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To investigate the potential of ferulic acid (FA) in attenuating the deleterious effects of oxidized fish oil (OF) on Macrobrachium nipponense, four experimental diets were formulated: 3% fresh fish oil (CT group, peroxide value: 2.2 mmol/kg), 3% oxidized fish oil (OF group, peroxide value: 318 mmol/kg), and 3% OF with an additional 160 and 320 mg/kg of FA (OF+FA160 group and OF+FA320 group, respectively). M. nipponense (initial weight: 0.140 ± 0.015 g) were randomly divided into four groups with six replicates (60 individuals per replicate) and reared for a period of 10 weeks. The results showed that the OF treatments significantly reduced the growth performance, the expression of antioxidant genes in the hepatopancreas, the levels of low-density lipoprotein cholesterol, and the gene expression levels of ACC, FAS, FABP10, ACBP, G6PDH, and SCD in the hepatopancreas (p < 0.05). OF supplementation significantly increased the levels of high-density lipoprotein cholesterol in hemolymph and the gene expression levels of CPT1 (p < 0.05). Addition of FA to the OF group significantly increased total bile acids (p < 0.05). In addition, it was found by Oil Red staining that the proportion of lipid droplets was significantly increased in the OF group (p < 0.05). However, the lipid droplets were alleviated by FA supplementation in the diet. OF was found to significantly reduce the diversity of intestinal microbiota by 16S rDNA sequencing and significantly increase the Firmicutes/Bacteroidetes (F/B) ratio (p < 0.05). Functional analysis of gut microbiota also showed that OF reduced lipolysis and led to fat deposition, which is related to gut microbiota. However, this study found that the composition of the gut microbiome of M. nipponense was changed by the addition of FA in the diet, including an increase in the abundance of Ruminococcaceae UCG-005 and Lachnospiraceae, a reduction in the F/B ratio, and an improvement in lipid metabolism. In conclusion, the OF induced oxidative stress, disturbed the balance of intestinal microbiota, promoted lipid accumulation, and caused disorders of lipid metabolism in M. nipponense by increasing lipid synthesis and reducing β-oxidation. However, the results of this study highlighted the potential of FA supplementation to modulate intestinal microbial composition, promote bile acid production, and activate genes related to lipid metabolism in the hepatopancreas, ultimately leading to a reduction in lipid deposition in M. nipponense. [ABSTRACT FROM AUTHOR]

Fish oil is the primary oil source in aquafeeds, but is susceptible to oxidation during production and storage, thereby leading to oxidative stress in fish. Pyrroloquinoline quinone (PQQ) is a novel redox cofactor that possesses numerous pharmacological properties. Hence, the aim of this study was to evaluate whether dietary PQQ supplementation could alleviate stress response of yellow catfish (Tachysurus fulvidraco) caused by oxidized fish oil. Fish were fed four experimental diets containing fresh and oxidized fish oil either with or without PQQ (0 or 5 mg kg−1) supplementation for 8 weeks. Results revealed that dietary oxidized fish oil significantly decreased growth performance of fish, fat content in whole-body, and the immunological parameters. Also, it significantly elevated aspartate aminotransferase and alanine aminotransferase activities, as well as the levels of total cholesterol, triglyceride, and glucose in serum. Meanwhile, oxidized fish oil decreased antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase) and total antioxidant capacity but increased MDA level in serum. However, the addition of PQQ in the oxidized fish oil diet could overcome the negative impacts of oxidized fish oil on yellow catfish and normalise the detected parameters nearly to the control values. Taken together, long-term feeding of oxidized fish oil diet destroyed liver, disordered lipid metabolism, diminished nonspecific immunity as well as caused oxidative stress, and eventually resulted in growth retardation of yellow catfish, whereas dietary PQQ supplementation had a significant ameliorative role in adverse effects induced by dietary oxidized fish oil, and therefore, may be recommended for use in aquaculture to prevent oxidized lipid.

Aims: Studies demonstrated that oxidized fish oil (OFO) promoted oxidative stress and induced mitochondrial dysfunction and lipotoxicity, which attenuated beneficial effects of fish oil supplements in the treatment of nonalcoholic fatty liver disease (NAFLD). The current study was performed on yellow catfish, a good model to study NAFLD, and its hepatocytes to explore whether selenium (Se) could alleviate OFO-induced lipotoxicity via the inhibition of oxidative stress and determine its potential mechanism. Results: The analysis of triglycerides content, oxidative stress parameters, and histological and transmission electronic microscopy observation showed that high dietary Se supplementation alleviated OFO-induced lipotoxicity, oxidative stress, and mitochondrial injury and dysfunction. RNA-sequencing and immunoblotting analysis indicated that high dietary Se reduced OFO-induced decline of peroxisome-proliferator-activated receptor alpha (Pparα) and ubiquitin-specific protease 4 (Usp4) protein expression. High Se supplementation also alleviated OFO-induced reduction of thioredoxin reductase 2 (txnrd2) messenger RNA (mRNA) expression level and activity. The txnrd2 knockdown experiments revealed that txnrd2 mediated Se- and oxidized eicosapentaenoic acid (oxEPA)-induced changes of mitochondrial reactive oxygen species (mtROS) and further altered Usp4 mediated-deubiquitination and stabilization of Pparα, which, in turn, modulated mitochondrial fatty acid β-oxidation and metabolism. Mechanistically, Usp4 deubiquitinated Pparα and ubiquitin-proteasome-mediated Pparα degradation contributed to oxidative stress-induced mitochondrial dysfunction. Innovation: These findings uncovered a previously unknown mechanism by which Se and OFO interacted to affect lipid metabolism via the Txnrd2-mtROS-Usp4-Pparα pathway, which provides the new target for NAFLD prevention and treatment. Conclusion: Se ameliorated OFO-induced lipotoxicity via the inhibition of mitochondrial oxidative stress, remodeling of Usp4-mediated deubiquitination, and stabilization of Pparα. Antioxid. Redox Signal. 40, 433–452. [ABSTRACT FROM AUTHOR]

To investigate the potential of ferulic acid (FA) in attenuating the deleterious effects of oxidized fish oil (OF) on Macrobrachium nipponense, four experimental diets were formulated: 3% fresh fish oil (CT group, peroxide value: 2.2 mmol/kg), 3% oxidized fish oil (OF group, peroxide value: 318 mmol/kg), and 3% OF with an additional 160 and 320 mg/kg of FA (OF+FA160 group and OF+FA320 group, respectively). M. nipponense (initial weight: 0.140 ± 0.015 g) were randomly divided into four groups with six replicates (60 individuals per replicate) and reared for a period of 10 weeks. The results showed that the OF treatments significantly reduced the growth performance, the expression of antioxidant genes in the hepatopancreas, the levels of low-density lipoprotein cholesterol, and the gene expression levels of ACC, FAS, FABP10, ACBP, G6PDH, and SCD in the hepatopancreas (p < 0.05). OF supplementation significantly increased the levels of high-density lipoprotein cholesterol in hemolymph and the gene expression levels of CPT1 (p < 0.05). Addition of FA to the OF group significantly increased total bile acids (p < 0.05). In addition, it was found by Oil Red staining that the proportion of lipid droplets was significantly increased in the OF group (p < 0.05). However, the lipid droplets were alleviated by FA supplementation in the diet. OF was found to significantly reduce the diversity of intestinal microbiota by 16S rDNA sequencing and significantly increase the Firmicutes/Bacteroidetes (F/B) ratio (p < 0.05). Functional analysis of gut microbiota also showed that OF reduced lipolysis and led to fat deposition, which is related to gut microbiota. However, this study found that the composition of the gut microbiome of M. nipponense was changed by the addition of FA in the diet, including an increase in the abundance of Ruminococcaceae UCG-005 and Lachnospiraceae, a reduction in the F/B ratio, and an improvement in lipid metabolism. In conclusion, the OF induced oxidative stress, disturbed the balance of intestinal microbiota, promoted lipid accumulation, and caused disorders of lipid metabolism in M. nipponense by increasing lipid synthesis and reducing β-oxidation. However, the results of this study highlighted the potential of FA supplementation to modulate intestinal microbial composition, promote bile acid production, and activate genes related to lipid metabolism in the hepatopancreas, ultimately leading to a reduction in lipid deposition in M. nipponense.

