The continuous growth of aquaculture places a growing demand on alternative sources for fish oil (FO) and fishmeal (FM) in aquafeeds. Certain microorganisms provide a potential sustainable replacement for FO and FM due to their content of omega-3 long-chain polyunsaturated fatty acids, which are essential for fish health. Salmon feeding trials were conducted to determine the effects of replacing FO and FM with oil and biomass from different microorganisms. The first trial replaced FO with a microbial oil (MO) derived from Schizochytrium. The second reduced FO and replaced FM with algal biomass (AB) derived from Pavlova. Growth was unaffected when microbial products replaced dietary fish oil and fishmeal; however, lipid profiles were altered. With MO, linoleic acid and α-linolenic acid were present in low proportions, and DHA was present in very high proportions in the cellular membrane, especially in muscle tissue. In addition to cholesterol in muscle tissue, cholestanol, campesterol, stigmasterol, dinosterol and 24-methylpavlovol were detected in salmon. With AB, DHA was present in high proportions in tissues of all dietary treatments, especially in cellular membranes. Stable isotope data indicated a direct integration of EPA and DHA and not biosynthesis from its precursor ALA. Growth performance, lipid class composition, phospholipid fatty acid composition, and compound specific stable isotope analysis all suggest that salmon grown on microbial-based diets digested and utilized nutrients well, and directly incorporated critically important fatty acids into their tissues.

Primary Presenter: Chris Parrish, Memorial University of Newfoundland (cparrish@mun.ca)

Authors:

Nigel Guerra, Memorial University of Newfoundland  ()

Judy Perry, Memorial University of Newfoundland  ()

Minmin Wei, Dalhousie University  ()

Stefanie Colombo, Dalhousie University  (SColombo@dal.ca)