Use of a Staphylococcus aureus vaccine to reduce prevalence of staphylococcal mastitis and lower somatic cell counts in a registered Saanen dairy goat herd

The purpose of this investigation was to evaluate the efficacy of a commercial bacterin (Lysigin ® ) in reducing the prevalence of staphylococcal intramammary infections (IMI) and lowering somatic cell counts (SCC) in a commercial dairy goat herd. Does were sampled over a 4-month period prior to vaccination to establish a baseline for the prevalence of mastitis, SCC, and bulk tank bacteria count. All does were vaccinated, and the levels of mastitis and SCC were monitored at 4-week intervals over a 6-month period. The average IMI prevalence over the 4 months prior to vaccination was 77.0%, and Staphylococcus caprae, S. xylosus, S. simulans, and S. capitis were the predominant causes of IMI. Following vaccination, culture results revealed that although the distribution of isolates had not changed, the average prevalence of infection decreased to 63.9%. Likewise, the average number of mastitic udder halves per doe decreased from 1.2 prior to vaccination to 0.91 postvaccination. The average bulk tank SCC decreased from 1,118,625/ml during the prevaccination period to 886,600/ml during the postvaccination period, and the average bulk tank bacteria count decreased from 14,900 to 6,200/ml. Data analysis suggested that herd vaccination led to a short-term reduction in the overall prevalence of mastitis, which was supported by the reduction in the bulk tank SCC and bacteria count. Results support the continued study of vaccination for managing staphylococcal mastitis and SCC in dairy goats in lieu of antibiotics.