An eight-week feeding trial was conducted to elucidate the effects of diets containing oxidized fish oil (OFO) and/or spoiled fish meal (SFM) supplemented with various contents of vitamins E (VE: 100 and 200 mg/kg) and C (VC: 200 and 400 mg/kg) on some selected physiological parameters of juvenile rainbow trout, Oncorhynchus mykiss. The growth indices were affected by OFO and SFM-contained diets; the lowest values were observed in those fish raised on diet containing OFO and high levels of the vitamins. In all experimental groups, the hematological parameters (erythrocytes, leukocytes, hematocrit, and hemoglobin) were increased compared to the control group, and higher values were recorded in group fed OFO+VE (200 mg/kg) +VC (400 mg/kg)-supplemented diet (P

Sulforaphane (SFN) is an antioxidant. Unsaturated fatty acids are rich in fish oil, and they are indispensable fatty acids for aquatic animals to grow and reproduce. However, fish oil is easily oxidized, which could have adverse effects on aquatic animals. In this study, Litopenaeus vannamei was divided into four groups: fresh fish oil group (control group), oxidized fish oil group (OFO group), OFO plus low-concentration SFN group (OFO + SL group), and OFO plus high-concentration SFN group (OFO + SH group). A 28-day experiment was conducted, and the antioxidant capacity, inflammation, autophagy, and pathological characteristics were investigated to explore whether SFN could protect L. vannamei from oxidative stress induced by OFO. Results showed that OFO significantly increased the contents of MDA in hepatopancreas, muscle and serum, while high concentrations of SFN significantly decreased the MDA compared with the OFO group (P

Coenzyme Q10 (CoQ10) is a powerful antioxidant that is gradually being used in aquafeeds. Here, we examined the influence of oxidized fish oil and CoQ10 supplementation on intestinal microbiota of Micropterus salmoides at different growth stages. Three isonitrogenous and isoenergetic diets were formulated to contain 100% fresh fish oil (FFO), 100% oxidized fish oil (OFO) and OFO + 0.1% CoQ10 (QFO) and were fed to Micropterus salmoides (95 ± 0.60 g) for 70 days. Furthermore, three different growth stages (28-day, 49-day, 70-day) were selected to observe the dynamic changes of intestinal microbiota. The growth performance of fish fed QFO were significantly higher than that of fish fed OFO after a 70-day’s feeding. Intestinal microbial community of Micropterus salmoides was significantly affected by different growth stages more than diets. The abundance of phylum Proteobacteria showed an increasing trend, while the abundance of Firmicutes decreased with increased feeding time. Compared with OFO, diet supplemented with CoQ10 significantly increased the abundance of Firmicutes, and decreased Proteobacteria on the 28- and 70-day of feeding. When fish fed OFO and QFO, Simpson and Shannon indices significantly increased with increased feeding time from 28 to 70 days. Fish fed QFO significantly decreased the value of Bray-Curtis distance than those fed FFO on the 70-day of feeding. Moreover, Bray-Curtis distance showed an increased trend with increased feeding time. Notably, intestinal microbial functional prediction indicated that OFO suppressed amino acid metabolism, while long-term oral administration of CoQ10 could improve amino acid metabolism and detoxification of Micropterus salmoides. This study demonstrated that prolonged application of CoQ10 is needed to produce some beneficial effects to Micropterus salmoides.

This study aimed to investigate the effects of oxidized fish oil (OFO) on growth performance, intestinal health, and antioxidant function and to determine the minimum concentration of oxidized fish oil to cause irreversible damage to the intestinal tissue structure of zebrafish. A 30-day feeding trial on zebrafish (average weight 0.054 g) was conducted in triplicate groups of fish fed four test diets containing different concentrations of OFO: 0% OFO (OFF, blank control), 2% OFO (OF1), 4% OFO (OF2), and 6% OFO (OF3). The body weight gain (WG), specific growth rates (SGR), feed conversion ratio (FCR), survival rate (SR), and antioxidant function [glutathione peroxidase (GSH-PX), total superoxide dismutase (T-SOD), catalase (CAT), and malondialdehyde (MDA)] were recorded. The intestinal structure was observed at the end of the trial. After the 14-day experimental period, Final body weight (FBW), WG, and SGR decreased significantly with the increase in the concentration of feed OFO (P < 0.05), while FCR showed a downward trend. The activity of T-SOD decreased significantly, the activities of GSH-PX and CAT, and the MDA content increased significantly with the increase in the concentration of feed OFO (P < 0.05). The intestinal morphological damage score showed an upward trend with the increase in the concentration of OFO, and it was significantly higher in group OF2 and OF3 than in group OF1 (P < 0.05). After the 28-day test period, the experimental indexes and intestinal antioxidant function trends were the same as those on 14 days. The increased OFO concentration significantly increased the intestinal morphological injury score (P < 0.05). These results demonstrated that adding 4% OFO to the feed for 14 days could induce irreversible damage to the intestinal tissue structure, weaken the antioxidant function, and decrease the growth performance of zebrafish. [ABSTRACT FROM AUTHOR]

Effect of S-LA and R-LA on Serum Estrogen of Laying Hens under Oxidative Stress As shown in Figure 4, the serum estrogen content was not significantly different between the OFO group and the OFO group ( I p i > 0.05). R- Is Superior to S-Form of -Lipoic Acid in Anti-Inflammatory and Antioxidant Effects in Laying Hens S-form of -lipoic acid, R-form of -lipoic acid, antioxidant, laying hen, oxidized fish oil Keywords: S-form of -lipoic acid; R-form of -lipoic acid; oxidized fish oil; antioxidant; laying hen EN S-form of -lipoic acid R-form of -lipoic acid oxidized fish oil antioxidant laying hen N.PAG N.PAG 12 08/29/22 20220801 NES 220801 1. [Extracted from the article]

The objective of this study was to determine the effect of dietary taurine on lipid metabolism and liver injury in mice fed a diet high in oxidized fish oil. The ICR mice (six weeks old) were randomly assigned to six groups and fed different diets for 10 weeks: control (CON), normal plus 15% fresh fish oil diet (FFO), normal plus 15% oxidized fish oil diet (OFO), or OFO plus 0.6% (TAU1), 0.9% (TAU2) or 1.2% (TAU3) taurine. Compared to the CON group, OFO mice showed increased liver index, aspartate aminotransferase (AST) and malondialdehyde (MDA) levels in serum (p < 0.05). In addition, OFO mice had increased cholesterol (CHOL)/high-density lipoprotein cholesterol (HDL-C) and decreased HDL-C/low-density lipoprotein cholesterol (LDL-C) and n-6/n-3 polyunsaturated fatty acid (PUFA) ratio in serum (p < 0.05) compared with CON mice. Notably, dietary taurine ameliorated the liver index and AST and MDA levels in serum and liver in a more dose-dependent manner than OFO mice. In addition, compared to OFO mice, decreased levels of CHOL and ratio of CHOL/HDL-C and n-6 PUFA/n-3 PUFA in serum were found in TAU3-fed mice. Supplementation with TAU2 and TAU3 increased the relative mRNA expression levels of peroxisome proliferator-activated receptor α, adipose triglyceride lipase, lipoprotein lipase, hormone-sensitive lipase and carnitine palmitoyl transferase 1 in liver compared with the OFO group (p < 0.05). Moreover, impaired autophagy flux was detected in mice fed with the OFO diet, and this was prevented by taurine. These findings suggested that dietary taurine might provide a potential therapeutic choice against oxidative stress and lipid metabolism disorder. [ABSTRACT FROM AUTHOR]

Oxidized fish oil, as a harmful ingredient in feed, has a negative impact on aquatic animals. But the effect of oxidized fish oil on hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus), especially the intestinal flora, is not yet understood. In the current study, a 65-day raising experiment with diets containing 0 g/kg, 30 g/kg, 60 g/kg, and 90 g/kg oxidized fish oil was performed (called as R, L, M and H group respectively) to investigate the effects of oxidized fish oil on growth performance, whole body composition, serum biochemical index, intestinal digestive enzyme activities and microbiome composition in juvenile hybrid grouper. Oxidized fish oil inhibited growth performance of pearl gentian grouper. The Moisture, crude protein, and ash content in whole body increased as increasing dietary oxidized fish oil content. The vitamin E content and antioxidant enzyme activity in serum including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were significantly increased as the oxidized fish oil in the diet increased, but malondialdehyde (MDA) content in serum was significantly decreased. Meanwhile, the D-Lactate (D-LA) and interleukin-10 (IL-10) content in serum was promoted by oxidized fish oil, but interleukin-6 (IL-6) content was suppressed. Moreover, the intestinal digestive enzyme activities were promoted by oxidized fish oil. The oxidized fish oil reduced alpha diversity of intestinal bacteria. At the same time, oxidized fish oil changed the structure of grouper intestinal flora according to beta diversity and line discriminant analysis (LDA) effect size. In conclusion, oxidized fish oil inhibited growth performance, changed the composition of the body and caused oxidative stress and inflammation in the body, but it promoted the secretion of digestive enzymes in the intestine. More importantly, oxidized fish oil reduced the diversity of intestinal flora and changed the structure of intestinal flora.

