¹Airlangga University, Faculty of Veterinary Medicine, 60115 Surabaya, INDONESIA
²Airlangga University, Faculty of Veterinary Medicine, Basic Veterinary Medicine Department, 60115 Surabaya, INDONESIA
³Airlangga University, Faculty of Veterinary Medicine, Animal Husbandry Department, 60115 Surabaya, INDONESIA
⁴Research and Development Division, 40286 Bandung, INDONESIA DOI : 10.9775/kvfd.2026.37133 Passive immunization using immunoglobulin yolk (IgY) has attracted considerable attention as a prominent antibiotic alternative in poultry health management. However, its practical application is constrained by vulnerability to gastrointestinal degradation, limiting its immunoprotective potential against enteric pathogens like Salmonella Pullorum. To address this gap, this study investigated the protective efficacy of encapsulated IgY on bursa of Fabricius integrity and antibody responses in challenged Cobb 500 broilers. Under a completely randomized design, the chickens were allocated into a negative control group, a positive control group, and three treatment groups receiving encapsulated IgY at doses of 0.11, 0.22, and 0.34 mL/day, respectively. Encapsulated IgY administration was initiated at 8 days of age and continued for 14 consecutive days until the challenge infection was performed at 22 days of age via intramuscular injection into the pectoralis major muscle using a bacterial dose of 1.5×10⁸ CFU. AGPT analysis demonstrated delayed antibody kinetics post-infection. Crucially, encapsulated IgY significantly countered Salmonella-induced lesions through distinct structural protections: minimizing follicular depletion (P1: 2.00±0.37 vs K+: 2.80±0.14), reducing lymphoid cell necrosis (P3: 1.36±0.17 vs K+: 2.60±0.20), and dose-dependently restoring plica diameter up to 243.02±9.5 μm (P1) and 224.78±20 μm (P2) at the highest dose. Although IgY technology shows immense therapeutic value, its encapsulated potential in veterinary medicine remains underexplored. This study provides a scientific rationale for utilizing encapsulated IgY as a physiological protective factor, advancing sustainable health management in livestock production, which directly aligns with current priority areas in veterinary research. Keywords : Broiler Chickens, Bursa of Fabricius, Encapsulation, Immunoglobulin Yolk, Salmonella Pullorum