Growth, Chemical Composition, Histology and Antioxidant Genes of Atlantic Salmon (Salmo salar) Fed Whole or Pre-Processed Nannochloropsis oceanica and Tetraselmis sp.

Sørensen, Solveig Lysfjord; Ghirmay, Ateshm; Gong, Yangyang; Dahle, Dalia; Vasanth, Ghana Kalerammana; Sørensen, Mette; Kiron, Viswanath

doi:10.3390/fishes6030023

Cited by 10 publications

(10 citation statements)

References 92 publications

(122 reference statements)

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“…The high Sod1 concentration in liver of fish fed C. vulgaris intact and T. chuii acutely after salinity change (20 h in seawater) may provide a better oxidative state during this time period but protein levels potentially decreased 2 weeks in seawater because lower ROS levels were subsequently present. In line with these results, previous research on salmon fed with a pre-extruded Tetraselmis diet also revealed significantly induced sod1 expression in the liver ( Sørensen et al, 2021 ).…”

Section: Discussionsupporting

confidence: 85%

Salinity change evokes stress and immune responses in Atlantic salmon with microalgae showing limited potential for dietary mitigation

van Muilekom,

Mueller,

Lindemeyer

et al. 2024

Front. Physiol.

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Smoltification was found to impact both immune and stress responses of farmed Atlantic salmon (Salmo salar), but little is known about how salinity change affects salmon months after completed smoltification. Here, we examined (1) the effect of salinity change from brackish water to seawater on the stress and immune responses in Atlantic salmon and (2) evaluated if functional diets enriched with microalgae can mitigate stress- and immune-related changes. Groups of Atlantic salmon were fed for 8 weeks with different microalgae-enriched diets in brackish water and were then transferred into seawater. Samples of the head kidney, gill, liver and plasma were taken before seawater transfer (SWT), 20 h after SWT, and 2 weeks after SWT for gene-expression analysis, plasma biochemistry and protein quantification. The salmon showed full osmoregulatory ability upon transfer to seawater reflected by high nkaα1b levels in the gill and tight plasma ion regulation. In the gill, one-third of 44 investigated genes were reduced at either 20 h or 2 weeks in seawater, including genes involved in cytokine signaling (il1b) and antiviral defense (isg15, rsad2, ifit5). In contrast, an acute response after 20 h in SW was apparent in the head kidney reflected by increased plasma stress indicators and induced expression of genes involved in acute-phase response (drtp1), antimicrobial defense (camp) and stress response (hspa5). However, after 2 weeks in seawater, the expression of antiviral genes (isg15, rsad2, znfx1) was reduced in the head kidney. Few genes (camp, clra, c1ql2) in the gill were downregulated by a diet with 8% inclusion of Athrospira platensis. The results of the present study indicate that salinity change months after smoltification evokes molecular stress- and immune responses in Atlantic salmon. However, microalgae-enriched functional diets seem to have only limited potential to mitigate the related changes.

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Section: Discussionsupporting

confidence: 85%

Salinity change evokes stress and immune responses in Atlantic salmon with microalgae showing limited potential for dietary mitigation

van Muilekom,

Mueller,

Lindemeyer

et al. 2024

Front. Physiol.

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“…Specifically, two algae that have been recently explored by the feed industry are the macroalga Gracilaria gracilis and the microalga Nannochloropsis oceanica. Although there are some reports on the effect of these algae on fish growth performance, immunity, oxidative status and intestine histomorphology (Batista et al, 2020;Passos et al, 2021;Sørensen et al, 2021), little is known about their impact on the intestinal microbiota of farmed fish.…”

Section: Introductionmentioning

confidence: 99%

Gracilaria gracilis and Nannochloropsis oceanica, singly or in combination, in diets alter the intestinal microbiota of European seabass (Dicentrarchus labrax)

Ferreira

Abdelhafiz²,

Abreu³

et al. 2022

Front. Mar. Sci.

