodies.

Optimizing the fatty acid profile of novel terrestrial oil blends in low fishmeal diets of rainbow trout (Oncorhynchus mykiss) yields comparable fish growth, total fillet n-3 LC-PUFA content, and health performance relative to fish oil

Article

Jul 2021
AQUACULTURE

Identifying and effectively utilizing suitable, novel, terrestrial oil sources either alone or as blends to replace fish oil (FO) is a prerequisite for improving the sustainability of global aquaculture. Therefore, the present study evaluates several novel terrestrial oil blends (TOBs), optimized for their fatty acid profile, as alternatives to FO in low fishmeal diets fed to rainbow trout (Oncorhynchus mykiss) and describes the subsequent effects on fish growth, fatty acid composition and health. Insect oil (IO), genetically modified canola oil (CO), palm oil (PO) and linseed oil (LO) were used for the formulation of three TOBs viz., TOB-1 (30%IO+36%CO + 34%LO), TOB-2 (40%PO + 20%CO + 40%LO) and TOB-3 (50%TOB-1 + 50%TOB-2). Formulas TOB-1 and TOB-2 considered the total fatty acid profile based upon the general FO fatty acid profile, published fatty acid research for rainbow trout, and the fatty acid requirements of rainbow trout. A low fishmeal based basal diet containing 44% crude protein was formulated, and FO, TOB-1, TOB-2 and TOB-3 were incorporated in the basal diet to prepare the experimental diet groups, Control, TOB-1, TOB-2 and TOB-3, respectively. All experimental diets were fed to triplicate groups of rainbow trout juveniles (initial weight 7.9 ± 0.02 g) for 9 weeks. Growth performance (final weight, percent weight gain and specific growth rate) in TOBs fed groups were equal to the FO-based control group. Fish fed the TOB-3 diet consumed more feed followed by the control and TOB-1 diet groups. Significantly lower feed intake was observed in the TOB-2 diet group. Feed conversion ratio and protein efficiency ratio were not significantly influenced by dietary oil sources. Fish fed the control group showed significantly higher hepatic lipid content compared to TOB groups, followed by TOB-2, TOB-3, and TOB-1, which was significantly lower in hepatic lipid content. Muscle lipid content and whole-body major nutrient compositions were not significantly influenced by the dietary oil sources. Fatty acid composition of muscle and liver reflected that of the diets. Maximum values for n3 LC-PUFAs (EPA and DHA), lauric acid (C12:0) and C18:3n-3 were observed in the FO, TOB-1 and TOB-2 groups, respectively. Except for C12:0, muscle saturated fatty acid contents were significantly lower in TOBs-based diet compared to the FO-based control diet fish. As expected, muscle C12:0 content was significantly higher in the TOB-1 group followed by the TOB-3 group. TOB-2 and control groups had significantly lower content of C12:0. The fillet total n-3 LC-PUFA was significantly higher in fish fed the control diet group followed by TOB-3 and TOB-2 groups, TOB-1 showed significantly lower content of total n-3 LC- PUFA. Hepatic delta-5 desaturase (Δ5fad), delta-6 desaturase (Δ 6fad) and fatty acid elongase-2 (Elovl-2) gene expressions were significantly influenced by dietary oil sources, where TOB-based groups showed higher Δ6fad and Elovl-2 expressions. Measured innate immunity and antioxidant markers were not affected by TOBs. Finally, we concluded that TOBs could serve as a substitute for FO in rainbow trout feed without negatively impacting growth and health performance. Moreover, fillet total n-3 LC-PUFA of TOB-fed fish also satisfies the suggested dietary requirement of total n-3 LC-PUFA relative to the suggested daily serving for humans.

Are fish what they eat? A fatty acid's perspective

Article

Oct 2020
PROG LIPID RES

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.

Microalga Isochrysis galbana in feed for Trachinotus ovatus: effect on growth performance and fatty acid composition of fish fillet and liver

Article

Full-text available

Oct 2018
AQUACULT INT

Seeking alternatives to the depleting fish oil are crucial for marine fish aquaculture, which is currently dependent on fish oil as the primary source of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs). Five isonitrogenous (46% crude protein) and isolipidic (16% crude lipid) feed diets (FO, ISO2.9, ISO4.8, ISO6.7, ISO8.6) were formulated by partially replacing fish oil with microalgae Isochrysis galbana. These diets were fed to triplicate tanks of Trachinotus ovatus (mean initial weight 1.92 g) for 80 days. This work demonstrates that a moderate inclusion (around 4.5–5.0 wt%, equivalent to the replacement of 24–26 wt% fish oil) of I. galbana biomass in fish diet improves fish growth performance, lipid deposition and enhances total n-3 fatty acids, DHA, and EPA contents in neutral and polar lipids (PLs) of fish muscle and liver of T. ovatus. The results disclosed in this study suggest that I. galbana microalgae represents a potential high-quality substitute for fish-based ingredients in aquaculture feeds, which can be a promising sustainable solution to resolve the depleting fish oil resource in a cost-effective manner.

Fish Oil Replacement in Feeds for Juvenile Florida Pompano: Composition of Alternative Lipid Influences Degree of Tissue Fatty Acid Profile Distortion

Article

Mar 2016
AQUACULTURE

Effect of dietary saturated and monounsaturated fatty acids in juvenile barramundi Lates calcarifer

Article

Sep 2015

Barramundi (Lates calcarifer), a catadromous teleost of commercial interest, perform well when fed a wide range of dietary oils. However, the range of alternative oils now being explored is typically rich in saturated and monoun- saturated fatty acids (SFA and MUFA). In this study, the response of juvenile barramundi (47.0 g per fish initial weight) fed isolipidic and isoenergetic diets with 82 g kg1 added oil was tested. The experimental test diets had a 2 : 1 or 1 : 2 ratio of SFA to MUFA (SFA-D and MUFA-D, respectively) compared to a control diet (CTRL-D) fed for 8 weeks. The diets containing mostly olive oil (dietary MUFA-D) and mostly refined palm oil (dietary SFA-D) did not impact the growth performance or feed utilization parameters of the barramundi. The in vivo beta-oxidation activity was consistent with the dietary fatty acid composition, with the most dominant FA being heav- ily beta-oxidized. Together, the in vivo whole-body mass balance of fatty acids showed that n-3 long-chain polyun- saturated fatty acids (LC-PUFA) were most efficiently uti- lized in the SFA-D- and MUFA-D-fed fish. This study provides evidence that additional dietary MUFA and SFA are suitable lipid classes for juvenile barramundi and they are both equally efficient at sparing LC-PUFA from an oxidative fate.

Tallow in Atlantic salmon feed

Article

Feb 2014
AQUACULTURE

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.

Seven fish oil substitutes over a rainbow trout grow-out cycle: II) Effects on final eating quality and a tentative estimation of feed-related production costs

Article

Sep 2013

The effects of seven alternative oils on final product quality and production cost were assessed in rainbow trout (Oncorhynchus mykiss). The tested oils were as follows: monola (a high oleic acid canola cultivar; MO), canola (rapeseed; CO), poultry by-product (chicken fat; PbPO), palm (PO), sunflower (SFO), high oleic acid sunflower (HOSFO) and soybean (SBO). Tested oils were included at a 75% substitution level of fish oil and were compared with a control diet containing 100% fish oil (FO). Fillets of trout fed FO contained a 2.8-fold higher amount of EPA + DHA in comparison with fish fed the alternative oils, whilst the n-6/n-3 ratios varied from 0.2 in FO to 3.67 in SFO. Fillet pigmentation was highly affected by the different dietary treatments, as was the refrigerated product shelf-life. Fillets of trout fed FO recorded significantly higher lipid peroxidation at days 6 and 9 of refrigeration compared with the other treatments. The fillet flavour volatile compounds were significantly affected by the treatments, but no differences were detected by the panellists in the sensorial analysis. A discrepancy between production costs at ‘feed mill’ or ‘on-farm’ was recorded, suggesting that FO replacement may result in no real economic benefit.

Corrigendum to “DHA (22:6n-3) supplementation is valuable in Totoaba macdonaldi fish oil-free feeds containing poultry by-product meal and beef tallow” [Aquaculture 497 2018, 440-451/Article Number 633457]

Article

Oct 2019
AQUACULTURE

Combination of Dietary Ahiflower Oil and Equol Enhances Long‐Chain Polyunsaturated Fatty Acid Levels in Rainbow Trout Tissues

Article

Feb 2019

Equol and Ahiflower oil have been shown to increase either eicosapentaenoic acid (EPA, 20:5n‐3) or docosahexaenoic acid (DHA, 22:6n‐3) levels in tissues of rainbow trout when applied individually. Thus, we investigated whether the combination of an Ahiflower oil‐based diet and equol might increase both, EPA and DHA levels, in rainbow trout. Rainbow trout (87.1 ± 0.3 g) were fed with five diets for 8 weeks. A diet based on a blend of fish and vegetable oils (FV) served as a reference diet. The four experimental diets contained a blend of Ahiflower oil and vegetable oils (AV). The AV‐diets were supplemented with equol by 0.0%, 0.1%, 0.2%, and 0.3% DM of the diet (AV‐C, AV‐EQ1, AV‐EQ2, and AV‐EQ3). The dietary treatments did not affect growth performance of fish and chemical nutrient composition of the whole body samples. Fish fed with the equol diets showed dose‐dependently increased liver weights and 18:0 liver levels. The content of EPA showed no consistent pattern between tissues but all AV‐groups were characterized by higher liver EPA values than FV. DHA values of AV‐EQ2 and AV‐EQ3 were similar to FV in fillet, tended to be the highest in the whole body and were significantly higher in liver compared to FV. In contrast, mRNA steady state levels of fatty acyl desaturase 2a (delta‐6) [fads2a(d6)] were not affected by the dietary treatments. In conclusion, the combination of dietary Ahiflower oil and equol (0.2% and 0.3%) seems to affect the fatty acid metabolism of rainbow trout positively to increase DHA tissue levels.

DHA (22:6n-3) supplementation is valuable in Totoaba macdonaldi fish oil-free feeds containing poultry by-product meal and beef tallow

Article

Aug 2018
AQUACULTURE

A n-3 PUFA depletion applied to rainbow trout fry (Oncorhynchus mykiss) does not modulate its subsequent lipid bioconversion capacity

Article

Full-text available

Jan 2017

Nutritional strategies are currently developed to produce farmed fish rich in n -3 long-chain PUFA (LC-PUFA) whilst replacing fish oil by plant-derived oils in aquafeeds. The optimisation of such strategies requires a thorough understanding of fish lipid metabolism and its nutritional modulation. The present study evaluated the fatty acid bioconversion capacity of rainbow trout ( Oncorhynchus mykiss ) fry previously depleted in n -3 PUFA through a 60-d pre-experimental feeding period with a sunflower oil-based diet (SO) followed by a 36-d experimental period during which fish were fed either a linseed oil-based diet (LO) (this treatment being called SO/LO) or a fish oil-based diet (FO) (this treatment being called SO/FO). These treatments were compared with fish continuously fed on SO, LO or FO for 96 d. At the end of the 36-d experimental period, SO/LO and SO/FO fish recovered >80 % of the n -3 LC-PUFA reported for LO and FO fish, respectively. Fish fed on LO showed high apparent in vivo elongation and desaturation activities along the n -3 biosynthesis pathway. However, at the end of the experimental period, no impact of the fish n -3 PUFA depletion was observed on apparent in vivo elongation and desaturation activities of SO/LO fish as compared with LO fish. In contrast, the fish n -3 PUFA depletion negatively modulated the n -6 PUFA bioconversion capacity of fish in terms of reduced apparent in vivo elongation and desaturation activities. The effects were similar after 10 or 36 d of the experimental period, indicating the absence of short-term effects.

