Total Replacement Of Fish Oil Research Articles

Nutritional innovations in superior European sea bass (Dicentrarchus labrax) genotypes: Implications on fish performance and feed utilization

The sustainable development of the aquaculture industry relies on the use of alternative conventional and emergent raw materials that contributes to a circular economy and to reduce the dependency on fish meals and fish oils coming from oceanic fish populations. Additionally, the genetic selection of farmed fish that can display higher growth and feed utilization when fed alternative feeds, is pointed out to be a complementary valuable tool to facilitate the implementation of circular economy approaches. The main purpose of the present study was to determine the effectiveness of genetic selection for growth in European sea bass, in response to a challenge with an alternative diet that aimed to partially replaced fishmeal (FM) by poultry meal (PM) and totally replace fish oil (FO) by a blend of poultry oil (PO) with a novel microalgae oil. The two families of fish juveniles were obtained by in vitro fertilization of selected for a multi-trait including high growth (genetically selected, GS) or non-selected (wild type, WT) broodstocks and then were nutritionally challenged with a control diet that mirrored a standard commercial diet with fishmeal (20%) and fish oil (7%), or a Future diet that partially replaced the FM by PM and totally replaced the FO by a blend of rapeseed oil, PO, and a novel DHA rich-algal oil. From the second month of feeding until the end of the trial, European sea bass that was selected since for 7 generations performed better in terms of growth than the wild-type genotype, possibly related with an apparent favored feed and nutrient utilization. Furthermore, selection decreased the perivisceral fat and increased the nutritional value of flesh by increasing DHA (in g/ 100 g flesh) and ARA contents. In contrast, the dietary treatment showed little effect on fish growth performance, denoting the successful partial replacement of FM by PM and the total replacement of FO by a blend of poultry oil and an emergent microalgal oil. However, Future diet tended to reduce the ADCs of some amino acids, as well as showed an additive effect to genotype in increasing the n-3 PUFA of flesh. Altogether, our data demonstrate that multi-trait genetic selection of European sea bass improve fish plasticity to cope with the variations of ingredients in alternative feeds with low FM/FO.

Fish Oil Replacement by Camelina (Camelina sativa L.) Oil in Diets for Juvenile Tench (Tinca tinca L.): Effects on Survival, Growth, and Whole-Body Fatty Acid Profile.

Tench (Tinca tinca L.) plays a key role in the diversification of inland aquaculture, but its culture is mainly based on extensive culture systems with usually low and unpredictable yields. Rearing procedures under controlled conditions are essential to promote and consolidate tench production, and it is necessary to set up adequate feeding in early growth phases. Fish oil (FO) is currently the main source of lipids in aquafeeds, but considering the stagnation of smaller pelagic fisheries, alternative oils should be addressed. In a ninety-day experiment, the effects of partial and total replacement of FO with camelina oil (CO) on juvenile tench growth performance and whole-body composition were evaluated. Six isonitrogenous and isolipidic diets with different levels of CO were tested: 0% (control), 20%, 40%, 60%, 80%, and 100%. The survival rate was 100%, and no significant differences in growth performance (total length, weight, specific growth rate, feed conversion ratio, and biomass gain) were found. The lipid content in whole-body juveniles was significantly lower when juveniles were fed diets containing 40% and higher levels of CO than those fed the control diet whereas linolenic acid content was significantly higher. No differences in ΣSFA, ΣMUFA, ΣPUFA, Σn - 3, or Σn - 6 whole-body content were found. The nutritional indices ΣPUFA/ΣSFA and Σn - 6/Σn - 3 showed a linear increase trend with dietary CO inclusion whereas the EPA + DHA showed an opposite tendency. Compared to the control diet, EPA + DHA content (g kg-1) was significantly lower in juvenile tench fed a 100% CO diet, and Σn - 6/Σn - 3 was significantly higher in juvenile tench fed 80% and 100% CO diets. Overall, the results indicate that the total replacement of FO with CO in diets is feasible without negative effects on growth performance whereas the nutritional quality of juvenile tench was unaffected with a maximum replacement of 80%.

