Replacement Of Dietary Fish Oil Research Articles

The use of fishery and aquaculture by-products with Nannochloropsis sp. allows total dietary replacement of wild-caught fishmeal, fish oil and soy protein in European sea bass juveniles

Five experimental diets (CTRL, 50FMFO, 50FMFO-50MIC, 0FMFO-50MIC, 0FMFO-100MIC) were formulated to replace wild-caught fishmeal (FM), wild-caught fish oil (FO) and soy protein using fisheries, aquaculture by-products (BP) and microalgae (MIC). Fifty European sea bass juveniles were distributed in 15 tanks (initial body weight 46.66 ± 0.04 g) and reared in a recirculating aquaculture system for 88 days. Temperature, salinity, oxygen and photoperiod were kept constant throughout the experiment (22 ± 0.5 °C, 25 g L−1 and 8.0 ± 1.0 mg L−1, 12:12 light/dark, respectively). Growth, feed intake (FI), proximal composition, nutritional index, apparent digestibility, somatometric indexes, blood plasma biochemistry and digestive enzyme activity were evaluated. Also, gut microbiota composition was assessed through next-generation sequencing. Results showed that growth performance and feed digestibility were not affected by FM, FO and soy replacement using BP and MIC. Dietary replacement of 100% FM and FO with circular substitutes and 50% replacement of soymeal with microalgae increased the activity of alkaline phosphatase and chymotrypsin. Moreover, the inclusion of BP and MIC had positive effects on the gut microbiota richness and abundance. In conclusion, the utilization of BP and MIC represents a valuable alternative to FM and FO as well as soy protein in feed for European sea bass juveniles.

Dietary LC-PUFA and environmental salinity modulate the fatty acid biosynthesis capacity of the euryhaline teleost thicklip grey mullet (Chelon labrosus).

The capacity to biosynthesise long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA) depends upon the complement and function of key enzymes commonly known as fatty acyl desaturases and elongases. The presence of a Δ5/Δ6 desaturase enabling the biosynthesis of docosahexaenoic acid (22:6n-3, DHA) through the "Sprecher pathway" has been reported in Chelon labrosus. Research in other teleosts have demonstrated that LC-PUFA biosynthesis can be modulated by diet and ambient salinity. The present study aimed to assess the combined effects of partial dietary replacement of fish oil (FO) by vegetable oil (VO) and reduced ambient salinity (35ppt vs 20ppt) on the fatty acid composition of muscle, enterocytes and hepatocytes of C. labrosus juveniles. Moreover, the enzymatic activity over radiolabelled [1-14C] 18:3n-3 (α-linolenic acid, ALA) and [1-14C] 20:5n-3 (eicosapentaenoic acid, EPA) to biosynthesise n-3 LC-PUFA in hepatocytes and enterocytes, and the gene regulation of the C. labrosus fatty acid desaturase-2 (fads2) and elongation of very long chain fatty acids protein 5 (elovl5) in liver and intestine was also investigated. Recovery of radiolabelled products including stearidonic acid (18:4n-3, SDA), 20:5n-3, tetracosahexaenoic acid (24:6n-3, THA) and 22:6n-3 in all treatments except FO35-fish, provided compelling evidence that a complete pathway enabling the biosynthesis of EPA and DHA from ALA is present and active in C. labrosus. Low salinity conditions upregulated fads2 in hepatocytes and elovl5 in both cell types, regardless of dietary composition. Interestingly, FO20-fish showed the highest amount of n-3 LC-PUFA in muscle, while no differences in VO-fish reared at both salinities were found. These results demonstrate a compensatory capacity of C. labrosus to biosynthesise n-3 LC-PUFA under reduced dietary supply, and emphasise the potential of low salinity conditions to stimulate this pathway in euryhaline fish.

Effects of replacement of dietary fish oil with plant oil on growth performance and fatty acid composition of spinefoot rabbitfish, Siganus rivulatus.

