Levels Of Fish Oil Research Articles

Effects of Oxidized Fish Oil on the Growth, Immune and Antioxidant Capacity, Inflammation-Related Gene Expression, and Intestinal Microbiota Composition of Juvenile Sea Urchin (Strongylocentrotus intermedius)

A 60 d feeding experiment was conducted to investigate the effects of oxidized fish oil (OF) on survival, growth, immune and antioxidant capacity, inflammation-related gene expression, and intestinal microbiota of juvenile sea urchin (Strongylocentrotus intermedius). Six feeds were formulated by including equal amounts of fish oil with different oxidation levels (0, 50, 100, 150, 200, and 300 meq/kg). The feed OF0 and fresh kelp (Laminaria japonica) were used as the control groups. Results showed that the weight gain rate (WGR) of sea urchins significantly decreased as the oxidation level increased. When the oxidation level of fish oil was equal to or above 150 meq/kg, the WGR of sea urchins was significantly lower than those fed the control diets. The activities of digestive enzymes (pepsin and amylase), immune enzymes (alkaline phosphatase and acid phosphatase), and antioxidant enzymes (superoxide dismutase, catalase, and glutathione S-transferase) first decreased significantly as the oxidation level increased to 150 or 200 meq/kg and then bounced to values comparable to or even higher than those in the control feed group, while the transcription of immune, antioxidation, and inflammation-related genes was upregulated by the increasing oxidation level of fish oil. Oxidized fish oil decreased the intestinal microbial diversity and the relative abundance of Firmicutes. Vibrio was the dominant genus of microbiota in the intestine of sea urchins fed almost all formulated feeds (except for OF150), with its abundance above 20%. Comparably, the abundance of Vibrio in the intestine of sea urchins fed fresh kelp was only 2.32%. These results showed that oxidized fish oil had negative effects on the growth, immune response and antioxidant capacity, and bacterial diversity of juvenile S. intermedius. The abnormal increase of antioxidant enzyme activities and malondialdehyde contents at relatively higher oxidation level (>150 meq/kg) could be due to the oxidative stress occurrence inside the body of sea urchins. Sea urchins fed formulated feeds host more Vibrio than those fed fresh kelp, and this could be a potential incidence of disease occurrence.

Improved long-chain omega-3 polyunsaturated fatty acids in sago palm weevil (Rhynchophorus ferrugineus) larvae by dietary fish oil supplementation

The nutritional values of sago palm weevil larvae (SPWL) reared on mixed plant-based diets (ground sago palm trunk (GS), cornmeal, rice bran, soybean, and perilla seed), containing different levels of dietary fish oil (FO) were compared to those reared on commercial pig feed (PF) and GS. Increased FO content resulted in an increase in ω-3 fatty acids (FA) in SPWL (p < 0.05), especially α-linolenic acid and eicosapentaenoic acid. When fed FO-fortified diets instead of PF, the health-promoting indices of the SPWL lipid improved significantly (e.g., decreased ω-6/ω-3 ratio, thrombogenicity index, and hypercholesterolemic FA with increased PUFA content). The lipid, protein, and mineral contents of SPWL were increased while growth performance was maintained on a 1.5% FO-fortified diet. Higher FO levels (3–5%) had a negative impact on the nutritional values and growth performance of the SPWL. Thus, there was a reasonable chance of developing a high-nutrient alternative insect for human consumption.

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.

Effects of different dietary canola and fish oil levels on overall performance, fatty acid profile, haemato‐biochemical responses, and digestibility of macronutrients of Caspian brown trout ( Salmo trutta caspius Kessler) fingerling