Retro-engineering the protein sparing effect to preserve n-3 LC-PUFA from catabolism and optimise fish oil utilisation: A preliminary case study on juvenile Atlantic salmon

Article

Oct 2016
AQUACULTURE

Viability of tallow inclusion in Atlantic salmon diet, as assessed by an on-farm grow out trial

Article

Sep 2015
AQUACULTURE

The effect of total replacement of fish oil with DHA-Gold® and plant oils on growth and fillet quality of rainbow trout (Oncorhynchus mykiss) fed a plant-based diet

Article

Mar 2015
AQUACULT NUTR

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.

Oils Derived from GM Crops as Sustainable Solutions to the Supply of Long-Chain Omega-3 for On-Growing Atlantic Bluefin Tuna (Thunnus thynnus L.)

Article

Full-text available

Nov 2022

Recently Camelina sativa, has been genetically modified to produce oils rich in omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), EPA (eicosapentaenoic acid) and EPA + DHA (docosahexaenoic acid). The aim of this study was to test the feasibility of using these novel sources of de novo EPA and EPA + DHA as substitutes for marine oil in feeds for juvenile Atlantic Bluefin tuna (ABT). The results showed the oils were practical sources of n-3 LC-PUFA which could potentially replace fish oil (FO) in feeds for ABT juveniles. Fish fed the test diets (ECO, EPA alone and DCO, EPA + DHA) displayed good growth performance, survival and feed utilisation approaching that of ABT fed the reference diet (MGK) containing marine fish oil with the rank order being MGK > DCO > ECO. The test diets showed positive effects, upregulating the expression of genes of major nuclear receptors and those of lipid metabolism including digestion, LC-PUFA synthesis and antioxidant pathways. The results indicated that the DCO feed containing both DHA and EPA performed better than the ECO feed with much lower DHA. However, feeds formulated with both these oils may still require supplementary DHA to satisfy the high requirement of ABT for this essential nutrient.

Fish Oil Replacement with Poultry Oil in the Diet of Tiger Puffer (Takifugu rubripes): Effects on Growth Performance, Body Composition, and Lipid Metabolism

Article

Full-text available

Sep 2022
AQUACULT NUTR

Booming fish farming results in relative shortage of fish oil (FO), making it urgent to explore alternative lipid sources. This study comprehensively investigated the efficacy of FO replacement with poultry oil (PO) in diets of tiger puffer (average initial body weight, 12.28 g). An 8-week feeding trial was conducted with experimental diets, in which graded levels (0, 25, 50, 75, and 100%, named FO-C, 25PO, 50PO, 75PO, and 100PO, respectively) of FO were replaced with PO. The feeding trial was conducted in a flow-through seawater system. Each diet was fed to triplicate tanks. The results showed that FO replacement with PO did not significantly affect the growth performance of tiger puffer. FO replacement with PO at 50-100% even slightly increased the growth. PO feeding also had marginal effects on fish body composition, except that it increased the liver moisture content. Dietary PO tended to decrease the serum cholesterol and malondialdehyde content but increase the bile acid content. Increasing levels of dietary PO linearly upregulated the hepatic mRNA expression of the cholesterol biosynthesis enzyme, 3-hydroxy-3-methylglutaryl-CoA reductase, whereas high levels of dietary PO significantly upregulated the expression of the critical regulatory enzyme of bile acid biosynthesis, cholesterol 7-alpha-hydroxylase. In conclusion, poultry oil is a good substitution for fish oil in the diets of tiger puffer. Poultry oil could replace 100% added fish oil in the diet of tiger puffer, without adverse effects on growth and body composition.

Partial Substitution of Fish Oil with Microalgae (Schizochytrium sp.) Can Improve Growth Performance, Nonspecific Immunity and Disease Resistance in Rainbow Trout, Oncorhynchus mykiss

Article

Full-text available

May 2022

The price of fish oil has reached a historical peak due to a consistent downward production trend, and therefore, the search for sustainable alternative sources has received great attention. This research was conducted to evaluate dietary micro-algae, Schizochytrium sp. (SC) as fish oil (FO) replacer in rainbow trout, Oncorhynchus mykiss. In the first trial, apparent digestibility coefficient (ADC) was 92.4% for dry matter, 91.4% for crude protein, and 94.2% for crude lipid in rainbow trout. In the second trial, six diets were formulated to replace FO at 0% (CON), 20% (T20), 40% (T40), 60% (T60), 80% (T80), and 100% (T100) with SC in the rainbow trout (3.0 ± 0.4 g, mean ± SD) diet. After eight weeks’ feeding trial, weight gain (WG), specific growth rate (SGR), and feed efficiency (FE) of fish fed the T20 diet were significantly higher than those of fish fed other diets (p < 0.05). However, there were no significant differences in these parameters among those of fish fed CON, T40, T60, and T80 diets. Lysozyme activity of fish fed the T20 diet was significantly higher than those of fish fed other experimental diets (p < 0.05). After 10 days of disease challenge testing with pathogenic bacteria (Lactococcus garvieae 1 × 108 CFU/mL), the cumulative survival rate of fish fed the T20 diet was significantly higher than those of fish fed the CON, T80, and T100 diets. Therefore, these results suggest dietary microalgae SC is well-digested and could replace up to 80% of fish oil in the diet of rainbow trout without negative effects on growth and immune responses.

Dietary phosphorus requirement for juvenile bighead carp (Aristichthys nobilis)

Article

Full-text available

Aug 2022
AQUACULT INT

A 60-day feeding trial was conducted to estimate the optimum phosphorus requirement of juvenile bighead carp (Aristichthys nobilis). Fish (initial body weight: 2.42 ± 0.08 g) were hand-fed with six isoproteic (437 g kg⁻¹) and isolipidic (68 g kg⁻¹) diets containing graded phosphorus levels (0.90, 4.40, 8.30, 11.90, 15.50, and 19.30 g kg⁻¹) thrice daily to apparent satiation. Each diet was randomly assigned to triplicate tanks, and each tank was stocked with 30 fish. The highest weight gain rate (WGR, 288.94%) and specific growth rate (2.28% day⁻¹) and the best feed conversion rate (FCR, 1.91) were recorded in fish fed 8.30 g kg⁻¹ phosphorus. The body composition analysis showed that the phosphorus contents in the whole body, muscle, vertebra, and plasma of fish fed the phosphorus-supplemented diets were higher than those of fish fed the control diet, whereas the phosphorus retention rate and crude lipid contents in the whole body and muscle presented the reverse results. The highest activity of lipase (41.97 U g⁻¹ prot) in the intestine was found in fish fed the diet with 11.90 g kg⁻¹ phosphorus. Further, the contents of total protein, albumin, and globulin in plasma were increased as dietary phosphorus levels ranged from 0.90 to 11.90 g kg⁻¹ and then decreased with further increased phosphorus levels. The highest contents of triglyceride (1.85 mmol L⁻¹) and total cholesterol (2.16 mmol L⁻¹) in plasma occurred at dietary phosphorus level of 0.90 g kg⁻¹. Broken-line model analysis based on WGR, FCR, and the phosphorus contents of the whole body and vertebra indicated that the optimal phosphorus requirements for juvenile bighead carp were 7.16, 9.02, 10.88, and 11.04 g kg⁻¹, respectively.

The omega‐3 sparing effect of saturated fatty acids: A reason to reconsider common knowledge of fish oil replacement

Article

Jul 2021

Fish oil (FO) is four times more expensive than it was 30 years ago, yet it remains the most economical source of eicosapentaenoic acid (20:5n-3, EPA), docosahexaenoic acid (22:6n-3, DHA) and other long-chain polyunsaturated fatty acids (LC-PUFA) for aquafeeds. Although most reduction fisheries are considered well-managed and sustainable, supplies are limited and subject to interannual fluctuations. To address this, as well as social and environmental pressures to limit marine-origin inputs, the aquaculture industry has engaged in a decades-long effort to reduce its reliance on FO. Initially, this effort was focused on identifying blends of lipids that could satisfy the essential fatty acid requirements of cultured species. It was discovered that some species—largely omnivores—were able to sufficiently synthesise LC-PUFA from C18 polyunsaturated fatty acids (C18 PUFA), such as 18:2n-6 and 18:3n-3 found in terrestrial lipids. For these species, replacing dietary FO was straightforward. Conversely, carnivorous species were found to exhibit insufficient capacity for bioconverting C18 PUFA into LC-PUFA. Whereas a certain amount of FO could be substituted without affecting growth or survival of these species, aggressive substitution or complete replacement with lipids lacking LC-PUFA predictably resulted in reduced performance. It is common knowledge that fish tissue composition is strongly and directly influenced by dietary fatty acid intake Whereas partial or complete FO replacement might not affect growth performance, the nutritional value of the resulting seafood is inevitably compromised by the loss of beneficial ‘omega-3’ content. Accordingly, LC-PUFA demand is now defined in terms of the amounts needed to (1) prevent nutritional pathology, (2) support optimal growth and performance, or (3) maintain desired levels of EPA and DHA in the resulting seafood. Farmed fish are routinely compared with their wild-caught equivalents—a unique onus associated with the ‘last wild food’—and consumers expect high levels of EPA and DHA in cultured seafood. Thus, the aquaculture industry finds itself in a ‘catch-22’ situation: feeding FO-based feeds ensures nutrient requirements and consumer expectations are satisfied; however, reliance on FO increases feed prices and draws the ire of sustainability-minded consumers. Consequently, nutritionists have devised various strategies to use less FO in aquaculture feeds while maintaining EPA and DHA levels in the resulting products.

Application of the fish oil-finishing strategy in a lean marine teleost, tiger puffer (Takifugu rubripes)

Article

Mar 2021
AQUACULTURE

A feeding trial was conducted to test the efficacy of the fish oil-finishing strategy in a lean marine teleost, tiger puffer (average initial body weight, 19.50 g). During the 50-day growing-out period, fish was fed diets differing only in supplemented lipid source (6% of dry dietary matter), namely, fish oil (FO), tiger puffer liver oil (TO), linseed oil (LO), soybean oil (SO), rapeseed oil (RO), palm oil (PO), and beef tallow (BT). In the fish oil-fishing period, all the fish were fed diet FO for 30 days. The results showed that the fish oil-finishing strategy restored the muscle DHA content in terrestrially sourced oil (TSO)-based groups to be 82.8–91.6% of that in fish fed fish oil continuously. Compared to DHA, muscle EPA was less easily retained during the growing-out period, but more easily restored during the fish oil-finishing period. Compared to muscle, the LC-PUFA contents in liver of tiger puffer were much lower and more difficult to restore by the fish oil-finishing strategy. LO, RO and BT resulted in significant growth reduction than FO at the end of growing-out period, but this reduction no longer existed at the end of the fish oil-finishing period. Compensatory effects of fish oil re-feeding were also observed for LC-PUFA deposition. Very little difference was observed in fish proximate composition, somatic parameters, and muscle texture among dietary groups during the whole feeding period, but the lipid metabolism-related biochemical parameters in the serum were significantly affected by diet. Liver oil of farmed tiger puffer can be used a suitable and safe lipid source for diets of tiger puffer, and beef tallow seems a better dietary lipid source for tiger puffer than other TSO in terms of easy restoration of LC-PUFA and growth by the fish oil-finishing strategy. In conclusion, the fish oil-finishing strategy had high efficiency in restoring LC-PUFA and growth of tiger puffer previously fed TSO-based diets.

