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New research demonstrates how on-farm milk testing with polymerase chain reaction (PCR) technology that detects specific DNA fragments outperforms traditional on-farm microbiological culture testing. The results open new horizons for dairy producers to quickly detect Mycoplasma bovis DNA and take appropriate actions to control mastitis and get cows back to the milking string sooner.
“The quick, accurate diagnosis of mastitis-causing pathogens is critically important to mastitis control,” says Dr. Roger Saltman, a consultant with Acumen Detection and former chief medical officer of U.S. cattle and equine at Zoetis. “With the sensitivity and speed of the Acu-PCR test, producers can identify DNA from Mycoplasma bovis in 3 hours compared to 7 to 14 days for conventional culture tests.”
The study used a large number of raw milk samples with specific, known concentrations of M. bovis added. Each sample was processed using the Acu-POLARIS interface, Milk Lysis Prep Reagent and MYCOB™ PCR reagent designed by Acumen Detection. After inoculation the culture plates were incubated and observed for the presence of mycoplasma colonies at 3,7 and 14 days.
The sensitivity of PCR testing was 98 percent with specificity at 100 percent for the detection of Mycoplasma bovis DNA oligonucleotides. At the same concentration, microbiologic culture yielded 52 percent sensitivity at seven days of incubation and 68 percent sensitivity at 14 days of incubation. With regard to non-M. bovis species, specificity from PCR testing was still 100 percent while conventional culture was not able to determine some of the species.
“Technology is rapidly advancing making some of the historical forms of pathogen detection obsolete,” says Dr. Saltman. “With our PCR testing platform, we have much higher accuracy at a fraction of the time.”
A quick diagnosis of subclinical and clinical mastitis cases is most important after freshening and through about 45 days in milk. This period, along with the period around dry off, are the two critical times when cows are most challenged by mastitis-causing pathogens. On-farm tests using PCR technology can help speed up the process to identify the presence of potential mastitis-causing pathogens at dry off, at freshening or at any point during the lactation. Knowing results faster helps producers be more proactive at addressing mastitis incidents and getting cows back into the milking string sooner.