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

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 effects of replacing fishmeal by Chlorella vulgaris and fish oil by Schizochytrium sp. and Microchloropsis gaditana blend on growth performance, feed efficiency, muscle fatty acid composition and liver histology of gilthead seabream (Sparus aurata)

The present study evaluated the effects of replacing fishmeal protein by Chlorella vulgaris meal and fish oil by a blend of Schizochytrium sp. and Microchloropsis gaditana on growth, feed utilization, muscle fatty acid composition and liver histology of Sparus aurata. Fish were fed twice a day for 12 weeks, six isonitrogenous (52% CP) and isoenergetic (21 MJ/Kg) diets at which fishmeal protein of the Control diet was replaced by C. vulgaris meal at 10% (CM10), 20% (CM20) and 30% (CM30) and fish oil of the control diet was replaced by a blend of Schizochytrium sp. and Microchloropsis sp. at 50% (SM50) and 100% (SM100). It was found that the partial replacement of fishmeal protein by C. vulgaris meal up to 30% and the total fish oil replacement by Schizochytrium sp. and M. gaditana blend did not exert any adverse effects on the feed intake, SGR, FCR and PER of fish. Graded levels of C. vulgaris led to an increased lipid retention and deposition mainly in the liver, but no other diet-dependent changes were observed in the whole body and muscle proximate compositions of fish. Microalgae-based diets displayed no major hepatic histomorphological effects, but the very few incidences of hydropic degeneration and haemorrhage that were observed call for further investigation to reveal any potential histopathological impacts of such dietary strategy. Fishmeal replacement by C. vulgaris increased the levels of 18:2n-6 and 18:3n-3 in fish muscle, while EPA and DHA levels were not significantly reduced since dietary fish oil maintained their deposition. Fish oil replacement by the blend of Schizochytrium sp. and Microchloropsis sp. increased the n-6 PUFA and particularly 20:4n-6 and 22:5n-6 in the muscle, while maintained similar EPA and DHA levels compared to the Control group. The present study suggests that the blend of dried biomasses of Schizochytrium sp. and M. gaditana could totally replace dietary fish oil in fishmeal-based diets formulated with soybean oil, without negatively affecting the growth performance, feed efficiency, proximate composition and muscle EPA and DHA levels of S. aurata, even if this resulted in a few histomorphological alterations. Moreover, replacing fishmeal protein by C. vulgaris meal up to 30% that was the maximum level tested did not adversely affect growth performance and feed utilization, even if it resulted in increased lipid retention and deposition in the liver.

Effect of dietary inclusion of camelina or chia oil on fatty acid digestibility, histology, blood biochemistry and molecular biomarkers in juvenile gilthead sea bream (Sparus aurata, L.)

The present study evaluated fatty acid digestibility, histology, blood biochemistry and gene expression in the gut of juvenile gilthead sea bream, Sparus aurata (initial mean weight, 60.4 ± 4.9 g) fed with iso-proteic (48%) and iso-lipidic (20.7%) diets in which fish oil was partially (60%) or totally (100%) replaced with either camelina or chia oil. Each of the experimental diets was fed to triplicate groups of fish stocked at 10 fish/tank in 150 L tanks for 90 days. Although inclusion of camelina or chia oil altered dietary fatty acid (FA) profile, major differences in digestibility in the individual FAs were not observed. Total replacement of fish oil with camelina or chia oil did not have any effect on blood glucose levels, whereas cholesterol and triglyceride levels were reduced. Results of messenger ribonucleic acid (mRNA) transcription showed elevated levels in the expression of the elongases and desaturases in gilthead seabream fed with diets devoid of fish oil. Fish fed with camelina or chia oil based diets had increased expression in lipolytic and lipogenic genes, resulting in accumulation of lipid droplets in the gut of fish. Histological examination revealed no pathological disorders in the guts of the fish.

Fish Oil Replacement by a Blend of Vegetable Oils in Diets for Juvenile Tench (Tinca tinca Linnaeus, 1758): Effects on Growth Performance and Whole-Body Composition.

