Effects of soybean and sunflower meals on the growth, feed utilization, and gene expression in two Canadian strains of juvenile Arctic charr (Salvelinus alpinus)

Authors: SMITH, AMANDA - University Of Guelph; DUMAS, ANDRE - Coastal Zones Research Institute Inc; YOSSA, RODRIGUE - Coastal Zones Research Institute Inc; Overturf, Kenneth - Ken; BUREAU, DOMINIQUE - University Of Guelph

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2017
Publication Date: 9/7/2017
Citation: Smith, A.A., Dumas, A., Yossa, R., Overturf, K.E., Bureau, D.P. 2017. Effects of soybean and sunflower meals on the growth, feed utilization, and gene expression in two Canadian strains of juvenile Arctic charr (Salvelinus alpinus). Aquaculture. 481:191-201. https://doi.org/10.1016/j.aquaculture.2017.08.038.
DOI: https://doi.org/10.1016/j.aquaculture.2017.08.038

Interpretive Summary: The effects of varying levels of soybean meal (SBM) and sunflower meal (SFM) were investigated on growth, nutrient utilization, and the expression of genes related to the pro-inflammatory response in the intestine and spleen of two commercial Canadian strains (strain 1 and strain 2) of Arctic charr. Five experimental diets with increasing levels of SBM or SFM were fed for 84 days to two Canadian strains of Arctic charr. Feeding these diets resulted in no differences in growth rate between the two strains. Increased levels of plant proteins in the diet negatively affected feed efficiency in both strains of fish. The effect of either soybean meal or sunflower meal was significant on the expression of certain inflammatory genes in the intestine; these expression levels were higher in feeds with SBM than with SFM. The effect of plant ingredient levels in the feed was also significant on specific inflammatory genes in the spleen. Feed intake, feed efficiency, whole body crude protein, lipid, and gross energy, of the fish were significantly affected by genetic strain. Strain 2 exhibited higher levels of feed efficiency and carcass crude protein content and lower carcass lipid content. The difference in feed efficiency, protein and lipid content for the two genetic strains of charr may indicate variations in efficiency for protein and lipid utilization.

Technical Abstract: The effects of graded levels (0-20% total dietary inclusion) of commercial, solvent-extracted soybean meal (SBM) and expeller sunflower meal (SFM) were investigated on growth, nutrient utilization, and pro-inflammatory gene expression in the distal intestine and spleen of two commercial Canadian strains (strain 1 and strain 2) of Arctic charr. Five experimental diets with increasing inclusion of SBM or SFM were fed for 84 days to two Canadian strains of Arctic charr (initial body weight = 9g/fish). Feeding these diets resulted in no differences in growth rate (measured as final weight or thermal-unit growth coefficient, TGC) in the two strains. Increased inclusion level of plant proteins negatively affected FE (P<0.0001) with effects most commonly observed in groups fed SBM-based diets. The effect of the ingredient was significant (P<0.05) on PXR gene expression in the distal intestine; PXR expression was higher with SBM than with SFM. The effect of the inclusion level of plant ingredients was significant (P<0.05) on IL-Iß gene expression in the spleen. Feed intake, FE, NRE, ERE, whole body crude protein, lipid, gross energy, and organo-somatic indices (P<0.05) were significantly affected by genetic strain examined. Strain 2 exhibited higher FE and carcass crude protein content and lower carcass lipid content. The difference in FE, protein and lipid content for the two genetic strains of charr may indicate variations in efficiency for protein and lipid utilization, with a potential protein-sparing effect of dietary lipid noted in strain 2.