Determination of serologic and colostral response in late-gestation cows vaccinated with a Mycoplasma bovis bacterin

To determine whether vaccinating cows during late gestation against Mycoplasma bovis will result in adequate concentrations of M bovis-specific IgG(1) in serum, colostrum, and milk. 78 dairy cows. Serum samples were obtained 60 and 39 days prior to expected parturition in vaccinated and control cows from a single herd. Serum and colostrum samples were also obtained at parturition. Milk samples were obtained 7 to 14 days after parturition. Samples were analyzed for anti-M bovis IgG(1) concentrations. Prior to vaccination, control and vaccinated cows had similar anti-M bovis IgG(1) concentrations. After initial vaccination and subsequent booster and at parturition, there was a significant difference between the 2 groups, with vaccinated cows having higher IgG concentrations. Colostrum from vaccinated cows had higher anti-M bovis IgG(1) concentrations, compared with control cows; however, IgG(1) concentrations in milk did not differ between the 2 groups. Vaccination of late-gestation cows resulted in increased concentrations of anti-M bovis IgG(1) in colostrum. However, ingestion of colostrum by calves may not guarantee protection against M bovis infection.