Simple SummaryFish oil (FO) can be totally replaced by a blend of vegetable oils (30% linseed oil, 20% corn oil, and 50% olive oil) in diets for juvenile tench (Tinca tinca Linnaeus, 1758) without negative effects on survival rate and growth performance. Diets affected the composition of juveniles so that lipid content was significantly lower in animals fed diets without FO. Moreover, the content of linolenic acid (18:3n-3) increased as FO substitution did, being significantly higher with respect to control diet (without vegetable oils) from 40% or higher FO replacement diets. No differences in saturated, monounsaturated, and polyunsaturated fatty acids were found in the fish whole-body. Nutritional indices can be considered within optimal values for healthy foods.Among freshwater species, tench (Tinca tinca Linnaeus, 1758) is considered as a promising species for the diversification of aquaculture, but the intensification of techniques is necessary to promote and consolidate its culture. Adequate feeding in early growth phases is essential to face further grow-out. Fish oil (FO) is the main source of lipids in fish diets, but its production is unsustainable, and thus, alternative oils should be considered. A 90-day experiment was performed to evaluate the effects of partial and total replacement of cod liver oil (FO) by a blend of vegetable oils (VO) in juvenile tench. Six isonitrogenous and isolipidic diets with different levels of a VO blend containing 30% linseed oil, 20% corn oil, and 50% olive oil were tested: 0% (control), 20%VO, 40%VO, 60%VO, 80%VO, and 100%VO. With all diets, survival was 100%, and there were not differences in growth performance (total length (TL); weight (W); specific growth rate (SGR); feed conversion ratio (FCR); and biomass gain (BG)). Compared to the control group, whole-body lipid content decreased significantly in the 100%VO group. No differences in total saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were found in the whole-body. The content of linolenic acid (ALA) in the whole-body increased as FO substitution did, being significantly higher with respect to control diet from 40% FO replacement diets. Nutritional indices, such as ΣPUFA/ΣSFA and Σn-6/Σn-3 ratios, tended to increase with increasing VO content, whereas the EPA + DHA showed an opposite trend. A total replacement of FO by the blend of VO did not affect the growth performance and fatty acid profile of juvenile tench. Further research on the effects of VO diet on nutritional quality in tench reared to commercial size should be performed.

Replacing fish oil with crude palm oil in the diet of larval hybrid lemon fin barb (Barbonymus gonionotus ♀ × Hypsibarbus wetmorei ♂)

Hybrid lemon fin barb is a novel carp species produced in Malaysia crossing lemon fin barb (Hypsibarbus wetmorei, ♂) and silver barb (Barbonymus gonionotus, ♀). As the delicious wild H. wetmorei is being overexploited, this new hybrid species is produced, filling the production gap in Malaysian aquaculture. The hybrid larvae in our previous study showed high tolerance to bacterial diseases and revealed the suitability of culturing hybrid lemon fin barb in the tropics. The effects of increasing dietary replacements level of fish oil (FO) with crude palm oil (CPO) were investigated for the larval stage of this fast-growing and delicious carp species. Three-day old hybrid larvae were randomly allocated to fifteen 5-L tanks stocked at the rate of 50 larvae L−1. Five micro diets containing 0%, 25%, 50%, 75% and 100% dietary substitution levels of FO with CPO levels were formulated. An extra replicate tank was maintained for each treatment for enzyme sampling at 4-day intervals. After 20 days of the feeding trial, dietary replacement of FO with CPO did not significantly affect (p > 0.05) survival and growth of hybrid lemon fin barb larvae. Dietary CPO reduced (p < 0.05) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in hybrid larval tissues. Partial replacement of FO with CPO in hybrid lemon fin barb diets showed no lipid vacuoles in the liver and gut during the challenge test against A. hydrophila. In conclusion, total replacement of FO with CPO is acceptable for the culture of hybrid lemon fin barb larvae; though considering the health status of larvae, 75% replacement of dietary FO with CPO would be more applicable. However, lipid metabolism seems low at the early larval period in larvae fed dietary CPO.

