The State Institute for Agriculture researches protein sources for fish feeding in cooperation with the Fraunhofer Institute Freising and other partners.
Freising - The LfL Institute for Fisheries has researched the suitability of domestic protein feed as a substitute for fish meal.
We have succeeded in formulating a trout feed in which regionally produced rapeseed press cakes reduce the fish meal content by 50 percent.
The so-called rapeseed press cake is left over from the extraction of rapeseed oil, a local product from the field.
For many consumers, environmental protection and enjoyment with a clear conscience are already part of the purchasing decision.
At the same time, fish feed in ponds and aquacultures is essentially based on the use of fish meal.
Due to the strong increase in aquaculture production over the past few decades, the demand for fish meal has risen sharply, although the amount available worldwide cannot be increased.
And although fishmeal is also a by-product of fish processing, the majority comes from wild fish species not caught for human consumption.
Every year around six million tons of fishmeal are produced and shipped all over the world, mainly from South America.
The product
A significant proportion of this is fed to salmon, trout and char in the European salmonid aquaculture.
Press cake is a so-called by-product that arises from the cold pressing of oil seeds.
The ingredients
The gentle treatment gives the oil press cake a high content of natural ingredients.
The high-quality protein profile and the good availability of large, regionally produced quantities make them an interesting and sustainable alternative to fishmeal.
The challenge in the research project was the bitter substances and indigestible raw fibers, which severely limit fish acceptance.
It was found that with a 20 percent share of rapeseed press cake in the feed, there is no loss of performance compared to conventional feed.
The trout were not only growing well, but also in excellent health.
The conclusion
At the end of the project, based on the results obtained so far, a feed was created in which substantial proportions of the fish meal (50 percent) and the soy meal (70 percent) were replaced by local rapeseed cakes.
The use of local press cakes in fish feed is an economically and ecologically sensible alternative to fish meal and soy meal.