SASYA’S FISHMEAL ALTERNATIVE FOR RAINBOW TROUT FEED

The rapid global growth in fish farming and limited supply of fish meal (FM) have generated reduced inclusion of FM in compound feed for finfish and increased substitution with alternative protein sources. Sasya, LLC is a U.S. corporation that has developed a proprietary method to produce single cell protein (SCP) product for use in feeds for farmed fish. The resulting SCP was shown to have a similar nutrient profile as wild-capture fishmeal. Aim of the present study was to evaluate the nutritional value of Sasya's SCP as an alternative protein source for Rainbow trout (Oncorhynchus mykiss). Thirty rainbow trout fingerlings fish (4.99 ± 0.20g) were stocked into each of 9, 145-L tanks. Each tank was supplied with 8 L/min of constant temperature (15 °C) spring water supplied by gravity to the fish-rearing laboratory. Three iso-nitrogenous (470 g/kg crude protein) and iso-energetic (5150 kcal/kg) diets: Diet 1: Fish meal control (30% FM); Diet 2 (L-SCP_FM): Low SCP (containing 24% FM and rest 6% FM replaced by SCP) and Diet 3 (H-SCP_FM): High SCP (containing 18% FM and rest 12% FM replaced by SCP) were fed to rainbow trout for nine weeks. Each diet was fed by hand to three replicate tanks of fish to apparent satiation. In a completely randomized design, each of the three experimental diets was randomly assigned to triplicate tanks within the laboratory system to account for any tank position effects.

In vivo digestibility of Sasya's SCP was determined when fed to rainbow trout as part of a complete diet. The apparent digestibility coefficients of SCP for dry matter, crude protein, lipid and energy were 60, 80, 93 and 74% respectively. At the end of feeding trial (9 weeks) growth performance (final weight: 69 - 71 g) and feed utilization parameters (FCR: 0.91 - 0.94) did not differ significantly among the groups. Dietary treatments have significant effects on crude fat and gross energy content of whole body of fish, higher value was observed in the diet 3 (highest inclusion of SCP) fed group than other groups. Whereas, there was no significant impacts on protein and amino acids content of fish. A similar trend (no significant difference) was observed for the protein metabolism enzymes (alanine transaminase and aspartate transaminase) activity in serum of fish. Majority of the hepatic key genes involved in fatty acid metabolism were higher in SCP fed groups (diets 2 and 3) than control (fish meal) group, such as Carnitine Palmitoyltransferase-1b (CPT1b), fatty acid delta 5/6 desaturase (FADS5/6) and fatty acid elongase 5. High expression of these genes indicates that increased in synthesis of omega-3 fatty acids in fish therefore fatty acids compositions of whole body of fish are being analyzed and will be presented. Overall, quality of single cell protein is as good as fish meal, therefore such product could enlarge the portfolio of alternative protein sources that can be used in fish diets and open a new market opportunity for use of a new feed resource in the feed industry.