Effect of total replacement of fish oil with tallow and emulsifier in diet on growth, feed utilization, and immunity of olive flounder (Paralichthys olivaceus)

AbstractThe supplementary effects of an emulsifier mixture (polyoxyethylene (20) sorbitan monolaurate and distilled monoglycerides) were investigated on feed utilization, growth performance, and immunity of olive flounder, Paralichthys olivaceus, replacing fish oil with beef tallow. A fish oil containing diet was considered as positive control (PC) and a diet containing beef tallow instead of fish oil was considered as negative control (TW). Two other diets (EM01 and EM02) were prepared by adding 0.01 and 0.02% of the emulsifier into the TW diet. After 8 weeks of a feeding trial, growth performance and feed utilization were significantly higher in fish fed EM01, EM02, or PC diets compared to those fed the TW diet. Dry matter digestibility was higher in EM01 and EM02 diets than the TW diet and comparable to PC diet. Lipid digestibility was significantly higher in PC diet compared to TW diet. Liver EPA and DHA levels were lower, and oleic acid level was higher in fish fed diets containing tallow compared to PC group. Significantly increased aspartate aminotransferase and triglyceride levels were observed in TW group. Dietary supplemented emulsifier restored the reduced performance of olive flounder fed diets containing tallow instead of fish oil. However, the optimum inclusion level of the emulsifier should be elucidated in future studies.

Implication of total replacement of fish oil with vegetable oils on nutritional and lipid profiles of fish

In this study, the effects of using vegetable oils solely in finfish feed on nutritional status as well as lipid damage were evaluated. Polyene index (PI), atherogenic index (AI) as well as hypocholesterolemic and hypercholesterolemic fatty acids were assessed. Also, n-3/n-6 and n-6/n-3 ratios were assessed. In all, 32 articles were used for this study after carefully assessing them. Eighteen (18) articles had studied Freshwater species (FWF) whiles fourteen (14) had studied Marine species (MF). TI, n-3/n-6, and n-6/n-3 were significantly higher in fish-fed saturated fatty acids (SFA), n-3, and n-6 dominant vegetables. We document that using vegetable oils without supplementing fish diets with fish oil does not compromise the nutritional status as well as lipid damage. This work provides important information about the effect of using 100% vegetable oils in fish with respect to the nutritional composition of the final product.

Zootechnical performance, biochemical response, and chromaticity in Pacific white shrimp (Litopenaeus vannamei) (Boone, 1931) after the inclusion of lyophilized açaí (Euterpe oleracea) in the diet

Functional foods have molecules that promote health benefits beyond their nutritional qualities. In this context, the zootechnical performance, color, and biochemical responses of Pacific white shrimp (Litopenaeus vannamei) fed with different levels of acai (Euterpe oleracea), a fruit with unique antioxidant characteristics, were observed. Four diets with different levels of inclusion of lyophilized acai (0.0%, 2.5%, 5.0%, and 10.0% W/W) were administered to shrimps reared in biofloc technology (BFT) systems. After 43 days, the zootechnical parameters (weight gain, feed conversion ratio, and specific growth rate) and coloration in fresh and cooked shrimps were measured, and the L*, a*, and b* parameters were estimated with a digital colorimeter. Survival and growth performances were not affected by acai inclusion in diets. Acai inclusion modulates the flavonoid content in the gills of L. vannamei and in the bioflocs of the rearing BFT system. As in the diet of 10.0% acai, performed with a total replacement of fish oil without affecting growth, we propose the use of acai as a vegetal oil source for shrimp feeding in BFT systems. Acai also induced the reddish color in fresh and cooked L. vannamei, an influential factor in their commercial value.

