Effect of Rearing Substrate on Nutritional Composition, Growth Performance and Multi-Omics Characteristics of Black Soldier Fly

To address global protein shortages, black soldier fly (<i>Hermetia illucens</i> L.) larvae (BSFL) can be used as a sustainable feed alternative, with nutritional quality dependent on rearing substrates. This study compared quail feed (QF), food waste (FW), and quail manure (QM) for BSFL cultivation. Larvae raised on FW and QM had higher crude protein content (47.5-48.3%) than the QF group, while QF-reared larvae contained more fat (33.2%) than the other groups. QM led to larvae with the highest mineral content, and larvae from the FW group showed elevated calcium levels (5.6%). The FW-reared larvae also demonstrated superior growth, with a yield of 186.3 g/kg and a dry-matter conversion rate of 13.7%. Multi-omics analyses indicated substrate-specific differences in gut microbiota and metabolic pathways. FW promoted beneficial bacteria such as <i>Lactobacillus</i>, enhancing nutrient assimilation, while QF and QM upregulated lipid and mineral processing. For sustainable protein production through BSFL rearing, FW was the most suitable substrate among the three tested, offering a balanced combination of high larval protein content and efficient growth.