Dietary Vegetable Oils Research Articles

Differential effects of Chinese high-fat dietary habits on lipid metabolism: mechanisms and health implications

BackgroundThe traditional Chinese diet blends lard with vegetable oil, keeping the fatty acid balance intake ratio of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids at nearly 1:1:1. However, the effects of a mixture of lard and vegetable oil on lipid metabolism have never been researched. In the present study, by simulating Chinese high-fat dietary habits, we explored the effects of a mixture of lard and vegetable oil on lipid metabolism.MethodsWe randomly assigned 50 male C57BL/6 J mice to 5 groups (10 in each group) and fed them lard, sunflower oil (SFO), soybean oil (SBO), lard blended with sunflower oil (L-SFO), or lard blended with soybean oil (L-SBO) for 12 weeks.ResultsWe found that the final body weights of mice in the lard group were significantly higher than those of mice in the SFO and SBO groups. Body fat rate and volume of fat cell of the lard group were significantly higher than those of the SFO, SBO, and L-SBO groups. Liver triglyceride level of the lard group increased significantly compared to the other groups. Although body fat rate and liver triglyceride level in the SBO and SFO groups decreased compared to those in the other groups, the high-density lipoprotein cholesterol/low-density lipoprotein cholesterol ratio were also significantly decreased in the SBO and SFO groups.ConclusionsWe found that a lard diet induced accumulation of body fat, liver and serum lipids, which can increase the risk of obesity, non-alcoholic fatty acid liver disease, and atherosclerosis. The vegetable oil diet resulted in cholesterol metabolism disorders even though it did not lead to obesity. The mixed oil diet induced body fat accumulation, but did not cause lipid accumulation in the liver and serum. Thus, differential oil/fat diets have an impact on differential aspects in mouse lipid metabolism.Graphical abstract

Genome wide identification and functional characterization of two LC-PUFA biosynthesis elongase (elovl8) genes in rabbitfish (Siganus canaliculatus)

Elongases of very long-chain fatty acids (Elovls) catalyze the rate-limiting step of the elongation pathway that results in net two‑carbon elongation of pre-existing fatty acyl chains. As a set of crucial enzymes involved in the long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis, Elovls of fish have been investigated extensively in recent years. In the present study, we first identified two novel fish-specific elovl genes (named as elovl8a and elovl8b) from the herbivorous marine teleost rabbitfish (Siganus canaliculatus) by genomic survey and molecular cloning methods. Subsequently, their functional characteristics, tissue distribution patterns and transcriptional changes in response to different nutritional states were investigated. Full-length coding sequences of the elovl8a and elovl8b genes were 804 and 792 bp, encoding 267 and 263 amino acids, respectively. Multiple alignment, genomic synteny and phylogenetic analyses further suggested that elovl8 genes were unique to teleosts. Functional characterization by heterologous expression in yeast showed that Elovl8b could elongate C18 (18:2n-6, 18:3n-3 and 18:4n-3) and C20 (20:4n-6 and 20:5n-3) polyunsaturated fatty acids (PUFAs) to longer-chain polyunsaturated fatty acids (LC-PUFAs) whereas Elovl8a lacked this ability. In vitro, the expression of elovl8b but not elovl8a in rabbitfish hepatocytes was significantly up-regulated by incubation with 18:2n-6, 18:3n-3, 20:4n-6 and 20:5n-3, respectively. In vivo, compared with fish oil, dietary vegetable oil enriched in C18 PUFA enhanced the expression of elovl8b in rabbitfish brain, liver, intestine and gill tissues. These findings suggest that elovl8b but not elovl8a is a novel active member of the Elovl protein family involved in the LC-PUFAs biosynthesis pathway in rabbitfish, and provide novel insight into the mechanisms of LC-PUFAs biosynthesis in teleost.

ToF-SIMS spectrometry to observe fatty acid profiles of breast tissues in broiler chicken subjected to varied vegetable oil diet.

This study is aimed to observe changes in fatty acid profiles by time of flight secondary ion mass spectrometry (ToF-SIMS) in breast muscle tissues of broilers. Four different groups were identified. The source of fat in group I was soy oil (rich in linoleic acid, ω-6), group II received linseed oil (ω-3), and the third group was fed a mixture of the two mentioned oils. Broilers in the control group were fed with beef tallow, used in mass commercial production. The results reveal that the use of vegetable oils in animal nutrition determines the lipid profile of fatty acids. ToF-SIMS measurements showed that the lipid profile of muscle fibers and intramuscular fat reflect the composition of fats used as feed additives. In both structures, the ratio of ω-6/ω-3 fatty acids, which is most favorable for human health, was found in the groups in which a mixture of vegetable oils and a supplement of linseed oil were used.