A 95-day feeding study was carried out to evaluate the impact of complete replacement of fish oil by plant oils in the growth performance, feed consumption fatty acid and body composition of juvenile rabbitfish, Siganus rivulatus. There were four treatments i.e., A (fish oil diet), (linseed oil diet), C (soybean meal oil diet) and D (sunflower oil diet). The experimental trial was conducted in twelve 1.5-m3 fiber glass tanks (n=3). Spinefoot rabbitfish juveniles had an average initial weight of 0.948 g ± 0.124 g and they were stocked at 50 fish per tank. Fish fed diet A showed significantly better growth rate, final body weight, and total body weight than fish fed on the other diets. Moreover, the best FCR was observed for diet A followed by diet C and diets B and D had the worst FCR. Fish body composition for crude protein, dry matter, ashes and gross energy at the end of the trial had not differed between the treatments. The highest polyunsaturated fatty acids (PUFA) was found in fish fed diet A followed in decreasing order by diets D, B, and C. Fish oil is a better dietary lipid source for Spinefoot rabbitfish juveniles, Siganus rivulatus, than plant oils. Among plant oils, soybean oil was better than linseed oil and sunflower oil as the main dietary fat source.

Malformed jaw phenotype and replacement of dietary fish oil by olive oil affect fatty acid composition, antioxidant defense and the expression of the retinoic signaling pathway in juvenile Seriola lalandi (Valenciennes, 1833)

Yellowtail kingfish (Seriola lalandi) is a valuable commercial aquacultural product in high demand in several countries. Growth performance, survival, lipid content, antioxidant enzyme system defense, gene expression and malformation were investigated in the juvenile specimens subjected to different diets. Three experimental diets with different proportions of fish oil (FO) and olive oil (OO) and different levels of long chain polyunsaturated fatty acids (LC PUFA), were formulated and manufactured: D1: 100% FO + 0% OO; D2: 50% FO + 50% OO; D3: 0% FO + 100% OO. S. lalandi juveniles weighing 0.81 g (57 days dph) were fed during four weeks with experimental diets (D1, D2, and D3). Samples of normal or malformed-jaw fish were collected at the end of the feeding trial. Although the incidence of malformations seemed to slightly increase with the incorporation of OO, the statistical association between diet and the malformation rate was not clear. The most frequent malformation observed was shortening of the lower jaw, followed by shortening of the upper jaw. At the gene expression level, the antioxidant genes CAT, SOD, GPX, RXR and PPAR were upregulated in malformed-jaw fish compared to normal specimens, independent of their diets. The results of multi-dimensional scaling suggest that a disruption of hepatic lipid composition may be associated with jaw and operculum malformations in juvenile S. lalandi.

Partial and full replacement of dietary fish oil by poultry fat feeds in rainbow trout, Oncorhynchus mykiss

ABSTRACT The study investigated the effects of dietary fish oil replacement by poultry fat on growth performance, fillet quality, and serum enzymatic activities in rainbow trout, Oncorhynchus mykiss. The fish were fed three diets (0%, 50%, and 100% replacement) for 2 months with or without a washout period. No significant effects were observed among treatments on growth performance and viscerosomatic index or on fillet moisture, fat, protein, and ash contents (p > .05). Increased poultry fat led to decrease in ω-3 fatty acids and increase in ω-6 fatty acids and monounsaturated fatty acids. The washout period restored most of the changes in fillet fatty acid profiles and serum enzymatic activity in the fish feed containing poultry fat. In conclusion, replacement of dietary fish oil by poultry fat had no detrimental effects on fish growth performance, but reduced fish fillet ω-3 fatty acids, which can be restored via a washout period.

Fillet Quality in Rainbow Trout (Oncorhynchus mykiss) Raised on Different Dietary Oils Over a Long-Term Feeding Trial

ABSTRACT Effects of dietary fish oil replacement with vegetable oils on physical and sensorial qualities and shelf life of rainbow fillet were investigated. Color did not change in red muscle, while white muscle was redder (a* 0.88) in hazelnut oil-fed fish. Red muscles from fish oil-fed fish had higher lipid peroxidation in all cases, while dietary hazelnut oil decreased lipid peroxidation and increased α-tocopherol content. General acceptance by consumers did not change among treatments. Overall, fish oil replacement did not cause any remarkable inconvenience in sensory attributes, on the contrary, dietary vegetable oils, especially hazelnut oil, increased oxidative stability during storage.

