Insects are an up-and-coming feed additives for animals, because they contain not only valuable nutrients, but also special components that, presumably, are able to affect the microbiota of animals and improve their health. In this article we will discuss some of them.
These useful ingredients were discussed in an article published in the “Journal of Food and Feed” magazine. In this review article, the authors discuss the effects of chitin, lauric acid and antimicrobial peptides contained in insects. These components can be useful for meat and dairy animals, and, for example, can reduce the need for antibiotics.
The first beneficial component of insects is chitin, which is contained in the outer skeleton of crustaceans and insects. Chitin and its derivatives can stimulate cells of the innate immunity. The example of feeding broiler chickens with shrimp chitin has shown that growth of pathogens such as Escherichia coli and Salmonella is suppressed in the intestine. In the course of other tests, it was found that feeding chickens with chitin feed leads to a decrease in fat deposits and, possibly, the production of more tender meat. This is due to the hypolipidemic and hypocholesterolemic properties of this substance. Experiments on laying hens who were fed with about 1.02 g of chitin from black soldier fly larvae every day showed an increase in immunity and resistance to diseases.
The second beneficial component of insects is lauric acid, known for its antiviral and antibacterial activity. Black soldier fly larvae are rich in fat, its content varies from 15% to 49% in dry matter. The composition of fatty acids in the prepupa is high in the content of medium chain lauric acid (C12: 0). The fat from prepupa grown on organic waste with a high starch content contains up to 60% of this acid. A recent in vito study found that fat of the black soldier fly prepupa (0.58 g C12: 0/100 ml) inhibits the growth of some bacteria, and has the most striking antibacterial effect on D-streptococci, infectious agents in pigs.
The third beneficial component of insects is peptides, including antimicrobial ones. Today, insects have a greater diversity of these substances (more than 150 peptides). These peptides are classified as follows:
- α-helical peptides (cecropin, moricin);
- cysteine peptides (for example, insect defensin and drozomycin);
- Proline enriched peptides (PRPs) (apidecin, drozocin and lebocin);
- glycine enriched peptides (GRPs) (attacine and gloverin) (Otvos, 2000).
In pigs and broiler chickens, antimicrobial peptides increase the growth rate, promote the absorption of nutrients, heal the intestine, improve its microbiota, and also increase immunity.
Tests have shown that diarrhea in weaned piglets was reduced when kept on a diet with the addition of flour from mealworm, large mealworm and larvae of domestic fly. This result is attributed to the antimicrobial effect of insect peptides. The antimicrobial peptide P5 can be used as an alternative to antibiotics to increase the growth rate of broiler chickens.