Quick M for improved fillet qualit
The correct feed can help reduce dark spots and improve fillet quality. Nofima has estimated that almost 20% of all salmon farmed in Norway suffer from melanin spots, which result in major production losses and extra work. The total loss in value for Norwegian salmon production may actually approach NOK 500 million. BioMar Quick M feed has a tested and proven beneficial effect on melanin spots.
Supplying essential fatty acids and antioxidants through the feed can reduce the incidence of dark spots. Antioxidants guard the body’s own tissue against tissue damage by stabilising the cell membranes and protecting them from harm. Tests involving adding krill to feed have demonstrated a reduction in dark fillet spots of up to 20%.
Krill is known for its capacity to combat the harmful effects of viral infections in the heart caused by the PRV virus. There is evidence to suggest that this is the same virus that triggers melanin spots.
What are melanin spots?
The occurrence of dark spots and melanin spots in salmon meat has increased in recent years. Dark spots affect our perception of the quality of the fillet. As a result, the financial consequences linked to dark spots are significant.
Melanin is a dark brown pigment produced by infection cells known as melanomacrophages. The pigment is not harmful to eat, nor is it harmful to the fish. In fact, it is an antioxidant and the result of the fish’s natural defence against tissue damage. Melanin occurs naturally in fish skin, providing protection against tissue damage when fish are exposed to sunlight. In addition, melanin serves to encapsulate infectious agents that the body is unable to eliminate. The reason why dark spots are considered a problem is first and foremost on account of the aesthetic experience.
Comprehensive research has been conducted to understand the root cause of these spots, and thus to find ways to reduce their appearance. ‘Dark spots’ is an umbrella term for several types of spot: blood spots and brown-black spots with a varying content of melanin.
Research indicates that they start out as blood spots and then pass through a healing process that involves scarring and a gradual accumulation of melanin. The dark spots are probably the result of a slowly developing infection, and there is much evidence to suggest that the PRV virus that appears in both wild and farmed salmon can produce melanin deposits in fillets.
Spots are expensive
It is estimated that this problem affects almost 20% of all salmon produced in Norway, and that it results in appreciable production losses – also in the form of the extra work required to trim fillets with pigment anomalies, and the need to discard ruined muscle mass.
The level of seriousness of the dark spots depends on where they are positioned in the fillets and how big they are. Spots on the belly are less problematic than spots on the back as they are easier to trim off, and large spots are naturally a bigger problem than small ones.
NOK 500 million in direct costs
Assuming that 20% of Norwegian fillets feature dark spots, this means that around 250,000 tonnes of salmon are at risk of having to be discarded. With a reduction in price of approx. NOK 2 per kilo, the estimated loss in value reaches at least NOK 500 million.
According to the fish health report from 2015, the costs linked to dark spots were already approaching NOK 500 million as early as in 2010. There is therefore every reason to believe that these costs are even higher today, given that dark spots have become more common since then.
Norwegian salmon is a valuable brand. Targeted refinement and brand building over a protracted period have boosted the quality experience and increased the willingness to pay among consumers. If this quality is brought into doubt, it will be expensive to have to rebuild the market position once more.
Norway is the biggest salmon exporter in the world. Aquaculture is our biggest renewable export business today. The precondition is and has always been the stable, high quality of our salmon. Norwegian salmon has featured unmistakable quality that has captured one market after another – even the most critical and discerning.
Market demands are now moving in the direction of more fillet and less whole salmon. This increases requirements for a delicate product, without blood and melanin spots – and with a consistent colour and fat content. From this perspective, dark spots constitute one of the biggest challenges to quality in modern salmon production.
How to reduce spots?
A trial involving adding krill to the feed at the BioMar experimental station on Senja revealed, as so many times before, ‘incredible results’ on both fillet and harvest quality. However, it also transpired that this feed produced an almost 20% reduction in dark spots in fillets. There were clear indications that feed components which modulate inflammation also help reduce the development of spots. Specific vitamins and minerals also have an effect, and we have noted effects of the fatty acid balance.
The findings stem from the Nofima report from a trial in which 200 fish were examined. The full-scale feed trial was carried out at the BioMar experimental facility outside Senja, Norway, with salmon released into the water in spring 2014. The test feed used was Qardio, whose ingredients comprise krill.
Fatty acid balance
It was not particularly surprising that Qardio – which is already known to reduce the harmful effects of viral infections in the heart – also proved to reduce the incidence of dark spots in fillets. Discovery of the same virus (PRV), which causes HSMI, in dark spots suggests that this virus may also have a role to play in this context.
The development of a feed such as Quick M, where the focus is on reducing dark spots, has also generated positive effects in other areas.
The components in the feed affect the fish’s metabolism on several levels, and also influence how nutrients are used to build cells and tissue. A higher proportion of fatty acids is emitted into the body, where these acids assist in building muscle tissue rather than simply being stored as useless fatty tissue in the abdominal cavity. This has proved to have a positive effect on harvest yield, fillet yield and fillet quality.
The findings from the feed trial set up by Nofima demonstrated a significant reduction in melanin spots among the group fed on the trial feed containing antioxidants. Another test, conducted by NMBU in 2015, found PRV virus in all the dark spots examined. There is therefore evidence to suggest that PRV must be present for melanin to be deposited in fillets.
- Anyone interested in learning more about the topic can read the report entitled Mørke flekker i laksefilet- omfang, årsakssammenhenger og forebygging (Dark spots in salmon fillets – scope, causes and prevention), which is published on the FHF website.