Vince McDonagh

The right kind of fat

Omega-3 oils really do make a difference in salmon feed, research has shown

BY VINCE MCDONAGH

NEW 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They found that limited access to fishmeal and fish oil for use in salmon feed means that some ingredients have been replaced by plant-based raw materials, leading to a lower content of marine omega-3.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 38

“Researchers and the industry have received the instruments they need to develop the feed of the future”

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

Top: Nofi ma feed technology centre Top right: Fish feed Above: Bente Ruyter handles the transi� on into the sea. One of the recipes was close to commercial quality, while others had adjusted levels of commercial quality, while others had adjusted levels of amino acids, omega-3, minerals and salts in various amino acids, omega-3, minerals and salts in various combina� ons. combina� ons. None of the adjusted recipes had an eff ect on None of the adjusted recipes had an eff ect on robustness, survival or growth when compared to the robustness, survival or growth when compared to the commercial-quality feed. commercial-quality feed. The researchers think this may indicate that the freshwater feed already on the market today covers a salmon’s nutri� onal needs in this phase of its life. The content of the long-chain fa� y acids is o� en stated as the sum of EPA + DHA, without men� oning stated as the sum of EPA + DHA, without men� oning the ra� o between the two fa� y acids, but it has long the ra� o between the two fa� y acids, but it has long been thought that DHA is the more essen� al. been thought that DHA is the more essen� al. But FHF says another experiment, led by the Ins� tute But FHF says another experiment, led by the Ins� tute of Marine Research, has shown that EPA has a unique and of Marine Research, has shown that EPA has a unique and special role in the immune system of Atlan� c salmon, especially special role in the immune system of Atlan� c salmon, especially when they are exposed to viral infec� on.

The reason for this study is because there is the poten� al to add a lot more DHA and less EPA to some feeds. It is important to fi nd out whether it would be suffi cient to add DHA from these sources or whether a small propor� on of EPA could have unforeseen consequences. While the studies were not carried out on live fi sh, they did show that EPA is very important for salmon.

A high level of marine omega-3 in a fi sh’s diet is likely to improve its quality, FHF maintains, and this was most evident in the sea phase.

It also turns out that when it comes to maintaining fi sh health, quality and welfare, salmon have a greater need for essen� al fa� y acids than was thought only a few years ago.

As supplies of fi shmeal and fi sh oils are limited, however, the study concludes, the industry should look for alterna� ve sources of omega-3 that are rich in both DHA and EPA. These sources could include yeast, microalgae, krill or gene� cally modifi ed plants.

Bente Ruyter, a senior researcher at Nofi ma, believes that in the future the industry will be able to fi nd a number of addi� onal sources.

She adds: “We know that the feed industry is already well under way with this job and has included the results of these studies in their new feed recipes. In fact, the omega-3 levels in feed are now higher than when we did our studies.” FF

MINISTER OPENS “WORLD CLASS” FISH FEED RESEARCH CENTRE

NOFIMA’s reputa� on as a global leader in aquaculture research received a major boost last month with the opening of its new Aquafeed Technology Centre by Norway’s Fisheries Minister, Odd Emil Ingebrigtsen.

Scien� sts at the £3m centre say it will enable them to work together on one of their main objec� ves: developing more environmentally friendly fi sh feed. With more than 70%of greenhouse gas emissions produced by the salmon sector coming from fi sh feed, it makes the task all the more urgent. “Today, researchers and the industry have received the instruments they need to develop the feed of the future,” said Ingebrigtsen before cu� ng the ribbon.

He made it clear that the work conducted at the centre has been based on open research. This means that all industry players will have access to the results and therefore the pace of innova� on can be increased.

He added: “This world-class centre is the result of targeted investment over many years. The centre will be made accessible to researchers from all countries

Research Director Mari Moren at Nofi ma is pleased with all the ini� a� ves, but was clear in her message: “It is not as simple as just removing soy and then adding a new raw material.”

She explained: “Firstly, research must be conducted on the suitability of raw materials in the feed pellet, because feed produc� on is rather complex. We have to start in the right place. Sustainable raw materials must fi rst be processed in the correct manner before they can be used in salmon feed. Once this is in place, suppliers can start large-scale produc� on.”