Effects of dietary n‐3 to n‐6 fatty acid ratios on spawning performance and larval quality in tongue sole Cynoglossus semilaevis

This study investigated the effect of n‐3 to n‐6 fatty acid ratios in broodstock diets on reproduction performance, fatty acid composition of eggs and gonads of tongue sole Cynoglossus semilaevis. Broodstock were fed five isonitrogenous and isoenergetic diets for 60 days. The supplemented lipids were prepared by a combination of fish oil and soybean oil inclusion FO (fish oil); FSO1 (fish oil: soybean oil = 7:1); FSO2 (fish oil: soybean oil = 2.2:1); FSO3 (fish oil: soybean oil = 1:1); FSO4 (fish oil: soybean oil = 1:4.3) as lipid sources with different n‐3 to n‐6 fatty acid ratios 10.40, 5.21, 2.81, 1.71 and 0.87. Results showed that relative fecundity, fertilization rate and survival rate of larvae at 7 days posthatching were all higher in broodstock fed FSO1 and FSO2 diet and significantly (P < 0.05) decreased in groups fed FSO3 and FSO4 diets. The best result in starvation tolerance test was obtained in FSO2 diet. The present study suggests that n‐3 and n‐6 PUFA ratio in broodstock diet has a considerable effect on spawning performance, egg and larval quality for C. semilaevis.     

Dietary fish oil replacement by soybean oil: Effect on plasma vitellogenin,sex steroids and ovarian steroidogenesis in Chinese strip‐necked turtles (Mauremys sinensis)

In order to investigate the effects of dietary fish oil replacement, the turtles (Mauremys sinensis) were fed four experimental diets for 10 months: FO (100% fish oil), FSO (70% fish oil and 30% soybean oil), SFO (30% fish oil and 70% soybean oil) and SO (100% soybean oil), sampled at pre‐vitellogenesis, vitellogenesis and post‐vitellogenesis. The results showed that plasma gonadotropin‐releasing hormone (GnRH) levels were the highest at pre‐vitellogenesis, which promoted the secretion of gonadotropin and sex steroids. Therefore, plasma luteinizing hormone (LH) and estrogen (E₂) levels were significantly increased at post‐vitellogenesis (p < 0.05), while follicle‐stimulating hormone (FSH) levels increased at vitellogenesis (p < 0.05). The FO and FSO groups had significantly higher GnRH and E₂ levels than the other two groups (p < 0.05). In addition, plasma vitellogenin (Vtg) levels significantly increased at vitellogenesis and post‐vitellogenesis (p < 0.05), which were significantly higher in the groups of FO and FSO than SO (p < 0.05). Moreover, the expression levels of hepatic estrogen receptor α (Erα) mRNA were significantly increased at vitellogenesis and post‐vitellogenesis while ovarian Cyp19α1α mRNA were significantly increased at post‐vitellogenesis (p < 0.05), and both were the lowest in SO. Taken together, the replacement of fish oil with 66.7% soybean oil is feasible.     