Lipids are essential nutrients for animal. Oxidized lipid might induce injury stress for prawns. This study was conducted to evaluate the oxidized fish oil on growth, digestive enzymes activities, antioxidant system of giant freshwater prawn (Macrobrachium rosenbergii) post-larvae for 21 days with the initial body weight of 1.13 ± 0.04 mg. Three trial diets were with fed the basal diet (C), basal diet supplemented 4% fish oil (4F), basal diet supplemented 4% oxidized fish oil (4OF), respectively (feeding 0 d, 7 d and 14 d, denoted as T7, T14 and T21, respectively). The results showed that the final body weight (FBW) and weight gain ratio (WGR) was increased in the group of 4F and decreased in the group of 4OF. After feeding fish oil or oxidized fish oil, the proteinase activity of T14, T21 post-larvae in 4OF group was significantly higher than T7 post-larvae (P

Fish oil (FO) is an important source of lipid in functional food and aquafeeds. However, the harmful effects of oxidized fish oil (OFO) on host metabolism and reproductive health are not yet clear. In addition, lipoamide (LAM) has been widely studied as an agent for alleviating various diseases associated with oxidative disruption. Therefore, in the current study, to investigate the effects of LAM in alleviating OFO-induced decline in reproductive performance and oxidative damage to the oviduct in laying hens. We constructed a 1% fresh FO model, a 1% OFO model, and a LAM model with 1% OFO (OFO + LAM) added at 100 mg/kg to explore the antioxidant effect of LAM. Herein, these results were evaluated by breeding performance, immune responses, estrogen, and antioxidant indices of serum samples, as well as the number of follicles and antioxidant parameters of oviducts. From the results, compared with the FO group, OFO significantly decreased the egg-laying rate, increased the contents of total protein (TP) and inflammatory factors [tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-8, and interferon γ (INF-γ)], and reduced the concentrations of anti-oxidation [total antioxidant (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), glutathione (GSH), glutathione reductase (GR), catalase (CAT), and hydroxyl radical scavenging activity (HRSA)] in serum samples, as well as reduced the levels of anti-oxidation indexes in oviduct tissues (p < 0.05). Of note, the supplementation of LAM could significantly increase the laying performance, improve the levels of serum immunoglobulins (IgA, IgG, and IgM), serum estrogen [progesterone (P) and estradiol (E2)], and serum antioxidant parameters (T-AOC, T-SOD, GSH-Px, GSH, GR, CAT, and HRSA) and decrease the concentrations of serum inflammatory cytokines (TNF-α, IL-6, IL-8, and INF-γ) in laying hens following OFO administration (p < 0.05). In addition, LAM could dramatically increase the contents of antioxidant factors (p < 0.05) in oviducts and enhance the secretion capacity of the uterine part. Taken together, OFO caused host metabolic dysfunction, oxidative damage, uterine morphological abnormalities, and alterations of ovarian function. These results suggested that LAM administration could alleviate host metabolic dysfunctions and inflammatory damage, and then ameliorate oxidative damage in the oviduct induced by OFO, ultimately improving reproductive function.

The aim of the study was to investigate the effects of fresh fish oil (FFO) and oxidized fish oil (OFO) diets on the muscle quality of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu). Hybrid grouper were fed with diets containing 9% FFO or OFO for 60 days. Muscle sample were collected at 0, 30, and 60 days and the selected indexes of muscle were measured. Malondialdehyde (MDA), reactive oxygen species (ROS), total cholesterol (TC) and triglycerides (TG) in grouper muscle accumulated gradually with prolonged ingestion time, especially OFO group. Total saturated fatty acids (ΣSAFA) was significantly reduced and total polyunsaturated fatty acids (ΣPUFA) was significantly increased of muscle in FFO group; meanwhile, the muscle ΣSAFA and monounsaturated fatty acids (ΣMUFA) contents in the OFO group were significantly higher than those in the FFO group and the ΣPUFA (especially C22:5n3, C22:6n3) contents was significantly lower than that in the FFO group at 60 days. Consumption of OFO diet for 60 days reduced the diversity of volatile compounds, significantly reduced the content of total esters and increased the content of total aldehydes and total aromatics in grouper muscle. Furthermore, ingestion of OFO diet significantly reduced the mRNA expression of fraction growth factors and antioxidant genes in the muscle of grouper. In conclusion, the increasing MDA content in FO and the oxidative rancidity of PUFA can cause the deterioration of grouper quality and flavor due to oxidative muscle damage.

Fish oil oxidation can produce harmful substances, but the specific effects of oxidized fish oil on liver function in the hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus) are not yet clear. In the present study, hybrid grouper was fed diets containing 0, 3, 6, or 9% oxidized fish oil (referred to as the control, L, M, and H groups respectively) for 65 days to investigate its effects on liver physiology. Oxidized fish oil significantly decreased protein content in liver (P

The spleen is an important organ in the immune function of fish, and it is also important for hematogenesis and antibody and granulocyte production. However, the effect of oxidized fish oil on the spleen of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus) is unknown. In this study, hybrid groupers were fed with oxidized fish oil and the spleen index, antioxidant ability, histology and transcriptome were investigated. Oxidized fish oil did not affect the spleen index. Levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in the spleen were significantly increased as the amount of oxidized fish oil in the diet increased, but the vitamin E concentration was significantly decreased. The morphological organization of the spleen was damaged with increased oxidative stress. And the spleen reacted to oxidative stress by platelet activation, FOXO and notch signaling pathways, which involved amyloid beta precursor protein binding family B member 1 interacting protein (APBB1IP) gene, glucose-6-phosphatase (G6PC) gene, histone acetyltransferase p300 (EP300) gene, insulin gene and notch 2 gene. In conclusion, the oxidized fish oil caused oxidative stress and damaged its structure. Additionally, oxidized fish oil changed the transcription profile of the spleen.

This 10-week feeding experiment examined the effects of supplementing vitamin C (VC) and E (VE) in oxidized oil diets on growth, fatty acid composition, blood physiological indicators, innate immunity, antioxidant capacity, and liver and intestine histology of rainbow trout (Oncorhynchus mykiss). Four diets were produced including a fresh fish oil containing diet (FFO diet), an oxidized fish oil containing diet (OFO diet), and OFO diet supplemented with 500 mg kg–1 VC and 400 mg kg–1 VE (OFO+C500+E400 diet) or 1,000 mg kg–1 VC and 800 mg kg–1 VE (OFO+C1000+E800 diet). Four hundred and twenty fish averaging 46.9 ± 0.32 g were stocked into 12 tanks and fed the diets twice a day to visual satiety. The results showed no significant effect of OFO or vitamins supplementation on growth, feed intake and feed utilization (P > 0.05). The groups that received OFO and OFO+C1000+E800 diets had significantly (P < 0.05) lower hepatosomatic indices than the other groups. Muscle fatty acid composition showed decreased proportion of 15:0, 16:0, 16:1n-7, 16:2n-4, 18:1n-5, 18:2n-6 (linoleic acid) and total saturated fatty acids in OFO group. Whereas higher percentages of 20:3n-6 and 20:3n-3 were found in OFO group. In addition, the highest ratio of docosahexaenoic acid (DHA, 22:6n-3) to eicosapentaenoic acid (EPA, 20:5n-3) was detected in OFO+C500+E400 group. The highest serum triglyceride concentration was recorded in the OFO group. Serum aspartate aminotransferase activity increased in OFO and OFO+C1000+E800 groups compared to OFO+C500+E400 group. Furthermore, significantly higher alkaline phosphatase activity in blood was found in OFO and OFO+C500+E400 groups. Significantly lower serum lysozyme, antiprotease, superoxide dismutase, and catalase activities were recorded in OFO group compared to FFO and OFO+C500+E400 groups, and an opposite trend was observed for malondialdehyde concentration. Muscle VC and VE concentrations, and liver and intestine histology remained unaffected. To conclude, feeding diet containing oxidized oil with peroxide value of 182 meq kg–1 with/without VC and VE supplementation did not influence growth and tissue VC and VE concentrations of rainbow trout. However, supplementing 500 mg kg–1 VC and 400 mg kg–1 VE reversed the adverse effects of OFO on non-specific immune response and antioxidant capacity.

