Seaweed has a long tradition as animal feed in coastal areas, but new technology can broaden the use of seaweed in a variety of farmed animals and fish.
“Seaweed is good for sheep, for example. The meat will often have a more aromatic, saltier flavour than meat from other lambs,” says Margareth Øverland, Professor at the Norwegian University of Life Sciences (NMBU).
Happy and sustainable
She is talking about high-quality meat from happy sheep – but sustainability is an underlying factor. Øverland is the centre director of the research centre Foods of Norway at NMBU, where scientists cooperate with business and industry partners to produce more environmentally friendly feed for fish and livestock.
One place to look is just beneath the surface of the sea. “Seaweed grows much faster than terrestrial plants. All it needs is seawater and sunlight. Moreover, seaweed has a beneficial effect on the environment, as it can recycle nutrients from the aquaculture industry that would otherwise be lost,” Øverland explains.
Øverland and her colleagues are initially looking at brown seaweed and how it can be used in feeds for a variety of animal species, from chickens to farmed salmon. Simply feeding them seaweed and letting the chickens or salmon eat it as is, is not going to work, however. Species with a single stomach, such as fish, chickens and pigs, are not able to get much nutrition from the seaweed.
“The initial nutritional value is very low. Targeted processing is required to turn seaweed into feed,” she says.
This involves extracting the active substances. Sugar and nutrients are then used to produce yeast, which in turn becomes a protein-rich feed ingredient. And what is left of the plant can be used as fertiliser.
“We see that seaweed extract has a highly beneficial effect on fish health, especially in connection with the transfer of salmon to seawater,” Øverland says. Seaweed extract has anti-inflammatory properties and gives the fish a healthier gut flora.
“We have great faith in this as a good solution for the aquaculture industry, where the fish is exposed to a high level of stress. Salmon experience changes in their environment and feed, pathogens and stress from being handled in connection with vaccination or delousing. This could impair growth and cause considerable losses, particularly in seawater,” she says.
Perhaps seaweed extract can reduce stress and strengthen the immune system, thus making the salmon more robust and better able to withstand these challenges. Lower mortality means better financial results for fish farmers. In Øverland’s words: “This shows very interesting potential.”
Unprocessed for ruminant animals like sheep
Some farmed animals can eat seaweed in an unprocessed state.
“We have added seaweed to feed for ruminants without processing it. Ruminants are much better equipped to utilise the seaweed’s nutritional value, as they come with their own natural ‘bioreactor,’” she says.
Scientists have fed lambs seaweed grown on the island of Frøya in Norway. The company Seaweed Solutions has farmed seaweed, cut it up, frozen it and sent it to Ås, where it was sun-dried. The end-product had a dry matter content of about 30 per cent. This is roughly equivalent to the sheep’s normal winter feed of silage stored in round bales or silos.
“We found that the sheep liked this feed very much. There was no negative effect on their growth, and the meat was of high quality,” says Øverland.
Good meat, more milk
The sheep were not the only ones to enjoy their feed. So did the people who ate the high-quality meat from the lambs. “There was less loss in cooking, and the meat was more tender. It also improved storage stability,” she says.
The researchers had consumers taste meat from lambs that had been fed seaweed and lambs that had not, and there was a clear distinction. The meat of lambs that had been fed seaweed had a more aromatic, saltier flavour. It is juicier, redder, it can be stored for longer, and it also has a higher content of nutrients such as iodine and selenium.
Trials where cattle and goats have been given feed containing seaweed indicate similar effects: tenderer meat, less loss in cooking, and more and healthier milk.
Øverland gave a presentation of the project at the SIG Seaweed conference in Trondheim. “One thing that came out of the conference is that Norway is in a good position to develop a seaweed-based industry, and there is considerable interest in seaweed farming, but access to sales channels presents a bottleneck,” she says.
Most of the seaweed presently farmed is used for human consumption. If it could also be used in animal feed, that would open up possibilities for new products and sales channels, and production could be increased considerably.
Margareth Øverland, Liv T Mydland and Anders Skrede: Marine macroalgae as sources of protein and bioactive compounds in feed for monogastric animals. Journal of the Science of Food and Agriculture, 2018, doi: 10.1002/jsfa.9143