Supplementation with Yellow Mealworm (Tenebrio molitor) Larvae Grown on Deoxynivalenol-Contaminated Substrate Improves Growth and Gut Integrity in Broilers

Deoxynivalenol (DON), a Fusarium mycotoxin frequently detected in poultry feeds, impairs broiler health by damaging gut integrity, altering immune response, and compromising growth performance. Insect-derived proteins, such as those from yellow mealworm (Tenebrio molitor) larvae meal (YMW), are gaining interest as an alternate protein source for broiler chickens. Hence, this study evaluated whether defatted YMW produced from larvae reared on DON-contaminated substrates can be safely included in broiler diets. A total of 400 one-day-old Cobb 700 mixed-sex broilers were assigned to four dietary treatments—(1) the control, (2) DON (15 mg/kg), (3) 2% YMW, and (4) 4% YMW—in ten replicates with 10 birds per replicate for 15 days. On day 14, performance parameters, intestinal morphology, tight-junction protein (TJP) gene expression, and CD4+ and CD8+ T-cell populations in cecal tonsils were evaluated. Data were analyzed using one-way ANOVA followed by Tukey’s multiple comparison test. DON exposure reduced body weight by 1% and body weight gain (BWG) by 1.2%, decreased the CD4+: CD8+ T-cell ratio by 80%, and reduced the villus height in the jejunum by 19.8% and ileum by 16%. DON altered the TJP expression by upregulating claudin-2 mRNA expression by 2.1-fold in the jejunum and 5.2-fold in the ileum, and it downregulated claudin-4 expression by 6.4-fold in the ileum (p < 0.05). Dietary inclusion of 2% or 4% YMW from DON-contaminated substrates had no negative effect on growth performance or immune parameters and maintained intestinal morphology and TJP gene expression, comparable to the control groups. In conclusion, defatted YMW produced from larvae reared on DON-contaminated substrates can be safely used as a sustainable alternative protein ingredient in broiler diets.