اثرات پری‌بیوتیک، پروبیوتیک و مخلوط آن ها بر عملکرد، پاسخ ایمنی و فلور میکروبی دستگاه گوارش جوجه های گوشتی

     In order to investigate the effects of probiotic, prebiotic and a mixture of these feed additives (at different ratio) on the performance, immunity response and cecal microflora of broiler chickens, in a complete random design, a total of 360 ond-day-old broiler chicks (Cobb 500) were randomly distributed among 6 experimental treatments with four replicates. Experimental treatments (diets) were: 1- a basal diet without any additive, as control (Ctrl) 2- basal diet added with prebiotic (Pre) 3- basal diet added with probiotic (Pro) 4- basal diet added with a mixture of probiotic and prebiotic at ratio of 1:1 (M1), 5- basal diet added with a mixture of probiotic and prebiotic at ratio of 2:1 (M2), 6- basal diet added with a mixture of probiotic and prebiotic at ratio of 1:2 (M3). Probiotic and prebiotic were added to diets in amounts as recommended by producer. During 42 d rearing period, birds were fed starter and grower diets form 1 to 21 and 22 to 42 days of age, respectively. Performance traits were measured weekly. On d 21 and 42, one bird from each replicate pen, was slaughtered and cecal content was collected, under sterile condition, to determine the E. coli and Lactobacillus count. In addition, immunity respose to SRBC was measured at the end of the experiment. Data were subjected to one way analysis of variance, by SAS sotware. The results indicated that in the starter phase, birds fed diets M1 or M3 achieved more gain compared to the control group (P<0.05). At the same time, feeding with M1 diet resulted in a better FCR than the control group (P<0.05). Significant differences were not observed for performance traits in the finisher phase or whole period (1-42 d of age) of the experiment. All supplemented diets had more total antibody titer against SRBC compared to the control group, at the end of the experiment (P<0.05). Also, IgM titer was higher in all supplemented treatments (except for Pre) relative to the control group (P<0.05). On d 21, lactobacillus number was higher in Pre, M1 and M3 treatments than the control (P<0.05). Also, at the end of the experiment, all supplemented tretments (except for Pre) had higher count of lactobasillus compared to the control group (P<0.05). On d 21, E. coli count was significantly not influenced by experimental treatments, but significant reductions in E. coli content were observed for Pre and M1 treatments compared to the control group at 42 d of age (P<0.05).