Partial and total replacement of fish oil with fatty acid ethyl esters in the starter diets of rainbow trout (Oncorhynchus mykiss)

Fatty acid ethyl esters (FAEE) are a potential alternative to fish oil as a source of polyunsaturated fatty acids in fish feeds. This investigation examined the growth performance, lipid composition, and intestinal and liver histology of rainbow trout (Oncorhynchus mykiss) fed experimental starter diets with graded levels of FAEE and fish oil. Five experimental diets were formulated with 20% total lipid content and 0%, 25%, 50%, 75%, and 100% replacement of Alaskan Pollock oil with FAEE oil, and they were formulated with analogous fatty acid levels. The five diets used defatted fish meal as the primary protein source, and a sixth diet was included that used full-fat fish meal and extracted fish oil. Triplicate groups of rainbow trout (144 ± 20 mg initial weight) were fed experimental diets for 62 days on a restricted feeding regime (4–5.5% biomass/day). The group fed the full-fat fish meal diet had faster growth and a lower feed conversion ratio than the defatted fish meal diet groups after 31 and 62 days of feeding. The growth rate and feed conversion ratios of fish were significantly different between the FAEE-containing diet groups in the first 31 days of feeding, but were not significant from 32 to 62 days of feeding. Fatty acid analysis showed similarity between the fatty acid profiles in experimental diets and in fish muscle and liver tissues at the end of the experiment (all groups mean weight ~3.6 g/fish). Satiation feed intake for a single day was measured at 31 days of feeding, and feed intake was higher in the 100% FAEE diet than the control (8.3 ± 1.1% vs 6.4 ± 0.3% daily satiation ratio). This result suggests that FAEE has a positive effect on voluntary feed intake. Histological analysis of posterior intestine enterocytes and hepatocytes showed a significant reduction in lipid vacuole size in the 100% FAEE group, relative to the defatted and full-fat fish meal control groups. These results suggest that rainbow trout had utilized diet with ≥50% FAEE less efficiently in the first feeding phase, likely due to reduced fatty acid absorption, but that these trends were diminished as fish grew to a larger size.

Effects of dietary vegetable oils on growth, lipogenic enzyme activities and tissue fatty acid composition of Heterobranchus longifilis

Abstract Feasibility of total replacement of fish oil (FO) with vegetable oils (palm oil (PO) and soybean oil (SO)) in practical diet for Heterobranchus longifilis fingerlings was evaluated. Six iso-nitrogenous and iso-caloric diets were prepared. Control diet (A) used FO as the lipid source, diets B–F contained various blends of palm and soybean oils. Fish were fed to apparent satiation twice daily for twelve weeks. No significant (P &gt; 0.05) differences were observed for feed intake, weight gain, feed conversion ratio or specific growth rates among dietary treatments. Activities of glucose-6-phospate dehydrogenase (G6PDH) and malic enzyme (ME) were significantly (P &lt; 0.05) higher in fish fed diet C (1.5 % PO). Generally, hepatic G6PDH activity was about 3-4 times higher than ME activity in fish fed the experimental diets. The tissue fatty acid (FA) profiles in fillet and liver reflected the dietary FA compositions. However, the concentrations of eicosapentaenoic acid and docosahexaenoic acid were higher in fish tissue (fillet and liver) than in the diets. Results from the present study indicate that replacement of fish oil with vegetable oil resulted in satisfactory growth and body composition characteristics in Heterobranchus longifilis. Compared with soybean oil, palm oil is relatively cheap and readily available; therefore, diet F (6 % PO) is recommended for use in H. longifilis diet.

Growth performance and nutrient utilisation of Senegalese sole fed vegetable oils in plant protein-rich diets from juvenile to market size

Sustainable aquaculture is highly dependent on the optimization of aquafeeds in terms of production costs, environmental sustainability and nutritional value. Senegalese sole (Solea senegalensis) is a prized flatfish produced in Europe with demonstrated capacity to cope well with both vegetable protein and oil sources. However, the total replacement of fish oil (FO) in diets with a high inclusion of plant proteins (PP) has never been assessed before in this species. Three extruded isoenergetic (23 KJ/g) and isolipidic (15% DM) practical PP-based diets (75% PP) were formulated: a control diet with fish oil (FO) and two experimental diets with 50% and 100% inclusion of a vegetable oil (VO) blend to replace FO (VO50 and VO100). Triplicate groups of fish (13.3 ± 0.9 g) were kept in a recirculation saltwater system at 19 °C and fed the experimental diets ad libitum during 18 months. Fish were sampled after 6 and 18 months (in juvenile and on-growing developmental stages, respectively). The total substitution of FO by VO (VO100) during the juvenile phase (6 months of feeding) significantly reduced final body weight, daily growth index, and protein gain, and increased FCR. A longer feeding period (after 18 months) showed that VO inclusion had no major effects on fish growth, but FCR was still significantly higher in fish fed VO100 than in FO. At the end of the trial, muscle saturated FA level decreased with increasing dietary VO, whereas monounsaturated and polyunsaturated FA levels increased in fish fed VO diets particularly due to increased levels of linoleic, α-linoleic and arachidonic acid acids. In conclusion, the long-term replacement of marine ingredients by VO and PP sources does not impair Senegalese sole growth, but strongly reduces EPA + DHA muscle levels, compromising the nutritional value of fillets for human consumption.

