The use of blue mussels as a n ingredient in fish feed is proposed as one of the solutions to increase access to sustainable raw materials and is especially relevant as a source of marine protein. In Norway, blue mussels may be one alternative to increase the amount of locally produced ingredients for fish feeds. Blue mussels can be cultivated along the Norwegian coastline, and the production potential is considered to be higher than what is relevant for human consumption.
The production of blue mussels has a very low carbon footprint , and the use of blue mussels as a raw material may therefore contribute to an overall lower footprint from the feed . This is also dependent on each processing step to make a feed grade raw material. Processing blue mussel meat into silage is of interest as a method with a lower footprint . However, i nitial short-term studies have shown that the treatment of the blue mussel silage prior to and during feed production can influence the feed utilization and bioavailability of minerals, which will also have an environmental impact . The present study is the third experiment in a series of studies investigating the use of b lue mussel silage in feed for Atlantic salmon.
A six- month feeding study was done with Atlantic salmon (start weight ~ 600 grams) to determine long term effects of using blue mussel silage alone or in combination with blue mussel meal in the feed. The reference feed was designed as a commercially relevant salmon diet containing 10% fish meal . Three experimental diets were made replacing up to half of the fish meal with two levels of blue mussel silage, as well as one feed with a combination of blue mussel silage and blue mussel meal. During the experiment the fish approximately tripled the weight, and no differences were seen in feed intake and weight gain between the experimental groups. There was however a somewhat higher feed conversion ratio (FCR) in the groups given the feeds with the highest inclusion of blue mussels. The results will be presented with a focus on production parameters including feed intake, growth and digestibility, as well as nutrient uptake and welfare parameters . In addition , the environmental impact of the raw materials and feed will be evaluated.