Effects of palm oil blended with oxidized fish oil on growth performances, hematology, and several immune parameters in juvenile Japanese sea bass, Lateolabrax japonicas

Successful Co-Feeding of Asian Seabass, Lates calcarifer Larvae With Palm Oil-Based Microdiets and Live Feeds

Palm oil has been recognized as a high potential alternative dietary lipid source to reduce the reliance on expensive fish oil in aquaculture feeds. Unfortunately, most research studies were focusing on the juvenile or grow-out stage of aquatic species. This study was designed to develop weaning microdiets for Asian seabass larvae with dietary fish oil being replaced with crude palm oil (CPO) at 25, 50, and 75% (CPO25, CPO50, and CPO75) and refined bleached deodorized palm olein, refined palm oil (RPO) at 50 and 75% (RPO50 and RPO75) replacement levels. A fish-oil-based microdiet was used as a control treatment (FO100). The triplicate groups of fish larvae with initial weight and length of 1.71 ± 0.13 mg and 5.54 ± 0.34 mm, respectively, were stocked at 150 larvae/tank and co-fed with the experimental microdiets and live feeds (L-type rotifer and artemia). The final body weight (0.54–0.63 g) and specific growth rate (SGR) (12.8–13.13%/d) of fish-fed palm oil-based diets were significantly better than the control diet (0.42 g; 12.21%/day, respectively). In particular, RPO75 yielded the best SGR followed by RPO50, CPO75, CPO50, and CPO25. The feeding intake and feed conversion ratio (FCR) were not statistically different from other treatments (0.2–0.3 g/fish/d and 1.06–1.63, respectively). The survival rate of larvae-fed palm oil-based diets (33.11–46.67%) during the feeding trial was comparable to the control diet (39.33%). In the 65 ppt-salinity stress test at 25 DPH, there was no significant difference in terms of the survival rate of larvae fed the control diet and the CPO-based diets, but the lowest survival rate was observed in the RPO-based diets than the control diet. Higher final whole-body protein and lipid contents (15.3 ± 0.4 and 3.7 ± 0.0%, respectively) were observed in fish-fed CPO50 compared to other treatments. Generally, the replacement of fish oil with palm oil increased the palmitic acid (C:16:0) and oleic acid (C18:1n9) and significantly reduced the eicosapentaenoic acid (EPA) (C20:5n3) and docosahexaenoic acid (DHA) (C22:6n3) contents in both the microdiets and larval body, a common observation in this kind of investigation. Considering the good growth and survival of Asian seabass larvae in this study, availability of palm oil, and its competitive price compared to fish oil, it is suggested that weaning diets for Asian seabass larvae can be developed using palm oil as a partial source of dietary lipid.

Degradation of Muscle Quality in Hybrid Grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu) Due to Oxidative Damage Caused by Ingestion of Oxidized Fish Oil

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.

High percentage of dietary palm oil suppressed growth and antioxidant capacity and induced the inflammation by activation of TLR-NF-κB signaling pathway in large yellow croaker (Larimichthys crocea)

A 70-day feeding trial was conducted to investigate the effects of dietary fish oil (FO) replaced by palm oil (PO) on growth, biochemical and antioxidant response as well as inflammatory response in the liver of large yellow croaker (initial weight 15.87 ± 0.14 g). Four iso-proteic and iso-lipidic experimental diets were formulated with 0% (the control group), 33.3%, 66.7% and 100% FO replaced by PO. Fish fed the diet with 100% PO showed significantly lower growth performance than the control group. As expected, the contents of C16:0, C18:1n-9 and C18:2n-6 were increased with increasing dietary PO levels. There were remarkable increases in total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels in fish fed the diet with 100% PO compared to the control group. Moreover, dietary PO significantly increased activities of plasma alanine transaminase (ALT) and aspartate aminotransferase (AST) in fish fed the diet with 100% PO compared to the control group. The total antioxidant capacity (T-AOC) and the activity of catalase (CAT) in plasma were significantly decreased in fish fed the diet with 100% PO compared to the control group, and meanwhile no significant differences were found in T-AOC and CAT activity in fish fed diets with no more than 66.7% PO. Fish fed the diet with 100% PO exerted significantly higher toll like receptors (TLRs) and myeloid differentiation factor (MyD88) mRNA expression levels than the control group. The IFNγ, IL-1β and TNFα mRNA expressions were increased with increasing dietary PO levels. The increase of pro-inflammatory gene expression may be due to the activation of NF-κB signaling as the ratio of nucleus p65 to total p65 protein was elevated with the increase of dietary PO levels. These results showed that relatively higher PO levels in diets suppressed the growth and antioxidant capacity as well as induced the inflammatory response by activating TLR-NF-κB signaling pathway in juvenile large yellow croaker.

