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

Objective - To determine whether vaccinating cows during late gestation against Mycoplasma bovis will result in adequate concentrations of M bovis-specific lgG₁ in serum, colostrum, and milk. Animals - 78 dairy cows. Procedures - 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 lgG₁ concentrations. Results - Prior to vaccination, control and vaccinated cows had similar anti-M bovis lgG₁ concentrations. After initial vaccination and subsequent booster and at parturition, there was a significant difference between the 2 groups, with vaccinated cows having higher lgG concentrations. Colostrum from vaccinated cows had higher anti-M bovis lgG₁ concentrations, compared with control cows; however, lgG₁ concentrations in milk did not differ between the 2 groups. Conclusions and Clinical Relevance - Vaccination of late-gestation cows resulted in increased concentrations of anti-M bovis lgG₁ in colostrum. However ingestion of colostrum by calves may not guarantee protection against M bovis infection.