Background: Insect species are suitable for farming as 'mini livestock' for human and animal consumption. It is important to assess the protein quality of relevant species to understand the potential of these novel protein sources in future sustainable food systems.

Objectives: To determine the protein quality of five insect species: lesser mealworm (LMW), yellow mealworm (YMW), house cricket (HC), banded cricket (BC) and black soldier fly (BSF) using the digestible indispensable amino acid score (DIAAS) in a pig model.

Design: Five diets were formulated to contain 10% insect crude protein (CP). A nitrogen (N)-free diet was included to estimate endogenous losses. In a 6 × 6 Latin square design, 6 ileal cannulated crossbred [Duroc × (Danish Landrace × Yorkshire)] male pigs with an initial body weight of 35 ± 2 kg were fed the 6 diets. Each diet was fed for 1 wk over 6 wk. Ileal digesta was collected for 8 h on days 5 and 7 each wk. Analyzed CP, amino acid (AA) contents and calculated values of standardized ileal digestibility (SID) for CP and AAs were used to assess the DIAAS of each insect.

Results: The DIAAS for young children aged 6 mo-3 y and for older children, adolescents, and adults identified sulphur AAs (cysteine + methionine) as the first limiting AA in all 4 species of cricket and mealworm. For young children, both cricket species had DIAAS above 75 and for older children, adolescents and adults both cricket species and LMW had DIAAS > 75.

Conclusions: Both cricket species (HC and BC) are classified as good-quality protein sources for young children aged 6 mo-3 y and for older children, adolescents and adults. One mealworm species, LMW, is a good-quality protein source for older children, adolescents and adults.