Proteomics and phosphoproteomics analysis identifies liver immune protein markers in large yellow croakers (Larimichthys crocea) fed a soybean oil-based diet

Dietary fish oil (FO) replacement has led to an inflammatory response in fish species. This study aimed to identify immune-related proteins in the liver tissue of fish fed a FO-based or soybean oil (SO)-based diet. By conducting proteomics and phosphoproteomics analyses, a total of 1601 differentially expressed proteins (DEPs) and 460 differentially abundant phosphorylated proteins (DAPs) were identified, respectively. Enrichment analysis revealed immune-related proteins involved in bacterial infection, pathogen identification, cytokine production, and cell chemotaxis. The mitogen-activated protein kinase (MAPK) pathway exhibited significant alterations in both protein and phosphorylation levels, with several hub DEPs and DAPs associated with MAPK pathway and leukocyte transendothelial migration being notable. In vitro experiments indicated that linolenic acid (LNA), derived from SO, inhibited the expression of NF-E2-related factor 2 (Nrf2), but increased the expression of signaling proteins linked to nuclear factor κB (NF-κB) and MAPK pathways. Transwell assays indicated that treatment of liver cells with LNA promoted macrophage migration. Collectively, the results showed that the SO-based diet upregulated the expression of NF-κB signaling-related proteins and activated the MAPK pathway, promoting immune cell migration. These findings provide novel insights for developing effective solutions to alleviate health problems caused by dietary high levels of SO inclusion.

Hepatic, Muscle and Intestinal Oxidative Status and Plasmatic Parameters of Greater Amberjack (Seriola dumerili, Risso, 1810) Fed Diets with Fish Oil Replacement and Probiotic Addition.

The present study was conducted to investigate the effects of dietary fish oil replacement with a mixture of vegetable oils and probiotic supplementation on plasma biochemical parameters, oxidative stress, and antioxidant ability of Seriola dumerili. Specimens with an initial weight of 175 g were used. Four feeds were formulated with 0% (FO-100), 75% (FO-25), and 100% (FO-0 and FO-0+ with the addition of Lactobacillus probiotics) substitution of fish oil with a mixture of linseed, sunflower, and palm oils. After 109 days, no significant differences were observed in the activity of antioxidant enzymes in the liver, foregut, and hindgut, only glucose-6-phosphate dehydrogenase activity in the liver was higher in the fish fed the FO-100 diet than in those fed the FO-0 diet. No significant differences were observed in the total, reduced, and oxidized glutathione and the oxidative stress index in the liver. In addition, lipid peroxidation in the liver and red muscle values were higher in the fish fed the FO-100 diet than in the fish fed the FO-0+ diet, however, the foregut of the fish fed the FO-100 diet presented lower values than that of the fish fed the FO replacement diet, with and without probiotics. There were significant differences in cholesterol levels in the FO-100 group; they were significantly higher than those observed with the fish diets without fish oil. To sum up, fish oil can be replaced by up to 25% with vegetable oils in diets for Seriola dumerili juveniles, but total fish oil substitution is not feasible because it causes poor survival. The inclusion of probiotics in the FO-0+ diet had no effects on the parameters measured.

Effects of dietary replacement of fish oil with different lipid sources on growth, fatty acid composition, mineral content and expression levels desaturase and elongase genes in rainbow trout (Oncorhynchus mykiss)

In this study, the effects of alternative lipid sources on growth, mineral content, proximate composition, fatty acid profile and gene expression of rainbow trout were investigated. Four different diets were prepared with isonitrogenous and isolipid casein-gelatin based formulations, consisting of cod liver oil (CO), goose fat (GF), soybean oil (SO) and mixture of cod liver oil, goose fat and soybean oil (BLEND). Rainbow trout were randomly distributed in three replicate research tanks with 25 fish per tank for each diet group, and the feeding trial lasted for 56 days. Dietary lipid sources did not significantly affect growth performance, feed conversion ratio, survival rate and whole-body mineral composition. The crude lipid and neutral lipid contents were found to be highest in the fish fed GF diet and lowest in the CO group. MUFA content was increased by GF, while it was decreased by SO. Diets generally increased the amount of n-6 PUFA while it decreased the amount of n-3 PUFA and the ratio of n-3/n-6 PUFAs compared to control. The GF diet decreased whole body α-linolenic acid (ALA) and linolenic acid (LA) levels, while SO and BLEND increased these levels. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels were decreased generally in three diets compared to the control group. mRNA expression levels of delta-6-desaturase enzyme were increased in SO and BLEND groups with highest values in SO in both muscle and liver tissues. Elongase expression levels were increased in GF and BLEND groups with highest values in GF in both muscle and liver tissues. It was concluded that synthesis of EPA and DHA from LA and ALA is limited in fish fed all diets. Goose fat can be promising dietary source due to its potential of increasing the n-6 content, decreasing the moisture holding capacity and positive effect on flesh quality.

