Two experiments were conducted to evaluate the effects of using black cumin seeds (BCS), Artemisia leaves (AL), and Camellia L. plant extract (CLE) in the diets of broiler chicks. Experiment 1 was conducted as a completely randomized design in a factorial arrangement (2 × 2) with 8 replicates of 4 chicks in each battery cage. Factors included 2 levels of BCS and AL (0 and 1%). Experiment 2 was conducted as a completely randomized design with 4 treatments (control, 0.3 and 0.5 g/kg of CLE, and 0.5 g/kg of mannanoligosaccharide) of 8 replicates and 4 chicks in each. Body weight and cumulative feed intake were measured at 21, 35, and 42 d of age. Antibody response against SRBC was measured on d 28 and 42. Blood characteristics, relative weight and length of different parts of the carcass, gastrointestinal pH, villi length, and crypt depth were measured at 42 d of age. Artemisia addition did not affect BW and feed conversion ratio (FCR) but decreased feed intake significantly up to 21 d of age (P ≤ 0.01). Black cumin significantly increased BW (P ≤ 0.05) at 21 and 42 d of age and decreased FCR
