Dietary Fish Oil Research Articles

Thraustochytrids and Algae as Sustainable Sources of Long-Chain Omega-3 Fatty Acids for Aquafeeds

There is limited ability to biosynthesize long-chain omega-3 fatty acids such as EPA and DHA in food webs leading to humans. Seafood is the key source of ω3 LC-PUFA, with aquaculture expected to meet rising global demand; however, marine fish have a high dietary requirement for EPA and DHA themselves. This was traditionally met using unsustainable dietary fish oil and fish meal, but limited supply and environmental concerns have dictated research on replacements. Among the industrial sources of EPA and DHA, microalgae and especially thraustochytrids stand out as resources with high concentrations. Although unicellular, thraustochytrids are not microalgae as they are not photosynthetic but instead are microheterotrophs. This removes the light requirement and facilitates high yields of monoculture for the production of single-cell oils. The availability, in high concentrations, of usually one or the other essential fatty acid permits a calibration of the EPA and DHA dose, which is especially useful as their effects have mainly been considered together in medical and aquaculture research. EPA and DHA have different effects on cell function and are precursors of different bioactive compounds. Using thraustochytrids, microalgae, and heterotrophic dinoflagellates, the importance of DHA has been investigated. DHA was essential for optimizing the growth of the early life stages of scallops and finfish and was preferentially incorporated into fish membrane phospholipids. The production of microalgae and microheterotrophs can contribute to the treatment of wastewater and waste gas, further enhancing their sustainability and reducing the environmental costs of aquaculture.

Fish Oil Supplement Mitigates Muscle Injury In Vivo and In Vitro: A Preliminary Report.

Background: Following injury, older adults exhibit slow recovery of muscle function. Age-related impairment of sarcolemmal membrane repair may contribute to myocyte death, increasing the need for myogenesis and prolonging recovery. Dietary fish oil (FO) is a common nutritional supplement that may alter plasma membrane composition to enhance the response to membrane injury. Methods: We assessed effects of an 8-week dietary intervention on muscle contractile recovery in aged (22 mo.) rats on control (n = 5) or FO (control + 33 g/kg FO (45% eicosapentaenoic acid; 10% docosahexaenoic acid); n = 5) diets 1-week after contusion injury, as well as adult (8 mo., n = 8) rats on the control diet. Results: Recovery was reduced in aged rats on the control diet vs. adults (63 vs. 80%; p = 0.042), while those on the FO diet recovered similarly to (78%) adults. To directly assess sarcolemma injury, C2C12 cells were cultured in media with and without FO (1, 10, and 100 μg/mL; 24 or 48 h) and injured with an infrared laser in medium containing FM4-64 dye as a marker of sarcolemmal injury. FO reduced the area under the FM4-64 fluorescence-time curve at all concentrations after both 24 and 48 h supplementation. Conclusions: These preliminary data suggest FO might aid recovery of muscle function following injury in older adults by enhancing membrane resealing and repair.

Impact of oil type and savory plant on nutrient digestibility and rumen fermentation, milk yield, and milk fatty acid profile in dairy cows

Fat supplements are well known for their multiple beneficial effects on ruminant health, reproduction and productivity, and as a source for certain bioactive compounds in ruminant products. On the other hand, numerous phytochemicals have demonstrated the potential to improve rumen fermentation through modifying the volatile fatty acid (VFA) pattern to favour those with greater energy efficiency, boosting microbial protein synthesis, and decreasing methane emission and ruminal ammonia concentration. Savory is an aromatic plant rich in various phytochemicals (mainly carvacrol and flavonoids) that can alter ruminal metabolism of dietary fatty acids, potentially increasing the production of some bioactive compounds such as conjugated linoleic acids (CLAs). This study aimed to investigate combined effects of oil type (fish oil (FO) versus soybean oil (SO)) and the inclusion of savory (Satureja khuzistanica) plant (SP) in the diet on total tract digestibility of nutrients, rumen fermentation, milk yield and milk fatty acid profile in dairy cattle. Eight multiparous lactating Holstein cows were used in a replicated 4 × 4 Latin square design experiment with four diets and four 21-d periods. During each experimental period consisted of 14 days of adaptation and a 7-day sampling period, cows were randomly assigned to one of the four dietary treatments: the diet supplemented with 2% (DM basis) fish oil (FOD) or soybean oil (SOD), the FOD or SOD plus 370 g DM/d/head SP (FODs, SODs, respectively). The experimental diets were arranged in a 2 × 2 factorial design, with the fat sources as the first and SP as the second factor. The FO-supplemented diets had lower dry matter intake (DMI) and higher total tract digestibility than SO-supplemented diets (P < 0.05), and including SP in the diet improved total tract digestibility of dry matter (DM), organic matter (OM), ether extract (EE), and non-fibrous carbohydrates (NFC) (P < 0.05) without negatively affecting DMI. Rumen pH was lower with SO than with FO diets (P < 0.01) and increased with SP inclusion in the diet (P < 0.05). Total protozoa count and ruminal ammonia concentration decreased, and the branched-chain VFA (BCVFA) proportion increased with SP inclusion in the diet (P < 0.05). Milk production, as well as the concentration and yield of milk components (except lactose concentration) were higher with SO than with FO diets (P < 0.05), but these variables remained unaffected by SP. The milk concentrations of both non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB) were lower with SO compared to FO diets, and these variables were reduced by SP (P < 0.01). The proportions of both mono- and polyunsaturated FA (MUFA and PUFA, respectively) in milk were higher with FO than with SO diets (P < 0.01), and their proportions increased by SP at the expense of saturated FA (SFA) (P < 0.01). Including SP in the diet increased the proportions of all the milk n-3 FA (C18:3c, C20:5, and C22:6) by 21%, 40%, and 97%, respectively, and those of conjugated linoleic acids (C18:2 (c9,t11-CLA) and C18:2 (t10,c12-CLA)) by 23% and 62%, respectively. There was no interaction between oil type and SP for the assessed variables. Fish oil, despite reducing milk production and milk components, was more effective than soybean oil in enriching milk with healthy FA. These findings also show promise for SP as a feed additive with the potential to improve total tract digestibility, rumen fermentation and milk FA composition.