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.

Dietary fish oil levels modulated lipid metabolism, immune response, intestinal health and salinity stress resistance of juvenile Penaeus monodon fed a low fish-meal diet

Dietary fish meal (FM) and fish oil (FO) replacement are crucial for the sustainable development of aquaculture. An eight weeks feeding trial was conducted to evaluate the potential replacing FM with soy protein concentrate, and the suitable FO level for a low FM diet of Penaeus monodon. A diet containing 25% FM was used as the control (C diet), and three other diets were formulated to contain 15% FM, and supplemented with 3%, 2%, 1% FO [high FO (HF), medium FO (MF) and low FO (LF), respectively]. The experiment was conducted in quadruplicates (30 shrimp per replicate, average weight 1.00 ± 0.01 g). The results indicated that besides the final body weight, there were no differences in weight gain, feed efficiency and survival rate observed among the four groups. The results of the acute salinity stress showed that shrimp fed the C and MF diets showed a similar survival rate, which was significantly higher than those fed a LF diet. Shrimp that were fed HF, MF and LF diets showed a lower level of fatty acid transport-related mRNA expression in the hepatopancreas, compared with those fed the C diet. Shrimp fed HF, MF and LF diets showed lower expression levels of superoxide dismutase, endoplasmic reticulum protein 57 and immune deficiency (IMD) in the hepatopancreas than those fed the C diet. Shrimp that were fed a LF diet showed the lowest expression levels of inhibitor of apoptosis proteins, Toll and tumor necrosis factor receptor associated factor 6 (TRAF6) in the hepatopancreas, as well as the highest expression levels of Toll, extracellular signal-regulated kinase, Relish and TRAF6 in the intestine among four groups. Intestinal microstructure damage was observed in shrimp that were fed a LF diet, and intestinal endoplasmic reticulum (ER) swelling was observed in shrimp fed MF and LF diets. In conclusion, these results indicated that the growth performance of shrimp was not affected when the FM and FO contents decreased, whereas a low content of FM negatively influenced the immune response in shrimp by modulating IMD and ER stress related gene expression. Under low FM conditions, a suitable dietary FO level would benefit to the lipid transport, hepatopancreas and intestine health, as well as the immune response of shrimp.

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.

Replacement of fish oil with black soldier fly larvae oil and vegetable oils: Effects of growth, whole‐body fatty acid profile, digestive enzyme activity, haemato‐biochemical responses and muscle growth‐related gene expression of juvenile striped catfish, Pangasianodon hypophthalmus

A 10-week feeding trial was conducted to evaluate the effects of dietary replacement of fish oil (FO) with black soldier fly larvae oil (BSFLO) and vegetable oils, namely moringa oil (MO), black cumin seed oil (BCSO) and flax seed oil (FSO) on growth and whole-body fatty acid profile, digestive enzyme activity, haemato-biochemical responses and muscle growth-related gene expression of juvenile striped catfish, Pangasianodon hypophthalmus. Five isonitrogenous (313.34 g kg−1) and isolipidic (81.82 g kg−1) experimental diets were formulated. A total of 450 fingerlings (5.02 ± 0.1 g per fish) were randomly distributed into 15 tanks and fed thrice a day. The final weight gain was significantly improved in fish fed FO (45.7 ± 0.72 g/fish), BSFLO (45.53 ± 1.32 g/fish) and MO diet (47.2 ± 0.26 g/fish) when compared to BCSO (36.3 ± 1.05 g/fish) and FSO (35.83 ± 0.71g/ fish) diets. The lower value of daily weight gain was recorded in the FSO and BCSO treatments compared with other oils could be due to effects on stress resistance and immunosuppression in fish, whereas the whole-body EPA and DHA content of fish fed with FSO and FO diets was substantially higher than fish fed with other experimental diets. However, the relative expression of Myo D and Myogenin was upregulated in fish fed with FO, BSFLO and MO diet than the BCSO and FSO diet. Present results indicate that the juveniles can be reared on diets in which FO has been replaced with BSFLO and MO, with no significant effects on fish performance.

