Experimental design and basal diet: A total of 198 day old broiler chicks of “Hubbard Isa Starbro” strain were purchased from Kazi Farms Ltd., Dhaka, Bangladesh. The birds were randomly assigned to six groups as T1 (Control group-no antibiotics or probiotics), T2 (antibiotics fed group), T3 (GuardizenM probiotics fed group), T4 (Protexin Boost probiotics fed group) and T5 (Poultry star sol probiotics fed group) each consisting of 33 chickens in which 11 in each replication (3 replications in each group) and were reared in well partitioned area in a room under strict hygienic condition in the experimental poultry shed in the Faculty of Animal Science & Veterinary Medicine, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh. The experimental groups were fed with commercial ration, but the group T2 supplemented with antibiotics (2.5ml Ciprocin vet® from Square Pharmaceuticals Ltd. whose generic name is Cirofloxacin Hydrochloride USP/5 litre water) and T3, T4 and T5 were fed with commercial ration plus 2.5 g of different probiotics [Guardizen-M, Dong Bang Co. Ltd., Korea which contains Lactobacillus plantarum, L. bulgaricus, L. casei, L. acidophilus, Bifidobacterium bifidum, Streptococcus thermophilus, S. faecium, Aspergillus oryzae and Torulopsis bovina; Protexin Boost, manufacturer Protoxin Animal Health and marketed by Elanco (Bangladesh) Ltd.; Poultry star sol, manufacturer Biomin and marketed by Renata Ltd., Animal Health Division]/5 L drinking water up to 4th week of age. It is worth to mention that no any antibiotic was supplemented to or injected in the broilers from the first day until the end of the experiment whose were selected for probiotics based. The basal diet was formulated to meet or exceed nutrients recommended by the NRC (1994) for broiler chickens based on soybean meal and corn (without supplementing antibiotics, coccidiostats or growth promoters). Chemical composition of feed ingredients and experimental diets for dry matter (DM), crude protein (CP), crude fiber (CF) and crude fat (EE) were determined by AOAC, 1990), whereas starter and finisher diet contained 94% and 93% DM, 22% and 20% CP, and 3000 kcal/kg and 3100kcal/kg ME, respectively. 1Trace mineral mixture provides in milligrams per kg of diet: Mn, 70; Zn, 50; Fe, 30; Cu, 5, Se, 0.3.; 2 Vitamin mixture provides per kg of diet: vitamin A 8000 IU; cholecalciferol 1000 IU; riboflavin 5 mg/kg; niacin 40 mg/kg; thiamin 2 mg/kg; folic acid 0.6 mg/kg; vitamin B12 15 μg/kg.; 3Calculated by AOAC (1990). Vaccination schedule for newcastle and gumboro diseases was maintained properly according the recommended manual of Hubbard Isa Starbro strain. Growth performance and mortality: Measurements of broiler performance including body weight, daily weight gain, daily feed consumption and mortality rate were determined. All birds in each group were weighed individually at hatch, 1, 2, 3 and 4 weeks of age. Daily weight gains were then calculated for the periods: day old, 1, 2, 3 and 4 weeks. The feed offered to each room was recorded daily with an automatic weighing machine. At the end of each week feed residues were weighed, feed consumption was therefore recorded on a weekly basis and then calculated as feed consumed per day over the periods: day-old, 1, 2, 3 and 4 weeks. The feed conversion ratios could then be calculated for the time periods of 1st, 2nd, 3rd, and 4th weeks. The feed conversion ratio is feed consumed/weight gain. Mortality rate was weekly determined as a cumulative percentage. Statistical analysis: All data were analyzed using the One-Way analysis of variance using GLM procedure (SAS Institute Inc., 2003). Significant differences among treatments were identified at 5% level (P<0.05) by Duncan’s multiple range tests (Duncan, 1955).