Total replacement of dietary fish oil with alternative lipid sources in a practical diet for mandarin fish, Siniperca scherzeri, juveniles

A 12-week feeding trial was designed to evaluate the effect of total replacement of fish oil (FO) with terrestrial alternative oils on growth, feed utilization, body composition, hematological parameters, and fillet fatty acid profile of mandarin fish juveniles. Four iso-nitrogenous (56% crude protein) and iso-lipidic (13% crude lipid) practical diets were formulated. A control diet contained 6% FO and three other experimental diets were prepared by replacing FO with linseed oil, soybean oil, and lard (designed as FO, LO, SO, and lard, respectively). Each diet was randomly allocated to triplicate groups of 25 fish (1.8 ± 0.03 g/fish) in a circular tank. Complete replacement of FO by three tested alternative oils had no remarkable impact on growth performance, feed utilization efficiency, and morphological and hematological parameters of juvenile mandarin fish. However, daily feed intake was found to be significantly higher for fish fed the SO diet compared with those fed the FO and LO diets. Fish fed LO and SO diets exhibited significantly higher levels of the whole body lipid compared to fish fed diet containing FO. Fillet fatty acid composition reflected dietary fatty acid profile. The highest level of α-linolenic acid, linoleic acid, and oleic acid was observed in fish fillet fed LO, SO, and lard, respectively. Although the eicosapentaenoic acid level of fish fillet fed diet FO was higher than other treatments, no significant difference was found in docosahexaenoic acid content among all dietary groups. The results of the present study clearly demonstrate that the complete replacement of FO in mandarin fish diets is achievable. These findings are useful in dietary formulation to reduce feed costs without compromising mandarin fish growth.

Total Replacement of Fish Oil by Balanites aegyptiaca and Adansonia digitata Seed Oils in Diets of Clarias anguillaris Fry

Clarias anguillaris fries were fed with three isoproteic (30.25%) and isoenergetic (1.42 MJ/Kg) diets to evaluate the effects of plant seed oil on the growth performance, feed efficiency and survival rate. The test was carried out on Clarias anguillaris with an initial average weight of 0.07 g distributed in 6 plastic tanks with a stocking density of 15 fries each. The treatments were in duplicate for 45 days. The results of this experiment showed that the fish fed diet B containing Adansonia digitata seed oil as a source of lipid has the best total average weight gain (AWGa) (0.15g) compared to those fed with P and S diets containing fish oil and the Balanites aegyptiaca seed oil respectively. Similar results were obtained with the specific growth rate, which showed a significant difference between the fish fed with B diet and those fed with S and P diets that do not differ significantly between them. The best feed conversion rate (FCR) was obtained with the fish fed with B diet, which showed a significant difference with the fish fed with P and S. The best survival rate (SR) of 80% was obtained with the fish fed with diet B, followed by 73% in fish fed with diet S, and finally the lowest value 67% was contained in the fish fed with the control diet P. The best protein efficiency ratio (PER) was obtained with the fish fed with diet B (1.16) followed by the fish fed with diet S (0.80) compared with the fish fed with the control diet P (0.74). From the results of this study, we can say the replacement of fish oil with Balanites aegyptiaca seed oil and Adansonia digitata seed oil has no negative impact on the growth of Clarias anguillaris fries. In conclusion, diet B containing Adansonia digitata seed oil appears to be more suitable for Clarias anguillaris fry growth.