银鲳卵黄发生期间组织中抗氧化水平的变化及饲料n-3 LC-PUFA对其的影响

研究了银鲳(Papus argenteus)肝及卵巢组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性、总抗氧化能力(T-AOC)及丙二醛(MDA)含量在整个卵黄发生过程中的变化情况,并分析了饲料n-3 LC-PUFA对卵黄发生期间组织中抗氧化水平的影响。分别以100%鱼油(FO组)、70%鱼油和30%大豆油(FSO组)、30%鱼油和70%大豆油(SFO组)、100%大豆油(SO组)为脂肪源,配制了4组等氮、等能及等脂的试验饲料。以1年龄雌性银鲳为试验对象,每组饲料设3重复,试验周期185 d。研究结果表明,肝与卵巢组织SOD、CAT活性、T-AOC水平及MDA含量在卵黄发生过程中均呈现逐渐升高的趋势,且卵黄发生后期各指标水平均显著高于卵黄发生前期(P0.05)。肝SOD(除SO饲料组外)、CAT活性、T-AOC水平及MDA含量在卵黄发生中期与前期之间未表现出显著性差异(P0.05),而卵黄发生中期FO与FSO饲料组卵巢SOD、CAT活性及T-AOC水平则均显著高于卵黄发生前期(P0.05)。FSO饲料组肝与卵巢SOD、CAT活性在卵黄发生过程中均为最高值,且在卵黄发生中、后期均显著高于SO饲料组(P0.05),但与FO饲料组无显著性差异(P0.05)。各饲料组间肝与卵巢T-AOC水平在卵黄发生前期均未表现出显著性差异(P0.05),而在卵黄发生后期,FO与FSO饲料组肝与卵巢T-AOC水平均显著高于SO饲料组(P0.05),但FO与FSO饲料组间无显著性差异(P0.05)。肝与卵巢中MDA含量随着饲料n-3 LC-PUFA含量的升高而呈现出升高趋势,且这种升高趋势在肝组织中表现更为明显,卵巢组织MDA含量在卵黄发生中、后期仅FO饲料组表现出显著性升高趋势(P0.05),其他各饲料组在卵黄发生各期均未表现出显著性差异(P0.05)。统计分析表明,银鲳卵黄发生过程中组织中抗氧化水平逐渐升高,适宜的饲料n-3 LC-PUFA含量(4.01%,FSO饲料组)可明显改善银鲳卵黄发生中期与后期组织中的抗氧化水平。双因素方差分析结果表明,试验饲料与卵黄发生时期对银鲳组织抗氧化水平均具有极显著性影响(P0.01),且两者对肝T-AOC水平与MDA含量存在显著性的交互作用(P0.05)。     

Fatty acid influence on Prochilodus lineatus (Characiformes,Prochilodontidae) embryo cryopreservation parameters.

This study aimed to evaluate the vitellogenic transference and incorporation of long‐chain polyunsaturated fatty acids (LC‐PUFA) into the membranes of Prochilodus lineatus embryos, aiming to increase the permeability to cryoprotectants and resistance to electric fields. One hundred thirty broodstock of P. lineatus were fed with control (C) or fish oil‐supplemented diets (FO) for 12 months. The fatty acid (FA) profle was determined using gas chromatography. For the neutral fraction, the FO group had a decrease in monounsaturated fatty acids (MUFA) and an increase in n3PUFA and, n6PUFA. To test for cryoprotectant toxicity, embryos were exposed for 20 min to a cryoprotectant solution of 1,2‐Propanediol (Prop) at a concentration of 5 or 6 molar (M). For FO, a reduction in survival of 33.1% was observed in 5 M, and no survival was observed at 6 M. Embryo samples were exposed the six polarized electric fields (3.4–51.6 joules), and with 11.2 J of energy, the control group exhibited reduced survival in 98.3% of the fish, whereas the FO presented superior resistance, exhibiting a survival similar to that of the OJ up to 40.2 J. We conclude that FA were transferred between P. lineatus broodstock to the embryos, with an increase in LC‐PUFA resulting in lower survival rates in the cryoprotectant test in the FO group and a greater physical plasticity of FO embryos to electrical field tests.     

n‐3 and n‐6 fatty acid bioconversion abilities in Eurasian perch (Perca fluviatilis) at two developmental stages

