A real alternative to conventional protein carriers?
Insect proteins are expected to take a relevant position in the animal feed market and especially in the aquaculture sector since the EU lifted the ban on insect proteins in 2017 for the use in fish feeds. A new industry that was already in the starting blocks developed even faster since then. Larvae from several insects are in the focus of research and industry with strong concentration on very few species.
Six-Legs-Consulting, Germany
According to the Commission Regulation (EU) 2017/893 within the European Union seven insect species (or their larvae, respectively) are allowed to be used exclusively in aquaculture feed formulations. These are: Black Soldier Fly (Hermetia illucens), Common Housefly (Musca domestica), two mealworm species and three cricket species. This list may be amended in the future upon application. Species like the Silk Worm (Bombyx mori), Super Worm (Zophobas morio) or locusts might be candidates as they are widely used in countries outside of the EU and are discussed as valuable and potential feed ingredients widely in the literature. The admission for the use of insect-protein in poultry feeds is still pending on EU-level but in France insect-oil-fed chicken is available in supermarkets since summer 2020.
For aquaculture- and poultry feed purposes, respectively the larvae of the black soldier fly, H. illucens, housefly, M. domestica and the larvae of the meal beetle, Tenebrio molitor might be the best investigated (and most used) organism, due to their quite simple life cycles. They also show suitable protein profiles (H. ilucens, M. domestica) and fat profiles (T. molitor) and simple engineering requirements for mass production. Crickets and locusts are investigated and produced for food consumption in many areas of the world. In the western world they are produced at high production costs which exclude them from the animal feed market.
THE DREAM OF COMPLETE FISH MEAL-
AND SOY MEAL REPLACEMENT AND SOME OPEN QUESTIONS
Initially started in the United States in the 1980s with research on the Black Soldier Fly (BSF) for reasons of poultry waste treatment, the idea to use insect larvae as animal feeds was reactivated with the beginning of the 21st century. Since then, the animal feed aspect spread quickly – especially in the aquaculture feed sector.
Since the percentage of fish meal in most aquaculture compound feeds decreased in the last two decades in favour of soy bean meal, cereals, etc. the use of animal-based alternatives is discussed more intensively. This is due to the fact that the use of just plant-based feed ingredients is limited physiologically, especially for carnivore fish – though completely vegetarian feeds had been developed and tested for trout, recently. But the question remains if we really want to have “vegetarian predatory fish” like trout, salmon or seabass (still having in mind the BSE-disaster when real vegetarian animals were forced to become cannibals).
As the ban on insect-based PAP (processed animal protein) for fish feeds was lifted in 2017 by the European Commission the new insect-industry took-off in many European countries. Same happened in Asia and the Americas where research and industry, both display strong performance since then – as could be seen at the conferences on “Insects to feed the World” in 2014 and 2018.
BSF-larvae meal is the most popular and most used insect-based feed-ingredient but, it has got one small disadvantage: It shows a high fat-content in the matrix (30 – 45%) depending on the given feed stock and the time of harvest. Therefore, BSF-meal needs to be defatted before being added to feed formulations. The fatty acid spectrum of the oil section is rather adverse and contains very little or no ω-6 and ω-3-fatty acids (which belong to the poly-saturated fatty acids, PUFA’s). If the BSF-oil is not or just partly extracted from the meal, the fat content in the fish and the sum of saturated fatty acids (SFA) will increase with increasing BSF-meal inclusion levels. The addition of macro- or micro-algae meal or -oil might be an alternative to the use of fish-oil which is commonly used to reach high levels of PUFA’s in the fish fillet.
The dietary inclusion level of BSF meal in carnivore fish is reported to be best between 13 and 20%, but also minimum concentrations of 3 to 5% diet inclusion have been reported to result in decreasing feed conversion ratios in rainbow trout. On the contrary there are also studies available reporting good results up to 40% with no negative effects on morphometric traits like growth rate, weight gain or feed conversion ratio.
In general, meals from insects show different performances regarding growth and quality aspects in different animal species and reveal limited suitability as fish- and soymeal replacement in most cases, so far.
