The titre of bactericidal antibody against Salmonella gallinarum in chicks.

Using a bactericidal assay for the presence of antibody it was found that 1-day-old chicks had little natural antibody against Salmonella gallinarum. However, in contrast adult hens possessed relatively higher levels. The titre of antibody could not be increased in chicks by prior immunization at the time of hatching. These results are in conflict with those recently reported by Solomon (1968a).