Impact of black soldier fly larvae (Hermetia illucens) inclusion in broiler diets on growth performance, specific fecal bacteria, and intestinal morphometry

Abstract Insect meals, particularly those from black soldier fly ( Hermetia illucens ) larvae, represent a sustainable protein alternative that supports circular economy principles by recycling agro-industrial by-products. This study evaluated the effects of including full-fat black soldier fly larvae (BSFL) in broiler diets on growth performance, specific faecal bacteria, and intestinal morphology. Four dietary treatments were tested: a Control diet, control with bacitracin methylene disalicylate (BMD; 0.2 g/kg), 5% BSFL and 10% BSFL. From 7 to 35 days, birds on the Control diet consumed less feed ( ) but achieved a 4% higher average daily gain than all other treatments. Birds fed 10% BSFL had poorer feed conversion compared with the remaining diets ( ). Total coliform counts were higher ( ) in birds receiving 10% BSFL, while E. coli , Lactobacillus sp., and Enterococcus spp. were unaffected ( ). Control-fed broilers exhibited longer villi and greater villi area compared with the BSFL and BMD diets ( ). Crypt depth was higher in birds fed the Control and 10% BSFL diets than in those given BMD, with intermediate values for 5% BSFL ( ). The villi-to-crypt ratio was lowest in the 10% BSFL group ( ). Increasing BSFL inclusion linearly reduced average daily feed intake, average daily gain, villi length, villi area, and villi-to-crypt ratio ( ). Overall, full-fat BSFL inclusion impaired growth performance and intestinal health indicators, particularly at 10%, suggesting inclusion levels should not exceed 5%.