The development of single enantiomers with high efficiency and low toxic activity has become a hot spot for the development and application of drugs and active additives. The aim of the present study was to investigate the effectiveness of the application of α-lipoic acid with a different optical rotation to alleviate the inflammation response and oxidative stress induced by oxidized fish oil in laying hens. Sixty-four 124-week-old Peking Red laying hens were randomly allocated to four groups with eight replicates of two birds each. The normal group was fed basal diets supplemented with 1% fresh fish oil (FO), and the oxidative stress model group was constructed with diets supplemented with 1% oxidized fish oil (OFO). The two treatment groups were the S-form of the α-lipoic acid model with 1% oxidized fish oil (OFO + S-LA) and the R-form of the α-lipoic acid model with 1% oxidized fish oil (OFO + R-LA) added at 100 mg/kg, respectively. Herein, these results were evaluated by the breeding performance, immunoglobulin, immune response, estrogen secretion, antioxidant factors of the serum and oviduct, and pathological observation of the uterus part of the oviduct. From the results, diets supplemented with oxidized fish oil can be relatively successful in constructing a model of inflammation and oxidative stress. The OFO group significantly increased the levels of the serum inflammatory factor (TNF-α, IL-1β, IL-6, and IFN-γ) and the oxidative factor MDA and decreased the activity of the antioxidant enzyme (T-AOC, T-SOD, GSH-Px, GSH, and CAT) in the oviduct. The addition of both S-LA and R-LA significantly reduced the levels of serum inflammatory factors (TNF-α, IL-1β, IL-6, and IFN-γ), increased the activity of antioxidant indexes (T-AOC, T-SOD, GSH-Px, GSH, and CAT), and decreased the MDA contents in the serum and oviduct. Meanwhile, the supplementation of S-LA and R-LA also mitigated the negative effects of the OFO on the immunoglobulins (IgA and IgM) and serum hormone levels (P and E2). In addition, it was worth noting that the R-LA was significantly more effective than the S-LA in some inflammatory (IL-1β) and antioxidant indices (T-SOD, GSH, and CAT). Above all, both S-LA and R-LA can alleviate the inflammation and oxidative damage caused by oxidative stress in aged laying hens, and R-LA is more effective than S-LA. Thus, these findings will provide basic data for the potential development of α-lipoic acid as a chiral dietary additive for laying hens.

The objective of this study was to determine the effect of dietary taurine on lipid metabolism and liver injury in mice fed a diet high in oxidized fish oil. The ICR mice (six weeks old) were randomly assigned to six groups and fed different diets for 10 weeks: control (CON), normal plus 15% fresh fish oil diet (FFO), normal plus 15% oxidized fish oil diet (OFO), or OFO plus 0.6% (TAU1), 0.9% (TAU2) or 1.2% (TAU3) taurine. Compared to the CON group, OFO mice showed increased liver index, aspartate aminotransferase (AST) and malondialdehyde (MDA) levels in serum (p < 0.05). In addition, OFO mice had increased cholesterol (CHOL)/high-density lipoprotein cholesterol (HDL-C) and decreased HDL-C/low-density lipoprotein cholesterol (LDL-C) and n-6/n-3 polyunsaturated fatty acid (PUFA) ratio in serum (p < 0.05) compared with CON mice. Notably, dietary taurine ameliorated the liver index and AST and MDA levels in serum and liver in a more dose-dependent manner than OFO mice. In addition, compared to OFO mice, decreased levels of CHOL and ratio of CHOL/HDL-C and n-6 PUFA/n-3 PUFA in serum were found in TAU3-fed mice. Supplementation with TAU2 and TAU3 increased the relative mRNA expression levels of peroxisome proliferator-activated receptor α, adipose triglyceride lipase, lipoprotein lipase, hormone-sensitive lipase and carnitine palmitoyl transferase 1 in liver compared with the OFO group (p < 0.05). Moreover, impaired autophagy flux was detected in mice fed with the OFO diet, and this was prevented by taurine. These findings suggested that dietary taurine might provide a potential therapeutic choice against oxidative stress and lipid metabolism disorder.

Our previous study indicated that dietary xylooligosaccharide (XOS) supplementation improved feed efficiency, ileal morphology, and nutrient digestibility in laying hens. The objective of this study was to evaluate the mitigative effects of XOS on intestinal mucosal barrier impairment and microbiota dysbiosis induced by oxidized fish oil (OFO) in laying hens. A total of 384 Hy-Line Brown layers at 50 weeks of age were randomly divided into four dietary treatments, including the diets supplemented with 20 g/kg of fresh fish oil (FFO group) or 20 g/kg of oxidized fish oil (OFO group), and the OFO diets with XOS addition at 200 mg/kg (OFO/XOS200 group) or 400 mg/kg (OFO/XOS400 group). Each treatment had eight replicates with 12 birds each. The OFO treatment decreased (P < 0.05) the production performance of birds from 7 to 12 weeks of the experiment, reduced (P < 0.05) ileal mucosal secretory immunoglobulin A (sIgA) content, and increased (P < 0.05) serum endotoxin concentration, as well as downregulated (P < 0.05) mRNA expression of claudin-1 (CLDN1) and claudin-5 (CLDN5) in the ileal mucosa at the end of the experiment. Dietary XOS addition (400 mg/kg) recovered (P < 0.05) these changes and further improved (P < 0.05) ileal villus height (VH) and the villus height-to-crypt depth ratio (VCR). In addition, OFO treatment altered cecal microbial composition of layers, and these alterations were probably involved in OFO-induced ileal mucosal impairment as causes or consequences. Supplemental XOS remodeled cecal microbiota of layers fed the OFO diet, characterized by an elevation in microbial richness and changes in microbial composition, including increases in Firmicutes, Ruminococcaceae, Verrucomicrobia (Akkermansia), Paraprevotella, Prevotella_9, and Oscillospira, along with a decrease in Erysipelatoclostridium. The increased abundance of Verrucomicrobia (Akkermansia) had positive correlations with the improved ileal VH and ileal mucosal expression of CLDN1. The abundance of Erysipelatoclostridium decreased by XOS addition was negatively associated with ileal VH, VCR, ileal mucosal sIgA content, and the relative expression of zonula occludens-2, CLDN1, and CLDN5. Collectively, supplemental XOS alleviated OFO-induced intestinal mucosal barrier dysfunction and performance impairment in laying hens, which could be at least partially attributed to the modulation of gut microbiota.

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.

Our previous study indicated that dietary xylooligosaccharide (XOS) supplementation improved feed efficiency, ileal morphology, and nutrient digestibility in laying hens. The objective of this study was to evaluate the mitigative effects of XOS on intestinal mucosal barrier impairment and microbiota dysbiosis induced by oxidized fish oil (OFO) in laying hens. A total of 384 Hy-Line Brown layers at 50 weeks of age were randomly divided into four dietary treatments, including the diets supplemented with 20 g/kg of fresh fish oil (FFO group) or 20 g/kg of oxidized fish oil (OFO group), and the OFO diets with XOS addition at 200 mg/kg (OFO/XOS200 group) or 400 mg/kg (OFO/XOS400 group). Each treatment had eight replicates with 12 birds each. The OFO treatment decreased (P < 0.05) the production performance of birds from 7 to 12 weeks of the experiment, reduced (P < 0.05) ileal mucosal secretory immunoglobulin A (sIgA) content, and increased (P < 0.05) serum endotoxin concentration, as well as downregulated (P < 0.05) mRNA expression of claudin-1 (CLDN1) and claudin-5 (CLDN5) in the ileal mucosa at the end of the experiment. Dietary XOS addition (400 mg/kg) recovered (P < 0.05) these changes and further improved (P < 0.05) ileal villus height (VH) and the villus height-to-crypt depth ratio (VCR). In addition, OFO treatment altered cecal microbial composition of layers, and these alterations were probably involved in OFO-induced ileal mucosal impairment as causes or consequences. Supplemental XOS remodeled cecal microbiota of layers fed the OFO diet, characterized by an elevation in microbial richness and changes in microbial composition, including increases in Firmicutes , Ruminococcaceae , Verrucomicrobia (Akkermansia), Paraprevotella , Prevotella_9 , and Oscillospira , along with a decrease in Erysipelatoclostridium. The increased abundance of Verrucomicrobia (Akkermansia) had positive correlations with the improved ileal VH and ileal mucosal expression of CLDN1. The abundance of Erysipelatoclostridium decreased by XOS addition was negatively associated with ileal VH, VCR, ileal mucosal sIgA content, and the relative expression of zonula occludens-2, CLDN1 , and CLDN5. Collectively, supplemental XOS alleviated OFO-induced intestinal mucosal barrier dysfunction and performance impairment in laying hens, which could be at least partially attributed to the modulation of gut microbiota. [ABSTRACT FROM AUTHOR]

A study was conducted to characterize the effects of dietary oxidized fish oil on the growth performance, immunity and antioxidant status of genetically improved farmed tilapia (Oreochromis niloticus) and to determine the role of ferulic acid on the oxidative damage induced by the oxidized fish oil. The tilapia (13.73 ± 0.31 g) were fed four experimental diets containing untreated (peroxide value, POV: 2.2 meq/kg) and highly oxidized (POV: 120.6 meq/kg) fish oil either with or without ferulic acid (0 or 400 mg/kg) supplementation for 12 weeks. From the results, the oxidized fish oil treatments increased antioxidant enzyme activities and MDA values but decreased the weight gain and the immunological parameters in tilapia. Meanwhile, the serum biochemical indices were significantly affected by the oxidized fish oil. Besides, the addition of ferulic acid partially counteracted the free radical‐induced damage and improved the health status of tilapia. In conclusion, the oxidized fish oil may induce oxidative stress, destroy liver, dysregulate lipid metabolism as well as reduce non‐specific immunity, and eventually result in growth inhibition of tilapia. The ferulic acid supplementation partially offset the negative effects of the oxidized fish oil on tilapia. [ABSTRACT FROM AUTHOR]