Seasonal effects on growth and product quality in Atlantic salmon fed diets containing terrestrial oils as assessed by a long‐term, on‐farm growth trial

Article

Dec 2020

Seasonal changes in water temperature affect the utilization of dietary fatty acids in Atlantic salmon (Salmo salar L.). Furthermore, fatty acid profiles of terrestrial oils dictate their suitability in terms of provision of metabolic energy and final product quality. An on‐farm, growth trial of Atlantic salmon was conducted in Tasmania, Australia over the final year of grow‐out (323 days), consisting of a ‘summer phase’ and a ‘winter phase’. Poultry by‐product oil, canola oil and tallow were fed at high dietary lipid inclusion level (80%) to assess growth, fillet fatty acid composition and sensorial attributes. In the summer phase, the tallow diet appeared to provide added substrate for metabolic energy, potentially enhancing the deposition of n‐3 LC PUFA into the fillet, despite lower final weight and a reduced apparent lipid digestibility. Subsequent winter phase results suggested all diets adequately provided metabolic energy and fillet n‐3 LC PUFA concentrations were comparable. Additionally, this study highlights the importance of a well‐considered experimental design and subsequent statistical interpretation, for commercial scale, on‐farm feeding trials. Ultimately, this study demonstrates the importance of seasonally tailored diets for Atlantic salmon, using high terrestrial oil inclusion, under challenging Australian farming conditions.

Hepatic biochemical, morphological and molecular effects of feeding microalgae and poultry oils to gilthead sea bream (Sparus aurata) Hepatic biochemical, morphological and molecular effects of feeding microalgae and poultry oils to gilthead sea bream (Sparus aurata)

Article

Full-text available

Oct 2020
AQUACULTURE

The present work investigated how the combination of poultry oil with microalgae oils, rich in eicosapentaenoic acid and docosahexaenoic acid (ED diets) or n-6 docosapentaenoic acid and n-3 docosahexaenoic acid (DD diets) modulates hepatic lipid metabolism in gilthead sea bream juveniles. Diets were tested using two different fishmeal contents (15% and 7.5%) and compared against a fish oil-based diet (CTRL) and two negative control diets based on poultry oil as lipid source (PO diets). After 74 days of feeding, sea bream fed 15% FM ED or DD diets showed similar daily growth index to those fed CTRL, while those fed PO diets caused reduced growth. Fish livers reflected the highest contents in n-3 long-chain polyunsaturated fatty acids when fed CTRL, ED or DD diets, which down-regulated fas, scd-1a, fads2, lpl and cpt1, reducing hepatic lipid accumulation and hepatocytes size. In contrast, fish fed PO diets showed the lowest deposition of n-3 long-chain polyunsaturated fatty acids and the highest oleic acid in liver, leading with the highest hepatosomatic index due to increased liver lipids. Therefore, these fish revealed a severe hepatic steatosis associated with an increased expression of lipogenesis- related genes, particularly fas, lpl and sbrep1. Furthermore, PO diets seemed to activate desaturation pathways in fish livers, reflected by the highest accumulation of fatty acids that are products from desaturases and the highest fads2 and scd-1a expressions. The reduction of the dietary fishmeal content to 7.5% lowered fish growth, although hepatic lipid metabolism seemed to be more affected by FO replacement than FM replacement. Combining microalgae with poultry oil could be an alternative lipid and essential fatty acid source to fish oil in marine fish diets.

Growth Performance and Organoleptic Quality of Hybrid Grouper (Epinephelus fuscogutattus ♀ × Epinephelus lanceolatus ♂) Fed Palm-Oil Based Diets at Grow-Out Stage

Article

Full-text available

Sep 2020

The performance of crude palm oil (CPO)-based diets in the grow-out stage of hybrid grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) was examined in a net-seacage culture system. Isoproteic (50% crude protein) and isolipidic (16% crude lipid) experimental diets were formulated to replace fish oil (FO) at 25% increment level; 25CPO, 50CPO, 75CPO, and 100CPO. The FO-based diet was formulated to serve as a control treatment (100FO). Triplicate groups of hybrid grouper containing 30 fish per treatment were stocked in 15 cages and fed once daily. After 4 months of feeding trial, no significant differences (p>0.05) were observed in terms of growth performance, survival, feed utilization efficiency, body indices, fillet yield, and condition factor of fish fed different experimental diets. Except for total cholesterol, all parameters for blood analysis showed no significant differences (p>0.05) among the treatments. Findings from the organoleptic test showed that all fillets were well accepted by the consumers without any significant differences in their scores (p>0.05). In conclusion, CPO is an excellent source of lipid to replace fish oil in the grow-out diet for hybrid grouper, Epinephelus fuscoguttatus × Epinephelus lanceolatus.

Effects of dietary phosphorus level and stocking density on tiger puffer Takifugu rubripes: Growth performance, body composition, lipid metabolism, deposition of phosphorus and calcium, serum biochemical parameters, and phosphorus excretion

Article

Jul 2020
AQUACULTURE

An 8-week feeding trial was conducted to comprehensively investigate the effects of dietary phosphorus level and stocking density on tiger puffer. A 3 × 3 factorial design was used. The three dietary phosphorus levels were 0.68% (LP), 0.98% (MP), and 1.31% (HP) of dry matter, of which the available phosphorus level was 0.44%, 0.76%, and 1.06%, respectively. The three stocking density grades were 1.53 (LD), 2.30 (MD), and 3.06 (HD) kg m⁻³. The feeding trial was conducted in an indoor flow-through seawater system. Three replicate tanks were used for each group. The results showed that HP resulted in the highest growth rate. Higher dietary phosphorus levels reduced the whole-body lipid content, serum cholesterol contents, and hepatic mRNA expression of lipid metabolism-related genes such as ACACβ, DGAT1, and PPARα2. High stocking density levels reduced the growth rate and feed intake, but rarely affected other physiological parameters. Significant interactions were observed between effects of dietary phosphorus level and stocking density on phosphorus and calcium metabolism, but not between effects of both variables on the growth performance. Synergetic enhancement of phosphorus excretion by high phosphorus level and high stocking density was observed. These results shed new lights into the phosphorus physiology of marine fish and the interactions between phosphorus nutrition and rearing condition.

Effective complete replacement of fish oil by combining poultry and microalgae oils in practical diets for gilthead sea bream (Sparus aurata) fingerlings

Article

Jul 2020
AQUACULTURE

Few ingredients allow the complete replacement of fish meals (FM) and fish oils (FO) in aquaculture feeds without affecting fish performance or fillet nutritive value. This is due to the adequate content of essential nutrients, including the n-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA), and the unique high palatability of FM and fish oil. Some microalgae present abundant amounts of these fatty acids, for instance docosahexaenoic acid (DHA). Therefore, the aim of the present study was to evaluate the effect of two different microalgae products, one providing DHA and eicosapentaenoic acid (EPA, 20:5n-3; ED diet) and the other one DHA and n-6 docosapentaenoic acid (DPA, 22:5n-6; DD diet), in combination with poultry oil and rapeseed oil, as total replacers of fish oil, at two different dietary fish meal contents (15 and 7.5%). The effects of these dietary oil combinations on performance, composition and nutritive quality indexes of gilthead sea bream (Sparus aurata) juveniles were studied and compared against a positive control diet (FO) and two negative (PO diets) controls, one for each dietary fish meal content tested, giving in total 7 experimental diets. Both microalgae products in combination with poultry and rapseed oils were able to completely replace fish oil in practical diets with 15% FM without affecting growth performance, utilization of dietary fatty acids or the nutritional quality of fish fillet for the consumer. On the contrary, PO alone was not able to completely replace fish oil and negatively affected fish performance, in relation to an insufficient dietary n-3 LC-PUFA content. A similar decrease in growth performance was also observed with the reduction of the dietary FM content to 7.5%. In conclusion, both oils from microalgae, providing either DHA and EPA or DHA and n-6 DPA, were effective n-3 LC-PUFA sources for sea bream juveniles and allowed complete replacement of fish oil in combination with more cost-effective lipid sources, such as poultry and rapeseed oils.

FISH MEAL AND FISH OIL REPLACEMENT FOR AQUA FEED FORMULATION BY USING ALTERNATIVE SOURCES : A REVIEW

Article

Full-text available

Jan 2020

Aquaculture is fastest growing food producing sector in the world. It is contributing nearly half to the global food fish consumption. The total Indian fish production is estimated as 12.60 million metric tonnes, from which 65% is from inland sector and about 50% of total production is from culture. The total global aquaculture production reached up to 83.6 Mt. The growth of aquaculture increases tremendously in compare to capture fisheries. In the aquaculture production system feed represent major cost for growth and survival of fish. Fishmeal and fish oil are major proteinand lipid sources mainly used for feed formulation in the aquaculture feed industry. Nowadays, the supply of quantity of fishmeal and fish oil in aqua feed has been significantly decreases. This is mainly due to the less catch comes from capture fishery and ultimately results in increasing costs of fishmeal and fish oil.The price of fishmeal and fish oil has increased significantly to over US $ 1600 and US $900-1800 per Mt. So with the growing aquaculture industry, supply of fishmeal and fish oil cannot remain sustain. Therefore, we need to hour utilized the alternative protein and lipid sources for continue increases aquaculture production. This can replace shortage of fishmeal, fish oil and also maintain aquaculture industry. There are so many alternative protein and lipid sources easily available mainly from animal, plant origin and other sources. Which can replace the nutritional profile of fishmeal and fish oil without compromising growth rates and also available in much cheaper price in general market.

A systematic review and analysis of long-term growth trials on the effect of diet on omega-3 fatty acid levels in the fillet tissue of post-smolt Atlantic salmon

Article

Nov 2019
AQUACULTURE

Elucidating the specific effects of diet on the fatty acid composition in Atlantic salmon (Salmo salar), particularly health beneficial omega-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA), remains an area of intense commercial interest given the increasing market restrictions placed on the supply of fishmeal and fish oil. The present study conducted a systematic review and subsequent analysis of published nutritional data from long-term growth trials using post-smolt Atlantic salmon to provide a summary of currently available information and to identify the most significant drivers of omega-3 levels in Atlantic salmon fillet tissue. Overall, there were relatively few studies which met the selection criteria and this had implications for further explanation of some results. Statistically significant regression models were generated for fillet DHA and fillet n-3 LC PUFA. Fish weight was a significant predictor in both models, and dietary 22:6n-3 (DHA) was an intuitive predictor of fillet DHA. Furthermore, dietary EPA and dietary 22:1 isomers were significant predictors of fillet n-3 LC PUFA.

