author(s)
PH Murade, MM Kadam, AR Patil and KK Khose

abstract
The experiment was conducted on 360 day-old straight run Vencobb broiler chicks for a period of 42 days. The chicks were randomly distributed into six treatment groups A, B, C, D, E and F having 4 replicates of 15 birds in each. The group A was maintained as a control group without any treatment; feeding of competitive exclusion culture by beak dipping method on first day of age at hatchery level (B); feeding of CE by beak dipping on the first day of age on farm arrival i.e. approx. 12 hr after hatch (C); birds challenged with pathogenic Escherichia coli strain after 72 hr of hatch without any feeding of CE (D); birds fed with CE culture on the first day by beak dipping at hatchery level and challenged with pathogenic E. coli after 72 hr hatch (E); birds fed with CE culture on first day after farm arrival (i.e. Approx. 12 hr after hatch) and challenged with pathogenic E. coli after 72 hr hatch (F). All the birds placed under treatment D, E and F was challenged (orally) with pathogenic E. coli @ 1.0x10⁵ colony-forming units per chick. The live body weight and weight gain was significantly (P<0.01) higher in treatment group B as compared to groups A, C, D and F at the end of 42 days. The feed intake was significantly (P<0.01) higher in treatment group B as compared to control group. The feed conversion ratio was significantly (P<0.01) improved in group B as compared to groups A and D. However, significantly poor FCR was recorded in treatment group D birds challenged with E. coli as compared to all other groups. Overall the higher percentage of mortality was observed in treatment group D due to E. coli infection. The net profit rupees per kg live weight in treatment groups A to F was Rs. 7.62, 11.31, 9.95, 1.37, 10.27 and 9.10, respectively. Based on the results of the present experiment, the feeding of competitive exclusion culture at hatchery and farm level with or without E. coli challenged birds showed better growth performance and economic returns in broilers. Thus, it is concluded that the feeding of competitive exclusion culture @ 12.5 g/1000 chicks by beak dipping method at hatchery level were benefited in term of achieving highest live body weights, better feed conversion ratio, maximum liveability and a good amount of net profit returns in broilers.