Exploring side streams upcycling for crickets farming: Insects biology and chemical composition

This study formulated and evaluated different feeds for farm crickets (Gryllus assimilis) aiming to enhance productive performance, and understand protein, and fatty acid content accumulation. A control feed based on corn-soybean meal-corn oil, recommended by FAO, was compared with a fresh kale supplement, and low-fat variant lacking corn oil. Additionally, three other feeds incorporating the side streams wheat germ, brewing spent grains (BSG), and peanuts were also investigated. The biological parameters of the crickets were influenced by the feeds, with improved early-stage survival rate and adult weight observed with kale, wheat germ, and BSG feeds. The body weight of the insects ranged from 0.5 to 0.75 g. An adequate fat content (>4 %) in feeds is crucial for crickets short development period, oviposition, and egg viability. The total protein content of crickets fed with wheat germ, BSG, and peanut feeds was lower compared to the control, kale, and low-fat feeds, due to lower protein content in side stream feeds. Fatty acid analysis revealed a predominant abundance of C18:2, followed by C18:1, C16:0, and C18:0. BSG resulted in a high abundance of total polyunsaturated fatty acid (PUFA), mainly C18:2 (n = 6). Utilizing brewery waste for feed development enhances the sustainability of cricket protein production for food and feed uses.