Digestibility Assessment of Black Soldier Fly (Hermetia illucens) Meal in Broilers: Effects of Different Processing Methods

One of the major challenges in animal production today is meeting the growing global demand for protein while reducing environmental impact. Insects have emerged as a sustainable alternative to conventional protein sources such as soybean meal (SBM) and fishmeal (FM), especially in poultry diets. The black soldier fly (Hermetia illucens, BSF) is of particular interest due to its high protein content, efficient feed conversion, and capacity to be reared on organic waste, supporting circular economy practices. In Europe, recent regulatory changes have allowed the inclusion of insect-derived proteins in poultry and swine diets, opening new opportunities for innovation in feed formulation. However, the presence of chitin in BSF may negatively affect nutrient digestibility, particularly of protein, in monogastric animals. This study evaluated the effects of different processing methods of BSF larvae on nutrient digestibility in broiler chickens. An in vivo experimental trial was conducted with 120 one-day-old broiler chickens, divided into four groups: a control group and three experimental groups, in which 25% of the basal corn-soybean diet was replaced by BSF meal processed using enzymatic hydrolysis (BSFE), conventional heat drying (BSFH), or microwave drying (BSFM). Each group consisted of seven replicates with two birds per replicate (14 birds per treatment). Birds were raised under controlled environmental conditions for 21 days, after which 56 animals were selected and assigned to cages based on body weight. Experimental diets were administered gradually from day 26 to day 33. Excreta were collected from days 31 to 33, and birds were slaughtered at day 33 to collect ileal content for chemical analysis. The samples were analyzed for dry matter, crude protein (CP), ether extract (EE), and gross energy (GE), following AOAC protocols. Uric acid content was also assessed to estimate corrected CP values. The results showed that BSF processing method significantly influenced nutrient digestibility, particularly lipid digestibility and energy availability. EE digestibility was significantly higher in BSFE (95.10%) and BSFH (94.88%) compared to BSFM (88.36%). However, BSFM showed the highest metabolizable energy values (AME: 20.76 MJ/kg, AMEn: 19.76 MJ/kg), possibly due to better preservation of lipid quality during microwave treatment. CP digestibility was slightly higher in BSFM and BSFH compared to BSFE, though not statistically significant. These findings suggest that while enzymatic and heat treatments enhance lipid digestibility, microwave processing may better preserve energy content. The choice of processing method can therefore influence the nutritional efficiency of BSF-based feeds. Future research should focus on the economic viability and industrial standardization of these processing techniques to ensure consistent quality and digestibility outcomes.