Why should we feed pigs and poultry with insects protein?

On Monday 5th April, ValuSect submitted its feedback to a European Commission public consultation on "Authorisation to feed non-ruminants with ruminant collagen / gelatine and with proteins from insects, pigs and poultry".

The consortium highlighted the advantages to authorise the use of insects proteins to feed poultry and pigs: high nutritional value, immunological advantages, environmental benefits and safety aspects.

1.   Introduction

In order to continue feeding the world population, it is necessary to optimise our food-producing sectors. This will be a major challenge since models predict an increase in world population the following decades, which means also a rising demand for animal proteins. This does not only imply an increase in human food production, but an increase in animal feed production as well. Currently, the leading resources of feed protein are oilseed meals, fish/animal proteins and biofuel coproducts¹. The production of oilseeds, such as soy beans, contributes to deforestation significantly². Furthermore, fisheries for the production of fishmeal exceed the maximum capacity to maintain a sustainable system³. Nevertheless, the need for protein will proceed to grow. Therefore, research is conducted on the potential of alternative protein resources, such as insects for feed and food.

2.   Nutritional value

Research has shown that insects are mainly composed of protein and fat⁴, with the remaining being carbohydrates, fibres, vitamins and minerals. Insect protein contents can go up to 82%⁵, although commercially reared insect species like mealworms, black soldier fly larvae, desert locusts and house crickets have protein contents of respectively 53, 42, 57 and 63%⁶, which is still significant. Insect proteins, like those present in black soldier fly larvae have favourable amino acid profiles, which are comparable to amino acid profiles in fishmeal⁷. These proteins therefore are  an interesting alternative protein source.

Insects can also contain high fat contents. The fatty acid profile varies among different species, but is also dependent on the substrates on which the insects are grown. As an example, it is possible to grow black soldier fly larvae that contain high amounts of omega-3 and omega-6 fatty acids by using feed substrates rich in these fatty acids⁸.

Moreover, insects’ edible fraction is higher than that of conventional farm animals. 80 to 100% of an insect is edible, while poultry and pork have on average an edible fraction of 55%. For ruminants, this edible fraction is even lower⁹.

Insects are well accepted by farmed animals as feed. For many fish, poultry and pig species, insects are part of their natural food source. Many fish species have adapted their physiology to hunt insects and the diet of some wild Salmonidae species contain up to 70% of insects¹⁰. Feed trials conducted with poultry species indicated that diets containing insects are preferred over diets that lack insects¹¹. In the wild, pig species forage and dig to find and eat insects¹¹. Trials were conducted for pigs, with dietary replacement of fishmeal by black soldier fly larvae meal. Research showed a full replacement of fishmeal by full-fat larvae meal was possible and did not adversely affect growth and blood characteristics¹². For poultry, black soldier fly larvae (BSFL) have a good level of acceptance as well¹³. A study with a 10% inclusion of BSFL in poultry feed highlighted the possibility of using them as ingredients¹⁴. Moreover, feeding live BSFL to broilers and laying hens improves animal welfare^15,16.

3.   Immunological advantages in feed

Insects are not only an interesting protein source, but also have immunological advantages. The most important advantageous characteristics are the presence of chitin, the favourable fatty acid profile and their beneficial effects on the gut microbiota of the animal they are fed to¹⁷. Chitin and its derivatives are beneficial for the digestive system. Research suggests it promotes the antioxidant status, immune response and intestinal development of poultry^18,19. Furthermore, chitin and chitosan have antimicrobial traits: it impedes bacterial metabolism and RNA transcription^20–22. Chitin, combined with the fatty acid profile of insects such as the black soldier fly, has an advantageous effect on the gut microbiota of poultry. Poultry cannot fully digest chitin. Once the remaining chitin reaches the ceca, the gut microbiota can use it as prebiotics to enhance the production of short-chain fatty acids (SCFAs), such as acetate and propionate²³. These are indispensable for the animal’s metabolism and gut physiology²³. Furthermore, they inhibit virulence factors of pathogenic bacteria²⁴. Research has indicated that the black soldier fly in feed caused changes in the cecal microbiota of poultry due to diversification of microbiota. There is a strong correlation between microbial diversity and SCFAs content²³.

In insects such as black soldier fly larvae, dodecanoic acid makes up between 29 and 50% of the total fatty acid profile. Dodecanoic acid has an antimicrobial effect on gram-positive bacteria^25,26. Furthermore, lauric acid can transform into monolaurin, which could dismantle the lipid membrane of bacteria²⁷. Both in vitro tests and tests with piglets have used lauric acid to combat gram-positive bacteria such as D streptococci (2 log fold reduction in vitro). Gram-negative bacteria such as coliforms were almost unaffected²⁵. In poultry, it significantly lowered the amount of Bifidobacterium and Lactobacillus, which could be attributed to the antimicrobial effects of chitin and saturated fatty acids such as lauric acid²⁸.