Optimal dietary lipid requirement of hybrid lemon fin barb (Barbonymus gonionotus ♀× Hypsibarbus wetmorei ♂) larvae

ABSTRACT Hybrid lemon fin barb is a crossed product between silver barb (Barbonymus gonionotus) and lemon fin barb (Hypsibarbus wetmorei). In the present study, the optimum dietary lipid requirement of larval hybrid lemon fin barb was examined using a total of 90 hybrid larvae (L) of 3-day-old (0.36 ± 0.01 mg). The larvae were stocked in triplicated 90 L tanks and fed with micro diets containing 0, 4, 8, 12, and 16% (FO 0, 4, 8, 12 and 16) dietary lipid levels for 20 days. While hybrid larvae fed non-lipid diet showed lowered survival and growth, larvae fed FO12 diet increased (p < .05) in weight gain, total length gain, specific growth rate, and protein efficiency ratio after 20 days. Hybrid larvae’s whole-body lipid content was increased with increasing dietary lipid level. Hybrid larvae consisted of significantly improved (p < .05) eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and n-3 fatty acid contents at 12% dietary lipid. Excessive dietary lipids resulted in lipid droplets in enterocytes and swollen hepatocytes. The hybrid larvae fed non-lipid diet had shrunken hepatocytes. In conclusion, the optimum dietary lipid requirement for hybrid lemon fin barb larvae in terms of maximum growth is determined at 13.5% dietary fish oil by second-order polynomial analysis.

Effects of Dietary Fish Oil Supplementation on the Growth, Proximate Composition, and Liver Health of Chinese Stripe-Necked Turtle (Mauremys sinensis).

Dietary lipids provide energy for animals and can also be converted into other nutrients (such as non-essential amino acids), which play a role in saving protein. The Chinese stripe-necked turtle is a protected and endangered species that has been bred in captivity; however, basic data on lipid requirements remain unavailable. In this study, 360 Mauremys sinensis (body weight of 65.32 ± 0.15 g) were randomly divided into six groups with three replicates per group; the turtles were fed experimental diets supplemented with various levels of fish oil (i.e., 1% (control group, CG), 3.5% (HF-1), 6% (HF-2), 8.5% (HF-3), 11% (HF-4), and 13.5% (HF-5)) for 10 weeks. The results showed that compared with CG, increasing the fish oil level promoted the growth performance of turtles, and the HF-3 group achieved the best effect. The HF-4 group showed the highest increases in the hepatosomatic index and viscerosomatic index. In addition, increased lipid levels also increased the crude lipid content and reduced the crude protein content in muscle tissue. Oil red O staining showed that the liver lipid content increased with the level of supplemented fish oil, which is consistent with the results of the hepatosomatic index. Compared with CG, triglyceride, total cholesterol, and low-density lipoprotein cholesterol increased significantly in both the liver and serum when fish oil levels exceeded 8.5% (p < 0.05), while high-density lipoprotein cholesterol decreased significantly. Aspartate transaminase and cerealthirdtransaminase levels in serum increased significantly when fish oil levels exceeded 8.5% (p < 0.05). Moreover, the activities of antioxidant enzymes (GSH-Px, SOD, T-AOC, and CAT) and MDA showed similar results, indicating that high fish oil levels (8.5-13.5%) caused liver tissue damage in M. sinensis. Increased fish oil levels significantly upregulated the expression levels of cytokines (IFN-γ, TNF-α, TGF-β1, IL-10, and IL-12) (p < 0.05), downregulated the expression levels of antioxidant enzyme-related genes (cat, mn-sod, and gsh-px), and increased apoptosis of liver cells. Supplementation of the diet with 3.5-6% fish oil improved the growth performance of M. sinensis, and the turtles maintained a beneficial immune status. The results provide a scientific basis for optimizing the commercial feed formula of M. sinensis.

