Aquaculture for all

Insights into omega-3s in aquafeeds

Feed ingredients Health

A workshop that focused on a range of critical questions around the use of omega-3s in aquafeeds was organised by IFFO last month.

a group photo outside the entrance to a historic stone building
Speakers at the recent IFFO omega-3 workshop

The workshop took place in Stirling on 31 May © IFFO

Taking place in Stirling, IFFO explained at the event how fish oils can contain up to one third omega-3s, while most crude oils for omega-3 products come from small pelagic fish like anchovies and sardines, and increasingly from by-products from the seafood industry. In 2022, 54 percent of global fish oil production was made from using fish by-products. Up to 25 percent of global EPA and DHA [eicosapentaenoic acid and docosahexaenoic acid – two of the most sought-after omega-3s in aquaculture] production is from Peru.

According to IFFO, global production of fish oil has been remarkably stable over the last decade at around 1.2 million metric tonnes a year on average, although this year it appears likely that there will be a slump in global supplies.

The recent “El Niño events explains the drop in EPA and DHA production in 2022”, explained Enrico Bachis, market research director at IFFO, adding that in addition to El Niño events, the counter-event of La Niña greatly reduces the overall oil content in fish.

Three sectors are driving this demand: aquaculture (with more than 70 percent of fish oil usage), pharmaceuticals and pet food.

Requirements and benefits of omega-3s

It is well established that EPA and DHA have a wide range of effects both on fish and human physiology: cell membrane structure, regulation of inflammation and disease resistance.

Looking to different species, IFFO’s technical director Brett Glencross stated that it is difficult to pool marine fish species together and how they respond to EPA and DHA. Requirements change with fish size: higher requirements are needed at a young age. Only few quantitative models on maximising uptake and retention efficiency are available for a few species, and further work is needed in this area to develop more optimal management strategies for omega-3 optimisation.

Nofima’s Bente Ruyter, reported on how omega-3s influence growth, quality and health in Atlantic salmon. She reported that an intake of 6.5 percent to 10 percent of EPA and DHA in the fat in feeds fed to fish in sea cages is needed to impact growth and quality positively. Whereas an intake of 3 percent to 10 percent is needed to impact health positively, depending on tissue, life stage and degree of stress and environment.

As for shrimp, they don’t store lipids like fish and are not considered a useful source for omega-3 intake by humans, but they still require omega-3s in their diets.

“Shrimp don’t tolerate high lipid levels. Digestion of lipids is affected by lipids levels and fatty acid profiles,” Dr Brett Glencross highlighted. However, he added that shrimp need dietary omega-3 fatty acids: research has demonstrated that absence of lipids and omega-3 is terminal. A combination of short chain and long chain PUFA is better than either alone, with this effect evident in multiple shrimp species.

Novel omega-3 sources

Moving on to novel omega-3 resources, Monica Betancor, associate professor at the Institute of Aquaculture, reported that each of them presents a range of benefits and risks:

  • Indoor vertical farming of microalgae (which are primary producers of EPA and DHA) can be used to feed fish both at larval and adult stages. However, the use of microalgal biomass directly in feeds limits inclusion, due to digestibility issues, and price has been a barrier, especially for algal oil.
  • GM-crops have been produced that include microalgal genes and are now capable of producing their own EPA and DHA. But legislation and deregulation in certain countries has been are limiting and public acceptance is low at present (in some markets).
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