New sources of protein in aquaculture


Lecture presented at the Animal Production Conference organized by IRTA on 12-13 May.

«Co-creating the future of animal production«

Co-author Enric Gisbert & Cristóbal Aguilera

If the world doesn’t change, which we cannot guarantee either, in 2050 we will inhabit this planet about over nine billion people.

It is evident that the effect of the climatic emergency, together with current events such as the war in Ukraine, which produces a substantial imbalance in the production of essential vegetable proteins, forces us to find alternative raw materials that guarantee the population’s nutrition .

A relevant fact is that a third of the proteins that we will consume will come from seafood and, specifically, two thirds’ parts will come from farmed fish.

The effect that this demand can have, to serve the 800 million people who depend directly on blue food systems, implies that we must increase supply by between 25% and 70% in order to promote healthy habits associated to the consumption of fish.

And, of course, its conditioned by the increase in needs from Asian countries and the relevant facts commented before.

So, this estimated increase in blue food is the order of 150 million tons, and more than 100 million tons will be produced by aquaculture. Perhaps even more since it’s not possible to estimate the effect on fisheries.

Therefore, to meet this challenge, if we continue as before, it would be necessary to increase catches by 35-40 million tons of forage fish.

Obviously, and with current knowledge, this increase based on fisheries is unsustainable and not feasible independently of increasing the catching effort.

Lynn Fanton in a recent article in «Aquaculture North America» , refers to the effect of changes and pressure on fisheries: «Small pelagic fish are at risk, as marine heatwaves diminish their abundance, size, and quality. More storms could also limit fishing«

It would mean a collapse of the ecosystem and it would be unfeasible to maintain it.

This surpass would cause a destabilization in the entire oceanic food chain. Thus, fisheries not only support direct human consumption but also serve as a supply of fish meal and fish oil for animal nutrition.

This is the main reason why alternative sources of protein are necessary.

And although we can see that in the last 30 years there has been a considerable change in the components of aquaculture feed, going from almost 70% of fish meal and oil in the nineties, to 30% today, in the future we must be at most 10%.

Thus, there is a need to develop alternative feed ingredients based on more efficient use of natural available resources from land and ocean, by exploitation of waste streams that is currently not utilised, and by improving processing technology to obtain safe and healthy aquafeed ingredients.

Future feed resources are expected to include low-trophic species produced or cultivated in the ocean, such as mesopelagic fish and zooplankton (krill, copepods and amphipods), polychaetes, macroalgae and crustaceans.

Ingredients can also be produced from land-based production, such as microbial ingredients (bacteria, yeast and microalgae), insects and animal by-products; poultry meal, meat and bone meal, blood meal and hydrolysed feather meal.

Resources derived from other commercial production, such as biodiesel, brewing and distillation industries, and by-products from the agriculture industry, can also be refined and used as feed ingredients.

Where most progress has been made in substitution is in plant-based alternatives (like soya, corn or wheat, among others).

Identifying different plant-based by-products for use as fish feed ingredients has received increasing attention in recent decades as the industry continues to search for alternative feed resources.

Actually the substitution level is more than 50% of the composition of the diet, however, there are certain limitations, and it’s necessary to continue studying some effects such as: anti-nutritional factors, amino acid profiles, fatty acid profile, mineral profiles, palatability or mycotoxin contents.

The sustainability of some crops is also questioned. May be as a cause of deforestation in some biodiversity spots of the planet, may be because their use is also questioned from a sustainable and responsible point of view from the consumers.

Production of soya in Brazil and the competence for others uses like human and terrestrial animals it’s a clear expample of this controversial use of resources.

In addition to the main source of alternative proteins like from plant origin, fish are also valuable sources of nutrients and micronutrients, and play an important role in human nutrition and the global food supply.

The use of by-products: viscera, head, skin, bones and blood, it’s an important alternative and sustainable source. Currently it’s estimated that of all fisheries, and as a result of processing, there is about 50-70% that is considered inedible, and only 20% is actually used.

The use of these kinds of by-products in aquaculture feeds will be alienated with circular economy models; thus, enhancing and promoting its sustainability.

But there are questions about economic feasibility and must be resolved before the commercial potential can be fulfilled.

According to the Food and Agriculture Organization of the United Nations (FAO) food loss and food waste is estimated to be 1.3 billion tons per annum globally, is about 30% of all food produced.

Food loss is defined as any food lost in the supply chain and food waste is defined as discarded food items fit for human consumption.

In this context, food loss and waste may be also used as a nutritional source for producing other sources of protein, that may be used in aquafeed formulas.