AMPK activation by dietary acadesine improves fillet texture in large yellow croaker (Larimichthys crocea) fed a linseed oil-based diet

The impacts of AMP-activated protein kinase (AMPK) activation by dietary acadesine (AICAR) on growth performance and muscle quality of large yellow croaker (Larimichthys crocea) fed a linseed oil-based diet (LO) were investigated by a 56-day feeding trial in this study. Fish (initial weight: 92.24 ± 0.30 g) were fed fish oil-based diet (FO), LO or LA (LO diet supplemented with 150 mg kg−1 AICAR) with three replicates of each treatment. Results indicated that weight gain rate and specific growth rate (SGR) were significantly decreased in the LO and LA groups than those of the fish fed FO, while the opposite was true for the feed conversion ratio. Moreover, the SGR of fish fed LA was significantly lower than that of the LO group. Dietary linseed oil and AICAR significantly lowered muscle eicosapentaenoic acid and docosahexaenoic acid contents. Furthermore, the LO group showed significantly lower fillet hardness, chewiness and pH, while higher lipid loss than those of the FO group. However, the FO and LA groups had similar fillet hardness, lipid loss and pH. Compared with the fish fed FO and LA, the LO group possessed significantly lower p-AMPK protein level and p-AMPK/AMPK ratio in muscle. The phosphorylation of TOR protein and the ratios of p-TOR/TOR and p-S6/S6 were significantly decreased in muscle of the LA group than those of the fish fed FO and LO. Meanwhile, totally replacing fish oil with linseed oil inhibited the AMPK/SIRT1/PGC-1α pathway, changed myofibre characteristics (e.g., density, diameter and type of myofibre) and raised the expression of genes or activity of enzyme related to anaerobic metabolism in fish muscle. Dietary AICAR activated AMPK/SIRT1/PGC-1α pathway, restored myofibre characteristics and promoted aerobic metabolism-related genes expression in muscle to some extent. In conclusion, total substitution of dietary fish oil with linseed oil reduced growth, feed utilization and nutritive value of large yellow croaker. And high level of dietary linseed oil induced softer texture and poorer liquid holding capacity (LHC) of muscle, which may be ascribed to the myofibre characteristics changed by linseed oil through depressing muscle AMPK/SIRT1/PGC-1α pathway. Inclusion of AICAR in a linseed oil-based diet improved fish muscle hardness and LHC, which may be relevant to the activated muscle AMPK/SIRT1/PGC-1α pathway and restored myofibre characteristics by AICAR. Notably, dietary AICAR could inhibit TOR pathway by activating AMPK in muscle, which may be responsible for the further decreased SGR of fish fed a linseed oil-based diet.

Liver structure and function in yellowtail kingfish, Seriola lalandi, in response to alternative oils in feed

The inclusion of low cholesterol alternatives to fish oil (FO) in aquaculture diets could result in alterations to the biosynthesis and availability of bile acids for the digestions and absorption of dietary lipids. In this study the effects of graded substitution of FO with poultry oil (PO) and the replacement of PO with canola oil (CO) in formulated feeds on Yellowtail Kingfish (1.45 ± 0.12 kg; n = 342) liver function was investigated over 84 days. Dietary FO was replaced with PO at 100%, 75% and 50% inclusion levels (Diets 1, 2 and 3, respectively). The lipid source (PO) was further replaced with CO at 0%, 33.3%, 66.7% and 100% (Diets 2, 4, 5 and 6, respectively). The liver vacuole volume as a proportion of the liver cell volume (VPLC%) was significantly increased (P = 0.008) in fish fed the 100% PO diet (Diet 1) compared to that of fish fed diets with greater levels of FO inclusion (Diets 2 and 3). Regression analyses showed that: 1) liver VPLC% increased as FO decreased (r2 = 0.588; P = 0.016), 2) total bile acid concentration in liver tissue decreased with increasing CO and decreasing PO (r2 = 0.402; P = 0.027), and 3) liver CYP7A1 concentration increased with increasing PO and decreasing FO (r2 = 0.506; P = 0.032). No statistically significant differences were observed in any of the blood biochemistry parameters measured from fish fed diets with decreasing FO and increasing PO nor from fish fed diets formulated with FO and a graded PO and CO blend. Yellowtail Kingfish may be able to be fed a formulated diet containing: 1) ∼25% dietary lipid level (2.12 g 100 g−1 of ƩLC n-3 PUFA) with up to 100% of the FO component replaced by PO; and 2) ∼25% dietary lipid level (2.12 g 100 g−1 of ƩLC n-3 PUFA) with up to 100% of the commercially used alternative lipid source (PO) replaced with CO without an apparent negative impact on any of the parameters measured in this study.

