Efficacy of combined mild, live IBD [infectious bursal diseases] vaccine and antibiotic flortenicol in cobb broiler chicks (Gallus gallus domesticus Linn.)

Infectious bursal disease (IBD) is a constant problem to the Philippine commercial poultry industry, being highly contagious and immunosuppressive. There is a need to effectively control IBD without causing immunosuppression and at the same time reduce the early bacterial infection. This study was initiated to determine the efficacy of combined mild, live IBD vaccine and antibiotics florfenicol using the parameters: effect to the intestinal E. coli, coliforms and vaccine virus titer using embryonatedmeggs, immunogenicity by seroconversion, and pathogenicity using bursa to body weight index. Two hundred day-old Cobb broiler chicks with high maternal (MDA) against IBD were divided into four groups. Using the subcutaneous route, Group A was vaccinated with combined antibiotic and IBD vaccine; Group B with IBD vaccine; and Group C with florfenicol. Group D was the negative control. At 24 hours post treatment, Group C Counts for significant ly (P less than or equal to 0.05) lower than those for group D, suggesting the effect of florfenicol on E. coli, total coliforms, and total bacterial counts. The low values for Groups A and B could be an effect of the antibiotic incorporated in the IBD vaccine, used as common treatment for both groups. After 48 hours post treatment, the decrease in E. coli and total coliforms count could probably be explained by the presence of antimicrobials in commercial feed. The constant total coliform mean value of Group D at 24 and 48 hours may be attributed to favorable gut conditions, antibiotic resistance or microbial competition. The continuous decline of antibodies for both vaccinated and non vaccinated groups, showed that the birds did not exhibit seroconversion to IBD vaccination with or without florfenicol. The mild IBD vaccine did not break through high maternally-derived antibodies and thus elicited no immune response. No bursal atrophy as demonstrated by the bursa to body w e ight index. EID50 titer determination of IBD vaccine alone and IBD vaccine combined with florfenicol had no significant differences despite low EID50 titers.