Lipid content of a diet is very susceptible to oxidation, which has many negative effects on farmed animals. Therefore, this study studied the protective effect of L‐carnitine (LC) on fish body stimulated by oxidized fish oil (OFO) from lipid metabolism. Lipid content of the diet was replaced by OFO in 0, 100 and 400 meq/kg. L‐carnitine was added to the diet in two levels, 500 and 1,000 mg/kg, giving a total of seven experimental diets. A total of 735 healthy Rhynchocypris lagowski Dybowski with an initial weight of 4.48 ± 0.14 g after 2‐week adaptation randomly divided into 15 glass aquariums. Fish were fed satiated three times daily. After 8 weeks, biometry was done to evaluate growth performance, and hepatopancreas and muscle samples were taken for biochemical analysis. The result showed that feeding with OFO had negative growth. However, in fish received both OFO and LC, growth indices improved slightly (p >.05). Feeding with OFO and LC, the content of EPA, DHA and PUFA in the muscle of R. lagowski was significantly higher than that in the control group (p <.05), which reached the maximum value in the OFO100 + LC500 group. The content of SFA, MUFA, ∑n‐6 and PUFA in hepatopancreas increased significantly (p <.05), and the content of SFA reached the maximum in OFO100 + LC500 group. Feeding with OFO increased hepatopancreas total cholesterol, triacylglycerol, HDL/LDL ratio, FAS and ACCα that involved in lipid synthesis enzymes, while reduced HL and HSLα enzyme activity and gene expression that associated with lipid decomposition. Dietary LC moderated the effects of OFO on lipid metabolism. According to the result of the present study, it can be argued that feeding of R. lagowski with OFO has negative effects on growth performance and lipid metabolism, whereas LC dosages used in this study have increased the oxidation rate of fatty acids in the hepatopancreas of R. lagowski and improved the accumulation of fat in hepatopancreas cells induced by oxidized fish oil. [ABSTRACT FROM AUTHOR]

Dietary lipids and fatty acids are involved in cell metabolism and animal physiological regulation. However, oxidized lipids could induce oxidative stress and disorder normal growth and physiological health in fish. A 12-week rearing experiment with 6% fish oil (6F), 6% oxidized fish oil (6OF) and emodin supplemented diets (6F + E, 6OF + E) was conducted to evaluate the protective mechanism of emodin on oxidized fish oil stress in Megalobrama amblycephala. Results indicate that, under oxidized fish oil stress, emodin rescued the growth performance inhibition, improved special growth ratio (SGR), and reduced feed conversion ratio (FCR) and hepatosomatic index (HSI); rescued intestine histological impairment, ameliorated the structural expansion and membrane damage of mitochondria in intestine cells, and increased the length and intensity of intestinal villus. Moreover, emodin enhanced serum immune and antioxidant enzyme activity, increased metabolic activity through PPARs signaling, increased antioxidant capacity through PPARs and Nrf2-Keap1 signaling based on the transcriptional expression of specific genes. These results indicate emodin could be used as an effective immunostimulant to protect organism form oxidative stress induced by dietary oxidized lipid. This may provide insights for oxidized lipid prevention in aquaculture production. • Emodin ameliorates the growth inhibition and histological impairment induced by oxidized fish oil. • PPARs signaling involves in metabolic and antioxidant amelioration. • Nrf2-Keap1 signaling functions in antioxidant resistance. [ABSTRACT FROM AUTHOR]

Nrf2/Keap1 pathway is associated with oxidative stress. l -carnitine is currently under preclinical evaluation as a antioxidant, but the use of l -carnitine in aquaculture has been poorly evaluated and so far no mechanism has been demonstrated. Here, we explored the effects of l -carnitine in vitro and in vivo and discussed the possible molecular mechanisms involved. Firstly, Nrf2 -siRNA significantly knocked down the mRNA level of Nrf2 in FHM cells. Thus, the activities of antioxidant enzymes (T-SOD, CAT, GSH-PX) and the level of antioxidant substance (GSH) and the level of MDA showed that Nrf2 -siRNA pretreatment weakened the protective effect of l -carnitine. Moreover, the mRNA levels of Keap1 , Nrf2 , Maf and HO-1 indicated that l -carnitine regulated Nrf2/Keap1 activation. Furthermore, oxidized fish oil remarkably suppressed growth in Rhynchocypris lagowski Dybowski, and the lower antioxidant capacity was also observed in liver. According to the results of immune related indexes (the levels of IL-1β, TNF-α, LZM, AKP) in serum and the mRNA levels of immune related genes (NF-κB , IL-1β , TNF-α , IL-8 , IL-10 and TGF-β) in liver, oxidized fish oil also induced inflammatory response in fish. Also, l -carnitine supplementation can relieve this bad condition. In conclusion, l -carnitine regulated Nrf2/Keap1 activation in vitro and in vivo and protected oxidized fish oil-induced inflammation response by inhibiting the NF-κB signaling pathway in Rhynchocypris lagowski Dybowski. • Nrf2-siRNA weakened the protective effect of l -carnitine in FHM cells. • Oxidized fish oil suppressed growth performance, antioxidant capacity and immunity. • The protective effect of l -carnitine was due to the activation of Nrf2/Keap1 and NF-κB signaling. [ABSTRACT FROM AUTHOR]

Dietary lipid oxidation is a lasting concern to aquafeed manufacturers and aquaculture farmers. Here, we determined if there was an association between oxidized fish oil (OFO) and hepatopancreatic injury in Chinese mitten crab, and evaluated the alleviating effects of a combination of vitamins C and E on hepatopancreatic injury. There were significant reductions in the body weight gain, hepatopancreatic index, and feed efficiency in crabs that received OFO. Diets with OFO also resulted in reduced crude fat contents in the hepatopancreas and muscle tissues, and alternations in the hepatopancreatic fatty acid compositions, especially a reduction in polyunsaturated fatty acids. Moreover, dietary OFO exposure reduced the antioxidant defense and non‐specific immune response, caused hepatopancreatic injury, and even apparent whitening. An ultrastructural examination of the whitened hepatopancreas revealed that hepatopancreatic cells were injured at varying degrees following OFO exposure. The combination of vitamins C and E could efficiently maintain a constant fatty acid profile in the hepatopancreas exposed to OFO, thus alleviating OFO‐induced hepatopancreatic injury. In addition, a biochemical analysis indicated that a combination of vitamins C and E not only improved the antioxidant status by mitigating the harmful effects of oxidized oil, but also modulated non‐specific immune responses in the crab that received OFO. Overall, OFO‐induced hepatopancreatic injury may be alleviated by a dietary combination of vitamins C and E, and the feeding of rancid forage fish or diets that contain highly oxidized oil is likely a cause of hepatopancreatic necrosis that is frequently observed in farmed crabs. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of oxidized fish oils on growth performance, metabolic oxidative status, and intestinal barrier function in broiler chickens. A total of 240 1-d-old female broiler chickens were assigned to 4 dietary treatments. Dietary treatments comprised of a basal diet supplemented with 4% of non-oxidized (fresh) fish oil, low-oxidized fish oil (FLX), moderately oxidized fish oil (FMX), and highly oxidized fish oil (FHX). Serum corticosterone levels at day 14 and liver concentrations of malondialdehyde (MDA) at day 14 and 21 were higher in birds fed oxidized fish oil compared with those fed then non-oxidized fish oil diet (P < 0.01 in both cases). Furthermore, mRNA expression levels of claudin-1 and occludin were reduced, while those of IL-22 and catalase were increased, in the livers of birds fed the highly oxidized oils compared with those fed fresh fish oils (P ≤ 0.001 in all cases). These results indicate that supplementation of broiler diets with 4% oxidized fish oils can cause lipid peroxidation in the liver, involving increased concentrations of MDA, impaired gut barrier function as a result of increased intestinal permeability due to decreased expression of the tight junction proteins claudin-1/occludin, and intestinal inflammation mediated via upregulation of IL-22 expression in the mucosal tissues. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of dietary astaxanthin (AX) on the growth performance, antioxidant parameters, and repair of hepatopancreas damage in Pacific white shrimp (Litopenaeus vannamei). To evaluate the hepatopancreas protective function of AX in shrimps, we compared the effect of five isonitrogenous and isoenergetic diets under oxidized fish oil conditions with varying AX levels during the 50-day experimental period. The formulated diets were as follows: (i) OFO (oxidized fish oil); (ii) OFO/AX150 (oxidized fish oil + AX150 mg/kg); (iii) OFO/AX250 (oxidized fish oil + AX250 mg/kg); (iv) OFO/AX450 (oxidized fish oil + AX450 mg/kg); and, (v) control group (fresh fish oil). Results showed that the oxidized fish oil with 275.2 meq/kg peroxide value (POV) resulted in a substantial decrease in the final body weight of L. vannamei (P > 0.05) and induced some visible histopathological alterations in the hepatopancreas. Growth performance was significantly higher in shrimps fed with the OFO/AX450 diet than those fed with the OFO diet (p < 0.05). However, no significant difference was observed when the OFO/AX450 diet was compared to the control diet containing fresh fish oil (p > 0.05). Moreover, shrimps under the OFO/AX450 diet displayed a significant improvement in hepatopancreatic health and showed a reduction of malondialdehyde (MDA) compared to those under the OFO diet (p < 0.05). Dietary AX improved the antioxidant capacity of L. vannamei by increasing the catalase (CAT) activity in the hemolymph. Acute salinity change test showed a higher shrimp survival rate under OFO/AX450 diet than the OFO diet (p < 0.05), suggesting that AX can contribute to enhanced stress tolerance. In conclusion, our data suggest that AX confers dose-dependent protection against OFO-induced oxidative insults and hepatopancreatic damage in shrimp.