Replacement of fish oil by palm oil in diet for juvenile greenfin horse-faced filefish (Thamnaconus septentrionalis): Effects on growth performance, fatty acid composition, antioxidant capacity and inflammatory responses

This study investigated the effects of replacing dietary fish oil (FO) with palm oil (PO) on the growth performance, proximate composition, antioxidant capacity, and inflammatory responses of juvenile greenfin horse-faced filefish, Thamnaconus septentrionalis. Five isonitrogenous and isocaloric diets with varying levels of PO inclusion (0%, 25%, 50%, 75%, and 100%) were prepared, and each diet was administered in triplicate to juvenile fish for 10 weeks. Results indicated that moderately partial replacement of FO did not result in detrimental effects whereas complete or high-level replacement of FO compromised survival, growth, and feed utilization. Moderate PO inclusion slightly increased the antioxidant capacity. However, this effect was significantly impaired by high levels of dietary PO. The moisture and ash content of whole fish showed an increasing trend, while crude lipid and crude protein content tended to decline, showing significant linear response. Dietary PO appeared to affect triglyceride synthesis, albeit with minimal impact on the lipid content of the liver. Fatty acid compositions in both liver and muscle tissues were linearly correlated with dietary FA profiles, with fish liver being more reflective of dietary fatty acid composition than muscle tissue. ARA, EPA and DHA were selectively retained in the muscle tissue, whereas EPA retention was significantly reduced in the liver tissue with the gradual replacement of FO. High levels of PO inclusion in the diet resulted in elevated gene expression related to hepatic inflammation, including TLRs, MyD88 and TNFa. In conclusion, palm oil could potentially serve as an alternative to fish oil in the diet for juvenile T. septentrionalis, with up to 50% substitution without deteriorating growth performance, n-3 LC-PUFA deposition in muscle, and health status of juvenile greenfin horse-faced filefish.

Effects of dietary fish oil replacement with rice bran oil on growth performance, serum biochemical index, antioxidant capacity, lipid metabolism and inflammatory response of large yellow croaker (Larimichthys crocea) juveniles

Fish oil (FO) replacement has become a top priority with the increasing growth of aquaculture and the decline of FO production. Dietary rice bran oil (RBO) has been marked with good application prospects and development potential in humans and terrestrial animals. Hence, this study was geared towards ascertaining the effects of replacing dietary FO with RBO in fish feeds. In this study, a 74-day feeding trial was conducted with large yellow croaker (Larimichthys crocea) juveniles to ascertain the effects of dietary FO replaced by different levels (0%, 25%, 50%, 75% and 100%) of RBO. Each diet was randomly fed to triplicate groups of large yellow croaker juveniles (120 fish per group) with an initial mean body weight of 13.02 ± 0.02 g. Fish fed with dietary RBO 25% showed significantly higher final body weight, weight gain rate, specific growth rate, and feed intake compared to other treatments. Also, fish fed diets with RBO showed significantly higher antioxidant capacity compared to the control. Interestingly, fish fed with RBO 25% diet showed a significantly improved serum lipid profile when compared to the control. Moreover, the hepatic mRNA expression of sterol regulatory element-binding protein-1 (srebp-1), and fatty acid synthase (fas) was significantly upregulated in RBO 25% replacement, while peroxisome proliferator-activated receptor α (pparα), was significantly suppressed in fish fed RBO 100% compared to the control. Furthermore, fish fed RBO 100% had significantly increased Interleukin-1β (il-1β), Tumour necrosis factor-α (tnf-α), and Interferon-γ (ifn-γ), and significantly decreased transcript levels of Interleukin-10 (il-10). Therefore, the results of the present study showed that RBO could promote the performance of large yellow croaker juveniles, by improving the growth indexes, serum biochemical properties, antioxidant capacity, and alleviating liver inflammation.

Effects of oxidized fish oil diet supplemented with tea polyphenols on intestinal health and liver metabolism of spotted sea bass (Lateolabrax maculatus)

