Despite all technology and safety standards in place, a minute portion of the 16-million gallons of milk consumed every day in the U.S. contains a nasty bacterium linked to Johne's disease in cattle – even after normal pasteurization. And that "bug" may have a possible link to Crohn's disease in humans.
That's one reason why USDA recently added another $500,000 grant to build on results of a $2.5 million research effort underway since 2009, according to Ynte Schukken, lead investigator for Cornell University's College of Veterinary Medicine. Unfortunately, the Mycobacterium avium subspecies of paratuberculosis, MAP for short, requires about four years to show clinical signs, explains the dairy herd health expert.
During those four years, dairy cows typically produce thousands of gallons of milk headed for store shelves. . "A high percentage of U.S. dairy farms have MAP-infected cattle, so reducing viable MAP in raw and pasteurized milk is important," he adds. The disease costs the dairy industry up to $250 million in annual losses.
Numerous studies show MAP can survive high temperature/short time pasteurization used for most fresh milk. "That raises human health concerns, especially due to the widespread nature of MAP in dairy herds," he points out. "I'm not sure about survival in ultra-high temperature processed milk."
Next crucial phase
With cross-sectional DNA from four generations of cows and bacteria in 300 dairy herds plus data from two known MAP-infected herds, the scientists feel they're closing in on designing a sustainable MAP-free management program. The project involves researchers from Cornell, Penn State University, University of Pennsylvania and University of Maryland.
The scientists are closing in on the use of a current test used to identify MAP; focusing on the relationship between management practices and MAP contamination of milk. They're developing risk assessment models that predict MAP contamination. They already have designed models for keeping herds MAP-free.
"We have the potential to unravel the mysteries of Johne's disease," says Schukken, "and provide dairy farmers with the tools needed to produce milk that's free of MAP bacteria."