Effects of Soybean- and Cottonseed-Based Diets on Growth Performance and Gut Microbiota of Black Soldier Fly Larvae

The impacts of various feed substrates and processing treatments (boiling and extrusion) designed to reduce plant-derived antinutritional factors on the growth and development, nutritional composition, and intestinal microbiota of black soldier fly larvae (BSFL) were evaluated. The research revealed that, except for the soybean flour group, the cottonseed meal group and the treatment group with antinutritional factors removed showed better growth trends compared to the Gainesville House Fly Diet group. The heat-processed groups had higher maximum larval weights, survival rates, and feed conversion rates than the untreated groups. Additionally, BSFL fed with high-protein and high-fat experimental diets generally exhibited higher fat and protein contents. Plant-derived antinutritional factors in the test substrates significantly affected the intestinal microbiota and their metabolic pathways in BSFL. Gut microbiota—including phyla such as Firmicutes, Proteobacteria, and Bacteroidetes, along with various lactic acid—and short-chain fatty acid-producing genera—and metabolic pathways related to carbohydrates, amino acids, cofactors, and vitamins, play crucial roles in helping BSFL resist plant antinutritional factors.