AbstractIntroductionThe objective of this research was to evaluate the antibody response to multiple doses of an inactivated mixed vaccine against Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica, and to investigate the influence of age at time of vaccination in the field.Material and MethodsHealthy female Holstein calves received the vaccine at the age of 5–12 days and 2, 3, or 4 weeks later in the first experiment or at 1, 2, or 3 weeks of age and 4 weeks later in the second. Blood samples were collected at each vaccination and 3 weeks after the booster dose. Based on the antibody titres after the vaccinations, calves were divided into positive and negative groups for each of the bacteria. Calves in the control group were vaccinated only once at the age of 19–26 days.ResultsAntibody titres against H. somni and P. multocida were significantly increased by the booster. After the second vaccinations, the titres against each bacterium were higher than those of the control group, and the M. haemolytica-positive percentage in calves with high maternal antibody levels (MAL) exceeded that in calves with low MAL. In the first experiment, a majority of the M. haemolytica-positive calves tended to have received the primary dose at seven days of age or older.ConclusionA booster dose of the inactivated bacterial vaccine in young Holstein calves increased antibody production and overcame the maternal antibodies. Calves should be vaccinated first at seven days of age or older.

Introduction Bovine respiratory disease (BRD) is one of the primary causes of death in young calves. Vaccination against infection by the common bacteria causing BRD is possible; however, the physical condition of the young calves that enables antibody production when stimulated by early immunisation remains to be elucidated. Material and Methods Healthy young female Holstein calves on a commercial dairy farm were fed a colostrum replacer and administered primary and booster immunisations with an inactivated vaccine against the bacterial pneumonia agents Histophilus somni, Pasteurella multocida and Mannheimia haemolytica. At each immunisation, the body weight and height at the withers were measured and the body mass index (BMI) was calculated. Blood was sampled immediately before immunisation and 3 weeks following the booster. The calves were divided into positive and negative groups based on the antibody titre at the final blood sampling. Maternal antibody titres at the primary immunisation and BMI, nutritional status and oxidative stress at both immunisations were compared between the two groups. Results Antibody titre at the primary and BMI at both immunisations were significantly higher in the positive than in the negative group (P < 0.05). Additionally, serum gamma globulin was significantly higher in the positive group (P < 0.05), indicating a strong correlation between maternal antibody and serum gamma globulin levels. Conclusion Elevated maternal antibody titre and higher BMI are positive factors for successful early immunisation, for which suitable colostrum may also be fundamental in young calves administered inactivated vaccines.

Introduction Early vaccination of cattle with an inactivated commercial bacterial vaccine against bovine respiratory disease has been reported to increase antibody production and can alleviate the disease. However, its dosage has been little investigated in young Holstein calves. This study addresses the need to establish guide values for vaccine dosage in these animals. Material and Methods Healthy calves received an inactivated vaccine for Histophilus somni, Pasteurella multocida and Mannheimia haemolytica intramuscularly at the ages of 1 and 4 weeks. Administered vaccine doses were 1.0 mL for the primary and booster vaccinations (1.0 + 1.0 group), 0.5 mL for the primary and 1.0 mL for the booster vaccination (0.5 + 1.0 group), or 0.5 mL for both vaccinations (0.5 + 0.5 group). Results Differences in the vaccine responses between the 1.0 + 1.0 group and 0.5 + 1.0 group were minor. However, the number of calves with a positive vaccine response to H. somni in the 0.5 + 0.5 group was less than half of that in the 1.0 + 1.0 and 0.5 + 1.0 groups. In logistic regression analysis, although the booster vaccination dose was positively correlated with seropositivity for H. somni, the primary vaccination dose was not correlated with vaccine response. The number of calves with positive vaccine responses to M. haemolytica was low even after booster vaccination regardless of the dose. Conclusions The dose of 0.5 mL can be used for primary vaccinations in newborn Holstein calves, but 1.0 mL may be required for booster vaccinations.