In a research it is found that marine nutrients of immense value to the farmed fish can be better exploited. Fishmeal is a valuable source of protein but the producers of fish prefer to feed less fishmeal owing to a combination of price, sustainability and flexibility. Therefore, increasingly more fishmeal is being replaced with protein-rich plants.
Experts believe that plants cannot completely replace marine ingredients without affecting the performance of the farmed fish. Consequently, Nofima Ingrediens is trying a different approach: by increasing the nutritional value of the fishmeal, less fishmeal is needed in the feed than before.
Some of the substances that make marine raw ingredients valuable are separated with water in the production of fishmeal. This water is called stickwater. To exploit this stickwater, it is highly concentrated and transferred back to the fishmeal. Katerina Kousoulaki, who together with Anders Aksnes at Nofima Ingrediens in Bergen has headed the project, said that in the production of fishmeal of high quality, all stickwater is transferred back.
The scientists expressed that they have observed how large the growth gain was for salmon receiving feed with different contents of stickwater, and feed in which part of the fishmeal was replaced with plant meal. A trial was carried out in which juvenile salmon in saltwater received eight different feeds. One of the feeds was commercial and contained 30 percent fishmeal. The remaining seven feeds contained just 10 percent fishmeal, but contained stickwater equivalent to that in the commercial feed and up to 200 percent over and above that found in commercial feed.
After ten weeks of feed the results show how decisive tiny marine components are in salmon feeds containing much plant material. Increased use of stickwater will mean that the feed producers can use more protein raw materials from the plant kingdom than previously.
