June 20, 2008
Norway scientists find bioactive fatty acid improves salmon immune system
Scientists at Norway's aquaculture research centre, Nofima, have developed a salmon feed that enhances the immune defence of salmon, which improves survival rate after a natural outbreak of the IPN virus.
Professor Kjell-Arne Rorvik of Nofima Marine believes this is an example of the fish feed of the future, saying that the best way of enhancing fish feed entails finding and using components that work with the fish's biology so the energy in the feed is better utilised.
Transferring 100-gram salmon or smolt from fresh water to sea water involves a major readjustment which means the smolt have a poor appetite and the intake of energy-rich feed is often inadequate to maintain a good immune defence.
The infectious pancreatic necrosis or IPN virus is one of the aquaculture industry's major health challenges and particularly affects smolt in the first weeks after transfer to salt water.
One way to allow smolt to have enough energy to fight off the disease is to add bioactive fatty acids to the feed.
Tetradecylthioacetic acid (TTA) improves the salmon's ability to oxidize fat to energy.
Scientists Kjell-Arne Rørvik and Magny Thomassen conducted TTA trials on smolt.
The smolt were divided into three groups with each group receiving a different feed, one of which contained small amounts of TTA.
While in the sea cages, the salmon were exposed to a natural outbreak of IPN. As a result, the scientists recorded clear differences between the groups of fish that had consumed different feeds.
The results showed that the fish that consumed the feed containing TTA had a mortality rate of 2.3 percent compared with 7.8 percent for the fish that consumed normal feed.
This is a user-controlled innovation project part funded by the Research Council of Norway in collaboration with BioMar and Thia Medica.
Before TTA may be utilised commercially, it must gain EU approval as an additive.