Reevaluating Polyunsaturated Fatty Acid Essentiality in Rainbow Trout

Article

Oct 2019

The National Research Council (NRC) reports the essential fatty acid requirements of Rainbow Trout Oncorhynchus mykiss can be satisfied by 0.7‐1.0% 18:3n‐3 or 0.4‐0.5% n‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA; defined by NRC as 20:5n‐3 + 22:6n‐3) in the diet. These requirements were defined roughly 50 years ago and do not consider the importance of n‐6 polyunsaturated fatty acids in the diet. Therefore, we assessed survival, growth performance, and tissue fatty acid composition of juvenile Rainbow Trout (24.6 ± 0.1 g initial weight [mean ± SE]; 10 fish/tank, 4 tanks/diet) fed experimental diets (~53% protein, ~13% lipid) that contained fish oil, fully hydrogenated soybean oil, or fully hydrogenated soybean oil with five different combinations of fatty acid ethyl esters (18:2n‐6, 18:3n‐3; 20:4n‐6, 20:5n‐3 and 22:6n‐3) to illuminate the relative essentiality of n‐3 and n‐6 PUFA. Final individual weight (78.2 – 132 g), weight gain (216 – 433%), feed conversion ratio (0.93 – 1.42), specific growth rate (2.05 – 2.98 % body weight/day), and hepatosomatic index (1.4 – 2.1) were significantly affected by dietary treatment whereby trout fed the fish oil‐based diet outperformed all other treatments. Growth of fish fed different combinations of fatty acid ethyl esters were not statistically different. Fatty acid tissue composition generally reflected dietary treatment with the greatest profile change seen in intraperitoneal fat, fillet, and liver and smallest in brain and eye tissues. Results largely validate previous reports that indicate Rainbow Trout are physiologically able to synthesize LC‐PUFA from C18 PUFA and therefore do not necessarily require LC‐PUFA‐rich feeds. However, numeric increases in growth of Rainbow Trout suggest this species may achieve an energetic advantage if offered n‐3 and n‐6 LC‐PUFA in the diet.

Total replacement of dietary fish meal with black soldier fly (Hermetia illucens) larvae does not impair physical, chemical or volatile composition of farmed Atlantic salmon (Salmo salar L.)

Article

Full-text available

Oct 2019

Background: The aquafeed sector has been replacing conventional dietary ingredients with more economic and eco-friendly ingredients. Insects embody a promising alternative as a result of being highly nutritious and showing traits leading to a circular bioeconomy. Atlantic salmon (Salmo salar L.) at the sea-water stage were fed diets with a partial or complete substitution of fishmeal with meal of Hermetia illucens larvae reared on a media containing Ascophyllum nodosum mixed with organic wastes (60:40). The present study aimed to assess the quality of fillets by characterizing its physico-chemical traits with conventional and innovative methods, such as the proton transfer reaction-time of flight-mass spectrometer technique, allowing the analysis of samples at room temperature. Finally, steamed fillets underwent a consumer test to investigate the liking of consumers and their intention of re-consumption. Results: The main findings showed that a complete dietary substitution of fishmeal with H. illucens larvae meal did not impair the physico-chemical quality of A. salmon fillets. Notably, neutral n-3 polyunsaturated fatty acids (PUFA) slightly but significantly increased in the fillets of A. salmon fed H. illucens, also as a result of the additional fish oil present in the diets containing insect. The volatile organic profile was not altered by the different diets. The consumer-liking test revealed that Italian consumers appreciated the tested salmon irrespective of the administered feed. Conclusion: Tailoring the insect fatty acid profile by rearing the larvae on a PUFA-rich substrate, coupled with a dietary modulation of the oily source, can successfully maintain or even increase the cardioprotective characteristics of fillets. © 2019 Society of Chemical Industry.

Response of European seabass (Dicentrarchus labrax) to canola oil diets: Effect on growth performance, fish health and liver and intestine Histomorphology

Article

Full-text available

Jan 2016
AQUACULT INT

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

Endogenous biosynthesis of n-3 LC PUFA in Atlantic salmon

Article

Full-text available

Mar 2019

A more efficient utilisation of marine derived sources of dietary omega-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA) in cultured Atlantic salmon (Salmo salar L.) could be enhanced by nutritional strategies that maximise endogenous n-3 LC PUFA synthesis. The objective of the present study was to quantify the extent of n-3 LC PUFA biosynthesis and the resultant effect on fillet nutritional quality in large fish. Four diets were manufactured providing altered levels of dietary omega-3 substrate, namely 18:3n-3, and end-products, namely, 20:5n-3 and 22:6n-3. After 283 days of feeding, fish grew to in excess of 3000g and no differences in growth performance or biometrical parameters were recorded. An analysis of fatty acid composition and in vivo metabolism revealed that endogenous production of n-3 LC PUFA in fish fed a diet containing no added fish oil resulted in fillet levels of n-3 LC PUFA comparable to fish fed a diet with added fish oil. However, this result was not consistent among all treatments. Another major finding of this study was the presence of abundant dietary omega-3 substrate with the addition of dietary omega-3 end- product (i.e. fish oil) served to increase final fillet levels of n-3 LC PUFA. Specifically, preferential oxidation of dietary C18 n-3 PUFA resulted in conservation of n-3 LC PUFA from catabolism. Ultimately, this study highlights the potential for endogenous synthesis of n-3 LC PUFA to, partially, support a substantial reduction in the amount of dietary fish oil in diets for Atlantic salmon reared in seawater.

Dietary Buglossoides arvensis Oil as a Potential Candidate to Substitute Fish Oil in Rainbow Trout Diets

Article

Oct 2018

The utilization of vegetable oils in salmonid diets substantially decreased the body content of omega‐3 long‐chain polyunsaturated fatty acids (n‐3 LC‐PUFA), and thus the product quality for human consumption. Therefore, new ingredients for aquaculture feeds are needed that maximize the deposition of health‐promoting n‐3 LC‐PUFA. This study investigated Buglossoides arvensis (Ahiflower) oil, a plant oil rich in alpha‐linolenic acid (18:3n‐3, ALA) and stearidonic acid (18:4n‐3, SDA), as a source of n‐3 fatty acids in rainbow trout (Oncorhynchus mykiss) nutrition. Rainbow trout (87.4 ± 0.6 g) were fed for 56 days. The oils of the control diet (FV) were substituted by Ahiflower oil at 33%, 66%, and 100% (A33, A66, A100). Dietary Ahiflower oil increased the final body weights of fish. mRNA steady state levels of fatty acyl desaturase 2a (delta‐6) (fads2a(d6)) and 2b (delta‐5) (fads2b(d5)) as well as carnitine palmitoyl transferase 1 a (cpt1a) were not altered by dietary treatments. In contrast, cpt1c mRNA steady state levels were significantly downregulated in samples of fish fed A66 and A100. Significantly higher eicosapentaenoic acid (20:5n‐3, EPA) and docosahexaenoic acid (22:6n‐3, DHA) levels were found in the liver and significantly higher EPA levels in the fillet of rainbow trout of A66 and A100 compared to FV. The content of DHA in fillets of fish fed Ahiflower oil was not significantly different to fish fed FV. Thus, high dietary amounts of Ahiflower oil can compensate for reduced dietary EPA and DHA levels.

Altered levels of shorter vs long-chain omega-3 fatty acids in commercial diets for market-sized Atlantic salmon reared in seawater – Effects on fatty acid composition, metabolism and product quality

Article

Sep 2018
AQUACULTURE

There is a growing trend of ‘replacing’ long-chain omega-3 polyunsaturated fatty acid (n-3 LC PUFA) rich oils with C18 shorter-chain omega-3 polyunsaturated fatty acid rich oils in Atlantic salmon aquafeed formulations. n-3 LC PUFA, including 20:5n-3 and 22:6n-3, play contrasting physiological roles and are metabolised differently in comparison to C18 PUFA. Accordingly, the present study recorded the effect of replacing n-3 LC PUFA rich dietary fish oil with C18 n-3 PUFA rich camelina oil at two inclusion levels in commercial-like diets fed to market-sized Atlantic salmon. This assessment was achieved by an analysis of industry relevant production parameters including growth performance, fatty acid composition and metabolism, nutrient digestibility and consumer acceptance (liking and attribute analysis of fillet). The trial was conducted over the final 150 days of an on-farm grow-out period in seawater. The dietary replacement of n-3 LC PUFA with C18 n-3 PUFA resulted in a significant decrease in fillet n-3 LC PUFA and a poorer growth performance. However, in the absence of fish oil, the inclusion of camelina oil at high levels (40 %) contributed to an improved n-6/n-3 ratio and partially ameliorated low dietary n-3 LC PUFA by providing added substrate for endogenous n-3 LC PUFA synthesis in comparison to a 20% camelina oil inclusion. Furthermore, consumer acceptance of Atlantic salmon was unaffected by the dietary addition of camelina oil.

A blend of land animal fats can replace up to 75% fish oil without affecting growth and nutrient utilization of European seabass

Article

Dec 2017
AQUACULTURE

Animal fats of terrestrial origin are often by-products from agro-food industries that could be valuable sustainable sources of lipids for aquafeeds. Four diets were hence tested in European seabass (Dicentrarchus labrax) juveniles (initial body weight, 20 g): a control diet with fish oil (FO) and three diets where a blend of poultry and mammal fats (50:50) replaced 50, 75 and 100% of the supplemental fish oil (50PFMF, 75PFMF and 100PFMF). All diets were isoproteic (51% dry matter, DM) and isoenergetic (23 kJ g− 1 DM). After 114 days of feeding the experimental diets, the apparent digestibility coefficients (ADCs) of nutrients were determined and fish growth performance evaluated. Postprandial plasma metabolites and muscle fatty acid profile were determined. Liver was also sampled for histologic evaluation and determination of lipogenic enzymatic activity. Protein and energy ADCs were not affected by the dietary treatments, but lipid ADC was lowest in the diet devoid of fish oil (100PFMF). Replacement of fish oil by a blend of land animal fats did not affect daily growth index, feed conversion ratio or nutrient utilization. Whole body composition remained unaffected by dietary treatments, but there was a significant increase in the hepatosomatic index of fish fed 100PFMF. Total replacement of fish oil by PFMF resulted in increased hepatic vacuolation, apparent steatosis and compromised glycogen deposition. Malic enzyme activity was lowest in fish fed 100PFMF. A significant reduction of muscle eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) content was observed with decreasing levels of dietary fish oil. Results indicate that juvenile seabass can effectively use diets with high levels of land animal fats as alternative lipid source, up to 75% fish oil replacement, without impairing nutrient intake, growth performance and nutrient utilization. Despite alteration in the muscle fatty acid profile, European seabass fed up to 75% PFMF can still retain high levels of EPA + DHA in the muscle (> 0.3 g/100 g).

A Mammal And Poultry Blend Can Replace Up To 75% Fish Oil In Diets For Dicentrarchus labrax Without Impacting Growth Performance And Nutrient Utilization

Poster

Oct 2017

This study aimed to assess the effects of replacing fish oil by increasing levels of a blend of poultry and mammal fat (lard and beef tallow, 70:30) in European sea bass growth performance, nutrient utilization, whole-body composition and tissue lipid deposition as well as liver histological evaluation and the fatty acid profile of muscle.