The aim of this work was to study the fatty acid (FA) bioconversion ability in Eurasian perch fed with diets differing in their polyunsaturated fatty acids (PUFA) from n‐3 and n‐6 series content at two development stages: adults in exogenous vitellogenesis, and juveniles during the on‐growing phase. Duplicate groups of adults and juveniles were fed for 12 weeks with four diets: D1 and D2, two diets prepared with fish oil partially or totally as the lipid source, and so containing long‐chain PUFA (LC‐PUFA). Those two diets differed by their n‐3/n‐6 FA dietary ratio (0.2 and 7.0, respectively), D1 being characterized by a high n‐6 LC‐PUFA level, while D2 had a high level of n‐3 LC‐PUFA. D3 and D4 were constituted only with vegetable oils, and were therefore devoid of LC‐PUFA. D3 was characterized by a high level of 18:2 n‐6 (n‐6/n‐3 ratio of 0.3), while D4 was characterized by a high level of 18:3 n‐3 (n‐3/n‐6 ratio of 1.9). Both groups of fish were able to elongate and desaturate the 18:3 n‐3 precursor into eicosapentaenoic acid and docosahexaenoic acid, regarding the FA profile of livers. Furthermore, total elongation/desaturation from [1‐¹⁴C]18:3 n‐3 of LC‐PUFA was higher in fish fed with the high dietary 18:3 n‐3 level compared to the diet rich in n‐3 LC‐PUFA. By opposition, the bioconversion of 18:2 n‐6 into LC‐PUFA was limited, regarding the elongation/desaturation activity of LC‐PUFA from [1‐¹⁴C]18:2 n‐6. In view of the great ability for bioconversion of n‐3 FA, linseed oil is a promising alternative to fish oil in formulating feed for juveniles perch as there were no differences in terms of specific growth rate between the treatments, but adults undergoing maturation should have at least partially LC‐PUFA in their diet, particularly arachidonic acid (ARA) which is important during maturation, as breeders are not able to bioconvert 18:2 n‐6 into ARA.     

Effect of dietary lipid source and vitamin E on growth,non‐specific immune response and resistance to Aeromonas hydrophila challenge of Chinese mitten crab Eriocheir sinensis

Six purified diets were formulated to contain three lipid sources, fish oil (FO), linseed oil (LO) and soybean oil (SO), at 6% diet lipid crossing two levels of vitamin E (100 and 300 mg α‐tocopheryl acetate/kg diet) for each lipid source (FO100, FO300, LO100, LO300, SO100, SO300). The juvenile Chinese mitten crab, Eriocheir sinensis, respectively, fed on these diets with four replicates for 6 weeks. The crab weight gain (WG) and specific growth rate (SGR) were significantly affected by dietary lipid sources. No difference was found between the crabs fed two levels of vitamin E, but the WG and SGR were numerically higher in crab fed 300 mg/kg vitamin E than those fed the other level of vitamin E. The lipid source and vitamin E level could affect fatty acid composition in the hepatopancreas. The contents of saturated fatty acids (SAFA) and n‐3HUFA were significantly higher in the crab‐fed fish oil. The highest contents of n‐6PUFA and n‐3PUFA were found in the crab‐fed soybean oil and linseed oil respectively. The contents of SAFA, n‐3HUFA and n‐3PUFA were higher in the 300 mg/kg vitamin E treatment. A lower malondialdehyde (MDA) content and higher phenoloxidase (PO) activity were observed in the crab fed 300 mg/kg vitamin E. The results of this study indicate that the Chinese mitten crab fed the diet with 6% fish oil and 300 mg/kg vitamin E showed better growth, antioxidant capacity and resistance to Aeromonas hydrophila.     

Molecular cloning,characterization and expression analysis of the fatty acid‐binding protein (MnFABP), involved in dietary lipid sources response in oriental river prawn,Macrobrachium nipponense

A fatty acid‐binding protein (FABP) gene designated as MnFABP10 was cloned and characterized from the freshwater prawn Macrobrachium nipponense. The full‐length cDNA of MnFABP10 was 646 bp encoding a 130 amino acid. Real‐time quantitative RT‐PCR showed that the MnFABP10 gene was expressed in various tissues with the highest expression in the hepatopancreas. The MnFABP10 mRNA levels in the hepatopancreas and ovary of M. nipponense were dependent on the stages of ovarian development. Western blot results revealed a single immunoreactive band with an estimated molecular mass of approximate 14 kDa in the developmental ovary. Then, M. nipponense with an initial body weight of 0.090 ± 0.0010 g were fed with four isonitrogenous and isocaloric diets with different oils, that is, beef tallow (BT), soybean oil (SO), pollack fish oil (FO) and a mixture of fish oil and soybean oil (FO/SO 2 : 1 w/w) for 52 days. The mRNA levels of MnFABP10 in the hepatopancreas were influenced by different lipid sources, with a peak expression observed in prawns fed SO. This study suggests that MnFABP10 may have a putative function in ovary maturation, and its mRNA expression in the hepatopancreas can be regulated by the source of dietary lipids in M. nipponense.     

