An In Vivo and In Vitro Trial on Layer Chicken Breed Susceptibility and Yolk Sac Infection to Escherichia Coli and Evaluation of the Immune Response in Bishoftu Poultry Farms, Central Ethiopia

Chicken colibacillosis is a bacterial disease of great concern in the layer industry causing substantial animal and economic losses worldwide. Yolk sac infection of chicks which result in high mortality in the first week of age. A challenge test was carried out to evaluate the susceptibility of three chicken breeds to E. coli pathogenic strain. Thus, a total of 48 day-old Horo, Fayoumi and Koekoek chicken breeds were allotted into the treatment and Control groups Containing 8 birds each. An experimental infection with E. coli pathogenic strain was given (104c.f.u/0.1 ml) intra yolk sac to treatment group on day-one of experiment, while the control group was kept as non-injected. The studied parameters involved examination of yolk sac weight, yolk sac, and body weight ratio and antibody titer against Newcastle disease virus (NDV). The study revealed that there was no statistically significant difference between Horo, Fayomi and Koekoek breeds in infection. However, intra yolk infection with E. coli pathogenic strain result in gross pathological change of the yolk sac, increased yolk sac body weight ratio, increased yolk sac weight and the transfer of maternal immunity in serum was not changed. In conclusion local and exotic breeds of chickens are highly susceptible to E. coli. Therefore, vaccination and therapeutic treatment should be properly used and supplementary management practices should be adopted in the farm.