Effects of dietary inclusion of black soldier fly larvae and grasshopper on broiler performance, gut health, and related gene expression

A total of 546 one-day-old male commercial broiler chicks were used to evaluate the effects of dietary inclusion of black soldier fly larvae (BSFL, Hermetia illucens ) and grasshopper (GH, Dociostaurus maroccanus ) powders at varying levels on growth performance, ileal digestibility, specific bacterial species, small intestinal morphometry and morphology, and the expression of Mucin 2 ( MUC2 ) and Claudin 1 ( CLDN1 ) genes.Chicks were randomly assigned to seven treatments with six replicates (13 birds each) in a completely randomised design. Experimental isonitrogenous and isocaloric diets included: (1) basal maize-soya diet (control), (2) 8% BSFL, (3) 16% BSFL, (4) 24% BSFL, (5) 8% GH, (6) 16% GH, and (7) 24% GH, partially replacing soybean meal. Feed and water were provided ad libitum . The BSFL24 diet significantly improved body weight gain and ileal protein digestibility ( ) without affecting dry matter, calcium, or phosphorus digestibility ( ). GH24 significantly reduced caecal Escherichia coli counts ( ). While small intestinal segment weights were unaffected, total intestinal length and relative jejunal length were significantly altered in BSFL24 and GH24 groups ( ). GH24 also significantly influenced intestinal morphology ( ). MUC2 expression was significantly upregulated in GH8 compared to BSFL groups ( ), whereas CLDN1 was significantly upregulated in BSFL-fed groups ( ). These findings demonstrate that insect-based proteins, particularly at 24% inclusion, can serve as effective and sustainable alternatives to conventional feedstuffs, enhancing broiler growth, gut health, and nutrient utilisation.