Effects of Dietary Vegetable Oils on Mammary Lipid-Related Genes in Holstein Dairy Cows.

Simple SummaryThis study analyzed effects of vegetable oils fed to dairy cows on abundance of genes related to lipid metabolism in milk somatic cells (MSC). During 63 days (9 weeks), 15 cows were allocated to 3 treatments: a control diet with no added lipid and the same diet supplemented with olive oil (OO, 30 g/kg DM) or hydrogenated vegetable oil (HVO, 30 g/kg DM). Dietary oil supplementation (3% DM) had a modest nutrigenomic effect on biological functions such as acetate and FA activation and intra-cellular transport, lipid droplet formation, and transcription regulation in MSC. Results suggest that long-term dietary monounsaturated and saturated lipids could alter mRNA abundance in MSC from mid-lactating cows.This study analyzed effects of vegetable oils fed to dairy cows on abundance of genes related to lipid metabolism in milk somatic cells (MSC). During 63 days, 15 cows were allocated to 3 treatments: a control diet with no added lipid the same diet supplemented with olive oil (OO, 30 g/kg DM) or hydrogenated vegetable oil (HVO, 30 g/kg DM). On days 21, 42 and 63, MSC were obtained from all cows. Relative abundance of genes involved in lipid metabolism in MSC from cows fed control on days 42 and 63 was compared with relative abundance at day 21 to evaluate fold-changes. Those genes without changes over the time were selected to analyze effects of OO and HVO. Compared with control, on day 42, PLIN2 and THRSP were upregulated by OO. Compared with control, on day 21, HVO up regulated ACACA, down regulated FABP3, and on day 63 THRSP and FABP4 were down regulated. Dietary oil supplementation (3% DM) had a modest nutrigenomic effect on different biological functions such as acetate and FA activation and intra-cellular transport, lipid droplet formation, and transcription regulation in MSC.

Endogenous Losses of Fat and Fatty Acids in Growing Pigs Are Not Affected by Vegetable Oil Sources but by the Method of Estimation.

Simple SummaryApparent digestibility of fat in diets does not reflect the true availability of fat, especially in low-fat diets. Estimation of endogenous losses of fat and fatty acids from the digestive tract is required for the determination of true digestibility of fat. This study evaluates the effect of oil sources on endogenous losses of fat and fatty acids in growing pigs in which endogenous losses were estimated by both regression and fat-free diet methods. Results indicate that the estimated values for endogenous losses of fat and fatty acids were not different in pigs fed palm oil, soybean oil, flaxseed oil or rapeseed oil. The fat-free diet had lower estimated values compared with the regression method. A fat-free diet method deserves to be explored further. These findings contribute to accurate estimation of endogenous losses of fat and fatty acids for vegetable oils in the future.An experiment was conducted to determine the effect of oil sources with differing degrees of fatty acid saturation on endogenous losses of fat (ELF) and fatty acids (ELFA) in growing pigs, in which endogenous losses were estimated by two methods. Sixty-eight growing barrows (initial body weight 31.13 ± 4.44 kg) were randomly allotted to a completely randomized design with 17 diets. Sixteen added-oil diets were formulated by adding four levels (2%, 4%, 6% and 8%) of palm oil (PO), soybean oil (SBO), flaxseed oil (FSO) and rapeseed oil (RSO) to a diet poor in fat, respectively. One fat-free diet was formulated from cornstarch, soy protein isolate and sucrose. All diets contained chromic dioxide (0.4%) as an indigestible marker. Results indicated that, according to the regression equations, the amounts of ELF in PO, SBO, FSO and RSO were 6.28, 5.30, 4.17 and 4.84 g/kg of dry matter intake (DMI), respectively. The true total tract digestibility of fat was greater (p < 0.05) for FSO and RSO than for PO, and the ELFA were different from 0 only for C16:0, C18:0 and C18:1 in FSO, and C16:0 and C18:0 in RSO (p < 0.05). The estimated values for ELF and ELFAs in pigs fed PO, SBO, FSO or RSO were not different. The amount of ELF determined by the fat-free diet method was 2.60 g/kg DMI, and the amounts of C16:0, C18:0, C18:1 and C18:2 in ELFAs were 0.28, 0.26, 0.03 and 0.02 g/kg DMI, respectively. The fat-free diet method had lower ELF and ELFA values compared with the regression method (p < 0.01). Collectively, dietary vegetable oil sources do not affect estimation of ELF and ELFA, but different evaluation methods lead to varying estimates of endogenous losses in pigs.