Abstract Four isonitrogenous and isolipidic diets containing fresh fish oil (peroxide value, POV: 7.2 meq kg−1, diet FR) and three degrees of oxidized fish oil (POV: 155, 275 and 564 meq kg−1, diet OX155, OX275 and OX564, respectively) were formulated to investigate the effects of dietary oxidized fish oil on growth performance, body composition, antioxidant defense system and mitochondrial function of juvenile largemouth bass, Micropterus salmoides. After a 12-week feeding trial, fish fed the OX155 obtained significantly higher (P <.05) weight gain, final body weight and specific growth rate than the FR because of their remarkable higher feed intake. Malonaldehyde (MDA) levels were markedly increased in plasma, liver and mitochondria of largemouth bass fed diet OX564 than those fed FR. Fish fed the OX564 also obtained the highest levels of lipid peroxidation (LPO) than other groups. Antioxidant enzyme activities and mRNA levels were stimulated after 12 weeks of feeding. The highest activities of superoxide dismutase (SOD) and glutathione peroxidase (Gpx) in liver and plasma were obtained in group OX564. The relative expression of TNF-α was decreased with the increasing oxidative degree of dietary fish oil, while the relative expression of Caspase 8, 9 and 10 were increased with the increasing oxidative degree of dietary fish oil. The relative expression of Bcl-2 and Bcl-xL were lower in fish fed the OX275 and OX564. The lowest activities of malate dehydrogenase (MDH), succinate dehydrogenase (SDH) and citrate synthase in liver were found in group OX564, in which the ATP level also lower than other groups. Liver mitochondria of fish fed the FR were more resistant to the calcium-induced mitochondrial swelling. More reactive oxygen species (ROS) were produced in fish fed the OX564 compared with those fed the FR after the 12-week trial. Membrane potential and Ca2+ induced swelling of mitochondria also affected by dietary oxidized fish oil. The present study indicated that dietary oxidized fish oil increased oxidative stress, influenced antioxidant system and induced apoptosis of largemouth bass, hepatic mitochondrial function and energy metabolism also were impaired by dietary oxidized fish oil. Highlights • Dietary oxidized fish oil disordered the function of mitochondria and impaired the energy metabolism of largemouth bass. • Dietary oxidized fish oil increased the lipid peroxidation, impaired the antioxidant system of Largemouth bass. • Dietary oxidized fish oil induced the apoptosis of Largemouth bass. [ABSTRACT FROM AUTHOR]

The present study was designed to assess the effects of fish oil with different oxidation degree on growth performance, serum biochemistry parameters and expressive abundance of oxidative stress and fat metabolism genes of orange spotted grouper Epinephelus coioides. The oxidized fish oil was conducted as follows: storage temperature: 4°C, ambient temperature (AT, [31.5 ± 3.5]°C); storage time: 45, 90, 135 days; antioxidant contents: 30 mg/kg (ethoxyquin [EQ]), 300 mg/kg Higher EQ (HEQ). According to the different treated conditions, 14 kinds of fish oil with different oxidation degree were obtained: TF+EQ [positive control (fresh oil + EQ)], TF (negative control [fresh oil]), T4°C+45d+EQ, T4°C+45d+HEQ, T4°C+90d+EQ, T4°C+90d+HEQ, T4°C+135d+EQ, T4°C+135d+HEQ, TAT+45d+EQ, TAT+45d+HEQ, TAT+90d+EQ, TAT+90d+HEQ, TAT+135d+EQ, TAT+135d+HEQ. Groupers were fed isonitrogenous and isolipidic diets containing 14 kinds of fish oil for 8 weeks, respectively. The results showed that survival, weight gain rate and thermal growth coefficient decreased as oxidation degree of dietary fish oil increased (p < 0.05). Higher serum total protein, triglyceride and glucose were observed with ascending oxidation degree of fish oil (p < 0.05). The genes expression levels of catalase, superoxide dismutase and glutathione peroxidase were up‐regulated with dietary oxidized level increasing (p < 0.05). In addition, the similar status also appeared in expression of peroxisome proliferator‐activated receptor gamma (PPARγ), hormone‐sensitive lipase (HSL) and fatty acid synthase (FAS) genes. In conclusion, the fish oil would show negative influence on the fish health until peroxide value and p‐anisidine value in oil exceed 12.96 meq/kg and 20.89. The best storage condition for fish oil is 4°C, 45 days and 30 mg/kg EQ which could keep fish oil available property to grouper. [ABSTRACT FROM AUTHOR]

The current study is conducted to determine the influences of dietary selenium (Se) and oxidized fish oil (OFO) on growth, nutritional composition, muscle development, antioxidant responses and selenoprotein expression in the muscle of yellow catfish. We used the 2 × 2 factorial experimental design, which included two dietary Se levels at 0.25 (adequate) and 0.5 (high) mg Se/kg diets, and each Se level had fresh fish oil (FFO) and OFO, respectively. The experiment continued for 10 weeks. Compared to FFO group, dietary OFO reduced final body weight (FBW), specific growth rate (SGR) and weight gain (WG), and the contents of n-6 polyunsaturated fatty acid (PUFA), 18: 2n-6, 20: 4n-6, n-3 PUFA, 20: 5n-3, 22: 6n-3 and total PUFA, the diameters of muscle fibers >80 μm, mRNA expression of mef2d , myf5 , myod , s6kb and mTOR, and the ratio of p-mTOR to mTOR protein expression, but increased feed conversion rate (FCR), muscle lipid content, malic enzyme (ME) and isocitrate dehydrogenase (ICDH) activities, the number of the muscle fiber with the diameter lower than 50 μm; high dietary Se addition alleviated OFO- induced variations of these indices mentioned above. Dietary OFO also reduced muscle catalase (CAT) and glutathione peroxidase (GPX) activities and total antioxidant capacity (AOC), and mRNA expression of gpx1 , gpx2 , gpx3 , selenoe , selenok and selenos , but increased total superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and NRF2 protein expression, and high dietary Se addition alleviated OFO-induced changes of these parameters involved in antioxidant responses and selenoprotein expression in the muscle of yellow catfish. Based on these observations above, dietary Se addition alleviated OFO-induced lipogenesis, and reversed the OFO-induced inhibition of muscle growth and development, and oxidative damage of muscle. Our study provides new mechanistic insights into the Se and OFO interaction in fish. The biological basis through which dietary OFO and Se diets interacted to affect muscle metabolism and physiology is scarce. Our study indicated that dietary Se could alleviate OFO-induced negative effects on muscle metabolism and physiology, which will be helpful to the feed formulation and fish farm. • Se alleviated dietary OFO-induced reduction of growth performance. • Se alleviated dietary OFO-induced reduction of muscle PUFA content. • Se alleviated dietary OFO-induced reduction of muscle growth and development. • Se alleviated dietary OFO-induced increase of lipogenesis and lipid deposition. • Se reversed dietary OFO-induced oxidative stress and selenoprotein expression. [ABSTRACT FROM AUTHOR]

