Effectiveness of the RB51 vaccine in controlling brucellosis in adult beef cows.

Introduction: The aim of this study was to compare the effectiveness of brucellosis control and reproductive performance using one or two doses of RB51 strain vaccine.

Methods: This experiment was conducted at two commercial beef farms (A,  = 477; and B,  = 673), which were selected due to their records of endemic brucellosis and a prevalence of 6 to 8% of seropositive cows. An initial serology screening (Day 0) was carried out in all cows using the Rose Bengal test (RB), and presumptive positive results were re-evaluated using a slow agglutination test with 2-mercaptoethanol (2-ME).