Why Insect Meal Will Be the New Feed for Animals in Aquaculture

Insects as a viable animal feed have been receiving increasing recognition due to their high energy and protein content. Since July 2017, EU legislation has been changed and now permits that animals in aquaculture can be fed with processed animal protein (PAP) from insects. This legislative amendment mainly affects insect meal (dried insects ground to meal) that primarily consists of protein, especially when it is defatted.

The advantage of insect meal compared to fresh or unprocessed dried insects is that it can easily be mixed with other feed components, such as ground grains and soy, to form a mixture of a desired composition that is then pressed into pellets for better and more convenient feeding to animals.

Animals in aquaculture in the EU

Within the EU, animals in aquaculture are mostly reared by Spain, the UK, France, Italy and Greece, who collectively produce around 75 % of the EU total. 294,000 tons of animals in aquaculture were reared by Spain (equals 23.0 % of the EU total, valued at approximately €513 million), 212,000 tons by the UK (16.6 %, €995 million), 180,000 tons by France (14.1 %, €627 million), 149,000 tons by Italy (11.6 %, €437 million) and 106,000 tons by Greece (8.3 %, €463 million) (1). Here, the most relevant and important animals are molluscs and fish. The following 10 species account for around 90 % of the total weight of reared animals in aquaculture in the EU in descending order:

1) Mediterranean mussel (Mytilus galloprovincialis), 2) Atlantic salmon (Salmo salar), 3) rainbow trout (Oncorhynchus mykiss), 4) blue mussel (Mytilus edulis), 5) gilt-head seabream (Sparus aurata), 6) Pacific oyster (Magallana gigas), 7) European bass (Dicentrarchus labrax), 8) common carp (Cyprinus carpio), 9) Japanese carpet shell (Venerupis philippinarum), and 10) Atlantic bluefin tuna (Thunnus thynnus).

Fish and shellfish species have different natural habitats and consequently there is country to country variation in the types of aquatic produce that predominates. 95 % of Atlantic salmon are reared in the UK, and 87 % of Pacific oysters in France for instance (1). At the same time, other species are more broadly farmed. Rainbow trout for example are reared by 17 of the EU member states and the common carp is reared by 13 states as one of their major fish species (2).

Issues with current fish feed

The seven fish species mentioned above are carnivorous or omnivorous and a major part of their diet in the wild are other fish and shellfish, as well as insects (3-6). Currently, fish in aquaculture are fed with fishmeal and plant-based feeds, as well as oil from fish and plants. Due to the increasing prices of fishmeal and fish oil, more and more plant-based material from legumes, oil seeds or cereal gluten have been included in feed. It seems, however, it is ill-advised to substitute large amounts of fishmeal and fish oil in particular with plant-based material. Plant-based feed material is less palatable, contains anti-nutritional components, is high in fiber and non-starch polysaccharides and has an apparently less suitable fatty acid and amino acid profile (1). Insect-based feed material on the other hand has several advantages.

The amino acid profile of insects meets the needs of fish 

Insect meal could be partially substituted for fishmeal and plant content. Overall, the amino acid profile of insect meal is more comparable to fishmeal than plant-based feed. Therefore, insects would be a preferable alternative to soy for instance (7). However, depending on the utilized insect species, the crude protein may still be low in some amino acids, such as methionine and lysine. Potentially, it would be necessary to supplement these amino acids in animal feeds to cater for the needs of specific farmed species, specifically for growing animals (8,9). However, using different insect species in combination could compensate for the lack of certain amino acids in some species. For instance, the amino acid profiles of the black soldier fly (Hermetia illucens) and house fly (Musca domestica) larvae partly complement each other and together they match the profile of fishmeal much more closely than they do individually. 

The fatty acid profile of insects can be customized 

Fish oil contains higher amounts of omega-3 fatty acids than vegetable oil, which are particularly important for carnivorous species such as salmon and trout. Feeds high in plant material may therefore contain insufficient levels of these fatty acids (10). The ratio of alpha-linolenic acid (one of the three omega-3 fatty acids) to linoleic acid in insect oils is not as good as in fish oils, but in general better than in vegetable oils. These fatty acids need to be supplied in the fish’s diet as they only have limited metabolic capabilities to synthesize these fatty acids or have shown better growth and development when these fatty acids are provided in their diet (9). Interestingly, investigations showed that the fatty acid composition of insects can be modified by modulating the content of the substrate on which they are reared, and thus can potentially be adjusted to fit the requirements of a specific fish species more closely (8,9).

Potential disadvantage of insects as feed

- Chitin is an antinutritional factor

Fish diets in general contain relatively low levels of carbohydrates, the most common carbohydrate probably being chitin. However, chitin has been suggested to be an antinutritional factor that impedes the absorption of nutrients in fish. Even though in insects the carbohydrate content is less than 20 % of their biomass, chitin forms the majority. This could present an issue when insects are utilized in fish feed. Even though investigations on the effect of chitin are still inconclusive, they suggest that chitin negatively affects feed conversion and, therefore, is a limiting factor for the utilization of insects in fish feed (8).