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Algae feeds and fish gut microbiota have been given importance in the past few years because of the necessity to rely on sustainable ingredients in aquafeeds and the link of host-associated microbes to organismal health. But little is known about the potential of algae, particularly of micro- and macroalgae combination, to shape the intestinal bacterial communities. Hence, in the present work, the 16S rRNA gene sequencing technique was employed to unravel the effects of the seaweed Gracilaria gracilis and the microalga Nannochloropsis oceanica - included either singly or in combination in the diets of European seabass - on the diversities and composition of the gut bacterial communities. Results indicated that 8% inclusion of either G. gracilis (GRA) or N. oceanica (NAN) led to a reduction in the gut microbial diversity. On the other hand, inclusion of the micro- and macroalga in a blend (NANGRA) mitigated these plausible effects on the intestinal bacterial communities. The core microbiota of European seabass was composed of both beneficial (Lactobacillus and Cetobacterium) and potentially pathogenic (Flavobacterium) bacteria. The GRA diet was associated with a lower abundance of carbohydrate degraders and also promoted the growth of bacteria capable of outcompeting fish pathogens (Sulfitobacter and Methylobacterium). On the other hand, the NAN diet led to a higher representation of the genus Bacillus, with probiotic potential, accompanied by a decrease in Vibrio, a genus encompassing several fish pathogenic species. These findings demonstrate the ability of micro- and macroalgae to modulate the gut microbiota of European seabass, with plausible implications to host gut homeostasis.

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“…In another study, serum SOD and GPx activities recorded the highest values in Nile tilapia fed on a diet partially replaced with N. oculata at 5% for 60 days compared to the control fish [ 56 ]. Such GPx upregulation effect was not evident in the liver of whole N. oculata -fed Atlantic Salmon ( Salmo salar ) at 30% for 60 days [ 79 ]. Similar induction in the expression of Hsp70 was evident in the liver of whole N. oculata at 10% in Nile tilapia under naïve conditions for 4 weeks [ 75 ].…”

Section: Discussionmentioning

confidence: 99%

Nutritional and immunological evaluation of Nannochloropsis oculata as a potential Nile tilapia-aquafeed supplement

et al. 2023

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Nannochloropsis oculata (N. oculata) is a marine microalga containing bioactive compounds and a high omega-3 polyunsaturated fatty acid (ω-3 PUFAs). Therefore, it is very promising for nutraceutical and the functional food industry applications. Three groups of Nile tilapia (forty-five fish/group) were fed on basal diets or diets containing 5% (N5) or 10% (N10) of the microalga N. oculata for seven weeks. Fish growth performance, proximate composition, and lipid (fatty acids/ FAs and lipoproteins) profile were estimated. In addition, the expression pattern of some lipid metabolism and immune-relevant genes were assessed. An enhancement in whole body crude protein and growth indices of Nile tilapia was observed on both the supplemented groups N5 and N10. Higher levels of high-density lipoproteins (HDL); and lower levels of the low-density lipoproteins (LDL) were evident in both supplemented groups, while the cholesterol and triglycerides (TG) levels were similar among groups. Ω-3 PUFAs were the significant FAs profile of tilapia fed on N. oculata-supplemented diets in terms of eicosapentaenoic acid, docosahexaenoic acid, and n3/n6 ratio. Concerning the gene expression pattern, heat-shock protein70, glutathione-S-transferase, glutathione peroxidase, and interleukin-1β (IL-1β) were elevated significantly in both supplemented groups. IL-10 is only upregulated in the N10 group. The lipid metabolism-related gene expression showed downregulation of only fatty acid synthase (FAS) in both supplemented groups, with no statistical changes in Peroxisome proliferator-activated receptor alpha (PPARα). Tumor necrosis factor-α (TNF-α), Transforming growth factor-β1 (TGF-β1), and the apoptotic related genes [caspase3 and Proliferating cell nuclear antigen (PCNA)] showed insignificant changes among groups. The histopathological examination of the intestine, liver, and spleen supports our findings and confirms the benefits and safeness of N. oculata dietary inclusion. Collectively, N. oculata is a very promising nutraceutical for improving fish health and sustainability of aquaculture production. Graphical Abstract

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Growth, Chemical Composition, Histology and Antioxidant Genes of Atlantic Salmon (Salmo salar) Fed Whole or Pre-Processed Nannochloropsis oceanica and Tetraselmis sp.

Cited by 10 publications

References 92 publications

Salinity change evokes stress and immune responses in Atlantic salmon with microalgae showing limited potential for dietary mitigation

Salinity change evokes stress and immune responses in Atlantic salmon with microalgae showing limited potential for dietary mitigation

Gracilaria gracilis and Nannochloropsis oceanica, singly or in combination, in diets alter the intestinal microbiota of European seabass (Dicentrarchus labrax)

Nutritional and immunological evaluation of Nannochloropsis oculata as a potential Nile tilapia-aquafeed supplement

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