A 2-month feeding trial was undertaken to evaluate the effects of replacing dietary fish oil (FO) with canola oil (CO) at four levels of HF (100% fish oil), FF (70% fish oil + 30% canola oil), FV (50% fish oil + 50% canola oil), and HV (100% canola oil) on overall performance, haemato-biochemical responses, fatty acid composition and digestibility of Caspian brown trout, Salmo trutta caspius (Kessler) fingerlings. Fingerlings (N = 180, 4.6 ± 0.23 g) were randomly scattered to four various diet treatments. In fingerlings fed with FV diet a considerable increase in specific growth rate and weight gain were recorded (p < .05). No significant difference was observed in none of the macronutrients of the whole-body among the treatments (p > .05). The highest saturated fatty acids and the lowest monounsaturated fatty acids were recognized in the HF diet (p < .05). The lowest red blood cell was found in fingerlings fed HF diet (p < .05), but the white blood cell activity was not influenced in the groups (p > .05). The fingerlings that consumed the HF diet implied the highest aspartate transaminase, alanine transaminase, alkaline phosphatase and lactate dehydrogenase activities in serum than the other groups (p < .05). None of the whole-body compositions such as protein, lipid, ash, and moisture were affected by dietary treatments (p > .05). The lowest value of apparent digestibility of crude lipid (ADCCL) was observed in the HF group (p > .05). Overall, the data exhibited that elevating dietary canola oil up to 50% in Caspian brown trout fingerling resulted to improve growth efficiency and blood biochemistry.

Effects of fish oil substitution by hazelnut oil on growth performance, whole‐body fatty acid composition and enzymes of intermediary metabolism of juvenile meagre ( Argyrosomus regius Asso, 1801)

The need for new alternative oil sources in the ever-increasing aquaculture of carnivorous species is imperative. We substituted fish oil (FO) with hazelnut oil (HO) in meagre diet at 20, 40, 60, 80 and 100%. Triplicate groups of 40 fish/tank juvenile meagre (ca 15 g) were used. For the reduction of FO level in meagre diet, a 40% substitution by HO is attainable without affecting growth performance. However, higher substitutions appear to have a negative effect on growth performance and feed efficiency, although daily feed intake seems to remain unaffected by the reduction in FO. No effects on whole-body protein and lipid concentration were observed for fish fed the experimental diets. Whole-body fatty acid composition reflected the dietary fatty acid composition in all dietary groups. Diets with higher than 40% levels of FO substitution significantly reduce highly unsaturated ω-3 fatty acids in the fish. Although the metabolic relationship between carbohydrate and fatty acid exploitation is extremely versatile, and thus it is difficult to reach a safe conclusion, it seems that FO substitution by HO activates fish carbohydrate, rather than fatty acids, exploitation machinery. These results support the use of HO in meagre diets up to 40% FO substitution with a future thought for more efficient use of 30% FO substitution by HO.

Influence of Varying Dietary ω6 to ω3 Fatty Acid Ratios on the Hepatic Transcriptome, and Association with Phenotypic Traits (Growth, Somatic Indices, and Tissue Lipid Composition), in Atlantic Salmon (Salmo salar).

Simple SummaryPlant oils are routinely used in fish feeds as a fish oil replacement. However, these terrestrial alternatives typically contain high levels of ω6 fatty acids (FA) and, thus, high ω6 to ω3 (ω6:ω3) FA ratios, which influence farmed fish and their consumers. The ω6:ω3 ratio is known to affect many biological processes (e.g., inflammation, FA metabolism) and human diseases; however, its impacts on fish physiology and the underlying molecular mechanisms are less well understood. In this study, we used 44 K microarrays to examine which genes and molecular pathways are altered by variation in dietary ω6:ω3 in Atlantic salmon. Our microarray study showed that several genes related to immune response, lipid metabolism, cell proliferation, and translation were differentially expressed between the two extreme ω6:ω3 dietary treatments. We also revealed that the PPARα activation-related transcript helz2 is a potential novel molecular biomarker of tissue variation in ω6:ω3. Further, correlation analyses illustrated the relationships between liver transcript expression and tissue (liver, muscle) lipid composition, and other phenotypic traits in salmon fed low levels of fish oil. This nutrigenomic study enhanced the current understanding of Atlantic salmon gene expression response to varying dietary ω6:ω3.The importance of dietary omega-6 to omega-3 (ω6:ω3) fatty acid (FA) ratios for human health has been extensively examined. However, its impact on fish physiology, and the underlying molecular mechanisms, are less well understood. This study investigated the influence of plant-based diets (12-week exposure) with varying ω6:ω3 (0.4–2.7) on the hepatic transcriptome of Atlantic salmon. Using 44 K microarray analysis, genes involved in immune and inflammatory response (lect2a, itgb5, helz2a, p43), lipid metabolism (helz2a), cell proliferation (htra1b), control of muscle and neuronal development (mef2d) and translation (eif2a, eif4b1, p43) were identified; these were differentially expressed between the two extreme ω6:ω3 dietary treatments (high ω6 vs. high ω3) at week 12. Eight out of 10 microarray-identified transcripts showed an agreement in the direction of expression fold-change between the microarray and qPCR studies. The PPARα activation-related transcript helz2a was confirmed by qPCR to be down-regulated by high ω6 diet compared with high ω3 diet. The transcript expression of two helz2 paralogues was positively correlated with ω3, and negatively with ω6 FA in both liver and muscle, thus indicating their potential as biomarkers of tissue ω6:ω3 variation. Mef2d expression in liver was suppressed in the high ω6 compared to the balanced diet (ω6:ω3 of 2.7 and 0.9, respectively) fed fish, and showed negative correlations with ω6:ω3 in both tissues. The hepatic expression of two lect2 paralogues was negatively correlated with viscerosomatic index, while htra1b correlated negatively with salmon weight gain and condition factor. Finally, p43 and eif2a were positively correlated with liver Σω3, while these transcripts and eif4b2 showed negative correlations with 18:2ω6 in the liver. This suggested that some aspects of protein synthesis were influenced by dietary ω6:ω3. In summary, this nutrigenomic study identified hepatic transcripts responsive to dietary variation in ω6:ω3, and relationships of transcript expression with tissue (liver, muscle) lipid composition and other phenotypic traits.

