Humoral immunity assessment in calves born to cows immunized with inactivated vaccine for Bovine Herpesvirus 1 and Bovine Viral Diarrhea Virus

ABSTRACT

Background: Considering that calves are immunologically immature at birth, maternal vaccination at the precalving period has been used as an alternative approach to increase the antibody titers in the colostrum, providing better immunological assistance to neonates. This study aimed to evaluate the influence of maternal immunization with inactivated vaccine for Bovine Herpesvirus type I (BoHV-1) and Bovine Viral Diarrhea virus (BVDV) at the precalving period on the transfer of passive immunity to calves.Material, Methods & Results: Eleven pregnant cows were divided into non-vaccinated (C, control; n = 4) and vaccinated (VAC; n = 7) groups. The vaccinated cows were seronegative for BVDV, but two animals of the control group presented titers for BoHV-1 due to natural exposure. The immunization was performed at 60 and 30 days precalving by using a commercially available vaccine from Argentine that consisted of inactivated strains of BVDV-1, BVDV-2, and BoHV-1. Calves were fed 4 L of colostrum in the first 12 h after birth. Colostrum and blood samples were collected from calves before (T0) and after colostrum feeding up to 15th day (T1-T6). Specific antibodies (ABs) in the colostrum and serum were detected using serum neutralization (SN) test. At T0, AB titers for BVDV and BoHV-1 were not detected in the blood serum of calves. Only one cow from the VAC group had ABs for BVDV...