ARE INSECTS SUSTAINABLE WHEN USED IN ANIMAL FEEDS?
Still, it’s unclear which insect species will be the most suitable ones and to which extent fish meal, fish oil and/or soy bean meal can be substituted. The financial sustainability and the market competitiveness will need to be proved in the near future. With the argument of high fishmeal prices and a price plus that recognizes the environmental sustainability above fish meal and soybean meal, high prices for BSF meal were quoted in the past. The insect protein industry still has to fight with very high first costs – mostly due to immense investments and consequential high amortisations. It might be possible that BSF meal or house-fly-larvae meal can compete financially with fish meal on the long run but it is unimaginable that insect meal will replace soybean meal in chicken feeds while keeping the feed at the same price level.
The question regarding the environmental and ecological sustainability of insect meals was answered positively by many studies during so-called life-cycle assessments. For example, housefly larvae meal shows a much better performances compared to soybean meal regarding land use and a much better performance compared to fish meal regarding energy use and global warming potential (Fig. X).
The LCA balance of BSF production can be strongly positive in case unused side streams of agricultural production or food processing is used. Feeding cereals or commodities that are in competition with direct human consumption could be seen critical.
THE OLD FRIEND TENEBRIO AND THE ROLE OF CHITIN IN ANIMAL FEEDS
The larvae of the beetle Tenebrio molitor are produced as pet food for reptiles and birds since decades and are commonly known as “meal worm”. Due to the fact that they are rich in proteins and lipids and as they are easily to be produced in big quantities, Tenebrio molitor meal (TM meal) is also considered as suitable fish meal- and soy bean replacement in aquaculture diets and in poultry diets. Several studies on feeding trials with TM meal inclusion in aquaculture diets were published in the recent years, among them studies on cold water and marine species as well as tropical ones. Comparable to the findings on BSF- and housefly meals, morphometric traits in the fish are negatively influenced from the dietary inclusion above a species-specific threshold ranging between 25 – 43%. Also, a tendency of decreasing ω-3 FA content and ω-3/ω-6 ratio with increasing insect meal inclusion can be observed. The results might suggest that warm water species like African catfish and tilapia can cope better with TM meal than trout and Mediterranean species but the available studies are difficult to be compared and further investigations are necessary.
The role of chitin included in insect meals is discussed brisky in the last years and also recently: Chitin is supposed to develop anti-nutritive properties when administered in higher concentrations to fish because in the insect cuticle it is bound to a complex matrix with proteins and lipids, hardly to digest. The needed enzymes for digestion of this matrix were thought not to be abundant in all fish. Today it seems to be clear that three enzymes needed for the digestions of chitin (chitinase, chitobiase and lysozyme) are present in carnivorous and also in omnivorous fish in different sections of the intestinal tract. Fish species feeding naturally on benthic invertebrates, insects and crustaceans (e.g., common carp or red seabream) show a high ability to digest these and also to digest artificial diets containing shrimp and crab meals. In addition to that, chitin shows positive immunomodulatory effects when administered in low doses (like in insect meals) as it enhances the antioxidant defence system of the fish. An explanation might be eventual similarities between the molecular surface of the exoskeleton of parasites and insects.
FEED SECURITY ASPECTS
The microbial- and general safety aspects of insect-based feed components (and of food insects) in the course of the application at EU-level, were subject of several investigations and discussions. These finally were leading to the admission in 2017 as fish feed component and to the acceptance of some species as “Novel Foods” for human consumption at EU level. The European Authority for Feed and Food Security EFSA, stated in 2015 that in case currently allowed feed materials (for livestock) is administered to insects, the risk of microbial and chemical hazards of resulting animal feeds is not expected to be elevated. This excludes the use of food waste etc. as feedstock for the Black Soldier Fly larvae and further insects, but reduces the risk of transmission of food-born diseases considerably. Furthermore production- and processing methods like drying, grinding or extrusion do have important influence on the bacterial and pathogen load of insect-based feeds. For example, a strong correlation was found between the water content and the microbial load including psychrotrophic bacteria, bacterial endospores and fungi. It is clear that insect meals subjected for animal feeding need to undergo accurate drying procedures besides strictly following the relevant legal directions on the treatment of animal by-products laid down in the EU-regulation (EC) 1069/2009.