Improvement of Omega-3 in Lemuru (Sardinella sp) Fish Oil by Using Enzymatic Reaction

This study aims to scale-up the production of the omega-3 enrichment generated from Lemuru fish oil using a 1 L reactor without experimental design through enzymatic reactions that might have increased the economic value of lemuru fish oil. The enrichment of omega 3 fish oil was carried using a 1 L reactor through hydrolysis with commercial lipase enzymes’ help. Enzymatic reactions were carried out with variations in temperature (40,45,50 and 55°C), time of reaction (0, 6, 12, 18, 24, 30, and 36 hours), the enzyme concentration of 1000 units, and agitation (50, 100, and 150 rpm). The fatty acid content of fish oil before and after the enzymatic reaction was analyzed using GC-MS. At the same time, the omega-3 fatty acid content of fish oil that had been hydrolyzed with lipase was determined using Gas Chromatography (GC). The results show that the optimum conditions for enzymatic reactions were 24 hours reaction time, 50°C temperature, and 150 rpm agitation. Enzymatic reactions using commercial lipases can increase the omega-3 levels of Lemuru fish oil consisting of the content of ALA, EPA, and DHA, 10, 18, and 35-fold, respectively.

Interactive effect of dietary fish oil and pyrimidine nucleotide supplementation on the fatty acid composition of juvenile rainbow trout Oncorhynchus mykiss : Enhancement of ARA and DHA contents in the fillet of fish fed‐supplemented diet

The present study investigated interactive effect of different levels of dietary fish oil and pyrimidine nucleotide supplementation on growth and fatty acid composition of juvenile rainbow trout. Six experimental diets were formulated with two different levels of fish oil. High fish oil (HFO) diet contains 120 g/kg fish oil, while low fish oil (LFO) diet contains 40, 60 and 20 g/kg fish, linseed and rapeseed oils respectively. Uridine 5’-monophosphate (UMP) or cytidine 5’-monophosphate (CMP) disodium salt was supplemented onto each diet at 1.5 g/kg respectively. For control diet, UMP and CMP were not supplemented to HFO and LFO diets respectively (HFO-Cont. and LFO-Cont.). Rainbow trout with initial average body weight of 13.5 g were randomly placed into 12 tanks and offered one of the six diets for 12 weeks. Growth, feed utilization and hepatosomatic index (HSI) of fish were not influenced by either fish oil or pyrimidine nucleotide supplementation. This trend was also similar on the crude lipid content in the liver and proximate composition in the muscle and whole fish body. In addition, fatty acid composition in the liver was influenced by fish oil level, but not by pyrimidine nucleotide supplementation. Interestingly, pyrimidine nucleotide supplementation affected 20:4n-6 and 22:6n-3 contents in the muscle of fish. In summary, although dietary UMP and CMP have no positive effect on growth, it affected on the fatty acid composition of fish by increasing muscular 20:4n-6 and 22:6n-3 contents particularly when it is supplemented in low fish oil-based diet.

