The Relationship of Pathogenicity to the Growth of Pasteurella multocida Serotype 3,4 Isolates in Normal Turkey Plasma

The percent mortality (M%) caused by various isolates of Pasteurella multocida serotypes 3,4 in turkeys challenged with these organisms was significantly associated with the growth curve when these organisms were grown in normal turkey plasma. The organisms that lysed the most caused the least mortality. In turn, the longer it took for an organism to reach the lowest point on its growth curve, the lower the M%. The highest point on the growth curve and the time that it took to reach that point were analyzed in normal and heat-treated plasma (HTP). The isolates with the maximum growth had the highest M%. The isolates that reached their maximum growth faster also had the greatest M%.