Integrated Analysis of Metabolomics and Transcriptomics for Assessing Effects of Fish Meal and Fish Oil Replacement on the Metabolism of Rainbow Trout (Oncorhynchus mykiss)

Reducing dependency on dietary fish meal (FM) and fish oil (FO) is extremely important for the sustainable development of the aquaculture industry. However, the metabolic consequences and mechanisms underlying the replacement of dietary FM and FO by terrestrial proteins (TPs) and lipids remain unclear. To reveal the effects of replacing dietary FM and/or FO on the metabolic changes, the integrated analysis of metabolomics and transcriptomics were employed to evaluate the changes in metabolites and genes of rainbow trout (Oncorhynchus mykiss) feeding different experimental diets. Four diets were formulated for the 84-day duration of the experiment: control group (FMFO), FM and vegetable oil (FMVO), terrestrial protein and FO (TPFO), and terrestrial protein and vegetable oil (TPVO). Integrated metabolomic and transcriptomic analyses revealed the significant difference in the metabolic pathways of O. mykiss among the three replacement schemes, i.e., single replacement of dietary FM by TP, single replacement of dietary FO by VO, and combined replacement of FM by TP and FO by VO. The combined replacement of FM and FO by TP and VO, respectively, disturbed immune function, energy metabolism, cellular protein biosynthesis capacity, and lipid metabolism of O. mykiss. The reduction of antioxidant capacity was only observed in individuals feeding diets with replacement of FM by TP. Furthermore, as soon as the dietary FM and/or FO were reduced, cellular protein biosynthesis ability was suppressed and accompanied by higher energy consumption in response to fluctuations of dietary quality, resulting in reduced growth performance. Interestingly, adenylosuccinate and adenosine monophosphate involved in purine metabolism were induced by both individual and combined replacement of FM and FO by TPs and lipids, respectively. It suggested that these two metabolites might be potential biomarkers for O. mykiss fed diets with reduction of FM and/or FO. This study constitutes a new understanding of the molecular and metabolic mechanisms of O. mykiss in response to the replacement of dietary FM and/or FO by TP and/or VO, respectively, and built a theoretical basis for further improvement of aquafeed formulation and sustainable development of aquaculture.

Lipid variations in tilapia (var. GIFT Oreochromis sp.) tissues due to dietary replacement of fish oil with camelina oil ( Camelina sativa )

Dietary fish oil can potentially be replaced by camelina oil in aquafeeds since 18:3n-3 (α-linolenic acid: ALA) accounts for 35% of the fatty acids. To test the effect of camelina oil on fish lipid composition, a feeding trial with tilapia (var. GIFT Oreochromis sp.) was carried out. Four experimental diets were formulated, one containing only fish oil (TFO), two where fish oil was replaced by camelina at low (Low-CO) and medium (Med-CO) levels, and another made only with camelina oil (TCO). A commercial diet (COM) was used as a reference diet. At the end of an 8-week feeding trial, the liver, kidney, heart and brain were sampled. In terms of proportions across tissues, the liver showed the highest triacylglycerol and oleic acid content; the kidney was higher in arachidonic (ARA) and eicosapentaenoic acid (EPA); the heart had the highest total lipids, linoleic acid (LOA) and ALA, while the brain was higher in sterols, acetone-mobile polar lipids (AMPL), phospholipids and docosahexaenoic acid (DHA). In terms of concentration among diets within tissues, when comparing TFO vs TCO, the phospholipids and ARA increased in the kidney, while the phospholipids decreased in the heart and the DHA in the brain. The TCO diet significantly increased 20:1n-9 and ALA in all analysed tissues. As expected, the COM diet significantly increased concentrations of EPA, docosapentaenoic acid (n-3DPA) and DHA in all analysed tissues.

Effects of L‐carnitine supplementation on growth performance, histomorphology, antioxidant and immune function of Rhynchocypris lagowskii fed dietary fish oil replaced with corn oil