Changes in carcass traits, meat quality, muscle fiber characteristics, and liver function of finishing pigs fed high level of fish oil

The study was aimed to investigate the changes in carcass traits, meat quality, muscle fiber characteristics, and liver function in pigs fed with high levels of fresh fish oil and oxidized fish oil. About 30 piglets were randomly assigned to receive basal diet plus 2% fish oil (LFO), basal diet plus 8% fish oil (HFO), or basal diet plus 8% oxidized fish oil (OFO) for 120 d. Pigs of the HFO and OFO group showed reduced carcass weight, dressing percentage, loin eye area, and increased yellowness of the longissimus dorsi muscle compared with LFO group (P &lt; 0.05). Dietary HFO and OFO suppressed the relative expression levels of myosin heavy chain (MyHC) isoform (I and II a), glutathione peroxidase 4, and NAD(P)H: quinone oxidoreductase-1 and mitochondrial biogenesis in longissimus dorsi muscle (P &lt; 0.05). Dietary HFO or OFO increased the serum aspartates aminotransferase, alanine aminotransferase, total bilirubin, direct bilirubin, oxidized low-density lipoprotein, liver index, and concentration of malondialdehyde (MDA) in liver (P &lt; 0.05). In conclusion, high levels of fresh fish oil and oxidized fish oil have adverse effects on carcass traits, muscle fiber characteristics, and liver function, which may be partly due to the mitochondrial dysfunction and impaired antioxidative capacity.

EFEK PENAMBAHAN EKSTRAK KAYU SECANG (Caesalpinia sappan L.) DAN MINYAK IKAN LEMURU DALAM RANSUM PAKAN TERHADAP HEN DAY PRODUCTION, KONVERSI PAKAN, DAN MORTALITAS PUYUH PETELUR

The purpose of this study was to evaluate the effect of giving levels of secang wood extract and lemuru fish oil on the appearance of laying quails which included feed consumption, Hen Day Production (HDP), feed conversion of quail egg mortality. This study used Autumn strain quail with a population of 168 individuals with basal feed supplemented with several levels of secang wood extract. This research method is an experiment using a completely randomized design (CRD) factorial with 4 treatments with 6 replications with each repetition consisting of 7 quails aged 10-15 weeks. The treatment was as follows: P0 = basal feed without the addition of secang wood extract P1 = basal feed + 0.2% EKS + 4% MIL, P2 = basal feed + 0.4% EKS + 4% MIL, P3 = basal feed + 0 , 6% EX + 4% MIL. The addition of a combination of secang wood extract and fish oil was carried out according to the level of quail feeding. The variable being measured; feed consumption, Hen Day Production (HDP), Feed conversion, mortality. Addition of secang wood extract with a level of 0%; 0.2%; 0.4%; 0.6%, and 4% lemuru fish oil had no significant effect on feed consumption, hen day production, feed conversion, mortality, this was due to flavonoids, polyphenols and active compounds in oil. lemuru fish does not affect the appearance of quail egg production. Flavonoid compounds in low concentrations have no effect on chicken feed consumption, because the content of flavonoid compounds can still be tolerated by the chicken body. The use of lemuru fish oil with a concentration of up to 6% in quails does not affect the consumption of quail feed, because the addition of lemuru fish oil does not affect the palatability of quail feed. The conclusion of this study was that the addition of secang wood extract. The addition of secang wood extract and lemuru fish oil did not affect hen day production, feed conversion and mortality of laying quails

Better fatty acids profile in fillets of Nile Tilapia (Oreochromis niloticus) supplemented with fish oil

