Evaluation of the potential of black soldier fly larvae (Hermetia illucens) in improving the nutritional value of poultry manure and its effects on performance, egg characteristics, and blood profile of laying hens

Context Sustainable management of poultry manure and the search for alternative protein sources are major challenges in the poultry industry. Black soldier fly larvae (Hermetia illucens, BSFL) offer a promising bioconversion pathway to recycle poultry manure into a nutrient-rich feed ingredient, reducing waste and reliance on conventional protein meals such as soybean. Aims This study aimed to evaluate the potential of BSFL reared on poultry manure to improve manure nutrient value and to assess the effects of partially replacing soybean meal with a BSFL–manure mixture on the performance, egg characteristics, blood biochemical profile, and humoral immunity of laying hens. Specifically, we tested a BSFL–poultry-manure ingredient, obtained by rearing larvae on layer manure and using the resulting mixture, as a partial replacement for soybean meal in the diets of aged laying hens. Methods In total, 320 laying hens were allocated to five dietary treatments, with eight replicates in which soybean meal was replaced with a BSFL–manure mixture at 0%, 5%, 10%, 15%, or 20% of the diet for 7 weeks. Parameters evaluated included laying performance (egg production rate, feed intake, and feed conversion ratio), egg-quality traits (egg weight, shell thickness, shell strength, yolk color, and Haugh unit), and selected blood biochemical and immune indices, including serum immunoglobulin G (IgG) concentration. Key results Dietary replacement level had no significant effect on bodyweight, egg weight, shell strength, albumen height, Haugh unit, or shell weight. Yolk weight increased at 5% replacement, whereas eggshell thickness decreased at 15–20% replacement levels. Serum total protein, albumin, cholesterol, and low-density lipoprotein were unaffected, whereas high-density lipoprotein increased at 10%. Immunological assessment showed higher total immunoglobulin and IgG concentrations at 5% replacement, suggesting improved humoral immunity. Conclusions Partial substitution (5–10%) of soybean meal with BSFL–manure mixture improved aspects of yolk deposition, lipid metabolism, and immune function without compromising productive performance. Implications Incorporating BSFL bioconverted poultry manure into layer diets can support sustainable nutrient recycling and reduce dependence on conventional protein sources. However, higher inclusion levels may require precise calcium–phosphorus and amino acid balancing to maintain eggshell integrity.