Effects of different dietary vegetable oils on growth and intestinal performance, lipid metabolism and flesh quality in gilthead sea bream

This study tests the effects of feeding different vegetable oils (VO) in gilthead sea bream with the aim of improving sustainable aquafeeds. Juveniles were fed ad libitum with ten isonitrogenous (46%) and isolipidic (22%) diets with a 75% fish oil (FO) replacement, differing in VO composition leading to two experimental blocks: fish fed with VO blends or mono-substituted diets. Growth parameters, skin and muscle colour, muscle texture, plasma metabolites, digestive capacities, and transcript levels of intestinal lipid transport, muscle dynamics and lipid metabolism-related genes in white muscle and adipose tissue were studied. In fish fed high-palm oil diets, final body weight and mesenteric fat significantly increased, while effects were not found in hepatosomatic index, reflecting tissue-specific lipid accumulation. Relative intestinal length increased significantly with dietary soya oil (SO) content, suggesting a compensatory mechanism to improve nutrient absorption capacity. Plasma parameters showed few changes upon dietary treatments. Lipase activity was unaltered, while intestinal fatp1b expression increased in animals fed blended diets high in rapeseed oil (RO). In adipose tissue, expression of nuclear receptors pparβ and lxr was modified by dietary fatty acids (FA) profile; however, regarding lipid metabolism and β-oxidation genes, only lpl showed significant differences, suggesting that FA uptake and oxidation, but not de novo lipogenesis is what appears to determine the increase in adipose tissue mass. In fish fed blended VO diets, lpl expression showed a positive correlation with MUFA dietary content, suggesting that some FA present in RO enhance its expression, according to data from fish fed mono-substituted diets. In muscle, fish fed blended VO diets also showed a positive correlation of lpl expression with dietary MUFA, whereas in mono-substituted, it was significantly higher in fish fed SO, suggesting other mechanisms are involved in LPL regulation. Concerning β-oxidation genes in muscle, significant differences were detected in cpt1a expression for fish fed blended VO diets, whereas hadh and cpt1b were unaltered, suggesting slight FA uptake regulation in mitochondria. Expression levels of genes related to myogenic processes were not greatly modified by dietary lipid sources except for myogenin in blended VO diets-fed fish, showing a similar profile as that in body weight and opposite with the differentiation marker mhc. This study provides new information regarding the effects of dietary VO, demonstrating moderate effects in lipid homeostasis without adverse effects on growth performance, leading to a transversal view of the responses and interactions from intestine to muscle growth and flesh quality.

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

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

Dietary vegetable oils inclusion on the performance, hormonal levels and hsp 70 gene expression in broilers under heat stress

The aim of the present study was to compare the effects of unsaturated and saturated oils on the performance, hormonal levels and hsp gene expression in broiler chickens exposed to heat stress. 300 one-day male broiler chicks were assigned to 4 treatments (Diets containing palm, corn, linseed or olive oils) with 5 replicates. At day 28 of age, 2 chickens were removed from each replicate, then blood samples and liver tissue samples were collected for analyses. Feeding linseed and olive oil reduced feed conversion ratio compared to corn and palm oils. The lowest level of insulin was for chickens fed linseed oil and corn oil. The highest level of corticosterone was found in chickens fed palm oil and the lowest level was for those received linseed oil. Chickens received linseed and corn oils had the highest levels of T3 and T4 and those fed palm and olive oils had the lowest levels. The highest HSP 70 gene expression was for chickens fed diet containing olive and linseed oils and the lowest one was for those fed corn and palm oils. It was concluded that olive oil and linseed oil could improve performance and heat tolerance of chickens under heat stress.