Selenium (Se) functions through selenoproteins and is essential to growth and metabolism of vertebrates. The present study was conducted to identify twelve selenoproteins genes (selenoe , selenof , selenoh , selneoi , selenom , selenok , selneon , selenoo , selenot , selenos , selenou and msrb1) from yellow catfish. Their mRNA expression patterns, as well as their response to dietary oxidized fish oils and Se addition were explored. We use 3′and 5′ RACE PCR to clone full-length cDNA sequence of twelve selenoprotein genes from yellow catfish. Their mRNA expression patterns were assessed via quantitative real-time PCR. Yellow catfish were fed diet adequate Se+ fresh fish oil, adequate Se+ oxidized fish oil, high Se+ fresh fish oil and high Se+ oxidized fish oil, respectively, for 10 weeks. Their kidney, heart, brain and testis were used to assess the mRNA expression of twelve selenoprotein. Twelve selenoprotein genes had similar domains with mammals and the other fish. Their mRNAs were expressed widely in eleven tissues but varied with the tissues. Dietary oxidized fish oils and Se addition influenced their mRNA abundances of twelve selenoproteins in a tissue-dependent manner. Our study demonstrated the characterization and expression of twelve selenoproteins, and elucidated their responses in yellow catfish fed diets varying in oxidized fish oils and Se addition, which increased our knowledge into the biological function and regulatory mechanism of Se and selenoproteins in fish. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effects of dietary aged maize with supplementation of different levels of oxidized fish oil on growth performance, nutrient digestibility, serum antioxidant activity and gut health in piglets. Forty-two piglets were arranged in 2 × 3 factorial treatments in a complete randomized block design with seven replicates per treatment and one pig per replicate for 28 d. Diets included twp types of maize (normal maize or aged maize) and three levels of oxidized fish oil (OFO) (3% non-oxidized fish oil (0% OFO), 1.5% OFO and 1.5% non-oxidized fish oil (1.5% OFO), and 3% OFO (3% OFO). Results showed that dietary aged maize did not affect growth performance, diarrhea, and the apparent total tract digestibility (ATTD) of nutrients in piglets (p > 0.05). However, aged maize increased malonaldehyde (MDA) content and decreased total antioxidant capacity (T-AOC) in serum on both 14th and 28th days (p < 0.05) compared to the normal maize groups. Meanwhile, compared with normal maize, dietary aged maize showed a slight, but not significant (p > 0.10) decrease in total superoxide dismutase (T-SOD) activity and VE content in serum on the 14th day. In addition, aged maize significantly decreased GLUT2 mRNA expression (p < 0.05) and tended to increase (p < 0.10) TNF-α and IL-6 mRNA expression in jejunal mucosa. Compared with non-oxidized fish oil, oxidized fish oil resulted in the decrease of the 14−28 d and 0−28 d ADG, as well as the ATTD of dry matter (DM), ether extract (EE), organic matter (OM) (p < 0.05), whereas the increase in diarrhea index (p < 0.05) and F/G of the whole period (p < 0.05). Oxidized fish oil decreased serum T-AOC on both the 14th and the 28th days (p < 0.05), and decreased serum T-SOD activity and VE content on the 28th day (p < 0.05), whereas increased serum MDA content on the 28th day (p < 0.05) and 14th day (p < 0.10) compared with fresh fish oil. Meanwhile, MUC2 (p < 0.05) and SGLT1 (p < 0.10) mRNA expression in jejunal mucosa were decreased compared with non-oxidized fish oil. In addition, dietary oxidized fish oil tended to decrease 14−28 d ADFI and the ATTD of CP (p < 0.10), and piglets fed oxidized fish oil significantly decreased 14−28 d ADFI, the ATTD of CP, GLUT2 and SGLT1 mRNA expressions in jejunal mucosa when piglet also fed with aged maize (p < 0.05). Collectively, these results indicated that dietary oxidized fish oil decreased growth performance and nutrients digestibility of piglets fed with aged maize. This nutrient interaction may be mediated by inhibiting intestinal nutrient transporter, inducing intestinal inflammation, and reducing antioxidant capacity.

The aim of this experiment was to investigate whether dietary coenzyme Q10 could alleviate stress response of Micropterus salmoides caused by oxidized fish oil. Four isonitrogenous and isoenergetic diets were formulated to contain 100% fresh fish oil (FFO), 50% fresh fish oil + 50% oxidized fish oil (BFO), 100% oxidized fish oil (OFO) and 100% oxidized fish oil + 0.1% coenzyme Q10 (QFO) and were fed to Micropterus salmoides (95 ± 0.60 g) for 70 days. Higher weight gain rate was recorded in fish fed diet supplemented with coenzyme Q10 (CoQ10). FFO and BFO significantly increased contents of fat and energy in whole-body, while protein and energy retention significantly decreased in fish fed OFO. Apparent digestibility of energy and fat showed a significant decrease trend with increased the proportion of dietary oxidized fish oil. Fish fed OFO significantly increased activities of superoxide dismutase and catalase, while CoQ10 supplementation significantly reduced activities of alanine aminotransferase and aspartate aminotransferase in plasma. Contents of n-3 polyunsaturated fatty acids and highly unsaturated fatty acids, especially EPA and DHA in liver and muscle significantly decreased in fish fed OFO. Transcriptome analysis indicated that a total of 1238, 1189 and 1773 differentially expressed genes (DEGs, |log 2 (fold change) | >= 1 and q-value<=0.001) were found in the three comparison groups (FFO vs. OFO, FFO vs. QFO, OFO vs. QFO), respectively. After KEGG enrichment, the main changed pathways in the two comparison groups (FFO vs. OFO, OFO vs. QFO) related to the immune system. Dietary OFO up-regulated the expression of immune-related genes and inflammatory factors, while dietary CoQ10 supplementation reduced these effects. • Oxidized fish oil decreased feed utilization and protein and energy retention. • Oxidized fish oil adversely affected fillet quality of M. salmoides. • Dietary coenzyme Q10 promoted growth of M. salmoides. • Coenzyme Q10 alleviated stress response caused by oxidized fish oil. [ABSTRACT FROM AUTHOR]

Under oxidative stress condition, the protective effects of dietary chlorogenic acid (CGA) supplementation on liver antioxidant capacity, intestinal inflammation and barrier function, muscle development and skin coloration in channel catfish Ictalurus punctatus were explored in the current study. With that purpose, I. punctatus were fed five experimental diets containing 2% fresh fish oil (FFO, 9.2 meqO 2 /kg) or 2% oxidized fish oil (OFO, 897.4 meqO 2 /kg) without or with CGA supplementation (0.02%, 0.04% and 0.08%) for 8 weeks. Upon comparative analysis, the oxidized fish oil consumption significantly lowered weight gain rate, decreased intestinal villi length and muscular thickness values and the tight junction proteins mRNA abundance, augmented the intestinal proinflammatory factors, attenuated hepatic antioxidant enzymes activities and related genes mRNA expression levels, influenced the myogenic regulatory factors expression profile and impacted the myocyte density, myocyte area values as well as the skin pigments contents compared to the FFO treatment. Collectively, long-term feeding of the oxidized fish oil diet suppressed the growth performance, destroyed intestinal structural integrity, caused intestinal inflammation and hepatic oxidative stress, impacted the skeletal development and skin color of I. punctatus. Whereas CGA supplementation in oxidized fish oil diets partially counteracted the negative effects of the oxidized fish oil on I. punctatus in terms of increasing the growth performance, improving the intestinal mucosal structure, alleviating hepatic oxidative stress and intestinal inflammation, recompiling the myogenic regulatory factors expression and improving skin color. In conclusion, CGA has great potential to be an aquatic feed additive. • Oxidized fish oil suppressed growth, destroyed intestinal structural integrity, attenuated liver antioxidant capacity. • Long-term feeding of the oxidized fish oil diet impacted the skeletal growth and development and skin color of Ictalurus punctatus. • CGA supplementation partially counteracted the negative effects of oxidized fish oil on Ictalurus punctatus. [ABSTRACT FROM AUTHOR]

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A 4-week feeding trial was conducted to determine the effects of oxidized fish oil ( OFO, POV: 234.84 meq kg−1) on growth performance and oxidative stress of Litopenaeus vannamei. Five diets containing various OFO levels (0, 25, 50, 75 and 100 g kg−1) with the same dietary lipid level were fed to L. vannamei. The results showed that the body weight gain and the specific growth rate of the shrimp fed with 50, 75 and 100 g kg−1 of OFO diets decreased significantly ( P < 0.05), whereas the hepatosomatic index increased significantly ( P < 0.05). The malondialdehyde concentrations in the serum and muscle of the shrimp fed with 50, 75 and 100 g kg−1 of OFO diets were significantly higher than that of the shrimp fed with fresh fish oil ( P < 0.05). The total antioxidant competence decreased significantly compared with the control group. Therefore, dietary OFO affects the growth performance and increases the oxidative stress of shrimp. [ABSTRACT FROM AUTHOR]

Recent studies in terrestrial animals have shown that feeding the oxidized lipids led to a reduction in triacylglycerols ( TAG) and total cholesterol ( TC) in liver and plasma. However, limited information is available on the effect of oxidized lipids on lipid metabolism in fish. In this study, four diets containing 0 g kg−1 (control: fresh fish oil), 30 g kg−1 (low-oxidized oil, LOO), 60 g kg−1 (medium-oxidized oil, MOO) and 90 g kg−1 (high-oxidized oil, HOO) graded oxidized oil levels with the same dietary lipid level were fed to channel catfish for 86 days. The tissue lipid metabolism and fatty acid composition of the fish were investigated after this period. The results showed that plasma and liver concentrations of TAG and TC decreased with increasing dietary oxidized oil level ( P < 0.05). Decreasing liver lipoprotein lipase and hepatic lipase activities were observed with increasing dietary oxidized fish oil inclusion ( P < 0.05). The liver C22:6n−3 concentrations significantly decreased with increasing dietary oxidized oil level ( P < 0.05), while muscle lipid had a high proportion of polyunsaturated fatty acids. It suggests that the adverse effects of dietary oxidized oil may be induced by inhibiting lipid metabolism enzymes and, consequently, inhibition of cholesterol homoeostasis and fatty acid synthesis. [ABSTRACT FROM AUTHOR]

