Evaluation of Oyster Mushroom (<i>Pleurotus Ostreatus</i>) as a Biological Growth Promoter on Performance, Humoral Immunity, and Blood Characteristics of Broiler Chicks
This study was conducted to determine the impacts of two levels of oyster mushroom (Pleurotus ostreatus) powder on productive and carcass traits, humoral immune responses, and blood characteristics of Ross 308 male broiler chicks reared to 42 d of age in comparison with a prebiotic supplement. Two hundred and forty, day-old male broiler chicks (Ross 308) were randomly assigned to one of four treatments with four replicates of 15 chicks based on a completely randomized design. The dietary treatments consisted of the basal diet as control, prebiotic group receiving 1 g/kg A-Max (Mannan-oligosaccharides), 10, and 20 g/kg oyster mushroom powder added to the basal diet. The obtained results showed that inclusion of 20 g/kg mushroom powder significantly improved body weight over the starter and grower (P<0.05) while feed efficiency was improved only over the starter (P<0.05) period compared to the control group. Considering the entire experimental period, (1-42 d) birds receiving prebiotic supplemented diets exhibited the highest body weight and lowest feed conversion ratio relative to the other treatments (P<0.05). Carcass yield and internal organs relative weights were not influenced by dietary treatments, but prebiotic supplementation significantly (P<0.05) decreased abdominal fat pad compared to the control group. Newcastle, influenza and sheep red blood cell antibody responses of chicks did not differ significantly at either level of inclusion of supplements. Chicks fed supplemented diets had the lowest serum triglyceride concentration at 42 day (P<0.05) compared to the control chicks, but other biochemical and hematological values tested including protein, albumin, globulin, high-density lipoprotein, low-density lipoprotein, and total cholesterol, red blood cell, white blood cell, hemoglobin and hematocrit were not markedly affected by treatments. In conclusion the obtained results indicated that oyster mushroom powder at an inclusion level of 20 g/kg of diet had favorable effects on performance criteria of chicks reared to 28 day of age while, prebiotic supplementation revealed its beneficial impact on chicks productive traits at slaughter age, besides reducing carcass abdominal fat and serum triglyceride concentration at 42 day.