Effects of dietary vegetable oils on the expression of eicosanoid receptors genes in Senegalese sole (Solea senegalensis) intestine

Vegetable oils (VO) are being extensively used as lipid sources in marine fish diets, due to the decreased availability of fish oil. The use of VO could induce some imbalances on essential fatty acids (EFAs) with the subsequent well described detrimental effects on fish immunity. EFAs are directly associated with several immune functions, acting as important elements for the fluidity of cytoplasmic membranes and as precursors of eicosanoids. At intestinal level, eicosanoids produced via cyclooxygenase (COX-2) enzymes are involved in gastrointestinal cyto-protection by influencing the homeostasis regulation and the onset of gut inflammation process through the action on eicosanoid receptors (EPs), which modulate gastrointestinal mucosal integrity amongst other functions. Senegalese sole is a flatfish with high susceptibility to deleterious effects due to stress and diseases and highly sensitive to changes in dietary fatty acids. In this study, Senegalese sole juveniles were fed diets (56% crude protein, 12% crude lipid) containing linseed (100LO), soybean (100SO) or fish (100FO) oils as unique oil source. Intestinal fatty acid composition plus relative expression of intestinal EPs and other genes related with eicosanoid cascade were determined after 90 days. Moreover, at the end of the experiment a stress test (5 min of net chasing) was carried out. The use of VO altered the fatty acid profile of intestine and the expression of EP genes. The use of SO (rich in n-6 fatty acids) induced an overexpression of cox-2 in basal (non-stress) situation, plus a down-regulation of intestinal ep4 gene expression. Besides, fish fed soybean oil in the diet seems to be unable to respond properly to chasing stress.

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

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

Influence of different lipid sources on growth performance, oxidation resistance and fatty acid profiles of juvenile swimming crab, Portunus trituberculatus

The effects of dietary lipid sources on growth performance, feed utilization, hematological characteristics, antioxidant capacity and tissue fatty acid profiles were assessed in juvenile swimming crab (Portunus trituberculatus). Six isonitrogenous (approximately 45% crude protein) and isolipidic (approximately 8% crude lipid) experimental diets were formulated to contain fish oil (FO), krill oil (KO), palm oil (PO), rapeseed oil (RO), soybean oil (SO) and linseed oil (LO), respectively. 270 swimming crab juveniles (approximately initial weight 5.43 ± 0.03 g) were randomly stocked and sorted into 270 individual rectangle plastic baskets in three cement pools. The results showed that crabs fed the diet containing KO had a significantly higher percent weight gain (PWG), specific growth rate (SGR) and molting ratio (MR) than those fed the other diets. Crabs fed the KO diet had the lowest feed conversion ratio (FCR) among all treatments, followed by the FO diet. However, survival, daily feed intake (DFI) and hepatosomatic index (HSI) were not affected by the dietary lipid sources. Crabs fed the FO and KO diets led to significantly higher glucose (GLU) concentration in hemolymph compared to that fed the vegetable oils (VOs) diets. Moreover, a significant elevation of total protein (TP), glucose (GLU) and low density lipoprotein (LDL) was observed in hemolymph of crabs fed the KO diet. The activities of total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC) as well as the content of glutathione (GSH) in hepatopancreas of crabs fed the KO diet had the highest value among all treatments. The minimum concentrations of MDA in hemolymph and hepatopancreas were observed in crabs fed the KO diet. The fatty acid compositions of tissues reflected that of diets and lipid sources. Crabs fed the FO and KO diets had significantly higher values of EPA, DHA and n-3/n-6 ratio in hepatopancreas and muscle than those fed the VOs diets. In summary, based on the growth response and antioxidant capacity in comparison to VOs even FO, KO appeared to be more effective and beneficial for juvenile swimming crab. This will provide reference for the development of the diet for the reproductive and developmental stage of swimming crab.

Effects of dietary lipid sources on the intestinal microbiome and health of golden pompano (Trachinotus ovatus)

