Partial insect-based meal inclusion in the diets of Ross® 308 broilers upregulates growth and immune related genes

This work investigated the effects of black soldier fly ( Hermetia illucens L.) larvae meal (BSFLM) on growth- and immune-related gene expression in Ross 308 broilers. Birds were fed diets containing soybean meal (SBM), fishmeal (FM), combinations with BSFLM, or BSFLM alone. Growth, organ weights, immune genes [interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrotic factor alpha (TNF-α), interferon-gamma (IFN-γ)] and growth-related genes [chicken growth hormone (cGH), insulin growth factor 1 (IGF-1)] expression were measured. Our results demonstrate that birds fed FM+BSFLM had significantly higher final liveweight, average daily weight gain (ADG), and low feed conversion ratio. Birds fed FM+BSFLM showed highest carcass weight, while the SBM-only group yielded the lowest. Average daily feed intake (ADFI) differed significantly, and birds fed SBM+BSFLM had the highest. The IL-2, IL-6, TNF-α, IFN-γ, IGF-1 and cGH gene expressions were significantly upregulated in the liver and spleen of birds fed diets containing BSFLM. Growth-related genes (cGH) positively correlated with liveweight, body weight gain, and ADG. Insect-based diet upregulates the expression of genes associated with protein synthesis, muscle hypertrophy, better feed efficiency, cell proliferation and adaptive immunity, leading to improved productivity in partial replacement groups, while complete replacement showed patterns suggesting nutritional stress.