Is Mycoplasma Still Out There on California Dairies?
In a recent retrospective study of the bulk tank milk samples cultured for mycoplasma from a central California creamery over the period of 1989 through 1995, the yearly percentage of mycoplasma-positive bulk tank samples for all species of mycoplasma ranged from 1.8% to 5.8%. When the non-pathogenic mycoplasma were removed, the yearly percentage mycoplasma positive bulk tank samples was between 1.2% and 3.1% for the study period. The bulk tank milk samples were cultured using direct plating at the creamery and were speciated at the Veterinary Medical Teaching and Research Center, Milk Quality Laboratory. Considering only incident cases (the first cases or the next case when over a year had gone by since the first case for a given species), only one species of mycoplasma was isolated from 74% of the dairies having a positive case. Nearly 20% of the positive dairies had 2 species of mycoplasma isolated as incident cases. The extreme was a dairy which had 6 different mycoplasma species i
