¹Ahmadu Bello University, Faculty of Veterinary Medicine, Department of Veterinary Pathology, Zaria, NIGERIA
²Abubakar Tafawa Balewa University, Faculty of Veterinary Medicine, Department of Veterinary Pathology, Bauchi, NIGERIA
³Federal University of Agriculture Abeokuta, College of Veterinary Medicine, Department of Veterinary Pathology, Abeokuta, NIGERIA
⁴Ahmadu Bello University, Faculty of Veterinary Medicine, Department of Veterinary Medicine, Zaria, NIGERIA DOI : 10.9775/kvfd.2025.35718 Infectious bursal disease (IBD) compromises the immune system of young birds, lowering protective antibody levels. This study assessed antibody and serum interferon-gamma (INF-γ) responses in cockerels pre-treated with Nigella sativa seed powder (NSSP) and challenged with very virulent IBD virus (vvIBDV). One hundred one-day-old Dominant Black Marshal Cockerels were assigned to five groups (A-E, 20 birds each). Groups A and B received standard feed from 1-42 days of age; groups C and D received NSSP from 21-27 days of age; group E received NSSP continuously from 1-42 days of age. All birds were vaccinated against Newcastle disease. On day 28, groups B, D, and E were orally challenged with vvIBDV. Blood samples were analyzed for IBD antibody and INF-γ. Maternal antibody titres declined below protective levels by 14 days in groups A-D but remained protective in group E. Post-challenge, groups D and E showed significantly higher antibody titres, with group E maintaining the highest levels. Serum INF-γ increased from 7 to 21 days of age in all groups, and from 29 to 42 days of age, group E exhibited the highest levels compared to D and B. Pre-administration of NSSP slowed maternal antibody decay and enhanced post-challenge immune responses. Dietary inclusion of NSSP may therefore provide a natural strategy to sustain IBD antibody protection and improve immune performance in poultry. Keywords : Antibody, Infectious bursal disease, Interferon gamma, Nigella sativa