Detection of Mycoplasma bovis in preservative-treated field milk samples

Control of mycoplasmal mastitis requires individual cow milk sampling for c ulture and identification of Mycoplasma bovis. This sampling is time-consum ing and expensive. Currently, some herds sample cows monthly with the dairy herd improvement (DHI) program, but a preservative is added to this milk t hat kills M. bovis. In this paper, a nested polymerase chain reaction (PCR) procedure that allows for rapid testing of preservative-treated milk is va lidated. The specificity of the nested PCR assay was confirmed by testing i solated nucleic acids of other organisms phylogenetically related to M. bov is or common to milk. A comparison against blind-passage culture on 53 fiel d milk samples determined its sensitivity. Exposure of seeded milk samples to the procedure resulted in a sensitivity of 5.1 cfu equivalents per milli liter. Analysis of these results proved that the nested PCR assay was as se nsitive as traditional culture and can be used on preservative-treated milk .