The effects of L-carnitine (LC) and dietary lipid on the growth and health of farmed fish are still conflicting. This study aimed to explore the effects of LC supplementation and dietary fish oil replacement by corn oil on growth performance, antioxidant, immune function and histomorphology of Rhynchocypris Lagowskii. Six diets were evaluated as follows: dietary fish oil as 50% and 100% replacement by corn oil, and differing in LC supplementation (0 and 400 mg/kg), were tested in R. Lagowskii for 8 weeks. The highest weight gain rate, specific growth rate and feed efficiency were observed in mix oil diets with LC. The diet with LC significantly increased the total antioxidant capacity level, total superoxide dismutase, alkaline phosphatase, lysozyme activities and immunoglobulin M, complement levels in liver and intestine compared with corn oil diet (p < 0.05). Moreover, the diet with LC significantly up-regulated the nuclear factor E2-related factor 2 (p < 0.05), and significantly down-regulated the interleukin-1-beta and tumour necrosis factor-alpha expression in liver and intestine compared with corn oil diet (p < 0.05). In conclusion, LC supplementation improved the weakening of growth performance, antioxidant capacity, immune function and tissue health caused by R. lagowskii intake of corn oil diets.

Effect of dietary fish oil replacement with grape seed oil on growth performance, feed utilization and fatty acid profile of mirror carp, Cyprinus carpio , fingerlings

This study aimed to investigate the effect of grape seed oil (GSO) on growth performance, feed utilization and the fatty acid profile of mirror carp fingerlings. Five isonitrogenous (36 g/100 g) and isoenergetic (3650 kcal/kg) diets supplemented with 0% (control), 0.5%, 1%, 2% and 3% of GSO were prepared. Three hundred fish (3.65 g) were randomly allocated in five trial groups in triplicate with 20 fish per aquarium and fed three times a day with experimental diets at satiation level for 84 days. Growth performance and feed utilization in fish were similar among all test groups, except for the GSO-0.5 group. The condition factor, feed intake, hepatosomatic index, viscerosomatic index and proximate composition were not affected by GSO inclusion levels, except fatty acid profiles in fish flesh. The highest Σn3-PUFA and Σn6-PUFA values were observed in the GSO-3 group, whereas this group showed the lowest atherogenic and thrombogenic index values compared with the other test groups. The ratio of hypocholesterolaemic/hypercholesterolaemic fatty acids in fish also increased by GSO inclusion levels. The results suggest that GSO supplementation up to 3% could improve fish flesh fatty acid profile and lipid quality without adverse effect on growth performance and feed utilization in mirror carp fingerlings.

Growth performance, fatty acid composition, and lipid metabolism are altered in groupers (Epinephelus coioides) by dietary fish oil replacement with palm oil.

In this study, we conducted a 56-d feeding trial to investigate the effects of replacing the fish oil (FO) with palm oil (PO) on the performance, tissue fatty acid (FA) composition, and mRNA levels of genes related to hepatic lipid metabolism in grouper (Epinephelus coioides). Five isolipidic (13% crude lipid) and isonitrogenous (48% CP) diets were formulated by incrementally adding PO to the control diet (25% fish meal and 9% added FO) to replace FO in the control diets. Triplicate groups of 30 groupers (initial weight: 12.6 ± 0.1 g) were fed one of the diets twice daily, to apparent satiety. The replacement of FO with 50% PO revealed maximum growth without affecting the performance and whole-body proximate compositions, and replacing FO with 100% PO revealed a comparable (P > 0.05) growth with that of the control diet, suggesting PO as a suitable alternative to FO. The analysis of FA profiles in the dorsal muscle and liver though reflected the FA profile of the diet, PO substitutions above 50% could compromise (P < 0.05) the FA profile in the liver and flesh of the fish species in comparison with the control diet. Furthermore, the mRNA levels of FAS, G6PD, LPL, PPARΑ, and Δ6FAD genes in the liver had positive linear and/or quadratic responses, but the SCD, HSL, ATGL, FABP, SREBP-1C and ELOVL5 had the opposite trend, with increasing dietary PO inclusion levels, whereas the mRNA level of ACC was not affected by dietary treatments. The optimal level of PO substitution for FO was estimated to be 47.1% of the feed, based on the regression analysis of percent weight gains against dietary PO inclusion levels; however, it might affect the FA profile in the liver and flesh of the fish species, and further study is required to investigate whether the changes in tissue FA composition will affect the welfare and market value over a production cycle of grouper.