4.   Environmental benefits

Insects seem to be a promising agent in food and feed since they are highly efficient in converting organic matter into biomass. They have the ability to accumulate protein very efficiently. Under optimised diets, poultry can convert 33% of dietary protein into edible biomass, while black soldier fly larvae are able to convert 43-55% into edible biomass²⁹. When it comes to feed conversion ratio, they surpass other farm animals, such as ruminants and pigs²⁹. This means that a higher proportion of ingested feed is converted into biomass. One explanation for this is insects being cold-blooded, thus not having to spend energy on the regulation of their body temperature⁹. In order to reach a high efficiency, it is important to gain knowledge about their nutritional requirements and pay attention to genetic selection to establish more efficient strains¹⁰.

The biggest environmental impact of most commonly-used protein sources like milk, eggs and meat is associated with agricultural field activities used to grow and harvest crops, required to feed the animals³⁰. Therefore insects are extremely interesting because they can be reared on a wide range of substrates, such as agricultural side streams and supermarket food waste³¹. Since insects can be reared on unused or underused organic streams, they can possibly be the missing link towards increased circularity in the agriculture and food industry. Thus, both waste reduction and biomass production can be addressed simultaneously. Waste reduction is an important topic, since 27% of the world’s annual agricultural produce (worth US$750 billion) goes to waste^10,32.

With regards to land-use efficiency, insects are an efficient protein source. It is possible to stack boxes in which insects are grown, a method known as ‘vertical farming’. This is possible since larvae of multiple insect species, such as those of black soldier flies, do not require much space and any source of light for their development³³.

Since they grow and breed quickly, it is possible to have multiple cycles of insects farmed every year. Their land use efficiency can be up to 70 times higher than commonly used materials of vegetal origin⁵.

Insects, such as house crickets, desert locusts, mealworms also produce a low greenhouse gas equivalent when compared to traditional farm animals. They produce merely 1% of the greenhouse gasses compared to ruminants. Additionally, the ammonia emissions for these insect species is lower than conventional farm animals³⁴.

5.   Safety aspects

In order to evaluate the safety risks of insects in food and feed, it is important to evaluate chemical, microbiological and allergenic hazards, as well as the presence of prions.

Feed substrates on which insects are grown are the main exposure route of insects to chemical hazards. Research has shown that essential heavy metals do not accumulate in insects^35–37, although precaution should be taken with high levels of cadmium and arsenic in feed substrates as cadmium may accumulate in the black soldier fly³⁸ and arsenic in yellow mealworm larvae³⁹. The accumulation of certain EU-regulated mycotoxins has already been investigated: those that were tested did not accumulate in black soldier fly larvae, but were metabolized instead^40,41.

It should be noted that no indications are present that currently reared insect species for the use for food and feed produce reactive, irritating or toxic substances in the life stages during which they are used for consumption⁴². The microbiological hazards in insects used for food and feed are affected by both the intrinsic microbial community linked to the insect as the microbial community introduced during the rearing and processing⁴². The substrate used for insect rearing influences the insects’ microbial load. Therefore the hygienic conditions of both the substrates and farming environment are important⁴³. Heat treatment may eliminate most microbiological hazards⁴⁴. However, in order to eliminate bacterial spores, sterilisation at high temperature under high pressure will be necessary^44,45  .

There are allergens present in insects which one should be aware of. Certain proteins may trigger allergic reactions or play a role in cross-reactivity with crustaceans or dust mites^46,47. For example, mealworms contain the pan-allergin, which is also commonly found in prawn and shrimp⁴⁷. Chitin, found in the insects’ exoskeleton can play a role in allergenicity, but so far the mechanisms are poorly understood^10,42,43.

No specific prionic diseases have been found in insects due to the lack of a PrP-encoding gene⁴³. Nevertheless, they might be able to act as mechanical vectors of prions. Thus, risk substrates of ruminant origin should not be used as feed substrates for insects⁴⁸.

6.   Conclusion

Actions need to be taken in order to supply sufficient proteins to keep feeding the world population. Therefore, it is necessary to find alternative and more sustainable protein sources. Insects as food and feed show a great potential, since they can successfully convert low-value organic by-products into high-value protein. Proteins produced by insects have environmental benefits compared to farmed animals, such as lower greenhouse gas emissions, lower land use and favourable conversion ratios. Insects in feed have immunological advantages for the animals they are fed to. Insects are safe to be used as feed, if one pays attention to allergic factors, their feed substrates, keeping a hygienic environment and proper processing techniques. Since they are accepted as a feed source by numerous farmed animals, they can be a potent source of renewable protein in the feed industry.

7.   References

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