Deer farmers have another tool in the battle with Johne's.
Until now, owners of deer infected with abnormal lesions have not been advised of the fact.
But research has shown that deer infected with Mycobacterium avium sub-species paratuberculosis (Map), the bacteria which cause Johne's, can develop lesioned lymph nodes without the signs of Johne's.
The manager of Johne's Management Ltd, Dan Lynch, said this additional information would now be passed on to farmers so they can use it to make management decisions.
"By itself, it is not definitive, but we are capturing information not previously captured for farmers," he said.
Mr Lynch said meat inspectors had proven to be expert in detecting Map lesions and it was a case of giving that information to farmers.
Johne's is an acute disease in young animals, but the only way of accurately detecting it was by culturing it.
Mr Lynch said the information would be confidential, with the first letters to farmers posted in mid-May.
He suggested farmers and their vets use the information to look at management options.
He also suggested using techniques to determine if Map or Johne's was an issue in their herd.
Deer Industry New Zealand and Massey University have validated the programme.
Mr Lynch said a study by Massey last year found that over 94% of 129 lesioned lymph nodes taken from 76 deer herds were Map infections.