Influence of Dietary Long-Chain Polyunsaturated Fatty Acids and ω6 to ω3 Ratios on Head Kidney Lipid Composition and Expression of Fatty Acid and Eicosanoid Metabolism Genes in Atlantic Salmon (Salmo salar)

Abstract

The interaction of dietary eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) levels with omega-6 to omega-3 ratios (ω6:ω3), and their impact on head kidney lipid metabolism in farmed fish, are not fully elucidated. We investigated the influence of five plant-based diets (12-week exposure) with varying EPA+DHA levels (0.3, 1.0, or 1.4%) and ω6:ω3 (high ω6, high ω3, or balanced) on tissue lipid composition, and transcript expression of genes involved in fatty acid and eicosanoid metabolism in Atlantic salmon head kidney. Tissue fatty acid composition was reflective of the diet with respect to C18 PUFA and MUFA levels (% of total FA), and ω6:ω3 (0.5–1.5). Fish fed 0.3% EPA+DHA with high ω6 (0.3% EPA+DHA↑ω6) had the highest increase in proportions (1.7–2.3-fold) and in concentrations (1.4-1.8-fold) of arachidonic acid (ARA). EPA showed the greatest decrease in proportion and in concentration (by ~½) in the 0.3% EPA+DHA↑ω6 fed fish compared to the other treatments. However, no differences were observed in EPA proportions among salmon fed the high ω3 (0.3 and 1.0% EPA+DHA) and balanced (1.4% EPA+DHA) diets, and DHA proportions were similar among all treatments. Further, the transcript expression of elovl5a was lowest in the 0.3% EPA+DHA↑ω6 fed fish, and correlated positively with 20:3ω3, 20:4ω3 and EPA:ARA in the head kidney. This indicates that high dietary 18:3ω3 promoted the synthesis of ω3 LC-PUFA. Dietary EPA+DHA levels had a positive impact on elovl5a, fadsd5 and srebp1 expression, and these transcripts positively correlated with tissue ΣMUFA. This supported the hypothesis that LC-PUFA synthesis is positively influenced by tissue MUFA levels in Atlantic salmon. The expression of pparaa was higher in the 0.3% EPA+DHA↑ω6 compared to the 0.3% EPA+DHA↑ω3 fed fish. Finally, significant correlations between head kidney fatty acid composition and the expression of eicosanoid synthesis-related transcripts (i.e., 5loxa, 5loxb, cox1, cox2, ptges2, ptges3, and pgds) illustrated the constitutive relationships among fatty acids and eicosanoid metabolism in salmon.

Evaluation of the nutritional quality of ultra‐processed foods (ready to eat + fast food): Fatty acids, sugar, and sodium

“…As expected, E (food items composed of mayonnaise mainly) and S (fried and boiled shrimp meals) contained the highest content of PUFA (61.76% and 46.41%, respectively) with minimal differences when compared to previous literature values for the same items and cooking methods (Awogbemi et al, 2019;Czech et al, 2015;Ekiz & Oz, 2019;Katan et al, 2020;Modzelewska-Kapituła et al, 2019;Rant et al, 2019;Shan et al, 2019). For example, in fried shrimp from an FF restaurant, no C22:6 was detected in its reference values state; instead of C18:3n-3, we were able to identify just C18:3n-6 (Czech et al, 2015).…”

Transcriptome Analysis of Atlantic Salmon (Salmo salar) Skin in Response to Sea Lice and Infectious Salmon Anemia Virus Co-Infection Under Different Experimental Functional Diets

“…The details of the composition offour diets are provided in Table 1. Three of the diets were the same as used in Katan et al (16) and the relationship was indicated in Table 1. The four diets were initially blinded to investigators until the completion of the trial.…”

Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin

“…However, several nutritional and disease challenges threaten the Atlantic salmon aquaculture industry. There is growing evidence that nutritional modulations may be employed to improve Atlantic salmon’s immune response to the pathogens impacting its health and welfare ( Caballero-Solares et al, 2017 ; Martin and Król, 2017 ; Katan et al, 2020 ; Xue et al, 2020 ).…”