Addition of Emulsifiers to Hydrogenated Soybean Oil-Based Feeds for Yellowtail

Article

Dec 2017

Hydrogenated soybean oil can be used to spare fish oil in aquafeeds, but lipid digestibility may be a limiting factor. We evaluated the performance and tissue fatty acid composition of juvenile Yellowtail Seriola dorsalis that were fed diets containing menhaden fish oil (positive control), hydrogenated soybean oil (negative control), or hydrogenated soybean oil amended with 1% mixed bile acids, casein, whey protein, or monoglycerides as emulsifying agents. Juvenile fish (~10 g) were stocked in a semi-closed recirculation aquaculture system (15 fish/tank), diets were randomly assigned to tanks in triplicate (N = 3), and fish were fed in slight excess of estimated apparent satiation amounts for 6 h/d with belt feeders. After 8 weeks, production performance was equivalent for fish fed the positive control and negative control feeds; amending the hydrogenated soybean oil-based feeds with casein, whey protein, or monoglycerides did not affect performance, whereas adding mixed bile acids significantly impaired performance (weight gain = 655–681% versus 459%; survival = 98–100% versus 49%; feed conversion ratio = 1.19–1.22 versus 1.56). Whole-body fatty acid composition tended to mirror dietary composition except that fish receiving the hydrogenated soybean oil-based feeds exhibited disproportionately lower levels of saturated fatty acids and higher levels of monounsaturated fatty acids, long-chain polyunsaturated fatty acids, and n-3 and n-6 fatty acids compared to dietary levels. Results suggest that casein, whey protein, and monoglycerides could be added to saturated fatty acid-rich hydrogenated soybean oil-based diets to reduce tissue fatty acid profile distortion, but production performance might not be enhanced. Of all the hydrogenated soybean oil-based feeds in this study, the one supplemented with casein resulted in a whole-body fatty acid profile closest to that of fish fed the fish oil-based feed. Mixed bile acids should not be added due to the resulting negative impacts on survival and growth.

Anti-obesity effects of Lipid Extract from Sea-reared of Rainbow Trout (Oncorhynchus mykiss) Fed with Sea Squirt (Halocynthia roretzi) Tunic's Carotenoids and CLA

Article

Full-text available

Jan 2016

Purpose: In order to produce new functional seafood, rainbow trout were acclimation in seawater and fed with inclusion of CLA and carotenoid extract from sea squirt tunic. Lipid extract from the sea-reared rainbow trout muscle (RME) and viscera (RVE) were administered to rats simultaneously with normal or high fat diet for six weeks. We evaluated the effects of the dietary supplementation with CLA, carotenoids, and n-3 HUFA by the beneficial effects of anti-obesity activities. Materials and method: Sea-reared rainbow trout (800 ± 20.5 g; 40.0 ± 1.7 cm) were fed with basal feed which supplemented with 10 mg/kg sea squirt tunic’s carotenoids and 3% CLA (w/w) for three months. Lipid was extracted from rainbow trout muscle and viscera using chloroform/methanol (2/1). Forty eight male Sprague Dawley rats (400 ± 2.0 g) were randomly divided into six groups (n=8). Two types of diets, normal types (SN, RVN, RMN) and 45% of high fat research diets (SHF, RVHF, RMHF) were used. The excised liver and epididymal adipose tissues were fixed in 3% formaldehyde solution, embedded in paraffin. Organs sections were stained with hematoxylin-esosin. Histological examination on liver and adipose tissues sections were carried out with a light microscope. Results: Sea farming and inclusion of CLA and carotenoids pigment extracted from the tunic of sea squirt, the content of C18:1n-9 was reduced to 32.5% in the muscle’s lipid and 35.8% in the viscera’s lipid. Serum lipid and liver enzymes activity in blood serum showed that RME and RVE have the liver protective ability. Conclusion: RME and RVE have potency as weight reducer through fat burner routes as well as liver protective ability. Hence, it could be considered as anti-obesity supplement for the long period of administration.

The effect of marine and non-marine phospholipid rich oils when fed to juvenile barramundi (Lates calcarifer)

Article

Jan 2016
AQUACULTURE

Effects of Fish Oil Sparing on Fillet Fatty Acid Composition in Hybrid Striped Bass Are Influenced by Dietary Levels of Saturated and Unsaturated Fatty Acids

Article

Mar 2015
N AM J AQUACULT

We assessed the growth performance and fillet fatty acid composition of hybrid Striped Bass (White Bass Morone chrysops × Striped Bass M. saxatilis; initial weight = 29.1 ± 0.2 g [mean ± SE]) fed diets containing only menhaden fish oil (100 FISH); fully hydrogenated saturated fatty acid (SFA)-rich soybean oil (100 SFA SOY); 75:25, 50:50, 25:75, or 0:100 blends of fish oil and standard C18 polyunsaturated fatty acid (C18 PUFA)-rich soybean oil (25 PUFA SOY, 50 PUFA SOY, 75 PUFA SOY, 100 PUFA SOY); or nonhydrogenated monounsaturated fatty acid (MUFA)-rich soybean oil (25 MUFA SOY, 50 MUFA SOY, 75 MUFA SOY, 100 MUFA SOY) for 8 weeks. Feed conversion ratio varied, with the 100 SFA SOY feed yielding a significantly greater value (1.3) than the rest of the feeds (0.9–1.0). Although significant treatment effects were not observed for weight gain, specific growth rate, feed intake, or organosomatic indices, some variation was observed, suggesting some minor (albeit not significant) loss of growth performance among fish fed the 100 SFA SOY and, to a lesser extent, 100 MUFA SOY feeds. Fillets of fish fed diets containing soybean-derived lipids had reduced levels of fish-oil-associated, n-3 long-chain polyunsaturated fatty acids (LC-PUFAs, i.e., 20:5[n-3] and 22:6[n-3]) compared with those fed the 100 FISH feed. Conversely, fillets of fish fed diets containing C18 PUFA-rich soybean oil and nonhydrogenated MUFA-rich soybean oil had higher levels of these fatty acids (i.e., 18:2[n-6] and 18:1[n-9], respectively). Although the 100 SFA SOY diet contained substantially more SFAs (i.e., 18:0) than the other diets, these fatty acids were not proportionally elevated in the fillets. It is possible that blending SFA-rich lipids with ingredients containing some level of unsaturated fatty acids may be a means of addressing digestibility limitations while still mitigating the effects of fish oil sparing on tissue composition.

Towards achieving circularity and sustainability in feeds for farmed blue foods

Article

Nov 2022

The aims of this review are to describe the role of ‘blue‐food production’ (animals, plants and algae harvested from freshwater and marine environments) within a circular bioeconomy, discuss how such a framework can help the sustainability and resilience of aquaculture and to summarise key examples of novel nutrient sources that are emerging in the field of fed‐aquaculture species. Aquaculture now provides >50% of the global seafood supply, a share that is expected to increase to at least 60% within the next decade. Aquaculture is an important tool for reducing resource consumption in global protein production and increasing resilience to climate change and other global disruptions (i.e. pandemics, geo‐political instability). Importantly, blue foods also provide essential nutrition for a growing human population. Blue foods are helping to help the global goal of ‘zero hunger’ (United Nation's Sustainable Development Goal 2) while reducing the dependency on finite natural resources but further refinement and new solutions are needed to make the industry more ‘circular’ and sustainable, particularly with respect to sourcing raw materials for aquafeeds. This review describes the feed resources that are available or may be created within a circular bioeconomy framework, their role within the framework and in aquaculture and ultimately, how these resources contribute to de‐risking and establishing a resilient aquaculture production chain.

Fish oil replacement by beef tallow in juvenile turbot diets: Effects on growth performance, body composition and volatile flavor compounds in the muscle

Article

Nov 2022
AQUACULTURE

A 12-week feeding trial was conducted to evaluate the effects of dietary fish oil (FO) replacement by beef tallow (BT) on the growth performance and body composition of juvenile turbot (average initial weight, 19.6 g). The control diet contained 6% added FO (of dry matter, Diet FO-C). Beef tallow was supplemented into Diet FO-C, replacing added FO at different levels, i.e., 25%, 50%, 75%, and 100%, formulating the other 4 experimental diets, designated as 25BT, 50BT, 75BT, and 100BT, respectively. The feeding trial was conducted in a flow-through seawater system. Each diet was randomly fed to triplicate tanks (30 fish in each tank). The results showed that a cubic regression relationship was observed between weight gain and dietary FO replacement level. Although total FO replacement by BT significantly reduced the growth of juvenile turbot, no significant difference was observed between FO-C and 75BT. Diet BT decreased the whole-body crude lipid content but increased the whole-body moisture and ash contents. Dietary BT regulated the proximate composition of fish tissues in a dose dependent manner. High dietary BT levels did not reduce the n-3 long-chain polyunsaturated fatty acid content (% total fatty acid) in the muscle. Partial FO replacement (25 and 50%) by BT even significantly increased the muscle DHA content. The fatty acid composition of the liver, subcutaneous adipose tissue around the fin, and intestine generally reflected those of the diets. No significant difference was observed in muscle and liver mitochondrial DNA copy number among groups, indicating the similar general energy supply status. Dietary BT significantly reduced the concentration of triacylglycerol, cholesterol and malondialdehyde in the serum. The volatile flavor compound in muscle was analyzed with gas chromatography-ion migration spectrometry (GC-IMS). Dietary BT resulted in lower number and abundance of flavor aldehydes and alcohols in the muscle. In conclusion, beef tallow can replace 75% added fish oil (appr. 45% of total fish oil including the residual fish oil in fishmeal) in the diets of turbot, without reducing fish growth. Dietary beef tallow significantly affected the body composition and volatile flavor compound composition in the muscle.

The Use of Rubber Seed Oil as an Alternative Plant Lipid Source for Stripped Catfish (Pangasianodon hypophthalmus) Diet

Article

Full-text available

May 2021

Dietary lipid in the forms of fish oil and corn oil are known as the best lipid sources. An effort to find an alternative to lipid sources other than both forms of oil can be done through the use of ts rubber seed oil. The study was conducted to evaluate rubber seed oil as a lipid source in the diet for increasing the growth of striped catfish (Pangasianodon hypophthalmus) fingerlings. A tested diet having isoprotein (30.14±0.01%) and isoenergy (271.26±0.08 DE kcal/100g) was used in this study. Fish oil, corn oil, and rubber seed oil at a total of 3% were used as the diet's lipid sources. Rubber seed oil was added to the diet at 0, 1, and 3%, respectively. After acclimatized to the experimental condition, striped catfish fingerlings (9.72±0.01 g) were randomly stocked in 12 aquariums (69x29x35 cm3; Volume 50 L) with a density of 15 fingerlings/container and fed on the tested diet at satiation for 40 days. The use of rubber seed oil as a source of lipid in the diet does not affect the survival rate and body fat (P> 0.05). The composition of 2% rubber seed oil in the feed gives the best growth in striped catfish fingerlings, with feed intake of 233.00±1.00 g, a specific growth rate of 2.01±0.05% day-1, feed efficiency of 75.45 ± 1.18%, protein efficiency ratio of 2.45 ± 0.11% and body protein of 44.03 ± 2.42%. There is a tendency that higher rubber seed oil content in the diet, produce better the fatty acid profile in the body of the striped catfish.

