Researchers in Canada have found that different species of salmon have varying levels of susceptibility to soybean meal-induced enteritis (SBMIE).

In a recently completed study, three species of salmon were fed soy-based diets to asses and compare the effects of soybean meal on intestinal morphology, inflammation and microbiome composition.

“Solvent-extracted soybean meal (SBM) is an attractive protein source for fish feed because of its high protein content, favorable amino acid profile, and low cost. In Atlantic salmon (Salmo salar), SBM at low levels causes soybean meal-induced enteritis (SBMIE). Few studies have been done with SBM in Pacific salmon, and none of those have included intestinal inflammation analysis.”

During a three-week feeding trial, Chinook salmon (Oncorhynchus tshawytscha), Atlantic salmon (Salmo salar), and pink salmon (O. gorbuscha) were fed either a 20% soybean diet or a control diet containing fishmeal. Results found that Chinook were more susceptible to SBMIE than Atlantic, whereas pink salmon were not susceptible to SBMIE at the levels tested.

 “After one week on the soy diet, Atlantic and Chinook salmon showed increased submucosa thickness in the distal intestine compared to the fish fed on the fishmeal diet. Intestinal inflammation in these species increased over time, and after 3 weeks on the SBM diet, intestinal inflammation was most severe in Chinook salmon. In contrast, pink salmon only showed a slight increase in submucosa thickness after three weeks on the SBM diet, and no significant increase in inflammatory cellinfiltrate.” 

“Sequence-based analysis of the intestinal microbiome showed a significant difference in overall microbiome composition between species, but did not show an effect of the SBM diet on microbiome diversity or composition in any of the three salmon species.”

The study results, published in the Journal of Aquaculture, indicate that the use of soybean meal in salmonid diets requires species-specific research on inclusion rate and feeding regimes.