Partial and total replacement of fish oil by poultry fat in diets for European seabass (Dicentrarchus labrax) juveniles: Effects on nutrient utilization, growth performance, tissue composition and lipid metabolism

Rendered fats can be sustainable alternatives to fish oil due to their lower price and wider availability. This study evaluates the effects of replacing fish oil by increasing levels of poultry fat (PF) on the nutrient utilization, growth performance, tissue composition and lipid metabolism of European seabass (Dicentrarchus labrax) juveniles. Homogeneous groups of 20 fish (19.1 ± 2.6 g) were subjected to a 12-h light/12-h dark photoperiod regime and kept in a recirculating saltwater system (salinity 35‰, 21 ± 1 °C) for 16 weeks. Triplicate groups of fish were fed a commercial-based diet as control (FO) and four isonitrogenous experimental diets, with 25 (25PF), 50 (50PF), 75 (75PF) and 100% (100PF) fish oil replacement. Soy lecithin was also tested in the diet with 100% PF (100PFL) as an emulsifier agent. The inclusion of PF did not affect nutrient's digestibility nor plasma metabolites at 24 h post-feeding. Final body weight (62–67 g), feed intake, feed conversion ratio, protein efficiency ratio and whole-body composition were similar among experimental diets. Selected lipogenic enzymes' activities were similar among FO and PF diets. The fatty acids profile of muscle, liver and heart reflected the dietary lipid source, decreasing PUFA and increasing MUFA contents with PF inclusion. Fish fed 25PF and 50PF were still able to provide the EPA and DHA muscle levels recommended for human consumption, but 100PF resulted in increased liver lipid accumulation and reduced muscle omega-3 levels. Including soy lecithin could significantly attenuate liver lipid content in fish fed PF-based diets.

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

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, 20g): 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 (23kJg−1 DM). After 114days 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 (>0.3g/100g).

Effects of totally replacing dietary fish oil by linseed oil or soybean oil on juvenile hybrid sturgeon,Acipenser baeriBrandt♀×A. schrenckiiBrandt♂

The growth performance, body composition, fillet fatty acid content, serum hepatic enzymes and postprandial changes in serum lipid metabolism of hybrid sturgeon (70.8 ± 0.5 g) were investigated to determine the effects of total replacement of 80 g kg-1 fish oil (diet A) with linseed oil (diet B) and soybean oil (diet C), respectively. No significant differences in weight gain rate and specific growth ratio were observed among all fish groups (p > .05). Diet A fish group had the highest, but diet B fish group had the lowest feed intake (p .05). In summary, total replacement of fish oil with linseed oil or soybean oil had no significant adverse effects on hybrid sturgeon growth during 84-day period, and linoleic acid and linolenic acid in fillet were modified by dietary treatments.

The implications of substituting dietary fish oil with vegetable oils on the growth performance, fillet fatty acid profile and modulation of the fatty acid elongase, desaturase and oxidation activities of red hybrid tilapia, Oreochromis sp.