In this study, the effects of oxidized fish oil diet supplemented with tea polyphenols (TP) on the intestinal health and liver metabolism of spotted sea bass (Lateolabrax maculatus) were investigated. Five kinds of diets were designed. They were the negative control (NC) group without antioxidants and TP, the positive control (PC) group with antioxidants, three experimental groups were supplemented with 0.05 %, 0.10 %, and 0.15 % TP (TP1, TP2, and TP3). The fish with a mean body weight of 11.43±0.02 g was fed on five diets for 56 days. The results showed that TP1 improved lipase (LPS) activity. The intestinal superoxide dismutase (SOD) activity of TP1 was significantly higher than that of the NC group and was not different from that of the PC group. Histological observation of the intestine showed that the height of the intestinal villus was significantly increased and the width of the intestinal villus was significantly decreased in TP1, while the muscular thickness layer did not change significantly. Furthermore, inflammatory symptoms were present in the intestines of all groups, with improvements observed in TP1 and TP3. By intestinal microbial analysis, the results showed that the ACE and Chao1 indexes of TP1 were significantly higher than those of the NC and PC groups, and the Shannon and Simpson indexes were significantly lower than those of the NC and PC groups. Regarding the structure of the microbiome community, there were a lot more Fusobacteriota in TP2 and TP3 at the phylum level, and there were a lot more Cetobacterium at the genus level. The metabolomic analysis of TP1's liver showed that it controls the metabolism of amino acids, nucleotides, cofactors, vitamins, energy, and carbohydrates. The results showed that adding TP to the oxidized fish oil diet enhanced the intestinal health and liver metabolism of spotted sea bass.

Maternal consumption of fish oil protected breast-fed piglets against Escherichia coli lipopolysaccharide-induced damage through reshaping of intestinal fatty acids profile.

It has been well documented that n-3 polyunsaturated fatty acids (n-3 PUFA) can alleviate inflammation caused by Escherichia coli (E. coli) lipopolysaccharides (LPS), the etiologic agents that causing yellow or white dysentery in young pigs. However, it remains unclear whether the increase in n-3 PUFA availability could enhance the ability of nursery pigs to resist invasion by E. coli. LPS. Twenty-four 21-day-old female piglets, each two of them from the same sow fed the beef tallow (BT) or fish oil (FO) diets, were allocated into four treatment groups: BT-CON, piglets from the BT-fed sows and intraperitoneally injected with saline (9 g/L); BT-LPS, piglets from the BT-fed sows and injected with LPS (100 μg/kg body weight); FO-CON, piglets from the FO-fed sows and injected with saline; FO-LPS, piglets from the FO-fed sows and injected with LPS. Following 2 h of LPS challenge, the magnitudes of increase in body temperature approached to a marked (p < 0.01) difference between the BT-CON and BT-LPS piglets, whereas the dramatic (p < 0.01) difference between the FO-CON and FO-LPS piglets was only observed at 4 h post LPS challenge. The body temperature averaged across the time points evaluated was about 0.2°C lower (p < 0.05) in the FO group than in the BT group. The FO group had lower (p < 0.05) mean corpuscular hemoglobin concentration, lower increase in serum interleukin (IL)-1β (p < 0.10) and IL-8 (p < 0.05) levels, higher (p < 0.01) serum albumin concentration, and higher (p = 0.10) ratios of jejunum villus height to crypt depth than the BT group. The FO group had much higher (p < 0.0001) ileal content of C20:5n3, C24:0, and C22:6n3, which were 2-4 times the content of the BT group. LPS challenge resulted in decreased (p < 0.05) intestinal C20:1 and C20:5n3 content, and the decrease (p < 0.05) in intestinal C20:3n6 and C24:1 content was observed in the BT-LPS piglets rather than in the FO-LPS piglets. Taken together, this study indicated that maternal consumption of fish oil protected breast-fed piglets against E. coli LPS-induced damage through reshaping of intestinal fatty acids profile, which sheds new light on the development of nutritional strategies to enhance the ability of young pigs to resist E. coli invasion.

Effects of dietary soybean lecithin on growth, tissue fatty acid composition, and gonadal development in the hermaphroditic rice field eel (Monopterus albus)

This study investigates the effects of soybean lecithin (SL) on the growth, fatty acid composition, lipid metabolism, and gonadal development of rice field eels. Fourteen-month-old eels were fed either fish oil diets or varying levels of dietary soybean lecithin (0 %, 1.4 %, and 2.8 %) for 10 weeks. Dietary SL had no significant impact on growth, whereas 1.4 % SL led to a significant decrease in moisture content and an increase in crude protein content in eels. The content of both saturated and polyunsaturated fatty acids increased in muscles fed the higher SL diet, with a concurrent decline in saturated fatty acids and an increase in polyunsaturated fatty acids detected in the liver. The expression levels of genes related to lipid synthesis, including accα and PPARγ, and genes related to polyunsaturated fatty acid synthesis, such as pla2g4a, fad2 and scd, were significantly increased in the liver of eels fed with 1.4 % SL diet. SL supplementation enhances lipid transport and antioxidant capacity in the liver, reduces fat deposition, and protects the liver from damage. Hepatosomatic index of fish in the SL1.4 % and SL2.8 % groups decreased. Supplementation of the diet with 1.4 % SL led to a significant decrease in the content of saturated fatty acids and an increase in the content of polyunsaturated fatty acids in the gonads, with a significant increase in arachidonic acid levels. The gonadosomatic index also increased with increasing dietary SL content. Rice field eels fed diets containing SL exhibited elevated serum levels of E2, delayed ovary-to-testis transition, and a preference for retaining the female state. In conclusion, dietary supplementation with SL increased the proportion of highly unsaturated fatty acids in the tissues, enhanced lipid metabolism in the liver, and improved antioxidant capacity. Furthermore, SL supplementation has been demonstrated to promote ovarian development and delay sex reversal in rice field eels.