Fish oil is used as a supplement in animal feed and is recognized for its positive effects on human health. This work evaluated the fatty acid composition and the nutritional quality of the lipid fraction of Nile tilapia fillets (Oreochromis niloticus) that were supplemented with different levels of fish oil (0% (control group), 5%, 10%, or 15% diet in addition to the ether extract of the commercial formulation) for 30 and 60 days pre-slaughter. The effective treatments were 4.61, 9.22, and 13.83% ether extract based on dry matter, respectively. The influence of hyperlipidic diets on the biometric indexes, the variables of weight and body income analyzed was not verified. The effects of oil level and treatment duration were determined by contrast analysis. Thirty-three fatty acids were identified in fillet, with a predominance of oleic (C18:1n-9), palmitic (C16:0), linoleic (C18:2n-6), and stearic (C18:0) acids. Experimental diets significantly influenced the content of fatty acids, particularly eicosapentaenoic acid (C20:5n-3), docosahexaenoic acid (C22:6n-3) and n-3 docosapentaenoic acid (C22:5n-3). Fish oil supplementation showed lower n-6/n-3 ratios and higher polyunsaturated fatty acids/saturated fatty acids ratios compared with the control, contributing to a reduction in thrombogenic index in the sampled fillets. The experimental diets had no effect on the atherogenic index. Comparison of the duration of treatments (30 days vs. 60 days) demonstrated that the total n-6 fatty acids, n-6/n-3 ratio, and contents of docosapentaenoic acid (C22:5n-6) in fillet decreased with extension of the supplementation time. We conclude that fish oil added to tilapia feed nutritionally enriches the fish fillets and it is a good option for commercial production.

Minimizing marine ingredients in diets of farmed Atlantic salmon (Salmo salar): effects on liver and head kidney lipid class and fatty acid composition.

Limited fish meal and fish oil supplies have necessitated research on alternatives for aquafeeds. Seven dietary treatments with different protein and lipid sources were formulated for farmed Atlantic salmon, and their effects on liver and head kidney lipid class, fatty acid, and elemental composition were studied. Fish meal, fish oil, and EPA + DHA content ranged from 5-35%, 0-12%, and 0.1-3%, respectively. Elemental analysis showed that the C to N ratio was higher in the head kidney than in the liver, which is consistent with higher content of total lipids in the head kidney compared with the liver. There was a greater susceptibility to dietary lipid alterations in the liver compared with the head kidney despite liver having a greater proportion of phospholipid and a much lower proportion of triacylglycerol. So long as fish oil levels were 5% or more of the diet, arachidonic acid (ARA) and docosahexaenoic acid (DHA) proportions were the same for each tissue as with feeding the marine diet with 12% fish oil; however, livers and head kidneys from fish fed the lowest amount of fish meal and fish oil had the lowest levels of eicosapentaenoic (EPA) and DHA and the highest ARA levels. Removal of fish oil and reduction of fish meal to 5% in diets of farmed Atlantic salmon affected elemental and lipid compositions of the liver and head kidney tissues potentially increasing susceptibility to inflammation. However, with 10% of the diet comprising fish meal and fish oil, lipid contents were comparable with fish fed marine-based diets.

Effect of High Dietary Level (8%) of Fish Oil on Long-Chain Polyunsaturated Fatty Acid n-3 Content in Pig Tissues and Plasma Biochemical Parameters.

Simple SummaryFish oil is a source of “healthy” polyunsaturated fatty acids that decrease the risk of cardiovascular and other chronic diseases in humans. One possible way to increase consumption of these fatty acids is to incorporate them into pork via pig-feed. We enriched the pigs’ diet with 8% fish oil and found a several-times higher content of the above-mentioned fatty acids in the pig meat in comparison with controls. The meat of the fish oil-fed pigs was also more tender. We also used the same pigs as a model for testing the effects of the high level of dietary fish oil on selected markers of their state of health and detected an increased level of plasma lipids (risk factor for cardiovascular diseases) and a possible overreaction of the immune system. In conclusion, we can recommend consumption of polyunsaturated fatty acids-enriched “functional” pork, but direct human consumption of fish oil should be limited and in accordance with the recommendation of a moderate intake.There were two objectives of the present study using dietary fish oil (FO) in pigs: to use pigs as a model for studying the effects of high FO doses on selected physiological markers; and to evaluate the physical traits and nutritive value of pork enriched with long-chain polyunsaturated fatty acids n-3. Two groups of six female pigs were fed for 30 days with either a standard feed mixture (control, C) or the same mixture supplemented with 8% FO (F). Physical characteristics of the muscle, fatty acid deposition in tissues and selected hematologic and plasma markers were tested. The daily weight gain of the F-pigs was lower in comparison with controls (p < 0.05). Dietary fish oil decreased Warner-Bratzler shear force of the longissimus muscle (p < 0.01). The eicosapentaenoic and docosahexaenoic acid content was higher (p < 0.05) in all tested F-tissues. Dietary fish oil had no effect on plasma cholesterol (p < 0.05), but it increased plasma triacylglycerol levels by 260% (p < 0.05), and increased counts of leukocytes, neutrophils, and eosinophils in the blood plasma (p < 0.05). In conclusion, high dietary FO improved the texture and nutritive value of meat, but negatively affected plasma biochemical parameters.