Replacement of fish oil (FO) with vegetable oils (VO) in diets is economically desirable for the sustainable development of the aquaculture industry. However, inflammation provoked by FO replacement limited its widely application in fish industry. In order to understand the mechanism of VO-induced inflammation, this study investigated the impact of different dietary vegetable oils on the intestinal health and microbiome in carnivorous marine fish golden pompano (Trachinotus ovatus). Three diets supplemented with fish oil (FO, rich in long-chain polyunsaturated fatty acids), soybean oil (SO, rich in 18:2n-6) and linseed oil (LO, rich in 18:3n-3), respectively, were fed on juvenile golden pompano for 8 weeks, and the intestinal histology, digestive enzymes activities, immunity and antioxidant indices as well as intestinal microbiome were determined. The results showed that dietary SO significantly impaired intestinal health, and decreased the number and height of intestinal folds, and muscle thickness, as well as the zonula occludens-1 (zo-1) mRNA expression in intestine. Moreover, the two dietary VO significantly decreased the amylase and lipase activities in intestine, and reduced the trypsin activity in the dietary SO group. Furthermore, the two VO diets increased intestinal acid phosphatase (ACP) activity, while intestinal lysozyme (LZM) activity and serum diamine oxidase (DAO) activity in the SO group were also significantly increased (P < 0.05). Analysis of the intestinal microbiota showed that the two VO diets significantly increased the abundance of intestinal potentially pathogenic bacteria (Mycoplasma and Vibrio) and decreased proportions of intestinal probiotics (Bacillus and Lactococcus), especially in the dietary SO group. These results indicate that complete replacement of FO with VO in diets would induce intestinal inflammation and impair intestinal function, which might be due to changes in intestinal microbiota profiles, and that dietary SO would have a more negative effect compared to dietary LO on intestinal health in T. ovatus.

Effects of Replacement of Fish Oil by a Mixture of Balanites aegyptiaca and Adansonia digitata Seed Oils on the Growth and Survival of Clarias anguillaris Fries (Linnaeus, 1758)

To investigate the effects of replacement of fish oil by a mixture of Balanites aegyptiaca and Adansonia digitata seed oils three isonitrogenous (35.36%) and isoenergetic diets (3.48 MJ / kg) were formulated for one kilogram (1kg). The study was carried out on fries Clarias anguillaris for six weeks.At the beginning of the experiment, 90 Clarias anguillaris of the initial average weight of 0.82 ± 0.055g were randomly divided into three different groups with two replicates containing 15 fish/each. Fish were kept in six plastic tanks (50 x 40 x 30 cm) container (50 L). The results showed that the substitution of fish oil by a mixture of Balanites aegyptiaca seed oil and Adansonia digitata seed oil gives growth for all diets. However, the best growths are obtained from all points of view (MWGr, MWGa and SGR) with diet A (mixture of Adansonia seed oil and Balanites seed oil at a ratio of 20 : 20) followed by the diet D (mixture of Adansonia seed oil and Balanites seed oil at 10 : 30) compare to the control diet M containing fish oil. The best FCR was observed with the diet A followed by the diet D compare to the FCR observed with the diet M. The PER was higher in diet A (0.57) followed by diet D with (0.45) that has no significant difference with the control diet M (0.43). The highest value 63% was obtained with the diet D followed by 60% with the diet M and finally the lowest value 53% was obtained with the diet A. In regards to the growth performance, fish fed a 100% vegetable oil diet showed the best growth performance. Therefore, the replacement of fish oil with a mixture of Balanites aegyptiaca seed oil and Adansonia digitata seed oil has no negative impact on the growth of Clarias anguillaris fry. It would be interesting first to study the inclusion rate of Balanites aegyptiaca seed oil for a partial replacement of fish oil.

Essential fatty acid deficiency increases hepatic non-infectious granulomatosis incidence in meagre (Argyrosomus regius, Asso 1801) fingerlings

Meagre (Argyrosomus regius) is a promising new aquaculture species, however with some bottlenecks to high-scale commercial production. One of those constraints are the scarce information about its nutritional requirements, which difficult the production of optimized diets and can lead to pathological alterations in liver, such as hepatic steatosis. Furthermore, meagre production is widely affected by granulomatosis, an infectious or non-infectious disease that may compromise fish performance and appearance. The cause of non-infectious granulomatosis is still unclear, but nutritional deficiencies are potential explanations. Since essential fatty acids are nutrients required to sustain vital functions, growth, but also immune status and disease resistance, the present work evaluated, in a 30-day feeding trial, the effect of 5 dietary n-3 long-chain polyunsaturated fatty acid levels (0.8, 1.4, 2.0, 2.6 and 3.5% in dry weight of the diet) on liver health status of meagre fingerlings. Fish fed the lowest n-3 LC-PUFA diets (0.8 and 1.4%) showed a higher hepatosomatic index, as well as a higher hepatic lipid infiltration, which resulted in severe hepatic steatosis. Oleic acid and docosahexaenoic acid were the most important fatty acids driving the variability of meagre hepatic fatty acid composition and, consequently, hepatic histological alterations. Although fatty acid composition of phospholipids was less affected by the dietary n-3 LC-PUFA, meagre fed 0.8% n-3 LC-PUFA tended to present lower levels of essential fatty acids and higher levels of oleic acid in polar lipids. Moreover, the diet with the lowest n-3 LC-PUFA content (0.8%) led to a higher incidence of hepatic granulomas, suggesting a possible relation between essential fatty acid deficiency and hepatic granulomatosis in meagre. These results suggest that the inclusion of vegetable oils in diets for meagre fingerlings should be taken with careful, guaranteeing that, at least, 2.0% DW of n-3 LC-PUFA is available in feeds, in order to maintain the normal hepatic function in meagre.

