Biomass and meal production of Gryllus assimilis subjected to different plant substrates

Abstract Recent research has focused on optimising insect production systems as a source of animal protein for inert diet formulation. However, information remains limited on the zootechnical responses of insects reared on plant-based substrates commonly used in livestock feeds. This study evaluated the growth performance of Gryllus assimilis fed wheat, soybean, or rice bran and characterised the proximate composition, colour and water activity of the resulting meals. Crickets were reared from the nymph stage for 25 days on the different substrates and subsequently harvested to determine production indices and physicochemical meal properties. Growth-related variables, including final weight, weight gain, daily weight gain, final biomass and productivity, did not differ significantly among treatments ( ) and feed conversion was likewise unaffected by substrate. Meal composition varied among treatments: wheat and soybean brans yielded meals with higher crude protein contents (56.44 and 59.42%, respectively), whereas rice bran produced meals with greater crude lipid content (25.15%). Meal yield also differed significantly among treatments ( ), with wheat and rice bran producing higher numerical values. All meals exhibited low water activity (0.38-0.42), corresponding to physicochemical conditions unfavourable to microbial growth. Colour parameters varied with substrate, with soybean- and wheat-based diets producing lighter meals and rice bran resulting in darker products. Overall, all three brans supported G. assimilis rearing under the tested conditions, while substrate selection modulated several nutritional and physical meal characteristics. These findings expand knowledge of G. assimilis production and support further evaluation of this species for insect-based ingredient production.