A bacterin against fowl cholera in turkeys: protective quality of various preparations originated from broth cultures.

Bacterins prepared from broth cultures of Pasteurella multocida were studied for their immunogenicity against fowl cholera in turkeys. The various preparations differed in culture medium, method of inactivation, and adjuvants added. Eight-to-twelve-week-old turkeys were inoculated subcutaneously with each preparation. After challenge with a live culture of the homologous strain, protection was significantly better from a broth bacterin grown in brain-heart infusion broth, concentrated tenfold, inactivated with formalin, and emulsified in incomplete Freund's adjuvant than in controls (unvaccinated birds and birds receiving commercial products). In two separate trials, protection was 86% from the bacterin and 21 and 14% from a commercial product (P less than 0.05 and P less than 0.01, respectively). The broth bacterin could be prepared on a large scale at minimum labor and therefore might be suitable for commercial production.