Effects of fish oil replacement with vegetable oil in diet of sterlet sturgeon (Acipenser ruthenus) broodstock on expression of lipid metabolism related genes in eggs

A 7-month feeding trial was conducted before spawning induction in sterlet (Acipenser ruthenus) broodstock (initial weight 990.3 ± 20.05 g). The effects of dietary fish and vegetable oils were investigated on fatty acid profiles in eggs, hematological characteristics, serum lipid indices, and expression of some lipid metabolism and transport-related genes. Three experimental diets with different levels of fish and vegetable oils were formulated as: FO (100% kilka oil), VO (100% rapeseed oil), and FO + VO (50% kilka oil + 50% rapeseed oil). At the end of the feeding trial, egg samples from ovulating females were collected to examine fatty acid profiles and transcriptional mechanisms involved in lipid metabolism and transport. The broodstock physiological condition was assessed using hematological and biochemical indices. Similar to the diets, oleic acid (18:1n-9) was the most predominant monounsaturated fatty acid among all lipid classes in sterlet eggs. Results revealed that the eggs of the broodstock fed VO diet had the highest ratio of DHA/EPA, while the eggs of the broodstock fed FO + VO or FO diet showed higher ratios of EPA/ARA and DHA/ARA. No changes were observed in the levels of lipoproteins, blood lipid indices or hematological parameters in broodstock. This implies that the examined oil sources did not have any adverse effects on fish health during the feeding trial. Feeding different dietary ratios of VO and FO resulted in altered expression of ApoE and PPARα in the eggs, suggesting that lipid metabolism pathways can be influenced by dietary lipid sources. Compared with broodstock fed FO or FO + VO diet, in eggs from the broodstock fed VO diet the expression of ApoE gene was significantly up-regulated and the expression of PPARα was down-regulated. However, the expression of PPARγ was not significantly different among the dietary treatments. Different expression levels of related genes in treatment with various oil sources demonstrate that ApoE, PPARα, and PPARγ play key roles in lipid metabolism, such that they might perform different functions in lipid metabolism and utilization.

MiR-24 is involved in vertebrate LC-PUFA biosynthesis as demonstrated in marine teleost Siganus canaliculatus

Recently, microRNAs (miRNAs) have emerged as crucial regulators of lipid metabolism. However, the miRNA-mediated regulatory mechanism on long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA) biosynthesis in vertebrates remains largely unknown. Here, we address a potentially important role of miRNA-24 (miR-24) in the regulation of LC-PUFA biosynthesis in rabbitfish Siganus canaliculatus. miR-24 showed significantly higher abundance in liver of rabbitfish reared in brackish water than in seawater for fish fed vegetable oil diets and in S. canaliculatus hepatocyte line (SCHL) cells incubated with alpha-linolenic acid (ALA) than the control group. Similar expression patterns were also observed on the expression of sterol regulatory element-binding protein-1 (srebp1) and LC-PUFA biosynthesis related genes. While opposite results were observed on the expression of insulin-induced gene 1 (insig1), an endoplasmic reticulum membrane protein blocking Srebp1 proteolytic activation. Luciferase reporter assays revealed rabbitfish insig1 as a target of miR-24. Knockdown of miR-24 in SCHL cells resulted in increased Insig1 protein, and subsequently reduced mature Srebp1 protein and expression of genes required for LC-PUFA biosynthesis, and these effects could be attenuated after additional insig1 knockdown. Opposite results were observed with overexpression of miR-24. Moreover, increasing endogenous insig1 by knockdown of miR-24 inhibited Srebp1 processing and consequently suppressed LC-PUFA biosynthesis in rabbitfish hepatocytes. These results indicate a potentially critical role for miR-24 in regulating LC-PUFA biosynthesis through the Insig1/Srebp1 pathway by targeting insig1. This is the first report of miR-24 involved in LC-PUFA biosynthesis and thus may provide knowledge on the regulatory mechanisms of LC-PUFA biosynthesis in vertebrates.

