Abstract The main objective of this study was to determine the effects of various levels of dietary
black cumin seed (BCS) on immune-responsiveness, broiler performance and lymphoid organs’
ratio scores against NDV, IBV and IBDV vaccines. One hundred and sixty-one day-old broiler
chicks (Rose 308) were randomly assigned into five groups with three replicates of seven birds each
(21 chicks per group) and fed diets supplemented with 0.7%, 1.4%, 2.1% or 2.8% black cumin. All
chickens were bled weekly for 35 days post-treatment. Body weights, thymus, bursa and spleen ratio
scores were determined at 21 and 35 days while body weight was determined weekly