Effects of Angelica sinensis extracts on lipid oxidation in fish feeds and growth performance of juvenile Jian carp (Cyprinus carpio var. Jian)

The study was to explore the effect of the extracts of Angelica sinensis (EAs) on lipid oxidation in fish feeds compared with ethoxyquin (EQ) and the effect of dietary EAs on growth performance of carp (Cyprinus carpio var. Jian). Firstly, fish feeds were respectively added with EQ, and ethyl ether extract, ethyl acetate extract (EAE), acetone extract, ethanol extract (EE) and aqueous extract (AQE) of Angelica sinensis, except for the control. The results showed that EAs and EQ inhibited lipid oxidation in fish feeds (P < 0.05). Of all of the examined EAs, EAE showed the strongest protective effects against lipid oxidation (P < 0.05). Moreover, EAE at high concentrations showed a stronger effect on lipid oxidation compared with EQ (P < 0.05). Then, 7 experimental diets respectively supplemented with 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g/kg of EAE were fed to the respective treatment groups for 30 d. Four replicates were performed for each treatment group; 20 carp (mean weight: 12.10 ± 0.13 g) were in each replicate. The results indicated that dietary EAE improved the growth performance in carp (P < 0.05). The appropriate concentration of EAE for carp growth was estimated to be 3.643 g/kg diet. Thus, EAE could be used as a natural antioxidant in feeds for Jian carp.

The effects of ethoxyquin and Angelica sinensis extracts on lipid oxidation in fish feeds and growth, digestive and absorptive capacities and antioxidant status in juvenile red carp (Cyprinus carpio var. xingguonensis): a comparative study

Firstly, a linoleic and linolenic acid emulsion and fish feeds were incubated with graded levels of ethoxyquin (EQ) and petroleum ether extract, ethyl acetate extract (EAE), ethanol extract and aqueous extract of Angelica sinensis. The results showed that EQ and extracts of Angelica sinensis (EAs) inhibited lipid oxidation in material above. Of all of the examined EAs, EAE showed the strongest protective effects against the lipid oxidation. Moreover, EAE at high concentrations showed a stronger inhibitory effect on lipid oxidation than that of EQ. Next, 7 experimental diets that respectively supplemented 0.0, 0.2, 0.8 and 3.2 g kg^-1 of EQ and EAE were fed to 280 juvenile red carp (Cyprinus carpio var. xingguonensis) with seven treatment groups for 30 days. The results indicated that dietary EAE improved growth performance in carp. Moreover, dietary EAE increased the activities of trypsin, lipase, alpha-amylase, alkaline phosphatase, glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase (GPT) and decreased plasma ammonia content in carp. Meanwhile, dietary EAE reduced the levels of malondialdehyde and raised the activities of anti-superoxide anion, anti-hydroxyl radical, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase and the content of reduced glutathione in the hepatopancreas and intestine of carp. However, with the exception of GPT, dietary EQ got the opposite results to dietary EAE in carp. These results revealed that dietary EAE improved the digestive, absorptive and antioxidant capacities in fish. However, dietary EQ inhibited the digestive, absorptive and antioxidant capacities in fish. So, EAE could be used as a natural antioxidant for replacing EQ in fish feeds.

