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ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #379031
Research Project: Integrated Research Approaches for Improving Production Efficiency in Rainbow Trout

Location: Cool and Cold Water Aquaculture Research

Title: Replacing fish oil and astaxanthin by microalgal sources produced different metabolic responses in juvenile rainbow trout fed 2 types of practical diets

Author
item ZHU, SHANLI - Cornell University
item PORTMAN, MARK - Us Fish And Wildlife Service
item Cleveland, Beth
item MAGNUSON, ANDREW - Cornell University
item WU, KIM - Cornell University
item SEALEY, WENDY - Us Fish And Wildlife Service
item LEI, XIN GEN - Cornell University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2020
Publication Date: 12/21/2020
Citation: Zhu, S., Portman, M., Cleveland, B.M., Magnuson, A.D., Wu, K., Sealey, W., Lei, X. 2020. Replacing fish oil and astaxanthin by microalgal sources produced different metabolic responses in juvenile rainbow trout fed 2 types of practical diets. Journal of Animal Science. 99(1):1-14. https://doi.org/10.1093/jas/skaa403.
DOI: https://doi.org/10.1093/jas/skaa403

Interpretive Summary: Finding alternatives to the fish oil in aquafeeds is essential for sustainable expansion of the aquaculture industry. Algal-based ingredients show potential as a fish oil replacement, particularly since they can be engineered to contain high levels of essential omega-3 fats. This study investigated whether dietary fish oil can be replaced by a high-omega-3 algal meal in a rainbow trout diet without negative consequence on growth and fillet quality. In addition, an algal-based astaxanthin was evaluated to determine if this pigment-inducing feed additive can replace synthetic astaxanthin. Results indicate that up to 50% of fish oil and 100% of synthetic astaxanthin can be replaced by these algal-based ingredients without negative effects on growth performance and fillet omega-3 content. These findings indicate the potential of algal as a sustainable feed ingredient to support the expansion of aquaculture without increasing reliance upon marine-derived oils.

Technical Abstract: Finding alternatives to fishmeal and fish oil aquafeed ingredients is essential for sustainable expansion of the aquaculture industry. These studies were conducted to evaluate the effects of replacing fish oil with a DHA-rich algal meal at three different inclusion levels (0%, 50%, and 100%) in combination with synthetic astaxanthin (SA) or a high-astaxanthin microalgal (AA) in juvenile rainbow trout (Oncorhynchus mykiss). This 3 X 2 factorial design was performed in two independent trials that used either a fishmeal (FM) or plant meal (PM) base diet. In the PM diet series, only 100% replacement of fish oil with algal meal had a negative effect on final fish weight and food conversion ratio (P< 0.001) while reductions in growth performance occurred at both 50% and 100% replacement in the FM diet. A significant interaction with astaxanthin type and final fish weight was observed wherein fish fed AA weighed less than fish fed SA (P< 0.05). In both the FM and PM diet series, muscle docosahexaenoic acid (c22:6n-3, DHA) content was similar between the 0% and 50% replacement diets, although DHA decreased (P<0.001) with 100% fish oil replacement. Muscle eicosapentaenoic acid (c20:5n-3, EPA) progressively decreased with increasing levels of fish oil replacement (P < 0.001). Replacement of SA with AA did not affect muscle and liver fatty acid content (P>0.05). In conclusion, algal meal, with AA, can replace up to 50% fish oil in a PM diet without negatively affecting juvenile rainbow trout growth performance and fillet DHA content.