Evidence-based effectiveness of vaccination against Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni in feedlot cattle for mitigating the incidence and effect of bovine respiratory disease complex.

Bovine respiratory disease complex is the leading cause of morbidity and mortality in feedlot cattle. A number of vaccines against bacterial respiratory pathogens are commercially available and researchers have studied their impact on morbidity, mortality, and other disease outcome measures in feedlot cattle. A systematic review will provide veterinarians with a rigorous and transparent evaluation of the published literature to estimate the extent of vaccine effect. Unfortunately, the published body of evidence does not provide a consistent estimate of the direction and magnitude of effectiveness in feedlot cattle vaccination against Mannheimia haemolytica, Pasteurella multocida, or Histophilus somni.