Evaluation of Spirulina and plant oil in diets for juvenile steelhead (Oncorhynchus mykiss)

Article

Jun 2020
AQUACULTURE

As diets fed to juvenile steelhead (progeny of anadromous rainbow trout, Oncorhynchus mykiss) reared in conservation hatcheries contain relatively high levels of protein and lipid supplied primarily by fish meal and fish oil, a 12-week feeding trial was conducted to evaluate alternative ingredients for this species. Using a factorial design, Spirulina meal and a plant oil mixture were evaluated as partial or complete replacements of dietary fish meal and fish oil, respectively. Thus, two diets containing 0 or 50% substitution of Spirulina for fish meal were extruded and top-coated with fish oil or a 63:37 mixture of canola and flaxseed oils. Each of the four dietary treatments was fed to quadruplicate groups of 100 steelhead initially weighing 12.4 g/fish. Steelhead growth rate and feed efficiency were not significantly affected by partial replacement of dietary fish meal with Spirulina, but growth responses were significantly reduced by replacement of dietary fish oil with plant oil. Lipid and protein apparent digestibility coefficients (ADC) were significantly higher in steelhead fed the fish meal diets compared with fish fed the Spirulina diets and significantly higher in steelhead fed the plant oil diets compared with fish fed the fish oil diets. Whole body fatty acid profiles generally reflected those of the diets such that percentages of 18:2n-6 were significantly higher and n-3 polyunsaturated fatty acids (PUFA), including 20:5n-3 and 22:6n-3, were significantly lower in fish fed the Spirulina and plant oil diets compared with those fed the fish meal and fish oil diets. Plasma total cholesterol concentration was significantly reduced in fish fed the Spirulina diets and in fish fed the plant oils diets. Growth results suggest Spirulina is a suitable replacement for 50% of dietary fish meal for steelhead whereas a mixture of canola and flaxseed oil is not suitable as a complete replacement for fish oil in diets for this species.

Replacing fish oil with hydrogenated soybean oils in feeds for California Yellowtail

Article

Dec 2017

To assess the relative merits of monounsaturated fatty acid (MUFA)-rich vs. saturated fatty acid (SFA)-rich lipids as alternatives to fish oil in aquafeeds, diets formulated for California Yellowtail Seriola dorsalis containing menhaden fish oil, fully hydrogenated soybean oil (high SFA content), partially hydrogenated soybean oil (high MUFA content) or blends of these soy-derived lipids (20/80, 40/60, 60/40, or 80/20) were tested in a 7-week feeding trial. Juvenile fish (~11 g) were stocked in a semi-closed recirculation aquaculture system (15 fish/tank), diets were randomly assigned to tanks in triplicate (N =3), and fish were fed in slight excess of estimated apparent satiation. Growth performance did not vary based on dietary SFA vs. MUFA content, but performance was inferior among fish fed the soybean oil-based feeds relative to those fed the fish oil-based feed: weight gain = 714-770 vs. 848%; specific growth rate = 4.03-4.16 vs. 4.32% body weight/d; feed conversion ratio = 1.30-1.38 vs. 1.27. Generally, fillet fatty acid composition mirrored dietary composition, except that fillets of fish fed diets containing primarily fully hydrogenated soybean oil contained fewer SFAs and more long-chain polyunsaturated fatty acids (LC-PUFAs) than one would expect based on dietary fatty acid profiles. Fillets of fish fed partially hydrogenated soybean oil contained trans fatty acids (0.02-0.06 g trans fats per 100 g fillet), but only at trace levels. Liver fatty acid profiles were less affected by dietary lipid source, but where differences existed, they followed similar patterns to those observed in fillets. Results suggest that blends of fully and partially hydrogenated soybean oils may yield slightly higher growth performance and fillet lipid content without accumulating enough trans fats to negatively affect consumers. Diets containing only fully hydrogenated soybean oil may slightly reduce lipid digestion in California Yellowtail, but they mitigate LC-PUFA loss associated with fish oil sparing.

Effets de l’alimentation végétale sur les capacités digestives de la truite arc-en-ciel et sur le microbiote associé à sa muqueuse digestive en fonction de son génotype

Thesis

May 2017

Marion Borey

La pression sur les quotas de pêche et l’augmentation de la production aquacole ont contribué à une substitution importante des farines et des huiles de poisson incorporées dans les aliments pour poissons carnivores, par des farines et des huiles végétales. La truite arc-en-ciel, qui est un poisson carnivore, est affectée par ce changement de régime. Ainsi un retard de croissance apparaît dès le plus jeune stade si certaines transformations et supplémentations ne sont pas apportées aux végétaux. L’objectif de ce travail a été d’évaluer, aux stades alevins et juvéniles, l’impact d’une substitution totale des huiles et farines de poisson sur le tractus digestif de la truite arc-en-ciel, et plus particulièrement sur ses capacités digestives et sur la composition de son microbiote intestinal. Le but in fine étant de déterminer si certaines enzymes de la digestion, transporteurs intestinaux, ou sous-communautés bactériennes sont impactés par le changement de régime et peuvent expliquer le retard de croissance observé. Chacun de ces facteurs ont été étudiés via une approche de métagénomique par séquençage de nouvelle génération NGS pour la caractérisation du microbiote, et via de la PCR quantitative et des mesures d’activités enzymatiques pour la comparaison des capacités digestives. Des lignées isogéniques de truites, identifiées comme divergentes dans leur réponse à l’alimentation végétale (capables d’adaptation ou réfractaires) ont permis de disposer d’un matériel biologique pertinent pour répondre à cette question.Chez la truite au stade alevin, une alimentation 100% végétale conduit à une plus forte transcription des gènes codant pour le pepsinogène, le trypsinogène, et le chymotrypsinogène qui sont des enzymes protéolytiques. Deux principales hypothèses peuvent expliquer cette réponse, et pourraient être étudiées : soit cette réponse est physiologique et s’explique par le plus faible poids des truites nourries avec un aliment végétal, soit cette réponse reflète une plus forte transcription d’enzymes digestives pancréatiques en compensation à une digestibilité protéique réduite. Au niveau de l’intestin, une augmentation de la transcription des gènes codant pour l’IAP, le SGLT1, la CCK-t, et PEPT1, et une diminution de la transcription du gène codant pour GLUT2 chez les truites nourries avec une alimentation végétale reflète une capacité réduite à grandir sous une alimentation végétale.Chez la truite au stade juvénile, l’alimentation végétale conduit à une baisse de la digestibilité des lipides et des niveaux plasmatiques des triglycérides et des acides aminés totaux. Ces perturbations pourraient en partie s’expliquer par une diminution de l’activité enzymatique de la phosphatase alcaline, qui témoigne de l’homéostasie intestinale, et de la phospholipase A2. Une baisse de la transcription du transporteur membranaire de triglycérides MTP et de la transcription de la prolidase, peptidase du cytosol des entérocytes, ont également était révélées. Une modification du microbiote intestinal associé à la muqueuse digestive pourrait également contribuer à la baisse de l’homéostasie intestinale. Le changement de régime conduit en effet à une équitabilité plus faible chez les truites ayant reçue un aliment végétal, ce qui reflète un changement dans la représentativité de certains OTUs. Ce changement de régime s’est également traduit par des communautés dissimilaires en moyenne à 70 %, d’après l’estimation de la β-diversité entre les communautés de truites nourries avec l’aliment marin et celles nourries avec l’aliment végétal. La sélection opérée par l’aliment a conduit à un remplacement des OTUs rencontrés au sein des Firmicutes, c’est-à-dire que différentes espèces bactériennes de Firmicutes sont rencontrées suivant le régime considéré. La comparaison de communautés bactériennes entre les différentes lignées isogéniques a montré que la sélection opérée par le génotype de l’hôte a davantage eu lieu sur le remplacement des β-Protéobactéries. Enfin, les comparaisons d’abondances en certaines espèces bactériennes particulières suggèrent que les bactéries Cetobacterium somerae, capables de synthétiser de la vitamine B12, et Shewanella, dont l’implication dans la stimulation des cellules β du pancréas endocrine a déjà été observée chez d’autres espèces, pourraient être impliquées dans la réponse métabolique des truites aux végétaux. Les modifications identifiées dans ce travail constituent des indicateurs biologiques qui pourront être mis à profit pour évaluer la réponse du tractus digestif des truites à de nouvelles formules alimentaires.

Optimal dietary alpha-linolenic acid/linoleic acid ratio improved digestive and absorptive capacities and target of rapamycin gene expression of juvenile grass carp (Ctenopharyngodon idellus)

Article

Aug 2015
AQUACULT NUTR

Growth performance, digestive and absorptive capacities and target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6K1) and eIF4E-binding protein (4E-BP) gene expression in the hepatopancreas and intestine of juvenile grass carp (Ctenopharyngodon idellus) fed graded ratios of dietary alpha-linolenic acid/linoleic acid (ALA/LNA) (0.01, 0.34, 0.68, 1.03, 1.41, 1.76 and 2.15) for 60 days were investigated. The results showed that ALA/LNA ratio of 1.03 significantly improved (i) per cent weight gain (PWG) and feed efficiency, (ii) hepatopancreatic trypsin, chymotrypsin, lipase, amylase and intestinal creatine kinase (CK) activities, (iii) hepatopancreatic trypsinogen-2 and chymotrypsinogen mRNA levels. Meanwhile, fish fed with ALA/LNA ratio of 0.68 significantly enhanced, (iv) Na+/K+-ATPase and γ-glutamyl transpeptidase activities in whole intestine, and alkaline phosphatase activities in the proximal intestine (PI) and distal intestine, (v) amylase, intestinal Na+/K+-ATPase alpha-subunit isoform 1, Na+/K+-ATPase alpha-subunit isoform 8 and CK mRNA abundances, (vi) TOR and S6K1 gene expression in the hepatopancreas and intestine of juvenile grass carp. Based on the quadratic regression analysis of PWG, cholecystokinin and leptin contents in the PI, optimal dietary ALA/LNA ratio of juvenile grass carp (8.78–72.00 g) was estimated to be 1.08, 1.19 and 1.05, respectively.

Resources for fish feed in future mariculture

Article

Full-text available

Mar 2011

Yngvar Olsen

There is a growing concern about the ability to produce enough nutritious food to feed the global human population in this century. Environmental conflicts and a limited freshwater supply constrain further developments in agriculture; global fisheries have levelled off, and aquaculture may have to play a more prominent role in supplying human food. Freshwater is important, but it is also a major challenge to cultivate the oceans in an environmentally, economically and energy-friendly way. To support this, a long-term vision must be to derive new sources of feed, primarily taken from outside the human food chain, and to move carnivore production to a lower trophic level. The main aim of this paper is to speculate on how feed supplies can be produced for an expanding aquaculture industry by and beyond 2050 and to establish a roadmap of the actions needed to achieve this. Resources from agriculture, fish meal and fish oil are the major components of pellet fish feeds. All cultured animals take advantage of a certain fraction of fish meal in the feed, and marine carnivores depend on a supply of marine lipids containing highly unsaturated fatty acids (HUFA, with >= 3 double bonds and >= 20 carbon chain length) in the feed. The availability of HUFA is likely the main constraint for developing carnivore aquaculture in the next decades. The availability of fish meal and oil will decrease, and the competition for plant products will increase. New harvested resources are herbivore zooplankton, such as Antarctic krill and red feed, and new produced resources are macro-algae, transgenic higher HUFA-producing plants and bacterial biomass. These products are to a limited extent components of the human food chain, and all these resources will help to move cultured carnivores to lower trophic levels and can thereby increase the production capacity and the sustainability of the production. Mariculture can only become as successful as agriculture in the coming century if carnivores can be produced at around Trophic Level 2, based mainly on plant resources. There is little potential for increasing the traditional fish meal food chain in aquaculture.

