A bioactive extract rich in triterpenic acid and polyphenols from Olea europaea promotes systemic immunity and protects Atlantic salmon smolts against furunculosis

Deciphering the dietary immunomodulatory effects of a feed additive rich in triterpenic compounds and polyphenols (AQUOLIVE®, NATAC Biotech SL, Spain) on the systemic immune response and disease resistance of Atlantic salmon (Salmo salar L.) smolts. Transcriptomic analysis was conducted in order to determine the differences on gene expression level between these two dietary strategies at head kidney specific level. The experimental design included two conditions: (1) fish fed basal diet with no phytogenic feed additives (AQUOLIVE®) (control); (2) fish fed 0.15% inclusion of AQUOLIVE® (10% olive bioactive compounds, 8.0% triterpenic acid and 2% polyphenols) from olive fruit extract. After 133 days of feeding trial, total RNA were extracted invidually from Atlantic salmon (S. salar) head kidney fed basal diet or an experimental diet containing 0.15% inclusion. Total RNA samples were grouped into 3 pools (n= 6 fish for each condition). The transcriptomic analysis was done following a reference design using the control diet group as reference.