Figure 3: Mean ± SEM serum IgG2 titers in 22 BLV-positive cows (BLV POS) and 13 BLV-negative cows (BLV NEG) administered a J5 E. coli bacterin with 4 doses of bacterin administered SC in the left side of the neck (odd-numbered doses) or right side of the neck (even-numbered doses). Blood samples were collected from all cows at the time of the first (V1: approx 7 weeks before parturition), third (V3: second week after parturition (between days 8 and 14 after parturition)), fourth (V4: 5 weeks (between 29 and 35 days) after parturition) vaccinations, and 21 days after the fourth vaccination. *Within a time point, mean values for groups differ significantly ( ).