Replacing Fishmeal and Fish Oil with Complex Protein and Canola Oil: Effect on Organoleptic and Nutritional Quality of Triploid Rainbow Trout (Oncorhynchus mykiss).

A twelve-week feeding experiment was undertaken to explore the impact of substituting dietary fish meal (FM) and fish oil (FO) with complex protein (CP) and canola oil (CO) in the diet of triploid rainbow trout on the quality of their fillets. The control diet (F100) contained FM (60%) and FO (18.6%) as the main protein and lipid sources. Based on this, 50% and 100% of FM and FO were substituted by CP and CO and they were named as F50 and F0, respectively. The results showed that there were no significant differences in the specific growth rates, condition factors, gutted yields, fillet yields and yellowness values as the substitution levels increased (p > 0.05). The F50 treatment obtained the highest values of fillet springiness and chewiness, improved the umami and bitter taste of the fillets by increasing the contents of inosine-5'-monophosphate and histidine, and increased lipid, protein, C18: 1n-9 and C18: 2n-6 contents (p < 0.05). The F0 treatment obtained the highest values of fillet hardness and pH, attenuated the sweet taste of the fillets by decreasing the content of glycine, and decreased the contents of EPA and DHA (p < 0.05). Both F50 and F0 treatments could increase the redness value, decrease the lightness and hue values of fillets, and increase the odor intensity, resulting in the typical fillet odors of green, fatty, orange and fishy (p < 0.05). In general, 50% and 100% of FM and FO substitution did not affect the growth of trout, but it did affect quality. Compared to the F100 treatment, the fillet quality of the F0 treatment was similar to the F50 treatment and could improve the appearance and odor intensity of the fillets. However, the difference was that the F50 treatment increased the springiness, umami, bitterness and lipid nutritional value of the fillets, but the F0 treatment increased the hardness, decreased the sweetness, and decreased the lipid, EPA and DHA contents of the fillets.

Histology and transcriptomic analysis reveal effects of dietary fish oil and soybean oil on lipid absorption and immune inflammation in the foregut of adult female spotted scat (Scatophagus argus)

The foregut is the main site of lipid absorption in fish, but the effect of different lipid sources on the foregut lipid absorption and metabolism in adult female spotted scat is still unclear. In this experiment, adult female spotted scat (length = 19.48 ± 1.13 cm, weight = 242.83 ± 50.90 g) were fed two iso-nitrogenous (45 % crude protein) and iso-lipidic (12.5 % crude lipid) diets configured with either 8 % fish oil (FO) or 8 % soybean oil (SO) for 60 days. Histological observations, serum measurements and transcriptome sequencing were used to investigate the effects of the oil sources on the foregut. Histological observation showed that the foregut folds of the SO group were shorter and narrower than those of the FO group, and nuclear vacuolation and villous atrophy were observed in the intestinal cells of fish in the SO group, indicating an inflammatory reaction. Both serum triglyceride and total cholesterol levels were significantly higher in the FO group than in the SO group. Transcriptome analysis revealed 1355 differentially expressed genes between the FO and SO groups. Genes related to lipid metabolism (adipor2 and creb3l3) and cholesterol absorption and efflux (npc1l1 and sphk2) were up-regulated, whereas genes related to fatty acid synthesis and transport (fad1 and mfsd2ab) were down-regulated in the FO group. Circadian rhythm related genes ciart and nfil3, which are also involved in lipid metabolism, were up- and down-regulated, respectively in the FO group. The immune-related genes steap4, ddit4 and cldn6 which can inhibit inflammation, were up-regulated in the FO group, whereas pro-inflammation gene rnf225 was up-regulated in the SO group. In conclusion, compared with SO, FO may enhance the lipid absorption and reduce the inflammatory response in the foregut of the spotted scat. The results of this study provide a reference for the selection of dietary oil sources for adult female spotted scat.