The Relationship between the Expression of Fatty Acyl Desaturase 2 (fads2) Gene in Peripheral Blood Cells (PBCs) and Liver in Gilthead Seabream, Sparus aurata Broodstock Fed a Low n-3 LC-PUFA Diet.

The principle aim of this study is to elucidate the relationship between the fatty acid desaturase 2 gene (fads2) expression pattern in peripheral blood cells (PBCs) and liver of gilthead seabream (GSB), Sparus aurata broodstock in order to determine the possible use of fads2 expression as a potential biomarker for the selection of broodstock. This selection could be utilized for breeding programs aiming to improve reproduction, health, and nutritional status. Passive Integrated Transponder (PIT)-tagged GSB broodstock (Male-1.22 ± 0.20 kg; 44.8 ± 2 cm and female-2.36 ± 0.64 kg; 55.1 cm) were fed a diet containing low levels of fish meal and fish oil (EPA 2.5; DHA 1.7 and n-3 LC-PUFA 4.6% TFA) for one month. After the feeding period, fads2 expression in PBCs and liver of both male and female broodstock were highly significantly correlated (r = 0.89; p < 0.001). Additionally, in male broodstock, liver fads2 expression was significantly correlated (p < 0.05) to liver contents in 16:0 (r = 0.95; p = 0.04) and total saturates (r = 0.97; p = 0.03) as well as to 20:3n–6/20:2n–6 (r = 0.98; p = 0.02) a Fads2 product/precursor ratio. Overall, we found a positive and significant correlation between fads2 expression levels in the PBCs and liver of GSB broodstock. PBCs fads2 expression levels indicate a strong potential for utilization as a non-invasive method to select animals having increased fatty acid bioconversion capability, better able to deal with diets free of fish meal and fish oil.

Replacement of fish oil by soybean oil and microalgal meals in diets for Totoaba macdonaldi (Gilbert, 1890) juveniles

The objective of this study was to evaluate the use of soybean oil (SO) and two microalgal meals derived from Schizochytrium limacinum (SL1 and SL2) to replace fish oil (FO) in diets for Totoaba macdonaldi juveniles. Nine isoproteic (54% crude protein, CP) and isolipidic (14% crude fat, CF) diets were formulated based on a 3 × 3 factorial design, using the three lipid sources and three replacement levels, 33%, 66% and 100%. A control diet containing FO as the main lipid source served as a reference. Diets were fed for 6 weeks and were randomly assigned to six replicate tanks of a recirculating aquaculture system, with 25 fish stocked per tank. Initial mean fish weight was 8.08 g; at the end of the trial, statistical differences for growth responses such as weight gain (WG; P = 0.0069) and thermal growth coefficient (TGC; P = 0.0027) were detected. WG (SL1 = 50.75 g, SL2 = 51.43 g) and TGC (0.148) of fish fed the S. limacinum meals were significantly higher than in those fed SO (WG = 41.13 g; TGC = 0.129). Conversely, the hepatosomatic index (HSI; P = 0.0009) of fish fed SO was significantly higher (1.38%) compared to those fed the microalgae meals (SL1 = 1.13%, SL2 = 1.22%). Also, proximate composition of liver was significantly influenced by the lipid source and CF was significantly higher (P = 0.0067) in fish fed SO (47.68%) than in fish fed SL1 (37.44%) or SL2 (39.86%). The fatty acid (FA) profile of muscle and liver reflected the dietary FA composition; SO prompted increased concentrations of 18:2n-6 and total n-6 FA in fish fillet; whereas, the S. limacinum meals increased 22:6n-3, total n-3 FA and the n-3/n-6 ratios, which is highly desirable in food destined for human consumption. In addition, the concentration of pancreatic lipase 1 (70.2 kDa) in anterior intestine and pyloric caeca of fish significantly decreased (P = 0.0019) from 2.93 to 1.85 mg g−1 as the level of FO replaced increased. These findings indicate that up to 100% of FO can be replaced by S. limacinum meals improving the growth of T. macdonaldi and preserving the nutritional value and the health benefits of the fillet for human consumption; whereas, SO decreased growth and the concentration of 22:6n-3, 20:5n-3, total n-3, and n-3/n-6 ratios, while increasing the HSI and the risk of hepatic dysfunction and steatosis.