Screening dietary biochanin A, daidzein, equol and genistein for their potential to increase DHA biosynthesis in rainbow trout (Oncorhynchus mykiss).

Plant oil utilization in aquafeeds is still the most practical option, although it decreases the content of the nutritionally highly valuable omega-3 fatty acids eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) in fish. Phytoestrogens and their metabolites are putatively able to affect genes encoding proteins centrally involved in the biosynthesis of EPA and DHA due to their estrogenic potential. Thus, the aim of the study was to screen the potential of the phytoestrogens to stimulate the biosynthesis of EPA and DHA in rainbow trout (Oncorhynchus mykiss). Additionally, the potential effects on growth performance, nutrient composition and hepatic lipid metabolism in rainbow trout were investigated. For that, a vegetable oil based diet served as a control diet (C) and was supplemented with 15 g/kg dry matter of biochanin A (BA), daidzein (DA), genistein (G) and equol (EQ), respectively. These five diets were fed to rainbow trout (initial body weight 83.3 ± 0.4 g) for 52 days. Growth performance and nutrient composition of whole body homogenates were not affected by the dietary treatments. Furthermore, feeding EQ to rainbow trout significantly increased DHA levels by +8% in whole body homogenates compared to samples of fish fed the diet C. A tendency towards increased DHA levels in whole body homogenates was found for fish fed the diet G. Fish fed diets BA and DA lacked these effects. Moreover, EQ and G fed fish showed significantly decreased hepatic mRNA steady state levels for fatty acyl desaturase 2a (delta-6) (fads2a(d6)). In contrast, carnitine palmitoyl transferases 1 (cpt1) hepatic mRNA steady state levels and hepatic Fads2a(d6) protein contents were not affected by the dietary treatment. In conclusion, when combined with dietary vegetable oils, equol and genistein seem to stimulate the biosynthesis of DHA and thereby increase tissue DHA levels in rainbow trout, however, only to a moderate extent.

Adipose tissue contributes to hepatic pro-inflammatory response when dietary fish oil is replaced by vegetable oil in large yellow croaker (Larimichthys crocea): An ex vivo study

The shortage of fish oil (FO) leads to the extensive use of vegetable oil (VO) in marine fish diets. High replacement percentage of dietary FO by VO induced pro-inflammatory response of adipose tissue (AT) and liver tissue (LT) in large yellow croaker (Larimichthys crocea). Mammalian studies showed that the secretion of cytokines by AT affected the immune response of LT. To investigate whether or not the inflammation response of LT is related to AT in large yellow croaker, LT and AT cells from fish fed FO diet (FOL and FOA) and VO diet (VOL and VOA) were co-cultured in a trans-well system, which resulted in an assembly of the two cells types sharing the culture medium but being separated by the membrane of the insert.Co-culture of FOL and FOA was selected as the control group (FOL-FOA). Results indicated that, when compared with the control group, the expression of pro-inflammatory genes (toll like receptors [TLRs], tumour necrosis factor α [TNFα], interleukin 1β [IL1β], suppressor of cytokine signalling 3 [SOCS3] and cyclooxygenase 2 [COX2]) in FOL was significantly increased in the co-culture group of FOL and VOA (FOL-VOA), while the expression of anti-inflammatory genes (arginase I [ArgI] and transforming growth factor β1 [TGFβ1]) in FOL was significantly depressed. On the contrary, a significantly depressed expression of pro-inflammatory genes (TLRs, TNFα, IL1β and COX2) and increased expression of anti-inflammatory genes (interleukin 10 [IL10]) in VOL was observed in the co-culture group of VOL and FOA (VOL-FOA) when compared with the co-culture group of VOL and VOA (VOL-VOA). The change of immune-related gene expressions in LT cells was attributed to nuclear factor κB (NF-κB) signalling since the expression of the p65 protein was observed to show a similar trend to the expression of pro-inflammatory genes. It is speculated that dietary VO increased the secretion of cytokines, which induced pro-inflammatory response in LT cells. These ex vivo results indicate that AT plays a vital role in LT pro-inflammatory response in fish fed VO diet.