The microbial biomass produced from various microorganisms, also known as ‘‘microbial protein’’ or ‘‘single-cell protein,’’ (originated from yeast, bacteria, fungi, microalgae) is a promising substitute for animal or plant-derived ingredients for aquafeeds.

To achieve this potential, there should be a focus on improving the scale of production, and ensure the process is environmentally sustainable and reduce the cost of production.

Production of microbial protein-based feed and its use in aquaculture is a relatively new technology and its implementation is not expected to cause large scale consequences.

Commercial production of microbial ingredients is under development and several start-up companies have been established, although current production volumes are not known.

Recently, Smallfood in Nova Scotia have a license for single-celled marine microalgae for aquaculture.

The production of marine macroalgae (also termed seaweeds) is an established industry that represent nearly 30% of global aquaculture production.

Nearly 90% of all cultivated seaweeds are produced in China and Indonesia, but actually exist a trend to enhance this production in Europe (kelp in North Europe and Ulva in Mediterranean and south Atlantic).

The proportion of crude protein in macroalgae, particularly when harvested from the wild, is highly variable, ranging from <1% to 50% of the biomass dry weight, and depends on both species and environmental conditions.

Using whole macroalgal biomass as an alternative protein source has been successful in conjunction with herbivorous aquatic animal species.

Currently, the opportunity and value of using macroalgae in aquafeed for carnivorous fish, lies more in its application as a functional feed to improve the health and welfare of these animals. Rather than as a viable large-scale alternative protein source.

Microalgae have been used in aquaculture applications for several decades, mainly for applications, such as in green water hatcheries, as feed for mollusc larvae, echinoderms and crustaceans, as well as some fish larvae or their live prey (e.g., copepods and rotifers) or shellfish refinement.

The nutritional quality of microalgae is high, with a crude protein content of up to 70% and a lipid content of up to 40%, which are comparable with terrestrial plant and animal sources.

Different microalgae-based products, such as dried whole cells, ruptured cells, defatted cells (after lipid extraction) and extracts from various microalgal species, have been studied in feeding trials over the last decade, with different inclusion levels, nutritional profiles and feed processing treatments.

Similarly to macroalgae, processing costs are really high, and they use is only considered as feasible in terms of cost in diets for larvae and early juveniles.

Among the alternative sources of proteins discussed so far, probably the most sustainable and with more future are insects.

The European Union approved processed animal protein from insects to be used in aquafeed in from July 2017. Regulation (EU) 2017/ 893. Pet food was the only feed market for insect protein in the European Union until this data.

Just last August, the European Union approved use of insect protein in poultry and pig feed.

The insects more commonly used in the industry in development are the black soldier fly, yellow mealworms and crickets.

Farming insects is more scalable than forage fish capture and more climate-friendly than soy production, which has a high carbon footprint related to land-use change.

Actually, the key appeal of insect protein, is its circularity: low-value agricultural by-products and food waste are naturally converted to high-value ingredients to nourish the fish that people eat. 

The nutritive value of insects can be enhanced by combining insect meals, with complementary nutritional profiles or by manipulating the substrate used as a nutrient source to improve fatty acid content, digestibility, and even palatability.

However, some challenging issues remains, including costs and scaling up of insect production. And some legislative approaches related with the source of by-products or food waste, like manure.

But the really important is that this industry didn’t exist 12 years ago, and something are changing:

Protix, companies like Canada’s Enterra, French-based Ynsect and InnovaFeed, and Entocycle in the UK are building giant high-tech facilities, with acquisitions and cross-border partnerships that are changing the landscape.

And some news from one week ago: soon, the largest factory in the world for the breeding and transformation of the Tenebrio molitor insect (a mealworm), will be in the province of Salamanca and belongs to Tebrio, is a Spanish company created in 2014.

In the next 10 years, probably, we will see a future based on a combination of the current-day alternatives and the potential of each protein source.

This feasibility is a combination of economics of commercial-scale, limits of this resource, supply and legal issues.

Although novel ingredients are needed to bridge the gap in aquaculture feed resources, several challenges must be resolved to successfully implement these in the aquaculture industry.

All of the above-mentioned protein sources have been tested, validated and their use is commonly used in formulations.

Since their use doesn’t impact growth performance and feed efficiency, what is needed is to evaluate whether they have a direct impact on fish immune performance.

Basically when included in diets at high levels; thus, the potential use of feed additives may be needed for the proper balance of diets.

In conclusion, changing climatic conditions and increasing competition for land, water and energy, as well as fully exploited capture fisheries, emphasise the urgent need for sustainable feed ingredients developed from underutilised natural resources.

Finally, as Kip Thorne (Nobel Prize in Physics) said: “The right answer is seldom as important as the right question”.