Characterization of volatile compounds of French and Spanish virgin olive oils by HS–SPME of quality freshness markers

Article

Full-text available

Nov 2004
FOOD CHEM

Headspace-Solid Phase Microextraction (HS-SPME) was applied to the analysis of volatile compounds of virgin olive oils from southern France (Alpes–Maritimes) and Spain (Reus). Forty one compounds were isolated and characterized by GC–RI and GC–MS, representing 85.3–92.8% of the total amount. (E)-Hex-2-enal, the main compound extracted by SPME, characterized the olive oil headspace for all samples. The other compounds identified were mainly hexanal, (Z)-hex-3-enol, (E)-hex-2-enol and hexanol. Changes in the chemical composition of the olive oil headspace were also monitored during storage. The content of (E)-hex-2-enal decreased over several months, and that of the C6 alcohols and C5 ketones increased. These compounds can be used as markers for the evaluation of olive oil quality.

Effects of dietary lipid level and vegetable oil on fatty acid metabolism in Atlantic salmon (Salmo salar L.) over the whole production cycle

Article

Full-text available

Jul 2003

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 C(18) 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 beta-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.

Volatile aldehydes in smoked fish: Analysis methods, occurence and mechanisms of formation

Article

Full-text available

Dec 2007
FOOD CHEM

The carbonyl function of volatile aldehydes is discussed from methodological point of view (reactivity and analysis method). From this presentation, an inventory of volatile aldehydes recovered in smoked fishes are carried out. Then, the different pathways possible for the formation of these molecules are explained in order to better understand their occurence in smoked fish aroma. Maillard reactions for the “smoked” aroma and lipid oxidation for “fishy” aroma are the two main pathways of creation of odorant volatile aldehydes. Each odorant aldehyde recovered in smoked fish is characterized by its descriptors, its odour thresholds and its origins are investigated. Volatile aldehydes in smoked fishes are also studied according to the others organoleptic roles that they play in this kind of food matrices especially about their contribution in organoleptic properties of smoked products. Finally, the toxicity of several aldehydes identified in smoked fishes is discussed in order to assess their roles in smoked fish safety.

Genotype-specific responses in Atlantic salmon (Salmo salar) subject to dietary fish oil replacement by vegetable oil: A liver transcriptomic analysis

Article

Full-text available

May 2011
BMC GENOMICS

Expansion of aquaculture is seriously limited by reductions in fish oil (FO) supply for aquafeeds. Terrestrial alternatives such as vegetable oils (VO) have been investigated and recently a strategy combining genetic selection with changes in diet formulations has been proposed to meet growing demands for aquaculture products. This study investigates the influence of genotype on transcriptomic responses to sustainable feeds in Atlantic salmon. A microarray analysis was performed to investigate the liver transcriptome of two family groups selected according to their estimated breeding values (EBVs) for flesh lipid content, 'Lean' or 'Fat', fed diets containing either FO or a VO blend. Diet principally affected metabolism genes, mainly of lipid and carbohydrate, followed by immune response genes. Genotype had a much lower impact on metabolism-related genes and affected mostly signalling pathways. Replacement of dietary FO by VO caused an up-regulation of long-chain polyunsaturated fatty acid biosynthesis, but there was a clear genotype effect as fatty acyl elongase (elovl2) was only up-regulated and desaturases (Δ5 fad and Δ6 fad) showed a higher magnitude of response in Lean fish, which was reflected in liver fatty acid composition. Fatty acid synthase (FAS) was also up-regulated by VO and the effect was independent of genotype. Genetic background of the fish clearly affected regulation of lipid metabolism, as PPARα and PPARβ were down-regulated by the VO diet only in Lean fish, while in Fat salmon SREBP-1 expression was up-regulated by VO. In addition, all three genes had a lower expression in the Lean family group than in the Fat, when fed VO. Differences in muscle adiposity between family groups may have been caused by higher levels of hepatic fatty acid and glycerophospholipid synthesis in the Fat fish, as indicated by the expression of FAS, 1-acyl-sn-glycerol-3-phosphate acyltransferase and lipid phosphate phosphohydrolase 2. This study has identified metabolic pathways and key regulators that may respond differently to alternative plant-based feeds depending on genotype. Further studies are required but data suggest that it will be possible to identify families better adapted to alternative diet formulations that might be appropriate for future genetic selection programmes.

Saturated Lipid Sources in Feeds for Sunshine Bass: Alterations in Production Performance and Tissue Fatty Acid Composition

Article

Full-text available

Oct 2009

Jesse Trushenski

Feeds rich in saturated (SFAs) and monounsaturated fatty acids (MUFA) appear to maximize the retention of long-chain polyunsaturated fatty acids (LC-PUFA) in the fillets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). To determine whether different sources of SFA and MUFA have equivalent effects on tissue fatty acid (FA) profile change, coconut (CO) and palm oils(PO) were evaluated as partial and complete substitutes for fish oil (FO) in feeds for juvenile sunshine bass. After 8 weeks of culture, the production performance of all groups was within the acceptable range for sunshine bass; however, weight gain was significantly reduced within the 100%-CO group. Partial replacement of FO with CO or PO resulted in significant alteration of fillet FA profiles, and these changes were exacerbated in the complete-FO-replacement groups. The LC-PUFA were disproportionately enriched in the fillets of fish fed the reduced or FO-free feeds, whereas dietary surpluses of 12:0 and 14:0 (CO-based feeds) and 16:0 (PO-based feeds) were not reflected in any of the tissues analyzed. Rather, the levels of the SFA elongation–desaturation products (i.e., 18:0 and 18:1[n-9]) were elevated, particularly within liver lipid, suggesting enhanced FA biotransformation activity among fish fed higher levels of either alternative lipid source. Based on tissue FA composition, PO and CO appear to be approximately equivalent in terms of fillet LC-PUFA retention. However, the digestibility and utilization of these feedstuffs must be further investigated to maximize the ability of PO and CO to (partially or completely) replace FO in sunshine bass feeds.

Nutritional bioenergetics and estimation of waste production in non-salmonids

Article

Full-text available

Jul 1998

Sadasivam Kaushik

The general principles behind the bioenergetic approach for predicting growth, as well as for decreasing feed and nutrient losses, have been set forth for salmonids. Given the diversification of fish farming activities around the world and the ever increasing concern for water quality management, it becomes essential to verify whether an approach developed for salmonids is applicable to other species. Given this general background, an attempt is made here to check the theoretical assumptions and technical considerations behind the bioenergetic principles developed for rainbow trout with other freshwater or marine species. From a conceptual point of view, recent literature data do indicate that as far as nitrogen or energy balance is concerned, the general scheme is as valid for marine species as it is for salmonids, even in quantitative terms. Given the methodological tools available today, it should not be difficult to reduce feed and nutrient losses and to estimate the potential environmental loadings using the same principles for non-salmonids. Chez les salmonidés, l'efficacité de l'approche bioénergétique pour prédire la croissance, le taux de rationnement en fonction de la qualité des aliments permettant ainsi de réduire les rejets d'origine nutritionnelle est bien démontrée. Dans le contexte de la diversification de l'aquaculture et pour une plus grande prise en compte des aspects environnementaux, il paraît essentiel de vérifier la validité de telles approches initialement proposées pour les salmonidés, pour d'autres espèces marines ou d'eau douce. Les données actuelles montrent qu'en ce qui concerne les bilans azoté et énergétique, une transposition de ces principes est assez aisée. Les outils méthodologiques et conceptuels existants nous permettent d'envisager une meilleure maîtrise de l'alimentation et une réduction des rejets pour ces espèces comme pour les salmonidés.

A Simple Method for the Isolation and Purification of Total Lipides from Animal Tissues

Article

Full-text available

Jun 1957

Interactive Effects of Dietary Palm Oil Concentration and Water Temperature on Lipid Digestibility in Rainbow Trout, Oncorhynchus mykiss

Article

Full-text available

Nov 2003

An experiment was conducted to evaluate the interactive effects of dietary crude palm oil (CPO) concentration and water temperature on lipid and FA digestibility in rainbow trout. Four isolipidic diets with 0, 5, 10, or 20% (w/w) CPO, at the expense of fish oil, were formulated and fed to groups of trout maintained at water temperatures of 7, 10, or 15 degrees C. The apparent digestibility (AD) of the FA, measured using yttrium oxide as an inert marker, decreased with increasing chain length and increased with increasing unsaturation within each temperature regimen irrespective of CPO level fed to the fish. PUFA of the n-3 series were preferentially absorbed compared to n-6 PUFA in all diet and temperature treatments. Except for a few minor FA, a significant (P < 0.05) interaction between diet and temperature effects on FA digestibility was found. Increasing dietary levels of CPO lead to significant reductions in the AD of saturates and, to a lesser extent, also of the other FA. Lowering water temperature reduced total saturated FA digestibility in trout regardless of CPO level. Based on the lipid class composition of trout feces, this reduction in AD of saturates was due in part to the increasing resistance of dietary TAG to digestion. Increasing CPO level and decreasing water temperature significantly increased TAG content in trout fecal lipids, with saturates constituting more than 60% of the FA composition. Total monoene and PUFA digestibilities were not significantly affected by water temperature in fish fed up to 10% CPO in their diet. The potential impact of reduced lipid and FA digestibility in cold-water fish fed diets supplemented with high levels of CPO on fish growth performance requires further research.

Fish oil replacement and alternative lipid sources in aquaculture feeds

Article

Jan 2010

Palm Oil and Saturated Fatty Acid-Rich Vegetable Oils

Chapter

Jul 2010

Fish oil replacement and alternative lipid sources in aquaculture feeds

Article

Jan 2011

A simple method for the isolation and purification of total lipids from animal Tissues

Article

May 1957

Fish Oil Replacement in Starter, Grow-Out, and Finishing Feeds for Farmed Aquatic Animals

Chapter

Jul 2010

As aquaculture production continues to grow, there will be an increased use of lipid resources (oils and fats) alternative to fish oil for feed production. The potential for the use of these alternatives varies depending on the feeds in which they are included according to the production phase of the animals to which they are being fed. In starter feeds, where rapid growth, high survival, and normal development are critical priorities, there will remain a need for the use of lipid resources high in omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA). Fish in this starter phase have a critical requirement for the n-3 LC-PUFA docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and fish oils remain the only cost-effective source of these nutrients in the volumes required. However, the greatest demand for lipids is in those diets for the grow-out phase. Most studies on alternative lipid use with animals in this part of the production phase show positive outcomes, in that there are few studies where all the added fish oil cannot be replaced. There are some species, however, where potential replacement levels are suggested to be more conservative, and a general substitution level in this production phase of 75% has been suggested. One of the key effects noted across the grow-out phase is that all alternatives affect the flesh fatty acid characteristics by reducing the level of n-3 LC-PUFA. This issue has provoked the concept of finisher diets, whereby a high n-3 LC-PUFA content diet is fed in order to restore the desired meat fatty acid profiles. Studies examining this concept have found that the tissue triacylglycerol fatty acids were greatly modified and responded in a simple dilution process to the added oil fatty acid composition, whereas the fatty acids of tissue phospholipids were less influenced by dietary fatty acid makeup.

