Means of serum HP concentration for treatment group by date. Serum Hp concentration in micrograms/mL over time by treatment group. Treatment group 0: Negative control group, Treatment group 1: leukotoxin negative B. trehalosi group, Treatment group 2: leukotoxin positive B. trehalosi group, Treatment group 3: M. haemolytica group, Treatment group 4: Combination of leukotoxin negative B. trehalosi and M. haemolytica group. Circles above trend lines indicate significant differences from other treatment groups. Triangles below trend lines indicate significant differences from prior bleeding dates.