Dietary menhaden fish oil supplementation suppresses lipopolysaccharide-induced neuroinflammation and cognitive impairment in diabetic rats

Context Menhaden fish oil (FO) is widely recognized for inhibiting neuroinflammatory responses and preserving brain function. Nevertheless, the mechanisms of FO influencing brain cognitive function in diabetic states remain unclear. Objective This study examines the potential role of FO in suppressing LPS-induced neuroinflammation and cognitive impairment in diabetic animals (DA). Materials and methods Thirty male Wistar rats were divided into 5 groups: i) DA received LPS induction (DA-LPS); ii) DA received LPS induction and 1 g/kg FO (DA-LPS-1FO); iii) DA received LPS induction and 3 g/kg FO (DA-LPS-3FO); iv) animals received normal saline and 3 g/kg FO (NS-3FO) and v) control animals received normal saline (CTRL). Y-maze test was used to measure cognitive performance, while brain samples were collected for inflammatory markers and morphological analysis. Results DA received LPS induction, and 1 or 3 g/kg FO significantly inhibited hyperglycaemia and brain inflammation, as evidenced by lowered levels of pro-inflammatory mediators. Additionally, both DA-LPS-1FO and DA-LPS-3FO groups exhibited a notable reduction in neuronal damage and glial cell migration compared to the other groups. These results were correlated with the increasing number of entries and time spent in the novel arm of the Y-maze test. Discussion and conclusion This study indicates that supplementation of menhaden FO inhibits the LPS signaling pathway and protects against neuroinflammation, consequently maintaining cognitive performance in diabetic animals. Thus, the current study suggested that fish oil may be effective as a supporting therapy option for diabetes to avoid diabetes-cognitive impairment.

Dietary omega-3 fatty acids modulate the production of platelet-derived microvesicles in an in vivo inflammatory arthritis model.

The aim of this study was to investigate the effects of different ω-3 polyunsaturated fatty acid (PUFA) enriched diets, including a novel renewable plant source of ω-3 fatty acids (Buglossoides arvensis), on the development and progression of rheumatoid arthritis (RA). RA was induced in mice consuming experimental diets using the K/BxN model. The experimental diets consisted of either a western control diet (control), diets containing B. arvensis oil or fish oil. The effects of the diets on platelets, platelet microvesicles (PMVs), and inflammatory markers such as clinical index, ankle thickness and cytokine/chemokine release were measured. While ω-3 PUFA-enriched diets did not prevent the development of arthritis in the K/BxN model, a significant decrease in ankle swelling was observed compared to the control group. Platelets isolated from mice consuming either low content of B. arvensis oil or fish oil diets exhibited significantly decreased PMVs production compared to mice consuming the control diet. Our study provides insight into the contribution of ω-3 PUFA supplementation in modulating the pro-inflammatory phenotype of platelets in RA pathology. Furthermore, our study suggests that low concentrations of dietary B. arvensis oil may have similar anti-inflammatory potential seen with dietary fish oil supplementation.

Dietary lipid sources affect growth performance, lipid deposition, antioxidant capacity and inflammatory response of largemouth bass (Micropterus salmoides)

The present study explored the effects of different lipid sources on growth performance, lipid deposition, antioxidant capacity, inflammatory response and disease resistance of largemouth bass (Micropterus salmoides). Four isonitrogenous (crude protein 50.46 %) and isolipidic (crude lipid 11.12 %) diets were formulated to contain 7 % of different oil sources including fish oil (FO) (control), soybean oil (SO), linseed oil (LO) and coconut oil (CO). Largemouth bass with initial body weight of 36.0 ± 0.2 g were randomly distributed into 12 tanks, with 30 fish per tank and 3 tanks per treatment. The fish were fed with the experiment diets twice daily for 8 weeks. The results indicated that the weight gain of largemouth bass fed the FO diet was significantly higher than that of fish fed the LO and CO diets. The liver crude lipid content in FO group was significantly higher than other groups, while the highest liver triglyceride content was showed in SO group and the lowest was detected in LO group. At transcriptional level, expression of lipogenesis related genes (pparγ, srebp1, fas, acc, dgat1 and dgat2) in the SO and CO group were significantly higher than the FO group. However, the expression of lipolysis and fatty acids oxidation related genes (pparα, cpt1, and aco) in vegetable oils groups were significantly higher than the FO group. As to the antioxidant capacity, vegetable oils significantly reduced the malondialdehyde content of largemouth bass. Total antioxidant capacity in the SO and LO groups were significantly increased compared with the FO group. Catalase in the LO group was significantly increased compared with the FO group. Furthermore, the ER stress related genes, such as grp78, atf6α, atf6β, chop and xbp1 were significantly enhanced in the vegetable oil groups compared with the FO group. The activity of serum lysozyme in vegetable oil groups were significantly higher than in FO group. Additionally, the relative expression of non-specific immune related genes, including tlr2, mapk11, mapk13, mapk14, rela, tgf-β1, tnfα, 5lox, il-1β and il10, were all significantly increased in SO and CO groups compared to the other groups. In conclusion, based on the indexes including growth performance, lipid deposition, antioxidant capacity and inflammatory response, SO and LO could be alternative oil sources for largemouth bass.

