The project will study the effect of immune-stimulating feed additives to combat salmon lice. The project is scheduled to be completed by mid 2011. The awarded funds will be used to further document that it is possible to modulate the salmon’s natural immune defense system against lice through the use of feed ingredients from baker’s yeast as well as describe the mechanisms behind the effect.
The reason for Biorigin’s and BUC’s joint application is the growing problem related to salmon lice. Salmon lice, Lepeophtheirus salmonis, has always been present in wild salmon. However, as the salmon farming industry has grown significantly during the last 10-15 years, the number of potential hosts for lice has multiplied equally as fast. As a consequence, the lice population has become significantly larger, and in some regions also impacts wild stocks.
Managing Director for Biorigin Scandinavia, Dr. Rolf Nordmo, says that until now, chemical treatments have been the main way to reduce the salmon lice problem. These chemicals are either added to feed or used to dip the fish in. Dr. Nordmo continues that “one of the main challenges the salmon farming community is facing is that the salmon lice develops resistance to these chemical treatments, causing the industry to face major problems related to fighting the increasing lice problem”. The alternative for many farms currently is to dip all their fish in hydrogen peroxide as the only real treatment option.
According to Rolf Nordmo, the project’s primary goal is to research and further document how specific ingredients added to feed affect the salmon’s ability to fight salmon lice. The salmon’s own immune system has mechanisms to protect itself from parasites. By strengthening the immune system, the salmon will become much better prepared to fight lice. Counting will be used to measure the effect on the copepodids/salmon lice, two and four weeks after being infected.
The salmon’s mucus membrane consists of, among other things, anti-pathogen enzymes. The project will also study the mucus membrane before and after feeding the test ingredients, as well as after the fish is infected by copepods. Salmon lice primarily consist of chitin and chitin preventers are currently used to treat infestations. If any of the test ingredients increase the amount of lysozyms or chitinase, it is reason enough to believe that it will increase protection against copepodids/salmon lice. The amount of mucus, blood and organ parameters between the diets in the test will also be studied.
By using biochemical methods, we will try to find and indentify proteins that have an increased concentration after feeding the test feed and after infecting the fish with copepods. This would be a first step to understanding how the feed components function.
The goal of the project Biorigin and BUC is starting is to document that it is possible to modulate salmon’s natural immune system against lice through the use of feed ingredients from baker’s yeast. A series of feed trials will be conducted using different diets containing ingredients from baker’s yeast. Mucus tests will be taken during the feeding period and at the end the fish will be infected with copepodids from salmon lice.
Biorigin produces natural feed ingredients based on yeast (Saccharomyces cerevisiae) and has previously developed a product, MacroGard®, which is a high grade beta-1.3/1.6-glucan from a related strain of baker’s yeast. Earlier, it has been shown and described that MacroGard® is effective against lice, but what the underlying mechanisms are, are still unknown. Researchers think that the fish’s natural defense against lice may be the amount of mucus or substances in the mucus membrane, including unspecified antibodies, enzymes (lysozym, chitinase) or other components which repel the lice. This is a part of the congenital immune system and which is a particularly important barrier against all infections, regardless of its nature.
The project participants expect to document the relationship between the different yeast based feed ingredients’ properties related to:
- Mucus amounts
- Chemical composition of mucus
- Reduced lice infestation after feeding (contamination model)