Nutritional Characterisation of <i>Acheta domesticus</i> at Different Developmental Stages for Application in Animal Feed

The house cricket Acheta domesticus has emerged as a promising alternative protein source for animal nutrition; however, limited information is available on how developmental stage influences its nutritional characteristics. This study compared subadults (30-day-old) and adults (40-day-old) crickets in terms of chemical composition, mineral profile and heavy metal-content, fatty acid profile, crude protein digestibility, and chitin yield. Adults showed significantly higher dry matter, crude protein, nitrogen-free extract, and protein digestibility values, whereas subadults exhibited ether extract and ash content, resulting in higher gross energy. Mineral analysis revealed low levels of toxic elements in both groups, with adults displaying higher selenium and phosphorus concentrations. Fatty acid profiling highlighted marked developmental differences: subadults had higher MUFA and linoleic acid, alongside an unbalanced ω6/ω3 ratio, while adults exhibited a more favourable fatty acid distribution, including increased long-chain ω3 and ω6 derivatives such as arachidonic acid. Chitin extraction revealed no significant differences between groups, although a strong negative correlation was identified between chitin content and crude protein digestibility. Overall, the results indicate that while adults provide superior protein quality and a more balanced lipid profile, subadults offer advantages in terms of energy content and potentially reduced production time. These findings support the strategic integration of A. domesticus at different developmental stages into animal feed formulations and underscore the importance of stage-specific nutritional characterisation for optimising insect-based feed ingredients.