Effects of dietary fish oil replacement by microalgae raw materials on growth performance,body composition and fatty acid profile of juvenile olive flounder,Paralichthys olivaceus

Replacing dietary fish oil with DHA‐rich microalgae Schizochytrium sp. and EPA‐rich microalgae Nannochloropsis sp. for olive flounder (Paralichthys olivaceus) was examined. Three experimental isonitrogenous and isolipidic diets with lipid source provided by 50% fish oil (F50S50), 50% (M50F25S25) and 100% microalgae raw material (M100) respectively were compared with a soybean oil (S100) diet as control. Triplicate groups of olive flounder juveniles (16.5 ± 0.91 g) were fed the experimental diets, and a group was fed the control diets for 8 weeks in a recirculation system. Results showed feed efficiency and growth performance were not significantly changed when fish oil (FO) was totally substituted by soybean oil (SO) or microalgae raw material (MRM). The whole‐body composition, lipid content of liver and muscle, and lipid composition of plasma were not significantly influenced by the total substitution of FO by MRM. The polyunsaturated fatty acids (PUFA) content of muscle and liver declined in fish fed S100 diet, whereas it was not significantly reduced in fish fed M50F25S25 and M100 diets. The total substitution of FO by MRM not only maintained the levels of arachidonic acid, EPA or DHA but also increased n‐3/n‐6 ratio. In conclusion, MRM as the sole lipid source is sufficient to obtain good feed efficiency, growth performance and human health value in olive flounder juveniles.     

Effect of replacing dietary fish oil with soybean oil on growth performance,fatty acid composition and haematological parameters of juvenile meagre,Argyrosomus regius

A nutrition trial with meagre, Argyrosomus regius was assessed to determine the effect of dietary replacement of fish oil (FO) by soybean oil (SO) on the growth, feed utilization, body composition, fatty acid composition and basic haematological parameters. Six isonitrogenous (47% crude protein) and isoenergetic (gross energy 22 kJ/g) experimental diets were formulated by replacing 0 (FO), 20 (S20), 40 (S40), 60 (S60), 80 (S80) and 100 (S100) % of the FO with SO. Fish were fed three times daily to near satiation for 14 weeks. The specific growth rate (SGR) of fish fed S100 diet was significantly lower than the other treatments, except SO80 diet. The fish fed SO100 diet displayed significantly higher feed conversion ratio than that of other diets (P < 0.05). It was observed that fish fed the SO100 and SO80 diets displayed haemoglobin (HGB) levels significantly lower (P < 0.05) than fish fed the SO20 diet. Packed cell volume (PCV) of fish fed SO20 diet was significantly higher compared to SO100. The white blood cell (WBC) and red blood cell (RBC) remained unaffected by dietary treatment. The docosahexaenoic acid (22:6n‐3, DHA) and eicosapentaenoic acid (20:5n‐3, EPA) levels of meagre were significantly reduced by the substituting of dietary SO by FO at the end of the feeding period. The level of linoleic acid (18:2n‐6, LA) and linolenic acid (18:3n‐3, LNA) significantly raised in fish fed with SO diets (P < 0.05). The results of this study showed that SO could be replaced FO up to 80% in meagre diet without negative effect on growth performance and basic haematological parameters. Furthermore, the maximum level of FO replacement with SO determined by second order polynomial regression analysis, was 30.1% on the basis of maximum SGR.     

