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Should seaweed be more widely used in shrimp feeds?

29 June 2021, at 8:00am

Seaweed has huge potential in for use in shrimp aquaculture, according Alexandre Veille, although there are still a number of bottlenecks – including consumer perception, market competition and a relative lack of studies into the comparative benefits of different seaweed diets – to overcome.

Gold Coin's shrimp feeds contain up to 10 percent seaweed
Gold Coin's shrimp feeds contain up to 10 percent seaweed

© Gold Coin & Pilmico

Veille, who formulates shrimp feeds for Gold Coin Group, believes that aquafeed companies, aquaculture producers and consumers are currently too concerned with the use of microalgae to replace fish oil, and are neglecting the wider benefits of macroalgae.

“Most of the focus on seaweeds in the aquafeed sector has been on microalgae so far – as a source of DHA and astaxanthin – but we are looking at other alternatives, mainly locally grown macroalgae that are found in Asia. We’re looking at green, brown and red seaweeds – some farmed, some wild harvested,” he explains.

Price, availability and sustainability all have a bearing on Veille’s decision to focus on macroalgae.

“Producing microalgae is still very expensive. And why should we focus on producing microalgae in cold countries, using lamps and heaters, then drying and processing it before shipping the end product to Asia, when in Asia we can collect macroalgae from beaches or harvest it from the seas locally?” he asks.

“This company is well rooted in Asia. We have contacts, we can make deals,” he adds.

However, Veille admits, sourcing these seaweeds isn’t always easy – China being the largest supplier, while other countries tend to sell to a handful of major customers, making it harder for emerging companies to find reliable suppliers.

Post-larval shrimp
Post-larval shrimp

© Gold Coin & Pilmico

Veille is currently concentrating largely on Ulva and Laminaria species – and Gold Coin has been trialling these at inclusion rates of up to 10 percent in a wide range of its feeds for over a year now.

“They’re mainly used to replace soybean and other plant products in the feeds. Not so much fishmeal, as our feeds contain so little fishmeal these days,” he explains.

Prior to Gold Coin, Veille worked with Olmix – a French seaweed additive provider – for five years. However, he now believes that aquafeed manufacturers should view seaweed as a raw material, and that they should investigate doing more with the whole product.

“People need to realise the value of the whole product in aquaculture, not just the extracts,” he argues.

Performance

Veille is cautious about making sensationalist claims about the value of seaweed in aquafeeds, but believes that it does have advantages over crops such as soy.

“So far, substituting seaweed for soybean meal in shrimp diets has at least matched the performance of conventional feeds. Reducing the use of soybean meal helps to reduce the price of the feeds, as the price of soybean meal is currently very high and it also needs to be imported from Latin America, so comes with extra shipping costs,” he explains.

The comparative sustainability of using seaweed is another key factor.

“Issues with soy can include deforestation – which can lead to flooding and soil degradation as well as loss of biodiversity. This is affecting Brazil and – in particular – the countries around it. Water use is another potential issue with soy – and other crops such as wheat,” he notes.

Limitations

While Veille might be a firm believer in the value of seaweed for shrimp feeds he is aware that there are still a number of obstacles to overcome before it can be used more widely.

“The limiting factor is the price and availability of some seaweeds. The volume is there, but seaweed producers and processors tend to sell to the human market – where it is used as a raw material for the production of things like agar and alginate, or for nori [ie for sushi],” laments Veille.

Gold Coin produces around 60,000 tonnes of shrimp feed a year
Gold Coin produces around 60,000 tonnes of shrimp feed a year

© Gold Coin & Pilmico

Other species

Gold Coin makes feeds for a variety of species, not purely aquatic ones, and Veille has been keeping tabs on other possible uses for seaweeds.

“There’s been good feedback on the use of seaweeds in fish feeds. It’s also suitable for ruminants [eg cattle] because of their digestive systems. However, it’s too high in fibre for monogastrics [eg pigs and chickens],” he says.

“We’ve had particularly good feedback about the performance of feeds that contain seaweed for shrimp that are grown in biofloc systems. It’s part of the natural diet of shrimp and they can digest the fibre in seaweed better than they can digest the diets in [terrestrial] plants. This leads to better protein efficiency. And we have also seen some improvements in palate performance, using seaweeds,” he notes.

He is more hesitant about the health benefits for the shrimp, but is quietly confident that this will soon be demonstrated too.

“It’s too early to calculate. We know that using seaweed certainly has no negative effects. And we’ve seen promising results in the lab, but we need at least a year to see if there’s a general trend in relation to the prevention of diseases,” he reflects.

Given that many of Gold Coin’s 60,000 tonnes of commercial shrimp feeds contain seaweed, it will be interesting to see what patterns emerge over the next 12 months.

In the meantime, Veille welcomes the proliferation of novel ingredients that are emerging in the aquafeeds sector.

“All alternatives are welcome – diversity is key to help balance our feeds. Whether it’s insects, seaweeds, single-cell proteins or yeasts, the more options the better, as each has different properties. However, we also have to consider the market – will consumers be willing to eat vegetarian shrimp?” he adds.