Freshwater, Landlocked Grand Lake Strain of Atlantic Salmon (Salmo salar L.) as a Potential Genetic Source of Long Chain Polyunsaturated Fatty Acids Synthesis

Abstract

Selection efforts focused on adaptation to plant-based diets, particularly the ability to synthesize polyunsaturated fatty acids (PUFA), are now emerging in aquaculture. Landlocked salmon (Grand Lake population; GL) may differ from the commercial Saint John River (SJR) strain in terms of PUFA metabolism. The objective of this study was to determine if GL salmon can contribute toward broodstock selection for enhanced PUFA synthesis. Two diets containing either fish oil (FO) or plant-based oil (FO-free) were fed to the SJR and GL strains (∼58 g/fish) for 16 weeks. Growth, liver, and muscle fatty acid (FA) content, and transcript expression of lipid metabolism and inflammation-related genes were evaluated. GL salmon fed the FO diet showed reduced growth compared to SJR salmon (fed either diet); however, GL salmon fed the FO-free diet, growth was not significantly different compared to any group. In liver, SJR salmon fed the FO-free diet had higher levels of n-6 PUFAs (21.9%) compared to GL fed the same diet (15.9%); while GL salmon fed the FO-free diet had higher levels of monounsaturated FAs (48.9%) compared with SJR salmon fed the same diet (35.7%). 20:5n-3 and 22:6n-3 were the same in GL and SJR salmon liver and muscle, respectively, fed the FO-free diet. In liver, GL salmon fed the FO-free diet had higher acac and acly compared to all treatments and had higher fasb compared to both strains fed the FO-diet. GL salmon fed the FO-free diet had higher cd36c and fabp3b in liver compared to GL salmon fed the FO diet and SJR salmon fed either diet. GL salmon fed the FO-free diet had higher lect2a and pgds in liver compared to SJR salmon fed the FO-free diet. In muscle, GL salmon fed the FO-free diet had higher fadsd5 and fadsd6b compared with both strains fed the FO diet. These results suggest there is a genetic basis behind the potential for GL salmon to utilize FO-free diets more efficiently than SJR salmon, with regards to FA metabolism.

Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin

“…Providing low dietary EPA + DHA [0.3% used in ( Emam et al, 2020 ) and 0.4% in the current study] alongside either high C 18 -ω3 (representing precursors of anti-inflammatory mediators) or high C 18 -ω6 (representing precursors of ARA as pro-inflammatory mediators) might promote selective elongation to the required LC-PUFA (e.g., DGLA, EPA, and DHA) from the dietary C 18 precursors ( Emam et al, 2020 ). Salmonids have the ability to elongate and desaturate FAs to fulfill their physiological needs (e.g., balance the pro-inflammatory and anti-inflammatory FA profile in the membranes) using the available dietary FAs (ω3 or ω6) ( Leaver et al, 2008 ; Castro et al, 2012 ; Colombo et al, 2021 ). During immune stimulation (e.g., infection), a balance between pro- and anti-inflammatory responses of the host is required to minimize cellular damage caused by immune responses ( Cicchese et al, 2018 ).…”

Effects of Low-Lipid Diets on Growth, Haematology, Histology and Immune Responses of Parr-Stage Atlantic Salmon (Salmo salar)

“…3 Specific growth rate (%/day) = [100 × (ln final weight − ln initial weight)/days], 4 FI (g) = feed intake. 5 Feed efficiency (%) = 100 × (wet weight gain/dry feed intake). 6 Condition factor = 100 × (fish weight/total body length 3 ).…”

“…Atlantic salmon is a carnivorous species classified as an anadromous fish [ 5 ]. They inhabit freshwater during the initial parr stage and then move to seawater through a transformation from parr to smolt (smoltification) [ 6 ].…”

“…The values in the table are means ± SDs (n = 8). 2 VL, villi length (µm);3 VT, villi thickness (µm); 4 LPW, lamina propria width (µm);5 MT, muscularis thickness (µm); 6 GC, goblet cells (counts in a villus).…”

A Comparative Analysis of the Nutritional Quality of Salmon Species in Canada among Different Production Methods and Regions

“…Also, there may be genetic differences among different operations; this may have nothing to do with production method, but rather the source of salmon. Even among the same species, strain differences have been shown to impact nutritional metabolism, particularly regarding fatty acid metabolism [39,40]. Even within the same strain, differences in nutrient metabolism and fillet fatty acid profile could be due to differences in selective breeding programs at each operation.…”