Norway spruce extracts (NSEs) as bioactive compounds in novel feeds: Effect on intestinal immune-related biomarkers, morphometry and microbiota in Atlantic salmon pre-smolts
Sérgio D.C. Rocha, Byron Morales‐Lange, Ruth Montero, Dawit Teklay Okbayohanese, Kathiresan Purushothaman, Charles McL. Press, Liv Torunn Mydland, Margareth Øverland
Abstract
Compounds from woody biomass are promising candidates as feed additives to improve fish health and welfare of Atlantic salmon (Salmo salar) during the productive cycleng. Thus, conidendrin- and isorhapontin-based extracts (NSEs) from Norway spruce (Picea abies) were evaluated at different levels in a four-week trial. A commercial-like diet (D1) was supplemented with 0.2% of a commercial β-glucan (D2) or with NSEs at 0.02%, 0.1% and 0.2% (D3-D8). No significant differences were found in growth, intestinal morphometry and microbiota at the genus level. Immune-related biomarkers in distal intestine from D5 and D6 indicated an activation of a pro-inflammatory response by the up-regulation of il1b, as in D2. Interestingly, isorhapontin-based extract at higher inclusion level (D8), showed a down-regulation of both pro- and anti-inflammatory- genes, suggesting maintenance of homeostasis. These results showed the importance of source and inclusion levels of bioactive compounds on the regulatory balance associated with fish immune response.