18th October

Seaweeds: the answer for future global animal production

By Dr Stefan Kraan
Scientific Director of Ocean Harvest Technology Ltd

With the world population topping 7 billion last year, and forecast to reach 9 billion in 2050, we are heading for major problems regarding food production and security.
The global aquaculture industry currently produces 50% of all seafood consumed - 6% from marine fish farming. Fish farming is still the fastest growing sector, however in order to increase production to secure food production we encounter problems.

9.1aquaculture OHT
exotic looking Irish red seaweeds – a source of novel antibiotics

Fish meal is becoming expensive as a protein source to feed farmed fish, and there’s an urgent need for alternative resources other than plant protein. Chemical use also to combat disease is becoming an issue with contamination and residues in fish and increased resistance built up by the disease against these chemicals. With protein values ranging from 10-40% for certain seaweed species might very well be a part of the answer. Besides, seaweeds can bring with them other interesting bioactive molecules that could be applied via aquaculture feeds to replace currently used chemical ingredients such as colorants, preservatives, lice treatments and pre-mixes.



Health issues
Farmed fish, especially salmon, is a healthy food, high in omega-3 polyunsaturated fats which have a variety of beneficially health effects.  Farmed fish - depending on the feed used - may however contain lower amounts of omega-3 fatty acids compared to wild fish when fed on vegetable oils, and tend to have more total fat and calories and slightly less protein. They may also have higher levels of contaminants, such as, antibiotics, synthetic chemicals, colorants preservatives and PCBs.

Ocean Harvest Technology (OHT), Ltd has developed a sustainable, seaweed-based commercial salmon feed ingredient that not only replaces all synthetic chemical additives and colorants currently used in salmon fish feed – but has also been shown to bolster the fish’s ability to ward off sea lice.

Results from commercial farmers confirm that fish eating Ocean Feed™ have increased resistance to sea lice infestation. Sea lice control costs the industry more than $100 million a year.

Alternative options
Seaweeds (Macroalgae) are rich in all the nutrients needed by humans and animals. For instance, Gracilaria ― a species cultivated in many countries ― contains all the essential amino acids in levels close to egg protein, while 74% of its fatty acids are unsaturated; 33% of the fatty acids in this seaweed is EPA and 13% DHA.

Algae are also known to be a rich source of carotenoid pigments and could replace the current chemically produced colorants in fish farming. The brown alga Ascophyllum nodosum may contain up to 80 mg/kg dry weight of such pigments.

Pigments such as carotenoids can also act as anti-oxidants, protecting the polyunsaturated fatty acids and hence improve shelf-life of fish products. Certain seaweeds have been identified as providing a natural therapeutic solution to control diseases in salmon that avoids the problems associated with the excessive use of antibiotics and other bio-accumulating chemicals.

Certain specific carbohydrates such as alginates, carrageenans, laminarins and fucoidans, present in brown and green algae, are known to have anti-viral and anti-tumour functions and have been shown to have immunostimulatory, and probiotic properties stimulating the natural immune system.

Ocean Harvest Technology
Based in Milltown, Co Galway, OHT has already advanced this concept and has trialled different seaweed formulas (Oceanfeed) on salmon and some other farmed species with considerable success resulting in lower FCRs, higher weight gain and a clear reduction in sea lice. 

The end product (fresh and smoked salmon) has been taste-tested by independent panels, retailers, consumers and Michelin Chefs and has received high acceptance for taste and texture, while reducing the environmental impact and increasing fish sustainability.  

These seaweed-fed salmon are currently produced commercially on farms in Canada and Norway using Oceanfeed. More additional data from these farms have come out demonstrating, superior fish in health and taste and 80% lice reduction lowering the need for chemical treatments.

Oceanfeed and swine farming
Concern about the use of antibiotics as growth-promoters in animals led to Sweden imposing a general ban on animal feed antibiotics in 1986. On 19 September 2012, a group of 150 scientists in the US including the former commissioner of the US Food and Drugs Administration issued a statement calling on the FDA and Congress to regulate the use of antibiotics in animal agriculture.

"There's no question that routinely administering non-therapeutic doses of antibiotics to food animals contributes to antibiotic resistance," Donald Kennedy, former FDA commissioner and President emeritus at Stanford University, said.

He added that the FDA's current voluntary approach, which asks the animal drug industry to stop selling antibiotics that are medically important to human disease management as growth promoters in animal feed, was not enough.

The FDA’s own data shows that 80% of all antimicrobial drugs sold nationally are used in animal agriculture.

Antibiotic activity from seaweed
Chemicals responsible for antibiotic activities are widespread in macroalgae. Interesting substances in particular are the halogenated compounds such as haloforms; halogenated alkanes and alkenes; alcohols; aldehydes; hydroquinones and ketones.

The list of terpenoids with antibiotic qualities is especially long, many of which  are also halogenated. Compounds such as sterols and heterocyclic and phenolic compounds sometimes have antibiotic properties.

A promising antibacterial agent is a halogenated furanone, or fimbrolide, from Delisea ― a common red alga found in the intertidal on the Irish coast. It has been examined for its effectiveness as an active ingredient in bacterial antifouling agents, and as a possible treatment for chronic Pseudomonas aeruginosa infection.

Some common Irish brown seaweeds show strong antibacterial effects on Vibrio ― a widespread bacterial infection in shrimp and fish farming.

In general, seaweeds show antibacterial effects on many marine and terrestrial pathogens although the exact mechanism and possible synergies with other compounds is not understood yet.

OceanFeed-Swine trials

In 2011, Ocean Harvest Technology commissioned an Irish swine research farm feeding trial with OceanFeed-Swine at different percentages of inclusion of 0%, 2%, and 5%, and compare the results against a reference diet using 240 pigs.

Due to current industry requirements, OHT was unable to fully replace all of the mineral and vitamin pre-mix in this particular trial.

OceanFeed-swine was therefore fed in addition to conventional premixes, diluting the other ingredients. After a four-month trial period with weanlings to 100 kg pigs the results showed a positive outcome of having OceanFeed incorporated at 5% in the diet on taste and intestinal health. In respect of FCE and weight gain the lower inclusion level scored better than the control.


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