Abstract
Aquafeed manufacturers have reduced, but not fully eliminated, fishmeal and fish oil and are seeking cost competitive replacements. We combined two commercially available microalgae, to produce a high-performing fish-free feed for Nile tilapia (Oreochromis niloticus)—the world’s second largest group of farmed fish. We substituted protein-rich defatted biomass of Nannochloropsis oculata (leftover after oil extraction for nutraceuticals) for fishmeal and whole cells of docosahexaenoic acid (DHA)-rich Schizochytrium sp. as substitute for fish oil. We found significantly better (p < 0.05) growth, weight gain, specific growth rate, and best (but not significantly different) feed conversion ratio using the fish-free feed compared with the reference diet. Fish-free feed also yielded higher (p < 0.05) fillet lipid, DHA, and protein content (but not significantly different). Furthermore, fish-free feed had the highest degree of in-vitro protein hydrolysis and protein digestibility. The median economic conversion ratio of the fish-free feed ($0.95/kg tilapia) was less than the reference diet ($1.03/kg tilapia), though the median feed cost ($0.68/kg feed) was slightly greater than that of the reference feed ($0.64/kg feed) (p < 0.05). Our work is a step toward eliminating reliance on fishmeal and fish oil with evidence of a cost-competitive microalgae-based tilapia feed that improves growth metrics and the nutritional quality of farmed fish.
Highlights
Aquafeed manufacturers have reduced, but not fully eliminated, fishmeal and fish oil and are seeking cost competitive replacements
Fish fed the fishfree diet for 184 days displayed significantly better (p < 0.05) final weight, weight gain, percent weight gain and specific growth rate than fish fed the reference diet, which contained FM and fish oil (FO) levels typically found in commercial tilapia diets (Table 2)
This is the first report of improved feed utilization metrics, including growth, weight gain, specific growth rate, and of beneficial docosahexaenoic acid (DHA) fatty acid profile in Nile tilapia fed a fish-free microalgal diet compared to a commercial feed formulation containing FM and FO
Summary
But not fully eliminated, fishmeal and fish oil and are seeking cost competitive replacements. We combined two commercially available microalgae, to produce a high-performing fish-free feed for Nile tilapia (Oreochromis niloticus)—the world’s second largest group of farmed fish. Our work is a step toward eliminating reliance on fishmeal and fish oil with evidence of a cost-competitive microalgae-based tilapia feed that improves growth metrics and the nutritional quality of farmed fish. Tilapia (dominated by Oreochromis niloticus)—the world’s second top group of aquaculture organisms—is cultured in such large volumes and is such an integral part of human diets across the world, that even low inclusion rates of FMFO in aquafeeds for this species is a substantial portion of global demand of forage fish (Supplementary Table S1)[19]. Elevated levels of n-6 (e.g. linoleic acid) fatty acids from crop oils[23,24] changes the long-chain n-3/n-6 ratio in Scientific Reports | (2020) 10:19328
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
