Maternally and Naturally Acquired Antibodies to Histophilus somni in Japanese Black Calves

Abstract

We investigated the sequential changes of serum antibody titers against Histophilus somni in Japanese Black calves. Thirty-six unvaccinated calves from three Japanese Black breeding farms in Japan were studied. Blood samples were obtained from all calves at 1, 4, 8, 12, 16 and 20 weeks after birth. As a result, antibody titers against H. somni in calves decreased by 4 weeks of age, followed by a gradual increase during the study period in three groups. The antibody titers against H. somni at 4 weeks of age were significantly lower than those at 12, 16 and 20 weeks of age at Farm A and B, and at 20 weeks of age at Farm C (P＜0.05). These results might provide useful information for designing a vaccination program to prevent H. somni in Japanese Black calves.