Publisher: Nofima AS
Number of pages: 47
International Standard Numbers:
Open Access: none
Atlantic salmon (ca 180 g) were challenged with PRV (HSMI virus) or SAV3 (PD virus) after feeding 18 weeks on four different diets (A: Low EPA/DHA control, B: medium EPA, C: high EPA, D: high DHA). The fish challenged with PRV was given control feed and high EPA feed after challenge, whereas those challenged with SAV3 only received control feed.
There was reduced HSMI pathology in the heart (myocardium) of fish fed high EPA diet, and the difference was significant (P<0.05) at 6 weeks post challenge (wpc). This was supported by microarray analyses showing massive down-regulation of immun genes in the heart. In parallel to the pathological changes in the heart, there was a development of microvesicular steatosis in liver, apparently associated to diet and not to infection.
There were no effects of pre-challenge feeding in this study, partly explained with high feed intake after challenge, diluting initial differences in tissue fatty acid composition. Also, the fish in the PD challenge trial had feed intake similar to uninfected fish, so the effects of feeding before challenge were diluted. Despite of this, there were interesting trends, particularly related to improved recovery from disease, which should be followed up.