The Effects of Fish Oil Replacement on Nutritional and Organoleptic Qualities of Farmed Fish

Chapter

Jul 2010

The “n−3 LC-PUFA sparing effect” of modified dietary n−3 LC-PUFA content and DHA to EPA ratio in Atlantic salmon smolt

Article

Aug 2012
AQUACULTURE

n−3 Long-chain (≥ C20) polyunsaturated fatty acids (LC-PUFA) are used extensively by fish via β-oxidation when in dietary surplus. Therefore it is of interest to optimize n−3 LC-PUFA deposition in fish via a reduction in β-oxidation which may be induced by manipulation of dietary fatty acids. This study tested whether Atlantic salmon smolt fed a diet with a higher docosahexaenoic acid (DHA):eicosapentaenoic acid (EPA) ratio and a lower content of n−3 LC-PUFA to that of fish oil (FO) based diets would enhance deposition of n−3 LC-PUFA in fish tissues. Comparisons were made between fish fed: a FO diet, a blend of 50% rapeseed and 50% tuna oil diet (model oil, MO 1), a blend of 50% rapeseed, 25% tuna and 25% FO diet (MO 2), and a blend of 50% FO and 50% chicken fat diet (FO/CF). The dietary DHA:EPA ratio was in the order MO 1 > MO 2 > FO/CF ~ FO. Dietary n−3 LC-PUFA content was approximately 2-fold lower in fish fed the MO 1, MO 2 and FO/CF diets compared to the FO diet. There were comparable amounts of n−3 LC-PUFA in the muscle of FO, MO 1 and FO/CF fed fish. Our findings indicate that the right balance in both absolute and relative amounts of EPA and DHA can promote n−3 LC-PUFA retention.

Seven fish oil substitutes over a rainbow trout grow-out cycle: II) Effects on final eating quality and a tentative estimation of feed-related production costs

Article

Sep 2013

Fish oil replacement in rainbow trout diets and total dietary PUFA content: II) Effects on fatty acid metabolism and in vivo fatty acid bioconversion

Article

Oct 2011
AQUACULTURE

This study aimed to gain a better understanding of the metabolic fate of dietary fatty acids in rainbow trout, with a specific focus on the effect of varying total C18 PUFA level. Fish were fed a control fish oil based diet or one of five experimental fish oil deprived diets formulated with a constant 1/1 ratio of 18:3n-3/18:2n-6 and varying total C18 PUFA levels for a period of 7weeks. The transcriptional changes of the Δ-6 desaturase and elongase enzymes in direct comparison to in vivo fatty acid bioconversion, estimated using the whole-body fatty acid balance method, were analysed. The main findings were that i) the efficiency of Δ-6 desaturase was negatively affected by C18 PUFA availability, but the total apparent in vivo enzyme activity was directly proportional to C18 PUFA substrate availability; ii) Δ-6 desaturase had a greater affinity towards n-3PUFA than n-6PUFA; iii) excessive C18 PUFA substrate availability could limit the availability of Δ-6 desaturase to act on C24 fatty acid; iv) the elimination of dietary n-3LC-PUFA (enzyme products) up-regulated the transcription rate of Δ-6 desaturase; but v) the total apparent in vivo enzyme activity was directly and positively affected by substrate availability, and not product presence/absence nor the extent of the enzyme transcription rate.

Flesh quality of raw and smoked fillets of Atlantic salmon as influenced by dietary oil sources and frozen storage

Article

Apr 2004
FOOD RES INT

The aim of this study was to evaluate the effects of dietary oil source and frozen storage on flesh quality characteristics of Atlantic salmon. Four diets containing either 100% of Peruvian fish oil (PO), capelin oil (CO), soybean oil (SO) or low-erucic acid rapeseed oil (RO) as supplemental oil were fed to triplicate groups of salmon for 135 days. After slaughter, half of the fish were smoked while the rest were analysed when raw. For smoked and raw fish, the left fillet was analysed as fresh fillet while the right fillet was frozen and stored at −20 °C for two or four months before analyses. Fish fed SO and PO diets had firmer texture than fish fed RO diet. Liquid holding capacity (LHC) and colour evaluation were influenced by dietary oil source. Colour of fish fed fish oil-diets had significantly higher colour than fish fed vegetable oil-diets. Frozen storage decreased the firmness of raw fillets and the LHC of raw and smoked fillets. Colour evaluation was affected by frozen storage by increasing L*, a* and b* values whereas muscle carotenoid concentrations slightly decreased. Lipid oxidation was more pronounced in fish fed high levels of n-3 fatty acids and increased with frozen storage.

Effects of alternative dietary lipid sources on performance, tissue chemical composition, mitochondrial fatty acid oxidation capabilities and sensory characteristics in brown trout (Salmo trutta L.)

Article

Jul 2003
AQUACULTURE

The efficiency of five dietary lipid sources (fish oil as control—C; canola oil—CO; poultry fat—PF; pork lard—PL; and oleine oil—OO) were evaluated in juvenile brown trout (58.4±0.7 g) in an experiment conducted over 70 days at 14.6±0.4 °C. The best growth was observed in fish fed the C diet whereas the PL diet fed fish had the best feed utilization. Significant differences in carcass and muscle proximate composition, but not in liver, were noted among fish fed the different dietary treatments. The fatty acid composition of muscle largely reflected that of the diets, while total cholesterol was not affected. The atherogenicity and the thrombogenicity qualities of the trout flesh were modified by the lipid sources. Sensory analysis did not show any significant differences among the cooked fillets with respect to dietary treatments, while in uncooked products, some significant differences were observed. The carnitine palmitoyltransferase I and II (CPT-I and CPT-II) activities of liver and white muscle were assayed for a better understanding of the potential β-oxidation capability of the different dietary lipid sources. The hepatic, but not white muscle CPT-I and CPT-II activities were affected by dietary treatments. This study showed that alternative lipid sources could be used effectively for oil coating extruded diets for brown trout.

Evaluation of acid-insoluble ash as natural marker in ruminant digestibility

Article

Jan 1977

SUMMARY Comparisons were made of the total fecal collection method and Acid-Insoluble Ash (AIA) natural marker method for determina- tion of dry matter digestibility coefficients of rations by sheep. Three laboratory analytical procedures (Concentrated (Cone.) He1, 4N HCI and 2N HCI) which differed in ashing sequence, ashing temperature and acid strength, were used to determine the AIA content of feed and fecal samples. The dry matter digestibility coefficients esti- mated by the AIA marker method, by all three analytical procedures, were not significantly different from the coefficients determined by the traditional total fecal collection method. However, the digestibility coefficients esti- mated using the 4N HCI marker were higher (P

Evaluation of Acid-Insoluble Ash as an Indicator of Feed Digestibility in Rainbow Trout (Salmo gairdneri)

Article

Apr 2011

Relative performances of dietary acid-insoluble ash, celite (a source of acid-insoluble ash), and chromic oxide as digestibility references were compared. Apparent digestibilities of dry matter, crude protein, and gross energy in a practical diet fed to rainbow trout (Salmo gairdneri) were similar regardless of indicator used. Acid-insoluble ash can bean effective indicator for digestibility trials with fish. Its natural occurrence in fish foods and feedstuffs and ease of analysis make it preferable to added indicators, such as chromic oxide, in many circumstances. When the acid-insoluble ash content of a diet is low, the addition of celite can improve the precision of the analysis without affecting absolute values of digestibility coefficients.

The influence of environmental temperature on the apparent nutrient and fatty acid digestibility in Atlantic salmon (Salmo salar L.) fed finishing diets containing different blends of fish oil, rapeseed oil and palm oil

Article

Aug 2004
AQUAC RES

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.

Relationships between carotenoid concentration and colour of fillets of Arctic charr, Salvelinus alpinus (L.), fed astaxanthin

Article

Jun 2008
AQUAC RES

The relationships between fillet colour (CIE L* a* b* and CIE L* C* H°ab) and carotenoid concentration were investigated using samples taken from Arctic charr, Salvelinus alpinus (L.), of different ages and sizes, which were held under a variety of rearing conditions. Relationships between colour parameters and carotenoid concentrations were nonlinear. Increasing carotenoid concentrations led to increased redness (a*), yellowness (b*) and chroma (C*), and decreased lightness (L*) and hue angle (H°ab). Redness was the colour parameter most highly correlated with carotenoid concentration of the Arctic charr fillets. For a given redness value, yellowness was higher in sexually mature than in immature Arctic charr. This was possibly a result of mature fish having higher proportions of idoxanthin in the fillet than immatures. Alternatively, the differences in yellowness may have been a consequence of differences in proximate composition of fillets of mature and immature charr. There were also differences in yellowness in fillets from Svalbard and Hammerfest charr, Svalbard fish having the most yellow fillets. Fish from the two strains did not differ in relative proportions of fillet carotenoids, indicating that differences in colour were mediated through differences in other chemical properties.

Fatty acid productive value and ?-oxidation capacity in Atlantic salmon (Salmo salar L.) fed on different lipid sources along the whole growth period

Article

Mar 2007
AQUACULT NUTR

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.

The use of palm oil in aquaculture feeds for salmonid species

Article

Apr 2007
EUR J LIPID SCI TECH

In this overview, our current knowledge and research being conducted on the use of palm oil in the commercial feeds for cold-water salmonid species such as Atlantic salmon and rainbow trout will be highlighted. Salmonid diets have a high lipid content to provide a source of easily available energy and also n-3 polyunsaturated fatty acids (PUFA) which is used to maintain membrane fluidity in a cold-water environment. The culture of salmonid fishes has traditionally depended on marine fish oils for this purpose, but with limited supplies and the rapid increase in salmon production, alternatives to fish oils must be investigated. Research has shown that crude palm oil can be used to replace 100% of added fish oils in salmonid diets without compromising growth performance and feed utilization efficiency, despite reductions in lipid and fatty acid digestibilities that occur during low water temperatures over the winter rearing period. Fatty acid desaturation and elongation activities increased with increasing dietary palm oil and, to a certain extent, decreasing water temperatures. The effects of palm oil on fish health requires further research, but the use of this more saturated vegetable oil may reduce oxidative stress in fish, thereby reducing pathological conditions associated with this physiological state. It is generally known that the fish fillet fatty acid composition directly reflects that of the dietary oil used. Extrapolating from work done with other vegetable oils, the supply of beneficial n-3 PUFA in salmon fillets to the human consumer can be maintained by using a finishing diet strategy just prior to harvesting, despite significant reductions in these fatty acids when high levels of dietary palm oil are used in grower feeds. Compared to vegetable oils such as soybean or rapeseed oil, palm oil has several advantages in terms of high oil productivity, lower cost, less deposition of undesirable fatty acids such as 18:2(n-6), superior energy source in the form of saturated and monounsaturated fatty acids, and a high content of natural antioxidants (carotenes and vitamin E). Fillet texture and color were not affected by feeding salmon palm oil-based diets.

Seven fish oil substitutes over a rainbow trout grow-out cycle: I) Effects on performance and fatty acid metabolism

Abstract

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