Impact of partially defatted black soldier fly larvae meal on coccidia-infected chickens: effects on growth performance, intestinal health, and cecal short-chain fatty acid concentrations

Abstract

Black soldier fly larvae meal (BSFLM) stands out as a promising nutritional resource due to its rich bioactive substances and favorable protein profile. Nonetheless, its potential to mitigate coccidia infection in broilers remains uncertain. This study aimed to evaluate the impact of partially defatted BSFLM (pBSFLM) on growth performance, nutrient utilization, and intestinal health, focusing on morphology, immunology, and cecal fermentation in coccidia-infected broilers. Over the initial 13 d, 480 newly-hatched Cobb 500 male birds were allocated to three diets with increasing pBSFLM concentrations (0, 60, or 120 g/kg). At d 13 post hatching, chicks within each dietary group were further allotted to non-challenge or challenge subsets, generating six treatments in a 3 × 2 factorial arrangement. Challenged birds were orally administered oocysts of E. maxima, E. acervulina, and E. tenella (25,000:125,000:25,000). During the infection phase (d 13 to 19), linear interactions between Eimeria and pBSFLM were observed in gain to feed ratio (G:F) (P < 0.05) and cecal interferon-γ (IFN-γ, P < 0.05), with a tendency in cecal acetate concentration (P = 0.06). A quadratic interaction was observed in crypt depth (CD, P < 0.05). Incremental pBSFLM inclusion negatively affected G:F, CD, IFN-γ, and acetate productions in the ceca under coccidia challenge. Conversely in non-challenged birds, the impact of pBSFLM varied from neutral (e.g. G:F) to potentially advantageous (e.g. acetate). Challenged birds exhibited decreased (P < 0.01) BW, BW gain, feed intake (FI), and the apparent ileal digestibility and total tract nutrient utilization of DM, gross energy, and nitrogen (N). Eimeria challenge reduced (P < 0.01) serum carotenoid concentrations, decreased the villus height to crypt depth ratio (VH:CD, P < 0.01), and increased concentrations of branched-chain fatty acids, specifically isobutyrate (P = 0.059) and isovalerate (P < 0.05) in the cecum. Dietary pBSFLM addition linearly reduced (P < 0.05) BW, FI, and N utilization. Tendencies (P < 0.06) were observed where pBSFLM linearly decreased VH:CD and reduced goblet cell density. Increasing pBSFLM supplementation, particularly at 12%, adversely affected growth, ileal morphology, cecal acetate production, and downregulated key cytokine expression in response to coccidia infection.