Utilizing a 2 × 2 factorial design, four experimental diets (diet LVFF, low-vitamin premix + fresh fish oil; diet LVOF, low-vitamin premix + oxidized oil; diet HVFF, high-vitamin premix + fresh oil; diet HVOF, high-vitamin premix + oxidized oil) were formulated to investigate the protective role of high level of vitamin premix against the deleterious effects of highly oxidized fish oil (peroxide value, POV: 450 meq kg−1) consumption in juvenile largemouth bass. After a 10-week feeding trial, survival rates of all treatments were 100%. Neither vitamin premix level nor oil type affected feed intake, growth performance or feed utilization, although treatment HVFF obtained the highest weight gain and specific growth rate, and the lowest feed conversion ratio. Hepatosomatic and viscerosomatic index increased while intraperitoneal fat ratio decreased with rancid oil reception, and they did not benefit from increasing vitamin premix supply. However, dietary high level of vitamin premix ameliorated the decreased whole-blood haemoglobin content and increased plasma low- and high-density lipoprotein cholesterol levels induced by oxidized oil reception. Whole-body and liver composition were sensitive to dietary oil oxidation, and vitamin premix addition eliminated the decreased whole-body lipid content challenged by rancid oil consumption. Hepatic superoxide dismutase activity was stimulated by dietary oil oxidation and increment of vitamin premix abrogated this effect. Dietary oxidized oil inclusion resulted in increased malondialdehyde contents and decreased vitamin E concentrations both in the liver and muscle, and vitamin premix supplementation ameliorated these effects. In conclusion, the results in this study suggested that the well-ingested oxidized oil could induce severe oxidative damage and loss of reducing capacity in largemouth bass, and dietary high level of vitamin premix could alleviate these effects. This practice is recommended in intensive aquaculture practice in tropical or subtropical regions where oils are susceptible to lipid peroxidation under unsatisfactory storage. [ABSTRACT FROM AUTHOR]

Six oxidized fish oil contained diets were formulated to investigate the effect of graded levels of vitamin E (V) (α-tocopherol acetate: 160, 280, and 400 mg kg) associated with either 1.2 or 1.8 mg kg selenium (Se) on growth, body composition, and antioxidant defense mechanism of juvenile largemouth bass. Another control diet containing fresh fish oil with 160 mg kg V and 1.2 mg kg Se was also prepared. Over a 12-week feeding trial, about 5 % of Micropterus salmoide fed diet OxSe1.2/V160 showed inflammation and hemorrhage symptoms at the base of dorsal, pectoral, and tail fin. Fish in all treatments survived well (above 90 %). Feed intakes (88.42−89.58 g fish) of all treatments were comparable. Growth performances (weight gain and specific growth rate) and feed utilization (feed and protein efficiency ratio) were significantly impaired by dietary oil oxidation, and they did not benefit from neither V nor Se supplementation. Regardless of dietary V and Se supplementation, oxidized oil ingestion resulted in markedly decreased hepatosomatic index and intraperitoneal fat ratio. Oxidized oil ingestion also induced markedly lower liver and muscle lipid contents, and these effects could be alleviated by dietary Se supplementation. Dietary oil oxidation stimulated hepatic catalase activities relative to the control, and supplementation of V abrogated this effect. Hepatic reduced glutathione content in the control was markedly higher than that of treatment OxSe1.2/V160, without any significant differences comparing with the other oxidized oil receiving groups. Hepatic glutathione peroxidase activity and liver Se concentration reflected dietary Se profile, whereas liver V level reflected dietary V profile. Compared with the control, fish fed diet OxSe1.2/V160 obtained markedly higher serum, liver and muscle malondialdehyde contents, which droppe significantly with increasing either V or Se supplementation. In conclusion, the overall results in this study suggested that both V and Se inclusion could protect largemouth bass from the oxidative damage challenged by dietary oil oxidation. [ABSTRACT FROM AUTHOR]

A 60-day feeding trial was conducted to determine the effects of palm oil blended with oxidized and non-oxidized fish oil on growth performances, hematology, and non-specific immune response in juvenile Japanese sea bass, Lateolabrax japonicas. Japanese sea bass (1.73 ± 0.01 g) were fed seven experimental diets containing 100 g/kg of dietary lipid in forms of palm oil (10P), fish oil (10F), fish oil blended with palm oil at different ratios, 6:4 (6F4P) and 4:6 (4F6P), oxidized fish oil (10OF), and oxidized fish oil blended with palm oil at different ratios, 6:4 (6OF4P) and 4:6 (4OF6P). After the feeding trial, the following results were illustrated. No significant effects were observed in survival, feed conversion ratio, condition factor, and hematocrit after feeding with experimental diets for 60 days. The relatively higher specific growth rate and hematology were observed in 6F4P. Furthermore, both palm oil and oxidized fish oil acted as a negatively on serum lysozyme activity ( P < 0.05). This study suggested that a ration of 6F4P is recommended as an innocuous ratio for Japanese sea bass. Furthermore, according to the present investigation, palm oil seems to have the ability to improve the protein efficiency when added to oxidized fish diets as well as a positive trend to the growth performance ( P > 0.05). [ABSTRACT FROM AUTHOR]

Four isonitrogenous and isolipidic diets containing fresh fish oil (peroxide value, POV: 11.5 meq kg−1, diet FR) and three degrees of oxidized fish oil (POV: 132, 277 and 555 meq kg−1, diet OX132, OX277 and OX555, respectively) were formulated to investigate the effects of dietary oxidized fish oil on growth performance, body composition, antioxidant defence mechanism and liver histology of juvenile largemouth bass. After a 12-week feeding trail, a proportion of approximately 9% of Micropterus salmoides showed inflammation and haemorrhage at the base of dorsal, pectoral and tail fin in both groups OX277 and OX555. Fish fed oxidized oil diets obtained significantly higher ( P < 0.05) weight gain and specific growth rate because of their remarkable higher feed intakes, compared with the fresh oil receiving group. The analysis of biometric parameters and body composition indicated significant differences ( P < 0.05) in various test diets. The activities of hepatic catalase and superoxide dismutase were significantly stimulated ( P < 0.05) by oxidized oil ingestion. Hepatic glutathione peroxidase, glutathione reductase and glutathione-S-transferase activities were significantly higher ( P < 0.05), and liver glutathione content was markedly lower ( P < 0.05) in group OX555 than the other treatments. Oxidized oil consumption resulted in marked depletion ( P < 0.05) of vitamin E concentration in plasma, liver and muscle tissue, increased plasma and muscle malondialdehyde content along with decreased haematocrit value. Histological examinations indicated that hepatocytes with lipid vacuoles and nuclear migration were shown in groups OX277 and OX555. The overall results in this study suggested that an increased oxidative stress in M. salmoides fed oxidized lipid may account for their stimulated hepatic antioxidant defences, vitamin E depletion in plasma and certain tissues, and pathological changes. The detrimental effect of oxidation products on fish health and the unexpectedly enhanced feed intake of oxidized feeds in M. salmoides underline the importance that cares should be taken to minimize dietary oxidation products to the greatest extent possible. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study was to investigate the effects of replacement of fresh fish oil (FFO) by palm oil (PMO) and/or oxidized fish oil (OXF) mixed with PMO on growth performances, tissue fatty acid composition and oxidative status in juvenile Japanese sea bass. A 50-day feeding trial on Japanese sea bass (average weight 1.7g) was conducted in triplicate groups of fish fed with seven test diets containing different level of FFO and PMO at 100%FFO (10F, a positive control), 60%FFO and 40%PMO (6F4P), 40%FFO and 60%PMO (4F6P), 100%OXF (10OF), 60%OXF and 40%PMO (6OF4P), 40%OXF and 60%PMO (4OF6P) and 100%PMO (10P, a negative control), respectively. Body weight gain (BWG), specific growth rates (SGR), feed conversion ratio (FCR), fatty acid compositions, vitamin E contents and thiobarbiturate reactive substances (TBARS) in muscles and livers were taken at the end of a trial. Survival rates were relatively high and almost similar among all groups. There were no significant differences in BWG and SGR among 10F, 6F4P and 4F6P or 10OF, 6OF4P and 4OF6P, respectively. However, addition of OXF reduced the growth rates of fish regardless of PMO supplementation. Contents of saturates and n−6 fatty acids in tissue increased linearly with increasing dietary PMO level. However EPA and DHA decreased gradually with higher inclusion of PMO among treatments. These results demonstrated that 50% FFO could be replaced by PMO for juvenile Japanese sea bass. Moreover, although the replacement of OXF (POV: 26meq/kg diet) with PMO could reduce lipid peroxidation in fish intestine and muscle, it could not improve fish growth performances. [Copyright &y& Elsevier]