饲料中大豆油替代鱼油对银鲳(Pampus argenteus)幼鱼血清溶菌酶活性及组织抗氧化能力的影响

银鲳(Pampus argenteus)是沿海重要的经济鱼类,本研究针对养殖银鲳幼鱼进行人工配合饲料研发,降低饲料成本、增强鱼体体质、提高存活率等.通过配制以100％鱼油(FO)、70％鱼油和30％大豆油(FSO)、30％鱼油和70％大豆油(SFO)、100％大豆油(SO)为脂肪源的4组饲料,检测银鲳幼鱼血清溶菌酶(LZM)和组织抗氧化性能的变化情况,以探究饲料大豆油替代鱼油对银鲳幼鱼健康的影响.结果显示,SFO组血清LZM水平最高,SO组最低,但各组间差异不显著(P＞0.05).FSO和SFO组的肌肉丙二醛(MDA)含量显著高于FO和SO组(P＜0.05),肝脏MDA含量则是FO和FSO组较高(P＜0.05).血清和肌肉超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活力最高的均为SFO组,而SO组活力较低.相对地,肝脏SOD和CAT活力均是FO组最高(P＜0.05).肌肉和肝脏总抗氧化能力(T-AOC)均是FO和FSO组较高,而血清T-AOC是SO组较高.研究表明,豆油替代30％和70％鱼油,对银鲳幼鱼免疫和抗氧化能力都略有促进作用,但完全使用豆油会对机体产生负面影响.     

The effect of soybean oil containing stearidonic acid on growth performance,n‐3 fatty acid deposition and sensory characteristics of pacific white shrimp (Litopenaeus vannamei)

The ability of shrimp Litopenaeus vannamei to utilize soy oil (SO) modified to contain stearidonic acid (SDA) in replacement of fish oil (FO) by converting SDA to highly unsaturated fatty acids (HUFA) was examined. Six diets with either supplemental modified SO or FO and three levels of fishmeal (FM) replacement (0%, 50% and 100%) by soybean meal (SBM) were fed to shrimp (1.7 g) for 12 weeks. The effect of oil source at the three SBM levels on growth and fatty acid profiles was examined by contrast analysis and sensory attributes by t‐tests (5% error rate). At 0% SBM inclusion, there was no effect of dietary oil source, while at the highest SBM inclusion level, shrimp fed the FO diet outperformed those fed the corresponding SO diet. Oil source had no effect on sensory attributes. The fatty acid profiles of the shrimp reflected that of the diets. SDA SO can replace supplemental FO in diets for shrimp with no reduction in growth when there is sufficient oil present from FM. At low FM, however, replacing FO with SDA SO reduces shrimp performance and tissue n‐3 HUFA levels. It is concluded that SDA is unable to meet the essential fatty acid needs of shrimp.     

Net production of Atlantic salmon (FIFO,Fish in Fish out < 1) with dietary plant proteins and vegetable oils

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

Partial replacement of fish oil with terrestrial lipid blend and effects on growth performance,body composition,immune parameter and growth‐related genes in yellow drum (Nibea albiflora)

The imbalance of fish oil (FO) supply and demand has motivated efforts to identify an alternative for aqua feed. An 8‐week feeding trial was conducted to evaluate the effects of dietary fish oil partial replacement with mixed oil from linseed and lard (1:1) on growth, body composition and immunity when the N3 long‐chain polyunsaturated fatty acid (N3 LC‐PUFAs) requirement is met for Nibea albiflora. Two types of experimental diets were formulated with 100% fish oil (FO) or 69% mixed oil (Mix). The results indicated that the Mix diet significantly improved the specific growth rate (SGR), weight gain (WG), feed efficiency ratio (FER), muscle tissue growth hormone receptor (GHR), insulin‐like growth factor 1 (IGF1) and insulin‐like growth factor 1 receptor (IGF1R) gene expression of the yellow drum (p < .05). No significant difference in the survival rate (SR), feed intake (FI), hepatosomatic index (HSI), viscerosomatic index (VSI), condition factor (CF), N3 PUFA percentage, liver antioxidant enzyme activities or pro‐inflammatory gene expression was observed between the two treatments. Therefore, terrestrial blend lipid from linseed and lard could be used as an alternative for dietary fish oil without compromising growth performance and immunity for the juvenile yellow drum.     

Fish oil–based finishing diets strongly increase long‐chain polyunsaturated fatty acid concentrations in farm‐raised common carp (Cyprinus carpio L.)

