Evaluating the Efficacy of Commercial Escherichia coli Killed Vaccine in Broiler Chickens

Abstract

Escherichia coli infections cause significant financial losses for the worldwide chicken economy, so this research is being conducted to evaluate the efficacy of the inactivated multivalent Escherichia coli vaccine. Six groups were created from a total of 120 broiler chicks; the groups (1 and 3) were received E. coli inactivated vaccine at day 7 and challenged with O78 and O128 respectively, groups 2 and 4 were referred to as the control of challenge for the Escherichia coli strains O78 and O128. Groups 5 and 6 were maintained as the non-vaccinated and non-challenged control negative group and vaccinated non challenged group respectively. Challenged with E. coli strains of heterologous O128 and homologous O78 were given at 28 days old broilers by injection into the muscle of the thigh with 0.2ml contained 10⁷ CFU / bird. Moreover, the performance measurements of body weight per gram, feed intake and feed conversion ratio were measured; histopathological findings, clinical symptoms, rate of mortality and total intestinal counts of Escherichia coli were also examined. The study revealed that the vaccination of COLI-VACâ„¢ E. coli provided a significant defense against the challenge between homologous O78 strain and heterologous O128 strain. Just used the aforementioned parameters, Groups 1 and 3 that vaccinated at seven days old and challenged at 28 days old chicks with homologous and heterologous (O78 and O128) serotypes of E. coli provided impressive protection against all those non-vaccinated chicks (Groups 2 and 4) that were challenged with O78 and O128 serotypes of E. coli.