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 A total of 320 laying hens were allocated to five dietary treatmentswith eight replicates in which soybean meal was replaced with a BSFL–manure mixture at 0, 5, 10, 15, or 20% of the diet for seven 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 IgG concentration. Key results Dietary replacement level had no significant effect on body weight, egg weight, shell strength, albumen height, Haugh unit, or shell weight. Yolk weight increased at 5% replacement (P 0.05), whereas eggshell thickness decreased at 15–20% replacement levels (P 0.05). Serum total protein, albumin, cholesterol, and LDL were unaffected, but HDL increased at 10% (P 0.05). Immunological assessment showed higher total immunoglobulin and IgG levels at 5% replacement (P 0.05), 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.
Salehifar et al. (Thu,) studied this question.