This study was carried out to assess the effect of oyster mushroom (Pleurotus ostreatus) and probiotic alone or their combination on the growth performance, organs relative weight and some blood attributes of male broilers. A total of 256 male chicks (Ross 308) were randomly assigned to four treatments with four replications (16 birds per replication). The experimental treatments were maize–soybean meal basal diet and basal diet supplemented with 2 g/kg of oyster mushroom or 450 mg/kg of probiotic, or their combination. Results showed that the inclusion of the oyster mushroom powder decreased (P<0.05) feed intake and body weight gain of broiler chicks during 1–21 days of age. Dietary supplementation of mushroom or probiotic decreased (P<0.05) bird’s body weight and weight gain during the entire experiment. The combination of mushroom and probitic had no effect (P>0.05) on birds’ performance. Inclusion of the probiotic to the diet decreased (P<0.05) relative weight of abdominal fat. Mushroom, probiotic and their combination had no effect (P>0.05) on relative lengths of duodenum and jejunum at 21 and 42 days of age. However, ileum relative length at 21 days of age was higher (P<0.05) in chicks that received oyster mushroom in their diet. Experimental diets did not affect antibody response against Newcastle disease virus, triglyceride (TG), cholesterol, low density lipoproteins (LDL) and very low density lipoproteins (VLDL) concentrations of plasma. High density lipoproteins (HDL) was higher (P<0.05) in birds were fed by probiotic. In conclusion, the results of the present study showed that inclusion of mushroom and probiotic alone decreased growth performance while their combination had no beneficial effects on birds’ performance. However, probiotic supplementation decreased abdominal fat of carcass and increased the HDL concentration in plasma.
