Effects of dietary fish to rapeseed oil ratio on steatosis symptoms in Atlantic salmon (Salmo salar L) of different sizes – PubMed Black Hawk Supplements

BLACK HAWK: Best lions mane supplement for energy

Published article

Choline is recognized as an essential nutrient for Atlantic salmon at all developmental stages. However, its dietary requirement is not well defined. Choline plays a critical role in lipid transport, and the clearest deficiency sign is intestinal steatosis. The present work, aiming to find whether lipid source and fish size may affect steatosis symptoms, was one of a series of studies conducted to identify which production-related conditions may influence choline requirement. Six…
Black Hawk Supplements, best supplements in the UK

Effects of dietary fish to rapeseed oil ratio on steatosis symptoms in Atlantic salmon (Salmo salar L) of different sizes - PubMed

Effects of dietary fish to rapeseed oil ratio on steatosis symptoms in Atlantic salmon (Salmo salar L) of different sizes

D Siciliani et al. Sci Rep. .

Abstract

Choline is recognized as an essential nutrient for Atlantic salmon at all developmental stages. However, its dietary requirement is not well defined. Choline plays a critical role in lipid transport, and the clearest deficiency sign is intestinal steatosis. The present work, aiming to find whether lipid source and fish size may affect steatosis symptoms, was one of a series of studies conducted to identify which production-related conditions may influence choline requirement. Six choline-deficient diets were formulated varying in ratios of rapeseed oil to fish oil and fed to Atlantic salmon of 1.5 and 4.5 kg. After eight weeks, somatic characteristics were observed, and the severity of intestinal steatosis was assessed by histological, biochemical, and molecular analyses. Fatty acid composition in pyloric intestine, mesenteric tissue, and liver samples was also quantified. The increasing rapeseed oil level increased lipid digestibility markedly, enhancing lipid supply to the fish. Moreover, small fish consumed more feed, and consequently had a higher lipid intake. In conclusion, the results showed that choline requirement depends on dietary lipid load, which depends on the fatty acid profile as well as the fish size.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1

Distribution of the histology scores for enterocyte steatosis of the pyloric caeca tissue among the treatment groups. X-axis presents rapeseed oil level for the two fish sizes: small (S1 = autumn smolts) and large (S0 = spring smolts) fish. Table insert presents results for an ordinal logistic regression of impact of fish size and rapeseed oil level on the distribution of the histological scores among the diet groups for pyloric caeca enterocyte steatosis.

Figure 2
Figure 2

Representative images of the pyloric caeca mucosal folds showing a close-up appearance of the different scores for the enterocyte steatosis changes. a shows no enterocyte vacuolization (orange arrow) which is normal morphology, while images b, c, and d show enterocyte steatosis changes graded as moderate, marked, and severe, respectively. Black arrows in images b to d depict the lipid accumulation in the supranuclear space of the enterocytes while the blue arrow in images c and d show the progressive squashing of the enterocyte nuclei from the normal ellipsoid shape to a smaller and more spherical shape as intracellular lipid accumulation increases.

Figure 3
Figure 3

Distribution of histology scores for inflammatory cell infiltration in the submucosa and lamina propria of distal intestine among the treatment groups. X-axis presents rapeseed oil level for the two fish sizes: small (S1 = autumn smolts) and large (S0 = spring smolts) fish. Table insert shows results for an ordinal logistic regression of impact of fish size and rapeseed oil level on the distribution of the histological scores among the diet groups for distal intestine submucosal infiltration.

Figure 4
Figure 4

Relative expression of biomarker genes for choline requirement. The curves show the estimated regression lines with indication of 95% credible intervals for posterior mean.

Figure 5
Figure 5

Effects of the increasing dietary rapeseed oil level on the sum of fatty acids in pyloric caeca (PI), liver (LI), mesenteric fatty tissue (Mes) and on the sum of absorbable fatty acids in the feed (Feed) (Unit: g/kg feed or tissue), for small (0) and large (1) fish. The legend in the figure presents the best model for the data. The curves show estimated regression on dietary rapeseed oil level with indication of 95% credible intervals for the posterior means, allowing comparison of the results: lines and parts of lines for which the 95% range do not overlap differ significantly.

