Insect meal is becoming a more common ingredient as scale increases, but currently, not all of the insect is used in aquafeeds. Insect larvae are processed into three fractions: oil, meal and stickwater. The meal is rich in protein, and stickwater is thought to be rich in bioactive components. The properties these fractions have in fishmeal are already well known. From a bioeconomic perspective, it is therefore desirable to test and utilize this resource from insects in salmon feed.
In a recent trial, Nofima researchers tested the latter two fractions (insect meal and stickwater) in feed for salmon parr. Insects were produced and processed at Innovafeed’s facility in France.
Nofima scientists and a master’s student at NMBU measured the effect on digestion and growth in juvenile fish during the growth phase from approximately 20 to 85 grams.
At Nofima in Bergen, feed technologists produced trial feed in which they added 10% insect meal and different levels of stickwater from insects. The insect ingredient was compared in feed with similar protein content and replaced half of the fishmeal in a control diet. The feeds were given to salmon parr at Nofima’s Sunndalsøra research station. The goal was to find any differences in digestion and growth in fish that were fed feed based on insects with an increasing content of stickwater.
Nofima’s trials show that salmon parr like feed that contains insect meal and grow just as well with stickwater in the feed as without. Parr is the stage between fry and smolt. Credits: Terje Aamodt, Nofima
Grew just as well
The trials showed that salmon grew just as well and had just as good digestion when their diet contained stickwater from insects. With 10% insect meal in the feed, fish also grew just as well as fish that received the control feed.
“The trial shows that there is no problem in salmon having at least 10% insect meal in their feed. Based on the positive effects of the stickwater fraction from fishmeal, we cannot rule out that this fraction from insects would have had a positive effect under other conditions. In any case, it is an important side stream to safeguard for the optimal utilization of insects as feed for fish,” said Nofima’s Andre Sture Bogevik.
In the project, the level of the mineral manganese was also investigated. The EU has threshold values for the content of manganese in the finished feed for farmed fish, and insects contain naturally high levels of this. The trial showed that the fish excrete the mineral and do not absorb more in the body than if the meal did not contain high levels of manganese. Nor did the mineral lead to any deformities or have a negative impact on growth.
Aqua director at Innovafeed, Elin Kvamme, is satisfied with the result. “We are delighted to observe results aligned with the internal research we have carried for the past years at Innovafeed. The growth results pave the way for the widespread use of insect protein in the salmon industry, as a sustainable, traceable, and performing ingredient.”
Research on low-trophic raw materials
The research was conducted in the Millennial Salmon project, which is funded by the Research Council of Norway. The research is published in the master’s thesis of Erika Marie Hanson at the Norwegian University of Life Sciences (NMBU) from 2022 entitled Effects on growth and welfare of Atlantic salmon parr, feed diets with 10% BSFL meal, with different inclusions of BSFL stickwater.
Nofima senior scientist Katerina Kousoulaki is the project manager for the Millennial Salmon project, which focuses on optimizing and using heterotrophic microalgae and insect meal as replacements for large parts of fish oil and soy in salmon feed.