Agroscope, 1725 Posieux, Switzerland

Insects as alternative protein sources for imported protein-rich feed

Saprophage insects convert diverse biowaste streams into protein- and fat-rich insect biomass generated independently of arable land. Since 2017, 7 insect species have been approved for fish feed in the EU so far. The most promising species are: black soldier fly (SF; Hermetia illucens), house fly (HF; Musca domestica), mealworm (MW; Tenebrio molitor), and house cricket (HC; Acheta domesticus). The larvae and nymphs are the most nutritious stages with crude protein (CP) contents ranging from 400 g/kg DM for SF to 665 g/kg DM for HC. The fat contents vary considerably and can reach on average 300 g/kg DM in the case of SF and MW larvae. Commercial products of insect larvae are often marketed as defatted meals with a CP content of around 620 g/kg DM. Protein quality varies with insect species and substrate. Compared to soy protein, insect proteins systematically contain lower proportions of cystine, phenylalanine and arginine. With 6.5 g Lys/100 g CP, protein from HF exceeds the soy profile, while SF, MW and HC are slightly below 6 g Lys/100 g CP. The amino acid digestibility of insect protein fed to piglets and broilers is usually over 80 %. The fatty acid profiles of insect fats are species-dependent and can be modulated via the feed basis. Fat from SF is characterized by a high degree of saturation mainly caused by the high content of lauric acid (C12:0) of more than 40 %. This results in a favorable low PUI index (fat quality index) for fattening pigs. The fat of MW is rich in oleic acid (C18:1), while HG fat stands out for its high percentage of C16:1. The production of antimicrobial peptides (AMP) provides insects with an efficient defense mechanism that guarantees their survival in environments with high germ loads. Insects are regarded as a reservoir for future antibiotics. Soldier fly larvae are particularly qualified for the recycling of biowaste. Their protein is a sustainable alternative to soya and fish meal and thus increases feed autonomy. In addition, the extracted fat can be converted to biodiesel. Knowledge gaps on the use of insect protein in pig feeding indicate a need for further research.

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