Aurantiochytrium sp. and Nannochloropsis spp. meals as substitutes for fish oil in practical diets for Pacific white shrimp Penaeus vannamei

This study aimed to evaluate the use of microalgae meal (Aurantiochytrium sp. and Nannochloropsis spp.) as a substitute for fish oil in the diet of shrimp Penaeus vannamei reared in a clear water system. In the diet of these animals, the concentration of fish oil decreased as microalgae meal was inserted, and these were used in five different substitutions: 0, 25, 50, 75, and 100%. The treatments were carried out in triplicate, and after 49 days of cultivation, the zootechnical parameters and the composition of fatty acids in the animals' muscles were analyzed. In zootechnical performance, the shrimp obtained an average final weight of 16.59 ± 0.3 g, and the growth was approximately 1.89 ± 0.30 g week-1. In addition, feed conversion was, on average, 1.47 ± 0.28, and survival was greater than 97%. However, no significant difference was observed in these parameters. Regardless of the levels of fish oil replacement by microalgae meal, the composition of fatty acids in the shrimp muscle was ensured, as well as their quantity within groups, such as n-3 and n-6 polyunsaturated fatty acids. Thus, with the results obtained in the present study, it is suggested that it is possible to formulate a high-performance diet without any ingredients of marine origin (fish oil or fish meal), contributing to aquaculture's sustainability.

Effect of dietary fish oil sparing with blended vegetable oils on growth, fatty acid composition and lipid-metabolism-related genes expression in juvenile rainbow trout (Oncorhynchus mykiss)

Abstract A nutritional study was conducted to evaluate the influence of dietary fish oil (FO) sparing by using a mixture of vegetal oils (VO) on rainbow trout (Oncorhynchus mykiss) juveniles (30.0 g). A basal diet was supplemented with the experimental oils at a 10% level, including FO (FO diet), a blend of VO (sunflower, soybean and rapeseed oils with a 1:1:1 ratio), and a mixture (1:1 ratio) of FO and the blends of VO (MIX). In a raceway system, 450 fish were stocked in nine rectangular concrete tanks (50 fish/ tank−1). Three experimental diets, with three replicates each, were offered to fish up to visual satiation for eight weeks. Growth performance did not change among groups (P&gt;0.05). The highest and lowest proportions of n-3 polyunsaturated fatty acids (PUFA), n-3 long chain-PUFA, especially docosahexaenoic acid, and n-3/n-6 PUFA ratio were in the whole body of FO and the VO groups, respectively (P&lt;0.05). Serum catalase and glutathione peroxidase activities in VO group were higher than others. Serum superoxide dismutase activity in fish fed FO and VO diets was higher than MIX group (P&lt;0.05). VO group had higher serum lysozyme, alternative complement pathway, and total immunoglobulin levels than other experimental groups. MIX group had highest serum triglyceride, cholesterol, and low-density lipoproteins. Serum high-density lipoproteins, aspartate aminotransferase, and alanine aminotransferase levels in VO treatment were in the lowest level compared to others (P&lt;0.05). The highest relative transcription levels of fatty acid synthase, delta-6 fatty acyl desaturase, and apolipoprotein b-100 genes were in the liver of fish fed the MIX diet. The relative transcription level of the fatty acid-binding protein1 gene did not change (P&gt;0.05). In summary, the results of this study revealed that dietary FO sparing with VO did not adversely affect the growth and health indices of rainbow trout; nevertheless, it had adverse effects on its nutritional values by reducing whole-body n-3 LC-PUFA content.

N-3 enriched Fish oil diet enhanced intestinal barrier integrity in broilers after Eimeria infection

Coccidiosis caused by Eimeria spp. results in substantial economic losses in the poultry industry. The objective of this study was to investigate the effects of dietary supplementation with n-3 polyunsaturated fatty acids-enriched fish oil on growth performance, intestinal barrier integrity, and intestinal immune response of broilers challenged with Eimeria spp. A total of 576 14-day-old broilers were randomly assigned in a completely randomized design with a 3×2 factorial arrangement, comprising two diets supplemented with either 5% fish oil or 5% soybean oil, and three Eimeria spp. infection levels: a non-challenge control, a low dose of Eimeria challenge, and a high challenge dose. The results of the study revealed significant interactions between diet and Eimeria challenge to parameters of gut barrier integrity and feed intake. A significant interaction was observed in feed intake between 5-8 days post-infection (DPI), where the fish oil groups exhibited a higher amount of feed intake compared to the soybean oil diet groups after coccidiosis infection. The effects of the fish oil diet resulted in enhanced gut barrier integrity, as evidenced by a trend of decreased gastrointestinal leakage and a lower mean of small intestine lesion scores after Eimeria challenge. Additionally, significant interactions were noted between Eimeria spp. challenge and diet regarding jejunal crypt depth. The positive impact of the fish oil diet was particularly noticeable with the high Eimeria challenge dose. Overall, these findings underscore the relationship between the fish oil diet and Eimeria challenge on broiler chicken intestinal health. Dietary supplementation of fish oil has the potential to maintain small intestine barrier integrity with severe Eimeria infection conditions.