Facts about the use of salmon oil in salmon feed

Salmon oil is produced from cut-offs from farmed salmon from EU approved slaughterhouses in either Norway, Iceland or Faroe Island. This is done in a controlled environment following EU regulations for salmon processing. Salmon oil contains natural fatty acids including both EPA+DHA (Omega-3) which is essential for the salmon’s health.

A natural question is, don’t we risk cross contamination of DNA between the same species, which again could cause an infection by a misfolded protein, known as a prion? This was the cause of the “mad cow disease” (BSE) that resulted in the Creutzfeldt-Jakob diseases in the UK in the 1980’ies. There are no prions in salmon oil which could cause BSE, because oil consists of fat and not protein, and protein is the carrier of DNA, therefor we are safe from prions.

A team of scientists at the department of Biology at the Norwegian University of Science and Technology (NTNU) and Nutrimar wrote a scientific paper in 2023 where they looked at prion content in salmon hydrolysate. The salmon hydrolysate was analysed for prion content by shotgun and targeted proteomics, but no prions were found (Sandbakken et al., 2023).

Requirements for salmon oil and the production process
Salmonid oil is produced from fresh trimmings of farmed salmon (Salmo salar) and/or trout (Oncorhynchus mykiss) from Norway, Iceland or Faroe Island. The fish is slaughtered by an EU approved slaughterhouse in same countries, and is either used fresh or conserved by adding organic acid and antioxidants. The further process includes a step of heat treatment and separation.

When salmon oil is produced the manufacturer separates protein, water and the fatty acids in oil using category 3 salmonids by-products. Every batch of salmon oil is monitored and checked for sediments and protein water before being used in salmon feed. That is why it is legal and safe to use salmon oil in salmon feed.

Risk assessments of using salmon oil
All manufactures of marine oils, including salmon oil, must be internally approved by Skretting, and there are strict product quality agreements in place to secure nutritional oils that are legal, sustainable, and are safe for food production and the environment.

Any laboratory used for marine oil analysis must be ISO 17025 accredited and participate in accredited (ISO 17043) ring test specific to fatty acid analysis in marine oils. The method of analysis used for marine oils must be according to a recognized method and validated and agreed with Skretting.

Use of salmon oil follows EU regulations
Regulations regarding the use of salmon oil in salmon feed is covered by Regulation (EC) No 1069/2009 and Regulation (EU) No 142/2011 and may be subject to restrictions in use according to Regulation (EC) No 999/2001.

Scientific studies confirm the safety and benefit of salmon oil

The Norwegian Scientific Committee for Food and Environment (VKM) performed in 2012 a large scientific risk evaluation of by-products from aquaculture, among them salmon oil, for use in salmon feed (VKM, 2012). The assignment was given by The Norwegian Food Safety Authority (NFSA) who asked specifically about the risks of using processed salmon oil in salmon feed. It was concluded that the probability of presence of viruses and parasites assessed was ineligible after heat-treatment of at 85°C. Salmon oil used in commercial fish is heat-treated at least at 88°C.

In 2011 the Norwegian Food Safety Authority also requested the Norwegian Scientific Committee for Food Safety (VKM) to make a risk and benefit assessment of marine oils. The Scientific Committee performed a risk assessment of decomposition substances and oxidation products in fish oils, evaluating the negative, and positive health effects of n-3 fatty acids, plus risk and benefit assessment of marine oils.

VKM’s recommendation was to avoid oxidations. Oxidated oils are nutritionally poor in addition to the health risk, so Skretting has strict product quality agreements in place, and requirements for analytical methods for the determination of oxidation products and other substances of concern in marine oils and n-3 fatty acid food supplements.

The report also says that microorganisms present in the raw material are not likely to be carried over to oil for human consumption due to considerable heat-treatment both for the raw material and the oil during processing. Furthermore, decomposition substances from proteins in the raw material are water soluble and largely removed by several washing steps during the refining processes and will normally not be detectable in the n-3 fatty acid food supplements (VKM, 2011).