An estimation of the dietary long-chain n-3 polyunsaturated fatty acids levels for optimum growth and feed utilisation for large Yellowtail Kingfish (Seriola lalandi)

Understanding optimal dietary long chain n-3 polyunsaturated fatty acid (LC n-3 PUFA) levels for aquaculture species is vital to sustainably and economically utilise fish oil. The optimum dietary LC n-3 PUFA level for large Yellowtail Kingfish (Seriola lalandi; YTK) was unknown. In this 84 day study, the growth, feed efficiency and health of YTK (2.67 kg) fed graded levels of dietary fish oil, using poultry oil as the replacement, were investigated to determine the practical optimal dietary LC n-3 PUFA levels. Eight diets were formulated to contain graded dietary LC n-3 PUFA levels that ranged from 0.753 to 2.950 g 100 g−1. There was a moderate positive quadratic relationship between dietary LC n-3 PUFA and specific growth rate (SGR) (R2 = 0.5697; P < .001). Based on the SGR, the optimal level of LC n-3 PUFA (ymax) was 2.12 g 100 g−1. This equated to a LC n-3 PUFA daily intake of 191 mg kg−1 d−1. There was no improvement in SGR by increasing LC n-3 PUFA levels above 2.39 g 100 g−1. There was a moderate negative quadratic relationship between dietary LC n-3 PUFA level and feed conversion ratio (FCR) (R2 = 0.5758; P < .001). The FCR of YTK improved as dietary LC n-3 PUFA levels increased from 0.75 to 2.14 g 100 g−1. Based on the FCR, the optimal level of LC n-3 PUFA (ymin) was 2.26 g 100 g−1. This equated to a LC n-3 PUFA daily intake of 203 mg kg−1 d−1. The 95% CI for each response variable ranged between 1.90 and 2.33 g 100 g−1 and 1.93 to 2.58 g 100 g−1 for SGR and FCR, respectively. Apart from minor alterations to hindgut villus branching, LC n-3 PUFA level had no significant impacts on hind or midgut histology (P > .05). Based on SGR and FCR response variables it was estimated that the optimal dietary level of LC n-3 PUFA for large YTK was between 2.12 and 2.26 g 100 g−1.

Effects of dietary fish oil and soya bean lecithin on gonad index, colour and biochemical composition of the purple sea urchin,Strongylocentrotus purpuratus(Stimpson 1857)

The effects of increasing soya bean lecithin (SL) levels (0%, 2% and 4% of diet dry matter, DM) at two fish oil (FO) levels (0% and 3% DM) on gonad index, colour and biochemical composition of Strongylocentrotus purpuratus were evaluated using a 3 × 2 factorial design with six iso‐nitrogenous formulated diets. All diets generated an increase in gonad index of more than 9%. Dietary FO had a positive effect on diet digestibility and accumulation of proteins in the gonad. Soy lecithin did not affect gonad composition, but improved its coloration, decreased gonad feed conversion ratio and increased gonad protein efficiency. There was a clear effect of diets on sea urchins gonad protein, ash and fatty acid content, in particular, decreasing the n‐3/n‐6 ratio associated with a decrease in 20:5n‐3 when SL levels increased. Nevertheless, 22:6n‐3 levels increased by week 12 in all treatments, and diets with SL increased the content of 20:4n‐6 in gonads. A decrease in bitter‐tasting amino acids such as histidine, cysteine, valine and methionine was observed in all treatments with a concomitant increase in isoleucine levels. We recommend using a diet containing 3% of FO and 2% of SL to increase food consumption, diet digestibility, improving marketable gonad colour and an increasing gonad n‐6 fatty acids and C22:6n‐3. In addition, the present study paves the way for future research in the use of FO and SL as an additive in diets for S. purpuratus towards the goal of increasing gonad size and nutritional quality.