Effect of alkoxy glycerol on growth performance, immune response and disease resistance in Nile Tilapia (Oreochromis niloticus)

Fish oil and their compounds derived from the same have immense applications in the improvement of health, brain development, enhancing immunity etc. This study aimed at the supplementation of such a compound alkoxy glycerol derived from shark liver oil in fish diet and thereby analyzing growth as well as immune parameters of Oreochromis niloticus. 400 fishes were distributed into 11 glass tanks, and then fishes were weighed before starting the experiment. (Average weight was found to be 5.3 ± 0.10 g). Feed was prepared using alkoxy glycerol in the doses like 5, 10, 15 g kg^-1 Fishes were fed with the prepared diet for 30 days and growth parameters like specific growth rate (SGR), weight gain (WG), final weight (FW), and feed conversion ratio (FCR) were measured. On the 30th day, fishes were challenged with 0.1 ml of normal saline solution containing 10⁷ CFUml^-1 of Aeromonas hydrophila and disease resistance was monitored. After 30 days of post challenge observation, immunological and lipid peroxidation assays like alternative complement (ACH50), phagocytosis (PI), respiratory burst activities (RB), and serum lysozyme (SL) were performed.

Oxidized fish oil injury stress in Megalobrama amblycephala: Evaluated by growth, intestinal physiology, and transcriptome-based PI3K-Akt/NF-κB/TCR inflammatory signaling

Lipids are essential nutrients for animal. Oxidized lipid might induce injury stress for fish. Here we conducted a 12-week rearing experiment with diets containing 0, 2, 4, and 6% oxidized fish oil (6F, 4F2OF, 2F4OF, and 6OF) to describe the oxidative impairment mechanism on teleost fish blunt snout bream, Megalobrama amblycephala. Results were evaluated by growth performance, intestinal physiology, and transcriptome-based PI3K-Akt/NF-κB/TCR inflammatory signaling. From the results, 6OF reduced growth performance with increased FCR and reduced FBW, WGR and SGR compare with 6 F. Meanwhile, oxidized fish oil treatments also increased antioxidant enzyme activity, suggesting an impaired physiological condition. The plasmatic antioxidant enzyme activity of T-SOD, GSH-Px, ASAFR, concentration of MDA and cortisol were significantly increased in 6OF, while GSH concentration was decreased. Histological ultrastructure revealed the integrity of mid-intestinal cells and villus were destroyed in 6OF. Moreover, transcriptomic analysis revealed PI3K-Akt/NF-κB/TCR inflammatory signaling were active to oxidized fish oil stress. We verified the expression of twelve key genes related to this signaling by RT-PCR, which revealed TLR2, PI3K, Akt, NF-κB, MHCII-β, TCR-α, TGF-β, TNF-α, IL-6, IL-1β, GPx1 and GSTm were all activated under 6OF stimulation. We found that oxidized fish oil may induce oxidative stress, destroy intestinal integrity, produce free radical, dysregulate lipid metabolism and oxidative balance, reversely affect the physiological adaptation, and eventually lead to growth inhibition. This study revealed the mechanism of PI3K-Akt/NF-κB/TCR inflammatory signaling in M. amblycephala under oxidized fish oil stress, which may help to understand the complex regulation involved in lipid oxidative stress resistance.

