Field observations with Salmonella enteritidis bacterins

A study involving II commercial layer flocks was conducted to determine the efficacy of Salmonella enteritidis bacterins (autogenous or federally lice nsed). The criterion for evaluation of vaccine efficacy was the presence or absence of S. enteritidis in the environment, the organs of the bird (incl uding ovary and oviduct), and eggs. Environmental, rodent, and organ specim ens from dead birds as well as eggs were cultured throughout the life of th e flock All layers were obtained from pullet sources that were negative for S. enteritidis, as determined by organ and environmental cultures. Despite the use of S, enteritidis vaccination, 63.6% of the houses had S. enteriti dis-positive environmental cultures and 100% of the hocks had S. enteritidi s organ-culture-positive birds. The range of positive cultures for S. enter itidis in the environment in vaccinated flocks was between 0 and 45.5%. Bir ds in vaccinated flocks were organ-culture positive for S. entericidis betw een 10% and 40% of the time. The unvaccinated portion of flocks in the same house and the unvaccinated flock in a complex had similar results compared with the vaccinated portion of the flocks.