The effect of oxidized fish oil on lipid metabolism in Rhynchocypris lagowski Dybowski

Fish oil can not only provide energy for the growth and development of fish, but also constitute a variety of tissue and cellular structural components of fish. However, fish oil is easily oxidized in the process of feed processing, treatment and storage, which reduces the feed quality and threatens the health of fish. Therefore, the purpose of this study was to investigate the effects of different degrees of oxidation of fish oil in feed on fatty acid composition and lipid metabolism in hepatopancreas of Rhynchocypris lagowski Dybowski. Five diets containing five oxidation levels (0, 100, 200, 300 and 400 meq/kg) of fish oil were formulated and fed to 525 healthy R. lagowski (4.48 ± 0.14 g) that were randomly divided into 15 glass aquariums. After 8 weeks, hepatopancreas samples were taken for fatty acid composition, and biochemical analysis. The results showed that the content of Polyunsaturated fatty acid (PUFA) in muscle of R. lagowski increased significantly with the increase of oxidation degree of fish oil (P < 0.05), but there were no changes in Saturated fatty acid (SFA), Monounsaturated fatty acid (MUFA), EPA (C20:5n3), and ∑n-6 (P>0.05). Compared with the control group, the contents of SFA, MUFA and EPA in hepatopancreas were significantly increased (P < 0.05), while DHA (C22:6n3), ∑n-3, ∑n-6, and PUFA were decreased (P < 0.05). Feeding with OFO increased hepatopancreas total cholesterol (TC), triacylglycerol (TG), HDL/LDL ratio, FAS, and ACCα that involved in lipid synthesis enzymes (P < 0.05), while reduced liver esterase (HL), fatty acyl-CoA synthetase (ACS), carnitine palmitoyltransferase (CPT-1) and hormone-sensitive triglyceride lipase α (HSLα) enzyme activity and gene expression that associated with lipid decomposition (P < 0.05). It is suggested that the adverse effects of dietary oxidized oil may be achieved by promoting fatty acid synthesis, inhibiting fatty acid oxidation, increasing fatty acid uptake by hepatopancreas and reducing the ability of TG to transport from hepatopancreas to extrahepatic tissues, thus inducing fat accumulation in hepatopancreatic cells and further affecting lipid metabolism in hepatopancreas.

Arachidonic acid effects on the overall performance, fatty acid profile, hepatopancreas morphology and lipid-relevant genes in Litopenaeus vannamei juveniles

The effect of arachidonic acid (ARA) was evaluated on Litopenaeus vannamei juveniles. Growth performance; hepatopancreas and muscle fatty acid compositions; hepatopancreatic cells morphology; and expression of lipid-relevant genes were estimated after six-week experiment. A basal fat-reduced diet was manufactured and subsequently coated with different fatty acids sources, distinct levels of ARA (0, 0.3, and 0.6%), fish and soybean oil (50:50 Control diet). L. vannamei juveniles (1.10 ± 0.22 g) were randomly divided into twelve tanks with thirty animals each. The animals were fed three times per day, with 8% of the total biomass. The results showed that animals fed with diet containing 0.3% of ARA presented a lower final weight compared to the Control. Different levels of ARA inclusion in the experimental diets directly influenced in the tissues fatty acid profile with lower ARA levels in Control and 0% followed by 0.3% and 0.6%. In muscle and hepatopancreas tissues, a higher accumulation of docosahexaenoic acid (DHA) was revealed in the Control compared to the rest of the experimental treatments. The expression pattern of lipoxygenase (alox5), prostaglandin E synthase (pges2), sterol regulatory element-binding protein-1 (srebp1) and cycloxygenase (cox2) were significantly affected by the ARA inclusion, showing the highest expression in the Control treatment with a decrease according to the increasing levels of dietary ARA. It is concluded that ARA inclusion in shrimp diets result in a negative impact on the overall performance, probably modulated by a differential gene expression related to the eicosanoids synthesis, lipolytic and lipogenic pathways. Besides, the lipid deposition on the hepatopancreatic cells was reduced.