New blood testing method could enable early detection of Johne’s disease in calves

Researchers at the Royal Veterinary College discover that blood samples from newborn calves may reveal early exposure to Johne’s disease, potentially improving detection and management of the costly infection.

Researchers at the Royal Veterinary College say blood taken from newborn calves may offer an early clue to exposure to Johne’s disease, a chronic infection that is costly to dairy herds and notoriously difficult to detect in its earliest stages.

In work published in Animals, the team examined blood from 38 dairy calves and their dams on a commercial farm in south-west England. The samples had first been collected for routine checks on whether calves had absorbed enough antibodies from colostrum. The researchers then looked for antibodies specific to Mycobacterium avium subspecies paratuberculosis, the bacterium linked to Johne’s disease, in the leftover serum.

Calves born to cows carrying MAP antibodies were found to have higher levels of MAP-specific antibodies than calves whose mothers tested negative. The relationship between calf antibody levels and colostrum transfer also appeared to differ depending on whether the dam was seropositive or seronegative.

The findings add to earlier research showing that serological testing can pick up immune responses in young calves, while diagnostic references note that Johne’s disease remains hard to identify before clinical signs emerge. Jonathan Hedgecock, the study’s lead author, said the approach could be practical because many calves are already blood sampled at a young age for other reasons. He added: “Continued research into new testing strategies for Johne’s disease is important with more work still needed.”

Reference: Hedgecock, J.; Plate, P.; Winden, S.v. Neonatal Calf Serum MAP Antibody Titre as a Potential Marker of Early-Life MAP Exposure. Animals 2026, 16, 1963.
https://doi.org/10.3390/ani16131963