SUGAR KELP Saccharina latissima CONCENTRATE FOR FISH FEED

With the emergence of kelp aquaculture in the United States, there is an opportunity to use off-product plants in marine fish feeds.  Off-product kelp is generally mature plants which are approaching senescence and unsuitable for human consumption.  A feeding trial was conducted with sablefish (Anoplopoma fimbria), incorporating late season sugar kelp in plant based feeds at 2.5%, 5%, and 7.5%.  Results demonstrated a significant increase in feed consumption with sugar kelp addition.  Feed conversion ratio was reduced by kelp addition.  2.5% kelp and 5% kelp treatments initially increased growth before plateauing at 5% kelp addition.  

Feed pellets extruded with 7.5% sugar kelp were harder and less soluble than the 0% kelp control feed.  Feed extruded with 10% sugar kelp solids could not be produced with consistency and exhibited glassy properties.  In an effort to increase the feed efficiency and protein availability of the kelp feeds, a process was developed using 0.3 M phosphoric acid in a 20:1 w/w ratio with dried sugar kelp powder to reduce the ash and alginate content and increase protein concentration.  The acid treated sugar kelp is less hygroscopic and has more consistent behavior in the production of extruded feeds.  Development of this process could create a market for low value sugar kelp as fish feed.  Details of the processing and effects on pellet solubility will be described.

95% solids

25% protein (N x 6.25)