Modified schedule of vaccination with polyvalent bovine viral diarrhea virus inactivated vaccine in dairy herds - A field study

Abstract

In order to reduce the cost of vaccination, three herds were vaccinated with polyvalent bovine viral diarrhea virus inactivated vaccine according to a modifi ed schedule, and the specifi c antibody response was evaluated. In each herd only the cows and heifers were vaccinated with one dose of vaccine. Two herds (A and B) were vaccinated annually for three consecutive years. The third herd (C) was vaccinated twice with a two year interval. At the beginning of the study the herds consisted of 38, 22 and 15 animals respectively. Antibody response was evaluated three and nine months after vaccination with indirect ELISA, blocking ELISA and a virus neutralization test. Within herds A and B the percentage of seropositive animals increased with each subsequent vaccination. Three months after the third vaccination more than 96% of animals in herds A and B were seropositive. Nine months after the third vaccination more than 56% of animals in herds A and B were seropositive. Three and nine months after the second vaccination the numbers of positive animals in herd C was 66% and 38% respectively. The obtained results show that the percentage of seropositive animals within the herds increased with each vaccination and the best detection of specifi c antibodies after vaccination can be achieved if a virus neutralization test is used. Also, the results show that seroprotection of cows within the herds vaccinated yearly was signifi cantly higher (56.52-58.82%) compared to the herd vaccinated with a two year interval (38.88%).