Toxic substances and prions
The Norwegian Food Safety Authority (NFSA) also commissioned a report on toxic substances in marine oils in 2017. This concluded that the highest levels of organic contaminants were found in four cold pressed fish oils, while salmon oil had relatively high levels of sum PCDD/F+dl-PCB (1.36-2.31 ng TEQ/kg oil), but the values were still clearly below the maximum levels for all the organic contaminants with lowest levels in the salmon oil. Salmon oil is heat treated (Nilsen et al., 2017).

There is also a peer reviewed scientific paper discussing risk and the effects on salmon focusing on prions, among them are a study on salmon hydrolysate that looks closer into prion contents and effects on growth, digestibility and gut health, where no prions were found (Sandbakken et al., 2023). There is also a study on growth performance and feed utilisation in salmon with high-lipid/high-EPA (Hatlen et al., 2012).

Extensive experience with salmon oil

Skretting Norway has used salmon oil in customer specific feeds for the past decade. Those who have used it, are satisfied with this raw material and will continue to use it.

Scientific study shows similar salmon growth and quality of diets with and without salmon oil
In 2013 a scientific study was published that looked at growth performance, feed utilization and product quality in slaughter size salmon that had been fed a diet with salmon oil and European animal by-products (poultry oil and porcine blood meal).

The result showed that this salmon had a similar growth rate, but slightly improved feed conversion ratio compared with the control group that got a traditional diet based on fish and plant ingredients. No differences were seen in fish length, live weight or condition factor. Final body composition was similar to the control group. There were also no differences in slaughter yield, quality classification, gaping score or fillet texture (Hatlen et al., 2013).

Verified by a decade of real life farming
The result from this scientific trial is something Skretting has seen and verified during the long and substantial use of salmon oil over several generations of salmon production. Oil from farmed fish is a raw material with good nutrients that is a welcomed addition to oil from wild fish.

Not only does the salmon oil perform well regarding growth and quality, but it also secures the wellbeing and health of the salmon.

A welcomed supplement to combat the scarcity of omega-3
Due to the scarcity of EPA+DHA (omega-3) from wild fish, salmon oil is a needed supplement that also makes sense in our continued quest for an expanding circular economy where we utilize our resources in the best possible way.

The EPA+DHA scarcity and increasing demand for circular products in addition to the proven benefits of EPA+DHA for both the human and fish health, have increased the interest among other salmon farmers to include salmon oil in their feed. So, we expect the usage of salmon oil to grow in the near future.

References

Hatlen B., Berge G. M., Odom J. M., Mundheim H.Ruyter B., 2012. Growth performance, feed utilisation and fatty acid deposition in Atlantic salmon, Salmo salar L., fed graded levels of high-lipid/high-EPA Yarrowia lipolytica  biomass. Aquaculture 364-365,  (October 2012), 39-47.

Hatlen B., Oaland Ø., Tvenning L., Breck O., Jakobsen J.V., Skaret J., 2013. Growth performance, feed utilization and product quality in slaughter size Atlantic salmon (Salmo salar L.) fed a diet with porcine blood meal, poultry oil and salmon oil. Aquaculture Nutrition, vol. 19 (August 2013), 573–584.

Nilsen B. M., Sanden M., Måge A., 2017. Miljøgifter i fisk og fiskevarer 2016: Dioksiner og dioksinlignende PCB, ikke-dioksinlignende PCB, polybromerte flammehemmere og tungmetaller i marine oljer. Nasjonalt institutt for ernærings- og sjømatforskning (NIFES) 2017 Report.

Sandbakken I. S., Five K. K., Bardal T., Knapp J. L., Olsen R. E., 2023. Salmon hydrolysate as a protein source for Atlantic salmon; prion content and effects on growth, digestibility and gut health. Aquaculture 576 (July 2023).

VKM. Risk assessment regarding processing requirements of by-products from aquaculture for use in fish feed. Opinion of the Norwegian Scientific Committee for Food Safety, 11-603-final. Oslo: VKM Report 2012:14. 2012. ISBN 978-82-8259-041-9.

VKM. Description of the processes in the value chain and risk assessment of decomposition substances and oxidation products in fish oils. Opinion of the Norwegian Scientific Committee for Food Safety, 08-504-4-final. Oslo: VKM Report 2011:19. 2011. ISBN 978-82-8259-035-8.