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

Effects of replacement of dietary fish oil with soybean oil on growth performance and tissue fatty acid composition in marine herbivorous teleost Siganus canaliculatus

Fish oil (FO) substitution has been studied in many marine carnivorous fish, but seldom in marine herbivorous or omnivorous species. To evaluate the feasibility of using soybean oil (SO) as a dietary lipid and confirm its capability of converting C₁₈ polyunsaturated fatty acid (PUFA) into long chain polyunsaturated fatty acid (LC‐PUFA) in the marine herbivorous teleost Siganus canaliculatus, juvenile fish were fed with four formulated diets differing in lipid composition, with SO accounting for 0.76% (SO0), 23% (SO23), 45% (SO45) and 67% (SO67) of total dietary lipid respectively. After feeding for 8 weeks, growth performance including weight gain, specific growth rate, feed conversion ratio and protein efficiency rate were better in the SO23 and, especially, SO45 groups than in the SO0 and SO67 groups (P < 0.05). Tissue fatty acid compositions were affected by diet, with the liver contents of eicosapentaenoic (EPA), docosapentaenoic (DPA), docosahexaenoic (DHA) acids and total n‐3 PUFA displaying parallel changes with the corresponding dietary fatty acids. While the muscle contents of EPA, DPA and total n‐3 PUFA between SO0 and SO23 groups, and the liver contents of arachidonic acid (ARA) and 20:4n‐3, as well as the muscle content of 20:3n‐6 between SO0 and SO45 groups showed no difference, confirming the biosynthesis of LC‐PUFA from C₁₈ precursors in vivo as the contents of corresponding fatty acids in diets SO23/SO45 were much lower than those in diet SO0 (P < 0.05). The results indicate that SO may be a suitable dietary lipid source for S. canaliculatus, and can replace up to 67% or 45% of total dietary FO without negatively compromising growth performance or nutritional quality of fish respectively. Moreover, the study increases our knowledge of FO substitution in marine herbivorous fish.     

Diet,size and location as determinants of n‐3 long‐chain polyunsaturated fatty acid content in farmed Atlantic Salmon (Salmo salar)

We explored how currently manufactured feeds, under real‐world conditions and across geographically distinct locations, promoted flesh n‐3 long‐chain polyunsaturated fatty acid (LC‐PUFA, i.e. 20:5n‐3 + 22:6n‐3) levels in various life stages of farmed Atlantic Salmon (Salmo salar). Potential effects on flesh LC‐PUFA included: (1) diet and fish weight at one Canadian east coast farm, (2) diet and farm location across six east coast farms, and (3) diet and farm location between east and west coast farms. For objectives 1 and 2, salmon were fed a currently manufactured feed (labelled as feeds A, B or C) and harvested at 1, 3 and 5 kg. LC‐PUFA levels in 5 kg (harvest size) fish were then compared to previously published values for west coast farmed Atlantic Salmon (Obj. 3). Combined results revealed that variability in LC‐PUFA levels was better explained by diet than by fish weight or farm location. Fish size, however, was also important for two reasons. First, feeding a high LC‐PUFA diet early in life appeared important for ensuring high LC‐PUFA levels at harvest size. Second, salmon flesh LC‐PUFA levels increased with fish size, but only when dietary LC‐PUFA was provided above an apparent threshold value (~3000 mg per 100 g or 10% of total fatty acids) that likely promoted LC‐PUFA incorporation and storage. Overall, our comparison makes new recommendations for feed manufacturers and demonstrates that farmed Atlantic Salmon reared under real‐world conditions on currently available salmon feeds were good sources of n‐3 LC‐PUFA to consumers.     

Dietary profile of n‐3 series LC‐PUFAs in rainbow trout under regular stripping condition: Semen production and quality,hepato‐somatic index,haemato‐immunologic values,oxidative stress and fatty acid composition of liver,muscle and semen

