This experiment was conducted to evaluate the effect of adding Origanum majorana (OM)
powder to domestic pigeon diets on growth performance, feeding and drinking behaviour, blood
hematology, blood biochemical parameters, blood inflammatory and oxidative markers, carcass
characteristics, the weights of lymphoid organs, and and intestinal cecal, and bursa of Fabricius
histology. A random distribution of fifty-four unsexed pigeon squabs (30 days old, average body
weight; 321 g 7.5) into three groups was done. The first group was fed the grower basal diet
without adding OM powder, while OM powder was added at levels of 0.5 and 1% to the basal
diets of the second and third groups, respectively. The changes in growth performance parameters
and feeding and drinking behavior under OM powder’s effect were insignificant. However, the
lymphoid organs (spleen and thymus) significantly increased in weight (p < 0.05) in the OM-fed
groups. Moreover, blood examination showed positive responses to OM powder in terms of blood
cell counts (RBCs andWBCs), and the values of hemoglobin, hematocrit, mean corpuscular volume,
lymphocyte numbers, levels of globulin, and glutathione peroxidase enzyme were significantly
increased. The numbers of heterophils, the ratio of heterophil to lymphocyte, malondialdehyde levels
were reduced (p < 0.05). Histomorphometry examination revealed increases in intestinal villi height,
cecal thickness, and bursal follicle area and number. These results indicated that adding OM powder
to the pigeon diet may improve their immunity, increase their antioxidant status, and correct some
hematological disorders.