Serological response of turkey hens to vaccination with Salmonella hadar and its effect on their subsequently challenged embryos and poults.

An inactivated Salmonella hadar vaccine was administered to parent turkey stock and the progeny were subjected to challenge with S hadar. There was some evidence that eggs from vaccinated birds were more resistant to growth of the organism. When compared with similarly infected poults from unvaccinated parents, a markedly different serological picture and pattern of salmonella excretion was seen. It appeared that the passive immunity induced by the vaccine encouraged the faster establishment of other gut Enterobacteriacae, even in the presence of large numbers of S hadar.