In this study, the semen production and quality, hepato‐somatic index, haemato‐immunologic values, oxidative stress and the fatty acid contents in liver, muscle and semen of rainbow trout fed diets supplemented n‐3 series long‐chain polyunsaturated fatty acids (LC‐PUFAs) under regular stripping condition were investigated. For this aim, three diets (Control, D1 and D2) were prepared. These diets were contained n‐3 LC‐PUFAs (as a percentage of dietary total fatty acid) at 3.14%, 7.84% and 13.63% respectively. Experimental fish were fed with the control and test diets. The highest hepato‐somatic index, spermatologic (semen pH and volume, sperm motility and density), haematologic (haematocrit value, haemoglobin, erythrocyte count, corpuscular volume, haemoglobin and its concentration in corpuscular), immunologic (nitroblue tetrazolium activity, leucocyte count, phagocytic index, protein and immunoglobulin [IgM] in total plasma) and antioxidants (reduced glutathione, catalase, glutathione peroxidase and superoxide dismutase) values were found in fish fed the D2, D1 and control diets respectively (p < 0.01). Increase in the dietary n‐3 LC‐PUFAs was not significantly (p > 0.01) increased the oxidative stress (malondialdehyde) in fish. The results indicated that the n‐3 LC‐PUFAs at 13.63% level of total fatty acid in the diet could increase the semen production and quality, hepato‐somatic index, haematologic and immunologic values, and the n‐3 LC‐PUFA contents in liver, muscle and semen of rainbow trout broodstock under regular stripping condition.     

Replacement of Fish Oil with Linseed Oil or Soybean Oil in Feeds for Japanese Seabass,Lateolabrax japonicus: Effects on Growth Performance,Immune Response,and Tissue Fatty Acid Composition

A 66‐d feeding experiment was conducted to investigate the utilization of vegetable oils in Japanese seabass (initial weight: 10.09 ± 0.70 g). In experimental diets, linseed oil (LO) or soybean oil (SO) was used to replace 1/3, 2/3, and 3/3 of fish oil (FO) (Diets F₂L₁, F₁L₂, and LO, respectively, or Diets F₂S₁, F₁S₂, and SO, respectively). A diet with FO alone was used as the control diet. LO or SO supplementation did not reduce the specific growth rate (3.06–3.29%/d) and feed efficiency ratio (0.75–0.83) of fish, but group F₂L₁ showed significantly better growth (P < 0.05) and feed utilization (P < 0.01) than group SO. Total replacement of FO with LO or SO significantly reduced certain non‐specific innate immune responses. Total replacement of FO by LO significantly increased the lipid content of fish. Concentrations of long‐chain polyunsaturated fatty acids (LC‐PUFAs) in whole fish and tissues were significantly reduced by LO or SO supplementation. In conclusion, LO or SO supplementations did not reduce the growth of Japanese seabass but reduced the immune responses and LC‐PUFA concentrations. LO was a better lipid source than SO for Japanese seabass in terms of fish growth and immune responses.     

The influence of dietary fish oil replacement with mixture of vegetable oils on reproductive performance,immune responses and dynamic of fatty acids during embryogenesis in Oncorhynchus mykiss

A 90‐day feeding trial was carried out to examine the influence of fish oil (FO) substitution with blends of vegetable oils (VOs) on reproductive efficiency of female brooders and fluctuation in fatty acid (FA) profile of embryos in Oncorhynchus mykiss. A basal diet was formulated in which 20% (80FO/20VO), 50% (50FO/50VO), 75% (25FO/75VO) and 100% (100VO) of FO were replaced by mixture of VO. Reproductive performance of brooders was not affected by drastic alternations in FA profile of diets. The level of saturated and monounsaturated FAs (MUFAs) significantly increased, whereas the levels of long‐chain polyunsaturated FAs (LC‐PUFAs), mainly docosahexaenoic acid, profoundly decreased during embryogenesis. The concentrations of MUFA and n?6 PUFA increased in the eggs with increasing the incorporation of VO mixture in diets; however, the concentration of LC‐PUFA and n?3/n?6 PUFA ratio decreased. Haematological parameters and humoral immune responses including total immunoglobulin content, lysozyme and alternative complement pathway activities in brooders fed with the experimental diets did not statically different. In summary, incorporating mixture of various VO sources especially linseed and sunflower oils as good sources of α‐linolenic and linoleic acids, respectively, along with low levels of residual fat from fish meal in diet suggested a good strategy for providing the appropriate essential FA requirements of O. mykiss brooders for their successful reproduction.