Feed
The right kind of fat Omega-3 oils really do make a difference in salmon feed, research has shown BY VINCE MCDONAGH
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EW research by Nofima, Norway’s highly respected Food Research Institute, has confirmed that increased levels of omega-3 in salmon feed can lead to healthier and stronger fish. Fish with more omega-3 in their diet are also better able to cope with challenges such as stress and infection, which is especially important during the sea phase of their life cycle. Scientists at the organisation have carried a recent detailed study into the content of feed and how it impacts on salmon. They found that limited access to fishmeal and fish oil for use in salmon feed means that some ingredients have been replaced by plant-based raw materials, leading to a lower content of marine omega-3. This, the study found, has changed the fatty acid composition in the salmons’ tissue and organs. The study has been supported financially by FHF, the Norwegian fisheries and aquaculture research fund, and led by Nofima’s “OptiHealth” programme researchers. They looked closely at the salmons’ need for omega-3 fatty acids and asked whether there is a need to change recommendations regarding feed composition. FHF says salmon today are exposed to more handling and challenging environmental conditions, adding that fat levels and specific fatty acids play key a role in many biological functions. This means that if the composition of the fat in feed is altered, it can affect both growth, muscle quality and the health and robustness of fish. Different diets were tested throughout the project. Salmon were given
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feed in which the amount of omega-3 (ie EPA and DHA) varied from 1% to 3.5%. The highest level corresponded to a diet with about 50% fish oil. “Overall, the results showed that the higher the omega-3, the better the salmon performed in every way,” FHF declares. The fish showed signs of improved disease resistance and lower mortality. And they had fewer melanin spots, improved muscle quality and better growth, at least in their sea phase. The results also showed, however, that feeding salmon with a vegetable-oil-rich diet delivered improved growth in the freshwater phase, although it did not make the fish better equipped for the seawater cycle. It poses the question: “Can adjustments in the feed recipe in the freshwater phase make the fish better able to withstand the seawater release?” Norwegian fish farms generally suffer a loss of around 16-17% in the sea phase, with a large proportion occurring immediately after the transfer. A project led by the Norwegian Institute of Marine Research has tested different feed recipes in the freshwater phase and studied how salmon
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13/09/2021 15:46:46