Inhibition of lipid oxidation in foods and feeds and hydroxyl radical-treated fish erythrocytes: A comparative study of Ginkgo biloba leaves extracts and synthetic antioxidants

This study explored the effects of butylated hydroxytoluene (BHT) and ethoxyquin (EQ) and ethyl ether extracts, ethyl acetate extracts (EAE), acetone extracts, ethanol extracts and aqueous extracts of Ginkgo biloba leaves (EGbs) on lipid oxidation in a linoleic acid emulsion, fish flesh and fish feed and in hydroxyl radical (·OH)-treated carp erythrocytes. The linoleic acid, fish flesh and fish feed were incubated with BHT, EQ and EGbs at 45°C for 8 d, respectively, except for the control group. The lipid oxidation in the linoleic acid emulsion, fish flesh and fish feed was then measured by the ferric thiocyanate method or thiobarbituric acid method. The carp erythrocytes were treated with BHT, EQ or EGbs in the presence of 40 μmol/L FeSO₄ and 20 μmol/L H₂O₂ at 37°C for 6 h, except for the control group. Oxidative stress and apoptosis parameters in carp erythrocytes were then evaluated by the commercial kit. The results showed that BHT, EQ and EGbs inhibited lipid oxidation in the linoleic acid emulsion, fish flesh and fish feed and ·OH-induced phosphatidylserine exposure and DNA fragmentation (the biomarkers of apoptosis) in carp erythrocytes. Furthermore, BHT, EQ and EGbs decreased the generation of reactive oxygen species (ROS), inhibited the oxidation of cellular components and restored the activities of enzymatic antioxidants in ·OH-treated carp erythrocytes. Of all examined EGbs, EAE showed the strongest effects. The effects of EAE on lipid oxidation in the linoleic acid emulsion and on superoxide anion and malonaldehyde levels, catalase activity and apoptosis in ·OH-treated carp erythrocytes were equivalent to or stronger than those of BHT. Moreover, these results indicated that the inhibition order of EGbs on the generation of ROS and oxidation of cellular components in fish erythrocytes approximately agreed with that for the food and feed materials tested above. And, the antioxidative and anti-apoptotic effects of EGbs were positively correlated with their flavonoid content. Taken together, these results revealed that the fish erythrocyte system can be used as an experimental model to evaluate lipid oxidation in food and feed ingredients. The EAE can be used as a potential natural antioxidant or apoptosis inhibitor. The inhibition effects of EGbs on lipid oxidation and apoptosis may be due to the presence of flavonoid compounds.

Parâmetros hematológicos de tilápias-do-Nilo (Oreochromis niloticus) alimentadas com diferentes fontes de óleo

Objetivou-se avaliar a influência das fontes de óleo da dieta sobre os parâmetros hematológicos de tilápias-do-Nilo (Oreochromis niloticus). Foram utilizados 112 juvenis, com peso médio inicial de 50±12g, distribuídos em 16 caixas com capacidade total de 100L cada, num delineamento inteiramente casualizado com quatro tratamentos e quatro repetições, contendo sete peixes por repetição. Os tratamentos eram constituídos por: tratamento um - óleo de soja; tratamento dois - óleo de peixe; tratamento três - óleo de linhaça; tratamento quatro - óleo de oliva. As rações eram semipurificadas, isoproteicas (32% de proteína bruta) e isocalóricas (3200 kcal de energia bruta/kg de ração). Não houve diferença (P>0,05) entre os tratamentos quanto ao número e diferenciação de leucócitos, número de eritrócitos totais e níveis de hemoglobina. Os peixes do tratamento um apresentaram níveis superiores de hematócrito (P<0,05) comparados aos tratamentos dois e três. Encontrou-se maior volume corpuscular médio (VCM) nos peixes do tratamento quatro em relação aos outros tratamentos (P<0,05). O tratamento três apresentou concentração de hemoglobina corpuscular média (CHCM) superior, comparado aos peixes do tratamento quatro (P<0,05). As fontes de ácidos graxos da dieta podem influenciar os parâmetros hematológicos de tilápia-do-Nilo (Oreochromis niloticus). Houve uma tendência de aumento na eritropoiese de tilápia-do-Nilo alimentadas com dietas contendo altos níveis de ácidos graxos da série ω-6. As fontes dietιticas de óleo testadas não foram capazes de alterar o número total de eritrócitos e células sanguíneas da série branca em tilápias-do-Nilo.