In contrast to microbiological hazards, procedures like heating have minimal effect on concentrations of chemical contaminants. The fate of those contaminants can be influenced by concentration- or dilution during processing of insects into insect-derived proteins. Concentrations of chemicals will differ in the protein fraction and oil fraction, e.g. highly lipophilic dioxins will be removed from the protein fraction by de-fatting procedures and remain in the oil fraction.
RESUME AND FURTHER OUTLOOK
Since the ban on insect-based processed animal protein in the EU was lifted for aquaculture feeds in 2017 the young insect industry gained momentum also in Europe. The production processes have been industrialized and automated in the Western hemisphere and also in Asia by several companies and the production capacities have been multiplied. Though it is still unclear which volumes are produces annually worldwide and there still are uncertainties about the extent insect meal and oil can replace marine ingredients in high performing compound feeds. In other words: market uncertainties do exist although the demand for alternative feed proteins of non-plant origin is obvious.
Meals from different insect species appear to perform differently in terms of growth, digestibility, flesh quality and health-promotion in fish and poultry and the expectation of a totally possible replacement of fishmeal will certainly not be reached. Therefor the young insect industry might be well advised to develop mixed insect meals made from various species to minimise obvious amino-acids’ deficiencies. Low dietary inclusion levels of insect meals seem to promote both, the growth performance and the immune status of fish and poultry and should be investigated further.
The reported quality of the BSF-larvae meal in terms of lipid- and protein content is not comparable between different studies but it seems to have big influence on the performance of the diets they are used in. Quality standards in terms of minimum protein- and maximum lipid levels could be a future task for the insect meal industry and more investigations on the suitability of BSF-larvae oil are necessary. Insect oil might be much more suitable as fish oil replacement than expected and further research is needed.
Moreover, focusing on developing insect meals just from the black soldier fly larvae might not be the best of all bets and the industry should urgently look for mass production technologies of more species like locusts, beetles (e.g. Zophobas) and different fly-larvae.
Further reading
[1] Makkar HPS, Tran G, Heuze V, Ankers P. State-of-the-art on use of insects as animal feed. Anim Feed Sci Technol 2014; 197: 1-33.
[2] St-Hilaire S, Cranfill K, Mcguire M A, Mosley E E, Tomberlin J K, et al. Fish offal recycling by the black soldier fly produces a food stuff high in omega-3 fatty acids. Journal of the World Aquaculture Society 2007; 38: 309-313.
[3] Bovera F, Loponte R, Marono S, Piccolo G, Parisi G, Iaconesi V, et al. Use of Tenebrio molitor larvae meal as protein source in broiler diet: effect on growth performance, nutrient digestibility and carcass and meat traits. J Anim Sci 2016; 94: 639-47.
[4] Biasato I, Gasco L, De Marco M, Renna M, Rotolo L, Dabbou S, et al. Effects of yellow mealworm larvae (Tenebrio molitor) inclusion in diets for female broiler chickens: implications for animal health and gut histology. Anim Fed Sci Technol 2017 ; 234: 253-63.
[5] Kono M, Matsui T, Shimizu C. Effect of chitin, chitosan and cellulose as diet supplements on the growth of cultured fish. Nippon Suisan Gakk. 1987; 53: 125-129.
[6] Rumpold B A, Schlüter O K. Potential and challenges of insects as an innovative source for food and feed production. Innovative Food Science & Emerging Technologies 2013; 17: 1–11
[7] van Zanten H, Oonincx D, Mollenhorst H, Bikker P, Bastiaan G, Meerburg B G, de Boer I J M. In: Schenck, R., Huizenga, D. (Eds.), 2014. Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector. Can the environmental impact of livestock feed be reduced by using waste-fed housefly larvae?