Figure 6
Figure 6

a. Effects of the increasing dietary rapeseed oil level on the relative level of saturated and mono-unsaturated fatty acids (% of sum of fatty acids, Area %) indicated on the left above the graphs, in absorbed fat, pyloric caeca (PI), mesenteric fatty tissue (Mes), and liver (Unit: % of sum fatty acids), representative for small (0) and large (1) fish. The legend in the figure indicates whether fish size clearly affected the results and the best model selected for the data. For fatty acids not clearly affected by fish size, average cures are presented. For fatty acids showing significant effects of fish size, separate curves are shown. The curves show the estimated regression lines with indication of 95% credible intervals for posterior means. The curves show estimated regression on dietary rapeseed oil level with indication of 95% credible intervals for the posterior means allowing comparison of the results: lines and parts of lines for which the 95% range do not overlap differ significantly. b Effects of the increasing dietary rapeseed oil level on the relative level (% of sum of fatty acids, Area %) of poly-unsaturated fatty acids indicated on the left above the graphs, in absorbed fat, pyloric caeca (PI), mesenteric fatty tissue (Mes), and liver (Unit: % of sum fatty acids), representative for small (0) and large (1) fish. The legend in the figure indicates whether fish size clearly affected the results and the best model selected for the data. For fatty acids not clearly affected by fish size, average cures are presented. For fatty acids showing significant effects of fish size, separate curves are shown. The curves show the estimated regression lines with indication of 95% credible intervals for posterior means. The curves show estimated regression on dietary rapeseed oil level with indication of 95% credible intervals for the posterior means allowing comparison of the results: lines and parts of lines for which the 95% range do not overlap differ significantly.

Figure 6
Figure 6

a. Effects of the increasing dietary rapeseed oil level on the relative level of saturated and mono-unsaturated fatty acids (% of sum of fatty acids, Area %) indicated on the left above the graphs, in absorbed fat, pyloric caeca (PI), mesenteric fatty tissue (Mes), and liver (Unit: % of sum fatty acids), representative for small (0) and large (1) fish. The legend in the figure indicates whether fish size clearly affected the results and the best model selected for the data. For fatty acids not clearly affected by fish size, average cures are presented. For fatty acids showing significant effects of fish size, separate curves are shown. The curves show the estimated regression lines with indication of 95% credible intervals for posterior means. The curves show estimated regression on dietary rapeseed oil level with indication of 95% credible intervals for the posterior means allowing comparison of the results: lines and parts of lines for which the 95% range do not overlap differ significantly. b Effects of the increasing dietary rapeseed oil level on the relative level (% of sum of fatty acids, Area %) of poly-unsaturated fatty acids indicated on the left above the graphs, in absorbed fat, pyloric caeca (PI), mesenteric fatty tissue (Mes), and liver (Unit: % of sum fatty acids), representative for small (0) and large (1) fish. The legend in the figure indicates whether fish size clearly affected the results and the best model selected for the data. For fatty acids not clearly affected by fish size, average cures are presented. For fatty acids showing significant effects of fish size, separate curves are shown. The curves show the estimated regression lines with indication of 95% credible intervals for posterior means. The curves show estimated regression on dietary rapeseed oil level with indication of 95% credible intervals for the posterior means allowing comparison of the results: lines and parts of lines for which the 95% range do not overlap differ significantly.

Figure 7
Figure 7

The curve in the figure illustrates the dose–response relationship between dietary choline level and intestinal steatosis, as previously published by Hansen et al.. The dotted lines illustrate the strategy used for estimation of effect on choline requirement in the present study. The increase in rapeseed oil from 0 to 24% increased the score by 1.7 units (orange line) in the large fish. The figure indicates that this shift corresponds to a shift in choline requirement of about 650 mg/kg. The shift in the small fish was 1.2, corresponding to a shift of 450 mg/kg (not illustrated). The difference between the two fish sizes, when fed the lowest rapeseed oil level, was 0.8 units (blue line), i.e. lower in the small than the large fish, corresponding to a difference in choline requirement of about 250 mg/kg. At the highest rapeseed oil level, the difference was 0.3, corresponding to a difference in choline requirement of about 100 mg/kg (not illustrated). As there were great differences in the experimental conditions between Hansen et al. experiment and the present, these estimates should be taken as indications of magnitude of effects rather than accurate estimates.

Similar articles

References

    1. Hansen, A. K. G. et al. Choline supplementation prevents diet induced gut mucosa lipid accumulation in post-smolt Atlantic salmon (Salmo salar L.). BMC Vet. Res.16, 1–15 (2020). 10.1186/s12917-020-2252-7 – DOI – PMC – PubMed
    1. Krogdahl, Å. et al. Choline and phosphatidylcholine, but not methionine, cysteine, taurine and taurocholate, eliminate excessive gut mucosal lipid accumulation in Atlantic salmon (Salmo salar L.). Aquaculture528, 735552 (2020).10.1016/j.aquaculture.2020.735552 – DOI
    1. Hansen, A. K. G. et al. Dose-response relationship between dietary choline and lipid accumulation in pyloric enterocytes of Atlantic salmon (Salmo salar L.) in seawater. Br. J. Nutr.123, 1081–1093 (2020). 10.1017/S0007114520000434 – DOI – PubMed
    1. Penn, M. Lipid malabsorption in Atlantic Salmon—The recurring problem of floating feces (2011).
    1. Zeisel, S. Choline, other methyl-donors and epigenetics. Nutrients. 9(5), 445 (2017). 10.3390/nu9050445 – DOI – PMC – PubMed

MeSH terms

Substances

BLACK HAWK: Best lions mane supplement for dads

Read the original publication:

Effects of dietary fish to rapeseed oil ratio on steatosis symptoms in Atlantic salmon (Salmo salar L) of different sizes – PubMed