A 75-day feeding trial was carried out to examine the effects of fish oil (FO) replacement with various alternative vegetable oil (VO) on the growth performance and feed utilization efficiency of red hybrid tilapia (Oreochromis sp.). The VO evaluated included canola oil (high in monoenes), perilla oil (high in n−3 polyunsaturated fatty acids, PUFA), sunflower oil (high in n−6 PUFA) and refined, bleached, deodorized palm olein (high in saturates) added as the sole lipid source in semi-purified experimental diets. The ability of hybrid tilapia to biosynthesize long chain-polyunsaturated fatty acids (LC-PUFA) from dietary 18:2n−6 and 18:3n−3 was also determined. With the exception of sunflower oil, results showed that total FO replacement by various VO did not compromise (P>0.05) tilapia growth performance. However, dietary VO significantly (P<0.05) influenced the fatty acid composition of tilapia fillet and whole-body lipids through changes in the overall fatty acid metabolism. The total Δ5 and Δ6 fatty acid desaturase activities were exclusively triggered in tilapia fed VO-based diets. Tilapia fed the VO diets, which contained no PUFA longer than C18, recorded significant amounts of both n−6 and n−3 LC-PUFA in their tissue lipids. Dietary canola oil (CO) increased Δ-6 desaturation of 18:3n−3 to the greatest extent despite the dietary 18:3n−3 content being comparatively lower than dietary perilla oil (PeO). Beta-oxidation of 18:3n−3 was observed to be highest in fish fed the PeO diet, indicating that the 18:3n−3 content in the PeO diet exceeded the optimum substrate level for Δ-6 desaturase. Omega-3 LC-PUFA biosynthetic activities were highest in fish fed the CO diet and resulted in a comparatively higher eicosapentaenoic acid (EPA)+docosahexaenoic acid (DHA) content than in fish fed other VO diets. However, endogenous LC-PUFA synthesis induced by the VO diets was insufficient to rival the n−3 LC-PUFA content of fish fed the FO diet. It was also observed that β-oxidation of 18:3n−3 and 18:2n−6 was regulated by tissue n−3/n−6 PUFA ratio and proportional to their dietary level. This study provided the first comprehensive evidence of the significant impact of dietary oils with different fatty acid class profile on the in vivo fatty acid metabolism of tilapia. Statement of relevanceMarine fish oil (FO) was traditionally used as the major lipid source in commercial tilapia feeds to provide energy and essential fatty acids as well as to impart palability to the feed. With the rising costs of FO and limited global supplies, the use of alternative lipid resources in aquafeeds, including tilapia feeds, has become more critical to enable the continued sustainability and scalability of the global aquaculture industry. Terrestrial vegetable oil (VO) are viable alternatives since their production is more sustainable and cost-effective. However, unlike FO, which is rich in n−3 long chain-polyunsaturated fatty acids (LC-PUFA), VO are deficient in these essential fatty acids and but high in other fatty acid classes. The present study evaluated perilla oil (high levels of n−3 polyunsaturated fatty acids), sunflower oil (rich in n−6 PUFA), canola oil (high amounts of monounsaturated fatty acids) and palm oil (rich in saturated fatty acids) together with fish oil. By understanding how dietary lipid source with different major fatty acid classes modulates in vivo fatty acid metabolism, we can better formulate fish feeds that can optimize not only growth performance but also maintaining the health benefits of eating seafood for the human consumer in regards to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels in farmed fish fillets. As far as we know, there is currently no information comparing the fatty acid metabolism of red hybrid tilapia fed diets with lipids containing different major fatty acid classes.

Dietary Oil Source and Selenium Supplementation Modulate Fads2 and Elovl5 Transcriptional Levels in Liver and Brain of Meagre (Argyrosomus regius).

The meagre (Argyrosomus regius) is taking on increasing importance in the aquaculture industry. In view of the limited supply of fish oil (FO) as a feed ingredient, the study of the capacity to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFA) from alternative dietary oil sources is important. We analyzed changes in fatty acid (FA) desaturase 2 (fads2) and FA elongase 5 (elovl5) mRNA levels in livers and brains in response to FO replacement with a blend of vegetable oils (VO) and selenium (Se) supplementation. Fish were fed for 60days with either a diet containing FO or a diet including VO, each supplemented or not with organic Se. Results showed that fads2 and elovl5 transcription was higher in liver when fish were fed VO diets. The brain mRNA levels of both genes were not affected by the dietary replacement of FO by VO. FA composition in the liver and skeletal muscle was altered by FO replacement, particularly by decreasing eicosapentaenoic acid and docosahexaenoic acid contents. The α-linolenic, linoleic, and arachidonic acid contents increased in both liver and brain of fish fed VO diets. The effect of Se supplementation on lipid metabolism was evident only in fish fed FO, showing a decrease in the transcription of hepatic fads2. Results indicate that the total replacement of FO by VO in diets modulates the expression of genes involved in LC-PUFA biosynthesis in meagre, affecting the FA profile of the fish flesh.