Total replacement of dietary fish oil with vegetable lipid sources influenced growth performance, whole body composition, and protein retention in Nile tilapia (Oreochromis niloticus) fingerlings

ABSTRACT Several reports show that aquaculture is the fastest food-producing sector globally, contributing nearly half of global fish production from all sectors. However, there has been a steady decline in production of fish oil (FO), which supports intensive aquaculture production. This has resulted in variable but generally increasing prices of FO. Finding suitable alternatives to scarce FO is essential for aquaculture sustainability. Therefore an experiment was carried out to investigate the influence of complete FO substitution with vegetable oil (VO) in the diet of Oreochromis niloticus fingerlings on growth performance, whole-body composition, and protein retention. Four isonitrogenous (30% crude protein), isolipidic (8% crude lipid), and isocalorific (17 MJ kg−1gross energy) basal diets were formulated as follows: a control diet was formulated to contain 5% FO and labeled FOD (fish oil diet), and three other diets were formulated and labeled SOD (soya oil diet), GOD (groundnut oil diet), and POD (palm oil diet); they contained soya oil (SO), groundnut oil (GO), and palm oil (PO) respectively as total replacements for FO. Triplicate O. niloticus fingerlings (N = 120, n = 10, 1.20 ± 0.03 g, mean weight ± SD) were randomly allocated to one of four experimental diets. Fish were hand-fed to apparent satiation twice daily for 63 days. The result obtained from the experiment revealed that dietary lipids significantly influenced growth performance and nutrient utilization of O. niloticus (P < 0.05). The fish fed POD had the least weight gain (WG) and highest feed conversion ratio (FCR) compared with fish fed FOD, SOD, and GOD from days 7–28 (P < 0.05). At day 35 the fish fed SOD had the highest WG (P < 0.05); fish fed GOD had the least WG. The best weekly overall growth at the end of day 56 was observed in fish fed FOD; fish fed POD had the least WG. At day 63, WG of fish fed FOD declined significantly compared to fish fed GOD, POD, and SOD, which had the best growth. At the end of the trial, the best cumulative growth in fish was observed for fish fed FO; however, there were no significant differences (P < 0.05) in WG and FCR between fish fed FOD and SOD. Survival was 100% for all treatments. Fish fed POD exhibited significantly lower levels of whole-body protein compared to fish fed FOD, SOD, and GOD. Fish fed a diet containing FO had the highest (P < 0.05) whole protein compared to diets with VO. However, no significant difference (P < 0.05) between whole-body protein of fish fed FOD and SOD was observed. Fish fed SOD had the highest (P < 0.5) body lipid compared with fish fed the FO, GO, and PO diets. In conclusion, the study has demonstrated that VO can completely replace FO in Nile tilapia diet without affecting growth performance of O. niloticus and that tilapia diet containing SO is a better alternative to FO compared to GO and PO. These findings are useful in dietary formulation to reduce feed costs without compromising tilapia fish growth.

Yemdeki balık yağının bitkisel yağlarla tamamen değiştirilmesinin optimum ve yüksek su sıcaklığında beslenen gökkuşağı alabalığının (Oncorhynchus mykiss) büyüme performansı, besin kalitesi ve yağ asidi profili üzerine etkileri

The present study investigated the effects of total replacement of dietary fish oil by different vegetable oils on growth performance, nutritional quality and fatty acid profiles of rainbow trout (Oncorhynchus mykiss) at optimum and high temperature conditions. Five iso-nitrogenous and iso-lipidic diets including 100% fish oil and vegetable oils were prepared for rainbow trout fingerlings with an average weight of 11.27±0.01 g. After the fish were fed experimental diets for 9 weeks at the optimum temperature (17.74±0.01°C), all groups were fed an FO diet containing only fish oil for 4-weeks at the upper optimum temperature conditions (19.28±0.11°C). In both feeding trials, experimental fish were hand-fed ad libitium twice a day. Results showed that growth performance and feeding efficiency were significantly better (p&lt;0.05) in groups fed by VO-based diets compared to groups fed by FO based diet at optimum temperature. Survival was 100% in CANO, SFO, CO PNO groups and 94.12±3.39% in FO (control) group at the end of the 9 weeks. Growth, feed consumption and survival of fish fed the upper-optimum temperature were significantly differed (p&lt;0.05). In particular, while the survival rate of the groups fed with vegetable oil-based diets at optimum temperature and then fed only fish oil remained 100%, this rate decreased to 54.17±1.39% in the control group. Eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and n-3 PUFA of fish fed by VO based diets were low. When all groups were fed only FO diet for 4 weeks at upper-optimum temperatures, EPA, DHA and n-3 PUFA ratios increased. In addition, after the upper-optimum temperature trial, increases in the nutritional quality indices of fish meat were also detected.