Effect of Duration of Dietary Rapeseed and Soybean Oil Feeding on Physical Characteristics, Fatty Acid Profile, and Oxidative Stability of Pig Backfat.

Simple SummaryThe fatty acid profile of pig backfat directly reflects the fatty acid profile of the pig diet. The increased intake of n-3 fatty acids, whose higher content is in vegetable oils, can decrease the risk of heart disease incidence and vascular disorders. The aim of this study was to evaluate the effect of rapeseed and soybean oils and the duration of supplementing the pig diet until slaughter on physical characteristics, fatty acid profile and lipid oxidation of backfat. With the supplementation of oil in the diet for 6 weeks until slaughter, the value of lightness and perforation part of backfat significantly decreased. A dose of 40 g/kg of rapeseed oil in the last 4 weeks before slaughter is sufficient for improving the fatty acid profile without adversely affecting the consistency of the backfat. From the point of view of human health, rapeseed oil is a more suitable source of unsaturated fatty acid than soybean oil in composing the diet for pigs.This study compared the effect of two vegetable oils and their feeding duration on pig backfat quality. The experiment was conducted with 60 DanBred pigs that were fed a diet supplemented (40 g/kg) with rapeseed or soybean oil for 2, 4 or 6 weeks before slaughter at 152 d of age. The supplementation of both vegetable oils in the diets for 6 weeks negatively changed backfat consistency. The pigs fed soybean oil for 4 (17.64%) and 6 weeks (18.52%) before slaughter showed an increase in backfat linoleic acid content (p = 0.002), whereas, in contrast to the other groups, rapeseed oil in the diet for 6 weeks (2.38%) increased α-linolenic acid content (p = 0.039). The content of PUFAs (p = 0.024) and n-6 PUFAs (p = 0.003) was increased by adding soybean oil to the diet for 4 and 6 weeks. The ratio of n-6/n-3 PUFAs was decreased (p = 0.040) by supplementing rapeseed oil for 4 and 6 weeks. The oil feeding duration decreased (p < 0.001) the atherogenic and thrombogenic indices. The lipid oxidative stability of backfat stored for 3 and 5 days increased (p < 0.001) in pigs fed dietary vegetable oils for 6 weeks prior to slaughter. In conclusion, the feeding of rapeseed oil for 4 weeks before slaughter is sufficient for improving the FA profile without negative effect on the consistency of the backfat.

Interactive effects of dietary vegetable oil and carbohydrate incorporation on the innate immune response of European seabass (Dicentrarchus labrax) juveniles subjected to acute stress

This study aims to understand the interactive effects of high dietary vegetable oils (VO) and carbohydrate (CH) content in European seabass cellular, humoral, and molecular innate immune responses to an acute stress. For that purpose, European sea bass juveniles (74.0 ± 1.5 g) were fed four diets differing in lipid source (fish oil (FO) or a blend of vegetable oils (VO)) and carbohydrate content (0% (CH–) or 20% (CH+) gelatinized starch). Nine fish per dietary treatment were sampled after 73 days of feeding and used as control whereas the remaining fish were subjected to an acute stress (netting, 1 min air exposure, and transfer to smaller tanks). Those fish were then sampled after 1 h and considered the stressed group. In the present study, dietary VO incorporation affected fish humoral immune parameters with a decrease of haematocrit, plasma peroxidase activity, and head-kidney mc2r and gr1 mRNA expression levels. Regardless of dietary treatment, higher cortisol levels were accompanied by an increase of several haematological, cellular, and humoral parameters in response to an acute stress. Dietary VO incorporation led to lower neutrophil numbers, plasma antiproteases activity, and head-kidney cox2 expression level in stressed fish. Fish fed CH+ diets showed a reduction of head-kidney mc2r expression levels in response to stress, while plasma cortisol remained unchanged, plasma NO decreases and antiproteases activity increased. In fish fed the VO diets, CH+ led to a decrease of plasma bactericidal activity compared to that of group CH-, while the opposite pattern was observed for plasma peroxidase. In conclusion, dietary substitution of FO by VO in CH– diet negatively affected the immune response in both undisturbed and stressed fish, while the effect of dietary CH incorporation in VO diet was not clear.