- Low amounts of calcium and phosphorus

Insects are, in general, relatively low in calcium compared to fish meal, although there are exceptions like black soldier fly larvae. Soy also contains low levels of calcium. However, similar to the fatty acid content, the calcium content of insects can be affected by the calcium content of the substrate they are reared on. Nevertheless, addition of calcium could be necessary to ensure optimal development and growth of fish. Phosphorus levels are also relatively low in insects, as well as in soy, compared to fishmeal. An important factor for fish feed is the ratio of calcium to phosphorous and this would therefore possibly require adjustment to reach a ratio of 1.1 to 1.4 as found in fishmeal (9).

Insect species authorized for fish feed production

According to EU legislation, seven insect species are permitted for the production of animal feed in aquaculture (Regulation (EU) N° 2017/893):

1) black soldier fly (Hermetia illucens), 2) housefly (Musca domestica), 3) mealworm or yellow mealworm (Tenebrio molitor), 4) lesser mealworm or litter beetle (Alphitobius diaperinus), 5) house cricket (Acheta domesticus), 6) tropical house cricket or banded cricket (Gryllodes sigillatus), and 7) Jamaican field cricket (Gryllus assimilis).

These species are regarded as non-pathogenic and do not pose a risk for human, animal or plant health. Furthermore, they do not transmit human, animal or plant pathogens, i.e. are not regarded as vectors, are not protected species or invasive alien species. In fact, they are now classified as “farmed insects” and have a similar status to livestock (according to EG 1069/2009 of the new legislation). The new legal status of these seven insects has certain additional consequences and regulations that need to be abided by. For animal feed production purposes, cultivation of these insects is only allowed on specific kinds of substrates. 

Authorized substrates for rearing of insects

Rearing of insects is not allowed on substrates that contains kitchen or food scraps, meat or bone meal, liquid manure or faeces (according to EG 999/2001 and EG 767/2009).

The substrate is required to be of: 

1) non-animal origin or

2) animal origin, however, only if it is fish meal, blood products of non-ruminants, Dicalciumphosphate and Tricalciumphosphate, hydrolysed proteins from non-ruminants, hydrolysed proteins of ruminants and their hides, gelatin and collagen of non-ruminants, eggs and egg products, milk and dairy-based substances, colostrum, honey, and rendered fats (category 3 substances) (amended schedule XIV, chapter I, clause 2, section 5 b and c of the EU 142/2011).

Significantly, high importance was placed on the exclusion of unprocessed products of ruminant origin to prevent potential cross-contamination with prions that have been attributed to the catastrophic outbreak of bovine spongiform encephalopathy (BSE) in the 1990s. These substrate regulations also apply for insect meal that is imported from non-EU counties into EU countries.

Overall, insects as a feed component for animals in aquaculture have great potential due to their high energy and protein content. This potential has been recognized by EU legislation and several insect species have been permitted for the production of animal feed in aquaculture. It will be exciting to follow the development of how and to what degree these insects will be used over the next few years. So, stay tuned for further information.

References

(1) Eurostat (2016) Dive into aquaculture in the EU. [online] Eurostat. Available at: http://ec.europa.eu/eurostat/en/web/products-eurostat-news/-/DDN-20171018-1 [Accessed 11.02.2019].

(2) Eurostat and Eumofa (2013) European Commission – Fisheries – 4. Fisheries and aquaculture production [online]. Available at: https://ec.europa.eu/fisheries/4-fisheries-and-aquaculture-production_en [Accessed 11.02.2019].

(3) Rochard, E. and Elie, P. (1994) La macrofaune aquatique de l’estuaire de la Gironde. Contribution au livre blanc de l’Agence de l’Eau Adour Garonne. In État des connaissances sur l’estuaire de la Gironde (ed. by Mauvais, J.-L. and Guillaud, J.-F.), pp 1-56. Agence de l’Eau Adour-Garonne, Éditions Bergeret, Bordeaux, France.

(4) Frimodt, C. (1995) Multilingual illustrated guide to the world’s commercial warmwater fish. Fishing News Books, Osney Mead, Oxford, England.

(5) Kottelat, M. and Freyhof, J. (2007) Handbook of European freshwater fishes. Publications Kottelat, Cornol and Freyhof, Berlin.

(6) ICCAT (2009) Report of the standing committee on research and statistics (SCRS). Madrid, Spain.

(7) PROteINSECT (2016) Insect Protein – Feed for the Future. [online] Minerva Communications UK Ltd. Available at: https://www.fera.co.uk/media/wysiwyg/our-science/proteinsect-whitepaper-2016.pdf [Accessed 11.02.2019].

(8) Makkar, H.P.S., Tran, G., Heuzé, V., Ankers, P. (2014) State-of-the-art on use of insects as animal feed. Animal Feed Science and Technology, 197, 1-33.

(9) Tran, G., Heuzé, V., Makkar, H.P.S. (2015) Insects in fish diets. Animal Frontiers. 5(2):37-44.

(10) Scientific, Technical and Economic Committee for Fisheries (STECF) (2014) The Economic Performance of the EU Aquaculture Sector (STECF 14-18) (Ed. Nielsen, R., Motova, A.), pp. 403. Publications Office of the European Union, Luxembourg, EUR XXXX EN, JRC XXXX, xxx pp.